Apparatus for producing metallic castings by progressively melting a solid charge

Claim 1

Apparatus for producing metallic castings comprising, an upright crucible provided with a bottom sprue opening into a mould supported in a casting box therebelow, said crucible being constructed to receive a solid metallic charge to be melted and cast and wherein an initial gap is provided between the metallic charge and a compressible refractory liner forming the inner wall surface of said crucible, and a high-frequency heating coil surrounding said crucible and which has the turns thereof arranged to effect a progressive melting of said metallic charge from the top down such that the initially melted upper part of said metallic charge flows downwardly through said gap into and refreezes in the lower part of said crucible so as to prevent discharge of melted metal through said sprue until the entire volume of the metallic charge has reached its molten state and reached a temperature higher than its melting temperature, said heating coil comprising an inner coil section having uniformly spaced turns extending over the entire height of the melting space within said crucible and an outer coil section surrounding said inner coil section and having a lesser number of turns and which is located at the upper portion of said crucible so as to apply more heat to the upper part of the metallic charge placed within said crucible, said outer coil section being adjustable longitudinally along said inner coil section to accommodate metal charges of different height within the crucible.