Abrading – Precision device or process - or with condition responsive... – Computer controlled
Patent
1996-11-07
1998-04-14
Rose, Robert A.
Abrading
Precision device or process - or with condition responsive...
Computer controlled
451 6, 451 43, 451 44, 451256, B24B 4900
Patent
active
057385637
DESCRIPTION:
BRIEF SUMMARY
FILED OF THE INVENTION
This invention relates to a substrate chamfering machine for chamfering an end face of a substrate used for a hard disc, for instance.
BACKGROUND OF THE INVNETION
A substrate 1 (FIG. 17) used for a hard disc, has its outer and inner edges machined before or after its front and rear surfaces are polished. Specifically, its outer edge 3 is ground and formed with chamfers 4 by the grinding wheel 2 of an inner/outer edge grinding/chamfering machine, as shown in FIG. 17(A). Also, its inner edge 5 is ground and formed with chamfers 4 by the grinding wheel 2, as shown in FIG. 18(B). The chamfers 4 thus formed are necessary for preventing damage to the edges 3 and 5 of the substrate 1.
As shown in FIG. 20(A), the length (or chamfer lengths L and K) of the chamfers 4 of the substrate 1 should be set in a predetermined range, and substrates 1 having chamfer lengths L and K outside this range are discarded.
In the above inner/outer edge grinding/chamfering machine, however, as shown in FIG. 19, a shaft 7 coupling the grinding wheel 2 and a drive motor 6 is subject to axial expansion in proportion to the machining time due to heat generated from the grinding wheel 2 and also from the drive motor 6 during machining. In such a case, the center 8 of the grinding wheel 2 may be deviated from the center 9 of the substrate 1, producing a deviation .DELTA. as shown in FIGS. 20(B) and 21. Thus, the chamfer length L and K is liable to be outside the predetermined range.
Accordingly, during operation of the inner/outer edge grinding/chamfering machine, the operator thereof always measures the chamfer lengths L and K of the substrate 1 having been machined by removing the substrate 1, calculating or determining the deviation .DELTA. of the grinding wheel center 8 from the substrate center 9 from the measured chamfer lengths L and K, and correcting the rate of axial feed (feed in Z directions in FIG. 19) of the grinding wheel 2 utilizing the deviation .DELTA. as a correction amount.
The measurement of the chamfer lengths L and K of the substrate 1 and the correction of the rate of axial feed of the grinding wheel 2 by the operator, is always necessary when starting the machine or when changing stages of the grinding wheel 2 in use. However, the chamfer lengths L and K of the substrate 1 may not be adequately controlled in the event of measurement errors or correction amount calculation errors.
DISCLOSURE OF THE INVNETION
The present invention was made in view of the above affairs, and it has an object of providing a substrate chamfering machine, which permits the chamfer length of chamfers in the outer and inner edge surfaces of the substrate to always be maintained adequately without requiting manual operation.
The invention as set forth in claim 1 provides a substrate chamfering machine for chamfering a substrate edge, and includes a chamfering machine including a grinding wheel for chamfering the substrate edge. A measuring unit successively measures the chamfer length of substrates worked by the chamfering machine, and a measurement data processing unit calculates the correction amount with respect to the feed amount of the grinding wheel according to the measuring result of the measuring unit. In addition, a control unit controls the operation of the chamfering machine and corrects the feed amount of the grinding wheel according to the correction amount from the measurement data processing unit.
Another feature of the invention as set forth in claim 2 resides in the substrate chamfering machine as set forth in claim 1, in which the measuring unit measures the chamfer length from the side of the front or back surface of the substrate.
A further feature of the invention as set forth in claim 3 resides in the substrate chamfering machine as set forth in claim 1 or 2, in which the measuring unit includes a camera for picking up the chamfer length of the substrate. An image processing unit digitally converts an image picked up by the camera and processes the resultant digital data to determine the ch
REFERENCES:
patent: 5295331 (1994-03-01), Honda et al.
patent: 5317836 (1994-06-01), Hasegawa et al.
patent: 5538463 (1996-07-01), Hasegawa et al.
patent: 5609514 (1997-03-01), Yasunaga et al.
patent: 5625446 (1997-04-01), Bedard
Kao Corporation
Nguyen George
Rose Robert A.
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