Development Of Tool Changeable Piezoelectric Dynamometer On Turning

Cutting force is widely used to evaluate the machinability of workpiece and cutting tool, cooling fluid performance as well as machine tool performance. At the same time, it is essential for diagnosing tool failure, investigating and controlling the deformation of machining system. Further, cutting force measurement is a practical method of developing cutting force models, and monitoring cutting condition.Dynamometer is indispensable in cutting force measurement, so optimizing its performance is of great significance.Based on tool type piezoelectric cutting dynamometer designed by Dalian University of Technology, this paper is focused on the design, construction and testing a tool changeable dynamometer, which is simple-structured, reliable, and convenient to maintenance.The natural frequencies of the finished dynamometer were greater than2000Hz at all the three load direction. After assembled and adjusted, the nonlinearly and repeatability error of dynamometer is less than1%, while crosstalk disturbance less than5%.Aimed at solving signal distortion problems founded in cutting test, an orthogonal experiment is designed to find the reasons of he distortion, and then research on relationship between the cutting parameters (cutting speed, feed rate, depth of cut) and the distortion error of the dynamometer. Thermal-structure finite element model of the dynamometer is established to analyze its thermal deformation rule in the cutting process. The results of the analysis, combined with the preload principle of piezoelectric sensor in dynamometer, prove that the main source of test error is temperature field change by cutting heat.Both experimental results and finite element simulation show that the deformation law of elastic ring is in accordance with the law of tool thermal elongation in the whole cutting process. Based on this conclusion, a method to compensate the distortion error by compensation equation in the virtual instrument is proposed, and the general function of cutting test distortion error is deduced. It proves that compensation precision is greater than97%.