WO2019198762A1 - Crown-shaped retainer for deep-groove ball bearing, and deep-groove ball bearing - Google Patents

Abstract

A crown-shaped retainer (20) for a deep-groove ball bearing, wherein a plurality of pockets (30) comprise: first pockets (31) that are each formed between column portions (22) that comprise hook portions (23); and second pockets (32) that each have a pair of side walls (24) that are respectively formed in adjacent column portions (22), and a flat bottom portion (25) that is formed in an annular portion (21). A minimum thickness Ts of the annular portion (21) in the first pockets (31), and a bottom portion thickness Tc of the annular portion (21) in the second pockets (32), satisfy Ts>Tc. Thus, the retainer is configured to be supported in the axial direction, the number of balls therein can be increased, and, even if a burr occurs, the behavior of the balls is not affected.

Description

Crown type cage for deep groove ball bearings and deep groove ball bearings

The present invention relates to a crown type cage for a deep groove ball bearing and a deep groove ball bearing.

Generally, as a plastic cage applied to a deep groove ball bearing, a crown-shaped cage having a spherical pocket is used, so that the cage does not fall off between the outer ring and the inner ring in the axial direction. Has elastic nails to hold balls in pockets.

On the other hand, the cage described in Patent Document 1 has a plurality of first pockets provided with claws that hold the cage in the axial direction, and a plurality of second pockets that do not have the claws. By providing large gaps in the radial direction and the circumferential direction, the pockets of each of the pockets can reduce friction between the cage and the ball and can be manufactured at low cost.

Further, in the cage described in Patent Document 2, a cylindrical pocket is formed over the whole by a partition wall that extends from the plate portion and holds balls at regular intervals, and the cage is a plate having a partition wall. It is held in the axial direction by adopting a two-part structure consisting of a portion and a substantially annular plate fitted to the partition.

Japanese Utility Model Registration No. 3122529 Japanese National Utility Model Publication No. 2-94954

By the way, when manufacturing a plastic product at a low cost, an injection molding called an axial draw method is applied, and it is also used for manufacturing the above-described crown type cage. On the other hand, in deep groove ball bearings, when increasing the number of balls for the purpose of increasing load capacity, etc., it is necessary to reduce the circumferential distance between adjacent pockets. Since the circumferential length is also shortened, it is difficult to manufacture the cage by injection molding.

In injection molding, a pin called an ejector pin (hereinafter abbreviated as EP) for pushing the product in the axial direction is used for the purpose of removing the product from the mold. Since there is a possibility that burrs may occur on the surface of the product pressed by this EP, in the conventional plastic cage, the EP is pressed against the end face of the column portion which does not affect the function even if the burrs are generated. However, in a bearing with a large number of balls, since the pillar portion is thin, the surface to be pressed by EP cannot be secured, and even if secured, the stiffness of the pillar portion is insufficient and there is a risk of deformation.

Even in the cage described in Patent Document 1, when the number of balls is to be increased, the column portion becomes thin. Therefore, when taking out a product during injection molding, the flat surface pressed by EP is the bottom of the second pocket. It will be. However, no measures are taken against burrs that may occur at the bottom of the second pocket, and the balls may come into contact with the burrs and hinder the behavior of the balls.

On the other hand, in the cage described in Patent Document 2, when the product is taken out by EP, the ball may come into contact with the burr generated on the plane of the plate portion, and the behavior of the ball may be hindered. Moreover, since the cage is composed of two parts, the number of assembly steps increases and the number of parts increases, resulting in high costs.

The present invention has been made in view of the above circumstances, has a function of being held in the axial direction, and has a configuration capable of increasing the number of balls, and even if burrs are generated, the deep groove ball does not affect the behavior of the ball. An object of the present invention is to provide a crown type cage and a deep groove ball bearing for a bearing.

