JPH11141540A - Manufacture of bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the remaining of the bubbles in a lubricant by placing a bearing having the lubricant existing in a gap between a bearing surface of a bearing member and an abutment of a shaft member in vacuum, and then placing the same in the atmospheric air. SOLUTION: A recessed part is formed by an upper face of a thrust plate 7 on a bottom face of a base 4, an inner diameter face of a sleeve 6 on a base 4 central part, and an inner diameter face of the base 4, and a lubricant is poured into the recessed part. An upper face of the lubricant is recessed by a bearing member and the surface tension of the lubricant, so that the air easily enters between a flat thrust abutment of a shaft and a free surface of the lubricant, which causes the remaining of the bubbles in the bearing gaps 12, 13 after the assembling. A bearing manufactured by assembling a shaft member in the bearing member 15 is placed in a vacuum tank 11 for degassing the same by making the vacuum tank 11 vacuum by a vacuum pump 14. Then the bearing is taken out from the vacuum tank 11 after the degassing, and an accessory such as a rotor is mounted on the shaft member 17. Whereby the fluctuation of the rocking of a non-rotary synchronous component of the bearing can be prevented, and further the outflow of the lubricating agent can be prevented by inhibiting the expansin of bubbles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to audio / video equipment,
The present invention relates to a method of manufacturing a bearing suitable for a disk drive device such as an information device, particularly a magnetic disk device, and more particularly to a method of manufacturing a bearing for removing air bubbles in a lubricant of the bearing, and particularly to a degassing process during a bearing assembling process. The present invention relates to a method for manufacturing a bearing provided with the above.

[0002]

2. Description of the Related Art Conventionally, in a disk spindle motor, a hub on which a disk is mounted is rotatably supported on a shaft via two ball bearings, and is rotationally driven by the motor.
In particular, in the magnetic disk drive, a high recording density has been developed, and a spindle motor used therein is required to have a small fluctuation of a non-rotational synchronous component.

[0003] Ball bearings have been used in conventional spindle motors. The ball bearing has been required to have a small run-out of a non-rotationally synchronized component (not synchronized with rotation). However, ball passing vibrations and vibrations due to shape errors of the bearing parts occur in the ball bearings, and it is difficult to reduce the runout of the non-rotational synchronous component to a value equal to or less than a predetermined value even if the processing accuracy of the bearing parts is improved. there were.

Accordingly, in recent years, the use of a grooved bearing for generating dynamic pressure as a bearing has been studied. However, even with a grooved bearing for generating dynamic pressure, if the lubricant is properly sealed without mixing of air bubbles in the bearing clearance, the runout of the non-rotational synchronous component of the spindle motor will be small, but air bubbles will remain. In such a case, there is a problem that the runout of the bearing fluctuates with the passage of time.

[0005] When transporting a spindle motor in which air bubbles remain in a bearing by an airplane, the air bubbles may expand when the air pressure is reduced, and the lubricant may flow out of the bearing clearance to the outside.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a bearing in which no air bubbles remain in a lubricant in a bearing clearance.

[0007]

According to the first aspect of the present invention,
A bearing characterized in that a bearing in which a lubricant is present in a bearing clearance between a bearing surface of a bearing member and a bearing surface of a shaft member is arranged in a vacuum, and then the bearing in a vacuum is arranged in the atmosphere. Is provided.

[0008]

Next, the present invention will be described based on a first embodiment. FIG. 1 is an assembled sectional view showing a first embodiment of a spindle motor using a bearing manufactured according to the present invention. 2 to 4 are assembly process diagrams of the spindle motor.
In FIG. 1, a bearing member 15 is a sleeve 6 and a sleeve 6.
And a thrust plate 7 fixed to a bottom surface of the base 4. The bearing surface provided in the concave portion 9 of the bearing member 15 is formed in the inner diameter surface of the sleeve 6 in a cylindrical radial bearing surface 6a provided at two places in the axial direction with a space therebetween.
And a flat thrust bearing surface 7 a provided on the upper surface of the thrust plate 7. The shaft member 17 includes the shaft 1 and a flange 8 fixed to the lower end of the shaft 1. The receiving surface of the shaft member 17 has a radial receiving surface 1c facing the radial bearing surface 6a and a thrust receiving surface facing the thrust bearing surface 7a. 1a.

