JPH04345667A - Sliding material - Google Patents

Abstract

PURPOSE:To provide a bearing which contains a metallic powder mixed therein, can be mass-produced, is abrasion-resistant, and has a low friction coefficient. CONSTITUTION:A sliding material which is injection-moldable and prepd. by mixing a synthetic resin (e.g. polyphenylene sulfide) with 20-40wt.% finely powdered lead and 20-40wt.% polytetrafluoroethylene powder.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding material, and more particularly to an injection moldable sliding material containing no metallic fine powder.

0002

2. Description of the Related Art Conventionally, composite bearings have been used to improve mechanical strength, dimensional stability, thermal conductivity, etc., which are disadvantages of resin-integrated bearings. As this composite type bearing, a metal composite type bearing made of a plurality of metal components, inorganic compounds, etc., and a synthetic resin type composite type bearing made of a metal component, a synthetic resin component, etc. are known.

0003

[Problems to be Solved by the Invention] However, bearings containing fine metal powders require sintering in the forming process, and may require multiple processes and complex treatments in some of the processes. There is also. This increases the manufacturing cost of the bearing. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a bearing containing fine metal powder that can be mass-produced, has wear resistance, and has a low coefficient of friction.

0004

[Means for Solving the Problems] The above object of the present invention is to use a synthetic resin as a base resin,
This is achieved by adding and kneading 0% by weight of lead fine powder and 20 to 40% by weight of polytetrafluoroethylene powder to make the sliding material moldable by injection molding.

1) Base Resin A synthetic resin is used as the base resin of the present invention and as a binder for sliding material components. If priority is given to productivity during molding, thermoplastic resin is desirable. Furthermore, in order to achieve a high limit PV value as a sliding material, it is desirable to use so-called engineering plastics that have excellent heat resistance. Specifically, resins such as polyacetal, polyamide, polyphenylene sulfide, liquid crystal polyester, and polyether nitrile can be used. Polyphenylene sulfide (PPS) resin is a resin with excellent mechanical strength and heat resistance, and is optimal in terms of cost performance. Moreover, this resin does not oxidize fine lead powder during kneading or molding, nor does the resin itself decompose. Furthermore, among these, linear PPS resins have slightly better sliding properties and weld strength than crosslinked ones, and can contain a large amount of additives. Furthermore, if higher heat resistance, creep resistance, etc. are required, a thermosetting resin can be used as the base. Specifically, phenol resin, epoxy polyimide resin, etc. are used.

2) Lead Powder The lead (Pb) powder preferably has a purity of 97% or more and a size of about 200 mesh (particle size of 75 μm or less). As for the manufacturing method, the atomization method is preferable because it is less susceptible to oxidative deterioration during compounding and is less expensive than crushed products. Furthermore, if the lead powder content is less than 20% by weight, the wear resistance of the sliding material will decrease, and if it exceeds 40% by weight, the dispersibility will decrease, making it difficult to mix uniformly with a tumbler mixer, for example. This results in segregation in the molded product. At this time, the content of PTFE simultaneously decreases and the coefficient of friction increases. Lead powder is preferably 30% by weight
used in

3) Polytetrafluoroethylene (PTFE) powder is used as a lubricity improving agent because polytetrafluoroethylene base resin has poor lubricity. PTFE
The resin used is of low molecular weight, and the particle size is 0.2 to 0.3.
[mu]m, and preferably has a diameter of 5 to 8 [mu]m in the agglomerated state. Also polytetrafluoroethylene (PTFE)
If the blending ratio of powder is less than 20% by weight, wear resistance will decrease, and if it exceeds 40% by weight, the molded product will become extremely brittle and cannot be put into practical use. PTFE is preferably used at 30% by weight.

[0008]

[Operation] The base resin powder, PTFE powder and Pb powder are placed in, for example, a tumbler type mixer, and mixed by stirring for about 10 minutes. This causes the PTFE powder to generate static electricity and adhere uniformly to the outer surface of the base resin particles. Further, fine Pb powder is uniformly attached to the surface of the base resin in a form surrounded by PTFE. In this way, even powders having extremely different specific gravities can be mixed uniformly. The material in this state is put into a twin-screw kneading device to produce pellets. The kneading temperature is preferably 310°C±10°C; if it exceeds this temperature, the Pb powder will dissolve and aggregate.

