2011 年 29 巻 3 号 p. 39s-42s
In plasma MIG welding process, because shielding gas is ionized in advance by a plasma electrode before supply, the shape of arc is easily controlled through electromagnetic force. Therefore the controllability of the arc is remarkably enhanced compared with that in a conventional MIG welding process. Because of this advantage, it can be employed for MIG welding in pure inert gas atmosphere. Although experimental results on plasma MIG welding in pure argon atmosphere were reported, further improvement of the welding process is required because it is difficult to form bead stably due to lack of the wettability. We have developed a new torch for plasma MIG welding which has shorter distance between a contact tip and the top of a nozzle than that of the conventional torch. In this paper, experimental results on welding of steel plates with V groove in pure argon atmosphere employing the new torch are discussed compared with those for the conventional torch. As a result, it was found that the bead formation was improved due to high wettability in case of the new torch, because melting volume of the base metal increased due to increase in averaged MIG current and heat flux.
