薄壁管缩径挤压工艺的模拟分析与应用

Simulation and application of extrusion-sinking technology for thin-walled tube

薄壁管缩径挤压成形过程可分为刚性滑入、缩径变形、反弯曲和挤压四个阶段。满足刚性滑入的动力学条件为tg（90°－α）≤tg。当总的缩径变形比n总大于其极限变形比n极时，需多次缩径，且每次缩径比n应小于n极。采用刚塑性有限元法对缩径变形过程进行计算机模拟，可得到管壁轴向剖面上网格变形和应变分布以及载荷位移曲线，与实验结果吻合程度高；采用主应力法和修正的Tresca屈服准则，可分别导出缩径成形力和壁厚变化规律的计算公式。采用这种工艺可节省材料，提高生产效率和零件的质量及性能。

The process of extrusion-sinking for thin-walled tubes can be divided into four stages: rigid sliding, sinking, backbending and extrusion. The critical angle α of the rigid sliding is tg(90° -α )≤tg. When the total ratio of sinking deformation n_t is larger than that of the critical deformation n_l, multi-sinking is demanded and every sinking ratio n should be less than n_l. By using tLhe rigid-plastic finite element method, the sinking process is simulated by computer, thereby the mesh deformation and stress-strain distribution along the axial section of the tube wall and the load-displaecement curve are obtained, and the calculated results show little difference from the test results. In addition, the equations for calculating the sinking force and wall change are derived by using the slab method and the modified Tresca yield criterion. By using tLhe above-mentioned technology, both the quality and Properties of the compoent parts can be improved.