粘塑性挤压成形变形规律研究

STUDY ON THE DEFORMING RULES OF THE VISCOPLASTIC EXTRUSION FORMING

为了寻求一种能全面揭示象等温和超塑性这类粘塑性复合挤压成形变形规律的方法，采用刚一粘塑性有限元对常温具有粘塑性行为的工业纯铅复合挤压进行了数值模拟。计算结果揭示了变形规律，如分流层的变化、速度场的分布、折叠缺陷的形成及原因等。计算表明，粘塑性复合挤压成形的最大变形区集中在凸模拐角处，变形分布梯度随着变形程度的增大而变小。增大变形速度、改善润滑条件有助于提高变形均匀性。对新旧网格的场变量传递、翻边现象的处理及初始速度场生成。

In order to find a method to reveal the deforming rnles of the viscoplastic extrusion forming such as the isothermal extrusion and superplastic extrusion etc. , the combined extrusion of industral pure lead which has viscoplastic behaviour at room temperalure has been simulated by viscoplastic finite element method. The calculating results bring to light the defotming rules such as the change of neutral layer position, the distribntion of velocity field and the cause of folding defect etc. On the basic of calculatingresults, It was found that the greatest deforming zone of viscoplastic combined extrusion is at the corner of punch bottom and the gradient of deformation distribution decreases with the deformation. The improvement of lubrication condition and the raising of deforelocity can ameliorale the deforming homogeneity.Some calculation problems snch as ming the generation of inifial velocity field, the treatment of folding and mesh rezoning had been treated effectively.