Sealed rolling bearings

Abstract

To provide a rolling bearing with a seal capable of stably molding a part of fine projections of a rubber material by applying a seal member having fine projections in slide-contact with an axial side face of a retainer, on a part of the rubber material adhering to an axial inner face of a core metal.SOLUTION: An outer face rubber portion 23 is formed in a manner of covering the whole surface of an axial outer face of a core metal 20. An inner face rubber portion 24 is formed with: an annular opening portion 30 for exposing an axial inner face of the core metal 20 at a position on the same circumference passing through a radial outer side than fine projections 29; and a circular arc-shaped opening portion 31 for exposing the axial inner face of the core metal 20 at a position on the same circumference passing through a radial inner side than the fine projections 29.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a sealed rolling bearing in which a seal member is provided between an inner ring and an outer ring. [Background technology]

[0002] Sealed rolling bearings are often used as bearings that support rotating shafts in automobiles, industrial machines, etc. A sealed rolling bearing has an inner ring, an outer ring that is coaxially arranged radially outward of the inner ring, multiple rolling elements arranged in an annular space formed between the inner ring and the outer ring, an annular cage that holds the multiple rolling elements, and an annular seal member that closes the axial end opening of the annular space between the inner ring and the outer ring (see, for example, Patent Document 1).

[0003] Sealed rolling bearings are generally designed so that the cage and seal member do not come into contact with each other. In other words, the cage that holds the rolling elements rotates at the orbital speed of the rolling elements (a speed intermediate between the rotational speed of the inner ring and the rotational speed of the outer ring), so there is a difference in rotational speed between the cage and the seal member. As a result, if the cage comes into contact with the seal member, the frictional resistance between the cage and the seal member will cause excessive torque loss and abnormal heat generation. For this reason, sealed rolling bearings are generally designed to keep the cage and seal member out of contact with each other.

[0004] In response to this, the applicant of the present application has already proposed a sealed rolling bearing that can be used with the cage and seal member in contact with each other (see Patent Document 2). The rolling bearing of Patent Document 2 has a plurality of minute protrusions, spaced apart in the circumferential direction, on the axially inner surface of the seal member, which slides against the axial side surface of the cage. With this rolling bearing of Patent Document 2, an oil film is formed between the minute protrusions on the axially inner surface of the seal member and the axial side surface of the cage due to the wedge film effect when the bearing rotates, and this oil film creates a fluid lubrication state between the contact surfaces of the cage and the seal member, so that the contact resistance between the cage and the seal member can be kept extremely small. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 143786 [Patent Document 2] JP 2020-133770 A Summary of the Invention [Problem to be solved by the invention]

[0006] The seal member used in the rolling bearing of Patent Document 2 is composed of a core metal in the form of an annular plate facing the cage in the axial direction, and a rubber material vulcanized and bonded to the core metal. Here, the rubber material has an outer rubber portion bonded to the axial outer surface of the core metal, an inner rubber portion bonded to the axial inner surface of the core metal, an outer periphery rubber portion extending radially outward from the radial outer end of the core metal and fitted and fixed in a seal fixing groove formed on the inner circumference of the outer ring, and a seal lip portion extending radially inward from the radial inner end of the core metal. The inner rubber portion is formed so as to cover the entire axial inner surface of the core metal, and a plurality of small protrusions that slide against the axial side surface of the cage are provided at intervals in the circumferential direction on this inner rubber portion. On the other hand, the outer rubber portion is formed so as to cover only a part of the axial outer surface of the core metal so as to expose most of the axial outer surface of the core metal.

[0007] In the sealing member of Patent Document 2, the axially outer surface of the core is exposed from the rubber material, so when the rolling bearing is used in an environment exposed to foreign matter such as water, the exposed part of the core from the rubber material may become susceptible to foreign matter such as water and rust.

[0008] Therefore, the inventors of the present application considered modifying the seal member of Patent Document 2 so that the entire axial outer surface of the core is covered with a rubber material. However, they found that if the entire axial outer surface of the core is covered with a rubber material, it is difficult to stably form minute protrusions on the rubber material portion bonded to the axial inner surface of the core when the seal member is vulcanized.

[0009] That is, a sealing member consisting of a core metal and a rubber material is generally manufactured by vulcanization molding. Vulcanization molding is performed by placing an unvulcanized rubber material between an upper mold and a lower mold that face each other vertically, and then sandwiching and pressurizing the rubber material between the upper and lower molds while heating the upper and lower molds. By sandwiching and pressurizing the unvulcanized rubber material between the upper and lower molds, it is molded into the shape of the cavity formed between the upper and lower molds, and by heating, the vulcanization reaction of the rubber material progresses, causing it to lose fluidity and change into an elastic rubber material. The core metal is placed in the cavity in advance, so that it adheres to the rubber material that is molded in the cavity.

