Rolling bearing

Abstract

The present invention relates to a rolling bearing having: an inner ring; an outer ring; a rolling body interposed between the inner ring and the outer ring; and an elastic member provided in at least one of the openings at both ends in the axial direction of the inner ring and the outer ring, the elastic member sealing a lubricant around the rolling elements, the lubricant being a silicone oil-based lubricant or a mineral oil-based lubricant. The elastic member is a sulfide of a rubber composition containing an epichlorohydrin rubber, a dispersion modifier, a reinforcing material, and a modified clay, so that the present invention can provide a rolling bearing having an elastic member in which the rubber component of the elastic member is an epichlorohydrin rubber. The elastic member is suppressed in volume change and hardness change when the lubricant is sealed, and has good wear resistance and hardness.

Description

Technical Field

[0001] The present invention relates to a rolling bearing, and more particularly to a rolling bearing having an elastic member using epichlorohydrin rubber. Background Art

[0002] Rolling bearings typically consist of an inner ring, an outer ring, and rolling elements interposed between them. Lubricant is enclosed to provide lubricity. Furthermore, to prevent this lubricant from leaking out of the opening between the inner and outer rings, a bearing seal is provided with an elastic member that seals this opening. This elastic member typically comes into contact with the lubricant while sliding against the inner or outer ring, requiring wear resistance and durability against the lubricant.

[0003] To meet the performance requirements for elastic components, rubber components such as nitrile rubber (NBR), acrylic rubber (ACM), ethylene acrylic rubber (AEM), fluororubber (FKM), and silicone rubber (VMQ) have been used as materials for elastic components used in bearing seals. These materials have been repeatedly improved to meet the application of rolling bearings and to enhance their performance.

[0004] On the other hand, epichlorohydrin rubber generally has excellent mechanical strength, heat resistance, low-temperature resistance (cold resistance), ozone resistance, air permeability, flame retardancy, and oil resistance, but it is known that its wear resistance is not necessarily sufficient. Therefore, as described in Patent Document 1, epichlorohydrin rubber is generally used as a hose material and is currently not actually used as a material for elastic components used to enclose lubricants in rolling bearings, such as those used in automobiles.

[0005] Patent Document 1: Japanese Patent Publication No. 60-33663

[0006] The present inventors, focusing on the aforementioned favorable properties of epichlorohydrin rubber, have attempted to use epichlorohydrin rubber as a rubber component for elastic members in rolling bearings. However, when using an ester oil-based lubricant containing an ester oil as a base oil, the elastic member experiences significant volume and hardness changes. (i) This large volume change leads to unstable interference fit in the seal, and (ii) the elastic member softens, for example due to a decrease in hardness. This increases the contact area between the raceway (raceway) formed by the inner and outer rings and the elastic member, leading to abnormal wear or reduced compressive force. Consequently, it has become apparent that epichlorohydrin rubber is difficult to use as a rubber component for elastic members in rolling bearings. Summary of the Invention

[0007] Therefore, an object of the present invention is to provide a rolling bearing having an elastic member having excellent wear resistance and hardness, wherein even if the rubber component of the elastic member is epichlorohydrin rubber, changes in volume and hardness when a lubricant is sealed are suppressed.

[0008] The present inventors have conducted extensive research to address the aforementioned issues. As a result, they have discovered that, when using a silicone oil or mineral oil-based lubricant containing silicone oil or mineral oil as a base oil, the rubber composition constituting the elastic member comprises epichlorohydrin rubber as the rubber component and also contains a dispersion improver, a reinforcing material, and modified clay, thereby addressing the aforementioned issues. The gist of the present invention is as follows.

[0009] The present invention relates to a rolling bearing comprising: an inner ring; an outer ring; rolling elements interposed between the inner ring and the outer ring; and an elastic member disposed in at least one of openings at both axial ends of the inner ring and the outer ring, for sealing a lubricant around the rolling elements. The lubricant is a silicone oil or a mineral oil lubricant, and the elastic member is a sulfide of a rubber composition containing epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay.

[0010] In an embodiment of the present invention, the rubber composition may contain 1.0 to 3.0 parts by weight of a dispersion improver, 25 to 35 parts by weight of a reinforcing material, and 40 to 80 parts by weight of modified clay, relative to 100 parts by weight of the epichlorohydrin rubber.

