缩径区形状对粘性介质外压缩径成形的影响

Influence of the shape of necking area on the necking of viscous medium by outer pressure

文章针对筒坯直径、缩径区长度及缩径区长径比(缩径区长度与筒坯直径的比值)等参数对粘性介质外压缩径成形的影响,采用理论分析、有限元分析和试验方法进行研究,得到了不同缩径区形状条件下的筒坯表面积变化及对缩径变形方式的影响规律。研究结果表明,在缩径区长径比在0～0.71范围内,筒坯表面积存在由减小向增加转变的"临界缩径量",使缩径变形方式由压缩类变形转变为伸长类变形,有助于极限缩径量的提高。

The paper focuses on analyzing the influence of the parameters of necking area on the necking of viscous medium with outer pressure. The parameters include diameter of the tube-blank, length of the necking area and the length-to-diameter ratio （ratio of necking length to the diameter of tubular blank）. Finite element methods, theoretical analysis and experiments are adopted respectively, by which the variation rules of the surface area of the tubular blank under different shapes of necking area and the influence of latter on necking deformation manners are obtained. The results show that, there is a critical necking point at the range of the length to-diameter ratios from 0 to 0.71, where the variation of the surface area of the tubular blank turns from decreasing to increasing. As a resuh the deformation mode would turn from compression to tension which is beneficial for increasing the necking limit.