Patent ID: 8789260

Claim:
A method for manufacturing a rotor for a generator comprising: rolling a metal plate to a circumferentially open circular cylinder comprising two free ends, the circumferentially open cylinder having an inner diameter smaller than a desired end inner diameter of the rotor; welding the two free ends of the rolled metal plate to form a closed cylinder; hot rolling the closed cylinder to a diameter that exceeds the desired end diameter; and controlled cooling of the closed cylinder responsive to a coefficient of thermal expansion of the closed cylinder to obtain the desired end diameter of the rotor, utilizing an apparatus comprising: a plurality rolls adapted for rolling a metal plate to a circumferentially open circular cylinder comprising two free ends, the circumferentially open cylinder having an inner diameter smaller than a desired end inner diameter of the rotor, and a welding device for welding the two free ends of the rolled metal plate to form a closed cylinder; a heating device for hot rolling the closed cylinder to a diameter that exceeds the desired end inner diameter of the rotor; and a cooling device for controlled cooling of the closed cylinder responsive to a coefficient of thermal expansion of the closed cylinder to obtain the desired end diameter of the rotor.