The invention is 80 years ahead of his time.

Six years later, in 1888, Didenko Slavyanov proposed a method of welding consumable electrode, and the era of welding.

A hundred years later, UNESCO celebrated the anniversary of the discovery of the century.

Welding since its inception has always been pronounced progressive. In a short period of time since the invention of the metal compounds arc welding method of repair and replacement techniques become indispensable in a massive process connection materials in all major sectors of industry, energy, construction and housing and communal services.

Today, the range of application of welding technology stretches from underwater to outer space welding, welding of low alloy to high-alloy steels, welding of cast iron to nearly all non-ferrous metals and their alloys, as well as to welding of plastic and other nonmetallic materials.

Is it a difficult profession, it can be judged from the fact that the average peak form highly welder comes only to 30 years. After all, the quality of the work of welders, qualifications and professional experience depends largely on the quality and reliability of manufactured products and a variety of technical security facilities where there are welds.

Despite the rapid development and introduction of high technologies, the so-called human factor is still leading. After all, the main tools of the welder — hands and eyes.

Social goals of the contest are: the improvement of vocational training, the creation of incentives for staff working professions, as well as the promotion of the achievements in this area.

In addition, such events — a platform for dialogue of employees of different companies. Here the participants get to know each other, learn the peculiarities and specifics of work in the enterprises of the region, share the secrets of their professional skills.

How does the competition took place in Tver?

Tver Excavator Plant was filled with sparkling stars and stellar fusion welders.

The contest was held in two categories.

…Numerous sparks workplaces scattered in all directions, fiery arc connecting parts into a unified whole with the help of stitches. The ability to cope with an electric arc or a gas flame gives special entertainment activities welder and is always a sense of respect for the master and his profession.

The audience commented on the results is quite friendly: «Good lad. It is a pity that alarmed. «

Next, the workpiece is still hot, go to the visual and measuring control and ultrasonic inspection. Experienced members of the jury are already determined other defects: presence of long seams, craters, undercut, sagging, lack of fusion and so. N.

However, in the future we plan to organize, sponsor and hold similar competitions in different cities with a high concentration of industrial enterprises.

Oyashinsky factory fasteners

On issues of the magazine «Hardware» meets the General Director of «OZKI» Eugene O. Kazantsev

LLC «Oyashinsky fasteners plant» is one of the largest manufacturers of hardware in the Siberian region.

The company has formed a complete cycle of hardware production: press-forging, machining, cold heading, thread rolling, welding and others.

Oyashinsky fasteners factory was founded in the spring of 1961, he was a member of the All-Union Production Association «Soyuzmashnormal» and then called Oyashinsky plant normals. Construction of the plant was completed in 1976, since it was renamed Oyashinsky factory fasteners. In the future, an extended list of products. Since 1986 the plant mastered the production of a wide range of nails. After the collapse of the USSR and the All-Union Production Association, the company was transformed into JSC «Plant Oyashinsky fasteners.» In 2006, in connection with the change of ownership, the company was transformed into Ltd. «Oyashinsky factory of fasteners».

The geography of deliveries of our company covers the Altai and Krasnoyarsk, Omsk, Kemerovo, Tomsk region. In recent years the company’s clients are such organizations as the JSC «Novosibirsk Instrument Plant», JSC «Sibselmashkomplekt», JSC «Altai transformer plant» and others.

— Eugene O., please tell us how to position itself Oyashinsky factory fasteners hardware products on the market.

— I run the company since July 2006. During this time we managed to achieve great results: we have restored production facilities acquired and launched new equipment, had a major overhaul of machine tools. It was possible to assemble a team of highly qualified specialists with extensive experience in hardware production. Today we are one of the largest companies for the production of metal products in the Siberian region among our customers the largest industrial and commercial enterprises in the region.

— We have learned from the news that in June 2008 OZKI started manufacturing screws. Please tell us more about this industry.

— In March 2008, we were acquired by two semi-automatic lines for the production of screws for wood and plasterboard with a diameter of 6 mm. In June, they began to produce its first products. Performance of the two lines allows to produce 5-7 tons of screws per month.

— As far as we know, for the production of screws you run two Chinese specialized production lines. How do you assess the level of this technology?

— Of course, the state of the art of Chinese production is very high. It is small-sized, easy to use, requires fewer consumables, has high productivity. The acquisition of two lines — the first step to upgrade machinery equipment company.

— The market dictates the price of screws manufacturers from South-East Asia, and especially China. How do you assess their competitive opportunities in this market?

— Currently, manufacturers of China dictate prices for standard products, with delivery of hardware parties is at least two months in view of delivery and customs clearance of goods. In my opinion, to reduce dependence on Chinese producers need to focus on the production of non-standard screws that are currently in demand in our market. Tool shop of our company developed and produced special equipment for the production of the screw in accordance with the requirements of our customers. This fact significantly increases our competitiveness in this market segment.

— We heard that from the second quarter of this year your company completely abandoned the product packaging in wooden crates. What type of packaging used by you at the moment and how it affected the possibilities of realization of your products?

— Currently, we use cardboard boxes. The transition from wooden boxes to cardboard boxes will significantly reduce the cost of production and accelerate the process of packing and shipping. We conducted a survey of our customers, one of the questions was whether they are happy with the change of packaging. All customers clearly answered yes!

— If not a secret, what further steps to develop the plant you intend to take in order to strengthen its position in the hardware market?

— Now we are developing a large investment program. The company plans to open its galvanizing plant, expansion of existing production facilities, the maximum updating of machinery equipment, introduction of modern technologies and expanding the product range.

Hardware — a vocation

New metalware company in Yellow Waters

On issues of the magazine «Hardware» meets the CEO of a new steel cord and wire plant in Yellow Waters Yuri O. pepper.

Young metalware company started its work in Yellow Waters Dnipropetrovsk region in Ukraine. The ideological leader of the creation of modern hardware production in the non-core businesses was Oleg Peppers — professional metiznik running a manager to «Dneprometiz» and is its co-owner. Today, his work he gradually passes son — Yuriy Olegovich Pertseva. Perhaps innovations in the hardware industry — a vocation Pertseva family.

Editors of the magazine «Hardware»

— Yuri O., the press has reported the discovery of a new hardware plant in the town of Yellow Waters Dnipropetrovsk region. You are the CEO of the new company, and the first question is why hardware plant, not the food or, for example, machine-building? What criteria form the basis of this decision?

— Have sight of such an experienced player in the market, this superb metiznika not take advantage of the situation and it would be illogical. You’re right in the examples: there are now many sectors of the economy that are on the rise, is no exception and the market metal, which at that time had to agitate, consumption and prices rose. The team studied the market and Oleg gave a start. Start of the project for the construction of the plant was laid in 2006, I joined at the beginning of 2007. This plant has a huge potential that we’re going to uncover.

— In newscasts various media reported that the new facilities are equipped with modern imported equipment, using new technologies. I would like to know more about it.

— Hardware industry was well developed in Ukraine, but only some companies have decided to invest in its development, it is basically the same place only «hardware resource consumption.» Our team (and we are in the market for over 20 years) to abandon the principle of patching up the holes, and used all his knowledge and experience as well as a new approach to the production, which resulted in a deep analysis and, consequently, the creation of a new plant, the basic idea of ​​which were high quality.

Let’s order. In 2005, the idea was born, who decided not to wait for better times, and immediately started to implement it. It was immediately purchased a building on the territory of the once thriving factory. In 2006, the first machines spun, but this part is less interesting. But in 2007-m was found to have well-known German Engineering Equipment Koch, high-performance straight-through wire drawing machine. Three machines have an annual capacity of about 25 000 tonnes. We have completely abandoned the Ukrainian-Russian counterparts infrastructure, including on supplies. When this wire is annealed in a French bell furnaces, or passes the next stage of redistribution — galvanized. The wire is manufactured in a range from

0 8 mm to about 6.0 mm (without intermediate annealing). Galvanizing process also runs on the equipment with the latest developments. Said equipment was provided advanced German, Italian and American machine builders.

Technical features allow galvanize as a wire with heat treatment or without it, diameters from 0.8 mm to 5.0 mm in heavy hanks Direct galvanized wire diameter of 0.8 mm instead of 2.0 mm galvanized wire and subsequently broaching more . The wire is wound on the small diameter riots weighing about 550 kg, thick — about 900 kg. The unit consists of 24 threads and has an annual capacity of about 21 000 tonnes in the nominal diameter of 2 mm. We also produce wire with a «heavy» zinc (galvanized vertical) with a surface density of the zinc coating of 500 g / m2. A rare, expensive, but still consumed product.

— Yuri O., which is the financial basis for this young dynamic enterprise? Investments? Leasing? Who are your financial partners?

— It all began with a 30% investment of the founders, which were carried out at their own expense. The project is interested in some of the banks in terms of long-term loans, and the leader of the banking industry of Ukraine was brought to us by foreign capital from one of the German banks.

Operational credits also granted the previously mentioned Ukrainian Privatbank. We have just entered the market at the time of an abrupt rise, and has already repaid part of the loan. We also hope to develop a program of investment and, consequently, rely on their partners to further service our project.

— Any modern production requires specially trained personnel and, of course, the key spetsialistah.Kak resolved this issue?

— Difficult question, but resolved. The basis of our personnel policies are highly qualified specialists who work in the industry is not the first dozen years. So, we have specialists — in the past workers’ Dneprometiza «, Zaporozhye Hardware Plant, who believed in this project.

Frankly, there are department heads and not older than 30 years, however, a reservation: a new approach, a new mindset, a new mentality. I assure you, this is a very sensible people, but when you consider who their teachers, it becomes clear that they are established in the market for a long time.

We are launching in stages, each time moving to a more complex product, so get the effect of increasing the qualification poorly trained staff.

With regard to skilled workers, the Yellow Waters — industrial city, which at the time was more than one plant. When we arrived, the city stagnated.

Selection of the production area has been very balanced. By the way, I would say we have galvanizing line located on the 3rd floor of a 3-storey production plant, with the weight of individual items of equipment exceeds 90 tons.

— Tell us more, to produce a product-oriented company? What are the volumes of production program provides?

— Construction wire — BP-1, «trehrebristaya»; General purpose — smooth diameter

0, 8-6,0 mm, annealed same diameter, galvanized t / a and T / H, nails and is woven mesh. In the future — special nails, fiber and welded galvanized mesh.

— Yuri O., the first two stages run enterprise implemented, although work on the debugging of the production mechanism is still a lot. But perhaps there are plans for the future? What kind? What is going to plan and how to implement the previously mentioned programs?

— We will gradually implement the program of membership evropalletchikov EPAL. Who are negotiating with potential suppliers. In the 4th quarter of this year we plan to identify the manufacturer of the equipment and sign a contract for the supply of grid equipment. Who among applicants we consider the Austrian, German, Swiss and American machine builders. With regard to the fixing of the production mechanism, the new equipment is calibrated chief assemblers, and then only control and rebuilding computers. This equipment requires a shallow intervention by staff. Today, a large part does automation, and the right skills to work with this equipment.

— In Russia at the present time within the framework of the association «RosMetiz» create new small metalware enterprises producing rebar for reinforced concrete. The construction industry is booming. In this connection, what are your plans for the production of products for the building complex? This refers to a class B500C cold-fittings, etc..

— There is a certain dynamics in the consumption of the product of the construction sector. BP-1 for us is not the most interesting product, however, we are producing. Metal a lot, production does not require high skills. It is logical and predictable development of small businesses in this sector to reduce the transport arm and reduce the cost of the product. Geography wide needs, and there is such a concentration of consumers in other metalware products mix, however it is fast working capital, the share of which is present in our capital. With regard to the reinforcement of cold, we know how to produce it, but the Ukrainian consumer market building wire lags in recognizing the advantages of this product, besides lagging behind and the legislative framework. We are pleased that Russia has woken up all the pros and adopted the national standard. Attempts individual producers are unsuccessful against the ruling bureaucratic colossus, so we offer and do not renounce their participation in the project to lobby the Russian analogue GOST R 52544-

2006 in Ukraine under the condition the organization of a joint project of Ukraine and the producers association Ukrmetiz in particular.

— As your business is focused on the domestic market of Ukraine, CIS and far abroad?

— We produce high-quality product. Not all Ukrainian consumers are ready for such a high quality. Mostly Western Europe. Now we consider the possibilities of supply on the market of the Middle East. The numbers look like this: 35% Ukraine 15% CIS, 50% of non-CIS countries. Recently, a very reduced supply in the Russian Federation due to the separation of raw material price offers. Now begins a kind of price correction in the Russian Federation, and look forward to a natural competition in the near future, which will allow a more aggressive sales policy in this market.

— It is no secret that the imported equipment and advanced technology are not a guarantee of high quality of the final product. Examples abound in this regard. Including in Russia. To a large extent determined by the quality of the hardware as the feedstock. What smelters will be your suppliers?

— In Ukraine, a very well-developed metallurgical industry. Despite this, the choice is small. Thus, our current suppliers are «ArcelorMittal Krivoy Rog» («Kryvorizhstal») and «Metinvest Ukraine» (Makeyevka Steel). We have a steady supply of wire rod with these companies and we are glad that after the change of the founders and the management team the quality of the products of both companies went up. However, the warning of this situation, we, together with the scientific group, representing the interests of Mechanical Engineering, conducted a deep analysis on the stage of ordering the equipment, and this is exactly the case when the advanced technology can help correct some oversight of suppliers of raw materials. Nevertheless, the problem is, and we are constantly holding talks on improving quality and we are glad that in recent years we have heard and participate in the resolution of our problems. There is another problem: the use of modern tools of incomplete financing of the purchase of raw materials. I believe that Ukraine will soon come to this. Also we consider deliveries from Moldova, but not now. Today, the price policy of the Moldavian plant is unacceptable to us.

— In conclusion, a few social issues. Tell me, is it safe to production staff and residents, as well as for the environment? And that gives the hardware plant population, and the city itself Yellow Waters?

— Business can not be social as such, and all its social orientation — it is also a business, because it is the fundamental basis of nothing more than how to housekeeping to get the maximum benefits, whether cash, or capitalization, or something else. With regard to social support from the city of our company, such a trend is present and takes a considerable share of our costs.

Let’s order. Let me remind you, we have come to the stagnating city where most of the working-age population went to work in the nearby towns such as Pyatikhatki and Krivoy Rog. Bought the building at JSC «Electron-Gas», held reorganization procedure at the time and is now estimated by experts as one of the best sanations in Ukraine.

Today, the average salary in our company exceeded the mark in 2000 hryvnia, and believe me, this is a high standard for our industry. Our staff regularly held free training to improve the skills, regularly paid bonuses, and the index of wage growth clearly exceeds the level of inflation, and it’s all over the place once a dying plant. We, together with the City of Yellow Waters are considering investing in the development of the city, but it plans for the future, because we just run the plant, and it takes several years to obtain economic benefits, particularly in view of the further investment and new jobs. Environmental activities at our plant on top, we have adapted to the European environmental standards.

We have the latest water treatment plant, we are self-neutralize spent solutions through equipment manufacturing company Oliver Dorn — one of the best in its segment. Here is an example. Our company sewage treatment plant (US-Belarusian origin) filtered air at 99,995%. This investment in the future of the city — it is our social pldderzhka.

Intellectual property in Russia

Patent law

1.Osnovy civil law;

2. Patent Law of the Russian Federation from September 23, 1992 №3517-1

3. Statutory acts of Rospatent and international agreements in the field of patent law.

1. Recognition of the patent owner the exclusive right to use (manufacture, use, importation, sale, and so forth. Patented object.

2. Limiting the term of the patent.

3. Provide protection only to those developments which are officially recognized as patentable inventions, utility models, industrial designs.

4. Recognition and protection of rights and interests of not only the patent, but the real creators of inventions, utility models and industrial designs.

