JP2006200733A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing capable of restraining generation of a large quantity of abrasion powder when an axial load acts on a resin inner race and a resin outer race and large reduction in the service life of a rolling body by biting-in of the abrasion powder generated in large quantities. <P>SOLUTION: The central part depth of rolling body track grooves 4 and 5 formed on an outer peripheral surface of the resin inner race 2 and an inner peripheral surface of the resin outer race 3, is set to 18% to 45% to a diameter of the rolling body 6, and a contact point of the rolling body track grooves 4 and 5 and the rolling body 5, is made to hardly run on a shoulder part of the rolling body track grooves 4 and 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing used in a wafer cleaning device or a food machine.

In a wafer cleaning apparatus for cleaning a semiconductor wafer, a rolling bearing such as a ball bearing is used as a bearing for supporting a rotating shaft of a wafer transfer mechanism. It is often formed from a metal such as. For this reason, when cleaning fluid such as water scatters and adheres to the rolling bearing, lubricant contaminants such as iron oxide are generated in the rolling element raceway grooves of the inner ring and outer ring, and lubricant such as grease is caused by this lubricant contaminant. Contamination makes it easy for the rolling elements to wear early. Therefore, in order to suppress the occurrence of lubricant contaminants such as iron oxide in the rolling element raceway grooves of the inner ring and the outer ring, those in which the inner ring and the outer ring are formed from a synthetic resin such as polyacetal are known (patent document). 1 and 2).
JP-A-5-202943 JP-A-9-303403

  However, since the elastic modulus of the inner ring and the outer ring is extremely small compared with the case where the inner ring and the outer ring are made of metal such as steel, the ones shown in the above-mentioned documents 1 and 2 have a load in the axial direction (hereinafter referred to as “axial load”). ”) Acts on the inner ring and the outer ring via the rolling elements, the rolling element raceway grooves formed on the outer circumferential surface of the inner ring and the inner circumferential surface of the outer ring easily deform, and the rolling element is deformed by the deformation of the rolling element raceway grooves. The contact point between the rolling element raceway groove and the rolling element raceway groove climbs onto the shoulder of the rolling element raceway groove, and as a result, a large amount of wear powder is generated due to the concentration of stress generated on the shoulder of the rolling element raceway groove and contaminates the surrounding environment. In addition, there is a possibility that the life of the rolling element may be significantly reduced by the wear powder.

  The present invention has been made paying attention to such problems, and a large amount of wear powder is generated when the contact point between the rolling element and the rolling element raceway groove rides on the shoulder of the rolling element raceway groove. Another object of the present invention is to provide a rolling bearing capable of suppressing the life of a rolling element from being significantly reduced due to a large amount of wear powder generated.

  In order to achieve the above object, an invention according to claim 1 includes an inner ring made of a resin composition, a resin outer ring provided on the outer periphery of the inner ring, and a rolling element track formed on the outer peripheral surface of the inner ring. In a rolling bearing comprising a groove and a number of spherical rolling elements that roll a rolling element raceway groove formed on the inner peripheral surface of the outer ring as the inner ring or the outer ring rotates, the center of the rolling element raceway groove The depth of the part is 18% or more and 45% or less with respect to the diameter of the rolling element.

According to a second aspect of the present invention, in the rolling bearing according to the first aspect, a cross-sectional shape of the rolling element raceway groove along the axial direction of the inner ring and the outer ring is 50.5% to 51.51 with respect to the diameter of the rolling element. It is characterized by a Gothic arch shape or arc shape with a curvature of 9%.
According to a third aspect of the present invention, in the rolling bearing according to the first or second aspect, the rolling element is rollable in a circumferential direction of the inner ring and the outer ring by a cage provided between the inner ring and the outer ring. It is characterized by being held in.

According to a fourth aspect of the present invention, in the rolling bearing according to the third aspect, the depth of the central portion of the rolling element raceway groove is 18% or more and 28% or less with respect to the diameter of the rolling element.
According to a fifth aspect of the present invention, in the rolling bearing according to the fourth aspect, the rolling element raceway groove has a cross-sectional shape along the axial direction of the inner ring and the outer ring of 52.2% to 55% with respect to the diameter of the rolling element. It is formed in a Gothic arch shape or an arc shape with a curvature of.

According to a sixth aspect of the present invention, in the rolling bearing according to any one of the first to fifth aspects, at least one of the multiple rolling elements is formed of a resin composition.
The invention according to claim 7 is the rolling bearing according to any one of claims 1 to 5, wherein at least one of the rolling elements is made of polyethylene resin, polypropylene resin, polyacetal resin, and melt-resistant corrosion resistance. It is formed from the resin composition which has any one of resin and a fluorine-containing resin as a main component.

The invention according to claim 8 is the rolling bearing according to claim 1 or 2, wherein the multiple rolling elements include a first rolling element made of a non-resin composition and a second rolling element made of a resin composition. One rolling element and a second rolling element are alternately arranged between the inner ring and the outer ring.
The invention according to claim 9 is the rolling bearing according to claim 8, wherein the ratio of the diameter of the second rolling element to the diameter of the first rolling element is 0.987 or more and 1.013 or less. .

