Microbeam Plasma Arc Welding Gun Structure Design

The configuration deviation of civil aircraft engine blade is usually caused by airflow scour,external impact and other reasons during service,more than 40% of the current engine maintenance is the using hot surface technology to repair engine blades,the use of surfacing technology to restore blade shape size can effectively reduce engine maintenance cost,reduce aircraft elapsed time.Plasma surfacing has the advantages of small plasma diameter,high energy density and large depth and width ratio,and is widely used in the welding of titanium nickel alloy.In this paper,the design of micro-beam plasma arc welding torch is studied.The overall design of micro-beam plasma torch and the nozzle of key energy-changing parts are effectively analyzed.The temperature of the nozzle of key energy-changing parts greatly affects the lifetime of the torch during the welding of micro-beam plasma arc welding torch.Based on Fluent simulation software,the law of heat transfer and flow of plasma nozzle was simulated,the flow field and temperature field were analyzed,and the effect of velocity of micro-beam plasma nozzle on plasma arc compression was studied.The structure parameters of plasma gun nozzle,compression ratio,compression angle and steady-flow section parameters are changed,and the flow field changes are compared.The results show that the compression ratio L/d=1,compression angle 45 degrees and steady-flow section length 2.6 mm meet the design requirements of theoretical dimension parameters,which provides a favorable basis for the design of plasma gun.A micro-beam plasma arc welding gun with contact heat transfer is designed.The cooling channel of the lower gun body extends downward,which enlarges the area of contact heat dissipation,thus reduces the heat conduction travel of coolant and improves the cooling effect of the micro-beam plasma gun nozzle.The tungsten pole centralized locking device consists of tungsten pole clamp,centralized jack and centralized sleeve,which can ensure that the tungsten pole and the nozzle are coaxial.So that the plasma torch can be welded stably.Through the experimental test of the formed welding torch,the results show that the plasma arc is stable and non-offset during welding,and the surface of the welded joint is free of cracks,pore and collapse,which meets the technical requirements of the engine maintenance manual.