Apparatus for assembling an electric motor employing a casing body having low dimensional accuracy

An apparatus for assembling an electric motor wherein first and second bearings, each having an outer diameter smaller than an inner diameter of a casing body such that a gap is formed between the bearings and the casing, are each mounted to each of both ends of the casing body in which a stator is inserted, with a rotary shaft around which a rotor is mounted being supported by the bearings at a center portion of the casing body, the apparatus comprising:

• a first bearing assembling machine for mounting the first bearing into a first end of the casing body in which the stator is inserted and fixed;
• and
• a second bearing assembling machine for mounting the second bearing into a second end of the casing body in which the first bearing is already mounted and in a center portion of which the rotary shaft is inserted with the rotor mounted around the rotary shaft,
• said first bearing assembling machine comprising a bearing positioning mechanism for holding the first bearing in an assembling position with the center of the first bearing placed in a specified position;
• a casing body positioning mechanism for holding the casing body, in which the stator is inserted and fixed, in an assembling position so that the center of an inner peripheral surface of the stator is aligned with the center of the first bearing, and a welding mechanism for plug welding the casing body to the first bearing in a plurality of locations on an outer peripheral surface of the casing body, and
• said second bearing assembling machine comprising a casing body positioning mechanism for holding the casing body, in which the first bearing is already mounted and the rotary shaft is already inserted, so that the center of the first bearing is placed in a specified position;
• a bearing positioning mechanism for holding the second bearing in an assembling position so that the center of the second bearing is aligned with the center of the first bearing;
• and a welding mechanism for plug welding the casing body to the second bearing at a plurality of locations on an outer peripheral surface of the casing body.