Tundish stopper rod for continuous molten metal casting

Abstract

Stopper rods ( 22 ) for the continuous casting of molten metal have a stopper rod body ( 22 - 3 ), and a stopper rod tip ( 22 - 1 ) at a lower end of the stopper rod body. The stopper rod tip defines a frustoconically shaped exterior surface ( 22 - 1 a ) which terminates in a recessed nose ( 22 - 1 b ). 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 frustoconically shaped exterior surface ( 22 - 1 a ) 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. Preferably the angle θ is greater than 70°.

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 frustoconically shaped exterior surface which terminates in a recessed nose.  
   
   
       2 . A stopper rod as claimed in  claim 1 , wherein the recessed nose is a recessed curvilinear surface.  
   
   
       3 . A stopper rod as claimed in  claim 2 , wherein the recessed curvilinear surface is a spherical segment.  
   
   
       4 . A stopper rod as claimed in  claim 1 , wherein the recessed nose is a recessed non-curvilinear surface.  
   
   
       5 . A stopper rod as claimed in  claim 4 , wherein the recessed non-curvilinear surface is selected from prismatic, pyramidal, triangular, and quadrangular surfaces.  
   
   
       6 . A stopper rod as claimed in  claim 1 , wherein the frustoconically shaped surface forms an angle θ with a horizontal surface which is between about 55° to about 85°.  
   
   
       7 . A stopper rod as claimed in  claim 6 , wherein the angle θ is greater than about 70°.  
   
   
       8 . A stopper rod as claimed in  claim 1 , comprising a gas supply channel formed in the stopper rod body.  
   
   
       9 . A stopper rod as claimed in  claim 8 , wherein the stopper rod tip includes a tip gas supply channel joined to the stopper rod body gas supply channel so as to enable a gas to be supplied from through the stopper rod body channel and the tip gas supply channel, to said recess of the nose.  
   
   
       10 . A stopper rod as claimed in  claim 1 , wherein the junction between the stopper rod body and the frustoconically shaped exterior is curved/rounded.  
   
   
       11 . 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 frustoconically shaped exterior surface which terminates in a recessed nose.  
   
   
   
       12 . A system as claimed in  claim 11 , wherein the recessed nose of the stopper rod tip is a recessed curvilinear surface.  
   
   
       13 . A system as claimed in  claim 12  wherein the recessed curvilinear surface is a spherical segment.  
   
   
       14 . A system as claimed in  claim 11 , wherein the recessed nose of the stopper rod tip is a recessed non-curvilinear surface.  
   
   
       15 . A system as claimed in  claim 14 , wherein the recessed non-curvilinear surface is selected from prismatic, pyramidal, triangular, and quadrangular surfaces.  
   
   
       16 . A system as claimed in  claim 11 , wherein the frustoconically shaped surface forms an angle θ with a horizontal surface which is between about 55° to about 85°.  
   
   
       17 . A system as claimed in  claim 16 , wherein the angle θ is greater than about 70°.  
   
   
       18 . A system as claimed in  claim 11 , wherein the stopper rod further includes a gas supply channel formed in the stopper rod body.  
   
   
       19 . A system as claimed in  claim 18 , wherein the stopper rod tip includes a tip gas supply channel joined to the stopper rod body gas supply channel, so as to enable a gas to be supplied from through the stopper rod body channel and the tip gas supply channel, to said recess of the nose.  
   
   
       20 . A system as claimed in  claim 11 , wherein the junction between the stopper rod body and the frustoconically shaped exterior is curved/rounded.  
   
   
       21 . A system as claimed in  claim 11 , wherein the stopper rod further includes a cross-pin adapted to being attached to a lifting mechanism.  
   
   
       22 . A system as claimed in  claim 11 , wherein the vessel is a tundish.  
   
   
       23 . A method of regulating the 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 frustoconically 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 vessel through the vessel discharge nozzle.    
   
   
       24 . The method of  claim 21 , wherein step (b) comprises positioning the stopper rod within a tundish.