Duflex impedance shield for shape control in electromagnetic casting

摘要

A duplex impedance shield is disclosed which is used to effect improved shape control in the electromagnetic casting of molten metal or alloy. The shield is provided with a primary loop which substantially surrounds the upper portion of an electromagnetic casting station and a secondary loop attached thereto which serves to enlarge the air gap enclosed by the shield thereby increasing the impedance of the shield. The secondary loop of the shield may be provided with shunt means which can be manipulated to vary the inductance and/or the resistance of the shield thereby varying the impedance of the shield.