Abstract: According to the research of tool pre-assembly in automotive body panels forming simulation, three preconditions for effective automatic assembly algorithm are presented：Normal consistent algorithm, definite tool property and correct initial normal direction; the automatic assembly algorithm based on the background mesh projection is also presented. Nodes of sheet and tools are projected and distributed onto background mesh along the overall normal direction, and according to the corresponding relation between tools, sheet and background mesh the minimum values of tool nodes and sheet elements are calculated, thereby determining the distance that tools need to be moved. Ultimately, the correct assembly is accomplished automatically. The algorithm eliminates the coupling relationship between stamping type and stamping direction to improve the adaptability of the program and efficiency of the algorithm, it also simplifies the user operation. The practice in the complex industry model proves the feasibility and efficiency of the new self-assemble algorithm satisfying the requirement of the automotive body panels forming simulation.

Key words: Automatic assembly, Finite element method, Mesh generation, Stamping