Induction melting of metals without a crucible

Apparatus for inductively melting a quantity of metal without a container, comprising:

• a first induction coil having a plurality of turns disposed around said quantity of metal and energized by an alternating current, said first induction coil adapted to provide a greater electromagnetic force towards the lower portion of the quantity of metal within said induction coil, the topmost of said turns being wound in a direction opposite that of the others of said plurality of turns;
• a second induction coil operatively associated with a magnetically-permeable core and energized by a direct current, said core being disposed relative to said quantity of molten metal to apply a non-varying DC-derived magnetic field to said metal;
• support means having an opening therethrough, substantially in contact with the bottom surface of said quantity of metal;
• and
• cooling means for maintaining said support means at a preselected temperature.

A method of inductively melting a quantity of metal without a container, comprising the steps of:

• placing said quantity of metal within an induction coil;
• producing a time-varying electromagnetic field within said induction coil, said time-varying electro-magnetic field inducing eddy currents within said quantity of metal and electromagnetic forces against the surface of said quantity of metal, said electromagnetic force being stronger towards the lower portion of said quantity of metal, thereby causing said quantity of metal to melt from its top portion downwards;
• applying to said quantity of metal a non-varying DC-derived electromagnetic field in addition to said time-varying electromagnetic field;
• melting said quantity of metal so that heat transfer from the liquid part of said quantity of metal will melt all of the remaining solid part of said quantity of metal except for a rim of solid metal in contact with a support disposed at the bottom surface of said quantity of metal;
• and
• further melting said quantity of metal so that said liquid part of said quantity of metal will flow through an opening in said rim of solid metal and an opening in said support means.