JPH07143720A - Arm assembly and voice-coil motor - Google Patents

Abstract

PURPOSE:To manufacture a firmly coupled arm assembly at low costs by a method wherein a protrusion part which is fixed and bonded to the tip of a suspension member and which has a hollow hole is fitted into a through hole which has been made in the tip of an arm piece and both are coupled integrally by applying a pressure to a direction in which the hollow hole is expanded. CONSTITUTION:A plurality of U-shaped grooves are formed in one end of a boss part 6 so as to be at right angles to the axial line of the boss part and along the axial line. Then, one end of an arm piece 7 which has supported the other end of a suspension 12 on which a recording and reproducing head 13 has been mounted at one end is fitted into, and mounted on, every U-shaped groove. The arm piece is stamped and molded to be a rectangular shape by a press stamping means, and a through hole is made. On the other hand, a spacer which has a guard part is fixed and bonded to the other end of the suspension 12 on which the head has been mounted at one end, and the guard part is force-fitted into the through hole. Then, a spherical body whose diameter is larger than that of the inside-diameter part of the guard part is inserted into the inside-diameter part and the suspension and the arm piece are fixed firmly by a force by which the inside-diameter part is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor used for head positioning means in a magnetic disk device and an arm assembly incorporated therein.

[0002]

2. Description of the Related Art In a magnetic disk device, a voice coil motor is used as a means for positioning a recording / reproducing head on a predetermined track on a magnetic disk. Among these magnetic disk devices, those used for laptop type or notebook type personal computers are
A magnetic disk of 3.5 inches or less is used. In such a small magnetic disk device, as a voice coil motor, a magnetic circuit portion having a pair of yokes facing each other and permanent magnets fixed to at least one yoke, and a magnetic circuit formed along the surface of the permanent magnets. A structure having a head arm (arm assembly) having a coil that swings in a gap is often used. The above arm assembly
A coil is fixed to the other end of an arm member that has a boss supported on a shaft provided in the case and an arm piece formed in multiple stages (a strip shape) at one end thereof, and a head is mounted at the tip of each arm piece. The suspension is fixedly formed. Then, the arm member is generally manufactured by die casting of an aluminum alloy.

[0003]

However, there is a demand for downsizing and increasing the capacity of recent magnetic disk devices, for example, a magnetic disk having a diameter of 3.5 inches having a recording capacity of 3 to 4 gigabytes (disk. Increase the number of
Accordingly, it is necessary to significantly increase the number of magnetic heads mounted on the head assembly (for example, 10 or more). On the other hand, the height of the head assembly (thickness of the boss portion) is limited in terms of downsizing of the magnetic disk device. For example, diameter 2.
In the case of a 5-inch magnetic disk, it is required to be 1/2 inch or less (about 10 mm). Therefore, the thickness of the carriage that forms the arm is 0.8 mm
It is necessary to make the thickness extremely thin, about 0.4 mm. However, when the arm portion having such an extremely thin arm piece is formed by the method of aluminum die casting, warping or bending of the arm piece occurs, and accurate positioning is almost impossible. Therefore, an object of the present invention is to provide an arm assembly capable of coping with miniaturization and high capacity of a magnetic disk device and a voice coil motor equipped with the arm assembly.

[0004]

In order to achieve the above object, in the first invention, a boss portion having a center of rotation, an arm portion having an arm piece formed in multiple stages at one end thereof, and the boss portion are provided. Has a coil member fixed to the other end thereof, and a suspension member fixed to the tip of each arm piece having a recording / reproducing head at one end thereof, and the coil member is disposed in the magnetic gap. In the arm assembly, insert a protrusion having a hollow hole fixed to the tip of the suspension member into the through hole formed at the tip of the arm piece made of a thin plate made of a non-magnetic metal material, and expand this hollow hole. The technical means of applying pressure in the direction of joining and joining them together was adopted. According to a second aspect of the present invention, there is provided a magnetic circuit section including a pair of opposing yokes and a permanent magnet fixed to at least one of the yokes, and a magnetic gap being formed on the surface of the permanent magnet; And an arm assembly configured as described above.

[0005]

