JPH10299767A - Rolling bearing unit for swing arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a structure in which preload is not changed with assembly error or temperature change at low cost. SOLUTION: Inner rings 11a, 11b of ball bearings 9a, 9b are fitted around and fixed to both ends of an inner cylinder 7. An outer ring 13a of the ball bearing 9a is fitted in and fixed to one end of an outer cylinder 8a by interference fit. An outer ring 13b of the ball bearing is fitted in and fitted to the other end of the outer cylinder 8a by clearance fit. An elastic member 20 is provided between the outer ring 13b and a stepped part 16b formed on the inner peripheral surface of the intermediate part of the outer cylinder 8a, and preload corresponding to elasticity of the elastic member 20 is applied to respective ball bearings 9a, 9b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A rolling bearing unit for a swing arm according to the present invention includes a hard disk drive (HDD) and a flexible disk drive (F).
It is used to support a swing arm incorporated in a magnetic disk drive device such as DD) so as to be swingable.

[0002]

2. Description of the Related Art An HDD used as a storage device of a computer or the like has a structure as shown in FIG. 4 as described in, for example, Japanese Patent Application Laid-Open No. 7-111053. HD
When D is used, the hard disk 1 is rotated at high speed by a direct drive type electric motor. A base end of a swing arm 3 having a head 2 at a tip end is supported on a substrate 5 by a rolling bearing unit 4 as shown in FIG. 6 is supported so as to be capable of swinging displacement.

The rolling bearing unit 4 has a pair of ball bearings 9 provided between an outer peripheral surface of an inner cylinder 7 as an inner member and an inner peripheral surface of an outer cylinder 8 as an outer member. . Each of these ball bearings 9 has an inner race 11 having a deep groove or angular inner raceway 10 on the outer peripheral surface, an outer race 13 having a deep groove or angular outer raceway 12 on the inner peripheral surface, and the inner race race. It comprises a plurality of balls 14, 14 provided between the outer raceway 12 and the outer raceway 12 so as to freely roll. The plurality of balls 14, 14 are rotatably held by a holder (not shown). The outer peripheral edges of the shield plates 15 and 15 are respectively engaged with the inner peripheral surfaces of both ends of the outer ring 13 to prevent leakage of grease in the space where the plurality of balls 14 and 14 are installed. .

[0004] Of the ball bearings 9 described above, the inner ring 1
Reference numerals 1 and 11 are externally fitted and fixed to both ends of the inner cylinder 7 by interference fit. Further, the outer races 13, 13 are fitted inside the outer cylinder 8, and their end faces facing each other abut against stepped portions 16, 16 formed on the inner peripheral surface of the middle part of the outer cylinder 8. Therefore, the pair of outer rings 13, 13 does not approach each other as compared with the state shown in the figure. Also, the pair of inner rings 11,
Numerals 11 are externally fitted and fixed to both ends of the inner cylinder 7 in a state where they are pressed in directions approaching each other. Therefore, a predetermined preload is applied to the pair of ball bearings 9, 9, and the outer cylinder 8 is rotatably supported around the inner cylinder 7.

The base end of the swing arm 3 (FIG. 4) is moved by the rolling bearing unit 4 as described above to the support shaft 6.
In order to swingably support the inner cylinder 7, the inner cylinder 7 is disposed around the support shaft 6, and the inner cylinder 7 is provided with a step 17 provided at a base end of the support shaft 6. The support shaft 6 is sandwiched between a holding plate 19 fixedly connected to a tip end surface of the support shaft 6 with a screw 18. The base end of the swing arm 3 is connected to the outer cylinder 8. In this assembled state, the head 2 (FIG. 4) supported on the tip of the swing arm 3 comes close to the surface of the hard disk 1 (FIG. 4) with the swing of the swing arm 3. In the state,
The signal is read and written while moving so as to follow the surface.

[0006]

In recent years, the density of storage devices such as HDDs has been increased, and the width of tracks for recording signals on the hard disk 1 or flexible disk has been increasingly narrowed. Also, the speed of reading and writing of magnetic recording has been improved. In addition, it is necessary to trace the extremely narrow track with the head 2 more faithfully and at a high speed. Therefore, it is required to improve the positioning accuracy and the swing speed accompanying the swing displacement of the swing arm 3. Have been. In order to meet such a demand, the rolling bearing unit 4 is required to have a small torque required for rotation and not to cause a torque fluctuation such as a torque spike (rapid torque fluctuation).

