Patent attributes
After a thermal displacement correcting program has started, a temperature is measured with a temperature sensor in S1, then when a rotational speed of a spindle is changed during the measurement (S2), a counter starts (S3). Then in S4, from a preset relationship between the rotational speed of the spindle and a setting-equivalent heat value, a correction factor that is a difference in setting-equivalent heat value between before and after the change in rotational speed of the spindle is calculated. Subsequently, in S5, a temperature-equivalent heat value is calculated, and then in S6, a compensation amount is calculated from the correction factor and a time elapsed after the change in rotational speed of the spindle. In S7, an equivalent heat value for compensating a dead time is obtained based on the sum of them S8, an estimated calculation for thermal displacement conversion is performed, and a correction process by an NC unit is performed in S9.