  In the rolling bearing according to the invention of claim 8, the first rolling element made of the non-resin composition and the second rolling element made of the resin composition are alternately arranged between the inner ring and the outer ring, so that the speed is particularly high. In the case of rotation, even when friction or collision between the rolling elements occurs, the first rolling element and the second rolling element come into contact with each other, and wear of the rolling elements is effectively reduced, resulting in a long life. That is, in the case of a rolling element of the total rolling element type, when the second rolling element made of the resin composition is not provided, the first rolling elements made of the non-resin composition come into contact with each other, particularly during high-speed rotation, and wear easily occurs. . As a result, the surface roughness of the rolling element increases, and as a result, the inner ring and the outer ring made of resin are abnormally worn or the diameter of the rolling element becomes abnormally small. The rolling bearing may reach the end of its life in a relatively short time. However, the rolling bearing according to the invention of claim 8 can effectively suppress wear due to contact or collision between the rolling elements. Can increase the durability.

  In the rolling bearing according to the invention of claim 9, the ratio of the diameter of the second rolling element made of the resin composition and the diameter of the first rolling element made of the non-resin composition is 0.987 or more and 1.013 or less. And the mating surface on which the second rolling element made of the resin composition slides at the contact surface with the sliding surface of the cage and the inner ring and the outer ring (the inner surface of the pocket if the cage, the raceway groove if the inner ring and the outer ring) As a result of an appropriate contact force with the surface), a resin material excellent in self-lubricating property is transferred from the second rolling element to the mating surface, and the rolling material and the cage or the surface of the raceway groove by the resin material transferred to the mating surface Thus, the frictional force generated at the contact portion is reduced, so that the rolling bearing and the inner and outer rings can be prevented from being worn and the rolling bearing can be operated over a long period of time. In addition, when the ratio of the diameter of a 2nd rolling element and the diameter of a 1st rolling element is less than 0.987, the contact of the said opposing surface and a 2nd rolling element becomes inadequate, As a result, a 2nd rolling element Since the amount of resin material transferred to the mating surface is reduced, the bearing life may be extremely shortened. When the ratio of the diameter of the second rolling element to the diameter of the first rolling element exceeds 1.013, the contact force of the second rolling element with respect to the mating surface becomes extremely large, and as a result, the second rolling element The bearing life may be extremely shortened due to abnormal wear on the moving body or damage to the second rolling element.

  A tenth aspect of the present invention is the rolling bearing according to any one of the first to fifth aspects, wherein all of the plurality of rolling elements are formed of a resin composition. Since the resin composition has excellent self-lubricating properties, the wear of the rolling elements is more effectively reduced under dry (no lubrication) conditions, and the life of the rolling bearing is further extended. be able to.

  The invention according to claim 11 is the rolling bearing according to any one of claims 1 to 5, wherein all of the numerous rolling elements are polyethylene resin, polypropylene resin, polyacetal resin, melt-resistant corrosion-resistant resin, and fluorine-containing resin. It is characterized by being formed from the resin composition which has any one of these as a main component, By setting it as such a structure, a polyethylene resin, a polypropylene resin, a polyacetal resin, and melt molding are possible Since the resin composition containing either one of the corrosion-resistant resin and the fluorine-containing resin as a main component is particularly excellent in self-lubricating property among the resin compositions, the wear of the rolling element is particularly improved under dry (non-lubricating) conditions. It can be effectively reduced and the life of the rolling bearing can be further extended.

  In the rolling bearing according to the present invention, even if the rolling element raceway groove is deformed by an axial load acting on the inner ring or the outer ring, the contact point between the rolling element and the rolling element raceway groove is unlikely to ride on the shoulder of the rolling element raceway groove. Become. Therefore, a large amount of wear powder is generated when the contact point between the rolling element and the rolling element raceway groove rides on the shoulder of the rolling element raceway groove. It can suppress that it falls significantly.

Hereinafter, the rolling bearing according to the present invention will be described with reference to Table 1 and FIGS.
Table 1 shows Examples 1 to 12 and Comparative Examples 1 to 4 of the rolling bearing according to the present invention.

  In Table 1, Examples 1 to 4 show examples of the rolling bearing with retainer 1A shown in FIG. 1, and Examples 5 to 12 show examples of the rolling bearing without retainer 1B shown in FIG. Comparative Example 1 and Comparative Example 2 show a comparative example of a rolling bearing with a retainer 1A shown in FIG. 1, and Comparative Examples 3 and 4 show a comparative example of a rolling bearing without a retainer 1B shown in FIG. Yes.

