JPH0289813A - Plain bearing - Google Patents

Abstract

PURPOSE:To prevent the occurrence of fretting, to reduce the occurrence of initial wear, and to improve draping properties, fatigue resistance, and seizure resistance by a method wherein a composite plating layer formed by PTFE, Ni, and/or Co is formed on the outermost surface side of a back plate or on the outermost surface of a bearing alloy layer. CONSTITUTION:In a substance in which an aluminum or copper bearing alloy layer 2 and an overlay layer 3, where necessary, are orderly formed on the surface of a back plate 1, composite plating layers 4 and 5 of PTFE, Ni, and/or Co is formed on an outermost surface on the bearing alloy layer 2 side, on the outermost surface of the back plate 1, or the outermost surfaces of both the bearing alloy layer 2 and the back plate 2. This constitution improves adhesion of a surface on which the composite plating layer is formed, reduces a friction factor, and improves heat resistance, resulting in prevention of the occurrence of fretting. Further, this constitution improves draping properties, reduces the occurrence of initial wear through the action of the draping properties, and improves wear resistance through the presence of Ni and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sliding bearing, and more particularly to an aluminum-based and copper-based sliding bearing suitable for use in a main bearing and a connecting rod bearing of an internal combustion engine.

(Prior Art) Various types of sliding bearings made of aluminum alloys are already known. In general, aluminum-based alloy sliding bearings are made by forming a Sn-based bearing alloy layer on the surface of a backing metal, but there are other types of sliding bearings, such as Aρ formed on the surface of a backing metal.
- An overlay layer formed on a Sn-based bearing alloy layer,
It is known that an Aρ-Sn bearing alloy layer is formed on the surface of a backing metal via two layers of pure AI. In addition, copper-based sliding bearings include Cu-8n-based, Cu-Pb-5n-based, Cu-I
It is known that bearings in which an n-5n series bearing alloy is laminated on the surface of the backing metal and an overlay layer is formed if necessary are used.Recent automobile engines are designed to achieve high output and high revolutions, and as fuel efficiency increases. Since low viscosity oil is used at high temperatures in the bearing industry, the conditions for bearings are becoming more severe, and improvements in the performance of the -layer are desired.

In particular, under the above conditions, fretting wear occurs between the backing metal and the housing or connecting rod that supports it, resulting in the accumulation of wear particles or sludge buildup due to carbonization of lubricating oil on the surface of the backing metal. If the deposits mentioned above grow on the surface of the backing metal, the outermost surface of the bearing will partially bulge, resulting in a strong uneven contact within the bearing surface, causing concentrated load to occur in that area and causing early fatigue failure of the bearing. was there. Similar fretting wear also occurs in connecting rod bearings, which can lead to fatigue failure of the bearings.

Conventionally, as a countermeasure against this fretting, (a) coating the back surface of the bearing (the surface in contact with the housing) with polytetrafluoroethylene (PTFE), (b) applying a puff polishing treatment to the back surface of the bearing, or (c) coating the back surface of the bearing with polytetrafluoroethylene (PTFE); Countermeasures such as copper plating have been devised. In addition, under the above-mentioned usage conditions of recent automotive engine bearings, bearing seizure and initial wear tend to occur, and as the oil temperature in the oil pan increases to 140°C or higher, bearings suffer from fatigue at high temperatures. have become more exposed to. As a countermeasure to this problem, attempts have been made mainly to (d) improve the composition and/or structure of the sliding bearing alloy and overlay.

Traditionally, lead-based alloys have been used as overlays in bearings used under normal lubrication conditions.

On the other hand, PTFE has been used in place of lead-based alloy overlays for bearings used under dry lubrication conditions because of its excellent lubricity.

(Problem to be solved by the invention) However, in the countermeasures against fretting wear, (a)
Although this countermeasure has the effect of preventing fretting in the initial stage after the bearing is installed, the adhesion of the PTFE coating is not good, so there is a problem in that the anti-fretting effect lacks reliability. In addition, measures (2) and (3) do not provide sufficient low wear characteristics, and therefore a sufficient fretting prevention effect could not be achieved. Also,
Measures (d) have significantly improved the fatigue resistance of sliding bearings, but it has been desired to improve the fatigue resistance of sliding bearings from a structural perspective.

On the other hand, when using PTFE as an overlay, P
Because the adhesion of the TFE coating was poor, it sometimes peeled off before it could function as an overlay.

In view of the above-mentioned circumstances, the present inventors conducted various studies on the structure of sliding bearings, and found that in order to provide a sliding bearing with excellent performance, a PTFE coating with excellent low abrasion properties was proposed. We found that improvements were most promising and proceeded with further research. That is, the first object of the present invention is to improve the quality of PTFE in a way that does not impair its low friction properties as much as possible.
To provide a sliding bearing with excellent fretting fatigue resistance by improving the adhesion of a coating.

