MACHINING METHOD FOR CURVED SURFACE

PURPOSE:To reduce machining time by moving a displacement sensor in two dimensional directions with respect to a workpiece based on a curved surface machining data and carrying out machining from where the signal of the displacement sensor is the largest based on the curved surface machining data. CONSTITUTION:A roughly machined workpiece W is installed on a chuck 11 and a tool rest 20 is rotted in its original position to index a displacement sensor 22 in a position corresponding to the workpiece W. Then, based on the curved surface machining data Xn, Zn inputted from a control panel 40 with CRT into a memory 34 via a CPU 33 to machine the workpiece W into a curved surface, the tool rest 20 and a headstock 10 are rapidly traversed. And, by reading a position where the maximum signal bmax is issued in a position where the displacement sensor 22 does not interfere with the workpiece, W, the tool test 20 and the headstock 10 are moved in this position to start machining based on the curved surface machining data Xn, Zn. Accordingly, an idle turning time can be reduced reducing machining time.