Safety requirements and safety of the lifting equipment has always stood and will stand in the first place. Of particular importance, they acquire in the design, manufacture and operation of lifts and elevators.
Nikolai Yefimovich Kurnosov — doctor of technical sciences, professor, corresponding member of the Academy of Engineering Sciences named after AM Prokhorov, Honored Worker of Higher School of Russia. Head of the department «Transport-technological machines and equipment» of the Faculty of mechanical engineering, transport and energy Penza State University. Director of Innovation and Technology Center «Vortex processes and technologies» Penza State University.
Andrey Nikolotov — Senior Lecturer, Department «Transport and technological machines and equipment» of the Faculty of Engineering of transport and energy Penza State University.
Cutting metal — the most common today, the process of machining units of lifting equipment. The cutting process is a complex physical-chemical process of interaction between the tool and workpiece. For optimal parameters of this process in the tool — the item can be artificially introduced a variety of environments, providing cooling and lubricating effect.
The use of cutting process fluids (MWF) allows to increase tool life, to intensify the process of cutting, to improve the quality of the surface layer, to improve the accuracy of manufacture, etc. However, due to the complexity of interaction of the tool and workpiece during the cutting process requires the use of a wide variety of cutting fluids.
The main trend in the development of metal cutting is currently the use of dry machining or processing with minimal use of cutting fluids. It is becoming increasingly important not only in terms of protecting the environment, but also in terms of cost cutting fluids, as it reduces production costs.
One way to apply the minimum amount of cutting fluid is used as coolants flow air-liquid mixture. The history of this method has more than a dozen years, but there are several factors that limit the scope of its application, namely the factor associated to produce a stream of atomized cutting fluid (coolant).
The solution to this problem is connected with the creation of such devices produce a stream of sprayed coolant, which would correspond to the following characteristics:
1) ensuring optimal ratio of energy consumed to the dispersion of the spray;
2) high stability with minimum quality coolant;
3) low cost of manufacture and operation of the system;
4) the possibility of controlling the parameters of the torch.
As a result of a group of scientists Penza State University developed a method of cooling the cutting area. Technical characteristics of the device for carrying out the method closest to the aforesaid.
A method of cooling the cutting zone is realized as follows: into the pressurized air is supplied, share it on the hot and cold flows to the cold air flow to the cutting area, and the hot air flow re-spin and partially cooled in a confined space, re-divided into hot and cooling is often cooled in part fed to the cutting zone, before being fed to a further ejected and dispersed liquid components to form a cutting fluid.
The process of separation of hot and cold flows is based on the effect of J. Ranque. Compressed air is fed at high speed through a tangential inlet nozzle disposed in the vortex energy converters where the feed air is split into two streams. As a result of the interaction between the complex energy flows peripheral stream is heated and cooled to the axial of 30 ° C relative to the temperature of the compressed air and then directed to the cutting area.
The process of ejecting and dispersion of liquid components is based on the ability of a swirling vortex flow having a large relative speed and a high pressure gradient, break fluid fine droplets. In operation, the vortex atomizer — dispersant — the flow of compressed air (pressure 0.05 MPa) is supplied to the atomizer through a tangentially disposed inlet nozzle directed tangentially to the interior cylindrical surface. The nozzle body is formed in the axial zone of the vacuum zone providing ejecting fluid through the conduit, and the vortex flows of air it is dispersed into tiny particles and discharged through the outlet nozzle of the torch in the form of an aerosol. Flow rate can be adjusted as a change of air pressure at the inlet and flow control fluid inlet device.
To implement this method requires supply of compressed air under pressure of 0.05-0.2 MPa.
The device has the following characteristics: dispersibility spray coolant within 5 … 20 m; compressed air consumption 0,2.20,0 m3 / h depending on size; the maximum flow rate of 50-500 ml / min, depending on size; the possibility of multi-component mixing and spraying coolant; the ability to adjust the temperature of the flame sprayed; the ability to control the geometric parameters of the torch; the ability to adjust the quality characteristics of the spray plume.
Atomized cutting fluids used in the machining of high-alloy steels and structural tools of high-speed steels and hard alloys, while stripping blanks on heavy machines, the processing of aluminum alloys and non-ferrous metals. Even limited use of this technology has shown that when applying a small amount of coolant in the form of an aerosol can be high-performance processing on existing equipment.
The beginning of the application of the developed system of training and supplying atomized coolant to the cutting area served by having one of the machine-building enterprises of Penza task. In the manufacture of a number of details on the operations of roughing it is necessary to enter the cutting area as coolants sulfofrezol vapors which can cause respiratory diseases, skin and many other diseases. To minimize the harmful effects on human health used the installation of exhaust ventilation with a total capacity of 45 kW. We proposed to abandon the use sulfofrezola and used as coolants cooled air with a minor amount (up to 0.5 g / h) mineral oil. To accomplish this, a technical proposal for milling machine was installed vortex power converters supplying cooled air to freezing temperatures in the cutting zone, as well as a lubricant is used the minimum amount of oil which is supplied with compressed air from the pneumatic system.
The two-year experience of operation of the cooling scheme has shown that, in addition to improving the environmental situation in the machine shop and save energy, found additional savings: savings on the cutting tool (resistance has increased in 2 times), savings on SOTS, productivity growth associated with reinstalling cutters . The total savings for 1 year is about 900 thousand rubles.
Another good example of the use of the method of cooling the cutting area was its use in the processing of aluminum alloy AMg6 operations shaped turning sphere. When using traditional methods of cooling and lubrication of the cutting tool to obtain the necessary surface finish was not possible.
It has been proposed to use as a cutting fluid stream of chilled liquid mixture of 1.5% aqueous solution emulsol. Solve the problem was not immediately apparent. Minimum quantity of atomized emulsion was sufficient to maintain a desired heat balance, but the quality of the surface layer proved unsatisfactory. Intensive built-up edge on the cutting edge is not possible to achieve the desired surface finish.
The use of cutting fluids, oil-based proved unacceptable because of a violation of thermal balance. Evaporation rate oil cause unacceptable environmental degradation in the shop, but the built-up edge has ceased, and has become an acceptable surface finish.
These results led to the idea to combine the beneficial properties of these two different classes in a coolant. Mixing oil and water is possible, but the process of separation of liquids fleeting, and to maintain the mixture in a serviceable condition must be permanent and intensive mixing, and this leads to lower reliability and higher operating costs. One of the functional characteristics of the designed system is the possibility of mixing dissimilar fluids directly before being fed to the cutting zone.
This feature is implemented in one of the elements of the system — the spray dispersant. Implementation is done by simultaneously ejecting a swirling flow of two fluids of air and dispersion and mixing. To ensure optimum flow of liquids, a simple and yet reliable system for dispensing cutting fluids. The result of this system was the reduction in production cost of manufacturing the pivot bearing is 15%.
Using domestic enterprises processing technology when applying sprayed coolant will reduce the cost, minimize environmental damage, will enable the replacement of foreign systems of preparation and submission of atomized coolant to the cutting zone.