大口径316L不锈钢管数控弯曲回弹规律研究

Springback laws of large diameter 316L stainless steel tube in NC bending

针对Φ123 mm×3.97 mm×350 mm规格的大口径316L厚壁不锈钢管,基于显/隐式弹塑性有限元仿真结合实验研究,对其数控弯曲卸载后的回弹现象进行了研究.采用单向拉伸试验和三维数字散斑动态应变测量方法获得了大口径316L不锈钢管大应变范围(真应变为49.02%)的力学性能参数,通过摩擦磨损实验获得管材316L不锈钢与45钢模具材料在不同压力和转速条件下的摩擦系数.基于ABAQUS平台,建立了大口径316L不锈钢管弯曲、抽芯、卸载回弹全过程数控弯曲有限元模型,并实验验证了所建模型的可靠性.研究表明,大口径316L不锈钢管回弹现象显著,在350 mm弯曲半径(相对弯曲半径D/t为2.846)条件下达到7.2°左右.芯棒伸出量e、芯球个数n和弯曲角度θ对卸载回弹有显著影响.

Combined with the Explicit/Implicit finite element （FE） simulations and experiments, the spring- back phenomenon of large-diameter 316L stainless steel tube with Ф123 mm × 3.97 mm ×350 mm （ tube di- ameter× thickness x bending radius） under Numerical Control （NC） Bending is investigated. The dynamic three-dimensional digital speckle strain measurement method and uniaxial tensile tests are used to obtain the mechanical properties of the 316L tube with large strain. The twist-compression test is performed to estimate the friction between 316L tube and die under different pressure,rotation speed and lubrication conditions. Under ABAQUS platform, a 3D FE model is established to simulate the tube bending, ball retracting and unloading of 316L tube, which is validated by the experimental results. The results show that the maximum springback angle is 7.2 °. The mandrel extension length （e） , number of balls （n） and bending angle （θ） have significant effects on the amount of springback .