Method and apparatus for producing a header with openings

Abstract

Method and apparatus for forming a tubular heat-exchanger header includes a tool die having a chamber dimensioned to receive the header, the chamber conforming to an outer peripheral contour of the header. A plurality of guide passages are formed through the tool die for insertion of a corresponding number of punches. The guide passages expose the areas of the header to be pierced for forming the openings. The ends of the tubular header are each sealed with a stopper. Fluid is supplied into the header using a fluid supply through one of the stoppers and the pressure is raised to a predetermined internal pressure. While the pressure is maintained, the punches are passed through the guide passages to simultaneously pierce through the header wall to form the openings. The header thus formed has an inwardly directed rim around each opening, which rim sealingly bears against the periphery of the punch to maintain the pressure during piercing. The inwardly directed rim has an insertion slope adapted to guide a heat exchanger tube to be inserted in the opening, and an inner lip extending wider inside the tubular member, which lip provides a solder meniscus. In another embodiment, the rim further includes an outer lip projecting outwardly beyond the peripheral surface of a wall of the header, both the inner and outer lips forming solder meniscuses.