Abstract: A heat exchanger includes a pair of header pipes, tubes disposed between the header pipes, and radiation fins provided along the tubes. Each of the header pipes has a plurality of connection holes for the tubes. Each of the header pipes is formed by bending a longitudinal flat plate in the form of a pipe and connecting the side edge portions of the bent plate to each other. The side edge portions of the bent longitudinal plate have connecting portions which are connected to each other with a junction area larger than the cross-sectional area defined by the thickness and length of each header pipe at a position other than the side edge portions. The connection holes are processed before the longitudinal flat plate is bent, and therefore, can be easily and precisely formed at desired positions. The manufacture of the heat exchanger can be simplified and the cost for the manufacture can be reduced.

Abstract: A method for manufacturing a header pipe of a heat exchanger wherein a planar raw plate is bent to have a U-shaped cross section in a first bending step. Connection holes to which heat exchanger tubes are to be connected are opened directly on the curved portion of the U-shaped raw plate formed by the first bending step. Thereafter, the side portions of the U-shaped raw plate are bent inward to abut their terminal ends to each other. Since the connection holes are formed directly on the curved portion of the raw plate, the size and shape of a punch for opening the connection holes may be set to a size and shape corresponding to the size and shape of the end portions of the heat exchanger tubes. Thus, the desired connection holes can be formed easily and precisely. Even if a deformation occurs on the side portions of the U-shaped raw plate in the connection hole opening step, such a deformation can be corrected in a second bending step.