Study On Welding Seam Forming Mechanism And Multi-pass Forming Process Of Double-wire Three-arc Welding

In traditional welding,there is a contradiction between high deposition rate and low heat input.High deposition rate will increase heat input,increase deformation and affect welding quality.In double wire and three arc welding,two main arcs are generated between two welding wires and workpiece respectively.The main arc starts and extinguishes alternately,and a third arc,namely m arc,will be generated between the two welding wires.The m-arc current and pulse frequency can be adjusted independently,which is mainly used to melt the welding wire rather than directly affect the base metal.Therefore,this method has the advantages of high deposition efficiency and low heat input.Twin wire welding technology can greatly improve the efficiency of welding.Firstly,based on the principle of static balance,aiming at the effect of arc in the process of double wire three arc welding,the force of droplet is analyzed,and the static balance model is established combining with the influence of M arc.It is found that with the increase of M arc current,the droplet transfer mode changes.The short-circuit jet hybrid transfer welding process is the most stable and the weld formation is good.Then the corresponding table of pulse frequency and wire feeding speed was established,and the appropriate wire feeding speed was selected to change the pulse frequency.The transition mode of one pulse and one drop was the least spatter.Then,in order to improve the forming quality and accuracy,it is necessary to study the relationship between the process parameters of single pass weld and the weld forming size and quality.For the double wire three arc welding,the forming factors of single pass weld formation mainly include welding speed,wire feeding speed,m arc current and M arc pulse frequency.Therefore,it is important to find out the influencing factors and the optimal range of welding parameters to control the welding quality.The optimal welding parameters were obtained by weld forming test and forming mechanism analysis.Finally,The basis of arc additive forming is a single-layer multi-layer lap process,and the most important part of the multi-layer lap process is to study the lap spacing.First,according to the actual weld contour shape of double-wire three-arc welding,the single-layer single-pass model of double-wire three-arc welding is fitted as a parabola.Then extract its advantages from the existing single-pass lap model,and analyze the defect principle of double-wire three-arc welding,propose and improve a new lap model suitable for double-wire three-arc welding,and finally find the optimal lap ratio as 0.689 times the melting width,and test verification.Then build a single-channel multilayer model and test.The analysis and comparison of the cross-sectional morphology of the lap weld show that the improved model is more consistent with the double-wire three-arc multi-pass lap welding.