| As an important means of energy-saving and emission reduction, light weight of automobile body has been highly identified and valued by many automobile enterprises at present. Due to various parts of the body, the recognition of "applying suitable materials to right place" has become a development direction of light weight. In the future, the automobile body will be made of steel, aluminum alloy, magnesium alloy and other lightweight materials, which can satisfy the requirements like light weight, safety and manufacturing cost. This kind of automobile body development will become the main stream direction. The aluminum steel thin plate connection has become the primary assembly method of multi material mixed with the body. However, it is difficult to control the dimensional quality of assembly because of the huge difference between the deformation index, linear expansion coefficient, thermal conductivity and other material properties. Therefore, studying on deformation law and control method of aluminum steel sheet welding processes is an urgent matter.This paper verifies the correctness of the finite element simulation analysis through sheet assembly experiment. Based on above, analyzing various factors which has impact on welding deformation by means of finite element simulation, then a response surface model of welding deformation was constructed, finally applying anti-deformation method to reducing welding errors. The specific contents are as follows:(1) Welding assembly test of steel-aluminum sheetsThe ranges of welding parameters of three steel-aluminum sheets were determined by bisection method. Then, the welding parameters were selected to carry out physical experiments. Before the test,disposing welding parts and reasonable designing the welding fixture could effectively improve the quality and reduce welding deformation. Through the welding test, observing panel size and welding deformation. At last, tensile test was conducted on welded plates. The morphology welded pieces which was observed under a microscope could comprehensively assess the quality of welding.(2) The spot welding simulation analysis of steel-aluminum sheetsAccording to the results of the aluminum sheet assembly test, applying the finite element simulation of the welding analysis software(SYSWELD). In this paper, the method of thermal-electric-force direct coupling is used to analyze the field of temperature, stress strain and deformation displacement. By carefully analyzing the different cloud charts of typical moments, comparing the shape and size of the weld to the experimental results, thus the correctness and effectiveness of the simulation model is verified. Based on above, by designing combination schemes of experimental parameters by the control variable method, the relationship between the welding parameters and deformation can be studied systematically, thus it provide theoretical foundation for effective control of welding deformation.(3) The deformation response surface model of spot welding of steel-aluminum sheetsThe response surface model of the steel-aluminum between welding deformation and welding parameters is established based on the least square method. Based on the model, the welding deformation control of the typical Z type sheet parts of the automobile body is analyzed. By adding certain amount of welding deformation opposite to the deformation direction before welding, the deformation of the welding deformation is reduced, which indicates that the model can effectively reduce the welding distortion.The research findings of this project can be applied not only controlling welding deformation of aluminum and steel sheet, but also in the future be expanded to other dissimilar materials such as magnesium-aluminum, magnesium-steel, titanium-steel, which are widely used in sheet manufacturing industry of the automobile body, fuselage, wings, hull and so on. The project has a great scientific research value and broad application prospect in engineering. |
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