Method of manufacturing commutator segments with claws and tilted recesses

A method of manufacturing a commutator, comprising:

• forming a cylindrical insulator, and
• forming a plurality of commutator pieces about an outer circumferential surface of the insulator, and causing the commutator pieces to be arranged side-by-side in a circumferential direction of the insulator,
• wherein the steps of forming the cylindrical insulator and the plurality of commutator pieces, and causing the commutator pieces to be arranged side-by-side in a circumferential direction of the insulator include the steps of:
• repeatedly pressing a wedge into a substantially flat conductive plate material to form a plurality of recess portions in the conductive plate material, the plurality of recesses defining a first row of recesses aligned in an axial direction and a second row of recesses aligned in the axial direction, the first row displaced from the second row in a longitudinal direction, the first row of recesses and the second row of recesses formed in a same substantially planar surface defined by the conductive plate material,
• punching a substantially rectangular, flat blank portion from the conductive plate material such that the blank portion includes a plurality of connection claws and engagement claws, the blank portion including the plurality of recess portions,
• rolling the blank portion to form a unitary cylindrical portion,
• bending each of the plurality of connection claws such that each of the plurality of connection claws extends radially outward from the unitary cylindrical portion,
• bending each of the plurality of connection claws such that each connection claw extends outwardly in a radial direction of the unitary cylindrical portion and is configured to be electrically connected to an armature coil,
• pouring a thermosetting plastic material into the unitary cylindrical portion, using a die,
• curing the poured thermosetting plastic material by chemical reaction to form the cylindrical insulator to cause each of the engagement claws to be engaged with the cylindrical insulator, and
• forming a plurality of axial grooves in the unitary cylindrical portion, thereby separating the unitary cylindrical portion into the plurality of commutator pieces,
• wherein:
• each of the plurality of commutator pieces includes a recess portion of the plurality of recess portions, the recess portion including an undercut formed in a surface facing inwardly in the radial direction of the insulator,
• the recess portion has a first sidewall, a second sidewall and a bottom surface between the first sidewall and the second sidewall, the first sidewall and the second sidewall tilt in a first tilt direction parallel to an axial direction of the insulator, the first sidewall projects over the bottom surface to form the undercut, and the second sidewall tilts more than the first sidewall in the first tilt direction, and
• a first ridge is formed between the first sidewall and the bottom surface, a second ridge is formed between the second sidewall and the bottom surface, the bottom surface tilts in a second tilt direction opposed to the first tilt direction, and, the second ridge is positioned deeper within the recess portion as compared to the first ridge.