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钢板异步轧制弯曲方向演变及机理分析

Evolution and mechanism analysis of bending direction of steel plates during asynchronous rolling

  • 摘要: 目前异步轧制工艺参数与轧板弯曲行为间的研究结论存在矛盾且弯曲机理不明确, 本文以08Al钢板为对象, 结合有限元模拟与轧制试验, 系统研究了轧制参数对异步轧制钢板弯曲行为的影响规律与机理。基于ABAQUS软件建立轧制模型, 通过分析应力演化及应变率带分布特征揭示轧板弯曲及反转行为机理。结果表明, 变形区等效塑性应变率带呈"X"形分布, 且应变率带数量与压下率呈正相关, 与初始板厚呈负相关。异步轧制使上下表面中性点移动形成搓轧区, 为平衡搓轧区存在引发的力矩, 上下表面轧制压力错位分布形成反向力矩稳定轧制过程, 导致出口处应变率带分布不对称, 从而引发板材弯曲, 弯曲方向与前滑区应变率带数目相关。当前滑区仅存在1个"X"形应变率带时, 在异步效应主导下轧板向快速辊弯曲。在异速比较小时, 随着压下率的增大或初始板厚的降低, 前滑区应变率带增多, 此时异步效应减弱, 仅影响中性点附近应变率带分布, 出口前新增应变率带经动态调整后使轧板向慢速辊弯曲; 当异速比持续增大时, 异步效应增强, 轧板转而向快速辊弯曲。本研究可为异步轧制板形控制提供理论依据与实践指导。

     

    Abstract: Existing research conclusions on the correlation between asynchronous rolling process parameters and plate bending behavior are contradictory, and the underlying bending mechanism remains unclear. Taking 08Al steel plate as the research object, this paper systematically investigates the influence law and mechanism of rolling parameters on the bending behavior of steel plates during asynchronous rolling by combining finite element simulation and rolling experiments. A rolling model was established based on ABAQUS software, and the formation mechanisms of plate bending and bending reversal were revealed by analyzing stress evolution and the distribution characteristics of strain rate bands. The results show that X-shaped equivalent plastic strain rate bands distribute in the deformation zone. The number of strain rate bands is positively correlated with the reduction rate and negatively correlated with the initial plate thickness. Asynchronous rolling drives the migration of neutral points on the upper and lower surfaces of the plate and forms a cross shear zone. To balance the moment generated by the cross shear zone, the staggered distribution of rolling pressure on the upper and lower surfaces produces a reverse moment to stabilize the rolling process, which causes an asymmetric distribution of strain rate bands at the roll exit and further induces plate bending. The bending direction is closely related to the number of strain rate bands in the forward slip zone. When only one X-shaped strain rate band exists in the forward slip zone, the steel plate bends toward the fast roll dominated by the asynchronous effect. At a small speed ratio, the number of strain rate bands in the forward slip zone increases with the rise of reduction rate or the decrease of initial plate thickness. In this case, the asynchronous effect is weakened and only affects the distribution of strain rate bands near the neutral point. The newly added strain rate bands before the exit undergo dynamic adjustment, making the steel plate bend toward the slow roll. With the continuous increase of speed ratio, the asynchronous effect is enhanced, and the bending direction of the steel plate reverses toward the fast roll. This study provides a theoretical basis and practical guidance for the plate shape control in asynchronous rolling.

     

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