Rolling bearing and cage for rolling bearing

Abstract

To provide a rolling bearing and a cage for a rolling bearing, enabling reduction of vibration, extension of the lubrication lives thereof and reduction of the manufacturing costs thereof.SOLUTION: A cage 6 has two annular bodies 10, 10 overlapping axially each other, each annular body 10 has a plurality of pocket wall portions 13, and a plurality of joining plate portions 14. The cage 6 has cutout portions 13a, 13b respectively provided in the inner diameter face and the outer diameter face of the pocket wall portion 13 in such a manner that a band width W1 being the radial size of the pocket wall portion 13 is smaller than a radial size W2 of the joining plate portion 14. Out of each pocket wall portion, the radial center of the band width W1 between a deepest portion P1 of the cutout portion 13a in the inner diameter face and a deepest portion P2 of the cutout portion 13b in the outer diameter face is located near the pitch circle diameter of the ball 5. The band width W1 is 35% or smaller of a diameter BD of the ball 5, and a peripheral range L1 of each of the cutout portions 13a, 13b is 50-100% of the diameter BD of the ball 5.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present invention relates to a rolling bearing and a cage for a rolling bearing, and more particularly to a technique for reducing vibration and improving lubrication life in, for example, a rolling bearing for a motor. [Background technology]

[0002] A synthetic resin cage for use in rolling bearings has been proposed (Patent Document 1). This synthetic resin cage consists of two annular bodies facing each other in the axial direction, and a number of pockets for accommodating balls are formed between the two annular bodies at intervals in the circumferential direction. Also, in order to improve the lubrication life, a rolling bearing has been proposed in which a circumferential groove-like grease pocket is formed on the inner diameter surface of the outer ring (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-7468 A [Patent Document 2] JP 2009-275176 A Summary of the Invention [Problem to be solved by the invention]

[0004] 6 and 7, the conventional synthetic resin cage Rt has a shape in which the radial dimension of the pocket portion Pt, that is, the band width W, is in the range of 40% to 50% of the ball diameter, centered on the ball PCD, and holds the ball 30. Also, the band width W is 70% to 80% of the radial dimension D1 between the inner diameter surface of the outer ring 31 and the outer diameter surface of the inner ring 32.

[0005] In this case, as shown in Fig. 6, the gap δ between the ball 30 and the inner diameter side edge of the pocket portion Pt, and the gap δ1 between the ball 30 and the outer diameter side edge of the pocket portion Pt become wider. Therefore, less of the grease adhering to the ball surface is scraped off by the pocket portion Pt, and more of the grease is caught between the pocket portion Pt and the ball 30. This increases the shear resistance of the grease between the pocket portion Pt and the ball 30, making the behavior of the cage Rt unstable, which may result in increased vibration and noise levels.

[0006] In addition, the inner diameter of the rolling bearing is dmm and the rotation speed is n(min -1 For rolling bearings used at high speeds, where the dn value obtained by multiplying the bearing diameter by the bearing diameter is 350,000 or more, the static space volume is limited to 100%, taking heat generation into consideration. The "static space volume" mentioned above is the volume of the space (static space) excluding the rolling elements and the cage in the bearing space between the inner and outer rings. When seal members are attached to both sides in the axial direction, the static space volume is the volume of the static space between the seal members on both sides in the axial direction, within the bearing space between the inner and outer rings. The space including the rolling elements and the cage in the bearing space is called the dynamic space.

[0007] After the bearing rotates, the grease is discharged from the moving space to the stationary space and is retained in the stationary space near the inner diameter side of the outer ring, and the base oil of the grease is supplied to the outer ring rolling surface and used as lubrication for the rolling parts. Grease retained between the seal member below the ball PCD and the back surface of the cage, and in the stationary space near the outer diameter of the inner ring, does not contribute much to lubrication. In the conventional product shown in Fig. 6, the width W of the pocket portion Pt is large, so the static space volume A1 is narrow and the amount of grease held near the inner diameter side of the outer ring is small, which can shorten the lubrication life. As shown in Fig. 8, if grease pockets 31b (Fig. 8) are provided on both axial sides of the rolling surface 31a on the inner diameter surface of the outer ring 31 to increase the amount of grease held near the inner diameter side of the outer ring in order to improve the lubrication life, manufacturing costs will increase.

