Rotor manufacturing apparatus and rotor manufacturing method

A rotor manufacturing method for manufacturing a rotor including a tubular rotor core having a slot extending therethrough in an axial direction, a magnet accommodated in the slot, and a plastic filling the slot to fix the magnet to the rotor core, the rotor manufacturing method comprising:

• clamping a first die and a second die with the rotor core and a caul plate sandwiched therebetween in the axial direction in a state in which the caul plate is disposed at an end face in the axial direction of the rotor core accommodating the magnet, the caul plate including a filling pot configured to introduce the plastic into the slot;
• and
• filling the slot with the plastic by extruding the plastic in the filling pot by using a plunger disposed in a receiving hole formed in the first die, the plunger being configured to protrude from and retract into a facing surface of the first die facing the caul plate, wherein
• the plunger includes:
• an enlarged-dimension portion;
• and
• a reduced-dimension portion protruding from the enlarged-dimension portion to form a distal end of the plunger, the reduced-dimension portion having a width smaller than that of the enlarged-dimension portion, and
• the filling the slot with the plastic includes moving the plunger at least to a position at which the enlarged-dimension portion is flush with the facing surface.