Continuous metal casting method

Abstract

The method of this invention is practiced within an elongated casting vessel disposed in upright position to receive liquid metal for solidification together with means for delivering liquid metal into the lower portion of the vessel. Heat exchange means are associated with the vessel for cooling and solidifying the liquid metal therein and means are provided for removing solidified metal from the upper portion of the vessel. Electromagnetic field generating means are disposed around the vessel along a portion of its length which includes a plurality of electromagnetic coils for connection to successive phases of a polyphase electric current source to produce both an upward lifting effect on liquid metal in the vessel and a containment field effect. By 'lifting effect' is meant that liquid metal is continuously urged upwardly into contact with the lower end of the solidifying product. In this way, voids and flaws are avoided and fully dense homogeneous products of uniform, small grain cross section result. The containment field effect produces a slight gap between the sidewalls of the casting vessel and the liquid metal. This maintains the liquid in a pressureless contact condition that allows for good heat transfer and provides solidification of the metal. The casting apparatus further includes a crucible to contain a bath of molten metal communicating with the lower end of the casting vessel and also includes means associated with the crucible to move liquid metal upwardly into the casting vessel to a level above the lower end of the electromagnetic field generating means. Such may take the form of a hydrostatic pressure source which operates to displace liquid metal upwardly into the casting vessel.