Additive manufacturing system and method

Abstract

To disclose an additive manufacturing system including a two-dimensional energy patterning system for imaging a powder bed.SOLUTION: Improved optical systems supporting beam combining, beam steering, and both patterned and unpatterned beam recycling and re-use are described.SELECTED DRAWING: Figure 3C

Description

[Technical Field]

[0001] [Cross-reference to related patent applications] The present disclosure provides: U.S. Patent Application No. 62 / 248,758, filed October 30, 2015; U.S. Patent Application No. 62 / 248,765, filed October 30, 2015; U.S. Patent Application No. 62 / 248,770, filed October 30, 2015; U.S. Patent Application No. 62 / 248,776, filed October 30, 2015; U.S. Patent Application No. 62 / 248,783, filed October 30, 2015; U.S. Patent Application No. 62 / 248,791, filed October 30, 2015; U.S. Patent Application No. 62 / 248,799, filed October 30, 2015; U.S. Patent Application No. 62 / 248,966, filed October 30, 2015; U.S. Patent Application No. 62 / 248,968, filed October 30, 2015; U.S. Patent Application No. 62 / 248,969, filed October 30, 2015; U.S. Patent Application No. 62 / 248,980, filed October 30, 2015; U.S. Patent Application No. 62 / 248,989, filed October 30, 2015; U.S. Patent Application No. 62 / 248,780, filed October 30, 2015; U.S. Patent Application No. 62 / 248,787, filed October 30, 2015; U.S. Patent Application No. 62 / 248,795, filed October 30, 2015; U.S. Patent Application No. 62 / 248,821, filed October 30, 2015; U.S. Patent Application No. 62 / 248,829, filed October 30, 2015; U.S. Patent Application No. 62 / 248,833, filed October 30, 2015; U.S. Patent Application No. 62 / 248,835, filed October 30, 2015; U.S. Patent Application No. 62 / 248,839, filed October 30, 2015; U.S. Patent Application No. 62 / 248,841, filed October 30, 2015; U.S. Patent Application No. 62 / 248,847, filed October 30, 2015; and This is a part of a non-provisional patent application claiming benefit of priority to U.S. Patent Application No. 62 / 248,848, filed October 30, 2015, and incorporated by reference in its entirety.

[0002] [Technical field] The present disclosure relates generally to systems and methods for additive manufacturing. In one embodiment, powder bed fusion manufacturing with two-dimensional energy patterning and energy beams is described. [Background technology]

[0003] Traditional part fabrication often relies on the removal of material by drilling, cutting, or fracturing to form a part. Additive manufacturing, also known as 3D printing, on the other hand, typically involves the successive layer-by-layer addition of material to build a part. Starting with a 3D computer model, additive manufacturing systems are used to create complex parts from a wide variety of materials.

[0004] One additive manufacturing technique, known as powder bed fusion (PBF), uses one or more focused energy sources, such as a laser or electron beam, to print a pattern in a thin layer of powder by melting the powder and bonding it to the layer below. The powder can be plastic, metal, or ceramic. This technique is highly accurate, achieving features as small as 150–300 μm. However, manufacturers of powder bed fusion additive manufacturing machines struggle to produce machines capable of printing material at rates greater than 1 kg / hr. Due to this slow powder-to-solid conversion rate, machines are relatively small in size due to the length of time it takes to print larger parts. Today's largest machines typically have a printable part volume of less than 64 L (40 cm). While these printers can print parts of nearly any shape, the high cost of the machines and the slow powder conversion rate ultimately make the amortized cost of the machines very high, resulting in expensive parts.

[0005] Unfortunately, simply scaling up the machine to increase part size or reduce manufacturing costs is not a satisfactory solution. At a minimum, to melt the desired volume of material, the laser must deliver enough energy to raise the melting temperature and the phase change energy required for melting. If no thermal energy is dissipated in this process, then there is a linear scaling between the accumulated laser energy over time (laser power) and the material throughput rate. If manufacturers of powder bed fusion additive manufacturing machines wanted to scale up in material throughput rate, they would necessarily need to increase their laser power. This increase in laser power, unfortunately, increases proportionally with the cost of the laser, and scaling up would significantly increase the cost of machines that are already expensive today.

[0006] Even if laser cost were not a factor, scaling laser power has other detrimental effects. All powder materials have optimal melting characteristics that depend on power flux. If the power is too low, the powder will not melt; if it is too high, the laser may drill into the material (keyhole). Increasing the laser power of a machine already operating at one of these optimum points inevitably results in the need to increase the laser area (spot size) to maintain optimal power flux. Splitting the laser into multiple beams increases system complexity, while simply increasing the spot size reduces the printable resolution.

[0007] Indeed, currently available powder bed additive manufacturing machines can be limited in part size, part manufacturing cost, part detail resolution, and part manufacturing throughput. [Brief explanation of the drawings]

[0008] Non-limiting, non-exhaustive embodiments of the present disclosure are described with reference to the following drawings, in which like reference numerals refer to like parts throughout the various drawings unless otherwise stated. [Figure 1A] 1 illustrates an additive manufacturing system. [Figure 1B] FIG. 1 illustrates a top view of a structure being formed on an additive manufacturing system. [Figure 2] 1 illustrates an additive manufacturing method. [Figure 3A] 1 is a diagram illustrating an additive manufacturing system including a laser. [Figure 3B] 3B is a detailed illustration of the optical patterning unit shown in FIG. 3A. [Figure 3C] FIG. 1 illustrates an embodiment of an additive manufacturing system with a “switchyard” for directing and re-patterning light using multiple image relays. [Figure 3D] 1 illustrates simplified mirror image pixel remapping. [Figure 3E] 1 illustrates a series of image transformation image relays for pixel remapping. [Figure 3F]1 illustrates a patternable electron energy beam additive manufacturing system. [Figure 3G] 3F illustrates a detailed description of the electron beam patterning unit shown in FIG. 3F. [Figure 4A] 1 illustrates various beam combining embodiments. [Figure 4B] 1 illustrates various beam combining embodiments. [Figure 4C] 1 illustrates various beam combining embodiments. [Figure 5A] 1 illustrates an embodiment of a reflective light patterning unit. [Figure 5B] 1 illustrates an embodiment of a reflective light patterning unit. [Figure 6] Illustrates light recycling. [Figure 7] It is a polarized beam system. [Figure 8] 10 is a flowchart of magnification change and gantry movement. [Figure 9A] The powder bed system and the thermal management system are respectively illustrated. [Figure 9B] The powder bed system and the thermal management system are respectively illustrated. [Figure 10] 10 is a flow chart illustrating the additive formation of temporary walls to contain the powder. [Figure 11A] 1 illustrates an embodiment of powder removal. [Figure 11B] 1 illustrates an embodiment of powder removal. [Figure 12A] 1 illustrates the production of a long part with multiple sections. [Figure 12B] 1 illustrates the production of a long part with multiple sections. [Figure 13A] Illustrates the processing of a part at an operating point. [Figure 13B] Illustrates the processing of a part at an operating point. [Figure 13C] Illustrates the processing of a part at an operating point. [Figure 14] It is a representative component with additional defined operating points. [Figure 15]1 is a flow chart illustrating the testing and characterization of powder samples. [Figure 16] FIG. 1 is a diagram of an enclosed additive manufacturing facility. [Figure 17] FIG. 1 is a diagram of an additive manufacturing facility with multiple work areas. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following description, reference is made to the accompanying drawings which form a part hereof, and which show by way of illustration specific exemplary embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the concepts disclosed herein, and it should be understood that various modifications may be made to the disclosed embodiments and other embodiments may be utilized without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0010] An additive manufacturing system having one or more energy sources, including one or more lasers or electron beams in one embodiment, is positioned to emit one or more beams. Beam shaping optics receive one or more energy beams from the energy source and form a single beam. An energy patterning unit receives or generates the single beam, transfers a two-dimensional pattern to the beam, and discards unused energy not in the pattern. An image relay receives the two-dimensional patterned beam and focuses it as a two-dimensional image onto a predetermined location on a build platform (e.g., a powder bed) that may be fixed or movable in height. In some embodiments, some or all of any discarded energy from the energy patterning unit is recycled.

[0011] In some embodiments, multiple beams from the laser array are combined using a beam homogenizer. This combined beam can be directed to an energy patterning unit that includes either a transmissive or reflective pixel-addressable light valve. In one embodiment, the pixel-addressable light valve includes both a liquid crystal module with a polarizing element and an optical projection unit that provides a two-dimensional input pattern. The two-dimensional image, focused by an image relay, is directed to multiple locations on the powder bed to build a three-dimensional structure.

