Insulated rolling bearing and method for manufacturing an insulated rolling bearing

Abstract

To provide an insulated rolling bearing that has low manufacturing costs and can prevent the occurrence of wrinkles in the non-loaded portion of the insulating coating. [Solution] The insulating coating 5 is made by heating and deforming a heat-shrinkable tube 10 having an inner diameter φD0 that is 103% or less of the outer diameter φD of the outer ring 1.

Description

Technical Field

[0001] This invention relates to an insulating rolling bearing and a method for manufacturing the same.

Background Art

[0002] In a rolling bearing that supports the rotating shaft of a device that uses electricity, such as an electric motor or an alternator (generator), when an electric current flows inside the bearing, a spark may occur between the outer ring or the inner ring and the rolling elements, and the surface of the outer ring, inner ring, or rolling elements may be locally melted by the spark (electric erosion). As a rolling bearing capable of preventing this electric erosion, an insulating rolling bearing provided with an insulating coating on the outer ring is known (for example, Patent Document 1).

[0003] The insulating rolling bearing of Patent Document 1 includes an outer ring, an inner ring disposed radially inside the outer ring, a plurality of rolling elements incorporated between the outer ring and the inner ring, and a resin insulating coating provided on the outer ring. This insulating coating is formed by insert molding (that is, a method of molding the insulating coating by injecting molten resin into the cavity inside the mold with the outer ring set in the mold).

[0004] When providing a resin insulating coating on the outer ring, it is the mainstream to form the insulating coating by insert molding as in Patent Document 1. However, forming the insulating coating by insert molding requires large-scale equipment and molds, so there is a problem that the manufacturing cost of the insulating rolling bearing increases.

[0005] Therefore, in order to reduce the manufacturing cost of the insulating rolling bearing, a product of Patent Document 2 has been proposed as an insulating rolling bearing provided with an insulating coating by a method different from insert molding.

[0006] The insulated rolling bearing described in Patent Document 2 has a heat-shrinkable tube with an inner diameter 1.05 to 1.15 times the outer diameter of the outer ring placed radially outward of the outer ring, and by heating and shrinking the heat-shrinkable tube, a resin insulating coating is formed that covers the outer circumferential surface and a pair of axial end faces of the outer ring. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-15667 [Patent Document 2] Japanese Patent Publication No. 2001-107974 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, the inventor of the present application, following the description in Patent Document 2, fabricated a sample of an insulated rolling bearing by placing a heat-shrinkable tube with an inner diameter 1.05 to 1.15 times the outer diameter of the outer ring radially outward on the outer ring, and then heating and shrinking the heat-shrinkable tube. When durability tests were conducted on this insulated rolling bearing, it was found that wrinkles may occur in the non-loaded portion of the insulating coating of the outer ring.

[0009] Specifically, as shown in Figure 8, the inventor prepared a rolling bearing with multiple rolling elements 23 incorporated between an outer ring 21 and an inner ring 22. A heat-shrinkable tube with an inner diameter 1.05 to 1.15 times the outer diameter of the outer ring 21 was placed radially outside the rolling bearing, and an insulating coating 24 was formed to cover the outer circumferential surface and axial end surface of the outer ring 21 by heating and shrinking the heat-shrinkable tube. Next, the insulating rolling bearing was assembled to the inner circumference of the housing 25 to support a rotating shaft 26 (assuming a rotating shaft such as an electric motor or alternator). Here, when supporting a rotating shaft 26 such as an electric motor or alternator with a rolling bearing, the inner ring 22 is the rotating side and the outer ring 21 is the non-rotating side. Therefore, the inner ring 22 was fitted to the outer circumference of the rotating shaft 26 in an interference fit, and the outer ring 21 was fitted to the inner circumference of the housing 25 in a clearance fit. Then, in a durability test in which the rotating shaft 26 was continuously rotated under a constant radial load between the rotating shaft 26 and the housing 25 at a temperature of 80°C (a temperature condition assumed when the rotating shaft of an electric motor of an electric vehicle or the rotating shaft of the reduction gear of an electric motor is supported by an insulated rolling bearing), as shown in Figures 8 and 9, wrinkles were found to form in the insulating coating 24 in the non-loaded area, which is located on the opposite side (upper side in the figure) from the side where the radial load is applied (lower side in the figure). When wrinkles form, there is a risk of misalignment (eccentricity) of the center of the insulated rolling bearing.

