Finite element simulation of seam welding process

To produce sound nugget, it is necessary to select the most suitable conditions, such as the squeezing force, the welding current, the welding speed, the electrode shape and the mode of current. To determine them, large numbers of experiments, which require significant cost and time, have to be conducted. One of the effective solutions for this problem is computer simulation. Thus, a finite element method for the seam welding is developed and the appropriate conditions are studied through numerical simulation. In this research, the effects of the mode and the value of the welding current and the welding speed on the formation of the nugget are examined by using newly developed method. In case of the continuous current mode, periodic instability appears in the process and continuous and uniform nugget is not produced. This periodicity is closely related to the contact area between the electrode and the work. It is also found that a current with discontinuous mode is preferable to achieve a good nugget because the contact state is stabilized by the cooling effect of the electrodes. (Example materials include Invar and copper.)