Crown type cage for ball bearing and ball bearing

Abstract

The present invention relates to a crown-type retainer for a ball bearing. A column portion (12) is formed such that the outer peripheral surface of the terminal portion side including a pair of claw portions is located at a position closer to the inner diameter side than the outer peripheral surface of the main portion (11). On the inner diameter side of the retainer (10), a plurality of weight-reducing portions are formed separately at the positions of each column portion in the circumferential direction, which are cut in the axial direction from the axial side surface of the main portion to each column portion. Each weight-reducing portion (20) is formed as a surface away from a pocket (13) and an axial outer side surface of the column portion formed between a pair of claw portions (14). When the axial dimension of a wall portion (22) formed between the axial outer side surface of the column portion and the inner wall surface of the weight-reducing portion is set to T1, and the axial dimension of the main portion at the bottom of the pocket is set to T2, T2>T1. As a result, even if the retainer is deformed by centrifugal force during high-speed rotation, it is not easy to contact other components, and the centrifugal force during high-speed rotation can be reduced by reducing the weight while ensuring the rigidity at a specified position to suppress deformation during high-speed rotation.

Description

Technical Field

[0001] The present invention relates to a crown-shaped retainer for a ball bearing and a ball bearing, and in particular to a crown-shaped retainer for a ball bearing and a ball bearing suitable for a high-speed motor. Background Art

[0002] Usually, in order to support the rotating parts of various rotating machines, Fig.11 The ball bearing 1 is as shown. The ball bearing 1 comprises: an inner ring 3 having an inner ring raceway 2 on the outer circumferential surface; an outer ring 5 which is arranged concentrically with the inner ring 3 and has an outer ring raceway 4 on the inner circumferential surface; and a plurality of balls 6 which are arranged between the inner ring raceway 2 and the outer ring raceway 4 so as to roll freely. Each ball 6 is held by a retainer 100 so as to roll freely. In addition, the outer circumferential edges of annular protective plates 7, 7 are respectively clamped on the inner circumferential surfaces at both ends of the outer ring 5, and the protective plates 7, 7 are used to prevent lubricants such as grease in the bearing space from leaking to the outside, or dust floating outside from entering the bearing space. In addition, as a sealing device, a contact type seal can also be used instead of the non-contact type protective plates 7, 7.

[0003] like Fig.12 As shown, the retainer 100 uses a crown-shaped retainer made of plastic, and includes an annular main portion 109 and a plurality of column portions 110 protruding axially from the main portion 109 at predetermined intervals in the circumferential direction, and spherical pockets 111 for retaining the balls 6 are formed between adjacent column portions 110. In addition, a pair of claw portions 112, 112 arranged at intervals from each other are formed at the distal end of the column portion 110, and the retainer 100 is prevented from falling off from between the outer ring 5 and the inner ring 3 in the axial direction by retaining the balls 6.

[0004] If the retainer 100 used in such a ball bearing is used at high speed, stress is applied due to centrifugal force, and the claws 112, 112 are deformed toward the outer diameter side. As a result, the retainer 100 contacts other components such as the outer ring 5 and the guard plates 7, 7, and the retainer 100 may be worn or damaged.

[0005] The retainer described in Patent Document 1 includes an annular main portion and an elastic piece protruding from the annular main portion to one side in the axial direction, and a cutout portion is provided on the outer diameter surface of the elastic piece so that the outer diameter of the elastic piece is smaller than the outer diameter of the annular main portion. Thus, the elastic piece is prevented from contacting the outer ring and the protective plate when deformed.

[0006] In addition, the retainer described in Patent Document 2 has an annular base and an axial portion extending from the base in the axial direction, the outer diameter of the axial portion is smaller than the outer diameter of the base, and a hole is formed in the base that passes through the axial direction and communicates with the recessed area of ​​the axial portion. Thus, the amount of material is reduced and deformation in the radial direction induced during high-speed rotation is suppressed.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2003-329045

[0010] Patent Document 2: Japanese Patent No. 5436204 Summary of the invention

[0011] Technical problem that the invention aims to solve

[0012] However, in the retaining frame described in Patent Document 1, the deformation of the elastic sheet as the column portion may increase during high-speed rotation, and further improvement is needed. In addition, in the retaining frame described in Patent Document 2, although the axial portion as the column portion is lightweight and the centrifugal force during high-speed rotation is reduced, the rigidity of the base portion is reduced due to the axial through hole formed in the base portion that is connected to the recessed area of ​​the axial portion, which is disadvantageous in terms of the deformation of the retaining frame. The situation where the base portion is connected without a through hole is advantageous in terms of the deformation of the retaining frame. In addition, in any retaining frame, in order to reduce the weight, it is considered to make the main portion (base) thinner at the bottom of the pocket, but there is a problem that the stress of the retaining frame increases during high-speed rotation and the deformation of the claw portion increases.