[0010] The cause of the wrinkles described above is thought to be as follows: The insulating coating 24 formed by heating and shrinking the heat shrink tubing has the property of easily deforming in response to external forces when subsequently heated again. Therefore, in the durability test described above, the load-side portion of the insulating coating 24 (lower side in the diagram) was compressed in the thickness direction and stretched in the circumferential direction, and it is thought that this circumferential stretching caused wrinkles to form on the non-load-side portion of the insulating coating 24 (upper side in the diagram).

[0011] The inventors of this invention then considered how to prevent the occurrence of the wrinkles described above. As a result of their consideration, they focused on the fact that the insulating coating 24 formed by heating and shrinking a heat-shrinkable tube is prone to deformation in response to external forces when subsequently heated again, but this deformation occurs only within the range of the dimensions of the heat-shrinkable tube before shrinkage, and is not likely to deform beyond the dimensions of the heat-shrinkable tube before shrinkage. They then conceived the idea that if the insulating coating 24 is formed using a heat-shrinkable tube with an inner diameter the same as or close to the outer diameter of the outer ring 21, rather than using a heat-shrinkable tube with an inner diameter the same as or close to the outer diameter of the outer ring 21, it would be possible to prevent the occurrence of wrinkles on the non-load side of the insulating coating 24, even when using an insulated rolling bearing under high temperature conditions such as 80°C.

[0012] The problem that this invention aims to solve is to provide an insulated rolling bearing that has low manufacturing costs and can prevent the occurrence of wrinkles in the non-loaded portion of the insulating coating. [Means for solving the problem]

[0013] To solve the above problems, this invention provides an insulated rolling bearing with the following configuration. [Configuration 1] Outer ring and, An inner ring positioned radially inward of the outer ring, A plurality of rolling elements are incorporated between the outer ring and the inner ring, It has a resin insulating coating that covers the outer ring, In an insulated rolling bearing in which the insulating coating is formed of a heat-shrinkable tube that shrinks when heated, The outer ring has a cylindrical outer surface with a constant outer diameter along the axial direction, a pair of chamfered portions with a circular arc cross-section whose outer diameter gradually decreases axially outward from the outer surface, and a pair of axial end faces extending radially inward from the pair of chamfered portions. The insulating coating comprises a cylindrical outer circumferential coating portion that covers the outer circumferential surface of the outer ring, a pair of chamfer coating portions with a circular arc cross-section that cover the pair of chamfer portions of the outer ring, and a pair of end face coating portions that cover the pair of axial end faces of the outer ring. The insulating coating is characterized by being formed by heating and deforming the heat-shrinkable tube having an inner diameter no more than 103% of the outer diameter of the outer ring, in an insulated rolling bearing.

[0014] This configuration allows for the formation of an insulating coating by placing a heat-shrinkable tube radially outside the outer ring and heating and deforming the tube. This eliminates the need for large-scale equipment, such as insert molding, when insulating the outer ring. As a result, the manufacturing cost of insulated rolling bearings can be reduced. Furthermore, since the insulating coating uses a heat-shrinkable tube with an inner diameter of 103% or less of the outer diameter of the outer ring (i.e., a heat-shrinkable tube with an inner diameter the same as or close to the outer diameter of the outer ring) that has been heated and deformed, when the insulated rolling bearing is used under high temperature conditions, it is possible to prevent the load-side portion of the insulating coating from being compressed in the thickness direction and stretching in the circumferential direction, thereby preventing the formation of wrinkles on the non-load-side portion of the insulating coating.

[0015] [Configuration 2] The insulating rolling bearing according to configuration 1, wherein the arc radius of the chamfered portion of the outer ring is at least twice the thickness of the chamfered covering portion.

