基于绕弯成形工艺的铝型材截面优化研究

异形多腔铝型材在绕弯成形区会出现严重的截面畸变,截面两侧形成宽度差,不满足平面度要求.为解决这一问题,本文采用数值模拟和实验的方法,对绕弯成形特性进行研究,并通过优化截面特征减小了成形后两侧面的宽度差.研究表明:仿真能够有效预测实际成形状态,成弧半径值、包角值及回弹角值的仿真与实际误差分别为6.7％,0.5％和11％.成形区仿真与实验所得外弧面宽度分别为79.42及79.00 mm,内弧面宽度分别为82.76及82.90 mm,误差为0.17％.通过优化产品截面得出:增强壁厚的方式不能够抵抗成形过程中立筋向内倒塌的趋势;采取增加微小凸台的方法,使得成形后右侧面宽度差由1.60 mm减小为0.90 mm,左侧面宽度差由1.74 mm减小为0.50 mm,两侧凸台能够有效地抑制立筋向内倒塌.经分析凸台位置最大主应变为0.21,未超过材料延伸率22％,满足强度要求.在8％的增重比约束范围内,优化方案增重1.8％,明显提升了成形工艺性.

Research on section optimization of aluminum profiles based on rotary-draw bending process

Serious section distortion and width difference exist on both sides of the section in the winding forming area, which cannot meet the requirement of flatness. To solve this problem, the characteristics of winding forming were studied by numerical simulation and experiment. The width difference of the two sides after forming was reduced by optimizing the section feature. The results show that the simulation can effectively predict the actual forming state.The simulation error of arc forming radius, the included angle,and the springback angle were 6.7%, 0.5%, and 11%, respectively. The outer cambered widths obtained by simulation and experiment in the forming area were 79.42 and 79.00 mm, respectively;the inner cambered widths were 82.76 and 82.90 mm, respectively, with an error of 0.17%. Optimization of the cross section shows that wall thickness could not resist the collapse trend of the neutral reinforcement in the forming process. By adding a boss, the width difference of the right side after forming was reduced from 1.60 mm to 0.90 mm, and that of the left side was reduced from 1.74 mm to 0.50 mm. Both sides of the boss could effectively restrain the vertical bars from collapsing inward. Analysis indicate that the maximum principal strain of boss position was 0.21, and its elongation did not exceed 22% of that of the material, which meets the strength requirement. Within the limit range of 8% weight gain ratio, the weight gain of the optimized scheme was 1.8%, and the formability was obviously improved. This study provides the basis and guidance for the winding forming of special-shaped multi-cavity aluminum profiles.