Method and system for printing graded materials by roller deposition of multiple powders

Abstract

The present invention provides, according to various aspects of the embodiments, a method and system for horizontally placing two or more powders with a certain precision to build multi-material functional hierarchical components using a roller deposition process. Instead of formulating a liquid ink by dispersing powder feedstock (metal or ceramic) in some binder-solvent mixture, the use of two different types of fluids that are digitally deposited on the roller surface is described in detail. The two different types of fluids produce "wetting pixels" that can then capture a specific powder type that has an affinity only for that fluid. Alternatives are also provided, such as electrostatics, electrophotography, etc., to be used exclusively or in conjunction with fluids to create affinity pixels for specific powder types.

Description

Technical Field

[0001] The present disclosure relates to manufacturing heterogeneous materials of various specifications, and more particularly to manufacturing such materials by roll deposition of various powders. Background Art

[0002] Additive manufacturing, also known as three-dimensional (3D) printing, allows for the formation of three-dimensional objects by depositing the desired material or materials in successive layers. Prior to printing, materials are stored in one or more reservoirs of a 3D printer and extruded through one or more heads of the printer, which move to extrude the desired material at different points in the layer while moving along a predetermined path. While extrusion is relatively simple when the material stored in the reservoir is extruded from one of the print heads in an isolated form, extrusion becomes more complex when 3D printing or similar fused deposition modeling ("FDM") must be used to create functionally graded materials ("FGMs"). FGMs are composites of two or more input materials whose concentrations vary in different parts of the FGM, where the parts have properties that are a mixture of the properties of the input materials, where these properties depend on the relative amounts of the input materials within the respective parts. Examples of functionally graded material properties include organic structures, such as muscle tissue that smoothly transitions into a tendon to allow for a strong bond with strain relief when attached to rigid bone. Similarly, in 3D printing, the ability to fabricate FGMs allows for the creation of highly optimized part designs aimed at meeting overall performance requirements such as weight, elasticity in specific directions, and stiffness in other directions.

[0003] Creating an FGM requires mixing two or more input materials in the desired proportions within a 3D printer and then extruding the mixture at the point where the FGM in that proportion is desired. This mixing occurs in a chamber within the printer, into which the input materials are supplied from a storage reservoir, and from which the mixture is extruded through a print head. The composition of the mixture within the mixing chamber can only change at a certain rate, which depends both on the characteristics of the printer and on the initial composition of the mixture, and the print head is limited by this rate of change and cannot extrude a mixture of a particular composition. Therefore, if the intended path of the extruder head requires the extruder head to extrude a mixture of a composition that is incompatible with the rate of change, the print head will not be able to comply with the extrusion command and will not be able to properly print the FGM without purging the contents of the mixing chamber. Not only does this purge significantly slow down the printing process, it also wastes material in the mixing chamber.

[0004] The existing technology is characterized by a combination of micro-mixing and extrusion, and there are still several issues that must be resolved, such as the ability to handle high viscosity inks, the ability to perform dynamic mixing to change gradients, and the ability to process completion speed. For these reasons, there is a need in the art to manufacture 3D parts with graded material properties, with the possibility of gradient resolution of particle size in one dimension (z) and gradient resolution of linear order of particle size in the other two directions (x, y). Summary of the invention

[0005] According to various aspects of the embodiments, methods and systems are provided for horizontally placing two or more powders with a certain precision using a roller deposition process to build multi-material functional hierarchical components. Instead of preparing a liquid ink by dispersing a powder feedstock (metal or ceramic) in some binder-solvent mixture, the use of two different types of fluids deposited digitally on the roller surface is described in detail. The two different types of fluids produce "wetting pixels" that can then capture a specific powder type that has an affinity only for that fluid. Alternatives are also provided, such as electrostatics, electrophotography, etc., to be used exclusively or in conjunction with fluids to create affinity pixels for a specific powder type. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various exemplary embodiments of the disclosed apparatus, mechanisms and methods will be described in detail with reference to the following drawings, wherein like reference numerals represent similar or identical elements, and:

[0007] Figure 1 A schematic diagram of a prior art system for changing the composition of an extrudable material mixture according to the characteristics of a 3D printer;

[0008] Figure 2 is a schematic diagram of a roller deposition system for multiple powders that can be used to manufacture 3D parts according to one embodiment;

[0009] Figure 3 shows a method of forming a plurality of substrates with different materials according to an embodiment. Figure 1 Rollers and build platforms;

[0010] Figure 4A shows a 2D representation of the roller surface after inducing two affinity treatments, and Figure 4B is shown a particle having an affinity for an applied treatment according to one embodiment;

[0011] Figure 5A and Figure 5B The support material is shown introduced by inkjet deposition of a solidified liquid wax (5A) or by scraping off a carrier powder material (5B) according to one embodiment;

[0012] Figure 6shows xy placement of adhesive and deposition of two materials using roll deposition to build subsequent layers on top of a first layer according to one embodiment;

[0013] Figure 7 is a flow chart illustrating the operation of a method of manufacturing a stratified graded material according to one embodiment; and

[0014] Figure 8 Flowchart showing a method for inducing affinity of powder type to specific pixels in a roller based on the environment. DETAILED DESCRIPTION

[0015] Provided below are illustrative examples of the apparatus, system and method disclosed herein. The embodiments of the apparatus, system and method may include any one or more of the examples described below and any combination thereof. However, the present invention may be implemented in many different forms and should not be construed as being limited to the embodiments set forth below. On the contrary, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Therefore, the exemplary embodiments are intended to cover all substitutions, modifications and equivalents that may be included in the spirit and scope of the apparatus, mechanism and method described herein.

