JP2857530B2 - Spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor, and more particularly to a thin spindle motor used for a disk drive or the like.

[0002]

2. Description of the Related Art A disk drive in which an information recording disk (hereinafter, referred to as a medium) such as a 3.5-inch diameter floppy disk is loaded is widely used today as an external storage device of a personal computer or a word processor. In addition, the reduction in thickness and weight has been promoted. FIG.
FIG. 1 is an explanatory view showing a spindle motor used in this type of magnetic disk drive. The spindle motor includes a rotating shaft 2 fitted and supported on an inner ring of a ball bearing 1, a rotor 3, a driving magnet 4 attached to the rotor 3, and a base 5 to which a lower wheel of the ball bearing 1 is fixed. A driving coil 6 is provided, and a force acting on the rotor 3 by a current flowing through the driving coil 6 and a magnetic field of the driving magnet 4 is used to connect the rotor 3 and the rotating shaft 2 to the ball bearing 1.
It is pivoted and rotated.

[0003]

By the way, with this kind of spindle motor, as the drive becomes thinner and lighter, the spindle motor is also required to be thinner and more efficient.
There is an increasing demand for high-efficiency materials such as Nd-Fe-B as a driving magnet material and silicon steel plates as a base material.
However, when the axial type spindle motor is made of the above materials, the attractive force of the driving magnet 4 becomes very large (1.5 to 2.0 kg), and the base 5 made of a silicon steel plate warps as shown in FIG. Would. (0.18
mm) Then, the driving magnet 4 and the driving coil 6 come into contact with each other. Therefore, in order to solve the above problems,
As shown in FIG. 9, the base 5 is warped in the opposite direction in advance in consideration of the warpage of the base 5 due to the attraction of the driving magnet 4 to form a sphere. According to this, when the base 5 is incorporated, the base 5 is flat even if it is attracted and warped by the driving magnet 4, so that the contact between the driving magnet 4 and the driving coil 6 can be prevented. However, in this case, the base 5 is warped in advance by assuming the amount of warpage of the base 5 due to the driving magnet 4. However, when manufacturing the base 5, the silicon steel plate is warped within the elastic limit. After processing, some return deformation occurs, and the return amount varies, and it is difficult to process the base 5 with a predetermined warpage. The base 5 is warped in an arcuate cross-section, and when deformed by the suction of the driving magnet 4, the amount of movement (deformation) becomes greater toward the outer peripheral side of the base 5; The variation in the amount of deformation also increases, and there is a possibility that the surface will not be flat as set after the deformation. Further, when the base 5 expands and contracts due to the heat of the equipment after use, the amount of deformation on the outer peripheral side increases as described above, which also affects the amount of warpage, and the driving magnet 4 and the driving coil 6 come into contact with each other. Was likely to occur. Thus, it was difficult to manage the warpage. In addition, the base 5 having such a reverse warp is formed by performing a punching process and then performing a warping process upon processing.
There were many processing steps and the production was complicated.

The present invention has been made in view of the above-mentioned problems of the prior art, and has been made to solve the problem. The object of the present invention is to facilitate the management of reverse warpage and to reduce the thickness of the device. It is to provide a spindle motor which can be reduced.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a rotor, a driving magnet mounted on the rotor, a driving coil arranged opposite to the driving magnet, and mounting the driving coil. And a spindle motor including a base rotatably supporting the rotor, wherein the base is formed by processing a plurality of annular portions with a step centered on the rotation center of the rotor, and the outer peripheral side thereof includes The base is formed to have a crank shape in cross section so as to be separated from the base, and the built-in base is configured to be flat in a direction of the rotor by the magnetic force of the driving magnet.

[0006]

According to the above means, the base is formed so as to be stepped from its center to the outer peripheral side in a stepwise manner, and the portion processed in the stepped form is plastically deformed. There is no return, and the amount of reverse warpage can be accurately processed. Also, since the base is composed of a plurality of annular flat parts, even if there is a deformation due to heat or the like, it will only expand and contract for each flat part, and even if there is a deformation, the base will be in a flat state. Is maintained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of a spindle motor according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, FIG. 3 is an explanatory view showing the rotor of FIG. 2 removed, and FIGS. FIG. 5 is a longitudinal sectional view of a base before being assembled, and an enlarged sectional view of an annular step portion. FIG. 5 is a longitudinal sectional view showing a modification of the present invention. FIGS. FIG. 7 is a plan view and a front view showing a state in which the base is mounted on the base, and FIG. 7 is an explanatory view showing the relationship between the steps and flat parts of the base and the respective parts in the state shown in FIG.

As shown in these figures, in the spindle motor according to the embodiment, a drive coil 11
Are arranged in the circumferential direction. A rotor 12 is provided so as to cover the drive coil 11, and a drive magnet 13 is fixed inside the outer peripheral wall of the rotor 12. The rotor 12 is fixed to a spindle shaft 15 via a disk mounting table 14, and the spindle shaft 15 is press-fitted inside a ball bearing 16. The rotor 12 and the disk mounting table 14 constitute a rotating body of a spindle motor. A chuck magnet for magnetically chucking a metal hub at the center of the media (not shown), a polyslider for friction reduction, and a positioning of the metal hub are provided on the inner peripheral portion on the top surface side of the rotor 12. A drive pin 17 or the like that fits in the hole and directly drives the medium is integrated. 18 is a substrate 10 on which the drive coil 11 is provided.
Is a FG (frequency power generation) coil, and 28 is an FG magnet. Such a spindle motor generates a torque in the drive magnet 13 by passing a current through the drive coil 11 which is located at a position facing the drive magnet 13 and is arranged in a ring shape, and causes the rotor 12 to rotate the spindle shaft 15. It is designed to be driven to rotate integrally with it.

