RACK SHAFT STOCK FORGING DEVICE, MANUFACTURING METHOD USING THE FORGING DEVICE, AND RACK SHAFT STOCK

摘要

PROBLEM TO BE SOLVED: To provide a rack shaft stock forging device capable of forming rack teeth of high shape accuracy even when the rack teeth are formed by forging, a manufacturing method using the forging device, and a rack shaft stock.SOLUTION: The forging device 20 is a forging device for a rack shaft stock 11 having first die 21a and a second die 21b constituting a half-sealed forging die. The rack shaft stock 11 includes a rack tooth forming part 13 and burrs 15. The first die has a first groove part 21a2 and a first edge surface 21a1. The second die is provided to face the first die, and includes a second groove part 21b2 and a second edge surface 21b1. The burrs 15 are bulged between the first edge surface 21a1 and the second edge surface 21b1 to be formed by the forging of a raw material before the formation of rack teeth 16 by using the first die and the second die. A space distance between the first edge surface 21a1 and the second edge surface 21b1 during the formation of the burrs 15 is smaller at the first end 13a of the rack tooth forming part 13 than at the center of the rack tooth forming part 13.SELECTED DRAWING: Figure 2