JP2003016742A - Swing arm unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swing arm unit which enables stabilized support of imbalanced load of an oscillating swing arm and which can be made thin. SOLUTION: A swing arm 10 equipped with a magnetic head at one end is installed on a rotary supporting shaft 12 via a bearing 1 so as to freely rotate both in normal direction and reverse direction. The bearing 1 is constituted of a single-row radial rolling bearing 6 and a thrust sliding bearing 5. The width surface of an inner ring 2 or an outer ring 3 in the radial rolling bearing 6 is constituted of a sliding bearing surface in the thrust sliding bearing 5. The thrust sliding bearing 5 is constituted of a pair of thrust plates 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing arm device provided in a hard disk drive device or the like for supporting a magnetic head.

[0002]

2. Description of the Related Art With the miniaturization of computers, HDD devices (hard disk drive devices) built into computers have become thinner. This HDD device has
A spindle motor that rotates a magnetic disk that is an information storage medium as a rotational drive source, and a swing arm motor that swings a magnetic head that exchanges information (records and reads) with the hard disk to perform high-speed positioning on the hard disk. Is used. It has become necessary to shorten the axial length of any of the rotating body support mechanisms driven by these motors as the HDD device becomes thinner.

Conventionally, these rotary member support mechanisms have a structure in which an axial preload is applied to two ball bearings. FIG. 10 shows a swing arm device which is an example thereof. In this example, the swing arm 40 is swingably supported by a rotary support shaft 41 by two ball bearings 31, and an axial preload is applied to each ball bearing 31. A miniature bearing is used for each ball bearing 31. In recent years, special ball bearings smaller than the width dimension specified by JIS have been used in order to cope with thinning.

The swing arm device is a servo device for positioning the magnetic head 42 on the hard disk 43 at high speed. Therefore, the torque of the ball bearing 31, which is a fulcrum of the swing arm 40, is required to be as small as possible and not to change. Also, to ensure the stability of the servo system,
The natural frequency in the radial direction must be set high. To meet these requirements, two ball bearings 3
When assembling No. 1, it is also done while measuring the natural frequency (rigidity).

[0005]

The conventional rotating body supporting mechanism for supporting the swing arm 40 and the like uses two ball bearings 31 as described above, so that the cost is high and the axial length is long. Since the HDD device will be made thinner in the future, it will be necessary to make the ball bearing 31 thinner, which inevitably leads to an increase in manufacturing cost and assembly cost.

As the bearing for the spindle motor,
Dynamic pressure fluid bearings have begun to be used in place of ball bearings, and assembly costs are being reduced. In the case of a spindle motor, since it rotates at a rotational speed of several thousand rpm, it is possible to replace the ball bearing with a hydrodynamic bearing. However, in the case of the swing arm 40, since swing motion, that is, forward and reverse rotation, is performed, the velocity becomes zero at the swing end, and no fluid film is formed. Therefore, the same hydrodynamic bearing as the spindle motor cannot be used.

An object of the present invention is to provide a swing arm device capable of stably supporting an unbalanced load of a swing arm which makes a swing motion and capable of reducing the thickness. Another object of the present invention is to reduce the number of parts, reduce the cost, and further reduce the thickness. Still another object of the present invention is to facilitate the assembly work by adhesion.

[0008]

According to the swing arm device of the present invention, a swing arm is rotatably mounted on a base through a bearing, and the swing arm is mounted on an information recording surface of a magnetic disk at one end of the swing arm. In a swing arm device provided with a magnetic head facing each other and a head positioning mechanism for driving a swing arm in forward and reverse directions, the bearing comprises a single row radial rolling bearing and a thrust sliding bearing, and the inner ring in the radial rolling bearing. Or the width of the outer ring is
It is characterized in that it is constituted by a slide bearing surface in the thrust slide bearing. According to this structure, the radial rolling bearing supports the radial load, and the thrust slide bearing supports the moment load and the thrust load. Therefore, the swing arm with an unbalanced load can be stably supported. Thrust plain bearings have a sliding bearing surface that is the inner or outer ring width surface of a radial rolling bearing.Therefore, the entire bearing that combines both radial and thrust type bearings is similar to a single row single rolling bearing. It has a simple and compact structure. Therefore, a thin-walled type swing arm device is possible.

In the radial rolling bearing, at least one of the raceways of the inner ring or the outer ring may be grooveless. Since the thrust load is supported by the thrust slide bearing, the radial rolling bearing does not need to support the thrust load. Therefore, there is no problem even if there is no groove. With no groove, the raceway surface need only be a cylindrical surface, which facilitates manufacturing. When either one of the race surfaces of the inner ring and the outer ring is formed by the groove inner surface, the position of the rolling element in the thrust direction is restricted. If both raceway surfaces are not grooved, the manufacturing becomes easier.

