JP2003314538A - Manufacturing method for fluid dynamic bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply form a gap of a thrust bearing at high accuracy. <P>SOLUTION: A bearing sleeve 8 is pushed downward together with a bearing member 2, a lower end face 8c of the bearing sleeve 8 is brought in contact with an upper end face 2b1 of a flange 2b, and a lower end face 2b2 of the flange 2b is simultaneously brought in contact with a spacer T. Thus, the bearing sleeve 8 is fixed on a housing 7. The thickness δ (δ=δ1+δ2) of the spacer T is equivalent to the total amount of a gap (δ1) of a thrust bearing for a first thrust bearing portion and a gap (δ2) of a thrust bearing for a second thrust bearing portion. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a dynamic pressure bearing device which supports a rotary member in a non-contact manner by the dynamic pressure action of lubricating oil generated in a bearing gap. This bearing device is used for information equipment,
For example, magnetic disk devices such as HDD and FDD, CD-R
Optical disk devices such as OM, CD-R / RW, DVD-ROM / RAM, spindle motors such as magneto-optical disk devices such as MD and MO, laser beam printer (LBP)
It is suitable for use as a polygon scanner motor or an electric device, for example, a small motor such as an axial fan.

[0002]

2. Description of the Related Art In addition to high rotation accuracy,
Higher speed, lower cost and lower noise are required.
One of the components that determines the required performance is a bearing that supports the spindle of the motor.In recent years, as a bearing of this type, the use of a dynamic pressure bearing having excellent characteristics in the required performance has been studied, Or actually used.

For example, in a dynamic pressure bearing device incorporated in a spindle motor of a disk device such as an HDD, a radial bearing portion that rotatably supports a shaft member in a radial direction in a non-contact manner, and a shaft bearing member is rotatably supported in a thrust direction. A thrust bearing portion that supports in contact is provided, and as these bearing portions, a dynamic pressure bearing having a groove (dynamic pressure groove) for generating dynamic pressure on the bearing surface is used. The dynamic pressure groove of the radial bearing portion is formed on the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member, and the dynamic pressure groove of the thrust bearing portion uses a shaft member having a flange portion,
It is formed on both end surfaces of the flange portion or on a surface (an end surface of the bearing sleeve, an end surface of a thrust member disposed at the bottom of the housing, etc.) opposed to the flange surface. Usually, the bearing sleeve is fixed in place on the inner circumference of the housing,
Positioning of the bearing sleeve with respect to the housing is often performed using a dedicated jig. Further, in order to prevent the lubricating oil injected into the inner space of the housing from leaking to the outside, a seal member is often arranged in the opening of the housing.

[0004]

The hydrodynamic bearing device having the above-mentioned structure is composed of parts such as a housing, a bearing sleeve, a shaft member, a thrust member, and a seal member, and is required as the performance of information equipment becomes higher and higher. Efforts are being made to improve the processing accuracy and assembly accuracy of each part in order to ensure the high bearing performance that is said. Especially, the size of the thrust bearing gap is
Assembly accuracy such as axial dimension of flange part of shaft member, surface accuracy of both end surfaces, surface accuracy of bearing sleeve and thrust member end surface which are thrust bearing surfaces, and axial space between bearing sleeve and thrust member Since it is affected by accuracy, it is difficult to control the value to a desired value, and for this reason, it is inevitably required to process parts with high accuracy or perform complicated assembly work more than necessary. On the other hand, as the price of information equipment has become lower, demands for cost reduction of this type of dynamic bearing device have become more and more strict.

An object of the present invention is to provide a method capable of easily and accurately setting the thrust bearing gap in this type of dynamic pressure bearing device.

Another object of the present invention is to reduce the manufacturing cost of a dynamic pressure bearing device.

[0007]

In order to solve the above problems, the present invention provides a housing, a bearing sleeve fixed to the inner circumference of the housing, a shaft member having a shaft portion and a flange portion, and a housing fixed to the housing. Provided between the thrust member and the inner peripheral surface of the bearing sleeve and the outer peripheral surface of the shaft portion,
Provided between the radial bearing part that supports the shaft part in the radial direction in a non-contact manner by the dynamic pressure of the lubricating oil generated in the radial bearing gap, and the end face of the bearing sleeve and the end face of the thrust member and the end face of the flange part facing them. And a thrust bearing portion for supporting the flange portion in the thrust direction in a non-contact manner by the dynamic pressure action of the lubricating oil generated in the thrust bearing gap. Provided is a structure in which a spacer having a corresponding thickness is interposed between the surfaces of the members constituting the thrust bearing portion to set the thrust bearing gap to a predetermined size.

