Insulated rolling bearing and method for manufacturing insulated rolling bearing

Abstract

An insulating coating (5) is obtained by heating and deforming a heat-shrinkable tube (10) having an inner diameter φD0 that is at most 103% the size of the outer diameter φD of an outer ring (1).

Description

Insulated rolling bearing and method for manufacturing the insulated rolling bearing

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

[0002] In rolling bearings that support the rotating shaft of electrical devices such as electric motors and alternators (generators), when an electric current flows inside the bearing, sparks can occur between the outer or inner ring and the rolling elements, causing localized melting of the surfaces of the outer or inner ring or the rolling elements (galvanic corrosion).Insulated rolling bearings in which an insulating coating is provided on the outer ring are known as rolling bearings that can prevent this galvanic corrosion (see, for example, Patent Document 1).

[0003] The insulating rolling bearing of Patent Document 1 has an outer ring, an inner ring arranged radially inward of the outer ring, a plurality of rolling elements installed 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 (i.e., a method of molding the insulating coating by injecting molten resin into a cavity inside a mold with the outer ring set inside the mold).

[0004] When providing an insulating resin coating on an outer ring, the insulating coating is typically formed by insert molding, as in Patent Document 1. However, forming an insulating coating by insert molding requires large-scale equipment and molds, which increases the manufacturing costs of the insulated rolling bearing.

[0005] Therefore, in order to reduce the manufacturing costs of insulating rolling bearings, Patent Document 2 proposes an insulating rolling bearing in which an insulating coating is provided by a method other than insert molding.

[0006] The insulating rolling bearing of Patent Document 2 has a heat-shrinkable tube with an inner diameter that is 1.05 to 1.15 times the outer diameter of the outer ring positioned radially outside the outer ring, and the heat-shrinkable tube is heated to shrink it, forming a resin insulating coating that covers the outer peripheral surface and a pair of axial end faces of the outer ring.

[0007] JP 2023-15667 A JP 2001-107974 A

[0008] Incidentally, the inventors of the present application fabricated a sample 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 on the radially outside of the outer ring and heating and shrinking the heat-shrinkable tube, in accordance with the description in Patent Document 2. When endurance tests were conducted on this insulated rolling bearing, it was found that there was a risk of wrinkles occurring in the non-load side portion of the insulating coating of the outer ring.

[0009] 8 , the inventors prepared a rolling bearing incorporating a plurality of rolling elements 23 between an outer ring 21 and an inner ring 22, arranged a heat-shrinkable tube with an inner diameter 1.05 to 1.15 times the outer diameter of the outer ring 21 on the radial outside of the rolling bearing, and heated the heat-shrinkable tube to shrink it, thereby forming an insulating coating 24 covering the outer peripheral surface and axial end face of the outer ring 21. Next, the insulated rolling bearing was assembled to the inner periphery of a housing 25, and a rotating shaft 26 (such as a rotating shaft of an electric motor or alternator) was supported thereon. Here, when the rotating shaft 26 of an electric motor, alternator, or the like is supported by the 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 onto the outer periphery of the rotating shaft 26 with an interference fit, and the outer ring 21 was fitted onto the inner periphery of the housing 25 with a loose fit. Then, an endurance test was conducted in which rotating shaft 26 was continuously rotated at a temperature of 80°C (temperature conditions expected when the rotating shaft of an electric motor for an electric vehicle or the rotating shaft of a reducer for that electric motor is supported by an insulated rolling bearing) with a radial load applied in a fixed direction between rotating shaft 26 and housing 25. As a result, wrinkles were found to have occurred in insulating coating 24 in the anti-load region located on the opposite side (upper side in the figures) from the side where the radial load is applied (lower side in the figures), as shown in Figures 8 and 9. The occurrence of wrinkles could cause the center of the insulated rolling bearing to become misaligned (eccentric).

