Insulated rolling bearing and method for manufacturing an insulated rolling bearing

Abstract

In insulated rolling bearings using heat-shrink tubing, the physical strength of the heat-shrink tubing is improved to prevent rupture, peeling, wear, and deformation of the insulating coating. [Solution] The insulating coating 5 is made by heating and deforming a heat-shrinkable resin tube 10 containing a reinforcing material.

Description

Technical Field

[0001] This invention relates to an insulated 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 this spark may cause a phenomenon (electrical erosion) where the surfaces of the outer ring, inner ring, and rolling elements are locally melted. As a rolling bearing capable of preventing this electrical erosion, an insulated rolling bearing provided with an insulating coating on the outer ring is known (for example, Patent Document 1).

[0003] The insulated rolling bearing of Patent Document 1 has 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 inside the mold).

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

[0005] Therefore, in order to reduce the manufacturing cost of the insulated rolling bearing, a product as disclosed in Patent Document 2 has been proposed as an insulated 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, an insulating resin coating is formed that covers the outer circumferential surface and a pair of axial end faces of the outer ring. Examples of resins used for this heat-shrinkable tube include polyethylene terephthalate resin (PET), fluoropolymer resins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) and tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), polycarbonate resin, polystyrene resin, and polyolefin resin (Patent Document 2, paragraph 0006). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3068311 [Patent Document 2] Japanese Patent Publication No. 2001-107974 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, the resins used for heat-shrink tubing in Patent Document 2 do not have sufficient physical strength. As a result, insulated rolling bearings with heat-shrink tubing insulation coatings may be damaged during manufacturing or handling, causing the insulation coating to break, or the heat-shrink tubing may peel off due to interference with the inner diameter surface or chamfered part of the housing when installed in the housing. Furthermore, even after installation, there was a possibility of wear and deformation occurring during use of the insulated rolling bearings.

[0009] The problem that this invention aims to solve is to improve the physical strength of the heat-shrinkable tubing in an insulated rolling bearing using heat-shrinkable tubing, thereby preventing rupture, peeling, wear, and deformation of the insulating coating. [Means for solving the problem]

[0010] 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 covering portion that covers the outer surface of the outer ring, a pair of chamfered covering portions with a circular arc cross-section that cover the pair of chamfered portions of the outer ring, and a pair of end covering portions that cover the pair of axial end faces of the outer ring. An insulated rolling bearing characterized in that the resin constituting the heat-shrinkable tube contains a reinforcing material.

[0011] This configuration improves the strength of the heat-shrink tubing and prevents damage such as scratches and peeling to the insulating coating during manufacturing and installation. It also suppresses wear and deformation during use after installation.

[0012] [Configuration 2] The insulating rolling bearing according to configuration 1, wherein the reinforcing material includes glass fiber, carbon fiber, or both.

[0013] [Configuration 3] The insulating rolling bearing according to configuration 2, wherein the reinforcing material is glass fiber, and the proportion of the glass fiber in the heat shrinkable tube is 20% by mass or less.

[0014] [Structure 4] The insulating rolling bearing according to Configuration 2, wherein the reinforcing material is carbon fiber and the proportion of the carbon fiber in the heat-shrinkable tube is 30% by mass or less.

[0015] [Configuration 5] The insulating rolling bearing according to any one of Configurations 1 to 4, wherein in the outer peripheral covering portion, the reinforcing material is oriented in the axial direction.

[0016] [Configuration 6] The insulating rolling bearing according to any one of Configurations 1 to 5, characterized in that the heat-shrinkable tube having an inner diameter (φD0) that is 103% or less of the outer diameter (φD) of the outer ring is heated and deformed.

[0017] When this configuration is adopted, when attaching the insulating coating to the insulating rolling bearing, it is possible to prevent the load-side portion of the insulating coating from being compressed in the thickness direction and extending in the circumferential direction, and it is possible to prevent the occurrence of wrinkles in the non-load-side portion of the insulating coating. That is, it is possible to prevent the insulating coating from wrinkling not only during use but also during manufacturing, and a more stable insulating rolling bearing can be obtained.

[0018] [Configuration 7] The insulating rolling bearing according to any one of Configurations 1 to 6, wherein the insulating coating has a pair of inner peripheral covering portions that wrap around from the pair of end face covering portions and cover a part of the inner peripheral surface of the outer ring.

