Method for producing h-shaped steel

Abstract

To efficiently and stably produce an H-shaped steel product with a flange width larger than a conventional flange width by creating deep splits on end surfaces of a material such as a slab using projections in acute-angle tip shapes and sequentially bending flange portions formed by the splits to thereby suppress occurrence of shape defects in a material to be rolled and reduce growth of a crop portion. A first caliber and a second caliber of a plurality of calibers are formed with projections configured to create splits vertically with respect to a width direction of the material to be rolled to form divided parts at end portions of the material to be rolled; a third caliber and subsequent calibers excluding a final caliber of the plurality of calibers are formed with projections configured to come into contact with the splits to sequentially bend the divided parts formed; and in at least one pass or more of rolling and shaping in the plurality of calibers, the rolling and shaping is performed with a rolling roll gap for a predetermined section at a rear end portion in a rolling longitudinal direction of the material to be rolled expanded as compared with a rolling roll gap for other than the predetermined section.

1 - 11 . (canceled) 
     
     
         12 . A method for producing H-shaped steel, the method comprising:
 a rough rolling step;   an intermediate rolling step; and   a finish rolling step, wherein:   a rolling mill that performs the rough rolling step is engraved with a plurality of calibers configured to roll and shape a material to be rolled, the number of the plurality of calibers being five 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 vertically with respect to a width direction of the material to be rolled to form divided parts at end portions of the material to be rolled;   a third caliber and subsequent calibers excluding a final caliber of the plurality of calibers are formed with projections configured to come into contact with the splits to sequentially bend the divided parts formed;   the final caliber of the plurality of calibers is a flat shaping caliber;   in the second caliber and subsequent calibers excluding the final caliber of the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with peripheral surfaces of the calibers in shaping in at least one pass or more; and   in at least one pass or more of rolling and shaping in the plurality of calibers, the rolling and shaping is performed with a rolling roll gap for a predetermined section at a rear end portion in a rolling longitudinal direction of the material to be rolled expanded as compared with a rolling roll gap for other than the predetermined section.   
     
     
         13 . The method for producing the H-shaped steel according to  claim 12 , wherein
 a tip portion angle of the projections formed in the first caliber and the second caliber is 25° or more and 40° or less.   
     
     
         14 . The method for producing the H-shaped steel according to  claim 12 , wherein
 in all passes of rolling and shaping in the first caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         15 . The method for producing the H-shaped steel according to  claim 12 , wherein
 in all passes of rolling and shaping in at least the third caliber and a fourth caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         16 . The method for producing the H-shaped steel according to  claim 12 , wherein
 in a pass where reduction is performed with the end surfaces of the material to be rolled are in contact with peripheral surface of the second caliber in the rolling and shaping in the second caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         17 . The method for producing the H-shaped steel according to  claim 12 , wherein
 in all passes of rolling and shaping in the final caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         18 . The method for producing the H-shaped steel according to  claim 12 , wherein
 in all passes of rolling and shaping in all calibers excluding the first caliber and the final caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         19 . The method for producing the H-shaped steel according to  claim 12 , further comprising:
 an intermediate crop cutting step performed only on a web portion of the material to be rolled after the rough rolling step and at a preceding stage of the intermediate rolling step.   
     
     
         20 . The method for producing the H-shaped steel according to  claim 12 , wherein
 a crop-shaped portion formed at an end portion in a longitudinal direction of the material to be rolled is removed only after completion of all of the rough rolling step, the intermediate rolling step, and the finish rolling step.   
     
     
         21 . The method for producing the H-shaped steel according to  claim 12 , wherein
 the rolling mill that performs the rough rolling step is provided with a reduction mechanism configured to change a roll gap of a caliber roll of the rolling mill.   
     
     
         22 . An H-shaped steel product produced by the method for producing the H-shaped steel according to  claim 12 , wherein
 a web height is 1000 mm or more, or a flange width is 400 mm or more.   
     
     
         23 . The method for producing the H-shaped steel according to  claim 13 , wherein
 in a pass where reduction is performed with the end surfaces of the material to be rolled are in contact with peripheral surface of the second caliber in the rolling and shaping in the second caliber of the plurality of calibers, the rolling and shaping is performed with the rolling roll gap for the predetermined section at the rear end portion in the rolling longitudinal direction of the material to be rolled expanded as compared with the rolling roll gap for the other than the predetermined section.   
     
     
         24 . The method for producing the H-shaped steel according to  claim 13 , further comprising:
 an intermediate crop cutting step performed only on a web portion of the material to be rolled after the rough rolling step and at a preceding stage of the intermediate rolling step.   
     
     
         25 . The method for producing the H-shaped steel according to  claim 13 , wherein
 a crop-shaped portion formed at an end portion in a longitudinal direction of the material to be rolled is removed only after completion of all of the rough rolling step, the intermediate rolling step, and the finish rolling step.   
     
     
         26 . The method for producing the H-shaped steel according to  claim 23 , further comprising:
 an intermediate crop cutting step performed only on a web portion of the material to be rolled after the rough rolling step and at a preceding stage of the intermediate rolling step.   
     
     
         27 . The method for producing the H-shaped steel according to  claim 23 , wherein
 a crop-shaped portion formed at an end portion in a longitudinal direction of the material to be rolled is removed only after completion of all of the rough rolling step, the intermediate rolling step, and the finish rolling step.