Spiral flow head assembly for polymer extrusion

Abstract

The present invention is directed to a method and apparatus for using a spiral flow assembly in a polymer extrusion process to make small diameter tubing for such items as wires, cables, and tubing. The invention comprises a mandrel inside of a housing, the mandrel having spiral grooves located on its external surface. A polymer melt is introduced into the housing through an ingress port and flows into and through the spiral grooves on the outside surface of the mandrel, in what is called “groove flow” or “channel flow.” As the polymer melt flows through the grooves or channels, the housing and mandrel begin to separate by either having the housing taper outwardly, becoming gradually larger in diameter along the axial distance of the mandrel or having the mandrel begin to taper inwardly, becoming gradually smaller in diameter along the axial distance of the mandrel. This allows the polymer, which was restricted to “channel flow,” to leak over the top of the walls that separate adjacent grooves, in what is called “leakage flow.”

Dependencies are inferred from the claim text.