| 摘要 |
PURPOSE:To eliminate the production of an inferior article, improve productivity, and obtain a good quality of finished article by filling each hole of a perforated workpiece with a packing material prior to a grinding operation and carrying out a grinding operation in this filled condition. CONSTITUTION:After perforating a workpiece 1 and before carrying out a grinding operation, the perforated holes are filled with packing materials 4 in such a way that the packing materials 4 are at least flush with the end face to be ground and their opening edges are ground in this filled condition and, then, the packing materials 4 are removed. Accordingly, it can be prevented that burrs 3 are produced or a hair like object produced by grinding off the burr 3 enters the hole due to a grinding operation as in the conventional method. Also, the problem of the chipping off of the opening edge of a perforated hole can be settled, eliminating the production of inferior article, improving productivity, and obtaining a good quality of finished article.
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