Tundish stopper rod for continuous molten metal casting

Abstract

Stopper rods for the continuous casting of molten metal have a stopper rod body, and a stopper rod tip at a lower end of the stopper rod body. The stopper rod tip defines a frustroconically shaped exterior surface which terminates in a recessed nose. The recessed nose is most preferably a curvilinear surface (e.g., a spherical segment), but non-curvilinear surfaces (e.g., prismatic, pyramidal, triangular, and quadrangular surfaces) may alternatively be employed. The frustroconically shaped exterior surface of the stopper rod tip most preferably forms an angle θ with respect to a horizontal plane which is sufficiently great so as to increase the velocity of the flowing molten metal to reduce the boundary layer thickness thereof adjacent the nozzle and stopper rod tip surfaces so as to minimize the deposition of inclusions thereon. In addition, the angle θ formed by the frustroconically shaped exterior surface is also most preferably sufficiently small so as to not detrimentally affect the lifting force sensitivities of the stopper rod.

1 . A stopper rod for continuous casting of molten metal comprising a stopper rod body, and a stopper rod tip at a lower end of the stopper rod body, said stopper rod tip having a frustroconically shaped exterior surface which terminates in a recessed nose.  
   
   
       2 . The stopper rod of  claim 1 , wherein the recessed nose is a recessed curvilinear surface.  
   
   
       3 . The stopper rod of  claim 2 , wherein the recessed curvilinear surface is a spherical segment.  
   
   
       4 . The stopper rod of  claim 1 , wherein the recessed nose is a recessed non-curvilinear surface.  
   
   
       5 . The stopper rod as in  claim 4 , wherein the recessed non-curvilinear surface is selected from prismatic, pyramidal, triangular, and quadrangular surfaces.  
   
   
       6 . The stopper rod as in  claim 1 , wherein the frustroconically shaped surface forms an angle θ with a horizontal surface which is between about 55° to about 75°.  
   
   
       7 . The stopper rod as in  claim 6 , wherein the angle θ is about 65°± about 7°.  
   
   
       8 . The stopper rod as in  claim 1 , comprising a vent channel formed in the stopper rod body.  
   
   
       9 . The stopper rod as in  claim 8 , wherein the stopper rod tip includes a tip vent channel joined to the stopper rod body vent channel.  
   
   
       10 . A system for continuous casting of molten metal comprising: 
 a vessel for holding a supply of molten metal to be cast;    a discharge nozzle for discharging molten metal from the vessel; and    a stopper rod mounted for reciprocal rectilinear movements towards and away from the discharge nozzle to allow flow rate regulation of the molten metal discharged from the vessel through the discharge nozzle, wherein said stopper rod includes,    (i) a stopper rod body, and    (ii) a stopper rod tip at a lower end of the stopper rod body,    (iii) said stopper rod tip having a frustroconically shaped exterior surface which terminates in a recessed nose.    
   
   
       11 . The system of  claim 10 , wherein the recessed nose of the stopper rod tip is a recessed curvilinear surface.  
   
   
       12 . The system of  claim 11 , wherein the recessed curvilinear surface is a spherical segment.  
   
   
       13 . The system of  claim 10 , wherein the recessed nose of the stopper rod tip is a recessed non-curvilinear surface.  
   
   
       14 . The system as in  claim 13 , wherein the recessed non-curvilinear surface is selected from prismatic, pyramidal, triangular, and quadrangular surfaces.  
   
   
       15 . The system as in  claim 10 , wherein the frustroconically shaped surface forms an angle θ with a horizontal surface which is between about 55° to about 75°.  
   
   
       16 . The system as in  claim 10 , wherein the angle θ is about 65°± about 7°.  
   
   
       17 . The system as in  claim 10 , wherein the stopper rod further includes a vent channel formed in the stopper rod body.  
   
   
       18 . The system as in  claim 17 , wherein the stopper rod tip includes a tip vent channel joined to the stopper rod body vent channel.  
   
   
       19 . The system as in  claim 10 , wherein the stopper rod further includes a cross-pin adapted to being attached to a lifting mechanism.  
   
   
       20 . The system as in  claim 10 , wherein the vessel is a tundish.  
   
   
       21 . A method of regulating flow rate of molten metal being discharged from a vessel through a discharge nozzle during a continuous casting operation, the method comprising: 
 (a) providing a stopper rod comprising a stopper rod body, and a stopper rod tip at a lower end of the stopper rod body, said stopper rod tip having a frustroconically shaped exterior surface which terminates in a recessed nose; and    (b) positioning the stopper rod within the vessel so that the stopper rod tip operatively cooperates with the discharge nozzle; and    (c) controllably displacing the stopper rod tip relative to the discharge nozzle so as to regulate the flow rate of molten metal being discharged from the tundish through the tundish discharge nozzle.    
   
   
       22 . The method of  claim 21 , wherein step (b) comprises positioning the stopper rod within a tundish.