Weld Penetration Control

A novel approach for controlling weld bead penetration is proposed. The methodology is distinguished from past techniques by use of: 1) a new and more accurate model of the weld pool dynamic behavior, 2) an improved method of sensing the weld pool oscillations, 3) a more efficient method of weld pool excitation, and 4) a model-based relation of pool dynamics, weld pool geometry, and equipment parameter settings. Application of the proposed technique allows control of the weld bead penetration in both the full and partial penetration cases. The proposed weld pool dynamic model uses a droplet formulation for describing the pool oscillation, in contrast purpose. The optical sensing methodology uses an improved sensor for increased signal quality and amplitude. Two techniques for implementing and controlling the excitation of the weld pool are outlined in the proposal. In both cases the pool is continuously excited at its natural resonant frequency and the excitation frequency changes. Excitation at the resonant frequency alows maximum excitation with minimum input energy. In addition to its proposed use for weld penetration monitoring and control, the resonant oscillations caused by the system can be used to enhance pool stirring and thus control other aspects of the weld, such as grain size and orientation. This system would be particularly applicable to the rigorous control requirements necessary for the welding of exotic alloys used in aircraft and aerospace construction. Anticipated Benefits: The proposed techniques can be implemented as generic weld penetration monitoring devices, making automatic penetration control feasible and practical. The utility of such devices is very broad and can be utilized in a variety of commercial applications.