JPH08275439A - Spindle motor for magnetic disk - Google Patents

Abstract

PURPOSE: To provide a thin and accurate spindle motor for driving magnetic disk which has improved productivity, less problems for magnetic disk, and has an inexpensive housing. CONSTITUTION: In a spindle motor for driving magnetic disk where a bearing is provided at the inner periphery of a central cylindrical part 15 of a housing 1 and a rotor hub part 2 is supported so that it can freely rotate relatively for the housing 1 via the bearing, the housing 1 is formed by press-work aluminum metal and damping metal plate, and a flexible printed circuit board take- out port 11 is formed at the bottom surface part of the housing 1 or at the bending part at the bottom surface side of an outer-periphery cylindrical part 16 which continues to a flange part 17 of the housing 1 by press work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a magnetic disk drive, and is suitable for a magnetic disk drive having a small diameter of 1.8 inches or 2.5 inches or less and a small magnetic disk drive for PCMCIA. The present invention relates to a spindle motor for driving a magnetic disk used in.

[0002]

2. Description of the Related Art In recent years, magnetic disk devices have become smaller and lighter,
There is a trend toward higher capacity. With the spread of the PCMCIA interface for notebook-sized personal computers and memory cards, it is inevitable that spindle motors will be made smaller and thinner, and shock resistance will be improved, higher accuracy, lower noise, and lower vibration, Cost reduction is demanded.

In particular, in a PCMCIA compatible spindle motor for driving a magnetic disk, thinness and lightness and portability are important. Therefore, there is an extremely strong demand for impact resistance for its small size, and a ball bearing cannot support it. Hydrodynamic bearings are beginning to be developed.

Further, in terms of space, the position where the lead wire of a flexible printed circuit board (hereinafter referred to as FPC) is taken out is also limited.

A conventional spindle motor for driving a magnetic disk will be described below with reference to FIG. In FIG. 6, 31 is a motor housing, 32 is a rotor hub,
33 is a ball bearing, 34 is a shaft, 35 is a magnet fixed to the rotor hub portion 32, 36 is a stator core,
37 is a coil. 38 is an FPC, 39 is a terminal lead wire 40 of the coil 37 formed on the bottom surface of the housing 31.
It is a hole for inserting.

A stator core 36 around which a coil 37 is wound is fixedly attached to the outer peripheral surface of the central cylindrical portion of the housing 31.
Two ball bearings 33 are fixed to the inner circumference of the central cylindrical portion of the housing 31. A shaft 34 is fixed to the center of the rotor hub portion 32, and is rotatably supported by the housing 31 via a ball bearing 33.

The rotor hub portion 32 is formed into a cup shape having a disc receiving surface and a disc inner diameter regulating cylindrical portion,
A cylindrical magnet 3 having N-poles and S-poles alternately magnetized in the circumferential direction is provided on the inner circumference of the motor-side cylinder of the rotor hub 32.
5 is fixed.

The FPC 38 is attached to the bottom surface of the housing 31, a hollow insulating tube is inserted into a hole 39 formed in the housing 31, a terminal lead wire 40 is passed through the tube, and the FPC 38 is soldered to the FPC 38. . After that, the hole 38 is covered with an ultraviolet curable adhesive and hardened to seal the inside of the motor.

[0009]

The housing 31 in the conventional magnetic disk drive spindle motor described above is
Since the shape is complicated and the thickness is not uniform, it is composed of a machined product from a bar material, or a partially processed aluminum die cast product. In particular, aluminum die-casting is often used because it is lightweight and can be used for different plate thicknesses and complicated shapes, but aluminum die-casting has the following problems.

(1) Since it is a cast product, its dimensions change after processing.

(2) Since it is a cast product, burrs are liable to be formed, and a magnetic disk which does not like dust requires a step such as barrel processing for removing burrs.

(3) The gas trapped in the cavity generated during casting comes out and attacks the surface of the magnetic disk.

(4) White powder is generated.

(5) The thickness cannot be reduced.

(6) It is necessary to cut the gate opening and the mounting surface.

(7) The damping characteristics of the material cannot be improved.

(8) Burrs are often generated in the holes for the coil end lead wires, and disconnection and insulation failure due to burrs are likely to occur.

