Method and apparatus for electromagnetic confinement of molten metal in horizontal casting systems

Abstract

The present invention provides an apparatus for strip casting of molten metal including a pair of casting rollers adapted to receive molten metal along a horizontal axis, wherein a vertical distance separating the pair of casting rollers defines a molding zone; and an electromagnetic edge containment apparatus positioned on each side of the molding zone having an induction coil wound about a portion of a magnetic member to generate magnetic lines of force upon application of a current, wherein the poles of the magnetic member are positioned distal from to aligned to the planar sidewall of the casting rollers and the current provides magnetic lines of force perpendicular to said horizontal axis that contain the molten metal in contact to the casting rollers without substantially increasing the temperature of the molten metal.

1 . An apparatus for strip casting of molten metal comprising: 
 (a) a pair of casting rollers adapted to receive molten metal along a horizontal axis, wherein a vertical distance separating the pair of casting rollers defines a molding zone;    (b) an electromagnetic edge containment apparatus positioned on each side of the molding zone, comprising an induction coil wound about a portion of a magnetic member to generate magnetic lines of force upon application of a current, wherein said magnetic member comprises a first and second pole positioned distal from and aligned with a sidewall of said pair of casting rollers and the current provides magnetic lines of force perpendicular to said horizontal axis that contain the molten metal in contact with the casting rollers with substantially no increase in temperature to the molten metal; and    (c) a means for supplying the molten metal to the molding zone along said horizontal axis from a tundish, while ensuring said molten metal remains substantially non-oxidized, wherein the tundish is separated from the molding zone by a distance to substantially eliminate wave generation within the tundish by the magnetic lines of force.    
   
   
       2 . The apparatus of  claim 1  wherein said current comprises an alternating current having a frequency ranging from 40 Hz to 10,000 Hz.  
   
   
       3 . The apparatus of  claim 1  wherein said current comprises less than 2,000 amp/turns.  
   
   
       4 . The apparatus of  claim 1  which includes shield means positioned about the magnetic member.  
   
   
       5 . The apparatus of  claim 1 , wherein the magnetic member has a generally C-shaped configuration, including a core portion and parallel poles integral with and extending therefrom.  
   
   
       6 . The apparatus of  claim 5 , wherein the induction coil is wound about the core of the magnetic member, in which the induction coil is coiled from 1 to 100 times around the magnetic member.  
   
   
       7 . The apparatus of  claim 1 , wherein the vertical distance separating the pair of casting rollers provides a metal head height that allows for containment of the molten metal between the casting rollers by the magnetic lines of force at said current without a substantial increase in temperature of the molten metal resulting from the magnetic lines of force.  
   
   
       8 . The apparatus of  claim 1 , wherein the vertical distance separating the pair of casting rollers is less than 1.0″.  
   
   
       9 . The apparatus of  claim 1 , wherein the magnetic member is positioned to the molding zone to position the magnetic lines of force to produce a convex sidewall, a concave sidewall, or a substantially flat sidewall to the molten metal within the molding zone.  
   
   
       10 . The apparatus of  claim 1 , wherein the magnetic member is formed of a ferromagnetic material from a stack of bonded or mechanically linked laminates or the magnetic member is formed from a solid core of ferromagnetic material.  
   
   
       11 . The apparatus of  claim 1 , wherein said pair of casting rollers comprises a ferromagnetic material, non-ferromagnetic material, or a non-ferromagnetic material that is at least coated with a ferromagnetic material on at least casting surfaces and said sidewalls of said pair of casting rollers.  
   
   
       12 . The apparatus of  claim 1 , wherein said sidewall of said pair of casting rollers is substantially planar.  
   
   
       13 . An apparatus for strip casting of molten metal comprising: 
 (a) a pair of opposing endless metal belts, each of the pair of opposing endless metal belts passing over a roller and having a periphery substantially aligned to a sidewall of the roller, said each of said opposing endless metal belts having a surface for accepting molten metal, wherein a vertical dimension separation the pair of opposing endless metal belts defines a molding zone;    (b) an electromagnetic edge containment apparatus positioned on each side of the molding zone comprising an induction coil wound about a portion of a magnetic member to generate magnetic lines of force upon application of a current, wherein the current provides magnetic lines of force that contain the molten metal within a width and in contact to at least a portion of said pair of opposing endless metal belts with substantially no increase in temperature to the molten metal; and    (c) a means for supplying said molten metal to the molding zone along a horizontal axis from a tundish, the tundish separated from said molding zone by a distance to substantially eliminate wave generation within the tundish by the magnetic lines of force.    
   