1. The devices (system components located in the space, a certain way of interacting with each other).

2. The method (a set of techniques to be performed in sequence, or under certain rules).

3. Substance (artificially created financial education, which is a set of inter-related elements).

4. Strain mikroorgnanizma cell cultures of plants and animals (set of cells having a common origin and are characterized by the same robust features).

5. The use of a known device, process, substance or strain for a new purpose (the establishment of the new properties of known objects and to identify new areas of use).

1. novelty.

2. Originality.

3. Industrial applicability.

1. Publication of the Patent Office in its official bulletin information about the grant of a patent. This information includes the name of the author and patent holder, the name and the claims or the list of essential features of the industrial design and image

2. Introduction of industrial property in the State Register;

3. The issuance of the patent.

1. The right of authorship — based on the law and the fact the possibility of granting a patent recognized creator of the object. Perhaps co-authorship

2. The right to the author’s name — based on the law and the fact the possibility of granting a patent the inventor to demand that his name was mentioned as the creator of development in any of the publications he created the object.

3. The right to obtain a patent in his own name (except for employee inventions).

1. The author, the patent shall be entitled to remuneration for the assignment of a patent and license sales.

2. The author, not the patent owner shall be entitled to remuneration commensurate with the benefits derived by the employer

1. The exclusive right to use the protected invention, utility model or industrial design at his discretion, and the ability to prohibit the use of patented objects of others.

2. The assignment of patent rights, that is, the transfer of the patent owner of his right to another natural or legal person (s). The assignment of patent rights is not limited to any specific contractual model and can be accomplished within many civil contracts. Assignment means that the patent transferred to the purchaser in full all the rights that the patent holder.

3. To authorize the use of the patented object, that is, the transfer of rights under license agreements. This patent owner (licensor) grants the right to use the protected object to the extent specified in the contract to another person (the licensee), and the latter undertakes to pay the licensor arising from contract payments and perform other actions envisaged by the agreement. Depending on the amount of rights differ extradition treaties simple (non-exclusive) and exclusive licenses. Under the contract a simple license, the licensor retains all rights, including the right to grant licenses to third parties.

4. According to the agreement the exclusive license, the licensor retains the right to use an object within the limits specified by the contract, and not transferred to the licensee.

1. The payment of fees.

2. The obligation to use the patented object, otherwise the possible issuance of a compulsory license.

Imports of metal products in Russia in 2007

The volume of imports to Russia in 2007 increased in comparison with 2006 by 76.1% and amounted to 451.8 thousand kind. Tons.

The largest growth of imports in 2007 occurred in the group «fasteners» — 55.6% and the group of «wires» — 21.5%.

Growth of imports of other groups was within the general growth in consumption of metal products in Russia — 3.5-7%.

Main imports of metal products in Russia were made in China. China’s share of total imports in 2007 amounted to 40.7%, or 184 thousand. Tonnes.

Imports from Ukraine to Russia in 2007 amounted to 99 thousand. Tons, or 21.9% of total imports. A significant proportion of imports from the Ukraine — a wire, ropes, mesh. To a lesser extent nails electrodes.

The share of Taiwan’s total imports to Russia in 2007 amounted to 14.1%.

However, Taiwan almost exclusively Russian supplies fasteners, whose production in Russia or limited or completely absent.

Fasteners in the total import of hardware in Russia — the largest commodity group. In 2007, total imports amounted to 251 thousand fasteners. Tonnes, which exceeds the total output of fasteners Russian producers.

The main supplier of fasteners in Russia — China. Its share in the total imports of this commodity group 49.3%.

The share of Taiwan’s total supply of fasteners in Russia decreased significantly compared with 2006 and is 21%. While in-kind shipments remained at the same level. Deliveries of fasteners from Ukraine amounted to 10 thousand. Tons, which is slightly lower deliveries in 2006, which sostavlyali11, 4 ths. Tons.

Antidumping cordon imposed by some Russian producers of hardware fasteners against the Ukrainian, did not bring them the desired results.

The general trend of the growth of imports to Russia is likely associated with a catastrophic backlog of domestic producers in a number of commodity groups. And this gap every year increases the effect on importers of the consumer market. Refuse to import hardware — so do not meet the demand for products to end users in terms of volume and quality.

Today, Russian manufacturers are not able to provide import substitution, and their desire to impose anti-dumping duties on Chinese hardware to some degree provoke a rise in prices and hence inflation.

Most likely the state is completely appropriate to abandon the collection of customs duties on certain commodity groups hardware.

Canadian hardware industry in 2008

Analysis of hardware production

Information-analytical agency of the Association «RosMetiz» t Canadian hardware industry — a combination of modern enterprises. More than 57% of the production is supplied to the domestic market, 43% of production is exported. The main volume of exports carried out in the United States.

Over the past three years, the Canadian hardware industry has lost more than 23% of production volumes. This trend is linked to increased imports of wire products from South-East Asia.

However, the decline in output of metal products in Canada to a halt. In 2005 it amounted to 15.24% of the volume of production in 2004, in 2006 — 7.56% to the volume of production in 2005, then in 2007 the fall in production was 2.06% for the volume of production in 2006.

In 2008, Canada experienced significant growth of hardware production. If the growth trend will continue production until the end of 2008, it is possible that the Canadian hardware industry can play a three-year decline and reach the volume of production in 2005.

Production growth in the first quarter of 2008 was 14.83% compared to the same period of 2007. In April 2008 to April 2007, production growth was 23.22%.

The increase in production of Canadian hardware industry is associated with a global increase in steel consumption in the world, with umensheniem.importa from China, which is associated with undertaken in 2007 by the Chinese government measures to change the export price policy.

Holodnodeformiravannaya fittings B500C class 4

Problems and achievements of production and use

Madatyan SA, d. M. Sc., Prof.

In our country many years since 1961 the main type fittings periodic profile with a diameter of 6-40 mm was hot-rolled reinforcement class A400 (A-III) with a yield strength of 400 N / mm2.

At the same time in our country the focus until recently has been on hot rolled and thermo hardened valve class A500S, manufactured by SRT AISU 7-93, and now according to GOST R 52544- 2006.

Existing standards require the production of the reinforcement strength class through microalloying low-carbon hot-rolled steel and cold work hardening by rolling or drawing similar to mild steel.

Each of these technologies for the production of reinforcement with a yield strength of 500 N / mm2 has its advantages and disadvantages.

The properties of hot-rolled (y / x) and thermo-hardened (TMU) reinforcement rod in this class in detail and discussed in the works and other publications.

Meanwhile, properties and application prospects of cold valves (x / d) * B500C class started in our country discussed recently, and materials for its production and use is not enough.

On the basis of this are discussed prospects for expanding the production and use of the valve.

* Cold-class fixture 500 is designated in the SP 52-101 -2003 as the B500, GOST R 52544-2006 how B500C, and on TSN 102 and SRT AISU 7-93 as the A500S (A500Shd).

Manufactured still GOST 6727 wire (accessories) with a yield 00.2 gt; 500N / mm2 VR-1 diameter of 4-5 mm has a significant negative tolerance on the weight, so the joint venture 52-101-2003 developers were forced to reduce the calculated resistance of the entire cold nodeformirovannoy reinforcement class B500 5% compared with the same indicators for steel grade A500.

A role in prejudice against cold-class B500C reinforcement (A500Shd) also plays its tension diagram characterized proof stress 00.2 and relatively low values ​​of uniform elongation 5rgt; 2.5% and the ratio 0V / 0 °, 2.

Thus, if the hot valve stem microalloyed ferrovanadium, value 0 °, 2 / 0V average of 1,307 (see. Table. 1) 5p to 10-12%, in the hardened core thermo valve according to the diameter and the specifics of a particular enterprise, According to our data, it ranges from 1.09 to 1.31 willows average — 1.2 = 5p at 9.3%, then cold-deformed reinforcement, as a rule, there is no physical yield strength and the ratio of 0 °, 2 / 0V approximately equal to 1.1, and can vary 1,02-1,2.

Despite this, in many countries this strength class armature diameter of 4-12 mm and a diameter of 4-16 mm Germany manufactured and shipped cold-builders are generally in the form of heading reinforcement meshes i.e., frames, etc.

Regulatory requirements adopted by different countries and international standards to the mechanical properties of the fittings periodic profile with a yield strength of (0 °, 2) gt; 500 N / mm2.

This in total, that is, in the production and processing, compares favorably with the valve stem of 3-5% of the steel.

Production of cold-valve diameter of 4-12 mm are very harmoniously combined with the manufacture of its finished reinforcing elements, as this is a continuous process and without intermediate processing. This results in significant energy savings, labor and cost.

Equally important is the automatic control of the strength of the resulting metal, since the mode is set and hardening properties of the original rod likelihood of providing the specified mechanical properties are much higher than for other types of valves.

Another advantage is the possibility of cold valves production and use reinforcement of any size, as readjustment of equipment is much simpler than in a metallurgical plant. Therefore, the release valve with a pitch diameter of 1 or 0.5 mm or even 0.2 mm, that is, for example, 6.0; 6.2; 6.4 mm, etc., is quite real.

In the production of different diameters of such reinforcement in the area of ​​construction is provided an opportunity to obtain and use the right mix.

Construction companies in the country permanently are deficient to produce rebar with a diameter of 6-12 mm, and especially 6 and 8 mm. The real solution to this problem is to expand the production and use of rebar B500C class in this assortment.

For a discussion of the impact of specific stress-strain diagram of cold valves for her work in reinforced concrete, we have selected the most typical stress-strain diagram, consistent with international standards and actually found in commercial batches of steel grade A500S and B500C.

Diagrams tensile rebar study approximated spline functions in accordance with the passing through with a clear point of the physical meaning of the chart stretching values ​​are given in Table. 3, where in addition to temporary resistance Rm conditional σ0,2 or physical ReH yield strength into account the elastic limit σe1 = η1 σo, 2lt; ReH), the modulus of elasticity Es and relative uniform elongation of steel — Ap.

To assess the impact stress-strain diagram of steel grade A500S and B500C in the work of this reinforcement in flexural concrete elements used developed earlier calculation model of the normal section, based on a direct account in calculating the strength of the normal sections of parameters chart stretching valves («theory hardening») and built on these the following assumptions.

Limit voltage valves, located in the tension zone section are determined based on the average deformation in the zone of bending and stretching diagrams. The diagram of the compressive stress of the concrete in the process of destruction of the rectangular cross-section conditionally accepted to the height of x, the value of which is determined based on the average height of the strain diagram of concrete in the zone of bends H.

The scheme of deformation of a middle section, and characterized εξsm εbm, estimated on the basis of the hypothesis of plane sections.

Limit stress of concrete in the compression zone, taking into account the specific characteristics of different types of concrete are determined by mb-Rnp, and the limit voltage in compressed fixture asc by the formula:

σsc = εm • Es

The height of the compressed zone section and the moment due to external forces, perceived cross section determined from the equilibrium conditions.

Based on the accepted hypothesis of plane sections of concrete compressive strain and tension reinforcement, as well as acceptance of conditions that εSm = ψs msm.

Introduction to the basic relationship between the average strain of concrete and reinforcement defined on the basis of the hypothesis of flat sections, feedback εsm with ξ, by msm, allows you to move away from this hypothesis in determining 0sm and bring the calculation model to the real work of the cross section of reinforced concrete elements, but at the same while preserving the relative ease of withdrawal of calculation formulas.

Without going into detail on the mathematical details of solving this problem, considered in [12,14, 17], we discuss the results presented in Fig. 2 and 3 and Table. 4.

Comparative evaluation of the results of theoretical analysis shows that the stresses in the armature to the yield plateau and Rm / 1.2 = ReH changing ξ, ranging from 0.1 to 0.46 are on the same level and in the armature with a nominal yield strength even at ratio σb / σo, 2 = 1.02 stresses grow almost proportionally to ξ, and almost reach interim resistance at ξ = 0,3, and at σb / σo, 2 = 1.2 tensile strength is achieved when ξ = 0,04.

Thus, over a wide range of flexible reinforcing elements, characterized by the relative height of the compressed zone of about 0.1 to 0.35, with the fixture proof stress it is used more efficiently than steel, has a yield stress of the physical [12, 13].

Therefore, in this range of the reinforcement of concrete structures of cold-fitting it has certain advantages.

However, this is not evidence of the benefits of such valves in all types of concrete products. The combination of the low rate of reinforcement and low elongation δp can theoretically cause a sudden brittle fracture or bending eccentrically compressed concrete element when ξ lt; 0,1 due to rupture of reinforcement.

Therefore, we investigated the effect of the separate relationship Rm / ReH (Rm / σo) and relatively uniform elongation ξr the possibility of premature failure of reinforced concrete structures, as measured by the minimum allowable value.

The analysis showed that μmin and ξmin predominant influence the value Dp, the change is from 1 to 10% lead, for example, Rm / ReH = 1.2 to change from 0.14 to ξmin

0, 017, that is 8 times (see. Fig. 4).

The ratio Rm / ReH more or less significant impact on the value of ξmin only if Dp less than 3%.

For large values ​​of Ap change this ratio affects the ξmin very weak. Thus, the change in Rm / ReH 1.02 to 1.5 resulting in Ap of 1% change ξmin from 0.17 to 0.11, and when Dp is 3 and 8%, respectively, from 0.075 to 0, 05 and from 0,030 to 0,022 (see. Fig. 4).

Based on the analyzes, the following conclusions.

— When using reinforcing steel grade A500S, chart area is characterized by tension strength at magnitude εt gt; 1.5-2.0%, and the reinforcement of cold-class B500C, the chart is characterized by proof stress σo 2 ratio Rm / σo, 2 or Rm / ReH. As discussed within virtually no effect on the armature voltage and the strength of normal sections of bent reinforced-concrete elements, steel-reinforced this.

The determining factor is the value of the yield strength of the conditioned — σo, 2 or physical — ReH and specifications charts — Es, σel and εt.

— The amount of elongation before breaking δmah (Agt) or Ap should be, respectively, not less than 2,5-2,0%, since its value is below these standards arises when the probability of rupture valves ordinary reinforcement in bending and eccentrically compressed reinforced concrete elements, characterized ξ≤0,1 and μ≤ 0,2.

— Lack yield plateau and having yield strength reinforcement provide higher voltage limiting fixture when changing ξ in the range from 0.1 to 0.35 compared with the use of steel with yield plateau.

Therefore, cold-class B500C reinforcement to the diagram characterized proof stress is more preferred for concrete structures in a fairly wide range of reinforcement.

In assessing the performance properties of reinforced concrete structures is an important criterion allowable width of the cracks, the value of which according to the SNIP 2.03.11- 85 for structures reinforced with cold-fitting of VR-1 (B500C), set the same as for the structures of reinforced steel hot-rolled reinforcement Class A-1 (A240), A-II (A300) and A-III (A400), and the fittings, as well as the steel grade A500S is permitted for use in the construction of the third category of crack resistance in slightly aggressive environments.

The use of cold-class B500C reinforcement in-situ reinforced concrete, usually in the form of ready-made frames and double-layer mesh carpets, which significantly reduces labor costs for reinforcement and to reduce the cost and accelerate the construction.

Thus, for technological reasons, as well as in the use of reinforced concrete in the application class B500C reinforcement diameter of 4-16 mm is very effective, and its calculated resistance should be harmonized with the calculated resistance of reinforcing steel grade A500S.

However, these problems are not limited to the production and use of cold fittings periodic profile of B500C.

For its production, as mentioned above, we need rod, wherein the rod certain properties and chemical composition.

If the total expected demand for rebars periodic profile in 2010, about 8.6 million. Tons of the need for reinforcement of 4-12 mm in diameter is 42% or 3.6 mln. Tons. Of this amount, at least half is desirable to have a reinforcing products from cold-reinforcing steel class B500C.

For its production will require about 1.8 million. Tonnes of wire rod of appropriate quality, that while it is difficult, because it requires to build 3-4 new wire mill and put in place in addition to the existing for at least 180 production lines of cold-class fittings B500C.

