High-flow equalized and directed duct for solidifying liquid extrusion

Abstract

A shroud for an extruder nozzle of a 3D printer structured for confining an airflow to an area near a liquid extruded from the nozzle, the shroud comprising a plurality of input vents in a baffle plate formed integrally or affixed to a frustoconical shroud body having a center opening in a spike plate; multiple, equalized vents and constriction outflow vents in the shroud body; wherein a ratio of an opened surface area of each the constriction outflow vents is less than an opened surface area of each of the input vents; wherein all slots in the baffle plate are between vents and not directly behind vents.

Description

ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 1 of 9HIGH-FLOW EQUALIZED AND DIRECTED DUCT FOR SOLIDIFYING LIQUID EXTRUSIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of provisional application 63 / 769485, filed March 10, 2025, the entire contents of which are hereby incorporated by reference for all purposes as if fully set forth herein.TECHNICAL FIELD

[0002] One technical field of the present disclosure is 3D printers. Another technical field is air cooling systems for the nozzles of 3D printers.BACKGROUND

[0003] The approaches described in this section are approaches that could be pursued but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.

[0004] 3D printers use a heated, hot nozzle to extrude a molten polymer filament or resin onto a work surface to form a workpiece. Cooling a volume of air near the nozzle and the workpiece is necessary to facilitate correct solidification of the molten material to form the part, avoid distorting completed regions of the workpiece, and maintain a stable work surface or bed.

[0005] Common cooling solutions in the industry today include: (a) Compressed air is blown through pinholes in a small metal tube around the extruder nozzle, also known as 'berd air', providing only low airflow, (b) A large, constricted ring, relatively far from the nozzle, provides unfocused airflow over a large area, (c) Airflow from one or two directions, with small vents close to the nozzle. This arrangement provides low airflow and introduces inconsistency between the part's surfaces due to one vertical side being cooled more than the others, (d) Large fans blow airflow across the entire volume of the 3D printer, cooling the entire 3D printed part during printing. Some geometries of 3D printed parts will cool drastically more at layers higher up, causing failures, particularly of tall parts often taking longer to print. This approach increases the frequency of print failures late in the cycle, resulting in excess expense, materials, and labor.

[0006] Rarely, some combination of the above has been attempted to reduce the severity of each of these shortcomings.515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 2 of 9

[0007] Usually, airflows are supplied by ambient or chilled air, which is far below the -200 °C melting point at which most plastics are extruded as a liquid. However, in some cases, such as clay extrusion, intentionally hot air may be used for warming. In currently less common cases, due to factors such as exotic materials or very high throughput requirements, it may be possible to pump other working fluids such as cryogenic fluids (e.g., liquid nitrogen) or other fluids (e.g., water).

[0008] Based on the foregoing, the referenced technical fields have developed an acute need for better ways to supply a cooling airflow near a 3D printer nozzle.SUMMARY

[0009] The appended claims may serve as a summary of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the drawings:

[0011] FIG. 1 is a bottom plan view of a 3D printer nozzle shroud according to one embodiment.

[0012] FIG. 2 is a top perspective view of the shroud of FIG. 1.DETAILED DESCRIPTION

[0013] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the present invention.

[0014] This disclosure may describe one or more different inventions, with alternative embodiments to illustrate examples. Other embodiments may be utilized, and structural, logical, software, electrical, and other changes may be made without departing from the scope of the particular inventions. Various modifications and alterations are possible and expected. Some features of one or more of the inventions may be described with reference to one or more particular embodiments or drawing figures, but such features are not limited to usage in the one or more particular embodiments or figures with reference to which they are described. Thus, the present disclosure is neither a literal description of all embodiments of one or more inventions nor a listing of features of one or more inventions that must be present in all embodiments.515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 3 of 9

[0015] Headings of sections and the title are provided for convenience but are not intended to limit the disclosure in any way or as a basis for interpreting the claims. Devices described as in communication with each other need not be in continuous communication with each other unless expressly specified otherwise. In addition, devices that communicate with each other may communicate directly or indirectly through one or more intermediaries, logical or physical.

