铝合金圆管拉伸外翻成形过程模拟研究

Investigation on axial drawing external inversion process of aluminum alloy tube by numercial simulation

拉伸外翻可以克服轴压失稳、翻管件尺寸精度不理想等问题。本文采用Deform-2D商业软件对铝合金圆管拉伸外翻成形过程进行数值模拟,观察了成形过程中材料流动情况和等效应力的分布,分析了管坯相对厚度和凸模圆角半径对翻管工艺力的影响。结果表明:翻卷过程中金属材料以较大的速率从内孔内壁流向凸模圆角处,并在凸模圆角入口处速度达到最大值;外筒外壁处材料处于等效拉应力状态,而内孔内壁处材料等效应力基本为零;对于几何尺寸规格一定的管坯,存在一个最佳拉伸外翻凸模圆角半径,当设计的凸模圆角半径等于该最佳值时,翻管工艺力最小。

The problems of buckling and inaccuracy of invertube size can be overcame by axial drawing external inver- sion. The deforming process of aluminum alloy tube was analyzed by commercial software Deform-2D, the material flow in the forming process and the stress distributions were observed, and the effects of relative thickness ratio and punch fillet radius on forming loads were also analyzed. The results show that the material flow speed of the inner wall is of a greater rate, and reaches to its maximum at the entrance of the punch fillet. The material state at outer tube wall is in the equivalent tensile stress zone, while the stress at inner wall is almost zero. For tube of regular specifications, there is a best punch fillet radius for axial drawing external inversion. When the punch fillet radius equals to the opti- mal value, the forming load will be the minimum.