Patent Application
20200001533
This invention relates to additive manufacturing and more particularly to additive manufacturing methods for creating layerless structures exploiting distributed localized field configurable selective techniques such as Selective Spatial Solidification (S3) and Selective Spatial Trapping (SST).
Ever since man began to fabricate things the dominant techniques over time have been those based upon selective material removal from a larger starting block of material. The exception being molding processes. Despite the evolution of tools over a few thousand years through the industrial revolution and a couple of hundred years of mechanization to the past few decades with computer numerical control (CNC) for increased precision the basic principle has remained the same. Namely, use something sharp and harder than the material being worked to remove it, leading to waste in not only the material employed but back through the supply chain to increased resources to get to that point.
However, during the past four decades a new trend of manufacturing has emerged, called additive manufacturing. In contrast to the old methods, additive manufacturing exploits materials that are added, commonly, layer by layer to form consecutive cross sections of the desired shape. Eliminating the waste is a significant advantage of additive manufacturing over subtractive manufacturing processes. Numerous methods have been utilized to implement the layer by layer material disposing within the prior art including laying photosensitive polymer and curing with UV focused beam, doctor blading a layer of metal powder and sintering by high power laser, or the deposition of melted polymer to shape the geometry. Such methodologies are depicted within the upper half of
However, as depicted within the lower half of
Over the past 30 years since the emergence of 3D printing and additive manufacturing (AM) concepts with their inherent layered process of solidification such processes have been very difficult and time consuming for building fully functional parts, especially metallic ones. In conventional laser assisted sintering AMs, structural imperfections arise by the method utilized to build up pixel-by-pixel layers which are therefore built in a non-continuous manner such that some inhomogeneity is inevitable. However, these voids and defect may potentially cause structural weakness by simply concentrating stress and initiating a fracture mechanism especially under dynamic loading. Further, poor surface quality through surface roughness is another drawback of aforementioned AM methods which may, independent of internal microstructure issues, trigger fatigue failure caused by surface crack propagation. In addition, warpage and deformation after solidification can significantly affect the final geometry of the part.
Within the prior art the importance of microstructure of parts was an issue and significant work has been directed to improving the mechanical properties of parts built by laser sintered AM. Laser scanning rate, laser power and layer thickness were investigated in order to optimize these processes. Despite these efforts, due to the layer-by-layer nature of the AM process, manufactured parts exhibit high porosity and as a result poor mechanical properties are obtained. Further, significant work within the prior art within the context of layer-by-layer AM has sought to address chronic issues such as warpage, curling, and porosity. For example, increased complexity such as heating cell mounted modular plates have been proposed to control the warpage and curling of parts by allowing the temperature of each cell to be independently controlled so that a localized temperature control system is implemented to selectively heat or cool each layer pixels to eventually achieve a less warped shape. However, very little prior art proposes novel AM methods that address these issues in a fundamentally different approach.
Examples of prior art techniques include exploiting electron beams to sinter the metal powder to achieve predefined surface topology, post process heat treatment processes, and laser processing. Laser frequency has been studied as it indirectly controls the microstructure of part via local temperature control. In other works secondary sintering is employed to reduce the porosity of the samples. However, despite this no prior art seeks to revamp the conventional layer-by-layer method such that all AM produced parts, especially metallic pieces, need excessive post processing operations to be functional.
More recently within the prior art the method of oxygen penetration assisted digital light processor (DLP) based AM has been demonstrated to provide decreased production time and improved mechanical properties for polymeric piece parts. The process exploits Continuous Liquid Interface Production (CLIP). However, the method can be only applied with polymers and still exploits cross section data of the designed parts.
Accordingly, it would be beneficial to provide AM processes that overcome these limitations within the prior art by providing parts formed with a layerless structure in contrast to prior art layer-by-layer 3D printed parts. Embodiments of the invention provide for parts that are sintered (in case of metal or ceramic powders) or polymerized and cured (in case of resin and polymers) in uniform and homogenous pattern resulting in homogenous structure and mechanical properties in comparison with parts manufactured by material removal or molding processes.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
It is an object of the present invention to mitigate limitations within the prior art relating to additive manufacturing and more particularly to develop additive manufacturing methods for creating layerless structures exploiting distributed localized field configurable selective techniques such as Selective Spatial Solidification (S3) and Selective Spatial Trapping (SST).
