JPH06302098A - Driving device for magnetic disk - Google Patents

Abstract

PURPOSE:To improve the life of cutting tool and quality of the device and to decrease manufacturing cost. CONSTITUTION:A driving device for a magnetic disk is provided with a hub which mounts a magnetic disk at outer peripheral surface and drives it, a driving magnet which is fixed at inner peripheral surface of this hub, a stator core which is wound coil facing the driving magnet, and a frame which fixes the stator core. The frame 11 leaves cutting allowance at a collar section 11A, has a hole 11a of which inner peripheral surface is non-cut surface, is molded by metal injection molding from a sintered metal, and cutting allowance is cut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive device.

[0002]

2. Description of the Related Art Conventionally, there is known a so-called center axis rotating type magnetic disk drive device as shown in FIG. In the figure, reference numeral 1 indicates a frame, and a hollow cylindrical bearing holder portion 1b is integrally provided upright in the central portion. A bearing is attached to the outer periphery of the bearing holder portion 1b.
The core 3 is fixed, and the coil 4 is wound around the core 3. Outer rings of bearings 5 and 5 are fitted and fixed to the inner circumference of the bearing holder portion 1b.
A central shaft 6 is fitted and fixed to each inner ring of 5. A hub 7 shaped so as to cover the core 3, the coil 4, etc. is fitted and fixed to an end portion of the central shaft 6, and a magnetic disk (not shown) is provided on the outer peripheral surface of the core 3 on the inner peripheral surface. The ring-shaped drive magnets 8 are mounted at the positions facing each other. The coil 4 in the collar portion 1A of the frame 1
An insulating paper 11 is provided on the lower upper surface, and a flexible substrate (Flexible Print) extending to the outside of the motor is provided on the lower surface.
Circuits 10 are attached respectively. The flexible substrate 10 is one in which a conductor pattern is formed on a base made of an insulating material, and a cover made of an insulating material is coated on the conductive pattern. Coil 4 of the frame 1
As shown in FIGS. 4 and 5, a through hole 1a for drawing out the terminal wire 9 from the coil 4 is formed in the lower part of the terminal wire 9, and the terminal wire 9 is formed on the insulating paper 11. Hole (not shown), through hole 1a of frame 1, flexible substrate 1
It is soldered 10b on the conductor pattern portion (solder land portion) exposed from the cover of the flexible substrate 10 through the notch (not shown) of 0. And
The coil 4 from the power supply means (not shown) outside the motor through the conductor pattern of the flexible substrate 10 and the terminal wire 9.
By applying a predetermined drive voltage to the hub 7, the hub 7 having the magnetic disk mounted thereon is rotated.

Here, the frame 1 is, for example, SUS.
It is formed by cutting a solid iron-based round bar such as, or by finishing cutting an intermediate body that has been previously formed by forging or casting.

[0004]

However, the above magnetic disk drive device has the following problems. That is, when the frame 1 is formed by finishing cutting an intermediate body which has been formed by forging or casting in advance, the through hole 1a is already formed at the time of forging and casting. When the top surface 1d of 1A is finished, it becomes interrupted cutting, and what is formed by forging or casting tends to have waviness and dirt on its surface, so the cutting edge of the cutting tool is easily damaged (chipping). ,
There is a problem that the bite life is reduced. Further, when the frame 1 is formed by cutting a solid round bar, the number of hole forming steps is increased as compared with the above method, resulting in an increase in cost, which is not preferable. When finishing the upper surface 1d of the portion 1A, intermittent cutting is eventually performed, and since iron-based materials such as SUS are difficult-to-cut materials, the cutting edge of the cutting tool tends to be damaged as described above. I will end up. Also, if the cutting edge of the cutting tool is damaged as described above, the dimensional accuracy and surface roughness will deteriorate.
There is also a problem that the quality is lowered, the processing efficiency is reduced, and the cost becomes high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic disk drive device which can improve the bite life and quality and can reduce the cost.

[0006]

In order to achieve the above object, a magnetic disk drive apparatus of the present invention has a hub for mounting and driving a magnetic disk on the outer peripheral surface thereof, and a drive magnet fixed to the inner peripheral surface of the hub. And a stator core having a coil wound around the drive magnet and a frame for fixing the stator core, the magnetic disk drive comprising: It is characterized in that it has a hole with a margin left and an inner peripheral surface formed of a non-cutting surface, is made by metal injection molding from a sintered metal, and is cut by the cutting margin.

