| 摘要 |
PURPOSE:To enable formation of band steel having wide range of thcikness into steel pipes using signal roll, by dividing an upper roll into left and right rolls, forming two R parts of different forming radius of curvature, and enabling reversed fitting of left and right rolls. CONSTITUTION:In the case where the thickness (t) of a band steel 15 is within the range shown by the equation I (t1=R0-R1, R0; forming radius of curvature of lower roll 14, R1; forming radius of curvature of the first R part 20A), two edges are perfectly bend by the caliber formed by R part 20A of left and right rolls 16, 17 and R part of the roll 14. When the thickness of the band steel 15 is within the range shown by the equation II (t1, R0 are as mentioned above, t2=R0-R2 R2;forming radius of curvature of the second R part, where t2 t1+ 2.0mm.), following steps are taken. That is, rolls 16, 17 are reversely fitted to the roll shaft 19, and two edges of the band steel 15 is perfectly bent by the caliber formed by the R part 20B and R part of the lower roll 14. |
