JP4291448B2 - Synthetic resin cage cage for ball bearings - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crown type cage for a ball bearing in which a plurality of ball holding pockets are provided on one surface of an annular body along a circumferential direction.
[0002]
[Prior art]
Precision devices such as hard disk drives are strongly required to have high performance and downsizing, and many ball bearings equipped with such precision devices are often used as sealed bearings with a minimum diameter of several millimeters. ing.
[0003]
As shown in FIGS. 6 to 8, as the cage (2) in the sealed ball bearing (1) having a very small diameter, a crown type made of a synthetic resin has been conventionally used. The retainer (2) has a plurality of ball retaining pockets (4) that open in the axial direction on one surface of the annular body (3) in the axial direction, and are formed at predetermined intervals in the circumferential direction. A grease reservoir recess (3a) is formed on one side of the direction corresponding to each of the ball holding pockets (4).
[0004]
Further, a pair of claw pieces (5) is formed at the opening edge of the ball holding pocket (4), and the pocket inner surface (4b) including the inner surfaces of the pair of claw pieces (5) is the ball center (O ) With a constant curvature corresponding to a sphere centered on).
[0005]
In the ball cage (2), the ball (8) is pushed into each ball holding pocket (4) from its opening (4a) so that the pair of claw pieces (5) are elastically expanded and deformed. By accommodating, the ball (8) is held in each holding pocket (4) so as to be able to roll by the elastic restoring force of the pair of claw pieces (5).
[0006]
The cage (2) holding the balls (8) in this way is, as shown in FIG. 6, with the grease retaining recess (3a) filled with lubricating oil such as grease, and the inner ring (1a) of the bearing (1). And the outer ring (1b), the bearing (1) is configured.
[0007]
In this bearing (1), for example, the inner ring (1a) rotates smoothly with respect to the outer ring (1b) based on the rolling contact of the ball (8), and at the time of rotation, lubricating oil is supplied to the ball surface, The contact portion between (8) and the pocket inner peripheral surface and the contact portion between ball (8) and raceway rings (1a) and (1b) are lubricated.
[0008]
[Problems to be solved by the invention]
The pocket inner surface (4b) of the ball cage (2) in the conventional bearing (1) generally has a constant radius of curvature (R4) that is larger than the radius (R8) of the ball (8) by a predetermined gap. It is formed in a spherical concave surface. For this reason, the edge portion (4e) between the pocket inner surface and the inner peripheral surface and outer peripheral surface of the annular body (3) is formed at an acute angle, and lubricating oil such as grease adhered to the ball surface during ball rotation. However, it is scraped off at the edge part (4e), and there is a possibility that the ball contact part may not be sufficiently lubricated.
[0009]
On the other hand, in the prior art, the inner surface of both sides of the ball holding pocket inner surface is formed as a cylindrical surface (axial cylindrical surface) having an axial center in the axial direction (vertical direction toward the paper surface in FIG. 8) line, A ball cage has been proposed in which the inner surface is formed on a cylindrical surface (radial cylindrical surface) having an axial center on a radial direction (perpendicular to the paper surface of FIG. 8) line.
[0010]
However, since these ball cages hold spherical balls by the inner surfaces of both side walls of the cylindrical pocket, the inner surfaces of the side walls cannot be made to correspond to the outer peripheral surfaces of the balls. In addition to not being able to obtain a force, a large gap is partially formed between the inner surface of both side walls of the pocket and the outer peripheral surface of the ball, and a large amount of lubricating oil is taken into the gap. There was a risk that the rotational load of the ball would increase and the ball rotation characteristics would deteriorate.
[0011]
The present invention solves the above-mentioned problems of the prior art, can prevent a shortage of lubricant and excessive lubricant, can take in an appropriate amount of lubricant, can maintain a sufficient lubrication state, An object of the present invention is to provide a ball bearing cage capable of obtaining holding characteristics and rotational characteristics.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a plurality of ball holding pockets are provided on one surface in the axial direction of the annular body so as to open in the axial direction and accommodate a ball so as to roll freely. In the ball bearing retainer provided, the ball retaining pocket is composed of a bottom wall, both side walls located on both sides in the circumferential direction of the bottom wall, and a pair of claw pieces for ball holding provided at the ends of the both side walls. In addition, each inner surface of the bottom wall, both side walls, and the pair of claw pieces has a curvature larger than the curvature of the ball and is formed by different types of spherical concave surfaces, The gist is that the closest position (ball proximity position) is set to a peripheral position on a circumferential line passing through the center of the ball.
