MIDDLE MANUFACTURING THINGS FOR PINION SHAFT

摘要

An intermediate molded article manufacturing method for machining a pinion shaft of a steering unit is provided to reduce an abrasion rate of a mold, and to extend mold life remarkably by reducing load applied to the mold due to a preliminary groove formed in an upper surface of material. An intermediate molded article manufacturing method for machining a pinion shaft of a steering unit comprises the steps of: forming round in a corner portion of a lower end of cut material; forming the round in a corner portion of an upper end of material; molding a tip part(4) and a helical gear molding part(3) as well as a third step difference part(7) and a second step difference part(6) by pressurizing with a former mold; forming an intermediate body(2) in an upper part of the helical gear molding part by pressurizing with the former mold; and molding a head part(1) and a first step difference part(5) by pressurizing with the mold as well as forming a coupling groove(8) and an oil groove in an upper surface of the head part, and forming an upper chuck inserting groove(10) in the middle of a bottom surface of the coupling groove of the head part as well as a lower chuck inserting groove in the middle of a lower surface of the tip part.