不同模具组合对0Cr21Ni6Mn9N不锈钢管数控弯曲成形质量的影响

采用有限元法研究了不同模具组合下0Cr21Ni6Mn9N不锈钢管数控弯曲应力应变分布、壁厚变化和截面畸变规律。研究结果表明：在弯曲模、夹块和压块组成的基本模块的基础上，添加防皱块会导致等效应力、切向拉应力和切向拉应变增加，而切向压应力、等效应变和切向压应变减小；添加芯棒会导致切向应力和等效应变减小，而等效应力和切向应变增大；同时添加防皱块和芯棒则会导致等效应力、切向应力和切向应变增大，而等效应变减小。添加防皱块会导致弯管截面畸变率增大，但对壁厚变化率影响不大；添加芯棒能够有效抑制弯管截面畸变，且壁厚减薄率仅为9.0%~9.15%，远小于15%的航空标准。综合考虑0Cr21Ni6Mn9N不锈钢管数控弯曲成形质量和生产成本，可确定出最优的模具组合为弯曲模+压块+夹块+芯棒。

Effects of Different Die Sets on Forming Quality of 0Cr21Ni6Mn9NStainless Steel Tube during NC Bending

The laws of stress/strain distribution, wall thickness variation and cross section deformation of 0Cr21Ni6Mn9N stainless steel tube during NC bending under different die sets were studied by using the finite element method. The results show that adding a wiper die to the base die set including bending die, clamp die and pressure die increases the effective stress, tangential tensile stress and tangential tensile strain, but decreases tangential compressive stress, effective strain and tangential compressive strain; adding a mandrel to the base die set decreases the tangential stress and effective strain, but increases effective stress and tangential strain; adding the wiper die and mandrel simultaneously to the base die set increases effective stress, tangential stress and tangential strain, while decreases the effective strain. Adding the wiper die increases the cross section deformation ratio, but has no obvious effects on wall thickness variation ratio; adding the mandrel can restrain cross section deformation effectively, and the wall thinning ratio is far less than 15% of the aviation standard, which is only 9.0%~9.15%. Considering the forming quality and cost of 0Cr21Ni6Mn9N stainless steel tube during NC bending, the optimal die sets are bending die, pressure die, clamp die and mandrel.