Study On The Stability And High-speed Welding Technology Of Triple-wire Indirect Arc Welding

The triple-wire indirect arc welding(TW-GIAW)is a new welding method.The workpiece is not connected to the power source.The arc is established between the main wire and the side wire.It has the characteristics of high deposition rate and low heat input.High-speed welding technology of thin plates by TW-GIAW is proposed for the first time in this paper.The main wire is connected to the positive pole of the power supply,and the side wire is connected to the negative pole of the power supply.The influence of welding parameters on stability,arc characteristics,droplet transfer and weld formation is analyzed.A high-speed welding process for 2 mm thick steel plates has been developed.The specific research contents and conclusions are as follows:First,high-speed cameras were used to collect arc shapes and droplet transitions,and Hanover arc mass analyzer was used to collect welding voltage and welding current signals.The effects of welding current,pulse frequency and main wire feeding speed on the stability of TW-GIAW were analyzed.Research shows that as the welding current increases,both the welding current variation coefficient and the welding voltage variation coefficient decrease,the voltage probability density distribution and the current probability density distribution become more concentrated,the droplets of the main wire change from projected transfer to spray transfer,the droplets of the side wire change from globular transfer to projected transfer and spray transfer,and the stability of TW-GIAW is improved.With the increase of pulse frequency,the fluctuation range of welding voltage and welding current decreases,the path of droplet transfer decreases,and the stability of TW-GIAW is improved.When the wire feeding speed matches the melting speed,the wire feeding speed can fluctuate within a certain range,in which the influence of the wire feeding speed on the arc stability is limited.Then the effects of pulse frequency and main wire feeding speed on arc shape and surfacing welding seam are analyzed.The study shows as the pulse frequency increases,the arc is compressed in the welding direction and perpendicular to the welding direction,the weld penetration depth increases,and the weld fusion width decreases.The increase of the pulse frequency reduces the welding voltage between the main wire and the side wire.By adjusting the pulse frequency,low energy consumption and large penetration can be achieved.In a certain interval of wire feeding speed,with the increase of the main wire feeding speed,the swing range of the arc decreases,the penetration depth of the weld increases,and the weld width decreases.The pulsed peak current and pulsed base current change the conductive position of the welding wire,and the changes in the magnetic field and electric field around the welding wire cause the indirect arc to deflect to the anode.Finally,the influence of different welding parameters on the weld formation was explored,and the high-speed welding mechanism of TW-GIAW is analyzed.The study shows that when the welding current is too small,the weld has unfused defects,and when the welding current is too large,the weld has burn-through defects.When the angle between the main wire and the side wire is too large or too small,burn-through defects occur in the weld.When the welding speed reaches 3.1 m/min,hump defects appear in the weld,and good weld formation can be obtained when the welding speed is 2.8 m/min.Compared with traditional arc welding,the welding speed of TW-GIAW can reach 2-3 times that of traditional arc welding,mainly because the deposition rate of TW-GIAW is 2.04-2.41 times that of traditional GMAW,and the dilution rate of TW-GIAW is 0.18-0.26 times that of traditional GMAW.The conductive channel of TW-GIAW is established between the main wire and the side wire.The increase in welding speed has less effect on the fluctuation of conductive spots,and TW-GIAW is more conducive to high-speed welding.