Electric heating – Metal heating – By arc
Reexamination Certificate
2001-07-02
2003-04-22
Dunn, Tom (Department: 1725)
Electric heating
Metal heating
By arc
C219S121660
Reexamination Certificate
active
06552302
ABSTRACT:
BACKGROUND TECHNOLOGY
A process of manufacturing a magnetic head slider of a magnetic disk drive unit includes the steps of: forming a work piece by cutting a wafer; and abrading or lapping the work piece so as to form a slider having a prescribed shape. By abrading or lapping the-work piece, residual stress in the work piece makes a surface shape of the slider deviate from a desired shape. For example, in the case of forming a disk-side face of the slider into a convex shape, the disk-side face is sometimes formed into a concave shape by the residual stress. The surface shape of the slider is corrected to remove the deformation of the work piece, e.g., crown, camber, twist, and form the desired surface shape.
The surface shape of the slider can be corrected by releasing the residual stress, and the residual stress is released by irradiating a laser beam to form fine grooves in the work piece (see Japanese Patent Gazette No. 6-84312), or mechanically scribing the work piece. The correction of the surface shape of the bar-shaped work piece
10
will be explained with reference to
FIGS. 13-15
. In
FIG. 13
, the work piece
10
is not corrected, and the disk-side shape
12
is formed into a concave shape. As shown in a sectional view of the work piece
10
, a residual stress layer
16
, which is formed by lapping, is formed on a rear face of the work piece
10
, so that the work piece
10
is warped.
In
FIG. 14
, a plurality of fine grooves
18
are formed in the residual stress layer
16
of the rear face by irradiating the laser beam to the rear face of the work piece
10
. By forming the grooves
18
in the residual stress layer
16
, the stress in the residual stress layer
16
is released; the work piece
10
is warped in the opposite direction, as shown in
FIG. 15
, so that the disk-side face
12
can be formed into a desired convex shape.
The method of correcting the surface shape by the fine grooves for releasing the residual stress, which are formed by irradiating the laser beam or mechanically scribing, has following disadvantages.
Namely, dusts are-apt to be made while the fine grooves are formed by irradiating the laser beam or mechanically scribing, and the dusts pollute the surface of the work piece. When the surface shape of the work piece is changed by releasing the residual stress by the fine grooves, fine pieces are sometimes peeled off from the work piece, especially the fine pieces of the work piece are peeled and fall down if the fine grooves are formed and crossed by mechanically scribing.
In the above described method, the surface shape is corrected by releasing the residual stress, so amount of correction is varied on the basis of magnitude of the residual stress, and the surface shape cannot always correct to the desired shape; namely, it is difficult to correct the surface shape with prescribed accuracy. Thickness of the residual stress layer is thin, and its unit is &mgr;m, and curvature can be proportionally adjusted to the thickness of the residual stress layer if the thickness is very thin; the curvature cannot be adjusted if the thickness is thicker than a prescribed value. Since the correction is executed by using the residual stress, the correction can be executed only in the direction of releasing the stress. Therefore, in the conventional method for correcting the surface shape of the slider, the residual stress, which is caused by abrading or lapping the work piece, must be remained in the direction of the correction.
An object of the present invention is to provide a method for correcting the surface shape of the magnetic head slider, which is capable of correcting the outer surface of the magnetic slider to the desired surface shape by correcting the deformation of the work piece, e.g., crown, camber, twist, which is caused by abrading or lapping the work piece, and the magnetic head slider to which said method is applied.
DISCLOSURE OF THE INVENTION
In the present invention, the method for correcting an outer surface of a magnetic slider having a ceramic base to a desired surface shape is characterized in that a laser beam is applied to an outer face of a work piece to partially melt the ceramic base, the melted part is resolidfied, and the surface shape of the slider is corrected to the desired shape by using shrinkage stress during the resolidification.
In the method, a disk-side face of the bar-shaped work piece, which has been cut from a ceramic wafer, may be formed into a convex shape by applying the laser beam to a rear face of the work piece, which is an opposite face to the disk-side face; camber of the bar-shaped work piece, which has been cut from a ceramic wafer, may be corrected by applying the laser beam to the work piece in the direction perpendicular to the direction of the camber; the surface shape of the work piece, which has been formed into the slider piece, may be corrected by applying the laser beam to the work piece.
In the method, the work piece may be held by a cooled jig so as to prevent overheat of the work piece, which is caused by the laser beam; the laser beam may be applied to the work piece in a cool atmosphere so as to prevent overheat of the work piece, which is caused by the laser beam; with these structures, the base can be resolidified in a short time, the surface shape can be efficiently corrected, and heat-destruction of elements can be prevented.
In the method, the surface shape of the work piece, which has been formed into the slider piece, may be corrected by applying the laser beam, which is linearly formed by a cylindrical lens, to the work piece; with this structure, the laser beam need not be scanned, so the correction can be executed in a short time.
Further, the magnetic slider of the present invention, which has a ceramic base and whose surface shape has been corrected to a desired surface shape, is manufactured by the steps of: applying a laser beam to an outer face of a work piece to partially melt the ceramic base; resolidifying the melted part; and correcting the surface shape of the slider to the desired shape by using shrinkage stress during the resolidification.
REFERENCES:
patent: 4910621 (1990-03-01), Matsuda et al.
patent: 4962584 (1990-10-01), Matsuda et al.
patent: 5982583 (1999-11-01), Strom
patent: 6295719 (2001-10-01), Strom
patent: 04-134770 (1992-08-01), None
patent: 05-334643 (1993-12-01), None
patent: 06-084312 (1994-03-01), None
patent: 07-296351 (1995-11-01), None
patent: 10-306363 (1998-11-01), None
patent: 11-328643 (1999-11-01), None
Complete Translation to JP11-328643. Apr. 23, 2002.
Dunn Tom
Fujitsu Limited
Greer Burns & Crain Ltd.
Johnson Jonathan
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