基于亥姆霍兹线圈电磁制动装置的结晶器内冶金行为研究

Metallurgical behavior of Helmholtz coil-based electromagnetic braking device in mold

为解决连铸过程中钢液在结晶器内不合理的自由液面流速所导致的板坯表面缺陷问题,根据现有电磁制动装置特点,提出一种新型的基于亥姆霍兹线圈的电磁制动装置,建立了板坯结晶器三维数学模型,研究了磁感应强度对结晶器内流场和温度场的影响以及拉坯速度与电磁制动效率之间的关系。结果表明,亥姆霍兹线圈能在覆盖区域形成均匀稳定的磁场,有效抑制射流冲击深度,降低钢液自由液面流速并使其控制在合理范围。同时,磁场的存在消除了结晶器下回流低温区,使得结晶器内温度分布更均匀。数值模拟结果所表征的冶金效果符合电磁制动装置的设计意图,能达到实时控制结晶器自由液面流速的效果。

In order to solve the slab surface defects caused by the unreasonable free surface velocity of molten steel in mold during continuous casting, a new type of electromagnetic braking device based on Helmholtz coil was proposed according to the characteristics of the existing electromagnetic braking device. The 3 D mathematical model of the slab mold was established, and the effects of magnetic induction on the flow field and temperature field in mold as well as the relationship between the drawing speed and braking efficiency were investigated. The results show that the Helmholtz coil can form a uniform and stable magnetic field in the coverage area, effectively suppress the jet impact depth, reduce the free surface velocity of molten steel and control it within a reasonable range. At the same time, the existence of magnetic field eliminates the low temperature area of reflux in the lower part of mold, and therefore the temperature distribution in mold is more uniform. The metallurgical effect obtained by the numerical simulation results meets the expectation of the electromagnetic braking device design, and can achieve real-time control of free surface velocity in mold.