[0012] As seen in FIG. 1 , additive manufacturing system 100 includes an energy patterning system 110 with an energy source 112 that can direct one or more continuous or intermittent energy beams to beam shaping optics 114. After shaping, the beam is patterned by an energy patterning unit 116, with some energy typically directed to a waste energy processing unit, if necessary. The patterned energy is relayed by an image relay 120 to an article processing unit 140, typically as a two-dimensional image 122 focused near a floor 146. The floor 146 (with optional walls) may form a chamber containing material 144 dispensed by a material dispenser 142. The patterned energy directed by image relay 120 may melt, fuse, sinter, fuse, change to a crystalline structure, impart a stress pattern, or otherwise chemically or physically modify the dispensed material 144 to form a structure with desired properties.

[0013] Energy source 112 generates photons (light), electrons, ions, or other suitable energy beams or fluxes that can be directed, shaped, and patterned. Energy source 112 can include lasers, white light, focused sunlight, other light sources, electron beams, or ion beams. Possible laser types include, but are not limited to, gas lasers, chemical lasers, dye lasers, metal vapor lasers, solid-state lasers (e.g., fiber), semiconductor (e.g., diode) lasers, free electron lasers, gas dynamic lasers, "nickel-like" samarium lasers, Raman lasers, or nuclear-pumped lasers.

[0014] Gas lasers may include lasers such as helium-neon lasers, argon lasers, krypton lasers, xenon ion lasers, nitrogen lasers, carbon dioxide lasers, carbon monoxide lasers, or excimer lasers.

[0015] Chemical lasers may include lasers such as hydrogen fluoride lasers, deuterium fluoride lasers, COIL (chemoenzymatic iodine lasers), or Agil (all vapor phase iodine lasers).

[0016] Metal vapor lasers can include lasers such as helium-cadmium (HeCd) metal vapor lasers, helium-mercury (HeHg) metal vapor lasers, helium-selenium (HeSe) metal vapor lasers, helium-silver (HeAg) metal vapor lasers, strontium vapor lasers, neon-copper (NeCu) metal vapor lasers, copper vapor lasers, gold vapor lasers, manganese (Mn / MnCl) vapor lasers, and the like.

[0017] Solid-state lasers include ruby ​​lasers, Nd:YAG lasers, NdCrYAG lasers, Er:YAG lasers, neodymium YLF (Nd:YLF) solid-state lasers, neodymium-doped yttrium orthovanadate (Nd:YVO4) lasers, and neodymium-doped yttrium calcium oxoborate (Nd:YCa4O(BO3)) lasers. 3Or simply Nd:YCOB, neodymium glass (Nd:glass) laser, titanium sapphire (Ti:sapphire) laser, thulium YAG (Tm:YAG) laser, yttrium YAG (Yb:YAG) laser, yttrium:2O3 (glass or ceramic) laser, yttrium doped glass laser (rod, plate / chip, and fiber), holmium YAG (Ho:YAG) laser, chromium ZnSe (Cr:ZnSe) laser, cerium doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), promethium 147 doped phosphate glass (147Pm +3 The lasers may include lasers such as a trivalent uranium-doped calcium fluoride (U:CaF) solid-state laser, a divalent samarium-doped calcium fluoride (Sm:CaF) laser, or an F-center laser.

[0018] The semiconductor laser may include laser media such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, GaInP, InGaAs, InGaAsO, GaInAsSb, lead salt, vertical cavity surface emitting laser (VCSEL), quantum cascade laser, hybrid silicon laser, or combinations thereof.

[0019] For example, in one embodiment, a single Nd:YAG q-switched laser can be used in conjunction with multiple semiconductor lasers. In another embodiment, an electron beam can be used in conjunction with an array of ultraviolet semiconductor lasers. In yet other embodiments, a two-dimensional array of lasers can be used. In some embodiments, with multiple energy sources, pre-patterning of the energy beam can be achieved by selectively activating and deactivating the energy sources.

[0020] The beam shaping unit 114 may include a wide variety of imaging optics to combine, focus, diverge, reflect, refract, homogenize, intensity-adjust, frequency-adjust, or otherwise shape one or more energy beams received from the energy source(s) and direct them to the energy patterning unit 116. In one embodiment, multiple light beams, each having a different optical wavelength, may be combined using wavelength-selective mirrors (e.g., dichroic) or diffractive elements. In other embodiments, multiple beams may be homogenized or combined using polygonal mirrors, microlenses, and refractive or diffractive optical elements.

[0021] The energy patterning unit 116 may include static or dynamic energy patterning elements. For example, a photon, electron, or ion beam may be intercepted by a mask with fixed or movable elements. Pixel-addressable masking, image generation, or transmission may be used for greater flexibility and ease of image patterning. In some embodiments, the energy patterning unit includes addressable light valves alone or in combination with other patterning devices to provide the patterning. The light valves may be transmissive, reflective, or use a combination of transmissive and reflective elements. The pattern may be dynamically changed using electrical or optical addressing. In one embodiment, a transmissive optically addressed light valve acts to rotate the polarization of light passing through the valve, with optically addressed pixels forming a pattern defined by an optical projection source. In another embodiment, a reflective optically addressed light valve includes a write beam to change the polarization of a read beam. In yet another embodiment, an electronic patterning device receives an address pattern from an electrical or photon stimulation source and generates a patterned emission of electrons.

[0022] The waste energy processing unit 118 is used to dissipate, redirect, and utilize energy that is not patterned and passes through the energy pattern image relay 120. In one embodiment, the waste energy processing unit 118 may include passive or active cooling elements to remove heat from the energy patterning unit 116. In other embodiments, the waste energy processing unit may include a "beam dump" to absorb and convert to heat any beam energy not used to define the energy pattern. In yet other embodiments, the discarded energy beam may be recycled using beam shaping optics 114. Alternatively, or in addition, the discarded energy beam may be directed to the article processing unit 140 for heating or further patterning. In some embodiments, the discarded beam energy may be directed to an additional energy patterning system or article processing unit.

[0023] Image relay 120 receives the patterned image (typically two-dimensional) from energy patterning unit 116 and directs it to article processing unit 140. In a manner similar to beam shaping optics 114, image relay 120 may include optics for combining, focusing, diverging, reflecting, refracting, intensity adjusting, frequency adjusting, or otherwise shaping and directing the patterned image.

[0024] The article processing unit 140 may include a walled chamber 148 and a floor 144, and a material dispenser 142 for dispensing materials. The material dispenser 142 may dispense, remove, or mix materials, provide gradations or variations in material types or article sizes, or adjust layer thickness. Materials may include metals, ceramics, glasses, polymer powders, and other meltable materials capable of undergoing a thermally induced phase change from solid to liquid and back again. The materials may also include composites of meltable and non-meltable materials, in which either or both components can be selectively targeted with an image relay system to melt the meltable component, while leaving only the non-meltable material or subjecting it to evaporation, destruction, combustion, or other destructive processes. In some embodiments, a slurry, spray, paint film, wire, strip, or sheet of material may be used. Unwanted material may be removed by using a blower, a vacuum system, sweeping, vibrating, shaking, sloping, or inverting the floor 146 for disposal or recycling.

[0025] In addition to the material processing components, the article processing unit 140 may include components for holding and supporting the three-dimensional structure, devices for heating or cooling the chamber, auxiliary or supporting optics, and sensors and controls for monitoring or adjusting material or environmental conditions. The article processing unit may support a vacuum or gas atmosphere in whole or in part to mitigate the risk of fire or explosion (especially with highly reactive metals) and to reduce unwanted chemical interactions.

[0026] The control processor 150 may be connected to control any component of the additive manufacturing system 100. The control processor 150 may be connected to various sensors, actuators, heating or cooling systems, monitors, and controllers to coordinate operation. A wide range of sensors may be used to provide information used for control or monitoring, including imaging devices, light intensity monitors, heat, pressure, or gas sensors. The control processor may be a single central controller, or alternatively, may include one or more independent control systems. The control processor 150 provides an interface through which manufacturing instructions can be entered. The extensive use of sensors allows for various feedback control devices to improve quality, manufacturing throughput, and energy efficiency.

