Patent ID: 8151617

Claim:
A method of forming apparatus for use as a turbulizer or fin for a heat exchanger, the apparatus including a member having a longitudinal axis, a lateral width and a plurality of strips including one or more first strips and one or more second strips, each strip extending widthwise of the apparatus and being corrugated longitudinally so as to form a plurality of sections laterally spaced-apart from one another and connected to one another by bridges projecting from the sections in a common direction, wherein the bridges of the first strips and the second strips extend in the same direction and the corrugations of the one or more second strips are offset laterally from the corrugations of the one or more first strips, the method comprising: crimping longitudinally-corrugated strip material between first and second forming dies to form said apparatus, said dies being adapted such that substantially all lateral movement of strip material in the crimping step occurs as a result of strip material being drawn laterally by material that has been displaced in a direction parallel to the direction of relative die movement.