Device and method for opening folded heat exchanger cores

A device is configured for opening a heat exchanger core from a U-shape to a V-shape. Such heat exchanger core has a plurality of parallel flat tubes, each having two ends; and two manifolds. Each of the flat tubes has two straight sections adjacent to the manifolds and an intermediate bent section. The device has two hinged frames, a respective clamp arrangement on each of the hinged frames for holding the two manifolds, and a trough shaped support for the intermediate portion. For opening the U-shaped heat exchanger core, the heat exchanger core is inserted into the device, and the two manifolds are secured with the clamp arrangements. The clamp arrangements are separated from one another by pivoting apart the two hinged frames, on which the clamps are mounted. Simultaneously, the intermediate bent section is pushed toward the trough adapted to provide a desired curvature to the intermediate section.