锥台形壳体液压胀形过程的数值模拟

等边双圆锥台壳体具有形状简单、容易制作的优点,常用于小直径球形容器的无模成形。但在成形过程中,壳体赤道环焊缝处极易向内收缩,从而引发该处的失稳起皱,严重影响了球形容器的质量。针对这一问题,用刚塑性有限元对壳体在内压作用下的胀形过程进行了数值模拟,在此基础上,对锥台形壳体的初始形状进行了改进,以限制赤道环焊缝处向内的收缩。数值模拟结果表明,改进后的初始壳体既具有形状简单的优点,又能避免赤道处的起皱,且能获得圆度较好的球形容器,而这是等边双圆锥台壳体自由胀形所无法实现的。

NUMERICAL SIMULATION FOR THE HYDROBULGING PROCESS OF FRUSTUM SHELLS

Being of simple shape and can be easily produced, equilateral frustum shells are often used as initial shells for the dieless hydroforming of small diameter spherical vessels. But in the forming process, equator of the shell tends to withdraw inwards and therefore creates wrinkles here, which badly affects the quality of the vessel. Pointing to this problem, rigid plastic finite element analysis is employed to simulate the hydrobulg-ing process of the shell under internal pressure, then some modifications for the initial shape of the frustum shell are presented to restrict withdrawing of the equator and to prevent it from wrinkling. Results of the simulations show that the modified frustum shell is both simple in shape and effective in anti-wrinkling, and has the capability to obtain a really round vessel which is not possible with an equilateral frustum shell.