Roundness and spindle error measurement by angular three-probe method (1st report)

This paper presents a new error separation method for roundness and spindle error measurement, which is called the angular three-probe method. Three two-dimensional angle probes are employed in this method. The two-dimensional surface local slopes of the cylindrical workpiece, the radial error motion and angular error motion of the spindle, which are included in the output of each probe, can be separated from each other using the two-dimensional outputs of probes. Comparing with the conventional displacement three-probe method, the angular three-probe method is more suitable for detecting the multi-degrece-of-freedom components of spindle error and roundnesś. In this paper, the measurement of roundness is discussed in detail theoretically and experimentally. An in situ self-calibration method, which does not require extra angle references, is proposed to calibrate the angle probes. Experimental results have indicated that the roundness can be measured with a repeatability of approximately 0.04μm. Comparison of roundness measurement with the displacement three-probe method has also been conducted.