Insulated rolling bearing and manufacturing method for insulated rolling bearing

Abstract

Provided is an insulated rolling bearing that is manufactured at low cost and can prevent insufficient strength or deformation in a high-temperature environment such as a motor for an electric vehicle. An insulating coating (5) is obtained by heating and deforming a heat-shrinkable tube (10) in which the glass transition temperature of a resin is 120 °C or higher.

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 insulated rolling bearing of 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 positioned radially outside the outer ring, and the heat-shrinkable tube is heated and shrunk to form a resin insulating coating that covers the outer peripheral surface and a pair of axial end faces of the outer ring. Examples of resins that can be used for this heat-shrinkable tube include polyethylene terephthalate resin (PET), fluororesins 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).

[0007] Japanese Patent No. 3068311 Japanese Patent Laid-Open No. 2001-107974

[0008] When the temperature of these resins exceeds their glass transition temperature, the molecules become more mobile and change from glassy to rubbery. This glass transition temperature varies depending on the resin, but is around 78°C for polyamide 46, around 66°C for polyamide 66, around 88°C for polyphenylene sulfide, around 69°C for polyethylene terephthalate, and around 87°C for polyvinyl chloride.

[0009] When heating heat-shrink tubing to shrink it, it should be heated above its glass transition temperature. After shrinking and attaching it to an object, it is best not to let it exceed its glass transition temperature. If it is heated above its glass transition temperature again, the attached heat-shrink tubing may shift or deform.

[0010] In electric vehicles such as e-Axle (registered trademark), it is desirable to use insulated rolling bearings to prevent sparks. However, while the motor and reducer components of electric vehicles are controlled to prevent overheating to prevent performance degradation, they are generally required to be kept below 100°C, and it is quite possible for them to heat up to nearly 100°C. Peak temperatures can reach nearly 120°C at short intervals. In such an environment, there is a risk that the heat shrink tubing will become weak or the resin will deform, resulting in a reduction in motor performance.

[0011] The first problem to be solved by this invention is to enable an insulating rolling bearing using a heat-shrinkable tube to be used stably in a high-temperature environment such as an electric vehicle motor.

[0012] On the other hand, the resins used for the heat-shrink tubing in Patent Document 2 do not have sufficient physical strength. As a result, insulated rolling bearings with insulating coatings formed with heat-shrink tubing could be damaged during manufacturing or handling, causing the insulating coating to break, or the heat-shrink tubing could come off due to interference with the housing's inner diameter surface or chamfered portion when mounted in the housing. Furthermore, even after mounting, there is a risk of wear and deformation during use of the insulated rolling bearing.

[0013] A second problem to be solved by this invention is to improve the physical strength of the heat-shrinkable tube in an insulated rolling bearing that uses a heat-shrinkable tube, thereby preventing breakage, peeling, wear, and deformation of the insulating coating.

[0014] In order to solve the first problem above, a first invention provides an insulated rolling bearing having the following configuration: [Configuration 1-1] An insulated rolling bearing comprising 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 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 outward in the axial direction, and a pair of axial end faces extending radially inward from the pair of chamfered portions, the insulating coating comprising a cylindrical outer peripheral covering portion covering the outer peripheral surface of the outer ring, a pair of chamfer 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 wherein the glass transition temperature of the resin constituting the heat-shrinkable tubing is 120°C or higher.

[0015] By adopting this configuration, the heat-shrinkable tubing that forms the insulating coating can be prevented from unintentionally deforming or becoming insufficient in strength, even in environments of around 100°C, such as those found in electric vehicle motors, and the insulating performance and mounting position can be stabilized.

[0016] [Configuration 1-2] The insulating rolling bearing according to Configuration 1-1, wherein the resin contains a reinforcing material, an additive, or both.

[0017] [Configuration 1-3] The inner diameter (φD) of the outer ring is 103% or less of the outer diameter (φD) of the outer ring. ０ 3. The insulating rolling bearing according to configuration 1-1 or 1-2, characterized in that the heat-shrinkable tube having the insulating rolling bearing is heated and deformed.

