Numerical Simulation Of Welding Assembly Discrepancies Of Automobile Panel

Welding process of Automobile Panel is the key working procedure in the manufacturing processes of the automobile body with its quality directly impact on the appearance and functionality of automobile. Welding quality control is one of the hot issues of the welding process. During automobile body assembly processes, the cause of discrepancies in the welding assembly can be part variation, assembly tooling variation, welding distortion and so on. As a major source of those discrepancies, variations in parts have an important effect on automobile body assembly quality.Springback is an unavoidable phenomenon for the Automobile Panel in stamping working procedure. Variations of pieces will cause great infection of the stress distributing inside welding assembly and change the shape of automobile body ultimately. Welding process of Automobile Panel is totally different from the traditional way which based on rigid pieces. The traditional "3-2-1" positioning is changed into "N-2-1" positioning with the large-scale coverage and flexible sheet. Such over constraints which targeted in the deformation of sheet metal at the same time add more factors to its internal stress state making springback more complex. Variation simulation analysis has been used in the design stage to predict such uncertainties, but variation analysis based on rigid body assumptions usually yields over-estimates of the assembly variations in the design stage. Three-dimensional structure of the welding fixture model is given accordance with the relevant components concern the structural characteristics of the welding fixture. In this paper, the cause of accuracy problem of welding assembly processes is studied first and the source of discrepancies in the welding assembly is reduced to: the variation caused by stamping process, the variation of welding assembly tooling, and the distortion caused by the spot welding process. In this paper, the quality problem of Automobile Panel caused by stamping process is analyzed in detail and Several control methods is offered relate to wrinkling, surface distortion, springback and other major issues concern surface accuracy.This paper presents a new numerical simulation method for the assembly process incorporating compliant non-ideal parts where pre-stressing are proposed to reflect the part variation and the node coupling method are used in the numerical simulation to predict the deformation caused by the welding process of Automobile Panel. After studying the welding process, we carry out numerical simulation of welding process based on the finite element of the back panel and rear section inner, and then predict the deformation of welding assembly process. Analysis and comparison with the experimental data showed that the simulation method is feasible.