Study On Twin-Wire Indirect Arc Gas Shielded Welding

Twin-wire indirect arc gas shielded welding is a new welding technology. Because of the difference of arc circuit, the welding process of twin-wire indirect arc gas shielded welding is more stable than single wire welding. Compared with single wire welding, twin-wire indirect arc gas shielded welding has higher deposition rate, lower energy consumption, and smaller the welding deformations and postwelding remanent stress.The welding process was studied through welding experiments in this paper. The condition of stable arc burning, welding current, arc voltage and their influence on melting rate of twin-wire, arc shape, welding processing property and the performance of weld bead were analysed by means of the home-made automatic welding device, FASTCAM Super- 10KC high-speed camera system and Agilent54624A oscilloscope etc.For the melting rate of twin-wire is not equal in twin-wire indirect arc gas shielded w elding, two d ifferent type o fw ire-feeding c ontrol s ystems w ere u sed i n order to make the wire-feeding speed equal to the melting rate in this paper. Results indicate that the twin-wire feeding speed equaling to each melting rate is the necessary and sufficient condition that the welding arc stably burns in twin-wire indirect arc gas shielded welding.The welding gun is a key component of twin-wire indirect arc gas shielded welding. The structural shape and physical dimension of welding gun not only relate to the service performance, but also to stable arc burning, gas shielded effect and welding quality. It is found that the angel of twin-wire is from 30° to 50°, and the electrode extension is from 10mm to 20mm by test. The welding gun of twin-wire indirect arc gas shielded welding was designed in this paper.The arc of twin-wire indirect arc gas shielded welding can be ignited and burn at different distance to workpiece, while the arc appears different shape. With different arc current, the degree of centralizing and decentralizing of welding arc varies. The welding arc becomes brighter and bigger with the increasing of arc current. The welding arc shape changes periodically with the changing of time in twin-wire indirect arc gas shielded welding.Welding current and arc voltage are two important processing parameters in twin-wire indirect arc gas shielded welding, and they have directly effect on the melting rate of twin-wires. The melting rate of twin-wire increases with the increasing of welding current, and the melting rate of cathode is faster than that of anode. The melting rate decreases slightly with the increasing of arc voltage. With the raising of arc voltage, the weld width reduces slightly. With the increasing of welding current, the droplets are refined and their transition frequency increases, the width of weld bead is enlarged and the penetration increases, and the formation of weld bead is better. Particularly, when welding current is higher than 200A, the droplets are more refined, the welding current has very small fluctuation and the welding process is stable.Furthermore, the distance between the top of wire and the workpiece, and the welding speed are also important processing parameters in twin-wire indirect arc gas shielded welding. Large number of experiment results show that the suitable distance between the top of wire and the workpiece is from 10mm to 20mm, and welding at this distance the process is stable and the shielded effect is better. Welding speed has obvious influence on the formation of weld bead. In order to obtain well continuous weld, suitable welding speed must be chosen with definite current and voltage.