Patent ID: 8191258

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 extending in the first longitudinal direction; transporting the second sheet of material along a second path extending in the second longitudinal direction; shaping a longitudinal edge of the first sheet of material while transporting the first sheet of material, the first sheet of material having a cross-sectional shape lying substantially in a first plane; 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, each of the plurality of longitudinally-extending peaks and valleys extending in the first longitudinal direction and the insert having a cross-sectional shape lying substantially in a second plane; inserting a longitudinal edge of the insert that extends in the first longitudinal direction into the shaped longitudinal edge of the first sheet of material at a point along a longitudinal axis of the insert; rotating the insert about the longitudinal axis of the insert that extends in the second longitudinal direction from a position in which the first plane is at an acute angle with respect to the second plane to a position in which the first and second planes are substantially parallel while transporting the insert and the first sheet of material; after inserting the longitudinal edge of the insert into the shaped longitudinal edge of the first sheet of material at the point along the longitudinal axis of the insert, continuing to insert the insert into the first sheet of material while rotating the insert about the longitudinal axis of the insert at the point along the longitudinal axis of the insert; and enclosing the insert within walls of the tube defined at least in part by the first sheet of material.