JPH04265652A - Spindle motor - Google Patents

Abstract

PURPOSE:To support a hub member securely and miniaturize and thin a motor at large and process the hub member using the material without waste. CONSTITUTION:A bracket 2 has a bracket body 6, and an inside cylindrical wall part 8 and an outside cylindrical wall part 10 provided at the bracket body 10, and a hub member 4 has a hub body 14, an axis 18 provided in the hub body 14, a flange part 22, and a pendant cylindrical part extended downward from the flange part 22, and a ball bearing 26 is interposed between this axis 18 and the inside cylindrical wall part 8, and the pendant cylindrical part 24 and the outside cylindrical wall part 10 constitute an air seal structure in cooperation. Moreover, a female screw 20 for fixing the a record disk is made in the hub middle part 4a, and a boss member 40 is screwed freely in mounting and removal in this female screw 20, and finishing processing is performed to the hub middle body 4a, holding the boss member 40.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotationally driving a recording disk such as a magnetic disk.

0002

2. Description of the Related Art Generally, a spindle motor includes a bracket, a hub member rotatable relative to the bracket, and bearing means interposed between the bracket and the hub member. A rotor magnet is attached to the hub member, a stator is attached to a bracket facing the rotor magnet, and a recording disk is attached to the hub member which is rotationally driven in a predetermined direction.

0003

However, this type of spindle motor has the following problems to be solved. First, in recent years, there has been a trend toward smaller and thinner parts, but as the size and thickness become smaller, it becomes difficult to reliably support the hub member in a rotatable manner.

Second, it is necessary to prevent grease and the like from the bearing means from entering the disk chamber, but the structure for this is complicated, and the conventional structure makes it difficult to achieve a smaller and thinner motor. It is difficult to

[0005]Although the hub member in the spindle motor described above has a hub body with one end open, it is difficult to easily process this hub body using conventional processing methods, and when processing, a part of the material is used. Unnecessary sections have been removed.

A first object of the present invention is to provide a spindle motor that can rotatably and reliably support a hub member, and that can also reduce the size and thickness of the entire motor.

[0007] A second object of the present invention is to provide a method for processing a hub member that uses materials without waste and that allows easy processing.

[0008]

[Means for Solving the Problems] In the spindle motor of the present invention, the bracket includes a plate-shaped bracket body, an inner cylindrical wall portion provided on the inner circumference of the bracket body,
The hub member has a hub body with an open bottom, a shaft extending downward from the center of the hub body, and an outer cylindrical wall part provided on the outer periphery of the bracket body. and a hanging cylindrical portion extending downward from the flange portion, the shaft portion extending approximately to the bracket body inside the inner cylindrical wall portion of the bracket, and the inner cylindrical wall portion extending to near the base of the shaft portion. bearing means is interposed between the shaft portion and the inner cylindrical wall portion, and the depending cylindrical portion of the hub member extends to the vicinity of the bracket body inside the outer cylindrical wall portion of the bracket and cooperates with the outer cylindrical wall portion. This creates an air seal structure.

In the method of processing a hub member of the present invention, a female threaded portion for fixing a recording disk is formed on the hub intermediate body, and a boss member is removably screwed into this female threaded portion to hold the boss member to form a hub. Perform finishing processing on the intermediate body.

0010

[Operation] In the spindle motor of the present invention, the shaft portion of the hub member extends approximately to the bracket body inside the inner cylindrical wall portion of the bracket, and the inner cylindrical wall portion extends to near the base of the shaft portion. The radial overlap between the shaft portion and the inner cylindrical wall portion can be made sufficiently large, and the hub member can be reliably supported even when the motor is made smaller and thinner. In addition, the hanging cylindrical part of the hub member extends inside the outer cylindrical wall of the bracket to the vicinity of the bracket body, and cooperates with the outer cylindrical wall to form an air seal structure. There is no need to adopt a new structure, and the motor can be effectively made smaller and thinner.

