| 摘要 |
The position of a feed shaft is monitored, the mean moving speed and moving frequency of the feed shaft are measured with every unit time for position correction, and a correction amount delta n is determined from the speed and frequency according to an approximation formula and updated (c7 and c8). A position correction amount for a commanded position is determined from this correction amount, and the commanded position is corrected by the position correction amount (c1 to c6). The position correction amount for the commanded position is determined from this correction amount, and the commanded position is corrected by this position correction amount. Since the correction amount is determined according to the approximation formula, thermal displacement correction can be effected at all times without requiring any sensor. When the correction amount changes substantially (c10), the thermal displacement is measured by means of a sensor and used as the correction amount (c11 and c12), whereby accuracy is improved. The frequency of measurement by means of sensors is reduced, so that the machining time can be reduced. <IMAGE> |