[0018] By adopting this configuration, when attaching the insulating coating to the insulated rolling bearing, the load-side portion of the insulating coating can be prevented from being compressed in the thickness direction and stretched in the circumferential direction, and it is possible to prevent the occurrence of wrinkles in the non-load-side portion of the insulating coating. In other words, it is possible to prevent the insulating coating from wrinkling not only during use but also during manufacturing, resulting in a more stable insulated rolling bearing.

[0019] [Configuration 1-4] An insulating rolling bearing according to any one of Configurations 1-1 to 1-3, wherein the insulating coating has a pair of inner peripheral coating portions that extend from the pair of end surface coating portions and cover part of the inner peripheral surface of the outer ring.

[0020] [Configuration 1-5] An insulating rolling bearing according to any one of Configurations 1-1 to 1-4, wherein the insulating coating has a withstand voltage of 200 V or more and an insulation resistance of 1 MΩ or more.

[0021] [Configuration 1-6] An insulating rolling bearing according to any one of Configurations 1-1 to 1-5, wherein the difference between the axial width (Wi) of the inner ring and the sum (Wo + 2 × t1) of the axial width (Wo) of the outer ring and the thickness (t1) of a pair of end face covering portions that cover the pair of axial end faces is less than 4% of the axial width (Wi) of the inner ring.

[0022] The first invention also provides a method for manufacturing the above-mentioned insulating rolling bearing, which has the following configuration. [Configuration 1-7] 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 reduces 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 heat-shrinkable tube made of a resin having a glass transition temperature of 120°C or higher 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.

[0023] [Configuration 1-8] In the heat-shrinkable tube placement step, the heat-shrinkable tube has an inner diameter (φD) of 103% or less of the outer diameter (φD) of the outer ring. ０ and fitting the heat-shrinkable tube onto the outer peripheral surface of the outer ring such that the shrinkage rate of the heat-shrinkable tube before and after heating is 3% or less.

[0024] [Configuration 1-9] A method for manufacturing an insulating rolling bearing according to Configuration 1-8 or 1-9, in which, in the heat-shrinkable tube heating step, the insulating coating also forms a pair of inner peripheral coating portions that extend from the pair of end surface coating portions and cover part of the inner peripheral surface of the outer ring.

[0025] [Configuration 1-10] The method for producing an insulating rolling bearing according to any one of Configurations 1-7 to 1-9, wherein the heating temperature in the heat-shrinkable tube heating step is 120°C or higher and 170°C or lower.

[0026] Furthermore, to solve the second problem, a second invention provides an insulated rolling bearing having the following configuration: [Configuration 2-1] An insulated rolling bearing comprising 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 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 outward in the axial direction, and a pair of axial end faces extending radially inward from the pair of chamfered portions, the insulating coating has 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 resin constituting the heat-shrinkable tubing contains a reinforcing material.

[0027] This configuration improves the strength of the heat-shrinkable tubing, preventing damage to the insulating coating, such as scratches or peeling, during manufacturing or installation, and also suppressing wear and deformation during use after installation.

[0028] [Configuration 2-2] The electrically insulating rolling bearing according to Configuration 2-1, wherein the reinforcing material includes glass fiber, carbon fiber, or both.

[0029] [Configuration 2-3] An insulating rolling bearing according to Configuration 2-2, wherein the reinforcing material is glass fiber, and the proportion of the glass fiber in the heat-shrinkable tube is 20 mass % or less.

[0030] [Configuration 2-4] The insulating rolling bearing according to Configuration 2-2, wherein the reinforcing material is carbon fiber, and the proportion of the carbon fiber in the heat-shrinkable tube is 30 mass % or less.

[0031] [Configuration 2-5] The electrically insulating rolling bearing according to any one of Configurations 2-1 to 2-4, wherein the reinforcing material is oriented in the axial direction in the outer peripheral covering portion.

[0032] [Configuration 2-6] An inner diameter (φD) of the outer ring is 103% or less of the outer diameter (φD) of the outer ring. ０ 6. An insulating rolling bearing according to any one of configurations 2-1 to 2-5, wherein the heat-shrinkable tube having the insulating rolling bearing is heated and deformed.

