钢管热连轧过程横断面壁厚变化的三维有限元模拟

针对20号钢Φ119.0mm×9.25mm规格全浮动芯棒无缝钢管8机架连轧过程进行了有限元模拟仿真分析,得到了热连轧管各机架出口等效塑性应变以及荒管壁厚变化情况,分析了轧制力和芯棒力的变化特点。研究表明,连轧管减壁量和外直径变化主要集中于开始第1~第6个机架,在第7、第8机架减壁作用很小,最终荒管壁厚均匀,且形状圆整。稳定连轧阶段的轧制力依轧制顺序呈递减趋势,第7、第8机架轧制力很小;同时芯棒力大于各机架轧制力,钢管内壁承受的作用力和塑性应变较大,应对芯棒表面进行合理润滑。模拟得到的壁厚、外径及轧制压力与实测结果吻合较好。

Finite element analysis of wall thickness changes of the cross section of seamless tube in hot continuous mandrel rolling

The eight-stand hot mandrel mill rolling of Ф119.0mm×9.25mm tube of 20steel is simulated by using 3-D thermo-mechanical coupled FEM.Equivalent plastic strain distribution at the cross section and wall thickness at exit of each pass as well as rolling force,mandrel force are simulated.The simulated results show that the decrease of wall thickness and outer diameter are mainly finished in the initial the 1st to 6th pass and there is a very small change of wall thickness in the 7th and 8th pass,which is helpful to controlling the precision of the product.During the stabilizing continuous rolling process the rolling force decreasing along the rolling sequence is very small at the final the 7th and 8th pass.The mandrel force which is larger than the rolling force at every pass can give rise to a corresponding larger load and plastic strain between the inner wall and the surface of mandrel,thus there is a necessity of adopting proper lubrication technology for the floating mandrel.Simulated wall thickness、outer diameter and rolling force are a good agreement with the measured results.