In accordance with an embodiment of the invention there is provided a system for forming three-dimensional (3D) structures comprising:
In accordance with an embodiment of the invention there is provided a method of forming three-dimensional (3D) structures comprising:
In accordance with an embodiment of the invention there are provided computer executable instructions stored upon a non-volatile non-transitory storage medium, the executable instructions when executed by a microprocessor executing a method comprising:
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:
The present invention is directed to additive manufacturing and more particularly to additive manufacturing methods for creating layerless structures exploiting distributed localized field configurable selective techniques such as Selective Spatial Solidification (S3) and Selective Spatial Trapping (SST).
The ensuing description provides representative embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the embodiment(s) will provide those skilled in the art with an enabling description for implementing an embodiment or embodiments of the invention. It being understood that various changes can be made in the function and arrangement of elements without departing from the spirit and scope as set forth in the appended claims. Accordingly, an embodiment is an example or implementation of the inventions and not the sole implementation. Various appearances of “one embodiment,” “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiments. Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention can also be implemented in a single embodiment or any combination of embodiments.
Reference in the specification to “one embodiment”, “an embodiment”, “some embodiments” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment, but not necessarily all embodiments, of the inventions. The phraseology and terminology employed herein is not to be construed as limiting but is for descriptive purpose only. It is to be understood that where the claims or specification refer to “a” or “an” element, such reference is not to be construed as there being only one of that element. It is to be understood that where the specification states that a component feature, structure, or characteristic “may”, “might”, “can” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.
Reference to terms such as “left”, “right”, “top”, “bottom”, “front” and “back” are intended for use in respect to the orientation of the particular feature, structure, or element within the figures depicting embodiments of the invention. It would be evident that such directional terminology with respect to the actual use of a device has no specific meaning as the device can be employed in a multiplicity of orientations by the user or users. Reference to terms “including”, “comprising”, “consisting” and grammatical variants thereof do not preclude the addition of one or more components, features, steps, integers or groups thereof and that the terms are not to be construed as specifying components, features, steps or integers. Likewise, the phrase “consisting essentially of”, and grammatical variants thereof, when used herein is not to be construed as excluding additional components, steps, features integers or groups thereof but rather that the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method. If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element.
An “application” (commonly referred to as an “app”) as used herein may refer to, but is not limited to, a “software application”, an element of a “software suite”, a computer program designed to allow an individual to perform an activity, a computer program designed to allow an electronic device to perform an activity, and a computer program designed to communicate with local and/or remote electronic devices. An application thus differs from an operating system (which runs a computer), a utility (which performs maintenance or general-purpose chores), and a programming tools (with which computer programs are created). Generally, within the following description with respect to embodiments of the invention an application is generally presented in respect of software permanently and/or temporarily installed upon a PED and/or FED.
“Electronic content” (also referred to as “content” or “digital content”) as used herein may refer to, but is not limited to, any type of content that exists in the form of digital data as stored, transmitted, received and/or converted wherein one or more of these steps may be analog although generally these steps will be digital. Forms of digital content include, but are not limited to, information that is digitally broadcast, streamed or contained in discrete files. Viewed narrowly, types of digital content include popular media types such as MP3, JPG, AVI, TIFF, AAC, TXT, RTF, HTML, XHTML, PDF, XLS, SVG, WMA, MP4, FLV, and PPT, for example, as well as others, see for example http://en.wikipedia.org/wiki/List of file formats. Within a broader approach digital content mat include any type of digital information, e.g. digitally updated weather forecast, a GPS map, an eBook, a photograph, a video, a Vine™, a blog posting, a Facebook™ posting, a Twitter™ tweet, online TV, etc. The digital content may be any digital data that is at least one of generated, selected, created, modified, and transmitted in response to a user request; said request may be a query, a search, a trigger, an alarm, and a message for example.
A “CAD model” as used herein may refer to, but is not limited to, an electronic file containing information relating to a component, piece-part, element, assembly to be manufactured. A CAD model may define an object within a two-dimensional (2D) space or a three-dimensional (3D) space and may in addition to defining the internal and/or external geometry and structure of the object include information relating to the material(s), process(es), dimensions, tolerances, etc. Within embodiments of the invention the CAD model may be generated and transmitted as electronic content to a system providing manufacturing according to one or more embodiments of the invention. Within other embodiments of the invention the CAD model may be derived based upon one or more items of electronic content directly, e.g. a 3D model may be created from a series of 2D images, or extracted from electronic content.
