Study Of Droplet Transfer And Formation's Experiment Of Welding Joint In Plasma-MIG Welding

Plasma-MIG welding is a kind of advanced welding-method,which uses plasma-arc and MIG-arc burning in the same blowtorch,so that weld-penetration and melting-width are properly distributed,and we can get high welding quality and efficiency.This article establish a simple model of Plasma-MIG welding compound arc,using the method of mathematical description to analyze the force on melt drop when it transfer,and improved the welding gun structure,analyze behavior of the Plasma-MIG welding droplet transition and welding joint forming using the improved welding gun, and made the contrast with the MIG welding situation.First,on the basis of a simple model of Plasma-MIG welding compound arc, analyze the force situation on melt droplet.The proper assumption and the numerical description of droplet transfer and stress were established by analyzing mechanical behavior of droplet transfer in hybrid welding process.Then,in view of the question which appeared in the earlier experiment,improve the gun structure.Improve the upper structure and inner and outer nozzle structure;increase circle insulation in the external nozzle inner.Assemble and debug welding system.Finally,experimental study Plasma-MIG welding different forms character of metal transfer.Including the arc voltage waveform,critical current of metal transition,weld joint forming situation.Using electron microscopy to analysis different line energy of weld joint,including organization analysis and flaw analysis.Analyzes the difference between Plasma-MIG melt drop transition and MIG welding,research the influence of plasma arc joining to melt droplet transition and its influence to the weld joint forming. The results show that:Primary droplet transition in Plasma-MIG weld is guttate transition and jet flow transition;The critical current of guttate transition to jet flow transition is approximately 280-300A;Compared with MIG welding,Plasma-MIG remarkable reduce the critical current of guttate transition to jet flow transition; Compared with MIG welding,Plasma-MIG welding have big superiority in penetration and welding joint width aspect,Plasma-MIG welding is a highly effective welding method.