[0013] The present invention has been completed in view of the above situation, and its purpose is to provide a crown-type retainer and ball bearing for a ball bearing, which are not easy to contact with other parts even when deformed due to centrifugal force during high-speed rotation, and can reduce the centrifugal force during high-speed rotation by reducing the weight while ensuring the rigidity at specified positions to suppress deformation during high-speed rotation.

[0014] Technical solutions to the problem

[0015] The above object of the present invention is achieved by the following structure.

[0016] (1) A crown-type retainer for a ball bearing, comprising:

[0017] a main portion having a circular shape; and

[0018] a plurality of column portions, the plurality of column portions protruding from the main portion in the axial direction at predetermined intervals in the circumferential direction, and each of the column portions having a pair of claw portions arranged at a distance from each other at a distal end thereof,

[0019] Spherical pockets are formed between adjacent columnar portions, and the pockets are capable of retaining balls.

[0020] The column portion is formed such that the outer peripheral surface on the side of the tip portion including the pair of claw portions is located on the inner diameter side relative to the outer peripheral surface of the main portion.

[0021] On the inner diameter side of the retainer, a plurality of weight-reducing portions are separately formed at positions of the respective column portions above the circumferential direction, and are cut in the axial direction from the axial side surface of the main portion over the respective column portions.

[0022] Each of the weight-reducing portions is formed away from the surface of the pocket and away from the axial outer side surface of the column portion formed between the pair of claw portions,

[0023] When an axial dimension of a wall portion formed between an axially outer side surface of the column portion and an inner wall surface of the lightening portion is T1 and an axial dimension of the main portion at the bottom of the pocket is T2, T2>T1.

[0024] (2) The crown type retainer for a ball bearing according to (1),

[0025] The outer peripheral surface of the distal end side of the column portion is radially located between a position 1 / 2 of the radial thickness T of the main portion from the inner peripheral surface of the retainer and a position 3 / 4 of the radial thickness T from the inner peripheral surface of the retainer.

[0026] (3) The crown type retainer for a ball bearing according to (1) or (2),

[0027] When the radial thickness of the main portion is set to T, T2>T / 4.

[0028] (4) A crown-type retainer for a ball bearing according to any one of (1) to (3),

[0029] The outer peripheral surface of the terminal end portion of the column portion is connected to the outer peripheral surface of the main portion via a concave curved surface, and the curved surface has a curvature radius of 25 to 55% of the radial thickness T of the main portion.

[0030] (5) A crown-type retainer for a ball bearing according to any one of (1) to (4),

[0031] The minimum radial thickness T3 of the column portion where the lightened portion is formed is substantially equal to the axial dimension T1 of the wall portion.

[0032] (6) In the crown-type retainer for a ball bearing according to any one of (1) to (6), the entrance diameter of the pocket is 90 to 95% of the ball diameter.

[0033] (7) In the crown-type retainer for a ball bearing according to any one of (1) to (6), the center of the pocket passes through the wall portion in the axial direction.

[0034] (8) A ball bearing comprising: an outer ring; an inner ring; a plurality of balls, wherein the plurality of balls are arranged between raceway surfaces of the outer ring and the inner ring; and the crown-type cage according to any one of (1) to (7).

[0035] Effects of the Invention

[0036] According to the crown-type retainer and ball bearing for ball bearings of the present invention, even if they are deformed due to centrifugal force during high-speed rotation, they are not easy to contact with other parts, and can reduce the centrifugal force during high-speed rotation by reducing the weight while ensuring the rigidity at specified locations to suppress deformation during high-speed rotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a perspective view of a crown-type cage for a ball bearing according to one embodiment of the present invention.

[0038] Figure 2 yes Figure 1 Front view of the crown cage.