[0008] An object of the present invention is to provide a rolling bearing and a cage for a rolling bearing which are capable of reducing vibration, improving lubrication life, and reducing manufacturing costs. [Means for solving the problem]

[0009] The rolling bearing of the present invention comprises an inner and outer ring, a plurality of balls interposed between the inner and outer rings, and a cage formed with pockets for holding the balls, the cage having two annular bodies overlapping each other in the axial direction, each annular body having a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and each constituting an inner wall surface of the pocket, and a plurality of connecting plate portions connecting adjacent pocket wall portions in the circumferential direction, the two annular bodies being overlapped and connected to each other at the connecting plate portions, The cage has cutouts on an inner diameter surface and an outer diameter surface of the pocket wall portion such that a band width, which is a radial dimension of the pocket wall portion, is smaller than a radial dimension of the connecting plate portion, In each pocket wall portion, the radial center of a band width between the deepest portion of the notch portion on the inner diameter surface and the deepest portion of the notch portion on the outer diameter surface is set near the pitch circle diameter of the ball, The band width is set to 35% or less of the diameter of the ball, and the circumferential range of each of the cutout portions is set to 50 to 100% of the diameter of the ball. The vicinity of the pitch circle diameter of the ball means a range of ±5% of the diameter of the ball, based on the pitch circle diameter (PCD) of the ball.

[0010] With this configuration, the grease adhering to the balls is scraped off by the cutouts on the inner and outer diameter sides of the pocket wall, respectively, so less grease gets caught between the pocket and the balls. This reduces the shear resistance of the grease between the pocket and the balls, stabilizing the behavior of the cage and providing the exceptional operational effects of reducing vibration and noise levels. If the width of the cutout exceeds 35% of the diameter of the ball, or if the circumferential range of the cutout is less than 50% of the diameter of the ball, less grease is scraped off and more grease gets caught between the pocket and the ball. In this case, the behavior of the cage becomes unstable and the effect of suppressing vibration and noise is small.

[0011] Since the outer diameter surface of the pocket wall is provided with a notch, the static space is enlarged. In this case, the static space volume is increased compared to a structure in which a notch is provided only on the inner diameter surface of the pocket wall, or a structure in which no notch is provided on the pocket wall. By providing a notch on the outer diameter surface of the pocket wall, the amount of grease held in the static space on the inner diameter side of the outer ring is increased. This makes it possible to improve the lubrication life without providing a circumferential groove-shaped grease pocket on the inner diameter surface of the outer ring. Therefore, manufacturing costs can be reduced compared to conventional structures in which a grease pocket is provided on the inner diameter surface of the outer ring.

[0012] If there is only a notch on the inner diameter side, grease is likely to get caught between the pocket and the balls from the outer diameter side where there is no notch, making it difficult for the cage to behave stably, resulting in increased vibration and noise. Also, the static space volume on the outer diameter side of the inner ring becomes wider, and the amount of grease held in the static space on the outer diameter side of the inner ring increases, but this does not contribute to the lubrication of the rolling parts. If there is only a cutout on the outer diameter side, the amount of grease retained on the inner diameter side of the outer ring increases, improving the lubrication life, but grease can easily get caught between the pockets and the balls from the inner diameter side where there is no cutout, making it difficult to stabilize the behavior of the cage and resulting in increased vibration and noise.

[0013] The width of the cage may be 50% or less of the radial dimension between the inner diameter surface of the outer ring and the outer diameter surface of the inner ring, which can more reliably reduce grease trapped between the pockets and the balls.

[0014] The cage may be made of a resin material with a melting point of 200 to 350°C. In this case, no abnormal sliding marks are observed on the cage, which is preferable. If the resin material has a melting point of less than 200°C, the resin will melt or wear abnormally due to frictional heat caused by the sliding between the balls and the pocket walls. If the resin material has a melting point of more than 350°C, the manufacturing cost will be high.

[0015] The balls may be ceramic balls, which have a smaller specific gravity than steel balls made of bearing steel or the like, allowing the rolling bearing to operate at higher speeds and with improved heat resistance.

