JP2019002562A - Resin thrust rolling bearing - Google Patents

Abstract

To provide a resin thrust rolling bearing which inhibits wear of a raceway surface in use under a high surface pressure environment and has a product life longer than a conventional resin thrust rolling bearing.SOLUTION: A thrust ball bearing 1 includes: a bearing ring 11 having a raceway surface 11a; a bearing ring 12 having a raceway surface 12a; multiple balls 13 which are disposed between the raceway surface 11a and the raceway surface 12a so as to roll; and a retainer 14 which retains the balls 13 at regular intervals in a circumferential direction. The bearing ring 11 and the bearing ring 12 are molded bodies formed by resin compositions. A tensile elastic modulus of the molded body is 3800 MPa or higher, and a bending elastic modulus is 3400 MPa or higher.SELECTED DRAWING: Figure 1

Description

   The present invention relates to a resin thrust rolling bearing used in a corrosive atmosphere such as in water, in chemicals, or in a high humidity environment.

  In general, a thrust rolling bearing having rolling elements such as balls (balls) and rollers (rollers) is such that the rolling elements are rotatably held between the raceway surfaces of a pair of bearing rings. There are many metal bearings made of stainless steel. When such a metal thrust rolling bearing is used in a so-called corrosive atmosphere such as in water, in chemicals, or in a high humidity environment, even a stainless steel bearing, for example, may cause corrosion on the raceway surface or rolling element surface. is there.

  Corrosion of metal thrust rolling bearings is relatively high on the raceway surface and rolling element surface. To prevent such corrosion, take measures such as mounting a resin sealing cover on the bearing. It is common not to allow a corrosive atmosphere to enter. However, since it is not easy to produce a cover that can completely seal the bearing, it is difficult to reliably suppress the progress of corrosion.

  As a countermeasure against such a corrosion problem, a resin thrust rolling bearing in which a pair of race rings is formed of a synthetic resin is known (for example, see Patent Document 1 and Patent Document 2).

  The resin-made thrust rolling bearing described in Patent Document 1 includes a pair of races, a phenol resin using a cotton cloth knitted with fine or thick yarn as a reinforcing material, or an epoxy resin or polyimide resin using a glass fiber as a reinforcing material. A molded product formed of any of the above is used.

  In Patent Document 2, as a material for a pair of races, phenol resin, polytetrafluoroethylene (PTFE) resin, ultra high molecular weight polyethylene (UHMWPE), polypropylene (PP) resin, polyether ether ketone (PEEK) resin are used. , Polyphenylene sulfide (PPS) resin, polychlorotrifluoroethylene (PCTFE) resin, polyvinylidene fluoride (PVDF) resin, polyethylene terephthalate (PET) resin, polyoxymethylene (POM) resin, monomer cast nylon, polybutylene terephthalate (PBT) ) Resin, polystyrene (PS) resin, polyethersulfone (PESF) resin, polyimide (PI) resin, polyamide (PA) resin, polyamideimide (PAI) resin, polyethylene (PE) resin, Urethane (PU) resins, silicone resins, epoxy resins, methacrylic resins, polycarbonate resin is disclosed.

JP-A-10-181302 JP 2006-161114 A

  However, the conventional plastic thrust rolling bearing is excellent in corrosion resistance, but its allowable range in use as a thrust bearing is small and its use is limited. For example, in a high surface pressure environment (for example, an environment exceeding a surface pressure of 20 kPa), the raceway surface may be worn.

  The present invention has been made in view of the above circumstances, and suppresses the wear of the raceway surface even when used in a high surface pressure environment, and has a longer product life than a conventional resin thrust rolling bearing. The purpose is to provide rolling bearings. More specifically, an object of the present invention is to provide a resin-made thrust rolling bearing that has no wear on the raceway surface even under use conditions exceeding a surface pressure of 20 kPa and has a product life that is twice or more that of a conventional product.