[0016] In one aspect, a method for manufacturing a layered graded material comprises: treating selected areas of a roller surface to induce an affinity of a powder type for specific pixels on the roller surface; running the roller surface over one or more powder beds after the treatment so that particles are transferred only to the treated selected areas of the roller surface, thereby causing the powder to adhere to the selected areas of the roller surface; wherein the one or more powder beds have a powder feedstock whose affinity is specific to the treated selected areas of the roller surface; and manufacturing the graded material layer by layer by depositing the powder on the roller surface onto a substrate.

[0017] In another aspect, in the method, wherein the treatment of the selected area is selected from the group consisting of fluid, electrostatic, electrophotographic, or combinations thereof.

[0018] In another aspect, the method further provides at least one reservoir for supplying fluid to the plurality of print heads.

[0019] In yet another aspect, in the method, wherein processing further comprises actuating at least one printhead of a plurality of printheads in communication with the at least one reservoir to deposit at least one of the defined volumes of fluids on selected areas of the roller surface.

[0020] In yet another aspect, in the method, the deposited fluid from at least one of the fluids causes an area of ​​the roller surface to have an affinity for a particular type of particles in one or more powder beds.

[0021] In yet another aspect, wherein when more than one powder bed is used the treatment of the selected areas is performed sequentially or simultaneously.

[0022] In another aspect, the powder feedstock is selected from the group consisting of metals, ceramics, alloys, low temperature alloys, high temperature alloys, non-metals, polymers, composites, and mixtures thereof that allow the powder to be deposited on a substrate.

[0023] In another aspect, the method further includes applying energy to selected areas of the roller surface to release the powder particles onto the substrate.

[0024] In yet another aspect, the support material is also applied in a layer-by-layer manner according to a pattern defined for supporting the graded material during the manufacturing process, wherein the layers of support material are applied after forming corresponding powder layers on the substrate.

[0025] In another aspect, the applied energy causes the fluid on selected areas of the roller surface to evaporate, thereby releasing the powder particles.

[0026] On the other hand, a system for manufacturing an object includes a processing subsystem for processing selected areas of a roller surface to cause an affinity of a powder type to specific pixels on the roller surface; a processor coupled to a storage device having instructions that, when executed by the processor, cause the processor to perform a method for manufacturing a layered, graded material by: running the roller surface on one or more powder beds after processing so that particles are transferred only to the treated selected areas of the roller surface, thereby causing the powder to adhere to the selected areas of the roller surface; wherein the one or more powder beds have a powder feedstock whose affinity is specific to the treated selected areas of the roller surface; and manufacturing the graded material layer by layer by depositing the powder on the roller surface onto a substrate.

[0027] It is noted at the outset that descriptions of well-known starting materials, processing techniques, components, equipment, and other well-known details may be only summarized or omitted so as not to unnecessarily obscure the details of the present disclosure. Therefore, where the details are otherwise well-known, we leave it to the application of the present disclosure to suggest or dictate choices regarding those details. The accompanying drawings show various examples related to embodiments of illustrative methods, apparatus, and systems for printing and using an inline air bearing heater after applying a surface coating on a recording medium.

[0028] When any numerical range of values ​​is mentioned herein, such ranges are understood to include every number and / or fraction between the minimum and maximum values ​​of the range. For example, the range 0.5-6% will explicitly include the endpoints 0.5% and 6%, plus all intermediate values ​​0.6%, 0.7% and 0.9%, up to and including 5.95%, 5.97% and 5.99%. Unless the context clearly indicates otherwise, the same applies to each other numerical property and / or element range set forth herein.

[0029] The modifier "about" used in conjunction with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes at least the degree of error associated with measurement of the particular quantity). When used with a particular value, it should be considered to disclose that value as well. For example, the term "about 2" also discloses the value "2", and the range "about 2 to about 4" also discloses the range "2 to 4".

[0030] As used herein, the term "affinity" refers to a liquid, charge or electrophotographic pixel that specifically binds to a target particle or target molecule in a powder bed. It is well known in the art that an affinity does not necessarily bind completely to its target particle, but generally interacts with a defined portion thereof.

[0031] "Hierarchical materials" are materials with structures spanning length scales of multiple orders of magnitude. "Graded materials" are materials with continuous and smooth spatial gradients of composition. "Digital materials" have controlled spatial composition and form, i.e., the spatial composition is two planar 2D dimensions (XY) and Z dimensions that form 3D. The unit of digital materials is the voxel, which is a three-dimensional droplet or characteristic volume of a material. "Multi-material composites" are materials composed of suspended materials and dispersed reinforcement materials, where the suspended materials can be metals, ceramics or polymers, also known as matrices, and the dispersed reinforcement materials can be continuous phases or discontinuous phases, also known as fillers or reinforcement materials. The reinforcement materials can be composed of colloidal clays, carbon nanotubes or macro additives such as carbon fibers or ceramic sheets.