In the hub member processing method of the present invention,
When finishing the hub member, the boss member is removably screwed into the female thread formed on the hub intermediate body, so the boss member only needs to be chucked with a processing device (for example, a lathe) during processing. Therefore, the material is not wasted and the processing becomes easy.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a spindle motor according to the present invention. In FIG. 1, the illustrated spindle motor includes a bracket 2 and a hub member 4 that is rotatable relative to the bracket 2. The bracket 2 includes a substantially circular bracket body 6, which extends substantially flat. An inner cylindrical wall 8 extending upward is provided on the inner circumference of the bracket main body 6, and an outer cylindrical wall 10 extending upward is provided on the outer periphery thereof. A mounting flange portion 12 extending radially outward is provided on the outer peripheral surface of the outer cylindrical wall portion 10, and the mounting flange portion 12 is attached to a frame (not shown) of a drive device for driving a recording disk. In the embodiment, the upper surface 12a of the mounting flange portion 12 is brought into contact with the lower surface of the frame, and the upper surface 12a is attached to the frame as a reference surface, thereby making the drive device thinner.

The hub member 4 includes a hub body 14 with one end (lower end) open. The hub body 14 has an end wall 16 provided at the other end (upper end), and this end wall 16
A shaft portion 18 extending downward is integrally formed in the central portion of. This hub member 4 has a shaft portion 1 extending through the end wall portion 16.
A female threaded portion 20 extending up to 8 is formed.

An annular flange portion 22 extending radially outward is integrally provided at the lower end of the hub body 14 . The flange portion 22 also includes a hanging cylindrical portion 2 extending downward.
4 are integrally provided. The hub member 4 described above can be formed from a magnetic material such as iron, and it is desirable to process it as described below.

Bearing means is interposed between the bracket 2 and the hub member 4. The illustrated bearing means is comprised of a pair of ball bearings 26, which are disposed between the inner cylindrical wall portion 8 of the bracket 2 and the shaft portion 18 of the hub member 4. The shaft portion 18 is disposed inside the inner cylindrical wall portion 8 of the bracket 2, and its free end extends through the opening formed in the flange body 6 to the vicinity of the outer surface (lower surface) of the bracket body 6. extends to the vicinity of the shaft portion 18 of the hub member 4, that is, to the vicinity of the inner surface of the end wall 16. By configuring like this,
The radial overlapping area between the inner cylindrical wall part 8 and the shaft part 18 is increased, and a pair of ball bearings 26 are provided at both ends of the overlapping area.
(In detail, the base of the inner cylindrical wall portion 8 and the shaft portion 18
One ball bearing 26 is arranged between the free end of the inner cylindrical wall 8 and the shaft 18, and the other ball bearing 26 is arranged between the free end of the inner cylindrical wall 8 and the shaft 18.
), the hub member 4 is rotatably and reliably supported.

An annular rotor magnet 28 is attached to the inner peripheral surface of the hanging cylindrical portion 24 of the hub member 4. Further, a stator 30 is attached to the outer peripheral surface of the inner cylindrical wall portion 8 of the bracket 2 so as to face the rotor magnet 28 . The stator 30 includes a stator core 32 formed by laminating a plurality of plate members and a coil 34 wound around the stator core 32.

A recording disk (not shown), such as a magnetic disk, is mounted on the hub member 4. That is, in the example,
One recording disk is attached to the annular flange portion 22 of the hub member 4.
After placing the recording disk on the upper surface, a fixing screw (not shown) is screwed into the female threaded portion 20 and a clamping member (not shown) is attached, so that the recording disk is placed between the flange portion 22 and the clamping member as required. Clamped as shown.

The embodiment is further configured as follows. The depending cylindrical portion 24 of the hub member 4 extends inside the outer cylindrical wall portion 10 of the bracket 2 along its inner peripheral surface, and the depending cylindrical portion 24 and the outer cylindrical wall portion 10 cooperate with each other to It constitutes a seal structure. In order to provide a desired sealing effect between the two, it is preferable to set the distance between the inner circumferential surface of the outer cylindrical wall portion 10 and the outer circumferential surface of the hanging cylindrical portion 24 to 0.3 mm or less. Further, it is preferable that the radial overlapping length of the outer cylindrical wall portion 10 and the hanging cylindrical portion 24 (the axial length of the overlapping portion thereof) is set to 1.5 mm or more. With this configuration, impurities such as grease scattered from the ball bearing 26 can pass between the two and enter the disk chamber (
The motor can be effectively prevented from entering the chamber in which the recording disk is accommodated, and the entire motor can be made smaller and thinner. Further, as in the embodiment, by arranging the air seal structure at the outer side when viewed in the radial direction, air convergence can be improved and the sealing effect can be further enhanced.

Although the distance between the outer cylindrical wall portion 10 and the hanging cylindrical portion 24 and the length of their overlap can be set as appropriate, in order to more effectively prevent the entry of grease, etc., the above-mentioned It is desirable to set the interval to 1.0 mm or less and the overlapping length between the two to 2.0 mm or more.