The second object of the present invention is to use PTF with excellent adhesion.
The purpose of the present invention is to provide the E-coating on the shaft of a sliding bearing or the surface in contact with the bottom of the stove to improve the phosphorescence resistance, wear resistance, and high temperature fatigue resistance of the shaft.

[Means for Solving the Problems] The sliding bearing of the present invention is one in which an aluminum or copper-based bearing alloy layer and, if necessary, an overlay I cap are sequentially formed on the surface of a backing metal. A composite plating layer is formed on (a) the f& surface on the bearing alloy layer side, (b) the outermost surface of the backing metal, or (c) the outermost surface of both the bearing alloy layer and the backing metal.

(Function) A sliding bearing having the above structure has high adhesion on the surface provided with the composite plating layer, a low coefficient of friction, and high heat resistance. Therefore, in case (a), fretting is less likely to occur over a long period of time while the bearing is in use. (b)
In the case of , there is PTFE with good adhesion on the bearing surface in contact with the shaft or connecting rod, so the conformability is good. This effect reduces initial wear. Furthermore, the presence of Ni etc. improves wear resistance. In addition, these effects enhance fatigue resistance. This improvement in fatigue resistance is due to
The main components of the bearing base metal are PTFE, which has better friction properties than aluminum and copper, and Ni/Ni, which has better heat resistance.
It is thought that the provision of a coating layer that shares Co on the bearing base metal layer contributed to this.

(Example) The present invention will be described in detail below with respect to an example illustrating the above (c) in which a composite plating layer is provided on both sides of the bearing base metal layer and backing metal layer, and an overlay is provided. The configurations of embodiments (a) and (b), in which a is provided on one side, will also become clear. In Figure 1, 1 is the back fund;
2 is an overlay layer of Ae-based shaft bearing alloy scraps, 4 is a coating layer on the outermost surface of the back metal 1, and 5 is an alloy layer provided on the outermost surface of the Ae-based shaft bearing alloy layer.

As the back metal 1, a normal back metal steel plate, for example, 5PCC is used. Ap-based shaft bearing alloy layer 2, although not particularly limited, if a layer with high strength is required at the bearing operating ambient temperature (150 to 200°C), Ag with 3 to 20 wt% Sn and a total amount of 0.1 to 1 wt% %Cr, Mn, Zr, V, Mo, Co
, Nb is preferably added.

The material for the AJ2 series bearing alloy R3 includes, in addition to the above-mentioned components, 5 wt% or less of PB, and 10 wt% or less of S.
t, 1 of 2.5 wt% or less of Cu and/or Mg
More than one species may be included. The above-mentioned PB improves conformability and improves the lubricity of Sn, and Si improves wear resistance because it has a high hardness itself and the hardness of an intermetallic compound of St and the other elements. Furthermore, Cu and/or Mg have the effect of improving the strength of the material without significantly reducing its elongation.

Further, an Ag layer with low hardness may be interposed between the back metal 1 and the Aρ-based shaft bearing alloy 2 to provide a cushioning function.

Furthermore, the overlay layer 3 is made of a pb-based alloy. This Pb-based alloy includes pb, 15 wt% or less of Sn,
15wt% or less In, 5wt% or less Cu, 5wt%
It is desirable to use a material to which one or more of the following sb is added. This overlay scrap can be formed by chemical plating, electric plating, or dry plating (sputtering, etc.). For example, the upper and lower surfaces of the AQ-based shaft bearing alloy N3 may be treated, and a Ni plating or Cu plating with a thickness of 4 to 5 μm or less may be formed, and the coating may be formed on the plating.

The above-mentioned overlay layer has excellent initial conformability against shaft roughness, waviness, etc., and is easily deformed, flows, and
It wears out and becomes familiar. In addition to being highly resistant to seizure, it also has the ability to embed foreign matter.

The most significant feature of the sliding bearing according to the present invention is that it is provided with a coating 4.5 consisting of a composite plating layer consisting essentially of Ni and/or Co (hereinafter referred to as Ni-Co), and is suitable for severe engine operation. This is intended to prevent fretting and seizure from being placed below the line 1↑.

Heat resistance and adhesion are enhanced by dispersing Ni--Co in the coating layer ll, 5. Also Ni
Although -Co itself does not hinder the deposition of foreign matter, it was found that when dispersed in the coating layer 4.5, along with PTFE, it hinders the deposition of foreign matter. Ni in the coating layer
-Ni-C to mutually disperse Co and PTFE
A composite plating method must be used in which PTFE is simultaneously deposited during electrolytic plating or electroless plating.