[0032] As used herein, the term "printing device" or "printer" encompasses any device that performs a printout function for the purpose of solid freeform fabrication ("SFF"), which encompasses a class of manufacturing methods that allow three-dimensional structures to be manufactured directly from computer-aided design ("CAD") data. SFF processes are typically additive because materials are selectively deposited to construct a product rather than removed from a block or billet. Almost arbitrary product geometries can be achieved with SFF, no machining is required, mating parts and fully assembled mechanisms can be manufactured in a single step, and multiple materials can be combined, allowing functionally graded material properties. As used herein, printers include 3D printers that can manufacture 3D objects, etc., such as functionally graded material ("FGM") printers, fused deposition modeling ("FDM") printers, and stereolithography ("SLA") printers. It should be understood that the structures depicted in the accompanying drawings may include additional features that are not depicted for simplicity, and the depicted structures may be removed or modified.

[0033] The term "controller" is generally used herein to describe various devices related to the operation of one or more devices of a process or machine that directs or regulates. A controller may be implemented in a variety of ways (e.g., such as by dedicated hardware) to perform the various functions discussed herein. A "processor" is an example of a controller that employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform the various functions discussed herein. A controller can be implemented with or without a processor, and can be implemented as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuits) for performing other functions. Examples of controller components that can be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0034] Examples also include at least one machine-readable medium, which includes a plurality of instructions for implementing or executing the method disclosed herein when executed on a computing device. Such computer-readable media can be any available medium that can be accessed by a general or special-purpose computer. By way of example and not for limiting purposes, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of computer-executable instructions or data structures. When information is transferred or provided to a computer via a network or another communication connection (hardwired, wireless or a combination thereof), the computer correctly regards the connection as a computer-readable medium. Therefore, any such connection is correctly referred to as a computer-readable medium. The above combination should also be included in the scope of computer-readable media.

[0035] Computer executable instructions include, for example, instructions and data that cause a general-purpose computer, a special-purpose computer, or a special-purpose processing device to perform certain functions or a set of functions. Computer executable instructions also include program modules executed by a computer in a stand-alone or network environment. Typically, program modules include routines, programs, objects, components, and data structures that perform specific tasks or implement specific abstract data types. In additive manufacturing, examples of these modules may include one or more roller modules for operating rollers to follow a desired sequence, a manufacturing module for depositing materials on a substrate or a building platform, an applicator module, an actuator module for causing a print head to deposit materials in a specific sequence, and an energy applicator module. Computer executable instructions, associated data structures, and program modules represent examples of program code devices for executing the steps of the method disclosed herein. A specific sequence of such executable instructions or associated data structures represents an example of a corresponding action for implementing the functions described therein.

[0036] Although embodiments of the invention are not limited in this respect, discussions utilizing terms such as “process,” “compute,” “arithmetic,” “determine,” “use,” “create,” “analyze,” “examine,” and the like may refer to one or more operations and / or one or more processes of a computer, computing platform, computing system, or other electronic computing device that manipulates and / or transforms data represented as physical (e.g., electronic) quantities within a computer's registers and / or memory into other data similarly represented as physical quantities within a computer's registers and / or memory or other information storage medium that may store instructions to perform the operations and / or processes.

[0037] The embodiments of roller deposition to be described can be used to make graded materials, particularly graded materials for metal-ceramic, metal-metal and ceramic-ceramic composites, which are typically made in a non-digital manner and are not based on 3D printing. Using the present invention, the manufactured 3D objects will have the desired geometry (a beneficial effect of 3D printing) and have digital gradients, that is, pixel by pixel, designed to fit the intended geometry. In addition, roller deposition also provides material gradient resolution up to the powder size scale in z and some powder sizes in x and y (about 2-5x).

[0038] In describing an embodiment of the present invention, the same parts as those in the previously described embodiment are denoted by the same reference numerals, and the description of the same parts as those in the previous embodiment will be omitted.

[0039] Figure 1 A schematic diagram of a prior art system for changing the composition of an extrudable material mixture according to the characteristics of a 3D printer.

[0040] The prior art system 10 shown is heavily dependent on the rate of change of composition of the material mixture that can be extruded according to the characteristics of the 3D printer. This dependency makes it difficult to perform mixing on the fly and to determine a reliable solution. Two storage reservoirs 31, 32 hold two different input materials, designated as material A and material B. The reservoirs 31, 32 are connected to a mixing chamber 33, where the input materials can be mixed, and the output material is supplied from the mixing chamber to a print head 34 for extrusion printing of the part. Extrusion printing of parts has several issues, such as the inability to handle high viscosity inks, which have significant pressure requirements for printing at small part resolutions (e.g., 100 micron diameter tracks); the challenges of running mixing where the mixture can easily change gradients (i.e., switching from 100% A to 100% B) in the span of a few voxels; the inability to predictably determine the minimum achievable gradient resolution (i.e., 49%, 50%, 51% vs. 49.5%, 50%, 50.5%) in the context of a voxel; and most importantly, there is an inherent tradeoff between print resolution and print speed, with the upper limit of print speed matching the upper limit of fused deposition modeling (FDM) printers. The upper limit of print speed is inherent in all continuous, point deposition-based 3D printing processes. In addition, depending on the specifics of the extruder system, the minimum addressable volume can be large. In some screw conveyor based displacement systems, this minimum addressable volume corresponding to the floor voxel size for defining the composition gradient can be anywhere in the range of 0.5 microliters to 5 microliters, which translates to a cube with dimensions of 0.79 mm to 1.71 mm on each side. This is quite large compared to powder sizes that are between 1 micron and 100 microns in diameter.

