Study On Arc Behavior And Droplet Transfer With Cable-type Welding Wire In TIG-MIG Composite Welding

In the traditional TIG-MIG composite welding manufacturing process,most of the composite welding uses monofilament welding.The energy of the TIG-MIG composite heat source cannot be fully utilized,and the weld deposition rate is small,resulting in a relatively low production efficiency.Based on the characteristics of TIG-MIG composite welding,this paper proposes a TIG-MIG composite welding method with cable welding wire.By introducing the cable welding wire,the composite welding heat source can be effectively used,and the welding production efficiency can be improved.Firstly,a composite cable welding welding platform was established and build a parameter collection system for composite welding.The high-speed imaging was used to record the arc shape and droplet transition in the welding process.the welding parameters were collected synchronously.This method was used to analyze the welding process of monofilament TIG-MIG composite welding,cable-type welding TIG-MIG composite welding and cable-type wire MIG welding.At the same time,the weld formation of the three were compared to study the influence of different factors on the arc shape,droplet transfer and weld formation in TIG-MIG welding.The Influence of parameters such as the wire pole spacing,MIG voltage,TIG current,MIG polarity,and the angle on the shape of the composite arc in the TIG-MIG composite welding were studied.When the wire pole spacing is 18 mm,it is the best distance between the two arcs to achieve coupling.When the TIG current is in the range of 130A-150 A,the magnitude of the force between the two arcs can achieve good coupling.When the two arcs have the same polarity,the two arcs attract each other.When the two arcs are opposite,the two arcs repel each other.two arcs attract each other,the welding is better.Compared U-I waveform and U-I distribution of MIG under different TIG currents,it is found that TIG current has different influence on MIG current and voltage under different transition modes.The results show that when the droplet transition mode is short-circuit transition and droplet transition,the presence of TIG arc can effectively reduce the fluctuation of MIG electrical parameters.When the optimal TIG current range is 130A-150 A,the fluctuation of the MIG electrical parameter is the smallest,When the droplet transfer mode is the droplet transfer,the TIG arc has little effect on the stability of MIG arc.The transition patterns,droplet diameters,and droplet transition frequencies of TIG-MIG composite welding,TIG-MIG composite welding,and MIG welding of cable-type wire under different conditions were analyzed.The presence of a TIG arc can change the droplet transfer pattern and drop path of the MIG weld,and also change the diameter and over-frequency of the droplet.When the TIG current is in the range of 100A-160 A,the droplets transition from the short-circuit transition and the droplet transition under the same conditions to the droplet transition respectively.The droplet diameter gradually becomes smaller,and the droplet transition frequency increases.Compared with the monofilament TIG-MIG hybrid welding,the mechanical rotation force is added to the droplet transfer of the TIG-MIG hybrid welding wire,which can accelerate the droplet necking and promote the droplet transfer and reduce the spatter in the welding process.When the two arcs have opposite polarities,the droplet path is deflected,and the shape of droplets changes greatly,and the transition effect is poor.A comparative analysis of the TIG-MIG composite welding and the MIG welding of the cable welding under different transition modes found that the introduction of the TIG arc can improve the weld formation,especially when the droplets are in the short-circuit transition and the droplet transition.At the time,the improvement of its welds is most obvious.When the TIG current is 130A-150 A,the welding defects are minimized and the weld appearance is beautiful.When the wire pole spacing is too small,the arc of TIG and MIG shielded gas are easy to flow to form turbulence.easily causing the coupled arc to become unstable,and the protection effect on the molten pool also deteriorates.The gas flow velocity of the TIG shield gas mainly affects the stiffness of the TIG arc.When the flow velocity is too large,the TIG arc stiffness is large,the quality of the weld seam is poor,and the arc stiffness is weak when the flow velocity is too small,which easily causes the tungsten defect of the weld seam.