In the case of a conventional rolling bearing unit 4 as shown in FIG. 5, the inner ring 1 constituting a pair of ball bearings 9, 9 is provided.
Each of the outer rings 1 and 11 and the outer races 13 and 13 is tightly fitted or fixed to the outer peripheral surface of the inner cylinder 7 or the inner peripheral surface of the outer cylinder 8 by adhesion or bonding. Then, each of the inner rings 1 with respect to the inner cylinder 7
The preload applied to the ball bearings 9 is adjusted by adjusting the fixed positions of the ball bearings 1 and 11. Because of this,
Since the preload is easily affected by the assembly error and the torque required for the swing arm 3 to swing easily fluctuates, it may be difficult for the recording apparatus to exhibit stable performance. Also, the inner rings 11, 11 and the outer rings 13, 1
When the axial dimension of the inner cylinder 7 or the outer cylinder 8 changes due to a temperature change due to a so-called fixed-position preload that applies a preload to each of the ball bearings 9 and 9 while keeping the positional relationship with the ball bearing 3 constant, The preload applied to each ball bearing 9 changes. The change in the preload generated in this manner is not preferable because it causes a torque change required to swing the swing arm 3. For this reason, the assembling work of assembling the rolling bearing unit 4 while applying a predetermined preload is troublesome, and it is difficult to exhibit stable performance at a rate that the cost of the rolling bearing unit 4 increases. The rolling bearing unit for a swing arm according to the present invention is designed to realize a structure that facilitates an assembling operation for assembling the rolling bearing unit while applying a predetermined preload, and that can perform a stable preload.

[0008]

The rolling bearing unit for a swing arm according to the present invention comprises an inner member having a cylindrical outer peripheral surface and a cylindrical inner peripheral member, like the above-mentioned conventional rolling arm unit for a swing arm. An outer member having a surface;
A first inner raceway provided in a diametrically outer portion of one axial end of the inner member; a first outer raceway provided in a diametrically inner portion of one axial end of the outer member; A first ball bearing configured by rolling a plurality of balls between the outer raceway and the first inner raceway, and a diametrically outer portion at the other axial end of the inner member; A second inner raceway, a second outer raceway provided in a diametrically inner portion of the other end of the outer member in the axial direction, and a plurality of raceways between the second outer raceway and the second inner raceway. And a second ball bearing configured by rolling the balls freely.

In particular, in the rolling arm unit for a swing arm according to the present invention, the second outer raceway is formed on the inner peripheral surface of an outer race fitted inside the outer member by a clearance fit. Also, between the outer ring and the outer member,
An elastic member for pressing the outer ring in the axial direction is provided. A preload is applied to the first and second ball bearings by this elastic member.

[0010]

In the case of the swing arm rolling bearing unit of the present invention configured as described above, the magnitude of the preload applied to the first and second ball bearings is determined by the first and second inner raceways during assembly. And it is determined by the elasticity of the elastic member regardless of the positions of the first and second outer raceways. Further, even when the dimensions of the constituent members change with a change in temperature, the elastic member expands and contracts, thereby applying a preload corresponding to the elasticity of the elastic member to the first and second ball bearings. to continue. Therefore, it is possible to stably apply the preload and stabilize the torque required for the swing displacement of the swing arm, despite the fact that it can be manufactured inexpensively, without requiring any troublesome assembly work.

[0011]

FIG. 1 shows a first embodiment of the present invention. The rolling bearing unit 4a has an outer peripheral surface of an inner cylinder 7 as an inner member and an outer cylinder 8 as an outer member.
A pair of ball bearings 9a and 9b are provided between the inner bearing and the inner peripheral surface. Each of these ball bearings 9a, 9b has a deep groove or angular inner ring raceway 10a, 10b on its outer peripheral surface.
The inner races 11a, 11b having the outer races 13a, 13b having the deep groove or angular outer raceways 12a, 12b on the inner peripheral surface thereof, and the inner races 10a, 10b and the outer races 12a, 12b rolling between the inner races 10a, 10b. It comprises a plurality of balls 14 movably provided. These plural balls 14,
14 is rotatably held by a holder (not shown). Further, the outer peripheral edges of the shield plates 15, 15 are respectively engaged with the inner peripheral surfaces of both ends of the outer rings 13a, 13b to prevent leakage of grease in the space where the plurality of balls 14, 14 are installed. I'm trying. For the above configuration,
This is the same as the conventional rolling bearing unit 4 shown in FIG.

