铝型材构件多点变曲率拉弯制件回弹研究

目的 研究不同预拉伸量和补拉伸量对矩形变曲率构件回弹的影响，以提高柔性三维拉弯成形精度。方法 用有限元模拟了矩形变曲率铝型材三维拉弯成形过程，并用试验验证了有限元模拟的精度，设计了5组不同的预拉伸量参数和补拉伸量进行三维拉弯成形有限元模拟。结果 大曲率和小曲率段试验和有限元模拟的回弹误差小于2 mm，表明有限元模拟分析可以很好地对矩形变曲率构件进行模拟。得出的数据表明预拉伸量对于小曲率弧段回弹的影响比对大曲率弧段的影响更大，当预拉伸量增长到1.0%以后，回弹的下降幅度不再明显;随着补拉伸量的增大，变曲率拉弯制件两段的回弹均得到较好的抑制，当补拉伸量为1.4%时，制件靠近夹钳端出现了缩颈缺陷，产生了较大的质量缺陷。结论 研究证明适量增加预拉量和补拉量能有效减小柔性三维拉弯成形回弹。

Springback of Multi-point Variable Curvature Stretch Bending Component of Aluminium Profile

The paper aims to study the effects of different pre-stretching and post-stretching bending on springback of rectangular variable curvature components to improve the forming accuracy of flexible 3D stretch bending. The 3D stretch bending process of rectangular variable curvature aluminum profile was simulated by finite element method, and the accuracy of finite element simulation was verified by experiments. Five groups of different pre-stretching parameters and post-stretching stretching amount were designed to simulate the 3D stretch bending forming. The springback error of large curvature and small curvature section experiments and finite element simulation was less than 2 mm, which showed that finite element simulation analysis can simulate rectangular variable curvature component well. The results showed that the influence of pre-stretching on the springback of small curvature arc section was greater than that of large curvature arc section. When the pre-stretching amount increased to 1.0%, the decrease range of springback was no longer obvious; with the increase of post-stretching bending amount, the springback of two sections of variable curvature stretch bending parts were better. The results showed that the necking defect appeared near the clamp end of the profile when the post-stretching bending amount was 1.4%, which resulted in a large quality defect. The results show that the springback can be effectively reduced by increasing the amount of pre-stretching and post-stretching bending.