For example, when the bearing sleeve is positioned with respect to the housing by a dedicated jig, when the components are finally assembled together, the thrust bearing gap is such that the thrust surfaces (both end surfaces of the flange portion, the bearing sleeve and the thrust surface). It is affected by surface accuracy such as flatness at the end surface of the member.
On the other hand, in the configuration of the present invention, the spacer having a thickness corresponding to the thrust bearing gap is interposed between the thrust faces to set the thrust bearing gap, so that the thrust bearing gap has a surface accuracy of the thrust face. Not affected. Therefore, the thrust bearing gap can be formed easily and accurately. In addition, since it is not necessary to process parts with higher precision or perform complicated assembly work in order to accurately form the thrust bearing gap, it is possible to reduce the manufacturing cost of the dynamic pressure bearing device.

In the above structure, the spacer is, for example,
It can be interposed between the end surface of the thrust member and the end surface of the flange portion facing the end surface.

Further, in the above structure, the spacer is taken out of the housing after setting the thrust bearing gap to a predetermined size. The taken out spacer can be reused, for example, for setting a thrust bearing gap in another dynamic pressure bearing device.

In the above structure, the housing can be made of metal or resin (such as a resin injection molded product). When the housing is made of metal, die-cast products such as aluminum alloys, pressed products such as metal plates (drawing products), machined products of metal materials such as brass (turning products), injection of metal powder A molded product or the like can be used.

Also, as means for fixing the bearing sleeve to the housing, adhesion with epoxy adhesive or the like, press fitting,
Laser beam welding (irradiating the laser beam to the fixed part of the bearing sleeve from the outer diameter side of the housing, or irradiating the laser beam directly to the fixed part of the bearing sleeve), high-frequency pulse bonding, crimping, etc. You can

As means for fixing the thrust member to the housing, adhesion, press-fitting + adhesion, laser beam welding (irradiating the laser beam to the fixed portion of the thrust member from the outer diameter side of the housing. Alternatively, the fixed portion of the thrust member) Directly irradiate the laser beam), high frequency pulse bonding, crimping, etc. can be adopted.

In the above structure, a sealing means for sealing the inner space of the housing can be provided on the other end surface side of the bearing sleeve. This sealing means can be formed by fixing the sealing member to the housing. In this case, as means for fixing the seal member, adhesion with epoxy adhesive or the like, press-fitting, laser beam welding (irradiating the laser beam from the outer diameter side of the housing to the fixed portion of the seal member. Direct laser beam irradiation), high frequency pulse bonding, crimping, etc. can be adopted.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 shows an example of the configuration of a spindle motor for information equipment in which a dynamic pressure bearing device 1 according to this embodiment is incorporated. This spindle motor is used in a disk drive device such as an HDD, and includes a dynamic pressure bearing device 1 that rotatably supports a shaft member 2 in a non-contact manner, a disk hub 3 mounted on the shaft member 2, and a radial direction, for example. And a motor stator 4 and a motor rotor 5 that are opposed to each other through the gap. The stator 4 is attached to the outer circumference of the casing 6, and the rotor 5 is attached to the inner circumference of the disc hub 3. The housing 7 of the hydrodynamic bearing device 1 is mounted on the inner circumference of the casing 6. The disk hub 3 holds one or a plurality of disks D such as magnetic disks. When the stator 4 is energized, the exciting force between the stator 4 and the rotor 5 causes the rotor 5 to rotate, whereby the disk hub 3
And the shaft member 2 rotates integrally.

FIG. 2 shows a hydrodynamic bearing device 1. The hydrodynamic bearing device 1 is composed of a housing 7, a shaft member 2, a bearing sleeve 8, a thrust member 9, and a seal member 10 as constituent parts.

