任意形状坯料反挤流变成形内圆筒上限单元技术的改善分析

提出了对任意形状坯料的反挤流变成形内圆筒的运动许可速度场改善．在以前各种著作中出现的速度场不满足在模具和材料接触面的法线速度必须为零的条件,而且忽略了冲头下面的材料旋转．同时对前者进行了修正,对后者以一种新的速度场进行了改进．得出的挤压载荷的理论计算值比文献中出现的低,且更接受实验结果,同时平均挤压高度与实际情况相吻合．

A MODIFIED ANALYSIS OF THE BACKWARD RHEOLOGICAL EXTRUSION OF INTERNAL CYLINDER FROM ARBITRARILY SHAPED BILLETBY THE UPPERBOUND ELEMENTAL TECHNIQUE

Amodified kinematical admissible velocity field for the backward rheological extrusion of internal cylinder from arbitrarily shaped billets is proposed. The original velocity fields appearing in the liberature is not satisfied for the condition that the normal velocity on the die and material infterface must be zero, and material rotation under the punch was neglected. Therefore, in work the former is corrected and the latter is improved by a new velocity field. The theorelical predictions of extrusion load are lower and closer to the expermental results than those in the previous literature. when using the proposed velocity field, the average extruded height of theory is in an excellent agreement with experiments.