Mandrel structure for use in manufacture of cellulose food casing

Abstract From the Canadian patent

The tubular extrusion of a thermoplastic nonderivatized cellulose solution about a mandrel and through a long air gap in excess of 304 mm is facilitated by use of a mandrel which is extensible from the extrusion die. On extrusion start-up, the mandrel extends a short length from the die. For steady-state operation, the mandrel is extended its full length from the die. Also disclosed is a mandrel structure to facilitate the introduction of a nonsolvent liquid into the interior of the extruded tube at a high location on start-up extrusion and at a lower location during steady-state operation. The mandrel also includes a sizing portion having circumferential grooves which gather gas bubbles …