Continuous roll casting of ferrous and non-ferrous metals

Abstract

A method of continuously casting metal strip, as well as an apparatus for carrying out the process, wherein the process includes the steps of: providing a pair of casting rolls operating at a selected rotational speed and the two casting rolls being spaced apart from each other at a pre-selected distance; introducing molten metal between the two casting rolls; monitoring the separation force exerted on the two casting rolls by the molten metal, and adjusting the rotational speed of the two casting rolls in response to the magnitude of the separation force wherein the rotational speed of the two casting rolls is reduced when the separation force is below a lower value and the rotational speed of the two casting rolls is increased when the separation force is above an upper value; and processing the strip by removing any shape defects therein.

1 . A method of continuously casting metal strip comprising the steps of: 
 providing two casting rolls spaced apart from each other at a pre-selected distance and operating at a selected rotational speed;    introducing molten metal between the two casting rolls,    monitoring the separation force exerted on the two casting rolls by the molten metal, and    adjusting the rotational speed of the two casting rolls in response to the magnitude of the separation force wherein the rotational speed of the two casting rolls is reduced when the separation force is below a lower value and the rotational speed of the two casting rolls is increased when the separation force is above an upper value.    
     
     
         2 . The method of continuously casting metal strip according to  claim 1  further including the steps of: supplying coolant to the casting rolls at a coolant flow rate, and adjusting the coolant flow rate to the casting rolls in response to the magnitude of the separation force  
     
     
         3 . The method of continuously casting metal strip according to  claim 2  wherein if the separation force exceeds the upper value, the coolant flow rate is decreased and if the separation falls below the lower value, the coolant flow rate is increased.  
     
     
         4 . The method of continuously casting metal strip according to  claim 1  further including the steps of: causing coolant to enter and exit the casting rolls at a coolant flow rate.  
     
     
         5 . The method of continuously casting metal strip according to  claim 4  further including the steps of sensing the difference between the temperature of the coolant entering the casting rolls and the temperature of the coolant exiting the casting rolls to define a temperature gradient.  
     
     
         6 . The method of continuously casting metal strip according to  claim 5  further including the steps of: decreasing the coolant flow rate when the temperature gradient is less than a low value and increasing the coolant flow rate when the temperature gradient is greater than a high value.  
     
     
         7 . The method of continuously casting metal strip according to  claim 5  further including the step of maintaining the temperature gradient within a pre-selected range by adjusting the coolant flow rate.  
     
     
         8 . A method of continuously casting metal strip comprising the steps of: 
 providing two casting rolls spaced apart from each other at a pre-selected distance and operating at a selected rotational speed;    introducing molten metal between the two casting rolls,    monitoring the separation force exerted on the two casting rolls by the molten metal,    supplying coolant to the casting rolls at a coolant flow rate, and    adjusting the coolant flow rate to the casting rolls in response to the magnitude of the separation force    
     
     
         9 . The method of continuously casting metal strip according to  claim 8  wherein if the separation force exceeds the upper value, the coolant flow rate is decreased and if the separation falls below the lower value, the coolant flow rate is increased.  
     
     
         10 . A mandrel assembly for receiving a moving strip so as to exert a tension upon the strip, the mandrel assembly comprising: 
 a deflection-free mandrel defining a generally cylindrical peripheral surface and the mandrel having a transverse dimension;    the mandrel being movable between and including a contracted position wherein the mandrel presents a minimum transverse dimension so as to exert a minimum tension on the strip and an expanded position wherein the mandrel presents a maximum dimension so as to exert a maximum tension upon the strip; and    a controller operatively connected to the mandrel so as to move the mandrel to a position between and including the contracted position and expanded position so as to exert a selected tension on the moving strip.    
     
     
         11 . The mandrel assembly of  claim 10  wherein the mandrel includes a segment that has an exterior surface that defines at least a portion of the cylindrical peripheral surface of the mandrel, and the segment being movable between and including a contracted position wherein the mandrel presents the minimum transverse dimension and an expanded position wherein the mandrel presents the maximum dimension.  
     
     
         12 . The mandrel assembly of  claim 10  wherein the mandrel includes a plurality of the segments.  
     
     
         13 . The mandrel assembly of  claim 10  wherein the controller being operatively connected to a speed monitoring means for monitoring the speed of the moving strip at a pre-selected position, and the controller moving the mandrel into a selected position in response to the speed of the moving strip at the pre-selected position  
     
     
         14 . A method for making a metal strip comprising the steps of: 
 providing two casting rolls spaced apart from each other at a pre-selected distance and operating at a selected rotational speed;    introducing molten metal between the two casting rolls whereby a metal strip exits the casting rolls;    monitoring the separation force exerted on the two casting rolls by the molten metal;    providing a deflection-free mandrel driven by a motor for receiving the metal strip;    providing a reverse bending roll station that engages the metal strip upstream of the mandrel;    providing an equalizer roll assembly upstream of the reverse bending roll station;    providing an upstream strip speed monitor located upstream of the reverse bending roll station and downstream of the equalizer roll assembly whereby the upstream strip speed monitor monitors the speed of the metal strip as it enters the reverse bending roll station;    providing a downstream strip speed monitor located downstream of the reverse bending roll station whereby the downstream strip speed monitor monitors the speed of the metal strip as it exists the reverse bending roll station; and    controlling the tension exerted on the metal strip as a function of the difference between the speed of the metal strip entering the reverse bending roll station and the speed of the metal strip exiting the reverse bending roll station.    
     
     
         15 . The method of making a metal strip according to  claim 14  further including the step of adjusting the rotational speed of the two casting rolls in response to the magnitude of the separation force wherein the rotational speed of the two casting rolls is reduced when the separation force is below a lower value and the rotational speed of the two casting rolls is increased when the separation force is above an upper value.  
     
     
         16 . The method of making a metal strip according to  claim 15  further including the steps of: supplying coolant to the casting rolls at a coolant flow rate, and adjusting the coolant flow rate to the casting rolls in response to the magnitude of the separation force  
     
     
         17 . The method of making a metal strip according to  claim 16  wherein if the separation force exceeds the upper value, the coolant flow rate is decreased and if the separation falls below the lower value, the coolant flow rate is increased.  
     
     
         18 . The method of making a metal strip according to  claim 15  further including the steps of: causing coolant to enter and exit the casting rolls at a coolant flow rate.  
     
     
         19 . The method of making a metal strip according to  claim 18  further including the steps of sensing the difference between the temperature of the coolant entering the casting rolls and the temperature of the coolant exiting the casting rolls to define a temperature gradient.  
     
     
         20 . The method of making a metal strip according to  claim 14  wherein the mandrel having a generally cylindrical surface so as to define a diameter, and controlling of the tension exerted on the metal strip is performed by the mandrel wherein the diameter of the mandrel increases or decreases in response to the difference between the speed of the metal strip entering the reverse bending roll station and the speed of the metal strip exiting the reverse bending roll station.