[0009]

[Example] In this example, W-214 grade of Fortron (trade name), a polyphenylene sulfide manufactured by Kureha Chemical Industry Co., Ltd., was used as the base resin. In addition, in this example, Daikin Industries (
Rubron L-5 (trade name) manufactured by Co., Ltd. was used. In this example, the Pb powder was Pb-At-20 manufactured by Fukuda Metal Foil and Powder Industry Co., Ltd.
0 (trade name) was used. 70 WT% of base resin powder, 30 WT% of PTFE resin powder, and 30 WT% of Pb powder are placed in a tumbler type mixer, stirred and mixed for about 10 minutes, and then placed in a twin-screw kneading device to produce pellets. The kneading temperature was adjusted to 310°C±10°C.

[0010] The blending ratio of each of the above components is shown in Table 1 below. As comparative examples, samples were used in which the content of lead powder and the content of PTFE resin powder were varied. A sliding material having the wear coefficient and friction coefficient shown in Table 1 was obtained (values immediately after manufacture).

[0011]

[Table 1]

Next, bearings were manufactured from the sliding materials of Examples 1 to 3 and Comparative Examples 1 and 2 using a PS60 injection molding machine manufactured by Nissei Jushi Kogyo Co., Ltd. in a conventional manner, and the bearings were subjected to the following test conditions. The friction coefficient, wear dimensions, and bearing temperature changes over time were tested. Testing machine: Journal type bearing testing machine sliding speed
: 25m/min Surface pressure: 15kgf/cm2 Atmosphere temperature: 2
3℃±1℃ Lubrication conditions: Completely oil-free Mating shaft: Carbon steel for machine structure (S45C)

00
13] Figures 1 to 7 show the results of measuring changes over time while keeping P (surface pressure) and V (velocity) constant, and a summary is shown in Figure 8. In Examples 1 to 3, the coefficient of friction shows a stable value even after long-term use, and the rate of change in wear dimension is relatively slow. In particular, in the case of Example 1, which is an example of the present invention having an optimum composition, the wear dimension was 0.05 μm/hour, showing particularly favorable performance. On the other hand, the comparative example had large initial wear.

[0014] The above test data was obtained by looking at the sliding characteristics while keeping the PV value constant, and the results of measuring the limit PV value are shown in FIG. As is clear from the figure, it has become clearer that the bearing of this example is superior.

Furthermore, under the same conditions, the friction coefficient of a conventional multilayer bearing (commercially available DU dry bearing) in which a bronze sintered layer is formed on a steel backing metal, and a layer of PTFE and Pb is formed on the sintered layer. Figure 10 shows the changes in wear dimensions over time.

The bearing manufactured using the sliding material of this example has a large sliding area ( This has the effect of reducing surface pressure) and preventing wear of the PTFE powder. Furthermore, it is well known that Pb powder itself also acts as a solid lubricant.

[0017]

[Effects of the Invention] The bearing obtained from the sliding material of the present invention has a stable coefficient of friction that does not change over time, and the friction dimension hardly changes even after long-term use, compared with existing bearings made of fine metal powder. It has very good performance. Another feature is that by pelletizing the compound, it can be injection molded and mass-produced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing changes over time in the friction coefficient of Example 1 of the present invention.

FIG. 2 is a diagram showing changes over time in wear dimensions in Example 1 of the present invention.

FIG. 3 is a diagram showing changes in bearing temperature over time in Example 1 of the present invention.

FIG. 4 is a diagram showing changes over time in friction coefficient, wear size, and bearing temperature in Example 2.

FIG. 5 is a diagram showing changes over time in friction coefficient, wear size, and bearing temperature in Example 3.

FIG. 6 is a diagram showing changes in friction coefficient, wear size, and bearing temperature over time in Comparative Example 1.

FIG. 7 is a diagram showing changes over time in the friction coefficient, wear size, and bearing temperature of Comparative Example 2.

FIG. 8 is a diagram showing the average coefficient of friction and the rate of change in wear dimension at a constant PV value for the embodiments of the present invention and comparative examples.

FIG. 9 is a diagram showing the limit PV values of the embodiments of the present invention and comparative examples.

FIG. 10 is a diagram showing changes over time in the friction coefficient and wear size of a conventional multilayer bearing.

Claims (1)

[Claims] [Claim 1] Using a synthetic resin as a base resin,
On the other hand, 20-40% by weight of fine lead powder and 20-40% by weight
A sliding material characterized by being made injection moldable by adding and kneading 0% by weight of polytetrafluoroethylene powder.