JP2010185546A - Bearing device and information recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device capable of enhancing positioning accuracy by suppressing resonance. <P>SOLUTION: The pivot shaft (bearing device) 10 includes: a shaft 40 formed to have a columnar shape around an axial line L1; a cylindrical sleeve 60 coaxially arranged in the radial direction of the shaft 40 leaving a predetermined interval and having an inner side filled with lubrication fluid J; and a bearing body 70 formed to have a cylindrical shape, arranged between the shaft 40 and the sleeve 60 and having an outer peripheral face 71 fixed to the sleeve 60 and an inner peripheral face 72 serving as an opposing face 73 opposing to the outer peripheral face 41 of the shaft 40 via the lubrication fluid J. A projection 74 is formed in the pivot shaft 10 so as to project from the opposing face 73 toward the outer peripheral face 41 of the shaft 40 to restrict flowing of the lubrication fluid J. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing device and an information recording / reproducing apparatus using the bearing device.

2. Description of the Related Art Conventionally, an information recording / reproducing apparatus such as a hard disk for storing and reproducing various kinds of information on a disk magnetically or optically is known. In general, an information recording / reproducing apparatus includes a carriage configured to be rotatable around a bearing device, a head gimbal assembly attached to the front end of the carriage, and a magnetic recording / reproducing head disposed at the front end of the head gimbal assembly. And a magnetic recording medium that is disposed to face the magnetic recording / reproducing head and rotates in a certain direction.
In such an information recording / reproducing apparatus, by rotating the bearing device with a motor or the like, the carriage can be rotated along a horizontal plane, and magnetic recording is arranged at the front end of the carriage via a head gimbal assembly. By moving the reproducing head to a predetermined position on the magnetic recording medium, signals and recording can be reproduced.

  In recent years, the recording density of information within a single recording surface has increased with an increase in the capacity of a hard disk or the like in a computer device, and in order to cope with this, an improvement in accuracy of position control of a magnetic head is desired. However, if the axis of each component constituting the bearing device is deviated, the accuracy of position control of the magnetic head is lowered when the carriage is rotated around the bearing device. Further, if the shaft center of the bearing device is deviated in this way, it may cause a disturbance in torque or cause noise, resonance, or the like.

  In order to solve such problems, there has been proposed a rolling bearing device that uses an adhesive to fix the inner ring and shaft of the rolling bearing and the outer ring and sleeve of the rolling bearing (for example, Patent Document 1). reference).

  In addition to the bearing device using the rolling bearing as described above, there is a bearing device that slidably supports a shaft on which a pair of hemispheres or conical surfaces are fixed by a support body in contact with the hemisphere or conical surfaces. Proposed. In this bearing device, the hemisphere and the conical surface are formed of ceramics, and the function of the bearing is realized by utilizing the slip between the hemisphere, the conical surface and the support (for example, see Patent Document 2).

JP 2001-214942 A JP 2002-250343 A

By the way, when controlling the positioning of the magnetic head, if the resonance frequency of the apparatus itself is generally low or the gain is high, positioning with high accuracy becomes difficult. Therefore, in the bearing device that positions the magnetic head, it is preferable that the resonance frequency is high and the gain is low.
However, in the case of a bearing device employing a rolling bearing as in Patent Document 1, it is difficult to increase the resonance frequency because of the structure, and the gain is also high, so that the positioning accuracy is increased to a certain extent. I could not.

  On the other hand, in the case of the bearing device using the hemisphere or the cone described in Patent Document 2, although the resonance frequency and gain can be lowered as compared with the rolling bearing, the resonance caused by the vibration of the shaft is still suppressed. There is a problem that the positioning accuracy is deteriorated.

  This invention is made in view of such a subject, Comprising: It aims at providing the bearing apparatus which can suppress a resonance and can make positioning accuracy high.

In view of the above problems, the present invention proposes the following means.
That is, the bearing device according to the present invention includes a shaft formed in a columnar shape centering on an axis, and a cylinder that is coaxially arranged with a predetermined spacing in the radial direction of the shaft and is filled with a lubricating fluid inside. And a cylindrical sleeve, which is disposed between the shaft and the sleeve, has an outer peripheral surface fixed to the sleeve, and an inner peripheral surface facing the shaft via the lubricating fluid A bearing device comprising: a bearing main body, and a pair of axially spaced apart outer peripheral surfaces of the shaft fixed to each other and a support member that contacts the bearing main body from both sides of the axial direction via the lubricating fluid. In this embodiment, a convex portion that protrudes from one of the opposing surface and the outer peripheral surface of the shaft toward the other and restricts the flow of the lubricating fluid is provided.

