Manufacturing method for insulating rolling bearing

Abstract

To provide a manufacturing method for an insulating rolling bearing comprising a bearing ring with high mechanical accuracy.SOLUTION: A manufacturing method for an insulating rolling bearing 100 comprises grinding a groove shoulder peripheral surface 13e on both axial sides of a raceway groove of a metal intermediate product 21 that has been turning-machined into a ring shape with the raceway groove and then heat treated. The intermediate product 21 is held in an insert mold using a ground groove piece peripheral surface 13e as a reference, and a resin layer 17 is insert-molded onto the peripheral surface and an axial end surface. Each of the resin layer 17 insert-molded onto the peripheral surface and the resin layer 17 insert-molded onto the axial end surface is ground to form a raceway ring.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an insulating rolling bearing. [Background technology]

[0002] For example, in bearings used in motors, generators, etc., if a discharge occurs between the rolling elements and the outer ring raceway surface, or between the rolling elements and the inner ring raceway surface, electrolytic corrosion may occur in the discharged area, significantly affecting the bearing life.For example, Patent Document 1 discloses an insulated rolling bearing that specifies the components of the resin layer composition of the resin layer formed on the outer peripheral surface of the outer ring, etc., thereby achieving both the heat dissipation properties and mechanical strength of the resin layer while maintaining good moldability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 202651 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the insulated rolling bearing described in Patent Document 1, when insert-molding the resin layer into the raceway, it was difficult to manufacture the resin layer with the dimensional tolerances in the μm range required for the bearing.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing an insulating rolling bearing having a raceway with high mechanical precision. [Means for solving the problem]

[0006] The present invention comprises the following configurations. (1) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface being on the opposite side to the raceway groove, the resin layer comprising: grinding a raceway groove-side peripheral surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the intermediate product is held in an insert mold using the ground raceway groove side circumferential surface as a reference, and the resin layer is insert-molded onto the anti-raceway groove side circumferential surface and the axial end surface of the intermediate product, respectively; the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings. (2) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface and the axial end face of the raceway groove, the a raceway groove-side circumferential surface and an axial end surface of a metal intermediate product machined into a ring shape having the shape of the raceway groove are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the raceway groove-side circumferential surface and the axial end surface, the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings. (3) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface and the axial end face of the raceway groove, the grinding the peripheral surface opposite the raceway groove side and the axial end surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the raceway groove-side circumferential surface and the axial end surface of the intermediate product are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the anti-raceway groove-side circumferential surface and the axial end surface, respectively. Manufacturing method for insulated rolling bearings. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for manufacturing an insulating rolling bearing provided with a raceway ring having high mechanical precision. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a partial cross-sectional view of an insulating rolling bearing. [Figure 2] FIG. 2 is a process explanatory diagram showing the procedure for forming an outer ring having no resin layer, and showing an assembly in which an inner ring and balls are attached to the formed outer ring. [Figure 3] FIG. 3 is a process explanatory diagram showing the procedure for forming the outer ring of the insulating rolling bearing of the first embodiment, and showing an assembly in which an inner ring and balls are assembled to the formed outer ring. [Figure 4] FIG. 4 is an explanatory diagram that schematically shows the thickness distribution of the resin layer when the inner diameter surface of the intermediate product is not ground and when it is ground before insert molding. [Figure 5] FIG. 5 is a process explanatory diagram showing the procedure for forming the outer ring of the insulating rolling bearing of the second embodiment, and showing an assembly in which an inner ring and balls are assembled to the formed outer ring. [Figure 6] FIG. 6 is a process explanatory diagram showing the procedure for forming the outer ring of the insulating rolling bearing of the third embodiment, and showing an assembly in which an inner ring and balls are assembled to the formed outer ring. [Figure 7] FIG. 7 is a schematic cross-sectional view of an insert molding die. [Figure 8] FIG. 8 is a partial cross-sectional view showing a configuration example of the insert molding die of the first modification. [Figure 9]FIG. 9 is a partial cross-sectional view showing a configuration example of an insert molding die according to the second modification. [Figure 10] FIG. 10 is a partial cross-sectional view showing a configuration example of an insert molding die according to the third modification. [Figure 11] FIG. 11 is a process explanatory diagram showing the procedure for forming the outer ring of the insulating rolling bearing of the fourth embodiment, and showing an assembly in which an inner ring and balls are assembled to the formed outer ring. [Figure 12] FIG. 12 is a process explanatory diagram showing the procedure for forming the outer ring of the insulating rolling bearing of the fifth embodiment, and showing an assembly in which an inner ring and balls are assembled to the formed outer ring. [Figure 13] FIG. 13 is a partial cross-sectional view of another insulating rolling bearing. [Figure 14] FIG. 14 is a schematic cross-sectional view of the insert molding die. [Figure 15] FIG. 15 is a cross-sectional view showing an example of the configuration of an insert molding die according to the fourth modification. [Figure 16] FIG. 16 is a partial cross-sectional view showing a configuration example of an insert molding die according to the fifth modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, an insulating rolling bearing according to the present invention will be described using a deep groove ball bearing as an example, but the type of bearing is not limited to this. For example, other types of bearings such as axial bearings, thrust bearings, roller bearings, and multiple-row bearings may also be used.

