JPH09139016A - Rotor of spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable rotor of spindle motor capable of getting precise vertical accuracy and also completely eliminating the wobbling by forming a rotary shaft part and a media center chuck part out of different materials and integrally forming the rotary shaft part and a turntable. SOLUTION: The rotary shaft part 1a and the turntable part 1b are integrally formed in the rotor member 1. Free-cutting materials are utilized for these parts. A hole is formed at the center part of the turntable part 1b, and the media center chuck member 2 consisting of a material like a stainless steel with corrosion resistance and wear resistance is fitted into the hole. A disk-like magnet 3 and a rotor yoke 4 are fixed to the turntable part. The work to integrally form the rotary shaft part and the turntable is facilitated, because only the media center chuck part consists of the different material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor of a spindle motor for rotating a medium such as an optical disk or a magneto-optical disk.

[0002]

2. Description of the Related Art Conventionally used spindle motors for rotating disk media are shown in FIG.
There was something like that shown. Here, FIG. 4 is a sectional view of an essential part of a conventionally used spindle motor.

In the figure, 31 is a shaft, and stainless steel such as SUS is used for the shaft 31 in terms of hardness, corrosion resistance and wear resistance. A turntable 32 for mounting a disk medium is fixed to the upper part of the shaft 31 by a method such as adhesion or press fitting. A disk-shaped magnet 33 is attached to the turntable 32, and a rotor yoke 34 forming a magnetic circuit with the magnet 33 is arranged.

On the other hand, the stator base 35 is provided with a bearing holder 36, and through the bearings 37 and 38 such as ball bearings arranged in the bearing holder 36, the shaft 31 described above is provided.
Is rotatably supported. Further, a plurality of coils 39 are fixed to the stator base 35 with the magnet 33 on the rotor side with a predetermined air gap therebetween.

In the spindle motor constructed in this way, the tip of the shaft 31 protruding from the fixed portion to the turntable 32 constitutes the center chuck 40 of the medium.

[0006]

However, the above-mentioned structure has various problems. That is,
FIG. 5 is a diagram showing the structure of a rotor of a conventional spindle motor, and FIG. 5 (a) is similar to the structure shown in FIG.
1 and the turntable 32 are separately configured and fixed by a method such as bonding, press fitting or shrink fitting. However, in such a case, when the thickness is reduced, the shaft and the turntable are Since the fitting part becomes a little,
Not only could the strength not be maintained, but the vertical accuracy of the shaft and turntable also deteriorated, causing the problem of surface wobbling.

On the other hand, as shown in FIG. 5 (b), if the shaft and the turntable are integrally formed, the above problem can be solved. However, in the case of the integrated type, the machining time becomes longer,
The cost will also increase. Further, when attaching or detaching the media disc, it is necessary to select a hard, corrosion-resistant and wear-resistant material such as SUS for the center chuck part 40, and if the material is processed according to the material, the workability is extremely poor. Will be.

Therefore, the present invention is intended to solve the above problems and to provide a rotor for a spindle motor that is highly accurate and highly reliable while achieving cost reduction.

[0009]

In a rotor of a spindle motor according to the present invention, a turntable for mounting a medium is integrated with a rotary shaft portion, and a media center chuck portion is arranged in the center portion of the turntable. In the rotor of the spindle motor, the rotating shaft portion and the media center chuck portion are made of different materials. Further, it is preferable that the rotary shaft portion is made of a free-cutting material and the media center chuck portion is made of an abrasion resistant material.

[0010]

[Function] Since the rotary shaft portion and the media center chuck portion are not integrally formed but made of different materials, a turntable is integrally formed on the rotary shaft portion and the rotary shaft portion is made of a free-cutting material, and at the same time, the media is formed. If the center chuck part is made of wear-resistant material, the shaft and turntable will not be fixed by press-fitting as in the past, but only the media center chuck part will be made of wear-resistant material. Even when integrally processing the shaft portion and the turntable, the material is not limited to a hard material, and the processing can be facilitated.

[0011]

[First Embodiment] FIG. 1 is a sectional view of a main portion of a spindle motor according to a first embodiment of the present invention. In the figure,
Reference numeral 1 denotes a rotor member, and the rotor member 1 is integrally formed with a rotary shaft portion 1a and a turntable portion 1b. The material is not particularly limited to hardness and the like, and a free-cutting material can be used. It has a wide range of freedom in its selection.

