JPS62227003A - Double-layered bearing - Google Patents

Abstract

PURPOSE:To obtain a double-layered bearing consisting of a high-strength resin layer which prevents seizure in a boundary lubrication state by impregnating resin powder obtd. by cocoagulation of a tetrafluoroethylene resin and solid lubricating agent onto a porous sintered metallic layer formed on a steel sheet, then subjecting the layer to coating and calcination. CONSTITUTION:The pulverized powder of the solid lubricating agent such as lead-tin alloy is uniformly dispersed and mixed into and with the tetrafluoroethylene resin, by which the two components of the above-mentioned tetrafluoroethylene resin 2 and the lead-tin alloy 3 are uniformly dispersed and the resin powder 1 subjected to the cocoagulation is obtd. On the other hand, a porous layer 6 consisting of bronze, etc., is sintered and formed on a backing metal 7 consisting of a steel plate. The above-mentioned resin powder 1 is impregnated via an org. solvent into the porous sintered layer 6. After said solvent is removed by heating, the coating is calcined and the resin layer 5 is formed. The double-layered bearing material 4 having excellent load resistance and wear resistance is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION <Object of the Invention> Industrial Application Field The present invention relates to a multi-layer bearing, and more particularly to a multi-layer bearing suitable for a shock absorber bushing for an automobile.

Conventional technology Various techniques have been used since the past. ! ill bearings have been proposed and implemented. For example, Japanese Patent Application Laid-open No. 54-86041 discloses that a porous layer lined with a fully flexible metal backing contains tetrafluoroethylene resin (hereinafter referred to as PTFE resin) as the main component, and contains lead fluoride and lead-tin. Bearing materials impregnated with alloys or mixtures with lead are described. Although this bearing has poor lubricity and is made of a good material, it is not necessarily satisfactory when used in a reciprocating motion that is subjected to a fluctuating load, such as in a shock absorber.

Recently, the lubrication conditions for shock absorbers have become more severe than before due to factors such as 1) lower viscosity oil due to measures against cold regions, and 2) higher loads in sliding motion due to cost reduction and weight reduction. .

For this reason, in areas where sliding parts make uneven contact, the oil film often breaks and a state of boundary lubrication occurs, increasing frictional resistance, making it difficult to achieve smooth sliding, and tending to increase the amount of wear.

Under these circumstances, conventional multilayer bearings such as those mentioned above have problems with the load-bearing and wear resistance of the bearing surface, and under boundary lubrication conditions, the resin that forms the bearing surface wears out and seizes. There is also. The reason for this is that the strength of the resin layer present as a film several tens of microns thick on the porous sintered body is weak. In other words, the bond between the resins is weak, and the bond between the resin and the filler is weak.

In conventional multilayer bearings, the porous sintered layer contains 1) PT
base consisting of a mixture of FE resin dispersion (aqueous dispersion) and filler] or 2) impregnating a porous sintered body with a mixed powder of PTFE resin powder and filler;
In the case of 1), the particle size of the PTFE resin in the paste is as small as 0.2-0.4u.
Furthermore, since PTFE particles are dispersed in water or an organic solvent, even if they are heated and baked to bond them together, the bonding strength between the PTFE particles is weak.
The force to hold and fix the FE resin filler is weak, and a strong film cannot be removed.In addition, in case 2, the average particle size of the PTFE resin powder is as large as 500μ, so the particle size mixed as the filler is 50μ. There was a problem in that it was difficult to uniformly disperse the following solid Ill lubricant, and stable film strength could not be obtained.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically provides a multilayer bearing in which the strength of the resin layer is improved in order to prevent seizure in a state of boundary lubrication. The purpose is to

<Structure of the Invention> Means for Solving the Problems and Their Effects The present invention co-coagulates a tetrafluoroethylene resin and a solid lubricant on a porous metal sintered layer formed on a steel plate. It is characterized by a mouth that is impregnated with a resin powder produced by the above method and then coated and fired.

Hereinafter, the configuration and operation of the present invention will be explained using the drawings.

Figure 1 is an enlarged view of an example of co-coagulated powder;
The figure is an enlarged longitudinal sectional view of an example of a multilayer bearing according to the present invention.

The PTFE resin powder and lead-lifting metal powder used in the present invention are not simply a mixture of these components in powder form, but two types of components co-coagulated together in one powder. Two components are uniformly dispersed in one powder particle. Therefore, since the lead-tin alloy is uniformly dispersed in the powder whose main component is PTFE resin, the effect of adding the lead-tin alloy can be further increased. Mechanical strength and wear resistance can also be improved, and cavitation improvement effects can also be achieved.

