JP2016180436A - Crown type holder, ball bearing and bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crown type holder capable of suppressing occurrence of out particles, a ball bearing, and a bearing unit.SOLUTION: A pocket 41A of a crown type holder 33A has a spherical first pocket surface 45 formed on an outer ring side in a bearing radial direction, and a cylindrical second pocket surface 46 formed on an inner ring side in the bearing radial direction, having a central line L, as a central axis, extending in a radial direction through a center O of a pocket 41, and having a tangent line L1, as a bus line, passing through a spherical contact point at the position of a pocket pitch circle diameter (PCD) with the first pocket surface 45 as a reference.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crown type cage, a ball bearing, and a bearing unit, and more particularly, to a crown type cage, a ball bearing, and a bearing unit that are applied to a swing arm of a hard disk drive. About.

  FIGS. 5A to 5C illustrate an example of a schematic configuration of a hard disk drive (Hard Disc Drive (hereinafter also referred to as HDD)). The HDD includes a magnetic disk (hard disk) 2 for recording information (data), a spindle motor 4 for rotating the magnetic disk 2, a swing arm 8 as an actuator having a magnetic head 6 attached to the tip, A voice coil 9 is provided at the base end of the swing arm 8 and rotationally drives the swing arm 8.

  The swing arm 8 is rotatably supported on the base Bs of the HDD via the bearing unit 10, and when it is rotationally driven by the voice coil 9, the swing head 8 is attached to the rotating magnetic disk 2. Translate (trace). Thereby, in the HDD, information can be read from the magnetic disk 2 via the magnetic head 6 or information can be written (recorded) to the magnetic disk 2.

  The bearing unit 10 includes a shaft 12 erected on the base Bs of the HDD, a sleeve 18 on which the swing arm 8 is externally mounted, and ball bearings 14 and 16 interposed between the shaft 12 and the sleeve 18. Is provided.

  Further, the ball bearings 14 and 16 are a plurality of inner rings 30 and outer rings 31, and a plurality of rolling rings incorporated between the inner rings 30 and the outer rings 31 as a pair of bearing rings arranged so as to be relatively rotatable. , And a retainer 33 that rotatably holds the balls 32 one by one. Generally, grease lubrication is performed by grease enclosed in a bearing. Between the inner ring 30 and the outer ring 31, non-contact type shield members 34 and 34 for sealing the inside of the bearing are interposed, thereby preventing foreign matter (for example, dust) from entering the outside of the bearing. In addition, leakage of the grease composition sealed inside the bearing to the outside of the bearing is prevented.

  As the retainer 33, as shown in FIG. 6, a resin crown retainer is applied, and a plurality of spherical pockets 41 each having an opening 40 on one side in the axial direction are formed at predetermined intervals in the circumferential direction. Has been.

  The ball bearings 14 and 16 are configured such that the swing arm 8 mounted on the sleeve 18 is rotatable in a state where the inner ring 30 is fitted on the shaft 12 and the outer ring 31 is fitted on the sleeve 18. It is pivotally supported. An annular spacer 20 is fitted to the inner peripheral portion of the sleeve 18 so as to be interposed between the ball bearings 14 and 16. As a result, the ball bearings 14 and 16 are positioned and fixed at predetermined positions with a predetermined preload applied, and can be stably rotated without rattling, and the swing arm 8 can be rotated smoothly with good responsiveness. Can be made.

  Conventionally, as a crown type cage for ball bearings, a concave portion extending from a pocket opening edge on the inner diameter side of the cage to the outer diameter side of the cage is provided on the inner surface of the pocket so that grease leakage resistance is achieved even at high speed rotation. What was given is known (for example, refer to Patent Document 1).

JP 2009-257579 A

  By the way, with the improvement in performance of hard disks, the demand for cleanliness inside HDDs is increasing year by year. If foreign matter adheres to a magnetic disk, a read head, or the like inside the HDD, performance degradation, program error, or worst case HDD failure is caused. Therefore, high cleanliness is required for the internal components of the HDD.

  In particular, oil particles resulting from the grease of the pivot bearing unit that supports the swing arm occupy a large weight as one of the contamination factors inside the HDD. The inside of the bearing is kept lubricated by the base oil supplied from the grease, but at the same time, the base oil scatters as fine particles by sliding the parts against each other with the base oil interposed therebetween. In addition, since there is a strong air flow accompanying the high-speed rotation of the recording medium inside the HDD, minute particles are released to the outside of the bearing by the air flow, leading to contamination inside the HDD.