  According to the bearing device having such characteristics, when vibration of the shaft with respect to the sleeve and the bearing main body occurs, the lubricating fluid between the facing surface of the bearing main body and the outer peripheral surface of the shaft flows to cause the lubricating fluid to flow. Attempts to pass through the clearance between the facing surface and the convex portion. At that time, the flow of the lubricating fluid is restricted, whereby the pressure of the lubricating fluid is increased, and a resistance force against the vibration of the shaft is generated. That is, the convex portion functions as a valve that suppresses the flow of the lubricating fluid and exhibits a damping effect, so that the vibration of the shaft can be attenuated.

  Further, in the bearing device according to the present invention, the both end openings of the inner peripheral surface of the bearing body are a pair of taper receiving surfaces whose diameter increases toward the opening side, and the support member is the pair of taper receiving surfaces. It has a conical surface which contacts a surface via the lubricating fluid.

  According to the bearing device having such a feature, the pair of taper receiving surfaces is configured to be in sliding contact with the conical surface of the support member fixed to the shaft, so that the shaft can be reliably held on the inner peripheral side of the bearing body. Is possible. In addition, since the resonance frequency and gain can be lowered as compared with the case where a rolling bearing is employed, the occurrence of resonance can be suppressed.

  Furthermore, in the bearing device according to the present invention, the convex portion is formed continuously in a circumferential direction of the opposing surface or the outer peripheral surface of the shaft.

  Since the damping effect as a valve can be obtained in the entire circumferential direction of the shaft, the vibration of the shaft can be attenuated more effectively.

  Furthermore, the bearing device according to the present invention is characterized in that a coating layer for reducing a friction coefficient is formed on at least one of the convex portion and the outer peripheral surface of the shaft.

  According to the bearing device having such characteristics, it is possible to reduce the friction torque when the convex portion and the outer peripheral surface of the shaft are in contact with each other.

  An information recording / reproducing apparatus according to the present invention includes any one of the above-described bearing devices, a carriage that is configured to be rotatable around the bearing device, and has an arm portion that supports a head gimbal assembly, and a magnet that rotates in a predetermined direction. And a recording medium.

  According to the information recording / reproducing apparatus having such characteristics, since the bearing device is provided, the vibration of the shaft can be effectively attenuated, and the position of the head gimbal assembly with respect to the magnetic recording medium can be controlled with high accuracy. It becomes possible to do.

  According to the bearing device of the present invention, by providing a convex portion on the opposing surface of the bearing body or the outer peripheral surface of the shaft to function as a valve that suppresses the flow of the lubricating fluid, the vibration of the shaft is effectively attenuated, It becomes possible to prevent the occurrence of resonance.

It is a schematic block diagram of the information recording / reproducing apparatus in embodiment of this invention. It is sectional drawing of the pivot axis | shaft in embodiment of this invention. It is a principal part enlarged view in FIG.

  Next, an embodiment of a bearing device according to the present invention will be described with reference to FIGS. In the present embodiment, the case where the bearing device is used for the pivot shaft of the information recording / reproducing apparatus will be described.

  FIG. 1 is a schematic configuration diagram of an information recording / reproducing apparatus 1 according to the present invention. Note that the information recording / reproducing apparatus 1 of the present embodiment is an apparatus for writing on a disk (magnetic recording medium) D having a perpendicular recording layer by a thrust recording method.

  As shown in FIG. 1, an information recording / reproducing apparatus 1 includes a carriage 11, a head gimbal assembly (HGA) 12 supported on the front end side of the carriage 11, and a head gimbal assembly 12 on a disk surface D1 (the surface of the disk D). , An actuator 6 that scans and moves in a horizontal plane parallel to the axis, a spindle motor 7 that rotates the disk D about the axis L2, and a control that supplies a current modulated according to information to the slider 2 of the head gimbal assembly 12. A part 5 and a housing 9 for housing these components are provided.

  The housing 9 has a box-like shape having an upper opening made of a metal material such as aluminum, and is erected in a vertical direction with respect to the bottom 9a at the periphery of the bottom 9a and the periphery of the bottom 9a. It is comprised with the surrounding wall (not shown). And the recessed part which accommodates each component mentioned above is formed in the inner side enclosed by the surrounding wall. In FIG. 1, the peripheral wall surrounding the housing 9 is omitted for easy understanding of the description.

  Further, a lid (not shown) is detachably fixed to the housing 9 so as to close the opening of the housing 9. The spindle motor 7 is attached to substantially the center of the bottom portion 9a, and the disc D is detachably fixed by fitting a center hole into the spindle motor 7.

