JPS5824648B2 - Oil-impregnated resin bearing - Google Patents

Description

[Detailed description of the invention] This invention relates to oleoresin bearings.

Conventionally, synthetic resins such as polyamide, polyacetal, polybutylene phthalate, polycarbonate, and polytetrafluoroethylene have been widely used as oil-free sliding bearings.

All of these materials have excellent self-lubricating and wear-resistant properties, but the range of use in which these properties can be fully utilized is limited to low-speed, low-load areas, and they cannot be used under high-load conditions. had an intolerable flaw.

For this reason, in order to withstand even under high load conditions,
Attempts have been made to impregnate the above-mentioned resins with lubricating oil to improve friction resistance and wear resistance, and to improve the limit PV value.

For example, activated carbon, synthetic rubber, metal salts, etc. are used as a lubricating oil carrier, and a mixture of these, lubricating oil, and synthetic resin is melt-kneaded and molded to form an oleoresin bearing. In the above-mentioned oleoresin bearing, activated carbon, synthetic rubber, metal salt, etc. used as a lubricating oil carrier have poor lubricity by themselves, and the above-mentioned carrier exposed on the sliding surface,
Since contact with the mating material is forced, it has been difficult to obtain good friction and wear characteristics.

In addition, since the above-mentioned oleoresin has not been essentially improved in terms of low thermal conductivity and high coefficient of linear expansion, it is easily affected by frictional heat accumulation on sliding surfaces under high speed and high load conditions, and as a result, its dimensions It lacks stability and also has the disadvantage of clinging to the mating material and being prone to melting and burning.

In view of the above-mentioned drawbacks, the present inventors conducted extensive research and testing with the aim of obtaining an oil-impregnated bearing material with excellent friction resistance, wear resistance, and dimensional stability. We discovered that expanded graphite is the most suitable material to have excellent lubricant adsorption ability, high thermal conductivity, low coefficient of linear expansion, and lubricating properties.Based on this knowledge, we developed this book. This led to the invention.

That is, the gist of the present invention is to heat-treat expanded graphite at 300°C to 1000°C and expand it in the C-axis direction. 5 to 20% by volume, 1 to 20
% by volume of lubricating oil, graphite/lubricating oil is 1(f,/ICC~
It was formed from a homogeneous mixture of 1 to 30% by volume of sprayed Kelmet powder or bronze powder, and the remaining volume% of a synthetic resin having self-lubricating properties and wear resistance, into a mixture pre-soaked with gold to give an ICC of 15CC. This is an oleoresin bearing characterized by the following.

In the above, expanded graphite refers to an interlayer compound obtained by oxidizing natural graphite with a high degree of crystallinity using an oxidizing agent.It expands irreversibly when heated and adsorbs various liquid components. Refers to graphite that exhibits porosity.

Next, this invention will be explained in more detail.

The oleoresin bearing material of this invention is made of expanded graphite of 3008C.
By heat treatment at ~1000°C, the graphite is expanded in the C-axis direction to obtain porous graphite having lubricating oil adsorption ability,
Add lubricating oil to this in a volume ratio of graphite/lubricating oil ICC, /Icc.
, ~ICC15Cf-, the lubricating oil is uniformly impregnated into the graphite, and the graphite and lubricating oil thus mixed are mixed with each other for graphite of 0.5 to 20% by volume and lubricating oil of 1 to 20% by volume. , sprayed kelmet powder or bronze powder 1-30% by volume
The remaining volume percent of a synthetic resin having self-lubricating properties and wear resistance, such as polyacetal resin, polybutylene terephthalate resin, polyamide resin, or polycarbonate resin, is blended, uniformly kneaded, and molded into a predetermined shape.

It is also possible to form a uniform layer on the inner surface of the metal sleeve for a bearing.

In the above explanation, the reason why the amount of graphite is set to 0.5 to 20% by volume is that if the amount of graphite is more than 20% by volume, the mechanical strength of the bearing will be weakened, and if it is less than 0.5%, the mechanical strength of the bearing will be weakened. This is because the amount of lubricating oil that can be contained becomes too small and a sufficient lubricating effect cannot be achieved.