[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-shrinkable tube has the property of being easily deformed in response to an external force when heated again, and as a result, during the durability test described above, the load-side portion of the insulating coating 24 (the lower side in the figure) was compressed in the thickness direction and stretched circumferentially, and this circumferential stretch is thought to have caused wrinkles to form in the anti-load side portion of the insulating coating 24 (the upper side in the figure).

[0011] The present inventors then studied how to prevent the occurrence of the aforementioned wrinkles. As a result of their investigation, they noticed that although the insulating coating 24 formed by heating and shrinking a heat-shrinkable tube is prone to deformation in response to an external force when subsequently heated again, this deformation only occurs within the range of the heat-shrinkable tube's dimensions before shrinkage and is unlikely to deform beyond the dimensions before shrinkage. They then came up with the idea that, rather than forming the insulating coating 24 using a heat-shrinkable tube with an inner diameter 1.05 to 1.15 times the outer diameter of the outer ring 21 as in Patent Document 2, forming the insulating coating 24 using a heat-shrinkable tube with an inner diameter equal to or close to the outer diameter of the outer ring 21 would make it possible to prevent the occurrence of wrinkles in the anti-load side portion of the insulating coating 24 even when the insulated rolling bearing is used under high-temperature conditions, such as at 80°C.

[0012] The problem to be solved by the present invention is to provide an insulating rolling bearing that can be manufactured at low cost and that can prevent wrinkles from occurring in the portion of the insulating coating on the anti-load side.

[0013] In order to solve the above problems, the present invention provides an insulating rolling bearing having the following configuration. and a resin insulating coating covering the outer ring, wherein the insulating coating is formed of heat-shrinkable tubing that shrinks when heated, wherein the outer ring has a cylindrical outer peripheral surface with a constant outer diameter along the axial direction, a pair of chamfered portions with an arc-shaped cross section that gradually reduces in outer diameter from the outer peripheral surface toward the axially outward, and a pair of axial end faces extending radially inward from the pair of chamfered portions, the insulating coating having a cylindrical outer peripheral covering portion covering the outer peripheral surface of the outer ring, a pair of chamfered covering portions with an arc-shaped cross section that cover the pair of chamfered portions of the outer ring, and a pair of end face covering portions that cover the pair of axial end faces of the outer ring, and the insulating coating is formed by heating and deforming the heat-shrinkable tubing, which has an inner diameter that is 103% or less of the outer diameter of the outer ring.

[0014] With this configuration, the insulating coating can be formed by placing a heat-shrinkable tube radially outside the outer ring and heating and deforming the heat-shrinkable tube, eliminating the need for large-scale equipment as is required when providing an insulating coating on the outer ring by insert molding. This reduces the manufacturing costs of the insulated rolling bearing. Furthermore, because the insulating coating is made of a heat-shrinkable tube with an inner diameter that is 103% or less of the outer diameter of the outer ring (i.e., a heat-shrinkable tube with an inner diameter that is the same as or close to the outer diameter of the outer ring), the load-side portion of the insulating coating can be prevented from being compressed in the thickness direction and stretching in the circumferential direction when the insulated rolling bearing is used under high-temperature conditions, and this prevents wrinkles from forming in 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 200 V or more and an insulation resistance of 1 MΩ or more.

[0017] By adopting this configuration, when the bearing is used as an insulated rolling bearing supporting the rotating shaft of an electric motor for driving an electric vehicle or the reduction gear of that electric motor, it becomes possible to effectively prevent electrolytic corrosion from occurring in the outer ring, inner ring, and rolling elements.

