Product Code: ICAL05_2006

Distortion Minimisation and Shielding Gas Flow Optimisation in CO2-laser Remote Welding of Steel
Authors:
Claus Thomy, BIAS Bremer Institut fr angewandte Strahltechnik; Bremen Germany
Steffen Neumann, BIAS Bremer Institut fr angewandte Strahltechnik; Bremen Germany
Frank Vollertsen, BIAS Bremer Institut fr angewandte Strahltechnik; Bremen Germany
Thomas Seefeld, BIAS; Bremen Germany
Presented at ICALEO 2005

In CO2-laser remote welding, a laser beam is rapidly deflected by a system of moving mirrors and directed towards the workpiece over distances exceeding 1000 mm. From such an arrangement, various advantages and disadvantages arise.
On the one hand, as the mirror system allows positioning speeds exceeding 700 m/s, positioning times can be nearly neglected. Consequently, it becomes possible to optimize the welding sequence not only in view of cycle time but also in view of distortion. On the other hand, as there is no working head close to the weld, the provision of shielding gas, which is normally required for beam powers exceeding 3 kW, may become a difficult task.
To deal with these topics, at the Bremer Institut fr angewandte Strahltechnik, a CO2-Laser remote welding system with 5 kW maximum beam power was utilized to study both the effect of various shielding gas nozzles on weld quality and the effect of heat input and welding sequence on distortion during stitch welding of one- and two-dimensional steel sheet structures. Moreover, strategies to minimize distortion for a variety of model systems have been developed.