Extrusion apparatus

Claim 1

A screw extruder particularly adapted and suited for deposition of material on a fixed base or support, the extruder comprising in cooperative combination a barrel having a feed end and a discharge end, the barrel defining a generally cylindrical cavity, the barrel having a plurality of heating zones, each of the zones having means to inductively heat the zone and fluid heat transfer means associated therewith, an extrusion screw disposed within said cavity, means to rotate said screw at a variable rate, a pressure sensing means disposed adjacent said discharge end to sense the pressure of extruded material discharging from said cavity, a control means in operative association with said pressure sensing means and said means to rotate the screw to thereby maintain a generally constant output pressure, a forming head positioned to receive an extrude from the extruder and form the extrude to a desired configuration, the forming head having in operative combination therewith means to detect a cross-sectional deviation of the extrude in operative combination with means to propel said head and extruder, to thereby maintain a generally constant cross-section of said extrude.