RU2424888C2 - Method of reclaiming plain bearing - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and repair, particularly, to plain bearing recovery. Proposed method comprises sleeve pre-machining, cutting irregular thread with skewed subsequent reticule rolling, gas thermal deposition and mechanical processing. Skewed reticule rolling is performed to sleeve ID reduction by 0.5-1.0 mm of ribbing pitch to produce truncated-cone elements on sleeve surface. Deposition is carried out using bronze powder "ПР-Б" 83 (babbit metal). Proposed method allows increasing bearing operating performances, for example, adhesion strength - by 12%, relative wear resistance - by 20%, and relative bearing capacity - by 50%.

EFFECT: material saving, higher mechanical properties.

3 dwg, 1 tbl

Description

The invention relates to the field of mechanical engineering and machine repair and can be used to restore worn parts, in particular plain bearings.

A known method of restoring sliding bearings, including applying to the inner surface of the coating by thermal spraying a powder of bronze [RF patent No. 2212324, IPC V23P 6/00, Bull. No. 26, September 20, 2003].

The disadvantages of this method are the high consumption of the sprayed material due to the need to compensate for the wear of the inner surface only due to the application of additional material and low performance of the resulting sliding bearing.

The objective of the invention is to reduce the consumption of the sprayed material, increasing the adhesion strength of the sprayed layer to the base with high performance characteristics of the resulting sliding bearing.

The problem is achieved in that in the known method, which consists in pre-machining the sleeve, preparing the surface and applying a coating to compensate for wear on the inner cylindrical surface, by thermal spraying of bronze powder and subsequent machining, according to the invention, the wear of the inner surface is compensated by oblique mesh rolling and spraying the powder of bronze PR-B 83 (babbit), which is produced immediately after rolling.

The invention is illustrated by drawings, where:

figure 1 is a fragment of a surface with a chopped "torn" thread;

figure 2 is a fragment of the surface after oblique mesh rolling;

figure 3 is a fragment of the surface after spraying.

The method is as follows. To eliminate traces of wear and to give the correct geometric shape, machining is performed by boring the inner diameter of the bearing. On the inner cylindrical surface of the bearing, a "torn" thread (Fig. 1) is cut to a depth of 0.5 ÷ 1.00 mm with a thread pitch of 1.75 ÷ 2.00 mm, then oblique mesh rolling is applied to the cut thread (Fig. 2) . The corrugation pitch is taken depending on the diameter and length of the rolled surface 1.6 ÷ 2.0 mm.

In the process of rolling, the teeth of the rolling rollers are introduced into the tops of the "torn" thread. When introducing the teeth of the rollers, the tops of the “torn” thread are deformed, and the deformed metal flows inward from each tooth, in this case depressions are formed, and the metal from the depressions forms vertices. As a result of rolling, the surface layer of the bearing is hardened and the inner diameter of the sleeve decreases by a value of 0.5 ÷ 1.0 from the corrugation step, which leads to a decrease in the amount of sprayed material necessary to compensate for wear.

On the thus prepared inner surface 1 (Fig. 3), the PR-B 83 bronze powder (babbitt) is sprayed in a gas-thermal manner using the Thermica-universal gas flame burner and an antifriction layer 2 is obtained. PR-B 83 bronze powder (babbitt) provides compensation amount of wear and reduces the coefficient of friction.

The profile of the obtained surface 1 provides an increased bearing capacity of the sliding bearing due to the elements of the “truncated pyramid” type 3 obtained on the surface after machining. In this case, the upper part of the pyramid receives the load transferred by the sprayed antifriction layer 2 covering the lateral surfaces of the “truncated pyramid” 3 , improves the intensity of heat dissipation from the area of the sliding bearing.

In addition, the depressions filled with the antifriction layer 2 work as lubrication grooves, due to the high oil absorption of the antifriction layer 2, which leads to increased wear resistance.

After spraying, the bearing is machined to the nominal or repair size.

Comparative physical and mechanical properties of the bearing, restored by the proposed method and known, are shown in the table.

Table The method of restoring plain bearings The size of the sprayed layer, mm Adhesion Strength, MPa Relative wear resistance,% The relative bearing capacity,% Prototype 0.3-0.5 85 one hundred one hundred Proposed 0.2-0.4 97 120 150

Thus, the use of the proposed method for the restoration of a sliding bearing allows to reduce the consumption of sprayed material (bronze) and to increase the operational characteristics of the bearing: adhesion strength by 12%, relative wear resistance by 20%, relative bearing capacity by 50%.

Claims (1)

A method of restoring a sliding bearing, including preliminary machining of the sleeve, cutting of “torn” thread with subsequent oblique mesh rolling, gas thermal spraying and subsequent mechanical processing, characterized in that to reduce the amount of sprayed material oblique mesh rolling is carried out to reduce the inner diameter of the sleeve by 0 , 5-1.0 mm from the corrugation step to obtain truncated pyramids on the surface to be treated.

Images