移动磁场电磁力对铸件表面粗糙度的影响

Effects of Electromagnetic Force in Traveling Magnetic Field on the Surface Roughness of Al Thin-walled Castings

采用移动磁场铸造薄壁铝合金流动试样 ,并对移动磁场铸造过程中铝合金熔体内的电磁力各分量的瞬时值及其对铸件表面质量的影响进行了理论分析。结果表明 ,随着磁感应强度的增加 ,铸件的表面粗糙度有增加的趋势 ,这在采用金属上型时表现更明显。由于通入电磁感应器的三相非平衡电流在铝合金熔体内所产生的电磁力是脉动的 ,其大小呈周期性变化 ,尤其是垂直于磁场运动方向上的电磁力 ,其脉动的幅度很大。由此认为 ,所产生的垂直于磁场运动方向上的脉动电磁力是引起熔体表面震荡起伏和导致铸件凝固后表面粗糙的主要原因。

The effects of instantaneous components of traveling electromagnetic force in Al alloy melt during casting process for thin-walled sample on surface quality of the casting were analyzed theoretically. The results showed that the roughness of the casting rose with increase in magnetic induction intensity, especially in making option of metallic cope. The periodically pulsating electromagnetic force appears in Al alloy melt due to applying 3 phase non-equilibrium current to electromagnetic inductor, especially in the case of the magnetic force perpendicular to the direction of magnetic field with larger pulse amplitude. It is believed that the pulse electromagnetic force perpendicular to direction of magnetic field is responsible for the surface fluctuation of the melt and surface roughness deterioration of solidified casting.