| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a corner drop-out shape steel forming rounded sections at flange tips of plural kinds of rolled H-steel having various dimensions without introducing new facilities.SOLUTION: A first intermediate rolled material 25-1 is obtained by subjecting a rough rolled material 22 having a dog bone shape to intermediate universal rolling by a reverse method with plural passes so that the value of draft balance becomes 0.3 or more in the final pass. Next, flanges 25-1f of the first intermediate rolled material is roll-reduced by intermediate rolling of 1 pass by an edger rolling mill having rounded sections for corner drop-out of inner corners of flanges of the first intermediate rolled material at grooved corners, and a second intermediate rolled material 25-2 is obtained in which flange tips 27 are made thicker than flange centers 28. Finally, the second intermediate rolled material is subjected to finish universal rolling of 1 pass by a finish universal rolling mill having vertical rolls in which grooves for corner drop-out of outer corners of flanges 25-2f of the second intermediate rolled material are arranged. |