The hub member 4 described above can be processed, for example, as follows. Mainly referring to FIG. 2, a hub intermediate body 4a is formed by cutting, for example, a block-shaped member. Next, the end wall portion 16a of this hub intermediate body 4a
A female threaded portion 20 is formed that extends through the shaft portion 18a. Thereafter, the boss member 40 is detachably attached to this female threaded portion 20. The boss member 40 of the embodiment has a cylindrical boss portion 42 at one end and a male threaded portion 44 at the other end, and this male threaded portion 44 is screwed into the female threaded portion 20 of the hub intermediate body 4a. be done. When finishing the hub intermediate body 4a using a processing device such as a lathe, the boss portion 42 of the boss member 40 mounted as described above is held by the chuck, and the hub intermediate body 4a is 4a is finished (for example, cutting is performed on the outer circumferential surface of the shaft portion 18a, the upper surface of the flange portion 22a on which the recording disk is placed, the outer circumferential surface of the hanging cylindrical portion 24a, etc.).

If the boss member 40 is removably screwed onto the hub intermediate body 4a as in this embodiment, there is no need to provide a portion to be held in the processing device, and therefore manufacturing can be carried out without wasting material. Costs can be lowered.

Although one embodiment of the method for processing a spindle motor and a hub member used therein according to the present invention has been described above, the present invention is not limited to these embodiments, and various modifications may be made without departing from the scope of the present invention. It is possible to modify or modify.

[0024]

[Effect of the invention] In the spindle motor of the present invention,
The shaft portion of the hub member extends inside the inner cylindrical wall portion of the bracket to approximately the bracket body, and the inner cylindrical wall portion extends to near the base of the shaft portion, so that the radial direction between the shaft portion and the inner cylindrical wall portion is By making the overlap sufficiently large and therefore arranging the bearing means between the two, the hub member can be reliably supported in a rotatable manner. In addition, the hanging cylindrical part of the hub member extends inside the outer cylindrical wall of the bracket to the vicinity of the bracket body, and cooperates with the outer cylindrical wall to form an air seal structure. There is no need to adopt a new structure, and the motor can be made smaller and thinner.

In the hub member processing method of the present invention,
When finishing the hub member, the boss member is removably screwed onto the internal thread formed on the hub intermediate body, so the boss only needs to be chucked with a processing device (for example, a lathe) during finishing. Therefore, finishing processing can be performed without wasting material, and the processing is also easy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a spindle motor according to the present invention.

FIG. 2 is an explanatory diagram for explaining a method of machining a hub member in the spindle motor of FIG. 1;

[Explanation of symbols]

2 Housing 4, 4
Hub member 6 Hub body 8
Inner cylindrical wall part 10
Outer cylindrical wall portion 14 Hub body 18, 18a Shaft portion 20 Female thread portion 22, 22a
Flange portions 24, 24a Hanging cylindrical portion 26 Ball bearing

Claims (2)

[Claims] 1. A bracket, a hub member rotatable relative to the bracket, a bearing means interposed between the bracket and the hub member, and a rotor magnet attached to the hub member. , a stator mounted on the bracket facing the rotor magnet, and the bracket includes a plate-shaped bracket body and an inner cylindrical wall portion provided on the inner circumference of the bracket body. and an outer cylindrical wall portion provided on the outer periphery of the bracket body, the hub member has a hub body with an open bottom, a shaft portion extending downward from the center of the hub body, and the hub member It has a flange portion provided at the lower end of the main body, and a hanging cylindrical portion extending downward from the flange portion, and the shaft portion extends approximately to the bracket body inside the inner cylindrical wall portion of the bracket. The cylindrical wall extends near the base of the shank, the bearing means is interposed between the shank and the inner cylindrical wall, and the depending cylindrical portion of the hub member extends near the base of the outer cylindrical wall of the bracket. 1. A spindle motor characterized in that the spindle motor extends inside to the vicinity of the bracket body and cooperates with the outer cylindrical wall to form an air seal structure. 2. A method for processing a hub member on which a recording disk is mounted, in which a hub intermediate body having a hub body with one end open and a shaft portion provided at the center of the hub body is formed, and then this hub A female threaded portion for fixing a recording disk is formed on the intermediate body, and then a boss member is removably screwed into the female threaded portion to hold the boss member and finishing processing is performed on the hub intermediate body. Characteristic hub member processing method.