Product Code: ICAL09_1803

Short Focal Length Scanner,Fiber Laser Welding Of Stainless Steel Sheets And Tubular Products
Authors:
Mikko Vänskä, Lappeenranta University of Technology / Outokumpu Stainless Tubular Products Oy Ab; Pietarsaari Finland
Veli Kujanpää, Lappeenranta University of Technology / VTT Industrial Systems; Lappeenranta Finland
Elin Westin, Outokumpu Stainless Ab, Avesta Research Center; Avesta Sweden
Terho Torvinen, Outokumpu Stainless Tubular Products Oy Ab; Pietarsaari Finland
Presented at ICALEO 2009

The fiber laser has generally better beam quality than the CO2-laser. This would normally be a positive effect, but also it causes limitations. Welding of joints with slightly inaccurate joint preparation with a very small focus spot usually results in poor weld quality. To solve this problem, new welding methods or procedures must be developed and the scanner technology gives new opportunities. In this project, the possibility of using laser welding with an oscillating mirror scanner was studied for different kinds of joint preparations and edge qualities. The purpose was to use this technology for improving the welding speed and weld quality in tube lines. It is, however, difficult, or even impossible, to fully simulate tube welding in a laboratory. The complex forming rolls, the side pressure and the joint shape are most suitably studied inline. For this reason, a new type of welding fixture was designed and used for the scanner welding tests. With the scanner technology, the laser weld can be widened to overcome different beveling and surface qualities. Another way to circumvent the problem is to use optical beam manipulation. This work has led to a patent application of a method for welding of inaccurate joint.