The above object of the present invention can be achieved by the following constitution.
(1) Annulus part,
A plurality of pillars protruding in the axial direction at predetermined intervals in the circumferential direction from the annular part,
A deep cage ball bearing for a deep groove ball bearing that forms a plurality of pockets capable of holding balls between adjacent pillars,
The plurality of pockets are
A first pocket formed between the pillars having a claw part;
A second pocket having a pair of side walls respectively formed on the adjacent column parts and a flat bottom part formed on the annular part;
Have
A crown type cage for deep groove ball bearings, wherein a minimum thickness Ts of the annular portion in the first pocket and a bottom thickness Tc of the annular portion in the second pocket satisfy Ts> Tc.
(2) The height Hc of the column portion not provided with the claw portion is Hs, the height of the column portion provided with the claw portion is Hs, the height of the center of the first pocket is Hp, and the opening side of the first pocket The crown type cage for deep groove ball bearings according to (1), wherein M is the amount of movement of the ball to, and satisfies Hp + M <Hc <Hs.
(3) A deep groove ball bearing comprising an outer ring, an inner ring, a plurality of balls disposed between raceways of the outer ring and the inner ring, and the crown type cage described in (1) or (2).

According to the crown type cage of the present invention, the plurality of pockets are formed between the pillar portions including the claw portions, the first pocket, the pair of side walls respectively formed on the adjacent pillar portions, and the annular portion. A second pocket having a flat bottom formed thereon. As a result, the crown-shaped cage has a function of being held in the axial direction and has a configuration capable of increasing the number of balls, and is manufactured at a relatively low cost by injection molding. Further, the minimum thickness Ts of the annular part in the first pocket and the bottom thickness Tc of the annular part in the second pocket are configured to satisfy Ts> Tc. Thereby, at the time of manufacture, there is a possibility that burrs harmful to the behavior of the ball may occur at the bottom of the second pocket. However, even if the burrs are generated, the behavior of the ball can be unaffected. .

It is a longitudinal cross-sectional view of the deep groove ball bearing which concerns on 1st Embodiment of this invention. (A) is a perspective view of the cage of FIG. 1, and (b) is a front view of the cage. It is a perspective view which shows a part of holder | retainer. It is sectional drawing along the pitch circle diameter position which passes along the center of a pocket through a part of cage | basket | tool in order to demonstrate the height of the pillar part in each pocket, and the minimum thickness of the annular part in each pocket. In order to explain the movement amount of the ball in the spherical first pocket, it is a cross-sectional view of a part of the cage along the pitch circle diameter position passing through the center of the pocket. It is the schematic diagram which looked at a part of cage | basket from the outer diameter side in order to demonstrate the position of the burr | flash at the time of using the ejector pin from which a diameter differs. It is a perspective view of the cage for deep groove ball bearings concerning a 2nd embodiment of the present invention. It is a principal part expansion perspective view of the holder | retainer of FIG. When the side wall of a 2nd pocket is a cylindrical surface, it is a partial front view of the ball | bowl and cage | basket for demonstrating the pocket clearance gap when a ball | bowl changes greatly from a revolution track. When the side wall of a 2nd pocket is a flat surface, it is a partial front view of the ball | bowl and cage | basket for demonstrating the pocket clearance gap when a ball | bowl changes greatly from a revolution track.

(First embodiment)
Hereinafter, a crown type cage and a deep groove ball bearing for a deep groove ball bearing according to a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the deep groove ball bearing 10 of this embodiment includes an outer ring 11 having a raceway surface 11a on an inner peripheral surface, an inner ring 12 having a raceway surface 12a on an outer peripheral surface, and raceway surfaces of the outer ring 11 and the inner ring 12. A plurality of balls 13 disposed between 11a and 12a, and a crown-shaped cage 20 that holds the balls 13 so as to roll freely.

The crown-shaped cage 20 is made of a synthetic resin material such as polyamide resin, polyacetal resin, polyphenylene sulfide, polyether ether ketone, polyimide, and is manufactured by injection molding. In the resin material, glass fiber, carbon fiber, aramid fiber, or the like may be added as a reinforcing material.

The crown-shaped cage 20 includes an annular portion 21 and a plurality of column portions 22 protruding from the annular portion 21 in the axial direction at predetermined intervals in the circumferential direction, and between the adjacent column portions 22, A plurality (21 in the present embodiment) of pockets 30 capable of holding the balls 13 are formed.

