Measurement of slide error of an ultra-precision diamond turning machine by using a rotating cylinder workpiece

Two measurement methods of using a rotating cylinder workpiece, which are referred to as the one-probe method and the two-probe method, respectively, are proposed for measurement of the horizontal error motion (X-directional error motion) of the Z-slide of an ultra-precision diamond turning machine. In the one-probe method, a displacement probe mounted on the opposite position of the turned (self-cut) cylinder workpiece with respect to the cutting tool is moved by the Z-slide to scan the workpiece being rotated by the spindle with its axis of rotation along the Z-axis. The Z-slide error can be obtained by an averaged output of the probe over one rotation without the influence of the spindle error and the surface form error of the cylinder. In the two-probe method, in addition to the displacement probe used in the one-probe method, another displacement probe is mounted at the position of the cutting tool. The rotating cylinder is scanned along the Z-direction by the two displacement probes simultaneously and the Z-slide error can be accurately measured by using the averaged output of the two probes over one rotation. Both the methods can measure not only the out-of-straightness component of the slide error but also the out-of-parallelism of the Z-slide axis with respect to the spindle axis. Experiments are carried out to verify the feasibility of the proposed methods.