[0011] In an embodiment of the present invention, the dispersion improver may be a coupling agent.

[0012] In an embodiment of the present invention, the reinforcing material may be silicon oxide.

[0013] In an embodiment of the present invention, the modified clay is silane-modified clay, which is a surface-treated clay obtained by surface-treating the clay with a silane coupling agent.

[0014] Furthermore, in the embodiment of the present invention, the configurations of the above-described embodiments can be arbitrarily combined.

[0015] According to the present invention, a rolling bearing having an elastic member having excellent wear resistance and hardness can be provided, even if the rubber component of the elastic member is epichlorohydrin rubber, in which volume change and hardness change are suppressed when a lubricant is sealed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view of a rolling bearing according to an embodiment of the present invention.

[0017] Figure 2It will Figure 1 A cross-sectional view showing an enlarged view of the main parts.

[0018] Figure 3 It is an explanatory diagram showing a method for carrying out a wear resistance test. DETAILED DESCRIPTION

[0019] A rolling bearing according to an embodiment of the present invention comprises an inner ring; an outer ring; rolling elements interposed between the inner and outer rings; and an elastic member disposed in at least one of the axially opposite openings of the inner and outer rings, for sealing lubricant around the rolling elements. The lubricant is a silicone oil or a mineral oil. The elastic member is a vulcanized rubber composition containing epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay.

[0020] As lubricant, when using silicone oil or mineral oil lubricant, compared with the situation that used ester oil lubricant, the influence on epichlorohydrin rubber is suppressed, and the volume change and hardness change (particularly the reduction of hardness) of elastic component are suppressed.And, by and using dispersion improver, reinforcing material and modified clay, the dispersibility of the reinforcing material in epichlorohydrin rubber and modified clay is good, thus can have the mechanical strength such as tensile strength, elongation when breaking of the good characteristic that has played a role in epichlorohydrin rubber, in addition, can improve wear resistance and the hardness of elastic component.In addition, hardness refers to the Shore A hardness that can be measured by the method described in embodiment one hurdle.

[0021] An embodiment of the rubber composition used for the elastic member will be described.

[0022] As mentioned above, the rubber composition includes epichlorohydrin rubber, a dispersion improver, a reinforcing material and modified clay. For the rubber composition, the rubber component is epichlorohydrin rubber. That is, as a rubber component, other rubber components other than the epichlorohydrin rubber are not included. As epichlorohydrin rubber, for example, the homopolymer of epichlorohydrin (sometimes abbreviated as CO), the copolymer of epichlorohydrin and ethylene oxide (sometimes abbreviated as ECO), the copolymer of epichlorohydrin and allyl glycidyl ether (sometimes abbreviated as GCO), the copolymer of epichlorohydrin and ethylene oxide and allyl glycidyl ether (sometimes abbreviated as GECO) etc. can be listed, and these can all be used. Wherein, preferably CO and ECO. In addition, as epichlorohydrin, the epichlorohydrin derived from plant raw materials can be used. By using this epichlorohydrin obtained from the raw material derived from plants, epichlorohydrin rubber can be made into an environmentally friendly rubber component. From the viewpoint of environmental protection, it is preferred to use the epichlorohydrin derived from plant raw materials, more preferably the homopolymer (CO) of the epichlorohydrin derived from plant raw materials. The content of the epichlorohydrin rubber in the rubber composition can be appropriately determined depending on the application of the rolling bearing, and can account for, for example, 35 to 75% by weight of the entire rubber composition.

[0023] As long as the dispersion improver can improve the dispersibility of the epichlorohydrin rubber of the reinforcing material and the modified clay, there is no particular limitation, and it can be appropriately selected according to the type of reinforcing material and the modifier. As such a dispersion improver, for example, a coupling agent, a surfactant, etc. can be listed. Among them, from the viewpoint of improving dispersibility and wear resistance, a coupling agent is preferably used. As a coupling agent, for example, silane coupling agents such as vinyl silane coupling agents, amino silane coupling agents, epoxy silane coupling agents, and mercapto silane coupling agents, zirconium oxide coupling agents, titanate coupling agents, aluminate coupling agents, etc. can be listed. Among them, a silane coupling agent is preferably used, and as a silane coupling agent, a mercapto silane coupling agent is particularly preferably used. For a mercapto silane coupling agent, for example, a functional group having 1 to 3 mercapto groups (-SH) directly bonded to Si or a mercapto group can be listed. As a functional group containing a mercapto group, for example, a hydrocarbon group having 1 to 6 carbon atoms substituted by a mercapto group can be listed. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, but is preferably a saturated hydrocarbon group. Furthermore, the hydrocarbon group may be linear or branched, but is preferably linear. Furthermore, the silane coupling agent preferably has an alkoxy group. Examples of the alkoxy group include methoxy and ethoxy, with methoxy being more preferred. The number of alkoxy groups may be any number from 1 to 3. Furthermore, the dispersion improver may be used alone or in combination of two or more.

