Patent ID: 7681313

Claim:
A method for forming a plate for a heat exchanger, comprising: (a) providing a flat sheet metal blank having a pair of elongate, longitudinally extending side edges and having end edges extending between the side edges, the side edges being parallel to each other such that the blank is of constant width, the blank having a central portion located between a pair of longitudinally-spaced end portions, wherein the width and length of the blank are substantially the same as a width and length of the plate; (b) forming pair of raised shoulders in the central portion of the blank, the shoulders being spaced from one another and spaced from the side edges, wherein a raised fluid flow channel is defined between the shoulders, wherein a width of the central portion after formation of the shoulders defines a maximum width of the plate, and wherein the step of forming the fluid flow channel comprises: (i) stamping a first channel portion having a proximal end portion and a distal end portion; and (ii) stamping a second channel portion having a proximal end portion and a distal end portion; wherein the proximal end portions overlap one another by a predetermined amount and the distal end portions are spaced from one another along the longitudinal axis; and (c) forming a pair of raised bosses in the blank, each of the bosses being formed in one of the end portions of the blank, each of the bosses having a pair of longitudinally-extending sides, having a longitudinal dimension which is greater than its transverse dimension, and being raised relative to the side edges and the fluid flow channel; wherein, during formation of the bosses, material from the end portions of the blank is drawn inwardly toward the bosses, thereby causing the side edges to converge inwardly toward one another along the sides of the bosses, such that a transverse distance between the side edges reaches a minimum along the sides of the bosses; wherein said minimum transverse distance between the side edges defines a minimum width of the plate; and wherein the shoulders and the bosses are sufficiently spaced from the side edges of the plate such that a continuous flange is formed along an entire periphery of the plate.