[0016] A description of an embodiment with several components in communication with one other does not imply that all such components are required. Optional components may be described to illustrate a variety of possible embodiments and to illustrate one or more aspects of the inventions fully. Similarly, although process steps, method steps, algorithms, or the like may be described in sequential order, such processes, methods, and algorithms may generally be configured to work in different orders unless specifically stated to the contrary. Any sequence or order of steps described in this disclosure is not a required sequence or order. The steps of the described processes may be performed in any order practical. Further, some steps may be performed simultaneously. The illustration of a process in a drawing does not exclude variations and modifications, does not imply that the process or any of its steps are necessary to one or more of the invention(s), and does not imply that the illustrated process is preferred. The steps may be described once per embodiment but need not occur only once. Some steps may be omitted in some embodiments or occurrences, or some steps may be executed more than once in a given embodiment or occurrence. When a single device or article is described, more than one device or article may be used in place of a single device or article. Where more than one device or article is described, a single device or article may be used instead of more than one device or article.

[0017] The functionality or features of a device may be alternatively embodied by one or more other devices that are not explicitly described as having such functionality or features. Thus, other embodiments of one or more inventions need not include the device itself. Techniques and mechanisms described or referenced herein will sometimes be described in singular form for clarity. However, it should be noted that particular embodiments include multiple iterations of a technique or manifestations of a mechanism unless noted otherwise. Process descriptions or blocks in figures should be understood as representing modules, segments, or portions of code, including one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 4 of 9embodiments of the present invention in which, for example, functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved.

[0018] 1. GENERAL OVERVIEW

[0019] Shroud airflow maintains consistent cooling or warming, enabling optimized printing. Achieving an equalized airflow ensures that extruded liquid cools at equal rates on all sides of the nozzle. Unequal airflows result in different sides of a part having disparate textures. Simply increasing airflow enough to overcome that is neither possible nor desirable. Extrusion cooling is physically limited by the surface area defined by the extruder nozzle’s diameter, which is subject to a product! vity / quality tradeoff. Variable-speed fans are typically used to control airflow and prevent the entire 3D-printed part from cooling below the thermoplastic softening temperature (~120°C), which helps maintain good adhesion both to the heated bed and between successive print layers. Confining flow tightly around the recently extruded liquid reduces excessive cooling of the overall 3D part, maintaining the entire part reasonably above the thermoplastic softening temperature needed for bed and subsequent layer adhesion.

[0020] FIG. 1 illustrates a bottom plan view of a 3D printer nozzle shroud according to one embodiment. FIG. 2 illustrates a top perspective view of the shroud of FIG. 1. Referring first to FIG. 1, in one embodiment of an improved shroud 10, a base plate incorporating a baffle plate 5 is formed integrally or affixed to a frustoconical shroud body 14 having a central opening 12. Cooling or warming air flows inward (Fig. 1, element 1) from large ducts to external fan or air movement devices, and cooling or warming air flows outward through multiple, equalized vents (Fig. 2, element 2).

[0021] In an embodiment, equalized airflow occurs because the ratio of the opened surface area of outflow vents (Fig. 2, element 4) is somewhat less than the opened surface area of input vents (Fig. 1, element 3). Constriction from the smaller total output aperture obstructs some pressure from the higher-flow vents 3 to increase behind all the other equally sized vents 2, redistributing flow more equally.

[0022] A baffle plate (Fig. 1, element 5) obstructs higher flow input streams from directly reaching output vents 4, redirecting these flows to increase pressure more equally behind the baffle plate 5 itself, redistributing flow more equally. To ensure higher-flow streams are redirected, all the slots in the baffle plate 5 are between vents, never directly behind vents.515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 5 of 9

[0023] Correction differences in the dimensions (Fig. 1, element 6) of slots in the baffle plate 5 slightly change the amount of flow through each slot. These differing dimensions are determined through simulation or prototyping experiments and then permanently set in the design to be included during production. The correction differences in slot dimensions adjust unequal flows without additional constriction, reducing the amount of constriction needed in the ratios of apertures between total input aperture, total baffle aperture, and total output aperture. As such, flow can be increased by reducing the amount of constriction while maintaining equalization by changing the correction differences in the baffle plate 5 slots.

[0024] A spike plate (Fig. 2, element 7) directs airflow to follow along the surface of this plate 7, getting closer to the liquid extrusion before spreading out. Experiments visualizing the airflow using smoke or fog have shown that equalized airflow not only meets in the center but predominantly exits as a rapid, focused beam of airflow only a few degrees offset from directly vertical. Moreover, the airflow is seen to remain confined to a tight layer until more than a few millimeters after leaving the spike plate 7. These experiments demonstrated that the structure of the improved shroud 10 shown in FIG. 1 and FIG. 2 is effective in confining airflow to a small area near the recently extruded liquid.

