Temperature monitoring independent of laser‐beam‐position during laser transmission welding of fibre reinforced thermoplastics
Conference on Lasers in Manufacturing (LiM)
The heterogeneous heat conductivity in carbon fibre reinforced plastics (CFRP) critically influences process temperature during welding and increases the necessity for temperature control to secure weld quality. While infrared cameras are a powerful tool for monitoring process temperature they have a low temporal resolution and they are comparatively expensive. A potential alternative is sought by utilisation of a dynamically movable pyrometer measuring spot. In this work, heat development during bead‐on‐plate laser welding on carbon fibre reinforced polyphenylenesulfide (PPS) is investigated. The pyrometer spot is capable of measuring temperatures locally independent of the processing laser spot. Thus, temperatures are monitored at a high temporal resolution during welding in front of, behind, and aside the current weld area. Results of this investigation give rise to expectations that a dynamic pyrometer spot allows for precise temperature measurements at critical points of complex weld geometries such as curved weld seams. This will set up the basis for an automatic laser welding control, which will be capable of adjusting the laser welding power according to required temperatures for a supreme weld quality.