Insulated rolling bearing

Abstract

The present application provides an insulating rolling bearing capable of preventing adhesion to a shaft or the like and falling from an inner ring or the like while preventing electric corrosion. The insulating rolling bearing has an inner ring (2) and an outer ring made of steel material, a plurality of rolling bodies interposed between the inner ring and the outer ring, and a substantially cylindrical insulating bushing (10) fitted to an inner peripheral surface (2a) of the inner ring (2), the insulating bushing (10) has an insulating portion (8) made of a resin composition on an outer diameter side and a metal portion (9) on an inner diameter side, the insulating portion (8) and the metal portion (9) are separately configured, the metal portion (9) is a split bushing having an opening (9a) formed in a part in a circumferential direction, and the insulating portion (8) is a cylindrical member covering the opening (9a) of the split bushing from the outer diameter side.

Description

Technical Field

[0001] This invention relates to insulated rolling bearings. Background Technology

[0002] For example, insulated rolling bearings are known to insulate the rotating shafts of objects that may carry current, such as the rotating shafts of electric motors or refrigerant compressors. By using insulated rolling bearings, electrolytic corrosion can be prevented from occurring on the two raceway surfaces of the inner and outer rings and the rolling surfaces of the rolling elements.

[0003] For example, in the refrigerant compressor described in Patent Document 1, a resin sleeve made of resin material is provided between the auxiliary bearing of the auxiliary shaft portion, which is located further from the crankshaft drive portion than the crankshaft drive portion, and the crankshaft. This allows for the suppression of bearing damage caused by electrolytic corrosion with an inexpensive structure, improving the reliability of the refrigerant compressor, without using rolling bearings filled with conductive grease.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-40261 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the refrigerant compressor described in Patent Document 1, a resin sleeve is embedded into the inner circumferential surface of the inner ring by means of pressing or other methods. However, under actual operating conditions of repeated heating and cooling, there are concerns that the resin sleeve may become stuck to the crankshaft or detach from the inner ring. Furthermore, it has been considered to embed the same resin sleeve into the outer circumferential surface of the outer ring to achieve insulation, but there are concerns that the resin sleeve may become stuck to the outer ring or detach from the housing.

[0009] The present invention was made in view of the above circumstances, and its object is to provide an insulated rolling bearing that can prevent electrolytic corrosion while preventing seizing of the shaft or the like and detachment from the inner ring or the like.

[0010] Methods for solving problems

[0011] The insulating rolling bearing of the present invention comprises an inner ring and an outer ring made of steel, a plurality of rolling elements between the inner ring and the outer ring, and a generally cylindrical insulating bushing fitted with the inner circumferential surface of the inner ring or the outer circumferential surface of the outer ring. The insulating bushing is characterized in that it has an insulating portion made of a resin composition on the outer diameter side and a metal portion on the inner diameter side.

[0012] The insulating rolling bearing of the present invention is characterized in that the insulating portion and the metal portion are separately constructed. Furthermore, the insulating rolling bearing of the present invention is characterized in that the metal portion is a spliced ​​bushing with an opening (seam) formed in a portion of its circumference, and the insulating portion is a cylindrical member that covers the opening of the spliced ​​bushing from the outer diameter side.

[0013] The insulating rolling bearing of the present invention is characterized in that the outer peripheral surface of the insulating portion is a tapered shape that expands from one side of the axial direction to the other.

[0014] The insulating rolling bearing of the present invention is characterized in that the base resin of the resin composition of the insulating part is polyphenylene sulfide (PPS) resin, polyether ketone (PEK) resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) resin, or tetrafluoroethylene-ethylene copolymer (ETFE) resin.

[0015] The insulating rolling bearing of the present invention is characterized in that the metal part is made of carbon steel or stainless steel for mechanical structures.

[0016] Invention Effects

[0017] The insulated rolling bearing of the present invention includes a generally cylindrical insulating bushing that fits into the inner circumferential surface of the inner ring or the outer circumferential surface of the outer ring. This insulating bushing has an insulating portion made of a resin composition on the outer diameter side and a metal portion on the inner diameter side. Therefore, for example, when fitted into the inner diameter of the inner ring, by providing the resin insulating portion on the side contacting the inner circumferential surface of the inner ring and the metal portion on the side contacting the shaft, the shaft and the inner ring do not come into metal contact, thus preventing electrolytic corrosion. Furthermore, since the resin insulating portion does not contact the shaft, it also prevents the insulating portion from gripping the shaft.