[0018] The present invention also provides a method for manufacturing the above-mentioned insulating rolling bearing, which has the following configuration. [Configuration 4] A method for manufacturing an insulated rolling bearing, comprising: a bearing preparation step of preparing a rolling bearing having an outer ring, an inner ring arranged radially inward of the outer ring, and a plurality of rolling elements fitted between the outer ring and the inner ring, the outer ring having a cylindrical outer peripheral surface with a constant outer diameter along the axial direction, a pair of chamfered portions with an arc-shaped cross section that gradually decreases in outer diameter from the outer peripheral surface outward in the axial direction, and a pair of axial end faces extending radially inward from the pair of chamfered portions; a heat-shrinkable tube arrangement step of arranging a resin heat-shrinkable tube with an inner diameter that is 103% or less of the outer diameter of the outer ring radially outward of the rolling bearing; and a heat-shrinkable tube heating step of heating and deforming the heat-shrinkable tube after the heat-shrinkable tube arrangement step to form an insulating coating having a cylindrical outer peripheral covering portion that covers the outer peripheral surface of the outer ring, a pair of chamfered covering portions with an arc-shaped cross section that cover the pair of chamfered portions of the outer ring, and a pair of end face covering portions that cover the pair of axial end faces of the outer ring.

[0019] [Configuration 5] A method for manufacturing an insulating rolling bearing according to Configuration 4, wherein in the heat-shrinkable tube arrangement step, the heat-shrinkable tube has an inner diameter that is less than 100% of the outer diameter of the outer ring, and the heat-shrinkable tube is fitted onto the outer peripheral surface of the outer ring with an interference fit.

[0020] By adopting this configuration, when the insulated rolling bearing is used under high temperature conditions, it is possible to particularly effectively prevent the load-side portion of the insulating coating from being compressed in the thickness direction and stretching in the circumferential direction, thereby reliably preventing wrinkles from occurring in the anti-load-side portion of the insulating coating.

[0021] [Configuration 6] In the heat shrink tube arrangement step, the heat shrink tube is ０ -φD １ ) / φD０ <A method for manufacturing an insulating rolling bearing according to configuration 4 or 5, wherein a material having a radial shrinkage rate X satisfying X is used. ０ is the inner diameter of the heat shrinkable tube 10 before shrinkage, and φD １ is the inner diameter of the outer ring.

[0022] By adopting this configuration, it is possible to reliably cover the axial end face of the outer ring with the heat-shrinkable tube in the heat-shrinkable tube heating step.

[0023] [Configuration 7] A method for manufacturing an electrically insulating rolling bearing according to any one of Configurations 4 to 6, wherein, in the heat-shrinkable tube heating step, portions of the heat-shrinkable tube corresponding to the end face covering portions are pressed against the pair of axial end faces of the outer ring by a pair of jigs arranged axially opposite the pair of axial end faces of the outer ring.

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

[0025] [Configuration 8] The method for manufacturing an insulating rolling bearing according to Configuration 7, wherein the pair of jigs have surfaces that come into contact with the heat-shrinkable tube formed from an elastomer or rubber material.

[0026] When this configuration is adopted, the surface of the jig that comes into contact with the heat-shrinkable tube is formed from an elastomer or rubber material, so that when the jig presses down on the part of the heat-shrinkable tube that corresponds to the end face covering, it is possible to prevent the end face covering from being damaged by contact with the jig, and it is possible to ensure the insulating performance of the end face covering.

[0027] In the insulated rolling bearing of this invention, the insulating coating can be formed by placing a heat-shrinkable tube radially outside the outer ring and heating and deforming the heat-shrinkable tube, eliminating the need for large-scale equipment as is required when providing an insulating coating on the outer ring by insert molding. This reduces the manufacturing costs of the insulated rolling bearing. Furthermore, the insulating coating is made by heating and deforming a heat-shrinkable tube with an inner diameter that is 103% or less of the outer diameter of the outer ring (i.e., a heat-shrinkable tube with an inner diameter that is the same as or close to the outer diameter of the outer ring). This prevents the load-side portion of the insulating coating from being compressed in the thickness direction and stretching in the circumferential direction when the insulated rolling bearing is used under high-temperature conditions, making it possible to prevent wrinkles from forming in the non-load-side portion of the insulating coating.