[0019] [Configuration 8] The insulating rolling bearing according to any one of Configurations 1 to 7, wherein the insulating coating has a withstand voltage of 200 V or more and an insulation resistance value of 1 MΩ or more.

[0020] [Configuration 9] The axial width (Wi) of the inner ring is The insulating rolling bearing according to any one of Claims 1 to 8, wherein the difference from the sum (Wo + 2 × t1) of the axial width (Wo) of the outer ring and the thickness (t1) of the pair of end face covering portions covering the pair of axial end faces is less than 4% of the axial width (Wi) of the inner ring.

[0021] Furthermore, this invention also provides the following configuration as a method for manufacturing the insulated rolling bearing described above. [Configuration 10] A bearing preparation step for preparing a rolling bearing comprising an outer ring, an inner ring positioned radially inward of 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 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, A heat shrink tube placement step is to place a heat shrink tube made of resin containing a reinforcing material on the radially outer side of the rolling bearing, A method for manufacturing an insulated rolling bearing, comprising a heat shrink tube heating step, after the heat shrink tube placement step, wherein the heat shrink tube is heated and deformed 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 a circular arc cross-section that covers the pair of chamfered portions of the outer ring, and a pair of end covering portions that cover the pair of axial end faces of the outer ring.

[0022] [Composition 11] The method for manufacturing an insulated rolling bearing according to configuration 10, wherein the heat shrinkable tube has the reinforcing material oriented in the axial direction.

[0023] [Composition 12] In the heat shrink tube placement step, the heat shrink tube used has an inner diameter (φD0) that is 103% or less of the outer diameter (φD) of the outer ring. A method for manufacturing an insulated rolling bearing according to configuration 10 or 11, wherein the heat shrink tube is fitted to the outer surface of the outer ring such that the shrinkage rate of the heat shrink tube before and after heating is 3% or less.

[0024] [Composition 13] A method for manufacturing an insulated rolling bearing according to any one of configurations 10 to 12, wherein in the heat shrink tube heating step, the insulating coating also forms a pair of inner circumferential coatings that wrap around from the pair of end face coatings and cover a part of the inner circumferential surface of the outer ring.

[0025] [Composition 14] A method for manufacturing an insulated rolling bearing according to any one of configurations 10 to 13, wherein the heating temperature in the heat shrink tube heating step is 60°C or more and 150°C or less. [Effects of the Invention]

[0026] 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 tube. This eliminates the need for large-scale equipment, such as when insulating the outer ring by insert molding. Therefore, it is possible to reduce the manufacturing cost of the insulated rolling bearing. This low cost allows for stable manufacturing, high yield, and improved durability during use. [Brief explanation of the drawing]

[0027] [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] Enlarged view of the outer ring area in Figure 2. [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] A flowchart illustrating an example of a method for manufacturing an insulated rolling bearing according to an embodiment of this invention. [Figure 6] Enlarged view of the outer ring area in Figure 4. [Figure 7] Figure 4 shows the state after the heat shrink tubing has been heated and shrunk. [Figure 8] Figure 7 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 9] Figure 2 shows an example of the usage state of an insulated rolling bearing. [Modes for carrying out the invention]

[0028] 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.

[0029] 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 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. 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. The radial inner side is the side of the outer ring 1 and inner ring 2 that approaches the radial center along the radial direction, and the radial outer side is the side of the outer ring 1 and inner ring 2 that moves away from the radial center along the radial direction.

[0030] 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.

[0031] Figure 3 shows an enlarged view of the area around the outer ring 1. 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 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 axial end faces 1c are planes perpendicular to the axial direction. The outer ring 1 also has a pair of inner chamfered portions 1d with a circular arc cross-section whose outer diameter gradually decreases axially inward from the axial end faces 1c. Furthermore, the outer ring 1 has a pair of inner circumferential surfaces 1e that are cylindrical with a constant outer diameter that does not change along the axial direction, extending axially outward across the outer ring raceway groove 6 formed on the inner circumference of the outer ring 1.

