Patent ID: 6408669
Filing Date: 2002-06-25
Classification: B23P,B60B,Y10T

Abstract:
A method for forming an opening in a steel flange into which is pressed a serrated shaft comprising the acts of:a) providing a blanking die having an opening on one side of the flange and a punch having a diameter smaller than the blanking die opening at the opposite side of the flange; b) forcing the punch through the flange to produce an axially extending frusto-conical opening having a minor diameter equal to the punch diameter at the opposite flange side and a major diameter equal to the blanking die opening at the one flange side; c) providing a coining punch of diameter greater than the shaft major diameter; d) forcing the coining punch into each end of the frusto-conical opening a set axial distance sufficient to extrude at least in the frusto-conical opening adjacent the minor diameter a work-hardened upset metal mass while providing countersunk openings at the axial ends of the frusto-conical opening; e) providing a cylindrical serration punch; and, f) forcing the serration punch through the frusto-conical opening from the opposite side to produce a cylindrical hole between the countersunk openings while shearing the work-hardened upset metal mass from the frusto-conical opening and forming radially outward extending serrations which extend for some axial distance in flange metal that is in a substantially non-work hardened state.