厚壁管温热缩口与管壁增厚的数值模拟研究

目的主要研究厚壁管两端同时温、热锥形缩口工艺的特点,以及缩口过程不同工艺参数对壁厚增厚的影响。方法通过选择合理的材料模型与热力耦合等温度场模拟参数,建立了有限元模型,使用DEFORM体积成形软件对厚壁管两端同时温热缩口工艺进行了分析,探究了温、热缩口两种条件下应力应变分布特点。结果模拟实验获得了管材缩口系数、模具半锥角、t/d0值、摩擦因子、成形温度等工艺参数,在温、热两种条件下对壁厚增厚量的影响曲线。结论管材缩口过程具有典型的变形阶段:入锥弯曲阶段、反弯曲阶段和缩口稳定阶段;管材高温下缩口变形特点为周向、轴向的压缩变形和径向的增厚变形;厚壁管缩口的增厚变形量随着模具半锥角的增大和缩口系数的减小而增大,同时受摩擦因子、成形温度、管材壁厚的影响较大。研究结果为管材缩口壁厚增厚工艺提供了基础技术数据。

Numerical Modelling Study on Warm-Hot Necking and Wall Thickening of Thick-Walled Tubes

Objective This study mainly focused on the characteristics of cone-shaped necking process under warm or hot conditions of the thick-walled tubes at both ends, and the impact of different process parameters on the wall thickening. Methods Through choosing reasonable temperature field simulation parameters such as material model and thermomechanical coupling, etc, a finite element model was built. Based on the DEFORM bulk forming software, the simultaneous warm-hot necking process at both ends of the thick-walled tubes was analyzed, and study was carried out on the strain stress distribution characteristics under warm or hot conditions. Results The influence curves for the impact of factors such as tube necking coefficient, half cone angle of mold, t / d0 value, friction factor and forming temperature on wall thickening amount were obtained from simulation experiments under warm or hot conditions. Conclusion Tube necking process had typical deformation phases, including cone bending stage, anti-bending stage and stable necking stage. The characteristics of tube necking deformation under hot conditions were circumferential, axial compression deformation and radial thickening deformation. With the increase of cone angle of mold, and the decrease of necking coefficient, the thickening amount of thick-walled tubes increased, besides, the thickening amount was influenced by friction factor, mold temperature and wall thickness of the pipe. The research results provided basic technical data for the thickening of the wall thickness of the tube necking process.