[0016] The rolling bearing may be a rolling bearing for a motor. If the rolling bearing for a motor can reduce vibration, improve the lubrication life, and reduce manufacturing costs, the rolling bearing can be applied to motors for various applications, and the versatility of the rolling bearing for a motor can be improved.

[0017] The cage for a rolling bearing of the present invention is a cage used in the above-mentioned rolling bearing of the present invention. Effect of the Invention

[0018] According to the rolling bearing or rolling bearing of the present invention, the grease adhering to the balls is scraped off by the cutouts on the inner diameter side and the outer diameter side of the pocket wall, respectively, so that the amount of grease caught between the pocket and the balls is reduced. This reduces the shear resistance of the grease between the pocket and the balls, stabilizes the behavior of the cage, and reduces vibration and noise levels. By providing cutouts not only on the inner diameter surface but also on the outer diameter surface of the pocket wall, the amount of grease held in the stationary space on the inner diameter side of the outer ring is increased. This makes it possible to improve the lubrication life without the need for manufacturing costs such as providing a circumferential groove-shaped grease pocket on the inner diameter surface of the outer ring. [Brief description of the drawings]

[0019] [Figure 1] 1 is a vertical sectional view of a rolling bearing according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a main portion of the rolling bearing. [Figure 3A] FIG. 2 is a front view of the cage of the rolling bearing as viewed from the axial direction. [Figure 3B] FIG. [Figure 4A] FIG. [Figure 4B] 4B is a cross-sectional view taken along line IVB-IVB of FIG. 4A. [Diagram 5] 2 is a schematic diagram showing a rolling bearing for a motor in which the rolling bearing is applied to a motor. FIG. [Figure 6]FIG. 1 is an enlarged vertical sectional view of a main portion of a conventional rolling bearing. [Figure 7] FIG. 1 is a front view of a conventional rolling bearing retainer as viewed from the axial direction. [Figure 8] FIG. 11 is an enlarged vertical sectional view of a main portion of another conventional rolling bearing. [Figure 9] FIG. 11 is a front view of still another conventional rolling bearing retainer as viewed from the axial direction. [Figure 10] FIG. 11 is a front view of still another conventional rolling bearing retainer as viewed from the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [First embodiment] A rolling bearing and a cage for a rolling bearing according to an embodiment of the present invention will be described with reference to Figs. <About rolling bearings> As shown in Fig. 1, the rolling bearing 1 of this example is a deep groove ball bearing that includes an inner ring 2, an outer ring 3, balls 5 which are multiple rolling elements interposed between the rolling surfaces 2a, 3a of the inner and outer rings 2, 3, a cage 6 that holds the balls 5, and a seal 4. The balls 5 are steel balls or ceramic balls.

[0021] An annular space is formed between the outer periphery of the inner ring 2 and the inner periphery of the outer ring 3, and openings at both axial ends of this annular space are closed by seals 4, 4. Lubricating grease is sealed in the closed annular space. A seal mounting groove 7 is formed on the inner circumferential surface of the outer ring 3, and an inner ring seal groove 8 is formed on the outer circumferential surface of the inner ring 2. As shown in FIG. 2, each seal 4 in this example is a non-contact seal in which the lip does not come into contact with the inner ring seal groove 8. The seal 4 is formed by molding a rubber material 4b onto a core metal 4a, and the outer circumferential edge of this seal 4 is fitted into and fixed in the seal mounting groove 7 of the outer ring 3.

[0022] <About retainer 6> As shown in Fig. 3A, the cage 6 is of a rolling element guide type, and as shown in Fig. 4B, it is composed of two synthetic resin annular bodies 10, 10 overlapping each other in the axial direction. In the cage 6 of Fig. 3A, when the two annular bodies 10, 10 are joined together, the outer diameter surfaces of the annular bodies 10, 10 form cylindrical surfaces of the same diameter except for the cutout portion 13b, and the inner diameter surfaces of the annular bodies 10, 10 form cylindrical surfaces of the same diameter except for the cutout portion 13a. Each annular body 10 is formed by, for example, injection molding of a synthetic resin. The two annular bodies 10, 10 have the same shape and can be molded using the same mold.

