Method of enhancing wear resistance of working surfaces of metal articles

FIELD: metalworking; mechanical engineering.

SUBSTANCE: alloying agent in form of powder is applied to working surface of article by explosion. At explosion application of alloying agent, layer of this agent is placed directly on working surface of article and layer of explosive charge following the shape of working surface is laid over it. Explosive charge is initiated by excitation of sliding shock wave in alloying agent. If it is necessary to enhance wear resistance of working surfaces when increase of hardness is not required, inert gasket following the shape of surface being treated is laid in between alloying agent and explosive charge.

EFFECT: facilitated procedure of method at simultaneous increased service life of parts due to enhanced wear resistance of working surfaces.

2 cl, 2 dwg, 2 ex

 

The invention relates to the processing of metals by pressure of the explosion of explosives and can be used to improve the wear resistance of the working surfaces of metal products.

There is a method of hardening the cast parts of railway crossings (patent RF №2007478 from 19.03.91 year), according to which the hardening explosion of railroad crossings is carried out after pre-bend, which is set depending on the process requirements. This creates conditions for increasing the intensity of hardening (increase the hardness of the hardened metal).

A device hardening of rail in the area of welded joint (patent RF №2102501 from 29.08.95 year), according to which the device includes a housing with located it charge cast CENTURIES and the site of initiation. The hull shape and the position of the node initiating chosen so that the detonation wave in the charge extends perpendicular to the longitudinal axis of the rail. The result was an explosive hardening of the distribution of hardness of the roll surface in the area of the weld becomes smooth without plots with low hardness in the heat-affected zone. The weld joint is less prone to wear than the non-reinforced.

There is a method of hardening the working surfaces of the cores arrow crosses (patent P is No. 2159292 from 25.09.99), according to which make processing of the surface crosses the moving detonation wave with the use of sheet explosive charge. When this occurs hardening of the surface and thereby increasing the wear resistance of the spider.

The known method (Gorbunov VG, Kozorezov SURDS, Usherenko S.M. investigation of the effect of microparticle bombardment on the structure of the steel target. - In the book: Powder metallurgy, Minsk: the High. HQ., 1982, issue 6, p.19-22), according to which the process of alloying the surface of metal parts is realized when throwing the fine alloy powder charge explosives (he). The charge is located at a certain distance from the workpiece, and throwing a stream of particles is carried out from a spherical cavity in charge. During the blasting charge on the item is the combined effect of the flow of fine particles and shock waves formed when braking on a hazard of explosion products. Thus the depth of penetration of fine particles up to several millimeters, and wear doped surfaces of the samples is reduced by half.

The last technical solution, as the closest to the technical essence and the achieved result, selected as a prototype.

The characteristics of the prototype in common with the claimed method:

- use as became the dominant elements fine powder;

- over lagerweij surface of the explosive charge;

initiation of the explosive charge.

This method of increasing the wear resistance of the working surface has an insufficient level of technology, so:

for machining a curved surface with a certain degree of increase of wear resistance will need introduction to process additional operations on multiple handling (demolition);

- to obtain a positive result of hardening required surgery to install charge with alloying powder at the right distance from the treated surface;

an important obstacle to the use of the known method of hardening is the factor limiting the surface to be treated, depending on the size of the spherical recess in the explosive charge.

The task, which is aimed by the invention, is to eliminate the above disadvantages.

The technical result, which is aimed invention is to increase the life of products due to quality improve wear resistance of the working surface.

This technical result according to the claimed method is due to the fact that:

- layer doping substances placed on the treated is poverhnosti, i.e. on the wear area of the product;

the explosive charge (for example, plastic EXPLOSIVES), the shape of the workpiece, is placed on the layer of doping substances on the treated surface;

- hardening by shock-wave loading of the working surface to produce a sliding detonation wave across the working surface of the workpiece;

- to improve the wear resistance of parts with high hardness and when a further increase in hardness is undesirable, between the alloying powder and the explosive charge include inert strip, the shape of the processed surface.

