曲面件柔性拉伸成形时的过渡区

利用多夹钳式拉伸成形机能够实现夹持和拉伸成形的柔性化特点,对投影面为梯形的曲面件分别建立矩形板料和梯形板料夹持有限元模型,并进行了不同过渡区的矩形板料和梯形板料的数值模拟.结果表明,随着过渡区最大长度的减小,板料容易贴模,成形力减小,成形件的最大应变值减小,有效成形区应变、厚度分布更均匀,成形效果更好.对投影面为梯形的曲面件进行拉伸成形实验,实验结果与数值模拟结果吻合,验证了数值模拟的正确性.多夹钳式拉伸成形机能够根据模具形状合理设计过渡区形状,提高成形质量,节省材料,降低拉伸成形成本.

Transition Zones in Flexible Stretch Forming for Surface Parts

According to the characteristics that the multi-gripper stretch forming machine can realize the flexibility of clamping and stretching， finite element models of rectangular and trapezoidal sheet metal were built for surface parts of trapezoidal projection plane， and numerical simulations of different transition zones for rectangular and trapezoidal metal sheets were conducted. The results showed that with the decrease of the maximum length of the transition zone， the conformability of the sheet metal to the forming die was increased， the forming force together with the maximum strain of the formed parts decreased while the strains and thickness of the effective forming zone distributed more uniformly and the formability was much better. Stretch forming experiments were done for the surface part of trapezoidal projection plane， and the experimental results were coincident with the numerical simulation results， which proved the validity of simulation. The multi-gripper stretch forming machine can reasonably choose the transition zone shape according to the shape of forming die， which improves forming quality and reduces the material and stretch forming costs.