JPH06129425A - Pre-load structure of bearing and magnetic disk device using it - Google Patents

Abstract

PURPOSE:To prevent the backlash of plural bearings by a simple pre-load means and realize high precision rotation and at the same time realize the reduction of work such as assembly and breaking-up. CONSTITUTION:In the case of bearing pre-load structure made up by being equipped with plural bearings 11 put between a rotary portion 7 and a fixed portion 10 and a pre-load means 15 to push-press respective bearings 11 radially against the rotary center axis of the bearings 11, the pre-load means 15 is composed of plural pushing portions to push plural bearings 11 respectively and an elastic means bent so as to retain and energize plural pushing portions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preload structure for a plurality of bearings provided between a rotating portion and a fixed portion. The present invention also relates to a magnetic head positioning mechanism, and more particularly to a magnetic disk drive characterized by a bearing preload structure in an actuator. In recent years, with the downsizing, weight reduction, speedup, and increase in storage capacity of magnetic disk devices, it has been desired to reduce the number of parts and improve the positioning accuracy of the magnetic head.

[0002]

2. Description of the Related Art Generally, a rotationally driven mechanism is provided to a shaft via a bearing like an actuator. Such bearings are manufactured with a slight gap in the inner ring or the outer ring in consideration of fitting of balls and deformation due to temperature change. As a result, a gap remains after assembly, which inevitably causes play in the bearing.

Further, since the arm is made of light metal such as aluminum and the bearing and the shaft are made of rigid stainless steel, there is rattling due to a difference in coefficient of thermal expansion caused by a difference in material and vibration due to high speed rotation. It can happen. In recent years, with the increase in storage capacity, the track-to-track density has fallen to about 10 microns or less, and even a slight displacement of the magnetic head caused by backlash cannot be ignored. Therefore, it is desirable to prevent backlash of the bearing and perform more accurate positioning of the magnetic head.

The prior art will be described below with reference to the drawings. Figure 1
1 is a schematic sectional view of a conventional magnetic disk device, FIG.
FIG. 12 is a schematic view of a main part of the bearing preload structure used in FIG. 11. An outline of a conventional magnetic disk device will be described with reference to FIG. Reference numeral 51 is a housing for enclosing the magnetic disk, 53 is a spindle which is rotationally driven by a drive motor, and 54 is a magnetic disk stacked on the spindle 53.

The actuator 57 includes an arm portion 52,
It is composed of a magnetic head 58 and the like for recording / reproducing data of the magnetic disk 54 attached to the tip thereof. The magnetic head 58 is driven by a voice coil motor 90 provided in the housing 51. 61 is a bearing, 70
Is a groove into which the radial preload spring 75 is inserted. Below,
FIG. 11 shows the bearing preload structure of this magnetic disk device.
Will be explained. Reference numerals 61a and 61b are bearings composed of an inner ring, an outer ring, and a sphere fitted between them. The outer rings of the bearings 61a and 61b are fixed to the actuator 7 side by adhesive bonding or press fitting.

The radial preload springs 75a and 75b are composed of a spring for pushing the bottom surface and a spherical pressing portion, and are inserted into the through holes 70, 70 extending toward the middle and deep portions of the shaft 60 to prevent looseness in the radial direction. Bearing 6 for
The inner rings 1a and 61b are pressed in the radial direction. The thrust preload spring 80 is a disc spring provided on the upper portion of the shaft 60, and presses the inner ring of the bearing 61 in the thrust direction in order to prevent looseness in the thrust direction.

Such a preload means causes a backlash caused by a gap in manufacturing the bearing, a difference in thermal expansion coefficient caused by a difference in materials of the arm portion 52, the bearing 61 and the shaft 60, and a backlash caused by vibration due to high speed rotation. To prevent this, the off-track amount of the magnetic head 58 is reduced.

[0008]

However, in the above-mentioned preload structure, the spring is inserted in the non-penetrating hole, and then the spherical pressing portion is inserted to assemble, so that a difficult work is required, and at the time of failure repair, Work problems such as not being easily disassembled are mentioned. Therefore, in order to easily assemble the radial preload portion, a method has been proposed in which the shaft and the rotating body are assembled and then inserted without using such a preload component.