Distinctive characteristics in a stable relationship all essential features enabled:

due to the location of the alloying substances on the treated surface to exclude the operation of the installation charge at a certain distance from the treated surface;

- due to the use of EXPLOSIVES in the shape of the processed surface, and the loading of the alloying substances sliding detonation wave to carry out doping over the entire working surface of the workpiece;

- due to the use of high EXPLOSIVES and implementation of shock-wave loading to produce hardening lagerweij surface, due to the use of inert gaskets to dampen shock Volnov the e impact and thereby to exclude the padding in those cases, when this is undesirable.

Each of these essential features required, and their combination is sufficient to achieve novelty quality, new overharvest, and not the sum of the effects, not the inherent characteristics of their disunity.

The essence of the proposed technical solution is illustrated by drawings, where figure 1 shows an embodiment of the proposed method explosive working surface alloying metal products.

Figure 2 shows a variant implementation of the proposed method with the use of an inert spacer installed between the layer of doping substances and explosive charge.

The method of increasing the wear resistance of the working surface of the metal part 1 (see figure 1) is as follows. On the working surface is placed a layer of alloy material 2, for example fine alloy powder (fraction 1÷63 μm). As alloying materials can be used as the particles of the highly rigid powders and plastic particles type solid lubricant or a mechanical mixture. The explosive charge 3 repeats the shape of the workpiece and is located on the layer of the alloying substances. Initiating charge may be implemented with arbitrary side. After blowing the charge is distributed detonation wave, a stimulating substance 2 SC is liteshow shock wave. The substance flow in the shock wave together and raced on a metal surface, it penetrates deep into her material. Similarly prototype doping occurs by a complex influence on the workpiece as a stream of particles and shock waves. When using high-density EXPLOSIVES shock wave in the metal may reach $ 20-25 GPA, it is possible shock wave hardening with increasing hardness up to 20%.

The proposed method is applicable, for example, to improve wear resistance of the surface non-reinforced wheels of railway cars having a surface hardness of HB ≈300÷310. When the surface hardness can be increased by up to HB ≈360÷365. At higher values of hardness is formed incorrectly friction pair: reinforced solid surface wheel on the steel rail, which inevitably leads to increased wear of the rail.

To improve, for example, wear of the wheels of railway cars, previously subjected to thermal hardening, the method is implemented using the profiled strip 4 (see figure 2). Using as a strip of metal, for example aluminium strip can act as a structural element (boxes), as well as charge can use relatively cheap industrial EXPLOSIVES (for example, ammo the al), what a clear impact on improving the manufacturability of the proposed method.

Examples of implementation of the proposed method can be:

Example 1. On the surface of the wheels of a railroad car had a 1.5 mm layer of powder graphite-like boron nitride (H-BN). On top of the powder was put in the charge of plastic EXPLOSIVES ("seismologist-2 TU 84-114487). The charge was repeated the shape of the surface of the wheel. Initiation was carried out on the inner side of the wheel opposite the ridge. As a result, the surface of the wheel procnias to HB≈350 and depreciation decreased from 320 µm (original sample) to 20 μm (when the linear velocity of the specimen slides V=0.1 m/s, the force pressing G=2,63 kg and the test time 500).

Example 2. On the surface of the wheels of a railroad car, previously subjected to thermal hardening, had a 2 mm layer of G-BN. On top of the powder was put aluminum strip thickness of 20 mm, which had a shape of a wheel. The gasket had a hard wall in the form box, which was filled industrial EXPLOSIVES - ammonal thickness of 20 mm. Initiation was carried out on the inner side of the wheel opposite the ridge. The results showed that the surface of the wheel procnias with 348 HB to HB 363, representing 4.3%, and depreciation decreased from 320 µm (original sample) to 18 μm (linear sliding velocity of the sample V=0.1 m/s, strength priia the Oia G=2,63 kg and the test time 500).

1. The method of increasing the wear resistance of the working surfaces of metal products, including the application of explosion alloying materials in the form of powder onto the working surface, wherein in the coating the explosion layer alloying materials include working directly on the surface of the product, and above it have a charge of explosives (he), the shape of the working surface of the product, and initiate the explosive charge, arousing in the alloying substance moving shock wave.

2. The method according to claim 1, characterized in that between the layer of doping substances and explosive charge have the gasket in the shape of the processed surface.



 

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