[0018] Furthermore, the inner ring is made of steel, such as bearing steel, which has a small coefficient of linear expansion compared to resin materials. Therefore, in the high-temperature range of the operating environment, the insulation portion is positioned along the inner circumference of the inner ring. On the other hand, in the low-temperature range of the operating environment, although the insulation portion may shrink, the shrinkage of the resin is suppressed by the metal portion on the inner diameter side supporting the insulation portion from the inside. Thus, even under conditions of repeated heating and cooling, the insulating bushing can be prevented from detaching from the inner ring.

[0019] Furthermore, when the insulating bushing is fitted onto the outer diameter of the outer ring, the resin insulating portion does not contact the outer ring, thus preventing the insulating portion from clinging to the outer ring and preventing electrolytic corrosion. Additionally, on the high-temperature side of the operating environment, the insulating portion runs along the inner circumferential surface of the housing. On the other hand, on the low-temperature side of the operating environment, although the insulating portion may shrink, the shrinkage of the resin is suppressed by the metal portion on the inner diameter side supporting the insulating portion from the inside. Therefore, even under conditions of repeated heating and cooling, the insulating bushing can be prevented from detaching from the housing.

[0020] The insulating part and the metal part are constructed separately, thus increasing the degree of freedom in the shape of the insulating part and the metal part compared to a one-piece construction. Furthermore, the metal part is a spliced ​​bushing with an opening (seam) formed in a portion of its circumference, and the insulating part is an annular member that covers the opening of the metal part from the outer diameter side. Therefore, by forming the opening, the metal part can have a radially expanding elastic force, which can appropriately suppress the shrinkage of the insulating part. In addition, by covering the opening with the insulating part, electrolytic corrosion can be reliably prevented.

[0021] The outer peripheral surface of the insulation part is tapered from one side of the axial direction to the other, which makes it easy to manage the fitting of the inner ring and the insulation part, thereby enabling cost reduction.

[0022] The base resin of the resin composition for the insulation part is PPS resin, PEK-based resin, PFA resin, FEP resin or ETFE resin, thus exhibiting excellent heat resistance and chemical resistance. Attached Figure Description

[0023] Figure 1 This is an enlarged cross-sectional view of the insulated rolling bearing of the present invention.

[0024] Figure 2 yes Figure 1 Exploded perspective view of the insulating bushing, etc.

[0025] Figure 3 It includes exploded perspective views showing other forms of insulating bushings, etc.

[0026] Figure 4 It includes exploded perspective views showing other forms of insulating bushings, etc.

[0027] Figure 5 This is an axial sectional view of the test components of Comparative Examples 1 and 2.

[0028] Figure 6 This is a diagram showing a general outline of the pull-out force test.

[0029] Figure 7 This is a diagram showing a general outline of the power-on test.

[0030] Figure 8This is a photograph of Comparative Example 1 after the pull-out force test.

[0031] Figure 9 This is a graph comparing the manufacturing costs of the embodiments and comparative examples.

[0032] Figure 10 This is a graph comparing the manufacturing costs of the areas formed by ceramic spraying. Detailed Implementation

[0033] use Figure 1 One embodiment of the insulated rolling bearing of the present invention will be described. For example... Figure 1 As shown, the insulated rolling bearing 1 includes: a bearing body having an inner ring 2 and an outer ring 3 serving as raceways, and a plurality of balls (rolling elements) 4 located between the inner and outer rings; and an insulating bushing 10 fitted into the inner circumferential surface of the inner ring 2. The balls 4 are held at regular intervals by a retainer 5. The bearing space around the balls 4 is filled with grease 7, and the bearing space is sealed by a sealing member 6. The inner ring 2, outer ring 3, and balls 4 are made of steel. Examples of steel used in rolling bearings include bearing steel such as SUJ2, carburized steel, carbon steel for mechanical structures, cold-rolled steel, or hot-rolled steel.

