Submerged entry nozzle

Abstract

A nozzle for transferring molten steel in a thin slab continuous casting machine from the tundish to the mold which provides at least two areas of stream compression below the major changes in section required to transition from the entry diameter to the rectangular submerged portion of the nozzle.

1 . A submerged entry nozzle (SEN) for use in a casting machine to conduct molten steel from the tundish to the mold, comprising: 
 a housing having 
 an inlet, for receiving an incoming flow of molten steel from the tundish;  
 a distribution zone, for delivering the molten steel to the mold; and  
 a main body, having a bore disposed at opposite ends thereof in fluid communication with said inlet and said distribution zone, said bore conducting the incoming flow of molten steel received from said inlet along a bore flow path having sequential, sectional flow path geometries that sequentially and alternately compress and decompress the molten steel flow in one or more compression and decompression zones to alternately increase and decrease the steel flow velocity to present the molten steel, at a flow path exit thereof, to said distribution zone as a substantially laminar molten steel primary flow, thereby minimizing the occurrence of flow turbulence introduced into the mold by the molten steel delivered thereto.  
   
   
   
       2 . The SEN of  claim 1 , wherein said bore flow path has at least two said compression zones along its length.  
   
   
       3 . The SEN of  claim 1 , wherein said distribution zone comprises: 
 first and second oppositely directed lateral passages, each in fluid communication with said flow path exit at a passage inlet end thereof, and each having a distal end passage outlet;    a flow divider, comprising a vertical section disposed adjacent to the flow path exit and intermediate to said lateral passages, said flow divider vertical section having a leading edge for dividing the molten steel primary flow into two molten steel secondary flows, and directing each said secondary flow to an associated one of said lateral passages; and    baffles, at least one disposed in the passage outlet end of each of said lateral passages to provide each said passage outlet end with an upper lateral outlet port and a lower lateral outlet port.    
   
   
       4 . The SEN of  claim 3 , wherein said flow divider leading edge has a minimum radius of curvature for dividing the molten steel primary flow into said molten steel secondary flows with minimum flow turbulence.  
   
   
       5 . The SEN of  claim 4 , wherein the radius of curvature of said flow divider leading edge is a maximum 5 mm radius.  
   
   
       6 . The SEN of  claim 4 , wherein said flow divider vertical section further includes a base extending on opposite sides thereof into each of said lateral passages, said base having a surface contour adapted to maintain said molten steel secondary flow through said passage to said lower lateral outlet port, thereby providing the metal flow discharge from said lower lateral outlet port with a lateral angle trajectory.  
   
   
       7 . The SEN of  claim 3 , wherein said housing transitions along the length of said main body from a circular geometry at said inlet, to a rectangular geometry having opposing side walls and opposing front and back walls at said distribution zone, said opposing side walls each having disposed therein said upper lateral outlet port and said lower lateral outlet port of said lateral passage associated therewith, and each having a wall span dimension which is sized in relation to an elected range of values for the thickness of the cast section to be produced, the opposing front and back walls each having a wall span dimension which is sized in relation to an elected range of values for the width of the cast section to be produced, the housing transition characterized by having said opposing front and back walls converge in a continuous linear taper from said inlet to said distribution zone.  
   
   
       8 . The SEN of  claim 7 , wherein said opposing side walls transition from a circular geometry at said inlet to said rectangular geometry at said distribution zone in an incremental manner.  
   
   
       9 . The SEN of  claim 7 , wherein, in consideration of said continuous linear taper convergence of said opposing front and back walls, the spacing between said opposing side walls is altered incrementally along the bore flow path, as necessary to provide said sectional flow path geometries.  
   
   
       10 . The SEN of  claim 7 , wherein said sequential sectional flow path geometries include an upper compression zone and a following, lower compression zone, said upper compression zone providing from five percent to ten percent compression of the molten steel flowing therethrough and said lower compression zone providing from twelve percent to eighteen percent compression of the molten steel flowing therethrough.