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

1. An extrusion-based additive manufacturing system comprising:

a filament drive mechanism configured to feed a filament of a consumable material;

a liquefier having an inlet end and an outlet end offset along a longitudinal length;

an extrusion tip secured to the outlet end of the liquefier;

a first thermal unit operably secured to the liquefier;

a second thermal unit operably secured to the liquefier;

a third thermal unit operably secured to the liquefier such that the first thermal unit, the second thermal unit, and the third thermal unit are positioned along the longitudinal length of the liquefier between the inlet end and the outlet end of the liquefier;

at least one electrically-insulative sleeve extending at least partially around all of the first thermal unit, the second thermal unit, and the third thermal unit; and

a controller configured to operate the filament drive mechanism to feed the filament to the inlet end of the liquefier, and to independently operate each of the first thermal unit, the second thermal unit, and the third thermal unit to produce independently heatable zones along the longitudinal length of the liquefier for melting the consumable material of the fed filament in the liquefier.

2. The system of claim 1 , wherein the first thermal unit comprises:

a first thermally-conductive component in thermal contact with an outer surface of the liquefier; and

a first electrically-conductive component configured to heat the first thermally-conductive component.

3. The system of claim 2 , wherein the first thermal unit further comprises a first temperature sensor configured to detect an electrical resistance of the first thermally-conductive component, and to relay the detected electrical resistance to the controller.

4. The system of claim 2 , wherein the second thermal unit comprises:

a second thermally-conductive component in thermal contact with the outer surface of the liquefier; and

a second electrically-conductive component configured to heat the second thermally-conductive component.

5. The system of claim 4 , wherein the second thermal unit further comprises a second temperature sensor configured to detect an electrical resistance of the second thermally-conductive component, and to relay the detected electrical resistance to the controller.

6. The system of claim 1 , wherein the controller is configured to independently operate each of the first thermal unit, the second thermal unit, and the third thermal unit in a manner that comprises shutting down the first thermal unit, the second thermal unit, and the third thermal unit in a downward serial manner.

7. The system of claim 1 , wherein the at least one electrically-insulative sleeve comprises a ceramic material.

8. The system of claim 1 , wherein the controller is configured to independently operate each of the first thermal unit, the second thermal unit, and the third thermal unit in a manner that comprises directing how many of the independently heatable zones are to be operated based on a toolpath to be followed.

9. An extrusion-based additive manufacturing system comprising:

a filament drive mechanism configured to feed a filament of a consumable material;

a liquefier having an inlet end and an outlet end offset along a longitudinal length;

an extrusion tip secured to the outlet end of the liquefier;

three or more thermal units operably secured to the liquefier at different locations along the longitudinal length of the liquefier between the inlet end and the outlet end of the liquefier; and a controller configured to operate the filament drive mechanism to feed the filament to the inlet end of the liquefier, and to independently operate each of the three or more thermal units to produce independently heatable zones along the longitudinal length of the liquefier for melting the consumable material of the fed filament in the liquefier; and

at least one electrically-insulative sleeve extending at least partially around all of the three or more thermal units.

10. The system of claim 9 , wherein each of the three or more thermal units comprises:

a thermally-conductive component in thermal contact with an outer surface of the liquefier;

an electrically-conductive component configured to heat the thermally-conductive component; and

a temperature sensor configured to detect an electrical resistance of the thermally-conductive component, and to relay the detected electrical resistance to the controller.

11. The system of claim 10 , wherein the electrically-conductive component comprises a wire wrapped around at least a portion of the thermally-conductive component.

12. The system of claim 9 , wherein the at least one electrically-insulative sleeve comprises a ceramic material.

13. The system of claim 9 , wherein the liquefier includes a length portion along the longitudinal length between the inlet end of the liquefier and a top-most thermal unit of the three or more thermal units.

14. The system of claim 9 , wherein the controller is configured to independently operate each of the three or more thermal units in a manner that comprises shutting down the three or more thermal units in a downward serial manner.

15. An extrusion-based additive manufacturing system comprising:

a filament drive mechanism configured to feed a filament of a consumable material;

a liquefier having an outer surface, an inlet end, and an outlet end offset along a longitudinal length from the inlet end;

an extrusion tip secured to the outlet end of the liquefier;

three or more thermal units positioned along the longitudinal length of the liquefier between the inlet end and the outlet end of the liquefier, wherein each of the three or more thermal units comprises:

a thermally-conductive component in thermal contact with an outer surface of the liquefier;

an electrically-conductive component configured to electrically heat the thermally-conductive component; and

an electrical connection configured to relay electrical power to the electrically-conductive component; and

at least one electrically-insulative sleeve extending at least partially around all of the three or more thermal units;

a controller configured to operate the filament drive mechanism to feed the filament to the inlet end of the liquefier, and to independently operate each of the three or more thermal units to produce independently heatable zones along the longitudinal length of the liquefier for melting the consumable material of the fed filament in the liquefier.

16. The system of claim 15 , wherein each of the three or more thermal units further comprises a temperature sensor configured to detect an electrical resistance of the thermally-conductive component, and to relay the detected electrical resistance to the controller.

17. The system of claim 15 , wherein the controller is configured to independently operate each of the three or more thermal units in a manner that comprises shutting down the three or more thermal units in a downward serial manner.

18. The system of claim 15 , wherein the at least one electrically-insulative sleeve comprises a ceramic material.

19. The system of claim 15 , wherein the controller is configured to independently operate each of the three or more thermal units in a manner that comprises directing how many of the independently heatable zones are to be operated based on a toolpath to be followed.

20. The system of claim 15 , wherein the liquefier includes a length portion along the longitudinal length between the inlet end of the liquefier and a top-most thermal unit of the three or more thermal units.