Method of improving synchronisation of motion accuracy of rotary axis and linear axes under a constant feed-speed vector of end-milling point

Abstract

ABSTRACTA five-axis machining centre is noted for its synchronous control capability that makes it feasible to create complicated three-dimensional surfaces such as propellers and hypoid gears quickly. As stated in this research, it is necessary to improve not only the accuracy of the machined shape but also the roughness of the machined surface of free-form surfaces. Therefore, in this study, it is aimed at maintaining the feed-speed vector at the milling point by through controlling two linear axes and a rotary axis to improve the machined surface quality. In addition, a method was suggested for reducing the shape error of machined workpieces by considering the differences in the servo characteristics of the three axes. The shape error was greatly decreased by applying the proposed method of using parameters (referred to as the precedent FF coefficient in this paper) determined by calculation instead of by trial and error. Moreover, to decrease the shape error, even in machining complex shapes that exhibit high angular velocity, the motor load, which is a key factor in the shape error, served as the focus, and a block diagram that considers the motor load was developed. The shape error can be evaluated via the simulation.