| 摘要 |
PURPOSE:To increase the edge angle of corner sections, suppress the occurrence of chipping, and remove the chipping having occurred by chamfering corner sections before polishing the periphery and performing the additional chamfering on the cross section between the chamfering sections and the end faces. CONSTITUTION:When the corner sections 23, 23 of a work material 20 are brought into contact with the polishing faces 12B, 12B of a polishing groove 12 and polished, chamfering sections 21A, 21A start to be formed, the edge angle, i.e., angle theta1, of the cross section between the chamfering sections 21A, 21A and the periphery is set sufficiently large, thus the occurrence of chipping at the cross section between the chamfering sections and the periphery when the periphery is polished can be thoroughly suppressed. After the periphery 21 and the corner sections 23, 23 of the material 20 is polished by the desired quantity, the material 20 is separated from the polishing groove 12 and brought into contact with the polishing faces 13B, 13B of a polishing groove 13 and polished, other chamfering sections 21B, 21B are formed, the chipping generated at the cross section between the chamfering sections 21A, 21A and the end faces 22, 22 can be removed, and the chipping can be removed because angles theta3, theta4 are larger than 90 deg. and larger than theta5.
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