Bemis Manufacturing Company

Steven F Schick

Daniel N Cykana

Peter F Bemis

Loren C Albrecht

A method of extruding a homogeneous plastic rod substantially free of shrink voids, the method having the steps of: extruding a rod central portion of plastic material having a glass transition point and a Vicat softening point below the glass transition point, the rod central portion having a center core and an outer skin; cooling the rod central portion while maintaining the outer skin above the Vicat softening point until the center core is cooled to approximately the Vicat softening point; using an extruder to extrude around the rod central portion a sheath of the same plastic material, the sheath having an outer skin and inner and outer portions, such that the rod central portion acts as a heat sink for the inner portion of the sheath, and such that, at the extruder, the plastic material forming the outer skin of the rod central portion is melted upon contact with the plastic material forming the sheath and the plastic material of the rod central portion and the plastic material of the sheath form the homogeneous rod, and such that the plastic material forming the center core of the rod central portion remains at a temperature below the glass transition point; and cooling the sheath while maintaining the outer skin of the sheath above said Vicat softening point until the inner portion is cooled to approximately the Vicat softening point.

Method and apparatus for extruding a rod of homogeneous plastic material

A method of manufacturing an etched extrusion, the method comprising the steps of extruding a thermoplastic material to produce a hot extrusion, and contacting the extrusion, while the extrusion is still hot, with a mixture of at least two fluids having different thermal conductivities so that the extrusion develops an uneven outer surface due to different rates of shrinkage caused by the different thermal conductivities.

Method and apparatus for manufacturing an extrusion having an uneven

Apparatus including a barrel including a generally cylindrical inner wall defining a generally cylindrical chamber having a longitudinal axis, an inlet end for receiving solid material, and an outlet end for discharging molten material, the inner wall having therein a recess extending longitudinally of the chamber, a screw which extends along the longitudinal axis and which is rotatably housed in the chamber, a drive mechanism for rotating the screw about the axis, and a conduit for introducing colorant into the chamber, the conduit having a downstream end communicating directly with the recess so that colorant flowing through the conduit flows directly into the recess.

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Sheboygan, WI, United States of America

Steven F Schick