小直径厚壁管材变曲率弯曲回弹预测

摘要

为快速、准确地预测管材变曲率的弯曲回弹，建立变曲率弯曲回弹预测的解析模型。基于ABAQUS平台建立小直径厚壁管材变曲率弯曲成形及回弹数值模拟模型，通过试验验证了所建模拟方法的可靠性。将变曲率回弹问题转化为离散定曲率回弹问题进行研究，通过近似纯弯曲回弹实验，建立管材定曲率弯曲回弹前后半径之间的函数关系式，将变曲率弯管轴线双圆弧拟合逼近离散，针对离散化的回弹弯管进行G1连续拼接，依据轴线复杂程度，构建拼接修正函数，建立管材变曲率弯曲回弹预测解析模型。通过2个试验算例验证该解析模型能够有效预测小直径厚壁管材平面变曲率弯曲回弹。回弹的准确预测是有效控制弯管回弹缺陷的前提，用于指导后续模具型面修正，补偿回弹误差，保证弯管几何精度。%To predict the springback of variable curvature tube forming quickly and accurately, mathematic analytic model for springback prediction of variable curvature tube bending is established. Using software ABAQUS, the bending and springback processes of minor diameter thick-walled tube are simulated to reveal the springback laws, and the accuracy and reliability are proved by experiments. First, the springback of variable curvature tube bending is transformed into discrete constant curvature problem and the mathematics relationship of the radius before and after springback can be built by the approximate pure bending springback experiment. Then the tube axis is segmented with biarc-curve fitting, merged with first-order geometric continuity, and compensated with modified function according to the axis complexity, to establish mathematic analytic model for springback prediction of variable curvature tube bending. Finally, the feasibility, reliability and accuracy of the model are proved. This model is useful for the maintenance of the bending die and will ensure the requirements of geometric accuracy of the variable curvature tube bending.