JPH0518269U - Magnetic disk drive motor - Google Patents

Abstract

(57) [Abstract] [Purpose] The hub 15 and the shaft 1 are constructed with a simple structure.
3 can be fixed with high strength and high rigidity, and the rotation accuracy of the hub 15 can be improved. When the shaft 13 and the hub 15 are crimped, the surface pressure at the crimping portion between the hub 15 side and the shaft 13 side is increased by the coupling means 14 to improve the natural vibration characteristics of the motor.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic disk drive motor for rotating a magnetic disk.

[0002]

[Prior Art]

 A disk drive motor of a commonly used disk drive device has a structure as shown in FIG. 6, for example.

In FIG. 6, a hollow cylindrical bearing holder 2 is integrally erected at a substantially central portion of a frame 1, and a pair of ball bearing rings 3 and 3 are provided in the hollow inside of the bearing holder 2. The shaft 4 is rotatably supported via the shaft. A disc-shaped rotor hub 5 is crimped and fixed to one end portion (upper end portion in the drawing) of the shaft 4. An annular drive magnet 6 is installed on the inner peripheral wall surface of the outer peripheral flange portion 5a of the rotor hub 5. On the other hand, a stator core 7 is fixed to the outer peripheral portion of the bearing holder 2 on the frame 1 side, and the outer peripheral surface of the stator core 7 faces the inner peripheral side of the drive magnet 6. A core winding 8 is loaded on the stator core 7.

A mounting hole 5b is formed at the center of the rotor hub 5 described above, and a fixing screw 9 fitted in the mounting hole 5b is attached to the upper end portion of the shaft 4 in the figure. The rotor hub 5 is connected / fixed by being screwed onto.

[0005]

[Problems to be solved by the device]

 However, in such a conventional hub mounting structure, the rigidity of the coupling portion between the mounting hole 5b of the hub 5 and the shaft 4 is relatively weak, and therefore the natural vibration characteristics required for the motor may not be obtained. In particular, when mounting a magnetic disk on a hub, it is necessary to improve the natural vibration characteristics of the motor because high rotational accuracy is required.

An object of the present invention is to provide a magnetic disk drive motor in which the necessary characteristic vibration characteristics of the motor can be obtained with a simple structure.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a magnetic disk drive motor having a rotary drive system in which a mounting hole provided in a hub for mounting a magnetic disk is crimped to one end of a shaft. It has a structure provided with a coupling means for increasing the surface pressure at the crimping portion between the mounting hole of the hub and the one end of the shaft so that the natural frequency of the rotary drive system exceeds a certain value.

[0008]

[Action]

 In the means having such a structure, when the shaft and the hub are crimped, the surface pressure at the crimping portion between the hub side and the shaft side is increased by the coupling means, and the natural vibration characteristics required Is obtained.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, as shown in FIG. 2, a pair of bearing ball bearings 12, 12 are arranged side by side in the axial direction inside the hollow cylindrical bearing holder 11 provided on the frame side. The shaft 13 is press-fitted and rotatably supported by the pair of ball bearings 12, 12.

At this time, as also shown in FIG. 1, at one end portion (upper end portion in the drawing) of the shaft 13, a collar-shaped fixing body 14 formed as a large-diameter disc-shaped member as a coupling means is integrated. The inner peripheral wall surface of the mounting hole 16 formed in the center of the hub 15 is fitted to the outer peripheral surface of the collar-shaped fixing body 14 by crimping.

A skirt-shaped enlarged flange portion 17 is provided on the lower portion of the hub 15 in the drawing, and an annular drive magnet 18 is installed on the inner peripheral wall surface of the flange portion 17. Has been done. On the other hand, a stator core 19 is fixed to the outer peripheral portion of the bearing holder 11, and the outer peripheral surface of the stator core 19 faces the inner peripheral side of the drive magnet 18. A core winding 21 is loaded on the stator core 19. Further, a magnetic fluid seal 22 is attached to the lower end of the shaft 13 in the figure.