The bearing clearance between the bearing surface and the receiving surface includes a radial bearing clearance 12 between the radial bearing surface 6a and the radial receiving surface 1c, and a thrust bearing surface 7a and the thrust receiving surface 1c.
a of the thrust bearing. The lubricant exists between the radial bearing clearance and the thrust bearing clearance. Groove 1 for generating dynamic pressure on radial receiving surface 1c
b, and a groove for generating dynamic pressure is provided on the thrust bearing surface 7a.

The hub 2 is fixed to the upper end of the bearing member 15,
The rotor 3 is fixed to the hub 2 via a yoke 19. A stator 5 fixed to the rotor 3 and the base 4
As a planar opposing motor, which faces in a plane in the axial direction,
It acts to suck the shaft member 17 toward the thrust bearing surface 7a which is a thrust bearing. The end surface of the retaining flange 8 attached to the shaft end of the shaft 1 by press fitting is installed so as to be substantially flush with the end surface of the shaft 1, and the thrust receiving surface is flush with the end surface of the shaft 1 and the flange 8. 1
a. With such a structure, the flange 8 can be easily incorporated into the shaft 1.

The assembly process of the spindle motor will be described with reference to FIGS. FIG. 2 is an assembly sectional view of a sub-assembly (a sub-assembly in which the stator 5, the sleeve 6, the thrust plate 7, and the flange 8 are incorporated in the base 4) according to the embodiment of the present invention. First, the sleeve 6 is attached to the base 4 by means such as press fitting. A stator 5 constituting a motor is fixed at a predetermined position on the base 4. Next, the thrust plate 7 having the flange 8 disposed on the upper surface is mounted on the base 4.
Secure to the bottom of. The flange 8 functions to prevent axial movement of the shaft member 17 with respect to the thrust bearing surface 7a during transportation of the bearing. This completes the mounting of the components on the base 4 side of the spindle motor.

The upper surface of the thrust plate 7 attached to the bottom surface of the base 4 and the sleeve 6 attached to the center of the base 4
A concave portion 9 is formed by the inner diameter surface of the base 4 and the inner diameter surface of the base 4. A predetermined amount of a lubricant 10 is injected into the recess 9. FIG. 3 is an assembly sectional view of the first embodiment showing a state in which a lubricant is poured into the concave portion 9. Here, the lubricant 10 is not particularly limited, and may be grease, lubricating oil, or the like.

FIG. 4 is a cross-sectional view of the sub-assembly according to the first embodiment when the shaft 1 is inserted into the recess 9 or the cylindrical hole when the sub-assembly is assembled. The shaft 1 is inserted into the recess 9 from above. The entry of the shaft 1 into the recess 9 causes the already injected lubricant 10 to be pressed by the shaft 1. That is, thrust receiving surface 1
The lubricant 10 in the axial clearance 13 between the shaft a and the thrust bearing surface 7 a is pressed by the shaft 1 entering.

Due to the pressure, the radial bearing clearance 12
Is sent to the lubricant 10. In particular, in the radial bearing clearance 12 between the radial receiving surface 1c and the radial bearing surface 6a, the thrust receiving surface 1a below the radial bearing clearance 12 is provided.
Lubricant 1 in the axial clearance between the bearing and the thrust bearing surface 7a
0 rises along the radial receiving surface 1c and the radial bearing surface 6a, and the lubricant spreads over the entire radial bearing clearance 12. When the shaft 1 is lowered, the axial clearance 13 between the thrust receiving surface 1a and the thrust bearing surface 7a becomes a thrust bearing clearance at an appropriate interval.