[0039] Figure 3 yes Figure 2 Cross-sectional view of the crown type cage along line III-III.

[0040] Figure 4 yes Figure 2 Cross-sectional view of the crown type cage along line IV-IV.

[0041] Figure 5 It is a front view of a crown-type cage for a ball bearing according to a modified example of the present invention.

[0042] Figure 6 yes Figure 5 Cross-sectional view of the crown type cage along line VI-VI.

[0043] Figure 7 (a) is a cross-sectional view along the axial direction passing through the center of the pocket of the crown type cage of Comparative Example 1, and (b) is a cross-sectional view along the axial direction passing through the circumferential middle position of the column portion of the crown type cage of Comparative Example 1.

[0044] Figure 8 (a) is a cross-sectional view along the axial direction passing through the center of the pocket of the crown type cage of Comparative Example 2, and (b) is a cross-sectional view along the axial direction passing through the circumferential middle position of the column portion of the crown type cage of Comparative Example 2.

[0045] Fig. 9Graphs showing the relationship between the rotation speed and the cage stress ratio in the embodiment, comparative example 1, and comparative example 2.

[0046] Fig.10 Graph showing the relationship between the rotation speed and the cage claw deformation ratio in the embodiment, comparative example 1, and comparative example 2.

[0047] Fig.11 This is a cross-sectional view showing an example of a ball bearing in which a cage is assembled.

[0048] Fig.12 It is a perspective view showing an example of a conventional structure of a cage.

[0049] Explanation of symbols

[0050] 10 Crown type cage for ball bearings

[0051] 11 Ring-shaped main part

[0052] 12 Column

[0053] 13 pockets

[0054] 14 claws

[0055] 20 Weight Loss Department

[0056] 21, 22 Wall

[0057] T Radial thickness of the main part

[0058] T1 Axial dimension of the wall

[0059] T2 Axial dimension of the main part at the bottom of the pocket

[0060] T3 Minimum radial thickness of the column with the lightened portion formed DETAILED DESCRIPTION

[0061] Hereinafter, a crown-type cage for a ball bearing and a ball bearing according to an embodiment of the present invention will be described with reference to the drawings.

[0062] like Figure 1 As shown, the crown type cage for ball bearings (hereinafter also referred to as "crown type cage" or simply "cage") 10 of the present embodiment is Fig.12 The cage of the prior art structure shown is also applicable to Fig.11 The ball bearing 1 shown in FIG. 1 is a crown-shaped retainer 10. That is, the crown-shaped retainer 10 includes: an annular main portion 11; and a plurality of column portions 12, which protrude from the main portion 11 in the axial direction at predetermined intervals in the circumferential direction. Spherical pockets 13 are formed between adjacent column portions 12, and the pockets 13 can retain the balls 6 (see FIG. 1 ). Figure 4). In addition, a pair of claws 14 , 14 are provided at the distal end of the column portion 12 . The pair of claws 14 , 14 are arranged at a distance from each other and form the opening side of the pocket 13 .

[0063] The crown cage 10 is made of synthetic resin materials such as polyamide resin, polyacetal resin, polyphenylene sulfide, polyetheretherketone, polyimide, etc., and is manufactured by injection molding. It should be noted that glass fiber, carbon fiber, aramid fiber, etc. may be added to the resin material as a reinforcing material.

[0064] In addition, if Figure 2 to Figure 4 As shown, in the crown-shaped cage 10, the column portion 12 is formed such that the outer peripheral surface 12a on the distal end side including the pair of claws 14 is located closer to the inner diameter side than the outer peripheral surface 11a of the main portion 11. Figure 2 As shown, a diameter D2 of an imaginary circle C connecting the outer peripheral surfaces 12 a on the distal end side of each column portion 12 is smaller than an outer diameter D1 of the outer peripheral surface 11 a of the main portion 11 .

[0065] In addition, if Figure 4 As shown, in the column portion 12, the outer peripheral surface 12a on the side of the tip portion extends axially to the main portion 11 side relative to the center O of the pocket 13, and is connected to the outer peripheral surface 11a of the main portion 11 by the concave curved surface 12b. The concave curved surface 12b has a curvature radius of 25 to 55% of the radial thickness T of the main portion 11. In this way, the concave curved surface 12b has a curvature radius of 55% or less of the radial thickness T of the main portion 11, thereby suppressing the volume of the column portion 12, and having a good effect of suppressing the deformation of the retainer 10 caused by the centrifugal force.

