US Patent 7897074 Liquefier assembly for use in extrusion-based digital manufacturing systems

A liquefier assembly comprising a liquefier tube, where the liquefier tube comprises a sidewall having an inlet opening configured to receive a filament strand, an outlet opening, and a port disposed through the sidewall at a location between the inlet opening and the outlet opening, the port being configured to provide access for a filament drive mechanism to engage with the received filament strand. The liquefier assembly further comprises a heat transfer component configured to generate a thermal gradient along a longitudinal length of the sidewall between the port and the outlet opening.