Patent ID: 6049964
Filing Date: 2000-04-18
Classification: B21D,B23P,F16D,Y10T

Abstract:
A method of processing a flat metal sheet member to form a universal joint yoke having a base for engaging with an end of a rotary shaft and fixing the end, a pair of arms having respective surfaces opposite to each other and extending in an axial direction of the base from an axial end of the base, and a pair of coaxial circular holes each formed in a tip portion of a corresponding one of said pair of arms, wherein in portions of said flat metal sheet member to be formed with said circular holes, preliminary holes having an inner diameter smaller than an inner diameter of said circular holes are formed by press punching, thereafter said flat metal sheet member is curved to form said base and said pair of arms, thereafter rough finishing is carried out by press punching the preliminary holes to form enlarged holes of nearly circular shape, and thereafter an inner peripheral edge of each nearly circular hole is shaved a small amount by press punching, thereby forming said circular holes.