Three-Probe Error Separation with Chromatic Confocal Sensors for Roundness Measurement

In this study, three-probe error separation was developed with three chromatic confocal displacement sensors for roundness measurement. Here, the harmonic suppression is discussed first to set suitable orientation angles among three sensors. Monte Carlo simulation is utilized to test the error separation and optimize the orientation angles and off-axial distance. The experimental setup is established using chromatic confocal sensors with a precise rotary platform. The experimental results show that the measured roundness with an orientation-angle combination of (0°, 90.1°, and 178.6°) is much better than that of another nonoptimal selection (0°, 90.4°, and 177.4°). The roundness error is only 0.7% between the proposed measurement system and an expensive ultraprecision roundness meter. Furthermore, it is proven that the eccentricity distance should be decreased as small as possible to improve the measurement accuracy. In sum, this paper proposes a feasible method for roundness measurement with reliable simulations, easily integrated sensors, and an ordinary precision rotary platform.

Measurement of five-degrees-of-freedom spindle error motion using multi probe error separation

Herein, a precision measurement method is proposed to evaluate the radial, axial, and tilt error motions of rotating devices such as precision spindles. To improve the accuracy of the estimated multiple-degree-of-freedom error motion components, form error signals in the runout signals are separated and precompensated for before the calculation of the five-degrees-of-freedom error motion components. Fourier model-based multi probe error separation (MPES) techniques, which can prevent the occurrence of harmonic distortions, are applied to separate the form error signals. A three-probe method is applied to layers on the side surface of the cylindrical artifact, and a modified two-probe method is developed and applied to the upper surface. The radial, tilt, and axial error motions are calculated using the runout signals that do not contain the separated form error signals. The measurement system uses eight capacitive probes to detect the runout signals of the cylindrical artifact mounted at the center of the rotating device. To compare the proposed method with the five-probe-based conventional measuring method, an evaluation test simulation is conducted repeatedly five times. Results indicate that the proposed MPES method calculated the uncertainty using the deviation between the computed results from the existing and novel methods; additionally, the input signal in terms of the radial, tilt (layers 1 and 2), and axial error motions are [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. It is confirmed that the undesirable effects of the form error signals are successfully removed and that the accuracies of the measured spindle error motion components improve.