Process of and apparatus for ingot cooling during direct casting of metals

Abstract

A process and apparatus for producing a cast and cooled metal ingot. The process comprises: casting a molten metal by a direct chill casting operation to form a metal ingot emerging from a mould, and directing one or more streams of liquid coolant onto an outer surface of the metal ingot adjacent to the mould at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot. The one or more streams of liquid coolant are orientated at an angle relative to the outer surface of the ingot, and the angle is varied during the casting operation to change the rate of heat extraction from the ingot to minimize cooling-related defects in the cast and cooled ingot.

What we claim is:  
     
         1 . A process of producing a cast and cooled metal ingot, comprising: casting a molten metal by a direct chill casting operation to form a metal ingot emerging from a mould, and directing one or more streams of liquid coolant onto an outer surface of said metal ingot adjacent to the mould at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, wherein said one or more streams of liquid coolant are orientated at an angle relative to the outer surface of the ingot, and said angle is varied during said casting operation to change said rate of heat extraction from said ingot to minimize cooling-related defects in said cast and cooled ingot.  
     
     
         2 . The process of  claim 1  wherein the said angle may be varied continuously.  
     
     
         3 . A process of producing a cast and cooled metal ingot, comprising: casting a molten metal by a direct chill casting operation to form a metal ingot emerging from a mould, and directing one or more streams of liquid coolant onto an outer surface of said metal ingot adjacent to the mould at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, wherein said one or more streams of liquid coolant are orientated at an angle relative to the outer surface of the ingot, and said angle is varied during said casting operation to change said rate of heat extraction from said ingot to minimize cooling-related defects in said cast and cooled ingot and wherein each of the said one or more streams is formed by the combination of two or more streams internally within the mould to form a single stream exiting the mould.  
     
     
         4 . A process of producing a cast and cooled metal ingot, comprising: casting a molten metal by a direct chill casting operation to form a metal ingot emerging from a mould, and directing one or more streams of liquid coolant onto an outer surface of said metal ingot adjacent to the mould at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, wherein said one or more streams of liquid coolant are orientated at an angle relative to the outer surface of the ingot, and said angle is varied during said casting operation to change said rate of heat extraction from said ingot to minimize cooling-related defects in said cast and cooled ingot, with the angle being varied in response to at least one measured parameter of the casting system.  
     
     
         5 . The process of  claim 4  wherein the said at least one measured parameter is selected from the group including ingot surface temperature measurement, metal sump temperature, starter block position, casting speed and coolant property.  
     
     
         6 . A process as in  claim 5  wherein the said coolant property is the coolant quenchability factor.  
     
     
         7 . A process as in  claim 5  wherein the said ingot surface temperature measurement is measured at a predetermined distance from the point at which the said streams of coolant impinge on the outer surface of the ingot after the cast has reached a steady state.  
     
     
         8 . A process of producing a cast and cooled metal ingot, comprising: casting a molten metal by a direct chill casting operation to form a metal ingot emerging from a mould, and directing one or more streams of liquid coolant onto an outer surface of said metal ingot adjacent to the mould at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, wherein said one or more streams of liquid coolant are orientated at an angle relative to the outer surface of the ingot, and said angle is varied during said casting operation to change said rate of heat extraction from said ingot to minimize cooling-related defects in said cast and cooled ingot and wherein the said one or more streams of liquid coolant exit the mould along a single line.  
     
     
         9 . The process of  claim 8  wherein the said single line is selected from the group consisting of a straight line, and a curve having no more than three inflection points on one side of the mould.  
     
     
         10 . The process of  claim 1  wherein each individual stream of said one or more streams is produced by passing liquid coolant through at least two channels, each channel being orientated at a different angle with respect to said surface of said ingot, and combining said coolant from said channels at a common outlet of said channels to produce said individual stream.  
     
     
         11 . The process of  claim 10  wherein said angle of said one or more streams relative to the outer surface of the ingot is varied by changing the relative flow of the coolant in said at least two channels provided for each individual stream.  
     