[0034] exist Figure 1 In this bearing, the insulating bushing 10 is generally cylindrical, with an insulating portion 8 made of a resin composition on the outer diameter side and a metal portion 9 on the inner diameter side. In the insulated rolling bearing 1, the bearing body and the insulating bushing 10 are integrated by press-fitting, without the use of adhesives or the like. A shaft S is inserted into the shaft hole of the insulated rolling bearing 1, thereby making the shaft S, the insulating bushing 10, and the inner ring 2 a single unit. Figure 1 As shown, the insulating part 8 is located between the shaft S and the inner ring 2, thereby blocking the shaft current from flowing to the bearing body through the shaft S.

[0035] Reference Figure 2 The insulating bushing 10 is described in detail. Figure 2 (a) shows an exploded perspective view of the inner ring and insulating bushing. Figure 2 In (a), the insulating part 8 and the metal part 9 are separately constructed. The insulating part 8 is a cylindrical member with a specified wall thickness and is a molded body of the resin composition described later. The metal part 9 is a fitted bushing with an opening 9a formed in a portion of its circumference. Figure 2 In (a), the opening 9a is formed along the axial direction of the metal portion 9. Furthermore, the opening 9a may also be formed at a predetermined angle relative to the axial direction, extending from one end of the axial direction to the other. The predetermined angle is, for example, 1° to 30°, preferably 1° to 10°.

[0036] Regarding the assembly sequence of the insulated rolling bearing, firstly, the insulating part 8 of the cylindrical member is inserted into the inner circumferential surface 2a of the inner ring 2 with an interference fit. Then, the opening 9a is narrowed so that the metal part 9 is inserted into the inner circumferential surface 8a of the insulating part 8 while elastically deforming, thereby obtaining the insulating bushing.

[0037] exist Figure 2 (b) shows a radial cross-sectional view of the state in which the insulating bushing is embedded. The metal part 9 has elasticity in the direction that presses the insulating part 8 against the inner circumferential surface 2a of the inner ring 2, and by means of this elasticity, the metal part 9 is fixed to the inner circumferential surface 8a of the insulating part 8. Preferably, the opening 9a of the metal part 9 is formed in a way that appropriately exerts the elasticity that expands radially outward, while being able to stably support the shaft. For example, it is formed such that the two separated ends are recessed within a range of ±θ based on the center position of the opening 9a. This range refers to the range of ±θ based on the center position of the opening 9a (the center position in the circumferential direction between the end faces of each end) in the metal part 9, which is set to 0° in circumferential position and measured in terms of the central angle. This range of ±θ is preferably a range of ±10°, and more preferably a range of ±5°.

[0038] like Figure 2 As shown in (b), the insulating portion 8 covers the opening 9a of the metal portion 9 from the outer diameter side, thereby ensuring insulation. Depending on the operating temperature environment, the insulating portion 8 may expand or contract, but the metal portion 9 has an elasticity that expands radially outward. Utilizing this elasticity, the insulating portion 8 is pressed against the inner circumferential surface 2a of the inner ring 2, thus suppressing the expansion and contraction of the insulating portion 8 and maintaining the dimensional stability of the inner diameter of the insulated rolling bearing. As a result, the shaft can be stably supported regardless of the temperature environment.

[0039] From a strength perspective, the material of the metal part is preferably molten metal, and more preferably ferrous molten metal. As ferrous metal, general structural carbon steel (SS400, etc.), mechanical structural carbon steel (S45C, etc.), stainless steel (SUS303, SUS316, etc.) can be used. Furthermore, these ferrous metals can be plated with zinc, nickel, copper, etc. There are no particular limitations on the wall thickness of the metal part; for example, it is 0.5mm to 5mm, and more preferably 1mm to 3mm. Figure 2 The assembled bushing can be obtained by bending a metal plate of a specified wall thickness.

[0040] Furthermore, there is no particular limitation on the wall thickness of the insulating part; for example, it can be 0.5 mm to 5 mm, and more preferably 1 mm to 3 mm. Regarding the wall thickness of the insulating part and the wall thickness of the metal part, either one can be thicker, or they can be of equal thickness.