A “fluid” as used herein may refer to, but is not limited to, a substance that continually deforms (flows) under an applied shear stress. Fluids may include, but are not limited to, liquids, gases, plasmas, and some plastic solids.
A “powder” as used herein may refer to, but is not limited to, a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders may be defined by both a combination of the material or materials they are formed from and the particle dimensions such as minimum, maximum, distribution etc. A powder may typically refer to those granular materials that have fine grain sizes but may also include larger grain sizes depending upon the dimensions of the part being manufactured, the characteristics of the additive manufacturing system etc.
A “metal” as used herein may refer to, but is not limited to, a material having good electrical and thermal conductivity. Metals are generally malleable, fusible, and ductile. Metals as used herein may refer to elements, such as gold, silver, copper, aluminum, iron, etc. as well as alloys such as bronze, stainless steel, steel etc.
A “resin” as used herein may refer to, but is not limited to, a solid or highly viscous substance which is typically convertible into polymers. Resins may be plant-derived or synthetic in origin.
An “insulator” as used herein may refer to, but is not limited to, a material whose internal electric charges do not flow freely, and therefore make it nearly impossible to conduct an electric current under the influence of an electric field.
A “ceramic” as used herein may refer to, but is not limited to, an inorganic, nonmetallic solid material comprising metal, non-metal or metalloid atoms primarily held in ionic and covalent bonds. Such ceramics may be crystalline materials such as oxide, nitride or carbide materials, elements such as carbon or silicon, and non-crystalline.
A “polymer” as used herein may refer to, but is not limited to, is a large molecule, or macromolecule, composed of many repeated subunits. Such polymers may be natural and synthetic and typically created via polymerization of multiple monomers. Polymers through their large molecular mass may provide unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semi-crystalline structures rather than crystals.
A “discretized element” as used herein may refer to, but is not limited to, an element creating an emitted signal within an additive manufacturing (AM) system according to or exploiting one or more embodiments of the invention. A discretized element may refer solely to that portion of each element generating the emitted signal, e.g. a transducer, or it may refer to the element generating the emitted signal together with part or all of the associated control and drive circuitry receiving control data, processing the control data, and generating the appropriate drive signal(s) to the element generating the emitted signal. A discretized element may generate an emitted signal selected from the group comprising infrared (IR) radiation, visible radiation, ultraviolet (UV) radiation, microwave radiation, radio frequency (RF) radiation, X-ray radiation, electron beam radiation, an ultrasonic signal, an acoustic signal, a hypersonic signal, a magnetic field and an electric field. Whilst a discretized element may refer to a single emitted signal type other discretized elements may emit multiple signals. The physical dimensions of a discretized element may vary according to the dimensions of the AM system they form part as well as the number of discretized emitters within the AM system. Accordingly, discretized elements may be pico-elements having dimensions defined in picometers (10−12 m) or Angstroms (10−10 m), nano-elements having dimensions defined in nanometers (10−9 m), micro-elements having dimensions defined in micrometers (10−6 m), as well as elements having dimensions defined in millimeters (10−12 m), centimeters (10−2 m), meters (100 m) and decameters (101 m).
A: Background
As depicted in the lower half of
Accordingly, embodiments of the invention solve limitations of additive manufacturing methods, e.g. 3D printing, and tooling burdens in creating complex geometries with less manufacturing time and post-processing and controllable mechanical properties. Within the Selective Spatial Trapping (SST) method, the work chamber within the AMSys is empty at the beginning of the process. Then, powder particles are released into the chamber wherein discretized elements on the surface of the chamber apply controlled electric/magnetic fields to trap these particles in specific regions inside the workspace of the chamber and form the part.
Whilst porosity in AM produced parts is a negative issue in the aerospace and automobile industries and generally in classical mechanical engineering fields, in some other areas such as bioengineering, controlled porosity is a desired characteristic of the produced structures such as implants and artificial tissues for example. Within embodiments of the invention, the inventors provide for control of the porosity quality and quantity of the pores within the structure of the produced part by providing adjustable parameters of the AM process such as dynamically varying or statically defining the pressure of the work chamber and also the intensity of the applied field.