[0028] 5 is a diagram showing a state in which a portion of the heat shrinkable tube along the axial end face of the outer ring is clamped in the axial direction between a pair of jigs; FIG. 6 is a diagram showing an example of a usage state of the insulated rolling bearing shown in FIG. 2; FIG. 7 is a diagram showing an insulated rolling bearing according to an embodiment of the present invention;

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

[0030] The axial direction is the direction parallel to the central axis of the outer ring 1 (the central axis of the bearing), the radial direction is the direction perpendicular to the central axis of the outer ring 1, and the circumferential direction is the direction along the circumference that goes 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 axially inner side is the side that approaches the axial center of the outer ring 1 and inner ring 2 along the axial direction, and the axially outer side is the side that moves away from the axial center of the outer ring 1 and inner ring 2 along the axial direction.

[0031] As shown in Figure 2, the rolling elements 3 are sandwiched radially between an outer ring raceway groove 6 formed on the inner circumference of the outer ring 1 and an inner ring raceway groove 7 formed on the outer circumference of the inner ring 2. In this example, the rolling elements 3 are balls. The outer ring raceway groove 6 and the inner ring raceway groove 7 are grooves whose cross sections perpendicular to the circumferential direction are arc-shaped. The outer ring 1, inner ring 2, and rolling elements 3 are each made of steel.

[0032] The outer ring 1 has a cylindrical outer peripheral surface 1a with a constant outer diameter along the axial direction, a pair of chamfered portions 1b with an arc-shaped cross section whose outer diameter gradually decreases axially outward from the outer peripheral 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 flat surfaces perpendicular to the axial direction.

[0033] Here, the outer diameter φD (see FIG. 4) of the outer peripheral surface 1a of the outer ring 1 is set to be no less than 45 mm and no more than 110 mm, and the axial width dimension of the outer ring 1 is set to be no less than 9 mm and no more than 30 mm. The surface roughness along the axial direction of the outer peripheral surface 1a of the outer ring 1 is set to be no less than 0.05 μm and no more than 1.6 μm (preferably no less than 0.25 μm and no more than 1.0 μm). The chamfered portion 1b of the outer ring 1 has an arc-shaped surface in a cross section perpendicular to the circumferential direction that smoothly connects to the outer peripheral surface 1a of the outer ring 1, and the arc radius R (see FIG. 4) is set to be no less than 0.3 mm (preferably no less than 0.5 mm) and no more than 4.0 mm. Here, the arc radius R of the chamfered portion 1b is at least twice the thickness of the chamfered covering portion 5b, described below.

[0034] The insulating coating 5 comprises a cylindrical outer peripheral covering portion 5a covering the outer peripheral surface 1a of the outer ring 1, a pair of chamfered covering portions 5b with an arc-shaped cross section covering the pair of chamfered portions 1b of the outer ring 1, and a pair of end face covering portions 5c covering the pair of axial end faces 1c of the outer ring 1. The pair of chamfered covering portions 5b are formed to be continuous with both axial ends of the outer peripheral covering portion 5a, and the pair of end face covering portions 5c are formed to be continuous with the radial inner ends of the pair of chamfered covering portions 5b. The end face covering portions 5c are preferably provided in close contact with the axial end face 1c of the outer ring 1, but may also be provided in a state where they are raised above the axial end face 1c of the outer ring 1 (a state where there is a gap between the axial end face 1c of the outer ring 1 and the end face covering portions 5c).

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

[0036] An example of a method for manufacturing this insulating rolling bearing will be described with reference to the flow chart shown in FIG.

[0037] [Bearing Preparation Step] A rolling bearing 9 shown in Fig. 4 is prepared. This rolling bearing 9 has a plurality of rolling elements 3 assembled between an outer ring 1 and an inner ring 2, and is not provided with the insulating coating 5 shown in Fig. 2.