[0033] By adopting this configuration, when attaching the insulating coating to the insulated rolling bearing, the load-side portion of the insulating coating can be prevented from being compressed in the thickness direction and stretched in the circumferential direction, and it is possible to prevent the occurrence of wrinkles in the non-load-side portion of the insulating coating. In other words, it is possible to prevent the insulating coating from wrinkling not only during use but also during manufacturing, resulting in a more stable insulated rolling bearing.

[0034] [Configuration 2-7] An insulating rolling bearing according to any one of Configurations 2-1 to 2-6, wherein the insulating coating has a pair of inner peripheral coating portions that extend from the pair of end surface coating portions and cover part of the inner peripheral surface of the outer ring.

[0035] [Configuration 2-8] An insulating rolling bearing according to any one of Configurations 2-1 to 2-7, wherein the insulating coating has a withstand voltage of 200 V or more and an insulation resistance of 1 MΩ or more.

[0036] [Configuration 2-9] An insulating rolling bearing according to any one of claims 2-1 to 2-8, wherein the difference between the axial width (Wi) of the inner ring and the sum (Wo + 2 × t1) of the axial width (Wo) of the outer ring and the thickness (t1) of a pair of end face covering portions that cover the pair of axial end faces is less than 4% of the axial width (Wi) of the inner ring.

[0037] In addition, a second aspect of the present invention also provides a method for manufacturing the above-mentioned insulating rolling bearing, which has the following configuration. [Configuration 2-10] 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 heat-shrinkable tube made of a resin that contains a reinforcing material on the radial outside 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.

[0038] [Configuration 2-11] The method for producing an insulating rolling bearing according to Configuration 2-10, wherein the reinforcing material of the heat-shrinkable tube is oriented in the axial direction.

[0039] [Configuration 2-12] In the heat-shrinkable tube placement step, the heat-shrinkable tube has an inner diameter (φD) of 103% or less of the outer diameter (φD) of the outer ring. ０ ) and fitting the heat-shrinkable tube onto the outer peripheral surface of the outer ring so that the shrinkage rate of the heat-shrinkable tube before and after heating is 3% or less.

[0040] [Configuration 2-13] A method for manufacturing an insulating rolling bearing according to any one of Configurations 2-10 to 2-12, in which, in the heat-shrinkable tube heating step, the insulating coating also forms a pair of inner peripheral coating portions that extend from the pair of end surface coating portions and cover part of the inner peripheral surface of the outer ring.

[0041] [Configuration 2-14] The method for producing an insulating rolling bearing according to any one of Configurations 2-10 to 2-13, wherein the heating temperature in the heat-shrinkable tube heating step is 60°C or higher and 150°C or lower.

[0042] In the insulated rolling bearing of the first invention, the insulating coating can be formed by placing a heat-shrinkable tube on the radially outside of 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. Because the resin constituting the insulating coating has a glass transition temperature of 120°C or less, even when this insulated rolling bearing is used in electric vehicle motors and reducers, which are prone to temperatures as high as 100°C, it is possible to prevent the insulating coating from shifting or wrinkling, resulting in insufficient strength and reduced bearing performance.

[0043] In the insulated rolling bearing of the second invention, the heat-shrinkable tubing is positioned radially outside the outer ring, and the insulating coating can be formed by heating and deforming the heat-shrinkable tubing. This eliminates the need for large-scale equipment as is required when applying an insulating coating to the outer ring by insert molding. This reduces the manufacturing costs of the insulated rolling bearing. This enables stable manufacturing at low cost, increases yield, and improves durability during use.

[0044] 2 is an enlarged view of the periphery of the outer ring; FIG. 3 is a diagram for explaining a method for manufacturing the insulated rolling bearing of FIG. 2, showing a state in which a heat-shrinkable tube before shrinking is disposed radially outside the outer peripheral surface of the outer ring; FIG. 4 is an enlarged view of the periphery of the outer ring; FIG. 5 is a diagram showing a state in which the heat-shrinkable tube shown in FIG. 4 has been heated and shrunk;

[0045] <First Invention> First, the first invention will be described. Fig. 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 assembled 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.

