Generalization of Identification Method of Geometric Deviations for Mixed Type Five-Axis Machining Centres

Abstract

This paper proposes a general method for measuring and identifying the geometric deviations inherent to five axis machining centers with a swivel angular head and a rotary table. The structural configuration of this machine is one of mixed five-axis machining centers. If the inclination angle of C axis is an initial value and its angular deviation is also superimposed on it, the inherent geometric deviations are same as multi-tasking machines, which have ten inherent deviations. The circular motion of simultaneous four-axis control around the tilt C-axis is newly proposed in order to measure the circular trajectories and its eccentricities. The measurement of simultaneous three-axis motion around the B-axis is also required to identify the inherent deviations. In this paper, mathematical relationships between geometric deviations and eccentricities of the trajectories are derived and then the procedure for identifying the deviations using the expressions was clarified through numerical experiments. It is also pointed out that six measurements are needed to identify the inherent deviations when the inclination is zero.