The method of controlling the wear of friction pairs under dynamic loads
(57) Abstract:The invention relates to the field of engineering, namely the technology of induction welding durable powder alloys, for example, to friction and moving the pair of machines and equipment transport vehicles, including cars, locomotives, track and road cars, parts superstructure. The essence of the invention: method including induction and metallurgical cladding of wear resistant material and its dynamic recrystallization by contact of the friction surfaces, welding lead material of wear-resistant alloys undergoing contact austenitic transformation in the contact zone with the formation of finely dispersed carbide phase with a grain size of 2-8 μm and microhardness H0,9812000-17000 MPa and form in the contact zone of oxide film, and dynamic recrystallization ensure that the specific pressure at the contact does not exceed 1100 kg/cm2while maintaining the elastic-plastic properties of the deposited wear-resistant alloys. The thickness of the oxide film formed in a contact zone is 0.2-0.3 microns. The technical result of the invention is the ability to control the wear of friction pairs ness to technology induction welding durable powder alloys, for example, friction and mobile interfaces machinery and equipment transport equipment, including cars, locomotives, track and road cars, parts superstructure.Currently, rail transport, there is the problem of rapid wear of friction pairs, working under high dynamic loads, such as vibration dampers, articulated swivel device, the shaft sleeve spring and walking beam suspensions, etc.According to the existing technology wears these nodes eliminate arc method of welding with subsequent machining or technology Engineering center "Alloy" induction-metallurgical method.Analyzing the optimization of friction pairs after induction welding, Engineering centre "Alloy" of the Ministry of Railways have discovered new opportunities recrystallization of the metal, not static, which is well known and dynamic that occurs in the contact zone of metal alloys at high loads or shocks cooperating friction surfaces, working in dry friction mode.Working on reducing wear in friction pairs under dynamic loads allowed principianti friction pairs by several orders of magnitude.The known method, which is implemented in the friction element managed tribological characteristics (see U.S. Pat. EN 2065098, CL F 16 F 3/08, B. I. 22, 1996), namely, that when the reciprocating movement of the friction pairs of speed change from V0=0 to Vmax=max by selecting the material, from which depend the friction coefficients from f1...fnand wear resistance j0...j0n.However, this technical solution has addressed the issue of friction and wear, but did not dare question about the impact of a specific contact pressure, temperature fields and areas of contact of the friction pairs, operating without lubrication dry friction mode, and this in turn was not allowed to raise issues such as the influence of recrystallization phenomena in the contact friction pairs and control their durability in the process of their adaptability.A prototype of the selected method of hardening of friction (see the book D. Buckley "Surface effects in adhesion and friction interaction), engineering, 1986, pp. 86-87), which describes the process of recrystallization during static loading of chemically pure iron.The disadvantage of this method awseme loads, since the yield strength of such metals is significantly lower than permissible, which will lead to deformation and low wear.In friction pairs usually work with a wear resistant steels or alloys, if steam is running in dynamic shock loads, the effect of recrystallization depends on the specific pressure and temperature of contact spots. Based on these circumstances, an important factor is the need to manage the phenomenon of recrystallization to improve wear resistance of the friction pairs.The technical problem of the invention was to develop ways to control the wear of friction pairs under dynamic loads.This object is achieved in that in the known method of controlling the wear of friction pairs under dynamic loads, including surfacing wear-resistant material and its dynamic recrystallization by contact of the friction surfaces, welding lead material of wear-resistant alloys undergoing contact austenitic transformation in the contact zone with the formation of finely dispersed carbide phase with a grain size of 2-8 μm and microhardness H0,9812000-17000 MPa and obrazuya contact does not exceed 1100 kg/cm2while maintaining the elastic-plastic properties of the deposited wear-resistant alloys.In addition, the thickness of the oxide film formed in a contact zone is 0.2-0.3 microns.In this case, the welding is conducted induction-metallurgical method.In Fig. 1 shows a graph of wear of various materials depending on the load;
Fig.2 - surface friction contrapasso different pairs:
a) a pair of GL+FL
b) a pair of USC+FL
in a pair On 27+USC;
Fig. 3 - microstructure of the surface layer contrapasso in cross section thin section:
a) a pair of GL+FL
b) a pair of USC+GL;
Fig.4 - microstructure of weld metal on the surface of friction:
a) the surface of the deposited metal On 27 (with magnification of 250 times)
b) the surface of the deposited metal On 27 (with increased 800-fold).Table of basic test results of friction pairs is given at the end of the description.The proposed method is as follows.The friction surface of the friction pairs, such as vibration dampers, articulated swivel device, the shaft sleeve spring and walking beam suspension, napravlyali durable pre-select materials, namely solid alloys that meet the following criteria.First, wear-resistant surface friction pair must have the specific load not exceeding the plastic deformation of metal.To improve wear resistance of friction pairs in the dynamic system of friction necessary to comply with the terms when specific load P(MC) is reduced to limits = 1100 kg/cm2while maintaining the elastic-plastic properties of metals.Consider the static wear resistance, for example, a pair of friction in wheel-rail according to the formula Hertz-Belyaeva (see the book by A. F. Zolotarevsky "Thermally hardened rails), Transport, 1976, page 30).< / BR>wherearticle(J0) - static contact strength of the rail, kg/cm2;
MCspecific contact pressure, kg/cm2;
R is the wheel's radius, cm;
m - coefficient taking into account the area of contact; dependent on contact area of the interacting surfaces;
E - the modulus of elasticity young's modulus, taking into account the elastic-plastic properties of metals, kg/cm2.The values of R and E are constant for these metals and of little significance. On this basis, considering the durability from the position on the wear of the friction pair can be expressed in the following dependencies:
< / BR>where P is the actual load, kg;
S is the contact area, cm2.Therefore, work must be done with alloys, in which the elastic-plastic properties is significantly higher than that of steel (see Fig.1).Thus, the load contacts the friction must ensure that the plastic deformation of the projections of the metal, leading to their transformation.Secondly, in thin surface layers in the process of friction generated temperature in the range 0.4 to 0.7 of the melting temperature alloys. This is because the temperature of the contact surfaces in friction pairs is significantly higher than that of pure metals. In this process the temperature reaches 1500-2000oC.The temperature of recrystallization dynamic friction is greatly reduced, so in alloys, the temperature decreases with 1200-1300oWith up to 400-600oC.Thirdly, a force in terms of wear causes in metastable structures structural transformations under the action of temperature. In the contact area due to local temperature flashes in the weld metal occurs vacation austenite with a selection of fine carbides with partial formation of Deuteronomy is PS.As a result, the friction surface of the resulting finely dispersed carbide phase with a size of 2-8 microns with a microhardness H0,9812000-17000 MPa enshrined in the plastic matrix, which provides a significant improvement of wear resistance.From the above we can conclude that as a result of dynamic recrystallization and oxidation of the contact surfaces of the tops of the protrusions are destroyed due to the transfer of the oxide film on the wear surface (softer), the number of contact points increases, the surface pressure at the contact points is reduced, which gives confidence to assert the possibility to control the wear of friction pairs under dynamic loading.Example. Conducted research of various pairs of friction (three options), where the samples (II and III variants) were deposited induction smelting method of wear-resistant alloys, and then were tested for installation (not shown), while return plane-parallel movement.Mode test: the load is 24.5 kg/cm2; cycle test - 2 hours.Materials options: I pair - FL + FL; II para - USC + PL; III pair - On 27+USC.ASD is used in the rolling stock of railway transport).The tests showed.Under load conditions of plastic deformation at the points of actual contact surfaces are activated by the adhesive forces between the atoms of the metals, which leads to adhesion on limited areas, leading to the setting of the first kind (see Fig. 2,a).It is known that the friction of metal surfaces is formed oxide film, but in this case due to the low hardness of steel HF, the oxide film is destroyed, creating favorable conditions for structural transformations under the action of heat. On the sample surface are formed projections or scallops height of 1000 μm and a trench depth of up to 70 microns.The microstructure was investigated in cross section (see Fig.3,a). In the surface layer due to navrachana metal prints microhardness