Stopper rod and method for inducing a rotational flow of a molten metal

Abstract

Stopper rod (100) for controlling the flow of molten metal and for inducing a rotational flow of molten metal, said stopper rod (100) comprising a rod-shaped stopper body (101), said rod-shaped stopper body (101) extending along a central longitudinal axis (L) from a first end (105) to a second end (107), said rod-shaped stopper body (101) comprising a nose (103) at said second end (107), wherein said nose (103) provides an exterior surface; a chamber (109), said chamber (109) extending along said central longitudinal axis (L) within said stopper body (101) from said first end (105) towards said second end (107) and ending at a distance from said second end (107); at least one channel (111), preferably a plurality of channels (111), being provided on an exterior surface of said rod-shaped stopper body (101) and at least partially on said exterior surface of said nose (103), and at least partially running around said central longitudinal axis (L), and progressing along the direction of said central longitudinal axis (L); gas supply connecting means (123), said gas supply connecting means (123) connecting said chamber (109) and each of said at least one channel (111).

1 . Stopper rod ( 100 ) for controlling the flow of molten metal and for inducing a rotational flow of molten metal, said stopper rod ( 100 ) comprising:
 1.1. a rod-shaped stopper body ( 101 ),
 1.1.1. said rod-shaped stopper body ( 101 ) extending along a central longitudinal axis (L) from a first end ( 105 ) to a second end ( 107 ), 
 1.1.2. said rod-shaped stopper body ( 101 ) comprising a nose ( 103 ) at said second end ( 107 ), wherein 
 1.1.3. said nose ( 103 ) provides an exterior surface; 
   1.2. a chamber ( 109 ), said chamber ( 109 )
 1.2.1. extending along said central longitudinal axis (L) within said stopper body ( 101 ) from said first end ( 105 ) towards said second end ( 107 ) and ending at a distance from said second end ( 107 ); 
   1.3. at least one channel ( 111 ),
 1.3.1. said at least one channel ( 111 ) being provided on an exterior surface of said rod-shaped stopper body ( 101 ), 
 1.3.2. said at least one channel ( 111 ) being provided at least partially on said exterior surface of said nose ( 103 ), 
 1.3.3. said at least one channel ( 111 ) is at least partially running around said central longitudinal axis (L), and 
 1.3.4. said at least one channel ( 111 ) is progressing along the direction of said central longitudinal axis (L); and 
   1.4. gas supply connecting means ( 123 ), said gas supply connecting means ( 123 )
 1.4.1. connecting said chamber ( 109 ) and each of said at least one channel ( 111 ). 
   
     
     
         2 . Stopper rod ( 100 ) according to  claim 1 , wherein said at least one channel ( 111 ) comprises a first channel wall ( 113 ), limiting each of said at least one channel ( 111 ) in a direction towards said first end ( 105 ), wherein said first channel wall ( 113 ) and said exterior surface of said nose ( 103 ) form a first edge ( 119 ), and wherein said first edge ( 119 ) has the shape of a sharp edge, said first edge ( 119 ) having a radius not above 2 mm. 
     
     
         3 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) defines a channel direction ( 112 ), and wherein each of said channel direction ( 112 ) is aligned at an angle (α i ) to the said central longitudinal axis (L), and wherein each of said angle (α i ) is in the range between 30° to 60°. 
     
     
         4 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) defines a channel direction ( 112 ), and wherein each of said channel direction ( 112 ) is aligned at an angle (α i ) to the said central longitudinal axis (L), and wherein all of said angles (α i ) are the same. 
     
     
         5 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) runs along a helical path on said exterior surface of said nose ( 103 ). 
     
     
         6 . Stopper rod ( 100 ) according to  claim 1 , said stopper rod ( 100 ) comprising an auxiliary gas supply connecting means ( 133 ), said auxiliary gas supply connecting means ( 133 ) leading from said chamber ( 109 ) and through said rod-shaped stopper body ( 101 ) into an auxiliary channel ( 131 ), said auxiliary channel ( 131 ) being provided on said exterior surface of said nose ( 103 ). 
     
     
         7 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said gas supply connecting means ( 123 ) lead into each of said at least one channel ( 111 ) by means of indirect permeability, wherein indirect permeability is achieved by at least one porous insert. 
     
     
         8 . Stopper rod ( 100 ) according to  claim 1 , wherein said at least one channel ( 111 ) is a plurality of channels ( 111 ), each channel ( 111 ) of the plurality of channels ( 111 ) is arranged in a rotationally symmetric arrangement with respect to the said central longitudinal axis (L), such that the distance between each nearest neighboring channels ( 111 ) is the same. 
     
     
         9 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) has a maximum depth of at least 3 mm. 
     
     
         10 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) extends from a first channel end ( 111   u ) to a second channel end ( 111   d ), wherein said second channel end ( 111   d ) is closer to said second end ( 107 ) than said first channel end ( 111   u ). 
     
