PURPOSE: To efficiently manufacture the box-type steel shape, by rolling the heated steel billet to form the hooked part to be the corner of the box, by forming it into the box shape, and by welding its butted edges.
CONSTITUTION: The heated steel billet of flat section is passed through the breakdown mill, the first edger, the first universal roughing mill, and the second roughing mill, in this order. The angle-type hooked part 28 is formed in the middle of the rolled material 20, and other hooked parts 29, 30, 31, are formed. This rolled material 20 is passed through the second edger. The hooked part 28 is bent inward by the caliber 32a of the upper roll 32 and the idle roll 35. The rolled material 20 is bent into right angle by the upper roll 41 possessing the transfer caliber 41a as the finishing roll and the corresponding roller 43. Next, a special guide 52 is inserted into the gap between the upper roll 48 and the lower roll 50, and the rolled material 20 is bent into the box shape. Finally, the seam welding is applied to the butted both edges of the material 20, and the box-type steel shape is completed.
GISHI TAKAO
NAGAHASHI SHINICHI
