Apparatus and method for thermoplastic extrusion

摘要

An electrically operated apparatus and method for altering the flow resistance experienced by a thermoplastic passing through a flow channel using one or more thermal valves having a short response time is described. The extrudate configuration of thermoplastic emerging from one or more extrusion orifices is alterable by selectively opening one or more of thermal valves that supply thermoplastic to the one or more extrusion orifices. Each thermal valve is cooled by a heat sink and has an associated heater responsive to control signals. Each heater is independently activated in synchronization with movement of the apparatus in a predetermined spatial pattern with respect to a base. By extruding thermoplastic onto a base layer-by-layer in this manner, a three-dimensional object may be formed.