Patent ID: 7559145

Claim:
A method of forming a wheel disc comprising the steps of: forming a flat disc blank into a bowl shape wheel disc and forming a center hole; forming the bowl shaped wheel disc to form spoke forming regions adjacent window forming regions; forming a plurality of lug bolt hole regions around the center hole and flanging the center hole; forming a plurality of windows in respective window forming regions of the wheel disc, wherein each window has a respective outer edge proximate with a continuous outer band around a periphery of the wheel disc, wherein the windows define a plurality of spokes in the spoke forming regions between adjacent windows, and wherein an angular size of each of the windows along the outer band is preferably greater than an angular size of each of the spokes; coining the plurality of windows; partially closing the outer band toward a cylindrical shape by engaging a cam die against at least a portion of the outer band; fully closing the outer band substantially into a cylindrical shape by wiping the outer band using a cylindrical die and piercing bolt holes in the bolt hole regions; and calibrating a peripheral edge of the outer band by striking the peripheral edge with a ledge advancing generally parallel to a wheel disc axis and coining the bolt holes.