METHOD AND APPARATUS FOR GAUGING BIAXIALLY ORIENTED THERMOPLASTIC BODIES

摘要

A process and an apparatus for blow molding completely finished hollow plastic containers of biaxially oriented material and having a finished neck. A dual-diameter blow pin is positioned between separable mold sections and is movable along its longitudinal axis. A crammer sleeve is reciprocably disposed about the blow pin, and gripping jaws are positioned to close around the blow pin. One end of a heated tubular parison is positioned over a larger-diameter portion of the blow pin, and the parison is longitudinally stretched, axially orienting the material and causing the parison to neck down onto a smaller-diameter portion of the blow pin. The mold sections are closed over the stretched parison, the blow pin is longitudinally inserted to size the inside diameter of the neck opening, the crammer sleeve is inserted to cram axially-oriented material into the neck finishing cavity of the mold and to finish form the neck opening, and the tail surplus material is severed. Upon separation of the mold sections, the crammer sleeve and blow pin are retracted, with the withdrawal of the crammer sleeve removing the severed neck surplus material. The neck forming portions of the mold sections are designed for easy insertion of the blow pin and the provision of a controlled volume of oriented material for the crammer sleeve.