An application filed by the present applicant regarding a bearing preloading structure characterized in that it is provided with a preloading means having a center portion of the leaf spring curved and a pressing portion for pressing one of the upper and lower bearings in the radial direction. Japanese Patent Application No. 03-0497
No. 29). However, this proposal did not particularly consider the case of preloading a plurality of bearings. Therefore, when preloading the bearings provided on the upper and lower sides of the shaft, a groove is provided for each bearing and the above-mentioned preloading means is inserted separately, which raises the problem that the number of assembly steps and the number of parts increase. .

The present invention provides a bearing preload structure which prevents rattling of a plurality of bearings by a simple preload means, enables highly accurate rotation, and reduces the work such as assembly and disassembly. The purpose is to Another object of the present invention is to provide a magnetic disk device which can perform highly accurate positioning by a simple means and enables accurate recording / reproducing.

[0011]

FIG. 1 is a principle view of a bearing preloading structure according to the present invention. (A) shows the case where the radial preload means is provided on the fixed portion side, and (b) shows the case where the radial preload means is provided on the rotating portion side. Further, FIG. 1 can be used as a principle diagram of a bearing preload structure used in the actuator of the magnetic disk device of the present invention. Therefore, for the sake of clarity, the drawing numbers of the bearing preload structure of the present invention and the drawing numbers of the magnetic disk device of the present invention are given in duplicate. However, the rotating part is not always the actuator.

According to claim 1 of the present invention, the rotating portion 7 and the fixed portion 1 are provided.
In the bearing preload structure, which comprises a plurality of bearings 11 fitted between 0 and 0, and a preload means 15 for pressing the bearings in a radial direction with respect to the rotation center axis of the bearing 11, the preload means 15 Is a plurality of pressing portions that press the plurality of bearings 11, and
It is characterized in that it is constituted by elastic means that holds the plurality of pressing portions and is bent so as to urge them.

According to a second aspect of the present invention, a spindle, a magnetic disk mounted on the spindle, a magnetic head for recording and reproducing information on the magnetic disk, and a rotating unit for holding and rotating the magnetic head. 7, a plurality of bearings 1 fitted between the rotating portion 7 and the fixed portion 10.
1, a plurality of pressing portions that respectively press the plurality of bearings 11 in the radial direction with respect to the rotation center axis of the bearings 11, and an elasticity that is bent to hold and press the plurality of pressing portions. And a preloading means constituted by means.

[0014]

According to the first aspect of the present invention, it is possible to prevent the play in the radial direction by uniformly pressing the plurality of bearings 11 in the radial direction only by the preloading means 15. According to claim 2 of the present invention, the plurality of bearings 1 are provided only by the preload means 15.
It is possible to evenly press 1 in the radial direction to prevent play in the radial direction and to prevent off-track of the magnetic head.

[0015]

FIG. 2 is a schematic sectional view of an embodiment of the magnetic disk device of the present invention, and FIG. 3 is a plan configuration diagram of FIG. The housing 1 is composed of a base 1a and a cover 1b. The spindle 3 is rotatably attached to the base 1a and is driven by a built-in spindle motor. The magnetic disk 4 includes a spindle 3 and an annular spacer 5
Are alternately inserted, and the disc clamp 6 tightens the screw 9 to fix the layers.

A cylindrical shaft 10 is rotatably provided on a base 1a together with an actuator 7 mounted via a pair of upper and lower bearings 11, and a cover 1b and a nut 16 are tightened. When the device is started, the number of rotations of each magnetic disk 4 is 4400rp as the spindle 3 rotates.
The magnetic head 8 which rotates at m and stops contacting the magnetic disk 4 floats.

Reference numeral 20 denotes a voice coil motor, and when a control circuit (not shown) supplies a current to the coil 21, a force is generated by the action of the magnet 22 and the coil 21 to rotate the actuator 7. Then, the magnetic head 8 attached to the tip of the arm 2 moves in the radial direction of the magnetic disk 4 to write and read digital information on the magnetic disk 4.