In addition to the above-mentioned problems, the following problems are also caused by the requirement structure.

(1) In the case of a thin motor, since the housing plate thickness is also thin, it is not possible to secure a sufficient plate thickness for the coil terminal lead wire outlet, which limits the device thickness.

(2) In a small device, the vibration generated from the ball bearing is large, and the reliability of recording / reproducing on the magnetic disk is reduced.

In view of the above conventional problems, it is an object of the present invention to provide a magnetic disk drive spindle motor having a thin housing, high accuracy, high productivity, less problems with respect to a magnetic disk, and an inexpensive housing. I am trying.

[0022]

In a spindle motor for driving a magnetic disk according to the present invention, a bearing is disposed on the inner circumference of a central cylindrical portion of a housing, and a rotor hub portion is rotatable relative to the housing via the bearing. In the supported spindle motor for driving a magnetic disk, the housing is formed by press working.

As the material of the housing, an aluminum metal plate or a vibration damping metal plate is preferably used.

Further, a hole for taking out the flexible printed circuit board is formed in the bottom surface portion of the housing or the bottom surface side bent portion of the outer peripheral cylindrical portion continuous with the flange portion of the housing by press working.

Further, a hole for taking out the flexible printed circuit board and a recess for preventing the flexible printed circuit board from protruding from the bottom surface of the housing may be formed by pressing on the bottom surface of the housing.

[0026]

According to the magnetic disk drive spindle motor of the present invention, since the housing is formed by press working, a thin and highly accurate housing can be manufactured inexpensively by mass production using a thin plate material. Therefore, the spindle motor for driving the magnetic disk can be provided with high productivity and at low cost.

If an aluminum-based metal plate is used as the material of the housing, the weight can be reduced, and if a vibration-damping metal plate is used, high vibration resistance can be ensured.

By pressing the hole for taking out the flexible printed circuit board, the housing can be processed only once and burrs can be easily eliminated.
No insulation failure occurs. The hole may be formed on the bottom surface portion, but when the hole is formed on the bottom surface side bent portion of the outer peripheral cylindrical portion, the flexible printed circuit board can be taken out of the housing in a straight state. Further, by forming a hole and a recess in the bottom surface of the housing, the flexible printed circuit board can be taken out without sticking out from the bottom surface of the housing.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk driving spindle motor of the present invention will be described below with reference to the drawings.

(Embodiment 1) A first embodiment in which the present invention is applied to a spindle motor for driving a magnetic disk utilizing a shaft rotary type fluid dynamic bearing will be described with reference to FIGS. 1 and 2. 1 is a motor housing, 2 is a rotor hub,
3 is a sleeve part, 4 is a shaft, and 5 is a thrust plate. Further, 6 is a rotor frame, 7 is a magnet, 8 is a stator core, and 9 is a coil. 10 is FPC, 11
Is an FPC outlet formed on the bottom wall of the housing 1,
12 is the F taken out from the FPC take-out port 11 to the outside.
An FPC arranging recess formed on the outer surface of the bottom surface of the housing 1 for disposing the PC 10, 13 is a protrusion provided on the outer circumference of the upper end of the sleeve portion 3, 14 is an inner periphery of the rotor hub portion 2, and the protrusion 13 can be engaged with the protrusion 13 from below. It is a fastener attached to.

The housing 1 is formed by press working, and has a central cylindrical portion 15, an outer peripheral cylindrical portion 16 and a flange portion 1.
7, the outer periphery of the flange 17 is attached to the chassis of the magnetic disk drive. The sleeve portion 3 is attached to the inner circumference of the central cylindrical portion 15, and the stator core 8 around which the coil 9 is wound is fixed to the outer circumference of the central cylindrical portion 15. The rotor hub portion 2 has a cup shape having a disc receiving surface 18 and an inner diameter regulating cylindrical portion 19 that regulates the inner diameter of the disc. The motor rotor mainly including the rotor hub portion 2 rotates around a shaft 4 fixed at the center of the cup-shaped rotor hub portion 2. A cylindrical magnet 7 having N-poles and S-poles alternately magnetized in the circumferential direction is fixed to the inner periphery of the cylindrical portion of the outer periphery of the rotor frame 6 fixed to the rotor hub portion 2.