In order to co-precipitate PTFE with N1-Co, PTFE
Since FE generally tends to aggregate or settle in a plating solution, it is necessary to take measures such as performing plating while vigorously stirring a plating solution containing PTFE and Ni--Co ions. Preferably, a positively charged polyfluorocarbon containing a cationic surfactant compound as disclosed in Japanese Patent Publication No. 56-452 is added to the plating solution. In this case, since PTFE is stably dispersed in the plating solution, the desired composite plating can be obtained without taking measures to forcefully stir the solution. The type of plating solution is not limited, but electroless plating solution is a mixture of hypophosphorous acid and nickel in an appropriate ratio, Watt Ni electrolytic plating solution, and a mixture of hypophosphorous acid and cobalt in an appropriate ratio. A CO electroless plating solution is preferred.

Ni in the coating obtained by the above plating method
- The ratio of Co and PTFE is preferably 1:0.05 to 0.
．． The ratio is 1 part by weight, more preferably 0.08 to 0.09 part by weight. The thickness of the coating ink layer is preferably 2
．． It is 5 to 15 μm, more preferably 5 to 15 μm.

In addition, the base material after Ni-Co plating is made of PTFE.
Immerse it in a liquid to disperse i! As a result, a coating having a concentration distribution with a large amount of PTFE on one surface and a large amount of Ni--Co in the center is obtained. This type of coating has a high adhesion to the base and a low coefficient of friction on the surface (the surface in contact with the shaft), so the desired properties of PTFE and Ni-Co can be effectively utilized to significantly improve the sliding bearing properties. can be done. Note that the same effect can be obtained by brushing or spray coating PTFE instead of dipping.

As optional components: Fluorocarbon (FC), tetrafluoroethylene-perfluoroalkylvinyl copolymer (PFA), etc., which improve the non-stick properties of PTFE and provide conformability, may be added to the coating.

Hereinafter, the present invention will be explained in more detail using experimental examples.

(Sample 1-Figure 2) Overlay layer 3: Pb-10%5n-2%Cu/5
μm thick Aρ-Sn bearing alloy layer 2: AL-12%5n-1, 5%Pb-2,
5%5i-1% Cu O-2%Cr Back metal 1:5PCC (Sample 2-Figure 3) N1-PTF as coating layer 4 on sample 1
Composite plating 4 of H was provided to a thickness of 15 μm. The method of composite plating was as follows.

An electroless Ni plating bath 1ρ was prepared by mixing Ni ions and hypophosphorous acid at a weight ratio of 1:1, and a cationic surfactant fluorocarbon liquid (applicant of the above-mentioned Japanese Patent Publication No. 56-452) was added to this bath. Akzo Namrose Pen Note Sharp Company's products/trade names/knife rope chair version)
A Ni-PTFE double gold plating bath was prepared by adding 40 g of Ni-PTFE. Sample 1 was immersed in this plating bath (liquid temperature 90°C) with a mask provided on overlay 3, and N1 with a thickness of 3 to 5 μm was immersed.
- PTFE composite plating coating was applied.

(Sample 3) Ni in the composite plating solution of Sample 3 was replaced with Co, the temperature of the plating bath was set to 90° C., and a coating similar to that of Sample 2 (3 to 5 μm thick) was applied while stirring.

(Sample 4 - Figure 4) N1-PTF was added as coating layer 5 to that of sample 1.
Composite plating 4 of H was provided at a thickness of 8, 15° and 20 μm, respectively. The composite plating method was the same as Sample 2.

<Sample 5) Ni in the composite plating solution of Sample 4 was replaced with Co, the temperature of the plating bath was set to 90° C., and a coating similar to that of Sample 4 (thickness 3 to 5 μm) was applied while stirring.

Table 1 (Test results) Table 2 Test conditions (blank below) (Effects of the invention) As explained above, according to the present invention, on the outermost surface of the back metal,
By providing a composite plating layer consisting essentially of PTFE and at least one of Ni and Co, fretting can be effectively and stably prevented.

In addition, by providing a composite plating layer made essentially of PTFE and at least one of Ni and Co on the outermost surface of the bearing alloy layer, initial wear is reduced and the wear resistance, fatigue resistance, and seizure resistance are improved. Improves gender, etc.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining a sliding bearing according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional sliding bearing sample, and FIGS.
The figure is a sectional view of a sliding bearing sample of the present invention. 1-backing metal, 2-bearing alloy layer, 3-overlay, 4.5-
Composite plating layer

Claims (1)

[Claims] 1. In a sliding bearing comprising an aluminum or copper-based bearing alloy layer and a backing metal, P is added to either or both of the outermost surface of the backing metal and the outermost surface of the bearing alloy layer side.
A sliding bearing comprising a composite plating layer consisting essentially of TFE and at least one of Ni and Co.