JP2005090550A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing in which abrasion or deformation is unlikely to occur even when used under a high load. <P>SOLUTION: An inner ring 1 and an outer ring 2 of a deep groove ball bearing are composed of polyolefin resin composition, and a rolling element 3 is composed of glass. The polyolefin resin composition comprises polyolefin as a resin component and potassium titanate whisker as reinforcement material. The polyolefin comprises ultra-high molecular weight polyolefin and low molecular weight to high molecular weight polyolefin. Under the presence of ultra-high molecular weight polyolefin, the low molecular weight to high molecular weight polyolefin is generated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin rolling bearing.

Conventionally, a rolling bearing used in an environment in contact with a corrosive liquid such as water or acid (for example, a rolling bearing used in an environment in contact with vapor or splash of the liquid, or used in the liquid As the rolling bearing), the inner ring, the outer ring, the cage and the like are made of polyethylene and the rolling elements are made of glass.
Japanese Patent Publication No. 8-26181 Japanese Patent Publication No. 8-26182 Japanese Patent Publication No. 8-26183 JP 2000-240666 A

However, it cannot be said that the conventional polyethylene rolling bearing as described above has sufficient wear resistance and mechanical strength. For this reason, when used under a heavy load, there is a possibility that the race part of the inner ring or the outer ring may be worn or deformed, and in the worst case, the rotation of the rolling bearing may become unstable.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a resin-made rolling bearing that solves the problems of the conventional rolling bearing as described above and is less likely to be worn or deformed even when used under a high load.

  In order to solve the above problems, the present invention has the following configuration. In other words, the rolling bearing according to claim 1 of the present invention includes an inner ring, an outer ring, and a plurality of rolling elements that are arranged to freely roll between the inner ring and the outer ring, and the inner ring and the outer ring. In a rolling bearing in which at least one of them is composed of a polyolefin resin composition, the polyolefin as a resin component of the polyolefin resin composition is composed of an ultrahigh molecular weight polyolefin and a low molecular weight to high molecular weight polyolefin, and the ultrahigh molecular weight polyolefin It is obtained by producing the low molecular weight to high molecular weight polyolefin in the presence of

  Such a polyolefin resin composition has excellent wear resistance because the ultrahigh molecular weight polyolefin is micro-dispersed in the low molecular weight to high molecular weight polyolefin. Therefore, even if the rolling bearing of this invention is used under a heavy load, it is hard to produce wear and a deformation | transformation. Further, since the polyolefin resin composition has chemical resistance against acids, alkalis, etc., the rolling bearing of the present invention can be used even in an environment where it comes into contact with a liquid having corrosive properties such as water, acid, etc. It is.

The ultra-high molecular weight polyolefin in the present invention means a polyolefin having an intrinsic viscosity of 10 dl / g or more and 40 dl / g or less measured in decalin at 135 ° C., and a low molecular weight to high molecular weight polyolefin is a 135 ° C. It means a polyolefin having an intrinsic viscosity measured in decalin of 0.1 dl / g or more and 5 dl / g or less.
The rolling bearing according to claim 2 of the present invention is the rolling bearing according to claim 1, wherein the content of the ultrahigh molecular weight polyolefin in the polyolefin is 15 mass% or more and 40 mass% or less. Features.

  When the content of the ultrahigh molecular weight polyolefin is less than 15% by mass, properties such as abrasion resistance may be insufficient. On the other hand, if it exceeds 40% by mass, the viscosity at the time of melting is high and it becomes difficult to mold by the injection molding method, and the absolute amount of the ultra high molecular weight polyolefin is increased, so that the ultra high molecular weight polyolefin is converted into a low molecular weight to high molecular weight polyolefin. It becomes difficult to disperse in the inside, and there is a possibility that the physical properties are lowered. In order to make such inconvenience difficult to occur, the content of the ultrahigh molecular weight polyolefin in the polyolefin is more preferably 20% by mass or more and 35% by mass or less.

Furthermore, the rolling bearing of Claim 3 which concerns on this invention is a rolling bearing of Claim 1 or Claim 2, The said polyolefin resin composition contains the potassium titanate whisker, The content is the said polyolefin. It is 10 mass% or more and 40 mass% or less of the whole resin composition, It is characterized by the above-mentioned.
The polyolefin resin composition may contain a reinforcing material such as potassium titanate whisker. Then, the abrasion resistance and mechanical strength of the polyolefin resin composition are further improved. When the content of the potassium titanate whisker is less than 10% by mass, the wear resistance and mechanical strength may be insufficient. On the other hand, even if the content exceeds 40% by mass, the wear resistance is not further improved, and the moldability is lowered. In order to make such inconvenience difficult to occur, the content of the potassium titanate whisker is more preferably 20% by mass or more and 30% by mass or less.

  The rolling bearing of the present invention has excellent durability even when used under high loads.