[0027] 1B is a diagram illustrating bed 146 supporting material 144. Structure 149 is additively fabricated using a series of sequentially applied two-dimensional patterned energy beam images (rectangles with dotted outlines). Of course, image patterns with non-rectangular borders can be used, overlapping or interpenetrating images can be used, and images can be provided by two or more energy patterning systems. In other embodiments, images can be formed with directed electron or ion beams, or with printing or selective spray systems.

[0028] 2 is a flow chart illustrating one embodiment of an additive manufacturing process supported by the described opto-mechanical components. In step 202, a material is placed in a bed, chamber, or other suitable support. The material may be a powder that can be melted, fused, sintered, induced to change crystal structure, affected to form a structure with desired properties, or have stress patterns chemically or physically altered.

[0029] In step 204, unpatterned energy is emitted by one or more energy emitters, including, but not limited to, a solid-state or semiconductor laser, or a power supply that sends electrons down a wire. In step 206, the unpatterned energy is shaped and modified (e.g., intensity adjusted or focused). In step 208, this unpatterned energy is patterned, along with energy that does not form part of the pattern being processed in step 210 (which may include conversion to waste heat or recycling as patterned or unpatterned energy). In step 212, the patterned energy that now forms the two-dimensional image is relayed toward the material. In step 214, the image is applied to the material to build part of a three-dimensional structure. These steps are repeated (loop 218) until the image (or a different subsequent image) has been applied to all required areas of the top layer of material. Once the application of energy to the top layer of material has finished, a new layer can be applied to continue building the three-dimensional structure. If the remaining excess material can be removed or recycled, the loop of these steps continues until the three-dimensional structure is completed.

[0030] FIG. 3A illustrates one embodiment of an additive manufacturing system 300 that employs multiple semiconductor lasers as part of an energy patterning system 310. A control processor 350 may connect to various sensors, actuators, heating or cooling systems, monitors, controllers for coordinating the operation of the multiple lasers 312, the light patterning unit 316, and an image relay 320, along with any other components of the system 300. These connections are generally indicated by a dotted outline 351 surrounding the components of the system 300. As can be seen, the connections may be wired or wireless, continuous or intermittent, and may include feedback capabilities (e.g., heating may be adjusted in response to a sensed temperature). The multiple lasers 312 may emit beams 301 of light at a wavelength of 1000 nm, for example, 20 mm high and 90 mm wide. Beam 301 is resized by imaging optics 370 to produce beam 303. Beam 303, 6 mm high and 6 mm wide, enters light homogenizer 372, which blends the light to create mixed beam 305. Beam 305 then enters imaging assembly 374, which reshapes the light into beam 307, and then enters hot / cold mirror 376. Mirror 376 reflects 450 nm light but allows 1000 nm light to pass. Light projector 378, capable of projecting low-power light at 450 nm with a pixel resolution of 1080p, emits beam 309, which then enters hot / cold mirror 376. Beams 307 and 309 are superimposed on beam 311, and both are imaged onto optically addressed light valve 380 as a 20 mm wide, 20 mm high image. The images formed from homogenizer 372 and projector 378 are recreated and superimposed on light valve 380.

[0031] Optically addressed light valve 380 is stimulated by light (typically 400-500 nm wide) which imprints a polarization rotation pattern onto transmitted beam 313, which is incident on polarizer 382. Polarizer 382 splits the two polarization states, transmitting p-polarized light into beam 317 and reflecting s-polarized light into beam 315, which is then sent to a beam dump for waste energy disposal. Of course, in other embodiments, the polarization could be swapped, with s-polarized light formed in beam 317 and p-polarized light reflected into beam 315. Beam 317 enters final imaging assembly 320, which includes optics 384 that resizes the patterned light. This beam reflects from movable mirror 386 into beam 319, which terminates in a focused image that is applied to material bed 344 in article processing unit 340. The depth of field of the image is selected to span multiple layers, providing optimal focus with a few layers of error or offset.

[0032] A bed 390 can be raised and lowered (pulled vertically) into chamber walls 388 containing material 344 dispensed by material dispenser 342. In some embodiments, bed 390 can remain fixed and the optics of final imaging assembly 320 can be raised and lowered vertically. Material distribution is provided by a sweep device 392 that evenly distributes powder held in a hopper 394 and can supply a new layer of material as needed. A 6 mm high by 6 mm wide image is continuously directed by a movable mirror 386 at various locations on the bed.

[0033] When using powdered ceramic or metallic materials in this additive manufacturing system 300, the powder can be spread in a thin layer, approximately 1-3 grains thick, on top of the substrate (and subsequent layers) as the part is built. When the patterned beam 319 melts, sinters, or fuses the powder, it bonds to the underlying layers, creating a solid structure. The patterned beam 319 can operate in a 40 Hz pulsed fashion, moving to subsequent 6 mm x 6 mm image locations at intervals of 10 ms to 0.5 ms (preferably 3 to 0.1 ms) until selected patterned areas of the powder are melted. The bed 390 then lowers itself by a thickness corresponding to one layer, and the sweeper 392 spreads a new layer of powder material. This process is repeated until the two-dimensional layers build the desired three-dimensional structure. In some embodiments, the article processing unit 340 can have a controlled atmosphere. This allows highly reactive materials to be produced in an inert gas or vacuum environment without the risk of oxidation or chemical reaction, or fire or explosion (if highly reactive metals are used).

[0034] FIG. 3B illustrates the operation of light patterning unit 316 of FIG. 3A in more detail. As seen in FIG. 3B, an exemplary input pattern 333 (here seen as the number "9") is defined by an 8×12 pixel array of light projected as beam 309 toward mirror 376. White pixels are unlit, and gray pixels represent bright pixels. For example, each pixel may have various light levels, including light-free, partial light intensity, and maximum light intensity. Unpatterned light 331, forming beam 307, is directed through and passes through hot / cold mirror 376, where it combines with patterned beam 309. After reflection by hot / cold mirror 376, patterned light beam 311 is formed from the superposition of beam 307 and beam 309 in beam 311, both of which are imaged onto optically addressed light valve 380. An optically addressed light valve 380, capable of rotating the polarization state of unpatterned light 331, is stimulated by patterned light beams 309, 311 to selectively unrotate the polarization state of polarized light 307, 311 in the pattern of the number "9" into beam 313. The representative pattern 333 of unrotated light in beam 313 may then pass through polarizer mirror 382, ​​which results in beam 317 and pattern 335. Polarized light of a second rotation state is discarded by polarizer mirror 382 into beam 315, which carries a negative pixel pattern 337 consisting of the light-free number "9".

[0035] Other types of light valves may be substituted for or used in combination with the described light valves. Reflective light valves, or light valves based on diffraction or refraction, may also be used. In some embodiments, non-optically addressed light valves may be used. These may include, but are not limited to, electrically addressable pixel elements, movable mirror or micromirror systems, piezoelectric or micro-actuated optical systems, fixed or movable masks or shielding plates, or other conventional systems capable of providing high intensity patterning. For electron beam patterning, these valves may selectively emit electrons based on address position, thereby imprinting a pattern onto the beam of electrons leaving the valve.

[0036] Figure 3C illustrates an embodiment of an additive manufacturing system including a switchyard system capable of patterned two-dimensional energy recycling. Similar to the embodiment discussed with respect to Figure 1A, additive manufacturing system 220 includes an energy patterning system with an energy source 112 that directs one or more continuous or intermittent energy beams to beam shaping optics 114. After shaping, the beams are typically patterned in two dimensions by energy patterning unit 222, with some energy being directed to waste energy processing unit 222. The patterned energy is relayed by one of multiple image relays 232 to one or more article processing units 234A, 234B, 234C, or 234D as a two-dimensional image focused near a floor, typically at a movable or fixed height. The floor (together with optional walls) may form a chamber containing material dispensed by a material dispenser. The patterned energy directed by the image relay 232 may melt, fuse, sinter, fuse, change to a crystalline structure, impart a stress pattern, or otherwise chemically or physically modify the dispensed material 144 to form a structure with desired properties.

[0037] In this embodiment, the waste energy processing unit has multiple components to enable reuse of the patterned waste energy. Relays 228A, 228B, and 228C may relay energy to generator 224, heating / cooling thermal management system 225, or energy dump 226, respectively. Optionally, relay 228C may direct the patterned energy to image relay 232 for further processing. In other embodiments, the patterned energy may be directed by relay 228C to relays 228B and 228A for insertion into the energy beam provided by energy source 112. Using image relay 232, reuse of the patterned image is also possible. The image may be redirected, inverted, mirrored, sub-patterned, or converted for distribution to one or more article processing units 234A-D. Advantageously, recycling patterned light can improve the energy efficiency of the additive manufacturing process and in some cases can improve the energy intensity directed at the floor or reduce manufacturing time.

