中文摘要：

对宽板自由弯曲成形及弹复过程进行理论分析，将弯曲过程分为板料未包覆凸模和已包覆凸模两个成形阶段，在每个成形阶段将弯曲板料分为弹性和弹塑性变形区。基于单向应力和小变形假设，分别建立了两个成形阶段的回弹计算模型，导出了任一成形阶段中性层上任一质点卸载前后的转角和弯曲半径数学表达式。基于VC＋＋软件平台，对回弹计算模型进行编程计算，并进行了实验验证，计算结果与实验结果吻合较好，最大误差为0．58°。

英文摘要：

With theoretic analysis on the forming and springback processes for sheet metal forming, the sheet metal air bending process can be divided into two stages including one stage of not wrapping the sheet about the punch surface and the other stage of having wrapped up the punch surface. In each forming stage, the deformed region of the sheet metal is considered to be composed of elastic region and elastic-plastic region. Using the assumptions of uniaxial stress and the little deforming theory, the analytical model of springback prediction is constructed. The equations for the rotation angle and radius of each point in neutral surface for any bending process are derived. The code is developed to calculate the springback amount based on VC＋ ＋ program. The air bending experiment is conducted to verify the validation of the theoretic model of springhack prediction. The comparison shows that the theoretical results of springback prediction fit well with experimental data and the maximum error is O. 58°.