Metal forged product, upper or lower arm, preform of the arm, production method for the metal forged product, forging die, and metal forged product production system

Abstract

A method for producing a metal forged product having a plurality of branches includes a preliminary forging step of forming a preform by closed forging from a cylindrical material (301) having a surface layer (302) on a circumferential surface thereof such that the surface layer is contained in a surface region of the preform; an intermediate forging step of subjecting the preform to forging to thereby extrude the surface layer in the form of flash outside a periphery of a forged product corresponding to a target product; a final forging step of forging the forged product into a product assuming a target product shape; and a flash removal step of removing the flash containing the surface layer from the product assuming a target product shape to thereby produce a target forged product. The forged product is enhanced in mechanical characteristics and has no flash removal mark. Since the cylindrical material having a surface layer on a circumferential surface thereof is used, the power required for the steps can be reduced to enhance the yield of the products on the basis of the forging material.

Dependencies are inferred from the claim text.