A method for manufacturing a rotor, wherein a rotor is manufactured by injecting thermoplastic into each of magnet housing holes in a core with a magnet accommodated in each magnet housing hole, thereby fixing the magnets, the method comprising:
- preparing the core and the magnets, the core including the magnet housing holes, wherein
- each of the magnet housing holes extends through the core in an axial direction of the core and includes an elongated hole portion that extends in a direction intersecting a radial direction of the core, and
- the elongated hole portion and the magnet are configured such that a difference between a dimension in a width direction, which is a direction orthogonal to a lengthwise direction of the elongated hole portion, and a dimension, in the width direction of the magnet when accommodated in the elongated hole portion, is greater than 0 and less than or equal to 0.45 mm;
- accommodating the magnets in the elongated hole portions of the magnet housing holes;
- clamping the core between a first die and a second die in a state in which the magnets are accommodated in the elongated hole portions of the magnet housing holes;
- and
- injecting the thermoplastic into the magnet housing holes of the core clamped between the first die and the second die, wherein
- each elongated hole portion includes two inner surfaces on opposite sides in the width direction, one of the inner surfaces closer to a peripheral edge of the core being defined as a first inner surface, and the other inner surface, farther from the peripheral edge of the core, being defined as a second inner surface,
- the magnet accommodated in each elongated hole portion includes two side surfaces on opposite sides in the width direction, one of the side surfaces closer to the peripheral edge of the core being defined as a first side surface, and the other side surface, farther from the peripheral edge of the core, being defined as a second side surface,
- the accommodating the magnets in the elongated hole portions of the magnet housing holes includes accommodating the magnets in the elongated hole portions of the magnet housing holes such that, in each of the elongated hole portion, a gap is formed
- between the first inner surface of the elongated hole portion and the first side surface of the magnet accommodated in the elongated hole portion, or
- between the second inner surface of the elongated hole portion and the second side surface of the magnet accommodated in the elongated hole portion, or
- both between the first inner surface of the elongated hole portion and the first side surface of the magnet accommodated in the elongated hole portion and between the second inner surface of the elongated hole portion and the second side surface of the magnet accommodated in the elongated hole portion,
- the gap includes an upper end portion and a portion other than the upper end portion, and
- the injecting the thermoplastic into the magnet housing holes of the core clamped between the first die and the second die includes injecting the thermoplastic into the magnet housing holes so that the thermoplastic is not filled in the portion of the gap other than the upper end portion.