The radial rolling bearing may have a negative clearance. By setting the negative gap, the radial rigidity is increased, and the swing arm can be supported more stably.

The thrust plate constituting the thrust slide bearing may be a member which also serves as a seal for preventing leakage of lubricant. Since the thrust plate also serves as a seal, the number of parts can be reduced, the cost can be reduced, and the wall thickness can be further reduced while obtaining the leakage preventing function of the lubricant.

An adhesive reservoir may be provided in at least one of the fitting portion between the inner ring and the shaft and the fitting portion between the outer ring and the swing arm of the radial rolling bearing. By thus providing the adhesive reservoir, the assembly work by bonding the inner ring and the shaft and the assembly work by bonding the outer ring and the swing arm are facilitated.

[0013]

1 is a block diagram of a first embodiment of the present invention.
3 to FIG. In this swing arm device, the swing arm 10 is attached to a rotary support shaft 12 of a base 11,
The head positioning mechanism 22 is installed so as to be rotatable forward and backward through the bearing 1, and has a magnetic head 13 facing the information recording surface of the magnetic disk 14 at one end of the swing arm 10 to drive the swing arm 10 forward and backward. Is provided.
The magnetic head 13 is for recording or reading information, or for both recording and reading.

The base 11 comprises a housing of a hard disk drive device and the like. The rotary support shaft 12 is a hollow shaft having an internal thread formed on the inner diameter surface thereof, and is fixed to the base 11 by a set screw 23 inserted from the rear surface of the base 11. The head positioning mechanism 22 is an oscillating motor including a rotor 22a provided on the other end of the swing arm 10 and a stator 22b installed on the base 11 so as to face the rotor 22a. In this example, the rotor 22a is a coil and the stator 22b is a magnet. Conversely, the rotor 22a may be a magnet and the stator 22b may be a coil.

As shown in FIG. 3, the bearing 1 comprises a single row radial ball bearing 6 and a thrust slide bearing 5, and the width surface of the outer ring 3 of the radial ball bearing 6 is the slide bearing surface of the thrust slide bearing 5. Becomes The rolling elements 4 are balls. A cylindrical fixing member 8 is fixed to the outer diameter surface of the outer ring 3 in a fitted state. The raceway surface 2a of the inner ring 2 of the radial ball bearing 6 is formed by the inner surface of the raceway groove, and the raceway surface 3a of the outer ring 3 is a cylindrical surface. The raceway groove forming the raceway surface 2a is preferably a groove having an arcuate cross-sectional shape having a radius of curvature slightly larger than the radius of curvature of the rolling element 4. The raceways 2a, 3a of the inner and outer rings 2, 3 are superfinished. The radial gap between the raceway surfaces 2a and 3a and the rolling element 4 is a negative gap, thereby increasing the radial rigidity.

The thrust slide bearing 5 has a pair of thrust plates 15 facing the width surfaces on both sides across the inner and outer races 2, 3.
It is composed of In this example, the thrust plate 15
Is fixed to the width surface of the inner ring 2. The width of the inner ring 2 is made slightly wider than the width of the outer ring 3, for example, about several microns.
A gap G is provided between the thrust plate 15 and the outer ring 3. The size of the gap G is such that even if the inner ring 2 and the outer ring 3 move relative to each other in the axial direction by the gap G, the rotor 22a and the stator 22b of the head positioning mechanism 22 (FIG. 1).
The size is set so that there is no interference with. This gap G
The widthwise surface of the outer ring 3 that forms the groove and the facing surface of the thrust plate 15 serve as a plain bearing surface. The thrust slide bearing 5 is required to have wear resistance. In order to respond to this, it is necessary to improve the finish roughness of the slide bearing surface of the thrust plate 15, increase the hardness of the surface, or use a high hardness material for the thrust plate 15. Has been taken. Nitriding treatment, shot blasting treatment, and hard coating (DLC, TIN, etc.) can be used for increasing the hardness of the surface. As the high hardness material, ceramics can be adopted in addition to the bearing steel.

The thrust plate 15 constituting the thrust slide bearing 5 also serves as a seal for preventing leakage of the enclosed lubricant. Specifically, the gap G2 between the outer diameter surface of the thrust plate 15 and the inner diameter surface of the fixing member 8 is set so that the lubricant does not move to the outside of the bearing due to a capillary phenomenon depending on the viscosity of the lubricant. There is.

As shown in FIG. 2, the rotary support shaft 12 of the bearing 1
The inner ring 2 is fitted to the outer diameter surface of the rotary support shaft 12 to be fixed to. The inner ring 2 is fixed by using this fitting as an interference fit or by adhering. Swing arm 1 to bearing 1
The fixing member 0 on the outer periphery of the outer ring 3 is fixed to the fitting hole 10a provided at the intermediate portion of the swing arm 10 in the longitudinal direction.
Is fitted, and the nut 24 is screwed into a male screw portion (not shown) provided on the outer diameter surface of the fixing member 8 and tightened.

