数值模拟的双层金属板拉深成形工艺研究

某轿车排气歧管保护罩采用双层镀铝钢板同步拉深工艺制成,为获得最佳成形工艺参数,避免拉深时产生严重减薄及起皱现象,采用Dynaform软件对双层金属板同步拉深成形过程进行了有限元数值模拟,分析了压边力对拉深成形过程的影响,获得了不同压边力下保护罩内、外层板的壁厚减薄与增厚分布规律。结果表明,与单层板拉深成形相似,对于复杂型面双层金属板拉深件而言,单纯增加压边力并不能完全避免拉深过程中的起皱现象;采用压边力及合理布置拉深筋,可以保证内、外层板材料塑性流动均匀,有效抑制起皱、拉裂等缺陷。根据数值模拟结果进行了产品试制,获得了质量合格的拉深件。

Research on drawing process of two layer sheet steel based on numerical simulation

The protective cover of automobile exhaust manifold consisted of two layer aluminium coated sheet steel is formed by the synchronous drawing process.The drawing process of the two layer aluminium coated sheet steel was simulated by the Finite Element Analysis(FEA) software Dynaform,to obtain the optimized processing parameters and to prevent the serious thinning and wrinkling during drawing.The effect of Blank Holder Force(BHF) on the drawing process was analyzed,and the distributions of thickness thinning and thickening with different BHFs were obtained.The results show that,similar to the deep drawing of single layer sheet,wrinkling can’t be prevented completely by increasing BHF only during deep drawing of complex profile part of double layer sheets.The uniform plastic flow of material in both inner and outer sheets during drawing can be guaranteed,and the wrinkling and cracking defects can be prevented completely by using BHF combining with a reasonable layout of drawbead.The drawing experiment was carried out according to the simulation results and the qualified drawn workpiece were obtained.