[0038] [Heat-Shrink Tube Arrangement Step] After the above-described bearing preparation step, a resin heat-shrink tube 10 is arranged on the radially outer side of the rolling bearing 9, as shown in FIG.

[0039] The heat-shrinkable tube 10 may be made by irradiating a resin material, such as polyolefin resin, polyvinyl chloride resin, or fluororesin, molded into a tube shape with radiation to crosslink the resin material, and then heating the tube to a predetermined high temperature and stretching it in the radial direction (or in the radial and axial directions), followed by cooling. In this case, the dimensions of the tube after stretching correspond to the dimensions of the heat-shrinkable tube 10 before shrinking due to heating.

[0040] The heat-shrinkable tube 10 has an inner diameter φD of 100% to 103% of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1. ０ In this case, in order to facilitate the work of arranging the heat shrinkable tube 10 on the outside of the outer ring 1, the inner diameter φD is set to 100% or more of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1. ０ The heat shrinkable tube 10 used had an inner diameter φD less than 100% of the outer diameter φD of the outer peripheral surface 1a of the outer ring 1. ０ Alternatively, a heat-shrinkable tube 10 having the above-mentioned shape may be used, and the heat-shrinkable tube 10 may be fitted onto the outer peripheral surface 1a of the outer ring 1 with an interference fit.

[0041] In addition, the shrinkable tube is formed to have a diameter (φD ０ -φD １ ) / φD ０ It is preferable to use a material having a radial shrinkage rate X that satisfies the condition: <X. Here, the radial shrinkage rate X is the inner diameter φD of the heat-shrinkable tube 10 before it is heated and shrunk. ０ is the ratio of the reduction in the inner diameter of the heat-shrinkable tube 10 when the heat-shrinkable tube 10 is completely shrunk to the １ is the inner diameter of the outer ring 1.

[0042] Furthermore, the axial length W of the heat-shrinkable tube 10 is set to be at least 1.6 times the axial width dimension (the distance between the pair of axial end faces 1c) of the outer ring 1 so that the axial end faces 1c of the outer ring 1 can be reliably covered with the heat-shrinkable tube 10 in the heat-shrinkable tube heating step described below. The thickness t of the heat-shrinkable tube 10 is set to be no more than 1 / 2 of the arc radius R of the chamfered portion 1b.

[0043] [Heat-Shrink Tube Heating Step] After the heat-shrink tube placement step described above, the heat-shrink tube 10 is heated and deformed to form an insulating coating 5 having a cylindrical outer peripheral covering portion 5a covering the outer peripheral surface 1a of the outer ring 1, a pair of chamfer covering portions 5b with an arc-shaped cross section covering the pair of chamfered portions 1b of the outer ring 1, and a pair of end surface covering portions 5c covering the pair of axial end surfaces 1c of the outer ring 1, as shown in FIG. Methods that can be used to heat the heat-shrink tube 10 include blowing hot air onto the outer periphery of the heat-shrink tube 10 using a heating gun or the like, or passing the rolling bearing 9 and the heat-shrink tube 10 disposed radially outside it through a heating furnace while supported by a support. The heating temperature for the heat-shrink tube 10 can be set within a range of 80°C to 170°C.

[0044] Here, when the heat-shrinkable tube 10 is heated, depending on the shrinkage characteristics of the heat-shrinkable tube 10, the portion of the heat-shrinkable tube 10 corresponding to the end surface covering portion 5c (see FIG. 2) may not be in close contact with the axial end face 1c of the outer ring 1 and may instead be raised above the axial end face 1c, as shown in Fig. 5. Therefore, as shown in Fig. 6, it is preferable to press the portions of the heat-shrinkable tube 10 corresponding to the end surface covering portion 5c (see FIG. 2) against the pair of axial end faces 1c of the outer ring 1 while the heat-shrinkable tube 10 is heated, using a pair of jigs 11 arranged axially opposite the pair of axial end faces 1c of the outer ring 1. In this way, it is possible to ensure that the end surface covering portion 5c of the insulating coating 5 is in close contact with the axial end face 1c of the outer ring 1, as shown in Fig. 2.