Nevertheless, it must be done, because the lack of reinforcement in the construction of periodic profile with a diameter of 4-10 mm leads to a waste of steel in an amount comparable to the amount of its use, and a significant rise in the cost of construction of reinforced concrete.

This is all the more important as the cost and the price of steel bars rose sharply and continued to rise.

You can see another aspect of the production and use of reinforcement class B500C: until all the equipment for their production is bought abroad: in Germany, Italy and Taiwan.

The development of such a production in Russia would be very useful for increasing the volume of production of the fittings, and for the development of domestic engineering.

I. Tikhonov, deputy director of NIIZhB to. T. N.,

Gumenyuk VS EXPERT center design and expertise NIIZhB to. T. N

In order to save steel hot-rolled and heat (or thermo) hardened rolled round or periodic profile is subjected to mechanical cold working to increase the strength by work hardening. Work hardening — a hardening of the steel as a result of plastic deformation at a voltage higher than the yield stress.

Thus obtained reinforcing steel in comparison with the original has higher elastic-plastic (apparent yield stress σ0, σ2) and strength (yield strength σ0,2, tensile strength Rm) characteristics that the rational use in reinforced concrete structures allows saving of metal .

By the method of treatment in which the change occurs in addition to the hardening of shapes and sizes, that is, the deformation of the original rental received reinforcement called holodnodefor- mated.

Currently out of applied in domestic and foreign practice ways of strengthening reinforcement cold enough widespread:

— drawing wire rod through the monolithic or roller die (caliber), in which by the action of a radially directed compressive stress and tensile force decreases rod cross-sectional area;

— cold rolled wire rod in caliber, with drive rollers, which differs from the drawing or the lack of a low value (less than the elastic limit) tensile force;

— extractor rod periodic profile or smooth by applying a tensile force to the control of a predetermined voltage and a predetermined limit extension, or the control of only the specified extension or control only the specified voltage (power calibration);

— twisting, where one end of the rod is fixedly mounted and the other end forcibly rotated about its own axis.

The latter type of reinforcement is produced mainly abroad. In the 40-50-ies of the last century in the Soviet Union in accordance with GOST 6234-52 produced holodnosplyuschennuyu ribbed bar, which can also be attributed to the hardened cold.

From the theory of strength of materials it is known that steel refers to a class of materials that resist the same tension and compression and, respectively, have the same basic mechanical properties. However, the actual voltage proportional limit, elasticity, tensile strength and compressive strain for the same do not match, the difference therebetween exceeds the error experiments.

This is due to anisotropy, discontinuity, heterogeneity of physical and mechanical properties (eg, length) of rolled steel, that is available in practice deviations from the hypotheses on which the modern theory of strength of materials.

It is known that pre-stretching of the metal in a direction making it stronger when operating in the same direction, but does not improve to the same degree of its mechanical properties when working in compression in the opposite direction. In addition, tensile (or compressive) strain above the elastic limit of the yield strength significantly reduces the compressive (or tensile), and the greater extent than the force applied was higher than the initial elastic limit. This phenomenon has been studied in the XIX century I. Baushinger and therefore has been called the effect Baushinger.

In view of the above, it is of interest the comparison of national rules adopted for the design of reinforced concrete structures of regulatory and calculated resistance reinforcement tension and compression in view of the technological features of its cold hardening.

As representatives consider hardened hood reinforcement class A540 (A-IIIB), cold-drawn reinforcement of VR-1, B-1 and cold-B500C.

According to the SNIP 52-01-2003 main characteristic strength of reinforcement in tension and compression, which determines its class, is a normative resistance Rs, n, equal to the value of the physical (ReH) or conditional (σo, 2) tensile yield strength, which is not guaranteed with security less than 0.95.

Estimated value of the resistance Rs reinforcement tensile and compression Rsc determined by dividing the value of Rs, n the safety factor for the fixture, whose value depends on the class of reinforcement and the considered limit state. Influence of various factors not directly reflected in the calculations take into account in the calculated values ​​of the armature resistance factors for ysi, the values ​​of which are set based on experimental studies.

This ensures the required level of reliability of reinforced concrete structures in which the working reinforcement is calculated in compression or tension.

As an illustration, Table 1 shows the calculated values ​​of tensile strength and compression hardened hood reinforcement class A540 (A-IIIB) and initial hot armature A400 grade (A-III) for limiting the first group of states in the design of reinforced concrete structures standards developed over the years . For comparison, the standard values ​​and tensile strength Rs, n for the same classes of reinforcement.

Given the massive use of modern construction in hot and thermo hardened reinforcement class A500 (A500S and A500SP) Table. 1 shows similar characteristics, and these types of valves.

The data in Table. 1 data indicate that the reinforcement class A-III (A400) A500 and the calculated resistance values ​​are the same tension and compression. This implies that the same values ​​and the relevant regulatory resistance, ie comply with the conditions that the yield stress of hot-rolled reinforcement in tension and compression are equal. Some increase in the calculated resistance reinforcement of class A-III (A400) at a constant value of resistance due to refinement of the regulatory safety factor for reinforcement increasing output and storage array (sample size) test results.

It should be noted that the value of Rsc for valves Class AIII (A400) are not limited to limit compression strain of concrete, and for the A500 limit limiting compressive deformation of the concrete occur only at short-term effect of load (Rsc = 400 MPa).

Another picture is observed in respect of reinforced hood reinforcement Class A-IIIB. Estimated (and normative) the value of tensile strength Rs that reinforcement is increased by 33% and the estimated value of compression resistance Rsc left at the level of the original fittings of Class A-III until 1970.

It assumed that the stretch hardening increases the yield strength, therefore, Rs, n, tensile reinforcement and reinforcement for compressed regulatory took without increasing the resistance as hardened steel obtained by stretching can not be used when working in compression.

The Guide [9] the estimated value of resistance to compression fittings have class-IIIB without justification [3; 15] was increased by 18% compared with the initial fitting of class A-III.

However, in snip 2.03.01-84 along with increased tensile strength values ​​calculated for reinforcement classes III-A and A-IIIB an average of 11% the value of the calculated compressive strength reinforcement in Class A-IIIB reduced by 45% compared with the armature class A-III.

Similar values ​​of Rs and Rsc stored in later regulations.

Table. 1 attracts attention an interesting fact: in view of the changes in SNIP 2.03.1- 84 the sum of the calculated resistance to tension and compression fittings for hot class A-III and reinforced hood reinforcement Class A-IIIB is almost the same (difference 3-6 % taking into account the rounding these values ​​is insignificant). Consequently, SNIP 2.03.01-84 for reinforced hood reinforcement Class A-IIIB ACCEPTANCE OF TERMS: how to increase its yield strength as a result of hardening in tension, so the reduced yield stress in compression.

The reason for the above-mentioned controversial changes calculated resistance compression and tension reinforcement Class A-IIIB was, apparently, in the absence of data of experimental research work on compression fittings due to the technical complexity of carrying out such tests.

Until the 70s of the last century in the domestic technical literature almost no publications on this topic. We only given in [4] test results for compression fittings of hot-rolled round steel SV of a diameter of 10, 12 and 15 mm and obtained from her holodnosplyuschennoy fittings periodic profile. The height of the samples was chosen to be twice the diameter. For the yield stress of taking the voltage at which the deformation of the sample no longer follow the law of proportionality.

Despite the drawbacks of testing, as evidenced by the character author cited work state diagrams samples reinforcement in compression, it was found that the ratio of yield strength and initial hot holodnosplyuschennoy reinforcement in tension and in compression are approximately equal. This is because when applying periodic profile holodnosplyuschennaya armature undergoes deformations transversely to the longitudinal axis of the shaft [4].

In the early 80-ies in NIIZhB it was tested reinforcement Class A-IIIB in tension and compression. Tensile specimens valves tested in accordance with GOST 12004-81 [16].

The methodology of the tests on samples of axial compression fittings periodic profile is described in detail in [17] differs from the recommendations of GOST 25.503-97 [18]. Based on pilot experiments in compression was found optimal length of the sample valve of 25 mm diameter equal to 90 mm, at which the rod does not lose stability at voltages exceeding the yield strength is an average of 1%, and thus there is uniform compression of the sample based on the measurement of deformations . With further increase of the load becomes unstable samples.

As a result of these tests it was found that the hardening of the hot hood reinforcement Class A-III tensile yield strength increased and compressive — decreased as compared with the initial state of the valve. This allowed to amend the SNIP 2.03.01- 84 and subsequent releases standards for design of reinforced concrete structures [11; 12; 13].

To assess the impact of the stress level for static tensile reinforcement with periodic profile its behavior under static and unitary dynamic compression of interest made in 1991 NIIZhB test fixtures class A600 diameter of 12 mm (steel grade 28C), the results of which are presented in [19]. This fixture was pronounced yield plateau, that is, the physical yield stress ReH. Therefore, to evaluate the behavior of fittings in the elastic-plastic zone until ReH as a control (limit) the index value used yield strength σ0, 2.

Upon initial static tension to a level equal 0,75σo, 2 and the subsequent static compression diagram of the valve (in the axes of σi-εi) corresponds to that in the separate loading of tension and compression to yield strength. When stretched to 0,960σo, 2, and subsequent compression value of yield strength decreased to a level of 0.93 σo 2.

If the initial tensile stress to close to the value σo, 2 (deformation reinforcement EP = 0, 45%, the residual strain relative εpgt; 0,1%), and subsequent compression yield strength in compression decreased to 0.7 σo, 2.

Consequently, tensile stress exceeding the elastic limit of the valve, but minimal yield strength σo, 2, significantly, up to 30%, reduced the yield strength of the static compression when compared with that in tension. It also noted that in the case of dynamic compression σo 2 in the fixture class A600 is strengthened by 8-10%.

After deformation at static tensile reinforcement of 1.4% of its tests on the static compression showed a decrease in yield strength by 60%, which confirms the validity of the rules [12,13,14] solutions for reinforcement reinforced hood. The value of yield strength under dynamic compression ratio is about 50% of its value at static tension.

In view of the foregoing valves class A-IIIB is used only as a pre-stressed reinforcement, mostly large diameter due to the scarcity of reinforcement class ATV (AT800). It is inefficient to use as a compressed reinforcement of concrete structures.

Taking into account the high resistance of the valve design class A500SP in tension and compression, good adhesion to concrete, it can expect mass adoption not only in unstressed, but also intense designs, including return valves class A-III (A400) and AIIIv.

The above must also be borne in mind in connection with the proposals appeared to increase the strength class fittings periodic profile, supplied in coils up to the level of 500 MPa by cold hardening (work hardening) alternating bending and axial tension [20, 21].

To determine the reasonable estimated values ​​of resistance to compression fittings needed a pilot study of the effect of the proposed technology in the phase diagram of reinforcement in tension and compression.

Consider the evolution of the design values ​​of resistance to tension and compression reinforcement of cold (also wire) of low-carbon steel according to GOST 6727-53 and GOST 6727-80 [22] with a diameter of 3 to 5 mm in domestic regulations.

Necessary data are shown in Table. 2, which is also presented to compare the characteristic values ​​of resistance to tension Rs.n.

Prior to 1984, due to regulatory resistance Rs.n reinforcing wire B-1 took the smallest controllable value of the ultimate tensile strength [8; 10].

In SNIP 2.03.01-84 for reinforcing wire Bp-1 Rs.n taken as a voltage equal to 0.75 ultimate tensile strength as measured by the nominal cross-sectional area [11].

Note that in the GOST 6727-80 [22] wire VR-1 class there is a requirement to decrease in the (6.3-6.8%), the actual cross-sectional area compared to the nominal.

In SNIP 2.03.01-84 * [12], which are edited snip

2.03.1- 84 [11] to change №2, entered into force on 01.01.1992 year for regulatory resistance reinforcing wire took the smallest controllable value of yield strength guaranteed with a probability of at least 0.95.

The same principle is used in the SP 52-101 -2003, where cold-drawn wire of VR-1 and class B500C cold-fitting combined into a single class of cold valves B500 [14]. Fittings class B500C different wire VR-1 class manufacturing technology, mechanical properties and views periodic profile [24].

Until 1992, the calculated resistance reinforcing wire tension and compression were taken the same.

Since 1992, rules of design of reinforced concrete structures design values ​​of tensile strength wire of VR-1 were increased by 9,3-13,9% compared to earlier, and the calculated values ​​of compressive strength remained unchanged under long-term load and reduced to 5,5-9,3% for short-term load.

As a result, SNIP 2.03.01-84 * [12] wire VR-1 class design value of tensile strength exceeds that in compression 9.3%.

For valves decrease the value of Rsc compared to Rs equivalent reduction of regulatory resistance (or the level of the guaranteed yield strength) when compressed by the same amount. At a constant value of the modulus of elasticity is a Certificate of SNiP 2.03.01-84 * [12] The difference between the elastic and plastic properties of the wire of VR-1 under compression and tension.

Unfortunately, in the domestic technical literature sources identified justifying accepted ratio calculated resistance to tension and compression wire VR-1 class.

The joint venture 52-101-2003 [4] for the reinforcement of cold-class B500 at long action taken equal load Rs = Rsc, that is, the condition is ignored differences elastic-tical properties of cold drawn wire of VR-1 in compression and tension provided in the SNIP 2.03 .01-84 * [12]. At short-term effect of the load is the difference indicated by the introduction of the coefficient of working conditions, equal to 0.9, the limiting value of resistance to compression fittings holodnodeformiruemoy, which is caused by strains of shortening the concrete surrounding the rebar compressed and having her grip, that is,

RscKP = 400 x 0.9 = 360 MPa.

Given the fact that for reinforcement classes A500 and B500 in tension and compression made the same value of the elastic modulus (E = 2×105 MPa), as set shows a certain contradiction in the appointment of the joint venture 52-101-2003 underestimated [14], the calculated values ​​of tensile strength and compression fittings for Class B500.

Obviously, this contradiction is due to exercising caution drafters of the rules published by the lack of statistics tensile tests, and the lack of compression testing wire VR-1 class and class B500C reinforcement due to the complexity of such tests.

At the same time, developers have ignored the joint venture 52-101-2003 long international experience of production and use of cold-class reinforcement strength of 500 MPa, measured, in particular, the draft Euronorm prEN 1992-1-1 [26].

In the manufacture and processing of cold-valves class B500 (VR-1; B500C), which comes as a rule, in coils, steel undergoes complex inelastic deformation: the radial compression and stretching during drawing and creating a periodic profile, bending deformation during the formation of the skein, the diameter of which It does not provide reinforcement straightness and reverse bending to improve the properties of plastic fittings and for ensuring its straightness.

Note that these inelastic deformation are perpendicular to the longitudinal axis of the armature. Tensile forces at drawing rod corresponds, as a rule, the elastic steel and is determined by the compression unit, the resulting pulling through a die (monolithic portage) or one size (roller die).

So, filed, given in [26], the force pulling the wire of carbon steel in the worst case (drawing standard monolithic portage without lubricant) was between 0,39N / p at the value of the unit of compression 15% and 0,59N / p at a value compression 25% of the unit where the N / p — breaking strength of the wire.

In consideration of the wire ratio σo, 2 / Rm = 0.93 … 0.97.

Therefore, the compression unit 25% and drawing adverse conditions the tensile force of the wire does not exceed 0.56 σo 2.

For reinforcement of cold-class B500 (VR-1; B500C) this level of stress is less than yield point σo 2 under tension.

When considering the features of cold-formed steel, obviously, it does not show the effect Baushinger. That is why the draft Euronorm for design of reinforced concrete structures made pr EN 1992-1-1 same state diagram in tension and compression of cold and hot rolled or thermomechanically hardened valve with guaranteed yield strength of 400 to 600 MPa [27].

