Method and apparatus for compensating thermal displacement of machine tool

An apparatus for compensating thermal displacement of a machine tool, the apparatus comprising:

• a compensation quantity calculating unit configured to calculate a compensation quantity by using temperature data and a predetermined compensation parameter;
• a smoothing filter configured to exponentially smooth the compensation quantity calculated by the compensation quantity calculating unit;
• a scaling unit configured to scale the compensation quantity exponentially smoothed by the smoothing filter;
• a time-dispersion compensating unit configured to calculate a final compensation quantity by time-dispersion compensation for the compensation quantity scaled by the scaling unit according to a time-dispersion compensating period;
• and
• a control unit configured to compensate each axis of equipment according to the final compensation quantity calculated by the time-dispersion compensating unit, in such a manner in which when an error absolute value representing a difference between an input value and an output value of the time-dispersion compensating unit is equal to or larger than a predetermined threshold parameter, the control unit adjusts the time-dispersion compensating period of the time-dispersion compensating unit according to the error absolute value.