[0038] 3D is a diagram illustrating a simple geometric transformation of a waste energy beam for reuse. An input pattern 236 is directed to an image relay 237, which can provide a mirror image pixel pattern 238. As can be seen, more complex image transformations are possible, including geometric transformations or pattern relocation of individual pixels and groups of pixels. Instead of using a beam dump, this relocated pattern can be directed to an article processing unit to improve manufacturing throughput or beam intensity.

[0039] 3E is a diagram illustrating multiple transformations of the waste energy beam for reuse. An input pattern 236 is directed to a series of image relays 237B-E, which can provide an image pattern 238.

[0040] 3F and 3G illustrate a non-light-based energy beam system 240 including a patterned electron beam 241 that can create, for example, a "P" shaped pixel image. A high-voltage power system 243 is connected to an optically addressable pattern cathode system 245. In response to application of a two-dimensional patterned image by a projector 244, the cathode units 245 are stimulated to emit electrons wherever the patterned image is optically addressed. Focusing of the electron beam pattern is provided by an image relay system 247 that includes imaging coils 246A and 246B. Final positioning of the patterned image is provided by a polarizing coil 248 that can move the patterned image to a desired location on the floor of an additively manufactured component 249.

[0041] In another embodiment supporting light recycling and reuse, multiple beams of light are provided from one or more light sources. The multiple beams of light may be reshaped and mixed to provide a first beam of light. A spatial polarization pattern may be applied to the first beam of light to provide a second beam of light. The polarization state of the second beam of light may be split to reflect a third beam of light and reshaped into a fourth beam of light. The fourth beam of light may be introduced as one of the multiple beams of light to provide a fifth beam of light. Indeed, this or a similar system may reduce energy costs associated with additive manufacturing systems. By collecting, beam-combining, homogenizing, and reintroducing unwanted light discarded by a spatial polarization valve or light valve operating in polarization-altering mode, the overall transmitted optical power may be unaffected by the pattern applied by the light valve. This advantageously results in an effective redistribution of the light passing through the light valve into the desired pattern, increasing the luminous intensity in proportion to the amount of area being patterned.

[0042] Combining beams from multiple lasers into a single beam is one way to increase beam intensity. In one embodiment, multiple light beams, each with a different optical wavelength, can be combined using either wavelength-selective mirrors or diffractive elements. In some embodiments, reflective optical elements that are not sensitive to wavelength-dependent refractive effects can be used to direct the multi-wavelength beam.

[0043] The patterned light can be directed using a movable mirror, a prism, a diffractive optical element, or a solid-state optical system that does not require many physical movements. In one embodiment, the magnification and image distance associated with the intensity and pixel size of the incident light on the location of the top surface of the powder bed can be determined for an additive manufacturing 3D print job. One of the multiple lens assemblies can be configured to provide incident light with the magnification on both the first set of optical lenses and the second set of optical lenses, and on the second set of optical lenses that are interchangeable from the lens assembly. Rotation of one or more sets of mirrors mounted on a compensating gantry and a final mirror mounted on the build platform gantry can be used to direct the incident light from the leading mirror onto the location of the top surface of the powder bed. Translational movement of the compensating gantry and the build platform gantry can also enable the distance of the incident light from the leading mirror to the location of the top surface of the powder bed to be approximately equal to the image distance. In practice, this enables rapid changes in the emission size and intensity of the optical beam across the build zone for various powder materials while ensuring high system availability.

[0044] In some embodiments, multiple build chambers, each having a build platform for holding a powder bed, can be used with multiple optical-mechanical assemblies arranged to receive and direct one or more incident energy beams into the build chamber. Multiple chambers enable simultaneous printing of one or more print jobs within one or more build chambers. In other embodiments, movable chamber sidewalls can facilitate removal of prints from the build chamber and enable rapid replacement of powder materials. The chambers can also include adjustable manufacturing process temperature control.

[0045] In another embodiment, one or more build chambers may have a build chamber in which the optics are vertically movable while maintaining a fixed height. The distance between the final optics of the lens assembly and the top surface of the powder bed may be controlled to be essentially constant by pulling the final optics upward a distance equal to the thickness of the powder layer while maintaining the build platform at a fixed height. Advantageously, precise micron-scale movement of the build platform is not required compared to vertically moving the build platform, making it easier to manufacture large, heavy objects. Typically, build chambers intended for metal powders with volumes greater than 0.1-0.2 cubic meters (i.e., heavier than 100-200 liters or 500-1000 kg) will benefit most from maintaining the build platform at a fixed height.

[0046] In one embodiment, a portion of the powder bed layer may be selectively melted or fused to form one or more temporary walls out from the fused portion of the powder bed layer to contain another portion of the powder bed layer on the build platform. In select embodiments, fluid passages may be formed in the one or more first walls to allow for improved thermal management.

[0047] Improved powder handling can be another aspect of an improved additive manufacturing system. The build platform supporting the powder bed can be tiltable, invertable, and vibrable to sufficiently separate the powder bed from the build platform in the hopper. The powder material forming the powder bed can be collected in the hopper for reuse in subsequent print jobs. The powder collection process can be automated, using vacuum or gas injection systems to assist in powder removal or removal.

[0048] Some embodiments of the disclosed additive manufacturing system can be configured to easily process parts longer than the available chambers. A continuous (long) part can be continuously advanced longitudinally from a first zone to a second zone. In the first zone, selected particles of granular material can be fused. In the second zone, unfused particles of granular material can be removed. A final portion of the continuous part can be formed in the first zone, and a first portion of the continuous part can be advanced from the second zone to a third zone while maintaining the first portion in the same transverse and transverse position that the first portion occupied in the first and second zones. Indeed, additive manufacturing and cleaning (e.g., separation and / or reclaiming or recycling of unfused granular material) can be performed in parallel (i.e., simultaneously) at different positions or zones on the part conveyor without the need to stop for removal of the granular material and / or parts.

[0049] In another embodiment, additive manufacturing capabilities can be enhanced through the use of an enclosure that limits the exchange of gas between the interior of the enclosure and the exterior of the enclosure. The gas-tight chamber provides an interface between the interior, containing multiple additive manufacturing chambers and their supporting powder bed melts, and the exterior. A gas management system maintains gaseous oxygen within the interior below a critical oxygen concentration, thereby increasing the flexibility of the types of powders and processes that can be used within the system.

[0050] In another manufacturing embodiment, performance may be improved by having a three-dimensional printer contained within the enclosure, the three-dimensional printer capable of producing parts weighing 2000 kilograms or more. A gas management system may maintain gaseous oxygen within the enclosure at a concentration below atmospheric levels. In some embodiments, a vehicle may transport parts from inside the enclosure to a location outside the enclosure and the airtight chamber through the airtight chamber, since the airtight chamber acts as a buffer between the gaseous environment within the enclosure and the gaseous environment outside the enclosure.

[0051] Other manufacturing embodiments include collecting powder samples in real time in a powder bed fusion additive manufacturing system. An intake system is used for in-process collection and characterization of powder samples. The collection may be performed periodically, and the results of the characterization may result in adjustments to the powder bed fusion process. The intake system may be used incidentally for one or more audits, process adjustments, or actions, such as changing printer parameters or verifying proper use of certified powder materials.

[0052] Yet another improvement to additive manufacturing processes can be provided and described by the use of manipulation devices such as cranes, lifting gantries, robotic arms, or similar objects capable of manipulating parts that are difficult or impossible to move by humans. The manipulation devices can grasp various permanent or temporary additive manufacturing manipulation points on a part so that the part can be repositioned or manipulated.

[0053] FIG. 4A illustrates a beam combining system having multiple wavelength semiconductor lasers and using transmissive imaging optics. Of course, the laser powers and wavelengths discussed, along with selected wavelengths reflected or transmitted by wavelength filters, are exemplary. With appropriate modifications to the placement and use of wavelength filters, more or fewer lasers may be used. In some embodiments, solid-state lasers may be used in place of or in combination with semiconductor lasers. In other embodiments, other types of lasers, such as those discussed with respect to FIG. 1 , may be used, including gas, chemical, or metal vapor lasers. In one embodiment, recycling and reusing waste light may be an alternative to lasers. Waste light available in an additive manufacturing system may be collected, homogenized, and reintroduced into the beamline. Advantageously, recycling and reusing waste light may increase beam intensity and reduce energy costs associated with the system.

