Effect of the cutter path and the workpiece clamping position on the stability of the robotic milling system

Abstract

The milling robots have many advantages compared with the traditional numerical control machine, but the chatter phenomenon in the robotic milling obstructs its popularization. Therefore, the chatter problem in the planar milling by robot is discussed in the way of cutter path and clamping position to give directions for chatter suppression and quality improvement. Firstly, the dynamic behaviour of the robotic milling system is studied by the models of the chatter stability domain analysis, which include robot stiffness model and dynamic milling force model. The mode coupling effect is considered in chatter stability lobe diagram of robotic milling, which is different with the machine tool. Then, the robotic milling experiments are conducted at six different clamping positions relative to robot by two ways of cutter path. Based on the obtained modal parameters under the different milling conditions, the corresponding chatter stability lobe diagrams are plotted. By the comparative analysis about the experiment results, it is found that the surface quality of workpiece with the feed motion of milling tool along the Y-axis direction of robot world coordinate system is better than the X-axis direction and the chatter is more likely to occur in the down milling than in the up milling. Furthermore, a proper workpiece clamping position can availably prevent the chatter in the robotic milling. These conclusions can be references for designing a suitable machining scheme in the robotic milling to ensure the application of robot in the metal cutting.