[0045] In Fig. 6, the surfaces of the pair of jigs 11 that come into contact with the heat-shrinkable tubing 10 can be made of an elastomer or rubber material. In this way, when the portion of the heat-shrinkable tubing 10 shown in Fig. 5 that corresponds to the end surface covering portion 5c (see Fig. 2) is pressed down with the jig 11 shown in Fig. 6, it is possible to prevent damage to the end surface covering portion 5c due to contact with the jig 11, thereby ensuring the insulating performance of the end surface covering 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 insulating rolling bearing of this embodiment can be used as a rolling bearing that supports a rotating shaft 12 of an electrical device (such as the rotating shaft of an electric motor, the rotating shaft of a reducer that slows the rotation of an electric motor, or the rotating shaft of an alternator). In Figure 7, the insulating rolling bearing is assembled between the cylindrical inner periphery of a housing bore 14 formed in a non-rotating housing 13 and the outer periphery of a rotating shaft 12 located at the center of the housing bore 14. Here, the inner ring 2 is the rotating side and the outer ring 1 is the non-rotating side, so the insulating rolling bearing is assembled in such a manner that the inner ring 2 is fitted onto the outer periphery of the rotating shaft 12 with an interference fit, and the outer ring 1 is fitted onto the inner periphery of the housing bore 14 with a clearance fit. When an insulated rolling bearing is used under high temperature conditions such as 80°C (temperature conditions that are expected when the rotating shaft of an electric motor of an electric vehicle or the rotating shaft of a reducer for that electric motor is supported by the insulated rolling bearing), there is a problem in that wrinkles may occur in the insulating coating 5 in the anti-load side region located on the opposite side (upper side in the figures) from the side on which the radial load is applied (lower side in the figures), as shown in Figures 8 and 9. If these wrinkles occur, there is a risk that the center of the insulated rolling bearing may become misaligned (eccentric).

[0047] To solve this problem, the insulating coating 5 of this embodiment has an inner diameter φD of 103% or less of the outer diameter φD of the outer ring 1 as shown in FIG. ０ A heat-shrinkable tube 10 having an inner diameter φD equal to or close to the outer diameter φD of the outer ring 1 ０ Since the heat-shrinkable tube 10 having the above-mentioned structure is heated and deformed, when the insulated rolling bearing is used at a high temperature such as 80°C, the load-side portion of the insulating coating 5 can be prevented from being compressed in the thickness direction and stretching in the circumferential direction, and wrinkles can be prevented from occurring in the non-load-side portion of the insulating coating 5.

[0048] In particular, the heat-shrinkable tube 10 shown in FIG. 4 has an inner diameter φD that is less than 100% of the outer diameter φD of the outer ring 1. ０When the insulating coating 5 shown in FIG. 2 is formed by using a heat-shrinkable tube 10 having a thickness of 1.5 mm or less, the heat-shrinkable tube 10 is fitted onto the outer peripheral surface 1 a of the outer ring 1 with an interference fit, and the heat-shrinkable tube 10 is heated and deformed, 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 the insulated rolling bearing is used under high-temperature conditions, and it is possible to reliably prevent wrinkles from occurring in the anti-load-side portion of the insulating coating 5.

[0049] Furthermore, as shown in Figure 4, this insulated rolling bearing can form the insulating coating 5 by placing heat-shrinkable tubing 10 radially outside the outer ring 1 and heating and deforming the heat-shrinkable tubing 10, so there is no need for large-scale equipment as is required when providing the insulating coating 5 on the outer ring 1 by insert molding. This makes it possible to reduce the manufacturing costs of the insulated rolling bearing.

