The theoretical and numerical calculation and experimental study on soft contact electromagnetic casting forming
Based on classical electromagnetic theory, the electromagnetic pressure calculation model and the formula of electromagnetic casting forming have been established. Theoretical and numerical results indicated that the frequency, current density, relative permeability of alloy melt and resistivity can also influence the effect of electromagnetic pressure. Meanwhile, the effect of metal physics properties parameters on the value of electromagnetic pressure is more complicated. The needed magnetic field for casting Al-Si alloys liquid column with length of 0.05m in experiment was very close to the theoretical value. This result indicated that the formula of electromagnetic casting forming can be used to guide experiments and the actual industrial production.
Meniscus Behavior in Electromagnetic Soft-Contact Continuous Casting Round Billet Mold
Using molten Pb-Sn-Bi alloy, the meniscus shape under high frequency magnetic field of ø100 mm round billet caster was investigated. The effect of some parameters on meniscus shape was studied. The results show that for a mold with 12 segments, the meniscus shape is relatively stable. With increasing power input, the meniscus height increases with intensification of fluctuation. For the given caster, the reasonable power input is about 70 kW. The coil should be near to the top of mold and/or the initial meniscus should be near to the center of the coil. The lower the frequency, the higher is the meniscus height. With increasing frequency, the free surface is more flattened and meniscus becomes more stable. In practice, the power input should be increased simultaneously with frequency. The optimal frequency is about 20 kHz.
Surface Quality Improvement of Continuously Cast Metals by Imposing Intermittent High Frequency Magnetic Field and Synchronizing the Field with Mold Oscillation
In order to improve the surface quality of continuously cast steel, two new casting processes imposing a magnetic field are developed. One is the imposition of an intermittent high frequency magnetic field from the outside of a mold and the other is a synchronizing imposition of the intermittent high frequency magnetic field with mold oscillation. To distinguish the characteristics of the processes, the meniscus dynamic behavior was investigated in molten gallium as simulator of molten steel and the meniscus deformation was numerically analyzed. The surface quality was examined in the cast tin used as simulator of steel. The imposition of the high frequency magnetic field reduces the effect of mold oscillation on dynamic pressure in a flux channel between molten metal and a mold and suppresses the deformation on meniscus shape. The intermittent high frequency magnetic field suppresses the surface wave motion generated by mold oscillation. When the timing of the magnetic field imposition is synchronized with the period including the lowest position in the stroke of mold oscillation, the better surface quality is obtained than that synchronized with the period including the highest position. The amount of electric current required to get the same surface quality decreases in the order of the imposition of continuous high frequency magnetic field, the imposition of intermittent high frequency magnetic field and the synchronizing imposition.