[0016] [Configuration 3] The insulating rolling bearing according to configuration 1 or 2, wherein the insulating coating has a withstand voltage of 200V or more and an insulating resistance value of 1MΩ or more.

[0017] Adopting this configuration makes it possible to effectively prevent electrolytic corrosion from occurring on the outer ring, inner ring, and rolling elements when used as an insulated rolling bearing to support the rotating shaft of an electric motor for electric vehicle propulsion or the reduction gear of that electric motor.

[0018] In addition, in this invention, as a method for manufacturing the above-described insulating rolling bearing, the following configurations are also provided. [Configuration 4] A rolling bearing having an outer ring, an inner ring disposed radially inside the outer ring, and a plurality of rolling elements incorporated between the outer ring and the inner ring, wherein the outer ring has a cylindrical outer peripheral surface with a constant outer diameter along the axial direction, a pair of chamfered portions having a cross-sectional arc shape whose outer diameter gradually decreases from the outer peripheral surface toward the outer side in the axial direction, and a pair of axial end surfaces extending radially inward from the pair of chamfered portions; a bearing preparation step of preparing a rolling bearing; A heat shrink tube arrangement step of disposing a resin heat shrink tube having an inner diameter of 103% or less of the outer diameter of the outer ring on the radially outer side of the rolling bearing; A heat shrink tube heating step of forming an insulating coating having a cylindrical outer peripheral coating portion covering the outer peripheral surface of the outer ring, a pair of chamfered coating portions having a cross-sectional arc shape covering the pair of chamfered portions of the outer ring, and a pair of end surface coating portions covering the pair of axial end surfaces of the outer ring by heating and deforming the heat shrink tube after the heat shrink tube arrangement step. A method for manufacturing an insulating rolling bearing.

[0019] [Configuration 5] In the heat shrink tube arrangement step, a method for manufacturing an insulating rolling bearing according to Configuration 4, wherein a heat shrink tube having an inner diameter of less than 100% of the outer diameter of the outer ring is used as the heat shrink tube, and the heat shrink tube is fitted onto the outer peripheral surface of the outer ring with an interference fit.

[0020] When this configuration is adopted, when the insulating rolling bearing is used under high temperature conditions, it is possible to particularly effectively prevent the portion on the load side of the insulating coating from being compressed in the thickness direction and extending in the circumferential direction, and it is possible to surely prevent the occurrence of wrinkles in the portion on the non-load side of the insulating coating.

[0021] [Configuration 6] In the heat shrink tube arrangement step, a method for manufacturing an insulating rolling bearing according to Configuration 4 or 5, wherein a heat shrink tube having a radial shrinkage rate X satisfying (φD0 - φD1) / φD0 < X is used as the heat shrink tube. Here, φD0 is the inner diameter of the heat shrink tube 10 before shrinking, and φD1 is the inner diameter of the outer ring.

[0022] By adopting this configuration, it becomes possible to reliably cover the axial end face of the outer ring with heat shrink tubing during the heat shrink tubing heating process.

[0023] [Composition 7] A method for manufacturing an insulated rolling bearing according to any one of configurations 4 to 6, wherein in the heat shrink tube heating step, the portion of the heat shrink tube corresponding to the end face covering portion is pressed against the pair of axial end faces of the outer ring with a pair of jigs positioned axially opposite to the pair of axial end faces of the outer ring.

[0024] By adopting this configuration, it becomes possible to make the end face covering portion of the insulating coating closely adhere to the axial end face of the outer ring.

[0025] [Structure 8] The method for manufacturing an insulated rolling bearing according to configuration 7, wherein the pair of jigs has a surface that contacts the heat shrinkable tube formed of an elastomer or rubber material.

