中文摘要：

方管的双辊交互式成形模式（Roll—Box）是一种新的圆成方成形模式．将共旋构架下材料客观性本构模型引入大变形弹塑性动力显式有限元算法，选用解析法描述轧辊，并推导出与其对应的接触算法，建立了双辊交互式成形方式有限元仿真模型，对圆成方再成形过程进行仿真．通过分析壁厚变化、周向收缩（拉伸）和应力等变形情况，为双辊交互式成形模式的实现提供了试验和理论基础．

英文摘要：

Roll-Box is a new forming mode of producing square steel tubes. In order to research the new mode, a large deformation elastic-plastic FEM model was developed by introducing objective constitutive model of rotational formula into the dynamic explicit FEM. Meanwhile, analytical method was selected to describe the surface of rollers and the corresponding contact algorithm was introduced. The roll forming process of ＂round to square＂ was simulated, and the change of wall thickness, stretch/ shrink ratio and stress of inner and outer surface were investigated, which provides guideline for experiment and theory to realize the new mode in workplaces.