Study On Simulation Of Heat Transfer And Weld Shape Of Rotating Arc In Gmaw Process

Rotating arc sensor with the unique ability of anti-magnetic field, anti-arc, and resisting high temperature resistant, is always consistent with the welding arc. The rotating arc sensor can be used as real-time seam tracking and has the prospect of industrial application. Current research mainly focuses on the technology of seam tracking, while there are few studies on the welding heat transfer and welding shape of rotating arc sensor. Due to the complexity of the rotating arc welding and lots of welding parameters, it will take high human and material resources if only using welding test to select the optimal welding process parameters. Therefore, it has important theoretical and practical engineering significance to use the numerical simulation and optimization technology to research three-dimensional transient temperature field and three-dimensional dynamic process of transient pool under rotating arc welding GMAW (Gas metal arc welding) thermal process. This technology is important to master rotating arc welding method for weld forming rules and intelligent optimization for the extensive use of rotating arc sensor technology.According to the characteristics of rotating arc GMAW, three heat source models (Gaussian heat source model, double elliptic heat source model and double ellipsoid heat source model) were used for low carbon steel Q235-A work pieces. The welding temperature distribution and molten pool shapes were analysied by numerical simulation and then the numerical simulation results of weld shape were compared with experimental results of actual welding. The results show that the shape and size of the weld is agreed well with the simulation results by using Gaussian heat source model. Then, Gaussian heat source model was used to study 3D transient temperature distribution and 3D transient pool. The thermal cycle curve and parameters of a few specified points on work pieces were calculated by means of numerical simulation. By comparison, the calculated thermal cycling curve coincides well with experimental results which provided the foundation of analysis on welding metallurgy and the control of welding microstructure.Based on the ANSYS software and second developing platform, a further research was done with APDL parametric programming technique on welding thermal process of different rotating arc welding parameters GMAW to obtain the influence law on 3D transient temperature field and 3D transient pool caused by processing parameters such as welding current, welding voltage, welding speed, the rotation radius, rotating frequency and rotation direction, which was a theoretical basis in the selection of technological parameters on rotating arc in GMAW.In order to quickly and easily obtain optimizing welding process parameters and get rid of the bondage of the experience of welding design in practical applications, the BP network was adopted here to construct a forecast model to predict the relationship between welding parameters and weld size. On this basis, the genetic algorithm is used to global optimization and find out the best welding process parameters and then the correctness of the optimization process parameters is verified by experiment.The rotating arc sensor was used in welding experiments and the welding joint was observed in macroscopic and microscopic observation by microscope. The results showed that the weld reinforcement of rotating arc sensor welding is lower than that of normal linear motion welding and its transition is smoother. Different process parameters of rotating arc welding affect the welding joint microstructure, which directly related to the thermal cycling curve of rotating arc welding. Mechanical properties and hardness experimental research on the welding joint of rotating arc sensor were processed. The results showed that:the welding joint using the parameters got by the optimization model can meet the requirements of the mechanic performance and welding quality is eligible.