[0023] The synthetic resin may be polyolefin resin, thermosetting resin, engineering plastic, super engineering plastic, etc., as long as it is injection moldable and has sufficient heat resistance, oil resistance, mechanical strength, etc., as a cage material. In addition, the cage 6 is preferably made of a resin material having a melting point of 200°C to 360°C, preferably 200°C to 350°C, in consideration of heat resistance. If the melting point is less than 200°C, the resin may melt or wear abnormally due to frictional heat caused by the sliding of the balls and the pocket wall. In order to increase the strength, the resin may contain 15 to 45 mass% of glass fiber, carbon fiber, aramid fiber, etc., but resin without these fibers may also be used.

[0024] Examples of the thermosetting resin include epoxy resin and phenol resin. Examples of the engineering plastics include polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, tetrafluoroethylene-hexafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, ethylene-tetrafluoroethylene copolymer resin, and wholly aromatic polyester resin. Examples of the super engineering plastics include polyether ether ketone resin, polyphenylene sulfide resin, polyetherimide resin, polyamideimide resin, polyethersulfone resin, thermoplastic polyimide resin, polyamide resin (e.g., PA46, PA66, PA9T, PA10T, etc.), etc. Also usable are mixtures of two or more of the above resins, polymer alloy materials, etc.

[0025] 4A and 4B, each annular body 10 has a plurality of semi-cylindrical pocket wall portions 13 and a plurality of connecting plate portions 14. The plurality of pocket wall portions 13 are arranged at regular intervals in the circumferential direction and each constitutes an inner wall surface of a pocket 12 that holds a ball 5. The plurality of connecting plate portions 14 connect the pocket wall portions 13 adjacent to each other in the circumferential direction.

[0026] The joining plate portion 14 has a mating surface 15 which comes into surface contact when the two annular bodies 10, 10 are joined together. Near the circumferential center of the mating surface 15 of the joining plate portion 14, there are formed a joining claw 16 which protrudes in the axial direction, and a joining hole 17 into which the joining claw 16 of the other annular body 10 is inserted. A hook 19 is formed at the axial tip of the connecting claw 16, and the hook 19 of one annular body 10 engages with a step 18 formed on the inner surface of the connecting hole 17 of the other annular body 10. This engagement prevents the connecting claw 16 from slipping out of the connecting hole 17, and the two annular bodies 10, 10 are overlapped and connected to each other.

[0027] The connecting plate portion 14 has a protruding wall portion 20 and a receiving recess 21. The protruding wall portion 20 is provided at one circumferential end of the mating surface 15 of one of the annular bodies 10 so as to protrude in the axial direction. The receiving recess 21 is provided at the other circumferential end of the mating surface 15 of one of the annular bodies 10, and receives the protruding wall portion 20 of the other annular body 10. Since the connecting plate portion 14 has the protruding wall portion 20 and the receiving recess 21, the joint of the two annular bodies 10, 10 when they are connected is located at a position shifted from the axial center of the pocket 12. This can prevent the balls 5 from contacting the connecting plate portion 14 due to the delay or advance of the balls 5 during bearing operation. Therefore, it is possible to stably hold the balls 5.

[0028] When the two annular bodies 10, 10 are joined together, the protruding wall portion 20 and the accommodating recess 21 are sized to generate circumferential and axial gaps 22, 23 between the protruding wall portion 20 and the accommodating recess 21. This makes it possible to prevent interference between the protruding wall portion 20 and the accommodating recess 21 due to differential shrinkage after the annular body 10 is injection molded, and makes it possible to reliably bring the mating surfaces 15 of the joining plate portions 14 of the two annular bodies 10, 10 into close contact with each other.

[0029] A partial concave spherical surface 25 is formed on both circumferential ends of each pocket 12, following the outer periphery of the ball 5. The partial concave spherical surfaces 25 are formed facing each other at the front and rear in the traveling direction of the ball 5, sandwiching the ball 5 therebetween. The radius of curvature of the partial concave spherical surface 25 is set slightly larger than the radius of the ball 5.

