Patent ID: 7216407

Claim:
A method for processing a screw rotor comprising a step of rotating a blade holder while shifting the blade holder in X-axis, Y-axis, and Z-axis directions to form a screw groove on the outer surface of a rotating cylindrical workpiece with a tool, using a processing apparatus comprising a bed; a C-axis shaft supporter disposed on the bed; a C-axis shaft held by the C-axis shaft supporter, for rotating the cylindrical workpiece; a column disposed on the bed; the blade holder rotatably held by the column; and the tool attached to the blade holder, in which said step to form a screw groove includes a first step of roughly cutting the groove on the other surface of the workpiece using a tool having an end mill and a round end mill, and a second step of shaving the left, right and bottom surfaces of the groove, wherein a shaving bit having two blades set at different angles is used for shaving the left surface and right surface, respectively, and a round bit is used for shaving the bottom surface.