fail. The depth of the deformed metal is about 200 μm, and the surface layer to a depth of about 40 microns, due to recrystallization takes place substructural strengthening. The latter happens when hot deformation at (0,4-0,7)TPL. Grain size less than 10 microns. When the friction pair FL on FL total depreciation per cycle was 28.5 gOption II.Spent tested ostonen alloy USC (TU 322-19-007-97), and the second is made of steel PL.Tests showed that this pair of friction process setting is missing (see Fig.2,b), wear contrapasso of steel GF was 0,194 g or decreased by 70 times. Wear the deposited sample was 0,062 g or decreased to 240 times. This improved wear resistance due to the following factors.First, the structural transformations on the surface of the alloy USC, in its surface layers is the collapse of the supersaturated solid solution or austenitic transformation with selection of the hardening phase - carbides of iron, chromium, manganese smaller than 10 microns (the original was 30-70 μm). This forms a finely dispersed carbide phase with a grain size of 2-8 μm and microhardness H0,9812000-17000 MPa, distributed in a plastic matrix (see Fig.4,a,b), providing good stability in conditions of friction.Secondly, high elastic properties of all weld metal (structural components - carbides and grain solid solution) practically do not experience plastic deformation (see Fig. 3), which inevitably leads to decreasing pressure not exceeding 1100 kg/cm2as increases the actual contact area component of 0.2-0.3 μm. The latter is transferred from the deposited sample on steel contrapasso (see Fig. 3,b), increasing its durability.The surface topography is almost flat.Due to dynamic recrystallization plastic deformation extends to a depth of 50 μm, the substructure is formed to a depth of 30 μm.Option III.We investigated a pair of friction of the samples, the surfaces of which were deposited hard alloys On 27+USC.Tests have shown that wear such a pair was 0,042-0,065 g per cycle, a pair of friction, both of the contacting surfaces of which are represented by solid alloys, wear 260 times higher than option I.When a small film thickness, its hardness is almost the same with the micro-hardness of the carbides H0,9811700-12200 MPa, due to the high strength (see Fig.2,) and a good connection with the deposited metal.Analyzing the results of tribological tests and physical metallurgy research has made the following conclusions.1. When the friction pair HL+HL is "sticking" of the first kind, leading to significant wear - 13,5-15 g per cycle tests.2. When surfacing the surfacing alloy USC one is 70 times;
alloy USC - 240 times.3. The hardening of the two elements of the pair of friction increases the wear resistance of 270 times.Based on comparison of experimental data it is possible to make such a conclusion (see Fig.1) that the dependence of the wear of materials from the loads as follows:
curve a shows: steel HB=150 when small loads are transferred from oxidative wear to be wrapped;
curve B shows: steel with hardness 40-50HRC - threshold setting is performed at much higher loads, due to thermal softening (leave a hardened structure in contact);
curve b shows: wear-resistant alloys with hardness 40-50HRC - setting wear-resistant alloys is carried out at very high loads, exceeding the contact strength of the material. High threshold setting due to the fact that as a result of dynamic recrystallization alloy surface and contrapasso become more smooth, and the contact patch is increased, which reduces the contact pressure that causes a temperature reduction of friction in the contact and a dramatic decrease wear.The use of the proposed izobreteniya, which has a positive effect on the wear resistance of the friction surfaces, hardened alloys induction-metallurgical method. As a result, this allows to reduce the specific load twice, which leads to increased wear resistance of hardened friction pairs and above (12 times), thereby increasing the service life of parts of friction, which saves materials, energy and labor resources in the operation of machines and equipment in any branch of engineering. 1. The method of controlling the wear of friction pairs under dynamic loads, including surfacing wear-resistant material and its dynamic recrystallization by contact of the friction surfaces, characterized in that the welding of the lead material of wear-resistant alloys undergoing contact austenitic transformation in the contact zone with the formation of finely dispersed carbide phase with a grain size of 2-8 μm and microhardness H0,9812000-17000 MPa and form in the contact zone of oxide film, and dynamic recrystallization ensure that the specific pressure at the contact does not exceed 1100 kg/cm2while maintaining the elastic-plastic properties of the deposited wear-resistant alloys.m3. The method according to p. 1 or 2, characterized in that conduct induction-steel cladding.