[0054] 4A, a first wavelength (1020 nm) semiconductor laser 406 emits a 33.3 kW beam of photons at a corresponding wavelength 407, and a second wavelength (1000 nm) semiconductor laser 408 emits a 33.3 kW beam of photons at a corresponding wavelength 409, which are then combined using a wavelength filter 410 that reflects the 1000 nm photons but transmits the 1020 nm photons. This results in a 66.6 kW combined two-wavelength beam 411. A third wavelength (980 nm) semiconductor laser 412 emits a 33.3 kW beam of photons at a corresponding wavelength 413, which is then combined with beam 411 using wavelength filter 414. Wavelength filter 414 reflects the 980 nm beam but transmits the 1020 nm and 1000 nm beams, resulting in a 99.9 kW three-wavelength beam 415. A fourth wavelength (960 nm) semiconductor laser 417 emits a 33.3 kW beam of photons at a corresponding wavelength 418, which is then combined with beam 415 using wavelength filter 416 that reflects 960 nm but transmits 1020 nm, 1000 nm, and 980 nm, resulting in a 133.2 kW four-wavelength beam 419. This beam enters the optical imaging system with beam dimensions of, for example, 20 mm x 20 mm and 1.1 degree divergence at lens 420. Lens 420 is a series of lenses using two materials, C79-79 and ULE7972, each with a different refractive index, to eliminate the effect of wavelength vibrations on the imaging ability of the beam. The beam exits the optical system at 421, which is a series of lenses using three materials, ZeruDur, ULE7972, and C79-79, to eliminate the effect of wavelength vibrations on the imaging ability of the beam. The beam at 422 has increased in intensity as a result of passing through the optical system and is now at 370 kW / cm, sufficient for additive manufacturing processing of metals such as powdered stainless steel. 2 It has a divergence of 3.67 degrees, is 6mm wide and 6mm high, and produces an intensity of .

[0055] Proper selection of lens materials is necessary for best performance. Transmitting optical elements, such as lens 420, can be made of fused silica. This reduces thermal expansion issues due to the extremely low absorption at wavelengths near 1000 nm and reduces thermal expansion of the lens due to the extremely low thermal expansion coefficient of silica glass. The use of fused silica allows the optical element to withstand much higher strengths without heating and expansion, which can lead to fracture, changes in the glass refractive index, changes in glass shape, and changes in focus. Unwanted optical changes can also be reduced by using two or more materials. Each material can have a different refractive index that varies differently with wavelength. When the appropriate combination is used, there is no change in index and optical path length, and the focal length does not change as a function of wavelength.

[0056] FIG. 4B illustrates another beam combining system 401 that includes a combination of multiple semiconductor lasers and uses reflective imaging optics to reduce the aforementioned problems associated with transmissive optics. As with the beam combining system of FIG. 4A, it should be understood that the laser powers and wavelengths discussed in system 401, along with the selected wavelengths reflected or transmitted by the wavelength filters, are exemplary. With appropriate modifications to the placement and use of wavelength filters, more or fewer lasers may be used. Multiple types of lasers may be used, and in one embodiment, recycling and reusing wasted light may be substituted for lasers. Waste light available in additive manufacturing systems may be collected, homogenized, and reintroduced into the beamline. Advantageously, reflective optics ameliorate the problem of semiconductor laser chirp (wavelength shift over time) during startup transients and throughout their lifetime. The use of reflective optics prevents detuning of the diode laser focus due to this effect, which does not affect the achieved resolution or imaging capabilities. Furthermore, with the use of reflective optics, wavelength differences caused by changes in laser operating temperature do not affect resolution or imaging capabilities.

[0057] 4B, a first wavelength (1020 nm) semiconductor laser 423 emits a 33.3 kW beam of photons at a corresponding wavelength 424, and a second wavelength (1000 nm) semiconductor laser 425 emits a 33.3 kW beam of photons at a corresponding wavelength 426. These beams are combined using a wavelength filter 427 that reflects the 1000 nm photons but transmits the 1020 nm photons, resulting in a 66.6 kW two-wavelength beam 411. A third wavelength (980 nm) semiconductor laser 429 emits a 33.3 kW beam of photons at a corresponding wavelength 430. These beams are combined using a wavelength filter 431 that reflects the 980 nm beam but transmits both 1020 nm and 1000 nm, resulting in a 99.9 kW three-wavelength beam 432. A fourth wavelength (960 nm) semiconductor laser 433 emits a 33.3 kW beam of photons at the corresponding wavelength 434. These beams are combined using a wavelength filter 432 that reflects 960 nm but transmits 1020 nm, 1000 nm, and 980 nm, resulting in a 133.2 kW four-wavelength beam 436. This beam enters the optical imaging system, for example, at reflective optics 437 with a beam size of 20 mm x 20 mm and a divergence of 1.1 degrees. The reflective optics have no wavelength dependency and do not affect the beam combining capabilities. The beam exits the beam combining optical system 401 at reflective optics 438. The beam 439, having increased in intensity as a result of passing through the optical system, is currently at 370 kW / cm, sufficient for additive manufacturing processes of metals such as powdered stainless steel. 2 It has a divergence of 3.67 degrees, is 6mm wide and 6mm high, and produces an intensity of .

[0058] 4C illustrates another embodiment of a beam combining system 440 that combines beams 443 from same or multiple wavelength lasers 442 using diffractive imaging optics 444. The diffractive optical element may be shaped or patterned to receive the beams 443 and reflect them along substantially the same beam axis. Of course, while a diffractive optical element that reflects the beams is shown in FIG. 4C, in other embodiments the diffractive optical element may transmit the beams, or a combination of reflective, transmissive, or other suitable beam steering optical assemblies or components may be used.

[0059] 5A is a reflective optically addressable light valve system 500A useful in additive manufacturing systems as disclosed herein. Reflective light valves do not need to transmit light through a transparent semiconductor for photopatterning, where even small amounts of absorption can cause unwanted and catastrophic heating at high average power levels. Reflective light valves also allow for easier cooling on the reflective surface, as well as cooling on the side opposite the write and read beams.

[0060] As shown in FIG. 5A, reflective optically addressed light valve system 500A is capable of patterning an energy beam and is composed of a highly transmissive layer 501, a twisted nematic (TN) liquid crystal layer 502, and a photoconductor layer 503. The highly transmissive layer is optically transparent to 1000 nm and 700 nm light and is made from a glass substrate (C79-79 fused silica) 501 with anti-reflective coatings on both sides 504 and 506. Indium tin oxide (ITO) conductive films are used for highly transparent layers 501 and 505. Layer 502 is anchored to 506 and 510 through anchoring substrates 507 and 509. The precise spacing of 502 is given by the dimensions of spacer balls 508, which define a 2.5 micron gap that adjusts the maximum contrast ratio when passing 1000 nm light in a double pass. Layer 503 is made of a single crystalline silicon semiconductor with a highly reflective dielectric film applied at 510 that is reflective at 1000 nm but transparent to 700 nm. Layer 511 is another layer of ITO with attached solder points 512 and connected to layer 505 through another solder point 513 via AC voltage source 514. A patterned writing beam of light is emitted from a floodlight source at 700 nm and is incident on 503 after transmitting through 504, 501, 505, 506, 507, 502, 509, and 510. When the writing beam hits 503, electrons move from the valence band to the conduction band, greatly increasing the local conductivity of 503 and allowing current to flow from 511 through 503, 510, 509, 502, 507, and 506 to 505. When a current is passed through the TN liquid crystal 502, it induces a rotation of the liquid crystal 502, causing a polarization rotation of the transmitted light. A "readout" beam 516 is p-polarized and is transmitted through 504, 501, 505, 506, 507, 502, and 509 before impinging on 510, at which point it is transmitted back through 509, 502, 507, 506, 505, 501, and 504 to exit light valve system 500A. This beam then impinges on polarizer 517, which reflects the s-polarized light resulting in reflected beam 518 and transmits the p-polarized light resulting in transmitted beam 519.Even though the absorption in the device is very low, the HR film 509 is not completely reflective and some energy is absorbed. This energy is removed by radiation, conduction or convection cooling 520.

