管材弯曲回弹对内高压成形的影响及补偿方法

摘要

The springback of CNC bending reduces accuracy of tube bending, which leads to the wrinkle during subsequent hydro-forming, and to avoid the defect during hydro-forming, springback compensation is necessary. In this paper, theoretical model of tube plastic bending and strain hardening model of materials were set up firstly, and then the value of springback angle was derived. Meanwhile, several groups of experiments were carried out, and linear fit formula between springback angle and bending angle based on mathematical statistics was also obtained. Finally, the hydro-forming experiments show that the wrinkle can be avoided by springback compensation during CNC bending, and the dimensional accuracy of hydro-formed sub-frame is acceptable.%管材数控弯曲后的回弹严重影响试件成形精度，容易导致弯曲管内高压成形过程起皱缺陷。为了补偿回弹，避免内高压成形过程的缺陷，首先建立管材塑性弯曲理论模型以及材料的弹塑性线性强化模型，通过理论解析得到弯曲回弹量表达式；其次对实验过程中不同弯曲角度下的回弹量进行线性回归分析。拟合结果表明：理论上对于回弹角的预测是合理的；同时将理论预测得到的回弹量补偿到管材数控弯曲过程，消除弯曲管内高压成形过程起皱缺陷，得到尺寸精度合格的试件。