Method for producing rotor laminated core

A method for producing a rotor laminated core by laminating circular core pieces, the method comprising:

• preparing a magnetic steel board from which each of the circular core pieces is blanked;
• determining a first blanking area, a second blanking area and a third blanking area in the magnetic steel board, wherein the first blanking area defines a shape of each core piece in the magnetic steel board, the second blanking area defines a shape of a magnet-insertion hole to be formed in each core piece to insert a permanent magnet therein, and the third blanking area defines a shape of an arbitrary part in the magnetic steel board;
• forming a temporary aperture in the second blanking area;
• forming a thinning part which extends at least from the temporary aperture to the third blanking area;
• and
• blanking the first blanking area, the second blanking area together with the temporary aperture and the third blanking area, thereby producing each circular core piece including the thinning part and a plurality of magnet-insertion holes which are formed in a circumferential direction.