[0010] <Configuration of insulated rolling bearings> FIG. 1 is a partial cross-sectional view of an insulated rolling bearing 100. The insulated rolling bearing 100 comprises an inner ring 11, an outer ring 13, and a plurality of balls (rolling elements) 15. The inner ring 11 and the outer ring 13 are made of a metal such as steel, and the balls 15 are made of steel or ceramics. An inner ring raceway groove (raceway groove) 11a is formed on the outer peripheral surface of the inner ring 11, and an outer ring raceway groove 13a is formed on the inner peripheral surface of the outer ring 13. The plurality of balls 15 are arranged to roll freely between the inner ring raceway groove (raceway groove) 11a and the outer ring raceway groove 13a.

[0011] An electrically insulating resin layer 17 is formed over the entire circumference of the outer ring 13 on the counter-raceway groove side circumferential surface (circumferential surface) 13b opposite the outer ring raceway groove 13a and on both axial end faces 13c at both axial ends. Groove shoulders 13d are formed at both axial ends of the outer ring raceway groove 13a, protruding radially inward. The groove shoulders 13d have groove shoulder inner circumferential surfaces (groove shoulder circumferential surfaces) 13e at their protruding tips. The resin layer 17 is also formed from the axial end faces 13c, wrapping around inward in the axial direction, up to a portion of the outer periphery of a groove shoulder end face 13f on the axial outside of the groove shoulder 13d. In other words, the resin layer 17 is formed to cover the counter-raceway groove side circumferential surface 13b and the axial end faces 13c, which are the outer periphery of the outer ring 13.

[0012] Examples of resins that can be used to form the resin layer 17 include epoxy resin, fluororesin, and polyamide. A curing agent may be added to a resin film made of epoxy resin or polyamideimide resin. The thickness of the resin layer 17 is, for example, 0.5 mm or more, with a minimum resin thickness of 0.3 mm. Depending on the conditions, the thickness may be 2 mm or more.

[0013] <Manufacturing method for insulated rolling bearings> Next, an example of a procedure for forming the outer ring 13 from a metal intermediate member prepared in advance and assembling it together with the inner ring 11 and balls 15 to form the insulating rolling bearing 100 will be described in order.

[0014] First, a general procedure for assembling a ball bearing will be described. In the following description, the same or equivalent parts as those shown in Figure 1 will be designated by the same reference numerals, and their description will be omitted or simplified.

[0015] Figure 2 is a process diagram illustrating the procedure for forming an outer ring without a resin layer, and the assembly in which an inner ring and balls are assembled to the formed outer ring. First, a metal intermediate product 21 is prepared (ST1), formed by turning or other processes into a ring shape that conforms to the shape of the outer ring 13 shown in Figure 1. The intermediate product 21 has a groove shape that will become the outer ring raceway groove 13a, and groove shoulder shapes on both sides of the groove shape that are similar to the groove shoulders 13d of the outer ring 13. This intermediate product 21 is then subjected to heat treatment such as quenching and annealing (ST2).

[0016] Then, axial end faces 21a (top and bottom faces shown in FIG. 2) on both axial sides of ring-shaped intermediate product 21 are ground (ST3). In FIG. 2 and the process explanatory diagrams described below, the position of the grinding surfaces is indicated by dashed lines. Furthermore, groove 21c and counter-raceway groove side circumferential surface 21b, which is the outer peripheral surface of intermediate product 21 opposite groove 21c, are ground (ST4, ST5). In intermediate product 21 obtained in this manner, counter-raceway groove side circumferential surface 21b becomes counter-raceway groove side circumferential surface 13b, which is the outer peripheral surface of outer ring 13, and groove 21c becomes outer ring raceway groove 13a of outer ring 13. A ball bearing is completed by assembling outer ring 13, inner ring 11, and balls 15 formed from this intermediate product 21.

