大径厚比薄壁封头多约束旋压成形方法

Spinning with multi-constraint for large-diameter to thickness ratio and thin-walled spherical head

大型薄壁封头具有大径厚比、弱刚性的特点,利用传统旋压加工方法易出现起皱等失稳现象。依据中心约束旋压法的成形缺陷,从能量法及金属塑性变形理论方面提出了多约束旋压新工艺方案,分析表明:多约束多道次配合作用能够增加工件成形的约束能,有效抑制法兰外缘起皱现象,成形件径厚比大,表面光洁度良好。通过逆行工程软件Poly Works进行模型重构,得到实际加工样件母线方向的壁厚数据,其壁厚分布规律表现为两端欠减薄,中间部分过减薄,旋压终端由于约束作用,壁厚增厚明显。正负壁厚偏差比稳定在15%以内,壁厚均匀性良好。

Large thin- walled spherical head is of large-diameter to thickness ratio and weak rigidity,therefore,it is easy to appear wrinkling by traditional spinning. The scheme of multi-constraint spinning was put forward based on the energy method and the metal plastic theory as well as the forming defects of central constraint spinning. The analysis shows that the synergistic effect of multi-constraint and multi-pass can increase the energy constraint in the forming process of workpiece,and effectively restrain the wrinkling in the outer flange.So the forming part is of large-diameter to thickness ratio and good surface smoothness. The model is reconstructed by reverse engineering software Poly Works to obtain wall thickness data of the actual sample along the generatrix direction with the distribution of lack thinning at both ends and over thinning at the center. However,due to the strong constraints,the terminal is thickened significantly. The deviation ratio of positive and negative wall thicknesses is less than 15%,so the uniformity of wall thickness is well.