     
         12 . Apparatus for producing a cast and cooled metal ingot, comprising: a direct chill casting mould having an annular body defining a casting cavity, for casting molten metal into a metal ingot having a periphery, and a mould outlet from which said metal ingot emerges as casting proceeds during a casting operation, one or more openings in said annular body adjacent to said mould outlet for directing one or more streams of liquid coolant onto an outer surface of said metal ingot at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, and an orientating arrangement within said annular body for orientating said one or more streams emerging from said openings at an angle relative to the surface of the ingot, and for enabling variation of said angle as said casting operation proceeds to minimize cooling-related defects in the cast and cooled ingot.  
     
     
         13 . Apparatus as in  claim 12  wherein the said orienting arrangement causes the said angle of the said one or more streams to be continuously variable.  
     
     
         14 . Apparatus for producing a cast and cooled metal ingot, comprising: a direct chill casting mould having an annular body defining a casting cavity, for casting molten metal into a metal ingot having a periphery, and a mould outlet from which said metal ingot emerges as casting proceeds during a casting operation, one or more openings lying along a single line in said annular body adjacent to said mould outlet for directing one or more streams of liquid coolant onto an outer surface of said metal ingot at positions spaced around the periphery of the ingot to achieve a rate of beat extraction from the ingot, and an orientating arrangement within said annular body for orientating said one or more streams emerging from said openings at an angle relative to the surface of the ingot, and for enabling variation of said angle as said casting operation proceeds to minimize cooling-related defects in the cast and cooled ingot.  
     
     
         15 . Apparatus according to  claim 14  wherein the single line is selected from the group consisting of a straight line and a curve have three or less inflection points along a side of the said mould.  
     
     
         16 . Apparatus for producing a cast and cooled metal ingot, comprising: a direct chill casting mould having an annular body defining a casting cavity, for casting molten metal into a metal ingot having a periphery, and a mould outlet from which said metal ingot emerges as casting proceeds during a casting operation, one or more openings in said annular body adjacent to said mould outlet for directing one or more streams of liquid coolant onto an outer surface of said metal ingot at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, and an orientating arrangement within said annular body for orientating said one or more streams emerging from said openings at an angle relative to the surface of the ingot, and for enabling variation of said angle as said casting operation proceeds to minimize cooling-related defects in the cast and cooled ingot and wherein the said orienting arrangement comprises, for each of the said one or more openings, two or more internal channels that meet internally within the mould body to form a single channel before exiting the mould.  
     
     
         17 . Apparatus according to  claim 12  wherein the said orienting arrangement is selected from the group consisting of a hydraulic means, a mechanical means, or a pneumatic means.  
     
     
         18 . Apparatus for producing a cast and cooled metal ingot, comprising: a direct chill casting mould having an annular body defining a casting cavity, for casting molten metal into a metal ingot having a periphery, and a mould outlet from which said metal ingot emerges as casting proceeds during a casting operation, one or more openings in said annular body adjacent to said mould outlet for directing one or more streams of liquid coolant onto an outer surface of said metal ingot at positions spaced around the periphery of the ingot to achieve a rate of heat extraction from the ingot, and an orientating arrangement within said annular body for orientating said one or more streams emerging from said openings at an angle relative to the surface of the ingot, and for enabling variation of said angle as said casting operation proceeds to minimize cooling-related defects in the cast and cooled ingot, said orienting means being controlled so as to cause the angle of impingement on the said one or more coolant streams to vary in response to one or more measured casting parameters.  
     
     
         19 . Apparatus according to  claim 18  wherein the said at least one measured parameter is selected from the group including ingot surface temperature measurement, metal sump temperature, stool cap position, casting speed and coolant property.  
     
     
         20 . Apparatus according to  claim 19  wherein the said coolant property is the coolant quenchability factor.  
     
     
         21 . Apparatus according to  claim 19  wherein the said ingot surface temperature measurement is measured at a predetermined distance from the point at which the said streams of coolant impinge on the outer surface of the ingot after the cast has reached a steady state.