Development of a Grinding Robot for Weld Beads to Create a Free-Form Surface

Abstract

Weld beads, which exist on the corner of an automobile doorframe, must be grinded as if there are no weld beads on it. Grinding task is usually done by skilled workers. This weld bead has joint bumps and welding distortions around the joint area. These bumps and distortions have made it difficult to develop a practicable grinding robot system. We think that grinding task should create a smooth Free-Form surface around the weld bead area, not grinding off the weld beads only. In this paper, we propose a new grinding method, which consists of four distinctive techniques. The first technique is to measure the shape of the weld bead area using a high speed CMM (Coordinate Measuring Machine) . The second technique is to estimate a target Bezier surface based on the measurement data. The third technique focuses on calculating an optimum robot trajectory based on the grinding volume and the grinding belt properties. Finally, with the fourth technique, the robot will be precisely controlled to trace the calculated trajectory. This paper also presents the experimental results of grinding accuracy using this newly developed robot system.