Research On Dynamic Process Behavior Of Flux Bands Constricting Arc Welding Sandwich Panel Based On Vision

High-strength steel sandwich panels have great application prospects in aerospace,rail transportation,shipbuilding and other fields due to their advantages of light weight,high strength,and impact resistance.Aiming at the welding process problems of high-strength steel sandwich panels,this paper uses the flux bands constricting arc(FBCA)welding method to obtain a well-formed T-joint(the most basic unit of the I-type metal sandwich panel).In FBCA welding high-strength steel sandwich panels,the welding dynamic process behavior such as arc behavior,droplet transfer mode and welding molten pool behavior are the key factors affecting welding stability and welding quality.This article uses high-speed camera system,electrical signal acquisition system to collect real-time welding process information and use image processing algorithms to quantitatively study the dynamic process behavior of welding,and initially obtain the relationship between image feature parameters and welding stability and welding quality.This research lays a foundation for the quantitative research of welding arc and molten pool behavior based on vision system,and provides a theoretical basis for real-time control of FBCA welding process and engineering application.Firstly,analyze the flux bands and FBCA welding arc spectrum,preprocess the image and establish a characteristic parameter system.The TG-IR analysis of the flux bands shows that:the flux sheet decomposes mainly in the form of water vapor and CO ₂,and the conductivity is only 0.7 S/m,which can effectively prevent the arc climbing problem in narrow gap welding and optimize the weld formation.Through the arc spectrum collection,650 nm,810 nm wavelength filters and 650 nm wavelength laser backlight were determined,which laid the foundation for the construction of the test system and the development of the test.Set up an electrical signal acquisition system and a high-speed camera system to study the state of flux bands,the arc behavior and the droplet transfer mode of FBCA welding,The results show that:in the set welding parameters,FBCA welding has short circuiting transfer,globular transfer,repulsion transfer,slag wall transfer,fine droplet transfer,mesos-pray transfer,projected transfer and Arc bridge coexistence transfer,the flux bands state has small particle,large particle,liquid bridge and arc bridge coexistence,and the arc restraint effect increases in sequence.On the basis of obtaining the arc image,the relationship between arc behavior and welding stability is further analyzed by discussed the image characteristic parameters.when the average arc width-to-height ratio is greater than 1.00,the arc restraint degree is greater;when the arc width-to-height ratio variation coefficient is less than 13.55,the arc fluctuation is small and the welding process is stable.By comparing the above research with the corresponding relationship of the joint morphology,When the droplet transfer mode is Arc bridge coexistence transfer,and the flux bands is arc bridge coexistence shape/liquid bridge shape,the arc is compressed,the heat is concentrated,the combustion process is stable,and the joint quality is the best.Furthermore,the morphology of molten pool directly above was collected,and the characteristic parameter changes of the molten pool topography and the weld morphology were analyzed.The results showed that change the welding parameters,the weld has unfused,no penetration,over penetration,penetration and mixed states.when the weld pool width is less than 5 mm,the weld is unfused;when the weld pool length is less than 24.27 mm,the weld pool width is greater than 5 mm and less than8.62 mm,the weld is not penetrated;when the weld pool length is greater than 25.49mm and less than 33.16 mm,the weld pool width is less than 10.68 mm,The weld is partially penetrated;when the weld pool length is greater than 37.14 mm,the weld pool width is greater than 11.77 mm and less than 12.62 mm,the weld is in a penetration state,and the comprehensive application of molten pool characteristic parameters can reflect the quality of the weld.Based on the analysis of the morphology of molten pool directly above,an innovative method for collecting the topography of the side molten pool with high-temperature resistant quartz glass instead of the side wall constraints of the panel is proposed.By extracting the edge curve of the molten pool and normalizing it,analyze the characteristic parameter changes of the molten pool in the core plate,and the results show that the edge fluctuation degree of the molten pool in the core plate exists:short circuiting transfer>globular transfer>slag wall transfer/globular transfer>repulsion transfer>fine droplet transfer>projected transfer/mesos-pray transfer>arc bridge coexistence transfer/globular transfer>arc bridge coexistence transfer.As the oscillation angle of the molten pool changes,the edge curve of the core plate molten pool appears a mixed U-shape(86.36°<average value of the molten pool oscillation angle<117.34°),deep U-shape(average value of the molten pool oscillation angle<81.56°)and shallow U-shape(average value of molten pool oscillation angle>126.17°),and the stability of the welding process is successively enhanced.When the edge curve of the molten pool presents a shallow U shape,the arc continues to burn,the arc force acts evenly,the welding process is stable,the weld seam is penetrated,and the quality is the best.