Next, features of the present invention will be described. FIG.
As shown in the figure, the base 18 constituting the spindle motor processes a plurality of annular steps 19 around the center of rotation of the rotor 12 so as to be stepped, and is further away from the rotor 12 toward its outer peripheral side. The base 18 is formed so as to have a stepped cross section, and the incorporated base 18 is set to be a flat plate warped in the direction of the rotor 12 by the magnetic force of the driving magnet 13. FIGS. 4A and 4B show the base 18A before assembly.
The base 18A is formed, for example, by a single punching and bending process of a silicon steel plate (thickness: 0.5 mm). As shown in FIG. 4B, a plurality of concentric annular steps 19 are formed on the base 18A by plastic deformation, and between the annular steps 19, flat portions 26 are formed. It is formed parallel to the plate material. The step of each annular step 19 is, for example, 0.06 mm in the case of three steps. Therefore, the base 18A is formed in a stepped shape in cross section which becomes lower toward the outer peripheral side. Further, three mounting portions 20, 20, 20 are provided on the outer peripheral portion of the base 18A.
The reference numeral 0 is inclined in advance by, for example, about 30 'so that the base 18A becomes horizontal in a state where the base 18A is assembled (in a state where the base 18A is flattened by suction of the driving magnet 13). The mounting portion 24 on the chassis 23 side extends horizontally in accordance with this. The FG coil 2 is provided on the flat portion 26 of the flat portion 26 inside the driving magnet 13.
7 can be provided.

FIG. 5 shows a modification of the present invention. This modification is different from the above-described embodiment in that the mounting portion 22 on the outer peripheral portion of the base 21 is formed in a horizontal state before being assembled. When the base 21 according to this modified example is assembled, the mounting portion 22 is tilted as shown in FIG.
On the other hand, the mounting portion 25 on the chassis 23 side is inclined and extended in accordance with this.

FIGS. 6 and 7 show a state in which the above embodiment is incorporated in a disk drive.

In the embodiment constructed as described above, the rotor 12, the driving magnet 13 attached to the rotor 12, the driving coil 11 arranged opposite to the driving magnet 13, the driving coil 11 In a spindle motor having a base 18 rotatably supporting the rotor 12 while mounting the same, the base 18 is formed by processing a plurality of annular steps 19 around the center of rotation of the rotor 12 so as to form a step. The side 18 is formed in a stepped cross section so as to be away from the roller 12, and the incorporated base 18 is formed.
The base 18 is formed so as to be warped in the direction of the rotor 12 by the magnetic force of the driving magnet 13 so as to be flat, so that the base 18 is formed so as to be stepped from the center to the outer peripheral side, and the portion processed in the step shape is Since it is plastic deformation, there is no return after processing unlike the conventional processing in elastic deformation, and the amount of reverse warpage can be processed accurately.

The base 18 has a plurality of annular flat portions 2.
Therefore, even if there is a deformation due to heat or the like, only the flat portions 26 are expanded and contracted, and even if there is a deformation, the flat state of the base 18 is maintained.

[0014]

As described above, according to the present invention,
The base is formed by stepping a plurality of annular steps around the center of rotation of the rotor, and is formed in a step shape in cross section so as to be away from the roller toward its outer peripheral side. Since the magnet is made to be flat by warping in the direction of the rotor due to the magnetic force of the magnet, reverse warpage can be easily managed, the thickness can be reduced, and the number of processing steps can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a plan view of FIG.

FIG. 3 is an explanatory view showing the rotor of FIG. 2 with the rotor removed;

FIG. 4 is a longitudinal sectional view of a base before being assembled.

FIG. 5 is a longitudinal sectional view showing a modification of the present invention.

FIG. 6 is an explanatory diagram showing a state where the motor is mounted on a chassis of the disk drive device.

FIG. 7 is an explanatory diagram showing the relationship between the steps and flat portions of the base and each portion in the state of FIG. 6A.

FIG. 8 is a longitudinal sectional view of a conventional spindle motor.

FIG. 9 is a longitudinal sectional view showing a conventional base before being assembled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11 Drive coil 12 Rotor 13 Driving magnet 18, 18A, 21 Base 19 Annular step part 20, 22 Base mounting part 23 Chassis 24, 25 Chassis mounting part 26 Flat part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 21 / 00,29 / 00 H02K 1/06 H02K 5/04

Claims (1)

(57) [Claims] 1. A spindle comprising a rotor, a driving magnet attached to the rotor, a driving coil arranged opposite to the driving magnet, a driving coil mounted, and a base rotatably supporting the rotor. In the motor, the front base is formed by stepping a plurality of annular portions around the center of rotation of the rotor, and is formed into a crank-shaped cross section away from the rotor toward its outer peripheral side, and is incorporated. The spindle motor according to claim 1, wherein the base is formed into a flat shape by warping in a direction of the rotor by a magnetic force of the driving magnet.