The Arc Interference Research And Welding Process Of Twin-wire GMAW

In contemporary society, many important industries such as shipbuilding, automotive and aerospace etc. are facing very rapid development, it is very urgent to develop high-efficient welding technologies so as to meet the high processing requirements. In order to increase the welding efficiency, twin-wire welding or multi-wire welding is adopted. The main problem of twin-wire welding is arc interference caused by the electromagnetic force. How to suppress or overcome arc interference becomes a very important subject for people working in the welding field.In this paper, we build up a twin-wire welding platform which contains automatic welding system, electrical data acquisition system and high speed photography system. We mainly focus on the arc shape, droplet transfer mode and electrical waveform in welding process to carry out systematic investigation and analysis. Then we come out with the cause for arc interference and the way to suppress that. We discuss the migrating of stable welding working point when the arc length changes. The experimental results are put into use for twin-wire butt welding. We analyze the metallography and mechanical properties of sing-wire and twin-wire welding. Besides, the welding efficiency and limited welding speed for single-wire and twin-wire welding are investigated.In single-wire welding, the arc shapes like a bell jar and the welding process is quite stable. While in twin-wire welding the arc tends to have large shift from the center. Either increasing the leading wire current to exceed the trailing wire current, enlarging the twin-wire distance, or using mixed shielding gas to replace pure argon will result in suppressing the arc interference and making welding process more stable.In single-wire welding, the transfer mode of droplet is a mixture of globular and spray transfer and the transfer process is quite stable. While in twin-wire welding, the droplet transfer mode becomes more agitated with a shift of the transfer path. Increasing the leading wire current to exceed the trailing wire current will be helpful to satisfy stable droplet transfer process.By the way, we investigate the influence of welding parameters that will result in the weld seam appearance. We find that when the leading wire current is larger than the trailing wire current, there both exists the “pullpush” flow mode and the “outward” flow mode. The surface tension becomes more well-distributed. And there factors will bring better weld seam appearance.Besides, we put the experimental results into practice, the twin-wire butt welding of E36 steel. We find that both the single-wire and twin-wire welding joints have similar metallography and mechanical properties. With the same welding speed, the twin-wire welding process seems to have a 37.5% efficiency superior to single-welding. With similar welding current and voltage, twin-wire welding can achieve a larger limited welding speed than single wire welding that avoids the humping defect. Additionally, we put twin-wire welding into thick board horizontal welding with a 60 mm deep groove and achieve excellent weld seam with good weld quality.