These emission class for a reinforcement of cold and the design modulus of elasticity is assumed to be 2,05h105MPa (allowed 2×105 MPa), although the actual value of this feature may vary from 1.85 to h105MPa 2,1×105 MPa. Safety factor is 1.15 for the fixture if the fixture complies with the European standard draft pr EN 10080 [28].

Experience certification of cold-class B500C reinforcement of domestic production (of «Upper Volga steel service center», Ivanovo, LLC «Plant-Innovator», Belgorod) has shown that compliance with certain technological requirements allows to obtain products whose mechanical properties with normalized security correspond to European standard pr EN 10080 [28].

In view of the above, and in order to harmonize the requirements of domestic and foreign design standards for the reinforcement of cold-class B500C invited to adopt the calculated resistance to compression: the short-term effect of load RscKp = 400 MPa and a prolonged action of the load RscKplt; Rs.

On delivery of cold-class B500C reinforcement, which normalized mechanical properties are guaranteed a certain security, safety factor γs of fixture for the first group of limiting states to adopt equal 1.15, as in the reinforcement of class A500S (Rs = 435 MPa) [24; 27].

In the absence or Failure to comply with at least one of the characteristics of standardized mechanical properties of a safety factor for the fixture to be taken equal to γs = 1,2 (Rs = 415 MPa).

Wire VR-1 class according to GOST 6727 [22] because of the deformation properties of instability corresponds to the second case, where γs = 1,2 (Rs = 415 MPa).

For a wire of VR-1 in determining the design values ​​of resistance to compression continue until the relevant experimental studies must maintain the approach taken in the SNIP 2.03.01 -84 * [January 2] (Rsc = 375 (340) MPa). In addition, due to low plasticity should not be recommended wire Bp-1 used as working (estimated) reinforcement for concrete.

References

1. Nikiforov BA, Kharitonov VA, Kireev EM Production of high-strength reinforcing wire. — Sverdlovsk, UPI Edition, 1982.

2.

3. Moulin NM bar reinforcement of concrete structures. — M .: «Stroyizdat», 1974.

4. Abaco AI fittings periodic profile for reinforced concrete structures. -A .: «Mashstroyizdat» 1949.

5. Timoshenko SP resistance materials. Volume Two. More complex questions of the theory and objectives. — M .: «Science», 1965.

6. P F. Moore, J. Commerce. B. Fatigue metal, wood and concrete. — M .: Gostekhizdat 1929.

7. SNIP 52-01-2003 Concrete and reinforced concrete structures. The main provisions. — M .: Federal State Unitary Enterprise Russian State Construction Committee of LAC, 2004.

8. SNIP II-B. 1-62 * Concrete and reinforced concrete structures. Design standards. — M .: «Stroyizdat», 1970.

9. Design Guide prestressed concrete structures of heavy concrete. — M .: «Stroyizdat», 1977.

10. SNIP II-21-75 Concrete and reinforced concrete structures. Design standards. — Moscow, «Stroyizdat», 1975.

11. SNIP 2.03.01-84 Concrete and reinforced concrete structures. — M .: TSITP USSR State Committee in 1985.

12. SNIP 2.03.01-81 * Concrete and reinforced concrete structures. — M .: SUE LAC Construction Committee of Russia, in 2000.

13 — M: TsNIIpromzdany of 2005.

14. SP 52-102-2003 rulebook on design and construction. Prestressed concrete structures. — M .: FSUE LAC,

2004.

15. New in the design of concrete and reinforced concrete structures. — M .: «Stroyizdat» 1978.

16. GOST 12004-81 Steel reinforcement. Methods Tensile testing. — M .: Publishing House. Standards, 1986.

17. Tarasov AA High-thermostrengthening large diameter valves and conditions of its use in the compressed concrete elements / Diss. on soisk. scientific degree of candidate. tehn. Sciences. — M .: NIIZhB 1983.

18. GOST 25.503-97 Calculations and tests of strength. Methods of mechanical testing of materials. Method for testing the compressive strength. — Minsk, IPKIzd standards, 1997.

19.N. Rebar responsible for buildings and structures, including projected considering emergency loads and prevent progressive collapse / Proceedings II Russian (International) Conference «Concrete and reinforced concrete — the path of development», ie 5 — M .: NIIZhB, 2005.

20. RF Patent N92074084 the invention «line for harvesting and hardening of reinforcing bars» with a priority of 26 November 1992

21. Kharitonov Vic. A. Kharitonov Ven. A. Features of hardware production of rebar diameter 5,0-12,0 mm strength class 500 // Dnipropetrovsk, «HARDWARE», №9, 2007.

22. — M .: Publishing house PKI. Standards, 1998.

24. I. Tikhonov, Gumenyuk VS Requirements Analysis SP 52-101 -2003 to fixture strength 500MPa class // «Concrete and reinforced concrete», № 4, 2006.

25. Chistyakov EA, Beisembaev MK Estimated high resistance to compression fittings // «Concrete and reinforced concrete», №6,1991.

26. pr EN 1992-1-1: 2003 Eurocode 2: Design of concrete structures-Part 1.1: General rules and rules buildings. CEN

27. Demidov AV Methods for producing drawn wire increased ductility by additional radial deformations // «Hardware», №1 (17), 2008.

28. pr EN 10080-1: 1999 Steel for the reinforcement of concrete — V fellable reinforcing steel. CEN

29. CTO 36554501-005-2006 *. Application class A500SP reinforcement in concrete structures.

The development of hardware production is impossible without the use of modern technologies. One such area is the production of the wire using a mechanical descaling. For successful implementation of this method of production of wire is necessary not only special equipment, but rods with special surface properties, which allows to fully implement this process and obtain a significant cost reduction.

Magazine «Hardware» continues to acquaint the readers with aspects of technology acid-free surface preparation of metal for drawing. Article Japanese experts will help to understand the essence of the technology, and the right to determine the requirements for steel wire rod for this mode of production.

Editors of the magazine «Hardware»

Production rod with a high capacity for descaling

Jiro Tomigana, Kinya Vakimoto, Toshimichi Mori Masaaki Murakami, Takafumi Yoshimura,

Japan

The development and mechanisms descaling rod chart shown using Fe-O.

I. Introduction

The hot products of mill scale formation is unavoidable in the course of cooling after a high temperature immediately after rolling to ambient temperature.

Etching is mainly used for descaling before drawing. However, due to stricter rules for the control of pollution related to the acid treatment, requiring additional costs, mechanical descaling was put into industrial use, and this process tends to spread because it provides a significant advantage in the formation of a low operating cost.

Residual scale due to insufficient quality of its removal leads to rapid wear of drawing dies, gloss reduction and an increase in surface roughness of the wire. Intensification remove residual slag leads to a significant increase in surface roughness, increase in costs, a loss of metal due to its peretrava. Therefore, consumers are demanding that the mill scale on wire rod was removable.

Manufacturers rod studied the optimal production conditions under which losses are reduced scale and a high quality of the surface at its disposal, while wire rod giving the required mechanical properties and structure.

These studies have provided some positive effect.

This report concerns the mechanism of descaling in the wire rod and the factors that determine the quality of descaling, such as the thickness of the scale, composition and roughness of the scale iron base, as well as considering the structure of scale, which are suitable for her etching and mechanical removal.

2. The mechanism of formation of scale

There have been many observations and studies on the scale, which was influenced by the surface oxidation of iron at a high temperature. The results of these studies are set out below.

As shown in Fig. 1, in the phase diagram of Fe-O, depending on the oxygen content, there are three phases: wüstite (FeO), magnetite (Fe304) and hematite (RegOz).

Wust, who has the greatest influence on the properties of the mill scale, considered in this report has the following features.

Firstly, wüstite always has a crystalline structure in which there is a lack of Fe atoms and the formula which is described by Fel-yO. Measurements Angell [1] the value of y increases with increasing distance between the iron base and scale, as shown in Fig. 2. wustite has a 5-16% ethyl lack of atoms Fe. This explains that the wustite — softest and most easily soluble in acids from all phases of scale.

Secondly, wustite, which is oxidized at high temperature undergoes eutectoid transformation at the temperature of about 570 ° C and is converted as follows:

4FeO — Fe3O4 — Fe. (1)

According to Chadron Foreysteru and [2] the maximum percent conversion wüstite achieved at 470 ° C.

According to Fisher [3] and Shiroive Matsuno and [4], this temperature is 400 ° C.

Shiroiva Matsuno and the grating period changes counted and noted that scale converted to wustite long period grating at temperatures from 400 to 500 ° C, and then carried out the conversion in the Fe3O4 (Fig. 3 and 4).

According to Fischer [3] and Takagi [5] release of the Fe is always observed after conversion into Fe304. They offered the following response:

(1 -4u ‘) Fe1-yO — (1- 4y) Fel-y’O + (y-y’) Fe3O4 (y ‘ lt; y). (2)

This means that in this reaction wustite loses less of Fe atoms and is confirmed by the fact that a slight amount of Fe in the transformed Fe3Cgt; 4 scale on the wire rod.

The composition of the wire rod mill scale schematically shown in Fig. 5. Theoretically wüstite, magnetite and hematite formed on an iron-based, in that order.

Davis [6] and Raidassi [7] demonstrated that the content of these oxides is correlated as 95% — 4% — 1% at a temperature of 620 ° C or higher and that the amount of magnetite is slightly increased at higher nizkihtemperaturah. According Ganberu Sterdzhinu and [8], these oxides have the molar ratio as shown in Fig. 6, at various temperatures, and mill scale consists of a few percent Fe304 and FeO to balance at ordinary temperatures between 700 ° C and 900 ° C. In general, this coincides with the described data.

Scale thickness increases with increasing temperature and time and is expressed as d = kt, (3) where: d — scale thickness, t — temperature, k — constant.

However, the actual scale is formed under the influence of different conditions of cooling, depending on the operating conditions and the location of wire rod in the skein. Therefore it is necessary to take into account the following conditions:

— the residual part of the oxide scale, formed during rolling, is estimated at a few micrometers and thus considered to be a minor;

— cooling is desirable to immediately after rolling, since the amount of slag increases as the temperature rises and increases the time between the end of rolling and start of cooling water;

— After cooling water temperature (temperature-called layout turns) — one of the most important factors. High temperature leads to the formation of a thick layer of scale containing a large amount of Fe3O4 and Fe2Oz. Low temperatures pickup coils form a thin dense scale, containing a large number of FezO4.

The degree of cooling affects converted to FeO Fe3O4 whether or not, and on the amount of dross. In the case of tight coils of a slow cooling, which is undesirable, and there are significant variations depending on the location of the wire rod in the skein.

Scale thickness and composition vary depending on these conditions. Also, the presence of cracks in the scale is an important factor in determining the quality of descaling.

Cracks are formed inevitably due to the different thermal expansion coefficients of the iron base and the scale during cooling and internal residual stresses that are quantitatively dependent on the phase transformation takes place or not. Cracking conditions depend on the thickness of the scale, its strength and other factors. The number of such cracks and the distance between them — are important factors to consider when descaling.

3. The mechanism of descaling

3.1. Etching

Etching has long been considered the main way to remove scale. In an acidic solution the solubility of FeO is highest, followed by reduction of the degree of solubility and are located Fe2Oz Fe3O4.

According to the main scale pattern shown in Fig. 5 Fe2Oz dissolution occurs, which is the most insoluble and in Fe3O4 and FeO. In general, however, this concept is not applicable. As mentioned above, the scale is not ideal, there are microcracks formed during cooling and processing. When these cracks reach the cell on a metal surface consisting of oxides of iron are formed and the acid, and it is believed that the base steel dissolves first.

For dissolving iron base should decrease dissolution of oxides. In connection with this example the following reactions are considered.

Anode reaction:

Fe -gt; Fe² * + + 2e (4); cathodic reaction:

* 2H + 2e -gt; H2 (5)

FeO + 2H + 2e -gt; Fe² + H2O * (6)

Fe3O4 + 2H * + 2e -gt; 3Fe² * + H2O (7)

Fe2O3 + 6H * + 2e -gt; 2Fe² * + ZN2O (8).

In theory ionnnogo decay Enzhella [9] it was shown that the rate of decay changes depending on the potential. In conventional etching, however, it is considered normal when the decay takes place in the order (4), (5), (6), (7) and (8).

In the case of a relatively thick oxide scale on the wire rod, oxides dissolve in acid, as shown in the above reactions, and a process of descaling. H2 pressure generated by the reaction of (5) contributes to the mechanical purification of metal from dross. This can be determined by piece dross floating in the pickling tanks.

Thus, it can be summarized that the scale is etched well, having the following characteristics:

— it consists mainly of FeO and to a lesser extent — of Fe2Oz;

— It has numerous cracks;

— It has poor adhesion to the iron base;

— It has a thin layer of scale.

3.2. Mechanical descaling

During the past decade, more than once, emphasis on the problem of processing liquid waste etching from the standpoint of controlling pollution. Mechanical descaling has been seriously investigated and has been used more frequently, as the cost of processing liquid waste and sludge disposal are high.

Currently, only three below-described process.

3.2.1. The process of reverse bending

In this process, scale, which is much more fragile than the steel, cleaned and removed with the surface of the rod tensile strain and compressive strain produced by bending and reverse bending using a plurality of rollers.

Deformation of the surface rod is determined by the formula d / (D + d) (d — diameter of the rod, D — diameter of the roller). In general, the required deformation descaling should be 6-8%. Constant tension rod is made through multiple bends at a constant voltage. As shown in Fig. 7 [10], such elongation tends to increase with the number of passes according to an exponential curve.

Fig. 8 [10] shows the relationship between the elongation of the material and the amount of residual scale. Descaling by simply stretching requires 10% stretch material. However, by the process of reverse bending sufficiently less than 5% stretch to effectively achieve the objective.

Final purification can occur only by means of stretching of the material should also be clear it of residual slag by means of metal brushes.

3.2.2. Surface shot blast

Descaling can be used blast installation. Currently used steel shot or chopped wire from 0.3 to 0.6 mm in diameter (the latter has a longer period of use, but its cost is higher), the surface of the wire rod which is processed in three or four directions, using high-speed impellers (4000 rpm per minute). It was also possible to connect the equipment directly to the blasting line drawing mills.

3.2.3. The process of blowing air from the abrasive

Chance of descaling process by means of abrasion. The abrasive (sand, alumina, etc.) is blown by means of compressed air through the outlet orifices and impinges on the surface of the rod. When using water and abrasive process is called abrasive blasting.

If we consider the above methods of non-chemical descaling, especially reverse bending mechanism, it is believed that the scale is easier to remove, having the following characteristics:

— thickness with a small number of cracks;

— transformation into FezO4 does not occur, and a large internal voltage;

— poor adhesion of scale to the iron base.

4. Terms of the production of wire rod, the formation of scale and especially its removal

The properties and dimensions of the scale forming on wire rod, depends largely on the operating conditions. Even with the same production conditions existing deviations are exempt. It is therefore necessary to determine the properties of scale from different points of view.

This section of the article for the results of studies conducted at four factories for the production of wire rod and described in the works of Muroran, Kamaishi, kimitsu and Hikari. As experimental materials used rolled mild steel (SWRM8) diameter of 5.5 mm and rods of higher strength steel with a diameter of 5.5 mm (SWRH62A), unless otherwise mentioned.

4.1. The effect of temperature on the scale rod layout and science

The temperature after the rolling the preform is determined by the heating temperature and rate of rolling and typically is about 1000 "C. If the wire to cool in air from this temperature, the formed oxide scale is very thick, which will result in production losses of metal. Therefore, among the finishing rolling stands and laying head mounted water cooling unit which cools the rod to the desired temperature in about 1 second. The temperature after cooling is usually called temperature layout.

During the passage of the workpiece through a plurality of rolling stands on the steel surface and peeled off repeatedly formed scale. Dross remaining on the wire after the step of pickup coils, approximately equal to several micrometers in thickness and is negligible.

Therefore, the temperature layout and cooling conditions after the pickup coils have a major impact on the formation of scale.