  A rolling bearing with a cage 1 </ b> A shown in FIG. 1 includes an inner ring 2, and an outer ring 3 is provided on the outer periphery of the inner ring 2. Further, the rolling bearing with a cage 1A includes a rolling element raceway groove 4 formed on the outer peripheral surface of the inner ring 2 and a rolling element raceway groove 5 formed on the inner peripheral surface of the outer ring 3 as the inner ring 2 or the outer ring 3 rotates. A cage 7 is provided between the inner ring 2 and the outer ring 3 to hold the rolling element 6 so that it can roll in the circumferential direction of the inner ring 2 and the outer ring 3. Is provided.

The rolling bearing without retainer 1B shown in FIG. 2 has substantially the same configuration as the rolling bearing with a cage 1A, but retains the rolling element 6 so that it can roll in the circumferential direction of the inner ring 2 and the outer ring 3. The point which is not provided is a point different from the rolling bearing 1A with a cage.
As shown in Table 1, the inner rings and outer rings of Examples 1 to 12 and Comparative Examples 1 to 4 are, for example, PE (polyethylene), PEEK (polyether ether ketone), PCTFE (polychlorotrifluoroethylene), PVdF (polyethylene). The resin composition is mainly composed of any one of vinylidene fluoride), PTFE (tetrafluoroethylene), PP (polypropylene), and POM (polyacetal).

  In Examples 1 to 12 and Comparative Examples 1 to 4 shown in Table 1, trade name: Polypenco U-PE (manufactured by Nippon Polypenco) as PE, and trade name: Duracon M140 (manufactured by Polyplastics) as POM. , PP as trade name: Sun Allomer PB370A (manufactured by Sun Allomer), PVDF as trade name: Kureha KF Polymer T- # 850 (manufactured by Kureha Chemical Co., Ltd.), and PPS as trade name: Ryton R-6 (Philippe Spectroy) Am)) as PEEK, trade name: Victorex PEEK150G (manufactured by Victorex), PTFE as trade name: Teflon (registered trademark) PTFE (manufactured by DuPont), and PCTFE as trade name: NEOFLON PCTFE M-300PL Trade name: Kureka chop M (made by Daikin Industries) as carbon fiber 102S (manufactured by Kureha Chemical Industry Co., Ltd., fiber diameter: 14.5 μm, length: 0.2 mm) as potassium titanate whisker, product name: Tismo D-101 (manufactured by Otsuka Chemical Co., Ltd., fiber diameter: 0.3-0. 6 μm, length 10-20 μm) was used.

Examples 1 to 9 and Comparative Examples 1 to 4 in Table 1 show that all the rolling elements are formed of any one of corrosion-resistant materials among borosilicate glass, SUS440C, silicon nitride, and SUS304. In Examples 10 to 12, one of the rolling elements is formed of a resin material such as PTFE or PP.
In Examples 1 to 4 (rolling bearings with a cage) in Table 1, the depth d (see FIGS. 3 and 4) of the center portion of the rolling element raceway groove is 18% to 28% with respect to the diameter of the rolling element. However, in Examples 5 to 12 (roller bearings without cage) in Table 1, the depth d of the central portion of the rolling element raceway groove is 18% to the diameter of the rolling element. The value within the range of 45% is shown. On the other hand, Comparative Examples 1 to 4 in Table 1 indicate that the depth d of the central portion of the rolling element raceway groove is 17%, 29%, 17%, and 46% with respect to the diameter of the rolling element.

  Further, in Examples 1 to 4 (rolling bearings with a cage) in Table 1, the curvature R (see FIGS. 3 and 4) of the rolling element raceway groove is in the range of 52.2% to 55% with respect to the diameter of the rolling element. In Examples 5 to 12 (roller bearings without cage) in Table 1, the curvature R of the rolling element raceway groove is within the range of 50.5% to 51.9% with respect to the diameter of the rolling element. Is shown. On the other hand, Comparative Examples 1 to 4 in Table 1 show that the curvature R of the rolling element raceway groove is 52%, 56%, 50.2%, and 52% with respect to the diameter of the rolling element.

The rolling element raceway grooves 4 and 5 shown in FIGS. 3 and 4 are illustrated in which the cross sections along the axial direction of the inner ring 2 and the outer ring 3 are formed in a Gothic arch shape. A rolling element raceway groove in which a cross section along the axial direction is formed in an arc shape may be used.
FIG. 5 is a diagram showing a schematic configuration of a test apparatus used for testing the durability of a rolling bearing, in which 11 is a motor, 12 is a coupling, 13 is a spindle, 14 is a shaft, 15 is a support bearing, Reference numeral 16 is a wire, 17 is a pulley, 18 is a weight, 19 is a spray gun, 20 is a vibration meter, 21 is a water tank, and 22 is a test bearing.