[0013]
In the ball bearing retainer of the present invention, the inner surfaces of the pair of claw pieces, both side wall inner surfaces, and bottom wall inner surfaces of the ball holding pocket have curvatures larger than the curvature of the ball, and are different from each other by different types of spherical concave surfaces. Since it comprises, the clearance gap of a moderate magnitude | size is formed between adjacent inner surfaces. For this reason, the lubricant is appropriately taken into the gap, and the lubricant is appropriately supplied to the outer peripheral surface of the ball, so that the oil film can be prevented from being cut due to the lack of the lubricant.
[0014]
Moreover, since each inner surface of the ball holding pocket is constituted by a spherical concave surface, the inner surface can be made to correspond to the outer peripheral surface of the spherical ball, so that the ball can be held in a balanced manner by each inner surface. In addition, an excessive gap is not formed between the pocket inner surface and the ball, and it is possible to prevent excessive grease from being taken in.
[0015]
In addition, since the ball proximity position on the inner surfaces of both side walls of the pocket is set near the ball center line, the ball can be held with sufficient holding force from both sides in the circumferential direction at the ball proximity position.
[0016]
In the present invention, different types of spherical concave surfaces include not only those having different curvatures and centers of curvature, but also those having the same curvature and different centers of curvature, and those having different curvatures and the same center of curvature.
[0017]
On the other hand, in the present invention, it is preferable to adopt a configuration in which the ball proximity positions on the inner surfaces of both side walls are set on a circumferential line passing through the center of the ball.
[0018]
That is, when this configuration is employed, the ball can be reliably held from both sides in the circumferential direction at the ball proximity position on the inner surfaces of the pocket side walls.
[0019]
Furthermore, in the present invention, it is preferable to adopt a configuration in which the ball proximity position on the inner surfaces of both side walls is set to a position shifted in the axial direction from a circumferential line passing through the center of the ball.
[0020]
That is, when this configuration is adopted, it is possible to prevent the positional deviation of the ball in the axial direction at the ball proximate position on the inner surfaces of the pocket side walls.
[0021]
Further, in the present invention, the center of curvature of the inner surfaces of both side walls of the ball holding pocket is set at a position farther from the axial line passing through the center of the ball, the center of curvature of the bottom wall of the ball holding pocket, The configuration that is set at a position closer to the claw piece than the ball center on the axial line passing through the ball center, or the center of curvature of the pair of claw pieces of the ball holding pocket is more than the ball center on the axial line passing through the ball center Also, it is desirable to adopt a configuration that is set at the position on the bottom wall side.
[0022]
That is, when these configurations are employed, the configuration of the present invention can be formed accurately and accurately.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
FIGS. 1 to 4 are views showing a synthetic resin crown-shaped ball cage (10) for a bearing according to a first embodiment of the present invention. As shown in these drawings, the bearing retainer (10) has an annular body (11).
[0024]
A plurality of ball holding pockets (20) opening in the axial direction are provided at predetermined intervals in the circumferential direction on one surface side in the axial direction of the annular body (11).
[0025]
Further, a grease reservoir recess (12) is formed between each of the ball holding pockets (20) in the annular body (11).
[0026]
Each ball holding pocket (20) of the ball cage (10) includes a bottom wall (23), both side walls (22) formed to rise on both sides in the circumferential direction of the bottom wall (23), and both side walls. At the tip, in other words, at the opening edge of the pocket (20), the side edges of the pocket opening (25) are closed to form a pair of elastic claw pieces (21). Therefore, the inner surface of the ball holding pocket (20) is defined by the inner surface (21a) of the pair of claw pieces (21), the inner surfaces (22a) of the side walls (22), and the inner surface (23a) of the bottom wall (23). Composed.
[0027]
Furthermore, each inner surface (21a)-(23a) of the ball holding pocket (20) has a curvature larger than the curvature of the ball (30), and is formed in different types of spherical concave surfaces. Street.