A first radial bearing portion R is provided between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the shaft portion 2a of the shaft member 2.
The first radial bearing portion R2 and the first radial bearing portion R2 are axially separated from each other. Further, a first thrust bearing portion S1 is provided between the lower end surface 8c of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b of the shaft member 2, and the end surface 9a of the thrust member 9 is provided.
The second thrust bearing portion S2 is provided between the lower end surface 2b2 and the flange portion 2b. For convenience of description, the description will proceed with the side of the thrust member 9 as the lower side and the side opposite to the thrust member 9 as the upper side.

The housing 7 is made of a metal material such as brass, for example, and is formed in a cylindrical shape with both ends open.

The shaft member 2 is formed of, for example, a metal material such as stainless steel, and has a shaft portion 2a and a flange portion 2b integrally or separately provided at the lower end of the shaft portion 2a.

The bearing sleeve 8 is made of, for example, a porous body made of a sintered metal, particularly a porous body of a sintered metal containing copper as a main component, and is formed into a cylindrical shape. Adhesion, press-fitting, laser beam welding, and high frequency pulse welding are used. It is fixed to a predetermined position on the inner circumference of the housing 7 by an appropriate means such as.

Bearing sleeve 8 made of this sintered metal
The inner peripheral surface 8a is provided with two upper and lower regions, which are the radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2, axially separated from each other. Herringbone-shaped dynamic pressure grooves 8a1 and 8a2 as shown in FIG. 3 (a) are respectively formed. The dynamic pressure groove may have a spiral shape, an axial groove shape, or the like.

The lower end surface 8c of the bearing sleeve 8 which is the thrust bearing surface of the first thrust bearing portion S1 has a spiral dynamic pressure groove 8 as shown in FIG. 3B, for example.
c1 is formed. As the shape of the dynamic pressure groove, a herringbone shape or a radial groove shape may be adopted.

The thrust member 9 is formed of a metal material such as brass in a disk shape, and is used for adhesion, laser beam welding,
The housing 7 is formed by an appropriate means such as high frequency pulse bonding.
Is fixed to the end face of the lower end of the. Second thrust bearing portion S2
A herringbone-shaped dynamic pressure groove 9a1 as shown in FIG. 4, for example, is formed on the end surface 9a of the thrust member 9 which serves as the thrust bearing surface. The dynamic pressure groove may have a spiral shape, a radial groove shape, or the like.

The seal member 10 is made of, for example, a metal material such as brass in an annular shape, and is fixed to the inner periphery of the opening 7a of the housing 7 by appropriate means such as bonding, press fitting, laser beam welding, and high frequency pulse bonding. To be done. Seal member 10
The inner peripheral surface 10a of the shaft member 2 is an outer peripheral surface 2a1 of the shaft portion 2a of the shaft member 2.
And the seal space (seal gap). Also,
The lower end surface of the seal member 10 contacts the upper end surface 8b of the bearing sleeve 8.

The shaft portion 2a of the shaft member 2 is inserted in the inner peripheral surface 8a of the bearing sleeve 8, and the flange portion 2b is formed in the bearing sleeve 8.
It is housed in the space between the lower end surface 8c and the end surface 9a of the thrust member 9. Lubricating oil is supplied to the internal space of the housing 7 sealed by the seal member 10.

When the shaft member 2 is rotated, the areas of the inner peripheral surface 8a of the bearing sleeve 8 which serve as the radial bearing surfaces (upper and lower two areas) respectively pass through the outer peripheral surface 2a1 of the shaft portion 2a and the radial bearing gap. opposite. Further, the region of the lower end surface 8c of the bearing sleeve 8 serving as the thrust bearing surface is the flange portion 2
The upper end surface 2b1 of b is opposed to the lower end surface 2b2 of the flange portion 2b via the thrust bearing clearance, and the area of the end surface 9a of the thrust member 9 which is the thrust bearing surface is opposed to the lower end surface 2b2 of the flange portion 2b. Then, as the shaft member 2 rotates, a dynamic pressure of the lubricating oil is generated in the radial bearing gap, and the shaft portion 2a of the shaft member 2 is rotated in the radial direction by the oil film of the lubricating oil formed in the radial bearing gap. Freely supported by non-contact. As a result, a first radial bearing portion R1 and a second radial bearing portion R2 that rotatably support the shaft member 2 in the radial direction in a non-contact manner are configured. At the same time, a dynamic pressure of the lubricating oil is generated in the thrust bearing gap, and the flange portion 2b of the shaft member 2 is rotatably supported in both thrust directions in a non-contact manner by the oil film of the lubricating oil formed in the thrust bearing gap. . As a result, the first thrust bearing portion S1 and the second thrust bearing portion S1 which rotatably support the shaft member 2 in the thrust direction in a non-contact manner.
The thrust bearing portion S2 is configured.

