杯形件等温压扭复合成形模具失效分析及改进

摘要

为解决7A60铝合金杯形件等温压扭复合成形实验中凹模的早期失效问题,借助DEFORM有限元软件,从工艺特点、应力分布及模具结构等方面详细探讨和分析失效原因,应力集中、冷热循环热应力以及高温模具氧化是导致凹模转角处发生早期破裂的主要原因.基于"未裂先分"的方法对凹模结构进行改进,结果表明:模具改进效果较好,等效应力极值降低30%,有效避免了凹模的应力集中;杯形件成形效果较好,宏观上无明显缺陷,表层金属流线清晰可见.%To solve the forming die's early failure of 7A60 aluminum cup in the twist-pressure isothermal composite formingexperiment,withthe use of finite element software DEFORM,a detailed discussion and analysis of the cause of failure is studied in terms of the technical characteristics,stress distribution and mold structure.The results show that the main reasons which cause the early rupture at the corner of the die arethe stress concentration,hot-cold cycle thermal stress and the oxidation of high-temperature mold.Then based on thetheory of "no crack first division",the structure of the die is improved.Finally,the results show thatthe improvements of die effectively avoid the stress concentration and reduce the equivalent stress extremes by 30%.The metal flow lines are visible on the surface of cup with no obvious defects.