[0028]
That is, as shown in FIG. 2, the center of the ball (30) accommodated in the ball holding pocket (20) is “O”, and the circumferential line (ball center line) passing through the ball center (O) is “PL”. When the axial line passing through the ball center (O) is “AL”, the inner surface (21a) of the pair of claw pieces has a center of curvature (O1) on the ball center line (PL) on the axial line (AL). ) Is formed in a spherical concave surface set at a position lower than (position on the bottom wall side). Furthermore, the inner surface (22a) of both side walls (22) is formed in a spherical concave surface whose curvature center (O2) is set at a position farther from the axial line (AL) on the ball center line (PL). Yes. Further, the inner surface (23a) of the bottom wall (23) is a sphere whose center of curvature (O3) is set at a position higher than the ball center line (PL) on the axial direction line (AL) (position on one claw side). It is formed in a concave surface.
[0029]
Further, the position (ball proximity position: NP) closest to the outer peripheral surface of the ball on both side wall inner surfaces (22a) is set on the ball center line (PL).
[0030]
Here, the curvature of the inner surface (21a) of the pair of claw pieces in the ball holding pocket (20) is preferably set to 1.02c to 1.3c when the curvature of the ball (30) is “c”. More preferably, the lower limit value is set to 1.05c or more and the upper limit value is set to 1.2c or less.
[0031]
Furthermore, the curvature of the inner surfaces (22a) of both side walls is preferably set to 1.5c to 3.0c, and more preferably, the lower limit value is set to 1.8c or more and the upper limit value is set to 2.5c or less. .
[0032]
The curvature of the bottom wall inner surface (23a) is preferably set to 1.2c to 2.5c, and more preferably, the lower limit value is set to 1.4c or more and the upper limit value is set to 2.0c or less. .
[0033]
The dimension from the ball center (O) to the ball proximity position (NP) of the inner surface (22a) of both side walls is set to 1.01r to 1.10r when the radius of the ball (30) is “r”. More preferably, the lower limit value is set to 1.02r or more and the upper limit value is set to 1.07r or less.
[0034]
In other words, when these specified values are deviated, there is a possibility that sufficient ball holding force cannot be obtained, and furthermore, the amount of lubricating oil taken in becomes too small, resulting in poor lubrication, or lubricating oil. There is a possibility that the take-in amount of the ball will increase so much that the rotational load increases and the rotational characteristics of the ball (30) deteriorate.
[0035]
The ball holder (10) of the present embodiment is configured as described above. In each ball holding pocket (20) of the ball holder (10), the ball (30) is opened from the opening (25). Is inserted into the pocket (20) so that the pair of claw pieces (21) are elastically expanded and deformed on both sides, and the ball (30) is held by the elastic restoring force of the pair of claw pieces (25). . Thereby, a ball | bowl (30) is accommodated in the pocket (20) so that rolling is possible.
[0036]
In this way, the cage (10) holding the ball (30) is in a state where the grease reservoir recess (12) is filled with lubricating oil such as grease, as in the conventional example, between the inner ring and the outer ring of the bearing. To form a bearing.
[0037]
As described above, the cage (10) in this bearing has a pocket inner surface with a pair of claw piece inner surfaces (21a), both side wall inner surfaces (22a) and a bottom wall inner surface (23a) larger than the curvature of the ball (30). Therefore, a grease reservoir gap (40) having an appropriate size is formed between the adjacent inner surfaces. For this reason, the grease is appropriately taken into the gap (40), and the grease is appropriately supplied to the outer peripheral surface of the ball, so that it is possible to effectively prevent the oil film from running out of the ball (30) and insufficient grease. The lubrication state can be maintained.
[0038]
Further, since the pocket inner surfaces (21a) to (23a), in particular, both side wall inner surfaces (22a) are constituted by spherical concave surfaces, these pocket inner surfaces (21a) to (23a) are made to correspond to the spherical ball outer peripheral surfaces. Therefore, the balls (30) can be held in a well-balanced manner by the inner surfaces (21a) to (23a), and good ball holding characteristics can be obtained. In addition, since the ball proximity position (NP) is set on the ball center line (PL) on the inner surface (22a) of the both side walls of the pocket, the ball (30) is sufficiently removed from both sides in the circumferential direction at the ball proximity position (NP). Can be reliably held with a sufficient holding force, and the ball holding characteristics can be further improved.