An embodiment of a rolling bearing according to the present invention will be described in detail with reference to a partial longitudinal sectional view of FIG.
The rolling bearing shown in FIG. 1 is a deep groove ball bearing having an identification number 6001 (inner diameter: 12 mm, outer diameter: 28 mm, width: 8 mm), and is formed between a resin inner ring 1, a resin outer ring 2, an inner ring 1 and an outer ring 2. A rolling element 3 made of glass that is freely rollable, and a cage 4 that holds a plurality of rolling elements 3 between an inner ring 1 and an outer ring 2 are provided.
The inner ring 1 and the outer ring 2 are made of a highly slidable polyolefin resin composition comprising 70% by mass of polyolefin as a resin component and 30% by mass of potassium titanate whisker as a reinforcing material. This polyolefin is composed of an ultra-high molecular weight polyolefin and a low to high molecular weight polyolefin. After the olefin is polymerized in the presence of a Ziegler-type catalyst to form an ultra-high molecular weight polyolefin, the olefin is further polymerized in the presence of hydrogen. Thus, it is obtained by producing a low molecular weight or high molecular weight polyolefin.

  As described above, when the polyolefin is produced by the multi-step polymerization method of producing the low molecular weight or high molecular weight polyolefin in the presence of the ultra high molecular weight polyolefin, the ultra high molecular weight polyolefin and the low molecular weight or high molecular weight polyolefin are mixed. It does not have a layered structure as in the case, and ultra-high molecular weight polyolefin is uniformly micro-dispersed between low molecular weight to high molecular weight polyolefin, and in some cases, the dispersion state is kept stable by forming a bonding state with each other. I'm leaning. Thus, by microdispersing the ultrahigh molecular weight polyolefin, the excellent wear resistance of the ultrahigh molecular weight polyolefin is expressed while maintaining the injection moldability.

  The type of polyolefin is not particularly limited, and examples thereof include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, A homopolymer or copolymer of an α-olefin such as 3-methyl-1-pentene is exemplified. In this, the homopolymer of ethylene and the copolymer which consists of ethylene and another alpha olefin and has ethylene as a main component are preferable. In addition, as long as the amount does not impair the object of the present invention, a resin other than polyolefin may be mixed with polyolefin.

  Further, since the potassium titanate whisker, which is a reinforcing material, has a low Mohs hardness of 4, even if it is exposed on the surface of the race ring due to wear of the resin composition, it is difficult to damage the rolling element that is the sliding counterpart. . Moreover, even if it falls off the raceway, it is difficult to cause scratches or wear on the raceway surface, rolling elements and cage. Therefore, this deep groove ball bearing has excellent durability and is unlikely to generate abnormal noise.

  It is possible to use a reinforcing material other than the potassium titanate whisker, but if a high hardness reinforcing material is used, the rolling elements are damaged as described above, causing problems in the durability and acoustic performance of the bearing. There is a fear. In particular, when the rolling element is made of glass, the glass has a Mohs hardness of 5, and therefore it is preferable to use a reinforcing material having a lower hardness. Thus, the reinforcing material contained in the polyolefin resin composition has a Mohs hardness of 4 or less, the rolling element is composed of a Mohs hardness of 5 or less, and the Mohs hardness of the rolling element is higher than that of the reinforcing material. If it is made large, it can be set as a rolling bearing excellent in durability and acoustic performance.

  In addition, in order to improve the thermal stability, the polyolefin resin composition contains a thermal stabilizer such as a phenolic thermal stabilizer, an organic phosphite thermal stabilizer, and an organic thioether thermal stabilizer alone or in combination of two or more. A mixture may be added. The content of the heat stabilizer is preferably 0.01% by mass or more and 5% by mass or less of the entire polyolefin resin composition. When the content of the heat stabilizer is less than 0.01% by mass, the effect of improving the heat stability is low. On the other hand, even if the content exceeds 5% by mass, the effect of improving the thermal stability is hardly changed, and the content of the resin component and the reinforcing material is decreased by that amount, which may adversely affect the wear resistance. There is. In order to make such inconvenience less likely to occur, it is more preferable that the content of the heat stabilizer is 0.1% by mass or more and 2% by mass or less of the entire polyolefin resin composition.

  Furthermore, in order to improve slidability, a lubricant composed of a higher fatty acid metal salt such as calcium stearate may be added to the polyolefin resin composition. The content of the lubricant is preferably 0.01% by mass or more and 3% by mass or less of the entire polyolefin resin composition. When the content of the lubricant is less than 0.01% by mass, the effect of improving the lubricity is low. On the other hand, even if the content exceeds 3% by mass, the effect of improving the lubricity is hardly changed, and the content of the resin component and the reinforcing material is decreased by that amount, which may adversely affect the wear resistance and the like. is there. In order to make such inconvenience less likely to occur, the content of the lubricant is more preferably 0.1% by mass or more and 2% by mass or less of the entire polyolefin resin composition.

