| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the tongue in both end parts of an H-beam rough shape material, the deviation of flange width in the length direction, the complication of the management of a base stock and the increase of inventory and cost in the manufacture of an H-beam for which a material having a rectangular cross section is used. SOLUTION: In a break-down mill, flat rolls are arranged near to a flange forming box pass group and a finishing box pass, after forming a guide groove in the middle of minor side parts of the cross section of the material having the rectangular cross section by using the 1st pass of the flange forming box pass group, immediately, the material having the rectangular cross section is reduced in the thickness direction by using the flat rolls and, successively, the material having the rectangular cross section is successively reduced breadthways by part or all passes of the flange forming box pass group and the finishing box pass.
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