[0041] Figure 2 Schematic diagram of a roller deposition system for multiple powders that can be used to make 3D parts according to one embodiment.

[0042] The system shown includes a roller 330, a processing subsystem including an inkjet head 310 and an exposure device 320 that is non-fluid, a controller 120, a powder bed (340, 345) having a raw material having an affinity for specific pixels in the roller as induced by the processing subsystem, and a build platform 360 such as a substrate for layer-by-layer growth manufacturing.

[0043] The inkjet head 310 can deposit multiple (e.g., two or more) fluids simultaneously without changing the fluids. The important beneficial effect of inkjet for fluid deposition is the high resolution (up to the scale of powder feed) or high resolution of material gradients, especially when the processing function depends on the materials produced in the form of thin films. The very small volume (e.g., picoliter) that can be achieved with inkjet droplets is particularly suitable for this. The inkjet droplets of multiple fluids ejected into the same position will react very quickly, thereby allowing local control of chemical reactions or physical interactions (e.g., wetting) within the deposited material, thereby allowing very small-scale structuring of chemical activity, wetting and other resulting material properties to affinity specific raw materials. The inkjet head 310 can dispense droplets with a limited volume of at least one fluid or these two fluids of 2 picoliters to 50 picoliters on the selected area of ​​the roller surface 330. The high resolution and point-by-point deposition of materials allow the actual realization of structures (such as linear features of their materials that vary with length, or multi-material lattices), making the products of inkjet tools at least complementary to those products that can be achieved by flow-type deposition tools such as extrusion / syringe tools.

[0044] return Figure 2 , this embodiment shows the use of a roll deposition process to place two or more powders with a certain degree of precision to build a multi-material functional graded component at a substrate such as a build platform 360. Instead of preparing a liquid ink by dispersing a powder feedstock (metal or ceramic) in some binder-solvent mixture for use as Figure 1 In the printing system shown, Figure 2 The illustrated embodiment shows the use of roller 330 to place powder directly onto the build platform.

[0045] The idea is to use two different types of induced affinity to the fluid by treating the roller, and then for each "wetting pixel" capture a specific powder type that has an affinity only for that fluid. To make the powder adhere to the roller surface (330) at the selected part, the embodiment will spray (310) a defined volume of fluid onto the roller surface, or in the alternative use an exposure device 320 that will cause temporary powder adhesion to the roller surface when the roller runs (330p1, 330p2) on the powder bed (340, 345). In the release step, an energy device 363 can be used to force any liquid to evaporate, thereby releasing the powder particles into the build platform 360 or substrate. The powder already in the build platform 360 may or may not be wetted with the same liquid or a different liquid such as an adhesive to subsequently allow the powder particles to be transferred between the roller and the build platform. In order to achieve functional grading using two or more different powders such as a powder bed 340 and a power bed 345, the system can inkjet two or more different fluids whose affinity is specific to the powder raw materials. In the main embodiment, this can be a hydrophilic liquid and a hydrophobic liquid that can be designed to attract or adhere to bare metal / ceramic particles (hydrophilic) or wax or polymer covered metal / ceramic particles (hydrophobic). Such powder feedstocks (340, 345) can be used in conventional metal and ceramic manufacturing processes. For example, wax or polymer covered metal particles are commonly used in metal injection molding. The intended process is then to inkjet (310) the two fluids sequentially or simultaneously onto the roller surface 330 (forming a pixel map of the intended multi-material or hierarchical structure within the layer), and then running the roller 330 sequentially into the two powder beds (340, 345) to allow the two powder types to adhere to the roller. These powders are then all transferred 365 to the build platform 360 using the instructions in the manufacturing module to manufacture the part in a layer-by-layer manner. The supporting material can be introduced by inkjet deposition of solidified liquid wax or by scraping off the supporting powder material, as shown in Figures 5a to 5b and Figure 6 As shown. These support materials can be designed to burn out during post-printing sintering, melt at high temperatures, or be removed by de-powdering. For a powder (365) having an average diameter of 10 microns, the disclosed embodiments can achieve an xy placement resolution on the order of 20 microns to 50 microns (rough area covered by inkjet droplets on some compatible substrates) and a z placement resolution on the order of 10 microns (average diameter size). Both of these dimensions are at least an order of magnitude smaller than the size of a cubic voxel corresponding to the minimum addressable volume of some paste extrusion systems, which can be as large as 0.79 mm to 1.71 mm.

