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Вестник технологического университета. 2015. Т.18, №18 УДК 537.525.7:621.762
A. A. Khubatkhuzin, I. Sh. Abdullin, V. I. Khristoliubova ANALYSIS OF MECHANICAL AND PHYSICAL PROPERTIES OF METAL CUTTING TOOLS PROCESSED BY RF-PLASMA OF LOWERED PRESSURE
Ключевые слова: ВЧплазма, пониженное давление, сверло, дисковая фреза, угловая фреза, торцевая фреза.
Рассмотрен метод упрочнения металлорежущего инструмента ВЧ плазмой пониженного давления. Получено покрытие на поверхности быстрорежущей стали. В результате формирования покрытия на поверхности выявлено улучшение физико-механических свойств поверхностных слоев металлов и повышение их твердости.
Keywords: RFplasma, low pressure, drill, disc cutter, corner cutter, end mill.
Method of hardening of cutting tools is considered. Coating on the surface of high-speed steel obtained by the RF plasma of low pressure. As a result of forming of a coating on the surface improvement of physical and mechanical properties of metals and increase of hardness was produced.
Introduction
Metal cutting tool is widely used by enterprises and ordinary customers. For this reason, very high demands on quality are required, work safety and ergonomics, that in turn forcing manufacturers to create more and more sophisticated types and forms of the instrument [1-3].
Metal cutting tools - equipment for different types of work with metal parts. In most cases, these include equipment for various metal-cutting equipment, such as milling cutters, taps, metal knives, saws and drills. Currently, consumers are often faced with a difficult choice to buy an expensive tool under the well-known trademark or cheaper by a little-known manufacturer. In recent years there has been a consistent trend of changing preferences of customers who refuse to buy cheap domestic instrument in favor of more expensive imported. What is the reason? First of all, the fact that the domestic manufacturer is not able to produce a tool that is comparable in quality to foreign analogues, but the lowest price is not so attractive for buyers, because then this advantage is lost because of the need of constant repair, the appearance of injuries and so on [4-6].
Manufacturers of cutting tools, feeling the intense competition in the market, introduce more and more new achievements in science and technology to improve productivity, quality and safety of its product. Constructive view of machines and mechanisms is being changed, new alloys for the production are being applied, very actual now is to improve the current cutting properties to improve cross-metal, the possible shortcomings of the current tool are extremely well-calculated to remove them and make it even more perfect.
Milling is one of the most common methods of processing of flat and shaped surfaces [7,8]. The grooves, ledges, edges, profiles, grooves in the wood products, metal, plastic, acrylic and other materials are carried out with this type of method.
The milling process is characterized by a set of several factors: the rapid rotation of the tool around its axis and the slow translational, rotational or screw sideways movement of feeder. The rectilinear motion of feed is used for the treatment of different types of cylindrical surfaces: planes, all kinds of slots and grooves, shaped cylindrical surfaces. The rotary motion is
used for milling surfaces of revolution. Screw traffic flow is handled for screw surfaces such as chip flutes tools, depression helical gears and others.
As the objects of study disk, corner, end mills and drills were chosen.
Experiments and results
For the purpose of steel processing with flow of radio-frequency (RF) discharge of low pressure plasma unit is used. Experienced RF capacitive plasma installation for modification of materials is shown in Fig. 1.
Sample processing is performed as follows: Samples are hung on the frame (1) and installed between the RF electrodes (2) in a vacuum chamber (5). As the door of the vacuum chamber hanging on the console (4) is closed electrodes are installed in the operating position. Further, the vacuum chamber is pumped using the pumping system (8), built on the basis of a vacuum unit AvR-50. Then, discharge chamber is filled with the plasma gas through the feed system (6) RRG-10. A predetermined gas flow rate is set, voltage is applied from the RF generator (7). The electromagnetic field from the electrodes make a partial ionization of the gas in the
workpiece; 2 - high-frequency electrodes, 3 - the door of the vacuum chamber; 4 - console for opening the door of the vacuum chamber; 5 - vacuum chamber; 6 - supply system and regulation of plasma-forming gas; 7 - RF generator; 8 - vacuum exhausts posts
RF generator. For studies of different types of RF discharges the creation of RF generators, collected in a single-circuit tuned to the capacitive load on the
permitted frequency of 13.56 MHz was required. Consumed power generators range is from 0.5 to 3 kW.
RF plasmotrones
Plasmatron for producing of a plasma flow capacitive type with flat electrodes consists of two water-cooled copper plates. The electrodes are placed in a vacuum unit. Means for fixing samples are located between the electrodes.
Vacuum chamber constructed in a cylindrical design. The door pulls back in a special console with a grounded electrode. Loading is carried into the chamber through the face door in the chamber. When the lid of the vacuum chamber are closed plates are installed in the operating position. Feed through rotation is provided for rotatable products in-chamber volume on the door.
The base of the vacuum unit mounted in a welded frame. Vacuum pumps and water cooling plant components are arranged at the frame unit.
