Manufacturing method for bearing member, bearing member, motor and disk drive

Abstract

A sleeve has a thrust dynamic pressure generating groove arrangement for generating a dynamic pressure in a thrust direction between another member and the sleeve. The sleeve is formed in the following manner. First, a mold is prepared which is provided with a portion corresponding to the thrust dynamic pressure generating groove arrangement. Injection molding is carried out by using this mold and material containing binders and metal particulates, thereby forming a work-in-process piece having the thrust dynamic pressure groove arrangement in a cavity of the mold. Then, binders in the work-in-process piece are removed by heating, and thereafter metal particulates in the work-in-process piece are sintered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an internal structure of a disk drive according to a first preferred embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a motor according to the first preferred embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a sleeve according to the first preferred embodiment of the present invention.

FIG. 4 is a bottom view of the sleeve of FIG. 3.

FIG. 5 is an enlarged vertical cross-sectional view of the motor of FIG. 2.

FIG. 6 shows steps in a procedure for manufacturing the sleeve according to the first preferred embodiment of the present invention.

FIG. 7 is a cross-sectional view of a mold used in the first preferred embodiment of the present invention.

FIG. 8 is a cross-sectional view of a work-in-process piece for the sleeve according to the first preferred embodiment of the present invention.

FIGS. 9A, 9B, and 9C show other exemplary molds in the first preferred embodiment of the present invention.

FIG. 10 shows another exemplary sleeve in the first preferred embodiment of the present invention.

FIG. 11 shows an upper end surface of the sleeve of FIG. 10.

FIG. 12 is a vertical cross-sectional view of a motor according to a second preferred embodiment of the present invention.

FIG. 13 is a vertical cross-sectional view of a sleeve according to the second preferred embodiment of the present invention.

FIG. 14 shows an upper end surface of the sleeve of FIG. 13.

FIG. 15 is a cross-sectional view of a mold used in the second preferred embodiment of the present invention.

FIGS. 16A, 16B, and 16C show other exemplary molds in the second preferred embodiment of the present invention.

FIG. 17 is a vertical cross-sectional view of a motor according to a third preferred embodiment of the present invention.

FIG. 18 is a vertical cross-sectional view of a sleeve housing according to the third preferred embodiment of the present invention.

FIG. 19 is a cross-sectional view of a mold used in the third preferred embodiment of the present invention.

FIG. 20 shows another exemplary mold in the third preferred embodiment of the present invention.

FIG. 21 shows another shape of thrust dynamic pressure generating grooves in the third preferred embodiment of the present invention.

Claims

1. A manufacturing method for a bearing member having a thrust dynamic pressure generating groove arrangement which generates a dynamic pressure in a thrust direction between the bearing member and another member, the manufacturing method comprising the steps of: a) preparing a mold provided therein with a portion corresponding to the thrust dynamic pressure generating groove arrangement of the bearing member;b) forming a work-in-process piece for the bearing member in a cavity of the mold by injection molding using a material containing binders and metal particulates having an average particle diameter of 10 μm or less, the work-in-process piece having the thrust dynamic pressure generating groove arrangement;c) removing the binders from the work-in-process piece by heating; andd) sintering the metal particulates in the work-in-process piece to obtain the bearing member having the thrust dynamic pressure generating groove arrangement in which a depth of each groove is 20 μm or less.

2. The manufacturing method as set forth in claim 1, wherein in the step b), the material is infused into the mold from an opening provided on a side of the mold opposite to the portion corresponding to the thrust dynamic pressure generating groove arrangement.

3. The manufacturing method as set forth in claim 2, wherein the bearing member has a hollow cylindrical portion centered on a center axis, andthe opening of the mold is arranged to face a location at an axially end surface of the hollow cylindrical portion near the center axis.

4. The manufacturing method as set forth in claim 1, wherein the bearing member has a hollow cylindrical portion centered on a center axis, andin the step b), the material is infused into the mold from an opening provided in the mold which faces a location at an axial end of the hollow cylindrical portion to be formed, the location being near the center axis.

5. The manufacturing method as set forth in claim 1, wherein the mold has a portion corresponding to a communication hole or groove which adjusts a pressure of fluid in a bearing.

6. The manufacturing method as set forth in claim 1, wherein the bearing member is one of a sleeve and a sleeve housing.

7. An electric motor comprising: a stationary portion;a rotor portion;a bearing having the bearing member as set forth in claim 1 and supporting the rotor portion in a rotatable manner around a center axis relative to the stationary portion; anda driving portion rotating the rotor portion around the center axis relative to the stationary portion.

8. A disk drive for use with a disk-shaped storage medium in which information is storable, comprising: the motor as set forth in claim 7 rotating the disk-shaped storage medium;a head carrying out at least one of reading information from and writing information on the disk-shaped storage medium; anda head moving portion moving the head relative to the disk-shaped storage medium and the motor.

9. A manufacturing method for a bearing member having a communication hole or groove for adjusting a pressure of fluid in a bearing, comprising the steps of: a) preparing a mold provided therein with a portion corresponding to the communication hole or groove,b) forming a work-in-process piece for the bearing member in a cavity of the mold by injection molding using a material containing metal particulates and binders, the work-in-process piece having the communication hole or groove;c) removing the binders from the work-in-process piece by heating; andd) sintering the metal particulates in the work-in-process piece.

10. The manufacturing method as set forth in claim 9, wherein the bearing member includes a thrust dynamic pressure generating groove arrangement which generates a dynamic pressure in a thrust direction between the bearing member and another member,the mold has a first portion corresponding to the thrust dynamic pressure generating groove arrangement and a second portion located on an opposite side to the first portion, andin the step b), the material is infused into the mold from the second portion of the mold.

11. The manufacturing method as set forth in claim 10, wherein the bearing member has a hollow cylindrical portion centered on a center axis, andthe second portion of the mold faces a location at an axial end of the hollow cylindrical portion to be formed, the location being near the center axis.

12. The manufacturing method as set forth in claim 9, wherein the bearing member has a hollow cylindrical portion centered on a center axis, andin the step b), the material is infused into the mold from a portion of the mold facing a location at an axial end of the hollow cylindrical portion, the locating being near the center axis.

13. The manufacturing method as set forth in claim 9, wherein the bearing member is one of a sleeve and a sleeve housing.

14. An electric motor comprising: a stationary portion;a rotor portion;a bearing having the bearing member as set forth in claim 9 and supporting the rotor portion in a rotatable manner around a center axis relative to the stationary portion; anda driving portion rotating the rotor portion around the center axis relative to the stationary portion.

15. A disk drive for use with a disk-shaped recording medium in which information is storable, comprising: the motor as set forth in claim 14 rotating the disk-shaped storage medium; anda head carrying out at least one of reading information from and writing information on the disk-shaped storage medium; anda head moving portion moving the head relative to the disk-shaped storage medium and the motor.