[0010] Here, when the unvulcanized rubber material is sandwiched between the upper and lower dies and pressurized to form it into the shape of the cavity, the core is placed in a state in which it is in contact with and supported by the lower die in advance. Since the rubber material does not flow into the contact area between the core and the lower die, after the seal member is vulcanized and molded, a part of the surface of the core (the part that was in contact with the lower die) is exposed from the rubber material. Therefore, when manufacturing a seal member consisting of a core and a rubber material, it is usually difficult to cover the entire surface of both the axial inner surface and the axial outer surface of the core with the rubber material, and one of the axial inner surface and the axial outer surface of the core will have a part exposed from the rubber material.

[0011] Therefore, when the seal member of Patent Document 2 is modified so that the entire axial outer surface of the core is covered with a rubber material, it becomes necessary to provide a portion of the axial inner surface of the core that is exposed from the rubber material. On the other hand, since the seal member of Patent Document 2 needs to provide a plurality of minute protrusions that come into sliding contact with the axial side surface of the cage on the portion of the rubber material that is bonded to the axial inner surface of the core, in order to secure a portion of the rubber material for providing the minute protrusions, it is not possible to adopt a configuration in which most of the axial inner surface of the core is exposed from the rubber material, as in general seal members (for example, the seal member shown in Patent Document 1).

[0012] Therefore, when modifying the seal member of Patent Document 2 so that the entire axial outer surface of the core is covered with a rubber material, it is possible to form, for example, an annular opening in the inner rubber part bonded to the axial inner surface of the core at a position on the same circumference that passes radially outside the small protrusions, which continuously exposes the axial inner surface of the core over the entire circumference. If this annular opening is formed in the inner rubber part, it becomes possible to perform vulcanization molding of the seal member using an upper mold and a lower mold while the part of the core corresponding to the circular opening is supported by the lower mold.

[0013] However, when the above-mentioned configuration is adopted, the core metal is supported by the lower mold at only one location in the radial direction (only the portion corresponding to the annular opening of the rubber material), so when the unvulcanized rubber material is sandwiched between the upper and lower molds and pressurized, the core metal is deformed by the pressure applied. If the pressure applied to the unvulcanized rubber material by the upper and lower molds is reduced in order to prevent deformation of the core metal, the minute protrusions of the rubber material cannot be stably molded.

[0014] In this way, when the sealing member of Patent Document 2 is modified so that the entire axial outer surface of the core is covered with rubber material, it was found that it is difficult to stably mold the small protrusions of the rubber material portion adhered to the axial inner surface of the core when the sealing member is vulcanization molded.

[0015] The problem that this invention aims to solve is to provide a sealed rolling bearing that employs a seal member in which tiny protrusions formed on the rubber portion bonded to the axial inner surface of the core bar are in sliding contact with the axial side surface of the cage, and in which the tiny protrusion portion of the rubber material can be stably molded. [Means for solving the problem]

[0016] In order to solve the above problems, the present invention employs the following configuration for a sealed rolling bearing. With the inner circle, an outer ring provided coaxially on the radially outer side of the inner ring; a plurality of rolling elements installed in an annular space formed between the inner ring and the outer ring; an annular cage that holds the plurality of rolling elements; an annular seal member provided at one end opening in the axial direction of the annular space, the seal member includes a metal core having an annular plate shape that faces the cage in the axial direction, and a rubber material that is vulcanized and bonded to the metal core, the rubber material has an outer rubber portion bonded to an axially outer surface of the core metal, an inner rubber portion bonded to an axially inner surface of the core metal, an outer peripheral rubber portion extending radially outward from a radially outer end of the core metal and fitted into and fixed in a seal fixing groove formed on an inner circumference of the outer ring, and a seal lip portion extending radially inward from a radially inner end of the core metal, In the rolling bearing, a plurality of small protrusions that are in sliding contact with a side surface of the cage in an axial direction are provided at intervals in the circumferential direction on the inner surface rubber portion, The outer rubber portion is formed so as to cover the entire axial outer surface of the core bar, A sealed rolling bearing characterized in that the inner rubber portion is formed with a first opening exposing the axial inner surface of the core bar at a position on the same circumference that passes radially outside the multiple small protrusions, and a second opening exposing the axial inner surface of the core bar at a position on the same circumference that passes radially inside the multiple small protrusions.