  The actuator 6 described above is attached to one corner of the bottom 9a outside the disk D. The actuator 6 is provided with a carriage 11 that can rotate along a horizontal plane about an axis L1 of a pivot shaft (bearing device) 10. The carriage 11 includes an arm portion 14 extending from the base end portion toward the tip portion (in the direction of the disk D), and a base portion 15 that supports the arm portion 14 in a cantilever manner via the base end portion. Are integrally formed by machining or the like. The base portion 15 is formed in a substantially rectangular parallelepiped shape, and is supported so as to be rotatable around the pivot shaft 10. That is, the base portion 15 is connected to the actuator 6 via the pivot shaft 10, and the pivot shaft 10 is the rotation center of the carriage 11.

The arm portion 14 extends in parallel with the surface direction (horizontal plane direction) of the upper surface of the base portion 15 on the side surface 15b opposite to the side surface 15a to which the actuator 6 is attached in the base portion 15 (side surface on the opposite side of the corner portion). It is a flat plate to be extended, and three pieces are extended along the height direction (vertical direction) of the base 15.
Specifically, the arm portion 14 is formed in a tapered shape that tapers from the proximal end portion toward the distal end portion, and is arranged so that the disk D is sandwiched between the arm portions 14 and 14. That is, the arm part 14 and the disk D are configured to be alternately arranged, and the arm part 14 can be moved in a direction parallel to the surface of the disk D (horizontal plane direction) by driving the actuator 6. . The carriage 11 and the head gimbal assembly 12 are retracted from the disk D by driving the actuator 6 when the rotation of the disk D is stopped.

  The head gimbal assembly 12 is connected to the tip of the arm portion 14, and includes a suspension 3 and a slider 2 attached to the tip of the suspension 3.

(Bearing device)
As shown in FIG. 2, the pivot shaft 10 includes a shaft 40 formed in a substantially columnar shape, a substantially cylindrical sleeve 60 arranged at a predetermined interval from the shaft 40, and the shaft 40 and the sleeve 60. And a pair of support members 50 and 50 fixed to the shaft 40.

  The shaft 40 is a substantially columnar rod-like member disposed around the axis L1, and a pair of support members 50 are fixed to the upper and lower portions of the outer peripheral surface 41 at a predetermined interval.

  The sleeve 60 is a member formed in a substantially cylindrical shape, and its inner diameter is sufficiently larger than the outer diameter of the outer peripheral surface of the shaft 40, and is coaxial with the shaft 40 so as to accommodate the shaft 40 inside. Is arranged.

A bearing body 70 having a substantially cylindrical shape is interposed between the shaft 40 and the sleeve 60 so as to be coaxial with the shaft 40 and the sleeve 60, that is, with the axis L1 as a central axis.
The length of the bearing body 70 in the axial direction is smaller than that of the sleeve 60, and the entire bearing body 70 is accommodated inside the sleeve 60. The outer peripheral surface 71 of the bearing body 70 is fixed to the inner peripheral surface 61 of the sleeve 60, and the bearing main body 70 and the sleeve 60 are configured to rotate integrally.

  Of the inner peripheral surface 72 of the bearing body 70, a substantially central portion in the direction of the axis L1 forms a cylindrical surface centered on the axis L1 and is a facing surface 73 that faces the outer peripheral surface 41 of the shaft 40. Yes. The inner diameter of the facing surface 73 is larger than the outer diameter of the outer peripheral surface 41 of the shaft 40, thereby forming a space between the facing surface 73 and the outer peripheral surface 41 of the shaft.

As shown in detail in FIG. 3, the bearing body 70 projects in a rectangular cross section from the facing surface 73 toward the outer peripheral surface 41 of the shaft 40, that is, radially inward, and has an axis L1. And a convex portion 74 formed in an annular shape that is continuous in the circumferential direction. The height of the convex portion 74 from the facing surface 73 is slightly smaller than the radius difference between the inner diameter of the facing surface 73 and the outer diameter of the outer peripheral surface 41 of the shaft 40, that is, between the opposing surface 73 and the outer peripheral surface 41 of the shaft. It is formed slightly smaller than the radial thickness of the space between. Thereby, a clearance d is formed between the convex portion 74 and the outer peripheral surface 41 of the shaft 40.
The convex portion 74 divides the space between the facing surface 73 and the outer peripheral surface 41 of the shaft into two spaces, and these two spaces are in communication with each other through a clearance d.

