Analysis by Modeling of Horizontal Coaxial Arc Welding Phenomena: Automatic Welding Process for Ship's Bottom Shell Plates

New automatic arc welding process has been developed for welding ship's shell plates upwards from the ground. In this process, the axis of the leading welding gun corresponds to that of a weld bead, therefore it is called ‘Horizontal Coaxial Arc Welding’ (HCAW). In order to keep the welding process under control, the simplified numerical model expressing the static balance of forces on the leading molten pool has been designed. The model enables to estimate the weld bead height and the bead formation rate. As a result of analysis by the model, the wire extension length will reach its equilibrium state spontaneously in the case of using a constant voltage characteristic power source, and controlling of the wire feeding speed is effective to reduce the change of the wire extension length during welding in various root opening.