60㎏f/㎟급 자동차 범퍼빔용 레이저 용접 튜브 제조기술 및 장치연구

Optimal process and system to produce the laser welded tube for one body formed bumper beam are studied. The calculated size of tube is a thickness of 1.4㎜, diameter of I05.4㎜ and length of 2000㎜. The tube is shaped from a cold rolled high strength steel sheet(tensile strength: 60㎏f/㎟ grade). Two roll bending method is the optimal tube shaping process compared to UO-bending, bending on press brake, multi-step continuous roll forming and 3 roll bending methods. Weld quality monitoring and seam tracking along the butt-joint lengthwise to the tube axis are also studied. The longitudinal butt-joint is welded by the CO₂laser welding system equipped with a seam tracker and plasma sensor. The constructed CO₂laser tube welding system can be used for the precision seam tracking and the real-time monitoring of weld quality. Finally, the obtained laser welded tube can be used for one-body formed automobile bumper beam.