Patent ID: 8732952

Claim:
A method of manufacturing serpentine fins for assembly between tubes in a heat exchanger core comprising: providing a flat metal strip for making heat exchanger fins, the strip having a width between opposite strip edges and a length greater than the width; forming in the strip multiple rows of split louvers each having openings extending in the direction of the strip length and formed in adjacent, spaced louver banks extending at least a portion across of the width of the strip, the metal strip having unformed portions extending across the strip width between rows of strip louvers; applying pressure to the metal strip so that the unformed strip portions buckle and provide folds in the strip to form the serpentine fin having at least one row of split louvers residing between adjacent folds; folding at least one of the strip edges to form a hemmed edge comprising a double thickness of the metal strip, the hemmed edge extending a portion of the distance inward from said at least one edge; and forming at the hemmed edge an end rib having an angled leg and a bent portion whereby the hemmed edge extends from said at least one edge along the angled leg and at least partially follows along the contour of the end rib bent portion.