[0039]
Further, since the pocket inner surfaces (21a) to (23a) can be made to correspond to the outer peripheral surface of the ball, an excessive gap is formed between the pocket inner surfaces (21a) to (23a) and the ball (30). Therefore, it is possible to prevent excessive grease from being taken in, to prevent an increase in rotational load due to excessive grease, and to obtain good rotational characteristics.
[0040]
<Second Embodiment>
FIG. 5 is a view showing a synthetic resin crown-shaped cage (110) for ball bearings according to a second embodiment of the present invention.
[0041]
As shown in the figure, in the inner surface shape of the ball holding pocket (120) in the cage (110), the inner surface (122a) of both side walls (122) has a center of curvature (O2) that is the ball center line (PL ) And a spherical concave surface set at a position distant from the axial line (AL). Further, when the radius of the ball (30) is “r”, the ball proximity position (NP) of the inner surface (122a) of both side walls is set to a position displaced 0.2r below the ball center line (PL). Yes.
[0042]
Since other configurations are the same as those of the first embodiment, the same or corresponding parts are denoted by the same or corresponding reference numerals, and redundant description is omitted.
[0043]
Also in this cage (110), since a moderately-sized grease reservoir gap (140) is formed between each of the inner surfaces (121a) to (123a), an appropriate amount of grease is formed in the gap (140). Can be taken in and good lubrication can be maintained.
[0044]
Further, since the pocket inner surfaces (121a) to (123a) can be made to follow the outer peripheral surface of the spherical ball, the inner surfaces (121a) to (123a) can hold the ball (30) in a well-balanced manner and are excessive. No gaps are formed, and grease is not taken in excessively. Furthermore, the ball (30) can be held from both sides with a sufficient holding force at the ball proximity position (NP) on the inner surfaces (122a) of the pocket side walls.
[0045]
Furthermore, since the ball proximity position (NP) is set at a position below the ball center line (PL), the downward force in the axial direction of the ball (30) is applied to the ball proximity positions of the side walls (122a). (NP) and the center (BP) of the bottom wall inner surface (123a) can be dispersed and received in a balanced manner, so that even better ball retention characteristics can be obtained and the ball (30) It is also possible to reliably prevent the downward displacement of the position.
[0046]
In the present invention, when the ball proximity position (NP) on the inner surfaces of both side walls is set to a position above the ball center line (PL) (position on the claw piece side), the ball is positioned by the ball proximity position (NP). There is a risk of being pushed downward in the axial direction, which is not preferable.
[0047]
Here, in the present invention, when the radius of the ball is “r”, the ball proximity position (NP) is preferably set to a position shifted by 0.5 r downward from the ball center line (PL). More preferably, it should be set between the position shifted by 0.3r. That is, when deviating from these specified ranges, there is a possibility that the effects specific to the present invention cannot be obtained.
[0048]
【The invention's effect】
As described above, according to the ball bearing retainer of the present invention, the pair of claw piece inner surfaces, both side wall inner surfaces, and the bottom wall inner surfaces of the ball holding pockets have respective curvatures larger than the curvature of the balls, and Since it is composed of different types of spherical concave surfaces, a moderately large gap is formed between the adjacent inner surfaces, so that the lubricant is appropriately taken into the gap and the lubricant is placed on the outer peripheral surface of the ball. The oil film is supplied as appropriate, so that the oil film can be prevented from being cut off due to lack of lubricant, and a good lubricating state can be maintained. In addition, since each inner surface of the pocket is constituted by a spherical concave surface, these inner surfaces can be made to correspond to the spherical ball outer peripheral surface, and the ball can be held in a well-balanced manner by each inner surface of the pocket, Good ball retention characteristics can be obtained. In addition, since the ball proximity position on the inner wall of both sides of the pocket is set near the ball center line, the ball can be held with sufficient holding force from both sides in the circumferential direction at the ball proximity position. Can be improved. In addition, since each inner surface of the pocket can be made to correspond to the outer peripheral surface of the ball, an excessive gap is not formed between the inner surface of the pocket and the ball, and it is possible to prevent excessive grease from being taken in. There is an effect that rotation characteristics can be obtained.