[0046] 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.

[0047] 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.

[0048] FIG. 3 shows an enlarged view of the outer ring 1 and its surroundings. The outer ring 1 has a cylindrical outer peripheral surface 1a with a constant outer diameter that does not change 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 axially outward direction, 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. The outer ring 1 also has a pair of inner peripheral chamfered portions 1d with an arc-shaped cross section whose outer diameter gradually decreases from the axial end faces 1c toward the axially inward direction. Furthermore, the outer ring 1 has a pair of cylindrical inner peripheral surfaces 1e with a constant outer diameter that does not change along the axial direction, extending axially outward across an outer ring raceway groove 6 formed on the inner circumference of the outer ring 1.

[0049] 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 (Ra). 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 merges with 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 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.

[0050] 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, a pair of end face covering portions 5c covering the pair of axial end faces 1c of the outer ring 1, a pair of inner peripheral chamfered covering portions 5d with an arc-shaped cross section covering the pair of inner peripheral chamfered portions 1d of the outer ring 1, and a pair of inner peripheral covering portions 5e covering parts of the axial outside of the pair of inner peripheral surfaces 1e of the outer ring. The pair of chamfered covering portions 5b are formed continuous with both axial ends of the outer peripheral covering portion 5a, the pair of end face covering portions 5c are formed continuous with the radial inner ends of the pair of chamfered covering portions 5b, the pair of inner peripheral chamfered covering portions 5d are formed continuous with the radial inner ends of the pair of end face covering portions 5c, and the pair of inner peripheral covering portions 5e are formed continuous with the axial inner ends of the pair of inner peripheral chamfered covering 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 may also be provided in a state where it is raised above the axial end face 1c of the outer ring 1 (a state where a gap exists between the axial end face 1c of the outer ring 1 and the end face covering portion 5c).

[0051] 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, the end face coating portion 5c, the inner peripheral chamfered coating portion 5d, and the inner peripheral coating portion 5e) 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 resin heat-shrinkable tube 10 that shrinks when heated, as will be described later.

[0052] Furthermore, the axial width Wo of the outer ring 1 is smaller than the axial width Wi of the inner ring 2. The closer the total width (Wo + 2 × t1) obtained by adding the axial width Wo of the outer ring 1 and the thickness t1 of the pair of end surface covering portions 5c of the insulating coating 5 formed on both axial ends to the axial width Wi of the inner ring 2, the more preferable it is. Specifically, it is desirable that |Wi - (Wo + 2 × t1)| / Wi < 0.04. In other words, it is desirable that the difference between the axial width Wi of the inner ring 2 and this 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 flush when mounting this insulated rolling bearing, making it easier to use in a favorable design.

[0053] An example of a method for manufacturing this insulating rolling bearing will be described with reference to the flow chart of FIG.

[0054] [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.

[0055] [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.

[0056] The heat-shrinkable tube 10 can be made by irradiating a resin material having a glass transition temperature of 120° C. or higher into a tube shape with electron beams to crosslink the resin material, then stretching the tube in the radial direction (or in the radial and axial directions) while heating it to a predetermined high temperature, and then cooling it. 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.

[0057] Examples of resin materials that can achieve a glass transition temperature of 120°C or higher include polyphthalamide (125°C) and polyether ether ketone (143°C). This resin material does not need to be a single type of resin, but may be a mixture of multiple types of resin. This resin material may also contain a reinforcing material, an additive, or both. Examples of reinforcing materials that can be used include glass fiber (GF) and carbon fiber (CF). Examples of additives that can be used include heat stabilizers and antioxidants.

[0058] On the other hand, it is preferable that the glass transition temperature of the resin material be 200° C. or lower. If the glass transition temperature is high, a high temperature is also required when heating the heat-shrinkable tube 10 to cause it to thermally shrink. If this temperature is too high, there is a risk that the bearing itself will be subjected to heat treatment (annealing).

[0059] The glass transition temperature in this case can be a value obtained by general differential scanning calorimetry (DSC).

[0060] 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.