According to this structure, the bearing 1 can receive the load in the radial direction by the single-row radial ball bearing 6 and the moment load and the thrust load by the thrust slide bearing 5. Therefore, the unbalanced load of the swing arm 10 that swings can be supported by the single bearing 1. Therefore, the swing arm device can be thinned. Further, since the bearing 1 is preloaded only in the radial direction, smooth rotation is possible while maintaining high rigidity. The necessary rigidity can be obtained only by controlling the amount of preload (the amount of negative clearance) in the radial direction. In addition, the thrust plate 15 of the thrust slide bearing 5 of the bearing 1 can prevent leakage of the enclosed lubricant. A lubricant is enclosed in the bearing 1 of this type for the purpose of reducing the torque. However, if the lubricant goes out of the bearing, it contaminates the environment inside the hard disk drive device, so that a seal is required.
Conventionally, the seal plate is press-fitted into the ball bearing, but in this embodiment, since the thrust plate 15 is also used as the seal member, the conventional seal plate can be omitted, the number of parts can be reduced, the cost can be reduced, and Further thinning becomes possible.

In this embodiment, the case where the thrust plate 15 of the thrust slide bearing is provided on the end surface of the inner ring 2 is shown, but the present invention is not limited to this, and the width of the outer ring 3 is made wider than the width of the inner ring 2. The thrust plate 15 may be provided on the end surface of the outer ring 3 to form a slide bearing surface between the inner ring 2 and the thrust plate 15.

The slide bearing surface of the thrust plate 15 is preferably subjected to lubricity improving treatment, and the improvement of lubricity can contribute to the improvement of wear resistance. As the lubricity improving process, as shown in FIG. 4, the sliding bearing surface of the thrust plate 15 is made a surface having innumerable depressions 16, or as shown in FIG. 5, the sliding bearing surface of the thrust plate 15 is provided with a groove 17. By providing it, it is effective to make it easier for the lubricant to enter the plain bearing surface.

Although not shown in FIG. 3, since contact between the rolling elements 4 increases the torque, a spacer made of resin is arranged between the rolling elements 4 and lubrication is performed by grease. In order to further improve the lubricity, it is effective to use a spacer made of a resin impregnated with a lubricating oil (for example, polyloop (NTN: trade name)).

Although FIG. 3 shows an example in which a ball is used as the rolling element 4, the rolling element 4 is not limited to this, and a roller may be used as the rolling element 4. When rollers are used for the rolling elements 4, the rigidity can be improved. In particular, when hollow rollers are used, elastic deformation of the rolling elements 4 increases, so that the negative clearance can be easily managed.

Although FIG. 3 shows an example in which the raceway surface 2a of the inner ring 2 is the inner surface of the raceway groove and the raceway surface 3a of the outer ring 3 is not grooved, both raceway surfaces 2a and 3a are the inner surface of the raceway groove. Alternatively, the outer race 3 may be provided with a raceway groove, and the inner race 2 may be formed without a groove.

The following bearings may be used as the bearing 1 in the swing arm device of the embodiment shown in FIG. The bearing 1 shown in FIG. 6 is obtained by improving the lubricating life by forming the thrust plate 15 from a porous material such as a sintered material in the bearing 1 of FIG. 3 and impregnating this with lubricating oil. . In this case, oil leaks from the surface opposite to the sliding bearing surface, so a back plate 18 is attached to the surface opposite to the sliding bearing surface as a leak preventing means. In addition to attaching the back plate 18, an oil leakage prevention layer such as a coating may be provided. Other configurations are the same as those in the example of FIG.

FIG. 7 shows another example of the bearing. In this example, in the example of FIG. 3, the outer ring 3 and one thrust plate 15 are integrated as an inner ring 3A with a thrust plate. Similarly to this embodiment, the inner ring 2 and one thrust plate 15 may be integrated.

FIG. 8 shows a bearing according to still another embodiment. In this example, a chamfer 15a is provided on the outer diameter surface of the thrust plate 15 on the outside of the bearing, and the surface tension of the lubricant is utilized to obtain the action of preventing leakage of the enclosed lubricant. In each of the above embodiments, the gap G2 between the outer diameter surface of the thrust plate 15 and the inner diameter surface of the fixing member 8 is set so that the lubricant does not move to the outside of the bearing due to the capillary phenomenon depending on the viscosity of the lubricant. This prevents leakage of the enclosed lubricant. However, the gap G2 may not be set due to the size limitation of the swing arm device.
In such a case, by providing the chamfer 15a to prevent the leakage of the lubricant, it is effective to obtain the function of preventing the leakage of the lubricant while achieving compactness.

