Design And Applicability Analysis Of Narrow Gap TIG Welding Torch For Oscillating Art

In recent years,the use of large wall thickness steel structure is increasing in petroleum and petrochemical industry,construction machinery,nuclear power,ocean engineering and other industrial fields.Compared with the traditional "V" groove,the use of narrow gap "U" groove has great advantages in saving cost and reducing labor time in the welding of large thick wall steel structure.Narrow-gap TIG welding completely inherits the characteristics of traditional TIG welding,such as low heat input,fewer welding defects,beautiful weld appearance,high arc stability and automatic welding at all positions.Especially suitable for chemical industry oil and gas pipeline docking,nuclear power main road,while drilling logging tools and other parts requiring high welding quality.This paper designs a TIG welding torch with a height of 100 mm,a width of 120 mm,and a thickness of 8mm with a narrow gap.On the premise that the structure of the welding torch is restricted by a narrow space,the function integration of conduction,cooling,wire feeding and air feeding is realized,and the stability of the welding process is verified through experiments.This paper uses Solidworks Simulation software to analyze the temperature field under the cooling condition of air forced convection and get the temperature gradient of each part of the welding gun body under the action of welding current.The flow state of protective gas has an important influence on the stability of welding arc.Using CFD computational fluid dynamics software Fluent,based on the flow field of the traditional TIG welding gun,the optimized design is carried out for the gas channel and outlet layout of the welding gun protection.In order to obtain a larger pool width,the welding test system adopts the way of swinging arc welding.The arc swing mechanism controls the servo motor through the Elmo driver,which is set as a displacement ring(UM=5).By programming in Elmo Studio,the arc periodic swing and the tungsten pole positioning function after welding stop are realized.In the swing ARC welding test of narrow gap TIG welding gun,the swing range,swing speed and side wall residence time are taken as the main parameters.The results show that when the swing period is constant,the weld width and side wall depth are positively correlated with the arc swing amplitude,the weld residual height and groove depth will decrease to a certain extent with the increase of the swing amplitude,and the fish scale pattern on the weld surface becomes more dense.Through single-pass multi-layer welding in narrow gap groove,after 7 passes surfacing welding,the section weld with beautiful appearance was obtained.Through the micro-hardness measurement,the changes of hardness values in each area of the weld were observed.The vickers hardness in the weld core area was higher on the whole,reaching 320 HV on average,and the average hardness value of the base metal was 140 HV.The welding test shows that the TIG welding torch with narrow clearance can achieve high quality swing ARC welding.