对矩形铝型材的三维拉弯工艺进行研究，提出了一种适用于三维拉弯、具有可重构性的柔性拉弯模具设计方法．通过在矩形型材内填充钢块来抑制截面凹陷，并以减小型材回弹前后对应节点的位移偏差和截面凹陷为优化目标，建立了矩形型材柔性三维拉弯成形工艺的多目标优化模型．采用拉丁超立方抽样和响应面法建立优化的代理模型，结合非支配遗传算法进行多目标优化全局求解．有限元模拟和实验结果表明: 柔性模具可以较好地完成三维拉弯; 填充钢块的方法可以有效地抑制截面凹陷，优化后的预拉量和补拉量的组合可以较好地同时控制回弹和截面凹陷，使之同时达到允许范围．

This paper deals with the three- dimensional stretch- bending forming process of rectangular hollow alumi-num profiles,and devises a die design method for the reconfigurable flexible three- dimensional stretch bending.Then,a method of filling blocks of steel into the profiles is proposed to suppress sagging,and a multi- objective optimization model of the forming process is constructed with a springback function and a sagging function as the multi- objective function.Finally,an optimized agent model is constructed by using the Latin hypercube sampling and the response surface method,and the multi- objective optimization of the global solution is carried out by combi-ning the non- dominated sorting genetic algorithm.The results of both the finite element simulation and the experi-ments show that (1) the flexible die can achieve a better three- dimensional stretch bending; (2) the method of filling blocks of steel can effectively suppress sagging; and (3) an optimized combination of pre- stretch and post-stretch can significantly reduce the springback and the sagging,thus,enabling both to reach the allowable range at the same time.