  The resin thrust rolling bearing according to the present invention includes a first race ring having a first raceway surface, a second race ring having a second raceway surface, the first raceway surface and the second raceway. A plurality of rolling elements arranged so as to be freely rollable between surfaces, and a cage for holding the rolling elements at equal intervals in the circumferential direction, the first raceway ring and the second raceway ring. Is a molded product of the resin composition, characterized in that the molded product has a tensile elastic modulus of 3800 MPa or more and a bending elastic modulus of 3400 MPa or more.

  The cage is a molded body of a resin composition. The rolling element is made of ceramics.

  The resin composition that forms the first raceway ring and the second raceway ring does not include a fibrous reinforcing material. Further, the resin composition forming the first raceway ring and the second raceway ring is characterized by using an aromatic polyetherketone (PEK) resin as a base resin.

  The resin composition forming the cage is characterized by using a fluororesin as a base resin.

  The molded article has a tensile elastic modulus of 3800 MPa to 4200 MPa and a bending elastic modulus of 3400 MPa to 4000 MPa. Further, the resin composition forming the first raceway and the resin composition forming the second raceway are resin compositions having the same composition.

  In the resin thrust rolling bearing of the present invention, the first bearing ring and the second bearing ring are molded articles of a resin composition, the molded article has a tensile elastic modulus of 3800 MPa or more, and a bending elastic modulus. Since it is 3400 MPa or more, it has excellent rigidity as a race, and even when used in an environment with a high surface pressure (for example, a surface pressure of 40 kPa), wear of the raceway surface does not occur. Thereby, the product life longer than the conventional resin thrust rolling bearing is obtained.

  Since the cage is a molded body of the resin composition, it has excellent corrosion resistance. Further, since the impact is small even when contacting with the raceway surface compared to a metal cage, it is suitable for preventing wear of the raceway surface.

  Since the rolling element is made of ceramics, it has excellent corrosion resistance. Further, since the burden on the raceway surface is smaller than that of a metal rolling element, it is suitable for preventing wear of the raceway surface.

  By not including a fibrous reinforcing material in the resin composition that forms the first and second race rings, the fibrous reinforcing material has fallen off the raceway surface and the raceway surface shape has become rough or has fallen off. It is possible to prevent the raceway surface from being worn by the fibers, and to improve the wear resistance of the raceway surface.

  Since the aromatic PEK-based resin is a base resin, the resin composition forming the first and second race rings is excellent in heat resistance and can be used in a high-temperature atmosphere. Further, since the friction and wear characteristics are excellent, the wear resistance of the raceway surface can be improved.

  Furthermore, since the fluororesin is a base resin, the resin composition forming the cage is excellent in lubricity and does not damage the raceway surface even when it comes into contact with the raceway surface.

  Since the tensile elastic modulus of the molded body of the first and second bearing rings is 3800 MPa to 4200 MPa and the bending elastic modulus is 3400 MPa to 4000 MPa, the rigidity as the bearing ring is excellent, and high surface pressure ( For example, even when used in an environment with a surface pressure of 40 kPa), the wear of the raceway surface does not occur and a product life longer than that of a conventional plastic thrust rolling bearing can be obtained.

  Since the resin composition that forms the first raceway and the resin composition that forms the second raceway are the same composition, parts can be shared.

It is an axial sectional view of a thrust ball bearing according to the present embodiment. It is a photograph which shows the result of an endurance test.

  The resin thrust rolling bearing of the present invention will be described with reference to FIG. FIG. 1 is an axial sectional view of a thrust ball bearing which is an example of the bearing of the present invention. As shown in FIG. 1, a thrust ball bearing 1 includes a pair of raceways 11 and 12 that are axially opposed to each other, balls 13 that are rolling elements, and cages that hold the balls 13 at regular intervals in the circumferential direction. 14. The bearing ring 11 is a first bearing ring, and the bearing ring 12 is a second bearing ring. A plurality of balls 13 are interposed between the raceway surfaces 11a and 12a having a circular arc cross section of the pair of raceways 11 and 12. In the thrust ball bearing 1, the pair of race rings 11, 12 and the ball 13 are in contact with each other, and an axial load can be supported. The rolling elements are not limited to balls, but may be rollers (cylindrical rollers, needle rollers, etc.).

