| 摘要 |
PROBLEM TO BE SOLVED: To ensure strong fixation at a joint and provide a small width size heat exchanger flat tube. SOLUTION: The height of a bead 13 opposing to a joint portion between opposite side edge portions 12A, 12 of a plate 12 is previously set lower by a size smaller than the thickness size t of the plate than the height H1 of the bead at a position not opposing to the joint portion. Accordingly, when a plate 13 is bent, a joint portion between the side edge portions 12A, 12B can be placed on the top of the bead 13 at the opposing position and pressurized for secure joint. Further, with the pressurization a plate 12 inside surface can be securely joined also with the top portion of the bead 14 located at the position not opposing to the joint portion. Thus, junction of the joint portion can be secured for secure fixing.
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