JPH07322555A - Spindle motor - Google Patents

Abstract

PURPOSE:To prevent the generation of noise from a motor and the contamination of a recording medium due to out gas produced through the use of an adhesive. CONSTITUTION:A recess 2b is made at a part corresponding to an upper bearing 5 at the upper end part of a shaft 2 and a ball, having diameter slightly larger than that of the recess 2b, is press fitted therein thus securing the bearing 5 with the pressure acting radially outward of the ball 8. A recess 2a is made at a part, corresponding to a bracket 1, at the lower end part of the shaft 2 and a ball 4, having diameter slightly larger than that of the recess 2a, is press fitted therein thus fastening the bracket 1 with a pressure acting radially outward of the ball 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor mainly used for rotationally driving a recording disk or the like.

[0002]

2. Description of the Related Art Conventionally, when fixing a bearing, a bracket or the like to a shaft of a spindle motor, a method of fixing them by using an adhesive or a method of fixing them by press fitting has been used.

[0003]

In such a conventional spindle motor, according to the method of fixing each member using an adhesive, outgas generated from the uncured adhesive becomes a problem. If this outgas flows out of the motor and the recording medium is contaminated, it may cause an error when reading / writing information. Further, if the uncured adhesive enters the inside of the bearing, there is a problem that abnormal noise is generated.

The present invention has been made in view of the above problems, and its problem is that the recording medium is contaminated by the outgas generated by the use of the adhesive and the abnormal noise of the motor is generated. It is to provide a spindle motor capable of preventing the above.

[0005]

A shaft, a rotor hub rotatable on the shaft via a pair of bearings, a bracket fixed to the shaft, a stator fixed to the bracket, and a rotor hub mounted on the rotor hub. A spindle motor provided with a rotor magnet facing the stator with a slight gap therebetween, a recess is provided in a portion of the upper end of the shaft corresponding to the upper bearing, and the recess has a diameter larger than that of the recess. A ball having a slightly larger diameter is press-fitted, and the bearing is fixed to the shaft by a pressure acting radially outward of the ball. In addition, a recess is provided in a portion of the lower end of the shaft corresponding to the bracket, and a ball having a diameter slightly larger than the diameter of the recess is press-fitted into the recess, and the shaft acts on the bracket by the pressure acting radially outward of the ball. Conclude

[0006]

In the above spindle motor, the upper bearing and the bracket are fixed by press-fitting the balls in the recesses provided at both ends of the shaft by the pressure applied outward in the radial direction. By not using the adhesive, the problem of contamination of the recording medium due to the outgas generated from the uncured adhesive does not occur.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The same reference numerals as those used above denote the same or corresponding ones.

An embodiment will be described in detail with reference to FIGS. 1 and 2. FIG. 1 shows an embodiment of the spindle motor of the present invention, for example, showing a spindle motor for rotationally driving a magnetic disk. FIG. 2 is a diagram showing a method of assembling the spindle motor of the present invention.

The spindle motor shown in FIGS. 1 and 2 is provided with a shaft 2 planted in a boss portion 1a of a bracket 1 and a rotor hub 3 which is rotatable relative to the shaft 2. . At the lower end of the shaft 2 and the portion corresponding to the boss portion 1a of the bracket 1, a recess 2a is formed.
Is provided. The ball 4 is press-fitted into the recess 2a,
Due to the pressure acting outward in the radial direction, the bracket 1
Is concluded. The rotor hub 3 is supported on the outer side of the shaft 2 via a pair of bearings 5 and 6, and has a ring-shaped projecting portion 3 a for mounting a disk on the lower outer periphery.

The upper bearing 5 interposed between the shaft 2 and the rotor hub 3 is positioned by the step portion 3b provided on the inner peripheral portion of the rotor hub 3. As an assembling method, the shaft 2 is previously fastened and fixed to the bracket 1 as described above. Then, the outer rings of the bearings 5 and 6 are mounted on the rotor hub 3, respectively. In this case, press fitting may be used, as long as the bearings 5 and 6 are held on the rotor hub 3. Next, the rotor hub 3 having the bearings 5 and 6 mounted thereon is fitted into the shaft 2. The inner rings of the bearings 5 and 6 and the shaft 2 may be lightly press-fitted so that they are smoothly inserted.

Then, a weight 7 is placed on the upper surface of the inner ring of the upper bearing 5, and a preload is applied in the axial direction to prevent the bearing from rattling. A through hole 7a is provided at the center of the weight 7, and the shaft 2 corresponds to the through hole 7a. A recess 2b is provided in a portion of the upper end of the shaft 2 corresponding to the upper bearing 5. The ball 8 that has passed through the through hole 7 a of the weight 7 is pressed into the recess 2 b of the shaft 2 by the press rod 9. The upper bearing 5 is fixed while being preloaded in the axial direction by the pressure acting radially outward of the balls 8.