  The race rings 11 and 12 of the present embodiment are molded bodies of a resin composition having a synthetic resin, which will be described later, as a base resin. By making the race rings 11 and 12 made of resin, the raceway surface can be prevented from corroding even when used in corrosive atmospheres such as in water, in chemicals, and in a high humidity environment.

  Furthermore, each of the race rings 11 and 12 has a tensile elastic modulus of 3800 MPa or more and a bending elastic modulus of 3400 MPa or more. That is, both the race rings 11 and 12 have extremely high rigidity. If at least one of the tensile modulus and the flexural modulus is less than the above value, the raceway surface may be worn under a high surface pressure environment (for example, an environment exceeding the surface pressure of 20 kPa). The “tensile modulus” in the present invention is a tensile modulus at a temperature of 25 ° C. measured in accordance with ASTM D638, and the “flexural modulus” is a temperature of 25 measured in accordance with ASTM D790. The flexural modulus at ℃.

  The resin composition forming the races 11 and 12 is not particularly limited as long as it is a resin composition having a tensile elastic modulus of 3800 MPa or more and a bending elastic modulus of 3400 MPa or more. Plastic can be used. As long as the above numerical range is satisfied, even if the resin composition of the first track ring and the resin composition of the second track ring are the same resin composition, the resin composition of the different composition. May be. When the shapes of the first and second race rings are the same, it is preferable to use resin compositions having the same composition because the parts can be shared. The resin composition may be a grade in which a synthetic resin is used as a base resin and an elastomer, an inorganic filler, or the like is appropriately blended to enhance the tensile elastic modulus or bending elastic modulus. However, as described later, it is preferable not to include a fibrous reinforcing material.

  As the synthetic resin used as the base resin, for example, an aromatic PEK resin can be used. The aromatic PEK resin has a continuous use temperature of 250 ° C. and is excellent in heat resistance, and is also excellent in creep resistance and frictional wear characteristics. Examples of the aromatic PEK-based resin include polyether ether ketone (PEEK) resin, polyether ketone (PEK) resin, polyether ketone ether ketone ketone (PEKEKK) resin, and among these, PEEK resin is preferable.

  As long as the resin composition has a tensile elastic modulus and a bending elastic modulus satisfying the above numerical ranges as described above, various fillers may be blended. For example, a solid lubricant such as PTFE resin or graphite can be blended. In the case of blending PTFE resin or graphite, the blending amount of the solid lubricant is preferably 1 to 10% by mass with respect to the entire resin composition. More preferably, it is 2-5 mass%. By setting the blending amount of the solid lubricant within this range, it is possible to maintain high rigidity while improving the lubricity on the raceway surfaces 11a and 12a.

  Moreover, it is preferable that this resin composition does not contain fibrous reinforcing materials such as carbon fibers and glass fibers. If the resin composition includes a fibrous reinforcing material, it is considered that the fibrous reinforcing material appears on the raceway surfaces 11a and 12a and falls off. In this case, the raceway surface may become rough, and the raceway surface may be worn by the dropped fibrous reinforcing material. In order to prevent such an event, it is preferable not to include a fibrous reinforcing material.

  Considering these, as a resin composition for forming the race, for example, an aromatic PEK-based resin having a sufficient tensile elastic modulus and bending elastic modulus is used as a base resin, and solid lubrication such as PTFE resin or graphite is used for this. Particularly preferred are those containing an agent and not containing a fibrous reinforcing material. Furthermore, it is preferable that the molded product of the resin composition has a tensile modulus of 3800 MPa to 4200 MPa and a flexural modulus of 3400 MPa to 4000 MPa.

  The races 11 and 12 are obtained by injection molding using the resin composition as described above. Moreover, you may give the finishing process by machining as needed. The inner diameter Φ of the races 11 and 12 is, for example, 60 to 80 mm, and the outer diameter Φ in that case is, for example, 80 to 100 mm.