FIG. 6 shows the durability of a rolling bearing with a crown-shaped resin cage using the test apparatus shown in FIG. 5 in water and at a rotational speed of 300 min ⁻¹ , an axial load of 80 N, a radial load of 10 N, and a temperature of room temperature. It is a figure which shows the result tested on test conditions. In this figure, the vertical axis shows the durability of the rolling bearing with cage (relative value when the test data of Comparative Example 1 is 1), and the horizontal axis is the depth of the central part of the rolling element raceway groove with respect to the rolling element diameter. d. Curve 61 in the figure shows the relationship between the durability of the rolling bearing with cage and the depth of the center of the rolling element raceway groove with respect to the diameter of the rolling element when the inner ring and outer ring are made of PEEK, and curve 62 shows the inner ring and outer ring. 7 shows the relationship between the durability of the rolling bearing with a cage and the depth of the central portion of the rolling element raceway groove with respect to the diameter of the rolling element when the bearing is made of PE. A curve 63 shows the relationship between the durability of the rolling bearing with a cage and the depth of the center of the rolling element raceway groove with respect to the diameter of the rolling element when the inner ring and the outer ring are made of PCTFE.

  As is apparent from the relationship between the durability of the rolling bearing with cage shown in FIG. 6 and the central depth of the rolling element raceway groove with respect to the rolling element diameter, the central depth of the rolling element raceway groove with respect to the rolling element diameter is 18% to It can be seen that the durability of the rolling bearing with a cage is drastically reduced when it is out of the 28% range. This is because when the depth of the central portion of the rolling element raceway groove with respect to the rolling element diameter is less than 18%, the elastic modulus of the resin composition constituting the raceway is very small compared to that of the metal, so that it acts on the raceway. The rolling element raceway groove is easily deformed by the axial load, and the contact point between the rolling element and the rolling element raceway groove rises on the shoulder of the rolling element raceway groove as a result of the deformation of the rolling element raceway groove. This is because a large amount of wear powder is generated due to the concentration of stress generated in the shoulder portion of the groove and pollutes the surrounding environment, or the life of the rolling element is significantly reduced due to the biting of the wear powder. Further, if the central depth of the rolling element raceway groove with respect to the rolling element diameter exceeds 28%, the shoulder of the rolling element raceway groove and the cage are likely to come into contact with each other. Abnormal wear occurs at the contact part between the shoulder of the rolling element rolling groove and the cage and the contact part between the rolling element and the bearing ring, so that a large amount of wear powder is generated and the surrounding environment is contaminated. This is because the life of the rolling element is significantly reduced by biting.

  Therefore, as in Examples 1 to 4 shown in Table 1, by setting the central depth of the rolling element raceway groove with respect to the rolling element diameter within the range of 18% to 28%, the rolling element raceway groove with respect to the rolling element diameter The durability of the rolling bearing with a cage can be enhanced as compared with those in which the center depth of the roller is out of the range of 18% to 28% (Comparative Example 1 and Comparative Example 2). Further, as in Examples 2 and 3 shown in Table 1, the durability of the rolling bearing with a cage is achieved by setting the central depth of the rolling element raceway groove to the rolling element diameter within a range of 20% to 25%. Can be further enhanced.

  It can be seen that the rolling bearings with cages of Examples 1 to 4 have a durability of the rolling bearing of about 3 to 12 times that of Comparative Example 1. This is because, as in Comparative Example 1, when the curvature R of the rolling element raceway groove is less than 52.2% with respect to the diameter of the rolling element, the elastic modulus of the resin composition constituting the raceway is compared with that of metal. Therefore, the rolling element raceway groove is easily deformed by the axial load acting on the raceway, and the contact point between the rolling element and the rolling element raceway groove is the shoulder of the rolling element raceway groove due to the deformation of the rolling element raceway groove. As a result, a large amount of wear powder is generated due to the stress concentration generated on the shoulder of the rolling element raceway groove, contaminating the surrounding environment, and the life of the rolling element is significantly reduced due to the biting of the wear powder. This is because Moreover, when the curvature R of a rolling element raceway groove exceeds 55% with respect to the diameter of a rolling element like the comparative example 2, it turns out that durability of a rolling bearing will be 1 or less.

Therefore, when the bearing ring of the rolling bearing with cage is made of resin and the depth of the central portion of the rolling element raceway groove with respect to the diameter of the rolling element is within a range of 18% to 28%, preferably 20% to 25%. As in Examples 1 to 4, it is preferable that the curvature R of the rolling element raceway groove is in the range of 52.2% to 55% with respect to the diameter of the rolling element.
FIG. 7 shows the durability of a rolling bearing without a cage using the test apparatus shown in FIG. 5 under the test conditions in water, bearing rotational speed: 300 min ⁻¹ , axial load: 80 N, radial load: 10 N, temperature: room temperature. It is a figure which shows the result of having tested. The rolling elements at this time are all silicon nitride.

