Analysis On Molten Pool Information And Welding Quality Control In Micro-Plasma Arc

As a kind of small current welding method and with the advantages of fast welding speed,narrow weld,small heat affected zone and small welding deformation,micro-plasma arc welding is widely used in ultra-thin plate,wire mesh and other parts of the welding.The causes of easily burnt defects of ultra-thin plate welding are discussed,partly because of the large welding heat input quantity,on the other hand is due to the too small welding speed,causing the concentrated arc force per unit time of molten pool.The shape of the welding seam is determined by the shape of the molten pool,which determined by the welding heat input and arc force.At the same time,liquid metal flow plays an important role in the process of welding on melting,vaporization,interfacial reaction and curing of a series of complex physical processes,affect the morphology and quality of the final welding seam.Therefore,the research on the weld pool shape and flow detection using the molten pool visual sensing method is of great significance to the quality control of ultra-thin plate welding.To obtain the image of weld pool using active vision sensing technology,image processing and analysis the relationship between weld pool shape and fluidity and welding parameters based on the control and provide an important basis for the welding quality is the main content of this study.Based on the thin plate weld pool size less than 2 mm,using high resolution CCD camera and telecentric lens,and the use of laser as back light with filter,a two-dimensional active pool visual sensing system,the system can filter out the electric arc interference strongly,collecting image information to the content of ultra-thin in abundant micro plasma arc welding pool.Secondly,the influence of CCD camera mounting parameters,shooting parameters,laser parameters and welding parameters on the weld pool image information is discussed.Then the weld pool image feature parameters were extracted in molten pool collected image contains a lot of noise,using MATLAB software to preprocess the image of weld pool,and use the two values of demising and edge extraction algorithm based on the extraction of the weld pool,the shape feature parameters with ellipse fitting equation,using the extracted image sharpening algorithm of weld pool image flow information after oscillation parameters.In the non-mobile micro-plasma arc under the effect of the weld pool shape parameters with the welding current changes with the increase of the current,the heat input and arc force increases,the width,length and area of the molten pool is large.When the molten pool is melted,the oscillation wavelength increases sharply.With the increase of welding time,the oscillation wavelength increases slowly and then decreases.In the mobile micro plasma arc under the action of combined with welding thin plate mobile micro plasma arc welding,welding current and welding speed were tested as variables,simultaneously sampling the image of weld pool,the relationship between the welding width and weld forming and welding parameters of molten pool through the analysis,by adjusting the different the welding parameters to obtain good weld shape and appearance,provide the basis for the control of welding quality.