| 摘要 |
PURPOSE:To improve forming and butting and even from a large diameter thin tube, to prepare a true circle without crop in forming an electric welded tube by semi-cage roll system by restraining the edge of steel plate using a V-roll in the upper stream side of the first fin pass roll. CONSTITUTION:A steel plate S is bent to U-shape by a break down roll 2 and an inner cage roll 4, and then bent gradually to true circle by combination of a V-roll 1 that presses the edge (a) of the steel plate and an outer roll 5, and enters the first fin pass roll 3. The welded tube is improved by this forming and butting process. By restriction of the V-roll, the generation of crop is prevented and a good true circle tube can be obtained even in the case of a large diameter thin tube. |
