Additively manufactured articles having a flock-like surface

Abstract

Provided herein are systems and methods that use three-dimensional (3D)-printing to produce articles having flock-like surfaces. The method can include providing a geometric model of an article to be 3D-printed; generating a point cloud associated with the surface of the article; sampling the point cloud to provide a plurality of fiber reference points; adding fibers to the geometric model associated with the fiber reference points; and assigning fiber features to the fibers in the geometric model. An article produced by such a method is described herein.

Description

[0001]ADDITIVELY MANUFACTURED ARTICLES HAVING A FLOCK-LIKE SURFACE NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION Portions of the material in this patent document are subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14. RELATED APPLICATIONS This application claims priority to and the benefit under 35 USC 119(e) of U.S. Provisional Application Serial No. 63 / 587,590 filed on October 3, 2023, entitled “ADDITIVELY MANUFACTURED ARTICLES HAVING A FLOCK-LIKE SURFACE,” the entire contents of which are incorporated herein by reference. BACKGROUND Applying texture and micro-structures to conventionally manufactured surfaces has been highly demanded and widely adopted. For example, applying dense and fine fibers to relatively harder surfaces (generally referred to as flocking) is a typical method to add soft finish and achieve specific surface properties. However, the major flocking techniques used in the industry usually need multiple processes and have limitations on surface shape, materials, and fiber features (including density, distribution, direction, length, element size). For example, static electronic flocking can only apply to relatively flat surfaces, has a limited density of fibers, has a limited length of fibers; and has a limited fiber thickness. Furthermore, the density and direction of fibers cannot be changed dramatically or selectively from one area to another area of the structure. SUMMARY In contrast to prior methods, the systems and methods described herein use three- dimensional (3D)-printing to produce articles having flock-like surfaces. Both the articles themselves and the methods used to produce the articles are new and advantageous For example, the systems and methods described herein can be fast and customizable, allow full control of each individual flock fiber, allow attribution mapping based on holistic input, and enable visualization of a design to be printed with predictable results. The systems and methods described herein can reduce or eliminate limitations (and / or create new advantages) associated with: (a) irregular surface flocking (e.g., one can apply flocking on both micro concave and convex surfaces, not limited to only larger, smoother surfaces); (b) interior flocking (e.g., flocking can be applied to both sides of the base surface, even the inner surface of a closed shell); (c) use of a single step or material (e.g., flocking together with monolithic structures can be design and produced at once); (d) selective flocking (e.g., variations on density, distribution, orientation, length, thickness, etc. can be selectively applied); (e) fiber features can be adjusted (e.g., including density, distribution, direction, length, element size, section shape, subdivided structures, etc.); and / or (f) multilayer flocking (e.g., the base surfaces of the flocking can be multiple and intersected with each other). In an aspect, provided herein is a method for producing an article to be 3D-printed having a flock-like surface. The method can include providing a geometric model of the article to be 3D-printed; generating a point cloud associated with a surface of the article; sampling the point cloud to provide a plurality of fiber reference points; adding fibers to the geometric model associated with the plurality of fiber reference points; and assigning fiber features to the fibers in the geometric model. In some embodiments, the method further comprises rendering the geometric model into instructions suitable for controlling a 3D printer to produce the article having the fibers. In some embodiments, the method further comprises executing the instructions to produce the article having the fibers. In some embodiments, the point cloud is generated using surface discretization. In some embodiments, the fiber features are assigned by parametric morphing. In some embodiments, the fiber features include length, thickness, density, orientation, and shape. In some embodiments, only a portion of the surface of the article comprises a point cloud and / or fiber reference points. In some embodiments, the fibers are formed from the same material and are contiguous with the 3D-printed article. In some embodiments, the fibers comprise lines, loops, feathers, or flaps. In another aspect, provided herein is an article produced by a method described herein. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows an example of a surface of an article to be 3D printed in accordance with one or more embodiments of the present disclosure. FIG.2 shows an example of surface discretization in accordance with one or more embodiments of the present disclosure. FIG. 3 shows an example of a point cloud in accordance with one or more embodiments of the present disclosure. FIG.4 shows an example of vectors in accordance with one or more embodiments of the present disclosure. FIG.5 shows an example of sampling the point cloud in accordance with one or more embodiments of the present disclosure. FIG.6 shows an example of fiber reference points in accordance with one or more embodiments of the present disclosure. FIG. 7 shows an example of fiber features in accordance with one or more embodiments of the present disclosure. FIG. 8 shows an example of parametric morphing in accordance with one or more embodiments of the present disclosure. FIG.9 shows an example of a bottom-up system for 3D-printing. FIG.10 shows an example of a top-down system for 3D-printing. FIG.11 shows an example of a system for 3D-printing on a pliable substrate, which is suitable for performing the methods and making the substrates described herein. FIG. 12 shows an example wireframe representation of a simple wire according to various embodiments described herein. FIG. 13 shows a uniform populate function showing hairs applied to a surface to create a flock-like surface, as described herein. FIG. 14 shows an example of a lip applicator having a flock-like surface in accordance with one or more embodiments of the present disclosure. FIG.15 shows an example of a Velcro (hook and loop adhesive) in accordance with one or more embodiments of the present disclosure. FIG.16 shows an example of a surface for vibratory conveyance in accordance with one or more embodiments of the present disclosure. FIG. 17 shows an example of mascara applicator having a flock-like surface in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION Recent advances in additive manufacturing (e.g., 3D printing technology) allow complex geometries that are difficult or impossible to make with conventional manufacturing technologies. However, there is a need for systems and methods that can be used to create articles having desired surface properties. The end-to-end platform described herein includes designing, visualizing, and manufacturing micro structures, integratively and together with its surface texture (i.e., flocking). The stereolithography technique referred to as Digital Light Processing (DLP) can achieve a printed resolution of less than 100 micrometers (um) and be used to perform the methods and create the articles described herein. Surface area per volume of a geometry is often used to identify how absorbent a material is. Flocking is an effective way to dramatically increase the absorption rate of the base material. It can also add extra softness to the article. Selectively applying flocking (i.e., texturing) with different attributions as described herein can achieve different properties and functions of the surface, which has value but it is difficult to design or manufacture using prior approaches. In some examples, only a portion of the surface includes fiber reference points and a point cloud, as described herein. As used herein, the term "flocking", "flock", "flocked", and the like generally refer to an article having (and / or method for making) fine hairs or similar features on the surface of an article. As described herein, the dimensions, density, shape, location, or other attributes of these hairs or features do not necessarily correspond to those produced by prior flocking techniques (e.g., static electricity flocking). Furthermore, the steps and materials used in the methods described herein do not necessarily correspond to those produced by prior flocking techniques (e.g., static electricity flocking). The term "flock-like" can be used herein to encompass the differences but general similarities between prior flocking methods and the methods and articles described herein. In an aspect, provided herein is a method for producing an article to be 3D-printed having a flock-like surface. The method can include (a) providing a geometric model of the article to be 3D-printed; (b) generating a point cloud associated with the surface of the article; (c) sampling the point cloud to provide a plurality of fiber reference points; (d) adding fibers to the geometric model associated with the fiber reference points; and (e) assigning fiber features to the fibers in the geometric model. The geometric model may be rendered into instructions suitable for controlling a 3D printer to produce the article having the fibers, and those instructions may be executed to produce the article. In some examples, the fibers are formed from the same material and are contiguous with the article. Turning to the figures, FIG.1 shows the surface of the article to be 3D-printed (i.e., geometric model thereof). Part or all of this surface can be flocked. It can be the physical surface 100 on which the flocking fibers will be located or a surface grid 102 of a lattice that braces the flocking fibers together. The base surface can be any shape. Base surfaces can be intersected (model 104). The base surface can be two sides 106 of the same geometry. FIG.2 shows an example of surface discretization, including the subdivision rules of the base surface. The type of the subdivision shape 200 can include any suitable shape (e.g., triangulation, hexagons). The size of the subdivision meshes 202 can also be varied, from 10 microns to 10 millimeters. A transition between two or more shapes can also be assigned. FIG.3 shows an example of a point cloud. The point cloud includes the collection of the points 300 at the junctions of subdivided meshes 302. The spacing between adjacent cloud points can vary from 10 microns to any customized value. The point cloud may correspond to subdivision shape 200 shown in FIG. 2. The point cloud may be generated using surface discretization. The point cloud may be generated according to techniques known to those skilled in the art. FIG. 4 shows a collection of the vectors of the base surface at each point from the point cloud of FIG.3. FIG.5 shows an example of sampling the point cloud (e.g., the point cloud shown in FIG. 3) to provide a plurality of fiber reference points. The sampling can include determination of density, attribution, and / or detection. The choosing of the fiber reference points 500 from the point cloud can