This dynamic pressure bearing device 1 is assembled, for example, in the manner as shown in FIGS.

First, as shown in FIG. 5, the thrust member 9 is attached to the end face of the lower end of the housing 7, and the end face 9a thereof is attached.
Attach the spacer T to. The spacer T is formed of, for example, a thin metal plate material or a thin resin sheet material, and has a thickness δ.
Is a dimension corresponding to the total amount of the thrust bearing gap of the first thrust bearing part S1 (the size is δ1) and the thrust bearing gap of the second thrust bearing part S2 (the size is δ2). (Δ = δ1 + δ2). In the figure, the thickness δ of the spacer T is greatly exaggerated.

Next, the bearing sleeve 8 is mounted on the shaft member 2 and inserted into the inner circumference of the housing 7. The bearing sleeve 8 may be press-fitted into the housing 7 on the inner circumference.

Then, as shown in FIG. 6, the bearing sleeve 8 is pushed downward together with the shaft member 2, and the bearing sleeve 8
The lower end surface 8c is brought into contact with the upper end surface 2b1 of the flange portion 2b, and at the same time, the lower end surface 2b2 of the flange portion 2b is brought into contact with the spacer T. Thereby, the spacer T is interposed between the lower end surface 2b2 of the flange portion 2b and the end surface 9a of the thrust member 9. Then, in this state, the bearing sleeve 8 is fixed to the housing 7.

Next, as shown in FIG. 7, the housing 7
The seal member 10 is inserted (or press-fitted) into the inner periphery of the opening 7a of the above, and brought into contact with the upper end surface 8b of the bearing sleeve 8. Then, in this state, the seal member 10 is fixed to the housing 7.

After that, as shown in FIG. 8, the thrust member 9 is once removed from the housing 7, and the spacer T is taken out of the housing 7.

Next, as shown in FIG. 9, the thrust member 9 is reattached to the end face of the lower end of the housing 7 and fixed to this portion. Then, the flange portion 2b has a thickness δ of the spacer T in the axial space formed between the lower end surface 8c of the bearing sleeve 8 and the end surface 9a of the thrust member 9.
And the axial gap δ is the sum of the thrust bearing gap (δ1) of the first thrust bearing portion S1 and the thrust bearing gap (δ2) of the second thrust bearing portion S2. The quantity (δ = δ1 + δ2).

According to the above method, the thrust bearing gap is formed by actually combining the respective components of the dynamic pressure bearing device 1 with the spacer T interposed therebetween, so that the thickness T of the spacer T is δ.
Just by managing (δ = δ1 + δ2), thrust surface (8
c, 9a, 2b1, 2b2) surface accuracy, flange portion 2b
It is possible to easily and accurately form the thrust bearing gap without being affected by the axial dimensional accuracy and the like.

FIG. 10 shows a dynamic pressure bearing device 1'according to another embodiment. This dynamic pressure bearing device 1 ′ differs from the dynamic pressure bearing device 1 shown in FIG. 2 in that the thrust member 9 is fixed to the inner periphery of the lower end portion of the housing 7, and the seal member 10 is the opening portion of the housing 7. It is a point fixed to the end face of 7a.

The dynamic pressure bearing device 31 is assembled, for example, in the manner described below.

First, the seal member 10 is attached to the end surface of the opening 7a of the housing 7. Then, the bearing sleeve 8 is inserted into the inner circumference of the housing 7, the upper end surface 8b thereof is brought into contact with the seal member 10, and further, the shaft member 2 and the spacer T (the same as that used in the above-described embodiment. (Not shown)
Wear and. Next, the thrust member 9 is inserted (or press-fitted) into the inner periphery of the lower end portion of the housing 7, and is pushed toward the bearing sleeve 8 side, so that the upper end surface 2b of the flange portion 2b.
1 is brought into contact with the lower end surface 8c of the bearing sleeve 8, and at the same time, the spacer T is brought into contact with the lower end surface 2b2 of the flange portion 2b and the end surface 9a of the thrust member 9. Then, in this state, the thrust member 9 is fixed to the housing 7.

