Patent ID: 7117584

Claim:
A heat exchanger tube expanding apparatus for a heat exchanger having a plurality of laminated radiating fins with penetrating apertures on peripheral edge portions where fin collars are disposed upright and in which substantially U-shaped hairpin tubes are inserted through the penetrating apertures in a direction of lamination of the radiating fins, said tube expanding apparatus integrally securing the plurality of radiating fins by expanding straight portions of the hairpin tubes to place the hairpin tubes in pressure contact with the fin collars, said tube expanding apparatus comprising: a receiver platform; mandrels, each mandrel having a billet on a leading end; a reciprocating actuator for supporting rear ends of said mandrels, said reciprocating actuator being supported to reciprocate in an axial direction of straight portions of the hairpin tubes; a pressure drive source for raising and lowering said reciprocating actuator and expanding the straight portions of the hairpin tubes by pressing said billets into the straight portions of the hairpin tubes; hairpin receivers for supporting curved portions of the hairpin tubes; a fin receiver disposed at an end near the curved portions of the hairpin tubes for supporting an end portion of the plurality of laminated radiating fins; and a passive elastic body disposed between said fin receiver and said receiver platform, wherein said passive elastic body lowers said fin receiver to a predetermined position as said mandrels descend and said billets begin to be inserted into the hairpin tubes.