电磁悬浮熔炼的温度特性

Temperature character of electromagnetic levitation melting

利用一般电磁悬浮熔炼感应器 ,球形试样悬浮情况下 ,悬浮力和悬浮试样输入功率表达式 ,建立了不含悬浮感应器电流的悬浮试样输入功率表达式 .利用这些表达式 ,结合自然对流情况下 ,球形试样在气体介质中的功率耗散模型 ,建立了悬浮熔炼工艺参量与悬浮熔炼试样温度之间的关系 .以 (TbDy)Fe2 合金在Ar气保护情况下 ,在一定工艺条件下的电磁悬浮熔炼为例 ,得到了电磁悬浮熔炼各种工艺参量与悬浮试样温度的关系 .通过对计算结果的分析 ,结合实际电磁悬浮熔炼特点 ,得到了降低电磁悬浮熔炼试样最低温度的措施 :减小悬浮试样的半径 ;在能够实现悬浮的情况下 ,采用较低的电源频率 ;通过调整电源功率 ,使试样悬浮于温度最低的位置 ;减小下悬浮绕组参量Rd;增大上稳定控制绕组与下悬浮绕组的间距Sm ;增大上稳定控制绕组参量Ru;

Utilizing the formula of electromagnetic force and input power, we have derived the expression of input power of a spherical sample for a general electromagnetic levitation inductor without including the current of the inducer. Combining the power dissipation model of the spherical sample in free-convection gas medium and the expression of input power without including the current of inducer, the relation between processing parameters of electromagnetic levitation and temperature of levitation sample is established. The electromagnetic melting of spherical (ThDy) Fe-2 alloys under the protection of Ar is employed as an example to study the effect of processing parameters on the temperature of levitation sample obtained by numerical computation. According to computation results and the character of actual electromagnetic levitation, the methods to decrease the temperature of the levitation melted sample are obtained: i.e. reducing the radius of the levitation melted sample, employing low frequencies of the inducer, adjusting the position of the levitated sample to a position at which the lowest levitation melting temperature can be obtained, reducing the radius of the lower levitation coil, increasing the space interval between the upper stability controlling coil and the lower levitation coil, increasing the radius of the upper stability controlling coil, and increasing the turns of the upper stability controlling coil.