Thermal displacement estimating method for machine tool and machine tool

A machine tool comprising:

• a cooling device;
• a temperature measurement device;
• a temperature detection unit that detects each temperature of a predetermined heat generating portion and a predetermined main body structure portion by the temperature measurement device;
• and
• a thermal displacement estimating unit that estimates a thermal displacement of the heat generating portion by an estimation model based on a detected temperature, wherein
• the thermal displacement estimating unit is configured to:
• determine a coefficient related to a time response for estimating the thermal displacement from the detected temperature in accordance with a cooling capacity change due to operation control of the cooling device when the machine is in operation;
• obtain a conversion coefficient equivalent temperature change amount equivalent to a change amount of a conversion coefficient before and after the cooling capacity change from a relationship between a predetermined cooling heat amount of the cooling device and the conversion coefficient between the temperature and the displacement for estimating the thermal displacement from the detected temperature and/or a cooling heat amount equivalent temperature change amount equivalent to a changed heat amount before and after the cooling capacity change from a relationship between the predetermined cooling heat amount and a temperature equivalent to the cooling heat amount;
• and
• estimate the thermal displacement of the heat generating portion based on the coefficient and a temperature obtained by adding the conversion coefficient equivalent temperature change amount and/or the cooling heat amount equivalent temperature change amount to the detected temperature.