The effect of axis coupling on machine tool dynamics determined by tool deviation

Abstract

High acceleration forces of machine tool with kinetic coupling as the dominating coupling forces may deform the machine structure and result in the tool deviation. In this paper, a dynamic model of a three-axis gantry milling machine tool considering axis coupling effects is proposed to model the varying dynamic behavior and evaluate the Tool Center Point (TCP) position deviations. The effect of axis coupling force on the stiffness changes of kinematic joints is analyzed. The variations of the frequencies and frequency response functions with respect to position parameters are calculated. And the TCP deviation affected by axial coupling in real-time motion state is discussed in detail. The results show that it is able to obtain an excellent match between the simulations and the measurements. The simulation and experimental results show that: (1) the natural frequencies and the receptance are greatly changed when the TCP is moving along the X-axis or the Z-axis, where the maximum changing of natural frequencies is up to 10% and response magnitude up to 2 times; (2) the elastic deformation and vibration of machine tool are caused by the coupling forces in acceleration and braking, which detrimentally affect dynamic response of the TCP. Thus, the model proposed in this paper represents the important effects for comprehension of machine dynamic behavior and for further compensation in future.