Study on mathematical modeling of parameter optimization in gas tungsten arc (GTA) welding of thin pipes

In order to estimate the optimal process parameter in circumferential GTA welding of thin pipes, the objective was chosen to maintain a uniform bead width over the full circumferential joint, while the constraints consist of the capacity limit of power source and related equipments. The analytical solution of heat conduction equation with a Gaussian heat source was adopted for calculating the temperature field in circumferential welding of the pipe workpiece. The linear complementary problem(LCP) with Lemke's pivoting algorithm and Powell's unconstrained search method with the sequential unconstrained minimization technique (SUMT) have been applied to evaluate the optimal welding current and welding velocity for a required bead width respectively. The experimental results of the bead formation showed that the developed mathematical model can be effectively applied for obtaining the optimal welding condition in circumferential welding of thin pipes with a small diameter.