According to embodiments of the invention, the inventors present a new concept in AM which they refer to as “layerless” which is depicted as the lower half (Layerless 650) of the AM processing hierarchy 600 depicted in
As depicted the Layerless 650 processing is further split into two novel classes of methods which each introduce new concepts in additive manufacturing. The first class is Selective Spatial Solidification (S3 or S3) 660 using Configurable Fields. Within S3 Layerless processes an applied field is focused at a desired location within a processing chamber filled with a powder or fluid of the material to be employed in the current step or steps of the AM processing. These focal regions are created in predetermined locations inside the processing chamber to solidify the filled material inside the processing chamber selectively. Solidification may for example, occur when the focused field interacts with powder(s), a coating of the powder(s), liquid, fluid, polymer etc. These interactions may, within a subclass Electromagnetic Fields 660A, be via sintering or heat curing due to temperature increase for example through infrared (IR) light, visible light, ultraviolet (UV), microwaves, radio frequency (RF), X-ray or electron beam excitation for example. Also depicted is subclass Acoustic Fields 660B such as ultrasonic, acoustic, and hypersonic for example. The focused field is directed/generated/maneuvered inside the processing chamber by controlling active discretized elements which are responsible for applying the field(s).
The second class is Selective Spatial Trapping (SST) 670 wherein particles released into the processing chamber are trapped at the desired location inside the processing chamber to create required geometry. Within a subclass Electric/Magnetic Field(s) 670A is(are) configured within the processing chamber such that the powder particles are manipulated, placed and held in specific locations to shape the required geometry of the physical object. The electric/magnetic field may be uniform or non-uniform and may be tuned precisely based on the requirements of the geometry. Depending upon the environment within the processing chamber no subsequent processing may be required whilst in others post-formation fusing, in sub-class Heat Field 670B, may be exploited to fuse elements together using a heat source. Alternatively, in sub-class Chemical 670C a chemical reaction may be initiated with the layerless deposited material(s) to provide the fusing of the materials into a rigid piece-part.
Each of the classes S3 660 and SST 670 with their respective sub-classes may be exploited in each of the discrete layerless (single layerless process), multi-layerless (two or more layerless processes), layerless-layered (single layerless), multi-layerless-layered (two or more layerless processes with layered process), layerless-multi-layered (layerless with two or more layered processes) and multi-layerless-multi-layered (two or more layerless processes with two or more layered processes) methodologies. Optionally, the piece-part(s) formed in the layerless process(es) may be post-processed prior to another layerless and/or layered process or terminating. Within the S3 660 class methods the piece-part is manufactured in two different ways wherein (i) the entire part is focused with the excitation fields from inside to outside and further solidified whereas alternatively (ii) only the outer surface of the part is exposed to the excitation fields and solidified. When the target of the focused field is the geometrical envelope of the part, the initial material (e.g. powder) envelope is solidified and consequently produces the shell replica of the part filled with unprocessed material (e.g. the powder). When the outer solidified part is removed from the chamber the excessive powders which were not solidified may be removed through an opening within the piece-part. For example, with metallic powders the final hollow piece-part (or shelled part) may be transferred to a thermal processing environment, e.g. furnace, for final sintering to produce entire part or alternatively, the processing chamber is emptied whilst the piece-part is maintained in position and the processing chamber executes a sintering or thermal processing cycle.
B: Selective Spatial Solidification (S3) Method
Now referring to
Referring to
In the aforementioned process, temperature increases are applied to affect only localized zones of the part or of the outer shell of the part. However, it is possible to create such a field to increase the temperature to a limit that the powders themselves are sintered inside the chamber rather than requiring post-processing in a second element of manufacturing equipment. If the powders are sintered inside the chamber, there is no need to transfer the part to the furnace to further sinter the powders except in the case of outer shell approach. Optionally, rather than temperature forming the final bonding process the materials initially bonded within the S3 process are processed by either the same applied field methodology but at different conditions or another layerless sub-class of processing is applied. For example, with acoustic consolidation of powder particles to form a piece-part a subsequent higher energy acoustic processing sequence may further consolidate and bind the powders.
