Slit laser sensor guided real-time seam tracking arc welding robot system for non-uniform joint gaps

The parts built by pressing and welding have unavoidable large gaps that makes the joining process relatively difficult to perform a sound welded joint. A one-pass weld seam tracking arc welding system that utilizes a robot and laser sensor is developed to perform high quality and high speed joining for thin plate joints in automobile chassis. The laser sensor installed on the welding torch detects the welding position, gap size and relative offset of the joint ahead of welding point. The controller incorporates the feedback data from laser sensor controller and changes the welding position and condition based on the welding condition database already loaded in the controller. Welding speed and amount of metal deposition have also been improved by applying a newly introduced method based on melting part of the edge of a base metal. Moreover, using the tracking function, one is able to track the three-dimensional weld line of the thin plate at higher speed and accuracy. The paper outlines the tracking system, adaptive control of welding process, the principle of high speed joining with increased metal deposition and examples in automotive manufacturing industry.