Aluminum-steel dissimilar robotic arc spot welding with auxiliary insert

Abstract

The authors have developed the novel process for joining dissimilar metals, which uses gas metal arc welding and an auxiliary insert or element. In this process, the element or the flanged steel rivet that has a hollow center is inserted into the pre-hole prepared in an aluminum alloy sheet for the first step. Second, the hollow center is filled with steel weld metal by arc spot welding to join the element and a steel sheet at the fixing point, and thereby the element and the steel sheet are welded strongly enough to fasten the aluminum alloy sheet between the flange of the element and the steel sheet. This new joining process is called element arc spot welding (EASW). EASW has such advantages that it can easily be applied to a dissimilar metal joint with ultra-high-strength steel; it does not need to pinch the joining metals from the upper and lower sides of the joint with a clamping tool; and the resultant shear and peel strengths of the joint are equal to or greater than those by other dissimilar metal joining processes. The prototype robot system for automating the EASW process has also been developed. In this robot system, the position of the pre-hole in the aluminum alloy sheet is detected by an image sensor, and then the tool at the tip of the robot arm moves to the detected pre-hole position to insert the element correctly into the hole; in the next step, low-spatter arc welding is carried out to fasten the aluminum alloy sheet between the element and the steel sheet.