As shown in FIGS. 2 and 3, the plurality of pockets 30 are arranged at equal intervals in the circumferential direction, and include a spherical first pocket 31 occupying 1/3 of the total number of pockets and the remaining 2/3. The cylindrical second pocket 32 is occupied. The first pocket 31 is provided between adjacent column portions 22 each having a claw portion 23 at the tip portion, and the entire first pocket 31 extends from both the claw portions 23 to the annular portion 21 in a spherical shape. Further, the second pocket 32 is formed in each of the adjacent column portions 22, and a pair of side walls 24 having a cylindrical surface whose central axis extends along the axial direction, and a flat bottom portion 25 formed in the annular portion 21. And is formed in a cylindrical shape. Each side wall 24 and the bottom portion 25 are connected by a curved connection portion.
Hereinafter, the column portion 22 provided with the claw portion 23 is referred to as a claw-type column portion 22a, and the column portion 22 not provided with the claw portion is referred to as a claw-less column portion 22b.

Accordingly, the spherical first pocket 31 in which the column portion 22 includes the claw portion 23 has a function of holding the retainer 20 in the axial direction, while the column portion 22 has a cylindrical second pocket 32 that does not include the claw portion. Does not have a function of holding the cage 20 in the axial direction.

In order to prevent the retainer 20 from falling off, the number of spherical first pockets 31 increases as the holding force increases. On the other hand, the number of cylindrical second pockets 32 required for mold release decreases. Therefore, manufacturing becomes difficult. For this reason, it is desirable that the number of spherical first pockets 31 be at least three and arranged at equal intervals in the circumferential direction, and adjustment is performed according to the total number of pockets.

In addition, when the number of balls is expressed as (number of balls × ball diameter) / (ball pitch circle diameter × π) × 100%, in a general bearing, the value is 50% or more and less than 60%. However, in the present embodiment, it is possible to manufacture even with 60 to 75%. The value is more preferably 65 to 75% from the difficulty of mold release at the time of molding. If it exceeds 75%, the column portion 22 becomes too thin, and the resin does not flow during the injection molding, which may cause a failure.

4 shows the heights Hs and Hc of the pillar portions 22a and 22b of the pockets 31 and 32, the minimum thickness Ts of the annular portion 21 in the first pocket 31, and the bottom portion of the annular portion 21 in the second pocket 32. The thickness (minimum thickness) Tc is shown. The column portions 22 on both sides of the spherical first pocket 31 have claw portions 23 for holding the balls 13, but the column portion 22 sandwiched between the cylindrical second pockets 32 has no claw portion. The height Hc of the clawless column portion 22b is lower than the height Hs of the claw-equipped column portion 22a. Since the purpose of the nail-less column portion 22b is to isolate the balls 13 from each other, the height Hc of the nail-less column portion 22b is a ball held in the spherical first pocket 31, as shown in FIG. If the amount of movement is 13 (that is, the amount of movement of the ball from the center (ball center) of the first pocket 31 to the opening side of the first pocket 31) M is higher than the height Hp of the center O of the first pocket 31 Good. The moving amount M of the ball 13 is represented by the following formula (1).

here,
M: Ball travel distance D: Ball diameter C: Pocket clearance of the first pocket P: Pocket opening diameter of the first pocket

On the other hand, if the column portion 22 is higher than necessary, the stirring resistance due to grease or oil increases and the rotational torque increases, so the height Hc of the clawless column portion 22b is smaller than the height Hs of the column portion 22a with claw. To do. Accordingly, the height Hc of the clawless column portion 22b is expressed by the following formula (2).
Hp + M <Hc <Hs (2)

The height Hs of the claw-equipped column portion 22a, the height Hc of the claw-free column portion 22b, and the height Hp of the center O of the first pocket 31 are all heights from the annular portion side end surface 20a of the cage 20. I am trying. The annular portion side end surface 20a is a side surface in which the column portion 22 is not formed among the axial side surfaces of the annular portion 21, and is formed on an annular flat surface.
Further, the claw portion 23 has the same height as the height Hc of the claw-less column portion 22b and is continuous with the side wall 24 of the adjacent second pocket 32 from the axial plane 26 of the column portion 22a. It is formed to extend to the side.

