| 摘要 |
PURPOSE:To decrease man-hour to reduce manufacturing cost and make the number of parts to one piece by reducing the outer diameter of the fins so as to be smaller than the outer diameter of original tube. CONSTITUTION:A thick-walled tube is machined so that the outer diameters of the fins after risen up will never become larger than the outer diameter of the original tube under remaining both ends 11, 12 as well as support sections 13, 14. The fins 15 are worked on the parts which are machined. According to this method, the outer diameter of the fin may be made smaller than the diameter of the original tube even without applying expanding works for both ends of the tube and the fins may be inserted into a tube plate without touching with the plate in case the heat transfer tubes are inserted into a heat exchanger. The damage of the heat transfer tube due to hammering against a support plate, which is caused by the vibration of the heat transfer tube, may be prevented by the support sections 13, 14 even when rings for preventing hammering are not mounted to the tube. |