[0030] <Regarding the cutout portions 13a and 13b> Fig. 3B is an enlarged view of a portion IIIB in Fig. 3A. As shown in Fig. 3A and Fig. 3B, the cage 6 has cutouts 13a, 13b on the inner and outer diameter surfaces of the pocket wall 13 so that the band width W1, which is the radial dimension of the pocket wall 13, is smaller than the radial dimension W2 of the connecting plate 14. The cutouts 13a, 13b on the inner and outer diameter surfaces are curved surfaces that are concave curves when viewed from the bearing axial direction. These cutouts 13a, 13b are formed, for example, during injection molding of the annular body 10, but can also be formed by machining or the like after injection molding.

[0031] In each pocket wall 13, a deepest part P1 of the cutout 13a in the inner diameter surface is provided in a circumferential middle part of the inner diameter surface, and a deepest part P2 of the cutout 13b in the outer diameter surface is provided in a circumferential middle part of the outer diameter surface. In each pocket wall 13, a band width W1 in the circumferential middle part is smallest, and the band width W1 is gradually increased from the circumferential middle part toward both sides in the circumferential direction along the curved shape.

[0032] In addition, the radial center Pc of the minimum band width W1 between the deepest part P1 of the notch 13a on the inner diameter surface and the deepest part P2 of the notch 13b on the outer diameter surface of each pocket wall 13 is set to be near the pitch circle diameter (PCD) of the ball 5. The minimum band width W1 is set to be 20% to 35% of the diameter BD of the ball 5, and the circumferential range L1 of each notch 13a, 13b is set to be 50% to 100% of the diameter BD of the ball 5. Furthermore, in this embodiment, as shown in FIG. 2, the minimum band width W1 is set to be 50% or less of the radial dimension D1 between the inner diameter surface of the outer ring 3 and the outer diameter surface of the inner ring 2.

[0033] The pocket wall 13 is thickened by the amount of the volume reduction caused by the cutouts 13a and 13b. Specifically, for a synthetic resin cage used in a deep groove ball bearing having the same inner diameter, outer diameter, and width dimensions, compared to a conventional pocket wall 33 (FIG. 6) that has no cutouts, the cage of this embodiment has the entire pocket wall 13 thickened in the bearing axial direction by the amount of the volume reduction. This makes it possible to suppress a decrease in rigidity of the cage 6 caused by the cutouts 13a and 13b.

[0034] <Acoustic Test> An acoustic test was carried out using a testing machine described later to compare a rolling bearing equipped with the cage according to this embodiment with a rolling bearing equipped with a conventional cage. <Test conditions> Model number (nominal number) of the rolling bearing to be tested: 6312 (inner diameter 60 mm x outer diameter 130 mm x width 31 mm) Rotation speed: 8000min -1 Load: Radial load Fr=500N, Axial load Fa=785N Judgment method: Hearing judgment during bearing rotation at a specified time after the start of the test

[0035] The testing machine is configured, for example, such that a drive shaft is rotatably supported in a housing via two rolling bearings, and a pulley at one longitudinal end of the drive shaft is rotatably driven around its axis by a motor via a belt or the like. Of the two rolling bearings, the rolling bearing on the pulley side is the rolling bearing to be tested, and the other rolling bearing is the support bearing. The motor is driven to rotate the drive shaft and the inner rings of each rolling bearing, and a radial load is applied to the rolling bearing to be tested by the belt load. The testing machine is equipped with a preload spring or the like for applying a predetermined axial load to the rolling bearing to be tested.

[0036] <Acoustic test results> [Table 1]

[0037] In Table 1, "◯" indicates that no abnormal noise was generated in the cage by the auditory judgment, and "×" indicates that an abnormal noise was generated in the cage by the auditory judgment.

[0038] <High-speed testing> A high-speed test was carried out on a rolling bearing including a plurality of retainers having different melting points among the retainers according to this embodiment. The test machine was substantially the same as the test machine used in the acoustic test described above.

