| 摘要 |
PURPOSE:To make it possible to detect a position at which the front end of a cutting tool is aligned with the axis of a spindle, by providing a cutting power meter for delivering a machining force signal in accordance with the cutting force of the cutting tool, and a motor control means for controlling the operation of a servo-motor. CONSTITUTION:When the front end of a cutting tool 33 reaches a position at which it is aligned with the axis of a main spindle 22, the uncut part of a workpiece @ is abruptly decreased, and therefore, the cutting force is also abruptly decreased, resulting in the output voltage of a cutting power meter 32 abruptly decreasing. When the output voltage V is below a reference level S, an output signal from a converter 55a is closed. Then, the count value of a counting circuit 55c is held at a value which indicates the displacement of a transverse table 30 from its original point so that the front end of the cutting tool 33 is aligned with the axis of the spindle 22. A motor control means 50 further drives a servo-motor 34 to move the transverse table 30 so that the front end of the cutting tool 33 exceeds the axis of the spindle 22, and thereafter the machining of the workpiece is stopped. Then, the transverse table 30 is returned to the original point.
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