Method and apparatus for continuously casting steel strip

Abstract

A delivery nozzle for a twin roll caster for making has an elongated nozzle body having elongated extending side walls and end walls to form a nozzle trough, and side outlet openings in the side walls capable of discharging molten metal from the nozzle body laterally outwardly from the side walls of the nozzle body. The side walls below the side outlet openings extend downwardly to converge and meet at the lower extremity to form a bottom part of the nozzle body configured to inhibit entrapment of gas bubbles in a casting pool. The side walls forming the bottom part may have generally flat exterior surfaces throughout and meet at an acute angle to form a discrete edge along the nozzle body, or alternatively, convex curved external surfaces meeting at the bottom extremity in an arcuate shape along the nozzle body.

1 . A delivery nozzle for delivering molten metal into a casting pool of a strip caster comprising: 
 an elongate nozzle body having longitudinally extending side walls and end walls to form a nozzle trough;    side outlet openings in the side walls capable of discharging molten metal from the nozzle body laterally outwardly from the side walls of the nozzle body; and    the side walls of the nozzle body below the side outlet openings extending downwardly to converge and meet at the lower extremity of the nozzle to form a bottom part of the nozzle body with an external surface configured to inhibit entrapment of gas bubbles in a casting pool.    
   
   
       2 . The delivery nozzle as claimed in  claim 1  where the side outlet openings are spaced longitudinally along the side walls.  
   
   
       3 . The delivery nozzle as claimed in  claim 1  wherein the side outlet openings are capable of providing outward flow of molten metal adjacent the bottom part of the trough.  
   
   
       4 . The delivery nozzle as claimed in  claim 1  where the bottom part is an integral part with the side walls.  
   
   
       5 . The delivery nozzle as claimed in  claim 1  where the bottom part is a separate part from the side walls.  
   
   
       6 . The delivery nozzle as claimed in  claim 1  where upper parts of the side walls forming the bottom part have a generally flat external surface angled downwardly and inwardly along the nozzle body.  
   
   
       7 . The delivery nozzle as claimed in  claim 6 , where the side walls of the nozzle body extending downwardly to form the bottom part have a generally flat external surface throughout and meet at an acute angle to form a distinct edge along the nozzle body.  
   
   
       8 . The delivery nozzle as claimed in  claim 1  where the side walls of the nozzle body extending downwardly to form the bottom part have convex curved external surfaces meeting at the bottom extremity of the nozzle body in an arcuate shape along the nozzle body.  
   
   
       9 . The delivery nozzle as claimed in  claim 1 , where the upper parts of the side walls extending downwardly to form the bottom part have convex curved external surfaces along the nozzle body.  
   
   
       10 . The delivery nozzle as claimed in  claim 9  where the convex curved external surfaces of the side walls forming the bottom part meet at a bottom extremity in a rounded shape along the nozzle body.  
   
   
       11 . The delivery nozzle as claimed in  claim 9  where the convex curved external surfaces of the side walls forming the bottom part meet at an acute angle at a bottom extremity to form a distinct edge along the nozzle body.  
   
   
       12 . The delivery nozzle as claimed in  claim 1  where external surfaces of the side walls are coated with a carbon free material.  
   
   
       13 . The delivery nozzle as claimed in  claim 12  where said carbon free material is an alkaline silicate material.  
   
   
       14 . The delivery nozzle as claimed in  claim 1  where the longitudinal side walls and end walls of the nozzle body are formed of a carbon free refractory material.  
   
   
       15 . Apparatus for continuously casting thin metal strip comprising: 
 a pair of laterally positioned casting rolls forming a nip between them,    an elongate metal delivery nozzle disposed above and extending along the nip between the casting rolls capable of discharging molten metal to form a casting pool of molten metal supported on the casting rolls above the nip, the delivery nozzle comprising: 
 an elongate nozzle body having longitudinally extending side walls and end walls to form a nozzle trough;  
 side outlet openings in the side walls capable of discharging molten metal from the nozzle body laterally outwardly from the side walls of the nozzle body; and  
 the side walls of the nozzle body below the side outlet openings extending downwardly to converge and meet at the lower extremity of the nozzle to form a bottom part of the nozzle body with an external surface configured to inhibit entrapment of gas bubbles in a casting pool  
   
   
   
       16 . A method of continuously casting thin metal strip comprising the steps of: 
 assembling a thin strip caster having a pair of casting rolls positioned to form a nip between them;    assembling a metal delivery system capable of forming a casting pool between the casting rolls above the nip with side dams adjacent the ends of the nip to confine the casting pool; and    assembling as part of the metal delivery system a delivery nozzle comprising an elongate nozzle body having longitudinally extending side walls and end walls to form a nozzle trough, side outlet openings in the side walls capable of discharging molten metal from the nozzle body laterally outwardly from the side walls of the nozzle body, and the side walls of the nozzle body below the side outlet openings extending downwardly to converge and meet at the lower extremity of the nozzle to form a bottom part of the nozzle body with an external surface configured to inhibit entrapment of gas bubbles in a casting pool.