Patent ID: 7413006

Claim:
A header plate for receiving the flattened tubes of a heat exchanger core, each of the flattened tubes having an exterior cross section defined by a pair of broad side walls joined by a pair of shorter nose walls, the header plate comprising: a planar base wall; and a plurality of tube receiving openings in the base wall, each of the openings surrounded by a flange extending from the base wall towards the core to surround the exterior cross section of a flattened tube received in the opening, the flange being shaped to conform to said exterior cross section and having a pair of long side walls that conform to the broad side walls of the flattened tube and a pair of short side walls that conform to the nose walls of the flattened tube, wherein a blend radius R 1 is provided at the interface between a central portion of each of the long side walls and the base wall, a blend radius R 2 is provided at the interface between each of the short side walls and the base wall, and R 2 is in the range of 1.25×R 1 to 5×R 1 .