Laser welding seam tracking system

The introduction of laser welding techniques have made it possible to weld deep and narrow joints with low thermal lag. In order to produce faultless welds, the laser beam has to be positioned very precisely along the joint (1). Additionally, the laser is capable of welding nonmetal workpieces like ceramics and plastics with very high precision and quality. With such materials, seam tracking with high accuracy can only be achieved by using optical sensors instead of for example, capacitive or eddy current sensors (2, 3). Nowadays suitable optical sensors are based on the principle of light intersection, which means that one or more lines are projected to the surface of the workpiece and are monitored by a camera. Their position is ahead of the welding head and orthogonal to the joint geometry. Such sensors are however very limited in their ability to track three-dimensional seams. Therefore, a new type of sensor has been developed, designed and successfully tested with different types of welding seams in an industrial laser system, which not only recognises and tracks the seam to be welded, but also characterizes the area around the welding point with little pretravel.