圆筒件拉深成形临界防皱变压边力加载曲线研究

针对板料拉深成形过程中如何最优控制压边力的难题,文章首先从理论上分析了圆筒件拉深成形过程中法兰上任一点处的承载能力,建立其应力应变平衡关系,从而得到法兰上任一点处的瞬时径向拉应力和周向压应力公式;其次结合法兰起皱有关能量守恒定理和Hill厚向异性理论,推导出了包含摩擦系数和板料厚向异性系数在内的法兰起皱临界最小压边力公式,并分析了各种拉深成形工艺参数对此法兰起皱临界最小压边力大小的影响规律;最后应用数值模拟软件eta/DYNAFORM验证此临界变压边力加载曲线的可行性,并修正其表达形式。最终板厚变化量的均方差计算结果表明,理论推导的起皱临界最小压边力修正加载曲线,不仅比常见的最小压边力恒定加载模式更节省能量,而且其厚度分布也更加合理、均匀。

The study of load curve of critical wrinkless variable blank holder force in the process of deep drawing cylinder parts

In this paper,in order to solve one Gordian knot of how to optimized control blank holder force (BHF) in the process of sheet deep drawing,some theoretic analyses about carry capacity of one point on the surface of flange during the whole process of deep drawing cylinder parts were carried out firstly,and then real-time radial pull-stress and circumferential compress-stress formulas about random point on flange could be concluded out by the way of building corresponding stress-strain balance relations.By the aid of consulting correlative energy conversation theorem and Hill anisotropism theory when wrinkling,one minimum wrinkless variable BHF expression including friction coefficient and thickness anisotropism coefficient could be ratiocinated out,and then some corresponding influencing disciplines of all kinds of forming parameters on this expression were analyzed.In the end,numerical simulations were adopted to validate the feasibility of this load curve of variable BHF and revise it.Final computation results showed that this revised minimum critical wrinkless variable BHF curve could save more outer energy and conduce to more uniform in thickness distribution after calculating mean square deviation of thickness variation with final parts.