[0066] Specifically, the outer peripheral surface 12a on the terminal end side of the column portion 12 is located between a position that is 1 / 2 of the radial thickness T of the main portion 11 from the inner peripheral surface of the retainer 10 and a position that is 3 / 4 of the radial thickness T from the inner peripheral surface of the retainer 10. In addition, in the present embodiment, the outer peripheral surface 12a on the terminal end side is located at a position that is 1 / 2 of the radial thickness T of the main portion 11 from the inner peripheral surface of the retainer 10, that is, located on the pitch circle diameter PCD of the ball 6.

[0067] In addition, on the inner diameter side of the crown-shaped retainer 10, at the positions of each column 12 in the circumferential direction, a plurality of weight-reducing portions 20 are separately formed, which are cut in the axial direction from the axial outer side surface 11b of the main portion 11 to each column 12. The plurality of weight-reducing portions 20 are formed so as to be open on the inner diameter side and the axial outer side surface 11b side of the main portion 11, and on the other hand, be away from the surface of the pocket 13 and the axial outer side surface 12c of the column 12 formed between the pair of claws 14, 14. Furthermore, wall portions 21, 22 are formed between the surface of the pocket 13 and the inner wall surface 20a of the weight-reducing portion 20, and between the axial outer side surface 12c on the terminal side of the column 12 and the inner wall surface 20a of the weight-reducing portion 20, respectively.

[0068] It should be noted that the inner circumference of the main portion 11 and the column portion 12, including the wall portions 21 and 22, excluding the lightening portion 20, constitutes the inner circumference of the retainer 10 having an inner diameter D3 (see Figure 2 ).

[0069] The lightened portion 20 is formed in a substantially fan-shaped shape so that the circumferential width gradually decreases from the axially outer side surface 11b of the main portion 11 to each column portion 12. The lightened portion 20 is cut at the same depth so that the radial minimum thickness T3 of the column portion 12 defined between the inner circumferential surface thereof and the outer circumferential surface 12a on the terminal end side of the column portion 12 becomes the same thickness dimension in the entire circumferential direction.

[0070] Here, refer to Figure 3 as well as Figure 4 , when the axial dimension (thickness) of the wall portion 22 formed between the axial outer side surface 12c on the terminal side of the column portion 12 and the inner wall surface 20a of the lightening portion 20 is set to T1, and the axial dimension of the main portion 11 at the bottom of the pocket 13 (hereinafter also referred to as "bottom thickness") is set to T2, it is designed to be T2>T1. As a result, the bottom thickness T2 can be sufficiently ensured, and the cage stress under the action of centrifugal force can be reduced. In addition, the axial dimension T1 of the wall portion 22 can be thinned to a thickness that does not cause problems in injection molding, thereby achieving weight reduction and suppressing deformation in the circumferential direction during high-speed rotation.

[0071] In the present embodiment, the bottom thickness T2 satisfies the relationship T2>T / 4 with respect to the radial thickness T of the main portion 11 . Therefore, the bottom thickness T2 can be further sufficiently ensured, and the cage stress when the centrifugal force acts can be reduced.

[0072] In addition, the radial minimum thickness T3 of the column portion 12 formed with the lightening portion 20 is designed to be substantially equal to the axial dimension T1 of the wall portion 22 to avoid problems in injection molding. Thus, the radial minimum thickness T3 of the column portion 12 is made as thin as possible, achieving lightweighting of the retainer 10.

[0073] Furthermore, the center O of the pocket 13 is formed to pass through the wall portion 22 in the axial direction, so that the retainer 10 is not easily dislodged from the ball 6 during high-speed rotation. In particular, in the present embodiment, the center O of the pocket 13 is axially aligned with the axially outer side surface 12c of the wall portion 22.

[0074] In addition, the inlet diameter e of the pocket 13 at the position of the pitch circle diameter PCD of the ball 6 is 90 to 95% of the ball diameter. By reducing the inlet diameter e, the contact with the guard plate 7 and the sealing component caused by the fall of the retainer 10 is prevented. Usually, since the thickness of the claw 14 is relatively thick, if the inlet diameter e is reduced, the claw 14 may turn white or be damaged during demolding during injection molding or assembly to the ball 6. However, by reducing the thickness of the claw 14, it is easy to put the ball 6 into the pocket 13 even if the inlet diameter e is reduced, thereby eliminating the above concerns.