follow one or a combination of the rules of density, attribution, and detection. Density 502 can include a defined minimum distance between every two points from a point cloud. Attribution 504 can include a collection of values (e.g., 0 or 1) assigned to the point by parametric morphing. For example, 0 can mean to exclude the point, while 1 can mean to include the point. Detection 506 can include a defined threshold of adjacency to a or groups of defined geometries. For those fiber reference points within the detection, their attribution can be set to 1; for those outside the detection threshold, the attribution can be set to 0. FIG.6 shows fiber reference points including the collection of points from the point cloud after the sampling. These points 600 usually may be the root points of the fiber line. A collection of the flocking fibers 602 is shown. The fiber centerline falls between 0.01 mm to 0.9 mm, and the length falls between 0.5 mm to 6 mm. The taper at the base can be as low as 0.1 mm to 0.6 mm and the tip of the taper or end of the fiber can range from 0.05 mm to 0.25 mm. FIG.7 shows an example of fiber features. The feature settings of one fiber line can include its length 700, orientation 702, section profile 704, thickness 706, and subdivision structure 708. The fiber features can also include density and shape. FIG. 8 shows an example of parametric morphing. The distribution of a parameter (e.g., 0 to 1) can be assigned to each of the fiber features among all fibers. For example, if the fiber length parameter is from 2 mm to 3 mm and morphed following the location of fiber reference point from lowest to the top-most, then the lowest fiber will be assigned the length of 2 mm and the top-most fiber will be assigned the length of 3 mm. A fiber in the middle will be assigned a length between 2 and 3 mm. Parametric morphings can be applied multiple times. The rules of distributing the parameter morphing can include location, fiber orientation, and customized mapping. FIG.8 shows the combination results of applying two parametric morphings following two morphing patterns. They are morphing thickness based on location 800; morphing length based on location 802; morphing thickness based on fiber orientation 804; and morphing length based on fiber orientation 806. The final flocking assembly can include the collection of the flocking fibers. It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of subject matter within this disclosure are contemplated as being part of the inventive subject matter disclosed herein. Also, it should be appreciated that one or more 3D printing systems may be used to implement the one or more systems, methods and file formats to 3D print such microstructures. For example, some embodiments may be used in conjunction with one or more systems described in U.S. Patent Application Serial Number 16 / 552,382, filed August 27, 2019, incorporated herein in its entirety. However, it should be appreciated that other printer methods and systems may be used with embodiments as described herein. For example, the methods described herein can be performed with any suitable 3D printing hardware (e.g., having digital light processors). FIGs. 9-11 show systems for 3D printing. As seen in FIG. 9, printing can be performed from the bottom-up through a transparent window. Here, a container 900 can include a volume of photo-curable resin 905. UV light 910 can be projected through a glass plate or lens 915 onto a building platform 920. This can initiate polymerization into a cured article 925. The building platform can be moved upward, which can cause non-cured resin to flow and recoat 930 the printed article with resin such that a subsequent layer of the article can be printed. Similarly, FIG. 10 shows an example of a system for printing from the top-down. UV light 1000 can be projected from the top-down onto an open surface of photocurable resin 1005 that is contained in a vat 1010. The cured article 1015 can be printed onto a building platform 1020 which can be moved downward into the vat of resin after each print layer. This can result in un-cured resin 1025 flowing onto the surface of the cured article, which can be subsequently exposed to radiation to print another layer of the printed article. In some instances, this re-flow of resin is a rate limiting step of the overall process. Therefore, a recoating mechanism 1030 (e.g., mechanical arm) can assist the recoating process. One potential limitation of the top-down and bottom-up systems described herein thus far is that they require resetting the print stage after each article is printed and are not continuous processes. In contrast, FIG.11 shows an example of a system for printing on a pliable substrate. Here, the pliable substrate can be moved through a vat of the photo-curable resin in a continuous manner while article(s) are printed onto the substrate. UV radiation 1100 can be projected onto a surface of a volume of photo-curable resin 1105 in a container 1110 that is exposed to air. The printed article 1115 can be printed onto a pliable substrate 1120 that is moved through the photo-curable resin. In some cases, if the printing is continuous, a recoating mechanism is not used and recoating 1125 proceeds without mechanical assistance. A suitable system for printing on a pliable substrate is described in U.S. Patent Application Serial No.17 / 668,503, which is incorporated herein by reference in its entirety. In some cases, printing continuously on a pliable substrate may be preferred for the creation of textiles. The 3D printing systems described above can be used to print a variety of substrates for vibratory conveying. The shape of the substrate and its properties, such as the resolution of fine features, the consistency and extent of cure