Method for manufacturing a rotor for a generator
View Patent ↗A method for manufacturing a rotor for a generator is provided. In accordance with this method, a metal plate is rolled to a circumferentially open circular cylinder having two free ends, the circumferentially open cylinder having an inner diameter smaller than a desired end inner diameter of the rotor. The two free ends of the rolled metal plate are then welded to form a closed cylinder. The closed cylinder is rolled to obtain the desired end diameter of the rotor.
1. 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.
2. The method according to claim 1 , wherein the closed cylinder formed by the step of welding has an inner diameter which is 99-99.95% of the desired end diameter of the rotor.
3. The method according to claim 2 , wherein the closed cylinder formed by the step of welding has an inner diameter which is 99.5-99.95%, of the desired end diameter of the rotor.
4. The method according to claim 1 , wherein rolling of the metal plate is performed as cold or hot rolling.
5. The method according to claim 1 , further comprising performing a post-processing of the welded joint to obtain a uniform outer surface, or a uniform inner surface, or both.
6. The method according to claim 5 , wherein the post processing is performed after the step of welding, or after the step of rolling of the closed cylinder, or after both steps.
7. The method according to claim 1 , further comprising performing a heat treatment after rolling of the closed cylinder.
8. The method according to claim 7 , wherein annealing or surface hardening is applied as heat treatment.
9. The method according to claim 1 , wherein a steel plate is employed as metal plate.
10. The method according to claim 1 , wherein at least one roll is adapted to roll the inside of the closed cylinder, which at least one roll is removable out of the inside of the closed cylinder after rolling has finished.