[0046] The exemplary control system 120 may include one or more local processors 124 for independently operating the exemplary control system 120 and for implementing control and operating functions for additive manufacturing (“AM”) 3D object formation (e.g., fabrication using graded materials), and specifically for implementing fluid, electronic, or electrophotographic pixel formation schemes. The one or more processors 124 may include at least one conventional processor or microprocessor that interprets and executes instructions that direct the specific functions of the exemplary control system 120, and controls the AM 3D object formation process with the exemplary control system 120.

[0047] The exemplary control system 120 may include one or more data storage devices 122. One or more such data storage devices 122 may be used to store data or operating programs to be used by the exemplary control system 120 (specifically, one or more processors 122). The one or more data storage devices 122 may be used to store information about, for example, one or more 3D object models used to generate 3D objects in an AM 3D object forming device associated with the exemplary control system 120. The stored 3D object model information may be converted into data for printing a series of 2D slices (which may be used to create a pixel image on the surface of the roller 330) for forming a 3D object in the manner generally described above with respect to the build platform 360. The data storage device 122 may include a random access memory (RAM) or another type of dynamic storage device capable of storing updateable database information, as well as for storing instructions for performing system operations separately by, for example, the processor 124.

[0048] In the depicted embodiment, the roller 330 rotates clockwise 335 and starts with a clean surface. Disposed at the first location of the processing subsystem is a fluid type device 310 that ejects a fluid having an affinity for a particular powder type and forms an image thereon. The fluid type device as shown is one or more inkjet print heads that uniformly wet a selected portion of the roller surface with one or more fluids, such as Figure 4A The pixels shown are arranged to form a layer with uniform and controllable thickness and to cause a specific powder to adhere to its surface at selected locations. In this way, the fluids can be paired by spraying two or more different fluids whose affinity is specific to the powder feedstock. Sensors (not shown), such as in-situ non-contact laser gloss sensors or laser contrast sensors, can be used to confirm the uniformity and location of the layer. Figure 3 An isometric view of a roller having different materials according to one embodiment is shown.

[0049] Other forms of image creation and methods of causing powder type affinity for specific pixels in roller 330 that do not use fluid: for example, electrostatic, electrophotographic, etc. The same fluid-powder pairing method can be used for a first material based on fluid and a second material based on electrophotography or electrostatic. Well-known exposure devices 320 for generating pixel images include: a raster output scanner (ROS) that irradiates a charged portion of the outer surface of roller 330 to record a first electrostatic latent image thereon; a light emitting diode (LED) print head that emits irradiated exposure light or other electrostatic interactions with induced negative charges placed on roller 330 by using a corona discharge mechanism that recharges to a relatively high, substantially uniform potential or similar mechanisms.

[0050] Figure 3 A view of a roller with different materials is shown according to one embodiment. In the illustrated embodiment, roller 330 is shown in this illustration as rotating counterclockwise 335 to place a first type of particles 410 and a second type of particles 420 on a building platform such as substrate 360. As shown, the particles can be spread anywhere on the surface of roller 330 and gradually used to build a manufactured part.

[0051] Figure 4A shows a 2D representation of the roller surface after inducing two affinity treatments, and Figure 4B Particles having an affinity for an applied treatment are shown in FIG. 1 according to one embodiment. Figure 4A 2D representation of a selected area of ​​the roller 330. The selected area details the use of two different types of fluids (or charged pixels) to be digitally deposited sequentially or simultaneously on the 2D roller surface. The idea of ​​having two different types of fluids / charges is that for each "wet pixel" or charged pixel, then a specific powder type is captured that has an affinity only for that fluid or charged space. Figure 4A The pixel may have a first affinity treatment (AT1) and a second affinity treatment (AT2). Such induced affinity may be of a type selected from the group consisting of fluid, electrostatic, electrophotographic, or a combination thereof. Generally, the wetted pixels are designed to attract or adhere to bare metal / ceramic particles (hydrophilic) or wax-coated or polymer-coated metal / ceramic particles (hydrophobic) in a powder bed. Figure 4B Particles that are attractive to the applied induced affinities AT1 and AT2 are shown. Roller 330 is labeled 330B to indicate that the powder particles (450) attach to the surface of the roller based on their respective affinities.

[0052] Figure 5A and Figure 5B A solidified liquid wax (5A) is shown by inkjet deposition or by scraping off a carrier powder material ( Figure 5B) to introduce an exemplary support material. The material applied is a separate sacrificial support material. The role of the support material in the 3D printer is to provide a platform for overhanging geometries on subsequent layers in a bottom-up, layer-by-layer manufacturing process; weakly solidified materials that can be washed off or dissolved are generally used as supports. Related methods use wax as a support material; the wax hardens quickly after deposition and melts away in a post-processing purge step. As used herein, "support" refers to a material that can meet the structural requirements and is easily removed at the same time. Examples include polymer powders such as polyvinyl alcohol, polylactic acid, waxes with a defined melting temperature, loose powder materials, salts, other water-soluble or organic solvent-soluble powder raw materials, etc. The support material can be introduced by inkjet deposition 312 of solidified 510 liquid wax 505 or by scraping 520 support powder material 535 or a substrate or previously formed powder slice at the build platform 360. In the case where the support material is to be scraped off 520, the support material will be composed of a powder having an average particle size lower than the average particle size of the main raw material to facilitate easy scraping. For example, for an average particle size of 10 microns for metal or ceramic powders, the scraping material may be composed of wax or polymer particles with an average particle size of 1 to 3 microns. These support materials may be designed to burn out during post-print sintering, melt at high temperatures, or be removed by de-powdering.