  The material of the rolling element 13 is not particularly limited, but ceramics are preferable from the viewpoint of corrosion resistance when considering the use of the thrust ball bearing 1 in a corrosive atmosphere. As ceramics, for example, silicon nitride, alumina or the like can be used. Of these, alumina is preferable from the viewpoint of wear on the synthetic resin raceways 11 and 12.

  The material of the cage 14 is not particularly limited. However, considering the use of the thrust ball bearing 1 in a corrosive atmosphere, the cage 14 is preferably made of resin from the viewpoint of corrosion resistance. For example, the cage 14 can be obtained by molding a resin composition using a fluororesin, an aromatic PEK resin, a PAI resin, a PPS resin, or the like as a base resin. Among these, a fluororesin is preferable from the viewpoint of low friction.

  Examples of the fluororesin include PTFE resin, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and ethylene / tetrafluoroethylene copolymer. These resins can be used alone or as a mixture. Of these, a PTFE resin excellent in heat resistance and friction resistance is preferable.

  Various fillers may be blended in the resin composition forming the cage 14. For example, glass fibers, carbon fibers, aramid fibers, and various mineral fibers (whiskers) may be blended to increase the strength. Furthermore, you may mix | blend an inorganic filler etc.

  The thrust ball bearing 1 according to the present embodiment can be used for a long time even in a corrosive atmosphere such as in water, in a chemical, or in a high humidity environment because the races 11 and 12 are made of resin and have excellent corrosion resistance. . Furthermore, since the races 11 and 12 are highly rigid, they can be used over a long period of time even in a high surface pressure environment. In particular, it is suitable for use under the condition of a surface pressure of 20 kPa or more, which makes it difficult to use a conventional resin thrust bearing. For example, it is suitable for conditions with a surface pressure of 30 kPa or more, and more suitable for conditions with a surface pressure of 40 kPa or more. Therefore, the thrust ball bearing 1 can be widely applied to various devices in which the use conditions as described above are assumed.

Example 1
(1) Thrust ball bearing A thrust ball bearing was manufactured using each of the constituent members shown below. The total thickness of the thrust ball bearing was 9.6 mm. Table 2 shows a list of the compositions and physical properties of the races of each example and comparative example. In each of the examples and comparative examples, the pair of races uses the same resin composition. Moreover, about the PEEK resin used as a base resin in Examples and Comparative Examples, the PEEK resin of the same grade is used for the PEEK resins of Examples 1 to 3, and the PEEK resin of Examples 1 to 3 is used for the PEEK resin of Comparative Example 1. A PEEK resin of a different grade from the resin was used.

(I) Raceway (first raceway and second raceway)
PEEK resin is used as the base resin, and a resin composition ("PEEK1" in Table 2) containing 3% by mass of PTFE resin is injection molded to obtain a molded body having an outer diameter of Φ100 mm, an inner diameter of Φ60 mm, and a thickness of 4.5 mm. Obtained. The obtained molded body was machined to produce a race ring having an outer diameter of 90 mm, an inner diameter of 70 mm, a thickness of 3.2 mm, and a groove depth of 1.2 mm. Two were produced for the first and second races.

(Ii) Cage A PTFE resin was used as a base resin, a resin composition containing 10% by mass of aramid fibers was molded into the cage, and a cage was produced by machining.

(Iii) Rolling elements 29 ¼ inch balls made of alumina ceramics were used.

(2) Evaluation (i) Tensile elastic modulus Using a test piece obtained by injection molding the resin composition used for the production of the race, a tensile test according to ASTM D638 was conducted to determine the tensile elastic modulus. It was measured.

(Ii) Flexural modulus Using a test piece obtained by injection molding the resin composition used for the production of the race, a flexural test according to ASTM D790 was carried out to measure the flexural modulus.

(Iii) Durability test A durability test was performed using the produced thrust ball bearing under the operating conditions shown in Table 1 below. After the start of the test, the test was interrupted every week to check the raceway surface, and it was determined whether or not continuous use (continuation of the test) was possible each time.

