RU2242338C2 - Method of anode-mechanical honing - Google Patents

Abstract

FIELD: processes and apparatuses for working internal surfaces of revolution, possibly restoration works.

SUBSTANCE: method comprises steps of working part-anode by means of hone-cathode having metallic cathode members of anti-friction material; using liquid glass base working liquid; working surface at modes preventing occurring of while layer; then applying anti-friction coating due to rubbing by means of working cathode members when technological current is cut off; using working liquid containing, mass %: glycerin, 10 - 30; sodium chloride, 1 - 10; liquid glass (specific gravity 1.15 - 1.3), the balance.

EFFECT: enhanced wear resistance and running in capability of internal surfaces of revolution due to lowered crumbling out and additional anti-friction coating.

2 cl, 1 tbl, 1 ex

Description

The invention relates to mechanical engineering, in particular to methods of anodic-mechanical processing of internal surfaces of revolution, and may find application in the repair business.

A known method of anodic-mechanical grinding grinding holes, including processing in a working fluid based on liquid glass with a hone cathode with electrically neutral working elements, due to electrochemical dissolution and abrasive cutting of the treated surface [1].

The disadvantage of this method is the low wear resistance of the treated surface due to directional roughness and its sharpening with abrasive particles.

There is a method of anodic-mechanical honing of cylinder liners of automotive engines in a working fluid based on liquid glass with a hon-cathode with metal working elements, for example, of antifriction material, in which the preliminary processing is carried out in modes with a predominance of electrical discharge processes to obtain a white layer with a thickness of 0.15. ..0.17 mm, after which the surface is refined in modes with a predominance of electrochemical dissolution, while maintaining a white layer (prototype) [2].

The disadvantages of this method are the poor abrasion of the surface and the chipping of its particles due to the formation of a large number of cracks in the surface white layer, its high hardness and brittleness.

The present invention solves the problem of increasing wear resistance and improving the running time of the inner surfaces of rotation by reducing spalling and additional application of an antifriction coating.

The specified technical result is achieved by the fact that in the anodic-mechanical honing method, comprising treating the anode-part with a hon-cathode, made with metal elements-cathodes of antifriction material, with the supply of a working fluid based on liquid glass, the above-mentioned surface treatment is carried out in modes not allowing the occurrence of a white layer, after which an antifriction coating is applied by rubbing with cathode working elements with the technological current switched off.

The use of anodic-mechanical honing modes, which do not allow the appearance of a white layer on the surface to be treated, leads to an increase in its wear resistance and break-in for several reasons. The white layer appears due to the high cooling rates of surface areas when exposed to electrical discharges. This layer has high hardness (HRC 45 ... 65), brittleness and is replete with cracks, which affects the running-in of such a surface and contributes to the chipping of the layer particles during friction. The separated particles of the white layer cause abrasion of the friction surfaces. In addition, as the white layer wears out, a tempered metal layer appears on the surface, having a hardness lower than the hardness of the base metal, and, accordingly, lower wear resistance.

The method is as follows.

The part is installed on the table of the honing machine in a clamping device, electrically insulated from the mass of the machine and providing a reliable current supply from the positive pole of the DC source. At the initial moment, the hon-cathode is introduced into the hole to be machined, and the reciprocating and rotational motion is turned on. During processing, the working elements are bred and the working fluid is fed into the working area. Processing is carried out in one installation of the part, and transitions from mode to mode are carried out by changing the electrical and mechanical parameters. Pretreatment is carried out in modes with an operating voltage of 13 ... 16 V, a current density of 4 ... 15 A / cm ² and a pressure of the working elements of 0.05 ... 0.15 MPa. Then, in the finishing mode with an operating voltage of 6 ... 12 V and a current density of 1 ... 5 A / cm ² , due to the anode dissolution, the roughness is reduced to R _Z = 4.5 ... 7.5 μm. After that, the technological current is turned off and rubbing by working elements-cathodes of antifriction material is carried out for 5 ... 10 passes. In the course of the entire treatment, a working fluid of the following composition is used, wt.%: Glycerin 10 ... 30; sodium chloride 1 ... 10; liquid glass - the rest.

Example. To verify the effectiveness of the proposed method were tested tribological properties of the samples on a friction machine 77 MT-1. For the manufacture of samples used cylinder liners made of ICHG-33M cast iron, treated with various options for anodic-mechanical honing. Processing modes: peripheral speed 45 ... 90 m / min, the speed of the reciprocating movement of 8.1 m / min. Pretreatment: operating values of voltage 13 ... 16 V and current density 4 ... 10 A / cm ² , specific pressure of working elements 0.05 ... 0.16 MPa. Final processing: operating voltage 6 ... 10 V, current density 0.5 ... 3.0 A / cm ² and pressure of working elements 0.1 ... 0.25 MPa. Antifriction treatment: pressure of working elements 0.9 ... 1.5 MPa. The material of the working elements is brass 62.

The test was carried out at a sliding speed of 1.56 m / min. For lubrication, M10G _1K oil was used. Counter-pattern - cast iron piston ring. Test time 25 hours

The wear of the samples was determined by weighing before and after the test. The productivity was assessed by the time until stabilization of the roughness and by the state of the surface.

The test results are shown in the table.

The use of the invention allows to improve the workability by 5 ... 7 times and increase the wear resistance of the treated surface.

USED SOURCES

1. USSR author's certificate No. 86377 of 09/20/1947.

2. H.S. Faskhutdinov, P.P. Shaikhutdinov. Improving the wear resistance of cylinder liners of automotive engines by anodic-mechanical honing // Information leaflet No. 69-99. - Kazan, Tatar TSSTI, 1999. - 2 p.

Claims (2)

1. The method of anodic-mechanical honing, including surface treatment of the anode part with a hon-cathode, made with metal elements-cathodes of antifriction material, with the supply of a working fluid based on liquid glass, characterized in that the surface treatment is carried out in modes not allowing occurrence of a white layer, after which an antifriction coating is applied by rubbing with working elements-cathodes with the technological current switched off. 2. The method of anodic-mechanical honing according to claim 1, characterized in that the working fluid of the following composition is used, wt.%: Glycerin - 10 ... 30, sodium chloride - 1 ... 10, water glass (specific gravity 1, 15 ... 1.3) - the rest.