[0053] It should be understood that planarization of the deposited layer can be performed in some embodiments before depositing another layer. In the case of using a support material, the planarization process can be performed after the introduction of the support material, or simply after the complete deposition of the layer but before the deposition of the subsequent layer. Planarization establishes a flat surface on which the subsequent layer will be deposited, and is necessary to remove protruding irregular features that can cause leveling and other printing defects of the subsequent layer. These prominent, irregular features may be due to the placement of the powder raw material, the inherent size dispersion of the powder raw material (e.g., large particles or lumps), or the introduction of the carrier material. Planarization may include running a heavy roller to compact the deposited surface and planarize it, or running a sharp edge or a scraper along the surface at an expected height to remove protruding loose feature structures above a certain gap spacing. In the case of a wax or some other heated powder as the support material, planarization can be applied during the wax is fully warm and melted, and the action of the running roller or scraper applies the liquid level of the molten material to the specified gap.

[0054] Figure 6Shown is a blanket deposition of an adhesive material across the entire build of two materials and selective xy placement using roller deposition on top of a pre-existing layer including a support according to one embodiment. In this embodiment, the system and method deposits adhesive 610 on the entire build plate 360 ​​to facilitate the step of transferring a new powder layer 620 from a roller 330 to a pre-existing powder layer 602. In this illustration, an adhesive applicator 312 may be positioned to supply adhesive to a substrate 360 ​​(or the top of a layer 602 thereon) before the transfer step. Such adhesive 610 facilitates the transfer of a layer 630 from a roller 330 to a layer of pre-existing powder 602 such as on a substrate 360 ​​or a build platform. The adhesive 610 applied by the applicator 312 may be any commercially available adhesive product selected not to affect the support 510 or the powder material 365, and may be applied by spraying, rolling, brushing, etc. The binder 610 itself can be a polymer material, such as commercially available epoxies and other fast curing materials, or it can be an inert liquid, such as water, silicone, or mineral oil, which has a general affinity for all of the different powder materials 365, and where this affinity causes the powder to be transferred from the roll to the part. The binder 610 can be removed during post-print sintering or during other finishing processes. Methods for removing the binder along with any support materials used can include heating (such as a furnace or oven), mechanical means (such as vibration), chemicals (such as mineral oil or alcohol baths) to selectively dissolve the binder and / or the support.

[0055] A 3D printer using a print head such as 312 can deposit one or more cured and non-cured (e.g., adhesive) regions within build platform 360. Roller 330 can then deposit the same as described in reference to FIG. Figure 2 Another layer of powder 620 is shown deposited on the binder structure 610. The deposited binder structure 610 is shown sandwiched between the newly deposited material 630 and the previous layer 602 providing a bond between the layers.

[0056] In operation, roller 330 deposits raw materials by moving the roller along a determined path onto substrate 360 ​​to manufacture a 3D object. Typically, the manufacture of a product is performed by layered deposition of raw materials. This planar layered deposition method for graded material manufacturing enables the placement of multiple powders to create material composition gradients within a 3D object at a higher resolution than currently achieved through methods that rely on micro-mixing and extrusion ( Figure 1 ). The roller method should be able to place particles with a resolution that is on the order of the particle size in the z direction and a linear factor of the particle size in the xy direction. For example, for an average particle size of about 10 microns, this would correspond to an addressable voxel size of about 10 microns (z) x 50 microns (y) x 50 microns (x). This corresponds to 25,000 cubic microns or 2.5x10 -5This is orders of magnitude smaller than the addressable voxel size of about 0.5 μl to 5 μl in some extrusion-based systems, without taking into account the minimum dead volume required for mixing, which imposes different constraints on the material gradients that can be manufactured.

[0057] Methods 700 and 720 describe in detail the process of using a roller to digitally deposit multiple powder types onto a substrate such as a build platform 360 to build a 3D object. The inkjet head 310 and / or exposure device 320 will expose the roller 330 to record an image of a pixel map representing the desired multi-material or hierarchical structure. One image has an affinity for a certain type of building material, another image has an affinity for another type of material, and so on. These images are then transferred to a build platform 360 similar to the substrate and continuously registered with each other to form a hierarchical structure or 3D part.

[0058] Figure 7 Flowchart showing the operation of a method 700 for manufacturing a stratified graded material according to one embodiment. The method 700 begins at action 710, where an event such as system initialization or similar to pressing a start button to manufacture / produce a part or object. For example, a manufacturer of metal and ceramic parts for various applications: aerospace, automotive, biomedical, energy, and other functional uses. Control then passes to action 720, where the method 700 processes a selected area of ​​a roller surface such as roller 330 to induce an affinity of a powder type for a specific pixel. Figure 4A is an example of a selected area that has been adapted for different fluid types. Control is then passed to action 740, where roller 330 runs / rotates on a bed having material feedstock A. In action 750, roller 330 runs on a bed having material feedstock B. In actions 740 and 750, controller 120 using a roller module transmits a rotation signal or command to a mechanism such as an electric motor, causing roller 330 to rotate. In a similar manner, controller 120 using a program module can command another mechanism or a motor having a cam and gear to position roller 330 at a selected location, such as at a powder bed 340, 345 or at a build platform 360, to pick up an affinity material and deliver / deposit the material attached to its surface.