  In the same figure, the vertical axis shows the durability of the rolling bearing without a cage (relative value when the test data of Comparative Example 3 is 1), and the horizontal axis is the depth of the central part of the rolling element raceway groove with respect to the rolling element diameter. d. Curve 71 in the figure shows the relationship between the durability of the rolling bearing without a cage when the inner ring and the outer ring are made of POM and the central depth of the rolling element raceway groove with respect to the diameter of the rolling element, and curve 72 shows the inner ring and the outer ring. 7 shows the relationship between the durability of a rolling bearing without a cage when made of PP and the central depth of the rolling element raceway groove with respect to the rolling element diameter. Curve 73 shows the relationship between the durability of the rolling bearing without a cage when the inner ring and the outer ring are made of PVDF and the central depth of the rolling element raceway groove with respect to the rolling element diameter.

As is apparent from the relationship between the durability of the rolling bearing without a retainer shown in FIG. 7 and the central depth of the rolling element raceway groove with respect to the rolling element diameter, the central depth of the rolling element raceway groove with respect to the rolling element diameter is 18% to It can be seen that when it is out of the range of 45%, the durability of the rolling bearing without a cage is drastically lowered.
Accordingly, as in Examples 5 to 12 shown in Table 1, by setting the central depth of the rolling element raceway groove to the rolling element diameter within a range of 18% to 45%, the rolling element raceway groove to the rolling element diameter is set. The durability of the rolling bearing without a cage can be improved as compared with those in which the depth of the central portion is out of the range of 18% to 45% (Comparative Example 3 and Comparative Example 4). Moreover, like Example 6-8 shown in Table 1, and 10-12, the center part depth of the rolling-element track groove with respect to a rolling-element diameter shall be in the range of 20%-40%, and rolling with a holder | retainer is carried out. The durability of the bearing can be further increased.

  It can be seen that the cageless rolling bearings of Examples 5 to 12 have a durability of the rolling bearing of about 4 to 20 times that of Comparative Example 3. This is because, as in Comparative Example 3, when the curvature R of the rolling element raceway groove is less than 50.5% with respect to the diameter of the rolling element, the elastic modulus of the resin composition constituting the raceway is compared with that of metal. Therefore, the rolling element raceway groove is easily deformed by the axial load acting on the raceway, and the contact point between the rolling element and the rolling element raceway groove is the shoulder of the rolling element raceway groove due to the deformation of the rolling element raceway groove. As a result, a large amount of wear powder is generated due to the stress concentration generated on the shoulder of the rolling element raceway groove, contaminating the surrounding environment, and the life of the rolling element is significantly reduced due to the biting of the wear powder. This is because Further, as in Comparative Example 4, it can be seen that when the curvature R of the rolling element raceway groove exceeds 51.9% with respect to the diameter of the rolling element, the durability of the rolling bearing is drastically reduced.

Therefore, when the bearing ring of the rolling bearing without a cage is made of resin and the depth of the central portion of the rolling element raceway groove with respect to the diameter of the rolling element is in the range of 18% to 45%, preferably 20% to 40%. As in Examples 5 to 12, it is preferable that the curvature R of the rolling element raceway groove is in the range of 50.5% to 51.9% with respect to the diameter of the rolling element.
The present invention is not limited to Examples 1 to 12 shown in Table 1. For example, as a resin material suitable as a bearing ring material of a rolling bearing, polyarylene sulfide resin represented by polyethylene (PE) resin, polypropylene (PP) resin, polyacetal (POM) resin, polyphenylene sulfide (PPS) resin, poly Examples include ether ether ketone (PEEK), polyether nitrile (PEN), aromatic polyimide (PI), thermoplastic polyimide (TPI), polyamideimide (PAI), aromatic polyester (LCP), and various fluorine-containing resins.

  When a fluorine-containing resin is used as the bearing ring material, it is not particularly limited. For example, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE), polyvinylidene fluoride ( PVDF), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE) and the like can be used.

When the bearing ring of the rolling bearing is formed from a resin composition, the resin is used for the purpose of improving the lubrication characteristics of the bearing ring or reducing the frictional force generated at the contact point between the rolling element raceway groove and the rolling element. Composition includes tetrafluoroethylene resin powder (PTFE), graphite, hexagonal boron nitride (hBN), fluorine mica, melamine cyanurate (MCA), amino acid compound having a layered crystal structure (N-lauro / L-lysine) An appropriate amount of solid lubricant such as fluorinated graphite, fluorinated pitch, and molybdenum disulfide (MoS ₂ ) may be added. In this case, when the amount of the solid lubricant added to the resin composition exceeds 30% by mass, not only the improvement of the different lubricating action cannot be expected, but also the mechanical strength of the resin composition itself decreases, thereby causing the resin composition There is a case where wear of the bearing ring and the cage is increased, and the life is shortened. Therefore, when a solid lubricant is added to the resin composition constituting the bearing ring, the amount of the solid lubricant added is preferably 30% by mass or less.

  In addition, if the average particle size of the solid lubricant added to the resin composition is less than 0.1 μm, aggregation occurs when mixed with a melt-moldable fluororesin as a base material, and dispersion or non-uniformity of the particles occurs. It may become uniform. On the other hand, if the average particle diameter of the solid lubricant exceeds 60 μm, the smoothness of the surface of the resin composition, which is a molded body, may be reduced, the strength may be reduced, and the life of the rolling bearing may be shortened. Therefore, when a solid lubricant is added to the resin composition constituting the race, the average particle size of the solid lubricant is preferably 0.1 μm or more and 60 μm or less.

