Method for blow molding foamed walled plastic open mouthed containers
AssigneeCosden Oil & Chemical Company
InventorGranville J. Hahn
Life of this patent
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Abstract
The method for blow molding foam walled plastic using a quadrisectional mold. A parison of foamed plastic may be blow molded to assume the contour of the closed mold, after which the molded shape is severed into two portions and ejected. Desirably, cellular plastic is blow molded to form hot drink cups.
Claims4
A method for blow molding foamed walled plastic open-mouthed containers which comprises extruding foamed plastic through an annular orifice to form a foamed parison of tubular configuration, having foamed walls pinching a lower section of the tubular configuration within a lower portion of a sectional mold, pinching an upper portion of the tubular configuration within an upper portion of a sectional mold, introducing a gas through a hollow needle inserted at a point through a center portion of said mold and parison therein and blowing the tubular configuration with a gas introduced through said needle at said point to form a hollow foam-walled body assuming the contour of the closed mold and severing the molded hollow article in a single thin cut with a hot severing means passed through the center thereof, including the aperture formed in blowing, into two foamed wall container portions, said severing means melting said plastic as it passes thereby severing said container into clean smooth cut halves and substantially removing the aperture formed by said needle without substantial removal or production of plastic inter-connecting substances as scrap material.
The method of molding foam-walled cups comprising heating and softening thermoplastic particles to extrudable fluidity, introducing a foaming agent under pressure into the softened mass and extruding a parison of said softened plastic through an orifice to form a parison in the shape of a tubular body having foamed walls, periodically introducing lengths of said tubular body into an open multi-sectional mold, said mold severing and enclosing a molding length of said extruded tube corresponding to a pair of cups between opposite mold ends upon closure, said mold having its inner mold surfaces shaped as a pair of cups assembled mouth to mouth, inserting a hollow needle connected to a blowing gas supply through an aperture passing radially through the center of the mold wall a sufficient distance to penetrate the wall of said tube, introducing a blowing gas into said tube through said needle to expand its walls to a molded body corresponding to the shape of said mold as a pair of hollow cups in mouth to mouth assembly in said mold, separating said molds and severing the mouth portions of said molded cup bodies in a single hot wire cut from each other into a pair of cups, said hot wire severing means being thin and adapted to pass as a single cut through the walls of the plastic molding, melting said plastic as it passes to leave a simulated `fire polished` container lip at the severed wall portion, said cut being passed centrally of said molding to intercept and obliterate by melting the needle hole remaining in the cup wall following the formation of the molding.
Dependencies are inferred from the claim text.