[0032] Here, the outer diameter φD (see Figure 4) of the outer circumferential surface 1a of the outer ring 1 is set to be between 45 mm and 110 mm, and the axial width dimension of the outer ring 1 is set to be between 9 mm and 30 mm. In addition, the surface roughness of the outer circumferential surface 1a of the outer ring 1 along the axial direction is set to be between Ra 0.05 μm and 1.6 μm. 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 be between 0.3 mm and 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 later.

[0033] The insulating coating 5 includes a cylindrical outer coating portion 5a that covers the outer circumferential surface 1a of the outer ring 1, a pair of chamfered coating portions 5b with an arc cross-section that cover a pair of chamfered portions 1b of the outer ring 1, a pair of end face coating portions 5c that cover a pair of axial end faces 1c of the outer ring 1, a pair of inner chamfered coating portions 5d with an arc cross-section that cover a pair of inner chamfered portions 1d of the outer ring 1, and a pair of inner circumferential coating portions 5e that cover a part of the axially outer side of a pair of inner circumferential surfaces 1e of the outer ring. The pair of chamfered coating portions 5b are formed in conjunction with both axial ends of the outer coating portion 5a, 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, the pair of inner chamfered coating portions 5d are formed in conjunction with the radially inner ends of the pair of end face coating portions 5c, and the pair of inner circumferential coating portions 5e are formed in conjunction with the axially inner ends of the pair of inner chamfered coating portions 5d. The end face covering portion 5c is preferably provided in close contact with the axial end face 1c of the outer ring 1, but it may also be provided in a state where it is lifted away from 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 portion 5c).

[0034] The insulating coating 5 has a thickness set such that the outer peripheral coating portion 5a (i.e., the thinnest part of the outer peripheral coating portion 5a, chamfered coating portion 5b, end face coating portion 5c, inner peripheral chamfered coating portion 5d, and inner peripheral coating portion 5e) 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.

[0035] Furthermore, the axial width Wo of the outer ring 1 is smaller than the axial width Wi of the inner ring 2. It is preferable that the total width (Wo + 2 × t1), which is the axial width Wo of the outer ring 1 plus the thickness t1 of the pair of end face coverings 5c of the insulating coating 5 formed at both axial ends, is close to the axial width Wi of the inner ring 2. Specifically, it is desirable that |Wi - (Wo + 2 × t1)| / Wi < 0.04. That is, it is desirable that the difference between the axial width Wi of the inner ring 2 and the total width (Wo + 2 × t1) is less than 4% of the axial width (Wi) of the inner ring. The smaller this difference, the closer the inner ring 2 and the outer ring 1 with the insulating coating 5 will be to being flush when installing this insulated rolling bearing, making it easier to use in a suitable design.

[0036] An example of a manufacturing method for this insulated rolling bearing will be explained with reference to the flowchart in Figure 5.

[0037] [Bearing preparation process] Prepare the rolling bearing 9 shown in Figure 4. This rolling bearing 9 has multiple rolling elements 3 incorporated between the outer ring 1 and the inner ring 2, and does not have the insulating coating 5 shown in Figure 2.

[0038] [Heat shrink tubing placement process] After the bearing preparation steps described above, a heat-shrinkable resin tube 10 is placed radially outward of the rolling bearing 9, as shown in Figure 4.

[0039] As the heat-shrinkable tube 10, a tube made from a resin material containing a reinforcing agent can be formed into a tube shape, irradiated with an electron beam to crosslink the resin material, then heated to a predetermined high temperature and stretched radially (or radially and axially), and then cooled. In this case, the dimensions of the stretched tube correspond to the dimensions of the heat-shrinkable tube 10 before shrinkage due to heating.

[0040] The inclusion of the above-mentioned reinforcing material in the resin material improves the strength of the heat-shrinkable tube 10, preventing damage to the insulating coating 5 during the manufacturing and installation of the rolling bearing 9, and suppressing wear and deformation of the insulating coating 5 during use. This makes it easier to maintain the insulating performance of the insulating coating 5.

[0041] As the reinforcing material mentioned above, fibrous materials are preferable due to their oriented properties. Specific examples include glass fiber and carbon fiber.

[0042] The preferred proportion of the above-mentioned reinforcing material to the resin material varies depending on the type of reinforcing material used. If the proportion is too low, the strength-improving effect of the reinforcing material will not be substantially realized. For this reason, it is desirable for the reinforcing material to account for 5% by mass or more, and more preferably 10% by mass or more. Examples include BASF's A3HG5 and A3WG6. Note that increasing the amount of glass fiber contained in polyamide 66 increases the tensile strength as shown in Table 1 below. In the table, glass fiber is abbreviated as "GF".