In the case of the rolling bearing unit 4a of the present invention, of the pair of ball bearings 9a and 9b, the inner race 11a constituting the first ball bearing 9a is connected to one end of the inner cylinder 7 (FIG. 1).
Similarly, the outer ring 13a is fitted and fixed to one end of the outer cylinder 8a by tight fitting or bonding. That is, in the case of this example, the inner race 11a and the outer race 13
is fixed to the one end of the inner cylinder 7 or the outer cylinder 8a by external fitting or internal fitting by tight fit or adhesion, so that the first end of the inner cylinder 7 in the axial direction at the one end in the axial direction is first fitted. The inner raceway 10a is fixedly provided with a first outer raceway 12a at a radially inner portion of one end of the outer cylinder 8a in the axial direction. The end face of the outer ring 13a constituting the first ball bearing 9a is formed by a stepped portion 1 formed on an inner peripheral surface of an intermediate portion of the outer cylinder 8a.
6a. The outer ring 13a is provided with a step 16
a of the outer ring 13a in the axial direction (FIG. 1).
Is not displaced in the vertical direction. Therefore, this outer ring 1
3a may be internally fitted to one end of the outer cylinder 8a with a slight clearance fit. If the inner peripheral surface of the outer race 13a and the inner peripheral surface of the outer cylinder 8a need not be bonded to each other when the inner peripheral surface is fitted by the clearance fit, the assembling operation is facilitated.

On the other hand, of the inner ring 11b and the outer ring 13b constituting the second ball bearing 9b, the inner ring 11b is tightly fitted or bonded to the other end (upper end in FIG. 1) of the inner cylinder 7. While the outer ring 13b is fixed to the outside, the outer ring 13b is slightly fitted into the other end of the outer cylinder 8a (with a diameter of 1 to 10).
(about μm). That is, in the case of the present example, the inner ring 11b is fixed to the other end of the inner cylinder 7 by external fitting by tight fit or bonding, so that the other end in the axial direction of the inner cylinder 7 is diametrically outer. A second inner raceway 10b is provided in the portion. The outer race 13b is fitted inside the other end of the outer cylinder 8 in the axial direction by a clearance fit, so that the second outer raceway 12
b is provided. An elastic member 20, such as a metal spring, rubber, or elastomer, is sandwiched between the outer ring 13b and a step 16b formed on the inner peripheral surface of the intermediate portion of the outer cylinder 8a. Is elastically pressed in a direction away from the outer ring 13a forming the first ball bearing 9a. Therefore, the first and second ball bearings 9a and 9b are given a preload by the elastic member 20 in accordance with the elasticity of the elastic member 20. In this state, the outer cylinder 8a is rotatably supported around the inner cylinder 7 without rattling. Note that, in order to attenuate vibration such as ball passing vibration generated in the second ball bearing 9b and not transmit this vibration to the swing arm,
A lubricant such as grease is present in the annular space between the outer peripheral surface of the outer ring 13a and the inner peripheral surface of the outer cylinder 8a.

[0014] The rolling bearing unit 4 of the present invention as described above.
In order to swingably support the base end of the swing arm 3 (FIG. 4) with respect to the support shaft 6 implanted on the substrate 5, the inner cylinder 7 is arranged around the support shaft 6. At the same time, the inner cylinder 7 is sandwiched between a step 17 provided at the base end of the support shaft 6 and a holding plate 19 fixed to the distal end surface of the support shaft 6 by screws 18. In addition, the base end of the swing arm 3 is connected to the outer cylinder 8a. In this assembled state, the head 2 (FIG. 4) supported on the tip of the swing arm 3 comes close to the surface of the hard disk 1 (FIG. 4) with the swing of the swing arm 3. In this state, signals are read and written while moving to follow the surface.

In particular, in the case of the rolling bearing unit for a swing arm according to the present invention, the first and second ball bearings 9a and 9b are provided.
The magnitude of the preload applied to the
Regardless of the positions of the second inner raceways 10a, 10b and the first and second outer raceways 12a, 12b, the elastic member 2
It is determined by the elasticity of 0. Further, even when the dimensions of the constituent members change due to a change in temperature, the elastic member 20 expands and contracts, so that the preload corresponding to the elasticity of the elastic member 20 is reduced by the first and second ball bearings 9a. , 9b. Therefore, the mounting position of each inner ring 11a, 11b with respect to the inner cylinder 7, or each outer ring 13a, 13 with respect to the outer cylinder 8a.
It is possible to keep applying a stable preload despite the fact that it can be manufactured inexpensively without the need for a troublesome assembling operation such as strictly restricting the assembling position of b. Because of this,
The torque required for the swing displacement of the swing arm 3 supported by the rolling bearing unit 4a can be stabilized.

FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the case of this example, the first inner raceway 10a is formed directly on the outer peripheral surface of one end (the lower end in FIG. 2) of the inner cylinder 7a. For this reason, in the case of this example, the inner ring constituting the first ball bearing 9a 'is omitted. Further, the second outer ring 13b constituting the second ball bearing 9b is not only internally fitted to the other end (the upper end in FIG. 2) of the outer cylinder 8b by a clearance fit, but also
The second inner race 11b constituting the second ball bearing 9b is fitted to the other end of the inner cylinder 7a by a clearance fit. In accordance with this, the other end of the outer cylinder 8b protrudes from the end face of the second ball bearing 9b, and the stop ring 21 is engaged with the inner peripheral surface of the protruding portion. This stop ring 21 causes the second ball bearing 9b to fall off between the outer peripheral surface of the inner cylinder 7a and the inner peripheral surface of the outer cylinder 8b even before the rolling bearing unit 4b is mounted around the support shaft 6. Has the role of preventing Other configurations and operations are the same as those of the above-described first example.

FIG. 3 shows a third embodiment of the present invention.
An example is shown. In the case of this example, the inner cylinder is omitted, and the first and second inner rings 11a and 11b constituting the first and second ball bearings 9a and 9b are arranged around the support shaft 6 implanted on the substrate 5. Are fitted outside by a clearance fit. Therefore, in the case of this example, the support shaft 6 corresponds to the inner member described in the claims. In the case of such a structure of the present example, the inner cylinder is omitted, not only the cost can be reduced based on the reduction in the number of parts and the number of assembly steps, but also the first and second ball bearings 9 can be used.
The diameters of the pitch circles a and 9b can be reduced. The rolling bearing unit 4 including these first and second ball bearings 9a and 9b is reduced by the pitch circle.
c can be reduced. Other configurations and operations are the same as those in the first example or the second example described above.

[0018]

The rolling bearing unit for a swing arm according to the present invention is constructed and operates as described above, so that preload fluctuations due to assembly errors and temperature changes can be suppressed to a minimum.
The performance of a magnetic recording device incorporating a swing arm, such as an HDD, can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view schematically showing a first example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing the second example.

FIG. 3 is an enlarged sectional view showing the third example.

FIG. 4 shows an example of an HDD incorporating a swing arm supported by a rolling bearing unit to which the present invention is applied;
FIG. 2 is a perspective view showing a state where a cover is removed.

FIG. 5 is an enlarged sectional view schematically showing a conventional rolling bearing unit for a swing arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hard disk 2 Head 3 Swing arm 4, 4a, 4b, 4c Rolling bearing unit 5 Substrate 6 Support shaft 7, 7a Inner cylinder 8, 8a, 8b Outer cylinder 9, 9a, 9b, 9a 'Ball bearing 10, 10a, 10b, 10a 'Inner ring track 11, 11a, 11b Inner ring 12, 12a, 12b Outer ring track 13, 13a, 13b Outer ring 14 Ball 15 Shield plate 16, 16a, 16b Step 17 Step 18 Screw 19 Press plate 20 Elastic member 21 Stop ring

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shoji Noguchi 1-50-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa Nippon Seiko Co., Ltd.

Claims (1)

[Claims] 1. An inner member having a cylindrical outer peripheral surface, an outer member having a cylindrical inner peripheral surface, and a first inner raceway provided at a diametrically outer portion at one axial end of the inner member. A first outer raceway provided on a diametrically inner portion of one end in the axial direction of the outer member, and a plurality of balls rolling freely between the first outer raceway and the first inner raceway. A first ball bearing configured by providing, a second inner raceway provided in a diametrically outer portion of the other axial end of the inner member,
A second outer raceway provided in a diametrically inner portion of the other end in the axial direction of the outer member, and a plurality of balls rollable between the second outer raceway and the second inner raceway. In the rolling arm unit for a swing arm provided with the second ball bearing configured by providing the second outer ring raceway, the second outer raceway is formed on the inner peripheral surface of the outer race fitted inside the outer member by a clearance fit. An elastic member that presses the outer ring in the axial direction is provided between the outer ring and the outer member,
A rolling bearing unit for a swing arm, wherein a preload is applied to the first and second ball bearings by the elastic member.