Free-form surface machining strategy and shape error correction method based on slow tool servo turning

Since the measurement accuracy limits the machining quality of free-form surfaces, compensated machining is challenging in convergent shape errors effectively. Therefore, a free-form surface machining strategy is investigated based on slow tool servo technology and its shape error correction method. An iterative accuracy-adjusted surface matching measurement strategy based on the improved combined CPD and ICP algorithms is proposed, in which the measured surface is aligned with the theoretical surface in the same coordinate system through translational and rotational coordinate transformations to accurately obtain the surface shape error after single-point diamond turning machining for compensation. Finally, the compensation simulation uses the Q-type polynomial free-form surface as the ideal surface. After three compensations, the shape errors of the free-form surfaces converge continuously, in which the shape accuracies of PV and RMS are reduced from 2.01um and 271 nm to 765 nm and 188 nm, respectively. The results show that the effectiveness of the compensation method is verified, and it can improve the machining accuracy effectively.