Alternatively, one or more of the other S3 or SST processes may be applied discretely or in combination with other manufacturing processes as known within the art. For example, the piece-part may be embedded within another material, e.g. a fluid, and hypersonic acoustic excitation employed. Alternatively, visible, infrared irradiation may be employed to raise the piece-part temperature whilst chemical processes may be triggered to bind or support subsequent processes such as, for example, catalyst triggered nucleation/deposition onto the piece-part such that the piece-part formed provides a template for another 3D AM process.
Despite existing 3D printing technologies (upper half of
Within the embodiments of the invention, with the exploitation of powders, particulates, etc. rather than fluids or fluid mixtures it may be beneficial to control the level of the porosity of the part structure, e.g. biological implantation piece-parts, micro-catalytic reactors, etc. Accordingly, within an embodiment of the invention the powder(s) inside the chamber may be pressurized to achieve an acceptable density/low porosity of the part. The conventional AM machines lack this kind of pressure to compact the powders. Referring to
Optionally, the chamber 310 may be evacuated to remove air and/or flushed—filled with a predetermined fluid that may, for example, aid formation of the part, prevent adverse reactions, and be included within closed pores within the finished piece-part. For example, filling with an inert gas would prevent any reactions with the oxygen in air when the piece-part is heated. Alternatively, evacuating to a predetermined vacuum level would result in any enclosed voids being vacuum. In addition to adjusting the AM process the use of a vacuum and/or fluid may aid establishment of the required density within the compact powders thereby in producing high quality functional mechanical parts absent micro-structures or with homogeneous micro-structures. Processing without the same degree of compaction may provide micro-structures of varying dimensions.
Referring to
Second parallel process 700B comprises:
Accordingly, Process 700C comprises:
It would be evident that optionally, step 780 may be replaced with an apply sintering process within the chamber where the discretized elements or a second set of discretized elements support the sintering process
C: Selective Spatial Trapping (SST) Method
Now referring to
Accordingly, as with the S3 methodology, the 3D computerized model of the designed part is analyzed by the software 400 and varying fields applied by the discretized elements are calculated in such a way that the field in the interior regions of the part transiently equalized to force the fed powders to be gathered into desired regions of the piece-part, which the inventors refer to as called “settled regions”. This process being depicted in
For example, the piece-part may be infrared illuminated to heat it, a chemical fluid maybe introduced to react with a particle coating or catalyze a reaction, or a binder agent introduced. The part may be post-processed in situ, within another chamber via automated transfer or different processing system completely. For example, a piece-part exposing to a binding fluid may be transferred to a furnace for sintering. The final produced part, after the sintering process in the furnace, will accordingly have the desired mechanical properties for a functional mechanical component. In other words, embodiments of the invention provide a manufacturing process that is mold-less metallurgy powder based. Without using a mold, the powder particles are gathered in the desired regions to create the geometry of the part and then the part is mounted in the furnace for sintering process. Accordingly, re-entrant geometries that cannot be molded today without requiring destruction of the mold can be formed and the parts exploiting metallic cross-sections that vary in a controlled manner due to the selective addition—deposition (accretion) process or have different alloy compositions in different locations. Further, inserts of one metal may be made directly during manufacturing without requiring subsequent processing.
Further, by varying the applied fields within the workspace and the accretion locations allows the designer to form parts with a capability to compact the powders to avoid any porosity inside the structure of the part or engineer the porosity to a desired level. As inventive method does not use any layer(s) process, therefore, homogenous mechanical properties of the part can be established. Alternatively, non-homogenous mechanical properties can be established with a graduation-definition-location etc. that cannot be achieved with convention manufacturing processes without multiple molding/casting processes with or without additional milling/drilling/machining. For example, a copper core can be formed between stainless steel casing with complex 3D geometry in single manufacturing sequence. The produced parts can compete with the parts produced by machining or molding process in terms of mechanical properties and functionality. Further, as production time in the present method in lower than the conventional additive manufacturing using layer-by-layer concepts (where these are actually available) then the layerless AM process is expected to further offer lower costs and higher throughputs.
Referring to
It would be evident to one of skill in the art that the exemplary process flow 800 may be varied to support other AM processes such as, for example, supporting sequential deposition of different powders through a loop involving all or a subset of steps 810 to 850 respectively or that the step 840 may involve the injection of a time varying powder composition controlled by the overall system in response to the CAD file and driving the discretized elements appropriately.
