US Patent 7837391 Bearing retainer unit and electric motor furnished therewith

A bearing retainer unit is formed by an insert-molding technique to cast a molded component of the bearing retainer unit utilizing a bearing bushing. A first mold die, having a circumferential surface shaped to correspond to at least a portion of the inner circumferential surface of a bearing-positioning portion of the molded component, and a second mold die, having an abutment that abuts against an axial end face of the first die, are readied. A molten material is then injected into the mold to form the molded part, thereby forming the die-parting line on the inner circumferential surface of the component's bearing positioning portion, positioned at the radially outer side of the abutment.