The reason why the amount of lubricating oil is set to 1 to 20% by volume is 1. For the same reason as the graphite mentioned above, if it is more than 20% by volume, the mechanical strength of the bearing will be weakened, and if it is less than 1% by volume, it will affect the sliding surface. This is because the supply of lubricating oil to the bearings becomes small, making it impossible to obtain satisfactory friction and wear characteristics.

Furthermore, in the above formulation, it is most preferable that the ratio of graphite to lubricating oil be approximately 1:1 to 15 by volume.

In addition, the reason why the content of metal powder was set to 1 to 30% by volume is as follows.
This is because if the amount is more than 30% by volume, the mechanical strength will be weakened and the load resistance will be reduced, and if it is less than 1%, no improvement in thermal conductivity or reduction in the coefficient of linear expansion can be expected.

Next, examples of the present invention will be described.

5% expanded graphite was impregnated with 10% lubricating oil, this was mixed with 15% Kelmet powder and 70% polyacetal resin, and a bearing with dimensions 8m1 x 15mm x 15mm was formed by injection molding, and a rotating shaft made of 545C with a surface roughness of 3S was formed. It was operated continuously for 24 hours under the following conditions.

Test 1° axial load 5Ky/i Rotational speed 11000 rpm test 2° axial load 5 to 7/(i Rotational speed 3500 rpm
Wiping test 3° axial load 2Ky/i Rotation speed 8000rpm Wiping test 4° Axial load IKy/ffl Rotation speed 15000r
pm Under the above test conditions, A wear coefficient, B friction coefficient, and C bearing temperature rise were measured, and the following results were obtained.

In addition, the comparative example in the above table uses 20% lubricating oil.
and 80% polyacetal resin were uniformly mixed, molded into the same size as in the example by injection molding, and tested under the same conditions. The results are shown below.

Next, the same test was conducted using the same composition as in the above example, using bronze powder and polybutylene terephthalate resin in place of the Kelmet powder and polyacetal resin in the above example.

Based on this result, 5% expanded graphite was impregnated with 10% lubricating oil, and this was impregnated with 15% Kelmet powder, 7% nylon 66 resin.
0%, and the dimensions are 8mm x 15iiX by injection molding.
15 mm bearing molded (Example (a)), bearing molded using polycarbonate resin instead of the above nylon 66 resin (example port), polysulfon instead of nylon 66 resin in Example (a) Molded using resin (Example C), and 5% expanded graphite and 5% lubricating oil.
was impregnated with 15% blue dull powder and 75% polytetrafluoroethylene resin and molded (Example 2). Under the same test conditions as above, A wear coefficient, B friction coefficient, and As a result of measuring the C bearing temperature rise, the results shown in the table below were obtained.

As described above, this invention uses graphite, which not only functions as a lubricant adsorbent but also has lubricating properties as a sliding member, as a lubricant carrier, and also contains metal powder, which improves the coefficient of friction and wear. The amount of graphite can be made extremely small, and the degree of expansion of expanded graphite can be freely changed depending on the processing temperature, so the mixing ratio of graphite and lubricating oil can be freely selected depending on the usage conditions of the bearing. The expanded graphite used in the present invention has a linear expansion coefficient and thermal conductivity that are comparable to those of metals. Dimensional stability and molding accuracy can be expected, the temperature rise of the bearing is extremely small, and it can withstand high load and high speed usage conditions. It has various effects such as ease of manufacturing since there is no need to mold with a large clearance.

Claims (1)

[Claims] 1 Expanded graphite at 300℃
Porous graphite with lubricating oil adsorption ability obtained by heat treatment at ~1000°C and expansion in the C-axis direction 0.5 ~
Spray 1 to 30 volumes of Kelmet powder or bronze powder to 20% by volume and 1 to 20% by volume of lubricating oil, and 1 to 30 volumes of Kelmet powder or bronze powder to a pre-soaked gold mixture such that graphite/lubricating oil is 15cc of ICC,/ICC-ICC. %, and the remaining volume % is a synthetic resin having self-lubricating properties and wear resistance.