Abstract: A crosshead assembly for forming extruded shapes from molten polymer. The assembly includes body sections, a mandrel, a choke ring, and a tip holder for admitting, turning, and accelerating molten polymer toward a novel rotatable die sub-assembly. The die sub-assembly includes a hub, axially-loaded duplex ball bearings, and a pulley for rotating the sub-assembly. The choke ring extends into the die sub-assembly, and a cylindrical seal element is disposed therebetween. A changeable extrusion tip is threaded onto the second cylindrical portion of the tip holder. A die in the sub-assembly is specific to the shape to be extruded. For forming a spiral ribbon and a skin layer on core material, the die opening is a circular central aperture and a radial slot. Multiple ribbons may be extruded simultaneously by using multiple slots.

Abstract: A polymer extrusion crosshead assembly for forming a spirally-striped extrusion. The assembly includes conventional components for admitting, turning, and accelerating primary molten polymer toward a novel rotating die sub-assembly. A body element includes an axial counterbore for receiving a manifold supply block in communication with a source of secondary striping polymer. A wear plate is attached to the manifold block. The die sub-assembly includes a striping die having an annular passage for conveying the primary polymer to form an extruded tube or a core material coating. The die is loaded against the wear plate by a Belleville washer. The die includes one or more striping nozzles in communication with the manifold block for injecting secondary striping polymer into the annular stream of primary polymer flowing through the die, creating a longitudinal stripe of striping polymer. Rotating the die while extruding both polymers yields a helically striped (spiral) extrusion.

Abstract: An apparatus for conveying powder. The apparatus includes a hopper for receiving powder, a mechanical conveyor, a sifter and a ribbon blender. The mechanical conveyor delivers powder from the hopper to the sifter. The ribbon blender, which is situated below the sifter for receiving powder from the sifter, has two or more outlets for discharging powder.