Upward continuous casting process

摘要

Continuous casting process comprises (i) introducing molten metal into the lower portion of a casting vessel in the presence of an elongated, upwardly travelling, alternating electro-magnetic levitation field which provides a levitation ratio of 75-200% of the wt. per unit length of the molten metal; (ii) solidifying the metal while moving upwardly through the field; and (iii) removing solidified metal product from the upper portion of the field. The frequency (F, in kHz) of the alternating electromagnetic field is maintained at an optimum value of 36p/D2 (where p is the resistivity (in micro-ohm cm) of the molten metal column and D is the dia. (in mm.) of the solidified useful product). - The method is broadly applicable to metals, metal mixts. and metal alloys, including compsns. which tend strongly to phase sepn. since induced eddy currents result in a high degree of dispersion of the phases. Continuous pressure contact between the outer surface of the molten metal column and the interior surface of the casting vessel is prevented and the molten metal is in a weightless condition so that gravitational, frictional and adhesive forces acting on the solidifying column are minimised while heat transfer between the column and the vessel is simultaneously optimised. (2/8) EPAB- EP-114988 B Method of producing a metal product of long length which comprises the steps of forming an elongated upwardly-travelling alternating electromagnetic field within the interior of a surrounding casting vessel (25), introducing the liquid metal into the lower portion of the casting vessel and the field, establishing a set value of electromagnetic field acting on the liquid metal column (20) to provide a levitation ratio between 75% and 200% of the weight per unit length of liquid metal to thereby reduce the hydrostatic head of the column and to maintain a predetermined dimensional relationship between the outer surface of the liquid metal column and the interior surrounding surfaces of said casting vessel, maintaining the electromagnetic field at the set value of levitation ratio so that the cross-sectional dimension of the liquid metal in the solidification zone is sufficiently large to preclude formation of a substantial gap (45) between the outer surface of the column and the interior surrounding surfaces of the casting vessel thereby effecting optimised heat transfer conditions between the liquid metal column and the casting vessel for a given rate of production while simultaneously reducing frictional, adhesive and gravitational forces acting on the column to a minimum, moving the liquid metal column upwardly through the casting vessel, solidifying the metal while moving upwardly through said vessel and said field, and removing solidified metal product from the upper portion of said vessel; characterised by maintaining the frequency of the alternating electromagnetic field within a range of frequency values from 10 percent to about 100 percent of an optimum frequency value given by the expression - F = 36rho/D power 2 - where F is the frequency in kilohertz, rho is the resistivity of the liquid metal column in micro-ohm-centimeters, and D is the diameter of the solidified metal product in millimeters. (15pp) - EP-114988 B Method of producing a metal product of long length which comprises the steps of forming an elongated upwardly-travelling alternating electromagnetic field within the interior of a surrounding casting vessel (25), introducing the liquid metal into the lower portion of the casting vessel and the field, establishing a set value of electromagnetic field acting on the liquid metal column (20) to provide a levitation ratio between 75% and 200% of the weight per unit length of liquid metal to thereby reduce the hydrostatic head of the column and to maintain a predetermined dimensional relationship between the outer surface of the liquid metal column and the interior surrounding surfaces of said casting vessel, maintaining the electromagnetic field at the set value of levitation ratio so that the cross-sectional dimension of the liquid metal in the solidification zone is sufficiently large to preclude formation of a substantial gap (45) between the outer surface of the column and the interior surrounding surfaces of the casting vessel thereby effecting optimised heat transfer conditions between the liquid metal column and the casting vessel for a given rate of production while simultaneously reducing frictional, adhesive and gravitational forces acting on the column to a minimum, moving the liquid metal column upwardly through the casting vessel, solidifying the metal while moving upwardly through said vessel and said field, and removing solidified metal product from the upper portion of said vessel; characterised by maintaining the frequency of the alternating electromagnetic field within a range of frequency values from 10 percent to about 100 percent of an optimum frequency value given by the expression - F = 36rho/D power 2 - where F is the frequency in kilohertz, rho is the resistivity of the liquid metal column in micro-ohm-centimetres, and D is the diameter of the solidified metal product in millimeters.