Further, the minimum thickness Ts of the annular portion 21 in the first pocket 31 and the bottom thickness Tc of the annular portion 21 in the second pocket 32 satisfy Ts> Tc. Preferably, the bottom thickness Tc of the annular portion 21 in the second pocket 32 is set to 70 to 90% with respect to the minimum thickness Ts of the annular portion 21 in the first pocket 31 (0.7Ts ≦ Tc ≦ 0. 9Ts).

Thus, when the mold is released, the bottom portion 25 of the annular portion 21 in the second pocket 32 is pressed by the ejector pin (EP), but even if a burr occurs on the surface of the bottom portion 25 pressed by the EP, Since the balls 13 in the pockets 32 are prevented from coming into contact with the bottom 25, the behavior of the balls 13 is not affected by burrs.
Also, the height of the burr varies depending on the injection molding equipment and mold, but if the bottom thickness Tc in the second pocket 32 is significantly reduced in consideration of burr, the resin will not flow during the injection molding, resulting in a failure. By providing a difference in degree, even if burrs occur on the bottom portion 25 of the annular portion 21 in the second pocket 32, the ball 13 can be manufactured without affecting the behavior. Further, since this burr is generated in accordance with the diameter of the EP, the EP diameter is increased, and the position where the burr is generated is separated from the center position of the ball, thereby preventing interference with the ball 13 as shown in FIG. it can. Conversely, the effect can be expected by reducing the EP diameter and installing a plurality of EPs at positions away from the center position of the ball 13 (that is, the center position in the circumferential direction of the second pocket 32). FIG. 6 schematically shows the burrs when the EP diameters are pressed by EPs of φD _EP1 and φD _EP2 .

Since the inner peripheral surface of the first pocket 31 is formed in a spherical shape, the axial thickness of the first pocket 31 in the annular portion 21 varies depending on the radial position and the circumferential position of the first pocket 31. To do. The thickness of the annular portion 21 in the first pocket 31 is the smallest at the center position of the first pocket 31 (position that is the center in the radial direction and the center in the circumferential direction). In the case of the present embodiment, the radial center of the first pocket 31 (= the position where the pitch circle diameter of the ball is located) is positioned at the radial center of the annular portion 21 (column portion 22).
On the other hand, since the bottom portion 25 of the second pocket 32 is a flat surface parallel to the annular portion side end surface 20a of the annular portion 21, the bottom thickness of the annular portion 21 in the second pocket 32 is determined in the radial direction and the circumferential direction. It is constant regardless of the position of the direction.

As described above, according to the crown type cage 20 of the present embodiment, the plurality of pockets 30 are formed between the first pockets 31 that are formed between the column portions 22 including the claw portions 23 and the adjacent column portions 22. And a second pocket 32 having a flat bottom portion 25 formed in the annular portion 21. Thereby, the crown type cage 20 has a function of being held in the axial direction and can increase the number of balls, and is manufactured at a relatively low cost by injection molding. The minimum thickness Ts of the annular portion 21 in the first pocket 31 and the bottom thickness Tc of the annular portion 21 in the second pocket 32 are configured to satisfy Ts> Tc. Thereby, at the time of manufacture, a burr harmful to the behavior of the ball 13 may occur at the bottom 25 of the annular portion 21 in which the second pocket 32 is formed. The configuration can be made unaffected.

Further, the height Hc of the column portion 22b not provided with the claw portion is Hs, the height of the column portion 22a provided with the claw portion 23 is Hs, the height O of the center O of the first pocket 31 is Hp, and the center of the first pocket 31. When the movement amount of the ball 13 from O to the anti-annular part side is M, Hp + M <Hc <Hs is satisfied. Therefore, by defining the height Hc of the pillar portion 22b, the balls 13 can be reliably isolated in the second pocket 32.

(Second Embodiment)
Next, a crown type cage for a deep groove ball bearing and a deep groove ball bearing according to a second embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 7 and 8, the crown-shaped cage 20a of the second embodiment is different from that of the first embodiment in that the side wall 24a of the second pocket 32 is a flat surface. Thereby, in this embodiment, even when it is used in such a way that the revolution trajectory of the ball 13 changes greatly, it is difficult for the ball 13 and the pillar portion 22b to collide, and the possibility that the pillar portion 22b is damaged is suppressed. Can do.