[0017] In this way, when the seal member is vulcanized and molded using the upper and lower dies, the part of the core metal corresponding to the first opening of the rubber material and the part of the core metal corresponding to the second opening of the rubber material can be vulcanized and molded in a state where they are supported by the lower die. Here, the first opening of the rubber material is located radially outward from the microprotrusions, and the second opening of the rubber material is located radially inward from the microprotrusions, so that the core metal is supported on both sides, radially outward from the microprotrusions and radially inward from the microprotrusions. Therefore, when the unvulcanized rubber material is sandwiched between the upper and lower dies and pressurized, the core metal is not easily deformed by the pressurization, and the pressure applied to the rubber material by the upper and lower dies can be made sufficiently strong, so that the part of the microprotrusions of the rubber material can be stably molded.

[0018] the first opening is an annular opening that exposes an axially inner surface of the core bar continuously around the entire circumference at a position on the same circumference that passes radially outward from the plurality of small protrusions, It is preferable that the second opening be configured as a plurality of arc-shaped openings that intermittently expose the axial inner surface of the core bar at circumferentially spaced positions on the same circumference that are radially inward of the plurality of small protrusions.

[0019] In this way, since the second opening is a plurality of arc-shaped openings that are exposed intermittently at intervals in the circumferential direction, when the unvulcanized rubber material is sandwiched and pressed between the upper and lower dies, the portions between adjacent arc-shaped openings in the circumferential direction become flow paths for the unvulcanized rubber material. Therefore, when the unvulcanized rubber material is pressed between the upper and lower dies, the rubber material can be reliably distributed over the micro-projections, and a sealing member of stable quality can be obtained.

[0020] the first openings are a plurality of arc-shaped openings that intermittently expose the axially inner surface of the core bar at circumferentially spaced positions on the same circumference that pass radially outward from the plurality of small protrusions, The second opening may be an annular opening that continuously exposes the axial inner surface of the core bar over the entire circumference at a position on the same circumference that is radially inward of the multiple small protrusions.

[0021] In this way, since the first opening is a plurality of arc-shaped openings that are exposed intermittently at intervals in the circumferential direction, when the unvulcanized rubber material is sandwiched and pressed between the upper and lower dies, the portions between adjacent arc-shaped openings in the circumferential direction become flow paths for the unvulcanized rubber material. Therefore, when the unvulcanized rubber material is pressed between the upper and lower dies, the rubber material can be reliably distributed over the micro-projections, and a sealing member of stable quality can be obtained.

[0022] the inner surface rubber portion has a protrusion forming annular portion on which the plurality of small protrusions are formed, the protrusion forming annular portion being located radially inward from the first opening and radially outward from the second opening, the inner surface rubber portion has a plurality of radially extending portions extending radially from the protrusion-forming annular portion through spaces between the arc-shaped openings adjacent in the circumferential direction, A configuration may be employed in which the plurality of radially extending portions are arranged at intervals of 10° or less in the circumferential direction.

[0023] In this way, the areas which become the flow paths for the unvulcanized rubber material when it is sandwiched and pressurized between the upper and lower molds (the areas between adjacent arc-shaped openings in the circumferential direction) are arranged at close intervals of 10° or less in the circumferential direction, so that the rubber material can be reliably distributed over the small protrusions, resulting in a sealing member of consistent quality.

[0024] It is preferable that the small protrusions have an arc-shaped cross section perpendicular to the radial direction.

[0025] In this way, when the bearing rotates, a stable oil film is formed between the tiny protrusions on the axial inner surface of the seal member and the axial side surface of the retainer due to the wedge film effect, and this oil film creates a fluid lubrication state between the contact surfaces of the retainer and the seal member, thereby keeping the contact resistance between the retainer and the seal member extremely low. Effect of the Invention

