Method and plant for the hot rolling of rails

Abstract

A rolling mill for the production of rails comprising a reversible intermediate working section ( 3 ) which receives broken down bars from an appropriate upstream break down rolling station ( 2 ) and passes them to a downstream finishing station ( 4 ). The intermediate working section ( 3 ) comprises a first ( 30 ) and a second universal stand ( 32 ), a high edging stand ( 31 ) placed between the first and the second universal stands ( 30, 32 ). The three stands ( 30, 31, 32 ) are placed at such a distance between each other that the bar can be simultaneously held in all three said stands ( 30, 31, 32 ) during rolling. A method for the rolling of rails with such a plant comprises the following operations in order: a rolling passage (U 1 ) in the second universal stand ( 32 ); a rolling passage (E 1 ) in the high edging stand ( 31 ); a rolling passage (U 2 ) in the first universal stand ( 30 ).

1 ) A method for the production of rails and similar products with a rolling plant, 
 wherein the plant comprises a reversible intermediate working station ( 3 ),    the intermediate working station ( 3 ) comprising a first ( 30 ) and a second universal stand ( 32 ),    a high edging stand ( 31 ) placed between said first and second universal stand ( 30 ,  32 ), the intermediate working station ( 3 ) being able to receive a pre-rough rolled bar from an appropriate upstream rough rolling station ( 2 ) and to deliver it, after having worked it, to a downstream finishing station ( 4 ),    the method comprising, in the order indicated, the following operations:    a first rolling passage (U 1 ) in said second universal stand ( 32 );    a first rolling passage (E 1 ) in said high edging stand ( 31 );    a first rolling passage (U 2 ) in said first universal stand ( 30 ),    characterised by the fact that said three stands ( 30 ,  31 ,  32 ) are placed at such a distance between each other that said bar can be held simultaneously in all three of said stands ( 30 ,  31 ,  32 ) during rolling operations.    
   
   
       2 ) The method according to  claim 1 , characterised by the fact that said first rolling passage (U 1 ) in said second universal stand ( 32 ) is performed with a reduction ratio (ρ 1 ) greater than the reduction ratio (ρ 2 ) with which is performed said first rolling passage (U 2 ) in said first universal stand ( 30 ).  
   
   
       3 ) The method according to  claim 2 , characterised by the fact that said reduction ratio (ρ 1 ) with which is performed said first rolling passage (U 1 ) in said second universal stand ( 32 ) is comprised of between around 10% and around 30%, and said reduction ratio (ρ 2 ) with which is performed said first rolling passage (U 2 ) in said first universal stand ( 30 ) is comprised of between around 3% and; around 25%.  
   
   
       4 ) The method according to  claim 3 , characterised by the fact that said reduction ratio (ρ 1 ) with which is performed said first rolling passage (U 1 ) in said second universal stand ( 32 ) is equal to around 20%, and said reduction ratio (ρ 2 ) with which is performed said first rolling passage (U 2 ) in said first universal stand ( 30 ) is equal to around 10%.  
   
   
       5 ) The method according to one or more of the preceding claims, characterised by the fact that said first rolling passage (U 1 ) in said second universal stand ( 32 ) is preceded by a second rolling passage (E 2 ) in said high edging stand ( 31 ).  
   
   
       6 ) The method according to one or more of the preceding claims, characterised by the fact that said following said first rolling passage (U 1 ) in said second universal stand ( 32 ) and prior to said first rolling passage (E 1 ) in said high edging stand ( 31 ) is carried out on said bar for rolling a second rolling passage (U 3 ) in said second universal stand ( 32 ).  
   
   
       7 ) The method according to  claim 6 , characterised by the fact that said second rolling passage (U 3 ) in said second universal stand ( 32 ) is performed with a reduction ratio (ρ 3 ) comprised of between around 10% and around 30%.  
   
   
       8 ) The method according to one or more of the preceding claims, characterised by the fact that following said first rolling passage (U 2 ) in said first universal stand ( 30 ) is performed a third rolling passage (E 3 ) in said high edging stand ( 31 ).  
   
   
       9 ) The method according to one or more of the preceding claims, characterised by the fact that immediately following said first rolling passage (U 2 ) in said first universal stand ( 30 ), in said first universal stand ( 30 ) is performed a second rolling passage (U 4 ).  
   
