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2016
Presentation
Title
Multi-pass-narrow-gap welding with high power diode laser for steel construction
Title Supplement
Presentation held at 9. Internationales Lasersymposium und Internationalen Fügetechnischen Symposium "Tailored Joining" 2016, Dresden, 22.-24.2.2016
Abstract
Machines and large technical facilities such as presses, heavy-duty cranes, rail or truck chassis as well as wind turbines in which thick-walled cross-sections have to be joint, can be produced according to the current state of the art by conventional GMAW or submerged arc welding processes. Although a high level of development since the introduction of modern inverter-welding power sources has been achieved, the use of these methods is also characterized by a high manual effort. The use of beam welding methods for large welding depths is, with the exception of the electron beam welding, due to bridging large joining gaps still unusual. In addition high investment costs of beam based methods have been a limitation to their use. The technology challenges of conventional welding methods include, among others, the regulation of heat input to reduce component distortion and the increase of production efficiency by minimizing the joints opening angle of currently up to 60 °. To overcome these and other issues, the Fraunhofer Institute for Material and Beam Technology has developed a so-called laser multi-layer narrow gap welding (Laser-MPNG). The new welding technology uses laser sources of limited beam quality (BPP: 150 mm mrad, diode) compared to fiber lasers in the power range from 10 to 20 kW. The opening angle is reduced to values of less than 15 °, whereby the gap volume that has to be refilled is significantly reduced compared to conventional GMAW or submerged arc welding processes. The technology of Laser-MPNG will be explained by using the example of a research development and its boundary requirements such as gap-geometry and gap-bridging will be presented. Furthermore, the potential for use on construction sites in steel construction by using the advantages of laser welding, localized heat input, high degree of automation and high reproducibility of the weld joint will be pointed out. In addition, an overview of the effectiveness of seam filling and the cost for the technology will be carried out in comparison between conventional welding methods and the Laser-MPNG technology.