[0026] In the sealed rolling bearing of the present invention, when the seal member is vulcanized using the upper and lower dies, the part of the core metal corresponding to the first opening of the rubber material and the part of the core metal corresponding to the second opening of the rubber material can be vulcanized and molded in a state where they are supported by the lower die. Here, the first opening of the rubber material is located radially outward from the microprotrusions, and the second opening of the rubber material is located radially inward from the microprotrusions, so that the core metal is supported on both sides, radially outward from the microprotrusions and radially inward from the microprotrusions. Therefore, when the unvulcanized rubber material is sandwiched between the upper and lower dies and pressurized, the core metal is not easily deformed by the pressure, and the pressure applied to the rubber material by the upper and lower dies can be made sufficiently strong, so that the part of the microprotrusions of the rubber material can be stably molded. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a cross-sectional view showing a sealed rolling bearing according to a first embodiment of the present invention. [Diagram 2] Cross-sectional view taken along line II-II in Figure 1. [Diagram 3] Cross-sectional view taken along line III-III in Figure 1. [Figure 4] Enlarged view of the seal member and its surroundings in Figure 1 [Diagram 5] Cross-sectional view taken along line VV in Figure 4. [Figure 6] FIG. 5 is a view of the seal member shown in FIG. 4 from the axial inner side. [Figure 7] Cross-sectional view taken along line VII-VII in Figure 6. [Figure 8] FIG. 8 is a cross-sectional view showing the state in which the seal member shown in FIG. 7 is vulcanized and molded using an upper mold and a lower mold. [Figure 9] FIG. 11 is a cross-sectional view showing a state in which a sealing member of a comparative example is vulcanized and molded using an upper mold and a lower mold. [Figure 10] FIG. 7 shows a second embodiment of the present invention, corresponding to FIG. 6. [Figure 11] Cross-sectional view taken along line XI-XI in Figure 10. [Figure 12] FIG. 11 is a cross-sectional view showing the state in which the seal member shown in FIG. 10 is vulcanized and molded using an upper mold and a lower mold. [Figure 13] FIG. 7 is a perspective view of the seal member shown in FIG. [Figure 14] FIG. 11 is a perspective view of the seal member shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Fig. 1 shows a sealed rolling bearing according to a first embodiment of the present invention. This sealed rolling bearing has an inner ring 1, an outer ring 2 provided coaxially on the radial outside of the inner ring 1, a number of rolling elements 4 assembled at intervals in the circumferential direction in annular space 3 formed between the inner ring 1 and the outer ring 2, an annular cage 5 that maintains the circumferential intervals between the multiple rolling elements 4, and an annular seal member 6 that closes one of the end openings on both axial sides of the annular space 3. Here, the rolling elements 4 are balls.

[0029] The inner ring 1 has an inner ring raceway groove 7 with which the rolling elements 4 roll and make contact, a pair of inner ring groove shoulders 8 located axially outward of the inner ring raceway groove 7, and a sliding recess 9 located axially outward of the inner ring groove shoulders 8. The inner ring raceway groove 7 is an arc groove with a concave arc-shaped cross section along the surface of the rolling elements 4, and is formed extending circumferentially through the axial center of the outer circumference of the inner ring 1. The pair of inner ring groove shoulders 8 are bank-shaped parts extending circumferentially on both sides of the inner ring raceway groove 7 in the axial direction. The sliding recess 9 is a recess extending circumferentially formed adjacent to the axial outside of the inner ring groove shoulders 8. A seal member 6 is in sliding contact with the inner surface of the sliding recess 9.

[0030] The inner circumference of the outer ring 2 is formed with an outer ring raceway groove 10 with which the rolling elements 4 roll and make contact, a pair of outer ring groove shoulders 11 located axially outward of the outer ring raceway groove 10, and a seal fixing groove 12 located axially outward of the outer ring groove shoulders 11. The outer ring raceway groove 10 is an arc groove having a concave arc-shaped cross section along the surface of the rolling elements 4, and is formed extending circumferentially through the axial center of the inner circumference of the outer ring 2. The pair of outer ring groove shoulders 11 are bank-shaped parts extending circumferentially on both sides of the outer ring raceway groove 10 in the axial direction. The seal fixing groove 12 is a groove extending circumferentially formed adjacent to the axial outside of the outer ring groove shoulders 11. A seal member 6 is fitted and fixed in the seal fixing groove 12.

[0031] The rolling elements 4 are sandwiched radially between the outer ring raceway groove 10 and the inner ring raceway groove 7. This sealed rolling bearing is a deep groove ball bearing. That is, the outer ring raceway groove 10 is an arc-shaped groove symmetrical with respect to the axial center of the outer ring 2, and the inner ring raceway groove 7 is also an arc-shaped groove symmetrical with respect to the axial center of the inner ring 1. The axial width dimension of the outer ring raceway groove 10 is greater than half the diameter of the rolling elements 4, and the axial width dimension of the inner ring raceway groove 7 is greater than half the diameter of the rolling elements 4.

[0032] The retainer 5 has a retainer annular portion 13 that extends circumferentially through a region that is axially sandwiched between the passing region of the rolling elements 4 and the seal member 6, and retainer claw portions 14 that extend axially from the retainer annular portion 13 between the rolling elements 4 that are adjacent in the circumferential direction. The retainer annular portion 13 and the retainer claw portions 14 are formed seamlessly as a single piece from a resin composition. The resin composition that forms the retainer annular portion 13 and the retainer claw portions 14 can be one made of resin material only, but here, a resin material to which a fiber reinforcing material has been added is used.

