Method for making a hub/pulley with a radially inward annular collar

A method of forming a hub by pressing a shaping roller against a side of a spinning annular disc of sheet metal while supporting the disc at an opposite side with a rotating head stock mandrel;

• moving the shaping roller progressively radially inwardly against the side of the rotating disc and displacing a portion of metal while thinning part of the disc and forming a sidewall and simultaneously forming a progressive axially extending annular wave of displaced metal;
• terminating radial movement of the shaping roller while pressing the annular wave against a rotating, axially extending mandrel while simultaneously forming a hub integral to the disc and with a bore configured to the mandrel wherein the improvement comprises:
• spinning an annular disc with a through bore having an inside diameter that is less than a maximum diameter of the hub bore;
• pressing the wave against a rotating, axially extending stepped mandrel with an end adjacent the rotary head stock, the end sized to press and hold an annular inward portion of the disc located between the disc inside diameter and the maximum diameter of the hub bore when forming the hub, the inward portion of the disc defining an annular collar that is integral with the disc and hub creating a blind bore of the hub.