Patent Application
20240208141
3-Dimensional (3D) printers are evolving for efficient, low cost use in tasks that traditionally required large machined molds or dies to produce. Efficient manufacturing is achievable for modest volumes of printed articles without the upfront investment in a large, expensive die. 3D printers employ a nozzle for extruding a print medium, often through a process known as fused deposition modeling, where a polymer filament passes through a heated nozzle, and emerges in a molten state to flow onto an accumulating article, where it solidifies and fuses to previous courses or layers of the printed article.
A nozzle apparatus for a 3D printer employs a center post or shape and extrudes a circumferential, tubular form having a central void. The nozzle includes a radial arrangement of prongs or supports around a center post, which provides space for a molten print medium to flow in a 360° form around the center post. The nozzle extrudes a hollow tubular form around the post that can lay a tube shaped article on a perpendicular print bed, or can be used to deposit high resolution, hollow cylindrical segments for forming lightweight articles with less volume of print medium required due to the hollow extruded shape. A stream of air or gas may be emitted into the center of the extrusion for maintaining a tubular shape. Other suitable shapes may be employed by altering the contour of the center post and the bore.
Configurations herein are based, in part, on the observation that extrusion printers such as 3-Dimensional (3D) and Fused Deposition Modeling (FDM) printers are gaining popularity for additive manufacturing and similar generation of low cost, precision formation of components. Unfortunately, conventional approaches to 3D printing tend to generate solid or dense representation of the volumes so formed, which adds weight and consumes additional material. Accordingly, configurations herein substantially overcome the shortcomings of solid, homogeneous moldings by extruding a tubular form with a hollow cross section. By extruding a hollow form of a closed shape surrounding a void, solid volumes are formed from a network or iteration of the closed shape, saving material without substantially sacrificing strength. Injection of air into the cross-section void during formation prevents the closed shape from contracting onto itself from reduced pressure. Tubular members for fluid transport may also be formed.
In further detail, the 3D printing extrusion nozzle includes an inlet configured for receiving molten extrusion material, and a coupling for engaging the inlet with an extrusion source. An extrusion channel fluidically couples to the inlet and leads to an extrusion outlet, and an insert disposed in the extrusion channel imparts a closed shape to the molten extrusion material upon passage through the outlet for forming a hollow tubular extrusion. An air injection channel in the insert provides an airflow to fill the void formed in the hollow for preventing low pressure from collapsing the hollow tubular shape.
The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
Additive manufacturing (3D printing) allows engineers and researchers to create complex and intricate geometries that would otherwise be incredibly difficult to manufacture with traditional techniques (e.g., subtractive manufacturing or injection molding). The most commonly available form of additive manufacturing is FDM printing. FDM printers use a material extrusion process, where thermoplastics are deposited layer by layer and parts are built from the ground up. Thermoplastics are plastics that at some temperatures become soft and flexible, and solidify when cooled. Feedstock includes a filament, usually rolled on a spool. Common filament types include Polylactic acid (PLA), Thermoplastic polyurethane (TPU), Acrylonitrile butadiene styrene (ABS), Acrylonitrile styrene acrylate (ASA) and Polycarbonate (PC). Although FDM printers excel at speed, build size, and material availability, they struggle to produce high-resolution prints at a small scale, and the use of layers leads to anisotropic parts that are weaker at layer lines and therefore compromise the material's mechanical properties. 3D printers typically generate their “prints” by layering material on top of previously laid material in order to create the desired geometries and parts.
One area where current methods of 3D printing have fallen short is in the creation of small (<2 mm outer diameter), thin walled, and flexible tubular structures. The small size and hollow geometries of these structures are difficult to manufacture using current 3D printing methods on the market. FDM printers are challenged in producing high-resolution and accurate shapes for tubes this size. The highest-resolution printers currently available on the market (selective laser sintering, or SLS and stereolithography, or SLA) can produce smaller tubes than FDM printers but are still incapable of producing tubes smaller than 3 mm and the tubes that they can produce suffer from inaccurate OD and ID dimensions and inconsistencies between prints. The largest issue that affects tubes created on all current 3D printers is their anisotropic material properties from the layered construction.
3D printers generally operate via extrusion for rendering the printed object. A print nozzle is the vessel through which the molten print medium is extruded in a controlled manner.
In order to maintain the benefits of FDM printers, (speed, build size, and material availability), while also creating small, isotropic, and high-resolution extrusions, configurations herein depict a beneficial nozzle design that can be used to retrofit conventional FDM 3D printers. This nozzle design allows for any suitable melted thermoplastic to be pushed into the nozzle and emerge in a multi-feature extrusion (shapes with holes and/or non-circular shapes) such that the desired part can be “printed” in one consistent ‘layer”. Due to the design utilizing existing nozzle thread specifications, any FDM 3D printer can easily be adapted by simply swapping the nozzle via the coupling 112, and no further hardware modifications are required.
Therefore, the extrusion channel 114 has an interior wall 117 defining a shape (circular, in
The flow control member 250 and insert 116 is maintained in the cavity by friction and the pressure of melted plastic feedstock, avoiding the need for fasteners between the nozzle layers 140, 142, 144. The insert incorporates a central air channel for avoiding a vacuum effect inside of the newly formed closed shape tube from a lack of an air supply, which has a tendency to collapsed the tube, still a viscous melt 252, as the void created by the insert forms a lower pressure region. The configuration of
The nozzle 200 of
The flow control member 250 and insert 216 define a forward end 260 on a leading edge of the flow control member 250, and a rearward end 262. The forward end 260 is configured for insertion into the extrusion channel 114, as a body defined by the redial members 232 becomes slidably engaged with an interior wall 117 of the extrusion channel. A beveled edge 264 on an interior of the extrusion outlet 120 is adapted to engage the forward end 260 at a limit of forward travel for aligning the airflow gap 246 with the airflow receptacle 248 when the forward end 260 engages the beveled edge 264. The forward end 260 may itself have a complementary bevel for enhancing position, however the limit of forward travel aligns the airflow gap 246 and receptacle 248.
An extrusion chamber 268 forms in the extrusion channel 114 forward of the end 260 where the extrusion chamber defines an open volume 270 surrounding the insert 216 and the air injection vessel 210, The open volume 270 is responsive to air from the air injection vessel 210, where the air is enclosed in a hollow extruded form resulting from forced molten extruded melt 122 through the extrusion channel 114. The insert forms 216 a void in a cross section of a closed shape defined by an extruded melt forced through the extrusion channel.
In the example configuration, the insert 216 is concentric with the interior wall 117 of the extrusion channel 114 and the insert and interior wall define a substantially constant circumferential gap 115, which results in an extruded form 252 having a uniform tubular wall. A circular extrusion may, of course, be altered by a shape of the insert 216 and the shape of the extrusion channel 114 and the outlet 120, for forming any suitable closed shape cross-section to the extruded form 252.
While the system and methods defined herein have been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
This patent application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent App. No. 63/434,503, filed Dec. 22, 2022, entitled “HOLLOW EXTRUSION NOZZLE,” and on U.S. Provisional Patent App. No. 63/459,816, filed Apr. 17, 2023, entitled “HOLLOW EXTRUSION NOZZLE,” both incorporated herein by reference in entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63459816 | Apr 2023 | US | |
| 63434503 | Dec 2022 | US |