[0017] (First embodiment) Next, a method for manufacturing the insulated rolling bearing 100 of the first embodiment in which the resin layer 17 is formed on the outer ring 13 of the above-mentioned ball bearing will be described. In the following description, for the sake of simplicity, the parts of the intermediate product 21 corresponding to the outer ring 13 (outer ring raceway groove 13a, outer peripheral surface 13b on the side opposite the raceway groove, axial end face 13c, groove shoulder 13d, etc. shown in FIG. 1) will be designated by the same reference numerals as those used for the respective parts of the outer ring 13.

[0018] 3 is a process explanatory diagram showing the procedure for forming the outer ring 13 of the insulated rolling bearing 100 of the first embodiment, and showing an assembly in which the inner ring 11 and balls 15 are assembled to the formed outer ring 13. Steps ST11 to ST14 shown in FIG. 3 are the same as steps ST1 to ST4 for processing the intermediate product 21 shown in FIG. 2. In this embodiment, groove shoulder inner peripheral surfaces 13e of groove shoulders 13d on both axial sides of the outer ring raceway groove 13a (groove 21c), which constitute the inner peripheral surface of the intermediate product 21, are ground (ST15), and then groove 21c is ground (ST16). The grinding of groove shoulder inner peripheral surfaces 13e and grinding of groove 21c described above may be performed simultaneously.

[0019] Next, a resin layer 17 is insert-molded around the entire circumference of the ring on the counter-raceway groove side circumferential surface 13b of the intermediate product 21, the axial end face 13c, and the region from the axial end face 13c to the axially inner groove shoulder end face 13f (ST17). This insert molding can be performed using a commonly known procedure. For example, the intermediate product 21 is placed in the cavity of an insert molding die 25, and heated resin material is injected into the gap between the mold surface that faces the counter-raceway groove side circumferential surface 13b of the intermediate product 21, the axial end face 13c, and the region from the axial end face 13c to the groove shoulder end face 13f, and then solidified.

[0020] Generally, the resin layer 17 insert-molded onto the surface of the insert material (intermediate product 21) may have variations in thickness after resin formation. Therefore, in the procedure for forming the intermediate product 21 of this embodiment, the groove shoulder inner peripheral surface 13e (also simply referred to as the inner diameter surface) of the intermediate product 21 is ground before insert molding, and the resin layer 17 is insert-molded using this inner diameter surface as a reference surface. This has the effect of making the thickness of the formed resin layer 17 uniform around the circumference.

[0021] 4 is an explanatory diagram schematically showing the thickness distribution of the resin layer 17 when the inner diameter surface of the intermediate product 21 is ground and when it is ground before insert molding. When the inner diameter is not ground, the radial cross-sectional shape of the inner peripheral surface (groove shoulder inner peripheral surface 13e) of the intermediate product 21 is likely to be elliptical, which may cause misalignment with the insert molding die 25. On the other hand, when the inner diameter is ground, the radial cross-sectional shape of the inner peripheral surface (groove shoulder inner peripheral surface 13e) of the intermediate product 21 becomes closer to a perfect circle, which reduces misalignment with the insert molding die 25. As a result, the resin layer 17 obtained after insert molding has a uniform thickness.

[0022] Next, the resin layer 17 formed on the axial end face 13c of the intermediate product 21 is ground (ST18). Similarly, the resin layer 17 formed on the counter-race groove side circumferential surface 13b of the intermediate product 21 is ground (ST19). In this way, even if the thickness of the resin layer 17 formed on the axial end face 13c and the counter-race groove side circumferential surface 13b of the intermediate product 21 after insert molding is uneven, grinding the formed resin layer 17 allows the resin layer 17 to be finished with high dimensional accuracy. The resin layer 17 formed on the counter-race groove side circumferential surface 13b may be centerless ground, for example, using the outer diameter surface of the intermediate product 21 as the reference surface, or may be ground using the inner diameter surface as the reference surface. As a result, it is possible to manufacture an insulating rolling bearing 100 with highly accurate radial and axial dimensional tolerances, which enables the insulating rolling bearing 100 to be fitted with a mating member with high precision and maintain good electrical insulation.

[0023] It is preferable to use a grinding stone that is porous and has gaps between the abrasive grains contained in the grinding stone for grinding the resin layer 17. By using such a porous grinding stone, clogging of the grinding stone with resin during resin grinding can be prevented, and the life of the grinding stone can be extended.

[0024] Furthermore, the procedure for forming the outer ring 13 in this embodiment involves resin insert molding on a typical finished outer ring alone, so existing production equipment can be used as is with only a partial addition of a process. In other words, there is no need to significantly modify the production equipment, helping to keep equipment costs down.

[0025] (Second embodiment) The procedure for forming the outer ring in the second embodiment is modified such that the grinding process for the outer ring raceway groove 13a in the first embodiment is performed after insert molding rather than before insert molding.

[0026] Figure 5 is a process explanatory diagram showing the procedure for forming the outer ring 13 of the insulated rolling bearing 100 of the second embodiment, and showing an assembly in which the inner ring 11 and balls 15 are assembled to the formed outer ring 13. Steps ST21 to ST24 and ST26 to ST28 shown in Figure 4 are similar to the processing steps ST11 to ST14 and ST16 to ST19 of the intermediate product 21 shown in Figure 3. In this embodiment, groove grinding step ST29 is performed after resin grinding (ST27, ST28) following insert molding (ST26).

[0027] According to this embodiment, after insert molding, by performing resin grinding processing (ST28) on the anti-raceway groove side circumferential surface 13b of the intermediate product 21 and then grinding processing (ST29) on the outer ring raceway groove 13a, it is possible to achieve high precision of concentricity between the outer ring raceway groove 13a and the surface of the resin layer 17 on the anti-raceway groove side circumferential surface 13b.

[0028] (Third embodiment) In the procedure for forming the outer ring in the third embodiment, the inner diameter grinding (ST25) in the second embodiment is omitted. Fig. 6 is a process explanatory diagram showing the procedure for forming the outer ring 13 of the insulating rolling bearing 100 of the third embodiment, and an assembly in which the inner ring 11 and balls 15 are assembled to the formed outer ring 13. Steps ST31 to ST38 shown in Fig. 6 are the same as the processing steps ST21 to ST24 and ST26 to ST29 of the intermediate product 21 shown in Fig. 5. In this embodiment, the inner diameter grinding (ST25) of the second embodiment shown in Fig. 5 is omitted.

[0029] In this embodiment, the inner diameter grinding (ST25) is omitted, and instead the intermediate product 21 is centered and fixed to the insert molding die 27 for insert molding. 7 is a schematic cross-sectional view of the insert molding die 27. The insert molding die 27 for insert molding the resin layer 17 includes an outer diameter side die 31, an inner diameter side die 33, a width presser upper die 35, and a width presser lower die 37. The outer diameter side die 31 is arranged so as to cover the outer diameter side of the intermediate product 21 which will become the outer ring 13. The inner diameter side die 33 is arranged at the ring center on the inner diameter side of the intermediate product 21. The width presser upper die 35 and the width presser lower die 37 clamp the axial end faces of the intermediate product 21 in the axial direction (width direction) of the ring, thereby centering the intermediate product 21 in the axial direction within the insert molding die 27.

[0030] The insert molding die 27 also includes an inner diameter chucking mechanism 29 that chucks the outer ring raceway groove 13a, which is the inner peripheral surface of the intermediate product 21, by pressing it radially outward. The inner diameter chucking mechanism 29 includes a ball 39 that abuts against the outer ring raceway groove 13a of the intermediate product 21 housed in the inner diameter side mold 33, and a spring 41 that urges the ball 39 radially outward. The spring 41 need only be capable of urging the ball 39, and may be, for example, a cam mechanism. The spring 41 and the ball 39 urge the intermediate product 21 radially outward, thereby centering the intermediate product 21 radially. In other words, the intermediate product 21 housed in the insert molding die 27 is positioned radially concentric with the center axis CL of the insert molding die 27.

[0031] Four pairs of springs 41 and balls 39 that make up the inner diameter chucking mechanism 29 are arranged at 90° intervals in the circumferential direction of the ring-shaped intermediate product 21 around the central axis CL, but this can be modified as appropriate, such as arranging three pairs at 120° intervals. The gaps between the anti-raceway groove side peripheral surface 13b, axial end face 13c, groove shoulder end face 13f of the intermediate product 21 and the outer diameter side mold 31, width hold down upper mold 35, and width hold down lower mold 37 form cavity CB into which resin material is filled.