  In the conventional crown-shaped cage 33 shown in FIG. 6, the diameter of the spherical pocket 41 is designed to be slightly larger than the ball 32 so as to hold the ball 32 and not hinder the movement of the ball 32. For this reason, a gap is formed between the spherical pocket 41 and the ball 32, and a part of the base oil exists in the gap with the gap as an oil reservoir.

Since the swing arm of the HDD basically reciprocates, the ball bearings 14 and 16 always reciprocate. For this reason, it can be considered that the ball 32 moves back and forth within the pocket 41 and moves repeatedly to the inner wall of the pocket 41. In the crown-shaped cage 33 shown in FIG. 6, the ball 32 reciprocates and repeatedly collides with the inner wall of the pocket 41, so that the ball 32 strikes the oil reservoir inside the spherical pocket 41, and the base oil is scattered. It is thought that oil particles are generated.
The crown type cage described in Patent Document 1 does not consider the above-described problems.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a crown type cage, a ball bearing, and a bearing unit that can suppress the generation of out particles.

The above object of the present invention can be achieved by the following constitution.
(1) A crown-type cage in which a plurality of pockets each having an opening on one side in the axial direction are formed at predetermined intervals in the circumferential direction,
The pocket has a spherical first pocket surface formed on one side in the bearing radial direction and a center line formed on the other side in the bearing radial direction and extending in the radial direction through the center of the pocket. And a second pocket surface having a cylindrical shape or a conical shape having a tangent to the first pocket surface as a generating line and having a boundary position with the first pocket surface as a contact point with the spherical shape. Mold holder.
(2) The second pocket surface is formed in the cylindrical shape by having the contact point of the tangent line coincide with an intersection point of a pitch circle diameter of the first pocket surface and the tangent line. The crown type cage as described in 1).
(3) The second pocket surface is formed in the conical shape by having the contact point of the tangent line on one side in the bearing radial direction with respect to the intersection point of the pitch circle diameter of the first pocket surface and the tangent line. The crown type retainer according to (1), wherein
(4) An inner ring, an outer ring, a plurality of balls arranged between the inner ring and the outer ring, and the crown type cage according to any one of (1) to (3), which holds the balls, respectively. Having ball bearings.
(5) a housing;
A shaft member;
Two or more bearings which are arranged between the housing and the shaft member and are composed of the ball bearings according to (4);
Have
The two or more bearings are bearing units that are integrally fixed to the housing and the shaft member.

According to the crown type cage of the present invention, the pocket includes a spherical first pocket surface formed on one side in the radial direction with respect to the predetermined radial position and the other side in the radial direction with respect to the predetermined radial direction position. A cylindrical or conical second pocket surface having a central axis extending in the radial direction through the center of the pocket as a central axis and a tangent of the spherical shape at the predetermined radial position as a generating line; Have As a result, the base oil of the grease wets the surface of the pocket, but does not collect inside the pocket, so that generation of oil particles can be suppressed.
Therefore, the same effect can be obtained also in the ball bearing and the bearing unit provided with the crown type cage.

(A) is a fragmentary sectional view which shows the crown type holder | retainer which concerns on 1st Embodiment of this invention, (b) is the I section enlarged view of (a). It is a partial expansion perspective view of the crown type holder of Drawing 1. (A) is a fragmentary sectional view which shows the crown type holder | retainer which concerns on 2nd Embodiment of this invention, (b) is the II section enlarged view of (a). (A) is a modification of the crown type cage of the present invention, and (b) is another modification of the crown type cage of the present invention. (A) is sectional drawing which shows schematically the whole structure of HDD, (b) is a top view which shows the whole structure of HDD, (c) is a half sectional view which shows a pivot bearing unit. (A) is a fragmentary sectional view which shows the conventional crown type holder | retainer, (b) is a partial expansion perspective view.

Hereinafter, a crown type cage according to each embodiment of the present invention will be described in detail with reference to the drawings.
The present invention relates to an improvement of a crown type cage, and other configurations of the ball bearing to which the crown type cage is applied are the same as those of a conventional ball bearing. Accordingly, each schematic configuration of the bearing unit including the pair of ball bearings and the HDD to which the bearing unit is applied is the same as that shown in FIGS. 5A to 5C except for the crown type cage. It is the same.

