Patent ID: 7921559

Claim:
A method of forming a heat exchanger tube, the method comprising: providing a first sheet of material extending along a first longitudinal direction; providing a second sheet of material extending along a second longitudinal direction; transporting the first sheet of material along a first path; transporting the second sheet of material along a second path; shaping a longitudinal edge of the first sheet of material while transporting the first sheet of material; shaping a plurality of longitudinally-extending peaks and valleys into the second sheet of material while transporting the second sheet of material to produce an insert for the heat exchanger tube; inserting a longitudinal edge of the insert into the shaped longitudinal edge of the first sheet of material; bowing the insert; after inserting the longitudinal edge of the insert into the shaped longitudinal edge of the first sheet of material, continuing to insert the insert into the first sheet of material while bowing the insert; and enclosing the insert within walls of the tube defined at least in part by the first sheet of material.