汽车覆盖件用5B003A板拉伸实验及成形性的有限元分析

Tensile Tests and Finite Element Analysis of Formability of Automobile Covering Sheet Steel 5B003A

目的研究汽车车身用5B003A板的成形性能。方法在进行单轴拉伸试验的基础上,利用软件eta/DYNAFORM模拟了板成形极限曲线、破裂点应变路径、圆筒拉深过程,并进行了相应变形参数的优化。结果 5B003A板单向拉伸和有限元模拟均出现"交叉颈缩"现象,并且在与轧制呈45°角方向上的冲压性能优于0°和90°方向;5B003A板成形极限破裂点的应变路径漂移倾向较明显,双拉区中均呈ε2=const的应变状态;在与拱顶高实验相近变形条件下,优化得到最佳凸模圆角半径为20 mm时,与极限拉深系数0.43对应的无凸缘拉深的最大板坯尺寸为233 mm,相应最佳压料力为68 kN。结论 5B003A板在45°方向上有较好的冲压性能,且凸模圆角半径、板坯直径、压料力等工艺参数对其拉深成形性能影响较大。

Objective To study the formability of automobile covering sheet steel 5B003A. Methods Using the software eta/DYNAFORM, experiments including the simulation of sheet metal forming limit curve, strain paths in the fracture posi- tion and cylindrical deep drawing process and the optimization of concerned deformation parameters were carded out on the basis of uniaxial tensile tests. Results It was revealed that the phenomenon ＂cross-necking＂ appeared in both uniaxial ten- sile tests and finite element simulation, and the stamping formability in a 45° angle with the rolling direction had better performance than 0° and 90°. Strain paths of the fracture point tended to drift obviously, and double pull area showed a strain state of ε=2 ： const. In deformation conditions similar to the limit dome height test, while an optimal punch fillet radius of 20 mm could be obtained after optimization, the minimal drawing rate was 0.43 and corresponding maximal slab diameter of no -flange drawing was 233 mm with the most appropriate binder forth of 68 kN. Conclusion The sheet 5B003A exhibited good stamping formability in 45° direction, and processing parameters, like punch fillet radius, slab diameter and binder forth, had great impacts on its drawing formability.