Fig. 9 shows the effect of temperature on the number of layouts to scale dense coils, is wound on the conventional technology, and fluff coils, is wound on technology Stelmor.

In the case of thick skeins cooling rate is generally low: about O, 1 to 0.5 ° ‘C / s at the center. For fluff skeins cooling rate reaches 1 to 3 ° C / s, even when the forced air cooling is not carried out.

The difference in the amount of scale shown in Fig. 9, should be regarded as caused by the difference in the rate of cooling after process vitkoobrazovaniya.

Fig. 1D shows the effect of temperature on the layout of the etching time: the higher the temperature of the layout, the more the etching time.

When the rate of cooling coils fluff is relatively high, the etching time becomes longer at temperatures below 700 ° layout ‘C. Fluff coils cooled at a higher cooling rate, show better etched than the dense skeins.

The mechanical descaling show an inverse relationship. The higher the temperature of the layout, the more the metal surface is cleaned to remove scale and, therefore, less amount of residual scale.

However, tight winding at low cooling rates show only a small change in the amount of residual scale. The amount of residual scale on the dense coils, cooling at low speeds greater than that of the fluff on the coils cooled at high cooling rates (Fig. 11).

Fig. 12 (ah) are photographs of the above cases. They show that Fe2Oz exists on the outer surface of the double structure and the scale is observed at temperature higher than 800 ° ‘C Further, FezO4 formed by converting FeO, is observed at the interface between the iron base and scale even at 750 ° C."C and not observed below this temperature.

The star-shaped selection is observed in the transformed Fe3O4 FeO-stage. This tendency is more pronounced in dense coils than fluff, even at the same temperature layout.

Observations after mechanical descaling showed that the scale on the dense skeins goes flaky parts at high temperature layout in powder form at low temperature layout. In the case of rolls of fluff scale usually goes in the powder state. However, as part of the flaked powder caught at high temperature layout.

4.2. Influence of surface roughness on the wire rod descaling

Quality descaling, as discussed above, depends on the amount and composition of scale. However, it was found to influence the mechanical descaling method for rolling rod.

When winding a wire rod for conventional winders (Edenborna type) compared with coilers rolled without twisting (Garret type or vitkoukladchika Stelmor) difference was observed in the dross adhesion to the steel base, which is due to the difference in the surface roughness of the rod.

Fig. 13 shows the relationship between surface roughness and properties of the wire rod descaling.

Surface roughness rod has a great influence on the mechanical descaling method: with a smooth surface go large flaky particles.

On the scale removal by etching the surface roughness affects rod slightly.

4.3. Influence of cooling conditions on the descaling

Experiments conducted with the wire rod to determine the influence of cooling conditions, such as temperature layout and degree of density of the skein, the properties of the descaling demonstrated that fluff coils exhibit good etchable with layout at low temperatures and good mechanical descaling with the layout at high temperatures.

Thus, the cooling rate is a very important factor in the process of descaling.

Wire rod more than 14 mm in diameter has high rigidity and can not be wound using a winder profiled Edenborna system. She wound up with the help of varietal Garrett coiler system. So inevitably arrive thick hanks and it is impossible to achieve the required cooling rate.

Consequently, measures have been taken such as cooling fan air after coiling. However, it is necessary to achieve more efficient cooling conditions, and therefore the research conducted in the laboratory using a mild steel rod.

Wire rods 5.5 mm in diameter was polished using abrasive and heated in an annular furnace in an argon atmosphere. After the end of the argon treatment rod was cooled by means of various types of forced cooling and investigated.

The cooling mode used in the experiment is shown in Figure 14. The time at temperature before cooling corresponds to the time required for dense winding coils, and the transport time to the forced cooling apparatus.

Fig. 15 (a, b) shows the amount of scale on the cooling conditions. During work it was found that the higher the cooling start temperature, the longer the holding time at this temperature, the lower the cooling rate and the greater the amount of dross.

Fig. 16 shows photographs of (ad), showing the typical structure of the scale. At a temperature of 850 ° C and above FezO4 film becomes thicker, and Fe2Oz observed on the outer surface. Then a thin film FezO4 clearly evident at the interface between the iron base and scale.

Fig. 17 shows the graph of the effect of the cooling start temperature, and dwell time in the etching as a functional measure of the number of scale. At a temperature of 850 ° C and above, when the retention time exceeds 1 minute, the surface Fez04 thickens, despite the small amount of dross and etched noticeably deteriorates.

At a temperature of 800 ° C or below, even if the holding time increases, the film becomes thicker only FeO, but the film thickness does not change FezO4. Probably for this reason etchable not deteriorate as much as at 850 ° C and above. Etched worsens when an increasing number scale.

However, the quality of etching is also low when the amount is too small scale. Minimum pickling time is obtained when the amount of the scale varies from 1 to 1.5%. Tsunemi and Fujita [11] have also described this phenomenon.

When the scale becomes thin, the internal stress therein becomes smaller (which is manifested in a stronger molecular attraction and cracking) and the plasticity of the scale increases.

An interesting observation is that the quality of the purification scale during etching depends on the amount of dross. Dross tends to descend in the form of a flake particle, when it is thin, and in the particulate state, when thick.

Fig. 18 shows the effect of temperature at the end of cooling on the quality etching. At a temperature of 300 ° C and higher significantly in FezO4 conversion FeO. FezO4 remains on the surface after etching in the form of fine particles. Thus, the quality of the etching is not the best.

Fig. 18 also shows the result of isothermal transformation. Initially scale was cooled to ambient temperature, so as not to cause a conversion in FezO4 and then heated again to cause isothermal transformation into FezO4. Fastest conversion was carried out at a temperature of 400 ° C.

This indicates that cooling to 250 ° C is necessary to prevent the transformation of FeO to Fe3O4.

Fig. 19 presents photographs depicting the scale before and after isothermal transformation. At a temperature of 300 ° C can be observed uniformly dispersed allocation transformed Fe3O4. At a temperature of 400 to 500 ° C can be observed turned Fe3O4, which is dispersed unevenly across the surface, and a plurality of discharge converted Rez04; also observed on the exterior of the film residual FeO. The film evolved Fe3O4 is observed at the boundary between iron base and scale. The existence of Fe304 at the boundary between iron base and scale theory denies peroxidation due to the introduction of oxygen into the microcracks and confirms the theory of transformation proposed by J. Bodom [12].

Fig. 20 shows the effect of cooling rate on the quality of the etching. The higher the cooling rate, the better the etching. However, at 1 ° C / s and higher quality etching does not change, and there is no point in increasing the cooling rate above this level.

Fig. 21 and Fig. 22 shows the effect of cooling rate on the quality of mechanical descaling. When the cooling rate is 1 ° C / s or higher, the difference in temperature before cooling has only a small effect. At a lower rate of cooling effect of temperature before substantial cooling, and the lower the temperature, the worse the quality of mechanical descaling. When this temperature exceeds 850 ° C, and the cooling rate is low, mechanical descaling quality decreases and remains on the surface of the black powder, possibly due to the fact that the amount of Fe3O4, formed at the boundary between the substrate and the iron oxide scale increases. Greatly influenced the thickness of the scale, and the thicker it is, the better quality of its mechanical removal. However, the desired amount of oxide scale is about 1% at a cooling rate of 1 ° C / s or higher.

5. Conclusions

Factors that affect the quality of the descaling were studied by numerous studies. These factors do not act separately from each other. They act together to intersect and influencing each other. However, when considered theoretically individual factors based on their functions and operations that can be divided as shown in Table.

Scale thickness

If the scale is gradually dissolving on the surface, a thin oxide scale has the best quality of etching. The existence of cracks in the oxide scale also affects the quality of etching, if the scale start to clean at the boundary between the substrate and the iron oxide scale and the greater of these cracks, the better the quality of the etching. When slag is thick, it is increasing its strength and on its surface there are fewer cracks. When the scale is thin, its strength is weak and cracks are easily formed. However, too small a scale thickness may increase ductility and reduce the scale of its internal stress. This leads to fewer cracks.

Fig. 23 shows the relationship between the number of cracks and size of parts to be cleaned of scale. As mentioned above, the scale goes flake particles by etching if it is thin, and the mechanical descaling — when thick. Also, the above mentioned conditions of the quality of etching. The reason why a thick dross coming in powder form in pickling, the following: Select Fe or FeO transformed into Fe3O4 and dissolves first, and then the process proceeds to dissolve the surface by destroying scale.

The reason that fat scale offering the best quality when mechanical removal is the internal tension, which is reflected in the voltage at the boundary between iron base and scale. The number of cracks and exerts its influence. The thicker the scale, the less the number of cracks and the greater the distance between the cracks.

Thus, the total tangential tension in each flake becomes larger scale and purified under the influence of small bending stresses.

The surface roughness of iron base

From the standpoint of the major factors smoother surface than wire rod, the better the etching. On the other hand, the roughness has a large influence on the quality of mechanical descaling. When the iron base is smooth, mechanical descaling quality is pretty mediocre.

When there is at the interface between the iron base and scale irregularities in the processes of cooling and bending cracks. This results in less shear stress at the interface.

Fig. 24 schematically illustrates the formation of cracks during the existence of irregularities at the boundary.

Composition Scale

The lower the content of Fe3O4 and Fe2Oz, the better the quality of the etching. Consequently, the quality of etching will be low at temperatures above the pickup coils 850 ° C at which FezOgt thick layer 4 is formed on the outer side of the scale.

For the same reason, the quality of etching deteriorates when FeO is converted into Rez04. Particular attention should be given to fine-grain Rez04, which remains on the surface after etching a fine substance and makes the surface of the rod blackish.

The reason FezO4 film formed at the interface between the substrate and the iron oxide scale is explained by the following reaction:

4Feo -gt; Fe3O4 + Fe or

(1 — 4y ‘) Fe1-yO -gt; (1 -4y) Fe1-y’0 + (y-y ‘) Fe3O4.

Internal stresses in the scale formed by the difference in thermal expansion coefficient between the scale and Fe (Fe superimposed on most of the narrowing), which is a compressive stress, and detects the maximum intensity at the boundary.

Therefore, it is considered that the response is correct (Fig. 25). The conversion is also continuing with the outer film FeO. This apparently is because FeO Fe contain more defects, when it is removed from the rail base in the art exists Fe3O4 crystal-type structure.

The reason why the Fe3O4 is formed at the interface when the scale thickness becomes larger may be explained by the fact that the larger the scale thickness, the greater the internal stress. As mentioned above, the transformation of Fe304 to reduce internal stress, and hence degrades the quality of mechanical descaling.

Vitkoobrazovaniya temperature has a big influence on the composition of scale. At temperatures above 850 "With Fe304 layer becomes thicker and increases the amount of dross. Consequently, vitkoobrazovaniya temperature higher than 850 ° C is undesirable. It is advisable for a small amount of scale etching. An appropriate amount of the scale is about 0.5% at a temperature below 750 ° C and about 1% at a temperature of from 800 to 850 ° C. For mechanical descaling enough scale about 1% if the temperature vitkoobrazovaniya somewhat higher and the cooling rate is high enough.

Cooling at temperatures below 600 ° C after vitkoobrazovaniya very important to prevent the transformation of FeO to Fe3O4. The cooling rate higher than 1 ° C / s is desirable for the etching and mechanical descaling.

The surface roughness of wire rod has a great influence on the quality of mechanical descaling. Therefore, it is important to monitor the condition of the rolls.

References

1. N. J. Engell: Arch Eisenhuttenw., 2 (1957), 109.

2. G. Chaudron and H. Forestier: Acad. Sci., 178 (1924), 2173.

3. WA Fischer, A. Hoffmann and R. Shimada: Arch Eisenhuttenw., 27 (1956), 521.

4. T. Shiraiwa and H. Matsuno: Sumitomo Metals, 19 (1967), 33.

5. K. Takagi: Tetsu-to-Hagane, 50 (1964), 637.

6. M. H. Davies, MT Simnad and S. E. Birchenall: J. Metals 3 (1951), 889.

7. J. Raidassi: Acta Met., 6 (1958), 184.

8. S. Garber and GM Sturgeon: Wire Ind., 3 (1961), 257.

9. H.J. Engell: Z. Physik. Chem. N. F., 7 (1956), 158.

10. Mechanical Descaler Committee: J. Japan Soc. Tech. Plas., 19 (1978), 661.

11. N. Tsunemi and M. Fujita: Sumitomo Metals, 18 (1966), 35.

12. J. Baud, A. Ferrier and J. Manenc: Mem. Sci. Rev. Metall., 75 (1978), 371.

A comparative study of the effects of static strain aging low carbon steel under different schemes preliminary deformation

Gul YP, k. M. Sc., Prof., Ivchenko AV, r. T. N., P. n. s., National Metallurgical Academy of Ukraine

1. Statement of the Problem

eleven. Strain aging (DS) became generally regarded as a negative phenomenon, and therefore the study of DC, in most cases have a practical purpose of weakening or elimination of the process. At the same time fixed by hardening effects DS can be used in combination of various hardening treatments.

The positive effect of the use of the DS assumes, of course, save in aged condition of sufficient ductility and toughness. In the literature, noted the possibility of using the DS became covered in a very small degree, so the actual conduct of relevant research.

Achieving the goal of a positive effect of the use of the DS in a complex hardening treatments, which may find practical application in the production technology of cold valve diameter less than 6.8 mm requires the following tasks.

12. Determination of optimum schemes of cold deformation, which must meet the following requirements: a) to ensure the maximum effect of hardening in the DC while maintaining the necessary ductility; b) the execution of a) with a relatively small degree of cold deformation; c) providing technological possibilities for the practical implementation of the schemes of deformation in production lines finish fittings.

13. Modes DS must meet the requirements specified in paragraphs a) and c), the resulting set of properties as a result of cold deformation and subsequent DS should have sufficient stability, taking into account the effect of process steps in the manufacture of zhelelezobetonnyh designs.

2. Materials and methods study

As research material used hot-rolled wire of 6.5 mm diameter steel 1kp. Selection of the steel due to its relatively high ductility, high propensity to DS, as well as the possibility of its use for cold-deformed reinforcement.

In fact, for the common areas of research, this steel can be considered as a specific model for testing the material modes of cold deformation and DS.

As the cold deformation schemes using uniaxial tension, torsion and active cyclic torsion. In the latter case, the torsion performed using a different number of cycles (N) with varying amplitude cycle (a). Selected schemes deformation significantly different:

— on the degree of stiffness stress state; This characteristic is defined as the ratio of the maximum normal stress given to the maximum shear stress and tensile is equal to 2, and less than 1 in torsion;

— on the distribution of deformation of the deformable cross section of the sample: a relatively uniform for uniaxial tension and uneven, with the active and especially the cyclic torsion;

— largest non-equilibrium concentration of vacancies produced during cold deformation: the maximum concentration recorded under cyclic loading.

Warp to the DS for the above schemes was carried out on varying degrees of deformation (s). The choice of the degrees of deformation was determined not only produce different average dislocation density, but different dislocation structure, which naturally greatly affects the resulting properties after the cold working or after the cold deformation and the DS.

Choice of the strain with the above is shown in Fig. 1 as an example diagram of uniaxial stretching.

The first corresponds to the degree of deformation strain on the yield plateau, that is, after the completion of the process of distribution macroplastic deformation of the sample volume to produce an irregular dislocation structure of the «forest» dislocations and dislocation plexus.

The second stage corresponds to approximately one third of the plot of strain hardening (control) in the field of uniform strain. According to early data obtained at this stage is completed the formation of a cellular dislocation structure with a «broad» dislocation walls and weak disorientation dislocation cells.

The third degree of deformation (approximately two-thirds of land control) corresponds to a deformation in mature cellular dislocation structure, leading to the «thinning» of dislocation boundaries and increase the disorientation between the dislocation cells.

