The improvement of the conventional welding methods, the widespread use of the laser welding as well as subsequent treatments e.g. annealing and coating have made the automatic detection of the tube weld seam in many manufacturing processes such as in tube and pipe benders or hydroforming a demanding task for modern sensor technology . This applies both to the weld seam detection in tubes as well as to flat stock e.g. coils. Therefore, the use of special detection designed for special tasks, digital signal analysis with microprocessor or PC-based control systems have received our special attention.
