Mechanical expanding of tube with conical die was investigated, stress state of unit in deformation zone was analyzed, unit model of deformation zone was established, slab method to solve deforming force on metal plastic forming was adopted, according to Mises yield criterion, considering effects of work hardening and bending stress, analytic formula of the mechanical expanding was derived. Moreover, the formula was amended by taking account of effect of fixing-diameter zone.The amended formula indicate that expanding force is related to die semi-cone angle, friction coefficient between die and tube internal surface, original diameter of tube, tube thickness, expanding coefficient and length of die’s fixing-diameter district. The rationality and correctness of expanding force formula were proved by expanding tests.

研究了管材锥形模机械扩径的特点,分析了扩径过程中变形区的应力状态,建立了变形区单元体模型。采用金属塑性成形中求解变形力的主应力法,根据Mises屈服准则,考虑材料的加工硬化和弯曲应力的影响,推导出了机械扩径力的解析公式。在此基础上,考虑定径区摩擦力的影响,修正了计算公式,所得结果表明扩径力和扩径模具半锥角、模具与管材之间的摩擦因数、管材原始直径、管材壁厚、扩径系数以及模具定径区长度有关。扩径试验证明了扩径力公式的合理性与正确性。

 

锥形模, 机械扩径, 扩径力, 主应力法