In order to obtain comparable data in the case of torsional deformation after a certain number of turns of the active torsion and cycles with a given amplitude under cyclic torsion obtained stress-strain diagram, yield strength which characterized in terms of normal stress corresponding amount of deformation resistance achieved by the active or cyclic torsion .

Based on the data obtained the respective built diagram where axis voltage value delayed tensile stress and strain along the axis — corresponding to the torsional deformation characteristics. In such diagrams chose similarly Fig. 1 corresponding to the degree of deformation in the active and cyclic torsion. For the universal characteristics of the degree of deformation under torsion, which does not depend on the length of the swirl of the sample was used a so-called reduced angle of twist as the ratio of the angle of twist to the number of sections (n) sample equal to its diameter at the working length of the sample (α, ° / n).

Mechanical properties were determined by uniaxial stretching directly after cold deformation carried out in the above manner, as well as after cold working, followed by DS at 100 ° C h -1 and 250 ° C — 30 min., Separating the contribution to the mechanical properties of cold deformation and DS .

3. Results and discussion

3.1. Comparing the resulting properties after deformation in various patterns.

Experimental points relationship between the obtained level of hardening (yield strength — ReH) and the level of plasticity (of uniform elongation — Ap) for all circuits used strains are well described uniform dependence (Fig. 2-3).

By analyzing the ratio of the hardening effect (for ReH) and ductility (for Ap), which is shown in Fig. 2, we can draw the following conclusions:

1. In the scheme used degrees of deformation strain ascending strengthening effect are located as follows: cyclic torsion — tension — active torsion. Unfortunately, in the same manner, a decrease retentive metal plasticity, namely, the maximum ductility is fixed after cyclic torsion, intermediate values ​​- after stretching, and the minimum — after an active torsion;

2. Cyclic torsional strain, leading to hardening effect on m approximately 100 MPa hardly reduces the ductility (uniform elongation remains at the level of 22-23%). With increasing number of cycles and increase their amplitude is fixed with a slight degree of hardening of the fall of ductility (see. Fig. 2);

3. Deformation of stretching (in control) gives rise t 130 MPa (ε = 13%) and 200 MPa (ε = 23%), which is accompanied by a significant drop Dp, respectively, and 5 to 15%. Warping torsion active in the field of strain hardening leads to unacceptably low drop Dp. Thus, the transition from a cyclic torsion stretchability, and then to the active torsion is substantially increased the rate of decrease ductility.

3.2. The strain aged condition of the r = f (δp) in Fig. 3 have the same character, similar to that described above in Fig. 2.

However, there are significant quantitative differences: as the DC leads to hardening in comparison with the pure strain influence on the properties, the curves in Fig. 3 are arranged somewhat higher compared with the curve in Fig. 2.

At the same time, the interval of variation values ​​5p narrows due to falling values ​​of the characteristics at low degrees of strain and growth values ​​5p at high degrees, which is especially pronounced for the active circuit torsion. Therefore, the intensity changes with increasing value from the values ​​Dp in the DS-state increases.

Features of influence on the received DS ratio of strength and ductility are expressed as follows:

— after using the maximum degree of deformation of the active torsion and tension values ​​from reaching the level of 500 MPa at a satisfactory value 5p; revealing at the same time that stretching provides a DC level from above with the values ​​of uniform elongation is almost three times larger than the active torsion;

— almost all the investigated schemes deformation at small degrees of deformation produce similar effects: a relatively small hardening at the DS with a significant drop of plasticity; for example, an active twist on 4,5 ° / n gives an increase in the yield strength of 20-30 MPa, DC, and a drop in uniform elongation of 9%; stretching by 2% (in the yield plateau) gives approximately the same effect; DS after cyclic torsion (5 cycles with an amplitude of 2.25 ° / n) growth at 20 MPa ReH Dp decreases by 13%.

Thus, the process of DS, carried out in the presence of immature regular dislocation structure, generally a negative effect on the mechanical properties of the resulting complex.

3.3. Table. 1-3 shows data characterizing the contributions actually work hardening effect and DC circuits and in different degrees of cold deformation. Analysis of the data in the above table reveals the influence of both the general laws of the intensity of the deformation effects of various schemes of deformation and a number of features that influence.

— for all the investigated schemes deformation in varying degrees pronounced tendency to reduce the effect of the relative contribution to the total DC change properties under deformation and aging.

At the same time, there were significant quantitative and qualitative differences sometimes changes in properties under DC depending on the degree of deformation and schemes:

— in order of increasing the contribution of the DS in the hardening effect of T studied the scheme of deformation are located as follows: active torsion — cyclic torsion — tension, when the most of the degree of torsional deformation contribution DC to gain from is only 7%, while the tensile and cyclic torsion — 30-40%;

— when assessing the effect of strengthening the contribution of the increase in the tensile strength of the DS for all degrees of tensile deformation of 100% of the cumulative effect of hardening, and with the increase of deformation degree from 2 to 23% increase in tensile strength also increases nearly an order of magnitude;

— under cyclic torsion contribution to the total DS hardening effect on 0 V is in the range of 60-90%, that is a very significant;

— with active torsion of the maximum contribution to the total DS hardening effect on 0 in 30%.

The above data suggest that the combination of stretching the cyclic torsion can significantly increase the contribution of the DS in the cumulative effect of hardening.

It is significant that the decrease in ductility at DC maximum at small degrees of deformation and stretching of the active torsion, and with increasing degree of deformation under load of these schemes fall plasticity at DC does not decrease, but changes in the direction of increasing; DS after cyclic torsion leads to the most significant drop in ductility which progresses with increasing number of cycles.

conclusions

1. The scheme investigated strain has a significant impact on the range of different mechanical properties of low carbon steel, formed by cold deformation and subsequent strain aging.

2. The effects of strain hardening increases in the order of the cyclic torsion — tension — active torsion.

3. The maximum effect hardening DS observed after tensile deformation and cyclic torsion.

4. Strain aging after small degrees of deformation, irrespective of the investigated schemes deformation gives comparatively small effects hardening, accompanied by a significant drop in ductility.

5. The level of the yield strength of 500 MPa for steel PCP provided the total influence of cold deformation and aging at a satisfactory ductility under tensile deformation.

6. promising for further research can be considered the use of various combinations of stretching the cyclic torsion.

Thermokinetics collapse of supercooled austenite steel 30G1R

Hood VP Ivchenko AV, Sobolenko MA, Kokashinskaya GV, National Metallurgical Academy of Ukraine

UOM in [1, 2] stated that the increase of production efficiency for cold heading steels can be achieved by using energy-saving technologies speed nodularisation. For example, steel 20G2R the possibility of obtaining a normalized structure and properties tackle the implementation of High Speed ​​annealing duration of 600 seconds.

Working modes annealing steels of different chemical composition makes it necessary to study the regularities of decomposition of austenite at various thermo-kinetic conditions of cooling.

The purpose of this work — the construction of thermokinetic chart collapse of supercooled austenite perspective [3] steel 30G1R because data on characteristics of structure of steel during the decomposition of austenite in the known information sources available.

Material for the study served as a rod of steel ZOG1R 6.5mm the following composition: C — 0, 30%; Si -0,31%; Mn — 1.02%; S — 0, 007%; P — 0.024%; Al — 0.020%; Ti — 0,017%; B — 0.0007%; N — 0.016%.

To study the critical points and the kinetics of decomposition of austenite using differential thermal method, complete control of the hardness and microstructure analysis.

The microstructure of the metal produced on the light microscope metallographic Neophot-2, and the hardness of the samples was measured on the device Vickers (type TP-7R1).

The research results of the critical points following provisions: Ac1 = 725 ° C, and ASP = 795 ° C.

Fig. 1 is a diagram of steel thermokinetic 30G1R.

Analysis of patterns of decay of supercooled austenite steel showed that the conversion for diffusional mechanism to form martensite (Fig. 2a) occurs at a cooling rate of not less than 250 ° C / sec. The temperature of the martensitic transformation start point corresponds to 355 ° C, a hardness of decomposition products — 631 HV.

By reducing the cooling rate below a critical during cooling of time to partially leak diffusion processes to form up to 20% bainite (Fig. 2b, c), which leads to lower hardness of 365 HV. A further lowering of the cooling rate (up to

40 .. .30 ° C / s) is more intensive diffusion processes with the release over a temperature range

500 ° C .. .550 structurally free ferrite (Fig. 2d), which leads to a significant reduction of hardness (up to 222 HV). The number of the intermediate type of structure reaches the maximum (65%).

Formation of pearlite in the steel 30G1R occurs in the temperature range of 500 … 600 ° C at cooling rates of less than 20 ° C / sec.

With a decrease in the cooling rate the amount of ferrite and pearlite in the steel structure gradually increases, and the amount of bainite and martensite decreases and the cooling rate of about 1 "C / s ratio of these structural components is respectively 60%, 35%, 4% and 1% (Fig. 2, d-i), and the hardness of the steel with the structure — 169 HV.

Pure diffusion supercooled austenite transformation to form 60% ferrite and 40% pearlite occurs at cooling rates 0.8 ° C / s or less (Fig. 2, k, l). Minimum hardness of such a structure is 151 HV.

conclusions

1. The critical point of steel ZOG1 R.

2. The regularities of structure formation began 30G1R the decay of supercooled austenite.

3. Qualitative and quantitative picture of structure formation in its basic parameters is typical for this class of steels, except for the lower temperature range of the pearlite transformation, which may be associated with exposure to complex micro-alloying titanium, boron, aluminum.

References

1. KolpakV. P. Gul YP, Ivchenko AV, Kokashinskaya GV Energy-saving technologies for the production of rolled cold forming and wire Special // «Hardware», 2006, №1, p. 25-27.

2. MV Bobylev, Greenberg EM, Zakirov DM Training structure in electroheat steels used for landing high-strength products // «Steel», 1996, №11, p. 54-60.

3. Hook VO, Semenov A. The choice of material for the manufacture of high-strength fasteners // «Hardware», 2002, №1, p. 41-45.

Criteria for selecting the material and process parameters for the production of wire for cold forging

Sokolov AA, Artyuhin VI

steel grade

Selection of the grade of steel for the production of fasteners is performed in accordance with the technical requirements of the product standard. Steel grades for fasteners Hosh identified as the recommended standard GOST 1759.4-87, GOST 1759.5-87, DIN

267.4, ISO 898 part 2, and others. Technical requirements, chemical composition and mechanical properties are determined in accordance with GOST 10702-78, GOST 1050-88, GOST 4543-71 or specifications. Steel for the Hosh should:

1. To ensure the receipt of the product the desired shape and size with the minimum number of surface defects;

2. To ensure receipt of the required mechanical properties;

3. Be on the technological conversions in the manufacture of products.

The main factors affecting the compliance with the requirements for cold heading steel, are a method of producing steel and chemical composition, which largely determines the ability to become exposed to cold deformation. The most widely used for bulk cold forming of fasteners found: of medium (30, 35); carbon (50, 70); alloyed (12HN, 16HSN, 19HGN, 20X, 35X, 40X, 38HA, 38HGNM) and boron (06HGR, 12G1R, 20G2R, Zohra, 30G1R). This is particularly important when the content of elements causing plasticity.

The main chemical element in determining the behavior of the steel during cold forming, is carbon. Increasing the carbon content leads to higher strength and lower ductility (Fig. 1), the resistance drops significantly deforming tool, increasing the size and number of defects (cracks, flaws and the like. D.) Deteriorates clearance products [7]. Increasing the strength of the finished product without deteriorating plastic properties was made possible through the use of micro-alloyed steels. Thus the products of these steels can be heat-treatable at the higher strength class. The main alloying elements of structural steels are silicon, manganese, chromium, aluminum, and others.

Fig. 2 shows the changes in properties of the steel upon introduction of various alloying elements [7, 8]. Molybdenum, manganese and silicon reduce the viscosity of the ferrite. Chromium reduces the viscosity of the weaker and nickel increases.

It is generally known that grain refinement of steel embrittlement and decreases significantly increases corrosion resistance of steel under tension. Microalloying steels pulverizes titanium and aluminum and stabilizes grain size. Due to high affinity of aluminum and titanium for oxygen and nitrogen of microalloying provides dense ingot with fine microstructure due to a primary degassing efficiency.

The increased amount of aluminum increases the deformability of the steels. Aluminium reduces the amount of residual hydrogen. However, an excess of more than 0.03% of aluminum leads to contamination of steel by nonmetallic inclusions [7].

However, at a content exceeding 1% increases the propensity to stick to steel punching tool. Carbon and alloy steel used for Hosh, are, as a rule, to the pearlitic.

The microstructure of the steel should be fine. For forging favorable structure in which spheroidal carbides (cementite in carbon steels) are not less than 70%. The microstructure and medium-chromium steel is unacceptable presence of lamellar perlite and vidmanshtettovoy structure. The total depth of the decarburized layer (ferrite + transition zone) the mass of carbon steel with 0.3% or more must not exceed 1.5% to [9].

For the production of dowels is currently used steel grade 70 according to GOST 14959-79.

Rolled

The bulk of the rod is in the cold drawing of the wire, so are particularly important processes, that would provide rods, suitable for cold deformation with significant single and total reduction without intermediate heat treatment. The maximum effect on the structure has a cooling speed wire rod before its coiling into a compact riot. Practically rollback rod cooling conditions in the rebellion of the individual turns sharply differ. This difference is primarily in the different rates of cooling coils, which determines the duration of exposure and the metal structure. In addition, slow shutter speed metal at high temperatures promotes intensive formation of scale, which lowers not only yield, but also greatly complicates the technology of surface preparation of wire rod (mechanical descaling, pickling) for drawing.

Wire rod made from different steel grades mentioned above and subjected to a subsequent drawing process. The thus obtained preform and the wire used for the further heat treatment and disembarkation. The optimum structure for carbon steel is a fine pearlite structure (sorbitol) obtained immediately after cooling (two-stage) from rolling heat in a stream of small-section wire mill.

Wire

Ha tensile strength Rm of the wire affects the chemical composition and structure of steel, depending on the total reduction in the drawing. Modern technology of production of cold-drawn wire for cold heading, including drawing wire rod to a certain size, heat treatment and final calibration of the wire to a final diameter. The ability of steel for drawing characterized by the strain to failure or ductility after wire drawing. To evaluate the effect on the ability of the steel structure for drawing often use characteristics such as tensile strength Rm, yield strength σo, 2 and relative narrowing of φ, the number of bends and twists Nt nc.

At the heart of the hardening effect is the phenomenon of metal hardening. Work hardening is accompanied by significant structural changes, the main consequence of which is a dramatic increase in strength through the creation of numerous obstacles to the movement of dislocations in the form of fragments of crushed and chopped blocks, «forest» dislocations, vacancies and second-phase particles (cementite). Education required structure wire selects the optimal individual and total reduction.

Optimal total reduction substantially different for the blank and finished wire and defined the role of different defects and substructure at various stages of production of the wire. In cold-drawn wire detrimental effect neutralized microcracks form a cellular structure, which prevents the growth of cracks and thereby pushes the start of embrittlement, avoiding the use of large total reduction. Heat treatment eliminates substructure but retains microcracks when the austenitizing temperature is not high enough. As a result of subsequent deformation occurs under conditions favorable for the growth check cracks until it has a new substructure, reducing the supply of wire plasticity. Therefore, between the intermediate heat treatments are optimal compression to the first critical range (45-50%), when there began a massive crack opening.

The curves of changes in the mechanical properties of carbon steel wire according to the total reduction for steels with different carbon content shown in Fig. 3.

The hardening of austenitic steels increases with increasing carbon content in the metal. The curve of strength austenitic steels with the addition of titanium is well below the curve of the same strength of steel without the addition of titanium.

Fig. 4 shows the dependence of the tensile strength in the magnitude of the total reduction ratio and the size of individual reductions (15% and 30) for different types of heat treatment of the initial billet of steel wire with a carbon content

0, 5% C

These curves show that the value at a single cold working 5ed = 15% lower than the single cold working 5ed = 30% at all of the initial structure and the kinds of heat treatment of carbon wire.

