DEVELOPMENT OF HIGH-SPEED LASER WELDING TECHNOLOGY USING COMPOUND-LASER METHOD FOR TAILER WELDED BLANKS

摘要

This paper deals with a new laser welding technology of coupling CO{sub}2 laser with diode laser. As this development, the high-speed welding of steel materials with different grades for a car body -^sTailor Welded Blanks (TWB) is possible within good deal. So far, YAG laser or CO{sub}2 laser is used as welding tools for the tailored blank welding. Especially, a diode pumped YAG laser (called DP-YAG) is popular as the newest high power laser source in Japan. One good side of DP-YAG is realization of high-speed welding, it means undesirable point, is expensive cost as a laser source. Aiming the performance of 4.5 kW DP-YAG laser, the main point of development is generating the good laser beam for TWB with compounded different lasers of 3 kW CO{sub}2 laser and 3 kW diode laser. Developed new optical element was able to combine two lasers having large difference of wavelengths on the same ax. The laser-welding torch kept this optical element inside and achieved the high-speed welding with low cost. By compounding the two lasers, this technology could produce TWB combed different gauge sheets of 0.7 mm and 1.4 mm with high welding speed of 12 m/min. The performance was the same as 4.5 kW DP-YAG laser. The good point was that influence from the cutting accuracy of metal sheet was less than in the case of the YAG laser. This new welding method offered also high productivity of TWB. The mechanical strength and other properties about the welded seam were same as the YAG laser welded. The welding cost per 1m had decreased to about 85% with this laser welding technique. The next plan is the development of higher speed welding technology for TWB. The improvements of optical devices and other matter will be advanced for the achievement.