  Further, as shown in FIG. 2 and FIG. 3, of the inner peripheral surface 72 of the bearing body 70, both the opening end portions in the direction of the axis L <b> 1, that is, the portions on both sides of the facing surface 73 in the axis L <b> 1 direction. Tapered receiving surfaces 75 and 75 that gradually increase in diameter from the end of 73 toward the opening side (the axial end surface side of the bearing body 70) about the axis L1 are formed. The taper receiving surfaces 75 and 75 are formed so as to be symmetric with respect to the central portion in the axis L1 direction of the bearing body 70 as a boundary.

  The pair of support members 50, 50 fixed to the shaft 40 has a substantially cylindrical ring shape, and has an inner diameter that is substantially the same as the outer diameter of the outer peripheral surface 41 of the shaft 40. As a result, the support member 50 is fixedly integrated with the shaft 40 so as to be fitted on the outer peripheral surface 41 of the shaft 40 without a gap and projecting outward in the radial direction.

  The distance between the pair of support members 50, 50 in the direction of the axis L1 is substantially the same as the length of the facing surface 73 of the bearing body 70 in the direction of the axis L1, and the pair of support members 50, 50 The cylinder thicknesses of the 50 opposing end portions are formed to be substantially the same as the diameter difference between the radius of the facing surface 73 of the bearing body 70 and the radius of the outer peripheral surface 41 of the shaft 40.

  The support members 50, 50 have a conical surface 51 whose diameter increases from the end having the cylindrical thickness as described above in a direction away from each other, and this conical surface 51 is a taper receiver of the bearing body 70. It is comprised so that the surface 75 and 75 may contact, respectively.

  The sleeve 60 is hermetically sealed by an upper lid portion 65 having a disk shape in a state in which the shaft 40, the support member 50, and the bearing body 70 are accommodated therein, and the lower opening is further centered on the shaft 40. It is sealed by a lower lid portion 66 having a donut disk shape having a through-hole through which liquid is inserted.

  The inside of the sleeve 60 thus sealed is filled with the lubricating fluid J, whereby the lubricating fluid J is interposed in the gaps between the members. That is, as shown in FIGS. 2 and 3, the space between the facing surface 73 of the bearing body 70 and the outer peripheral surface 41 of the shaft 40, the clearance d between the convex portion 74 and the outer peripheral surface 41 of the shaft 40, and the taper. The lubricating fluid J is also interposed between the receiving surface 75 and the conical surface.

  As this lubricating fluid J, oil, grease, etc. with high extreme pressure are preferable, and those having a kinematic viscosity of 15 to 20 centistokes at 20 ° C. are particularly preferable. In addition, a gas such as air may be used as the lubricating fluid J.

Moreover, the structure by which the coating layer of the low friction coefficient was provided in at least one of the convex part 74 of the bearing main body 70 and the outer peripheral surface 41 of the shaft 40 may be sufficient.
Examples of the coating layer include a layer made of DLC (diamond-like carbon) or molybdenum disulfide. In the case of DLC, the coating layer can be formed by a technique such as vapor deposition or sputtering, and in the case of molybdenum disulfide, the coating layer can be formed by a technique such as painting or transfer.

  In the pivot shaft 10 configured as described above, the sleeve 60 rotates about the axis L1 in a state where the shaft 40 is fixed along the axis L1. That is, in a state where the shaft 40 and the sleeve 60 are arranged with the axis L1 as the center, the taper receiving surface 75 and the conical surface 51, particularly the convex curved surface 53, are slidably contacted with each other around the axis L1. To do.

In the pivot shaft 10 of the present embodiment, when vibration of the shaft 40 with respect to the sleeve 60 and the bearing body 70 occurs, the lubricating fluid that exists in the space between the facing surface 73 of the bearing body 70 and the outer peripheral surface 71 of the shaft 40. As J flows, the lubricating fluid J tends to pass through the clearance d between the outer peripheral surface 41 of the shaft 40 and the convex portion 74. At that time, the flow of the lubricating fluid J is restricted, so that the pressure of the lubricating fluid J increases, and resistance to vibration of the shaft 40 is generated.
That is, the projecting portion 74 functions as a valve that suppresses the flow of the lubricating fluid J, so that a damping effect is exhibited. As a result, it is possible to attenuate the vibration of the shaft 40 and suppress the occurrence of resonance.

  Further, in the pivot shaft 10, the pair of taper receiving surfaces 75 are configured to be in sliding contact with the support member 50 fixed to the shaft 40, so that the shaft 40 is disposed on the inner peripheral side of the bearing body 70 on the inner peripheral side. It can be held securely. Further, since the resonance frequency and gain can be lowered as compared with the case where a rolling bearing is employed, the occurrence of resonance can be more reliably suppressed.