[0024] The content of the dispersion improver in the rubber composition can be appropriately determined depending on the application of the rolling bearing, etc. From the viewpoint of dispersibility and wear resistance, the content is preferably 0.5 to 5.0 parts by weight, more preferably 1.0 to 3.0 parts by weight, per 100 parts by weight of epichlorohydrin rubber.

[0025] As a reinforcing material, as long as it can be used to improve the wear resistance and hardness of the elastic component with modified clay, there is no particular limitation. For example, silicon oxide, calcium carbonate, barium sulfate, clay (except modified clay), fiber, organic reinforcing agent, organic filler, etc. can be listed. As a reinforcing material, one of the above can be used alone, or two or more can be used in combination. The reinforcing material is particularly preferably the silicon oxide in the above-mentioned specific example. As long as silicon oxide is silicon dioxide or a substance composed of silicon dioxide, for example, silicates such as wet silicon oxide, fumed silicon oxide, diatomaceous earth, and magnesium silicate can be listed. Among them, silicon oxide is preferably silicon dioxide such as wet silicon oxide and fumed silicon oxide.

[0026] The content of the reinforcing material in the rubber composition can be appropriately determined depending on the application of the rolling bearing, etc. From the viewpoint of improving the hardness and wear resistance of the elastic member, the content is preferably 15 to 40 parts by weight, more preferably 25 to 35 parts by weight, per 100 parts by weight of the epichlorohydrin rubber.

[0027] As modified clay, as long as it can be used to improve the wear resistance and hardness of the elastic component with reinforcing material, there is no particular limitation. As such modified clay, for example, silane-modified clay etc. can be cited. Silane-modified clay is preferably clay (surface-treated material) obtained by surface-treating clay with a silane coupling agent. The clay used when carrying out this treatment can, for example, be fired at 600 ° C. Such silane-modified clay can use commercially available products, for example, Burgess KE etc. manufactured by BURGESS company can be cited.

[0028] The content of the modified clay in the rubber composition can be appropriately determined depending on the application of the rolling bearing, etc. From the viewpoint of improving the hardness and wear resistance of the elastic component, the content is preferably 10 to 90 parts by weight, more preferably 40 to 80 parts by weight, per 100 parts by weight of the epichlorohydrin rubber.

[0029] In addition to the above-mentioned components, other components may be added to the rubber composition. Examples of such other components include vulcanizing agents, vulcanization accelerators, stabilizers, antioxidants, lubricating oils, plasticizers, softeners, colorants, processing aids, and scorch retardants.

[0030] Examples of vulcanizing agents include sulfur; quinoxaline-based vulcanizing agents such as 2,3-dimercaptoquinoxaline, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, and 5,8-dimethylquinoxaline-2,3-dithiocarbonate; 2,4,6-trimercapto-s-triazine; thiurams such as tetramethylthiuram monosulfide (TMTS), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), and dipentamethylenethiuram tetrasulfide (DPTT); and sulfur-based vulcanizing agents such as 4,4′-dimorpholine disulfide. These agents may be used alone or in combination. The content of the vulcanizing agent is preferably 0.5 to 10 parts by weight per 100 parts by weight of the epichlorohydrin rubber.

[0031] Examples of vulcanization accelerators include guanidine compounds, imidazole compounds, quaternary ammonium salts, tertiary amine compounds, tertiary phosphine compounds, and alkali metal salts of weak acids. Examples of guanidine compounds include 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine. Examples of imidazole compounds include 2-methylimidazole and 2-phenylimidazole. Examples of quaternary ammonium salts include tetra-n-butylammonium bromide and octadecyltri-n-butylammonium bromide. Examples of tertiary amine compounds include triethylenediamine and 1,8-diazabicyclo[5,4,0]undecene-7. Examples of tertiary phosphine compounds include triphenylphosphine and tri-p-tolylphosphine. Examples of alkali metal salts of weak acids include inorganic weak acid salts such as sodium phosphate, potassium phosphate, and carbonates, and organic weak acid salts such as stearates and laurates. The content of the vulcanization accelerator is preferably 0.1 to 5 parts by weight per 100 parts by weight of the epichlorohydrin rubber.

