Method for manufacturing arm of joint and joint

Abstract

A first-stage intermediate formed body (60) is forged by applying pressure in one direction to a working material (41) made of an aluminum alloy. The first-stage intermediate formed body (60) has a tubular arm portion (21), a generally spherical first head portion (62) provided at one end of the arm portion (21), and a ledge portion (63) at the other end of the arm portion (21). A second-stage intermediate formed body (67) is formed by deforming the ledge portion (63) by upsetting. The arm portion (21) of the second-stage intermediate formed body (67) has a second head portion (66) and an axial hole (21a). The second head portion (66) has a rounded shape and is located at the aforementioned other end of the arm portion (21). The axial hole (21a) is formed in the arm portion (21). Pressure is then applied to the first head portion (62) and the second head portion (66) in such a direction as to intersect the axis of the arm portion (21), thereby forming a cylindrical body portion (23) and an outer tube portion (22). Thus, a suspension arm (2) is formed. The invention enables the improvement of the manufacturability and facilitates strengthening of the suspension arm through reduction of the number of parts.

Dependencies are inferred from the claim text.