[0033] The cage claw portion 14 is formed in a cantilever shape with one axial end being a fixed end (the base of the cage claw portion 14) fixed to the cage annular portion 13 and the other axial end being a free end (the tip of the cage claw portion 14). The axial length of the cage claw portion 14 is set to be larger than the radius of the rolling elements 4.

[0034] 2, the cage claw portions 14 have pocket side surfaces 15 that circumferentially face the rolling elements 4. The portions of the pocket side surfaces 15 that receive the rolling elements 4 in the circumferential direction have a flat shape so that the pocket side surfaces 15 do not interfere with the rolling elements 4 when the cage claw portions 14 move radially outward due to centrifugal force.

[0035] As shown in Fig. 3, the portion of the pocket side surface 15 that receives the rolling elements 4 in the circumferential direction has a straight shape that extends straight in the axial direction without any circumferential inclination when viewed from the radial direction so as to not generate an axial component force when receiving the rolling elements 4. The cage annular portion 13 has a pocket bottom surface 16 that faces the rolling elements 4 in the axial direction. The pocket side surface 15 and the pocket bottom surface 16 are connected in the shape of a concave arc when viewed from the radial direction.

[0036] As shown in Fig. 4, the inner circumference of the cage annular portion 13 is guided by an inner ring groove shoulder 8 on the outer circumference of the inner ring 1. In other words, the cage 5 is an inner ring guide type cage in which the radial position is determined by contact with the inner ring 1.

[0037] The seal member 6 is composed of a metal core 20 in the form of an annular plate that faces the cage 5 in the axial direction, and a rubber material 21 that is vulcanized and bonded to the metal core 20. The metal core 20 is formed by press-molding a steel plate such as a cold-rolled steel plate or a stainless steel plate. A cylindrical portion 22 is formed at the radial outer end of the metal core 20 by bending the metal core 20 axially inward. The rubber material 21 is made of rubber such as nitrile rubber or acrylic rubber. The rubber material 21 is bonded to the surface of the metal core 20 by vulcanizing the rubber material 21 while the metal core 20 is placed in a mold (upper mold 34 and lower mold 35 in FIG. 8 ) for the seal member 6.

[0038] The rubber material 21 has an outer rubber portion 23 bonded to the axially outer surface of the core metal 20, an inner rubber portion 24 bonded to the axially inner surface of the core metal 20, an outer peripheral rubber portion 25 extending radially outward from the radially outer end of the core metal 20, and a seal lip portion 26 extending radially inward from the radially inner end of the core metal 20. The outer peripheral rubber portion 25 is fitted and fixed in the seal fixing groove 12 on the inner circumference of the outer ring 2. The seal lip portion 26 is in sliding contact with the sliding recess 9 on the outer circumference of the inner ring 1. A plurality of protrusions 27 extending in a direction perpendicular to the circumferential direction are formed at intervals in the circumferential direction on the sliding contact surface of the seal lip portion 26 with the sliding recess 9. Each protrusion 27 has a convex arc-shaped cross section.

[0039] 4 and 5, the inner rubber portion 24 is provided with a plurality of small protrusions 29 spaced apart in the circumferential direction, which come into sliding contact with the axial side surface 28 of the cage 5. In the figures, the axial height of the small protrusions 29 is exaggerated to make the presence of the small protrusions 29 easier to understand, but the axial height of the small protrusions 29 is extremely small, at 0.5 mm or less.

[0040] 5, the small protrusions 29 are formed so that their cross-sectional shape perpendicular to the radial direction is an arc shape convex in the axial direction. The small protrusions 29 may also be formed so that their cross-sectional shape perpendicular to the radial direction is a trapezoid shape convex in the axial direction. The axial side surface 28 of the cage 5 (the surface with which the small protrusions 29 slide) is perpendicular to the axial direction and is a smooth flat surface over the entire circumference.

[0041] 4, the small protrusions 29 are disposed at a position overlapping the pitch circle of the rolling elements 4 (a virtual circle connecting the centers of the multiple rolling elements 4) or radially outward from the pitch circle. Here, "the small protrusions 29 are disposed at a position overlapping the pitch circle of the rolling elements 4" means that the small protrusions 29 are in a positional relationship in which a virtual cylindrical surface passing through the pitch circle of the rolling elements 4 passes through the position of the small protrusions 29, and "the small protrusions 29 are disposed radially outward from the pitch circle of the rolling elements 4" means that the entire small protrusions 29 are radially outward from a virtual cylindrical surface passing through the pitch circle of the rolling elements 4. In the figure, the small protrusions 29 are disposed radially outward from the pitch circle of the rolling elements 4.