     
         11 . Stopper rod ( 100 ) according to  claim 1 , wherein each of said at least one channel ( 111 ) extends from a first channel end ( 111   u ) to a second channel end ( 111   d ), wherein said second channel end ( 111   d ) is closer to said second end ( 107 ) than said first channel end ( 111   u ), wherein the distance between said first channel end ( 111   u ) and said second channel end ( 111   d ) defines a channel length ( 111   l ), wherein each of said at least one channel ( 111 ) has a maximum depth of at least 3 mm along at least 30% of said channel length ( 111   l ). 
     
     
         12 . Stopper rod ( 100 ) according to  claim 1 , wherein said gas supply connecting means ( 123 ) lead into each of said at least one channel ( 111 ) at a position between 50 mm to 100 mm distance from said second end ( 107 ) of the stopper body ( 101 ). 
     
     
         13 . Stopper rod ( 100 ) according to  claim 1 , wherein said stopper body ( 101 ) is made of a refractory ceramic material. 
     
     
         14 . Method for controlling the flow of molten metal and for inducing a rotational flow of molten metal, comprising the steps:
 14.1. a stopper rod providing step ( 300 ) in which a stopper rod ( 100 ) is provided, said stopper rod ( 100 ) comprising:
 14.1.1. a rod-shaped stopper body ( 101 ),
 14.1.1.1. said rod-shaped stopper body ( 101 ) extending along a central longitudinal axis (L) from a first end ( 105 ) to a second end ( 107 ), 
 14.1.1.2. said rod-shaped stopper body ( 101 ) comprising a nose ( 103 ) at said second end ( 107 ), wherein 
 14.1.1.3. said nose ( 103 ) provides an exterior surface; 
 
 14.1.2. a chamber ( 109 ), said chamber ( 109 )
 14.1.2.1. extending along said central longitudinal axis (L) into said stopper body ( 101 ) from said first end ( 105 ) towards said second end ( 107 ) and ending at a distance from said second end ( 107 ); 
 
 14.1.3. at least one channel ( 111 ), said at least one channel ( 111 ):
 14.1.3.1. being provided on an exterior surface of said rod-shaped stopper body ( 102 ) and at least partially on said exterior surface of said nose ( 103 ), 
 14.1.3.2. at least partially running around said central longitudinal axis (L), 
 14.1.3.3. and progressing along the direction of said central longitudinal axis (L); 
 
 14.1.4. gas supply connecting means ( 123 ), said gas supply connecting means ( 123 )
 14.1.4.1. connecting said chamber ( 109 ) and each of said at least one channel ( 111 ); 
 
   14.2. a gas supply system providing step ( 310 ) in which a gas supply system ( 200 ) provides a gas ( 210 ) to said chamber ( 109 ); and   14.3. a gas guiding step ( 325 ) in which said gas ( 210 ) is guided at a gas flow (Q(t)) by said gas supply system ( 200 ) via said chamber ( 109 ) through said gas supply connecting means ( 123 ) to said at least one channel ( 111 ) of said stopper rod ( 100 ).   
     
     
         15 . Method according to  claim 14 , with the additional steps of:
 15.1. a tundish nozzle providing step ( 320 ) in which a tundish nozzle ( 9 ,  10 ) is provided, said tundish nozzle ( 9 ,  10 ) comprising a rotational flow measurement unit ( 20 ), capable of measuring the rotational flow (Rot(t)) of the molten metal inside of said tundish nozzle ( 9 ,  10 );   15.2. a rotational flow determination step ( 330 ) in which the rotational flow (Rot(t)) of the molten metal inside of the tundish nozzle ( 9 ,  10 ) is determined by said rotational flow measurement unit ( 20 );   15.3. a target providing step ( 340 ) in which a target for the rotational flow (Rot 0 ) inside of the tundish nozzle ( 9 ,. 10 ) is provided;   15.4 a gas increasing step ( 350 ) in which said gas flow (Q(t)) is increased in case said target for the rotational flow (Rot 0 ) is higher than said determined rotational flow (Rot(t)); and   15.5. a gas decreasing step ( 360 ) in which said gas flow (Q(t)) is decreased in case said target for the rotational flow (Rot 0 ) is lower than said determined rotational flow (Rot(t)).   
     
     
         16 . Stopper rod ( 100 ) according to  claim 1 , said stopper rod ( 100 ) comprising a plurality of channels ( 111 ). 
     
     
         17 . Stopper rod ( 100 ) according to  claim 2 , said first edge ( 119 ) having a radius not above 1 mm. 
     
     
         18 . Stopper rod ( 100 ) according to  claim 6 , said auxiliary channel ( 131 ) is ring shaped, wherein said auxiliary channel ( 131 ) is of direct permeability, and wherein direct permeability is achieved by at least one selected from the group of: a hole and a pipe. 
     
     
         19 . Stopper rod ( 100 ) according to  claim 11 , wherein each of said at least one channel ( 111 ) has a maximum depth of at least 7 mm along at least 50% of said channel length ( 111   l ). 
     
     
         20 . Stopper rod ( 100 ) according to  claim 11 , wherein each of said at least one channel ( 111 ) has a maximum depth of at least 12 mm along at least 70% of said channel length ( 111   l ).