METHOD AND DEVICE FOR FORMING RACK BAR USED IN STEERING MECHANISM OF VEHICLES FROM PIPE MATERIAL BY FORGING

摘要

PURPOSE: To provide a method and device for forging a rack bar from a steel tube, wherein the method and device enhance accuracy of a product and extend the life of a tool at the same time so that manufacturing cost is reduced. CONSTITUTION: The device for forging a hollow rack member comprises a die(18) from the outer circumferential side of which a steel tube(10) is supported, and on the inner circumference of which a rack forming tooth form(28) is formed; and a core bar(40) comprising expanded head parts(40-2,40-3) that are indented in the steel tube supported by the die to form rack sawteeth on the outer surface of the steel tube by projecting the steel tube toward the tooth form, wherein the core bar comprises a forging action means constructed such that the forging action means is simultaneously projected and forged on a portion of the steel tube that is different from an axial line direction at the tooth form.