Method and apparatus for producing steel intermediate products

Abstract

Methods and apparatuses for continuously producing steel intermediate products are disclosed. Liquid steel is cast into plural moulds to continuously produce plural bloom strands using continuous casting apparatus. Subsequently, one or more of the bloom strands is fed in-line to respective rolling mills configured to hot roll the input continuously cast bloom strands to produce rolled billets.

1 . A method of continuously producing steel intermediate products, comprising:
 casting liquid steel into plural moulds to continuously produce plural bloom strands; and   feeding one or more of the bloom strands in-line to respective rolling mills configured to be selectively engageable to hot roll the input continuously cast bloom strands to produce rolled billets,   wherein the rolling mills comprise two or more cantilever rolling mill stands in which bearing supports for the rollers of each stand support the rollers at only one end, and wherein the angle of the axes of the rollers of the first cantilever rolling mill stand for a given bloom is set at 45 degrees to the top surface of the bloom and wherein the angle of the axes of the subsequent rolling mill stands is set at 90 degrees to each other.   
     
     
         2 . A method as claimed in  claim 1 , wherein the cast bloom strands fed in-line to the rolling mills are still hot from the continuous casting, and wherein no additional reheating of the blooms is performed between the casting and hot rolling. 
     
     
         3 . A method as claimed in  claim 1 , wherein the bloom strands have a cross sectional area above 230 square centimetres, and wherein the rolled billets have a cross sectional area below 230 square centimetres. 
     
     
         4 . A method as claimed in  claim 1 , further comprising:
 feeding the bloom strands through respective straightening rollers; and   operating each rolling mill at a speed based on a reference speed of the straightening rollers of the particular bloom strand fed to that rolling mill.   
     
     
         5 . A method as claimed in  claim 1 , wherein a drive mechanism and a motor for each cantilever rolling mill stand is arranged outside the outermost strands produced by the continuous casting. 
     
     
         6 . A method as claimed in  claim 1 , wherein each of the rolls for a given cantilever rolling mill stand is driven by an individual motor. 
     
     
         7 . A method as claimed in  claim 1 , wherein each rolling mill comprises at least two, or preferably at least four, in-line cantilever rolling mill stands arranged to roll increasingly small billet sizes. 
     
     
         8 . A method as claimed in  claim 1 , wherein a housing for the bearing supports for each cantilever rolling mill stand is configured as a replaceable cassette. 
     
     
         9 . A method as claimed in  claim 1 , wherein protective cooling or insulating jackets are provided around a housing for the bearing supports and/or a motor and/or a drive mechanism for each cantilever rolling mill stand. 
     
     
         10 . A method as claimed in  claim 1 , wherein only one or both of the outermost strands of the plurality of continuously cast bloom strands is hot rolled into a billet, and wherein at least one innermost bloom strand is provided. 
     
     
         11 . A method as claimed in  claim 1 , wherein the plural bloom strands are cast in a process of sequence continuous casting. 
     
     
         12 . A method as claimed in  claim 1 , wherein the rollers of the cantilever rolling mill stands are separated from each another to at least a distance wide enough for the cantilever rolling mill stands to clear the bloom and be moved out of the bloom casting line. 
     
     
         13 . Apparatus for continuously producing steel intermediate products, comprising:
 continuous casting apparatus arranged to, in use, continuously produce plural bloom strands; and   one or more in-line rolling mills each arranged to be selectively engageable to receive and hot roll, in use, one of the continuously cast bloom strands to produce rolled billets,   wherein the rolling mills comprise two or more cantilever rolling mill stands in which bearing supports for the rollers of each stand support the rollers at only one end, and wherein the angle of the axes of the rollers of the first cantilever rolling mill stand for a given bloom is set at 45 degrees to the top surface of the bloom and wherein the angle of the axes of the subsequent rolling mill stands is set at 90 degrees to each other.   
     
     
         14 . Apparatus as claimed in  claim 13 , wherein the apparatus is arranged such that the cast bloom strands fed in-line to the rolling mills in use are still hot from the continuous casting, and wherein no apparatus is provided arranged to performing additional reheating of the blooms between the casting and hot rolling in use. 
     
     
         15 . Apparatus as claimed in  claim 13 , wherein continuous casting apparatus comprises a tundish arranged to collect liquid steel and provide said liquid steel to plural moulds arranged side by side to continuously produce plural bloom strands. 
     
     
         16 . Apparatus as claimed in  claim 13 , wherein the continuous casting apparatus is configured to produce bloom strands having a cross sectional area above 230 square centimetres, and wherein the in-line rolling mills are configured to roll billets having a cross sectional area below 230 square centimetres. 
     
     
         17 . Apparatus as claimed in  claim 13 , further comprising:
 for each bloom strand, respective straightening rollers arranged to receive and straighten the bloom strand;   wherein each rolling mill is configured to operate at a speed based on a reference speed of the straightening rollers of the particular bloom strand fed to that rolling mill.   
     
     
         18 . Apparatus as claimed in  claim 13 , wherein a drive mechanism and a motor for each cantilever rolling mill stand is arranged outside the outermost strands produced by the continuous casting. 
     
     
         19 . Apparatus as claimed in  claim 13 , further comprising motors arranged to individually drive each of the rolls for a given cantilever rolling mill stand. 
     
     
         20 . Apparatus as claimed in  claim 13 , wherein the angle of the axes of the subsequent rolling mill stands is set at 90 degrees to each other. 
     
     
         21 . Apparatus as claimed in  claim 13 , wherein each rolling mill comprises at least two, or preferably at least four, in-line cantilever rolling mill stands arranged to roll increasingly small billet sizes. 
     
     
         22 . Apparatus as claimed in  claim 13 , wherein a housing for the bearing supports for each cantilever rolling mill stand is configured as a replaceable cassette. 
     
     
         23 . Apparatus as claimed in  claim 13 , further comprising protective cooling or insulating jackets provided around a housing for the bearing supports and/or a motor and/or a drive mechanism for each cantilever rolling mill stand. 
     
     
         24 . Apparatus as claimed in  claim 13 , wherein only one or both of the outermost strands of the plurality of continuously cast bloom strands is hot rolled into a billet, and wherein at least one innermost bloom strand is provided. 
     
     
         25 . Apparatus as claimed in  claim 13 , wherein the plural bloom strands are cast in a process of sequence continuous casting. 
     
     
         26 . Apparatus as claimed in  claim 13 , wherein the rollers of the cantilever rolling mill stands are separated from each another to at least a distance wide enough for the cantilever rolling mill stands to clear the bloom and be moved out of the bloom casting line.