Modeling and experiment for the roller hemming of variable curvature aluminum alloy panel with adhesive

Abstract

The autobody closures have high requirements on the appearance accuracy of A-class surfaces, smooth contours, and continuous edges, so the forming quality of the autobody closures has long been the center of attention in the roller hemming process. To facilitate weight reduction in automotive manufacturing, lightweight materials such as aluminum alloy and hemming adhesive are commonly used. However, the heterogeneous coupling effect between the adhesive and aluminum alloy panel during roller hemming can significantly influence the forming quality of the panel. Additionally, the precision of the roller posture and trajectory plays a crucial role in determining the final quality of the panels, given the complex geometry of the autobody closures. Therefore, in order to continuously improve the forming quality of the autobody closures, this paper investigates the roller hemming process applied to variable curvature panel with adhesive on autobody doors. Firstly, the kinematic model for the roller posture and trajectory during roller hemming of the curved surface-curved edge panel was developed based on differential geometry theory. Secondly, a simulation model for roller hemming of the panel with adhesive was established using the finite element method and the smoothed particle hydrodynamics method (FEM-SPH). The validity of the simulation was confirmed by comparing the simulated results with experimental outcomes. In the experiment, the algorithm for solving the posture and trajectory of the roller was applied, and the forming quality of the panel was evaluated by using the two indexes of roll-in/out coefficient and surface wave coefficient. Thirdly, the impact of the hemming factors on surface wave and roll-in/out was analyzed using the response surface methodology, leading to the development of a mapping relationship between the hemming factors and forming quality. This study provides valuable support for predicting the forming quality of variable curvature panels with adhesive and continuously improving the forming quality of autobody closures in the roller hemming manufacturing process.