Research On The Application Of Laminar Plasma In Welding

As a new type of heat source,laminar plasma has the characteristics of long jet length,low temperature gradient,and good controllability.It has been applied in thermal processing such as spraying,metal heat treatment,cutting,etc.The application of welding is in a blank.Laminar plasma as a good processing heat source has a good application prospect in welding.Therefore,the application of laminar plasma in the field of medium and thick plate welding has been studied.This article first introduced the laminar plasma device and tested the effect of plasma gas flow and current on the arc length.It was found that when the plasma working gas is 9L/min(where the Ar:N2 ratio is 2:8)and the current is 150 A,the laminar plasma arc length can reach 748 mm,far exceeding the arc length of an ordinary plasma arc.In addition,by testing the external characteristics of the laminar plasma power supply,it is verified that it has a good constant current characteristics and meets the requirements of laminar plasma welding for power supply.In order to facilitate the determination of the welding process parameters,the arcing heights of laminar plasmas under different argon gas flow rates,different non-transferred arc currents,and different transfer arc currents were also tested,and the maximum arcing height of the laminar plasma was found to be 100 mm.Above the arc starting height of a normal arc.Based on the previous study of laminar plasma-related basic properties,laminar plasma single-pass welding experiments were performed.This article first demonstrated that laminar plasma infusion welding has the ability to form welds.Secondly,in the laminar plasma pinhole welding experiments,it is found that it is difficult to perforate and it is easy to burn through after perforation.Based on the two welding methods and using the features of good laminar plasma collimation,this paper introduced the laminar plasma fusion wall welding concept.The laminar flow plasma fusion wall welding process of 12 mm and 15 mm thick Q235 A steel plates was studied under the condition of not opening the groove and maintaining a certain clearance.The influence of different welding parameters on the weld forming was analyzed.Studies have shown that laminar plasma has the ability to form welds in this case.The weld width is nearly uniform across the weld and the back of the weld is well formed.However,the surface of the weld seam is recessed and it is necessary to fill in the weld metal to obtain a complete weld seam.In view of the characteristics of MIG welding with large filling volume and small spatter,this paper introduced the welding concept of laminar plasma-MIG welding.By adjusting the MIG welding wire feeding from the side of the weld,when the height of the plasma torch is 30 mm,it achieves no slope cutting,one-time penetration of a 12 mm thick Q235 A steel plate with 2 mm clearance is reserved.