[0061] Figure 5B illustrates another reflective optically addressed light valve 500B with single-sided cooling, in which the write and read beams are incident from different sides. The valve is composed of a highly transmissive layer 521, a twisted nematic (TN) liquid crystal layer 522, and a photoconductor layer 523. The highly transmissive layer is made of a glass substrate (C79-79 fused silica) 521 that is optically transparent to 1000 nm and 700 nm light and has anti-reflective coatings on both sides 524 and 526. Indium tin oxide (ITO) conductive films are used for 521 and 525. Layer 522 is anchored to 526 and 530 through anchoring substrates 527 and 529. The precise spacing of 522 is given by the dimensions of spacer balls 528, which define a 2.5 micron gap that adjusts the maximum contrast ratio when passing 1000 nm light in a double pass. Layer 523 is made of a single crystalline silicon semiconductor with a highly reflective dielectric film applied at 530 that reflects at 1000 nm. Layer 531 is another layer of ITO with attached solder points 532 and connected to layer 525 through another solder point 533 via AC voltage source 534. A patterned writing beam of light is emitted from a floodlight source at 700 nm and is incident on 523 after being transmitted through an accompanying convective / conductive substrate 540 and through ITO film 531. When the writing beam strikes 523, electrons move from the valence band to the conduction band, greatly increasing the local conductivity of 523 and allowing current to flow from 531 through 523, 530, 529, 522, 527, and 526 to 525. When current flows through TN liquid crystal 522, it induces a rotation of the liquid crystal 522, causing a polarization rotation of the transmitted light. "Readout" beam 536 is p-polarized and is transmitted through 524, 521, 525, 526, 527, 522, and 529 before impinging on 530, at which point it is transmitted back through 529, 522, 527, 526, 525, 521, and 524 to exit the light valve. This beam then impinges on polarizer 537, which reflects s-polarized light resulting in reflected beam 538, and transmits p-polarized light resulting in transmitted beam 539. Even though absorption in the device is very low, the HR film 529 is not completely reflective and some energy is absorbed.This energy is removed by radiative, conductive, or convective cooling 540 .

[0062] To aid in a better understanding and appreciation of various system embodiments, including alternative or additional optical systems, chamber designs, powder processing systems and methods, structure configurations, part creation and manipulation, use of multiple additive manufacturing systems, and high-throughput manufacturing methods suitable for automated or semi-automated factories, the following disclosure will aid in understanding and appreciating various novel aspects of the disclosed systems, methods, and structures.

[0063] FIG. 6 illustrates the layout of an exemplary apparatus 400 for recycling laser light in an additive manufacturing process. Apparatus 600 may include one or more light sources, such as, by way of example and not limitation, light sources 601, 602, and 603. In some embodiments, light sources 601, 602, and 603 may include lasers. Alternatively, other types of light sources, such as solid-state lasers, may be utilized. In some embodiments, each or at least one of light sources 601, 602, and 603 may emit 11.1 kW of p-polarized light at 700 nm and may have dimensions of 7.9 cm x 7.9 cm and a divergence of 7.6 mrad. The beams of light emitted by light sources 601, 602, and 603 may be multiplexed with one another by a first optical assembly 604 that includes a series of mirrors, thereby allowing the beams to be as close together as possible. These beams may then be reshaped and mixed by optical device 605, resulting in beam 6, which is 33.3 kW, 4.7 cm x 4.7 cm, and 70.4 mrad divergence. Beam 606 may be incident on a spatial polarization valve, which may apply a spatial polarization pattern map onto beam 606 by rotating the polarization of selected pixels from p-polarized to s-polarized to provide beam 8. With appropriate modifications, selected pixels may be formed by rotating from s-polarized to p-polarized to provide a beam. In yet other embodiments, grayscale pixels may be created by partial rotation. Upon interacting with polarizer 609, the s-polarization state of beam 608 may be reflected into beam 610. The exact fraction may be given as a function of the fraction of light patterned by spatial polarization valve 607. Beam 10 may enter a second optical assembly 611, which may include a series of mirrors, reshaping lenses, wave plates, or other optical components, and may be changed into a 7.9 cm by 7.9 cm beam, which may then be reintroduced into the system as if it were light source 612 along with the original one or more light sources 601, 602, and 603.

[0064] A process for light recycling may include multiplexing multiple beams of light, including at least one beam of light from one or more light sources 601, 602, and 603. The multiple beams of light may be reshaped and mixed to provide a first beam of light. A spatial polarization valve 607 of the device 600 applies a spatial polarization pattern onto the first beam of light to provide a second beam of light. A polarizer 609 of the device 600 splits the polarization state of the second beam of light 608 to reflect a third beam of light (e.g., beam 610). A second optical assembly 611 of the device 600 reshapes the third beam of light into a fourth beam of light, which is directed to the first optical assembly 604 as one of the multiple beams of light to emit through the polarizer 609 and provide a fifth beam of light (e.g., beam 613) that is not reflected by the polarizer 609.

[0065] FIG. 7 illustrates an exemplary optical assembly 700 for polarization combining to achieve (in the limit) twice the original semiconductor laser intensity in accordance with the present disclosure. Semiconductor lasers are typically polarized approximately 70-90% in one polarization state. When polarization rotation methods are used to pattern light, 10-20% of the light in the unwanted polarization states would potentially be useless (wasted). To avoid this loss, polarization combining and patterning can be used to either improve transmission efficiency or increase the resulting intensity by a factor of two, or both.

[0066] In one embodiment, two or more beams of light having a first intensity are provided, each of the two or more beams of light being polarized and having a majority polarization state and a minority polarization state. An individual polarization pattern is applied to each of the two or more beams of light, and the two or more beams of light are combined to provide a single beam of light having a second intensity greater than the first intensity. In another embodiment, two or more lasers of any polarization state can be used. A polarizer is used to split the beams into their respective polarization states, spatially stacking the beams with corresponding polarization states close to each other by spatial positioning to create two effective beams. These two beams of different polarization states then pass through an optical modulator associated with their projected polarization states, and a polarization state pattern is then applied to the beams, followed by beam combination by polarization combining. This method can be used for all light in the process, allowing for higher utilization of laser light, thereby achieving better system efficiency and minimal or no losses due to changes in polarization state.

[0067] Optical assembly 700 may include some or all of the components shown in FIG. 7 , described below. Light sources 701 and 702 are each used as high-power photon sources. In some embodiments, light sources 701 and 702 may be semiconductor laser arrays with 33.3 kW output power each, emitting photons at 1000 nm that are shaped and mixed into a 20 mm wide by 20 mm square beam. The emitted light may be 90% polarized in the majority state p, resulting in light beams 703 and 704. Emitted light beams 703 and 704 may be incident on polarizers 705 and 706, respectively. Polarizers 705 and 706 may reflect the minority state s-polarized light to produce light beams 709 and 7010, which may be incident on beam dump 7011. Polarizers 705 and 706 may transmit p-polarized light to produce light beams 706 and 707, which may then be incident on polarization-rotating optically addressed light valves 712 and 713, respectively. Light valves 712 and 713 may each have the same image applied to light beams 706 and 707 to create a polarization pattern, spatially flipping 20% ​​of the "pixels" from p-polarized to s-polarized light in the desired pattern to produce light beams 714 and 715. Beams 714 and 715 may then be incident on polarizers 716 and 717, respectively. Polarizers 716 and 717 may reflect s-polarized light to produce light beams 718 and 719, which contain 20% of the energy and may be emitted to beam dump 720. Polarizers 716 and 717 may transmit p-polarized light to produce light beams 721 and 722. Beam 722 may be incident on half-wave plate 723, which rotates the polarization of all photons by half a wavelength, thereby rotating p-polarized light to s-polarized light to produce light beam 724. Beams 721 and 724 may be incident on mirrors 725 and 726, respectively, to produce light beams 727 and 728. Beam 727 may be incident on mirror 729 to produce beam 730, and on p-polarized polarizer 731.S-polarized light beam 728 may be incident on polarizer 731, which may reflect the s-polarized light of beam 728 and transmit the p-polarized light of beam 730 to produce light beam 732. Beam 732 may be twice as intense as a single polarization state beam from light source 701 or 702, for a total initial intensity of 1.8 times the original intensity due to the initial 90% polarization, and proportionally less than that intensity due to the 20% polarization map image applied by light valves 712 and 713. The total transmitted intensity in beam 732 may be 1.44 times the initial intensity for a total transmitted power of 47.52 kW emitted. Imaged onto the original 20 x 20 mm square, the final intensity may be 11.88 kW / cm² if the divergence angle is maintained.