[0007]

According to the magnetic disk drive of the above-mentioned means, when the frame is metal injection molded from the sintered metal, holes can be formed on one surface with a very small cutting allowance, and no hole machining step is required. In addition, there is no hole in the portion with the very small cutting allowance, and the cutting with the extremely small cutting allowance is not intermittent cutting. Further, the metal injection molding of a sintered metal has excellent dimensional accuracy, and the surface thereof is free from undulations and stains, so that the cutting of the cutting allowance is performed well.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a frame applied to a magnetic disk drive according to an embodiment of the present invention before cutting, FIG. 2 is a view of FIG. 1 seen from below, and FIG. 3 is a portion A in FIG. 3 is an enlarged view of FIG. 3 and is the same as the conventional art with respect to other portions than the frame, and therefore the description thereof is omitted here. The difference between the frame of the magnetic disk drive device of this embodiment and that of the prior art is that the frame 11 is made of sintered metal so that a hole 11a with a cutting allowance X can be formed in the upper surface 11d of the flange portion 11A. Injection mold (Meta
l Injection Mold)

Here, this sintered metal is, for example, SUS4.
After 10 or SUS430 metal powder is kneaded with a binder made of polyethylene resin, it is injection-molded in a mold having a predetermined shape to prepare an intermediate.
It is baked and solidified at a high temperature of 00 ° C. or higher, and this method is called a so-called metal injection molding method.

If such a metal injection molding method is adopted, it is possible to form the hole 11a leaving a very small cutting margin X, which is impossible by the aluminum die casting method, for example. X is 0.1 mm to 0.2 mm.

Then, the cutting allowance X on the upper surface 11d of the collar portion 11A is cut, the upper surface of the hole 11a is chamfered, and the other necessary portions are cut to complete the structure as shown in FIG. The frame will be obtained.

As described above, in this embodiment, since the frame 11 is metal injection molded from the sintered metal, it is possible to form the hole 11a in which the minimum machining allowance X is left on the upper surface 11d of the collar portion 11A. Therefore, it is possible to reduce the cost because there is no need for a hole processing step. In addition, since there is no hole in the portion with a very small cutting allowance X, the cutting with a very small cutting allowance X is not intermittent cutting, and the metal injection molding of sintered metal is forging, casting, etc. Dimensional accuracy is superior to that produced by the machining method of No. 1, there is almost no undulations and dirt on the surface, and the cutting allowance X is satisfactorily cut, so there is no damage to the cutting edge. , It is possible to improve the part-time job. Further, as described above, the bite life can be improved and the machinability is good, so that it is possible to improve the processing quality, and the processing efficiency can be improved, which further reduces the cost. It is possible.

The invention made by the present inventor has been specifically described based on each embodiment, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example, in the above embodiment, SUS4 was used as the powder metal.
10 or SUS430 is optimally used,
It is not limited to SUS410 or SUS430.

It is also applicable to a type in which the bearing holder portion 1b and the frame are separate bodies.

Further, it is of course applicable to a fixed center axis type magnetic disk drive.

Furthermore, the present invention can be applied to a portion other than the brim portion of the frame.

[0017]

As described above, according to the magnetic disk drive of the present invention, since the frame is formed by the metal injection molding of the sintered metal, it is possible to form a hole with a very small cutting margin on one surface. As a result, a hole forming process is not required, and cost reduction can be achieved. In addition, since there are no holes in the part with a very small cutting allowance, cutting with a very small cutting allowance does not result in intermittent cutting, and metal injection molding made of sintered metal has excellent dimensional accuracy, and its surface has undulations. Therefore, there is almost no dirt, and the cutting of the cutting allowance can be performed well, so that the cutting edge of the cutting tool is not damaged and the life of the cutting tool can be improved. Further, as described above, since the bite life can be improved and the machinability is good, the processing quality can be improved, the processing efficiency can be improved, and the cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a frame applied to a magnetic disk drive according to an embodiment of the present invention before cutting.

FIG. 2 is a view of FIG. 1 seen from below.

FIG. 3 is an enlarged view of a portion A in FIG.

FIG. 4 is a cross-sectional view of a magnetic disk drive device showing a conventional technique.

5 is a cross-sectional view of the frame in FIG.

[Explanation of symbols]

 11 frame 11A frame flange 11a hole 11d one side X cutting allowance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Ishizuka 14-888 Ako, Komagane-shi, Nagano Stock company Sankyo Seiki Seisakusho Komagane factory

Claims (1)

[Claims] 1. A hub for mounting and driving a magnetic disk on the outer peripheral surface thereof, a drive magnet fixed to the inner peripheral surface of the hub, a stator core around which a coil facing the drive magnet is wound. In a magnetic disk drive including a frame for fixing a stator core, the frame has a hole in which a cutting margin is left on one surface and an inner peripheral surface is a non-cutting surface, and A magnetic disk drive device which is formed by metal injection molding from a binder metal and is formed by cutting the cutting allowance.