| 摘要 |
PURPOSE:To polish a workpiece held by a carrier which is driven by an internal gear and a sun gear in the state of a planetary gear, to a set dimension by detecting and operating the position of a lowering upper surface table and the amounts of wear of the upper and lower surface tables. CONSTITUTION:The polishing of a workpiece 16 which is held by a carrier 15 is carried out by upper and lower surface tables 11, 12. The upper surface table 11 is lowered with the progress of the polishing, and its position is always detected by a position sensor 25 and inputted into a control circuit 27 while, at the same time, the transmission and reception of supersonic waves for the upper and lower tables 11, 12 are carried out by means of a transducer 30 and a received signal is inputted into the control circuit 27. Each of the inputted signals is subjected to prescribed signal processing in a sample hold circuit and an A/D converter and, then, arithmetic processing in an operating circuit. The operated result is compared with the set value of the finish of the workpiece in a comparator and the device is stopped when both values agreed. |