[0059] After the rollers are moved over the powder bed (340, 345), control is then passed to action 760 to move the rollers 330 over the build bed 360 or substrate to deposit slices of graded material. This process is repeated until the object is manufactured layer by layer. In action 780, the rollers are cleaned using well-known methods, such as heating, such as by IR lamp irradiation, chemicals, solvents, shaking, or application of electric fields, such as those produced by corona discharge devices. Cleaning 780 may be performed between layers, after a sequence of layers, and / or after all layers have been deposited by the rollers 330. Note that the actions described in 760 include processes for depositing multiple powders that occur within the actions of the main rollers. Once the multi-material powder layers have been transferred to the construct, the previously described support and binder material deposition processes (Figures 5, 7) may be performed prior to action 710 for depositing subsequent layers, and then prior to 720. Figure 6 ).

[0060] Figure 8 Flowchart showing method 720 of causing a powder type to have an affinity for a particular pixel in a roller according to circumstances. Method 720 begins with action 722, in which an affinity for a power type is selected. As described above, the affinity can take the form of a fluid type or a charged type, and the two types can be combined on the surface of roller 330. When manufacturing an object, two different types of materials, such as two or more different fluid-powder pairs, where each powder raw material has a wetting affinity and does not have wettability to the other fluid, or other means are used to cause the particles to temporarily have an affinity for the roller surface - for example, electrophotography, etc. Although described as being applied to two different materials, method 722 can be extended from two fluid-powder pairs to multiple fluid-powder pairs, and to using a roller to digitally deposit multiple powder types on a substrate to build a 3D object.

[0061] In act 724 , a fluid-based affinity is induced to those pixels in the selected area of ​​the surface of roller 330 .

[0062] In act 726 , the method induces a non-fluid affinity, such as a static charge, in selected areas of the surface of the roller 330 .

[0063] In act 728, fluid and non-fluid methods are selected to induce affinity on a pixel-by-pixel basis. Then in act 724, act 726, or act 728, control passes to act 732 to attract the appropriate powder to obtain the selected affinity.

[0064] It should be understood that several of the above disclosed and other features and functions or their alternatives may be desirably combined into many other different systems or applications. Moreover, those skilled in the art may subsequently make various currently unforeseeable or unforeseen substitutions, modifications, changes or improvements therein.

Claims

1. A method for manufacturing a multi-material 3D object, the method comprising: treating selected areas of a roller surface to induce an affinity of a plurality of powder types for specific pixels on the roller surface, the treating comprising depositing a first fluid onto the roller surface and depositing a second fluid different from the first fluid onto the roller surface, each of the first fluid and the second fluid being an affinity type that induces an affinity for a respective one of a plurality of powder types, the plurality of powder types comprising powder particles of a first material and powder particles of a second material; causing the roller surface to run over one or more powder beds containing the plurality of powder types after treatment so that the first material powder particles are transferred only to the treated selected areas of the roller surface having one of the first fluid and the second fluid thereon, and causing the second material powder particles to be transferred only to the treated selected areas of the roller surface having the other of the first fluid and the second fluid thereon, thereby causing the plurality of powder types to adhere to the selected areas of the roller surface; wherein the first material powder particles and the second material powder particles each have an affinity that is specific to a treated selected area of ​​the roller surface having a corresponding one of the first fluid and the second fluid thereon; The multi-material 3D object is manufactured layer by layer by simultaneously depositing first material powder particles and second material powder particles from the roller surface onto a substrate.

2. The method of claim 1 , wherein causing the roller surface to run on one or more powder beds containing the plurality of powder types after processing comprises rolling the roller surface in an affinity type in direct contact with powder particles of a first material and powder particles of a second material when the powder particles are contained by the one or more powder beds.

3. The method according to claim 1, further comprising: The support material is applied in a layer-by-layer manner according to a pattern defined for supporting the multi-material 3D object during the manufacturing process, wherein the layers of support material are applied after forming a corresponding plurality of powder-type layers on the substrate.

4. The method according to claim 1, further comprising: An adhesive is supplied to the substrate, wherein the adhesive facilitates transfer of a plurality of powder types from the roller surface to the substrate or to a pre-existing layer of a plurality of powder types on the substrate.

5. The method of claim 1, wherein the process uses a first fluid and a second fluid from at least one reservoir, the at least one reservoir being adapted to supply the fluids to a plurality of print heads.

6. The method according to claim 5, further comprising: At least one of the plurality of printheads in communication with the at least one reservoir is actuated to deposit a defined volume of 2 picoliters to 50 picoliters of at least one of the first and second fluids on the selected area of ​​the roller surface.

7. The method of claim 1, wherein after processing the roller surface is run over one or more powder beds so that multiple powder types adhere to selected areas of the roller surface in a single pass of the roller surface over the one or more powder beds.