[0026] By adopting this configuration, the surface of the jig that comes into contact with the heat-shrinkable tube is made of elastomer or rubber material. This prevents damage to the end-face coating of the heat-shrinkable tube from occurring when the jig presses down on the corresponding portion of the tube, thus ensuring the insulating performance of the end-face coating. [Effects of the Invention]

[0027] The insulated rolling bearing of this invention can form an insulating coating by placing a heat-shrinkable tube radially outside the outer ring and heating and deforming the heat-shrinkable tube, thus eliminating the need for large-scale equipment such as insert molding to provide an insulating coating to the outer ring. Therefore, it is possible to reduce the manufacturing cost of the insulated rolling bearing. Furthermore, since the insulating coating uses a heat-shrinkable tube with an inner diameter of 103% or less of the outer diameter of the outer ring (i.e., a heat-shrinkable tube with an inner diameter the same as or close to the outer diameter of the outer ring) that has been heated and deformed, when the insulated rolling bearing is used under high temperature conditions, it is possible to prevent the load-side portion of the insulating coating from being compressed in the thickness direction and stretching in the circumferential direction, and to prevent the occurrence of wrinkles on the non-load-side portion of the insulating coating. [Brief explanation of the drawing]

[0028] [Figure 1] Cross-sectional view showing an insulated rolling bearing according to an embodiment of this invention. [Figure 2] Cross-sectional view along line II-II in Figure 1 [Figure 3] Flowchart showing the manufacturing method of the insulated rolling bearing shown in Figure 1. [Figure 4] Figure 2 illustrates the manufacturing method of an insulated rolling bearing, showing the state in which the heat-shrinkable tubing is placed radially outward on the outer circumference of the outer ring before shrinking. [Figure 5] Figure 4 shows the state after the heat shrink tubing has been heated and shrunk. [Figure 6] Figure 5 shows the heat shrink tubing with a pair of jigs clamping the portion along the axial end face of the outer ring in the axial direction. [Figure 7] Figure 2 shows an example of the usage state of an insulated rolling bearing. [Figure 8] This diagram shows the state of an insulated rolling bearing, a reference example, after being assembled with the inner ring in an interference fit and the outer ring in a clearance fit, and subjected to a durability test at a temperature of 80°C. [Figure 9] Figure 8 shows a magnified view of the non-load side portion of the insulating coating. [Modes for carrying out the invention]

[0029] Figure 1 shows an insulated rolling bearing according to an embodiment of the present invention. This insulated rolling bearing comprises an outer ring 1, an inner ring 2 coaxially arranged radially inward of the outer ring 1, a plurality of rolling elements 3 assembled between the outer ring 1 and the inner ring 2 at circumferential intervals, an annular cage 4 that maintains the circumferential intervals of the plurality of rolling elements 3, and a resin insulating coating 5 provided on the outer ring 1.

[0030] The axial direction is parallel to the central axis of the outer ring 1 (the central axis of the bearing), the radial direction is perpendicular to the central axis of the outer ring 1, and the circumferential direction is along the circumference that revolves around the central axis of the outer ring 1. The outer ring 1 and inner ring 2 are formed symmetrically with respect to the axial center. Furthermore, the axial inner side is the side of the outer ring 1 and inner ring 2 that approaches the axial center along the axial direction, and the axial outer side is the side of the outer ring 1 and inner ring 2 that moves away from the axial center along the axial direction.

[0031] As shown in Figure 2, the rolling element 3 is radially sandwiched between the outer ring raceway groove 6 formed on the inner circumference of the outer ring 1 and the inner ring raceway groove 7 formed on the outer circumference of the inner ring 2. The rolling element 3 is a ball in this case. The outer ring raceway groove 6 and the inner ring raceway groove 7 are grooves with an arc-shaped cross-section perpendicular to the circumferential direction. The outer ring 1, inner ring 2, and rolling element 3 are each made of steel.

[0032] The outer ring 1 has a cylindrical outer surface 1a with a constant outer diameter that does not change along the axial direction, a pair of chamfered portions 1b with a cross-sectional arc shape whose outer diameter gradually decreases axially outward from the outer surface 1a, and a pair of axial end faces 1c extending radially inward from the pair of chamfered portions 1b. The axial end faces 1c are planes perpendicular to the axial direction.