[0032] Examples of the stabilizer include magnesium oxide, hydrotalcites, zeolites, calcium oxide, aluminum oxide, basic silica, magnesium hydroxide, etc. These may be used alone or in combination of two or more.

[0033] The rubber composition can be obtained by mixing the above-mentioned essential components and other components used as needed in a desired mixing ratio and uniformly kneading them. As a kneading method, a conventionally known method can be adopted. For example, a method of uniformly kneading using a sealed kneading machine such as a kneader or a Banbury mixer, or an open kneading machine such as a roller can be cited.

[0034] The elastic member according to the embodiment can be obtained as a vulcanized product (molded article) of the rubber composition having a predetermined shape by vulcanizing and molding the rubber composition obtained as described above at a predetermined temperature by a molding method such as compression molding, injection molding, transfer molding, extrusion molding, or calendar molding.

[0035] For the elastic component obtained by vulcanizing the above-mentioned rubber composition, even if the rubber component is epichlorohydrin rubber, when the lubricant enclosing the rolling bearing is a specific lubricant, the influence of the lubricant is also suppressed, and the good properties of the epichlorohydrin rubber itself will not be damaged substantially. Moreover, even if such an elastic component contacts with a specific lubricant, its volume change and hardness change (particularly the reduction of hardness) are also suppressed, and have good hardness, and also have good wear resistance. Therefore, as long as the lubricant is a specific lubricant, such an elastic component can be used for various rolling bearings. For example, it is applicable to rolling bearings with an elastic component enclosing silicone oils or mineral oil lubricants for automobiles, for example, electrical equipment of automobiles, auxiliary machines.

[0036] Hereinafter, an embodiment of a rolling bearing using the elastic member described above will be described with reference to the accompanying drawings. In the following, the axial direction of the rotating shaft will be referred to as the "axial direction," and the direction of the rotation radius will be referred to as the "radial direction."

[0037] Figure 1 and Figure 2 A rolling bearing 1 is shown in which a bearing seal 11 is installed. The inner ring 2 and outer ring 3 of the rolling bearing 1 rotate relative to each other via a plurality of rolling elements 5 held by a retainer 4. A lubricant 10 is sealed between the inner ring 2 and the outer ring 3. Bearing seals 11, 11 are provided at both axial ends (left and right in the bearing width direction) of the plurality of rolling elements 5. The bearing seals 11, 11 block the annular axial end openings A, A between the inner ring 2 and the outer ring 3 and are generally annular in shape when viewed from the front.

[0038] As mentioned above, the lubricant is a silicone oil or mineral oil lubricant. The lubricant can be a liquid lubricating oil or a semi-solid or solid grease, but is preferably a grease. In the case of a grease, the base oil is silicone oil or mineral oil, and various thickeners may be included. The thickener may be any known thickener, and examples thereof include metal soaps such as lithium soap and urea.

[0039] In addition, the bearing seal 11 may not be Figure 1 The double-shielded type shown here seals both sides of the annular openings A, A of the rolling bearing 1. In contrast, the single-shielded type seals only one side of the rolling bearing 1, depending on the location of use. Specifically, the bearing seal 11 is provided in at least one of the annular openings A, A between the inner ring 2 and outer ring 3 of the rolling bearing 1, located on either side of the bearing width.

[0040] like Figure 2 As shown, the bearing seal 11 comprises an elastic member 13 continuously wrapped around the outer and inner circumferences of an annular metal core 12 made of, for example, steel plate, by vulcanization bonding. The inner circumferential end of the elastic member 13 serves as a sealing lip 14, while the outer circumferential end serves as an outer diameter mounting portion 15. Furthermore, the axially inner contact lip (main lip) 14a of the sealing lip 14 is press-fitted against the radially extending sidewall surface 8 of the inner ring 2, thereby preventing leakage of the lubricant 10 filling the bearing 1 and preventing the ingress of foreign matter from the outside. Furthermore, the axially outer non-contact lip (dust lip) 14b of the sealing lip 14 faces the outer circumferential surface of the inner ring 2, outside the circumferentially extending inner ring groove 6 (also known as a seal groove), formed on the outer circumferential surface of the inner ring 2, with a slight gap therebetween. This labyrinth seal effect reduces the ingress of foreign matter from the outside.