(First embodiment)
As shown in FIGS. 1 and 2, the resin-made crown-shaped cage 33A according to the first embodiment has an annular main body portion 42, and extends axially from the main body portion 42, and has a predetermined circumferential direction. A plurality of pillar portions 43 provided at intervals, and claw portions 44 are formed on one side in the axial direction of the pillar portion 43 on both sides in the circumferential direction. A plurality of pockets 41 </ b> A each having an opening 40 </ b> A on one side in the axial direction are formed between the plurality of pillars 43 at a predetermined interval in the circumferential direction.
The crown type cage 33A of the present embodiment employs a resin cage made of polyamide resin such as polyamide 66 and reinforcing fibers such as 10 wt% glass fiber.

  In particular, the pocket 41A of the crown-shaped cage 33A has a spherical first pocket surface 45 formed on the outer ring side in the bearing radial direction and a cylindrical second pocket surface 46 formed on the inner ring side in the bearing radial direction. And having. The second pocket surface 46 is a spherical contact at a pocket pitch circle diameter (PCD) position with the center line L extending in the radial direction passing through the center O of the pocket 41 as a center axis and the first pocket surface 45 as a reference. It is formed in a cylindrical shape with the tangent line L1 passing therethrough as a generating line. Hereinafter, the pocket pitch circle diameter (PCD) based on the first pocket surface 45 is abbreviated as “pocket PCD”. Further, the intersection of the pocket PCD and the tangent L1 is PA.

That is, when the boundary position B1 between the first and second pocket surfaces 45 and 46 is the position of the pocket PCD, the intersection PA between the pocket PCD and the spherical tangent L1 coincides with the contact of the tangent L1, and the tangent L1 Extends along the radial direction of the bearing. For this reason, when the second pocket surface 46 is formed with the tangent line L1 as a generating line, the second pocket surface 46 is formed in a cylindrical shape. That is, the angle α at which the tangent L1 constituting the generatrix of the cylindrical second pocket surface 46 intersects the peripheral surface of the cage 33A is 90 degrees.
In the present embodiment, the center O of the pocket 41 coincides with the center of the ball held in the pocket 41, but the center O of the pocket 41 may not be coincident with the center of the ball.

In this way, the pocket 41A of the crown-shaped cage 33A is configured to include the spherical first pocket surface 45 and the cylindrical second pocket surface 46, whereby the base oil of grease is formed on the surface of the pocket 41A. The base oil does not collect inside the pocket 41A. Thereby, even when the ball reciprocates in the pocket 41A, the base oil inside the pocket 41A is sent out to the outside through the second pocket surface 46, so that generation of oil particles can be suppressed. Therefore, the cleanliness of the HDD can be improved by applying the crown-shaped cage 33A and the ball bearings 14 and 16 having the cage 33A to the bearing unit 10.
Further, since the crown-shaped cage 33A has the spherical first pocket surface 45, the cage 33A is guided by the ball guide method in the same manner as the crown-shaped cage 33 having the conventional spherical pocket 41.

  In the HDD swing arm bearing unit 10 shown in FIG. 5, the pair or ball bearings 14 and 16 each having such a crown-shaped cage 33A are integrated by adhesion or press-fitting while applying a preload. Fixed to. This eliminates the need for the preload adjustment required for assembly as in the prior art, so that the ball bearings 14 and 16 can be easily attached and replaced.

(Second Embodiment)
Next, a resin crown-shaped cage 33B according to a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the same part as 1st Embodiment, or an equivalent part, and description is abbreviate | omitted or simplified.

  Also in the crown type cage 33B of the second embodiment, a plurality of pockets having first and second pocket surfaces 45 and 46, each having an opening 40B on one side in the axial direction between the plurality of column portions 43. 41B are formed at predetermined intervals in the circumferential direction.

  Here, in the plurality of pockets 41B of the present embodiment, the boundary position B2 between the first and second pocket surfaces 45 and 46 is the position of the pocket PCD (the pocket pitch circle diameter with reference to the first pocket surface 45) (FIG. 1). Refer to the outer ring side in the bearing radial direction.

