Abstract: An apparatus for forming frangible score lines in rigid plastic sheet material. The apparatus utilizes a flat surface having a serrated edge having points and notches. The rigid plastic sheet material is laid on the flat surface. A scoring means is positioned to strike downwardly on the sheet material whereby the points of the serrated edge of the flat surface will extend into the sheet material a distance further than the notches of the serrated edge to thus form a corrugated fracturable score line in the plastic sheet material. The apparatus is useful for forming score lines in lids for drink cups intended for fast food service.

Abstract: According to this invention, there is provided a method and apparatus for making an article, such as a lid for a plastic food container made of plastic having frangible score lines. The article is formed of a sheet of plastic material having substantially constant thickness with score lines defining an offset portion thereof which is connected to the remaining sheet material by a segment that is thinner than said sheet material and being rupturable for the removal of said offset portion. The periphery of the inwardly directed portion of said offset portion overlaps the periphery of the outwardly directed portion of the offset portion on the opposite side of said sheet material. The fracturable score lines are corrugated along their length by a plurality of successive grooves and ridges with the grooves extending deeper into the material than the ridges.

Abstract: A method for making an article, such as a plastic food container lid having frangible score lines. The article is formed of a sheet of plastic material having substantially constant thickness with score lines defining an offset portion thereof which is connected to the remaining sheet material by a segment that is thinner than the sheet material and being rupturable for the removal of the offset portion. The periphery of the inwardly directed portion of the offset portion overlaps the periphery of the outwardly directed portion of the offset portion on the opposite side of the sheet material. The fracturable score lines are corrugated along their length by a plurality of successive grooves and ridges with the grooves extending deeper into the material than the ridges.

Abstract: A lid is provided for an open top container. The lid is made from a frangible material such as plastic. A tearable tab is defined by a pair of score lines each of which is on two spaced sections of the lid. The sections are located at least partially in different planes of the lid. The spacing between the sections defines a wall portion including at least another plane of the lid. This spacing is free of score lines to form a gap in each of the pair of score lines. The spaced sections of each of the pair of score lines are otherwise in alignment.