[0041] exist Figure 2In the illustrated embodiment, a constricted portion 16 is formed between the inner circumferential surface 12A of the core metal 12 of the bearing seal 11 and the sealing lip 14. When the bearing seal 11 is mounted on the outer ring 3, as described above, the contact lip 14a of the sealing lip 14 is pressed against the side wall surface 8 of the inner ring 2. The structure for this pressurized contact takes into account the balance between the lip position fluctuations caused by the centrifugal force generated by the rotation of the outer ring 3. The shape, size, and position of the sealing lip 14 and constricted portion 16 can be appropriately determined using conventional methods to ensure that the centrifugal forces applied to the contact lip 14a and non-contact lip 14b during rotation of the outer ring 3 are approximately equal. This balance prevents the pressure exerted by the contact lip 14a against the side wall surface 8 from being reduced, thereby widening the gap between the non-contact lip 14b and the inner ring 2 and facilitating the intrusion of dust, or the contact lip 14a from separating from the side wall surface 8, creating a gap that could cause leakage of lubricant 10 or the intrusion of dust, water, etc. Furthermore, the sealing lip 14 and the constricted portion 16 are elastic components formed from a cured product of the aforementioned rubber composition. Consequently, when a prescribed lubricant is used, they possess excellent properties such as mechanical strength (tensile burst strength, tensile burst elongation, etc.) derived from epichlorohydrin rubber, and also possess excellent hardness and wear resistance. Consequently, through a synergistic effect with the structure of the sealing lip 14, it is possible to continuously maintain good pressure contact between the contact lip 14a and the side wall surface 8, thereby suppressing a reduction in the life of the rolling bearing.

[0042] like Figure 2 As shown, a convex portion 17 is formed on the bearing seal 11 from the front end face 12A of the core metal 12 toward the inner direction of the bearing. It is preferred to set a small gap between the convex portion 17 and the front end edge of the side wall surface 8, that is, the end edge in the outer ring direction, so that the lubricant is not easy to flow toward the contact lip 14a through the labyrinth effect.

[0043] like Figure 2 As shown, outer diameter mounting portion 15 is fitted into outer ring circumferential groove 7 formed on the inner circumferential surface of outer ring 3, thereby positioning and securing bearing seal 11 to bearing 1 and preventing foreign matter from entering through the outer diameter portion of bearing seal 11. Furthermore, outer diameter mounting portion 15 is also an elastic member formed from the cured rubber composition described above. This maintains good contact between outer diameter mounting portion 15 and outer ring circumferential groove 7, effectively preventing the intrusion of foreign matter.

[0044] In addition, in this embodiment, the case where the above-mentioned elastic component is applied to a rolling bearing with a structure in which the contact lip 14a of the sealing lip 14 is always pressed against the side wall surface 8 of the inner ring 2 is described, but the present invention is not limited to such an embodiment. For example, as described in Japanese Patent Gazette No. 2010-265968, an elastic component having a structure that functions as a contact seal to seal the rolling bearing when the rotation speed of the outer ring is relatively low, and functions as a non-contact seal even when the sealing lip is separated from the inner ring when the rotation speed of the outer ring is relatively high, can also be applied as an elastic component that is a vulcanized rubber composition mentioned above, and in particular, when functioning as a contact seal, it can have good hardness and good wear resistance.

[0045] Example

[0046] Hereinafter, an elastic member that can be used in a rolling bearing according to an embodiment of the present invention will be described in detail.