Therefore, the contact point PB ′ of the tangent line L2 is formed on the outer ring side in the bearing radial direction with respect to the intersection point PB of the pitch circle diameter PCD and the tangent line L2, and the center line L extending in the radial direction through the center of the pocket 41B is the central axis. The second pocket surface 46 having a spherical tangent L2 at the contact PB ′ as a generating line is formed in a conical shape.
The pocket 41B is preferably formed such that an angle α at which the tangent L2 constituting the generatrix of the conical second pocket surface 46 and the peripheral surface of the cage 33B intersect is 75 degrees or more. If the angle α is smaller than 75 degrees, the width of the first pocket surface 45 in the bearing radial direction is short, so that the ball guide of the cage 33B may be insufficient, and the cage 33B may contact the inner and outer rings. There is.

As described above, even when the pocket 41B of the crown-shaped cage 33B is configured to include the spherical first pocket surface 45 and the conical second pocket surface 46, the base oil of the grease is used for the pocket 41B. While wetting the surface, the base oil does not collect inside the pocket 41B. Thereby, even when the ball reciprocates in the pocket 41B, the base oil inside the pocket 41B is sent to the outside through the second pocket surface 46, and therefore, generation of oil particles can be suppressed. Therefore, the cleanliness of the HDD can be improved by applying the crown-shaped cage 33B and the ball bearings 14 and 16 having the cage 33B to the pivot bearing unit 10.
Moreover, since the crown-shaped cage 33B has the spherical first pocket surface 45, the cage 33B is guided by a ball guide method in the same manner as the crown-shaped cage 33 having the conventional spherical pocket 41.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

For example, in the above embodiment, the spherical first pocket surface 45 is provided on the outer ring side in the bearing radial direction, and the cylindrical or conical second pocket surface 46 is provided on the inner ring side in the bearing axial direction. A pocket having a spherical first pocket surface 45 on the inner ring side in the bearing axial direction and a cylindrical or conical second pocket surface 46 on the outer ring side in the bearing axial direction as in the crown-shaped cages 33C and 33D shown in FIG. It is good also as 41C and 41D.
In these crown type cages 33C and 33D, the same effects as those of the first and second embodiments can be obtained.
That is, in the present invention, a spherical first pocket surface 45 is formed on one side in the bearing radial direction, and a cylindrical or conical second pocket surface 46 is formed on the other side in the bearing radial direction. That's fine.

In addition, the second pocket surface of the present invention has a center line that extends in the radial direction through the center of the pocket as a central axis, and a tangent line of the first pocket surface having a boundary position with the first pocket surface as a contact point with a spherical shape. As described in the above embodiment, the shape is formed in a cylindrical shape or a conical shape according to the boundary position between the first pocket surface and the second pocket surface.
Furthermore, the bearing unit of this invention should just be a structure which has two or more ball bearings.

10 Bearing unit 14, 16 Ball bearing 32 Balls 33A, 33B, 33C, 33D Crown type cages 40A, 40B Openings 41A, 41B, 41C, 41D Pocket 45 First pocket surface 46 Second pocket surface

Claims (5)

A plurality of pockets each having an opening on one side in the axial direction are crown-shaped cages formed at predetermined intervals in the circumferential direction,
The pocket has a spherical first pocket surface formed on one side in the bearing radial direction and a center line formed on the other side in the bearing radial direction and extending in the radial direction through the center of the pocket. And a second pocket surface having a cylindrical shape or a conical shape having a tangent to the first pocket surface as a generating line and having a boundary position with the first pocket surface as a contact point with the spherical shape. Mold holder.   The said 2nd pocket surface is formed in the said cylindrical shape, when the contact of the said tangent corresponds with the intersection of the pitch circle diameter of the said 1st pocket surface, and the said tangent. The crown type cage as described.   The second pocket surface is formed in the conical shape by having a contact point of the tangent line on one side in the bearing radial direction with respect to an intersection of the pitch circle diameter of the first pocket surface and the tangent line. The crown type cage according to claim 1, wherein   The ball bearing which has an inner ring | wheel, an outer ring | wheel, the some ball arrange | positioned between this inner ring | wheel and an outer ring | wheel, and the crown type holder | retainer of any one of Claims 1-3 each hold | maintain this ball | bowl. . A housing;
A shaft member;
Two or more bearings arranged between the housing and the shaft member and comprising the ball bearings according to claim 4;
Have
The two or more bearings are bearing units that are integrally fixed to the housing and the shaft member.

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