[0033] Here, the outer diameter φD (see Figure 4) of the outer circumferential surface 1a of the outer ring 1 is set to 45 mm or more and 110 mm or less, and the axial width dimension of the outer ring 1 is set to 9 mm or more and 30 mm or less. In addition, the surface roughness of the outer circumferential surface 1a of the outer ring 1 along the axial direction is set to Ra 0.05 μm or more and 1.6 μm or less (preferably Ra 0.25 μm or more and 1.0 μm or less). The chamfered portion 1b of the outer ring 1 is an arc-shaped surface whose cross-section perpendicular to the circumferential direction smoothly connects to the outer circumferential surface 1a of the outer ring 1, and its arc radius R (see Figure 4) is set to 0.3 mm or more (preferably 0.5 mm or more) and 4.0 mm or less. Here, the arc radius R of the chamfered portion 1b is at least twice the thickness of the chamfered covering portion 5b described later.

[0034] The insulating coating 5 has a cylindrical outer circumferential coating portion 5a that covers the outer circumferential surface 1a of the outer ring 1, a pair of chamfered coating portions 5b with a circular arc cross-section that cover a pair of chamfered portions 1b of the outer ring 1, and a pair of end-face coating portions 5c that cover a pair of axial end faces 1c of the outer ring 1. The pair of chamfered coating portions 5b are formed in conjunction with both axial ends of the outer circumferential coating portion 5a, and the pair of end-face coating portions 5c are formed in conjunction with the radially inner ends of the pair of chamfered coating portions 5b. It is preferable that the end-face coating portions 5c are provided in close contact with the axial end faces 1c of the outer ring 1, but they may also be provided in a state where they are lifted away from the axial end faces 1c of the outer ring 1 (a state where there is a gap between the axial end faces 1c of the outer ring 1 and the end-face coating portions 5c).

[0035] The insulating coating 5 is configured to have a thickness such that the outer periphery coating portion 5a (i.e., the thinnest part of the outer periphery coating portion 5a, the chamfered coating portion 5b, and the end face coating portion 5c) has a withstand voltage of 200V or more and an insulation resistance value of 1MΩ or more. This insulating coating 5 is formed from a heat-shrinkable resin tube 10 that shrinks when heated, as will be described later.

[0036] An example of the manufacturing method for this insulated rolling bearing will be explained following the flowchart shown in Figure 3.

[0037] [Bearing preparation process] Prepare the rolling bearing 9 shown in FIG. 4. This rolling bearing 9 incorporates a plurality of rolling elements 3 between an outer ring 1 and an inner ring 2, and does not have the insulating coating 5 shown in FIG. 2.

[0038] [Heat shrink tube placement process] After the above bearing preparation process, as shown in FIG. 4, place a resin heat shrink tube 10 on the radially outer side of the rolling bearing 9.

[0039] As the heat shrink tube 10, for example, a resin material such as a polyolefin resin, a polyvinyl chloride resin, or a fluororesin is formed into a tube shape, irradiated with radiation to crosslink the resin material, and then stretched in the radial direction (or the radial direction and the axial direction) in a state of being heated to a predetermined high temperature and cooled. In this case, the dimensions of the tube after stretching correspond to the dimensions of the heat shrink tube 10 before shrinking by heating.

[0040] The heat shrink tube 10 used has an inner diameter φD0 that is 100% or more and 103% or less of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1. Here, in order to facilitate the operation of placing the heat shrink tube 10 outside the outer ring 1, a heat shrink tube 10 having an inner diameter φD0 that is 100% or more of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1 is used. However, a heat shrink tube 10 having an inner diameter φD0 that is less than 100% of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1 may be used, and the heat shrink tube 10 may be fitted to the outer peripheral surface 1a of the outer ring 1 with an interference fit.

[0041] Also, it is preferable to use a heat shrink tube having a radial shrinkage rate X that satisfies (φD0 - φD1) / φD0 < X so that the axial end face 1c of the outer ring 1 can be surely covered with the heat shrink tube 10 in the heat shrink tube heating process described later. Here, the radial shrinkage rate X is the ratio of the decrease amount of the inner diameter of the heat shrink tube 10 when the heat shrink tube 10 is completely shrunk to the inner diameter φD0 of the heat shrink tube 10 before heating and shrinking, and φD1 is the inner diameter of the outer ring 1.