To explain in more detail, first, in order to make a bearing with excellent load carrying capacity and wear resistance, for example, PTFE resin and lead-tin alloy are combined into a porous material obtained from metal powder such as bronze powder. The coagulated composite resin powder is repeatedly impregnated and fired to form a bearing layer on the surface. At this time, the bearing layer is made of PTFt resin 7 resin 70 body 95 and lead-tin alloy 5 to 30%. In addition, the powder in which these components are co-coagulated refers to the resin-in-PTFE resin.
This powder is made by uniformly dispersing and mixing tin alloy fine powder and co-coagulating it, and as shown in Figure 1, this powder has two components, PTFE resin 2 and lead-tin alloy 3, uniformly contained in powder particles 1. distributed in

Generally, raw materials for molding PTFE resin can be roughly divided into three types depending on the molding method. Molding powder for compression molding, fine powder for base extrusion, and dispersion for painting and coating. Among these, fine powder and dispersion are used for impregnating and repeatedly coating porous bodies such as multilayer bearings. All of these are obtained from emulsion polymerization of intermediate products of PTFE resin, and by coagulating this emulsion polymer, fine powder can be obtained, and by layering, dispersion can be obtained. Co-coagulated powder is primary particles of PTFE resin in the state of emulsion polymer (diameter 0.2~
0.4μ) and lead-advanced gold powder are uniformly mixed and coagulated, and the appearance is that the powder is agglomerated secondary particles of a uniformly mixed lead-tin alloy with an average size of about 500μ.

For this reason, it has become possible to achieve mixing uniformity and increase the mixing ratio of fillers, which could not be achieved by mixing fillers with conventional fine powders, and base extrusion has become possible as a molding method. Therefore, the strength of the resin layer is determined by the fact that the powder easily turns into fibers and gets entangled with each other during molding, and the filler is easily wrapped between the fibers, which strengthens the bond between the resins and the bond between the resin and the filler. Significant improvements in physical properties were observed.

Furthermore, solid lubricants will be explained.

The solid lubricant used here improves the load resistance without impairing the low abrasion properties of the PTFE resin, and is chemically stable with oil.

That is, graphite, carbon powder, carbon fiber, molybdenum disulfide, lead-tin alloy, etc.

Example Next, examples will be described.

First, as shown in Fig. 2, a strip steel plate 7 (thickness 1.20 @)
A porous layer 6 (bronze thickness 0.3 mm) is sintered, and a co-coagulated powder (16 mesh or less) of 85% PTFE resin and 15% lead-tin alloy moistened with an organic solvent is placed on the top. After spraying, it was pressed in with a roll.

Next, after removing the organic solvent by heating,
After baking for 0 minutes to bring the powders into close contact with each other, the powder was further rolled down using rolls to adjust the dimensions, thereby obtaining a multilayer bearing 4 with a resin layer 5 formed on its surface.

On the other hand, the comparative materials are a mixed powder of 85% PTFE resin powder (fine powder) and 15% lead-tin alloy powder (7 in comparative sample 1), 85% PTFE resin, and 15% lead-tin alloy powder. A comparative sample was obtained by similarly impregnating a paste obtained by mixing a PTFE resin dispersion and a lead-tin alloy powder (comparative sample lio, G) into the porous material.

The bearing material obtained in this way was tested using a Suzuki 2mm wear tester to determine the load capacity, wear resistance, and I
The scratch resistance was evaluated. Specifically, a load of 20 klJf/j was accumulated every hour in a low-viscosity strut oil that tends to become in a state of boundary lubrication, and the limit load was determined and compared.

At the same time, a cavitation test was conducted under the conditions shown in Table 2 for the purpose of evaluating the film strength of the resin layer. It was found that the limit load was larger than that of Na7, and the cavitation resistance was also superior to that of the comparative sample.

In addition, in order to further compare the effects of the present invention,
Co-coagulated powder (comparative sample H@, 8) of PTFE resin and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (hereinafter referred to as PFA resin 7S;) described in No. 014315 was prepared under the same conditions as above. Impregnated with, repeated firing and
When this composite bearing was subjected to a Suzuki Ni FJ abrasion test and a cavitation test, it was found to be equivalent in terms of cavitation, but inferior to the product of the present invention in terms of load resistance. Further, when similar tests were conducted with different blends of lead-tin alloys in the multilayer bearing according to the present invention, the load resistance and cavitation were the same for Pb-3n alloys of 5 to 20%. Note that the criteria for cavitation in Table 3 are as follows.

A: There is almost no change. B: Part of the resin layer has been removed.

C...The resin material is completely removed and the sintered body is exposed.
Effects of the Invention> As explained above, the present invention provides resin powder obtained by co-coagulating tetrafluoroethylene resin and a solid lubricant on a porous metal sintered figure formed on a steel plate. It is a multi-layer bearing characterized by being impregnated with oil and sintered, and the viscosity of the oil decreases during reciprocating motion under fluctuating loads, and as the load increases, a boundary lubrication state can occur. It has excellent wear resistance and friction properties even under severe conditions, so it is especially suitable for applications where high loads are applied, such as shock absorber bushes or piston rings.
It has a large effective limit load and excellent cavitation resistance.

It goes without saying that this multilayer bearing is also effective when applied to bearings used in general machine tools and the like.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of an example of co-coagulated powder, and FIG. 2 is an enlarged longitudinal sectional view of an example of a multilayer bearing according to the present invention. Code 1...Co-coagulated powder 2...pTFEffl fat 3...
Lead-tin alloy 4...Compound bearing material 5...
・Resin layer G...Sintered porous question 7...
Steel plate backing metal patent applicant KonuDC Co., Ltd. Representative Patent attorney Yoshikatsu Matsushita Lawyer Deputy Fumiyu Shima

Claims (1)

[Claims] A porous metal sintered layer formed on a steel plate is impregnated with resin powder obtained by co-coagulating tetrafluoroethylene resin and a solid lubricant, and then fired to cover the surface. A multi-layer bearing featuring: