Multiple-zone liquefier assembly for extrusion-based additive manufacturing systems

Abstract

A liquefier assembly for use in an extrusion-based additive manufacturing system, and a method for building a three-dimensional model with the extrusion-based additive manufacturing system, where the liquefier assembly includes a liquefier tube having multiple, independently heatable zones along a longitudinal length of the liquefier tube.

1 . A liquefier assembly for use in an extrusion-based additive manufacturing system, the liquefier assembly comprising:
 a liquefier tube having a first end and a second end offset along longitudinal length;   an extrusion tip secured to the first end of the liquefier tube;   a first thermal unit operably secured to the liquefier tube adjacent the first end of the liquefier tube; and   a second thermal unit operably secured to the liquefier tube between the first thermal unit and the second end of the liquefier tube, wherein the first thermal unit and the second thermal unit are configured to be operated independently of each other.   
     
     
         2 . The liquefier assembly of  claim 1 , wherein the first thermal unit comprises:
 a first thermally-conductive component in thermal contact with an outer surface of the liquefier tube; and   a first electrically-conductive component configured to heat the first thermally-conductive component;   
     
     
         3 . The liquefier assembly of  claim 2 , wherein the first thermal unit further comprises a first temperature sensor configured to detect a temperature of at least one of the first thermally-conductive component, the liquefier tube at a location adjacent to the first thermally-conductive component, and a combination thereof. 
     
     
         4 . The liquefier assembly of  claim 2 , wherein the second thermal unit comprises:
 a second thermally-conductive component in thermal contact with the outer surface of the liquefier tube; and   a second electrically-conductive component configured to heat the second thermally-conductive component.   
     
     
         5 . The liquefier assembly of  claim 4 , wherein the second thermal unit further comprises a second temperature sensor configured to detect a temperature of at least one of the second thermally-conductive component, the liquefier tube at a location adjacent to the second thermally-conductive component, and a combination thereof. 
     
     
         6 . The liquefier assembly of  claim 1 , and further comprising a drive mechanism configured to feed successive portions of a filament to the second end of the liquefier tube. 
     
     
         7 . The liquefier assembly of  claim 1 , and further comprising at least one electrically-insulative sleeve. 
     
     
         8 . The liquefier assembly of  claim 1 , and further comprising a third thermal unit operably secured to the liquefier tube between the second thermal unit and the second end of the liquefier tube. 
     
     
         9 . A liquefier assembly for use in an extrusion-based additive manufacturing system, the liquefier assembly comprising:
 a liquefier tube having a first end and a second end offset along longitudinal length;   an extrusion tip secured to the first end of the liquefier tube; and   a plurality of thermal units operably secured to the liquefier tube at different locations along the longitudinal length of the liquefier tube, wherein each of the plurality of thermal units is configured to be operated independently of each other.   
     
     
         10 . The liquefier assembly of  claim 9 , wherein each of the plurality of thermal units comprises:
 a thermally-conductive component in thermal contact with an outer surface of the liquefier tube;   an electrically-conductive component configured to heat the thermally-conductive component; and   a temperature sensor configured to detect a temperature of at least one of the thermally-conductive component, the liquefier tube at a location adjacent to the thermally-conductive component, and a combination thereof.   
     
     
         11 . The liquefier assembly of  claim 10 , wherein the electrically-conductive component comprises a wire wrapped around at least a portion of the thermally-conductive component. 
     
     
         12 . The liquefier assembly of  claim 9 , and further comprising at least one electrically-insulative sleeve. 
     
     
         13 . The liquefier assembly of  claim 9 , wherein the plurality of thermal units range from two thermal units to ten thermal units. 
     
     
         14 . The liquefier assembly of  claim 13 , wherein the plurality of thermal units range from two thermal units to five thermal units. 
     
     
         15 . A method for building a three-dimensional model with an extrusion-based additive manufacturing system having an extrusion head, the method comprising:
 providing a liquefier tube of the extrusion head having multiple heatable zones along a longitudinal length of the liquefier tube;   heating a first zone of the multiple heatable zones;   at least partially melting a portion of a filament of a thermoplastic material within the first zone of the liquefier tube; and   extruding the molten thermoplastic material from an extrusion tip mounted to a bottom end of the liquefier tube.   
     
     
         16 . The method of  claim 15 , and further comprising, while only the first zone is heated, moving the extrusion head along a toolpath that defines an outer perimeter surface of the three-dimensional model. 
     
     
         17 . The method of  claim 15 , and further comprising heating a second zone of the multiple heatable zones, the second zone being located between the first zone and a top end of the liquefier assembly. 
     
     
         18 . The method of  claim 17 , and further comprising moving the extrusion head along a toolpath that defines an inner region of the three-dimensional model. 
     
     
         19 . The method of  claim 17 , and further comprising stopping the heating of the second zone while maintaining the heating of the first zone. 
     
     
         20 . The method of  claim 15 , wherein heating the first zone of the multiple heatable zones comprises applying an electrical current through a conducive wire in contact with a thermally-conductive component in thermal contact with the liquefier tube at the first zone.