| 摘要 |
PURPOSE:To prepare a rough shaped billet without thinning the thickness, by forming a blank material of vertically and laterally symmetrical H-shape section into an asymmetrical H-shape section with a flange possessing different length of legs standing from the web surface through the first caliber of the breakdown mill, and then, by equalizing the elongations of the web and the flange through the second caliber in the case of forming the recess part in the edge of flange. CONSTITUTION:A blank material 20, prepared in a vertically and laterally symmetrical H-shape section through the blooming or the continuous casting process, is fed to the breakdown mill provided with the first and the second calibers 23, 30. At fist the blank material 20 is passed through the first caliber 23 and is roll formed by the upper and lower caliber rolls 24, 25 into a vertically and laterally asymmetrical H-shaped section in which the lengths of upper and lower legs of the flange 27 standing from the surface of web 26 are different. This rough shaped billet 28 is passed through the second caliber 30 and is roll formed by the upper and lower caliber rolls 31, 32 into the finally rough shaped billet 33 in which the elongations of the web 26 and the flange 27 are almost equal and the recess part 35 is formed in the projecting part 36 of the flange 27. |
