Patent ID: 9065318
Filing Date: 2015-06-23
Classification: H02K,Y10T

Abstract:
1. A method of manufacturing a rotor core, the rotor core formed by laminating a plurality of core sheets each punched out from a magnetic thin metal strip, each of the core sheets including a shaft hole in a center, the shaft hole including keys protruding radially inward of the core sheet, the method comprising: a first process of punching out punched holes in the thin metal strip by a first punch and a first die paired with the first punch, the punched holes forming outlines of the keys, the punched holes including inside areas located inside the shaft hole and outside areas continuous with the inside areas and located outside the shaft hole; a second process of punching out the shaft hole by a second punch and a second die paired with the second punch, the shaft hole continuous with the punched holes, the shaft hole including recesses to avoid the keys; and a third process of punching out outlines of the core sheets each provided with the shaft hole and laminating the core sheets.