Method for producing a split louver heat exchanger fin

Abstract

A method of manufacturing serpentine fins for assembly between tubes in a heat exchanger core. The method includes providing a flat metal strip and forming in the strip, multiple rows of split louvers. Each row of split louvers has louvers formed in pairs of adjacent, spaced louver banks extending across the width of the strip. Each row includes ribs formed in the strip parallel to the louver openings and extending across the pair of louver banks. The metal strip has unformed portions extending across the strip width between rows of split louvers for forming folds across the width of the strip. After forming the rows of split louvers, pressure is applied to the strip to cause the flat strip to buckle along the unformed portions forming folds in the strip resulting in the serpentine fin. Preferably, the strip has ribs formed both in the center portion and along the edges.

Thus, having described the invention, what is claimed is: 
     
         1 . A serpentine fin for assembly between tubes in a heat exchanger core comprising a metal strip having a width between opposite strip edges and a length greater than the width and having 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 adjacent the strip edges and in a center portion of the strip between the strip edges 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, wherein the strip has folds along the unformed portions extending across the strip width such that the strip forms a serpentine shape with at least one row of split louvers between adjacent folds, the folds being adapted to contact the tubes in the heat exchanger core. 
     
     
         2 . The serpentine fin of  claim 1  wherein the ribs are elongated, plastically deformed sections and include at least one angled leg connected to an adjacent louver. 
     
     
         3 . The serpentine fin of  claim 1  wherein the louvers have ends adjacent the unformed portions of the metal strip and wherein the distance between the louver ends and the folds at the unformed portions is substantially equal. 
     
     
         4 . The serpentine fin of  claim 1  wherein the metal strip has a thickness and the ribs have a height extending from a plane of the metal strip, and wherein the ratio of the height to the thickness of the metal strip is between about 4 and 5. 
     
     
         5 . The serpentine fin of  claim 3  wherein the metal strip has a thickness and the ribs have a height extending from a plane of the metal strip, and wherein the ratio of the height to the thickness of the metal strip is between about 4 and 5. 
     
     
         6 . The serpentine fin of  claim 1  wherein the louvers are formed at an angle to a plane of the metal strip and the louver angle is between about 26 degrees and about 32 degrees. 
     
     
         7 . The serpentine fin of  claim 5  wherein the louvers are formed at an angle to a plane of the metal strip and the louver angle is between about 26 degrees and about 32 degrees. 
     
     
         8 . A serpentine fin for assembly between tubes in a heat exchanger core comprising a metal strip having a width between opposite strip edges and a length greater than the width and having 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 adjacent the strip edges and in a center portion of the strip between the strip edges and extending across the pair of louver banks, the ribs being elongated, plastically deformed sections and including at least one angled leg connected to an adjacent louver, the metal strip having unformed portions extending across the strip width between rows of strip louvers and ribs, wherein the strip has folds along the unformed portions extending across the strip width such that the strip forms a serpentine shape with at least one row of split louvers between adjacent folds, the folds being adapted to contact the tubes in the heat exchanger core. 
     
     
         9 . The serpentine fin of  claim 8  wherein the louvers have ends adjacent the unformed portions of the metal strip and wherein the distance between the louver ends and the folds at the unformed portions is substantially equal. 
     
     
         10 . The serpentine fin of  claim 9  wherein the metal strip has a thickness and the ribs have a height extending from a plane of the metal strip, and wherein the ratio of the height to the thickness of the metal strip is between about 4 and 5. 
     
     
         11 . The serpentine fin of  claim 10  wherein the louvers are formed at an angle to a plane of the metal strip and the louver angle is between about 26 degrees and about 32 degrees. 
     
     
         12 . A serpentine fin for assembly between tubes in a heat exchanger core comprising a metal strip having a width between opposite strip edges and a length greater than the width and having 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 substantially across the width of the strip, and including ribs formed in the strip substantially parallel to the louver openings between the strip edges and extending across the pair of louver banks, the metal strip having unformed portions free of louvers and ribs extending across the strip width between rows of strip louvers and ribs, wherein the strip has folds along the unformed portions extending across the strip width such that the strip forms a serpentine shape with at least one row of split louvers between adjacent folds, the folds being adapted to contact the tubes in the heat exchanger core. 
     
     
         13 . The serpentine fin of  claim 12  wherein the ribs are formed in the strip adjacent the strip edges. 
     
     
         14 . The serpentine fin of  claim 12  wherein the ribs are formed in the strip in a center portion of the strip. 
     
     
         15 . The serpentine fin of  claim 12  wherein the ribs are formed in the strip adjacent the strip edges and in a center portion of the strip. 
     
     
         16 . The serpentine fin of  claim 12  wherein the ribs are elongated, plastically deformed sections and include at least one angled leg connected to an adjacent louver. 
     
     
         17 . The serpentine fin of  claim 12  wherein the louvers have ends adjacent the unformed portions of the metal strip and wherein the distance between the louver ends and the folds at the unformed portions is substantially equal. 
     
     
         18 . The serpentine fin of  claim 12  wherein the metal strip has a thickness and the ribs have a height extending from a plane of the metal strip, and wherein the ratio of the height to the thickness of the metal strip is between about 4 and 5. 
     
     
         19 . The serpentine fin of  claim 12  wherein the louvers are formed at an angle to a plane of the metal strip and the louver angle is between about 26 degrees and about 32 degrees.