[0042] Furthermore, the axial length W of the heat shrink tube 10 is set to be at least 1.6 times the axial width dimension of the outer ring 1 (the distance between the pair of axial end faces 1c) so that the axial end faces 1c of the outer ring 1 can be reliably covered with the heat shrink tube 10 during the heat shrink tube heating process described later. The thickness t of the heat shrink tube 10 is set to be 1 / 2 or less of the arc radius R of the chamfered portion 1b.

[0043] [Heat shrink tube heating process] After the heat shrink tubing placement process described above, the heat shrink tubing 10 is heated and deformed to form an insulating coating 5, as shown in Figure 2, which has a cylindrical outer peripheral coating portion 5a that covers the outer peripheral surface 1a of the outer ring 1, a pair of chamfered coating portions 5b with a circular arc cross-section that cover a pair of chamfered portions 1b of the outer ring 1, and a pair of end-face coating portions 5c that cover a pair of axial end faces 1c of the outer ring 1. As a method for heating the heat shrink tubing 10, a method of blowing hot air onto the outer circumference of the heat shrink tubing 10 with a heating gun or the like can be used, or a method of passing the rolling bearing 9 and the heat shrink tubing 10, which is positioned radially outside of it, through a heating furnace while being supported by a support. The heating temperature of the heat shrink tubing 10 can be set in the range of 80°C to 170°C.

[0044] Here, when the heat shrink tubing 10 is heated, depending on the shrinkage characteristics of the heat shrink tubing 10, the portion of the heat shrink tubing 10 corresponding to the end face covering portion 5c (see Figure 2) may not adhere closely to the axial end face 1c of the outer ring 1, as shown in Figure 5, and may lift away from the axial end face 1c. Therefore, as shown in Figure 6, it is preferable to use a pair of jigs 11, positioned axially opposite to the pair of axial end faces 1c of the outer ring 1, to press the portion of the heat shrink tubing 10 corresponding to the end face covering portion 5c (see Figure 2) against the pair of axial end faces 1c of the outer ring 1 while the heat shrink tubing 10 is still heated. In this way, as shown in Figure 2, it is possible to ensure that the end face covering portion 5c of the insulating coating 5 adheres securely to the axial end face 1c of the outer ring 1.

[0045] In Figure 6, the surfaces of the pair of jigs 11 that come into contact with the heat-shrinkable tube 10 can be made of elastomer or rubber material. This prevents damage to the end-face coating portion 5c (see Figure 2) of the heat-shrinkable tube 10 from contact with the jig 11 when the jig 11 shown in Figure 6 presses down on the end-face coating portion 5c, ensuring the insulating performance of the end-face coating portion 5c. It is preferable to use an elastomer or rubber material that has a heat resistance of 100°C or higher.

[0046] As shown in Figure 7, the insulated rolling bearing of this embodiment can be used as a rolling bearing to support the rotating shaft 12 of an electrical device (such as the rotating shaft of an electric motor, the rotating shaft of a speed reducer that reduces the rotation of an electric motor, or the rotating shaft of an alternator). In Figure 7, the insulated rolling bearing is assembled between the cylindrical inner circumference of a housing hole 14 formed in a non-rotating housing 13 and the outer circumference of the rotating shaft 12 located at the center of the housing hole 14. Here, the inner ring 2 is the rotating side and the outer ring 1 is the non-rotating side, so the insulated rolling bearing is assembled so that the inner ring 2 is fitted to the outer circumference of the rotating shaft 12 in an interference fit, and the outer ring 1 is fitted to the inner circumference of the housing hole 14 in a clearance fit. Furthermore, when using insulated rolling bearings under high temperature conditions, such as 80°C (temperature conditions expected when supporting the rotating shaft of an electric motor in an electric vehicle or the rotating shaft of the reduction gear of that electric motor with an insulated rolling bearing), there is a problem that wrinkles may occur in the insulating coating 5 in the non-loaded region located on the opposite side (upper side in the figure) from the side where the radial load is applied (lower side in the figure), as shown in Figures 8 and 9. If these wrinkles occur, there is a risk of misalignment (eccentricity) of the center of the insulated rolling bearing.

