METHOD FOR FORMING TAPER HOLE IN SUSPENSION COMPONENT

摘要

[Problem] To increase the strength of the outer periphery of a taper hole (3) provided in a suspension component formed of a light alloy metal without adding a reinforcing member. [Solution] A suspension component parent material in which a taper bottom hole (3') is formed in advance is arranged on a die (10), and a punch (14) of approximately the same shape and having a slightly larger diameter is pressed into the bottom hole, thus at least partially scraping away the inner circumferential surface of the bottom hole and compressing the entire inner circumferential surface of the bottom hole. Consequently, plastic flow is induced in the material of the inner circumferential wall of the bottom hole (3'), a localized hardening process occurs, and the strength of the outer periphery of the taper hole (3), and particularly the fatigue strength, can be increased.