Today in 1985, US Patent 4530631 A was issued, an invention of Elton G. Kaminski and Carl F. McEldowney, assigned to The Stolle Corporation, for their “Pull Tab For Easy Open Can End — Method Of Manufacture Thereof.” Here’s the Abstract:
An easy open can end having a retained tear strip extending diametrically partly across the can end defined by a score line, and a graspable pull tab adjacent and outside the open end of the score line. The pull tab is provided with a nose portion to initiate a tear along the score line upon lifting of the pull tab. The edges of the nose portion are curled into a cylindrical cross-sectional shape to provide a high beam strength and to rigidize the nose portion and to prevent failure by bending before the tear strip is opened. A method for manufacture of the pull tab includes forming at least one relief notch in the peripheral edge of the pull tab blank at the nose end thereof, whereby to relieve compressive forces when the edge is curled, and curling the peripheral edge of the nose portion in successive steps to form an edge portion of continuous cylindrical cross-sectional shape.