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

[0051] In the above embodiment, as shown in FIG. 2 , an example was given in which the axial width dimension of the outer ring 1 and the axial width dimension of the inner ring 2 were the same (i.e., the axial end face 1 c of the outer ring 1 and the axial end face 2 c of the inner ring 2 were at the same axial position), but it is also possible to set the axial width dimension of the outer ring 1 smaller than the axial width dimension of the inner ring 2 so that the surface of the end face covering portion 5 c of the insulating coating 5 is at the same axial position as the axial end face 2 c of the inner ring 2.

[0052] Furthermore, in the above embodiment, the rolling elements 3 are balls, but other shapes of rolling elements 3 such as cylindrical rollers may be used.

[0053] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0054] DESCRIPTION OF SYMBOLS 1 outer ring 1a outer peripheral surface 1b chamfered portion 1c axial end face 2 inner ring 3 rolling element 5 insulating coating 5a outer peripheral coating portion 5b chamfered coating portion 5c end face coating portion 9 rolling bearing 10 heat shrinkable tube 11 jig φD outer diameter φD ０ Inner diameter R Arc radius

Claims

1. An insulated rolling bearing comprising an outer ring (1), an inner ring (2) disposed radially inward of the outer ring (1), a plurality of rolling elements (3) incorporated between the outer ring (1) and the inner ring (2), and a resin insulating coating (5) covering the outer ring (1), wherein the insulating coating (5) is formed of a heat-shrinkable tube (10) that shrinks when heated, wherein the outer ring (1) has a cylindrical outer peripheral surface (1a) having a constant outer diameter along the axial direction, a pair of chamfered portions (1b) having an arc-shaped cross section whose outer diameter gradually decreases from the outer peripheral surface (1a) toward the axially outward direction, and a pair of axial end surfaces (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) that have an arc-shaped cross section and cover the pair of chamfered portions (1b) of the outer ring (1), and a pair of end surface coating portions (5c) that cover the pair of axial end surfaces (1c) of the outer ring (1), and 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 ) by heating and deforming the heat-shrinkable tube (10).

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

4. A bearing preparation step of preparing a rolling bearing (9) having an outer ring (1), an inner ring (2) arranged radially inside the outer ring (1), and a plurality of rolling elements (3) assembled between the outer ring (1) and the inner ring (2), wherein the outer ring (1) has a cylindrical outer peripheral surface (1a) with a constant outer diameter along the axial direction, a pair of chamfered portions (1b) with an arc-shaped cross section whose outer diameter gradually decreases from the outer peripheral surface (1a) toward the axial outside, and a pair of axial end faces (1c) extending radially inward from the pair of chamfered portions (1b); ０ and a heat-shrinkable tube heating step, after the heat-shrinkable tube placing step, of heating and deforming the heat-shrinkable tube (10) to form an insulating coating (5) having a cylindrical outer peripheral covering portion (5a) covering the outer peripheral surface (1a) of the outer ring (1), a pair of chamfered covering portions (5b) having an arc-shaped cross section covering the pair of chamfered portions (1b) of the outer ring (1), and a pair of end face covering portions (5c) covering the pair of axial end faces (1c) of the outer ring (1).

5. In the heat shrink tube arrangement step, the heat shrink tube (10) is arranged to have an inner diameter (φD) that is less than 100% of the outer diameter (φD) of the outer ring (1). ０ 5. A method for manufacturing an insulating rolling bearing according to claim 4, wherein a heat-shrinkable tube (10) having a heat-shrinkable tube (10) is fitted onto the outer peripheral surface (1a) of the outer ring (1) with interference.

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

7. A method for manufacturing an insulating rolling bearing as set forth in claim 4 or 5, wherein in the heat-shrinkable tube heating step, portions of the heat-shrinkable tube (10) corresponding to the end face covering portions (5c) are pressed against the pair of axial end faces (1c) of the outer ring (1) by a pair of jigs (11) arranged axially opposite the pair of axial end faces (1c) of the outer ring (1).

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

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