JPH0142866Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a swing arm type actuator for positioning a head in a magnetic disk device.

Conventionally, in this type of swing arm type actuator, voice coils are attached to multiple arms each equipped with a magnetic head for writing and reading at the tip.
The shaft is rotatably supported by the housing through a bearing, and is configured to rotate smoothly. The voice coil constitutes a magnet circuit together with a fixed magnet, and by passing a current through the voice coil, a driving force is generated to rotate the arm and position the magnetic head. Positioning control is performed by reading positioning information written on the servo disk surface with a servo magnetic head and constructing a closed loop based on this information.

Incidentally, in recent years, the data recording density on magnetic disks has been increasing year by year, and as a result, it is necessary to position the magnetic head with higher precision than ever before, and the gain of the servo loop has become higher. As a result, the mechanical vibration of the actuator has a large effect on the stability of the positioning control system.

Among such mechanical vibrations, a vibration mode in which the shaft translates in the seek direction of the head is particularly problematic. One of the most important factors that determines the resonance frequency of this vibration mode is the spring constant between the shaft end and the housing. When the contact between the housing and the bearing and between the bearing and the shaft is incomplete, this spring constant becomes small and the resonance frequency of the vibration mode becomes low. Therefore, in order to make complete contact between the bearing, the shaft, and the housing, and to make the spring constant sufficiently high, a method as shown in FIG. 1 is adopted.

FIG. 1 is a vertical sectional view showing a conventional swing arm type actuator. In the figure, a round bar-shaped shaft 1 is rotatably supported by a housing 3 via bearings 2a and 2b. The inner ring of the bearing 2a is glued or press-fitted to the shaft 1, and the outer ring is glued to the housing 3. Therefore,
In this portion, the shaft 1, bearing 2a, and housing 3 are in complete contact with each other, and the spring constant of this portion is sufficiently large. On the other hand, the bearing 2b has an inner ring bonded to the shaft 1 and an outer ring bonded to the inside of a cylindrical bushing 4. The bushing 4 is pressed against the housing 3 by a radial spring 5 and is given a radial preload. Therefore, the spring constants in the radial direction between the shaft 1 and the bearing 2b, and between the bearing 2b and the bushing 4 are sufficiently large. Furthermore, since the bushing 4 is pressed against the housing 3 by the spring 5, the spring constant is sufficiently large between the bushing 4 and the housing 3. On the other hand, the spring 6 acts on the outer ring or the inner ring of the bearing 2b, and applies preload in the axial direction. This spring 6 also applies preload in the axial direction to the bearing 2a at the same time. 7 is an arm attached to the shaft 1 in a stacked state, and 8 is a driving voice coil attached to this arm.

The configuration of the conventional actuator is as described above, but since the shaft 1 and the bearing 2a, and the bearing 2a and the housing 3 are bonded to each other,
The disadvantage is that once the actuator is assembled, it is impossible to remove the shaft 1 again, making it difficult to replace a malfunctioning magnetic head.

This invention was made in order to eliminate the drawbacks of the conventional ones as mentioned above, and it consists of a disc-shaped bushing that is fixed with a screw so as to cover one end of the shaft, and a bushing that is glued to the outer periphery of this bushing. By supporting the shaft in the housing with a bearing having an inner ring and an outer ring bonded to the housing, the bearing and the shaft are connected by an inexpensive and simple mechanism, and the spring constant between the two is sufficiently high. Another object of the present invention is to provide a swing arm type actuator whose shaft can be easily removed from a housing.

An embodiment of this invention will be described below with reference to the drawings. FIG. 2 is a vertical cross-sectional view showing the shaft end and bearing portion on the side where radial preload and axial preload are not applied in a swinging arm type actuator according to an embodiment of the invention, and the figure is the same as FIG. 1. Codes indicate the same or corresponding parts. Reference numeral 9 denotes a disc-shaped bushing attached to the end of the shaft 1, the outer circumference of which is adhesively fixed to the inner ring of the bearing 2a. The outer ring of the bearing 2a is adhesively fixed to the housing 3. Disc shaped bushing 9
A cylindrical recess 9a having an inner diameter slightly larger than the outer diameter of the end of the shaft 1 is formed in the shaft 1.
It is in full contact with b. Further, there is a through hole 9c in the center of the disc-shaped bushing 9, and by passing a screw 10 into the through-hole 9c and tightening it, the disc-shaped bushing 9 and the shaft 1 are connected to the recess 9.
It is completely tightly fixed at the bottom part 9b of a. The bottom 9b of the recess 9a and the end face of the shaft 1 are
Both are perpendicular to the central axis of the shaft 1 and are arranged to coincide with or be located very close to a plane A-A passing through the center point of the bearing 2a in the width direction. This is to prevent the force generated when the shaft 1 tries to tilt with respect to the central axis from acting as a moment that tends to tilt the inner ring of the bearing 2a.

In the swing arm actuator configured as described above, the disc-shaped bushing 9 is in close contact with the end of the shaft 1 and the inner ring of the bearing 2a, and the outer ring of the bearing 2a is in close contact with the housing 3.
A large spring constant can be obtained. When the shaft 1 is to be removed from the housing 3, the end portion of the shaft 1 can be removed from the disc-shaped bushing 9 by loosening the spring 10. If radial preload and axial preload are applied to the other end of the shaft 1 in the same manner as in FIG. 1, the bushing 4 and housing 3 can be removed by removing these springs. In this way both ends of the shaft 1 can be easily removed from the housing 3.

In addition, although the above embodiment describes one end of the shaft 1, the same can be applied to the other end. Further, the shape and structure of the bushing 9 are not limited to those shown in the drawings, and can be changed.

As described above, according to this invention, a bearing has a disk-shaped bushing fixed by a screw so as to cover one end of the shaft, an inner ring bonded to the outer circumference of the bushing, and an outer ring bonded to the housing. Since the shaft is configured to be pivotally supported in the housing, it is possible to fix the bearing and shaft without adhesion and achieve a sufficiently large spring constant, and the shaft can be easily removed from the housing. .

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing a conventional swing arm type actuator, and FIG. 2 is a partial vertical sectional view showing a swing arm type actuator according to an embodiment of the present invention. 1...shaft, 2a, 2b...bearing, 3...
Housing, 4... Cylindrical bushing, 5... Radial preload spring, 6... Axial preload spring, 7... Arm, 8... Voice coil, 9...
Disc-shaped bushing, 10...screw. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) An arm equipped with a magnetic head for writing or reading data on a magnetic disk;
The arm includes a shaft to which the arm is attached, a driving voice coil that swings the arm about the shaft, and a housing that supports both ends of the shaft via bearings so that the shaft can rotate. A swinging arm type actuator that positions a magnetic head on an arbitrary track on a magnetic disk by swinging the shaft includes a disc-shaped bushing fixed by a screw so as to cover one end of the shaft, and the bushing. 1. A swing arm type actuator comprising: a bearing having an inner ring bonded to the outer periphery of the housing; and a bearing having an outer ring bonded to the housing. (2) The swing arm type actuator according to claim 1, wherein the bushing has a cylindrical recess that is in close contact with the end surface of the shaft. (3) Utility model registration claim 1 or 2, characterized in that the contact surface between the bushing and the shaft end surface substantially coincides with a plane that passes through the center point in the width direction of the bearing and is perpendicular to the axis of rotation. The swinging arm type actuator described in .