FIG. 9 shows a bearing according to still another embodiment. In the bearing 1 of this example, adhesive reservoirs 19 and 20 are provided at the fitting portion between the inner ring 2 and the rotary support shaft 12 of the radial rolling bearing 6 and the fitting portion between the fixing member 8 of the outer ring 3 respectively. . The adhesive reservoir 19 on the inner ring 2 side is formed by a groove or a local recess provided on the outer diameter surface of the rotary support shaft 12. The adhesive reservoir 20 on the outer ring 3 side is formed by a groove or a local recess provided on the outer diameter surface of the outer ring 3. As a method of assembling the bearing component to the rotary support shaft 12 and the fixed member 8, bonding is an excellent method from the viewpoint of cost. When performing adhesive assembly, the adhesive reservoir 1 as described above
By providing 9 and 20, adhesion can be performed easily and surely. Although not shown in the figure, an adhesive reservoir may be provided on the surface to be bonded, such as the inner diameter surface of the inner ring 2 or the inner diameter surface of the fixing member 8. Further, an adhesive reservoir may be provided in the fitting portion between the fixing member 8 and the fitting hole 10a (FIG. 2) of the swing arm 10.

[0029]

According to the swing arm device of the present invention, the swing arm is installed on the base through a bearing so as to be rotatable forward and backward, and the magnetic head facing the information recording surface of the magnetic disk is provided at the tip of the swing arm. In the swing arm device provided with a head positioning mechanism for driving the swing arm in the forward and reverse directions, the bearing comprises a single row radial rolling bearing and a thrust slide bearing, and the width surface of the inner ring or the outer ring in the radial rolling bearing is However, since it is composed of the slide bearing surface in the thrust slide bearing, it is possible to stably support the unbalanced load of the swing arm that swings while making the wall thickness thin. When at least one of the raceways of the inner ring or the outer ring of the radial rolling bearing has no groove, the inner ring or the outer ring can be easily manufactured. When the radial rolling bearing has a negative clearance, the radial rigidity is increased and the swing arm can be supported more stably. When the thrust plate that constitutes the thrust plain bearing is a member that also functions as a seal that prevents leakage of lubricant, it is possible to reduce the number of parts while achieving a sealing function, reduce costs, and further reduce the wall thickness. become. The fitting part between the inner ring of the radial rolling bearing and the shaft,
Further, when the adhesive reservoir is provided on at least one of the fitting parts of the outer ring and the swing arm, the assembling work by bonding becomes easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a swing arm device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a rotation supporting portion of the swing arm device.

FIG. 3 is a sectional view of a bearing of the swing arm device.

FIG. 4 is a plan view showing an example of a thrust plate in the bearing.

FIG. 5 is a plan view showing another example of the thrust plate in the bearing.

FIG. 6 is a sectional view of a bearing according to still another embodiment of the present invention.

FIG. 7 is a sectional view of a bearing according to still another embodiment of the present invention.

FIG. 8 is a sectional view of a bearing in still another embodiment of the present invention.

FIG. 9 is a sectional view of a bearing according to still another embodiment of the present invention.

FIG. 10 is a sectional view of a conventional example.

[Explanation of symbols]

1 ... Bearing 2 ... Inner ring 2a ... orbital plane 3 ... Outer ring 3a ... orbital plane 4 ... rolling elements 5 ... Thrust plain bearing 6 ... Radial rolling bearing 8 ... Fixing member 10 ... Swing arm 12 ... Rotating spindle 13 ... Magnetic head 14 ... Magnetic disk 15 ... Thrust plate 22 ... Head positioning mechanism

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3J016 AA08 BB17 CA08                 3J101 AA03 AA42 AA52 AA63 BA53                       BA54 BA56 BA77 FA44 FA46                       FA53 GA53                 5D068 AA01 BB01 CC12 GG07

Claims (5)

[Claims] 1. A swing arm is rotatably and reversely installed on a base via a bearing, and a magnetic head facing an information recording surface of a magnetic disk is provided at one end of the swing arm.
In a swing arm device provided with a head positioning mechanism for driving the swing arm in the forward and reverse directions, the bearing comprises a single row radial rolling bearing and a thrust slide bearing,
A swing arm device, wherein a width surface of an inner ring or an outer ring in the radial rolling bearing is constituted by a sliding bearing surface in the thrust sliding bearing. 2. The swing arm device according to claim 1, wherein at least one of raceway surfaces of the inner ring or the outer ring of the radial rolling bearing has no groove. 3. The swing arm device according to claim 1, wherein the radial rolling bearing has a negative clearance. 4. The swing arm device according to claim 1, wherein the thrust plate forming the thrust slide bearing is a member that also serves as a seal for preventing leakage of a lubricant. 5. An adhesive reservoir is provided in at least one of a fitting portion between an inner ring and a shaft and a fitting portion between an outer ring and a swing arm of the radial rolling bearing. The swing arm device described in 1.