Torsion bar by seat belt retractor torsion bar manufacture method and such method

摘要

PURPOSE: A method for manufacturing a torsion bar very efficiently is provided, wherein the torsion bar is installed inside belt coiling reel to absorb impact, and a torsion bar manufactured by the method is provided. CONSTITUTION: The manufacturing method of torsion bar for seat belt retractor comprises a process of supplying a rod shaped workpiece having long length due to forging performed using header machine to cut the workpiece to a certain length considering heads to be formed at both sides of the workpiece and form a circular head(2) at one side of the workpiece at the same time; a process of forming a circular head(2a) by forging an other side of the intermediate workpiece at one side of which the circular head(2) is formed by supplying each intermediate workpiece(1b) to the header machine; and a process of forming hexagonal heads(3,3a) by fixing the intermediate workpiece that is an object to be processed to a press and operating cutting tools(20,20a) on which blades(21,21a) having a desired shape, i.e., hexagonal shape are formed using the press, thereby strongly pushing the cutting tools(20,20a) to the circular heads(2,2a) so that unnecessary parts are removed as a process of forming the circular heads(2,2a) at both sides of the intermediate workpiece into hexagonal heads(3,3a) again.