Roundness improvement in taper machining based on two-dimensional active error compensation

Abstract

In this study, an on-line forecasting compensatory control (FCC) strategy is successfully employed to improve the workpiece accuracy in taper machining by compensating the relative two-dimensional motion errors between the workpiece and the cutting tool. The indirect measurement set-up is developed to determine the motion errors, in both radial and longitudinal directions, of the spindle which positions the workpiece via a master taper. Also, the straightness motion errors of the x-y slide are determined to give the actual tool positions. The reference datum in these measurements, i.e. the master form error and the slide profile, can be determined under on-machine conditions and highly accurate precalibrated references are not required. Based on the autoregressive moving average (ARMA) technique, the two-dimensional motion errors are modelled and their future values forecasted and compensated by means of a piezoelectric actuator. The adequate model order and parameters are found by performing off-line simulations. The effectiveness of the FCC strategy is also evaluated by comparing the roundness results with and without compensation. Experimental cutting with FCC reveals that a maximum improvement of 68 per cent and an average improvement of 41 per cent can be achieved for workpiece roundness in this taper machining process.

Harmonic-analysis-based method for separation of form error during evaluation of high-speed spindle radial errors

“…An external master taper is attached to the spindle system and used as a reference in the measurement of error motions of the spindle. 15 This method requires an additional proximity sensor for the measurement of the displacement of the master artifact. A simple technique that is based on the averaging of measured data has been proposed for the evaluation of the spindle error motion.…”