Method for producing h-shaped steel

Abstract

An H-shaped steel product having a larger flange width as compared with conventional ones is efficiently and stably produced by performing flat shaping and rolling of a large-size raw blank without bringing about problems such as elongation in a web height direction and deformation of a flange corresponding part. A rough rolling step includes an edging rolling step, and a flat rolling step of performing rolling of a web part by rotating the material to be rolled after completion of the edging rolling step, upper and lower caliber rolls of at least one caliber of calibers configured to perform the flat rolling step include recessed parts configured to form a raised part at a middle of a web part of the material to be rolled, the recessed parts being provided at roll barrel length middle parts, the caliber configured to perform the flat rolling step further includes a raised part eliminating caliber configured to reduce the raised part and perform inner size widening of the web part of the material to be rolled on the material to be rolled in which the raised part is formed, rolling and shaping in the raised part eliminating caliber is performed on the material to be rolled after forming the raised part in the caliber having the recessed parts configured to form the raised part, and rolling and shaping of forming the raised part is not performed after a reduction of the raised part.

1 . A method for producing H-shaped steel, the method comprising:
 a rough rolling step;   an intermediate rolling step; and   a finish rolling step, wherein:   the rough rolling step comprises: an edging rolling step of rolling and shaping a material to be rolled into a predetermined almost dog-bone shape; and a flat rolling step of performing rolling of a web part by rotating the material to be rolled after completion of the edging rolling step by 90° or 270°;   upper and lower caliber rolls of at least one caliber of calibers configured to perform the flat rolling step comprise recessed parts configured to form a raised part at a middle of a web part of the material to be rolled, the recessed parts being provided at roll barrel length middle parts of the upper and lower caliber rolls;   the caliber configured to perform the flat rolling step further comprises a raised part eliminating caliber configured to reduce the raised part and perform inner size widening of the web part of the material to be rolled on the material to be rolled in which the raised part is formed;   rolling and shaping in the raised part eliminating caliber is performed on the material to be rolled after forming the raised part in the caliber having the recessed parts configured to form the raised part; and   rolling and shaping of forming the raised part is not performed after a reduction of the raised part.   
     
     
         2 . The method for producing the H-shaped steel according to  claim 1 , wherein:
 the rolling and shaping in the raised part eliminating caliber is performed in a plurality of passes; and   the rolling and shaping is performed in a state where a flange inner surface of the material to be rolled and a caliber roll are brought into contact with each other in at least one or more passes of the plurality of passes.   
     
     
         3 . The method for producing the H-shaped steel according to  claim 1 , wherein:
 the rolling and shaping in the raised part eliminating caliber is performed in a plurality of passes; and   the rolling and shaping is performed in a state where a flange inner surface of the material to be rolled and a caliber roll are brought into contact with each other in a first pass of the plurality of passes.   
     
     
         4 . The method for producing the H-shaped steel according to  claim 1 , wherein
 in the rolling and shaping in the raised part eliminating caliber, elimination of the raised part is performed partially, and a remaining raised part is eliminated by rolling and shaping in an optional caliber at a subsequent stage.   
     
     
         5 . The method for producing the H-shaped steel according to  claim 1 , wherein
 a width of the raised part formed in the flat rolling step is set to 25% or more and 50% or less of a web part inner size of the material to be rolled.   
     
     
         6 . The method for producing the H-shaped steel according to  claim 1 , wherein
 a reduction ratio with respect to the raised part in the raised part eliminating caliber is 2.1 or less.   
     
     
         7 . The method for producing the H-shaped steel according to  claim 1 , wherein:
 the edging step is performed by a plurality of calibers, the number of the plurality of calibers being four or more;   shaping in one or a plurality of passes is performed on the material to be rolled in the plurality of calibers;   a first caliber and a second caliber of the plurality of calibers are formed with projections configured to create splits vertical to a width direction of the material to be rolled so as to form divided parts at end parts of the material to be rolled; and   the calibers after a third caliber of the plurality of calibers are formed with projections configured to come into contact with the splits and sequentially bend the formed divided parts.