管坯推压缩径端部翘曲机理及其影响因素分析

基于对管坯推压缩径的理论分析、试验研究和数值模拟,揭示出缩径时管坯端部存在翘曲的主要原因:管坯内外层缩径量不均匀,使得内层的轴向变形大于外层,导致变形后的管坯端部产生刚体转动,使其外径大于凹模出口处内径,产生翘曲,而且翘曲区的长度近似等于最初位于凹模锥口部分坯料流出后的长度;并分析了缩径率、缩径凹模半锥角、摩擦系数、缩径管坯初始壁厚对管端翘曲和轴向伸长率的影响规律。

Analysis of buckling in push-sinking and lts lnfluence factor

Based on the theoretical and experimental investigations and the numerical simulations of the push-sinking process, the paper finds the prime reason for the buckling in push-sinking is that the sinking deformation along the tubular wall is different and the axial deformation of the inner part is larger than that of the outer part. So rigid rotary movement appears in the end parts of the deformed tubular blank, which causes its external diameter larger than the die's and leads to buckling. The length of the buckling region approximates to that of the deformed part which originally locates in the die approach. In addition, this paper presents how the diameter reducing rate, the die semicone angle, the friction coefficient and the original wall thickness influence the buckling and the axial elongation rate.