Study On The Arc Physics Theories Of Self-Shielded Flux-Cored Wire

Arc physics theories of welding wires, which include the metal transfer mode, the physical mechanism of metal transfer and spatter and characteristics of electric arc parameters etc., is one of the most important guiding theory to enhance the level of operational behavior of welding wires as well as the theory for scientific and quantitative evaluation of its operational behavior.Through the high speed camera and Hanover analyzer, this thesis, taking self-shielded flux cored wire as the subject, studies the model of metal transfer, the spatter mode and the electrical parameters based on three different self-shielded flux cored wire. Furthermore, the present experiment studies the droplet transfer form, the spatter form and the electrical parameters of self-shielded flux cored wire under different welding conditions. In addition, the experimental study discusses the mechanism of metal transfer and the stability metal transfer of the self-shielded flux cored wires.The results reveal that bridging transfer without arc interruption which includes bridging explosive transfer without arc interruption and bridging surface tension transfer without arc interruption, droplet transfer and explosive transfer are the main transfer models for self-shielded flux cored wire; explosion spatter, spatter created by arc force, bubble release spatter, droplet flying away weld pool and spatter flying away weld pool are the most spatter forms for self-shielded flux cored wire.With the current increases, the proportion of bridging explosive transfer without arc interruption increases, the ratio of bridging surface tension transfer without arc interruption first increases under220A then decreases, the percentage of droplet transfer go down; the proportion of explosion spatter and bubble release spatter increase under220A then decrease, the ratio of spatter created by arc force growes up, and the percentage of droplet flying away weld pool make a decline.With the electrode change, the proportion of bridging explosive transfer without arc interruption increases, the ratio of bridging surface tension transfer without arc interruption decreases, and short-arc welding appear; the proportion of explosion spatter and droplet flying away weld pool decrease, the ratio of spatter created by arc force and bubble release spatter grow up.The arc physics characteristics of the self-shielded flux cored wire are analyzed further by analyzing self-shielded flux-cored arc welding voltage and current waveforms and its probability density distribution and its frequency distributions of the short-circuiting time T1. On the base of processing the data offered by the Hannover Analysator, arc stanbility is judged by the made arc U-I graphs, the voltage standard deviation ΔU and coefficient of variation δu, the current standard deviation ΔI and coefficient of variation δ1. It showes that the approximate entropy of arc voltage can be used to analyzed the stability of metal transfer. Through the high voltage rate of more than30V∑n(UB), spatter degree of self-shielded flux cored wire can be anlyzed quantificationally.