[0061] In addition, the heat-shrinkable tube 10 is formed to have a diameter (φD ０ -φD １ ) / φD ０ It is preferable to use a material having a radial shrinkage rate of 3% or less, which satisfies the condition of <0.03. Here, the radial shrinkage rate X is the inner diameter φD of the heat-shrinkable tube 10 before it is heated and shrunk. ０is 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.

[0062] Furthermore, the axial length W of the heat-shrinkable 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 by the heat-shrinkable tube 10 in the heat-shrinkable tube heating step described below. It is more preferable if the heat-shrinkable tube 10 after shrinking is long enough to reach part of the inner circumferential surface 1e of the outer ring 1, as this allows for the formation of the inner circumferential covering portion 5e. Specifically, the axial length W' of the heat-shrinkable tube 10 after shrinking preferably satisfies the relationship W' > W1 + 2 × W2 + 2 × W3 + 2 × W4, where W1 is the axial width of the outer peripheral surface 1a of the outer ring 1, W2 is the length along the arc of the pair of chamfered portions 1b of the outer ring 1, W3 is the radial width of the pair of axial end faces 1c of the outer ring 1, and W4 is the length along the arc of the pair of inner circumferential chamfered portions 1d of the outer ring 1, as shown in FIG. 6 . The axial length W′ after shrinkage is W′=W×(1−a / 100) where a (%) is the axial shrinkage rate of the heat-shrinkable tube 10 .

[0063] The thickness t of the heat-shrinkable tube 10 is set to be at least twice the arc radius R of the chamfered portion 1b. The thickness t of the heat-shrinkable tube 10 is slightly smaller than the thickness (t1) of the insulating coating. However, since the shrinkage rate of the heat-shrinkable tube 10 in the radial direction is very small and it may expand slightly due to axial shrinkage, in reality the thickness t is approximately equal to t1.

[0064] [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 120°C to 170°C.

[0065] 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. 7. Therefore, as shown in Fig. 8, 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.

[0066] Furthermore, the pair of jigs 11 preferably have protruding portions 11a for wrapping around and pressing down both axial ends of the heat-shrinkable tube 10 so as to cover portions of the pair of inner circumferential surfaces 1e of the outer ring 1 and form the inner circumferential covering portion 5e. The protruding portions 11a have curved surfaces that conform to the pair of inner circumferential chamfered portions 1d of the outer ring 1. However, the protruding portions 11a are formed so as not to interfere with and damage the cage 4.

[0067] In Fig. 8, 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. 3 that corresponds to the end surface covering portion 5c (see Fig. 2) is pressed down with the jig 11 shown in Fig. 8, 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.

[0068] 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 reduces the rotation of an electric motor, or the rotating shaft of an alternator), as shown in Figure 9. In Figure 9, the insulating rolling bearing is incorporated between the cylindrical inner periphery of a housing bore 14 formed in a non-rotating housing 13 and the outer periphery of the rotating shaft 12 located at the center of the housing bore 14.

[0069] 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.

[0070] 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.

[0071] In the above embodiment, as shown in Figure 2, an example has been described in which the axial width dimension of the outer ring 1 is set smaller than that 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. However, depending on the environment in which the insulated rolling bearing is installed, it is also possible for the axial width dimension of the outer ring 1 and the axial width dimension of the inner ring 2 to be the same (in other words, 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).

[0072] 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.

[0073] 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.

[0074] <Second Invention> Next, the second invention will be described. Figure 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 assembled 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.

[0075] 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. 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. The radially inner side is the side that approaches the radial center of the outer ring 1 and inner ring 2 along the radial direction, and the radially outer side is the side that moves away from the radial center of the outer ring 1 and inner ring 2 along the radial direction.

[0076] 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.

[0077] FIG. 3 shows an enlarged view of the outer ring 1 and its surroundings. The outer ring 1 has a cylindrical outer peripheral surface 1a with a constant outer diameter that does not change 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 axially outward direction, 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. The outer ring 1 also has a pair of inner peripheral chamfered portions 1d with an arc-shaped cross section whose outer diameter gradually decreases from the axial end faces 1c toward the axially inward direction. The outer ring 1 also has a pair of cylindrical inner peripheral surfaces 1e with a constant outer diameter that does not change along the axial direction, extending axially outward across an outer ring raceway groove 6 formed on the inner circumference of the outer ring 1.