The radial direction described here means a radial direction with respect to the center axis of rotation of the bearing, and the thrust direction is
It means the axial direction with respect to the center axis of rotation of the bearing. FIG. 3 shows the position where the radial preload means for pressing the bearing in the radial direction is provided. The radial preload means presses the bearing so that the magnetic head 8 always comes to the center of the cylinder of the magnetic disk.
It is desirable to provide it on a straight line connecting the shaft center of the shaft 10.

Therefore, here, the groove 30 is provided on the voice coil motor 20 side on the straight line connecting the magnetic head 8 and the shaft center of the shaft 10, and the radial preload means is installed therein. Although the radial preload means may be provided on the magnetic head 8 side, it may be provided at another position in consideration of vibration and the like due to high speed rotation. Further, although the radial preloading means is provided only at one place, it may be possible to provide at a plurality of places. In that case, it is necessary to consider the pressing force and the preload direction.

The bearing preload structure used in the actuator of the magnetic disk drive shown in FIG. 2 is shown in FIG.
The details will be described below. FIG. 4 is a schematic view of a main part of a first embodiment of the bearing preloading structure of the present invention, FIG. 6 is a schematic view of a main part of a second embodiment of the bearing preloading structure of the present invention, and FIG.
It is a schematic diagram of the 3rd Example main part of the bearing preload structure of this invention.

FIGS. 4, 6 and 7 show the case where a groove is provided in the fixed portion of the bearing preload structure of the present invention, which will be described by using the actuator of the magnetic disk device of FIG. 2 as an example of the rotating portion. Reference numeral 13 denotes an inner ring of the bearing 11, which is fitted with play on the shaft 10 side in order to apply a preload. Reference numeral 14 denotes an outer ring of the bearing 11, which is adhesively fixed or press-fitted and fixed to the actuator 7 side in order to receive a preload applied to the inner ring 11 side.

The shaft 10 is provided with a groove 30 that is cut out continuously in the thrust direction from the inner ring 13a facing portion to the inner ring 13b facing portion, and the radial preload spring 35 is installed in the groove 30. The radial preload spring 35 has pushing portions 35a and 35b that come into contact with the inner rings 13a and 13b, respectively, and a holding portion that holds the pushing portions 35a and 35b. Part of the holding portion (abutting portion) is a groove. The holding part is curved so as to abut the wall.

The radial preload here is about 2-3 kg weight for one bearing. Radial preload spring 3
Details of 5 will be described later with reference to FIG. It is provided on the upper part of the shaft 10 in order to prevent looseness in the thrust direction, and directly presses the upper part of the inner ring 13a of the bearing 11a and indirectly presses the inner ring 13b of the lower bearing 11b.
The thrust preload here is about 2-3 kg weight.

The thrust preload means may be provided between the bearings on the upper and lower sides of the shaft or provided on the lower side to directly or indirectly press the bearings, and in addition to the disc spring, an elastic member such as a coil spring. May be used, and it may be configured as a part of the shaft without being provided. 41 and 42 are disc-shaped pressers of the spring 40,
A circumferential projection band is provided so as to push only the inner ring 13.

The method of assembling the radial preload section will be briefly described below. As shown in FIG. 3, the shaft 10 is cut out in the thrust direction on the straight line connecting the magnetic head 8 and the shaft 10 to form the groove 30. Then, after the bearings 11 a and 11 b are attached and the shaft 10 and the actuator 7 are assembled, the radial preload spring 35 is inserted into the groove 30.

Thereafter, the thrust preload spring 40 is attached via the spring retainers 41 and 42, and the shaft 10 and the cover 1b are tightened with the nut 16. Therefore, the bearing preloading structure of the present invention facilitates the assembly and disassembly of the device and improves workability. FIG. 5 is an enlarged perspective view of the radial preload spring 35 used in FIG.

