Rotor manufacturing method

1. A rotor manufacturing method, comprising:

stacking a plurality of electromagnetic steel sheets, each of the electromagnetic steel sheets including an electromagnetic steel sheet body and an insulating film that covers the electromagnetic steel sheet body; and

welding the plurality of electromagnetic steel sheets by moving a welding head relative to the plurality of electromagnetic steel sheets that are stacked in a state in which the welding head is inclined at a predetermined angle with respect to a stacking surface of the electromagnetic steel sheets so that a molten portion is formed across the electromagnetic steel sheet body and the insulating film of an electromagnetic steel sheet of the plurality of electromagnetic steel sheets from a first surface of the electromagnetic steel sheet to a second surface of the electromagnetic steel sheet opposite the first surface of the electromagnetic steel sheet,

wherein welding the plurality of electromagnetic steel sheets includes welding the plurality of electromagnetic steel sheets in the state in which the welding head is inclined at the predetermined angle with respect to the stacking surface of the electromagnetic steel sheets so that the molten portion is formed across the electromagnetic steel sheet body and the insulating film of the electromagnetic steel sheet of the plurality of electromagnetic steel sheets from the first surface of the electromagnetic steel sheet to the second surface of the electromagnetic steel sheet opposite the first surface of the electromagnetic steel sheet,

wherein welding the plurality of electromagnetic steel sheets includes welding the plurality of electromagnetic steel sheets by moving the welding head relative to the plurality of electromagnetic steel sheets in a state in which the welding head is inclined at the predetermined angle to a side of a moving direction of the welding head, and

wherein welding the plurality of electromagnetic steel sheets includes welding the plurality of electromagnetic steel sheets by moving the welding head relative to the plurality of electromagnetic steel sheets that are stacked while gradually increasing power of a welding heat source from a start of welding in the state in which the welding head is inclined at the predetermined angle to the side of the moving direction of the welding head.

2. The rotor manufacturing method according to claim 1 , wherein

welding the plurality of electromagnetic steel sheets includes welding the plurality of electromagnetic steel sheets in the state in which the welding head is inclined at the predetermined angle with respect to the stacking surface of the electromagnetic steel sheets so that the molten portion is formed across the electromagnetic steel sheet body and the insulating film of each of the electromagnetic steel sheets.

3. The rotor manufacturing method according to claim 1 , wherein welding the plurality of electromagnetic steel sheets includes continuously performing the welding from side surfaces of the plurality of electromagnetic steel sheets that are stacked to an end surface on an outer side in a rotational axis direction in one of the electromagnetic steel sheets arranged at an end of a welding termination side via a corner of the one of the electromagnetic steel sheets arranged at the end of the welding termination side in the state in which the welding head is inclined at the predetermined angle to the side of the moving direction of the welding head.

4. The rotor manufacturing method according to claim 1 , wherein welding the plurality of electromagnetic steel sheets includes starting the welding from one end of the plurality of electromagnetic steel sheets that are stacked in a stacking direction, performing the welding up to a vicinity of a substantially central portion of the plurality of electromagnetic steel sheets that are stacked, then reversing the plurality of electromagnetic steel sheets that are stacked, starting the welding from the other end side of the plurality of reversed electromagnetic steel sheets in the stacking direction, and performing the welding up to the vicinity of the substantially central portion of the plurality of electromagnetic steel sheets that are stacked.

5. The rotor manufacturing method according to claim 1 , wherein welding the plurality of electromagnetic steel sheets includes starting the welding from a vicinity of a substantially central portion of the plurality of electromagnetic steel sheets that are stacked in a stacking direction, performing the welding up to one end side of the plurality of electromagnetic steel sheets that are stacked, then reversing the plurality of electromagnetic steel sheets that are stacked, starting the welding from the vicinity of the substantially central portion of the plurality of reversed electromagnetic steel sheets in the stacking direction, and performing the welding up to the other end side of the plurality of electromagnetic steel sheets that are stacked.

6. The rotor manufacturing method according to claim 1 , wherein the predetermined angle is equal to or larger than 30 degrees and equal to or smaller than 60 degrees.

7. The rotor manufacturing method according to claim 1 , further comprising

arranging an end plate at an end of the plurality of electromagnetic steel sheets that are stacked in the rotational axis direction, wherein

welding the plurality of electromagnetic steel sheets includes welding the end plate and one of the electromagnetic steel sheets adjacent to the end plate so that a distal end of the molten portion is located on the end plate and the molten portion is formed across the end plate and the one of the electromagnetic steel sheets adjacent to the end plate.