基于有限元法的拉伸弯曲矫直过程板形控制分析

 板形是带钢质量的重要判定指标,常见的板形缺陷有边浪、中浪、1/4浪等,其实质是残余应力在带宽上的分布不均。拉伸弯曲矫直机通过张力辊组、弯曲辊组和较真辊组的共同作用,使带钢在低于屈服强度的张力作用下发生塑性延伸,从而有效消除浪形缺陷,改善板形,提高带钢质量。然而在拉伸弯曲矫直机的设计和使用过程中,对拉伸弯曲矫直机参数的调整多基于经验,缺少理论指导。为了定量分析拉伸弯曲矫直机参数对浪形缺陷的改善效果,使拉伸弯曲矫直机在实际生产中发挥更好的作用,以某1 450 mm带钢酸洗冷轧生产线上的拉伸弯曲矫直机为研究对象,使用有限元软件ANSYS/LS-DYNA基于三维弹塑性有限元法建立了拉伸弯曲矫直机模型,对拉伸弯曲矫直机矫直过程进行了模拟,分析了张力和插入深度对初始浪形分别为边浪和中浪的带钢矫直后板形的影响规律。结果表明,经过拉伸弯曲矫直的带钢浪形缺陷得到显著改善;插入深度和张力对初始浪形缺陷分别为边浪和中浪的带钢板形的影响规律一致;3个辊组中矫直辊组的插入深度是影响带钢板形的主要因素,随着矫直辊组插入深度增大,带钢矫直后板形由边浪转变为平直,且随着矫直辊插入深度进一步增大,板形又由平直转变为边浪;随着入口张力增大,带钢矫直后板形由边浪转变为中浪。

Flatness control analysis of tension levelling process based on finite element method

Flatness is an important index to judge the quality of strip steel. The common flatness defects are edge wave,middle wave,quarter wave and so on,which is essentially the uneven distribution of residual stress in the bandwidth. Wave defects can be effectively eliminated by the joint action of tension roller, bending roller and straightening roller. In the straightening process,plastic elongation occurs on strip under the effect of tension which is below yield strength. The flatness and quality of strip can be significantly improved. However,in the design and application of the tension leveler,the adjustment of tension leveler parameters is mostly based on experience and lacks theoretical guidance. To quantitatively analyze the improvement effect of tension leveler with different process parameters on the straightening of wave defects and increase the straightening effect of tension leveler in actual production,the tension levelling process of strip steel in a 1 450 mm cold pickling-rolling line was analyzed by the finite element software ANSYS/LS-DYNA which based on the three-dimensional elastic-plastic finite element method. The influence of tension and roll-intermesh on the flatness of straightened strip with initial flatness defect was analyzed. The influences of intermesh and tension on the flatness of strip with initial edge wave or middle wave shape defects are consistent. The results shown that wave defects of strip steel can be significantly improved by tension levelling. The intermesh of straightening roll is the main influencing factor,with the increase of intermesh the type of strip defect changes from edge wave to straight,and with the further increase of intermesh for straightening roller,the edge wave defect appeared again. With the increase of inlet tension,the type of strip defect changes from edge wave to medium wave after tension levelling.