[0042] 4 and 5, the outer rubber portion 23 is formed so as to cover the entire axially outer surface of the core metal 20. In other words, no part of the axially outer surface of the core metal 20 is exposed from the rubber material 21, and even when the rolling bearing of this embodiment is used in an environment exposed to foreign matter such as water, foreign matter such as water is prevented from adhering to the core metal 20, thereby preventing the core metal 20 from rusting.

[0043] As shown in Figures 6, 7 and 13, the inner rubber portion 24 is formed with an annular opening 30 that continuously exposes the axial inner surface of the core wire 20 around the entire circumference at a position on the same circumference that is radially outer than the small protrusions 29, and a plurality of arc-shaped openings 31 that intermittently expose the axial inner surface of the core wire 20 at positions on the same circumference that are radially inner than the small protrusions 29, at intervals spaced circumferentially.

[0044] The inner rubber portion 24 has a protrusion-forming annular portion 32 radially inward from the annular opening 30 and radially outward from the arc-shaped opening 31. The small protrusions 29 are formed on the axially inner surface of the protrusion-forming annular portion 32 at equal intervals in the circumferential direction. The inner rubber portion 24 also has a plurality of radial extension portions 33 extending radially inward from the protrusion-forming annular portion 32 through between the arc-shaped openings 31 adjacent in the circumferential direction. The radial extension portions 33 are arranged at equal intervals of 10° or less in the circumferential direction. That is, the plurality of radial extension portions 33 are arranged at equal intervals such that the interval A between the circumferential center positions of the radial extension portions 33 is a predetermined angle of 10° or less, as shown in FIG. 6.

[0045] As shown in Figures 4 and 5, this sealed rolling bearing has a plurality of minute protrusions 29 spaced apart in the circumferential direction on the inner rubber part 24 of the seal member 6, which come into sliding contact with the axial side surface 28 of the cage 5, so that as the bearing rotates, an oil film is formed between the minute protrusions 29 of the inner rubber part 24 and the axial side surface 28 of the cage 5 due to the wedge film effect, as shown in Figure 5, and this oil film creates a fluid lubrication state between the contact surfaces of the cage 5 and the seal member 6, making it possible to keep the contact resistance between the cage 5 and the seal member 6 extremely small. As a result, abnormal heat generation due to the sliding resistance at the contact portion between the cage 5 and the seal member 6 can be prevented.

[0046] Here, the lubrication state between the sliding surfaces is classified into boundary lubrication state and hydrodynamic lubrication state. In the boundary lubrication state, the lubricating oil adsorbed on each sliding surface is a few molecular layers (10 -5 ~10 -6 The term "fluid lubrication" refers to a state in which the sliding surfaces are lubricated with an oil film of about 10 mm thick, and the fine projections and recesses of the sliding surfaces come into direct contact with each other. On the other hand, in the fluid lubrication state, a wedge film effect occurs between the sliding surfaces, causing an oil film (for example, 10 -3 ~10 -1 This refers to a state in which a wedge film effect (approximately 1 / 2 mm) is formed between the sliding surfaces, and the oil film prevents direct contact between the sliding surfaces (only indirect contact occurs via the oil film). When the wedge film effect occurs and a hydrodynamic lubrication state is established, sliding resistance becomes almost zero.

[0047] In addition, when this sealed rolling bearing is subjected to vulcanization molding of the seal member 6 using an upper mold 34 and a lower mold 35 as shown in Figure 8, it is possible to stably mold the portion of the micro-protrusions 29 of the rubber material 21.

[0048] For example, when a seal member of a comparative example having only the annular opening 30 out of the two openings, the arc-shaped opening 31 and the annular opening 30 shown in Fig. 7, is vulcanized and molded, as shown in Fig. 9, the portion of the core metal 20 supported by the lower mold 35 is only one portion in the radial direction (only the portion corresponding to the annular opening 30), so when the unvulcanized rubber material 21a is sandwiched and pressed between the upper mold 34 and the lower mold 35, the core metal 20 is deformed by the pressure as shown in Fig. 9. Therefore, if the pressure of the unvulcanized rubber material 21a by the upper mold 34 and the lower mold 35 is weakened in order to prevent the deformation of the core metal 20, the portion of the minute protrusions 29 cannot be stably molded.