FIELD: processes for surfacing with use of lying electrode, possibly restoration of worn surfaces of parts in different industry branches.
SUBSTANCE: method for surfacing bead of rollers of road building machines comprises steps of arranging roller in such a way that its axis is vertical; dividing surfaced zone of bead by technological sectors; forming electrodes of n mutually joined rods bent along arcs of sectors and arranging them on surfaced area of respective sector with gap; supplying flux and additive powder material to surfaced zone; connecting electrode and part with power source for exciting electric arc and performing surfacing; placing electrodes on sectors of bead simultaneously along the whole circle; electrically connecting front end of one electrode with bead; at surfacing narrow beads, forming electrodes of n mutually joined rods arranged one over another.
EFFECT: enlarged manufacturing possibilities of method for surfacing parts with annular worn surface, lowered cost, enhanced efficiency of process.
3 cl, 5 dwg, 1 ex
FIELD: processes for surfacing by means of lying electrode, possibly manufacture of crowns of teeth of digging machines working in condition of intensified wear.
SUBSTANCE: method comprises steps of placing electrodes with gap on part to be surfaced; using flux and additive powder material; exciting electric arc between electrode and surfaced surface; performing multi-layer surfacing alternatively on upper and lower sides of crown; using steel substrate whose width is equal to distance between lateral faces of crown and whose length is equal approximately to difference of length values of new and worn crowns along axis of lateral side; arranging steel substrate in direction of plane crossing axes of lateral faces of crown and welding it to crown along contour of wear; fixing crown with welded substrate in such a way that at first its upper side is arranged horizontally, then its lower side is arranged horizontally; placing electrodes across lengthwise axis of crown at first on substrate and then on surfaced zones until their complete restoration.
EFFECT: enhanced quality of restored surface, lowered cost and simplified technique of process.
3 cl, 5 dwg, 1 ex
FIELD: restoration of cast iron rolling rolls with journals damaged at operation.
SUBSTANCE: method comprises steps of mechanically removing damaged layer and performing electric arc surfacing of rotated roll in place of damaged layer removal while feeding steel austenite wire electrode with diameter 3 - 5 mm to welding zone. Surfacing is realized at density of electric current 30 - 40 A/sq. mm and at electrode feeding speed 80 - 110 m/h. After surfacing journal is subjected to spontaneous cooling.
EFFECT: possibility for completely restoring geometry size of operational properties of damaged roll at keeping the same values of its hardness and strength.
1 tbl, 1 ex
FIELD: machine engineering, namely apparatuses for surfacing at restoring defective or damaged parts.
SUBSTANCE: surfacing machine tool includes column with yoke, cross piece, carriage, face chuck, table with adjustable inclination angle, surfacing head having mechanism for reciprocation motion in horizontal plane, mechanism for vertically moving surfacing head, mechanism for rotating in horizontal plane surfacing head with mouthpiece. On surfacing head there are mounted: reel with surfacing wire, mechanism for feeding wire to surfacing zone through mouthpiece and mechanism for reciprocation motion of surfacing head in horizontal plane. Machine tool is provided with matching device having actuating organ and providing kinematic connection between mechanism for rotating surfacing head and mechanism for vertical motion of surfacing head. Handle and flywheel kinematically joined with toothed rack of cross piece are secured to carriage. Matching device is in the form of worm reduction gear of rotation mechanism that is kinematically joined through first cone reduction gear with face chuck and through set of gear wheels - with connection coupling. The last through spring of actuating organ in the form of electromagnet and through second and third cone reduction gears is joined with lead nut of vertical motion mechanism.
EFFECT: enhanced operating efficiency, enlarged functional possibilities of machine tool.
2 cl, 4 dwg, 1 tbl
FIELD: machine part restoration, namely restoration methods suitable for using in aircraft engines, machine engineering and other branches of technology for restoring rubbing surfaces of cylindrical parts.