After that, the seal member 10, the bearing sleeve 8 and the shaft member 2 are once removed, and the spacer T is taken out of the housing 7.

Next, the bearing sleeve 8 is attached to the shaft member 2 and inserted into the inner circumference of the housing 7. The position of the upper end surface 8b of the bearing sleeve 8 is set to the opening 7 of the housing 7.
The bearing sleeve 8 is fixed to the housing at that position, and the seal member 10 is attached to the housing 7.
It is fixed to the end face of the opening 7a. Then, the flange portion 2b is interposed in the axial space formed between the lower end surface 8c of the bearing sleeve 8 and the end surface 9a of the thrust member 9 with an axial gap equal to the thickness δ of the spacer T. Therefore, the axial gap δ is the total amount (δ = δ) of the thrust bearing gap (δ1) of the first thrust bearing portion S1 and the thrust bearing gap (δ2) of the second thrust bearing portion S2.
1 + δ2).

[0041]

According to the present invention, in this type of dynamic pressure bearing device, the thrust bearing gap can be set easily and accurately without being affected by the precision of the parts.

Further, since it is not necessary to process the parts with higher precision than necessary or to perform complicated assembling work in order to form the thrust bearing gap with high accuracy, the manufacturing cost of the dynamic pressure bearing device can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a spindle motor having a dynamic pressure bearing device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a dynamic pressure bearing device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the bearing sleeve {FIG. 3 (a)} and a view showing the lower end surface {FIG. 3 (b)}.

FIG. 4 is a plan view showing an end surface of a thrust member.

5 is a cross-sectional view showing an assembly process of the dynamic pressure bearing device shown in FIG.

FIG. 6 is a cross-sectional view showing an assembly process of the dynamic pressure bearing device shown in FIG.

7 is a cross-sectional view showing an assembly process of the dynamic pressure bearing device shown in FIG.

8 is a cross-sectional view showing an assembly process of the dynamic pressure bearing device shown in FIG.

9 is a cross-sectional view showing an assembly process of the dynamic pressure bearing device shown in FIG.

FIG. 10 is a cross-sectional view showing a dynamic pressure bearing device according to another embodiment of the present invention.

[Explanation of symbols]

1, 1'dynamic bearing device 2 shaft members 2a Shaft 2b Flange part 2b1 Upper end face 2b2 Lower end face 7 housing 8 Bearing sleeve 8a Inner surface 8c Lower end face 9 Thrust member 9a end face 10 Seal member R1 1st radial bearing part R2 2nd radial bearing S1 First thrust bearing part S2 Second thrust bearing part

Claims (3)

[Claims] 1. A housing, a bearing sleeve fixed to an inner circumference of the housing, a shaft member having a shaft portion and a flange portion, a thrust member fixed to the housing, and an inner peripheral surface of the bearing sleeve. A radial bearing portion that is provided between the outer peripheral surface of the shaft portion and non-contactly supports the shaft portion in the radial direction by a dynamic pressure action of lubricating oil generated in a radial bearing gap, an end surface of the bearing sleeve, and the thrust member. And a thrust bearing portion that is provided between the end surface of the flange portion and the end surface of the flange portion that faces them, and that supports the flange portion in the thrust direction in a non-contact manner by the dynamic pressure action of the lubricating oil generated in the thrust bearing gap. A method for manufacturing a pressure bearing device, comprising: a spacer having a thickness corresponding to a thrust bearing gap of the thrust bearing portion; And interposed between, the manufacturing method of the dynamic pressure bearing apparatus characterized by setting the thrust bearing gap to a predetermined size. 2. The method of manufacturing a dynamic pressure bearing device according to claim 1, wherein the spacer is interposed between an end surface of the thrust member and an end surface of the flange portion facing the end surface. 3. The method of manufacturing a dynamic pressure bearing device according to claim 1, wherein the spacer is taken out of the housing after the thrust bearing gap is set to a predetermined dimension.