[0032] In this way, the outer ring raceway groove 13a, which is the raceway groove-side circumferential surface on the raceway groove side of the intermediate product 21, is pressed against a specified reference surface (balls 39) to be centered in the radial direction, and the axial end face 13c is pressed against specified reference surfaces (upper width presser die 35, lower width presser die 37) to be centered in the axial direction (width direction). In this state, the intermediate product 21 is held in the insert molding die 27, and the resin layer 17 is insert-molded onto the anti-raceway groove side circumferential surface 13b and the axial end face 13c, respectively, thereby reducing variations in the thickness of the resin layer 17. Furthermore, in groove grinding (ST8), the outer ring raceway groove 13a is ground using the resin layer 17 of the anti-raceway groove side circumferential surface 13 after grinding as a reference surface, thereby enabling high-precision concentricity between the outer ring raceway groove 13a and the anti-raceway groove side circumferential surface 13b.

[0033] 8 is a partial cross-sectional view showing a configuration example of an insert molding die 27A of Modification 1. The inner diameter chucking mechanism 29 may be a block 40 that comes into surface contact with the inner peripheral surface 13e of the groove shoulder of the ring-shaped intermediate product 21, instead of the ball 39 described above.

[0034] In the configuration of this modified example, as shown in Fig. 8, the outer diameter side mold 31, the width presser upper mold 35, and the width presser lower mold 37 are fixed by a fixing mechanism (not shown), and the intermediate product 21 is centered and fixed to the central axis CL of the insert molding mold 27A by the inner diameter chucking mechanism 29. Then, heated resin material is injected from a gate (not shown) into the cavity CB to form the resin layer 17 (ST35). This prevents the intermediate product 21 from being unevenly positioned within the cavity CB, allowing for stable injection molding. As a result, variation in the thickness of the formed resin layer 17 can be suppressed.

[0035] 9 is a partial cross-sectional view showing a configuration example of an insert molding die 27B of Modification 2. In the insert molding die 27B of Modification 2, the outer diameter side die 31 and the width presser upper die 35 are fixed by a fixing mechanism (not shown), and a spring 43 provided below the width presser lower die 37 urges the width presser lower die 37 toward the width presser upper die 35. According to this modification, the width presser lower die 37 presses up the groove shoulder end face 13f of the intermediate product 21 with the urging force of the spring 43, thereby centering the intermediate product 21 in the axial direction (width direction).

[0036] 10 is a partial cross-sectional view showing a configuration example of an insert molding die 27C of Modification 3. In the insert molding die 27C of Modification 3, the outer diameter side die 31 is fixed by a fixing mechanism (not shown), and a spring 43 provided below the width presser lower die 37 urges the width presser lower die 37 toward the width presser upper die 35. In addition, a spring 45 provided above the width presser upper die 35 urges the width presser upper die 35 toward the width presser lower die 37. According to this modification, the width presser upper die 35 and the width presser lower die 37 clamp the groove shoulder end faces 13f of the intermediate product 21 with the elastic urging forces of the springs 43 and 45, thereby centering the intermediate product 21 in the axial direction (width direction).

[0037] According to the configurations of Modifications 2 and 3, the intermediate product 21 is accurately positioned in the axial direction, which more reliably reduces variations in the axial (width) dimension of the intermediate product 21 during insert molding. This enables more stable injection molding, and the resin layer 17 can be molded to a uniform thickness with high precision.

[0038] (Fourth embodiment) The procedure for forming the outer ring 13 in the fourth embodiment omits the grinding of the intermediate product 21 before insert molding in the third embodiment. FIG. 11 is a process explanatory diagram showing the procedure for forming the outer ring 13 of the insulating rolling bearing 100 of the fourth embodiment, and showing an assembly in which the inner ring 11 and balls 15 are assembled to the formed outer ring 13. Steps ST41 to ST46 shown in FIG. 11 omit the width grinding (ST33) and outer diameter grinding (ST34) of the intermediate product 21 from the processing procedures ST31 to ST38 of the intermediate product 21 shown in FIG. 6. That is, in this forming procedure, after heat treatment (ST42), insert molding (ST43) is performed without grinding the intermediate product 21. In this embodiment, as in the third embodiment, radial centering of the intermediate product 21 is performed using the inner diameter chucking mechanism 29. Furthermore, as in the above-mentioned modifications 2 and 3, axial (widthwise) centering may also be performed.

[0039] According to this embodiment, variations in the thickness of the resin layer 17 are suppressed, and manufacturing costs can be reduced by reducing the number of steps. In groove grinding (ST46), the outer ring raceway groove 13a is ground using the resin layer 17 on the anti-raceway groove side circumferential surface 13 after grinding as a reference surface, thereby making it possible to improve the coaxiality between the outer ring raceway groove 13a and the anti-raceway groove side circumferential surface 13b with high precision.

