Measurement and analysis of thermo-elastic deviation of five-axis machine tool using dynamic R-test

Thermal errors have a significant impact on machine tool accuracy. Due to their high expense, the conventional shop floors often have poor air conditioning. Even this environmental temperature variation can cause crucial thermo-elastic deviation for precise components. In this paper, a method based on dynamic R-test is presented for the measurement of thermo-elastic deviation of a five-axis machine tool under environmental temperature variation of a conventional shop floor. Due to short measuring time of under 8 minutes, the dynamic R-test enables geometric measurement of a thermal state of the machine tool. The advance in measuring speed is achieved by continuous movement of the machine tool during the measurement procedure. For this purpose, the position of machine axes and measurement data of the sensor are stored synchronously. With a mathematical model, the geometric errors are calculated including all location and orientation errors and important error motions of the five-axis machine tool. The error motions are modelled as a B-spline function of their related axis positions. The measurement is applied repeatedly over three days under environmental temperature variation. The results are presented with the measurement uncertainties and the correlation of the measured errors and temperature.