[0039] <Test conditions> Model number (nominal number) of the rolling bearing to be tested: 6312 Rotation speed: 13500min -1 Load: Axial load Fa=588N Judgment method: Visual judgment after the rotation has stopped after a specified time has elapsed

[0040] <High-speed test results> [Table 2]

[0041] <Action and effect> In the rolling bearing 1 and rolling bearing cage 6 described above, grease adhering to balls 5 in Fig. 3A is scraped off by notches 13a, 13b on the inner diameter side and outer diameter side of pocket wall 13, respectively, and therefore less grease gets caught between pocket 12 and balls 5. This reduces the shear resistance of the grease between pocket 12 and balls 5, stabilizing the behavior of cage 6 and providing the exceptional operational effect of reducing vibration and noise levels. If band width W1 of cutouts 13a, 13b exceeds 35% of diameter BD of ball 5, or if circumferential range L1 of cutouts 13a, 13b is less than 50% of diameter BD of ball 5, less grease is scraped off and more grease gets caught between pocket 12 and ball 5. In this case, the behavior of cage 6 becomes unstable and the effect of suppressing vibration and noise is small.

[0042] Since the cutout 13b is provided on the outer diameter surface of the pocket wall 13, the static space is widened. In this case, the static space volume is increased compared to a structure in which the cutout 33a is provided only on the inner diameter surface of the pocket wall 33 (FIG. 9) or a structure in which the pocket wall 33 has no cutout (FIG. 7). By providing the cutout 13b on the outer diameter surface of the pocket wall 13, the amount of grease held in the static space on the inner diameter side of the outer ring is increased. This makes it possible to improve the lubrication life without providing a circumferential groove-shaped grease pocket on the inner diameter surface of the outer ring 3. Therefore, compared to a conventional structure (FIG. 8) in which a grease pocket 31b is provided on the inner diameter surface of the outer ring, the manufacturing cost can be reduced.

[0043] In the case of only the notch 33a on the inner diameter side (Fig. 9), grease is easily caught between the pocket and the balls from the outer diameter side where there is no notch, making it difficult for the cage to behave stably, resulting in increased vibration and noise. Also, the static space volume on the outer diameter side of the inner ring becomes wider, and the amount of grease held in the static space on the outer diameter side of the inner ring increases, but this does not contribute to the lubrication of the rolling parts. When there is only the cutout portion 33b on the outer diameter side (FIG. 10), the amount of grease held on the inner diameter side of the outer ring increases, improving the lubrication life; however, grease is easily caught between the pockets and the balls from the inner diameter side where there is no cutout, making it difficult to stabilize the behavior of the cage and resulting in increased vibration and noise.

[0044] If the width W1 of the retainer 6 is set to 50% or less of the radial dimension D1 between the inner diameter surface of the outer ring 3 and the outer diameter surface of the inner ring 2, the grease that becomes caught between the pocket 12 and the balls 5 can be more reliably reduced. The cage 6 may be made of a resin material with a melting point of 200 to 350°C. In this case, abnormal sliding marks are not observed on the cage 6, which is preferable. If the resin material has a melting point of less than 200°C, the resin will melt or wear abnormally due to frictional heat caused by the sliding between the balls 5 and the pocket wall 13. If the resin material has a melting point of more than 350°C, the manufacturing cost will be high. When the balls 5 are ceramic balls, the specific gravity is smaller than that of steel balls made of bearing steel or the like, enabling the rolling bearing 1 to operate at a higher speed and to have improved heat resistance.

[0045] This rolling bearing is used, for example, as rolling bearings 50, 50 for a motor 51 as shown generally in Fig. 5. However, this rolling bearing can also be applied to applications other than motors. If the rolling bearing is a rolling bearing for a motor which reduces vibration, improves lubrication life, and reduces manufacturing costs, the rolling bearing can be applied to motors for a variety of applications, thereby increasing the versatility of the rolling bearing as a motor rolling bearing.

[0046] <Other embodiments> The pocket walls of each annulus are not limited to being semi-cylindrical, but may be semi-spherical. The seal may be a contact seal in which the lip contacts the inner ring seal groove. The seal may be a so-called shield plate made of only a steel plate. It may be an open type rolling bearing without a seal. Any of the rolling bearings may be applied to machine tools, industrial machines, vehicles, and the like. Each annulus can be formed by 3D printing or machining.

