Abstract: In the method and apparatus of making a header pipe, the end faces of the edge portions of a flat plate, which have been respectively cut into a given shape according to a trimming operation, are then respectively face-struck into a linear shape. Also, in the trimming operation, each of the edge portions of the flat plate is cut into a shape having a larger dimension than that of a finally required shape thereof, and the thus produced excess length portions of the edge portions are worked by compressing when a pair of semidivided cylindrical portions are butted against each other. Since a connecting portion situated between the pair of semidivided cylindrical portions is always pressed with a given pressure, the working properties of the connecting portion in the molding operation are prevented from being revived.

Abstract: The end faces of the edge portions of a flat plate, which have been respectively cut into a given shape according to a trimming operation, are then respectively face-struck into a linear shape. Also, in the trimming operation, each of the edge portions of the flat plate is cut into a shape having a larger dimension than that of a finally required shape thereof, and the thus produced excess length portions of the edge portions are worked by compressing when a pair of semidivided cylindrical portions are butted against each other. Since a connecting portion situated between the pair of semidivided cylindrical portions is always pressed with a given pressure, the working properties of the connecting portion in the molding operation are prevented from being revived.

Abstract: The end faces of the edge portions of a flat plate, which have been respectively cut into a given shape according to a trimming operation, are then respectively face-struck into a linear shape. Also, in the trimming operation, each of the edge portions of the flat plate is cut into a shape having a larger dimension than that of a finally required shape thereof, and the thus produced excess length portions of the edge portions are worked by compressing when a pair of semidivided cylindrical portions are butted against each other. Since a connecting portion situated between the pair of semidivided cylindrical portions is always pressed with a given pressure, the working properties of the connecting portion in the molding operation are prevented from being revived.

Abstract: In the method for manufacturing a pipe with a partition, a flat plate is molded such that a pair of semidivided cylindrical portions are arranged in parallel to each other through a connecting portion, a U-shaped partition forming portion is so formed in the pair of semidivided cylindrical portions as to project inwardly thereof, and the partition forming portion is compressed from the two sides thereof to thereby form a semidivided partition portion. The connecting portion situated between the partition forming portion is cut to thereby form an escape hole.

Abstract: In the end-closed pipe of the invention, a pair of half-cylindrical portions are opposed to each other to form a pipe portion, and part of an end portion of each of the half-cylindrical portions is folded or formed into a V-shaped or a U-shaped cross-section to form a half closure portion projecting from an inner surface thereof, and the half closure portions of the two half-cylindrical portions are bonded together so as to form a closure portion at the end portion of the pipe. Two closure portions are formed at the both ends of the pipe, and a partition portion which has same structure as that of the closure portion is formed between the two closure portions. In the heat exchanger header of the invention, a plurality of tube insertion holes are formed in the above end-closed pipe, and are spaced from one another along an axis thereof.

Abstract: The leading end portion of a caulking pawl portion formed in the end portion of a pipe main body is formed integrally with the pipe main body through the side surface portion of the caulking pawl portion which has a larger width in the longitudinal direction thereof than the width of the leading end portion in the longitudinal direction thereof. At the same time, the leading end portion of the caulking pawl portion is also formed integrally with the cap side end of the side surface portion of the caulking pawl portion.

Abstract: In an end-closed pipe of a pair of half-cylindrical portions are opposed to each other to form a pipe portion, and part of an end portion of each of the half-cylindrical portions is folded or formed into a V-shaped or a U-shaped cross-section to form a half closure portion projecting from an inner surface thereof, and the half closure portions of the two half-cylindrical portions are bonded together so as to form a closure portion at the end portion of the pipe. Two closure portions are formed at the both ends of the pipe, and a partition portion which has same structure as that of the closure portion is formed between the two closure portions. In the heat exchanger header a plurality of tube insertion holes are formed in the above end-closed pipe, and are spaced from one another along an axis thereof.