Patent ID: 6705753
Filing Date: 2004-03-16
Classification: B29B,B29C

Abstract:
An extruder comprisingat least one extruder screw shank which can be rotated by a motor, said screw shank having a part provided with flights, said part having a diameter, said screw shank further having at least one circumferential bulge section with a diameter which is larger than the diameter of the part provided with flights, an extruder barrel through which said at least one screw shank extends to form an extrusion space between said screw shank and said extruder barrel, said extruder barrel having at least one barrel section which surrounds in an essentially equidistant manner the respective at least one screw shank in the area of the respective at least one circumferential bulge section to form an encircling gap as a restricted flow zone, and a hydraulic pressure chamber formed in at least one of said screw shank and said barrel in the area of said restricted flow zone, said at least one of said screw shank and said barrel being formed with a membrane wall between said pressure chamber and said restricted flow zone, said membrane wall being deformable in a selective manner to adjust the size of the gap by adjusting the pressure in said pressure chamber.