JPH0225055B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oil-impregnated phenolic resin bearing, and its purpose is to have stable sliding characteristics from low to high loads,
It is an object of the present invention to provide an oil-impregnated phenolic resin bearing that does not damage a mating shaft, has excellent rigidity, heat resistance, and impact resistance, and can be mass-produced by injection molding. Conventionally, non-lubricated bearings include polytetrafluoroethylene (PTFE), polyamide, polyacetal, and polybutylene terephthalate. Thermoplastic resins such as polycarbonate are widely used. However, although these bearing products have excellent self-lubricating and wear-resistant properties, the range of use in which these properties are fully utilized is limited to low-speed, low-load areas; It cannot withstand use under high load conditions such as For this reason, attempts have been made to improve the load limit by blending lubricating oil into the above resins, but although the frictional properties of such oleoresins are improved compared to non-oleoresins, Since the resin is heat-resistant, it has low heat resistance and low rigidity, so if a large load is applied, it may deform or melt and sag due to frictional heat, greatly expanding the range of use. It was impossible. On the other hand, when using phenolic resin as a bearing material, it has the advantage of excellent heat resistance and rigidity, and does not melt and soften even at high temperatures. However, phenolic resin itself inherently has an extremely high coefficient of friction, and phenolic resin materials cannot be used in non-lubricated bearings. For this reason, bearing materials have been developed in which solid lubricants such as graphite, molybdenum disulfide, and PTFE are blended with phenolic resin, but there is a limit to the improvement of friction characteristics with the addition of solid lubricants alone, and the load limit Also, the properties obtained were only the same as those of the above-mentioned thermoplastic resins. In addition, in order to reduce the friction of phenolic resin materials,
Bearing materials made of cured phenolic resin laminates impregnated with oil after molding are also being studied, but these have low oil retention and require regular lubrication, so they cannot be considered completely lubrication-free bearings. Furthermore, since it is a laminated material, there is a quantitative restriction on the amount of solid lubricant, making it difficult to expect it to be effective as a non-lubricated bearing. Furthermore, in order to improve the brittleness of phenolic resin,
Glass fibers or carbon fibers have been used as reinforcing materials in combination with the above-mentioned solid lubricants, but although these fibers improve mechanical strength, they have the disadvantage of wearing out the mating shaft when used as a bearing. have. The inventors of the present invention solved the above-mentioned drawbacks of the conventional technology and, as a result of intensive research to complete a non-lubricated bearing material mainly made of phenolic resin, found that aromatic polyamide fiber was used as a reinforcing material in addition to phenolic resin, and solid lubricant was found. graphite, molybdenum disulfide,
As a result of combining one or more of PTFE powder, melamine cyanuric acid derivatives, aromatic polyester, etc., and lubricating oil as a fluid lubricant in an appropriate proportion, stable sliding over a wide range from low to high loads is achieved. We have succeeded in developing an oil-impregnated phenol bearing that exhibits the following characteristics, does not damage the mating shaft, has excellent rigidity, impact resistance, and heat resistance, and can be mass-produced into homogeneous products by injection molding. Below, the features of the phenolic resin bearing according to the present invention will be explained in more detail. As described above, the oil-impregnated phenolic resin bearing according to the present invention is characterized by exhibiting excellent sliding characteristics over a wide range from low loads to high loads. That is, under various conditions such as low speed, high load, intermittent motion, and rocking motion, where it is difficult to form a lubricating oil film,
The excellent lubricating effect of solid lubricants such as graphite and molybdenum disulfide provides good friction resistance and
Abrasion resistance is ensured, and under severe conditions of high speed and high load, lubricating oil oozes out from inside onto the sliding surface due to heat generation due to friction on the sliding surface, forming an oil film, resulting in excellent sliding characteristics. As a result, the bearing's load capacity increases dramatically. Furthermore, in the present invention, aromatic polyamide fibers are used as reinforcing materials, and these fibers not only contribute to improving mechanical strength, but also have a great effect on improving abrasion resistance. Furthermore, there is no effect of wearing out the mating shaft, which is seen in conventional glass fibers and carbon fibers. The phenolic resin used in the present invention is of course not limited to general phenolic resins, but includes boron-modified resins, silicon-modified resins, phosphorus-modified resins, heavy metal-modified resins, elastomer-modified resins,
Various other modified resins, resins in which aromatic alkyl ether and phenol are combined, resins in which 4-hydroxystyrene is polymerized, etc. are also included. The graphite, molybdenum disulfide, PTFE powder, melamine cyanuric acid derivative, and aromatic ester used in the present invention are powders that are commercially available as so-called solid lubricants. CPB30 (Chuetsu Graphite Industries), PTEF powder is Polymist F-5 (Allied Chemical Co., Ltd.), melamine cyanuric acid derivative is MCA
(Yuka Melamine Co., Ltd.), aromatic polyester is E-
101 (Sumitomo Chemical Co., Ltd.), and these may be used alone or in combination of two or more. The particle size of solid lubricants is 1 to 200 microns, especially
Preferably 10 to 100 microns. If the particle size is too large, problems arise in uniform mixing properties, moldability, etc., and it becomes difficult to obtain a dense molded product without voids. The amount of solid lubricant added is preferably 10 to 50 wt%, depending on the type of solid lubricant used, but for example, when graphite is used alone, it is 20 to 40 wt%,
In the case of molybdenum disulfide alone, 25 to 45 wt% is desirable. Note that the percentages shown below indicate weight percentages unless otherwise specified. If the amount added is less than 10%, the effect of adding the solid lubricant is small, resulting in large variations in properties and making it difficult to obtain sufficient friction and wear resistance. If it exceeds 50%, the mixability and moldability of the material will deteriorate significantly, and the strength of the material will decrease. Examples of the aromatic polyamide fibers used in the present invention include Kevlar-49 manufactured by DuPont in the United States, Nomex, and Cornex manufactured by Teijin, and the addition of these fibers only improves the mechanical strength of the bearing material. This also improves wear resistance. The amount of the fiber added is preferably 5 to 25%, particularly 10 to 15%. That is, if the amount added is less than 5%, the effect as a reinforcing material will not be sufficiently exhibited, and if it is more than 25%, uniform mixing properties and moldability will be significantly impaired. Next, the lubricating oil used in the present invention includes all mineral oils ranging from light oils to heavy oils such as spindle oil, liquid paraffin, machine oil, turbine oil, refrigeration oil, cylinder oil, and gear oil. Various synthetic lubricating oils such as synthetic hydrocarbon, ester, and silicone lubricants can be used. Furthermore, even if various additives such as extreme pressure additives and antioxidants are added to the lubricating oil, no problem will arise. The appropriate amount of lubricating oil to be added is 1 to 10%.
In other words, if the amount added is less than 1%, a sufficient lubricating effect cannot be obtained, and if it exceeds 10%, it becomes difficult to uniformly disperse the lubricating oil, resulting in extremely poor formability and a significant decrease in mechanical strength. descend. When blending the lubricating oil, carriers such as various metal salts and activated carbon may be used, or it may be added directly to the blended materials. In either case, uniform dispersion can be achieved by using a melt kneader such as a heating roll. The present invention was completed by combining the experimental results as described above. EXAMPLES Below, the manufacturing method and structure of the phenolic resin bearing according to the present invention will be explained based on examples, and the effects of the present invention will be explained in comparison with comparative examples described later. In the following Examples and Comparative Examples, the phenolic resin used was a novolac type phenolic resin powder, Millex 2410 (manufactured by Mitsui Toatsu Co., Ltd.).
The aromatic polyamide fiber used was Cornex (manufactured by Teijin), 2 denier, and cut length 1 mm. Example: 45 parts (by weight) of novolac-type phenolic resin powder, flaky natural graphite 35〃 Molybdenum disulfide 5〃 Aromatic polyamide fiber 10〃 Turbine oil 5〃 are mixed together, melted and kneaded, and further cooled and crushed. A molding material was obtained. Using an in-line injection molding machine, this molding material was molded at a mold temperature of 180°C and a curing time of 45 seconds.
A bush-shaped bearing test piece measuring 23 x 15 mm was prepared.
This test piece was tested using a radial/journal bearing tester at a load of 10 kg/cm ² and a sliding speed of 30 m/min.
The sliding characteristics were measured under the following conditions: test time 70 hours (continuous operation), mating shaft structural carbon steel (S45C), no lubrication. Next, regarding these results and the results of measuring the load limit (limit PV value) by the cumulative load test described later using the test piece of the comparative example described later,
A comparison of bearing characteristics was as shown in the table. Next, as a comparative example to the above example,
Bush-shaped bearing test pieces having three types of compositions were prepared in the same manner as in the above example, and bearing characteristics were measured under the same conditions as in the example. Comparative example Novolac type phenolic resin powder 45 parts Scale-like natural graphite 40〃 Molybdenum disulfide 5〃 Aromatic polyamide fiber 10〃 Comparative example Novolac type phenolic resin powder 45 parts PTFE resin powder 45〃 Aromatic polyamide fiber 10〃 Comparative example Novolac type phenolic resin powder 45 parts Wood powder 30〃 PTFE resin powder 25〃 As shown in the table, the friction coefficient, amount of wear, and limit load are all extremely superior.