[0040] (Fifth embodiment) The procedure for forming the outer ring in the fifth embodiment omits the grinding of the intermediate product 21 before insert molding and the grinding of the resin after insert molding in the third embodiment. Figure 12 is a process explanatory diagram showing the procedure for forming the outer ring 13 of the insulating rolling bearing 100 of the fifth embodiment, and showing an assembly in which the inner ring 11 and balls 15 are assembled to the formed outer ring 13. Steps ST51 to ST56 shown in Figure 12 omit the resin width grinding (ST36) and resin outer diameter grinding (ST37) of the intermediate product 21 shown in Figure 6. In the case of this embodiment, as in the third embodiment, the intermediate product 21 is centered by the inner diameter chucking mechanism 29. Furthermore, as in the above-mentioned modifications 2 and 3, centering in the axial direction (width direction) may also be performed.

[0041] According to this embodiment, the number of steps can be reduced, thereby reducing manufacturing costs. Furthermore, centering improves the positional accuracy between the insert molding die and the intermediate product 21. The thickness of the resin layer 17 is guaranteed by the high positional accuracy between the insert molding die and the intermediate product 21 during injection molding.

[0042] <Configurations of other insulated rolling bearings> FIG. 13 is a partial cross-sectional view of another insulated rolling bearing 200. The insulated rolling bearing 200 has a similar configuration to the insulated rolling bearing 100, except that the resin layer 17 formed on the outer ring 13 shown in FIG. 1 is formed on the inner ring 11. That is, an electrically insulating resin layer 18 is formed over the entire circumference of the inner ring 11, on the counter-raceway groove side circumferential surface 11b, which is the outer peripheral surface opposite the inner ring raceway groove 11a, and on the axial end faces 11c at both axial ends. Groove shoulders 11d are formed at both axial ends of the inner ring raceway groove 11a, protruding radially outward. The groove shoulders 11d have groove shoulder outer peripheral surfaces (groove shoulder circumferential surfaces) 11e at their protruding tips. The resin layer 18 is formed from the axial end faces 11c, wrapping around inward in the axial direction, to a portion of the inner peripheral side of the groove shoulder end face 11f on the axial outside of the groove shoulder 11d. That is, the resin layer 18 is formed to cover the inner peripheral surface of the inner ring 11, that is, the peripheral surface 11b on the side opposite to the raceway groove side and the axial end surface 11c.

[0043] 14 is a schematic cross-sectional view of the insert molding die 28. The insert molding die 28 includes inner diameter side dies 51 and 53, an outer diameter side member 55, an upper width presser die 57, and a lower width presser die 59. The inner diameter side dies 51 and 53 have a recess 54 that covers the inner diameter side of the intermediate product 22 to be machined into the inner ring 11. The outer diameter side member 55 is disposed on the outer diameter side of the intermediate product 22. The upper width presser die 57 and the lower width presser die 59 clamp the axial end face of the ring-shaped intermediate product 22 in the axial direction (width direction) of the ring. The insert molding die 28 also includes an outer diameter chucking mechanism 30 that presses the inner ring raceway groove 11a, which is the outer peripheral surface of the intermediate product 22, radially inward to chuck it.

[0044] The outer diameter chucking mechanism 20 includes an outer diameter side member 55 that abuts against the inner ring raceway groove 11a of the intermediate product 22 accommodated in the recess 54 of the inner diameter side mold 51, 53, and a spring 61 that biases the outer diameter side member 55 radially inward. A radially fixed seat 63 is disposed at the end of the spring 61 opposite the outer diameter side member 55. The spring 61 need only be able to bias the outer diameter side member 55, and may be, for example, a cam mechanism. The spring 61 and the outer diameter side member 55 bias the intermediate product 22 radially inward, thereby centering the intermediate product 22 radially. In other words, the intermediate product 22 accommodated in the insert molding die 28 is positioned so as to be concentric with the center axis CL of the insert molding die 28. Four pairs of springs 61 and outer diameter side members 55 that constitute the outer diameter chucking mechanism 30 are arranged at 90° intervals in the circumferential direction of the ring-shaped intermediate product 22 around the central axis CL, but this can be modified as appropriate, such as arranging three pairs at 120° intervals. Gaps between the anti-raceway groove side peripheral surface 11b, axial end face 11c, groove shoulder end face 11f, which are the inner peripheral surface of the intermediate product 22, and the inner diameter side dies 51, 53, width hold down upper die 57, and width hold down lower die 59 form cavity CB into which resin material is filled.