A center chuck member 2 is fitted in a hole formed in the center of the turntable portion 1b of the rotor member 1. This center chuck member 2 is as hard as SUS and hard to be corroded like a conventional shaft.
It is made of wear-resistant material. Further, a disk-shaped magnet 3 is fixed to the turntable portion 1b,
Further, a rotor yoke 4 that forms a magnetic circuit with the magnet 3 is provided.

On the other hand, bearings 7 and 8 such as ball bearings are arranged in the bearing holder 6 of the stator base 5, and the rotary shaft portion 1a of the rotor member 1 is rotatably supported via the bearings 7 and 8. There is. Further, in the stator base 5, a plurality of air-core coils 9 are arranged in the magnet 3 arranged on the rotor member 1 via a predetermined air gap.

The structure of the rotor of the spindle motor as shown in FIG. 2 will be described. As shown in FIG. 1A, as in FIG. 1, the rotary shaft portion 1a is formed in a hollow shape, and the media center chuck portion 2 is formed in the hole of the rotary shaft portion 1a.
Is to be attached.

In addition to this, as shown in FIG. 2B, a groove is formed in a part of the rotary shaft portion 11a of the rotor member 11 in which the rotary shaft portion 11a and the turntable portion 11b are integrally formed. Alternatively, the media center chuck portion 2 may be fitted in this groove.

In the thus constructed rotor member, since the rotary shaft portion and the turntable portion are integrally formed, even if the rotor member is made thin, vertical accuracy can be easily obtained, causing surface wobbling. Nothing.

Further, the shaft and the media center chuck part are not integrally formed but made of different materials, so that if only the media center chuck part is made of a wear-resistant material such as SUS, it is In the integrated processing with the turntable part, the processing can be easily performed because the material can be constituted by a free-cutting material without being particularly limited by the material or the like.

[0018]

[Second Embodiment] FIG. 3 is a sectional view of a main portion of a spindle motor according to a second embodiment of the present invention. First mentioned above
In this embodiment, the rotating shaft portion 1a is attached to the inner races of the ball bearings 7 and 8 to form an inner rotation type structure, but it is also possible to configure the outer rotation type as in this embodiment. Is.

That is, a bearing holder 15a is provided at the center of the stator base 15, and the inner rings of the ball bearings 17 and 18 are mounted on the holder 15a. On the other hand, by mounting the rotating shaft portion 21a of the rotor member 21 on the outer rings of the ball bearings 7 and 8, the rotor member 21 can be rotatably supported.

Even in this case, it is needless to say that the same effect as described above can be obtained by disposing the media center chuck portion made of another material in the center portion of the turntable 21b. In this embodiment, the coreless type spindle motor is described in detail, but the present invention is not limited to this, and a coreless type spindle motor may be used.

[0021]

As described above, according to the present invention, since the rotary shaft portion and the media center chuck portion are not integrally formed but made of different materials, a turntable can be integrally formed on the rotary shaft portion. Since it is not necessary to fix the shaft and the turntable by press fitting or the like as in the conventional case, the vertical accuracy can be accurately obtained even if it is thin, and the problem of surface wobbling can be eliminated.

Moreover, when the rotary shaft portion and the turntable are integrally machined, only the media center chuck portion is made of a wear-resistant material which is a separate member. Since it is not limited to the above, processing can be facilitated and workability is greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a spindle motor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a rotor of the spindle motor of the present invention.

FIG. 3 is a sectional view of a main portion of a spindle motor according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a conventionally used spindle motor.

FIG. 5 is a diagram showing a configuration of a rotor of a conventional spindle motor.

[Explanation of symbols]

 Rotor members 1a, 11a, 21a ... Rotating shaft parts 1b, 11b, 21b ... Turntable part 2 ... Media center chuck part

Claims (2)

[Claims] 1. A rotor of a spindle motor comprising a turntable for mounting a medium integrated with a rotary shaft portion, and a media center chuck portion arranged at the center of the turntable. A rotor for a spindle motor, characterized in that the media center chuck section is made of a different material. 2. The rotor of a spindle motor according to claim 1, wherein the rotary shaft portion is made of a free-cutting material, and the media center chuck portion is made of a wear resistant material.