Infrared sensor-based on-line weld penetration control

This paper describes progress made during the last year in identifying weld perturbations using indirect methods based on an infrared sensor. Using changes in the temperature gradient, it is now possible to identify the geometry of the weld pool and weld penetration changes due to welding current variations or plate thickness changes. The procedures for computing each of the penetration indicators were streamlined to reduce the computation time. Bead width was one of the methods used in an on-line control routine. A software was developed for on-line weld penetration control using the beam width as the error signal and the welding current as the control parameter.