Quality Assurance of Laser Welding Processes by Adaptive Closed-Loop Process Control

摘要

Laser welding processes have established themselves in automated production lines due to quality advantages such as minimized heat affected zones, low distortion, and the simple automatization in different industries. Nevertheless the welding process is sensitive to workpiece tolerances, misalignments and clamping problems as well as dust optics, etc. which leads to difficult manual adjustment and process monitoring. This paper describes the performance of an adaptive closed-loop control system which improves the weld quality and reduces manual adjusting. An optical sensor is used to monitor the welding process co-axially through the beam guidance system. The sensor signal is used as controlled variable. A strategy was developed to control the focal position and the wire feed rate. The sensor signals are correlated with the penetration depth of the welds.