Research On The Physical Characteristics And Weld Forming Of The Rotary Pendulum TIG-MIG Composite Heat Source

Combining the advantages of high quality of TIG welding and high efficiency of MIG welding,a TIG-MIG composite welding process is formed,which can obtain a weld joint with excellent comprehensive performance.According to related literature,the welding pool of TIGMIG composite welding has a strip-shaped feature,that is,the welding pool in the welding direction is larger than the width in the melt width direction,and welding defects such as undercut and finger penetration are prone to occur.In order to solve this problem and consider the high quality of the weld seam,further optimize and expand the distribution and application field of composite heat source,on the basis of TIG-MIG composite welding,the rotary pendulum TIGMIG composite heat source welding process is proposed.The use of the TIG arc's swinging pendulum effect to increase the lateral space of the composite arc and promote the molten pool spreading,improve welding problems such as under-melting width,undercut and finger,and further lay the foundation for research in the field of narrow gap welding technology.In order to better study the characteristics of the new process,based on the self-designed rotary pendulum TIG-MIG composite heat source welding gun,a welding experiment system was established,including a composite heat source welding system,auxiliary system high-speed camera acquisition system and current and voltage acquisition system.The auxiliary system is used to collect the composite arc posture and droplet shape to obtain the relationship between the composite arc current and voltage under the swing TIG,and to provide experimental data for further research.The effects of different welding parameters on the physical characteristics of the compound arc of the TIG-MIG rotating heat source with swing pendulum were studied.The increase of MIG current and TIG current is conducive to the increase of the arc space;the increase of the distance makes the two arc tail arcs longer and the arc stability changes;the increase of the swing amplitude expands the arc range.The MIG current increases with the TIG current,and the MIG voltage changes around 34V;the MIG current shows a downward trend in a small range with the increase of the swing amplitude,and the voltage changes little;when the spacing increases,the MIG current value tends to a single MIG The current value,MIG voltage appears to increase slightly.The UI change graph and UI random dispersion graph of MIG under TIG current parameters are analyzed.The increased TIG current can reduce the fluctuation of electrical parameters.The points in therandom dispersion graph tend to be concentrated,indicating that the rotating pendulum TIG arc is beneficial to improve the composite arc.Stability.Investigate the influence of process parameters on droplet transfer of TIG-MIG composite heat source.The swing of the TIG arc will change the droplet transfer method in the composite heat source.The change of the distance makes the droplet transition mode transition from jet to drop;the TIG current increases,and the transition mode of the droplet in the cycle changes from a mixed transition mode of jet transition,drop transition and a small amount of short circuit transition to a single jet transition;The increase of the pendulum speed will accelerate the transition between the droplet transitions;the increase of the swing amplitude increases the scope of the drop transition.Comparing the droplet transfer and weld formation of pulsed MIG-TIG and DC MIG-TIG under the same parameter TIG swing.The droplet transfer mode of the TIG-MIG composite heat source in the MIG pulse mode is expressed as a jet transition.The increase in TIG current promotes the transition frequency.The stability of the droplet transfer and the weld quality during welding are better than DC MIG-Welding seam under TIG composite heat source.The surfacing weld formation in pulse mode is as follows: the increase of TIG current and MIG current can increase the melting width and penetration depth,the increase of MIG current makes the residual height increase,and the increase of TIG current makes the residual height decrease;swing When the speed changes within a small range(0 ~ 160 ° / s),the melt width increases,but has little effect on the residual height and penetration depth;the spacing(5 ~ 7mm)makes the melt width increase,and when it exceeds 7mm,the change does not change much.The height and penetration depth decrease slightly with the increase of the spacing;When the welding speed is increased,the shape of the weld seam is obvious,and the quality of the weld seam gradually deteriorates.Welded TIG-MIG composite heat source welding was applied in narrow gap welding to verify the feasibility of the new process welding narrow gap.Welds can be shown as no obvious holes and no obvious gap between the molten pool and the two side walls.