[0045] In this configuration, the inner diameter side dies 51 and 53, the width presser upper die 57, the width presser lower die 59, and the base 63 are fixed by a fixing mechanism (not shown), and the intermediate product 22 is fixed and centered on the central axis CL of the insert molding die 28 by the outer diameter chucking mechanism 30. Then, heated resin material is injected into the cavity CB through a gate (not shown) to form the resin layer 18. Specifically, the inner ring raceway groove 11a and the groove shoulder outer surface (groove shoulder circumferential surface) 11e, which are the raceway groove-side circumferential surface of the intermediate product 22, are pressed against a specified reference surface (the outer diameter side member 55) to be centered radially, and the axial end face 11c is pressed against a specified reference surface (the width presser upper die 57, the width presser lower die 59) to be centered axially (widthwise). In this state, the intermediate product 22 is held in the insert molding die 28, and the resin layer 18 is insert-molded onto the non-raceway groove-side circumferential surface 11b and the axial end face 11c, respectively. This prevents the intermediate product 22 from being unevenly positioned in the cavity CB, allowing stable injection molding, and as a result, the resin layer 18 can be formed with reduced variations in thickness.

[0046] As with the intermediate product 21 described above, by performing the procedures for the outer ring 13 shown in Figures 3 (first embodiment), 5 (second embodiment), 6 (third embodiment), 11 (fourth embodiment), and 12 (fifth embodiment) on the inner ring 11 instead of the outer ring 13, the effects and advantages described in each embodiment can also be enjoyed for the inner ring 11.

[0047] Furthermore, in order to center the intermediate product 22 in the axial direction (width direction), the insert molding die 28 may have the configurations of modified examples 4 and 5 shown below. 15 is a cross-sectional view showing a configuration example of an insert molding die 28A of Modified Example 4. In the insert molding die 28A of Modified Example 4, the inner diameter side dies 51, 53 and the width presser lower die 59 are fixed by a fixing mechanism (not shown). The width presser upper die 57 is restricted in movement in the radial direction but is supported so as to be movable in the axial direction (width direction). A spring 65 provided above the width presser upper die 57 biases the width presser upper die 57 toward the width presser lower die 59. In this configuration, a ball 56 is used as the outer diameter side member 55 described above. According to this modification, the width presser upper die 57 presses down the groove shoulder end face 11f of the intermediate product 22 with the biasing force of the spring 65, thereby centering the intermediate product 22 in the axial direction (width direction).

[0048] 16 is a partial cross-sectional view showing an example of the configuration of an insert molding die 28B of Modification 5. In the insert molding die 28B of Modification 5, inner diameter side dies 51, 53 are fixed by a fixing mechanism (not shown). Furthermore, the width pressing upper die 57 and the width pressing lower die 59 are supported so that their movement in the radial direction is restricted but they are movable in the axial direction (width direction). A spring 65 provided above the width pressing upper die 57 urges the width pressing upper die 57 toward the width pressing lower die 59, and a spring 67 provided below the width pressing lower die 59 urges the width pressing lower die 59 toward the width pressing upper die 57. According to this modification, the width pressing upper die 57 and the width pressing lower die 59 respectively clamp the groove shoulder end faces 11f of the intermediate product 22 by the elastic urging forces of the springs 65, 67, thereby centering the intermediate product 22 in the axial direction (width direction).

[0049] According to the configurations of Modifications 4 and 5, the intermediate product 22 is accurately positioned in the axial direction, which more reliably reduces variations in the axial (width) dimension of the intermediate product 22 during insert molding. This enables more stable injection molding, and the resin layer 18 can be molded to a uniform thickness with high precision.

[0050] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0051] For example, in the above example, the resin layer is finished by grinding, but depending on the conditions, it may be finished by cutting instead of grinding.

