Metal working – Method of mechanical manufacture – Process for making bearing or component thereof
Reexamination Certificate
2001-03-12
2003-03-18
Vidovich, Gregory M. (Department: 3726)
Metal working
Method of mechanical manufacture
Process for making bearing or component thereof
C216S094000, C205S648000, C205S649000, C205S651000, C205S654000, C205S686000
Reexamination Certificate
active
06532662
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a dynamic pressure groove processing method for forming the dynamic pressure groove of a fluid dynamic bearing by electrochemical machining.
In regard to a fluid dynamic bearing having a dynamic pressure groove
101
formed by machining as shown in
FIG. 3B
, if sharp edges
103
and
103
of land portions
102
and
102
located between the dynamic pressure grooves
101
and
101
are brought in contact with the opposite bearing surface (not shown) in an inoperative state, then the bearing surface is damaged, reducing the durability of the bearing. If a surface
102
A of the land portion
102
has a significant surface roughness, then the surface
102
A of the land portion
102
that has the significant surface roughness comes in contact with the bearing surface in the inoperative state, consequently abrading the bearing surface and reducing the durability of the bearing.
In view of the above, if the dynamic pressure groove is formed by electrochemical machining, as shown in
FIG. 3A
, then the corners of land portions
82
located between dynamic pressure grooves
81
come to have a curved surface
83
, eliminating edges. At the same time, surfaces
82
A of the land portions
82
are allowed to have a relatively small surface roughness. Although the abrasion resistance characteristic can be improved with this arrangement, the effects have not been sufficient.
SUMMARY OF THE INVENTION
Accordingly, the present invention has the object of providing a dynamic pressure groove processing method capable of improving the abrasion resistance characteristic of the dynamic pressure groove further than that achieved by the conventional electrochemical machining and sufficiently improving the abrasion resistance characteristic and reliability.
In order to achieve the above object, there is provided a dynamic pressure groove processing method comprising the steps of:
setting an electrode tool having an electrode opposite to a workpiece with interposition of a specified gap and forming a dynamic pressure groove on the workpiece by electrochemical machining; and
setting the electrode tool opposite to the workpiece with interposition of a gap larger than the above gap and electrochemically processing a surface of the workpiece.
According to the present invention, first of all, dynamic pressure grooves are formed in specified regions by electrochemical machining with the electrode of an electrode tool put close to a workpiece in the initial stage. According to this electrochemical machining, corners of land portions adjacent to the dynamic pressure groove can be curved and smoothed.
Next, by subjecting the workpiece to electrochemical machining with the electrode of the electrode tool put away from the workpiece, the land portions are to undergo weak electrochemical machining. By this operation, the surface roughness of the surfaces of the land portions can be reduced, and the curved corners of the land portions can be made smoother at the same time.
Therefore, according to the present invention, the surface roughness of the land portions located between the dynamic pressure grooves can be reduced and smoothed further than in the conventional case, allowing the corners of the land portions to be curved more smoothly. Therefore, the abrasion resistance characteristic of the dynamic pressure groove can be improved further than that achieved by the conventional electrochemical machining, allowing the abrasion resistance characteristic and reliability to be sufficiently improved.
Also, there is provided a dynamic pressure groove processing method for setting an electrode tool having an electrode opposite to a workpiece with interposition of a specified gap and forming a dynamic pressure groove on the workpiece by electrochemical machining, whereby
a surface that belongs to the workpiece and is located within a region opposite to an insulator is electrochemically processed more weakly than a surface that belongs to the workpiece and is located within a region opposite to the electrode by flowing a current through the insulator buried in the electrode, the current being smaller than a current to be flowed through the electrode.
According to the present invention, the workpiece located in the region opposite to the electrode of the electrode tool undergoes strong electrochemical machining to have a dynamic pressure groove formed. At the same time, regions that belong to the workpiece and are located in the regions opposite to insulators (corresponding to the land portions) adjacent to the electrode undergo weak electrochemical machining, by which land portions that have a smooth surface and a smoothly curved corner are formed. Therefore, according to the present invention, the surface roughness of the land portions located between the dynamic pressure grooves can be reduced and smoothed further than in the conventional case, allowing the corners of the land portions to be curved more smoothly.
REFERENCES:
patent: 5628568 (1997-05-01), Takahashi et al.
patent: 6200035 (2001-03-01), Otsuki
patent: 2001/0050235 (2001-12-01), MacLeod et al.
patent: 2002/0126923 (2002-09-01), Usui
patent: 24 37 047 (1976-02-01), None
patent: 2319741 (1998-06-01), None
patent: 56-056342 (1981-05-01), None
patent: 04-053627 (1992-02-01), None
patent: 10-086020 (1998-04-01), None
patent: 10-180545 (1998-07-01), None
patent: 10-217035 (1998-08-01), None
patent: 10-220460 (1998-08-01), None
Fujii Yoshiki
Kobayashi Yasuhiro
Takahashi Takeshi
Compton Eric
Koyo Seiko Co. Ltd.
Nixon & Vanderhye P.C.
Vidovich Gregory M.
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