Stability Analysis of Milling Chatter in Six-Degree-of-Freedom Industrial Robots

Due to the low structural rigidity of six-degree-of-freedom (DOF) industrial robots, the chattering phenomenon is prone to occur under the excitation of periodic milling force, which has an effect on the processing quality of workpieces. In this paper, the influence of milling parameters on the stability of six-DOF robot milling is studied, under the consideration of the mode coupling effect and the regenerative effect on milling stability. First, a mode equation considering both the mode coupling effect and the regenerative effect is developed. Second, based on the fully discrete method, the chatter stability domain model of six-DOF robot (namely, the stability lobe diagram) is established, and the influences of the spindle speed, axial depth of cut, radial depth of cut, and feed rate on the stability of the machining system are analyzed. Finally, the accuracy of the prediction results of the chatter stability domain model is verified by milling experiments.