| In this paper,a novel multiple-wire welding process entitled integrated circular triple-electrode GMA welding was proposed.Another welding process entitled twinarc integrated cold wire hybrid welding was derived out through exchanging one of the consumable electrodes for cold wire(no arc).This welding process had both increasing welding deposition and keeping constant welding heat input,which benefited to heatsensitive material welding.The whole paper was focused on technological characteristics of above two welding procedures to research and analyse,which established foundation for high-efficient three wires welding process.Firstly,in consideration of arc interference under simultaneous arcing,the cooperative control among three arcs was put forward,i.e.,the pulse waveform of random phase difference can be outputted based on mutual communication among three power sources.The effects of welding electrical parameters on metal transfer process and weld formation were researched under three typical pulse phase difference of 0o,180o and 120o,and the optimum process parameter intervals were respectively obtained.In addition,the influence mechanisms of pulse phase difference on metal transfer and weld formation were researched and analyzed.Experiments found that the pulse phase difference of 0o had the highest arc electric filed intensity,closely followed by 180o,and the phase difference of 120o lowest.Thus the phase difference of 0o more easily showed one droplet multiple pulses.However,the pulse phase of 180o and 120o more easily showed one drolet per pulse,and the welding stability and weld formation of one droplet per pulse were visibly improved.Besides,the pulse phase difference of 180o had the maximum weld penetration,closely followed by 120o,and the phase difference of 0o minmum.The weld cross section under phase difference of 120o showed twin peaks appearance.Secondly,the influence mechanisms of welding electrical parameter on metal transfer and weld formation were respectively researched and analyzed in the DC,inphase pulse current and reverse-phase pulse current mode.Experiments found that the transfer modes were divided into short-circuiting and globular transfer in DC mode,which had worse welding stability and weld formation.In the in-phase pulse current mode,the desired metal transfer mode was projected transfer.In the reverse-phase current mode,the desired metal transfer mode was streaming transfer.In addition,the influence mechanisms of arcing mode on metal transfer and weld formation were researched and analyzed.Experiments found that the main transfer mode was projected transfer in the simultaneous arcing mode,but was streaming transfer in the alternative arcing mode when other welding parameters remained constant.The main reason was that the arcing mode greatly affected not only the electric field intensity of arc column,but also the directions of arc forces upon the droplet.Besides,the simultaneous arcing had the greater weld penetration and less weld width,and weld penetration was more likely to one side because of mutual attraction between two arcs.In alternative arcing mode,the arc forces generated from two arcs respectively acted on weld pool,and the cross-section appearance of twin peaks formed.Lastly,the study on the influence mechanism of cold wire on welding process in twin-arc integrated cold wire hybrid welding system.The experimental results indicated that in addition of increasing deposition rate,the cold wire played an important role in improving the welding stability.The addition of cold wire could stabilize the cathode spot on the surface of the weld pool without drifting with the rear flow of the liquid weld pool metal,which all contributed to decreasing the fluctuation of arc voltage to improve the welding stability.In addition,the above conclusion was fully validated by hypothesis test. |
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