The radial preload spring 35 is obtained by stamping a plate of which surface is made of stainless steel for springs so that the pressing portions 35a and 35b are spherical, and the inner rings 13a and 13b.
Is manufactured so as to abut against the wall 30h of the groove 30 on the opposite side of. Therefore, the radial preload spring 3
Since 5 has a simple component structure, it can be easily manufactured and the number of components of the device can be reduced.

Since the holding portion for holding the pressing portions 35a and 35b is formed by bending the spring material as described above, a biasing force is generated by contacting the wall 30h of the groove 30, and the force is utilized. Then, the bearings 11a and 11b are pressed. Therefore, the radial preload spring 35 can always apply uniform preload in a fixed direction even if the device is tilted due to temperature change, vibration, etc., to prevent backlash of the bearings 11a and 11b, and to prevent off-track.

The radial preload spring 45 shown in FIG.
In the modified example of the radial preload spring 35 shown in FIG. 4, the pressing portions 45a and 45b are spherical, and the pressing portion 45 is
The holding portions of a and 45b are the same in that they are curved, but they differ in that the contact portion 45c that contacts the wall 30h of the groove 30 is formed in a spherical shape. The radial preload spring 45 is installed in the thrust-direction groove 30 provided in the shaft 10 as in FIGS. 3 and 4.

With the radial preload spring 45 arranged in this way, an urging force can be generated as in FIG. 4, and the force is transmitted to the bearings 11a and 11b via the pressing portions 45a and 45b. . Therefore, the radial preload spring 45 has the bearing 11a and the bearing 11a.
Each b can be pressed, and play in the radial direction can be prevented. The radial preload is about 2-3 kg weight for one bearing.

In this radial preload spring 45, since the pressing portions 45a, 45b and the contact portion 45c are spherical,
Even if it touches any part of the surface, it can be pushed with a uniform force, and even if the shaft or the like is slightly inclined due to the temperature change of the device, the preload can be applied more reliably. Therefore, the bearing preload structure of FIG. 5 can control the position of the magnetic head 8 so that the magnetic head 8 is always at the center of the cylinder more reliably than that shown in FIG. 4, and off-track can be prevented. .

In FIG. 7, as in FIGS. 3 and 4, the groove 30 is provided, and the radial preload spring 55 is installed therein. This radial preload spring 55 is a modified example of the radial preload spring 35 shown in FIG. 4, and has inner rings 13a and 13b.
Spherical pressing portions 55a and 55b that respectively abut
Is the same in that it has a curved holding portion for holding the pressing portions 55a and 55b, but the holding portion is extended and bent so that the leaf spring 55 can be pulled out after newly installing the leaf spring 55 near the insertion opening. Is provided.

Therefore, since the radial preload spring 55 can be easily taken out from the groove 30, it is possible to perform the repair of the device without forcibly disassembling the bearing preload portion, thereby improving the work efficiency. You can It is also possible to extend the holding portion of the radial preload means near the insertion port to form a handle so that it can be pulled out after installation and screw it to the shaft. Further, the radial preload spring 45 having the shape shown in FIG. 6 can be provided with the hooking portion or the handle as described above.

FIG. 8 is a schematic sectional view of another embodiment of the magnetic disk device of the present invention, FIG. 9 is a plan view of FIG. 8, and FIG.
FIG. 9 is a schematic view of a main part of the bearing preload structure used in FIG. 8. The bearing preload structure of the magnetic disk drive shown in FIG.
2 shows a case where a groove is provided in the rotating portion, in which a preload in the thrust direction is applied by a coil spring provided in the intermediate portion of the actuator, and a groove in the thrust direction is provided on the actuator side. Is slightly different.

The structure of the magnetic disk drive shown in FIG. 8 and FIG.
The same parts in the configuration of the magnetic disk device are denoted by the same reference numerals, and the description thereof will be omitted. FIG. 10 shows an actuator 7 as an example of the rotating portion of the bearing preloading structure of the present invention.
Is applied to the magnetic disk device of FIG. The inner ring 13 of the bearing 11 is adhesively fixed or press-fitted to the shaft 10 in order to receive a preload applied to the outer ring 14 side. The outer ring 14 of the bearing 11 is fitted to the actuator 7 side with play to apply a preload.

