| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a fin for a heat exchanger capable of forming a smooth tubular protrusion in a shortened process than before. SOLUTION: When pierce-burring the tubular protrusion 20 of prescribed height which protrudes in one side of a metal sheet 12 and forming the tubular protrusion 20 in a collar part 10 passing through a heat exchanging tube to manufacture the fin for the heat exchanger, an opening part having a larger diameter than the opening diameter of the tubular protrusion 20 is opened in one side of the metal sheet 12 and a recessed part 16 in which a projection 16a protrudes in the other side of the metal sheet 12 is formed. Then, in order to form the tubular protrusion 20 from which the projection 16a of the recessed part 16 protrudes in the one side of the metal sheet 12, the tip end portion of a projection punch 18 having a smaller diameter than the opening diameter of the recessed part 16 protrudes in the one side direction of the metal sheet 12 from the tip end outer peripheral surface side of the projection 16a of the recessed part 16 without crushing a slackened part formed in a part of the projection 16a of the recessed part 16. COPYRIGHT: (C)2005,JPO&NCIPI
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