Patent ID: 8286331

Claim:
A method for manufacturing a laminated core, comprising: a first step of forming rotor core sheets and stator core sheets from a thin strip material, each of the stator core sheets being positioned so as to have a common axis with each of the rotor core sheets, each of the stator core sheets including a ring-shaped yoke piece and a plurality of magnetic pole pieces, the magnetic pole pieces integrally extending from a radially inside of the yoke piece, each of the magnetic pole pieces including a magnetic pole shaft piece and a magnetic pole tooth piece; and a second step of laminating the stator core sheets inside a die, wherein the first step comprises the steps of: forming first pilot holes on the thin strip material; with reference to the first pilot holes, punching out the rotor core sheets and preparatory slots which are smaller than finishing slots to form preparatory magnetic pole pieces having preparatory magnetic pole shaft pieces and preparatory magnetic pole tooth pieces; with reference to the first pilot holes, coining, thereby elongating a part of the preparatory magnetic pole shaft pieces in a radially inward direction; thereafter with reference to the first pilot holes, punching out the finishing slots over the preparatory slots to shape the magnetic pole pieces between each two of the adjacent finishing slots; forming second pilot holes at the same time with the punching out of the finishing slots; and with reference to the second pilot holes, shaping the magnetic pole tooth pieces from the preparatory magnetic tooth pole pieces.