| 摘要 |
In forming a heat exchanger, a tube of the heat exchanger is expanded by a bullet, which is attached to a mandrel. The tube is projected from both end faces of a piled body formed by piling a plurality of fins. Each fin has a tube hole through which the tube passes. The fins and the tube are integrated by expansion of the tube. A first projected section of the tube, which is projected from one end face of the piled body and which has been expanded by the bullet, is held at a prescribed position. The bullet is pressed toward a second projected section, which is projected from the other end face of the piled body. As the bullet moves toward the second projected section, it expands the tube. The second projected section of the tube is allowed to contract during the tube expansion. An object of the present invention is to prevent adhesion of adjacent fins and irregularities in fin clearances between adjacent fins.
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