   
       10 ) The method according to  claim 9 , characterised by the fact that said second rolling passage (U 4 ) carried out in said first universal stand ( 30 ) is performed with a reduction ratio (ρ 4 ) comprised of between around 3% and around 20%;  
   
   
       11 ) The method according to one or more of the preceding claims, characterised by the fact that said third rolling passage (E 3 ) in said high edging stand ( 31 ) is successive to said second rolling passage (U 4 ) in said first universal stand ( 30 ).  
   
   
       12 ) The method according to one or more of the preceding claims, characterised by the fact of comprising a series of operations substantially constituted of the following rolling passages, in the sequence indicated: 
 said second rolling passage (E 2 ) in said high edging stand ( 31 ) on exiting from said pre-rough rolling station ( 2 )    said first rolling passage (U 1 ) in said second universal stand ( 32 )    said second rolling passage (U 3 ) in said second universal stand ( 32 )    said first rolling passage (E 1 ) in said high edging stand ( 31 )    said first rolling passage (U 2 ) in said first universal stand ( 30 )    said second rolling passage (U 4 ) in said first universal stand ( 30 ).    said third rolling passage (E 3 ) in said high edging stand ( 31 ),    A rolling passage (UF) in said finishing station ( 4 ).    
   
   
       13 ) A method for the production of rails and similar products through rolling comprising a finishing operation (UF) of a bar transformed to a semi-worked rail, characterised by the fact that said finishing operation (UF) comprises a rolling passage in a universal stand ( 4 ) fitted with a first vertical roll ( 402 ,  422 ) able to work the base (B) of said rail, and a second vertical roll ( 403 ,  423 ) able to work the head (T) of said rail, and said first and second vertical rolls are able to roll the head (T) and said base (B) simultaneously.  
   
   
       14 ) The method according to  claim 13 , characterised by the fact that said finishing operation (UF) is performed with a reduction ratio (ρF) comprised of between around 1% and around 15%.  
   
   
       15 ) The method according to claims  13  and/or  14 , characterised by the fact that said vertical rolls ( 403 ,  423 ) able to work said head (T) of said semi-worked rail is able to roll rails comprising a head (T) comprising 
 a central rollable surface (T 1 ), able to vertically support the wheels of a railway vehicle    two lateral flanks (T 2 , T 3 ) located or vertically or with a slight inclination with respect to vertical when said rail is installed, and able to supply a lateral support to said wheels of said railway vehicle    two curved joining area (T 4 , T 5 ), each of which gradually joins said central surfaces (T 1 ) to one of said lateral flanks (T 2 , T 3 ),    and said vertical rolls ( 403 ,  423 ) able to work said head (T) of said semi-worked rail comprising a rolling groove which in turn comprises a central zone able to deform and refinish said central rollable surfaces (T 1 )    
   
   
       16 ) The method according to  claim 15 , characterised by the fact that said rolling groove of said vertical rolls ( 403 ,  423 ), able to work said head (T) of said semi-worked rail, comprising two lateral surfaces, placed to the sides of said central areas and able to contain and conform said lateral flanks (T 2 , T 3 ) of said head (T) of said semi-worked rail.  
   
   
       17 ) A rolling plant for the implementation of a method according to one or more preceding claims, said plant comprising a reversible intermediate working section ( 3 ) able to receive a pre-rough rolled bar from an appropriate upstream rough rolling station ( 2 ) and to supply it, after having worked it, to a downstream finishing station ( 4 ), where said intermediate working section ( 3 ) comprises, located in succession along at least one rolling axis, a first universal stand ( 30 ) and a high edging stand ( 31 ), comprising a second universal stand ( 32 ) located, along said at least one rolling axis, such that said high edging stand ( 31 ) is placed between said first and second universal stands ( 30 ,  32 ), characterised by the fact that said three stands ( 30 ,  31 ,  32 ) are located at such distances from each other that said bar can be held simultaneously in all three said stands ( 30 ,  31 ,  32 ) during rolling operations.  
   
   
       18 ) A plant according to  claim 17 , characterised by the fact that said three stands ( 30 ,  31 ,  32 ) of said intermediate rolling section ( 3 ) are placed one after the other, is without the interposition of further rolling stands.  
   
   
       19 ) A plant according to claims  17  and/or  18 , characterised by the fact of comprising a finishing station ( 4 ) comprising in turn a finishing stand placed at such a distance from said intermediate working section ( 3 ) that, when said finishing stand works a finishing passage on said bar (UF), said bar is not held in any of the said stands ( 30 ,  31 ,  32 ) of said intermediate working section ( 3 ).