ARC WELDING METHOD

PURPOSE:To stably obtain satisfactory welding quality by changing a king of shielding gas according to members to be welded, selecting and supplying the shielding gas by changing over valves and eliminating the shielding gas used before from a weld zone by the pressure of the shielding gas used afterward. CONSTITUTION:Plural kinds of members to be welded are arc-welded to a work by a consumable electrode by using the shielding gas. The kind of the above mentioned shielding gas is changed according to a kind of members to be welded and the shielding gas is changed over via changeover valves 10, 11 and 12 and supplied to the weld zone. The shielding gas used before is eliminated from the above-mentioned weld zone by the pressure of the shielding gas used afterward and then, welding is performed. An arc shape is changed and as a result, a weld bead shape is changed and the welding quality can be maintained satisfactorily by changing the kind and specially, a component of the shielding gas according to the kind and specially, the shape of members to be welded. In addition, mixing of both gases is prevented and the stable welding quality can be obtained.