[0043] [Table 1]

[0044] On the other hand, the reinforcing material has the effect of hindering the shrinkage of the heat-shrinkable tube 10, and if there is too much of it, the shrinkage rate may decrease too much, making it difficult to attach to the rolling bearing 9. Ideally, the shrinkage rate of the heat-shrinkable tube 10 should be 5% or more. To ensure this shrinkage rate, if the reinforcing material is fiberglass, it is desirable that its proportion in the resin material be 20% by mass or less. If the reinforcing material is carbon fiber, it is desirable that its proportion in the resin material be 30% by mass or less.

[0045] The reinforcing material described above is preferably oriented axially within the heat-shrinkable tube 10. Axial orientation means that the average value of the angles indicated by the long side direction of the numerous fibers is closer to the axial side than to the radial side. The angle of the direction indicated by the average value of the angles with respect to the axial direction is preferably less than 45 degrees, and the smaller this angle, the better.

[0046] If the heat shrink tubing 10 has the orientation described above, the reinforcing material will be aligned in the axial direction in the outer peripheral coating portion 5a of the insulating coating 5 formed by the heat shrink tubing 10, as described later. As a result, the heat shrink tubing will be less likely to deform in the axial direction when the bearing is used, making it easier to maintain its shape.

[0047] The heat shrink tubing 10 used has an inner diameter φD0 that is between 100% and 103% of the outer diameter φD of the outer surface 1a of the outer ring 1. Here, in order to facilitate the process of placing the heat shrink tubing 10 on the outside of the outer ring 1, a heat shrink tubing 10 with an inner diameter φD0 of 100% or more of the outer diameter φD of the outer surface 1a of the outer ring 1 is used. However, a heat shrink tubing 10 with an inner diameter φD0 of less than 100% of the outer diameter φD of the outer surface 1a of the outer ring 1 may also be used, and the heat shrink tubing 10 may be fitted onto the outer surface 1a of the outer ring 1 with an overlap.

[0048] Furthermore, it is preferable to use a heat shrink tube 10 having a radial shrinkage rate of 3% or less that satisfies (φD0-φD1) / φD0 < 0.03, so that the axial end face 1c of the outer ring 1 can be reliably 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 in 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.

[0049] 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 (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 in the heat shrink tube heating process described later. It is more preferable that the heat shrink tube 10 after shrinkage is long enough to reach a part of the inner circumferential surface 1e of the outer ring 1 so that an inner circumferential covering portion 5e can be formed. Specifically, it is preferable that the axial length W' of the heat shrink tube 10 after shrinkage is W' > W1 + 2 × W2 + 2 × W3 + 2 × W4, where W' is the axial width of the outer circumferential surface 1a of the outer ring 1 shown in Figure 6 (W1), the length along the arc of the pair of chamfered portions 1b of the outer ring 1 (W2), the radial width of the pair of axial end faces 1c of the outer ring 1 (W3), and the length along the arc of the pair of inner circumferential chamfered portions 1d of the outer ring 1 (W4). The axial length W' after shrinkage is given by W' = W × (1 - a / 100) with respect to the axial shrinkage rate a (%) of the heat shrink tube 10.

[0050] Furthermore, the thickness t of the heat shrink tubing 10 is set to be at least twice the arc radius R of the chamfered portion 1b. The thickness t of the heat shrink tubing 10 is slightly smaller than the thickness (t1) of the insulating coating. However, the radial shrinkage rate of the heat shrink tubing 10 is very small, and it may expand slightly with axial shrinkage, so in reality the thickness t is approximately the same as t1.

[0051] [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 60°C to 150°C.

[0052] 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 7, and may lift away from the axial end face 1c. Therefore, as shown in Figure 8, 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.

[0053] Furthermore, the pair of jigs 11 may have protruding portions 11a for wrapping around and pressing down both axial ends of the heat shrink tubing 10 so as to cover a portion of the pair of inner circumferential surfaces 1e of the outer ring 1, thereby forming an inner circumferential covering portion 5e. These protruding portions 11a have curved surfaces that are in line with the pair of inner circumferential chamfers 1d of the outer ring 1. However, these protruding portions 11a are formed so as not to interfere with and damage the retainer 4.

