Optimization And Numerical Simulation Of Welding And Forming Process Of Steel Frame

With the development and promotion of green building and building industrialization,the use of prefabricated components has gradually become the mainstream form of the construction industry.As the skeleton of prefabricated building,the quality of formed steel skeleton plays an important role in prefabricated components.The reinforcement framework is mainly composed of main reinforcement and stirrup.At present,the mainstream reinforcement framework is still formed by binding and manual spot welding,which not only has the defects of large size deviation,but also takes time and effort in quality control.At the same time,it is difficult to ensure the unity and stability of the quality of the welding point.As the key technology in the production line of steel frame welding,automatic welding plays an important role in the forming process of steel frame.Various factors involved in the welding process will become the key to affect the quality and efficiency of the whole steel frame production.Therefore,it is of great significance to optimize the key technology and process of automatic welding of reinforcement framework.In this paper,through experimental research and numerical simulation,the welding parameters of CO₂ shielded welding and the quality of welding skeleton under different stirrup welding sequence are studied respectively,and the skeleton welding process is optimized:(1)According to the national quality standards,the welding process of stirrup in the welding process of reinforcement framework forming process and the welding process engineering and quality of its quality inspection and overall framework forming should be designed according to the process.(2)Through numerical simulation and experimental research,the parameters of CO₂shielded welding in steel skeleton forming welding were optimized.The numerical simulation results show that:the more heat input during welding,the greater the impact on the model,the lower the yield strength of the model,the lower the elongation after fracture,but the length of welding time affects the size of the heat affected zone,under the same total heat input,the shorter the time,the more concentrated the heat,the greater the impact.Secondly,the specific parameters are optimized through experiments:the test results show that the welding current has the greatest influence on the excellent rate,followed by the welding time,and finally the welding voltage;and when the welding current,welding voltage,and welding time parameters match 315A,30V and 1.2s,the excellent rate of welding reaches the theoretical optimal value of 87.045%.(3)In order to optimize the welding sequence of the reinforcement framework,a three-dimensional finite element model of the reinforcement framework with 6 main bars is established to simulate the welding process of the reinforcement framework under three different welding schemes(scheme 1:first weld the upper and lower four welding points,and then weld the middle two welding points;scheme 2:weld the middle two welding points,and then weld the upper and lower four welding points;scheme 3:weld the six welding points at the same time)Stress,the welding residual stress and strain were analyzed and compared to select the best welding scheme.The results show that the residual stress mainly appears at the solder joint,and the maximum stress of the solder joint near the clamping end is 216.20MPa.The thermal deformation caused by welding has little effect on the overall size.Compared with scheme 1 and scheme 3,the welding quality of reinforcement framework after welding in scheme 2 is better.Through the research of this paper,the purpose of improving the mechanical properties of welded steel skeleton is achieved from the perspective of process optimization,which has certain significance for promoting the development of automatic welding technology of steel skeleton and green industrial building.