Error identification and compensation for a laser displacement sensor based on on-machine measurement

Faced with many turned parts on a lathe, the profile inspection usually relies on coordinate measuring machine, which is an off-line method and may introduce repositioning or reclamping errors. Then, an accurate and efficient on-machine measuring method of integrating a laser displacement sensor on a numerical control lathe has been proposed, which can inspect the profile of the workpiece without taking it off from the machine tool. Based on the measuring process, a deviation model is constructed after analysis of the error sources. To improve the accuracy of the measurement, the deviations are identified by several other related inspection methods, which are employed to compensate the measured values. Subsequently, an additional experimental test is conducted to verify the effectiveness of the proposed methodology. Results have shown that the positive and negative deviations in the static measurement are +4.4 μm and -2.7 μm, respectively. Then, to improve the measurement efficiency, the dynamic process is adopted, in which the workpiece rotates at the optimized parameters. Although the measuring deviations enlarge to +6.3 μm and -3.1 μm partially, the time consumption is reduced to 10 % to that of the static mode. The confidence interval analysis implies that the probability of 95 % of the authentic values will fall into the calculated intervals.