In the first embodiment of the present invention, the lubricant 10 is applied to the radial bearing clearance 12 and the thrust bearing clearance.
However, it is possible to feed the lubricant to the bearing clearance by pressing the lubricant in the concave portion with the shaft with respect to the bearing clearance of another type of bearing.

When the lubricant 10 is injected into the recess 9 as shown in FIG. 3, the upper surface of the lubricant 10 becomes concave due to the surface tension of the bearing member 15 and the lubricant 10, and the flat thrust receiving surface 1a of the shaft is Air tends to enter between the free surface of the lubricant 10 and air bubbles and remains in the bearing clearance after the spindle motor is assembled.

A vacuum chamber 11 is used to remove such bubbles. FIG. 5 is a schematic diagram showing the degassing step of the present invention. The deaeration step has a vacuum tank 11 and a vacuum pump 14, but FIG. 5 illustrates other control mechanisms in an abbreviated form for convenience of explanation of the deaeration step. The vacuum chamber 11 is connected to a vacuum pump 14, and the inside of the vacuum chamber 11 can be set to a vacuum state by controlling the vacuum pump.

In the deaeration step, the shaft member 17 is attached to the bearing member 15.
Is disposed at a predetermined position in the vacuum chamber 11, the vacuum pump 14 is operated to evacuate the vacuum chamber 11, and the radial bearing clearance 12 and the thrust bearing clearance up to the bearing clearance of the bearing arranged in the vacuum are lubricated. The air bubbles that have entered the agent 10 are degassed. In the deaeration step, it is necessary to dispose the bearing in a vacuum of 0.5 atm or less in consideration of use at high altitudes, and preferably 0.2 atm or less in consideration of the pressure drop during transportation by air. It is desirable to dispose the bearing in a vacuum to deaerate bubbles in the lubricant.

After the deaeration step, the vacuum state in the vacuum chamber 11 is released, and the bearing is taken out of the vacuum chamber 11. Next, the hub 2 provided with accessory parts such as the rotor 3 is attached to the shaft member 17 by a joining means such as press-fitting or bonding. Thus, the hub 2 is joined to complete the spindle motor shown in FIG.

FIG. 6 is an assembled sectional view of a second embodiment of a spindle motor using a bearing manufactured according to the present invention. The stator 39 fixed to the base 34 radially opposes the rotor 33 fixed to the hub 32 via the yoke 36, and the flat thrust bearing surface 7a is not provided with a groove for generating dynamic pressure. Retaining flange 38
Are formed as flat grooved thrust receiving surfaces 41 and 43 for generating dynamic pressure.
Reference numeral 3 axially faces the thrust bearing surface 7a of the thrust plate and the planar thrust bearing surface 51 provided on the lower end surface of the sleeve 6. In the second embodiment, the axial member 17 has a small axial displacement with respect to the bearing member 15 because both axial side surfaces of the flange 38 constitute a thrust bearing with a dynamic pressure groove. It is not necessary to use the suction force in the axial direction.

In this case, in order to use both side surfaces of the flange 38 as the thrust receiving surfaces 41, 43, it is necessary to secure a perpendicularity between the thrust receiving surfaces 41, 43 and the shaft 31. A flat step 49 perpendicular to the axis is provided between the diameter part 45 and the small diameter part 47 smaller in diameter than the large diameter part 45. As a specific configuration, as shown in FIG. 6, the small diameter portion 47 of the shaft 31 is press-fitted into the center hole of the flange 38 and the flange 38 and the step 49 are brought into contact with each other.
The shaft 31 is fixed to the flange 38. The perpendicularity of the flange 38 to the thrust receiving surfaces 41 and 43 can be ensured. Other configurations of the second embodiment are almost the same as those of the first embodiment. The assembly process of the circumferentially opposed motor of the second embodiment is basically the same as that of the first embodiment.