In such an embodiment, when connecting the shaft 13 and the hub 15, the outer peripheral surface of the collar-shaped fixing body 14 as a connecting means provided on the shaft 13 is attached to the hub 15. It is pressed against the inner wall surface of the hole 16. Therefore, the surface pressure at the crimping portion between the shaft 13 and the hub 15 is increased, which improves the natural vibration characteristic of the motor as described below.

That is, as shown in FIG. 3, when a pressure P ₀ is applied to the inner wall of a cylinder having an inner radius r ₀ and an outer radius r ₁ , the circumferential stress σt generated on the inner wall of the cylinder is

[Equation 1] It is represented by. Therefore, the inner wall pressure P ₀ is

[Equation 2] Is.

When the cylinder at this time is regarded as the hub 15, this embodiment corresponds to the case where the inner peripheral radius r ₀ in the above equation is increased. Therefore, the inner wall pressure generated on the inner wall of the hub 15 is It can be seen that P _0, that is, the surface pressure is significantly increased in this embodiment.

Next, in the second embodiment shown in FIG. 4, the outer peripheral portion of the collar-shaped fixed body 24 provided on the shaft 23 is attached to the hub 25 via the ring body 20 as a coupling means. It is fitted in the mounting hole 26. In this case, the hub 25 is made of an aluminum material and the shaft 23 is made of mild steel, while the ring body 20 is made of hard steel such as stainless steel.

In the second embodiment as described above, since the ring body 20 as the coupling means has a high hardness, the surface pressure at the crimping portion between the shaft 23 and the hub 25 is increased. The required natural vibration characteristics are obtained.

Further, in the third embodiment shown in FIG. 5, a step portion is formed in the axial direction on the inner peripheral wall of the mounting hole 36 of the hub 35, and the step portion of the mounting hole 36 is formed. On the other hand, the collar-shaped fixing body 34 of the shaft 33 is fixed so as to abut against it. That is, the stepped portion of the mounting hole 36 has a large-diameter portion 36a provided on the lower side in the figure, a small-diameter portion 36b provided on the upper side in the figure, and a radial direction connecting these portions 36a and 36b. The extending portion 36c is provided. Further, the collar-shaped fixing body 34 provided on the shaft 33 is such that the outer peripheral surface of the collar-shaped fixing body 34 is in contact with the large-diameter portion 36a of the mounting hole 36 and the collar-shaped fixing body of the shaft 33 is fixed. An outer peripheral portion of the upper end surface in the figure of the body 34 is in contact with a radially extending portion 36c of the mounting hole 36.

Also in the third embodiment adopting such a joint structure by abutting, it is possible to obtain the same operation and effect as in the above-mentioned respective embodiments.

[0019]

[Effect of the device]

 As described above, according to the present invention, when the shaft and the hub are crimped, the surface pressure at the crimping portion between the hub side and the shaft side is increased by the coupling means to obtain the natural vibration characteristic required by the rotary drive system. Therefore, with a simple configuration, axial runout of the hub can be prevented and the magnetic disk can be driven well.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view showing a fitted state of a shaft and a hub of a magnetic disk drive motor according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional explanatory view showing the overall structure of a magnetic disk drive motor to which the present invention is applied.

FIG. 3 is a principle plan view for calculating a surface pressure.

FIG. 4 is a partial vertical sectional view corresponding to FIG. 1 showing another embodiment of the present invention.

5 is a partial vertical cross-sectional view corresponding to FIG. 1 showing still another embodiment of the present invention.

FIG. 6 is an explanatory longitudinal sectional view showing an example of a conventional magnetic disk drive motor.

[Explanation of symbols]

 13, 23, 33 Shafts 14, 24a, 34 Coupling means 15, 25, 35 Hubs 16, 26, 36 Mounting holes

Claims (1)

[Scope of utility model registration request] 1. A magnetic disk drive motor including a rotary drive system, wherein a mounting hole provided in a hub for mounting a magnetic disk is crimped to one end of a shaft, and a natural vibration in the rotary drive system. A magnetic disk drive motor comprising coupling means for increasing the surface pressure at the crimping portion between the mounting hole of the hub and the one end of the shaft so that the number exceeds a certain value.