双辊铸轧6061铝合金温度场与冷却场数值模拟研究

Study on Numerical Simulation of Temperature Field and Cooling Field of 6061 Aluminum Alloy in Twin-Roll Casting and Rolling

为了进一步探明铸轧过程中熔池内熔体流动情况和凝固传热规律,揭示铸轧6061铝合金裂纹等缺陷的产生机理,为改善铸轧6061板材生产提供可靠的理论指导,利用三维建模软件SolidWorks建立了浇铸辊-冷却水-熔池耦合模型,对熔池、冷却水和铸轧辊之间的传热和冷却进行了描述,并确定了模拟各物理场所需的传热方程和边界条件,以云图、流线图的形式反映出熔池温度场、流场的周期分布情况,探讨铸坯质量影响原理,最后通过实验证明了计算的准确性。结果表明,表面涡流使熔池宽度方向上Kiss点高度不同,边部出口温度239.6℃,中心部位出口温度301℃。中心和边部的Kiss点偏低,这些部位容易产生裂纹。辊套处流线最高速度为16.94 m/s,且由于冷却水流入角度差异,在铸轧辊的旋转作用下,冷却水流速在铸轧辊圆周方向上按1/4周期交替变化,两个相邻周期的冷却温度相差约30℃。

In order to further investigate the melt flow and solidification heat transfer law in the molten pool during casting and rolling,reveal the generation mechanism of cracks and other defects of cast-rolled 6061 aluminum alloy,and provide reliable theoretical guidance for improving the cast-rolled 6061 sheet,a coupling model of casting roll-cooling water-molten pool is established by using three-dimensional modeling software SolidWorks.The heat transfer and cooling between molten pool,cooling water and casting roll are described,and the heat transfer equations and boundary conditions required for simulating each physical site are determined.The periodic distribution of temperature field and flow field in molten pool is reflected in the form of cloud diagram and flow diagram.The influence principle of casting billet quality is discussed,and the accuracy of calculation is proved by experiments.The results show that the surface eddy current makes the height of Kiss point different in the direction of the width of the molten pool,the exit temperature of the edge is 239.6℃,and the exit temperature of the central part is 301℃.The center and edge Kiss points are low,and these parts are prone to cracks.The maximum speed of the flow line at the rod sleeve is 16.94 m/s,and due to the difference in the inflow Angle of the cooling water,under the rotation of the casting roll,the flow rate of the cooling water changes alternately in the direction of the circumference of the casting roll according to 1/4 cycle,and the cooling temperature difference between the two adjacent cycles is about 30℃.