Patent ID: 7906067
Filing Date: 2011-03-15
Classification: B29C,B29K,B29L,B65D

Abstract:
1. A method of producing a splash-proof, thin plastic, disposable, press-on, drink-cup lid that features a pre-tensioned, one-way valve with a U-shaped, under-lapping flange, comprising the steps of: providing a plastic sheet with a material thickness in the range of 0.15-0.35 inches; creating a basic lid part by heating and sucking said sheet down into a first lid mold; removing a resultant molded sheet from said first mold; cooling said resultant molded sheet; providing a steel-ruled first die in a first base tool; positioning said molded sheet on said first base tool; stamping said molded sheet on said first die in said first base tool cutting a lid perimeter as well as a tongue-shaped valve within said lid perimeter, wherein said valve is cantilevered at a valve rear from a lid raised planar central platform out to a valve tip near to a lid rim, said valve being separated from its surround by a contoured shaped depression which is die cut along an outside valve perimeter base, said valve having substantially vertical side walls, said valve side walls being created with an L-shaped step adjacent a bottom of an exterior portion of a valve side wall; providing a second base tool having a coining second die; positioning the stamped and cut lid on said coining second die in said second base tool; creating a tongue flange by operating said second base tool to stamp said L-shaped step producing a smooth valve side wall and forcing an excess of plastic material through said die cut resulting in an under-lapping flange between said valve perimeter base and a lid body.