[0047] <Reference proposal example> Instead of the band width being 35% or less of the diameter of the balls, the band width of the cage may be 50% or less of the radial dimension between the inner diameter surface of the outer ring and the outer diameter surface of the inner ring. The rest of the configuration is the same as in the above-mentioned embodiment. In this case, the same effects as those described above can be obtained. The rolling bearing according to this reference proposal example is described as follows.

[0048] A rolling bearing comprising inner and outer rings, a plurality of balls interposed between the inner and outer rings, and a cage in which pockets for holding the balls are formed, the cage having two annular bodies overlapping each other in the axial direction, each annular body having a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and each constituting an inner wall surface of the pocket, and a plurality of connecting plate portions connecting adjacent pocket wall portions in the circumferential direction, the two annular bodies being overlapped and connected to each other at the connecting plate portions, The cage has cutouts on an inner diameter surface and an outer diameter surface of the pocket wall portion such that a band width, which is a radial dimension of the pocket wall portion, is smaller than a radial dimension of the connecting plate portion, In each pocket wall portion, the radial center of a band width between the deepest portion of the notch portion on the inner diameter surface and the deepest portion of the notch portion on the outer diameter surface is set near the pitch circle diameter of the ball, A rolling bearing, wherein the band width of the retainer is 50% or less of the radial dimension between the inner diameter surface of the outer ring and the outer diameter surface of the inner ring, and the circumferential range of each of the cutout portions is 50 to 100% of the diameter of the balls.

[0049] Although the embodiment for carrying out the present invention has been described above, the disclosed embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0050] REFERENCE SIGNS LIST 1... rolling bearing, 2... inner ring, 3... outer ring, 5... balls, 6... cage, 10... annular body, 12... pocket, 13... pocket wall portion, 13a, 13b... notch portion, 14... connecting plate portion

Claims

1. A rolling bearing comprising inner and outer rings, a plurality of balls interposed between the inner and outer rings, and a cage in which pockets for holding the balls are formed, the cage having two annular bodies overlapping each other in the axial direction, each annular body having a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and each constituting an inner wall surface of the pocket, and a plurality of connecting plate portions connecting adjacent pocket wall portions in the circumferential direction, the two annular bodies being overlapped and connected to each other at the connecting plate portions, The cage has cutouts on an inner diameter surface and an outer diameter surface of the pocket wall portion such that a band width, which is a radial dimension of the pocket wall portion, is smaller than a radial dimension of the connecting plate portion, In each pocket wall portion, the radial center of a band width between the deepest portion of the notch portion on the inner diameter surface and the deepest portion of the notch portion on the outer diameter surface is set near the pitch circle diameter of the ball, A rolling bearing, wherein the band width is 35% or less of the diameter of the ball, and the circumferential range of each of the cutout portions is 50 to 100% of the diameter of the ball.

2. 2. The rolling bearing according to claim 1, wherein the band width of the cage is 50% or less of the radial dimension between the inner diameter surface of the outer ring and the outer diameter surface of the inner ring.

3. 3. The rolling bearing according to claim 1, wherein the cage is made of a resin material having a melting point of 200 to 350°C.

4. 4. The rolling bearing according to claim 1, wherein the balls are ceramic balls.

5. 5. The rolling bearing according to claim 1, wherein the rolling bearing is a rolling bearing for a motor.

6. A cage for a rolling bearing comprising two annular bodies overlapping each other in an axial direction, each annular body having a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and constituting an inner wall surface of a pocket for holding balls, and a plurality of connecting plate portions connecting adjacent pocket wall portions in the circumferential direction, the two annular bodies being overlapped and connected to each other at the connecting plate portions, A notch is provided on an inner diameter surface and an outer diameter surface of the pocket wall portion so that a band width, which is a radial dimension of the pocket wall portion, is smaller than a radial dimension of the connecting plate portion, In each pocket wall portion, the radial center of a band width between the deepest portion of the notch portion on the inner diameter surface and the deepest portion of the notch portion on the outer diameter surface is set near the pitch circle diameter of the ball, A retainer for a rolling bearing, wherein the band width is 35% or less of the diameter of the ball, and the circumferential range of each of the cutout portions is 50 to 100% of the diameter of the ball.

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