PURPOSE: To enable discrimination of the right and the left, and to discharge chips generated during work automatically, by grinding the external shape of a workpiece and frosting at the same time, in a rolling center of a grinder or a lathe and so on.

CONSTITUTION: A drill 3 is fixed in a drill fixing part 2 of a rolling center's fixing part 1. The fixed drill 3 makes contact with the end face 4 of a workpiece, which rotates when the rolling center moves in the axial direction, by spring force of a helical compression spring 5, and it makes frosting machining thereof. When compressed air is sent to these chips generated during frosting machining from a compressed air intake 6 set at the side part of the rolling center, the compressed air is echausted to the outside passing through the inner space of the rolling center and through a spiral groove out round the drill. The chips are exhausted to the outside on this compressed air.