Example 2
A thrust ball bearing was produced in the same manner as in Example 1 except that a resin composition consisting of only PEEK resin ("PEEK2" in Table 2) was used in the production of the raceway rings, and each evaluation was performed.

Example 3
Thrust balls in the same manner as in Example 1 except that a PEEK resin was used as a base resin and a resin composition (“PEEK3” in Table 2) containing 3% by mass of graphite powder was used in the production of the bearing ring. A bearing was prepared and evaluated.

Comparative Example 1
Thrust ball bearings were produced in the same manner as in Example 1 except that a resin composition consisting only of PEEK resin ("PEEK4" in Table 2) was used in the production of the bearing rings, and each evaluation was performed.

  Table 2 shows the evaluation results. Moreover, the state of the track surface after the endurance test in Example 1, Example 2, and Comparative Example 1 is shown in FIG.

  As shown in Table 2, each of the race rings of Examples 1 to 3 had a tensile modulus of 3800 MPa or more and a flexural modulus of 3400 MPa or more, whereas the raceway of Comparative Example 1 The ring had a tensile modulus of less than 3800 MPa, although the flexural modulus exceeded 4000 MPa. In the durability test, as shown in FIG. 2, in Example 1 and Example 2, no significant change was observed in the raceway surface even after operation for 1680 hours (10 weeks). Therefore, it is considered that further continuous use is possible. On the other hand, in Comparative Example 1, wear of the raceway surface was observed after 504 hours (3 weeks) of operation. Therefore, it was judged that continuous use was difficult, and the durability test was interrupted at that time.

  As described above, the thrust ball bearing of each example is a conventional thrust ball bearing in which the axial load is 40 kPa or more because the race is made of a synthetic resin having a tensile elastic modulus of 3800 MPa or more and a bending elastic modulus of 3400 MPa or more. However, it was confirmed that it can be used even under a high load condition that is twice or more the load that can be used. In addition, the thrust ball bearing of Example 2 was the best in the condition of the raceway surface after 1680 hours of operation.

  The resin thrust rolling bearing of the present invention is excellent in corrosion resistance and suppresses the wear of the raceway surface even when used in a high surface pressure environment, and has a longer product life than conventional resin thrust rolling bearings. Therefore, it can be widely applied as a thrust bearing of various devices having a corrosion-resistant atmosphere.

DESCRIPTION OF SYMBOLS 1 Thrust ball bearing 11 Race ring 12 Race ring 13 Ball 14 Cage

Claims (8)

A first raceway having a first raceway surface, a second raceway having a second raceway surface, and a rollable arrangement between the first raceway surface and the second raceway surface. A thrust bearing comprising a plurality of the rolling elements and a cage that holds the rolling elements at equal intervals over the circumferential direction,
The first raceway ring and the second raceway ring are molded bodies of a resin composition,
A resin thrust rolling bearing, wherein the molded article has a tensile elastic modulus of 3800 MPa or more and a bending elastic modulus of 3400 MPa or more.   The resin-made thrust rolling bearing according to claim 1, wherein the cage is a molded body of a resin composition.   3. The resin-made thrust rolling bearing according to claim 1, wherein the rolling element is made of ceramics.   4. The resin product according to claim 1, wherein the resin composition forming the first raceway ring and the second raceway ring does not include a fibrous reinforcing material. 5. Thrust rolling bearing.   The resin composition that forms the first raceway ring and the second raceway ring includes an aromatic polyetherketone resin as a base resin. The resin-made thrust rolling bearing described in the item.   The resin thrust rolling bearing according to claim 2, wherein the resin composition forming the cage includes a fluororesin as a base resin.   7. The resin thrust rolling bearing according to claim 1, wherein the molded article has a tensile elastic modulus of 3800 MPa to 4200 MPa and a bending elastic modulus of 3400 MPa to 4000 MPa. .   The resin composition forming the first raceway ring and the resin composition forming the second raceway ring are resin compositions having the same composition. A resin thrust rolling bearing according to any one of the preceding claims.