| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming a circular tube by simple operation by making a metal plate meet to an upward circular-arcuate upper guide and a downward circular-arcuate lower guide by utilizing the dead weight of a metal plate while dispersing with a press, bending rollers or the like. SOLUTION: After forming the middle part of the metal plate 20 into a circular-arc shape by supporting and elevating the middle part with a circular- arcuate upper guide 2a in an upper apparatus 1A and after forming both side parts of the metal plate 20 into the circular-arc shape by guiding them to a circular-arcuate lower guide 2b of a lower apparatus 1B, the circular tube 20A is formed by joining respective tips of these side plate parts and this tube is taken out after making this tube into the state of falling sideways.
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