Patent ID: 7866042

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, while the strip is substantially flat, multiple rows of split louvers, each row of split louvers comprising louvers having openings extending in the direction of the strip length and formed in a pair of adjacent, spaced louver banks extending across at least a portion of the width of the strip, and including ribs formed in the strip substantially parallel to the louver openings and extending across the pair of louver banks, the metal strip having unformed portions extending across the strip width between rows of strip louvers and ribs for forming folds across the width of the strip; after forming the rows of split louvers, and while the strip is continually moving, applying an initial backpressure to the metal strip by contacting the strip at a first location to cause the substantially flat strip to buckle in the unformed portions and begin to form folds in the strip, with at least one row of split louvers between adjacent folds along the length of the strip; and thereafter applying further backpressure to the metal strip by contacting the strip at a second location downstream of the first location with respect to strip movement to complete formation of the folds of the strip to form the serpentine fin, the distance between the adjacent folds conforming to the desired spacing distance between the heat exchanger core tubes.