Extruded deposition of fiber reinforced polymers
A fiber reinforced polymer part is fabricated by rastering a deposition head over a substrate, and additively forming part features by extruding a polymer having an entrained continuous reinforcement from the deposition head onto a substrate.
1. A deposition fabrication method, comprising:
establishing a pressurized stream of a first polymer through a tube, wherein the first polymer has a first melt temperature;
entraining a carbon nanotube reinforcement within the pressurized stream, wherein the carbon nanotube reinforcement is pre-impregnated with a second polymer that has a second melt temperature, wherein the second melt temperature is less than the first melt temperature, and wherein entraining is performed above the first melt temperature but below the second melt temperature, and wherein entraining further comprises:
feeding the carbon nanotube reinforcement into the tube, the tube being disposed inside an annular inlet of an entrainment barrel surrounding the tube, wherein the tube ends at an entrance to a capillary tube disposed inside the entrainment barrel;
flowing the liquified polymer into the annular inlet and around the tube, including flowing the liquified polymer past the tube and into the capillary tube via a convergence region in which the liquified polymer is allowed to flow onto the carbon nanotube reinforcement just as the carbon nanotube reinforcement enters the capillary tube; and
depositing a bead of the polymer and the carbon nanotube reinforcement from the tube onto a substrate.
2. The deposition fabrication method of claim 1 , wherein entraining the carbon nanotube reinforcement includes feeding at least one of a tow, a roving and a yarn into the tube.
3. The deposition fabrication method of claim 1 , wherein entraining the carbon nanotube reinforcement includes feeding one of a dry fiber reinforcement and a pre-impregnated fiber reinforcement into the tube.
4. The deposition fabrication method of claim 1 , wherein entraining the carbon nanotube reinforcement includes feeding one of a continuous fiber reinforcement and a discontinuous fiber reinforcement into the tube.
5. The deposition fabrication method of claim 1 , further comprising:
heating the carbon nanotube reinforcement.
6. The deposition fabrication method of claim 1 , further comprising:
coupling together a plurality of discontinuous fiber reinforcements into a chain, and wherein entraining carbon nanotube reinforcement includes drawing the chain into the pressurized stream.
7. The deposition fabrication method of claim 1 , further comprising:
encapsulating the carbon nanotube reinforcement in a polymer having a melt temperature that is higher than the melt temperature of the polymer in the pressurized stream thereof.
8. The deposition fabrication method of claim 1 , further comprising:
maintaining a desired viscosity of the polymer by applying a varying amount of heat to the tube along a length of the tube.
9. The deposition fabrication method of claim 1 , further comprising:
depositing a bead of polymer onto the substrate, wherein the polymer is devoid of the carbon nanotube reinforcement.
10. The deposition fabrication method of claim 1 , wherein establishing the pressurized stream includes injecting the polymer under pressure into the tube.
11. The deposition fabrication method of claim 10 , wherein injecting the polymer under pressure into the tube includes establishing a pressure differential between an upstream end and a downstream end of the tube.
12. The deposition fabrication method of claim 10 , further comprising:
drawing the carbon nanotube reinforcement through the tube using the pressurized stream.
13. The deposition fabrication method of claim 10 , further comprising:
drawing the carbon nanotube reinforcement through the tube using capillary action.
14. The deposition fabrication method of claim 10 , wherein entraining the carbon nanotube reinforcement includes introducing the carbon nanotube reinforcement into an upstream end of the tube.
15. The method of claim 1 further comprising:
maintaining a third temperature at a material supply end of an entrainment barrel that contains the tube at a higher temperature than a fourth temperature at a material deposition end of the entrainment barrel.
16. The method of claim 1 , wherein the first polymer is different than the second polymer.
17. The method of claim 15 , wherein the first polymer is different than the second polymer.