  Furthermore, since the convex portion 74 is formed in an annular shape centering on the axis L1, a damping effect as a valve can be obtained in the entire circumferential direction of the shaft 40. Therefore, it becomes possible to attenuate the vibration of the shaft more effectively.

  Furthermore, in the bearing device according to the present invention, since the low friction coefficient coating layer is formed on at least one of the convex portion 74 and the outer peripheral surface 41 of the shaft 40, the convex portion 74 and the outer peripheral surface 41 of the shaft 40 It is possible to reduce the friction torque in the case of contact.

  And in the information recording / reproducing apparatus 1 of this embodiment, the arm part 14 (head gimbal assembly 12) is used using the pivot shaft 10 which can suppress the occurrence of resonance by attenuating the vibration of the shaft 40 as described above. Therefore, the position of the head gimbal assembly 12 with respect to the disk D can be controlled with high accuracy. That is, the recording density on the disk D can be increased, and the capacity of the information recording / reproducing apparatus 1 can be increased.

  As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to these without departing from the technical idea of the present invention, and some design changes and the like are possible.

  For example, in the embodiment, the convex portion 74 has been described as protruding from the facing surface 73 of the bearing body 70. Instead, the protruding portion 74 protrudes from the outer peripheral surface 41 of the shaft 40 toward the facing surface 73 of the bearing body 70. It may be what you did. Also by this, a damping effect as a valve that restricts the flow of the lubricating fluid J can be exhibited, and therefore, it is possible to attenuate the vibration of the shaft 40 and prevent the occurrence of resonance.

  In the embodiment, the support member 50 fixed to the shaft 40 is configured to be supported by the bearing body 70 by slidingly contacting the taper receiving surface 75 of the bearing body 70. As a configuration, a thrust plate that is in sliding contact with the end face of the bearing body 70 in the direction of the axis L1 may be employed. Also by this, the shaft 40 can be reliably held on the inner peripheral side of the bearing body 70, and the resonance frequency and gain can be reduced as compared with the case where a rolling bearing is employed. Therefore, it is possible to more reliably suppress the occurrence of resonance.

In the embodiment, the shaft 40 and the support member 50 are formed separately. However, the present invention is not limited to this, and the shaft 40 and the support member 50 may be formed integrally.
In the embodiment, the sleeve 60 and the bearing body 70 are formed separately. However, the present invention is not limited to this, and the sleeve 60 and the bearing body 70 may be formed integrally.

DESCRIPTION OF SYMBOLS 1 Information recording / reproducing apparatus 10 Pivot shaft 11 Carriage 12 Head gimbal assembly 14 Arm part 40 Shaft 41 Outer surface 50 Support member 51 Conical surface 60 Sleeve 61 Inner surface 70 Bearing main body 71 Outer surface 72 Inner surface 73 Opposite surface 74 Convex part 75 Taper receiving surface

Claims (5)

A shaft formed in a cylindrical shape centering on an axis,
A cylindrical sleeve that is coaxially arranged at a predetermined interval in the radial direction of the shaft and is filled with a lubricating fluid inside;
A bearing body having a cylindrical shape and disposed between the shaft and the sleeve, an outer peripheral surface fixed to the sleeve, and an inner peripheral surface opposed to the shaft via the lubricating fluid When,
A pair of bearing members spaced apart in the axial direction on the outer peripheral surface of the shaft and fixed to each other, and supporting members that respectively contact the bearing body from both sides of the axial direction via the lubricating fluid.
A bearing device, characterized in that a convex portion that protrudes from one of the opposing surface and the outer peripheral surface of the shaft toward the other and restricts the flow of the lubricating fluid is provided. Both ends of the inner peripheral surface of the bearing body are a pair of tapered receiving surfaces whose diameters are expanded toward the opening side,
The bearing device according to claim 1, wherein the support member has a conical surface that contacts the pair of taper receiving surfaces via the lubricating fluid.   The bearing device according to claim 1, wherein the convex portion is continuously formed in a circumferential direction of the opposing surface or the outer peripheral surface of the shaft.   The bearing device according to claim 1, wherein a coating layer that reduces a friction coefficient is formed on at least one of the convex portion and the outer peripheral surface of the shaft. A bearing device according to any one of claims 1 to 4,
A carriage configured to be rotatable around the bearing device;
A head gimbal assembly attached to the tip of the carriage;
A magnetic recording / reproducing head disposed at a tip of the head gimbal assembly;
An information recording / reproducing apparatus comprising: a magnetic recording medium that is disposed opposite to the magnetic recording / reproducing head and rotates in a predetermined direction.

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