8. The method of claim 1, further comprising causing, via the processing, a plurality of powder types to simultaneously affinity to specific pixels on a roller surface.

9. The method of claim 1, wherein the first material powder particles and the second material powder particles are selected from the group consisting of metals, non-metals, and mixtures thereof that allow the powders to be deposited on the substrate.

10. The method according to claim 1, further comprising: supplying an adhesive to the substrate, the adhesive facilitating transfer of the plurality of powder types on the roller surface to the substrate or a pre-existing layer of the plurality of powder types on the substrate; The applied energy causes the fluid on selected areas of the roller surface to evaporate, thereby releasing powder particles of the first material and powder particles of the second material.

11. The method of claim 1 , further comprising forming a patterned layer of functionally graded material by simultaneously depositing first material powder particles and second material powder particles, the patterned layer of functionally graded material having a material gradient resolution at the size of the first material powder particles and the second material powder particles.

12. The method of claim 11 wherein the powder placement resolution is within the linear order of the average particle size: 10 microns to 1000 microns in xy and 1 micron to 100 microns in z, resulting in a compositionally addressable voxel volume of 5 picoliters to 100 picoliters.

13. The method according to claim 12, further comprising: depositing a support material in a layer-by-layer manner according to a pattern defined for supporting the functionally graded material during a manufacturing process, wherein the support material layer is applied after forming respective layers of first material powder particles and second material powder particles on the substrate; The just-applied layer, which can consist of a mixture of deposited powder particles of the first material, powder particles of the second material and carrier material, is planarized.

14. The method of claim 9, wherein the metal comprises a low temperature alloy and a high temperature alloy.

15. The method of claim 9, wherein the non-metal comprises a polymer and a ceramic.

16. A system for manufacturing a multi-material 3D object, the system comprising: a processing subsystem for processing selected areas of a roller surface to induce an affinity of a plurality of powder types for specific pixels on the roller surface, the processing comprising depositing a first fluid onto the roller surface and depositing a second fluid different from the first fluid onto the roller surface, each of the first fluid and the second fluid being an affinity type that induces an affinity for a corresponding one of a plurality of powder types, the plurality of powder types comprising powder particles of a first material and powder particles of a second material; one or more powder beds containing a plurality of powder types, wherein the first material powder particles and the second material powder particles each have an affinity that is specific to a treated selected area of ​​a roller surface having a respective one of the first fluid and the second fluid thereon; At least one processor configured to execute code, the at least one processor comprising: a roller module configured to cause the roller surface to run over the one or more powder beds after processing to transfer the first material powder particles only to the processed selected areas of the roller surface having one of the first fluid and the second fluid thereon, and to transfer the second material powder particles only to the processed selected areas of the roller surface having the other of the first fluid and the second fluid thereon, thereby causing the plurality of powder types to adhere to the selected areas of the roller surface; A manufacturing module is configured to simultaneously deposit first material powder particles and second material powder particles from the roller surface onto a substrate to manufacture the multi-material 3D object layer by layer.

17. The system of claim 16, wherein the roller module configured to operate the roller surface is further configured to roll the roller surface in an affinity type in direct contact with the first material powder particles and the second material powder particles when the powder particles are contained by one or more powder beds.

18. The system of claim 16, the processing subsystem further comprising at least one reservoir that supplies fluid to the plurality of print heads.

19. The system of claim 18, wherein the processor further comprises: An actuator module is configured to actuate at least one of the plurality of print heads in communication with the at least one reservoir for depositing a defined volume of 2 picoliters to 50 picoliters of at least one of the first and second fluids on the selected area of ​​the roller surface.

20. The system of claim 16, wherein the roller module is configured to operate the roller surface after processing on one or more powder beds so that the multiple powder types adhere to selected areas of the roller surface in a single pass of the roller surface over the one or more powder beds.

21. The system of claim 16, wherein a processing subsystem causes, via said processing, simultaneous affinity of multiple powder types to specific pixels on said roller surface.

22. The system of claim 16, wherein the first material powder particles and the second material powder particles are selected from the group consisting of metals, non-metals, and mixtures thereof that allow the powders to be deposited on the substrate.

23. The system of claim 16, wherein the fabrication module is further configured to form a patterned layer of a functionally graded material by simultaneously depositing first material powder particles and second material powder particles, the patterned layer of the functionally graded material having a material gradient resolution at the sizes of the first material powder particles and the second material powder particles, the processor further comprising: An applicator module is configured to deposit a support material in a layer-by-layer manner according to a pattern defined for supporting the functionally graded material during a manufacturing process, wherein the support material layers are applied after forming respective layers of first material powder particles and second material powder particles on the substrate.

24. The system of claim 23, wherein the applicator module is further configured to supply an adhesive to the substrate, the adhesive facilitating transfer of the plurality of powder types on the roller surface to the substrate or to a pre-existing layer of the plurality of powder types on the substrate; The processor also includes an energy applicator module configured to apply energy to selected areas of the roller surface and vaporize fluid on the selected areas of the roller surface, thereby releasing first material powder particles and second material powder particles.

25. The system of claim 22, wherein the metal comprises a low temperature alloy and a high temperature alloy.

26. The system of claim 22, wherein the non-metals include polymers and ceramics.

Images