D: Selective Spatial Solidification (S3) Method
As described and discussed supra in respect of
As depicted in
Optionally, the tiles as depicted in
Each discretized element is activated to create a field by a pulse generator which creates voltage or current pulses. The activation pattern of the discretized elements and the type of the pulse is calculated by the software which analyzes the 3D geometry of the part and calculates the required field. The filed is calculated in such a way that the interior and boundaries of the part are solidified selectively. The digital signal processing unit generates the voltage information to create the field. The numerical calculations required to activate the electrodes are performed from the desire 3D model of the structure to be manufactured.
Now referring to
Now referring to
Depending upon the design and configuration of the chamber then these FFZs may be spherical within a spherical uniform chamber but within the system configuration of
D1: Material in the Selective Spatial Solidification (S3) Method
Embodiments of the invention may be applied to manufacture metallic, ceramic and polymeric parts. For metallic parts, metal powders may be coated with a thermoset resin which is cured with temperature increase. However, it is possible to use thermoplastic or wax powders mixed with metal powders, in this case, the field increases the temperature of the wax powders and melts them. Then, when the melted wax is solidified in the affected region, the metallic or ceramic powders would be trapped in the solidified region. Ceramic powders can be used to create ceramic parts. The process is similar to metallic parts when the coated ceramic powders are spatially fixed inside the powder chamber.
Polymeric parts can be manufactured out of liquid polymer materials or polymeric powders. In this case, chamber is filled with liquid thermoset. The field selectively increases the temperature inside the chamber and solidifies the liquid thermoset. It is also possible to insert or embed metallic and non-metallic parts inside the chamber to make 3D polymer products with metallic parts in it.
Optionally, parts can be coated with a combination of materials such that an initial thermoset defined accretion may be solidified and then a second material reacted to form a stronger more durable bond for final part use through exposing the interim piece part to one or more chemicals in fluidic form. Accordingly, a wide range of materials may be employed without coatings, with coatings, and exploiting one or more AM excitation means including, but not limited to, ultraviolet radiation, visible radiation, infrared radiation, microwave radiation, X-rays, heat, acoustic radiation, ultrasonic radiation, and hypersonic radiation. In some AM systems a combination of two or more excitation means many be required to “accrete” material to the piece-part.
D2: Field Sources in the Selective Spatial Solidification (S3) Method
Within embodiments of the invention for the S3 AM process then in principle any electromagnetic or non-electromagnetic field can be used in the present patent based on the specifications of the material of the part to be formed through the S3 process. Electromagnetic fields such as ultraviolet radiation, visible radiation, infrared radiation, microwave radiation, X-rays etc. do not need a medium for transmission. However, non-electromagnetic fields such acoustic radiation, ultrasonic radiation, and hypersonic radiation need a medium for transmission. In each case, the focal regions can be created in the 3D space of the chamber using the configuration of the elements as discussed and depicted in respect of
D3: Setup for Manufacturing Polymer Parts in the Selective Spatial Solidification (S3) Method
As discussed supra embodiments of the invention may be employed for creating polymeric parts, a setup can be built using single element spherical transducers. As shown in
Although the setup shown in
D4: FFZs Location Determination in the Selective Spatial Solidification (S3) Method
The center locations of the FFZs is important in achieving an accurate part. As shown in
E: Selective Spatial Trapping (SST) Method
In order to fabricate 2D structures, the electric field could be applied and configured in a 2D workspace such as that shown in
As depicted in
D1: Selective Spatial Trapping Case Studies
In the following case studies, the assumptions are for a particle diameter D=150μm and density ρ=2.7 gcm−3.
Case I: Two particles are released with initial velocity 10 μm/s. The workspace micro-electrodes apply a voltage of 1000V as depicted by first image 1410 in
Case II: A particle is released at velocity of 2 mm/s. The plan is to settle the particle on a moving target line with velocity as v0. Again as depicted in
Case III: Two particles are released with initial velocities wherein the intention is to settle the particles onto the target circle identified in first image 1710 in
Case IV:
F: S3 and SST Piece-Part Support
Within the preceding description with respect to the S3 and SST AM manufacturing processes the embodiments of the invention have been described with respect to isolated piece-parts. However, it would be evident that within some embodiments of the invention that the piece-part as it is formed may not be supported by the surrounding medium or that its density may be less than that of the surrounding medium and hence it seeks to rise within the chamber. Accordingly, the piece-part may be formed in conjunction with one or more dielectric elements disposed within the chamber wherein the material and geometry of these dielectric elements may vary according to the S3/SST AM process, e.g. high temperature SST of metals might exploit one or more ceramic dielectric elements, whereas a microwave based S3 AM of polymer might exploit polypropylene, for example, which has low dielectric constant and low dielectric loss. In most instances the determination of applied fields would require that in addition to the 3D material and geometry information of the piece-part to be manufactured that the same data for the one or more dielectric elements be included to achieve the correct fields to be generated.