[0049] In contrast, in the sealed rolling bearing of the above embodiment, as shown in Fig. 8, when the seal member 6 is vulcanized using the upper mold 34 and the lower mold 35, the vulcanization molding can be performed in a state in which the part of the core metal 20 corresponding to the annular opening 30 and the part of the core metal 20 corresponding to the arc-shaped opening 31 are supported by the lower mold 35. Here, the annular opening 30 is located radially outward from the minute protrusions 29, and the arc-shaped openings 31 are located radially inward from the minute protrusions 29, so that the core metal 20 is supported on both the radially outward side and the radially inward side of the minute protrusions 29. Therefore, when the unvulcanized rubber material 21a is sandwiched and pressurized between the upper mold 34 and the lower mold 35, the core metal 20 is not easily deformed by the pressurization, and the pressure applied to the rubber material 21a by the upper mold 34 and the lower mold 35 can be made sufficiently strong, and the part of the minute protrusions 29 can be stably molded. As a result, the adhesive strength of the minute projections 29 of the rubber material 21 to the core metal 20 can be ensured.

[0050] 8, when unvulcanized rubber material 21a is sandwiched and pressed between upper die 34 and lower die 35, the portions between adjacent arc-shaped openings 31 in the circumferential direction become flow paths for unvulcanized rubber material 21a. Therefore, when unvulcanized rubber material 21a is pressed between upper die 34 and lower die 35, rubber material 21a can be reliably distributed over the portions of minute protrusions 29, and a seal member 6 with stable quality can be obtained.

[0051] Furthermore, in this sealed rolling bearing, the radial extensions 33 (see Fig. 6) are arranged at intervals of 10° or less in the circumferential direction, so that when the unvulcanized rubber material 21a is sandwiched and pressed between the upper mold 34 and the lower mold 35, the portions that become the flow paths for the unvulcanized rubber material 21a (portions between adjacent arc-shaped openings 31 in the circumferential direction) are arranged at close intervals of 10° or less in the circumferential direction, as shown in Fig. 8. This allows the rubber material 21a to be reliably distributed over the portions of the minute protrusions 29, and a seal member 6 of stable quality can be obtained.

[0052] 10 and 11 show a second embodiment of the present invention. The second embodiment corresponds to the first embodiment in which the annular opening 30 and the arc-shaped opening 31 are interchanged. That is, comparing the first embodiment and the second embodiment, in the first embodiment, of the two openings, an opening radially outward from the small protrusion 29 and an opening radially inward from the small protrusion 29, the opening radially outward from the small protrusion 29 is the annular opening 30 and the opening radially inward from the small protrusion 29 is the arc-shaped opening 31, whereas in the second embodiment, the opening radially outward from the small protrusion 29 is the arc-shaped opening 31 and the opening radially inward from the small protrusion 29 is the annular opening 30, which is the difference between the two, and the other configurations are the same. Therefore, the parts corresponding to the first embodiment are given the same reference numerals, and the description will be omitted.

[0053] As shown in Figures 10, 11 and 14, the inner rubber portion 24 is formed with a plurality of arc-shaped openings 31 that intermittently expose the axial inner surface of the core wire 20 at positions on the same circumference that are radially outer than the small protrusions 29, and annular openings 30 that continuously expose the axial inner surface of the core wire 20 around the entire circumference, at positions on the same circumference that are radially inner than the small protrusions 29.

[0054] The inner rubber portion 24 has a protrusion-forming annular portion 32 radially inward from the arc-shaped opening 31 and radially outward from the annular opening 30. The small protrusions 29 are formed on the axially inner surface of the protrusion-forming annular portion 32 at equal intervals in the circumferential direction. The inner rubber portion 24 also has a plurality of radial extension portions 33 that extend radially outward from the protrusion-forming annular portion 32 through between the arc-shaped openings 31 adjacent in the circumferential direction. The radial extension portions 33 are arranged at equal intervals of 10° or less in the circumferential direction.

[0055] As shown in Fig. 12, in the sealed rolling bearing, similarly to the first embodiment, when the seal member 6 is vulcanized and molded using the upper mold 34 and the lower mold 35, the portion of the core metal 20 corresponding to the arc-shaped opening 31 and the portion of the core metal 20 corresponding to the annular opening 30 can be vulcanized and molded in a state in which they are supported by the lower mold 35. Here, the arc-shaped opening 31 is located radially outward from the minute protrusions 29, and the annular opening 30 is located radially inward from the minute protrusions 29, so that the core metal 20 is supported on both the radially outward side and the radially inward side of the minute protrusions 29. Therefore, when the unvulcanized rubber material 21a is sandwiched and pressurized between the upper mold 34 and the lower mold 35, the core metal 20 is unlikely to be deformed by the pressurization, and the pressure applied to the rubber material 21a by the upper mold 34 and the lower mold 35 can be made sufficiently strong, and the portion of the rubber material 21 corresponding to the minute protrusions 29 can be stably molded. As a result, the adhesive strength of the minute projections 29 of the rubber material 21 to the core metal 20 can be ensured.

