Extrusion apparatus and method includes a chamber of alterable volume having an outlet and a vent in a movable wall of the chamber to facilitate sealing the chamber upon application of force to the movable wall to displace viscous, fluid composition from within the chamber through the outlet and along...http://www.google.es/patents/US5449407?utm_source=gb-gplus-sharePatente US5449407 - Expansion compensated precision extrusion apparatus