The preload state of the bearings 5 and 6 is a contact action line such as the dotted line shown in the figure. Therefore, as the bearing 5 is fixed,
The bearing 6 is simultaneously fixed by the boss portion 1a of the bracket 1 and the step portion 3b of the rotor hub 3. Conventionally, in such a preload applying step, it took several minutes to complete the curing of the adhesive. However, the above steps can significantly reduce the time and realize the reliable fixing.

The balls 4 and 8 are made of a hard material, such as stainless steel, and the diameter of the balls 4 and 8 is slightly larger than the diameter of the recesses 2a and 2b of the shaft 2, so that the balls 4 and 8 are radially outward. Pressure acts on the upper bearing 5
And the bracket 1 is fixed.

In this embodiment, the inner diameter of the bearing 5 is φ.
Corresponding to 4.995 to φ5 mm, the outer diameter dimension of the shaft 2 is set to an allowable range of φ4.990 to φ4.994 mm. The maximum gap between them is 0.0.
It becomes 1 mm (diameter in the radial direction). The inner diameter of the recess 2b of the shaft 2 is set to φ3.974 to φ3.984m.
m, and the outer diameter of the ball 8 press-fitted into this is φ3.
It was set to 999 to φ4.001 mm. Therefore, the press-fitting margin with the ball 8 is 0.015-0.027 mm (radial dimension)
Therefore, the gap between the shaft 2 and the bearing 5 can be properly fixed.

The above-mentioned dimensional relationship can be applied to the fixing of the shaft 2 and the bracket 1. The outer wall portion 2c forming the recess 2a of the shaft 2
The thickness is preferably about 1 mm in view of the strength of the shaft itself, the degree of fixing the upper bearing 5 and the bracket 1, and the like.

A yoke 10 is provided by caulking on the lower surface of the annular projecting portion 3a, and an annular rotor magnet 11 is mounted on the inner peripheral surface of the yoke 10. The stator 12 is fixed to the outer peripheral portion of the boss portion 1a of the bracket 1 by screwing.
Closely opposed to the inside. The upper portion of the rotor hub 3 is open, and a substantially hat-shaped cap 13 is attached to close the rotor hub 3. The C ring 14 is fixed by being fitted into the upper outer peripheral portion of the cap 13. The cap 13 is a seal cap for preventing grease from the bearings 5 and 6 from scattering into the disk chamber.

Although the embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and corrections can be made without departing from the scope of the present invention. . For example, in the spindle motor of this embodiment, the bearing is a ball bearing, but the bearing is not limited to this, and a sleeve bearing or the like can be freely selected.

[0018]

As described above, in the spindle motor according to the present invention, the upper bearing and the bracket are fixed to each other without using an adhesive, and the balls are press-fitted into the recesses provided at both ends of the shaft, so that the radial direction of the ball is reduced. The upper bearing fixes the bracket with the pressure exerted outward. Since outgassing can be prevented by not using an adhesive,
It is possible to surely prevent the recording medium from being contaminated by the outgas, and prevent the occurrence of an error when reading / writing information. Further, it is possible to prevent the problem that the uncured adhesive enters the inside of the bearing to generate an abnormal sound. Furthermore, in the method of fixing the bearing using the conventional adhesive, it took several minutes to complete the curing of the adhesive.
Since no adhesive is used in the spindle motor of the present invention, the assembly time can be greatly shortened and the fixing can be performed reliably.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a method of assembling a spindle motor according to the present invention.

[Explanation of symbols]

 1 Bracket 2 Shafts 2a, 2b Recessed portion 3 Rotor hub 4,8 Ball 5,6 Bearing 11 Rotor magnet 12 Stator

Claims (2)

[Claims] 1. A shaft, a rotor hub rotatably attached to the shaft through a pair of bearings, a bracket fixed to the shaft, a stator fixed to the bracket, and a rotor hub mounted on the rotor hub. In a spindle motor including rotor magnets facing each other with a slight gap, a recess is provided in a portion of the upper end of the shaft corresponding to the upper bearing, and the recess has a diameter slightly larger than the diameter of the recess. A spindle motor in which a ball is press-fitted and the bearing is fixed to the shaft by a pressure that acts radially outward of the ball. 2. A shaft, a rotor hub rotatably attached to the shaft via a pair of bearings, a bracket fixed to the shaft, a stator fixed to the bracket, and a rotor hub mounted on the rotor hub. In a spindle motor including rotor magnets facing each other with a slight gap, a recess is provided in a portion of the lower end of the shaft corresponding to the bracket, and the recess has a ball slightly larger in diameter than the recess. Spindle motor for press-fitting the shaft and fastening the shaft to the bracket by a pressure that acts radially outward of the ball.