[0025] The center opening 12 in the middle of the spike plate 7 accommodates the extruder nozzle and a small metal tube around the extruder nozzle, releasing cooling through pinholes under high compression (5 PSI to 100 PSI) (aka. 'berd air'). Such a combination offers the highest practical performance, combining a large amount of focused flow from the shroud 10 with a small amount of especially highly focused flow as close to the nozzle as possible.

[0026] The shroud 10 can also operate in a cooling mode using chilled air.

[0027] Changing the vent and baffle slot 5 dimensions can reduce constriction by a factor of at least 5:1, increasing flow by a similar magnitude. Although this is not normally necessary, specialized shrouds 10 can be produced that maximize flow, maximizing useful extrusion speeds. Such embodiments could be used for cooling the liquid extrusion rapidly enough to prevent the highest anticipated 3D printing speeds at kilograms per hour from being printed as a semi-liquid blob rather than a useful 3D printed part. Such improved productivity would maximize productivity for users with exceptional use cases to desire such high throughput and accept very slightly rougher surface quality. Example applications include printing housing building materials, such as low-infill lumber replacement.515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 6 of 9

[0028] Therefore, the shroud of this disclosure is a versatile mechanism that can maximize equalization at reasonable airflow or absolutely maximize airflow around an extruder nozzle while still maintaining better equalization than alternatives by using the entire area around the nozzle for vents.

[0029] 2. BENEFITS AND IMPROVEMENTS

[0030] Being made of high-temperature 3D-printed material, such as 3D-printed metal or ceramic, this shroud is not limited to any particular purpose, material, etc., other than to effectively solidify essentially liquid extrusion by some or other flow through it, etc.

[0031] In the foregoing specification, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the invention, and what is intended by the applicants to be the scope of the invention, is the literal and equivalent scope of the set of claims issued from this application in the specific form in which such claims issue, including any subsequent correction.515849269.1

Claims

ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 7 of 9CLAIMSWhat is claimed is:

1. A shroud for an extruder nozzle of a 3D printer structured for confining an airflow to an area near a liquid extruded from the nozzle, the shroud comprising:a plurality of input vents in a baffle plate formed integrally or affixed to a frustoconical shroud body having a center opening in a spike plate;multiple, equalized vents and constriction outflow vents in the shroud body; wherein a ratio of an opened surface area of each the constriction outflow vents is less than an opened surface area of each of the input vents;wherein all slots in the baffle plate are between vents and not directly behind vents.

2. The shroud of claim 1, wherein the baffle plate obstructs higher flow input streams from directly reaching the outflow vents, redirecting these flows to increase pressure behind the baffle plate, thereby redistributing flow more equally.

3. The shroud of claim 1, wherein the spike plate directs airflow to follow along its surface closer to the liquid before spreading out.

4. The shroud of claim 1, wherein the center opening of the spike plate accommodates the extruder nozzle and a tube around the extruder nozzle, releasing cooling through pinholes under high compression of 5 PSI to 100 PSI.

5. A 3D printer comprising:an extruder nozzle;a shroud structured for confining an airflow to an area near a liquid extruded from the nozzle, the shroud comprising:a plurality of input vents in a baffle plate formed integrally or affixed to a frustoconical shroud body having a center opening in a spike plate;multiple, equalized vents and constriction outflow vents in the shroud body; wherein a ratio of an opened surface area of each the constriction outflow vents is less than an opened surface area of each of the input vents;515849269.1ATTORNEY DOCKET NO. PATENT APPLICATION 092142.0105Page 8 of 9wherein all slots in the baffle plate are between vents and not directly behind vents.

6. The 3D printer of claim 5, wherein the baffle plate obstructs higher flow input streams from directly reaching the outflow vents, redirecting these flows to increase pressure behind the baffle plate, thereby redistributing flow more equally.

7. The 3D printer of claim 5, wherein the spike plate directs airflow to follow along its surface closer to the liquid before spreading out.

8. The 3D printer of claim 1, wherein the center opening of the spike plate accommodates the extruder nozzle and a tube around the extruder nozzle, releasing cooling through pinholes under high compression of 5 PSI to 100 PSI.515849269.1

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