  When the bearing ring of the rolling bearing is made of resin, a fibrous filler may be added to the bearing ring material in order to improve the mechanical strength, heat resistance, dimensional stability and the like of the bearing ring. The fibrous filler to be blended in the raceway material is not particularly limited, but aluminum borate whisker, potassium titanate whisker, carbon whisker, aramid fiber, aromatic polyimide fiber, liquid crystal polyester fiber, graphite whisker, glass fiber, Carbon fiber, boron fiber, silicon carbide whisker, silicon nitride whisker, alumina whisker, aluminum nitride whisker, wollastonite, or the like can be used.

  In this case, if the aspect ratio of the fibrous filler is less than 3, the reinforcing effect of the resin composition is not sufficiently exhibited. If the aspect ratio exceeds 200, uniform dispersion during mixing becomes extremely difficult. The aspect ratio is preferably 3 or more and 200 or less. The fiber diameter of the fibrous filler is not particularly limited, but the average fiber diameter is preferably 0.2 μm or more and 30 μm or less, and preferably 0.3 μm or more and 5 μm or less.

When the blending amount of the fibrous filler in the resin composition exceeds 30% by mass, not only a further improvement in mechanical strength can be expected, but also the fluidity when melt-molding the resin composition is significantly reduced. . In addition, from the viewpoint of fluidity during melt molding and the mechanical strength of the resin composition, even if each content of the solid lubricant and the fibrous filler in the resin composition is 30% by mass or less, When the total content exceeds 50% by mass, the fluidity when the resin composition is melt-molded and the mechanical strength of the resin composition may be significantly reduced. Therefore, the blending amount of the fibrous filler in the resin composition is not particularly limited, but is preferably 30% by mass or less.
The fibrous filler contained in the resin composition is a silane or titanate for the purpose of improving adhesion with a meltable fluorine-containing resin that is a base material, or uniformly dispersing in the base material. The surface treatment may be performed with a system coupling agent, or the surface treatment may be performed according to other purposes.

In Example 1 of Table 1, the case where borosilicate glass is used as the rolling element material is exemplified, but glass other than borosilicate glass (for example, soda lime glass, Pyrex (registered trademark) glass) is used as the rolling element material. Also good.
In Example 2 of Table 1, although the case where SUS440C was used as a rolling element material was illustrated, you may use stainless steel type metal materials (for example, SUS304, SUS630) other than SUS440C as a rolling element material.

In Example 3 of Table 1, the case where silicon nitride (Si ₃ N ₄ ) was used as the rolling element material was exemplified, but ceramic materials other than silicon nitride (for example, silicon carbide (SiC), sialon (Sialon), part) Stabilized zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), etc.) may be used as the rolling element material.
In each Example of Table 1, although what formed the rolling element from the single material was illustrated, you may combine the multiple types of material mentioned above.

Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 8 is a sectional view along the radial direction of the rolling bearing according to the second embodiment of the present invention. As shown in FIG. 8, the rolling bearing according to the second embodiment includes an inner ring 2 and an outer ring 3. I have. The inner ring 2 and the outer ring 3 are formed of a material mainly composed of a resin such as PE, PP, POM, PPS, and the like. The rolling element raceway grooves 5 are formed on the circumferential surface.

Between the rolling element raceway grooves 4 and the rolling element raceway grooves 5, a plurality of (for example, six) first rolling elements 6 </ b> A made of a material other than resin (for example, glass, metal, ceramics, etc.) and a resin composition are used. A plurality of (for example, six) second rolling elements 6B are alternately arranged. These rolling elements 6A, 6B is formed in a spherical shape, diameter _{D N} of the first rolling element 6A, when the diameter of the second rolling element 6B and _{D P,} the ratio between _{D P} and _{D N} is, D _P / D _N = 0.987 to 1.013.
Examples of rolling bearings according to the second embodiment are shown in Table 2 together with comparative examples.

  In Table 2, Examples 13, 14, 16, 17, 19 and 20 show those using borosilicate glass as the rolling element material of the first rolling element 6A, and Examples 15 and 18 are examples of the first rolling element 6A. A material using SUS304 as a rolling element material is shown. In Examples 13, 16, 18 and 19, polyethylene (PE) resin is used as the rolling element material of the second rolling element 6B. In Examples 14 and 20, polypropylene (PP) resin is used as the rolling element material of the second rolling element 6B. Examples 15 and 17 show examples in which tetrafluoroethylene (PTFE) is used as the rolling element material of the second rolling element 6B.

