Abstract
In order to get a high quality of the welding, it is necessary to make a stable back bead and to melt metal plates. In narrow gap welding, it is difficult to control the bead height and the back bead simultaneously by using conventional welding. In order to solve this problem, authors proposed a switch back welding method, in which the welding torch was moving back and forth along the welding line. In the forward torch movement of the torch, the arc heat was given to the root edges to get a wide back bead. In the backward torch movement, the suitable bead height was formed. The traveling distance of the torch becomes key-factor to get a high quality welding result in this switch back welding. By carrying out the fundamental experiments, the numerical model in this welding was prepared. The numerical simulations were performed in the several kinds of the torch movement. The optimum welding conditions was found from simulation results. Its validity was verified by carrying out the welding experiments