   
       14 . The apparatus of  claim 13 , wherein the magnetic member comprises an upper pole and a lower pole, the induction coil wound about a portion of the magnetic member to generate magnetic lines of force passing from one of the upper and lower poles to the other, with the magnetic member being positioned such that the upper and lower poles direct magnetic lines of force establish containment forces at the edges of the pair of opposing endless metal belts to contain the molten metal therebetween.  
   
   
       15 . The apparatus of  claim 13 , wherein the vertical distance separating the pair of opposing endless metal belts provides a metal head height that allows for containment of the molten metal between the pair of opposing endless metal belts by the magnetic lines of force at said current without a substantially increase in temperature of the molten metal resulting from the magnetic lines of force.  
   
   
       16 . The apparatus of  claim 13 , wherein the minimum vertical distance separating the pair of opposing endless metal belts, at the nip of the caster, ranges from about 0.025″ to 0.25″.  
   
   
       17 . The apparatus of  claim 13 , wherein the magnetic member is positioned to the molding zone to position the magnetic lines of force to produce a convex sidewall, concave sidewall or substantially flat sidewall to the molten metal within the molding zone.  
   
   
       18 . A cast metal strip comprising: 
 a first shell;    a second shell; and    a central portion between said first shell and said second shell, said central portion comprising grains having an equiaxed structure, wherein said cast metal strip has sidewall edges being substantially uniform.    
   
   
       19 . The cast metal strip of  claim 18  wherein said first shell is an upper shell and said second shell is a lower shell.  
   
   
       20 . The cast metal strip of  claim 18 , wherein said cast metal strip may be rolled without machining said sidewall edges.  
   
   
       21 . The cast metal strip of  claim 18  comprising aluminum and other light metals such as magnesium and zinc.  
   
   
       22 . The cast metal strip of  claim 18 , wherein said equiaxed structure is substantially globular.  
   
   
       23 . A casting apparatus comprising: 
 (a) a pair of casting rollers adapted to receive molten metal along a horizontal axis, wherein a vertical distance separating the pair of casting rollers defines a molding zone;    (b) a tip delivery structure positioned to supply the molten metal to the molding zone along said horizontal axis from a tundish while ensuring said molten metal remains substantially non-oxidized; and    (c) an edge containment apparatus positioned on each side of the molding zone, said edge containment apparatus comprising: 
 a mechanical edge dam positioned overlying at least an end portion of said tip delivery structure and partially extending towards said molding zone, and  
 an electromagnetic edge dam comprises a first and second magnetic pole positioned distal from and aligned to a sidewall of said pair of casting rollers and overlying a portion of said mechanical edge dam partially extending towards said molding zone, wherein said electromagnetic edge dam provides magnetic lines of force perpendicular to said horizontal axis that contain the molten metal in contact to the casting rollers.  
   
   
   
       24 . The casting apparatus of  claim 23  wherein said tip delivery structure has a length that substantially eliminates wave generation within the tundish by the magnetic lines of force.  
   
   
       25 . The casting apparatus of  claim 24  wherein said electromagnetic edge dam comprises an induction coil wound about a magnetic member to generate magnetic lines of force upon application of a current.  
   
   
       26 . The casting apparatus of  claim 25  wherein said current provides magnetic lines of force that contain the molten metal in contact to the casting rollers with substantially no increase in temperature to the molten metal.  
   
   
       27 . A method of forming a cast metal strip comprising 
 providing molten metal to a molding zone along a horizontal axis;    containing said molten metal within said molding zone with a magnetic containment means; and    casting said molten metal into a cast metal strip, wherein sidewall geometry of said cast metal strip is configured by adjusting said magnetic containment means.    
   
   
       28 . The method of  claim 27  wherein said sidewall geometry is flat or is concave or convex relative to a centerline portion of said cast metal strip.  
   
   
       29 . The method of  claim 28  wherein said magnetic containment means comprises an induction coil wound about a magnetic member to generate magnetic lines of force upon application of a current, said magnetic member having a first and second magnetic pole positioned distal from to adjacent to said molding zone.  
   
   
       30 . The method of  claim 29  wherein said adjusting said magnetic containment means comprises increasing or decreasing said current through said induction coil.  
   
   
       31 . The method of  claim 29  wherein said adjusting said magnetic containment means comprises moving said first and second magnetic poles adjacent to or distal from said molding zone.