[0078] 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 (Ra). 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 merges with 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 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.

[0079] 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, a pair of end face covering portions 5c covering the pair of axial end faces 1c of the outer ring 1, a pair of inner peripheral chamfered covering portions 5d with an arc-shaped cross section covering the pair of inner peripheral chamfered portions 1d of the outer ring 1, and a pair of inner peripheral covering portions 5e covering parts of the axial outside of the pair of inner peripheral surfaces 1e of the outer ring. The pair of chamfered covering portions 5b are formed continuous with both axial ends of the outer peripheral covering portion 5a, the pair of end face covering portions 5c are formed continuous with the radial inner ends of the pair of chamfered covering portions 5b, the pair of inner peripheral chamfered covering portions 5d are formed continuous with the radial inner ends of the pair of end face covering portions 5c, and the pair of inner peripheral covering portions 5e are formed continuous with the axial inner ends of the pair of inner peripheral chamfered covering 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 may also be provided in a state where it is raised above the axial end face 1c of the outer ring 1 (a state where a gap exists between the axial end face 1c of the outer ring 1 and the end face covering portion 5c).

[0080] 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, the end face coating portion 5c, the inner peripheral chamfered coating portion 5d, and the inner peripheral coating portion 5e) 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 resin heat-shrinkable tube 10 that shrinks when heated, as will be described later.

[0081] Furthermore, the axial width Wo of the outer ring 1 is smaller than the axial width Wi of the inner ring 2. The closer the total width (Wo + 2 × t1) obtained by adding the axial width Wo of the outer ring 1 and the thickness t1 of the pair of end surface covering portions 5c of the insulating coating 5 formed on both axial ends to the axial width Wi of the inner ring 2, the more preferable it is. Specifically, it is desirable that |Wi - (Wo + 2 × t1)| / Wi < 0.04. In other words, it is desirable that the difference between the axial width Wi of the inner ring 2 and this 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 flush when mounting this insulated rolling bearing, making it easier to use in a favorable design.

[0082] An example of a method for manufacturing this insulating rolling bearing will be described with reference to the flow chart of FIG.

[0083] [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.

[0084] [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.

[0085] The heat-shrinkable tube 10 can be made by irradiating a resin material containing a reinforcing material into a tubular shape with an electron beam to crosslink the resin material, then heating the tubular material to a predetermined high temperature, stretching the tubular material in the radial direction (or in the radial and axial directions), and then cooling the tubular material. In this case, the dimensions of the tubular material after stretching correspond to the dimensions of the tubing 10 before shrinking due to heating.

[0086] The resin material containing the reinforcing material improves the strength of the heat-shrinkable tube 10, prevents damage to the insulating coating 5 during the manufacture and installation of the rolling bearing 9, and suppresses wear and deformation of the insulating coating 5 during use. This makes it easier to maintain the insulating performance of the insulating coating 5.

[0087] As the reinforcing material, it is preferable to use a fiber material, such as glass fiber or carbon fiber, because it has good orientation.

[0088] The preferred proportion of the reinforcing material in the resin material varies depending on the type of reinforcing material used. If the proportion is too small, the strength-improving effect of the reinforcing material will not be substantially achieved. For this reason, it is desirable for the proportion to be 5% by mass or more, and more desirably 10% by mass or more. Examples include A3HG5 and A3WG6 from BASF. Note that as the amount of glass fiber contained in polyamide 66 increases, the tensile strength increases as shown in Table 1 below. In the table, glass fiber is abbreviated as "GF."

[0089]

[0090] On the other hand, the reinforcing material has the effect of preventing the shrinkage of the heat-shrinkable tube 10, and if there is too much, the shrinkage rate may be too low, making it difficult to attach the tube to the rolling bearing 9. A target shrinkage rate of the heat-shrinkable tube 10 of 5% or more is desirable. To ensure this shrinkage rate, if the reinforcing material is glass fiber, its proportion in the resin material is desirably 20% by mass or less. Furthermore, if the reinforcing material is carbon fiber, its proportion in the resin material is desirably 30% by mass or less.

