Research On The Arc Behavior And Metal Transfer Of Triple-wire Gas Metal Arc Welding

High efficient welding process is an important part of the research of weldingtechnology. Triple-wire gas metal arc welding is a new high efficient welding processwhich was developed on the basis of single-wire welding and double-wire welding.Triple-wire welding is of great research value for its high deposition efficiency andhigh welding speed. Currently, the research on Triple-wire welding was mainlyfocused on welding equipment and welding process simulation，while the research ondroplet transfer and arc behavior during welding process was quite fewer, therefore itis necessary to study deeply onto this issue.In this study, the triple-wire gas metal arc welding system was established on thebasis of previous research with the improved equipment for the welding experiment.The multi-information synchronizing acquisition equipment was used to capture andanalysis the electrical signal and high-speed images signal during the welding process.The result showed that different welding parameters had different influence on arcbehavior, arcing alternating frequency, droplet transfer and weld forming.The force on droplet, the interaction between three arcs, the thermal distributionand the flow of weld pool, the characteristics of jointly conductive channel and itsforming characteristics were studied in this research. The result showed that there wasstrong interaction between three arcs as the current through three arcs was in the samedirection, therefor the direction of the force which applied on the arcs point to thecenter of the torch. The size of the weld pool was lager, the temperature gradient wassmall and the liquidity of weld pool was higher. There was only one arc burning onone of three wire, it turned into two arcs or three arcs and finally it turned into threearcs when the welding voltage increased. The conductive channels were independentwhen there were only one arc or two arcs. When it turned into three arcs, there wasintense interaction between the arcs while the jointly conductive path was formed.The welding efficiency ratio between single-wire welding, twin-wire weldingand triple-wire welding was approximately1:2:3, which proved that weldingefficiency could be greatly improved by triple-wire welding on the premise of thewelding quality guaranteed.There were three kind of arc behavior in this research, which were single arc, twin-arc and triple-arc. As the welding voltage increased, the single arc turned intotwin-arc and finally it turned into triple-arc, while the size of droplet increased, thealternating frequency of the arc deceased. As the feeding speed of the wire increased,the twin-arc turned into the mixed state of twin-arc and single-arc, while the size ofdroplet decreased, the alternating frequency of the arc increased.As the wire extensionlength increased, the triple-arc turned into the mixed state of twin-arc and single-arc,while the size of droplet decreased, the alternating frequency of the arc increased andthen decreased. As the welding speed increased, the stability of the arc decreased,while the size of droplet increased, the alternating frequency of the arc decreased. Itwas not conducive to obtaining a good weld when the flow of the shield gas was toolow or too high, it was the optimal when the flow of the shield gas was20L/min inthis research.