Study Of Characteristic And Process Of The Mirror-symmetry Triple-wire Indirect Arc

The triple-wire indirect arc welding process is a novel welding process with low energy consumption and high deposition rate.However,because no current flows through the base metal,the heat input to the base metal during the welding process is extremely low,which easily causes unfused defects.In order to improve the heat input of the base metal and increase the melting efficiency of the base metal,this paper proposes a triple-wire indirect arc based on mirror-symmetrical wire arrangement by optimizing the triple-wire indirect arc shape as the entry point and changing wire arrangement and the connection method of wire as a means,and the arc behavior and droplet transfer are studied,the arc deflection mechanism is clarified,and the droplet transition trajectory is analyzed.The melting efficiency of the base metal and the process parameters affecting the weld formation are discussed,and the 10 mm single-pass butt welding process is developed.The mirror-symmetrical wire arrangement is first determined and its arc characteristic is explored.In the triple-wire indirect arc of the mirror-symmetry wire arrangement,the indirect arc always deflects toward the anode under the action of the magnetic field and the special annular electric field.When the main wire acts as cathode and the side wires act as anode(MCSA),the two indirect arcs simultaneously deflect toward the side wires.In MASC,the two indirect arcs simultaneously deflect toward the main wire and a single indirect arc with a large stiffness is formed.In addition,the electron density around the main wire is higher in MASC.Under the conditions of minimum main wire feed speed and arc stability,the distance between the end of the main wire and the end of the side wires is larger,the arc voltage is higher,the heat input to the base metal is larger.The droplet transfer behavior of the mirror-symmetry wire arrangement is explored.Electromagnetic force between the electrodes has an important influence of the droplet transition trajectory.In MCSA,the end of the main wire is located between the ends of the two side wires,and the main wire droplets transfer along the extension line of the main wire,and the droplets of side wires respectively deflect toward the two sides under the repelling of the main wire.In MASC,there is a certain distance between the end of the main wire and the end of the side wires.The side wires droplets attract each other while the main wire droplets and the side wire droplets are respectively biased to the respective sides under the action of the repulsive force,and the repulsive force of the main wire droplets is greater than the side wire droplets.As a result,the short circuit caused by the contact between the main wire droplets and the side wire droplets is avoided and the stability of the arc is improved.The melting efficiency of the base material and pulse process parameters are studied.In MASC,a single indirect arc with a large energy density is established,and the melting efficiency of the base material is greatly improved compared to the MCSA.For example,under the experimental conditions,the melting efficiency of base metal is 6.5%~20.5% in MASC,but it is only 4.6%~8.05% in MCSA.In addition,the single indirect arc has pulse characteristic.Based on the preliminary determination of the basic pulse parameters,a single-pass butt welding process for 10 mm thick plates is proposed,and a comparison experiment with the traditional single wire welding process(T-SW)is performed.For the same weld,the energy consumption of MASC is only 43.8% of T-SW.