Number of bends and twists at a reduction 5ed = 15% was significantly greater than at a reduction 5ed = 30%. Increasing the number of broaches (or decrease 5ed) and decreases in hardness, and increases the viscous properties (number of bends and twists, elongation and contraction in tension) [5,6].

The dependence of the properties of the wire on the size of individual reductions can be attributed to:

1) The difference between the actual temperature at different drawing single crimping (the higher the temperature, the greater the compression unit);

2) differences in the deformation.

Heat treatment of carbon wire

The heat treatment is designed to remove and recover the plastic hardening properties of the steel, and to form a structure which in combination with the subsequent cold deformation and final heat treatment provides some special, often higher strength properties of the finished products.

Spheroidizing annealing creates favorable for metal forging structure and improves the resistance of upsetting tool. Some authors argue that for cold heading should be used only with metal microstructure 100% granular perlite. [10] However, the production of granular perlite associated with a significantly increased annealing cycle, and, moreover, reliably ensure a microstructure during the annealing of hot-rolled steel is practically impossible. Spheroidal carbides are obtained at annealing temperatures in the range of 660- 770 ° C. To speed up and improve the process of the pendulum is used spheroidizing annealing, which consists in repeating heating and slow cooling around the corresponding critical point A1 (zhelezouglerod chart).

Annealing temperature, duration of exposure and the cooling method chosen in each case depending on the steel chemical composition, volume cages furnace design and t. D.

When fine grain increases resistance to deformation as grains do not have a place for crushing causing the landing process. On the other hand, coarse steel very fragile. In boron-containing steels (12G1R and 20G2R, Zohra), as opposed to boiling, heterogeneity became non-existent or very weak, these have become much cleaner on the gas composition and metallurgical defects. In the hot rolled, annealed and calibrated states boron steels have a low deformation resistance. In addition, perlitic form inclusions weakly affect their ductility [10]. Hot-rolled steel is easy spheronized. The structure of 80% or more of the granular perlite is obtained after a simple scheme and short (7-9 hours.) Annealing [10].

Planting of fasteners

Mechanical properties of calibrated drawing metal provided (if necessary — after annealing) with a degree of deformation of medium alloy steel and — 5-10%. As a result of a calibrated metal one steel grade used for Hosh, due to the microstructure and compression at drawing gets different mechanical properties.

The use of metal calibration before planting increases the resistance to deformation compared to the initial hot rolled or annealed steel.

The degree of compression during the calibration of the metal selected from the calculation:

— obtaining the desired properties stampings;

— To ensure the necessary deformability of steel without failure at Hosh to obtain the product desired shape and size;

— the availability of rental according to GOST 2590-88, close to the desired diameter at the landing.

The high strength of the parent metal complicates the process of cold forming steel. Cost-effective tool life is achieved in most cases, if the pressure on the tool does not exceed 2000-2500 MPa [1]. This is achieved if the strength of a calibrated metal rod drop-off parts for products not more than 600-700 N / mm2.

Best ductile die forging have become a relative contraction of 50-60% [7].

With the reduction of the yield ratio of Ultimate / s ductility increases. The best formability has steel pertaining ReH / σvlt; 0.65.

Note that dragging occurs after aging of the metal consists in increasing its durability and decreasing ductility.

Of particular importance for the deformability of steel for cold stamping has the size and location of surface defects, which are one of the main causes of flaws, cracks and tears.

Surface defects (cracks, sunsets, slivers, deep risks, hairline, and others.), Their education and impact on the quality of metal for cold heading described in the works in the form of generalized most common in cold forging defects and are general recommendations.

These recommendations are reflected in the requirements of GOST 10702-78. The surface quality of hot-rolled products must comply with GOST 10702-78 Group 1.

Steel should withstand the cold draft of up to 1/3 of the original sample height [5]. Maximum permissible largest plasticity degree of deformation of steel at the rein-back and landing are given in Table. 1.

When designing processes do not allow high degrees of deformation. With increasing degree of deformation of the rising voltage on the tool and the metal, thereby reducing tool life. In cold landing values ​​of specific pressure should not exceed 200-250 kgf / mm2.

References

1. Forging and Stamping. Directory / T. 3. COLD forging / Ed. GA Navrotskiy. — M .: «Engineering», 1987, 384 p.

2. Production of high-quality hardware. Kuleshov

A. Klekovkina NA, Belalov X. N. et al. Collective monograph. — Beloretsk, 1999, 328 p.

3. Pavlov AM, Anashkin AV, Arkulis GE et al. New processes and equipment in hardware production. Thematic collection of scientific papers. — M.,

1986, 86 p.

4. Nedovizy JH, Arkulis GE, Baraz RB et al. Technological advances in the hardware manufacturing industry // Thematic collection № 7. — M., 1978, 95 p.

5. Shakhpazov X. S. I. Nedovizy, Orinichev VI Production of metal products. — M .: «Metallurgy», 1977, 392 p.

6. Krasil’nikov LA wiredrawer metalware shops. — M .: «Metallurgy», 1968, 284 p.

7. GA Navrotskiy. — M.Mashinostroenie «1973, 496 pp.

8. Die forging fasteners. Design and technological calculations. Guidance Document RD 37.002.0208-90. KTIavtometiz. — Bitter,

1990, p. 2-8.

9. VA Delle alloy structural steel. — M .: «Metallurgy», 1953. — S. 2.

10. Bykadorov AT, lean VA metal for cold heading fasteners // «Forging and stamping production», №9, 1985, p. 32.

Mathematical modeling of the formation of the internal thread plastic deformation

Gurov VD to. T. N., Ltd. «PromStroyKompleks» p.

References

1. Men’shakov VM Urlapov GP Sereda VS Besstruzhnye taps. — M .: «Engineering», 1976. 167 pp.

2. Parshin VG Zhelezkov OS some effort cold forging rotationally symmetric parts. // «Proceedings of the universities.» «Iron and steel», 1980, №3, p. 86-89.

3. Gurov VD tehn. Sciences. — Magnitogorsk, Moscow State Technical University, 2004. 133 pp.

Information and Analytical Center of the Association «RosMetiz»

In mid-July on the «Plant Innovator» in the city of Belgorod, held a meeting on the implementation of cold-rolled steel class B500C reinforcement according to GOST R 52544-2006 in construction.

The meeting was attended by the project organization of the Belgorod region, representatives of the construction of the complex, experts largest steel associations such as

Moldova Steel, «Mechel», «Maxi-Group», representatives of «Severstal-metiz», Beloretsk Metallurgical Plant, Ukrainian metalware enterprises, experts from Serbia, the heads of small and medium-sized enterprises, participants of the program «Development of hardware production in Russia.»

The organizers of the meeting were: Association «RosMetiz» NIIZhB administration of Belgorod, «Plant Novator».

The main objective of the meeting — to develop together with the design and construction organizations of decisions on methods and practical arrangements for the implementation of cold-rolled steel reinforcing in the building complex of the Belgorod region. Given that the administration of the city of Belgorod in recent years has managed to create conditions for intensive development of the construction sector and has provided some of the highest in the Russian housing per capita (1 m² per inhabitant of Belgorod), the introduction of cold-rolled steel class B500C reinforcement as key and intermediate diameters will promote further development of the program, not only the city of Belgorod, but the whole of the Belgorod region in general. It is the positive effect of the introduction B500C intermediate diameters in the construction pointed head of administration (mayor) of Belgorod

VN Potryasaev at a meeting with the organizers of the meeting, held in the city administration. «We will provide all possible assistance to this project, and the Association» RosMetiz «should continue its endeavors,» — he said in the conclusion of the meeting.

The main problem of implementation in the construction of cold-rolled steel class B500C reinforcement of basic and intermediate size is the lack of a complete regulatory framework and therefore limited its use. If you do not create a system implementation B500C, the expansion of production may drag on for years. Association «RosMetiz» and a group of experts developed a unique program NIIZhB implementation of this reinforcement in construction.

In the first stage, the program focused on regional implementation, B500C, when all the problems of its use in construction solved at the local level.

It is actively working with regional design and construction organizations to launch a mechanism would allow the use of B500C.

What is the essence of this program?

1. Construction and design organizations get the whole set of normative documents on the direct use of B500C.

2. If necessary, construction organizations receive permission for a direct replacement valve class A-III (GOST 5781) and A400 (STO AISU 7-93) at rebar B500C same or lower (intermediate) diameter.

3. In the interest of a construction company or companies for the production of JBK recalculated by experts NIIZhB project or project organization to complete replacement of the reinforcing elements of a design using all the advantages of cold-rolled steel class B500C reinforcing basic and intermediate diameters. It is possible to obtain the maximum economic benefit from use of this product.

Association «RosMetiz» and is actively developing projects NIIZhB production of cold-rolled steel class B500C reinforcement. The design is developed and launched into production lines for the production of B500C with advanced technological capabilities.

The new line will reduce the requirements for low carbon wire rod, used for the production of rebar B500C class. This will enable the group to expand the raw material suppliers and manufacturers to provide all the metal.

There are plans to carry out the work on the «Plant Novator», and in September held industrial tests of a new line in the Moscow region.

Today, the «Innovator Factory» is the industrial production of rebar B500C diameter of 6-10 mm in coils. Even this year, begin development of valves with a diameter of 12-14 mm and the production of reinforcement bars in the dimensional.

We can say that the Belgorod «Plant Novator» has become a regional center for the implementation of rebar B500C in the building, and the main organizers of the project: Association «RosMetiz» NIIZhB and Moldova Steel factory- make every effort for the success of its implementation.

Specifics of welding wire Sv-wire 08G2S

Kostyuchenko VP, Taranets MA, Degtyarenko 3. A., Shamin SA, Kuzyakov VD

Therefore, preference was given to the continuous-flow type drawbench equipped with computer program control process of drawing.

For the drawing rod in the maximum diameter of the workpiece

— the use of anti-corrosion lubricant kalibrovki- seals copper coating.

Mark G4SM (SG3) is an analog of the brand Saint-08G2S. Installation descaling possible to reduce the amount of residual scale on the wire rod to 0, 6 kg / t.

Today, the company produces more than 500 tons of copper-coated wire diameter

0.8-1.6 mm per month for modern welding equipment used in the machine and shipbuilding, on evrokasseta K300 according to DIN 8559.

Some features of the production and use ,; wire type W St. 08G2S

Medyushko VA

In this connection, a wire rod on the macro and micro levels are increased requirements for the set of physical, mechanical and technological properties.

As an example, some information about the process parameters of the manufacturing process of welding wire brand IS10 / W10 Hungarian production plant ISAF KFT Italian concern ISAF.

Wire drawing partial deformations not allowing exorbitant effort of drawing, allows to get ready for further processing the wire to ensure the requirements of Euronorm by the absence of helicity.

The deformation mode of hardening wire drawing process is shown in Fig. 1.

Wire with such indicators of strength is characterized by sufficient stiffness, the ability to freely pass through the channels feeders semi-automatic welding equipment in and out of the burner is strictly linear.

Copper thus showered, scoring feeding channels and elements of the current supply, the welding process due to the loss of stability of the arc becomes unstable or impossible, and the fruits of this in the form of unfair claims from consumers reap the manufacturers or suppliers of welding wire.

It is believed that increasing the thickness of the copper coating increases the likelihood of his detachment and shedding from the surface.

References

1. A. Razorenov O. Krivorotov VI Medyushko V. Analysis of the quality of the welding wire by statistical evaluation of the stability of its chemical composition // «Industry», №2 (49) / 2007, p. 76-77.

2. Novozhilov NM et al. Effect of technology of wire Sv-08G2S its welding characteristics // «Welding production», №7, 1974, p. 26-27.

3. Voropai NM technological properties of copper-coated wire // Materials of the report at a conference on welding. — Kyiv, 2000.

4. Rodichkin IA method for manufacturing a copper plating wire // «Welding production», №3, 2002, p. 41-43.

Goritsky VM, Guseva IA, Hooke VO Zakharov VV

01.2008 of the new GOST R 52643-2006 [1], the problem arises of evaluating the quality of high-strength fasteners supplied to the domestic market by foreign manufacturers and is used in construction and engineering.

The GOST R 52643-2006 attributed to the high-strength bolts bolts of strength class 6.8, 8.8, 9.8, 10.9, 12.9. It should be noted that under the current international classification for high-strength bolts are products temporary resistance (Rm) greater than or equal to 800 MPa.

Unfortunately, the domestic hardware production does not fully ensure consumers heat-treated high-strength fasteners strength classes 9.8-12.9, especially diameters up to 20 mm classes 10.9 and 12.9 and 30 mm in diameter over the same strength class, although the need for them today is quite large.

Due to this fact in the domestic market there are many companies that supply high-strength fasteners imported.

In these circumstances, ensuring the reliability of bolting urgently requires evaluation of the quality of imported high-strength fasteners. Given the harsh climatic conditions of Russia, high strength bolts must be guaranteed by brittle fracture. Thus, according to [2] galvanized bolts M10h160 labeled 8.8, produced in Switzerland and intended to be fixed microwave antenna has collapsed during installation.

Fractometrical analysis of brittle fracture of the bolts revealed that the high propensity type 40G2 steel to brittle fracture is caused by the appearance of tempering brittleness of the grain boundary (65.7% share of the reduced intergranular fracture rennogo).

Since the hardness of the bolts above the upper limit of allowable GOST 1759.4 bolt class 8.8 of values, the development of the grain boundary brittleness of steel was due to a holiday in the temperature range of irreversible temper brittleness (320-380 ° C). The most common cause of failure of the bolt is a temperature deviation from the optimal holiday.

Table. 1 shows the chemical composition and mechanical properties of some party imported high-strength bolts, which have been subjected to complex research on their compliance with the requirements of GOST R 52643-2006.

The parties examined the bolts included bolts, which were not detected cracks, scale, rust, burrs, dents and rock faces on the thread. These requirements for the external surface of the bolts according to GOST R 52643-2006. Table.

1 also shows the results of the mechanical properties of bolts which must be provided in the acceptance tests. Bolt having a protective coating, provided the data for the thickness of the zinc coating.

Key: «+» — satisfied; «H» — is not defined; «» — does not meet the requirements of GOST 52643-2006 (GOST 22354-77).

As can be seen from Table. 1, for the majority of the parties supplied bolts coated and uncoated mechanical properties of bolts meet the requirements of GOST R 52643-2006. However, there are cases of non-compliance by one or more mechanical properties.

In this situation when the bolts have satisfactory performance on the whole range of destructive testing and coefficient of twist, however, do not meet the standard values ​​of hardness (see. Line 2 tab. 1 M27h90 bolts, strength class 12.9).

After the mounting bolts have found Metal tendency to brittle fracture in the next 2-5 days. There are cases when failure observed after 4-15 days after the tightening of the bolts, fractographic analysis of breaks in the area of ​​stable crack growth showed that the proportion between the grains of destruction reaches 37.2%.

The latter indicates the development bolts M27h90 delayed brittle fracture.

Studies have concluded that the cause of premature failure was the vacation irreversible temper brittleness range of 350-380 ° C. With this agreement overestimate steel hardness to 460HV 435HV against GOST R 52627-2006 (until 01.01.08 GOST 1759.4) bolt strength class 12.9.

The chemical analysis of metal bolts, experienced slow brittle fracture, showed that they are made of steel 42SgMo4, 4140 and SCM435, ie do not correspond to the chemical composition of steel 20H2NMTRB recommended by GOST R 52643-2006 bolt strength class 12.9.

This Standard does not prohibit the use of other steels, however, it provides for the implementation of the additional requirements for resistance to delayed brittle fracture and crack bones.

The above case of premature brittle bolts mounted structures confirms the validity of such claims.

As can be seen from Table. 1, the mechanical properties of the investigated high-strength bolts in the main correspond to requirements of GOST R 52643-2006, but in some cases, these bolts are incomplete compliance of one or more mechanical properties.