[Table] Next, for each test piece above, radial,
Using a journal type testing machine, without lubrication, with the mating shaft made of structural carbon steel (S45C), a cumulative load test was conducted every 30 minutes at speeds of 30 m/min and 60 m/min. The changes in the coefficients are shown in FIGS. 1 and 2. That is, as shown in the figure, the test piece of the example (a in the figure) showed an extremely stable state with no increase in the friction coefficient regardless of the cumulative load or the passage of operating time, but the test piece of the comparative example (b in the figure) The friction coefficients of the test pieces c) and (d) in the figure increased rapidly, and a seizure phenomenon occurred at the X point in each case. As detailed above, the phenolic resin bearing according to the present invention maintains stable and excellent sliding characteristics from low loads to high loads, and does not damage the mating shaft compared to conventional products. The bearing does not have any drawbacks such as seizure or seizure, has good rigidity, impact resistance, and heat resistance, and can be mass-produced by injection molding.

[Brief explanation of drawings]

FIG. 1 illustrates the change in friction coefficient with respect to the cumulative load of each test piece at a sliding speed of 30 m/min. Figure 2 also shows the test results at a sliding speed of 60 m/min. In the figure, a... Example, b... Comparative example, c...
Comparative example, d... Comparative example, each test result is shown, and X shows the seizure point of the bearing material.

Claims (1)

[Claims] 1 Phenol resin, 5 to 25 wt% aromatic polyamide fiber as reinforcing fiber, graphite, molybdenum disulfide, melamine cyanuric acid derivative, PTFE powder, and aromatic polyester as solid lubricants, each alone or in combination of two or more. Things 10~
Knead and blend 50wt% and lubricating oil 1 to 10wt%,
An oil-free phenolic resin bearing that is manufactured by injection molding.