Device for preventing idle rotation in cylindrical ingot grinder

摘要

When a cylindrical single crystal ingot terminating in generally conical parts at the opposite ends thereof is machined with a cylindrical grinder which is adapted to support the ingot in place by fastening the conical parts of the ingot to a spindle side chuck and a tailstock side chuck severally provided with a conical hole and grind and finish the cylindrical part of the ingot while keeping the ingot driven on the spindle side, the ingot is liable to produce idle rotation possibly to the extent of disrupting the grinding work. A device for preventing the ingot from producing this idle rotation is provided which comprises revolution number detecting means adapted to be fastened to the tailstock side chuck and consequently allowed to detect the revolution number thereof, pressing means for pressing the ingot in the axial direction thereof through the medium of the tailstock side chuck, and control means adapted to compare the revolution number of a spindle with the revolution number found by the revolution number detecting means and effect due control of the pressing means when the difference between the two revolution numbers surpasses a prescribed threshold. The due control effected by the control means is utilized additionally or exclusively for the purpose of stopping the driving on the spindle side in one modified embodiment.