Cross-strip temperature variation control

Abstract

To achieve a substantially uniform microstructure across a continuously cast thin metal strip, it is beneficial to cool a width of the strip to a substantially constant temperature before further cooling the strip to reach any desired phase transformation temperature. Accordingly, methods of continuously casting a thin metal strip may include moving the thin strip to a cooling section, the cooling section having a plurality of coolant discharge ports configured to discharge a flow of coolant along the thin strip; initially sensing the temperature of the thin strip to determine a temperature distribution across the width of the thin strip, and producing a sensor signal corresponding to a sensed temperature at each of the first plurality of locations; and individually controlling the cooling across a width of the thin strip by way of the plurality coolant discharge ports in each zone of a first row using the determined temperature distribution.

What is claimed is: 
     
         1 . A method of continuously casting metal strip comprising:
 assembling a pair of counter-rotatable casting rolls having casting surfaces laterally positioned to form a gap at a nip between the casting rolls through which thin strip less than 3 mm in thickness can be cast;   assembling a metal delivery system capable of forming a casting pool supported on the casting surfaces of the casting rolls above the nip with side dams adjacent the ends of the nip to confine the casting pool;   counter rotating the casting rolls to form metal shells on the casting surfaces of the casting rolls that are brought together at the nip to deliver thin strip downwardly;   moving the thin strip from the casting rolls through a hot rolling mill to reduce the thickness of the thin strip to a desired thickness and then to a cooling section, the cooling section having a plurality of coolant discharge ports configured to discharge a flow of coolant along the thin strip, the plurality of coolant discharge ports being arranged into a plurality of rows each extending at least partially across a width of the cooling section and configured to substantially cool a full width of the thin strip, where each coolant discharge port is adapted to independently cool a portion of the thin strip across the width of the thin strip, where a first row of the plurality of rows is divided into three or more zones, each of the three or more zones including at least one of the plurality of coolant discharge ports;   initially sensing the temperature of the thin strip at a first plurality of locations across the width of the thin strip prior to the first row to determine a temperature distribution across the width of the thin strip, and producing a sensor signal corresponding to a sensed temperature at each of the first plurality of locations;   individually controlling the cooling across the thin strip by way of the plurality coolant discharge ports in each zone of the first row using the temperature distribution determined in the step of initially sensing for the purpose of achieving a substantially uniform temperature substantially across the width of the thin strip;   after achieving a substantially uniform temperature substantially across the width of the thin strip, substantially cooling the width having a substantially uniform temperature to achieve a desired microstructure extending substantially across the width of the thin strip.   
     
     
         2 . The method of  claim 1  further comprising:
 subsequently sensing a temperature of the thin strip at a second plurality of locations across the thin strip to determine a temperature distribution across the width of the thin strip subsequent to the first plurality of locations and after individually controlling the cooling across the thin strip along the first row, and producing a sensor signal corresponding to a sensed temperature at each of the second plurality of locations; 
 and, 
 subsequently controlling the cooling across the thin strip by way of the coolant discharge ports in each zone of a second row of the plurality of rows using the temperature distribution determined in the step of subsequently sensing, to assist in achieving the substantially uniform temperature across the width of the thin strip and/or to achieve the particular microstructure in the thin strip at the end of the cooling section. 
 
     
     
         3 . The method of  claim 2 , where the second row is located along the cooling section between the first row and the second plurality of locations across the thin strip. 
     
     
         4 . The method of  claim 3 , where the temperature distribution determined in the step of subsequently sensing is a final temperature distribution sensed along the cooling section. 
     
     
         5 . The method of  claim 4 , where the second plurality of locations are located at an end of the cooling section. 
     
     
         6 . The method of  claim 2 , where the second plurality of locations are located after the beginning and up to the end of the cooling section. 
     
     
         7 . The method of  claim 2  further comprising:
 subsequently controlling the cooling across the thin strip by way of the coolant discharge ports in each zone of the first row using the temperature distribution determined in the step of subsequently sensing, to assist in achieving the substantially uniform temperature across the width of the thin strip. 
 
     
     
         8 . The method of  claim 1  further comprising:
 subsequently sensing a temperature of the thin strip at a second plurality of locations across the thin strip to determine a temperature distribution across the width of the thin strip subsequent to the first plurality of locations and after individually controlling the cooling across the thin strip along the first row, and producing a sensor signal corresponding to a sensed temperature at each of the second plurality of locations; and, 
 subsequently controlling the cooling across the thin strip by way of the coolant discharge ports in each zone of the first row using the temperature distribution determined in the step of subsequently sensing, to assist in achieving the substantially uniform temperature across the width of the thin strip. 
 
     
     
         9 . The method of  claim 8 , where the temperature distribution determined in the step of subsequently sensing is a final temperature distribution sensed along the cooling section. 
     
     
         10 . The method of  claim 1 , where individually controlling the cooling of the thin strip in each zone of the first row is performed by controlling the discharge flow rate of any one or more of the plurality of the coolant discharge ports. 
     
     
         11 . The method of  claim 10 , where in individually controlling the cooling of the thin strip, is performed by adjusting the discharge flow rate of one or more of the plurality of coolant discharge ports. 
     
     
         12 . The method of continuously casting metal strip as recited in  claim 1 , wherein the first row is divided into at least five zones. 
     
     
         13 . The method of continuously casting metal strip as recited in  claim 1  further comprising:
 a controller adapted to control the coolant flow from the plurality of coolant discharge ports in each zone to provide temperature regulation across the width of the thin strip. 
 
     
     
         14 . The method of  claim 2  further comprising:
 subsequently controlling the cooling across the thin strip by way of the coolant discharge ports in each zone of any one or more additional rows of the plurality of rows, to assist in achieving the substantially uniform temperature across the width of the thin strip and/or to achieve the particular microstructure in the thin strip at the end of the cooling section. 
 
     
     
         15 . The method of  claim 14 , where subsequently controlling the cooling across the thin strip by way of the coolant discharge ports in each zone of any one or more additional rows of the plurality of rows is performed using any temperature distribution determined in any one or more additional steps of subsequently sensing a temperature of the thin strip at any further plurality of locations across the thin strip to determine any further temperature distribution across the width of the thin strip subsequent to the first and second plurality of locations and after individually controlling the cooling across the thin strip along the one row and along the second row, and producing a sensor signal corresponding to a sensed temperature at each of the further plurality of locations. 
     
     
         16 . The method of  claim 1 , where the plurality of coolant discharge ports are a plurality of spray nozzles. 
     
     
         17 . The method of  claim 2 , where the temperature distribution determined in the step of subsequently sensing is a final temperature distribution sensed along the cooling section. 
     
     
         18 . The method of  claim 2 , where the plurality of coolant discharge ports are a plurality of spray nozzles. 
     
     
         19 . The method of  claim 14 , where the plurality of coolant discharge ports are a plurality of spray nozzles.