of the resin can be determined by the combination of many factors such as the mechanical attributes of the system, the chemical attributes of the resin, and the printing methodology. One printing methodology is to computationally “slice” a model of the 3D object to be printed into a series of layers that nominally constitute the 3D object when printed in succession. This process can be referred to as “rasterization” and printing of “rasterization data”. Further details about the digitization of a design and operation of a 3D printer suitable for production of the textiles described herein and further details of an exemplary computer system applicable to the techniques described herein can be found in PCT Patent Application Serial No. PCT / US2021 / 023962, which is incorporated herein in its entirety for all purposes. In particular, with reference to FIG.12, each wire (hair on the flock-like surface) can contain an array of nodes and attributes at each node, which enable a highly abstracted parametric representation hair-like or lattice structure. The collection of wireframes can be indexed. FIG.12 shows an example wireframe representation of a simple wire according to various embodiments. As shown here, the node is an array of indices pointing to the vertices of the fiber. This forms the underlying central polyline spine of the fiber. The diameter 1200 may be an array of numbers representing diameter of fiber at each vertex. The Start Face Normal 1202 may be normal direction of start face. This creates a clipping plane with its origin at start point. The End Face Normal 1204 may be normal to the direction of end face. This creates a clipping plane with its origin at end point. The Frontal Vector 1206 is a frontal facing vector of profile in world coordinate and determines the orientation of the cross- sectional profile. Twisting 1208 is an array of numbers representing incremental rotation angle of profile. Each rotation is relative to the previous profile; i.e., set to 0 for a non- twisting straight hair. Profile may be the name of the Profile function. Branching are names and weights of Branching functions. Finally, Level may be a flag to indicate slicing level of this mesh face. Dense faux flocking can be achieved in multiple ways with the .MESO file format, with different effects on fidelity and data efficiency. For example, every hair can be represented as a separate wireframe. In this case, each hair will have its unique parameter that would allow a feature control down to individual hair. Alternatively, the format can represent a collection of hair as Populate function of Shell faces. With this method, only a small amount of geometry information is required to describe a larger collection of hairs. Multiple Populate functions can be assigned to the same mesh face to overlapped effects. FIG. 13 shows an example of applying multiple populate functions to a same mesh face according to various embodiments. Here, a uniform populate function shows hairs applied to a surface. Still other aspects, examples, and advantages of these exemplary aspects and examples, are discussed in detail below. Moreover, it is to be understood that both the foregoing information and the following detailed description are merely illustrative examples of various aspects and examples, and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and examples. Any example disclosed herein may be combined with any other example in any manner consistent with at least one of the objects, aims, and needs disclosed herein, and references to “an example,” “some examples,” “an alternate example,” “various examples,” “one example,” “at least one example,” “ this and other examples” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the example may be included in at least one example. The appearances of such terms herein are not necessarily all referring to the same example. The methods described herein can be used with any 3D printing system. The photo- curable resin can be any suitable resin that is capable of polymerization when exposed to radiation (e.g., ultraviolet (UV) radiation). The resin can be part of a formulation that can include a photo-initiator, a UV absorber, a pigment, a diluent, and one or more monomers or oligomers. In some cases, UV radiation interacts with the photo-initiator to start a free-radical mediated polymerization of the monomers and / or oligomers. Traditionally, UV curable formulations used for additive manufacturing can include ethylenically (i.e., double bond) unsaturated oligomers and monomers (e.g., acrylates, methacrylates, vinyl ethers), diluents, photo-initiators, and additives. The oligomers and monomers can provide mechanical properties to the final product upon polymerization. Diluents can reduce overall formulation viscosity for ease of processing and handling. Diluents can be reactive and can be incorporated into the polymer matrix of the finished article. Photo-initiators can form free radicals upon exposure to actinic radiation (e.g., through photolytic degradation of the photo-initiator molecule). The free radicals can then utilize the ethylenically unsaturated chemical groups to form vinyl-based polymers. Additives can include but are not limited to pigments, dyes, UV absorbers, hindered amine light stabilizers, and fillers. Additives can be used to impart useful properties such as color, shelf stability, improved lifetime performance, higher UV stability, etc. Example 1 - Lip applicator FIG. 14 shows an example of a lip applicator having a flock-like surface in accordance with one or more embodiments of the present disclosure. A 3D-printed lip gloss applicator with a flocked stent to absorb more liquid and provide softer touch was produced using the systems and methods described herein. By using the