  In Examples 13 to 20 and Comparative Examples 5 and 6, in addition to the materials used in Examples 1 to 12 and Comparative Examples 1 to 4, as a special PE, Lübmer L4000 (trade name) manufactured by Mitsui Chemicals, Inc. It was used. In addition, Prenact KR TTS (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd. was used as the titanate coupling agent, and KBM3103 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silane coupling agent.

The present inventor manufactured a rolling bearing (model number 6001, inner diameter: 12 mm, outer diameter: 28 mm, width: 8 mm) having the specifications shown in Table 2 and evaluated the bearing durability as follows. The test was performed in water. That is, the bearing generated by rotating the inner ring of the bearing at a rotational speed of 1000 min ⁻¹ , an axial load of 80 N, and a temperature of room temperature using a bearing rotation tester manufactured by NSK Ltd. shown in FIG. Was measured with a vibrometer 20. And the time when the measured value rose to 5 times the initial value was determined as the life of the rolling bearing, and the durability of each bearing was evaluated with the durability of Comparative Example 5 as 1. The evaluation results are also shown in Table 2.

  When Examples 13 to 20 and Comparative Example 5 are compared, it can be seen that Examples 13 to 20 have a bearing durability about 4 to 17 times higher than that of Comparative Example 5. This is because, as in Comparative Example 5 and Comparative Example 6, when there is no second rolling element made of a resin composition, the rolling elements come into contact with each other and wear tends to occur. As a result, the rolling bearing is relatively While reaching the life in a short time, as in Examples 13 to 20, the first rolling element made of the non-resin composition and the second rolling element made of the resin composition are alternately arranged between the inner ring and the outer ring. It is considered that the arrangement causes contact between the first rolling element and the second rolling element even when friction or collision between the rolling elements occurs, and wear due to contact or collision between the rolling elements is suppressed.

Accordingly, by alternately arranging the first rolling element made of the non-resin composition and the second rolling element made of the resin composition between the inner ring and the outer ring, wear due to contact or collision between the rolling elements is effective. Therefore, the durability of the rolling bearing can be enhanced.
Then, the present inventor has produced a rolling bearing A~C shown in Table 3, the ratio of the diameter D _P and the diameter D _N of the first rolling bodies of the second rolling element in the bearings D _{P /} D _N = The durability of the rolling bearing when changed in the range of 0.975 to 1.02 was evaluated. The evaluation results are shown in FIG.

As shown in FIG. 9, when D _P / _DN is in the range of 0.987 to 1.013, it can be seen that the durability of the rolling bearing shows a high value of 7 or more. This is because the second rolling element made of the resin composition slides on the sliding surface with the cage and the contact point with the inner ring and the outer ring (the inner surface of the pocket if the cage, the track if the inner ring and the outer ring). As a result of an appropriate contact force with the groove surface), a resin material excellent in self-lubricating property is transferred from the second rolling element to the mating surface, and the rolling element and the cage or raceway groove by the resin material transferred to the mating surface. It is considered that the frictional force generated at the contact portion with the surface is reduced.

On the other _hand, when the D P / _{D N} is out of the range of 0.987 to 1.013, the durability of the rolling bearing is understood to be rapidly decreased. This is because when D _P / _DN is less than 0.987, the contact between the mating surface and the second rolling element becomes insufficient, and as a result, the resin material that is transferred from the second rolling element to the mating surface is transferred. It is considered that because the wear amount is small, and the contact force of the second rolling member with respect to the mating surface when the D _{P /} D _N exceeds 1.013 is extremely large, as a result, abnormal second rolling element It is considered that wear occurs or the second rolling element is damaged.

Therefore, the ratio between the diameter D _N of the diameter D _P and the first rolling member of the second rolling element by a 0.987 or 1.013 or less, the contact portion between the rolling elements and the cage or raceway groove surface Since the generated frictional force is reduced, the durability of the rolling bearing can be further increased.
Next, Table 21 shows Examples 21 to 30 of the present invention together with Comparative Examples 7 to 9.

  In Table 4, Examples 21-30 show what formed the rolling element of the rolling bearing from which a bearing ring consists of a resin composition from resin materials, such as PTFE. Comparative Examples 7 and 9 show rolling elements of rolling bearings whose bearing rings are made of a resin composition made of borosilicate glass, and Comparative Example 8 shows rolling elements of rolling bearings whose bearing rings are made of a resin composition. The one made of SUS304 is shown. In Table 4, a crown type fluorine resin cage was used as the cage.

Rolling bearings (model No. 6001, inner diameter: 12 mm, outer diameter: 28 mm, width: 8 mm) as shown in Examples 21 to 30 and Comparative Examples 7 to 9 in Table 4 were made on trial, and these rotation tests (test conditions were inner ring) Under a rotating and dry (non-circulating) environment, a rotational speed: 600 min ⁻¹ , an axial load: 80 N, and a temperature: normal temperature were performed using a bearing rotation tester manufactured by Nippon Seiko Co., Ltd. shown in FIG. And the time when the vibration value at the time of the rotation test increased to 5 times the initial value was determined as the life of the rolling bearing, and the durability of each prototype rolling bearing was evaluated. The results are also shown in Table 4.

