Adaptable high-performance extrusion head for fused filament fabrication systems
An extrusion head for a three-dimensional printer is disclosed including a feed tube, a heater, a cooler, and a bridge. The feed tube can be made of metal and has an inlet for receiving a forwardly driven filament of solid deposition material, an outlet, a downstream portion adjacent to the outlet, an upstream portion upstream from the downstream portion, and an internal passage extending from the inlet to the outlet. The heater is thermally coupled with the downstream portion of the feed tube for heating a filament to provide softened fluid deposition material. The cooler is thermally coupled with the upstream portion and spaced generally axially from the heater to define a generally axially extending gap traversed by the feed tube. The bridge traverses the gap and provides a rigid mechanical connection between the heater and the cooler.
1. An extrusion head for a three-dimensional printer, the extrusion head comprising:
a generally axially extending metal feed tube having an inlet for receiving a forwardly driven filament of solid deposition material, an outlet, a downstream portion adjacent to the outlet, an upstream portion upstream from the downstream portion, and an internal passage extending from the inlet to the outlet;
a heater thermally coupled with the downstream portion for heating a filament positioned within the feed tube internal passage to provide softened deposition material;
a cooler thermally coupled with the upstream portion for reducing upstream heat transfer, the cooler spaced generally axially upstream from the heater; and
a generally axially extending gap, bound by a bridge traversing the gap between the cooler and the heater; wherein,
the gap is traversed by the metal feed tube;
the bridge is spaced radially and apart from the metal feed tube, the bridge provides a rigid mechanical connection between the heater and the cooler, and the bridge at least partially reduces mechanical loading on the feed tube, wherein the bridge comprises:
a first structural component, spaced radially and apart from the feed tube, and having a first portion bearing against the heater and a second portion bearing against the cooler, wherein the first structural component at least partially relieves mechanical loading on the feed tube; and
a second structural component, spaced radially and apart from the feed tube, and having a first portion bearing against the heater and a second portion bearing against the cooler, wherein the second structural component at least partially relieves mechanical loading on the feed tube.
2. The extrusion head of claim 1 , wherein at least one of the first structural component or the second structural component is a spacer or tension member.
3. The extrusion head of claim 1 , wherein the bridge further comprises a third structural component, spaced radially and apart from the feed tube, and having a first portion bearing against the heater and a second portion bearing against the cooler, wherein the third structural component at least partially relieves mechanical loading on the feed tube.
4. The extrusion head of claim 1 , wherein the metal feed tube comprises stainless steel.
5. The extrusion head of claim 4 , wherein the metal feed tube comprises hypodermic tubing.
6. The extrusion head of claim 1 , wherein the metal feed tube has a wall thickness less than 0.005 in. (less than 0.13 mm).
7. The extrusion head of claim 1 , wherein the metal feed tube has an inside diameter from 0.07 in. to 0.13 in. (1.8 mm to 3.3 mm).
8. The extrusion head of claim 1 , wherein the metal feed tube has a length from 0.5 in. to 3 in. (12 mm. to 76 mm.).
9. The extrusion head of claim 1 , wherein the portion of the feed tube traversing the gap extends axially from 0.03 in. to 3 inches (0.8 mm. to 76 mm.).
10. The extrusion head of claim 1 , wherein the metal feed tube internal passage is coated internally with a material reducing adhesion of the deposition material.
11. The extrusion head of claim 10 , wherein the material reducing adhesion of the deposition material is electroless nickel, an electroless nickel-boron composite, tungsten disulfide, molybdenum disulfide, boron nitride, diamond-like carbon, zirconium nitride, titanium nitride, or a combination of two or more of these.
12. The extrusion head of claim 1 , further comprising a bushing having an axial bore defined by a wall secured to the feed tube downstream portion, the bushing further comprising an exterior threaded surface engaged with the heater block threaded bore.
13. The extrusion head of claim 12 , wherein a line drawn from the first structural component to the second structural component passes through the bushing.
14. The extrusion head of claim 1 , wherein the first structural component and the second structural component of the bridge are each loaded in either compression or tension to resist the axial push-pull forces applied by the filament feed system.
15. The extrusion head of claim 1 , wherein the cooler comprises a heat sink comprising heat-conductive material.
16. The extrusion head of claim 1 , wherein the cooler comprises a heat sink comprising heat-conductive material and comprising an internal heat transfer passage configured to receive a cooling fluid.
17. The extrusion head of claim 1 , wherein at least one structural component comprises hypodermic tubing.
18. The extrusion head of claim 17 , wherein the hypodermic tubing is sized between 7 XX and 14 XX gauge, inclusive.
19. The extrusion head of claim 1 , wherein at least one- structural component comprises thermal insulation material.
20. The extrusion head of claim 19 , wherein the thermal insulation material is calcium silicate, ceramic, glass, an engineering thermoplastic, zirconia, mica, Portland cement or a combination of any two or more of these.