For example, as shown in FIG. 9, when the side wall 24 of the second pocket 32 is a cylindrical surface, if the center of the ball 13 changes from the radial intermediate position of the crown-shaped cage 20a to the outer diameter side, the ball 13 and the column The circumferential gap with the portion 22b becomes small (the circumferential gap C1 when the ball 13 is in the radial intermediate position of the second pocket 32> the circumferential gap C2 when the ball 13 is at the outer diameter side position of the second pocket 32. ). Therefore, when the ball 13 is used in such a way that the revolution trajectory of the ball 13 changes greatly, the ball 13 and the column portion 22b collide with each other due to the revolution speed difference of the ball 13 of each phase, and the column portion 22b is damaged. There is a possibility.

On the other hand, as shown in FIG. 10, when the side wall 24a of the 2nd pocket 32 is a flat surface, even if the revolution track of the ball | bowl 13 changes greatly, the reduction | decrease of the circumferential clearance between the ball | bowl 13 and the pillar part 22b is suppressed. (The ball 13 has a circumferential gap C1 ′ in the radial intermediate position of the second pocket 32 and the ball 13 has a circumferential gap C2 ′ in the outer diameter side position of the second pocket 32). It is difficult for the portion 22b to collide.

In the present embodiment, the ball 13 and the pillar portion 22b are less likely to collide with each other, so that the width of the opening in the radial direction of the second pocket 32 is an opening on the outer diameter side than the width W1 of the opening on the inner diameter side. It is preferable to increase the side width W2.
Other configurations and operations are the same as those in the first embodiment.

In addition, this invention is not limited to embodiment mentioned above, A change, improvement, etc. are possible suitably.
For example, in the above embodiment, the first pocket is spherical and the second pocket is formed in a cylindrical shape or a planar shape. However, the shape of each pocket of the crown type cage of the present invention is not limited to this. In other words, the first pocket may be formed between the pillar portions having the claw portions, and the second pocket is formed in the pair of side walls formed in the adjacent pillar portions and the annular portion. What is necessary is just to have a flat bottom portion.

This application is based on a Japanese patent application (Japanese Patent Application No. 2018-075481) filed on April 10, 2018, the contents of which are incorporated by reference into this application.

DESCRIPTION OF SYMBOLS 10 Deep groove ball bearing 11 Outer ring 11a Raceway surface 12 Inner ring 12a Raceway surface 13 Ball | bowl 20, 20a Crown type holder 21 Ring part 22 Pillar part 22a Claw pillar part 22b Clawless pillar part 23 Claw part 30 Pocket 31 First pocket 32 2nd pocket Hc Height of pillar part without claw Hs Height of pillar part with claw Tc Bottom thickness Ts of annular part in second pocket Minimum thickness of annular part in first pocket

Claims (3)

An annulus,
A plurality of pillars protruding in the axial direction at predetermined intervals in the circumferential direction from the annular part,
A deep cage ball bearing for a deep groove ball bearing that forms a plurality of pockets capable of holding balls between adjacent pillars,
The plurality of pockets are
A first pocket formed between the pillars having a claw part;
A second pocket having a pair of side walls respectively formed on the adjacent column parts and a flat bottom part formed on the annular part;
Have
A crown type cage for deep groove ball bearings, wherein a minimum thickness Ts of the annular portion in the first pocket and a bottom thickness Tc of the annular portion in the second pocket satisfy Ts> Tc. The height Hc of the column portion not provided with the claw portion is Hs, the height of the column portion provided with the claw portion is Hs, the height of the center of the first pocket is Hp, and the height toward the opening side of the first pocket is The crown type cage for a deep groove ball bearing according to claim 1, wherein when the amount of movement of the ball is M, Hp + M <Hc <Hs is satisfied. A deep groove ball bearing comprising an outer ring, an inner ring, a plurality of balls disposed between raceways of the outer ring and the inner ring, and the crown type cage according to claim 1.

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