Patent ID: 8839846

Claim:
A method for producing a flat-round tube-to-header joint in a CuZnFe alloy heat exchanger, said flat-round tube-to-header joint disposed between a tube and a header having a generally circular opening having a first predetermined diameter formed on a first side thereof for receiving one end of said tube, said header having a second side located at an opposite side from said first side, said method comprising: a) providing at least one generally circular end having a second predetermined diameter on said tube to fit into said generally circular opening of said header; b) providing a predetermined temper on said at least one generally circular end which is at least sufficient to enable cold working of said at least one generally circular end to prevent premature failures of said flat-round tube-to-header joint; c) inserting said one end of said tube into said first side of said header until it extends at least through a thickness of said header member; d) removing any excess portion of said tube which extends above said second side of said header member so that said generally circular end of said tube is approximately flush with said second side of said header; and e) mechanically rolling said one end of said tube to form said flat-round tube-to-header joint between said one end of said tube and said header, wherein said header has a thickness that is capable of supporting the mechanical joint between the header and the circular end of the tube so as to reduce deformation of the header during use.