[0047] To address this problem, the insulated rolling bearing of this embodiment uses a heat-shrinkable tube 10 with an inner diameter φD0 that is 103% or less of the outer diameter φD of the outer ring 1 (i.e., a heat-shrinkable tube 10 with an inner diameter φD0 that is the same as or close to the outer diameter φD of the outer ring 1) as the insulating coating 5 shown in Figure 2, which is then heated and deformed, as shown in Figure 4. Therefore, when the insulated rolling bearing is used under high temperature conditions such as 80°C, the load-side portion of the insulating coating 5 is prevented from being compressed in the thickness direction and stretched in the circumferential direction, and wrinkles are prevented from forming on the non-load-side portion of the insulating coating 5.

[0048] In particular, by using a heat-shrinkable tube 10 as shown in Figure 4, having an inner diameter φD0 that is less than 100% of the outer diameter φD of the outer ring 1, fitting the heat-shrinkable tube 10 to the outer circumferential surface 1a of the outer ring 1 with an overlap, and then heating and deforming the heat-shrinkable tube 10 to form the insulating coating 5 shown in Figure 2, it is possible to particularly effectively prevent the load-side portion of the insulating coating 5 from being compressed in the thickness direction and stretching in the circumferential direction when using an insulated rolling bearing under high temperature conditions, and to reliably prevent the occurrence of wrinkles on the non-load-side portion of the insulating coating 5.

[0049] Furthermore, as shown in Figure 4, this insulated rolling bearing can be manufactured by placing a heat-shrinkable tube 10 radially outside the outer ring 1 and heating and deforming the heat-shrinkable tube 10 to form the insulating coating 5. This eliminates the need for large-scale equipment, such as when the insulating coating 5 is applied to the outer ring 1 by insert molding. Therefore, it is possible to reduce the manufacturing cost of the insulated rolling bearing.

[0050] Furthermore, since the insulating coating 5 of this insulated rolling bearing has a withstand voltage of 200V or more and an insulating resistance of 1MΩ or more, it is possible to effectively prevent electrolytic corrosion from occurring on the outer ring 1, inner ring 2, and rolling elements 3 when used as an insulated rolling bearing to support the rotating shaft 12 of the electric motor or the reduction gear of the electric motor for driving an electric vehicle.

[0051] In the above embodiment, as shown in Figure 2, the axial width dimension of the outer ring 1 and the axial width dimension of the inner ring 2 are the same (that is, the axial end face 1c of the outer ring 1 and the axial end face 2c of the inner ring 2 are at the same axial position). However, it is also possible to set the axial width dimension of the outer ring 1 to be smaller than the axial width dimension of the inner ring 2 so that the surface of the end face covering portion 5c of the insulating coating 5 is at the same axial position as the axial end face 2c of the inner ring 2.

[0052] Furthermore, although the above embodiment described an example in which balls are used as the rolling elements 3, other shapes of rolling elements 3, such as cylindrical rollers, may also be used.

[0053] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0054] 1 Outer ring 1a Outer surface 1b Chamfered section 1c Axial end face 2 Inner ring 3 Rolling element 5. Insulating coating 5a Outer sheathing part 5b Chamfered coating 5c End covering part 9 Rolling bearings 10 Heat shrink tubing 11. Jig φD Outer diameter φD0 inner diameter R is the radius of the circular arc.