[0041] Examples of base resins used in the resin composition for insulation include PEK-based resins, polyacetal (POM) resins, PPS resins, injection-moldable thermoplastic polyimide resins, polyamide-imide (PAI) resins, polyamide (PA) resins, and injection-moldable fluoropolymers. These resins can be used alone or as a blend of two or more polymer alloys. Among these resins, PPS resins, PEK-based resins, PFA resins, FEP resins, and ETFE resins are preferred due to their excellent chemical resistance and heat resistance. Furthermore, examples of PEK-based resins include polyetheretherketone (PEEK) resins, polyetherketone (PEK) resins, and polyetherketone etherketone ketone (PEKEKK) resins.

[0042] In addition, additives can be appropriately added to the above-mentioned base resin as needed. As additives, non-conductive reinforcing materials such as glass fiber, aramid fiber, potassium titanate whiskers, and titanium dioxide whiskers can be added to improve creep resistance.

[0043] The coefficient of linear expansion of the resin composition used for insulation is preferably 1×10⁻⁶. -5 / ℃~10×10 -5 / ℃, more preferably 1×10 -5 / ℃~5×10 -5 / ℃. Furthermore, there are no particular limitations on the relationship between the linear expansion coefficient of the material of the metal part and the material of the insulating part; for example, it is preferable that the linear expansion coefficient of the material of the insulating part is greater than that of the material of the metal part.

[0044] There are no particular limitations on the molding method for the insulation part; compression molding, extrusion molding, injection molding, etc., can be used. In the case of injection molding, various raw materials are melted and mixed to form molding pellets, which are then used to mold the pellets into the specified shape using injection molding.

[0045] exist Figure 3 Other forms of the insulating bushings involved in this invention are shown. Figure 3 The insulating bushing 13 shown is Figure 2 Compared to the insulating bushing 10, the structure of the insulating part is different. Figure 3 (a) is an exploded perspective view of the inner ring and insulating bushing. Figure 3 (b) is an axial sectional view of the insulating bushing.

[0046] exist Figure 3 In (a), the insulating part 11 and the metal part 12 are separately constructed. The metal part 12 is a spliced ​​bushing with a separate opening 12a formed in a circumferential direction, and is connected with... Figure 2 (a) has the same structure as the metal part 9. On the other hand, as... Figure 3As shown in (b), the inner circumferential surface 11a of the insulating portion 11 is a cylindrical surface parallel to the axial direction, and the outer circumferential surface 11b is a conical surface that expands in diameter from one side of the axial direction to the other. The wall thickness of the insulating portion 11 increases from one side of the axial direction to the other, with each end of the axial direction becoming the thinnest and thickest part of the wall. The difference in wall thickness between the thinnest and thickest parts is, for example, 0.5 mm to 2 mm. Furthermore, in this configuration, it is preferable that the wall thickness of the insulating portion 11 is thicker than the wall thickness of the metal portion 12, that is, it is preferable that the wall thickness of the thinnest part of the insulating portion 11 is thicker than the wall thickness of the metal portion 12.

[0047] Regarding the assembly sequence of the insulated rolling bearing, firstly, the insulating portion 11 of the approximately cylindrical member is inserted into the inner circumferential surface 2a of the inner ring 2. At this time, if the outer circumferential surface 11b of the insulating portion 11 is tapered, the inner ring 2 can be inserted even if there are dimensional differences. Therefore, with... Figure 2 Compared to the previous configuration, the interference fit of the inner diameter of the inner ring 2 and the outer diameter of the insulating part 11 can be easily managed. Then, while elastically deforming the metal part 12, it is embedded into the inner circumferential surface 11a of the insulating part 11, thereby obtaining an insulating bushing.

[0048] exist Figure 4 This shows another form of insulating bushing. Figure 4 This is an exploded perspective view of the inner ring and insulating bushing. (See diagram below.) Figure 4 As shown, the insulating bushing 16 is a bushing on the outer peripheral surface of the cylindrical metal part 15, on which the insulating part 14, which is made of ceramic sprayed film, is formed.

[0049] As a base material for ceramics, metal oxides such as alumina, magnesium oxide, zirconium oxide, and titanium dioxide, as well as silicon nitride, silicon carbide, or mixtures thereof, are used. The composition of the sprayed material can be, for example, set to an alumina content of 95.0–98.5% by mass and a content of other metal oxides of 1.5–5.0% by mass. Furthermore, if the alumina content is set to 97.0% by mass or more and the content of metal oxides such as zirconium oxide is set to 1.5–2.5% by mass, strength and toughness can be improved along with insulation.

[0050] As a spraying method, known plasma spraying methods such as atmospheric pressure plasma spraying carried out in the atmosphere can be used. Alternatively, known spraying methods such as powder flame spraying and high-speed gas flame spraying can also be used.

[0051] The thickness of the ceramic sprayed coating is preferably 30μm to 300μm. If it is less than 30μm, sufficient insulation may not be obtained, and if it exceeds 300μm, the manufacturing cost tends to increase.

[0052] have Figure 4The insulating rolling bearing with an insulating bushing shown is an insulating rolling bearing in which a metal portion 15, with a ceramic-coated outer circumferential film, is inserted into the inner circumferential surface 2a of an inner ring 2 with an interference fit. The interference fit is set considering the difference in linear expansion coefficients between the material of the inner ring 2 and ceramic. Typically, the inner ring is made of bearing steel, which has a higher linear expansion coefficient than ceramic. Therefore, the interference fit is set to a value that does not disappear even if the inner ring expands at high temperatures within the operating environment. On the other hand, at low temperatures within the operating environment, the inner ring 2 shrinks, thus becoming attached to the metal portion 15. Therefore, even under thermal shock testing, the insulating bushing 16 can be prevented from detaching from the inner ring 2. Furthermore, with this configuration, special surface treatment of the inner circumferential surface of the metal portion 15 is not required, nor is resin injection molding necessary. In addition, since ceramic is coated on the outer circumferential surface of the metal portion 15, cost reduction can be achieved compared to coating on the inner circumferential surface. Furthermore, since the shaft does not come into metal-to-metal contact with the inner ring, it maintains insulation and has the effect of preventing electrolytic corrosion.

[0053] Furthermore, in order to achieve insulation properties, a method of directly spraying ceramics onto the inner circumferential surface of the inner ring has been considered. However, since the spraying method needs to be taken into account, the size and shape of the spraying material that can be sprayed onto the inner circumferential surface are limited, which tends to increase costs.

[0054] The structure of the insulating rolling bearing of the present invention is not limited to the above. Figures 1-4 The composition, for example, in Figure 1 The invention illustrates a ball bearing, but the insulated rolling bearing of the present invention can also be applied to tapered roller bearings, cylindrical roller bearings, self-aligning roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust self-aligning roller bearings, etc.

[0055] The above Figures 1-4 The insulated rolling bearing employs a configuration where an insulating bushing is fitted into the inner circumferential surface of the inner ring, but is not limited to this. For example, an insulating bushing 10 can also be fitted into the outer circumferential surface of the outer ring (see reference). Figure 2 ), Insulating bushing 13 (refer to) Figure 3 ), Insulating bushing 16 (refer to) Figure 4 The bearing is obtained by means of [various methods]. In the installed state, the metal part of the insulating bushing is fitted in contact with the outer peripheral surface of the outer ring, and the insulating part of the insulating bushing is fitted in contact with the inner peripheral surface of the housing. In this case, it is also possible to prevent the insulating part from closing towards the outer ring and from falling off the housing due to shrinkage of the insulating part.

[0056] In addition, Figure 2 and Figure 3In this configuration, the insulating part and the metal part are separately constructed. However, the resin composition can also be inserted into the outer peripheral surface of the metal part, or a resin coating can be applied using various coating methods, thus integrally constructing the resin molded body or resin coating with the metal part. Furthermore, in this case, it is preferable to form the metal part as an integral bushing. Alternatively, other layers can be sandwiched between the insulating part and the metal part.

[0057] The insulated rolling bearings of the present invention can be used, for example, as anti-electro-optic bearings in electric motors of refrigerant compressors and electric motors. Furthermore, as shown in the embodiments described later, they exhibit sufficient pull-out force even in thermal shock tests ranging from -30°C to 160°C, thus making them particularly suitable for use in a wide temperature range from low to high temperatures. For example, they are suitable for use in two temperature zones: below 0°C and above 100°C.