[0075] According to the crown-shaped retainer 10 of the present embodiment constructed in this way, the column portion 12 is formed so that the outer peripheral surface 12a on the side of the terminal portion including a pair of claw portions 14, 14 is located closer to the inner diameter side than the outer peripheral surface 11a of the main portion 11, thereby being able to suppress deformation caused by centrifugal force, and even when deformed by centrifugal force during high-speed rotation, it is difficult to contact other parts.

[0076] In addition, on the inner diameter side of the retaining frame 10, at the position of each column portion 12 in the circumferential direction, a plurality of weight reduction portions 20 are separately formed, which are cut axially from the axial side surface of the main portion 11 throughout each column portion 12, thereby being able to reduce the centrifugal force during high-speed rotation by reducing the weight.

[0077] Furthermore, the wall portion 22 is formed between the axially outer side surface 12c on the terminal side of the column portion 12 and the inner wall surface 20a of the lightening portion 20, and the axial dimension T2 of the main portion 11 at the bottom of the pocket 13 is made thicker than the axial dimension T1 of the wall portion 22, so that the rigidity of the portion of the main portion 11 constituting the bottom of the pocket 13 can be ensured and deformation during high-speed rotation can be suppressed. In addition, by leaving the wall portion 22 between the axially outer side surface 12c on the terminal side of the column portion 12 and the inner wall surface 20a of the lightening portion 20, deformation in the circumferential direction during high-speed rotation can be suppressed.

[0078] In addition, the present invention is not limited to the above-mentioned embodiment, and appropriate changes and improvements can be made.

[0079] For example, Figure 5The crown-shaped retainer 10a of the modified example shown is different from the first embodiment in the shape of the outer diameter side. Specifically, an axial side surface 11c of the main part 11 extending in the radial direction is formed between the outer peripheral surface 12a of the end portion side of the column part 12 and the outer peripheral surface 11a of the main part 11, and the outer peripheral surface 12a of the end portion side of the column part 12 and the axial side surface 11c of the main part 11 are connected by a concave curved surface 12d. In addition, in this modified example, the axial side surface 11c of the main part 11 is provided at a position slightly closer to the claw side from the groove bottom of the pocket 13 in the axial direction.

[0080] In this case, the crown-type cage 10a can be further reduced in weight compared with the above-described embodiment.

[0081] The other structures are the same as those of the crown-shaped cage 10 of the above-mentioned embodiment.

[0082] Example

[0083] Here, using Figure 1 The crown type cage 10 of the embodiment of the structure shown, Figure 7 The crown-shaped cage 10a of Comparative Example 1 shown in FIG. Figure 8 For the crown type cage 10b of Comparative Example 2 shown, the relationship between the rotation speed and the cage stress ratio and the relationship between the rotation speed and the cage claw portion deformation ratio were analyzed.

[0084] Comparative Example 1 is a specification in which the bottom thickness of the pocket 13 is thinned to a thickness that does not cause problems in injection molding in order to reduce the weight of the retainer 10a. Compared with Comparative Example 1, Comparative Example 2 is a specification in which the bottom thickness of the pocket 13 is thickened to a thickness that does not contact the sealing component in order to improve the rigidity of the retainer 10b. In addition, in Comparative Examples 1 and 2, a weight reduction portion 23 is formed in the radial middle portion of the retainers 10a and 10b at the position of each column portion 12 in the circumferential direction, which is cut from the axial side surface of the main portion 11 to each column portion 12 in the axial direction. Table 1 shows the bottom thickness T2 and weight of Example 1 and Comparative Example 2 in terms of ratios, respectively, when the bottom thickness T2 and weight of Comparative Example 1 are used as references.

[0085] in addition, Fig. 9 as well as Fig.10 The relationship between the rotation speed and the cage stress ratio and the relationship between the rotation speed and the cage claw deformation ratio in each cage are shown respectively. In addition, the cage stress ratio and the cage claw deformation ratio are expressed as a ratio when each value is 1 at 10000 rpm for the cage 10a of Comparative Example 1.

