Patent ID: 6847857

Claim:
A thread machining control method for a thread machining apparatus which is provided with a spindle rotating and controlling means for rotating a spindle in accordance with a spindle rotational number command, a detecting means for detecting a position of the spindle, and a feed axis driving and controlling means adapted to determine a movement quantity of a feed axis on the basis of an actual rotational movement quantity of the spindle obtained by the spindle position detecting means and a screw pitch command, and to drive and control the feed axis, and which carries out a thread machining process by the rotation of the spindle and the movement of the feed axis, characterized in that: a relative phase error of the spindle position and feed axis position occurring during the thread machining operation is determined in the spindle position, the movement quantity of the feed axis being determined on the basis of a pseudo spindle position in which a relative phase error quantity is compensated with respect to the spindle position.