Method for producing a heat exchanger having a flat tube and header pipes

A method for producing a heat exchanger comprising a flat metal tube of an aluminum alloy for conveying fluid, and two header pipes joined respectively onto opposite ends of said flat tube, which comprises the steps of preparing said flat tube and said header pipes of an aluminum alloy other than a brazing filler metal, and preparing two brazing filler members of an aluminum alloy brazing filler metal, each of said header pipes having an axial slot in a side wall for receiving an end of said flat tube therethrough, each brazing filler member comprising an elongated plate portion arcuately curved transversely with a lengthwise elongated opening therein, and with a flat sleeve portion projecting from an outer surface of said elongated plate portion overlying said elongated opening in registration therewith, said sleeve portion having an inner surface congruent with the perimeter of said elongated opening, said sleeve portion inner surface and said elongated opening having an inner contour slightly larger than the outer contour of said flat tube;

• inserting each of opposite ends of said flat tube through both said sleeve portion and said elongated opening of a respective brazing filler member, and thereafter inserting each of said flat tube ends into a respective one of said header pipes through said axial slot therein while bringing said arcuately curved plate portions in contact with the outer surface of the corresponding header pipe, and then heating said brazing filler members together with said header pipes and end portions of said flat tube to melt said brazing filler members, so that said header pipes are joined and brazed to the corresponding ends of said flat tube.