Patent ID: 6067712
Filing Date: 2000-05-30
Classification: B21J,F28F,Y10T

Abstract:
A method of manufacturing a heat exchange tube comprising:providing a ductile substrate having first and second services;passing said ductile substrate through a rolling mill to emboss a plurality of truncated conical protrusions on said first surface;forming the substrate into a tube so that the first surface becomes the inner surface of the tube and the second surface becomes the outer surface of the tube so that the protrusions are disposed in a plurality of longitudinal columns, such protrusions in each column having a first longitudinal pitch, the plurality of longitudinal columns comprising:a first subplurality of such columns each having such protrusions at a first set of longitudinal positions; anda second subplurality of such columns each having such protrusions at a second set of longitudinal positions, each column in the second subplurality located equidistant between two adjacent columns of the first subplurality, the second set of positions selected so that an angle .theta. between the downstream longitudinal direction and a line from each protrusion in the first subplurality and the next most downstream protrusion in an adjacent column of the second subplurality is greater than about 55 degrees and less than about 75 degrees.