Further, the embodiment of the present invention is not limited to the structure of the above example. For example, a bearing in which a grooved radial bearing for generating dynamic pressure and a thrust slide bearing supported by a pivot are used. Or a spindle motor using a bearing of a hybrid bearing in which one ball bearing and the other radial bearing with a groove for generating dynamic pressure are combined.

Even in the above-described structure, by providing a deaeration step, residual air bubbles harmful to performance can be discharged from the lubricant in the bearing clearance. In FIG. 1, a method of placing the bearing in the vacuum chamber after assembling the shaft member 17 to the bearing member 15 is adopted. However, the present invention is not limited to this. It is also possible to assemble a spindle motor or a bearing in a vacuum chamber, and then evacuate the vacuum chamber.

Note that the bearing includes a grooved bearing for generating dynamic pressure having a groove for generating dynamic pressure on at least one of the bearing surface and the receiving surface, and the bearing includes a slide bearing. The grooved bearings for generating dynamic pressure include a bearing with a radial dynamic pressure groove, a bearing with a thrust dynamic pressure groove, and the like, and the slide bearings include a radial slide bearing, a thrust slide bearing and the like. The present invention can be implemented in the above bearings.

The bearing surface includes a cylindrical radial bearing surface, a conical surface, a spherical surface and a planar thrust bearing surface, and the like, and the receiving surface includes a cylindrical radial receiving surface, a conical surface, a spherical surface, and a planar thrust bearing surface. There is a thrust receiving surface. By practicing the present invention, it is possible to easily eliminate bubbles of the lubricant that have entered the bearing clearance between the bearing surface and the receiving surface having such a shape.

Further, the content of the present invention has been described with the type in which the cylindrical member is provided with the concave portion 9 of the cylindrical hole. However, the present invention is not particularly limited to the shape of the cylindrical hole, and a bearing clearance capable of holding a lubricant. The present invention can be implemented as long as it has the following.

In the embodiment of the present invention, in the bearing assembling step, a step is provided in which a lubricant remaining in the lubricant in the bearing clearance is degassed in a vacuum chamber that can be evacuated by a vacuum pump after the lubricant is put into the bearing. . By providing the deaeration step in the vacuum chamber in this manner, bubbles remaining in the lubricant in the bearing clearance are eliminated. The retaining flange 38 may not be provided.

[0028]

According to the first aspect of the present invention, it is possible to eliminate the residual bubbles of the lubricant in the bearing clearance, prevent the fluctuation of the non-rotational synchronous component of the bearing, and furthermore, the fluctuation of the air pressure during transportation by an airplane or the like. Therefore, it is possible to eliminate the expansion of bubbles in the lubricant in the bearing, and to obtain a highly reliable bearing capable of preventing the lubricant from flowing out of the bearing clearance.

[Brief description of the drawings]

FIG. 1 is an assembled sectional view showing a first embodiment of a spindle motor using a bearing manufactured according to the present invention.

FIG. 2 is an assembled sectional view of the subassembly according to the first embodiment of the present invention.

FIG. 3 is an assembled sectional view of the first embodiment showing a state in which a lubricant is poured into a concave portion.

FIG. 4 is an assembled sectional view of the subassembly of the first embodiment showing a state where the shaft is inserted into the concave portion.

FIG. 5 is a schematic view showing a degassing step of the present invention.

FIG. 6 is an assembled sectional view of a second embodiment of a spindle motor using a bearing manufactured according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 shaft 1a, 1c receiving surface 2 hub 3 base 6 sleeve 6a, 7a bearing surface 7 thrust plate 8 flange 9 concave portion 10 lubricant 12 bearing clearance 15 bearing member 17 shaft member

Claims (1)

[Claims] A bearing in which a lubricant is present in a bearing clearance between a bearing surface of a bearing member and a bearing surface of a shaft member is placed in a vacuum, and then the bearing in a vacuum is placed in the atmosphere. A method for manufacturing a bearing, characterized in that: