JPS6445264A - Composite container lid - Google Patents

Abstract

PURPOSE:To prevent the presence of a sharp cut edge on the lower end of a skirt wall of an inner lid and to avoid the generation of hermetical seal inferiority, by forming an externally wound curl to the lower end of the skirt wall of the inner lid and prescribing the inner diameter of the holding ridge of an outer lid to hold the inner lid to the required space in the outer lid by the united action of the outwardly wound curl with the holding ridge. CONSTITUTION:At the time of or after the press molding of an inner lid 6, curling processing is applied to the lower end part of the skirt wall 32 of the inner lid 6 to form an outwardly wound curl 40. The outer diameter d1 of the outwardly wound curl 40 of the inner lid 6 is larger than the inner diameter prescribed by the free end of the engaging projection 28 in an outer lid 4 and the inner diameter prescribed by the inside end of the female screw ridge 24 in the radius direction of the outer lid 4. When the inner lid 6 is combined with the outer lid 4, the engaging projection 28, the female screw ridge 24 and the holding ridge 22 in the outer lid 4 are not damaged by the smooth outer peripheral part of the outwardly wound curl 40. The rigidity of the inner lid is increased by the outwardly wound curl 40 and the generation of excessive warpage thereof is prevented. Therefore, the generation of hermetical seal inferiority is prevented.