A similar pattern is characteristic for high-nuts (Table. 2). As can be seen from Table.

2, all the investigated party nuts in chemical composition and hardness meet the requirements of GOST R 52643-2006.

However, there are cases of defective manufacturing, nuts, for example, revealed circumferential and longitudinal cracks on the bearing surfaces of nuts.

During metallographic control on the support surface of nuts M24, M27 and MLO identified longitudinal cracks to a depth of 0.15 mm, which form a complex in the area of ​​stigma trajectory and subsurface cracks size 0,25×0,15 mm.

Annular crack depth of 0.20 mm are also found on the surface of the supporting nuts, are arranged at an angle of 45 ° to the supporting surface. As a result of the quality control of nuts production firm was terminated.

On other investigated batches of imported nuts by visual inspection of unacceptable surface defects: cracks shear cracks from scratches, traces of tools, rolled blisters, damage the thread in accordance with GOST 1759.3-82 — have been identified.

It should be noted that for all the investigated parties bolts with nuts and washers, hot zinc coating having a coefficient of twist Ks varied in the range from 0.13 to 0, 18, that meets the requirements of GOST R 52643-2006 (0.11 Kz0,20) .

For lots of the zinc coating of fasteners without tightening factor varied in the range of 0.14-0.17, which also meets the requirements of the new GOST R 52643-2006 (0.14 Ks 0.20).

In general, describing the investigated party fasteners should be made on the quality of products made by PEINER UmformtechnikGmbH (Germany).

With high mechanical properties of the complex, bolts and nuts are hot zinc coating thickness of 45-126 microns (Table. 1 and Table. 2).

Hot zinc coating uniformly covers the ridges and the base of the teeth of the threaded portion of high strength bolts (Fig. 1, b).

The microstructure of the coatings of bolts and nuts M36 shown in Fig. 2. At the interface of the coating matrix of bolts and nuts not revealed any defects.

Validity protective zinc coating greatly depends on the aggressiveness of the environment in which the structure is operated (Fig. 3). Even in conditions of the marine and industrial environments term reliable operation of bolting when the thickness of the zinc coating of 50 microns is 10-15 years, and in the urban environment — for more than 20 years.

References

1. Standard R52643-2006. High-strength bolts and nuts, and washers for steel structures.

2. Goritsky VM, Khromov DP quality steel bolting facilities, designed and constructed by foreign companies // «Industrial and civil construction.» 2000, №5, p. 44-45.

Driving landing heads rod fasteners

Napalkov AV, r. T. N.

2. Round, countersunk, countersunk, cylindrical, hexagonal head Phillips and / or flat-head screws with internal four-, six- or dodecahedron (screws, self-tapping screws, wood screws, special parts);

3. With a square or hexagonal head (screws, bolts, screws and special parts);

4. With a square, hexagonal, dodecahedral head and flange with flat or serrated base;

5. With the deepening of the head or in the head with a profile of the type TORX® (star-shaped profile, which is gradually replacing the hex and twelve-head);

6. asymmetric head (with unilateral or bilateral flattened);

7. A head forming a T-shaped structure of the fastener;

8. With the ring structure of the head of the «Eye-» bolts;

9. With the special design of the spherical head type, conical heads, heads, combination of 2, 3 or 4 elements.

002.0208-81 [1].

2,5d [2]. For two strokes in a matrix formed by the head of medium size Dgol 3d.

In case the head part has a size Dgol gt; 3d, changing landing scheme.

1.

2. Shaping the head flange double cropping;

3. Shaping the head flange due to operations redutsirovki polyhedron and local rainfall flange.

These conditions are valid for manufacturing parts with high hexagonal head portion (Ngolgt; 0,8 … 1,2S).

For heads with hexagonal (or polyhedral) of the head, the height of which Ngollt 0.85, use the scheme shown in Fig. 5.

Matrix is ​​identical to the matrix used to trim the hex head bolts.

8).

1. Landing polyhedral heads and cuts, using appropriate trimming matrices;

2. The landing of the head with the bending axis of the details;

3. Formation of the head in two planes landing like «Eye-» bolts.

1. 002. 0208-81. Forging fasteners. Design and technological calculations. — Gorky, 1983. — 249 p.

2. Auslegung der Werkzeuge und Entwicklung der Formteile fbr Mehrmatrizen-Kaltumformer. National Machinery Co. Tiffin, Ohio, 1996. — 320 s.

3. Marc Van Til. Flange bolts // «Hardware», №1 (14), 2007, p. 70-72.

4. Amirov, MG, Gare RK, Nurkan IB 14-16.

5. Skvortsova S. candidate. tehn. Sciences. — Magnitogorsk, 2006. — 20 s.

6. Proceedings of the Fourth All-Russian Conference metiznikov. Moscow. October 23-24

2007 — 33.

7. Forging and Stamping Handbook.

Self-fasteners

Bolts and screws rezbovydavlivayuschie

Overview branded designs

Khokhlov EN, Nizhny Novgorod

This fact contributed to the search for new technical solutions.

Fig. This is the most frequently used design.

On the locking portion of the value of roundness to the smallest.

The development was entrusted to branch institutes and KTIavtometiz plant «Krasnaya Etna». Release screws started in 1987, and they soon found their consumers.

11.5 million. Pcs. in 2003 to 30 million. pcs. in 2007, including their use in cars, «GAS» increased from 5 to 14 million. pcs. in year.

Carving full height throughout the rod consists of three parts: lead-caliber and principal.

There are seven automotive industry standard OST 5-88 … 37,001 .31 37,001.

In this regard it is expected in subsequent publications in the magazine set out in more detail the practical experience of rezbovydavlivayuschih fasteners.

References

1. Asatryan RS, Bunatyan GV, Magdysh SI Progressive fasteners for buses and trolleybuses // «Road Transport»

1991, number 12, p. 27-28.

2. Antonov VA Bunatyan GV Self-fasteners // «Automotive», 1992, № 3, p. 20-21.

3. Gongalyuk VG Bunatyan GV Fasteners new quality // «Automotive», 2000, №5, p. 35-36.

Production Technology privrnyh pins made of stainless steel from the company SACMA

Claudio Armar, regional manager SACMA Russian text Anton Zaitsev

Philosophy and the production process of the company SACMA

The company SACMA introduced to the market of equipment for cold heading 1939. During all these years, the company is constantly growing and evolving. The key factors that allow to achieve these results are permanent attention paid to technological innovations, case studies, customer-oriented philosophy, highly mobile productive structure with a special form of management to create a positive motivation to work in the company. SACMA company is constantly expanding its product range of equipment. SACMA presses are able to produce products from M3 to MLO, up to 330 mm and a capacity of 90 to 400 parts per minute.

The production program of the company is not only the press four-, five- and six-position, which are designed for stamping special pieces with complex geometries, but also small single station two-shock presses for simpler products.

One of the latest developments, five-cold heading press SACMA SP 660 / AL, having a pressing force of 4500 kN, is capable of producing products made of steel wire with a diameter up to 30 mm at a speed of 90 products per minute.

The main feature of the company SACMA has always been a goal, leading to the full development of the production of all components that SACMA designs and manufactures its own.

Over 25,000 different products are produced at two production sites in Italy, Limbiate and Vimercate, which are equipped with the most modern and productive centers for mechanical processing, flexible production systems capable of processing products 24 hours a day, flexible production lines with automatic feeding, which has 80 pallets with workpieces. All this equipment is used to ensure a high, consistent quality of all the hardware components that make up the quality of the equipment, and the full interoperability of all components of the replacement and installation of spare parts.

Performance as a key to success

Machinery SACMA carefully think through the project since that ensures efficient and accurate planting of the product of complex shape due to fine adjustment, readability and reproducibility.

In fact, one of the keys to the success of customers using equipment SACMA — the ability to produce at maximum speed complex products with a given accuracy, while reducing waste to a minimum. It is also important to minimize the time to process the machine stops, and for this reason the company SACMA offers on all models the possibility of quick change tool, which allows the operator without leaving his seat, to prepare a set of tooling for the next product out of the car at the time, as the previous product still produced.

In addition, each individual adjustment on the press is equipped with SACMA indicator scale, which allows the operator to read what’s going on, and record all the parameters, as well as play them at the next start in the production of this product, thereby maintaining the quality and performance.

Some of these adjustments, such as the position of the arms when pushing out of the matrix, the position limiter wire, move the wire feed, have an automatic adjustment on the motorized versions («M») This reduces to a minimum the interoperation time moving components and product assembly operations , the interim storage. The shorter production cycle, the more profitable production, because you reduce production costs and improve the quality of the final product, since using less manual labor.

Our customers are always looking for such solutions.

The technical solution for weld studs with aluminum scope

The company SACMA every day improves the level of interaction with customers to help solve their problems. After the expansion of the technical office of the company had additional resources for the study and implementation of new technological solutions.

In early 2008, the company SACMA worked and launched a new technology for the production of welded stainless steel studs with pressed sphere made of aluminum, which is used to obtain a stable arc when welding. The product is made from a wire rod of 10.5 mm in the five-cold forging press SACMA SP 260, which allows the assembly of weld studs.

The machine is equipped with an external vibrating hoppers supply aluminum spheres. The operator, as appropriate, in the areas of supply resumes vibrating hoppers. Hopper provides a substantial margin areas, which reduces the need for frequent they are added.

Aluminum spheres are fed from the hopper through a tube into the fourth position of the punch press. The system monitors the sensors with established presence in the sphere of punch at each pass for guaranteed shrinking sphere in the product.

Because of the specifics of working with stainless steel, there is a need to share the landing operation that provides an increase in tool life. This is especially true of punches, forming a recess which is set aluminum sphere.

The process is fully automated and has a monitoring system that tracks the correctness of each transaction.

This technology can be applied to other similar products like stainless and from ordinary carbon steel.

The production cycle has been selected without obsechki, in order to minimize waste of expensive raw materials.

Due to the difficulty of deformation of the stainless steel, it was decided to use an external heating system, which can increase the temperature of the wire before punching to 200 ° C.

This system — a simpler solution compared with conventional induction heating system, and an increase in equipment cost as a whole during the installation of such equipment to heat the billets can be considered negligible.

The heating system can easily be detached in the event that there is no need to use a heating wire, and can also be moved from a cold forging machine to another or separately stored until the next use.

Before the creation of a technology company SACMA customers to produce studs for the two operations, the assembly is done by hand and, of course, it can not be called quality.

With the automation of the manufacturing process weld stud has been increased productivity, and at the customer 100% of the pins are molded aluminum sphere.

Conclusion

From the examples in this article can be seen as a particularly cold forging machines SACMA can help manufacturers of fasteners, allowing them to produce special products at high speed with excellent quality and high efficiency.

Such factors make it possible to save on production costs as low as possible, since the selling price of a product, and the cost of raw materials and regulated by the market maker has a negligible effect on these parameters.

SACMA company having almost 70 years of experience in the field of cold forming and having a wide range of cold forging equipment, able to solve any problem and meet all the requirements of manufacturers of fasteners.

EWMenn — leader in technology thread rolling for over 60 fier m Today, in order to establish itself in an increasingly growing competition, you must take a clear position.

Manufacturer thread rolling machines from EWMenn do it for more than 60 years thanks to constant innovation and upgrading. Credo of the company: «Only a leader in the field of technology determines the trend.»

In 2007, the firm has built EWMenn 5000th machine. Such results are obtained, few engineering companies working in such niche markets.

The basic principle of thread rolling machine company EWMenn, in fact, has not changed since the first production machine with profile. The workpiece is fed between the two dies, rolls between them, and thus its surface is obtained threads.

Despite this, between the first and 5000-m machine has done a great number of technical improvements and upgrades.

In contrast to a simple feeder drum, characteristic of the first machines, thread rolling machines are equipped with today’s most advanced delivery system comprising an optoelectronic position control or pre-heating the workpiece just before the thumb. This allows complex parts made of titanium, for example, for aviation and space industry.

In addition, the high degree of automation and an efficient process control system ensures a long operating time with minimal staff and thus the optimal integration into modern working environment.

A step ahead through innovation

Electronic control of the process at each stage of processing the workpiece, as well as developed by EWMenn automatic monitoring and adjusting thread of the thread have achieved great success.

All developments are the result of hard work and constant purposeful search of innovative solutions meet the changing demands of the market. It is not an easy task.

Hot-rolling and the possibility of machining with a high degree of deformation are just some examples of the development of production technology company EWMenn.

Another example — hydraulic clamping plates, which pioneered company EWMenn for accurate repetitive configuration and fixing thread rolling dies. This provides significant savings in makeready and setup of the machine.

To meet the requirements of customers, the company is constantly striving to EWMenn introduction of new technologies.

Years of experience and a deep knowledge of the market allow a timely response to these requirements and to find solutions to complex technical problems.

Along with the thread rolling machines from EWMenn offers a great palette of additional equipment, allows you to combine many manufacturing operations to the process rolling. Thus, for example, can be mounted in front of the knurled workpiece bolt shim or shim. For parts with a simple carving and geometry it is not a problem, but for special details of this serious problem, which brilliantly manages mounting hardware company EWMenn Series PTO.

Technologies that meet the requirements of tomorrow

In some industries are increasingly used special bolts, heat treated. Straight parts with negligible diameter and long length of the rod during quenching tends to deform. Getting between thread rolling dies, such items can cause significant damage Dies or even the entire machine. To exclude this possibility, the firm has developed EWMenn control device, which is by rolling to check the straightness and length of each workpiece and automatically sorts out defective parts.

The modern automobile industry also makes its own demands. For example, many special bolts must be blunted, ie they make the pointy end to later assembly robots can accurately install them. The program production EWMenn already has two faskosemnye machine designed for a diameter of from 4 to 20 mm.

CM series machines are working on high-speed technology with the spindle without the use of coolant. This is a big step toward efficiency and careful use of resources and environmental protection.

By implementing improvements that are prepared to enter into a series, EWMenn company once again has the right to claim the leading position in technology.

Already in 2008 the market will be thread rolling machine screws with a length of the rod up to 1500 mm, equipped with a new system of automatic adjustment of dies AutoSet with CNC.

Address Mission: http://www.wsd-moscow.ru

E-mail: wsd-moscow@wsd-moscow.ru tel .: +7 (495) 781 91 01 Fax: +7 (495) 781 91 02

Dorken MKS" Systeme — system Microlayer E ma, z anti-corrosion coating

For over 25 years, Dorken MKS-Systeme produces and markets systems microlayer anti-corrosion coating, and shares its experience and application of the coating with more than 120 companies with a license to use this technology.

These systems are mainly used in mechanical engineering, but can also be used in the aviation industry, construction and other fields. The range of products consists of zinc coatings, inorganic and organic coatings with different properties are used for manufacturing parts of superplastic steels such as fasteners, springs, terminals, stamped parts according to different customers’ requirements.

Today Dorken MKS- Systeme is a leader in innovation in the field of anti-corrosion coating systems nehromovyh.

tailor’s pins designed for cleaving tissue fitting.

She suggested in 1895 the German FA Hessenbruh.

It was the perfect material, which held firmly and do not cling tightly.

Steel wire clip Johan Valera. Patented in 1899-1901 years

Clip «Konaklip.» Patented in 1900. Produced in 1909-1910, respectively

Patented in 1927-1930 years. Co. Amsterdam, USA. The teeth are designed for more reliable fastening.

It produced in the years 1910-1941

Magazine «Hardware» is published in two formats

The printed version of the magazine is published four times a year in full color printing of 100 pages. Electronic version (online version) magazine is published monthly and is available on the website of the Association «RosMetiz.»

On the content of the magazine is not the same.

Editorial address:

118452, Moscow, Russia. Azov, d. 25, Bldg. 4

Phone:

(495) 310-74-54,

(495) 310-74-43 E-mail: metiz@rosmetiz.ru http: // www.rosmetiz.ru

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