Within some embodiments a low temperature sacrificial dielectric element might be employed such that the dielectric element is removed through increasing the temperature of the piece part. In other embodiments of the invention the dielectric element may provide a fixture for automated and/or manual removal and transfer of the S3/SST manufactured piece part from one layerless AM process to another layerless AM process/layered AM process/conventional process etc.
In other embodiments of the invention according to the design of the piece-part and the chamber the supporting surface may be inner surface of the chamber (3D) or upper surface of the plate (2D).
Accordingly, within some embodiments of the invention the concepts described supra in respect of the provisioning of a dielectric element to support the layerless AM part during processing may be extended such that in addition to the dielectric element a predetermined portion of the piece-part is also provided having been formed from a layerless AM process, a layered AM process, and/or other manufacturing process. For example, a ceramic element formed from S3 based accretion with annealing may upon a mounting element form the carrier for a metallic SST process to deposit electrical connections and elements upon the surface of the ceramic prior to further manufacturing. Alternatively, a ceramic element may have a metallic fixturing element integrated by forming the fixturing element with an SST or S3 process.
G: Layerless-Layered and Layerless-Conventional Manufacturing
As described and discussed supra the S3 and SST layerless AM processes support manufacturing exploiting them as the sole AM process or they may be employed in conjunction with a “layered” AM process as known within the prior art. Accordingly, discrete layerless (single layerless process), multi-layerless (two or more layerless processes), layerless-layered (single layerless), multi-layerless-layered (two or more layerless processes with layered process), layerless-multi-layered (layerless with two or more layered processes) and multi-layerless-multi-layered (two or more layerless processes with two or more layered processes) may be implemented using techniques, processes, and methods according to embodiments of the invention.
H: Numerical Simulation Example
An embodiment of the invention comprising chamber, transducer and the container's wall was modeled using COMSOL software and the activation via sonication simulated by the Finite Element Method (FEM).
The wave equation defined within two-dimensional (2D) axisymmetric cylindrical coordinates can be written as Equation (1) where r, z, p, ω, ρc and cc are radial and axial coordinates, acoustic pressure, angular frequency, density and speed of sound respectively.
Within the acoustic simulation, the acoustic pressure and intensity were calculated. Table 1 lists some of the input parameters for the acoustic simulation.
Accordingly, referring to
Accordingly, an input pulse for sonication was estimated to raise the temperature at the focal region to the fast curing temperature of the resin. In the current simulated example, the temperature at the focal region was increased by approximately 75° C. (to 100° C. from 25° C. ambient temperature) in the steady state with a peak temperature increase of approximately 100° C. Accordingly, the temperature can be maintained for the period of time required to cure and solidify the resin in the focal region by continuing the sonication. The temperature increase at the focal region derived from the simulated is depicted in
The foregoing disclosure of the exemplary embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many variations and modifications of the embodiments described herein will be apparent to one of ordinary skill in the art in light of the above disclosure. The scope of the invention is to be defined only by the claims appended hereto, and by their equivalents.
Further, in describing representative embodiments of the present invention, the specification may have presented the method and/or process of the present invention as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the specification should not be construed as limitations on the claims. In addition, the claims directed to the method and/or process of the present invention should not be limited to the performance of their steps in the order written, and one skilled in the art can readily appreciate that the sequences may be varied and still remain within the spirit and scope of the present invention.
This application claims the benefit of priority a 371 national phase application from Patent Cooperation Treaty patent application PCT/CA2018/000,023 filed Feb. 7, 2018 entitled “Methods and Systems for Additive Manufacturing” which itself claims benefit of priority from U.S. Provisional patent application 62/455,750 filed Feb. 7, 2017 entitled “Methods and Systems for Additive Manufacturing”, the entire contents of each being incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2018/000023 | 2/7/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62455750 | Feb 2017 | US |
