Development of an advanced dual beam head for laser lap joining of zinc coated steel sheet without gap at the interface

Abstract

A novel concept for dual beam laser lap joining of Zinc coated steel sheets without intended gap at the interface is presented. This concept utilizes two laser beams with an angle between them. This concept is first proved by combining two laser focusing heads (twin-head system) through use of a custom designed fixture. Welding trials were conducted with a robot by mounting the whole beam delivery set-up at the end of the robot arm. The effects of various welding parameters were studied through both experimental trials as well as modelling of the keyhole geometry. Based on successful concept demonstration, a prototype head was designed and built which enabled the realization of this beam configuration through a single laser source. Excellent quality welds were obtained with both the twin-head system and the new dual-beam head on a variety of zinc-coated sheet combinations.