The inner ring 13 is fitted to the shaft 10 by using a material different from that of the shaft 10, but may be formed as a part of the shaft. Radial preload spring 35
Is installed in a groove 50 formed by cutting out the actuator 7 in the thrust direction in order to prevent looseness in the radial direction. This radial preload spring 35 is shown in FIG.
It is the same as that described in FIG. The pressing portions 35a and 35b that come into contact with the outer rings 14a and 14b, respectively, have a spherical shape, and a part of the holding portion (abutting portion) that holds the pressing portions 35a and 35b is located on the opposite side of the outer rings 14a and 14b. The whole is curved so as to abut against the wall 50h.

With this arrangement, the radial preload spring 35 generates an urging force, and the urging force is applied to the bearings 11a and 1a via the pressing portions 35a and 35b.
Tell 1b. Therefore, the radial preload spring 35 can press the bearings 11a and 11b, respectively, and can prevent looseness in the radial direction. The radial preload is approximately 2-3 kgf of preload on one bearing, as in FIG. Further, the radial preload springs 45 and 55 shown in FIGS. 6 and 7 and those to which they are applied may be used.

The thrust preload spring 40A is composed of a coil spring and is provided in the intermediate portion of the actuator 7 to prevent backlash in the thrust direction.
Preload 4. The thrust preload here is about 2-3 kg
It is heavy. Reference numeral 43 is a disc-shaped spring retainer, and 44 is a spring retainer integrally formed with the actuator 7, and is provided with irregularities so as to apply a preload only to the outer ring.

The thrust preload means may be provided on the upper side or the lower side of the actuator to directly or indirectly press each bearing, and an elastic member such as a disc spring may be used. Further, the thrust preload means may be provided by a method other than the above. The method of assembling the radial preload section will be briefly described below.

As shown in FIG. 9, a groove 50 is provided by notching the actuator 7 on the straight line connecting the magnetic head 8 and the shaft 10 and in the thrust direction. The bearing 11b is attached, the thrust preload spring 40A is installed on the spring retainer 44, the spring retainer 43 and the bearing 11a are attached, the shaft 10 and the actuator 7 are assembled, and then the radial preload spring 35 is inserted into the groove 50.

Therefore, the apparatus can be easily assembled and the workability can be improved. Although only one radial preload spring 35 is provided, multiple radial preload springs 35 may be provided. In that case, it is necessary to consider the pressing force of the radial preload means and the preload direction.

Therefore, the bearing preloading structure of the present invention is
Since the radial preloading means can have a simple part structure and the number of parts can be reduced, the device can be made lighter in weight and can be rotated at a higher speed. When rotating at high speed, it is better to use a bearing preload structure in which the groove for installing the radial preload means is in the fixed part, but it is also possible that the shaft can not be cut out, so use the bearing preload structure in which the groove is in the rotating part. It may be better to stay. In that case, the structure in which the groove is provided in the rotating portion is effective in reducing the number of parts.

The radial preload means of each of the embodiments shown in FIGS. 4, 6, 7, and 10 has been described above in which the pressing portion and the abutting portion are formed into spherical shapes. By using an elastic member such as a spring, for example, as shown in FIG. 1, it is simply curved so that both end portions are pressed portions, or the central portion is simply bent at an angle to abut the wall of the groove. The part may be used as the pressing part.

The pressing portion and the contact portion are cylindrical, spherical,
It may be processed into a hemispherical shape, simply curved so that it can be pressed, or bent into a streamline or zigzag shape. Further, the pressing portion and the contact portion may be covered with resin or the like, or may be processed and coupled separately from the elastic member in order to absorb vibrations and impacts accompanying high-speed rotation.

In each of the embodiments shown in FIGS. 2 to 10, the radial preloading method is provided with the groove to press the bearing, but the fixed portion and the rotating portion are not limited to the shapes shown in the respective drawings. It does not have to be a groove because it does not. For example, a radial preload means may be installed with a gap provided between the fixed portion and the inner ring. Similarly, for example, a radial preload means may be installed with a gap provided between the rotating portion and the outer ring.

