Patent ID: 8176619

Claim:
A method of manufacturing a molded commutator for a vacuum cleaner motor, the molded commutator having a plurality of commutator segments arranged in a circle, and grooves respectively formed between adjacent pairs of said commutator segments in a rotating direction, such that the grooves are extended orthogonal to the rotating direction; a plurality of cylindrical varistors respectively fitted in said grooves formed between the adjacent commutator segments; and a molding material molding the commutator segments and the cylindrical varistors together to maintain integral engagement of the commutator segments and the cylindrical varistors; wherein the commutator segments are made of copper alloy containing silver, wherein the cylindrical varistors are formed of zinc oxide compounds and have a density ranging from 5 g/cm 3 to 5.5 g/cm 3 ; wherein at least side surfaces of said cylindrical varistors make contact with the respective adjacent pairs of commutator segments; and wherein flexible metal is printed on said side surfaces of said cylindrical varistors that make contact with the respective adjacent pairs of commutator segments, the method comprising: providing a cylindrical molding ring; arranging a plurality of the commutator segments in a circle along an inner periphery of the cylindrical molding ring; press-fitting the cylindrical varistors between the commutator segments arranged in the circle along the inner periphery of the cylindrical molding ring, with a press-fitting load for each of the cylindrical varistors ranging from 2 kN to 5 kN inclusive; and resin-molding the commutator segments and the cylindrical varistors together with a molding material so as to maintain integral engagement of the commutator segments and the cylindrical varistors.