薄壁筒形件粘性介质外压缩径失稳起皱分析

缩径成形受筒坯稳定性的影响,容易产生失稳起皱,很难成形出缩径量较大的零件.提出了采用粘性介质外压缩径工艺成形直径变化量较大的薄壁异形曲面筒形零件新方法.针对坯料端部约束和自由条件下的失稳起皱问题进行了试验和有限元模拟,分析了试件失稳起皱过程中几何形状和应力的变化规律.研究表明,约束坯料端部可以改善试件失稳起皱后的应力分布规律,有利于消除褶皱,在较高粘性介质压力条件下可以直接成形出缩径量为15%的试件.

Wrinkling and instability analysis of thin-wall cylindrical parts in viscous medium outer pressure necking

Due to the influence of stability of cylindrical parts,necking process is subject to wrinkling and instability,and it is difficult to form parts with large necking scales.In this paper,a novel method of forming thin-wall special-shaped curved surface cylindrical parts with large diameter variation is proposed by using viscous medium outer pressure necking process.The wrinkling and instability processes of specimen with constrained and free ends are analyzed by experiments and finite element method,and the variation principles of geometrical shapes and stresses are studied.Results show that fixing the end conditions can improve the stress distribution of instable and wrinkling specimen and is benefitial to the elimination of wrinkles.Under the condition of high viscous medium pressure,the part with diametrical reduction of 15% can be formed directly.