[0047] (Test Example 1): Confirmation of oil resistance against silicone and mineral oil lubricants

[0048] <Preparation of elastic components>

[0049] 100.0 parts by weight of epichlorohydrin rubber (Hydrin H75, CO, manufactured by ZEON Corporation of Japan), 1.8 parts by weight of a vulcanizing agent (Zisnet F, 2,4,6-trimercapto-s-triazine, manufactured by Sankyo Chemical Co., Ltd.), 0.6 parts by weight of a vulcanization accelerator (Soxinol DG, 1,3-diphenylguanidine, manufactured by Sumitomo Chemical Co., Ltd.), 1.0 part by weight of a dispersion improver (A-189, silane coupling agent, γ-mercaptopropyltrimethoxysilane, manufactured by Momentive), 30.0 parts by weight of a reinforcing material (Nipsil ER, silica, manufactured by Tosoh Silicone Chemicals Co., Ltd.), and 60.0 parts by weight of a modified clay (Burgess KE, silane-modified clay, manufactured by Burgs Co., Ltd.) were mixed and kneaded using an 8-inch open roll to obtain a rubber composition. The obtained rubber composition was subjected to primary vulcanization (150-180°C, 10-15 minutes) and secondary vulcanization (150-180°C x 1-10 hours) to form a sheet, thereby obtaining a rubber sheet (rubber molded body, hereinafter referred to as "elastic member") having a thickness of 2 mm.

[0050] Tensile test

[0051] The tensile strength at break and the elongation at break of the obtained elastic member were measured in advance in accordance with JIS K 6251. The results were 14.2 MPa and 570%, respectively, confirming that the elastic member was suitable as an elastic member for rolling bearings.

[0052] Oil resistance test

[0053] The resulting elastic members were previously measured for hardness (Shore A hardness) in accordance with JIS K 6253-3, and for volume in accordance with JIS K 6258. They were then immersed in a mineral oil-based lubricant, silicone oil-based lubricant, or ester oil-based lubricant at 150°C for 72 hours. The hardness and volume were then measured in the same manner, and the hardness change (ΔShore A) and volume change rate (ΔV) were measured using the following formulas to evaluate oil resistance.

[0054] Δ Shore A = (Shore A hardness after immersion in lubricant) - (Shore A hardness before immersion in lubricant)

[0055] ΔV (%) = [(volume after immersion in lubricant / volume before immersion in lubricant) - 1] × 100

[0056] The evaluation criteria are as follows.

[0057] When ΔShore A is -20 or more and 20 or less, the wear amount can be suppressed and the steel sheet can be actually used.

[0058] When ΔV is not less than -5% and not more than 20%, the variation in the interference of the bearing seal is small, the torque is stable, and the bearing seal can be actually used.

[0059] The evaluation results and the lubricants used are shown in Table 1. The manufacturers and sellers of the lubricant product names in Table 1 are as follows: Alvania S: Shell Lubricants Japan Ltd., Raremax AF-I: Kyodo Yushi Co., Ltd., G40M: Shin-Etsu Chemical Co., Ltd., Molykote 44M: Dow Corning Toray Co., Ltd., HQ72-102: NOKKLUBER Co., Ltd., and Multemp SRL: Kyodo Yushi Co., Ltd.

[0060] Table 1

[0061]

[0062] (Test Example 2): Study on the Addition Amount of Dispersion Improver <Preparation of Elastic Member>

[0063] A rubber sheet (rubber molded article, hereinafter referred to as “elastic member”) having a thickness of 2 mm was prepared in the same manner as in Test Example 1 except that the components were mixed in the compounding ratio shown in Table 2.

[0064] Wear test

[0065] Test pieces were prepared using each elastic member, using Figure 3 The wear resistance tester was used to measure the wear loss (mm) of the test piece while applying a load from above with a friction plate. The test conditions were load: 200 gf, rotation speed: 10,000 rpm, and time: 15 minutes.

[0066] The evaluation criteria are as follows. In the case of "×", it is not actually usable.

[0067] ○: less than 0.10mm

[0068] △: 0.10mm or more and 0.30mm or less

[0069] ×: greater than 0.30mm

[0070] <Dispersibility test>

[0071] The resulting elastic member was used to produce a JIS No. 3 dumbbell, with the longitudinal direction aligned with the grain direction, in accordance with JIS K 6251. Two surfaces of the resulting dumbbell's fracture surface corresponding to the area between the markings (20 mm between the markings and both sides within a range of 2 mm in the thickness direction) were photographed using a digital microscope, and the size of the dispersed matter in the photographs was measured to confirm dispersibility.

[0072] The evaluation criteria for dispersibility are as follows. In the case of "×", the sample is not actually usable.

[0073] ○: Only dispersed particles with a size of 0.029 mm or less were observed during the imaging.

[0074] △: During the image capture, one or more dispersed particles larger than 0.029 mm and smaller than 0.049 mm were observed.