The material of the rolling element 3 is not limited to glass, and the same polyolefin resin composition as that of the inner ring 1 and the outer ring 2 may be used. However, considering durability, silicon nitride, silicon carbide, sialon, zirconia, alumina It is preferable to use ceramic such as glass or glass. However, in consideration of durability and cost, glass is most preferable.
The material of the cage 4 is not particularly limited, but it is preferable to use the same polyolefin resin composition as the inner ring 1 and the outer ring 2. However, in the case of the cage 4, there is no problem even if a polyolefin resin composition containing a reinforcing material other than the potassium titanate whisker is used. This is because the possibility that the cage is worn and the reinforcing material is exposed or dropped is low, and the possibility that the raceway surface and the rolling element are damaged or worn as described above is low.

The material of the cage 4 may be a fluororesin that can be melt-molded. The melt-moldable fluororesin includes tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride (PVdF), tetrafluoroethylene-hexafluoro. Examples include propylene copolymers. A reinforcing material such as aluminum borate whisker, potassium titanate whisker, carbon whisker, silicon carbide whisker, and wollastonite, a solid lubricant, or the like may be further added to the fluororesin.
〔Example〕
Hereinafter, the present invention will be described more specifically with reference to examples. Test bearings (Examples 1 to 4 and comparative example) having the same configuration as the deep groove ball bearing of FIG. 1 described above except that the materials of the inner ring, outer ring, rolling element, and cage are as shown in Table 1. Prepared.

The materials listed in Table 1 are as follows.
・ Highly slidable special polyethylene: Lübmer L4000 manufactured by Mitsui Chemicals, Inc.
・ High-density polyethylene: Jyrex HD KM490K manufactured by Nippon Polyolefin Co., Ltd.
ETFE: Neoflon ETFE EP-520 manufactured by Daikin Industries, Ltd.
・ Potassium titanate whisker: Tismo D manufactured by Otsuka Chemical Co., Ltd.
In Table 1, high-sliding special polyethylene is described as special PE, high-density polyethylene as high-density PE, and potassium titanate whisker as PTW.

These test bearings are mounted on a bearing rotation tester as shown in FIG. 2 and subjected to a rotation test (inner ring rotation) in a sulfuric acid aqueous solution having a concentration of 0.5 mol / L. (Lifetime) was evaluated. The conditions of the rotation test are as follows.
・ Radial load: 49N
・ Axial load: 49N
・ Rotation speed: 100min ^-1
The test results are also shown in Table 1. The time until the vibration value of the bearing exceeded three times the initial value was defined as the life of the bearing. The life of each bearing is shown as a relative value when the life of the comparative example is 1.

  As can be seen from Table 1, since the bearings of Examples 1 to 4 are made of a resin composition in which the inner ring and the outer ring contain high-sliding special polyethylene, the comparative example is made of high-density polyethylene. Durability was superior compared to bearings. In particular, the bearings of Examples 1 and 2 are composed of a resin composition containing a potassium titanate whisker as a reinforcing material, which has reinforcement and chemical resistance and has low damage to the counterpart material. The property was very good. Since the bearing of Example 4 is composed of a resin composition containing glass fiber as a reinforcing material, it is highly scratchable to the counterpart material and is composed of a resin composition that does not contain a reinforcing material. The durability was lower than that of the bearing of Example 3.

  In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in this embodiment, a deep groove ball bearing has been described as an example of a rolling bearing. However, the type of rolling bearing is not limited to a deep groove ball bearing, and the present invention is applicable to various types of rolling bearings. Can be applied. For example, radial type rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

  The rolling bearing of the present invention can be suitably used for food machinery, agricultural machinery, semiconductor-related equipment, and the like, and can be used even in an environment where it comes into contact with a corrosive liquid such as water or acid.

It is a fragmentary longitudinal cross-section which shows one Embodiment of the rolling bearing which concerns on this invention. It is the schematic which shows the structure of the bearing rotation test machine which evaluates durability of a bearing.

Explanation of symbols

1 Inner ring 2 Outer ring 3 Ball 4 Cage

Claims (3)

A rolling device comprising an inner ring, an outer ring, and a plurality of rolling elements that are arranged to roll between the inner ring and the outer ring, and at least one of the inner ring and the outer ring is made of a polyolefin resin composition. In the bearing
The polyolefin that is a resin component of the polyolefin resin composition comprises an ultrahigh molecular weight polyolefin and a low molecular weight or high molecular weight polyolefin, and is obtained by forming the low molecular weight or high molecular weight polyolefin in the presence of the ultrahigh molecular weight polyolefin. A rolling bearing characterized in that the rolling bearing is provided.   The rolling bearing according to claim 1, wherein the content of the ultrahigh molecular weight polyolefin in the polyolefin is 15 mass% or more and 40 mass% or less.   The said polyolefin resin composition contains potassium titanate whisker, The content is 10 to 40 mass% of the whole said polyolefin resin composition, The Claim 1 or Claim 2 characterized by the above-mentioned. The rolling bearing described.

Images