Vacuum exhausts posts consists of two pumps: forevacuum pump AVZ-20D and twin-rotor pump DVN-150, respectively, with a pumping speed of 50 l / s and 150 l / s. The pressure in the vacuum chamber is controlled by membrane capacitance sensor MKS 627B.
Microhardness and roughness measurement was applied to determination of physical mechanical properties. The relief and surface structure at a submicronic and nanometer scale was investigated by means of the scanning nanohardness gage «NanoScan-3D». On the «NanoScan» base the method of measurement of the hardness, based on measurement and the analysis of dependence of loading at indentation of indenter in a material surface from depth of introduction of an indenter is realized. This method is a cornerstone of the standard of measurement of hardness ISO 14577. The indenter of Berkovich type is applied to mechanical tests. It represents a trihedral diamond pyramid with a corner at
Supply system and regulation of plasma-forming gas consists of a compressed gas cylinder, a reducer for reducing the pressure, manometer, mass flow controller MKS 1179A and a needle valve to regulate flow and a device for producing a mixture of gases.
Water System of Installation BMT-20 serves to provide a set thermal regime of parts and assemblies, the most loaded thermally. The water supply to the installation and removal of it is carried out with rubber hoses.
Control equipment is used to control the input parameters of installation: RF voltage, generator frequency during all experiments for materials processing.
In all cases, in order to avoid side effects, treated details' parts degreased and dried before treatment.
To investigate the effect of the interaction of low pressure RF plasma to the surface of the material experiment with the plasma of an inert gas, argon, and mixture of plasma-chemical gas, methane and argon, was carried out.
Parameters of treatment and results of the experiments are presented in the table 1 and table 2 respectively.
top near 142°. The method of a measuring dynamic indentation consists in the following: the indenter is pressed into a sample surface with a constant speed, at the achievement of the set loading the indenter is taken away in the opposite direction. In the course of such test record of values of loading and shift of an indenter corresponding to it is made. Feature: pezorezonanse cantilever tuning fork construction with high bending resistance (~2-104 N/m) [9-11].
For quality control of convex surfaces the device on the basis of nanoskan hardness tester was designed determined specifically for the study of the quality
Table 1 - Parameters of treatment
N, Watt Q1, cm3/min Q1, mg/sec Q2, cm3/min Q2, mg/sec P, Pa Time, min
900 1500 44,4 22 20
900 1500 44,4 150 1,8 21 20
Table 2 - Results of the experiments
Workpiece Hardness of untreated work pieces, GPa Hardness of treated work pieces,
(material) GPa
side milling cutter 13,19±1,93 15,08±0,9
(R18) 12,10±2,32 17,39±2,84
face milling cutter 14,90±1,02 15,82±1,26
(R18) 20,38±1,02 21,75±,23
Drill (R6M5) 22,5±1,07 30,62±18,53
17,21±1,91 19,07±0,98
side milling cutter 20,87±0,98 20,25±0,87
(R18) 19,90±1,37 21,54±0,75
face milling cutter 13,28±0,50 23,32±3,97
(R18) 11,33±1,36 14,00±1,95
16,24±1,02
Drill (R6M5) 18,87±0,79 21,42±4,39
7,93±1,41 21,08±2,87
19,24±0,84 15,61±1,17
system by the non-destructive methods of physical and mechanical properties of the surface of the pipe.
Conclusion
Thus, it revealed that the physical and mechanical characteristics of metal cutting tools treated with capacitive radio-frequency plasma discharge, have a high technological and operational characteristics. Gas saturation (carbonizing) of surface layers of metals and alloys at a depth of 1 micron during processing to 40 minutes was obtained, resulting in an increase of strength properties, durability and lifetime of the products. The advantage of ion implantation over other methods of introducing other impurities in solids is the versatility of the process which allows introducing any element of any material in strictly controlled quantity, as well as setting its depth distribution.
Research of wear resistance was carried out by experimentation way on field trials of "Northwest trunk pipelines." They showed that lifetime of all treated mills increased in the range of 140 to 230%.
The complex approach to the study of surfaces with the use of methods to measure topography, roughness, hardness, wear resistance, modulus of elasticity, elastic recovery coefficient and the thickness of the modified layer in a single instrument was studied and mastered.
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© А. Khubatkhuzin - Ph.D., associate professor of Plasma Technology and Nanotechnology of High Molecular Weight Materials Department, KNRTU, [email protected]; 1 Abdullin - Ph.D., professor of Plasma Technology and Nanotechnology of High Molecular Weight Materials Department, KNRTU, [email protected]; V. Khristoliubova - Ph.D. student of Plasma Technology and Nanotechnology of High Molecular Weight Materials Department, KNRTU, [email protected].
© А. А. Хубатхузин - к. т. н., доц. каф. плазмохимических и нанотехнологий высокомолекулярных материалов, КНИТУ, [email protected]; И. Ш. Абдуллин - д.т.н., проф., зав. каф. плазмохимических и нанотехнологий высокомолекулярных материалов, КНИТУ, [email protected]; В. И. Христолюбова - аспирант той же кафедры, [email protected].
