板材多点成形过程中成形力的数值模拟

基于动力显式有限元格式,给出了多点成形中成形力的计算公式。对不同材料、不同厚度的圆柱面、球面及马鞍面三种典型形状的成形力进行了数值模拟,分析了成形力的变化过程及影响因素。结果表明:在成形过程中,随着基本体与板料接触数目的增多,成形力会越来越大。厚板成形、硬质材料成形时都将需要较大的成形力。由于变形的复杂性,成形双向曲率的目标面时所需的成形力明显高于单向曲率。这些结果对于选择多点成形设备、更好地控制板材多点成形过程以减少成形缺陷具有重要的指导作用。

Numerical simulation of forming forces in sheet metal multi-point forming process

Based on the dynamic explicit finite element scheme, the forming forces in the sheet metal multi-point forming (MPF) process were formulated.The forming forces for three typical shapes,i.e.cylindrical,spherical,and saddle surface of different materials with different thickness were simulated.The variation histories of the forming force were analyzed.The results indicate that the forming force becomes larger and larger along with the increase contacting punch number during the forming process.The forming force increases evidently with the sheet thickness and the relatively large forming force is needed if the material is stiffer.The forming force for the object with the surface of double curvature is obviously larger than that with single curvature due to the deformation of the former is more complex than that of the latter.These results are significant for choosing MPF press and controlling MPF process to alleviate forming defects.