Stator of electric motor and manufacturing method for stator of electric motor

A manufacturing method for a stator of an electric motor in which a plurality of segment coils of U shapes are inserted respectively into a plurality of slots formed in the stator, wherein

• each of the segment coils includes a first bent part and a second bent part that are bent to form a U shape,
• in a front view of the U shape, press marks are formed on the first bent part and on the second bent part, the press marks being dents sinking in a front-to-rear direction, from one surface of the first bent part and another surface opposite to the one surface of the first bent part, respectively, and from one surface of the second bent part and another surface opposite to the one surface of the second bent part, respectively,
• the press marks are formed by a press mark forming device,
• the press mark forming device includes
• an upper punch that forms a press mark on one surface of the segment coil,
• a press plate that has the upper punch and gives a press force to the upper punch,
• an upper work holding plate that has an upper guide hole formed thereon to guide movement of the upper punch,
• a lower punch that forms a press mark on another surface of the segment coil,
• a receiving plate that has the lower punch and gives a press force to the lower punch,
• a lower work holding plate that has a lower guide hole formed thereon to guide movement of the lower punch, and
• a guide pin that adjusts respective angles of the first bent part and the second bent part of the segment coil, and
• the press mark forming device executes the steps of
• setting the segment coil on the lower work holding plate,
• moving the upper work holding plate toward the lower work holding plate to fix the segment coil,
• operating the guide pin to adjust respective angles of the first bent part and the second bent part of the segment coil to target angles,
• applying a load to the upper work holding plate and the lower work holding plate to form the press marks respectively on the first bent part and the second bent part of the segment coil,
• releasing the load applied to the upper work holding plate and the lower work holding plate, and
• separating the upper work holding plate from the lower work holding plate.