Mold structure for manufacturing brush holder as part of an integrated molding process for an electric motor gear frame housing

摘要

A brush holder structure in an electric motor in which brush holders for housing brushes held in slidable contact with a commutator provided on a rotor shaft and an end bracket for rotatably supporting the rotor shaft are both integrally molded with a gear frame for housing and supporting a worm gear mechanism. In addition to the main mold for molding the gear frame, two first molds and two U-shaped second molds are abutted so as to form the brush holders when the gear frame is molded. A projection extending from each of the first molds extends between the arms of the associated U-shaped second molds to form a lead-out groove for leading out a pig tail extended from each brush. The lead-out groove is formed in a proximal end side wall of each brush holder with respect to the rotor shaft, and a receiving recess for receiving a resilient element fitted in each brush holder to press each brush against a commutator is disposed between the proximal and distal end side walls of each brush holder as a result of the separation between the projection on the first mold and the base of the associated U-shaped second mold. The receiving recess extends in the axial direction of the rotor shaft, and is set to have its width not exceeding the width of the lead-out groove in the circumferential direction of the rotor shaft. The brush holders having the receiving recess are molded by setting a paired first and second mold in butt relationship against the main mold.