SUBSTANCE: method comprises steps of mounting on surface of part prepared for restoration before surfacing, blank of additive material in the form of band; using band with thickness 0.1 - 5.0 mm and mounting it at gap no more than 0.2 mm; performing multi-layer surfacing of additive material in vacuum by means of scanning electron beam; mechanically working part after surfacing each layer of additive material.
EFFECT: simplified process of surfacing material, elimination of residual stresses and deformations in article.
11 cl, 2 dwg, 1 tbl
FIELD: processes for restoring steam turbine blades with damaged edges.
SUBSTANCE: method comprises steps of removing worn portion and then surfacing in impulse mode metal whose ductility exceeds that of blade material; welding on protection cover strip by two seams while forming one seam on base material of blade and forming other seam on surfaced metal. Surfaced metal has high cracking resistance; its melting temperature is less than that of base material of blade. Heat treatment with use of heat insulation jacket is performed after surfacing and welding on of protection cover strips.
EFFECT: lowered non-uniformity of structure-phase composition of material of restored blade, reduced tension residual stresses, enhanced resistance of blade against cracking, corrosion and erosion.
4 cl, 1 dwg, 1 tbl
FIELD: power production machine engineering, possibly manufacture of such parts whose surface layer operate in condition of erosion-corrosion actions, high mechanical loads, influence of cryogenic temperatures, for example in power production or chemical-production plants.
SUBSTANCE: method comprises steps of placing copper plate on substrate and melting it by means of electric-arc welding with use of non-consumable electrode; before placing plates, applying flux layers onto mutually joined surfaces; insulating ( for preventing contact with arc plasma) end edges of copper plate and portions of substrate near edges of plate along the whole perimeter; realizing surfacing at melting temperature of copper plate that causes no fusion of base metal of substrate.
EFFECT: enhanced quality of surfacing.
6 cl, 3 dwg, 1 ex
FIELD: restoration of worn surfaces, namely semichambers of rubber mixers.
SUBSTANCE: method comprises steps of placing on restored part metallic cover plate compensating wear; fusing cover plate along its whole thickness by annular or lengthwise seams at predetermined pitch with use of plasma arc and additional arc. The last burns between melt metal and alloy powder wire that is fed behind plasma arc. Spacing between said arcs is selected in range consisting of (0.4 - 0.6) of length of melt metal bath.
EFFECT: possibility for providing seam root minimally alloyed with powder wire components at keeping wear resistance of remaining metal of seam.
FIELD: restoring or strengthening worn parts by electric arc surfacing, manufacture of new parts operating in condition of variable dynamic loads combined with high wear and corrosion.
SUBSTANCE: method comprises steps of forming at least partial coating at least of one layer on part by electric arc surfacing with use of consumable electrode; forming said layer of alternating preliminarily set at least in one direction zones of metals with different linear expansion factors. At least one zone of said layer includes metal whose linear expansion factor is less than that of main metal of part. Such layer is formed by filling preliminarily formed grooves with metal or by applying beads.
EFFECT: enhanced operational properties of parts due to creation of in part designed favorable fields of residual stresses.
10 cl, 17 dwg, 7 ex
FIELD: welding, namely apparatuses for surfacing inner cylindrical surfaces, possibly electric-arc corrosion protection flux surfacing.
SUBSTANCE: apparatus for belt type surfacing of cylindrical surfaces of small-diameter openings is in the form of surfacing attachment and it includes guiding duct for passing welding material. At outlet of said duct there is electric current supply mouthpiece with pressing device. Guiding duct is rectangular one, it has shaped working surface. Contact surface of belt and pressing device is arranged over level of contact surface of belt and current-supply mouthpiece without their direct contact. Width of working surface of electric current supply mouthpiece and pressing device is less than that of fed belt. Pressing device is in the form of pressing roller or pressing plate whose working surface is rounded.
EFFECT: enhanced efficiency of surfacing, enlarged manufacturing possibilities of surfacing head, improved stability of belt feed, enhanced quality of surfaced coating due to optimization of constructional members of attachment.
3 cl, 3 dwg