Research On Welding Method Of Feeding Flux Bands Constrained Arc Ultra-narrow Gap

Due to the advantages of high production efficiency,low heat input,small welding deformation and excellent joint performance,ultra-narrow gap welding has a wide application prospect.As one of the ultra-narrow gap welding methods,flux bands constrained arc ultra-narrow gap welding has been widely used in rail butt welding,X70 pipeline steel butt we lding,cast steel valve ring welding and rail and frog butt welding.In order to further improve the process adaptability,this paper developed a feeding flux bands constrained arc ultra-narrow gap welding method.A welding torch and a test system were designed to realize the feeding flux bands constrained arc ultra-narrow welding.The process test was carried out by using this system.The influence of process parameters on arc heating characteristics was studied,and the appropriate matching range of process parameters was determined.The influence of process parameters on the droplet transfer mode was analyzed,and the optimal droplet transition form in the feeding flux bands constrained arc ultra-narrow gap welding was obtained.The main conclusions are as follows:(1)A feeding flux bands constrained arc ultra-narrow gap welding method was developed.This method further improves the utilization rate of flux bands,expands the matching range of welding process,and optimizes the stability of welding process by automatic feeding of flux bands.(2)The feeding flux bands constrained arc ultra-narrow gap welding torch is designed,which is mainly composed of the conductive structure of the welding torch and the flux bands conveying mechanism.This welding torch realizes the integrated design of the conductive structure of the welding torch and the conveying mechanism of the flux bands,improves the automation degree of the welding device and increases the stability of the flux bands conveying.A new type of flux bands was designed to ensure that the feeding flux bands constrained arc ultra-narrow gap welding can be carried out smoothly.(3)By studying the influence of process parameters on arc heating characteristics,it is found that when the welding voltage is constant,with the increase of flux feed rate,the weld width and side wall melting height decrease,and the bottom melting width and bottom melting depth increase.A good weld can be obtained by reasonably matching the relationship between flux feeding speed and welding voltage.(4)By studying the influence of process parameters on droplet transfer mode,it is found that the internal mechanism of welding voltage affecting droplet transfer is that it causes the different melting amount of arc to the flux bands,which leads to the change of the interaction between the flux bands droplet and the wire droplet.In addition,during the slag wall transition,the welding process is stable and the weld forming quality is excellent.