[0091] The reinforcing material is preferably oriented in the axial direction within the heat-shrinkable tube 10. "Oriented in the axial direction" means that the average value of the angle indicated by the long side directions of the many fibers is closer to the axial direction than to the radial direction. It is preferable that the angle of the direction indicated by the average value of the angle with respect to the axial direction is less than 45 degrees, and the smaller this angle, the better.

[0092] When the heat-shrinkable tube 10 has the above-described orientation, the reinforcing material is aligned in the axial direction in the outer peripheral coating portion 5a (described later) of the insulating coating 5 formed by the heat-shrinkable tube 10. This makes it difficult for the heat-shrinkable tube to deform in the axial direction when the bearing is in use, and therefore makes it easier to maintain its shape.

[0093] 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.

[0094] In addition, the heat-shrinkable tube 10 is formed to have a diameter (φD ０ -φD １ ) / φD ０It is preferable to use a material having a radial shrinkage rate of 3% or less, which satisfies the condition of <0.03. 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.

[0095] Furthermore, the axial length W of the heat-shrinkable 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 by the heat-shrinkable tube 10 in the heat-shrinkable tube heating step described below. It is more preferable if the heat-shrinkable tube 10 after shrinking is long enough to reach part of the inner circumferential surface 1e of the outer ring 1, as this allows for the formation of the inner circumferential covering portion 5e. Specifically, the axial length W' of the heat-shrinkable tube 10 after shrinking preferably satisfies the relationship W' > W1 + 2 × W2 + 2 × W3 + 2 × W4, where W1 is the axial width of the outer peripheral surface 1a of the outer ring 1, W2 is the length along the arc of the pair of chamfered portions 1b of the outer ring 1, W3 is the radial width of the pair of axial end faces 1c of the outer ring 1, and W4 is the length along the arc of the pair of inner circumferential chamfered portions 1d of the outer ring 1, as shown in FIG. 6 . The axial length W′ after shrinkage is W′=W×(1−a / 100) where a (%) is the axial shrinkage rate of the heat-shrinkable tube 10 .

[0096] The thickness t of the heat-shrinkable tube 10 is set to be at least twice the arc radius R of the chamfered portion 1b. The thickness t of the heat-shrinkable tube 10 is slightly smaller than the thickness (t1) of the insulating coating. However, since the shrinkage rate of the heat-shrinkable tube 10 in the radial direction is very small and it may expand slightly due to axial shrinkage, in reality the thickness t is approximately equal to t1.

[0097] [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 60°C to 150°C.

[0098] 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. 7. Therefore, as shown in Fig. 8, 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.

[0099] Furthermore, the pair of jigs 11 preferably have protruding portions 11a for wrapping around and pressing down both axial ends of the heat-shrinkable tube 10 so as to cover portions of the pair of inner circumferential surfaces 1e of the outer ring 1 and form the inner circumferential covering portion 5e. The protruding portions 11a have curved surfaces that conform to the pair of inner circumferential chamfered portions 1d of the outer ring 1. However, the protruding portions 11a are formed so as not to interfere with and damage the cage 4.

[0100] In Fig. 8, 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. 3 that corresponds to the end surface covering portion 5c (see Fig. 2) is pressed down with the jig 11 shown in Fig. 8, 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.

[0101] 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 reduces the rotation of an electric motor, or the rotating shaft of an alternator), as shown in Figure 9. In Figure 9, the insulating rolling bearing is incorporated between the cylindrical inner periphery of a housing bore 14 formed in a non-rotating housing 13 and the outer periphery of the rotating shaft 12 located at the center of the housing bore 14.

[0102] 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.

[0103] 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.

[0104] In the above embodiment, as shown in Figure 2, an example has been described in which the axial width dimension of the outer ring 1 is set smaller than that 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. However, depending on the environment in which the insulated rolling bearing is installed, it is also possible for the axial width dimension of the outer ring 1 and the axial width dimension of the inner ring 2 to be the same (in other words, 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).

