薄壁铝合金管圆角模内翻成形性的若干判别式

基于薄壁管直角圆角模轴压内翻过程中各处应力及最终壁厚与管材特性、管坯尺寸、卷曲半径及摩擦条件之间的关系,推出了判别任一铝合金双层管件可否由特定尺寸圆管稳定内翻成形而不出现管壁干涉与塑性失稳问题的解析判别式,指出了确定薄壁管圆角模内翻卷曲半径或模具圆角半径极限值的方法.分析表明,选用包辛格效应较弱的管材且设法减小管与圆角模之间的摩擦系数有助于提高管件内翻成形性并增大卷曲半径的可用范围.在将所得判别式应用于两种铝合金管内翻情况下的分析之后得出的结论与相关文献中已有的实验结果吻合良好.

Some discriminants for the formability of thin-walled tubes of aluminum alloy in internal inversion process on fillet die

Based on the relations among the stress, final wall-thickness of thin-walled tube and the characteristics of tube material, original size, curling radius along with friction condition in a axially-compressed internal inversion process on right-angled fillet die, some analytical discriminants were established for judging if a double-layered tubular piece of aluminum alloy could be steadily formed from a certain-sized round tube via internal inversion process without interference and plastic instability of tube wall, and a method was put forward for determining the maximum and minimum usable curling radius or die fillet-radius for thin-walled tubes in the process. Analysis shows that choosing tube material with little Bauschinger effect and decreasing the friction coefficient between tube and die will help to improve the formability of tubes in the process and enlarge the usable range of curling radius. The analytical conclusions aiming at the performance of two kinds of aluminum alloy tube in the process are in good accordance with the acquirable experimental results in some references.