With the above structure, the arm assembly in which the suspension and the arm piece having an extremely thin thickness are firmly coupled can be manufactured at low cost. Further, it is possible to obtain a voice coil motor suitable for a magnetic disk device which tends to be downsized and have a large capacity.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view of an essential part showing an embodiment of a coil assembly of the present invention, FIG. 2 is a sectional view taken along the line A--A of FIG. 1, and FIG. In FIG. 1 and FIG. 2, the arm assembly 5 is fixed to the other end of the boss 6 and an arm member 8 having an arm piece 7 fixed to one end of the boss 6 formed by aluminum alloy die casting, for example. Further, it has a flat coil 9 and a coil member 11 including a holding member 10. The other end of a suspension 12 having a recording / reproducing head 13 at one end is fixed to the tip of each arm piece 7. The above coil assembly can be manufactured as follows. First, a plurality of recessed grooves 14 are formed at one end of the boss portion 6 at right angles to and along the axis of the boss portion. Next, in each groove 14, one end of the recording / reproducing head 13
One end of the arm piece 7 supporting the other end of the suspension 12 on which is mounted is fitted. Here, as shown in FIG. 3, the arm piece is punched into a strip shape from a thin (0.1 to 0.2 mm thick) stainless steel plate by a press punching means, and the through hole 7a is formed during this shaping. Set up. When the recording capacity of the magnetic disk device is large, this arm piece requires as many as 10 or more sheets, so the thickness thereof is preferably 0.5 mm or less (more preferably 0.4 mm or less). Further, from the viewpoint of rigidity, it is preferable to use a non-magnetic metal material such as stainless steel or phosphor bronze having a spring property and a large specific gravity. On the other hand, the collar portion 1 is provided at the other end of the suspension 12 having the head mounted at one end.
The spacer 15 having 6 is fixed (for example, by beam welding), and the flange portion 16 is press-fitted into the through hole 7 a of the arm piece 7. Next, the inner diameter portion 17 of the collar portion 16
By inserting a sphere (for example, a steel ball) 20 having a larger diameter than that, a force is applied so that the inner diameter is expanded, so that the suspension and the arm piece can be firmly fixed. In this case, the connection between the arm piece and the suspension is
The means is not limited to a sphere, and other means may be used. The spacer 15 can be formed, for example, by punching from a metal thin plate made of the same material as the arm piece, and subjecting the inner diameter portion 17 to burring processing. Then, by fixing the coil member 11 to the other end of the boss portion 6, the coil assembly is obtained. Here, the boss portion 6 and the coil member 11 may be fixed to each other, for example, by bonding the coil member 11 having a bobbin accommodating the flat coil 9 to the boss portion. Further, after inserting the boss portion 6 and the flat coil 9 into the injection-molding die for positioning, injecting a heated melt of a thermoplastic resin such as polyphenylene sulfide resin, cooling and solidifying, and removing from the die. By the holding member 1
A coil assembly in which the flat coil 9 and the boss portion 6 are integrated with each other through 0 and the boss portion 6 and the arm piece 7 are integrated through the holding member 10 'is obtained (for example, Japanese Patent Application No. 1
No. 33214). Next, the above coil assembly 5 is shown in FIG.
A voice coil motor is obtained by combining with a magnetic circuit as shown in FIG. That is, in FIG. 4, reference numeral 1 denotes a yoke made of a ferromagnetic material, which is provided so as to face each other with a pillar 2 provided at an end portion therebetween. Reference numeral 3 denotes a permanent magnet, which is formed into a substantially trapezoidal flat plate shape, is magnetized in the thickness direction, and has N,
The magnetic pole 4 is fixed to the surface of the lower yoke 1 so that the S magnetic pole appears, and a magnetic gap 4 is formed between the magnetic pole 4 and the upper yoke 1. The coil assembly 5 is arranged in a casing (not shown) so that the flat coil 9 is located in the magnetic gap 4. With the above configuration, when the coil is energized, the driving force around the shaft 30 acts on the coil according to Fleming's left-hand rule, and the coil assembly 5 is rotated (swinged) to move the head to a predetermined position on the magnetic disk. Can be positioned on the recording track. The swing direction is switched by reversing the direction of the current flowing through the coil.

[0007]

Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since the arm piece can be formed of a rigid metal material, sufficient mechanical strength can be ensured and the resonance frequency of the head carriage can be increased even if the thickness of the free end is small. (2) Since the arm pieces can be firmly and inexpensively mounted over a large number of stages, it is possible to meet the demands for miniaturization and large capacity of the magnetic disk device. (3) Since it is easy to manufacture and assemble, it can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing an embodiment of a coil assembly of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view of part B in FIG.

FIG. 4 is an explanatory view of a main part showing an embodiment of a voice coil motor of the present invention. (A) is a partially crushed plane, (b) is a view in the direction C in (a).

[Explanation of symbols]

1 yoke, 2 columns, 3 permanent magnets, 4 magnetic air gaps, 5 arm assemblies

Claims (2)

[Claims] 1. An arm member having a boss portion having a center of rotation and an arm piece formed in multiple stages at one end thereof, a coil member fixed to the other end of the boss portion, and recording / recording at one end.
In an arm assembly having a reproducing head, a suspension fixed to the tip of the arm piece, and the coil member arranged in a magnetic gap, the arm piece is a thin plate made of a non-magnetic metal material. Formed, a through hole is formed at the tip thereof, and a protrusion having a hollow hole fixed to the tip of the suspension is inserted into the through hole, and the hollow hole is pressed in a direction to expand the both integrally. An arm assembly characterized by being connected. 2. A magnetic circuit unit including a pair of opposed yokes and a permanent magnet fixed to at least one of the yokes, wherein a magnetic gap is formed on the surface of the permanent magnet, and the magnetic circuit unit is rotatable in the magnetic gap. The voice coil motor according to claim 1, further comprising: an arm assembly according to claim 1.