[0105] 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.

[0106] 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.

[0107] REFERENCE SIGNS LIST 1 outer ring 1a outer peripheral surface 1b chamfered portion 1c axial end face 1d inner peripheral chamfered portion 1e inner peripheral surface 2 inner ring 3 rolling element 5 insulating coating 5a outer peripheral coated portion 5b chamfered coated portion 5c end face coated portion 5d inner peripheral chamfered coated portion 5e inner peripheral coated portion 9 rolling bearing 10 heat shrinkable tube 11 jig 11a protruding portion 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 chamfer 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 glass transition temperature of the resin that makes up the heat-shrinkable tube (10) is 120°C or higher.

2. The electrically insulating rolling bearing according to claim 1, wherein the resin contains a reinforcing material, an additive, or both.

3. The insulating coating (5) has an inner diameter (φD) of 103% or less of the outer diameter (φD) of the outer ring (1). ０ 2. The insulating rolling bearing according to claim 1, wherein the heat-shrinkable tube (10) is heated and deformed.

4. An insulated rolling bearing as described in claim 1, wherein the insulating coating (5) has a pair of inner peripheral coating portions (5e) that wrap around from the pair of end surface coating portions (5c) and cover part of the inner peripheral surface (1e) of the outer ring (1).

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

6. A bearing preparation step of preparing 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) 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 axially outward direction, and a pair of axial end surfaces (1c) extending radially inward from the pair of chamfered portions (1b); and a heat-shrinkable tube arrangement step of arranging a heat-shrinkable tube (10) made of resin and having a glass transition temperature of 120°C or higher radially outward of the rolling bearing (9). After the heat-shrinkable tube arrangement step, the method for manufacturing an insulated rolling bearing includes a heat-shrinkable tube heating step of heating and deforming the heat-shrinkable tube (10) to form an insulating coating (5) having 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 face coating portions (5c) that cover the pair of axial end faces (1c) of the outer ring (1).

7. 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 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) 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 resin that constitutes the heat-shrinkable tube (10) contains a reinforcing material.

8. An insulating rolling bearing according to claim 7, wherein the reinforcing material comprises glass fiber, carbon fiber, or both.

9. An insulating rolling bearing according to claim 8, wherein the reinforcing material is glass fiber, and the proportion of the glass fiber in the heat-shrinkable tube is 20 mass % or less.

10. An insulating rolling bearing according to claim 8, wherein the reinforcing material is carbon fiber, and the proportion of the carbon fiber in the heat-shrinkable tube is 30 mass % or less.

11. An insulating rolling bearing according to claim 7, wherein the reinforcing material is oriented in the axial direction in the outer peripheral covering portion (5a).

12. The insulating coating (5) has an inner diameter (φD) of 103% or less of the outer diameter (φD) of the outer ring (1). ０ 8. The insulating rolling bearing according to claim 7, characterized in that the heat-shrinkable tube (10) having the insulating rolling bearing is heated and deformed.

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

14. An insulated rolling bearing according to claim 7, wherein the difference between the axial width (Wi) of the inner ring (2) and the sum (Wo + 2 × t1) of the axial width (Wo) of the outer ring (1) and the thickness (t1) of a pair of end face covering portions (5c) covering the pair of axial end faces (1c) is less than 4% of the axial width (Wi) of the inner ring (2).

15. A bearing preparation step for preparing a rolling bearing (9) having an outer ring (1), an inner ring (2) disposed 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 axially outer side, and a pair of axial end surfaces (1c) extending radially inward from the pair of chamfered portions (1b); and a heat-shrinkable tube arrangement step for arranging a heat-shrinkable tube (10) made of a resin containing a reinforcing material radially outside the rolling bearing (9). After the heat-shrinkable tube arrangement step, the method for manufacturing an insulated rolling bearing includes a heat-shrinkable tube heating step of heating and deforming the heat-shrinkable tube (10) to form an insulating coating (5) having 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 face coating portions (5c) that cover the pair of axial end faces (1c) of the outer ring (1).

Images