High-Frequency beam oscillating to increase the process stability during laser welding with high melt pool dynamics

Abstract

Nd:YAG lasers with a double focus technique are usually used for welding aluminum alloys, due to low melt pool viscosity. For double focus welding, relatively high laser output powers and energy per section are necessary. Thus, techniques for reducing laser power and energy per section for process-safe welding are in demand. Also, when zinc-coated steel sheets with overlap seams are laser welded, improper degassing and weld pool sputtering can occur.This can be avoided by increasing the keyhole size in the welding direction using high-frequency beam oscillation. In this research project, this technology is transferred to laser welding, using adapted optics.Laser welding of aluminum alloys with a high-frequency oscillating beam should lead to high process stability and lower energy per section welding, using much lower output powers, and increasing the spectrum of existing applications.In this project, a processing head is being developed, which will be advantageous for laser welding of zinc-coated steel and aluminum alloys. By increasing the humping limit, higher welding speeds are possible. By oscillating perpendicularly to the feed direction, higher gap bridging is also possible. Further advantages can be expected concerning degassing overlap welds on zinc-coated sheets.