[0068] In powder bed fusion additive manufacturing (PBFM), a source image of an optical beam of sufficient energy is directed at a location on the top surface (print surface) of a powder bed to form a complete object when the powder material is processed (with or without chemical bonding). The resolution (or image size) of the optical system used in PBFM depends on whether the focal plane of the final optical system of the optical system or imaging system coincides with the print surface, and whether the distance between the lens for the optical system performing the imaging operation and the image surface is sufficiently constant for a given lens configuration. To be able to print large objects in PBFM, precise control of the image position on the print surface and the distance between the lenses is required to maintain the resolution or image size at all possible positions on the top surface of the powder bed. Different powder materials, with their individual thresholds of bonding energy, may require different intensities or energies of the optical beam. If a change in intensity is required when the powder type or powder size distribution is changed, the optical system may need to be shut down to reattach or reposition the imaging lens.

[0069] To address issues related to intensity and resolution changes, the process is described as follows. FIG. 8 is a flowchart 800 illustrating steps for using a dynamic optical assembly, which may include an image relay gantry. In step 810, information is acquired or determined to find the minimum resolution (pixel size of the incident light) for an object to be printed in a powder bed fusion additive manufacturing system. According to the intensity and resolution requirements, a magnification of the incident light, including the image information and the image distance of the dynamic optical assembly, is calculated. The magnification may translate a first size of the image at a previous image plane to a second size of the image at the print plane (top surface of the powder bed). The incident light may originate from an energy source or may pass through a previous image plane where image information may be created. Process 800 may include storing geometric data of the object and positional and rotational control data of the dynamic optical assembly.

[0070] In step 820, the process 800 may include configuring the mechanical assembly and one or more lens assemblies to achieve the magnification obtained in 810 appropriate for the powder material. Configuring one of the mechanical assembly and lens assemblies may include rotating the mechanical assembly, replacing a second set of optical lenses, or removing the second set of optical lenses.

[0071] In step 830, multiple rotations may be performed to direct the incident light from the previous image plane to the print plane at a desired location on the print plane (e.g., the top surface of the powder bed) at each successive step of powder bed fusion additive manufacturing. In step 840, the dynamic optical assembly may perform multiple translational movements to maintain a constant image distance from the previous image plane to all locations on the print plane (e.g., the top surface of the powder bed) at each successive step of powder bed fusion additive manufacturing. Vertical movement of the powder bed or the optical assembly may be used to maintain a constant separation of the powder bed with respect to the final lens.

[0072] An apparatus for performing process 800 may include a layer of powder material dispensed onto the top surface of a powder bed supported by a build platform. A source image of incident light positioned at a leading image plane is incident on a lens assembly in a barrel. The lens assembly may be configured by rotating the barrel to replace a second set of optical lenses, removing the second set of optical lenses, using a dynamic lens that changes shape, electronic lens exchange, a beam redirection system, an electro-optically controlled refractive beam steering device, or a combination thereof to have the appropriate magnification for the powder material. An object image, different in size from the source image, appears after passing through the lens assembly and is modified according to the magnification of the lens assembly. The beam containing the image information is incident on a leading mirror and directed to a mirror mounted on a compensation gantry, where it reflects off a mirror and subsequently incident on a final mirror mounted on the build platform gantry. The final mirror directs the beam containing the image information through a final lens toward the top surface of the powder bed, where the object image is recreated and magnified at an image plane on which it can be formed. The powder material on the powder bed may melt to form the shape of the object image. The build platform gantry then moves to the next position until the designated location on the top surface of the powder bed is bonded for that layer. A new layer of powder material is again dispensed, and the build platform may move downward a distance equal to the thickness of the layer of powder material to maintain a constant distance to the build platform gantry. As the additive manufacturing process continues, the cycle begins for the new layer.

[0073] FIG. 9A illustrates an example scenario 900 of a midpoint in a powder bed fused additive manufacturing printing process according to the present disclosure. The example scenario 800 shows moving a component upward in a build chamber while controlling depth of field with a fixed build platform 930. The build platform 930 may have a 1 meter by 0.5 meter area into which powder can be dispensed during a print cycle. In one embodiment, the build platform 930 moves to a position directly below a gantry table 905 and is fixed in place. Vertical columns 903(1)-903(4), each 3 meters high, support a gantry 907 mounted on the gantry table 905. A powder dispensing unit 910, a compression feature 911, and a mirror 917 may be mounted on the gantry 907 for translational movement in the horizontal plane. The gantry table 905 is shown at a higher position than the powder bed 920 in FIG. 8 to reflect that printing may be in progress. The powder bed 920 contains both the powder layer and the printed object in various stages of completion. A new layer of powder 925 is dispensed from a powder dispensing unit 910, which includes powder spreading and compaction. An incident beam 921 from a print head (not shown) may reflect off a mirror 917 to become a beam 922 that strikes a location 923 of the new layer of powder 925. Printing can occur by melting, sintering, or fusing the powder at the location 923 of the new layer of powder 925. The distance between the mirror 917 and the location 923 of the new layer of powder 925 is the depth of field, which must be tightly controlled to meet resolution requirements. Arrow 970 indicates the upward movement of the gantry 907, the powder dispensing unit 910, the mirror 917, and, in some embodiments, the gantry table 905, which supports the enclosed chamber or walls. During this process, the build platform 930 is fixed in position, and the gantry 907 (and / or the chamber and chamber walls) move relative to the build platform 930. This arrangement is particularly useful in the embodiments described below where the build platform is large and may need to support large amounts of heavy material that does not easily move vertically with the required precision.

[0074] In some embodiments, the build platform 930 in example scenario 900 may have an area greater than 0.25 square meters. Alternatively, the build platform 930 in scenario 900 may have an area greater than 0.5 square meters. Alternatively, the build platform 930 in scenario 900 may have an area greater than 1 square meter. Alternatively, the build platform 930 in scenario 900 may have an area greater than 5 square meters. Alternatively, the build platform 930 in scenario 900 may have an area greater than 10 square meters. Alternatively, the build platform 930 in scenario 900 may have an area greater than 50 square meters.

[0075] In some embodiments, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 10 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 50 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 100 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 500 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 1000 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 2000 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 5000 kilograms. Alternatively, the powder bed 920 including the printed object of exemplary scenario 900 may have a mass greater than 10,000 kilograms.

[0076] In some embodiments, the build platform 930 of the example scenario 900 may have an area greater than 0.25 square meters, and the powder bed 920 containing the print object of the example scenario 900 may have a mass greater than 10 kilograms.

[0077] Powder bed fusion technology processes powder materials to form whole objects from metal, ceramic, and plastic powders. Sufficient energy is required to bring the powder to its respective melting / sintering / alloying temperature, or phase change temperature. If the powder material starts near the phase change temperature, less energy may be required to complete the phase change. Powder bed fusion additive manufacturing may benefit from pre-heating the powder bed to reduce the amount of energy delivered by the laser or other energy source. This allows for the use of lower intensity lasers and shorter dwell times to bond the powder, improving processing speed.

[0078] Post-processing heat treatment may be required for some powder materials, such as metals, to relieve stress concentrations and increase mechanical strength. Post-processing heat treatment may include controlled temperature annealing or rapid cooling to enhance desired mechanical or electrical properties. Powder pre-heating and post-processing heat treatment may be achieved by incorporating heating / cooling elements / temperature sensors inside the build chamber walls / inside the build platform and controlling the heating / cooling rate with a feedback algorithm. Heat loss may be reduced by using insulating materials inside the build chamber walls.

[0079] Suitable thermal management systems for use with the desired powder bed and chamber are discussed with respect to FIG. 9B . FIG. 9B illustrates an exemplary arrangement of a laser-based powder bed fusion additive manufacturing system 900B according to an embodiment of the present disclosure. The system 900B includes both an energy source 950 and an energy beam steering system / driver 955 as part of a print head 910B. Opto-mechanical assemblies 930(1)-930(N) can distribute the energy beam to the print head 910B via the system 900B. Data input, monitoring, control, and feedback control using various sensors are enabled by a processor 901 and memory 940. These systems can include three-dimensional object data 941, print head control 942, build platform control 943, opto-mechanical assembly control 944, and build chamber control 945.

[0080] The laser-based powder bed fusion additive manufacturing system 900 may include one or more build chambers. For illustrative purposes and not limitation, one or more build chambers of the system 900 are shown in FIG. 9B as build chambers 920B(N), where N is a positive number greater than or equal to 1. The build chambers 920B(1)-920B(N) may include powder dispensing units 922(1)-922(N) for dispensing powder material and build platforms 924(1)-924(N) for supporting a powder bed formed by the powder material. Each of the build chambers 920B(1)-920B(N) may have a different size and may be interchangeable within the powder bed fusion additive manufacturing system 900. The build chambers 920B(1)-920B(N) may have movable doors to facilitate powder removal from the build chambers 920B(1)-920B(N) after build. Build chambers 920B(1)-920B(N) may be sealed in an atmosphere during powder bed fusion additive manufacturing, which may include, but is not limited to, vacuum, air, nitrogen, argon, or helium.