Claims

1. Outer ring (1) and, An inner ring (2) is positioned radially inward of the outer ring (1), A plurality of rolling elements (3) are incorporated between the outer ring (1) and the inner ring (2), The outer ring (1) is covered by a resin insulating coating (5), In an insulated rolling bearing in which the insulating coating (5) is formed of a heat-shrinkable tube (10) that shrinks when heated, The outer ring (1) has a cylindrical outer surface (1a) with a constant outer diameter along the axial direction, a pair of chamfered portions (1b) with a circular arc cross-section whose outer diameter gradually decreases axially outward from the outer surface (1a), and a pair of axial end faces (1c) extending radially inward from the pair of chamfered portions (1b). The insulating coating (5) has a cylindrical outer peripheral coating portion (5a) that covers the outer peripheral surface (1a) of the outer ring (1), a pair of chamfered coating portions (5b) with a circular arc cross-section that cover the pair of chamfered portions (1b) of the outer ring (1), and a pair of end face coating portions (5c) that cover the pair of axial end faces (1c) of the outer ring (1). The insulating coating (5) has an inner diameter (φD) that is 103% or less of the outer diameter (φD) of the outer ring (1). ０ An insulated rolling bearing characterized by being made by heating and deforming the heat shrinkable tube (10) having ).

2. The insulating rolling bearing according to claim 1, wherein the arc radius (R) of the chamfered portion (1b) of the outer ring (1) is at least twice the thickness of the chamfered covering portion (5b).

3. The insulating rolling bearing according to claim 1 or 2, wherein the insulating coating (5) has a withstand voltage of 200V or more and an insulating resistance of 1MΩ or more.

4. A bearing preparation step to prepare a rolling bearing (9) having an outer ring (1), an inner ring (2) arranged radially inward of the outer ring (1), and a plurality of rolling elements (3) incorporated between the outer ring (1) and the inner ring (2), wherein the outer ring (1) has a cylindrical outer surface (1a) with a constant outer diameter along the axial direction, a pair of chamfered portions (1b) with a cross-sectional arc shape whose outer diameter gradually decreases axially outward from the outer surface (1a), and a pair of axial end faces (1c) extending radially inward from the pair of chamfered portions (1b), On the radially outer side of the rolling bearing (9), an inner diameter (φD) of the outer ring (1) is provided, with a size of 103% or less of the outer diameter (φD). ０ A heat shrink tube placement step involves arranging a resin heat shrink tube (10) having the following properties: A method for manufacturing an insulated rolling bearing, comprising a heat shrink tube heating step, after the heat shrink tube placement step, by heating and deforming the heat shrink tube (10) to form an insulating coating (5) having a cylindrical outer peripheral covering portion (5a) that covers the outer peripheral surface (1a) of the outer ring (1), a pair of chamfered covering portions (5b) with a circular arc cross-section that cover the pair of chamfered portions (1b) of the outer ring (1), and a pair of end face covering portions (5c) that cover the pair of axial end faces (1c) of the outer ring (1).

5. In the heat shrink tube placement step, the heat shrink tube (10) has an inner diameter (φD) that is less than 100% of the outer diameter (φD) of the outer ring (1). ０ A method for manufacturing an insulated rolling bearing according to claim 4, wherein a heat shrink tube (10) having a heat shrink tube (10) is fitted to the outer circumferential surface (1a) of the outer ring (1) with an overlap.

6. In the heat shrink tube placement step, the heat shrink tube (10) is (φD ０ -φD １ ) / φD ０ A method for manufacturing an insulated rolling bearing according to claim 4 or 5, using a bearing having a radial shrinkage rate (X) that satisfies X. Here, φD ０ This is the inner diameter of the heat shrink tube (10) before shrinkage, and φD １ This is the inner diameter of the outer ring (1).

7. A method for manufacturing an insulated rolling bearing according to claim 4 or 5, wherein in the heat shrink tube heating step, the portion of the heat shrink tube (10) corresponding to the end face covering portion (5c) is pressed against the pair of axial end faces (1c) of the outer ring (1) by a pair of jigs (11) positioned axially opposite to the pair of axial end faces (1c) of the outer ring (1).

8. The method for manufacturing an insulated rolling bearing according to claim 7, wherein the pair of jigs (11) have surfaces that come into contact with the heat shrinkable tube (10) formed of elastomer or rubber material.

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