The gap bridging capability in laser tailored blank welding

The demand for the use of tailor welded blanks in the automotive industry continues to grow. Like in any other laser welding applications, the requirement for an intimate fit-up is a key in laser tailored blank welding. In the case of edge preparation is not sufficient, alternative laser welding method can be applied. A study on the bridging capability of co₂ laser welding with a twin spot optic was done. It shows that gaps with a maximum width of 0.45 mm can be bridged using a co₂ laser twin spot optic with the 8 kw laser power and a maximum welding speed of 4.75 m/min for 3.0 mm-1.9 mm and 3.0 mm - 1.2 mm butt joint combinations. By placing the center of the twin-spot a little more on the thicker blank about 0.15 mm away from the abutted line, the maximum gap which can be tolerated becomes approximately 0.2mm larger compared to that aligning the center of the twin spot on the abutted line. The changing in the incidence angle from 0° to 45°, the maximum width of the gap which can be bridged increases by 0.1 mm and the speed of welding by 1 m/min for 1.2-0.6 and 1.9-1.2 butt joint combinations. The changing in the orientation of the twin spot, angle θ, from 0° to 60°, the speed increased by 0.5 m/min, whereas the position accuracy for tolerating a variation in position (laser beam and weld seam alignment) decreases by 0.15 mm compared to 0.3 mm.