An accuracy diagnostic device for a machine tool, comprising:
- a change amount detecting unit that detects a magnitude of a change in at least one of a state of a machine tool and a surrounding environment of the machine tool as a change amount;
- a change amount recording unit that records the change amount;
- an accuracy change predictor that predicts a future accuracy change of the machine tool using the change amount recorded in the change amount recording unit;
- an accuracy adjustment timing presenting unit that presents a time point at which an absolute value of an accuracy change predicted from a base time point deviates from an acceptable value as a timing at which an accuracy adjustment is to be required for the machine tool based on the accuracy change predicted by the accuracy change predictor, the base time point and the acceptable value;
- an accuracy recording unit that records a machine accuracy obtained by actually measuring an accuracy of the machine tool together with a measurement date and time;
- and
- an accuracy change predicting formula determining unit that determines an accuracy change predicting formula based on the machine accuracy and the measurement date and time recorded on the accuracy recording unit and the change amount recorded on the change amount recording unit,
- wherein the accuracy change predictor predicts a future accuracy change of the machine tool using the accuracy change predicting formula determined by the accuracy change predicting formula determining unit, and
- wherein (i) the accuracy change predicting formula is formed by including a change amount dependent component that changes by the change amount and an elapsed time dependent component that changes by an elapsed time;
- (ii) a change amount of the change amount dependent component in the accuracy change predicting formula is represented by a formula including a periodic function;
- and (iii) the change amount dependent component in the accuracy change predicting formula is represented as a formula including a function that increases a magnitude of a predicted accuracy change as an elapsed time increases.