Reverse parison draping for blow molding

Abstract From the Canadian patent

A double-walled plastic box (20) is molded from a single parison (50) in an unlimited depth by closing and holding a bottom region of the parison at the bottom of a cavity (30) bringing together parts of a core (40) above the cavity to close off an upper region of the parison moving, the core, the cavity, or both vertically to position the core within the cavity and invert the parison so that a lower region of the parison forms an outside wall of the box against an inside surface of the cavity and an upper region of the parison forms an inside wall of the box against an outer surface of the core. The parison is then blown into a double-walled box (20) in the shape of an enclosed space …