The Calibration of Pre-travel Error and Installation Eccentricity Error for On-Machine Probes

Touch-trigger probes are widely used in modern high-precision CNC machine tools as an on-machine inspection solution. The calibration of the probe pre-travel error is a significantly factor affecting the accuracy of the inspection system. However, the existing pre-travel calibration methods either have poor accuracy in practical application or require complicated extra equipments. In this paper, a simple but effective method for measuring the pre-travel error is proposed. With a high-precision standard ring gauge of known size, the center of the ring gauge is obtained by least square method fitting all the measured points. The eccentricity of the probe installation is separated by the reverse method. Then, the probe pre-travel table is established. In order to verify the accuracy of the pre-travel error table and the probe installation eccentricity, the spindle is rotated to touch the same point repeatedly on the high-precision plane. The experimental results show that the proposed novel calibration method can improve the accuracy considerably.