[0054] In Figure 8, 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 covering portion 5c (see Figure 2) of the heat-shrinkable tube 10 from contact with the jig 11 when the jig 11 shown in Figure 8 presses down on the end-face covering portion 5c, as shown in Figure 3, and ensures the insulating performance of the end-face covering portion 5c. It is preferable to use an elastomer or rubber material that has a heat resistance of 100°C or higher.

[0055] As shown in Figure 9, 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 9, the insulated rolling bearing is incorporated 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.

[0056] 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.

[0057] 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.

[0058] In the above embodiment, as shown in Figure 2, the axial width dimension of the outer ring 1 was set 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 in the same axial position as the axial end face 2c of the inner ring 2. However, depending on the environment in which the insulated rolling bearing is installed, it is also possible to make the axial width dimension of the outer ring 1 and the axial width dimension of the inner ring 2 the same (i.e., the axial end face 1c of the outer ring 1 and the axial end face 2c of the inner ring 2 are in the same axial position).

[0059] 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.

[0060] 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]

[0061] 1 Outer ring 1a Outer surface 1b Chamfered section 1c Axial end face 1d Inner circumferential chamfer 1e Inner surface 2 Inner ring 3 Rolling element 5. Insulating coating 5a Outer sheathing part 5b Chamfered coating 5c End covering part 5d Inner circumferential chamfered coating 5e Inner circumferential coating 9 Rolling bearings 10 Heat shrink tubing 11 Jig 11a Overhang 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). An insulating rolling bearing characterized in that the resin constituting the heat-shrinkable tube (10) contains a reinforcing material.

2. The insulating rolling bearing according to claim 1, wherein the reinforcing material includes glass fiber, carbon fiber, or both.

3. The insulating rolling bearing according to claim 2, wherein the reinforcing material is glass fiber, and the proportion of the glass fiber in the heat shrinkable tube is 20% by mass or less.

4. The insulating rolling bearing according to claim 2, wherein the reinforcing material is carbon fiber, and the proportion of the carbon fiber in the heat shrinkable tube is 30% by mass or less.

5. The insulating rolling bearing according to claim 1, wherein the reinforcing material in the outer peripheral covering portion (5a) is oriented in the axial direction.

6. 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 The insulating rolling bearing according to claim 1, characterized in that the heat shrink tube (10) having ) is heated and deformed.

7. The insulating rolling bearing according to claim 1, wherein the insulating coating (5) has a pair of inner circumferential coating portions (5e) that wrap around from the pair of end face coating portions (5c) and cover a part of the inner circumferential surface (1e) of the outer ring (1).

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

9. The axial width (Wi) of the inner ring (2) is, The insulating rolling bearing according to claim 1, wherein the difference between the sum of the axial width (Wo) of the outer ring (1) and the thickness (t1) of the pair of end face coverings (5c) covering the pair of axial end faces (1c) (Wo + 2 × t1) is less than 4% of the axial width (Wi) of the inner ring (2).

10. A bearing preparation step to prepare a rolling bearing (9) having an outer ring (1), an inner ring (2) positioned 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), A heat shrink tube placement step is to place a heat shrink tube (10) made of resin containing a reinforcing material on the radially outer side of the rolling bearing (9), 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).

11. In the heat shrink tube heating step, the heat shrink tube (10) has an inner diameter (φD) that is 103% or less of the outer diameter (φD) of the outer ring (1). ０ Using one that has ), A method for manufacturing an insulated rolling bearing according to claim 10, wherein the heat shrink tube (10) is fitted onto the outer circumferential surface (1a) of the outer ring (1) such that the shrinkage rate of the heat shrink tube (10) before and after heating is 3% or less.

12. The method for manufacturing an insulated rolling bearing according to claim 10, wherein in the heat shrink tube heating step, the insulating coating (5) also forms a pair of inner circumferential coating portions (5e) that wrap around from the pair of end face coating portions (5c) and cover a part of the inner circumferential surface (1e) of the outer ring (1).

13. The method for manufacturing an insulated rolling bearing according to claim 10, wherein the heating temperature in the heat shrink tube heating step is 60°C or more and 150°C or less.

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