A rotating electric machine includes a weld formed by welding end portions of a pair of electric conductors for forming a coil and a weld-insulating member that covers, at least, a surface of the weld. The weld has an uneven portion formed on at least part of the surface thereof. The uneven portion is constituted of a plurality of annular recesses and a plurality of annular protrusions. The annular recesses are formed alternately and continuously with the annular protrusions.

A winding head for a stator tooth of an electric motor is provided. A stator core has a first stator flange and a second stator flange that are joined by a stator joint part. The stator core has an I-shaped cross section perpendicular to a longitudinal elongation with a first end and a second end. The winding head is configured to extend the longitudinal elongation at the first end. The winding head has a first winding head flange and a second winding head flange that are joined by a winding head joint part, and the winding head extends at least partially an elongation of a shape of the stator core. The winding head also has a winding hole at the first winding head flange and a winding opening at the winding head joint part. The winding hole and opening are connected by a groove in the winding head joint part.

A winding head for a stator tooth of an electric motor is provided. A stator core has a first stator flange and a second stator flange that are joined by a stator joint part. The stator core has an I-shaped cross section perpendicular to a longitudinal elongation with a first end and a second end. The winding head is configured to extend the longitudinal elongation at the first end. The winding head has a first winding head flange and a second winding head flange that are joined by a winding head joint part, and the winding head extends at least partially an elongation of a shape of the stator core. The winding head also has a winding hole at the first winding head flange and a winding opening at the winding head joint part. The winding hole and opening are connected by a groove in the winding head joint part.

With this manufacturing method, a stator provided with a plurality of segment coils, both leg portions of which are inserted into each slot of a stator core and which are overlapped in the radial direction of the stator core into a plurality of layers and aligned in an annular shape, is manufactured. In this manufacturing method, a tool having teeth is moved by a robot manipulator and thereby the teeth are inserted between the terminals of the leg portions of the respective layers. When inserted, the tool is tilted in the insertion direction of the teeth and around the axis orthogonal to the radial direction and thereby the ends of the teeth are made non-contact with the insulating coatings of the terminals of the leg portions.

A coil of a stator may include a first line portion including a first axial portion and a first inclined portion. The first axial portion may be located between first and second teeth. The first inclined portion is inclined relative to the first axial portion in the circumferential direction toward the first tooth. As viewed along a radial direction, an intersection of a straight line extending along a side surface of the first tooth and a straight line extending along the first end face is defined as a first intersection and an intersection of a straight line extending along a side surface of the second tooth and the straight line extending along the first end face is defined as a second intersection, and a shortest distance between the first intersection and the first tooth is greater than a shortest distance between the second intersection and the second tooth.

A coil insertion device includes coil diameter expanders, the coil diameter expanders being configured to insert a coil assembly in a wound state into slots of a stator core by expanding the coil assembly in diameter from inside of the stator core, each of the coil diameter expanders includes: a coil presser that is arranged inside the coil assembly and presses coil end portions of the coil assembly outward from inside to expand the coil end portions in diameter; and a restrictor that is arranged outside the coil assembly, restricts outward movement of the coil end portions expanded in diameter by the coil presser, and sandwiches the coil end portions of the coil assembly inserted in the slots with the coil presser.