| 摘要 |
A lower polishing disk is divided into inner and outer disks, and a holding portion for rollably holding a ball is formed with the outer circumferential portion of the inner disk and the inner circumferential portion of the outer polishing disk. The ball held by the holding portion is pushed by the upper polishing disk with a predetermined load. When the inner disk, outer disk, and upper polishing disk are driven in this state, the ball is polished.
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