Mfg. plastic bags with opening in one face - by punch cutting flat film passing cantilevered support

摘要

Plastic bags with an opening in one face are made by leading flattened folded or tubular thermoplastic film over a rigid cantilevered platform inserted via an open border to act as a back plate for a circular press cutter applied periodically to one face of the film as the film is stepped past the platform. Successive cut portions of the film are subsequently isolated by a combination of longitudinal and transverse welds. Used esp. for making bags in which continuous flexible profiles such as electric cable or small hose can be contained as a coil retained by the sealed borders of the bag and inserted or withdrawn progressively through the opening in the bag face.