[0049]
In the present invention, when the ball proximity position on the inner surface of both side walls of the pocket is set on the ball center line, the ball can be reliably held from both sides in the circumferential direction at the ball proximity position, and the ball holding characteristics are further improved. There is an advantage that can be improved.
[0050]
Also, in the present invention, when the ball proximity position on the inner surface of both side walls of the pocket is set to a position shifted in the axial direction with respect to the ball center line, the positional deviation in the axial direction of the ball is prevented at the ball proximity position. There is an advantage that the ball retention characteristics can be further improved.
[0051]
Further, in the present invention, when the center of curvature of each inner surface of the ball holding pocket is set at a specific position, the configuration of the present invention can be formed accurately and accurately, and the above effect can be more reliably achieved. There is an advantage that can be obtained.
[Brief description of the drawings]
FIG. 1 is a front view showing a pocket portion of a ball bearing cage according to a first embodiment of the present invention.
FIG. 2 is an enlarged front view showing a half on one side of a pocket portion in the retainer of the first embodiment.
FIG. 3 is a perspective view showing a pocket portion in the retainer of the first embodiment.
FIG. 4 is a plan sectional view showing a half on one side of the cage according to the first embodiment of the present invention.
FIG. 5 is an enlarged front view showing one half of a pocket portion in a ball bearing cage according to a second embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a main part of a conventional ball bearing.
FIG. 7 is a perspective view showing a conventional ball bearing retainer.
FIG. 8 is an enlarged front view showing one half of a pocket portion in a conventional cage.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 110 ... Cage 11, 111 ... Ring body 20, 120 ... Ball holding pocket 21, 121 ... Claw piece 21a, 121a ... Claw piece inner surface 22, 122 ... Side wall 22a, 122a ... Side wall inner surface 23, 123 ... Bottom wall 23a , 123a ... bottom wall inner surface 30 ... ball NP ... ball proximity position O ... ball center 01 ... curvature center on the inner surface of the claw piece 02 ... curvature center on the inner surface of the side wall 03 ... curvature center on the inner surface of the bottom wall AL ... axial line PL ... circumferential direction line

Claims (6)

Synthetic resin crown-type ball bearing holder, which is provided with a plurality of ball-holding pockets that open in the axial direction on one surface of the annular body and accommodate the balls in a rollable manner. In the vessel
The ball holding pocket is composed of a bottom wall, both side walls located on both sides in the circumferential direction of the bottom wall, and a pair of nail pieces for holding a ball provided at the tip of both side walls,
Each inner surface of the bottom wall, both side walls, and the pair of claw pieces has a curvature larger than the curvature of the ball, and is formed by different types of spherical concave surfaces,
The position closest to the outer peripheral surface of the ball on the inner surfaces of both side walls (the ball proximity position) is set at a position displaced downward along the axial direction from the circumferential line passing through the center of the ball ,
A cage for ball bearings made of synthetic resin , characterized in that the center of curvature of the inner surfaces of both side walls of the ball holding pocket is set at a position farther from the axial line passing through the center of the ball . The cage for ball bearings made of synthetic resin according to claim 1, wherein the center of curvature of the bottom wall of the ball holding pocket is set at a position closer to the claw piece than the ball center on an axial line passing through the ball center. . The synthetic resin crown-shaped mold according to claim 1 or 2, wherein the center of curvature of the pair of claw pieces of the ball holding pocket is set at a position closer to the bottom wall than the ball center on an axial line passing through the ball center. Ball bearing cage. The ball bearing retainer according to any one of claims 1 to 3, wherein the curvature of the inner surfaces of the pair of claw pieces is set to 1.02c to 1.3c when the curvature of the ball is "c". . The ball bearing retainer according to any one of claims 1 to 4, wherein the curvature of the inner surfaces of both side walls is set to 1.5c to 3.0c when the curvature of the ball is "c". The ball bearing retainer according to any one of claims 1 to 5, wherein when the curvature of the ball is "c", the curvature of the inner surface of the bottom wall is set to 1.2c to 2.5c.

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