ON-MACHINE PROFILE MEASUREMENT OF MACHINED SURFACE USING THE COMBINED3-POINT METHOD

The combined 3-point method, which combines the generalized 3-point me thod with the sequential 3-point method, is described in the present p aper. The combined 3-point method can not only measure profiles that i nclude high-frequency components whose spatial wavelengths are shorter than the probe distance, but also cancel the influence of the z-direc tional error and the pitching error in the scanning motion. In the com bined 3-point method, some data points from a profile evaluated by the generalized 3-point method are chosen as reference points of the stan dard area and are used to determine the relative heights among the dat a groups of the sequential 3-point method. An automatic selection meth od was used to select the standard area correctly and quickly. Theoret ical analyses and computer simulations were performed to confirm the e ffectiveness of the combined 3-point method. Experimental profile meas urements were also carried out using three capacitance-type displaceme nt probes.