[0056] 12, when the unvulcanized rubber material 21a is sandwiched and pressed between the upper mold 34 and the lower mold 35, the portions between the circumferentially adjacent arc-shaped openings 31 become flow paths for the unvulcanized rubber material 21a. Therefore, when the unvulcanized rubber material 21a is pressed between the upper mold 34 and the lower mold 35, the rubber material 21a can be reliably distributed over the portions of the minute protrusions 29, and a seal member 6 of stable quality can be obtained. Other effects are also similar to those of the first embodiment.

[0057] In the above embodiment, a ball bearing using balls as the rolling elements 4 has been taken as an example for explanation, but the present invention can also be applied to a roller bearing using rollers as the rolling elements 4.

[0058] In addition, in the above embodiment, the sealing member 6 has been described as a contact seal in which the seal lip portion 26 of the rubber material 21 is in sliding contact with the outer periphery of the inner ring 1, but the present invention can also be applied to a non-contact seal in which the seal lip portion 26 of the rubber material 21 forms a minute labyrinth gap with the outer periphery of the inner ring 1.

[0059] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0060] 1. Inner Circle 2 Outer ring 3. Annular Space 4 Rolling elements 5 Cage 6 Sealing material 12 Seal fixing groove 20 Core wire 21 Rubber material 23 Outer rubber part 24 Inner rubber part 25 Outer rubber part 26 Seal lip 28 Axial side 29 Microprotrusions 30 Circular opening 31 Arc-shaped opening 32 Circular ring for forming projection 33 Radial extension

Claims

1. Inner circle (1) and an outer ring (2) provided coaxially on the radially outer side of the inner ring (1); a plurality of rolling elements (4) installed in an annular space (3) formed between the inner ring (1) and the outer ring (2); an annular cage (5) that holds the plurality of rolling elements (4); an annular seal member (6) provided at one axial end opening of the annular space (3); The seal member (6) comprises a metal core (20) in the form of an annular plate axially opposed to the retainer (5) and a rubber material (21) vulcanized and bonded to the metal core (20), The rubber material (21) has an outer rubber portion (23) bonded to an axially outer surface of the core metal (20), an inner rubber portion (24) bonded to an axially inner surface of the core metal (20), an outer peripheral rubber portion (25) extending radially outward from a radially outer end of the core metal (20) and fitted into and fixed to a seal fixing groove (12) formed on an inner circumference of the outer ring (2), and a seal lip portion (26) extending radially inward from a radially inner end of the core metal (20), In the rolling bearing, a plurality of small protrusions (29) that are in sliding contact with an axial side surface (28) of the retainer (5) are provided at intervals in the circumferential direction on the inner surface rubber portion (24), The outer rubber portion (23) is formed so as to cover the entire axial outer surface of the core metal (20), A sealed rolling bearing characterized in that the inner surface rubber portion (24) is formed with a first opening that exposes the axial inner surface of the core metal (20) at a position on the same circumference that passes radially outside the plurality of small protrusions (29), and a second opening that exposes the axial inner surface of the core metal (20) at a position on the same circumference that passes radially inside the plurality of small protrusions (29).

2. the first opening is an annular opening (30) that continuously exposes an axially inner surface of the core metal (20) over the entire circumference at a position on the same circumference that passes radially outside the plurality of small protrusions (29); 2. A sealed rolling bearing as described in claim 1, wherein the second opening is a plurality of arc-shaped openings (31) that intermittently expose the axial inner surface of the core metal (20) at circumferentially spaced positions on the same circumference that pass radially inward of the plurality of small protrusions (29).

3. the first openings are a plurality of arc-shaped openings (31) that intermittently expose the axially inner surface of the core metal (20) at circumferentially spaced positions on the same circumference that pass radially outward of the plurality of small protrusions (29); 2. A sealed rolling bearing as described in claim 1, wherein the second opening is an annular opening (30) that continuously exposes the axial inner surface of the core metal (20) around the entire circumference at a position on the same circumference that is radially inward of the multiple small protrusions (29).

4. the inner surface rubber portion (24) has a protrusion forming annular portion (32) on which the plurality of small protrusions (29) are formed, the protrusion forming annular portion (32) being located radially inward from the first opening and radially outward from the second opening, The inner surface rubber portion (24) has a plurality of radial extension portions (33) extending radially from the projection-forming annular portion (32) through between the arc-shaped openings (31) adjacent in the circumferential direction, 4. A sealed rolling bearing according to claim 2, wherein the plurality of radially extending portions (33) are arranged at intervals of 10 degrees or less in the circumferential direction.

5. 5. A sealed rolling bearing according to claim 1, wherein the minute protrusion (29) has a cross section perpendicular to the radial direction that is arc-shaped.

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