[0058] Example

[0059] Example 1

[0060] A cylindrical component was obtained by injection molding of PEEK resin. This cylindrical component was then fitted onto the inner circumferential surface of an inner ring made of SUJ2 material. Finally, a SUS304 fitting bushing was fitted onto the inner circumferential surface of the cylindrical component to obtain… Figure 2 The experimental component is shown in the diagram.

[0061] Example 2

[0062] PEEK resin was injection molded to obtain a cylindrical component with a conical outer circumference. This cylindrical component was then fitted onto the inner circumference of an inner ring made of SUJ2 material. Subsequently, a SUS304 bushing was fitted onto the inner circumference of the cylindrical component, resulting in… Figure 3 The test component is shown in the diagram.

[0063] Example 3

[0064] An insulating bushing with a ceramic-coated film was obtained by atmospheric plasma spraying of the outer circumferential surface of a cylindrical component made of austenitic stainless steel. Alumina was used as the spraying material.

[0065] Comparative Example 1

[0066] PEEK resin was injection molded to obtain an insulating bushing consisting solely of an insulating portion. This insulating bushing was then fitted onto the inner circumferential surface of an inner ring manufactured in SUJ2, resulting in... Figure 5 The test component in the form shown in (a).

[0067] Comparative Example 2

[0068] After applying an amalgam treatment to the inner circumferential surface of a cylindrical component made of SUS304 to create a finely textured surface, a PPS resin insert is molded onto the inner circumferential surface to obtain an insulating bushing with an injection-molded layer. This insulating bushing is then fitted onto the inner circumferential surface of an inner ring made of SUJ2, resulting in... Figure 5 (b) shows the shape of the test component.

[0069] Table 1 shows the coefficients of linear expansion of the materials, etc., of the components used in Examples 1-3 and Comparative Examples 1-2.

[0070] [Table 1]

[0071]

[0072] <Pull-out force test (removal force test)>

[0073] Products with S45 shafts inserted into the shaft holes of each test component were placed in a constant temperature bath and subjected to repeated thermal shocks. The thermal shocks were performed in sets of 200 cycles, one at 160°C for 30 minutes and the other at -30°C for 30 minutes. After 200 cycles, the shafts were removed, and a pull-out force test was conducted on the test component under the following conditions.

[0074] Measuring instrument: Autograph

[0075] Measurement speed: 5 mm / s

[0076] Judgment criteria: 200N or above

[0077] A summary of the pull-out force test is shown below. Figure 6 .like Figure 6 As shown, the test member 17, after being subjected to thermal shock, is placed on the receiving fixture 18, and the pressing fixture 19 is abutted against the end face of the insulating bushing 17b, which is fitted with the inner circumferential surface of the inner ring 17a of the test member 17. A load is applied to the pressing fixture 19 in the direction of the arrow, and the peak value of the load is measured until the insulating bushing 17b falls off to the receiving fixture 18. A load of 200N or more is considered acceptable, and the number of acceptable tests is shown in Table 2.

[0078] <Electrification Test>

[0079] A general outline of the power-on test is shown below. Figure 7 .like Figure 7 As shown, an iron shaft S is inserted into the test member 17, and the terminals of the insulation resistance tester 20 are abutted against the shaft S and the outer circumferential surface of the inner ring 17a of the test member 17. The insulation resistance value is measured under the following conditions. In each test example, three samples are measured, and their average values ​​are shown in Table 2.

[0080] Applied voltage: DC500V

[0081] Temperature: 15~25℃ (room temperature)

[0082] Humidity: 40-60%

[0083] [Table 2]

[0084]

[0085] As shown in Table 2, in Examples 1-3 and Comparative Example 2, all test numbers were satisfactory, and the pull-out force was above 1000 N, maintaining sufficient pull-out force even after the thermal shock test. Furthermore, no axial clamping was observed in Examples 1-3 and Comparative Example 2. However, in Comparative Example 2, at high temperatures, the shape constraint of the metal portion on the outer diameter side caused volume expansion and escape towards the inner diameter side, potentially resulting in a smaller inner diameter. In Examples 1-3, the insulating portion was clamped by the inner ring and the metal portion, and the metal portion was energized in the direction of compressing the inner ring, thus suppressing volume changes in the insulating portion associated with temperature variations, resulting in superior dimensional stability of the inner diameter.

