| 摘要 |
A tube is composed of a first plate and a second plate which are opposed and engaged with each other. In a first region on both end sides of the tube, the first plate is formed into a shape in which an edge portion of the first plate is laid along a bent portion of the second plate so that an outer wall face of the tube forms a continuous face. In a second region of the tube, the first plate is formed into a shape in which the edge portion of the first plate is laid between the edge portion of the second plate and the bent portion of the second plate.
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