[0086] [Table 1]

[0087] Comparative Example 1 Comparative Example 2 Example Bottom thickness ratio (based on Comparative Example 1) 1 1.6 1.6 Weight ratio (based on Comparative Example 1) 1 1.14 0.8

[0088] In Comparative Example 1, the stress of the cage during high-speed rotation is significantly increased compared to Comparative Example 2 and the embodiment, so the deformation of the claw portion is also increased. As a result, it is found that reducing the bottom thickness for weight reduction is not advantageous for high-speed rotation.

[0089] On the other hand, it can be seen that in the embodiment in which the weight reduction is achieved by forming the weight reduction portion 20 by leaving the wall portion 22 at the end portion side of the column portion 12, the stress and deformation can be greatly reduced compared to Comparative Examples 1 and 2. In addition, it can be seen that the synergistic effect of reducing the thickness T1 of the wall portion 22 to a level that does not cause problems in injection molding to achieve weight reduction and making the bottom thickness of the pocket 13 thicker than the thickness T1 of the wall portion 22 can greatly reduce the stress and deformation.

[0090] It should be noted that the present application is based on Japanese patent application (Japanese Patent Application No. 2020-035971) filed on March 3, 2020, the contents of which are incorporated herein by reference.

Claims

1. A crown-type retainer for a ball bearing, characterized in that: have: a main portion having a circular shape; and a plurality of column portions, the plurality of column portions protruding from the main portion in the axial direction at predetermined intervals in the circumferential direction, and each of the column portions having a pair of claw portions arranged at a distance from each other at a distal end thereof, Spherical pockets are formed between adjacent columnar portions, and the pockets are capable of retaining balls. The column portion is formed such that the outer peripheral surface on the side of the tip portion including the pair of claw portions is located on the inner diameter side relative to the outer peripheral surface of the main portion. On the inner diameter side of the retainer, at the positions of the respective column portions in the circumferential direction, a plurality of weight-reducing portions are separately formed, which are cut in the axial direction from the axial side surface of the main portion to the respective column portions. Each of the weight-reducing portions is formed away from the surface of the pocket and away from the axial outer side surface of the column portion formed between the pair of claw portions, When the axial dimension of the wall portion formed between the axial outer side surface of the column portion and the inner wall surface of the lightening portion is set to T1, and the axial dimension of the main portion at the bottom of the pocket is set to T2, T2>T1, The outer peripheral surface of the distal end side of the column portion is radially located between a position 1 / 2 of the radial thickness T of the main portion from the inner peripheral surface of the retainer and a position 3 / 4 of the radial thickness T from the inner peripheral surface of the retainer.

2. The crown-type retainer for a ball bearing according to claim 1, characterized in that: When the radial thickness of the main portion is set to T, T2>T / 4.

3. The crown-type retainer for a ball bearing according to claim 1, characterized in that: The outer peripheral surface of the terminal end portion of the column portion is connected to the outer peripheral surface of the main portion via a concave curved surface, and the curved surface has a curvature radius of 25 to 55% of the radial thickness T of the main portion.

4. The crown-type cage for a ball bearing according to any one of claims 1 to 3, characterized in that: The minimum radial thickness T3 of the column portion where the lightened portion is formed is substantially equal to the axial dimension T1 of the wall portion.

5. The crown-type cage for a ball bearing according to any one of claims 1 to 3, characterized in that: The entrance diameter of the pocket hole is 90-95% of the ball diameter.

6. The crown-type retainer for a ball bearing according to claim 4, characterized in that: The entrance diameter of the pocket hole is 90-95% of the ball diameter.

7. The crown-type cage for a ball bearing according to any one of claims 1 to 3, characterized in that: In a cross section perpendicular to the circumferential direction, the center of the pocket passes through the wall portion in the axial direction.

8. The crown-type retainer for a ball bearing according to claim 4, characterized in that: In a cross section perpendicular to the circumferential direction, the center of the pocket passes through the wall portion in the axial direction.

9. The crown-type retainer for a ball bearing according to claim 5, characterized in that: In a cross section perpendicular to the circumferential direction, the center of the pocket passes through the wall portion in the axial direction.

10. A ball bearing, characterized in that: have: Outer ring; Inner circle; a plurality of balls, wherein the plurality of balls are arranged between the raceway surfaces of the outer ring and the inner ring; and The crown type cage according to any one of claims 1 to 9.

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