New finishing system for metallic molds using a hybrid motion/force control

In this paper, a finishing system with a mounted abrasive tool is proposed for polishing of metallic molds. The shape of the mounted abrasive tool is a ball-end type. When a metallic mold with curved surface is polished, not only the orientation of the mounted abrasive tool is fixed but also its revolution is locked. The motion of the mounted abrasive tool is feedforward controlled based on an initial trajectory calculated in advance. The surface is polished by the polishing force which consists of a contact force, motion and viscous friction forces acting between the mold and tool. In this case, the velocities in the normal and tangent directions are delicately regulated so that the polishing force can track the desired value. The effectiveness of the proposed system is proved by experiments using an industrial robot with a PC based controller.