Therefore, the bearing preloading structure of the present invention is
In order to install the radial preload means, considering that the radial preload means is an elastic means having a plurality of pressing parts and its action, each pressing part can face each bearing,
Moreover, it is sufficient that the space connecting them and the holding portion is continuous. INDUSTRIAL APPLICABILITY The bearing preloading structure of the present invention can be used in the case where the shaft rotates, and other than the actuator of the magnetic disk device, and also applicable to other rotating bodies such as a spindle.

[0047]

The bearing preloading structure of the present invention is provided with elastic means for evenly preloading a plurality of bearings to reliably prevent backlash and enable highly accurate rotation. Also,
Since the bearing preload structure of the present invention is provided with the groove in the thrust direction, the device can be easily assembled and disassembled, and the work efficiency can be improved.

Further, the bearing preloading structure of the present invention is
The number of parts can be reduced, and the weight of the device can be reduced. The magnetic disk device of the present invention prevents off-tracking of the magnetic head to perform highly accurate positioning,
It becomes possible to perform more accurate recording and reproduction. Further, in the magnetic disk device of the present invention, since the bearing preload portion of the actuator is simply configured, it is possible to improve the efficiency of work such as assembly and disassembly.

Further, in the magnetic disk device of the present invention,
The number of parts can be reduced, and the weight of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a principle diagram of a bearing preload structure of the present invention.
(A) shows the case where the radial preload means is provided on the fixed part side, and (b) shows the case where the radial preload means is provided on the rotary part side.

FIG. 2 is a schematic sectional view of an embodiment of a magnetic disk device of the present invention.

FIG. 3 is a plan configuration diagram of the magnetic disk device of FIG. 2;

FIG. 4 is a schematic view of a main part of a first embodiment of the bearing preloading structure of the present invention.

5 is an enlarged perspective view of the radial preload spring used in FIG.

FIG. 6 is a schematic view of a main part of a second embodiment of the bearing preloading structure of the present invention.

FIG. 7 is a schematic view of a main part of a third embodiment of the bearing preloading structure of the present invention.

FIG. 8 is a schematic cross-sectional view of another embodiment of the magnetic disk device of the present invention.

9 is a plan configuration diagram of the magnetic disk device shown in FIG. 8. FIG.

10 is a schematic view of a main part of the bearing preload structure used in FIG.

FIG. 11 is a schematic cross-sectional view of a conventional magnetic disk device.

FIG. 12 is a schematic view of a main part of the bearing preload structure used in FIG.

[Explanation of symbols]

 1 Housing 3 Spindle 4 Magnetic Disk 8 Magnetic Head 7 Actuator 10 Shaft 11 Bearing 13 Inner Ring 14 Outer Ring 30,50 Groove 35,45,55 Radial Preload Spring 40,40A Thrust Preload Spring 41,42 Spring Presser 43,44 Spring Presser

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[Submission date] December 24, 1993

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Claims (2)

[Claims] 1. A plurality of bearings (11) fitted between a rotating portion (7) and a fixed portion (10) and pressing the bearings in a radial direction with respect to a rotation center axis of the bearings (11). Preloading means (15) for preloading the bearing, wherein the preloading means (15) comprises the plurality of bearings (11).
A preloading structure for a bearing, comprising: a plurality of pressing portions that press each other, and elastic means that is bent to hold and press the plurality of pressing portions. 2. A spindle, a magnetic disk mounted on the spindle, a magnetic head for recording and reproducing information on the magnetic disk, a rotating unit (7) for holding and rotating the magnetic head, A plurality of bearings (11) fitted between the rotating part (7) and the fixed part (10), and the plurality of bearings (11) in the radial direction with respect to the rotation center axis of the bearing (11). A magnetic disk device comprising: a plurality of pressing portions to be pressed; and a preloading means configured by elastic means that holds the plurality of pressing portions and is bent to urge the pressing portions.