  When what is shown in Examples 21 to 30 and that shown in Comparative Example 7 are compared, those shown in Examples 21 to 30 are compared with those shown in Comparative Example 7 in terms of durability evaluation values. It can be seen that it is about 3 to 16 times higher. This is because the rolling element is formed from borosilicate glass in the comparative example 7, whereas the rolling elements are formed from a resin composition having excellent self-lubricating properties in the examples 21 to 30. It is because it has been.

  Therefore, since all of the rolling elements of the rolling bearing in which the race ring is made of the resin composition are formed from the resin composition, the resin composition has excellent self-lubricating properties, and therefore the rolling element under dry (non-lubricated) conditions. Wear is more effectively reduced, and the life of the rolling bearing can be further extended. In particular, a resin composition mainly comprising any one of a polyethylene resin, a polypropylene resin, a polyacetal resin, a melt-resistant corrosion-resistant resin, and a fluorine-containing resin is particularly excellent in self-lubricating properties among resin compositions. In particular, the wear of the rolling elements is more effectively reduced under dry (non-lubricated) conditions, and the life of the rolling bearing can be further extended.

It is an axial sectional view of a rolling bearing with a cage. It is an axial sectional view of a rolling bearing without a cage. It is a fragmentary sectional view of the inner ring | wheel shown in FIG.1 and FIG.2. It is a fragmentary sectional view of the outer ring | wheel shown in FIG.1 and FIG.2. It is a schematic block diagram of the testing apparatus used when testing the durability of a rolling bearing. It is a figure which shows the relationship between durability of a rolling bearing with a cage | basket, and the center part depth of a rolling element raceway groove | channel with respect to a rolling element diameter. It is a figure which shows the relationship between durability of a rolling bearing without a cage | basket, and the center part depth of a rolling element raceway groove | channel with respect to a rolling element diameter. It is radial direction sectional drawing of the rolling bearing which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship between the ratio of the diameter of a resin rolling element and the diameter of a non-resin rolling element, and durability of a rolling bearing.

Explanation of symbols

1A Rolling bearing with cage 1B Rolling bearing without cage 2 Inner ring 3 Outer ring 4, 5 Rolling element raceway groove 6 Rolling element 6A First rolling element 6B Second rolling element 7 Cage

Claims (11)

An inner ring made of a resin composition; an outer ring made of resin provided on the outer periphery of the inner ring; a rolling element raceway groove formed on the outer peripheral surface of the inner ring; and a rolling element raceway groove formed on the inner peripheral surface of the outer ring. In a rolling bearing comprising a large number of spherical rolling elements that roll as the inner ring or the outer ring rotates,
A rolling bearing characterized in that a depth of a central portion of the rolling element raceway groove is 18% or more and 45% or less with respect to a diameter of the rolling element.   The rolling element raceway groove has a cross-sectional shape along the axial direction of the inner ring and the outer ring formed in a Gothic arch shape or an arc shape with a curvature of 50.5% to 51.9% with respect to the diameter of the rolling element. The rolling bearing according to claim 1, wherein:   The rolling element according to claim 1 or 2, wherein the rolling element is held by a retainer provided between the inner ring and the outer ring so as to be able to roll in a circumferential direction of the inner ring and the outer ring. bearing.   4. The rolling bearing according to claim 3, wherein a depth of a central portion of the rolling element raceway groove is 18% or more and 28% or less with respect to a diameter of the rolling element.   The rolling element raceway groove has a cross-sectional shape along the axial direction of the inner ring and the outer ring formed in a Gothic arch shape or an arc shape with a curvature of 52.2% to 55% with respect to the diameter of the rolling element. The rolling bearing according to claim 4, wherein   The rolling bearing according to any one of claims 1 to 5, wherein at least one of the rolling elements is made of a resin composition.   At least one of the rolling elements is formed of a resin composition mainly composed of any one of polyethylene resin, polypropylene resin, polyacetal resin, melt-resistant corrosion-resistant resin, and fluorine-containing resin. The rolling bearing according to claim 1, wherein the rolling bearing is provided.   The plurality of rolling elements are composed of a first rolling element made of a non-resin composition and a second rolling element made of a resin composition, and the first rolling element and the second rolling element are between the inner ring and the outer ring. 3. The rolling bearing according to claim 1, wherein the rolling bearings are arranged alternately.   9. The rolling bearing according to claim 8, wherein a ratio of the diameter of the second rolling element to the diameter of the first rolling element is 0.987 or more and 1.013 or less.   All the said many rolling elements are formed from the resin composition, The rolling bearing as described in any one of Claims 1-5 characterized by the above-mentioned.   All of the numerous rolling elements are formed from a resin composition mainly composed of any one of polyethylene resin, polypropylene resin, polyacetal resin, melt-resistant corrosion-resistant resin, and fluorine-containing resin. The rolling bearing according to any one of claims 1 to 5.

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