MANUFACTURING METHOD OF IDLE GEAR FOR AUTO TENSIONER OF AUTOMOBILE TIMING CHAIN USING COLD FORGING AND IDLE GEAR FOR AUTO TENSIONER MANUFACTURED THEREBY

摘要

According to the present invention, disclosed is a method for manufacturing an idle gear of an auto tensioner of an automobile timing chain by using cold forging for producing a component, which was produced by a cutting and press process of a component produced by a forging process, in a series of multiple-stage forging processes. According to the present invention, the method for manufacturing an idle gear of an auto tensioner of an automobile timing chain by using cold forging to obtain a finished product in a cold rolling multiple-stage forging process by stages with a material cut by cutting a supplied coil comprises: a primary processed product molding step for obtaining a primary processed product by bending the edge of the cut material; a secondary processed product molding step for obtaining a secondary processed product by forming an extrusion molding part in the primary processed product obtained in the primary processed product molding step; a tertiary processed product molding step for obtaining a tertiary processed product for pre-molding a head part by hitting the extrusion molding part, which is formed in the secondary processed product molding step, by using a punch pin; a forth processed product molding step for obtaining a forth processed product by forming a circular head part by using the punch pin inside a mold by pre-molding the head part formed in the tertiary processed product molding step; and a finished product molding step for obtaining the completed form of an idle gear by molding a circular head part of the forth processed product, which is obtained in the forth processed product molding step, as the right and opposite angle head parts by using a trimming punch.