Abstract
As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.
About the authors
Oliver Pütsch received his diploma in Mechatronics Engineering from Aachen University of Applied Sciences, Germany in 2008 and his MSc in Mechatronics in 2010. During his masters course, he worked at the Faculty of Mechanical Engineering and Mechatronics at Aachen University of Applied Sciences in the subject area of Microtechnology. He is currently pursuing a PhD in engineering and has been working as a research scientist at the Chair for Technology of Optical Systems at RWTH Aachen University since 2011. His research interests are the application and development of active and controlled optical devices.
Dr. Jochen Stollenwerk received his Diploma degree in Physics at the RWTH Aachen University in 1996. He was a scientific employee at the Fraunhofer-Institute for Laser Technology in Aachen (ILT) and received his PhD in the area of Laser Materials Processing in 2001. After his PhD examination, he moved to TRUMPF Laser Marking Systems (Grüsch, Switzerland), where he was responsible for the Application department. In 2004, he became the Vice Director at the newly founded Chair for ‘Technology of Optical Systems’ at RWTH Aachen University and additionally took over the responsibility for the group ‘Thin Film Laser Processing’ at the Fraunhofer-Institute for Laser Technology.
Markus Kogel-Hollacher began his activities in the area of lasers working for his MS degree at the Fraunhofer Institute for Laser Technology in 1994. Since then, the focus of his work has been in the field of monitoring and control of laser processes. After earning his MS degree in physics in 1996 from the RWTH Aachen University in Germany, he joined Precitec Optronik GmbH (formerly Jurca Optoelektronik GmbH) in Rodgau, Germany, continuing the work with the emphasis on transferring R&D results to industrial solutions. This work has been discussed extensively in several technical journals and presented at various conferences. In his position as the head of the department’s R&D projects in the Precitec Group, he oversees national and international governmentally funded projects. Working together with RTD performers and end users, his guiding principle is to continuously increase the reliability and the use of process monitoring and process control devices in laser materials processing. In 2008, he obtained his PhD at the Technical University of Berlin, Germany. Dr. Kogel-Hollacher has been a member of the Laser Institute of America (LIA) since 2002. At present, he is a member of the board of directors at the LIA and recently has served as a jury member of the Innovation Award Laser Technology.
Martin Traub studied mechanical engineering at the RWTH Aachen and Michigan State University. He received his diploma in 1999 and started working as a research scientist at the Fraunhofer ILT. He gained a diploma in Industrial Engineering from RWTH Aachen in 2003. Since 2008, he leads the group ‘Optics Design and Diode Lasers’ at the Fraunhofer ILT.
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