The motor provided with this motor rotor and the housing 1 is a radial type brushless motor, in which a current is passed through the coil 9, a magnetic field is generated at the salient poles of the stator core 8, and a magnetic field for facing the stator core 8 is generated. Torque is generated between the magnet 7 and the motor rotor. Therefore, the disk receiving surface 18 of the rotor hub portion 2
The magnetic disk (not shown) clamped on the disk rotates.

The thrust plate 5 is fixed by caulking to the lower end of the sleeve portion 3 fixed to the central cylindrical portion 15 of the housing 1, and the inside thereof is filled with lubricating oil as a fluid substance. The thrust plate 5 is formed with a dynamic pressure bearing groove formed of a spiral groove, and is freely rotatable in the thrust direction by the dynamic pressure generated at the end surface of the thrust plate 5 and the shaft 4 as the shaft 4 rotates. It is supported. Further, a herringbone type groove is formed at two locations at intervals on the inner peripheral surface of the sleeve portion 3 to form a radial dynamic pressure bearing, and the dynamic pressure generated in the lubricating oil causes the shaft 4 to move.
Are rotatably supported without contacting the sleeve portion 3.

When the rotor hub portion 2 of the motor moves in the thrust direction due to impact or the like, the protrusion 1 provided on the sleeve portion 3
Since the stopper 14 fixed to the rotor hub portion 2 comes into contact with the rotor 3, the rotor hub portion 2 is structured so as not to come out.

An FPC take-out port 11 consisting of one elongated hole formed by press molding on the bottom surface of the housing 1.
The FPC 10 is inserted into the housing 1 and is inserted into the housing 1.
A coil terminal lead wire is soldered to the land portion of the PC 10 and wired outside the motor through the FPC 10. The FPC take-out port 11 is coated with an ultraviolet curable adhesive to cure the FPC take-out port 11 in order to seal the inside. At that time, FP
Workability is good because there is only one C outlet 11. Further, burrs generated at the corners of the FPC take-out port 11 due to burr of the press are pressed by the surface pressing press.
Insulation failure of 0 does not occur.

Further, since the FPC arranging concave portion 12 is provided by adding a step pressing process so that the FPC 10 does not protrude from the outer surface of the bottom surface portion of the housing 1, the FPC 10 can be arranged within the motor height.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In the following description of the embodiments, the same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Only the differences will be described.

In FIG. 3, the housing 1 is used in this embodiment.
The FPC take-out port 11 is formed by press working on the cylindrical portion side of the corner portion between the outer peripheral cylindrical portion 16 and the bottom surface portion.

According to this structure, since the FPC take-out port 11 is located at the same height as the FPC 10 attached to the inner surface of the bottom surface of the housing 1, the FPC 1
It can be taken out of the housing 1 while keeping 0 straight, and when connecting with the FPC connector part on the chassis side, the position of the connector part does not vary and stress is not applied to the connector part.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the vibration damping metal plate 20 as shown in FIG. 4 is used to press and form the housing 1 as shown in FIG.

In FIG. 4, 21 is an upper metal plate of the damping metal plate 20, 22 is a lower metal plate, and 23 is a viscoelastic polymer material. Further, in FIG. 5, reference numeral 24 is a projection formed on the outer peripheral cylindrical portion 16 at a plurality of circumferential positions so as to project radially outward.

As shown in FIG. 4, the vibration-damping metal plate 20 is a laminated composite of a viscoelastic polymer material 23 between two thin metal plates 21 and 22. It is characterized in that shear deformation occurs due to bending deformation and the vibration of the thin metal plates 21 and 22 is attenuated by converting into shear energy. The loss coefficient as a display amount representing the vibration damping capacity of the vibration damping metal plate 20 is 1/10 to 1/100 of that of a general metal, and the amount of vibration transmission is greatly reduced.

