| 摘要 |
PROBLEM TO BE SOLVED: To grind a substrate for magnetic disks as a work with high accuracy. SOLUTION: A sun gear 12 is rotatably provided concentrically with the center axis O of an internal gear 14, and a lower side grinding wheel 15 is installed in a ring-like lower surface plate body 16a of a lower surface plate 16. On the lower side grinding wheel 15, plural carriers 23 engaged with the sun gear 12 and the internal gear 14 are arranged, and works W are held in holding holes 24 formed in the respective carriers 23. Above the lower surface plate 16, an upper surface plate having the upper grinding wheel formed into the shape of a ring correspondently to the lower grinding wheel 15, is provided, and both surfaces of each work W are ground by the lower side grinding wheel 15 and the upper side grinding wheel. The lower surface plate body 16a is rotatably supported by a cylindrical supporting device through a thrust bearing, and a vertical load on the lower surface plate body 16a is supported on the cylindrical supporting device. |
