The process control of the starting arc in laser welding.

Laser welding as a high-energy beam precision welding technology, with its low thermal input, small welding deformation, welding speed, high degree of automation, a series of advantages, more and more widely used in the industrial field.

However, in Dotslaser welding, if the arc section and the arc collection section do not carry out special process treatment, then due to the machine tool or robot and other moving body of the acceleration process, at the beginning of the weld is prone to appear "match head" appearance, the end of the weld is prone to arc pit depression, the overall uniformity of the weld appearance has a greater impact, and the arc at the end of the arc will reduce the strength of the weld, easy to produce arc cracks. And the greater the laser power density, the more obvious this phenomenon.

Therefore, in the actual production process, the weld arcing and arcing process needs to be special treatment. If the weld position and conditions allow, can be avoided by adding an introduction arc plate, but in the actual mass production, this scheme is not applicable, and part of the weld trajectory is closed graphics, weld start and end segments are in the weld, so it is necessary to optimize the weld process parameters to adjust the shape of the weld arc closing segment.

The weld shape can be adjusted by the laser power control and PWM control of the starting arc segment, and during the arcing phase, the power can gradually change from low to high as the moving mechanism accelerates from stationary to normal welding speed, and the power can be changed gradually from low to high, low power in the low-speed stage and high power in the high-speed stage, which can be avoided. At the arc "match head" shape, in the arcing stage, the laser power is gradually reduced, can reduce the energy density of the welding line, the weld melt width gradually narrows, the welding process deep melting hole gradually becomes shallow, thus improving the arc pit shape at the weld arc.

Therefore, by controlling the laser power slowly rising and falling, the weld can be smoothed too smoothly at the start and end of the arc, significantly reducing the height of the weld starting arc point and the size of the arc pit at the end of the arc and depression. On this basis, in order to further control the heat input volume of the starting and ending segments, the dubing ratio or modulation frequency can be optimized again with the change of welding speed.

DOTSLASER uses continuous optical lasers for continuous welding and modulation mode welding, and laser power can be adjusted in real time. With Jept's continuous laser monitoring software, not only can the laser's working status be monitored in real time, but also the line energy density can be precisely controlled, thus avoiding the "matchhead" shape at the arc.