Patent ID: 8924003

Claim:
A thermal displacement compensation method for a machine tool, the thermal displacement compensation method comprising: setting a position sensor in a detectable position where a position of a movable part of the machine tool is detectable such that the position sensor outputs a signal when the detectable position is reached by the movable part, and previously storing a position where the signal is first output by the position sensor as an initial position; detecting the position where the signal is output by the position sensor as an actual position; calculating a difference between the stored initial position and the detected actual position as a compensation error in the initial position; obtaining a feed shaft thermal displacement amount; modifying the feed shaft thermal displacement amount according to an error compensation rate to obtain a modified feed shaft thermal displacement amount; compensating a position command for a feed axis by adding a thermal displacement compensation amount, which cancels the modified feed shaft thermal displacement amount, to the position command for the feed axis; and updating the error compensation rate based on the compensation error and the modified feed shaft thermal displacement amount corresponding to the initial position.