[0086] On the other hand, in Comparative Example 1, after the thermal shock test, the insulating bushing engaged with the shaft in all test numbers, resulting in the insulating bushing and shaft detaching together from the inner ring (see reference). Figure 8 Of the 5 tests, 1 passed. Of the remaining 4 failures, 3 resulted in the insulation bushing shrinking, causing the interference fit between the inner ring and the insulation bushing to disappear, leading to the insulation bushing and shaft detaching from the inner ring due to their own weight. Furthermore, as... Figure 8 As shown, cracks were also confirmed in the insulating bushing.

[0087] In all the examples, the shaft did not make metal contact with the inner circumferential surface of the inner ring, demonstrating insulation.

[0088] Next, the manufacturing costs of other insulating bushings were numericalized when the manufacturing cost of the insulating bushing of Comparative Example 2 was set to 1. The results are shown below. Figure 9 .

[0089] like Figure 9As shown, the insulating bushing of Comparative Example 2 requires special surface treatment and is injection molded, thus increasing the cost compared to others. On the other hand, the metal and insulating parts of the insulating bushings of Examples 1 and 2 are composed of a composite bushing and a resin cylindrical member, requiring no special surface treatment or injection molding, thus significantly reducing manufacturing costs. In particular, in Example 2, the outer peripheral surface of the resin cylindrical member is conical, allowing it to be inserted into the inner ring even with dimensional differences, further reducing manufacturing costs. Furthermore, although the insulating bushing of Example 3 requires ceramic plating, the plating is applied to the outer peripheral surface, thus reducing manufacturing costs compared to plating on the inner peripheral surface. For example, in ceramic plating, if the manufacturing cost for plating on the inner peripheral surface is set to 1, the manufacturing cost for plating on the outer peripheral surface is approximately 0.4 (refer to...). Figure 10 ).

[0090] As described above, the insulated rolling bearing of the present invention can prevent seizing towards the shaft and detachment from the inner ring even over a wide temperature range, maintaining dimensional stability and thus stably supporting the shaft. Furthermore, it enables cost reduction of the insulated rolling bearing.

[0091] Industrial availability

[0092] The insulating rolling bearing of the present invention can prevent electrolytic corrosion while preventing seizing towards the shaft or falling off from the inner ring, and therefore can be widely used as an anti-electrolytic corrosion bearing for supporting the shaft of an electric motor or a refrigerant compressor.

[0093] Explanation of reference numerals in the attached figures

[0094] 1. Insulated rolling bearing

[0095] 2 Inner ring

[0096] 3 Outer ring

[0097] 4 balls

[0098] 5. Holder

[0099] 6 Sealing components

[0100] 7. Lubricating Grease

[0101] 8 Insulation Part

[0102] 9 Metal Department

[0103] 10 Insulating bushings

[0104] 11 Insulation Part

[0105] 12 Metal Department

[0106] 13 Insulating bushings

[0107] 14 Insulation section

[0108] 15 Metal Department

[0109] 16 Insulating bushings

[0110] 17 Test Components

[0111] 18 Receiving clamps

[0112] 19 Pressing clamps

[0113] 20 Insulation Resistance Tester

[0114] S-axis

Claims

1. An insulated rolling bearing comprising an inner ring and an outer ring made of steel, a plurality of rolling elements between the inner ring and the outer ring, and a generally cylindrical insulating bushing fitted with the inner circumferential surface of the inner ring or the outer circumferential surface of the outer ring, characterized in that, The insulating bushing has an insulating portion made of a resin composition on the outer diameter side and a metal portion on the inner diameter side, the insulating portion and the metal portion being separately constructed. The metal part is a spliced ​​bushing with an opening formed in a circumferential direction, and the insulating part is a cylindrical member that covers the opening of the spliced ​​bushing from the outer diameter side. The outer circumferential surface of the insulating part is a tapered shape that expands from one side to the other in the axial direction.

2. The insulated rolling bearing according to claim 1, characterized in that, The base resin of the resin composition of the insulating part is polyphenylene sulfide resin, polyether ketone resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, or tetrafluoroethylene-ethylene copolymer resin.

3. The insulated rolling bearing according to claim 1, characterized in that, The metal part is made of carbon steel or stainless steel for mechanical structures.

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