Research on deformation prediction and error compensation in precision turning of micro-shafts

Abstract

The precision turning process has attracted enormous interest in the standardized and mass production of micro-shafts because it produces more efficiency and lower cost compared with the electrical-discharge machining method and micro-machining method. However, there are many critical factors that influence the dimensional accuracy of micro-shafts, such as the error of workpiece deformation, cutting force, and tool setting error. In this paper, a novel error compensation method was proposed to improve the dimensional accuracy of micro-shafts manufactured with the conventional precision machine tool, based on the constant force cutting method and tool path planning. Firstly, a cutting force model was established considering the effect of the tool nose radius, and the finite element method was used to simulate the turning process and predict the workpiece deformation. Secondly, an error analysis model was created by taking tool setting error, workpiece deformation error, and multi-process cumulative error into account, and the optimized tool path and cutting parameters were obtained. Finally, a series of turning experiments were carried out to verify the error compensation strategy and the cutting force model. The results show that the dimensional error of the micro-shafts with a large length-diameter ratio (l = 5 mm, d = 0.4 mm) can be reduced by 90% by means of the proposed error compensation strategy. In addition, the maximum prediction error of cutting forces is less than 8.6%, and the effect of cutting parameters on cutting forces can be concluded as “feed rate > depth of cut > spindle speed.”