When this vibration-damping metal plate 20 is press-molded, since the two laminated metal plates 21 and 22 are displaced from each other, the bending radius needs to be larger than that of a general press. Further, since flange wrinkles are generated, precision is obtained by pressing the skin in the pressing process. Further, in order to suppress the body wrinkles, as shown in FIG. 5, a protrusion 24 is provided on the outer peripheral cylindrical portion 16 to obtain accuracy of the outer diameter of the protrusion 24 used for positioning with the chassis. Thus, the coaxiality between the outer peripheral cylindrical portion 16 and the central cylindrical portion 15 is improved. Further, when the FPC 10 is taken out of the housing 1, the shape of the protrusion 24 can be used to take out the FPC 10 on the flange portion 17. Since the protrusion 24 projects outward from the outer peripheral cylindrical portion 16,
There is no risk that the FPC 10 will contact the motor rotor.

Although the magnetic disk drive spindle motor utilizing the shaft rotating type fluid dynamic pressure bearing has been exemplified in the above embodiment, the present invention is applied to the spindle motor utilizing the shaft fixed type fluid dynamic pressure bearing. Needless to say, the same effect can be obtained.

[0045]

According to the spindle motor for driving a magnetic disk of the present invention, as is clear from the above description, the housing is formed by press working, so that a highly accurate housing can be manufactured inexpensively by mass production. It is possible to provide a spindle motor for driving a magnetic disk with high productivity and at low cost. In addition, since it is a pressed product, burrs can be eliminated by methods such as surface pressing, barrel finishing process etc. are not necessary, and the thickness of the housing is uniform. It is also effective in that it does not contain gas like cast products, and there is no risk of damaging the magnetic disk due to the problem of outgassing.

Further, when an aluminum-based metal plate is used as the material of the housing, the weight can be reduced and the dimension stabilizing treatment such as die casting is unnecessary.

Further, when the vibration-damping metal plate is used, the vibration-proof effect is improved, the vibration of the motor is not transmitted to the chassis, and high vibration resistance can be secured.

By pressing the hole for taking out the flexible printed circuit board, the housing can be processed only once, burrs and dust are not generated, and insulation failure is not generated. The hole may be formed on the bottom surface, but if it is formed on the bottom side bent part of the outer peripheral cylindrical part, the flexible printed circuit board can be taken out of the housing straight and can be attached to the connector part when connecting to the chassis side. No stress.

By forming a hole and a recess in the bottom surface of the housing, the flexible printed circuit board can be taken out without sticking out from the bottom surface of the housing.

[Brief description of drawings]

FIG. 1 is a sectional view of a spindle motor for driving a magnetic disk according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the housing of the embodiment.

FIG. 3 is a partially cutaway perspective view of a housing in a second embodiment of the magnetic disk driving spindle motor of the present invention.

FIG. 4 is a perspective view of a vibration damping metal plate.

FIG. 5 is a perspective view of a housing of a spindle motor for driving a magnetic disk according to a third embodiment of the present invention.

FIG. 6 shows a conventional magnetic disk drive spindle motor, in which (a) is a cross-sectional view and (b) is a bottom view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Rotor hub part 3 Sleeve part 4 Shaft 11 FPC take-out port 12 FPC arrangement concave part 15 Central cylindrical part 16 Peripheral cylindrical part 17 Flange part 20 Damping metal plate

Claims (6)

[Claims] 1. A magnetic disk drive spindle motor in which a bearing is disposed on the inner circumference of a central cylindrical portion of a housing, and a rotor hub portion is supported rotatably with respect to the housing via the bearing. A spindle motor for driving a magnetic disk, characterized by being formed by. 2. The spindle motor for driving a magnetic disk according to claim 1, wherein the material of the housing is an aluminum-based metal plate. 3. The spindle motor for driving a magnetic disk according to claim 1, wherein the material of the housing is a vibration damping metal plate. 4. The spindle motor for driving a magnetic disk according to claim 1, wherein a hole for taking out the flexible printed circuit board is formed in the bottom surface of the housing by press working. 5. The spindle for driving a magnetic disk according to claim 1, wherein a hole for taking out the flexible printed circuit board is formed by press working on a bottom side bent portion of the outer peripheral cylindrical portion continuous with the flange portion of the housing. motor. 6. The housing according to claim 1, wherein a hole for taking out the flexible printed board and a recess for preventing the flexible printed board from protruding from the bottom surface of the housing are formed in the bottom surface of the housing by press working. Spindle motor for magnetic disk drive.