磁场均匀性对电磁软接触连铸坯表面质量的影响

Effects of Electromagnetic Field Uniformity on Surface Quality of Round Billet in EMC Process

针对圆坯电磁软接触连铸过程,建立了描述结晶器内三维电磁场分布的数学模型,研究了结晶器内磁场强度及其导出量的分布规律,并对高频磁场对铸坯表面质量的作用机理进行了初步分析。结果表明,由于结晶器上切缝的分布特点和金属集肤效应的影响,作用在软接触结晶器内部的磁感应强度沿径向、轴向和周向分布都不均匀。电磁力方向由钢液外表面指向液芯,线圈中心处电磁力最大,然后向两端迅速减小。焦耳热沿结晶器高度方向分布不均匀,在钢液自由表面附近,焦耳热最大并沿拉坯方向迅速减小。由于切缝周期对称的特点,电磁力、焦耳热在周向上也存在周期性对称的特点。

Aiming at the process of electromagnetic soft-contacting continuous casting, a three-dimensional finite element model of electromagnetic field was developed to investigate the distribution of electromagnetic field in the mold and the effect mechanism of high frequency magnetic field on surface quality of billet. The results show the electromagnetic flux intensity distributes unevenly along axial and radial direction due to skin-effect and slit. The electromagnet force fingers to the center of metal pool from exterior of billet, the maximal is in the center of coil, and decreases quickly towards two ends of billets. The Joule heat was unevenly along axial direction, the maximal produces near the free surface, and decreases along casting direction quickly. Due to the character of periodic symmetry of slit, the electromagnetic force and Joule heat also have the character of periodic symmetry on the exterior of billet.