[0075] ×: During the photographing, one or more dispersed objects larger than 0.049 mm were observed. The evaluation results are shown in Table 2.

[0076] Table 2

[0077]

[0078] (Test Example 3): Study on the amount of modified clay added

[0079] <Preparation of elastic components>

[0080] A rubber sheet (rubber molded article, hereinafter referred to as “elastic member”) having a thickness of 2 mm was prepared in the same manner as in Test Example 1, except that the components were mixed in the mixing ratio shown in Table 3.

[0081] Wear test

[0082] A wear test was performed and evaluated in the same manner as in Test Example 2.

[0083] <Hardness test>

[0084] The obtained elastic member was used to measure and evaluate the hardness (Shore A hardness) in accordance with JIS K 6253-3. The evaluation criteria were as follows: in the case of "X", the elastic member was not practically usable.

[0085] ◎: Shore A hardness of 65 or more and 75 or less

[0086] ○: Shore A hardness of 60 or more and less than 65

[0087] △: Shore A hardness greater than 75 and less than 85

[0088] ×: Shore A hardness less than 60 or greater than 85

[0089] The evaluation results are shown in Table 3.

[0090] Table 3

[0091]

[0092] (Test Example 4): Study on the amount of reinforcement material added

[0093] <Preparation of elastic components>

[0094] A rubber sheet (rubber molded article, elastic member) having a thickness of 2 mm was prepared in the same manner as in Test Example 1, except that the components were mixed in the compounding ratio shown in Table 4.

[0095] Wear test

[0096] A wear test was performed and evaluated in the same manner as in Test Example 3.

[0097] <Hardness test>

[0098] A hardness test was performed and evaluated in the same manner as in Test Example 3.

[0099] The evaluation results are shown in Table 4.

[0100] Table 4

[0101]

[0102] As shown in Table 1, for elastic components containing specified components, even if the rubber component is epichlorohydrin rubber, in the case of silicone oil or mineral oil lubricants, the change in hardness (Shore A hardness) and the volume change rate of the elastic components are smaller than those of ester oil lubricants, making them suitable for rolling bearings. As shown in Table 2, the inclusion of a dispersion improver makes the dispersibility of the reinforcing material and the modified clay good, thereby having a wear resistance at a level that does not pose a practical problem in the application to rolling bearings. As shown in Tables 3 and 4, the inclusion of a reinforcing material and modified clay achieves a wear resistance and hardness at a level that does not pose a practical problem in the application to rolling bearings. Therefore, as shown in Tables 1 to 4, when the lubricant is silicone oil or mineral oil lubricant, rolling bearings having specified elastic components are suitable for use as rolling bearings for various purposes such as automotive use.

[0103] Description of Reference Numerals

[0104] A…annular opening; 1…rolling bearing; 2…inner ring; 3…outer ring; 4…retainer; 5…rolling element; 6…inner ring circumferential groove; 7…outer ring circumferential groove; 8…side wall surface; 9…outer peripheral surface; 10…lubricant (grease); 11…bearing seal; 12…core metal; 12A…inner peripheral surface; 13…elastic component; 14…sealing lip; 14a…contact lip; 14b…non-contact lip (dustproof lip); 15…outer diameter mounting portion; 16…narrowed portion; 17…convex portion.

Claims

1. A rolling bearing comprising: inner circle; outer ring; rolling elements, interposed between the inner race and the outer race; and an elastic member provided at least at one of the axial end openings of the inner ring and the outer ring, for sealing lubricant around the rolling element; It is characterized by: The lubricant is a silicone oil or mineral oil lubricant, The elastic member is a vulcanized product of a rubber composition containing epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay.

2. The rolling bearing according to claim 1, characterized in that The rubber composition comprises 1.0 to 3.0 parts by weight of a dispersion improver, 25 to 35 parts by weight of a reinforcing material, and 40 to 80 parts by weight of modified clay, relative to 100 parts by weight of the epichlorohydrin rubber.

3. The rolling bearing according to claim 1 or 2, characterized in that: The dispersion improver is a coupling agent.

4. The rolling bearing according to claim 1 or 2, characterized in that: The reinforcing material is silicon oxide.

5. The rolling bearing according to claim 1 or 2, characterized in that: The modified clay is silane-modified clay, which is a surface-treated clay obtained by surface-treating the clay with a silane coupling agent.

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