Patent ID: 7809463

Claim:
A machining apparatus for a cylindrical or column-like workpiece having an extending portion extending in an X-axis direction, wherein said extending portion has an arc portion at a root of extension of said extending portion and a diameter of said arc portion is gradually reduced according to a spacing from the root of said extending portion, said machining apparatus comprising: a C-axis driving device to support said workpiece and to rotate said workpiece around a C-axis perpendicular to said X-axis; a cutting tool machining a peripheral profile of said workpiece; an X-axis driving device driving said cutting tool relatively to said workpiece along said X-axis; a Z-axis driving device driving said cutting tool relatively to said workpiece along a Z-axis parallel to said C-axis; and a numerical controller controlling operations of said C-axis driving device, said X-axis driving device and said Z-axis driving device; wherein: said numerical controller controls a rotation of said workpiece around said C-axis, said relative motion of said cutting tool to said workpiece along said X-axis against said relative motion of said cutting tool to said workpiece along said Z-axis to trace an arc profile of said arc portion of said extending portion, and an infeed motion of said cutting tool relative to said workpiece along said X-axis to increase gradually an amount of said infeed motion of said cutting tool to said workpiece along said X-axis in order to machine said arc portion to said arc profile during said rotation of said workpiece around said C-axis and to increase gradually a machining load of said cutting tool in machining.