point clouds from the surface of the stent of the lip gloss applicator, following the discretization of the stent mesh, the reference point of fiber can be defined. By assigning fiber features, the appearance and function of lip gloss can be designed. For example, by using these methods, flocking can be applied to irregular shapes of the stent, and the pointing direction of each fiber hair is selectively defined to ensure best absorption and release effects. Example 2 - Velcro FIG.15 shows an example of a Velcro (hook and loop adhesive) in accordance with one or more embodiments of the present disclosure. A velcro was produced having customizable locations on freeform surfaces with multiple fiber shapes to provide various adhesions. By introducing gradient orientations of the flock fibers, the velcro can achieve increased adhesion and easy separation properties in different directions. In addition to loops, the fibers may include lines, feathers, or flaps. Example 3 - Vibratory conveying surface FIG.16 shows an example of a surface for vibratory conveyance in accordance with one or more embodiments of the present disclosure. A dense flocking was produced on a lattice to transfer objects through vibrated hairs. By parametric morphing element size, fiber section profile and its orientation, the brush can provide holistic vibrations to move parts in desired path. Example 4 - Mascara brush FIG. 17 shows an example of mascara applicator having a flock-like surface in accordance with one or more embodiments of the present disclosure. The above-described embodiments can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. It should be appreciated that any component or collection of components that perform the functions described above can be generically considered as one or more controllers that control the above-discussed functions. The one or more controllers can be implemented in numerous ways, such as with dedicated hardware or with one or more processors programmed using microcode or software to perform the functions recited above. In this respect, it should be appreciated that one implementation of the embodiments of the present techniques comprises at least one non-transitory computer-readable storage medium (e.g., a computer memory, a portable memory, a compact disk, etc.) encoded with a computer program (i.e., a plurality of instructions), which, when executed on a processor, performs the above-discussed functions of the embodiments of the present techniques. The computer-readable storage medium can be transportable such that the program stored thereon can be loaded onto any computer resource to implement the aspects of the present techniques discussed herein. In addition, it should be appreciated that the reference to a computer program which, when executed, performs the above-discussed functions, is not limited to an application program running on a host computer. Rather, the term computer program is used herein in a generic sense to reference any type of computer code (e.g., software or microcode) that can be employed to program a processor to implement the above-discussed aspects of the present techniques. Various aspects of the present techniques may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and are therefore not limited in their application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Also, embodiments of the techniques may be implemented as one or more methods, of which an example has been provided. The acts performed as part of the method(s) may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed. Such terms are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term). The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing”, “involving”, and variations thereof, is meant to encompass the items listed thereafter and additional items. Having described several embodiments of the disclosure in detail, various modifications and improvements will readily occur to those skilled in the art. Such modifications and improvements are intended to be within the spirit and scope of the disclosure. Accordingly, the foregoing description is by way of example only, and is not intended as limiting. The scope is defined by the following claims and the equivalents thereto.

Claims

CLAIMS What is claimed is:

1. A method for producing an article to be 3D-printed having a flock-like surface, the method comprising: a. providing a geometric model of the article to be 3D-printed; b. generating a point cloud associated with a surface of the article; c. sampling the point cloud to provide a plurality of fiber reference points; d. adding fibers to the geometric model associated with the plurality of fiber reference points; and e. assigning fiber features to the fibers in the geometric model.

2. The method of claim 1, further comprising rendering the geometric model into instructions suitable for controlling a 3D printer to produce the article having the fibers.

3. The method of claim 2, further comprising executing the instructions to produce the article having the fibers.

4. The method of claim 1, wherein the point cloud is generated using surface discretization.

5. The method of claim 1, wherein the fiber features are assigned by parametric morphing.

6. The method of claim 1, wherein the fiber features include length, thickness, density, orientation, and shape.

7. The method of claim 1, wherein only a portion of the surface of the article comprises a point cloud and / or fiber reference points.

8. The method of claim 1, wherein the fibers are formed from a same material and are contiguous with the article.

9. The method of claim 1, wherein the fibers comprise lines, loops, feathers, or flaps.

10. An article produced by the method of claim 1.

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