| 摘要 |
PURPOSE:To reduce resistance on a tap and enable the prevention of the fracture of even a small-sized tap by providing a control means for a digital spindle motor in the tapping control of a machine tool using said motor. CONSTITUTION:Speed instructions 'VS' and 'VZ' depending upon a specified pitch amount are inputted to a position control means 4 and the position control part 12a of a servo circuit 12 from an interpolation circuit 3a as distribution pulses 'PS' and 'PZ'. Also, the position control means 4 makes speed control for a spindle motor 1 on a difference from the feedback pulse 'FS' of a pulse coder 'PC1' via a digital circuit 5 and a power circuit 6. The servo circuit 12 similarly makes synchronous control for a servo motor 2 on the basis of a feedback pulse 'FZ'. When a tap has shifted by a pulse distribution amount (d1) in the aforesaid constitution, both motors 1 and 2 synchronize and the rotation thereof is reversed, according to a reverse rotation instruction. When the tap has returned by (d2), said motors 1 and 2 are caused to give normal rotation again, thereby shifting the tap by d1+d2. Thereafter, a similar fixed cycle is repeated and machining is made up to a predetermined depth.
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