[0052] As described above, the present specification discloses the following: (1) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface being on the opposite side to the raceway groove, the resin layer comprising: grinding a raceway groove-side peripheral surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the intermediate product is held in an insert mold using the ground raceway groove side circumferential surface as a reference, and the resin layer is insert-molded onto the anti-raceway groove side circumferential surface and the axial end surface of the intermediate product, respectively; the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings. (2) The method for producing an insulating rolling bearing according to (1), wherein the raceway grooves of the intermediate product are ground after the resin layer is ground. (3) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface and the axial end face of the raceway groove, the a raceway groove-side circumferential surface and an axial end surface of a metal intermediate product machined into a ring shape having the shape of the raceway groove are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the raceway groove-side circumferential surface and the axial end surface, the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings. (4) The method for producing an insulating rolling bearing according to (1), wherein, before the insert molding, the peripheral surface on the side opposite to the raceway groove and the axial end surface of the intermediate product are each ground. (5) The method for producing an insulating rolling bearing according to (3) or (4), wherein the raceway grooves of the intermediate product are ground after the resin layer is ground. (6) A method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface and the axial end face of the raceway groove, the grinding the peripheral surface opposite the raceway groove side and the axial end surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the raceway groove-side circumferential surface and the axial end surface of the intermediate product are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the anti-raceway groove-side circumferential surface and the axial end surface, respectively. Manufacturing method for insulated rolling bearings. (7) The method for producing an insulating rolling bearing according to any one of (1) to (6), wherein the grindstone for grinding the resin layer is formed to be porous. [Explanation of symbols]

[0053] 11 Inner Circle 11a Inner ring raceway groove 11b Counter raceway groove side circumferential surface 11c Axial end face 11d Groove shoulder 11e Groove shoulder outer circumferential surface (groove shoulder circumferential surface) 11f Groove shoulder end face 13 Outer ring 13a Outer ring raceway groove 13b Counter raceway groove side circumferential surface 13c Axial end face 13d groove shoulder 13e Groove shoulder inner peripheral surface (groove shoulder peripheral surface) 13f Groove shoulder end face 15 balls (rolling elements) 17,18 Resin layer 21 Intermediate products 21a Axial end face 21b Counter raceway groove side circumferential surface 21c groove 25 Insert molding die 27, 27A, 27B, 28, 28A, 28B Insert molding die 29 Inner diameter chucking mechanism 30 Outer diameter chucking mechanism 31 Outer diameter side mold 33 Inner diameter mold 35 Wide presser foot upper die 37 Wide presser foot 39 balls 41 Spring 51,53 Inner diameter mold 54 Recess 55 Outer diameter member 57 Width presser upper die 59 Wide presser foot 61 Spring 63 Pedestal 65 Spring 100,200 Insulated rolling bearing

Claims

1. a method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface being on the side opposite to the raceway groove, the resin layer comprising: grinding a raceway groove-side peripheral surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the intermediate product is held in an insert mold using the ground raceway groove side circumferential surface as a reference, and the resin layer is insert-molded onto the anti-raceway groove side circumferential surface and the axial end surface of the intermediate product, respectively; the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings.

2. 2. The method for producing an insulating rolling bearing according to claim 1, wherein the raceway grooves of the intermediate product are ground after the resin layer is ground.

3. a method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface being on the side opposite to the raceway groove, the resin layer comprising: a raceway groove-side circumferential surface and an axial end surface of a metal intermediate product machined into a ring shape having the shape of the raceway groove are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the raceway groove-side circumferential surface and the axial end surface, the resin layers formed on the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground to form the raceway ring. Manufacturing method for insulated rolling bearings.

4. before the insert molding, the peripheral surface opposite the raceway groove side and the axial end surface of the intermediate product are ground; A method for manufacturing an insulating rolling bearing according to claim 3.

5. 4. The method for producing an insulating rolling bearing according to claim 3, wherein the raceway grooves of the intermediate product are ground after the resin layer is ground.

6. a method for manufacturing an insulating rolling bearing comprising an inner ring and an outer ring, each having a raceway groove, and a plurality of rolling elements arranged to roll freely between the raceway grooves of the inner ring and the outer ring, wherein an electrically insulating resin layer is formed on a peripheral surface and an axial end face of at least one of the inner ring and the outer ring on a side opposite to the raceway groove, the peripheral surface being on the side opposite to the raceway groove, the resin layer comprising: grinding the peripheral surface opposite the raceway groove side and the axial end surface of a metal intermediate product processed into a ring shape having the raceway groove shape; the raceway groove-side circumferential surface and the axial end surface of the intermediate product are pressed against a specified reference surface for centering, while the intermediate product is held in an insert molding die, and the resin layer is insert-molded onto the anti-raceway groove-side circumferential surface and the axial end surface, respectively. Manufacturing method for insulated rolling bearings.

7. The grindstone for grinding the resin layer is formed to be porous. A method for manufacturing an insulating rolling bearing according to any one of claims 1 to 6.

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