[0081] In some embodiments, the walls / ceilings of the build chambers 920B(1)-920B(N) may incorporate heating / cooling elements 926(1)-926(N) and temperature sensors 928(1)-928(N) to control the thermal environment inside the build chambers 920B(1)-920B(N).

[0082] In some embodiments, the heating / cooling elements 926(1)-926(N) may be heat exchangeable flow channels. Fluids may be heated or cooled outside the build chambers 920B(1)-920B(N) or may exchange heat with the walls / ceiling by moving the fluid through the flow channels. Fluids may include, but are not limited to, oil, water, steam, air, nitrogen, argon, or coolants.

[0083] In some embodiments, the heating / cooling elements 926(1)-926(N) may be resistive heating elements and thermoelectric cooling elements, respectively.

[0084] In some embodiments, the temperature sensors 928(1)-928(N) may be thermocouples embedded inside the interior walls / ceilings of the build chambers 920B(1)-920B(N).

[0085] In some embodiments, the temperature sensors 928(1)-928(N) may be infrared cameras embedded inside the interior walls / ceilings of the build chambers 920B(1)-920B(N).

[0086] In some embodiments, each of the build chambers 920B(1)-920B(N) may include heat shields on the walls / ceiling of the build chambers 920B(1)-920B(N) to reduce heat loss.

[0087] In some embodiments, the build chambers 920B(1)-920B(N) may include low thermal conductivity materials as wall / ceiling components.

[0088] In some embodiments, each of the build chambers 920B(1)-920B(N) may be vertically movable or may be fixed at a predetermined height during powder bed fusion additive manufacturing. The build platforms 924(1)-924(N) may be different sizes and may support variable powder bed masses. The build platforms 924(1)-924(N) may be removable from the build chambers 920B(1)-920B(N) by rails, wheels, or other means.

[0089] 10 describes a method for minimizing powder volume demand during a build operation. Process 1000 may be utilized to implement printing variable print chamber walls for powder bed fusion in a powder bed fusion additive manufacturing system according to embodiments of the present disclosure. At 1010, process 1000 includes dispensing powder material to form a first layer of a powder bed on a support surface of a build platform.

[0090] At 1020, process 1000 may include selectively melting a portion of the first layer of the powder bed to form one or more first walls outside the melted portion of the first layer of the powder bed. The one or more first walls may comprise another portion of the first layer of the powder bed on the build platform. In some embodiments, the one or more first walls may comprise multiple walls surrounding an area within the build platform to create an area devoid of powder material. At 1030, process 1000 may include dispensing powder material to form a second layer of the powder bed on the first layer of the powder bed. At 1040, process 1000 may include selectively melting a portion of the second layer of the powder bed to form one or more second walls outside the melted portion of the second layer of the powder bed. The one or more second walls may comprise another portion of the second layer of the powder bed.

[0091] In some embodiments, the one or more first walls may include a plurality of first walls that surround another portion of the first layer of the powder bed across a first area of ​​the build platform, and the one or more second walls may include a plurality of second walls that surround another portion of the second layer of the powder bed across a second area of ​​the first layer of the powder bed, the second area being smaller than the first area.

[0092] In some embodiments, the one or more first walls may include at least one wall along at least one of the boundaries of the build platform. Additionally, leaving one or more of the boundaries of the build platform may border one or more structural walls. In some embodiments, process 1000 may further include causing relative movement between the build platform and the one or more structural walls in a direction perpendicular to the support surface of the build platform. Furthermore, process 1000 may include dispensing powder material onto the first layer of the powder bed and the one or more first walls to form a second layer of the powder bed. Furthermore, process 1000 may include selectively melting a portion of the second layer of the powder bed to increase the height of the one or more first walls.

[0093] In another embodiment, the temporary wall can be fabricated with channels, cavities, or porous portions (hereinafter referred to as "fluid passages") capable of supporting fluid flow. The fluid passages can be open or partially closed and can be configured to interface with external pipes, hoses, sprayers, or other fluid delivery systems. To improve thermal management, air, nitrogen, water, high temperature or silicone oil, or other suitable gases or liquids can be circulated or otherwise moved through the fluid passages. Thermal management can include rapid cooling and / or controlled cooling, where the fluid can be circulated (e.g., through channels formed in the temporary wall) or sprayed, dripped, or splashed against the porous outer wall portion, for example.

[0094] The proposed scheme may be implemented in a powder bed fusion additive manufacturing system for printing metal, plastic, or ceramic parts. The use of the proposed scheme may be more specifically defined with respect to its use in the print bed portion of the machine on the receiving side of the laser or electron beam. In various embodiments of the present disclosure, one or more energy sources of a print head of a powder bed fusion additive manufacturing system may be controlled to print the walls of a build chamber. This may enable the elimination of chamber boundary walls and the creation of subset regions. The existence of subset regions / volumes / spaces may aid in minimal powder usage, allowing the creation of volumes devoid of powder. This is particularly beneficial when working with expensive materials such as gold, silver, and copper, and also when working with very large objects where excess powder may comprise a significant portion of the standard print volume. Under the proposed scheme, powder may be selectively dispensed across the build area in predefined walled regions created during the additive manufacturing process.

[0095] Because the print bed and print head are typically separated vertically for successive layers, a print chamber wall is needed to support the previously deposited layer, including the powder and print material. One example involves building into a tight-fitting wall. Another example involves printing an outer wall (and possibly its structural support) between each layer. This wall may be cut away and recycled after each print.

[0096] In some embodiments, many or all of the walls may be printed raised to reduce the powder bed area for the powder layer, using the "tub" formed by the walls to capture powder that falls outside the printed walls.

[0097] In some embodiments, the raised wall may not be intended for the entire perimeter. For example, a connection point for a forklift or other material handling equipment may be needed when the powder bed is initially loaded into the print station and when the completed bed (powder and prints) is subsequently lifted out. Printing a limited wall for this area provides the remaining bed required to support the powder during the print cycle. Material handling equipment may subsequently "drill" through this printed wall to gain connection to the lift point. In some embodiments, lift locations may be determined prior to construction by an algorithm or user configuration and are built into the wall at strategic locations.

[0098] The printed walls do not have to match the shape of the print table, nor do they have to exactly match the walls printed in the previous layer. This, along with appropriate powder dispensing equipment and logic, allows for dispensing just enough powder to cover the walled areas where powder is needed. Advantageously, this can keep weight and / or powder down per layer for a significant amount of time.

[0099] FIG. 11A illustrates an example scenario 1100 in which a powder bed 1120 is formed on a build platform 1130 according to the present disclosure and may be utilized. The build platform 1130 may have an area of ​​0.25 square meters and may support a powder bed 1120 of powder material, which may be 0.5 meters deep inside the build chamber 1110. The scenario 1100 may be at the end or middle of a print cycle. Below the build platform 1130 is a hopper 1140 with sloped walls that may be at a 45-60 degree angle relative to the horizontal plane on which the build platform 1130 is positioned. In some embodiments, the hopper 1140 may include an auger 1150.

[0100] FIG. 11B illustrates another example scenario 1101 depicting the separation of the powder bed 1121 from the build platform 1131. Scenario 1101 may be at the end of a print cycle or in the middle of a print cycle that is aborted for various reasons. Inside the build chamber 1111, the build platform 1131 supporting the powder bed 1121 may be tilted more than 90 degrees from a horizontal position. Gravity due to the weight of the powder bed 1121 causes the powder material and printed objects embedded in the powder bed 1121 to fall into a hopper 1141. The build chamber 1111 may include a vacuum cleaner 1160 and a high-pressure jet 1162 so that most of the powder can be collected in the hopper 1141. The vacuum cleaner 1160 and a gas jet 1162 may be used to remove unwanted powder remaining on the build platform 1131 after tilting the build platform 1131. The hopper 1141 may have sloped walls to help direct the powder to the bottom of the hopper 1141. The hopper 1141 may include an auger 1151 .

[0101] The process may include controlling a powder dispensing assembly to dispense multiple layers of powder material in forming a powder bed during a print cycle. Vertical movement of the powder dispensing assembly may be controlled to maintain a constant distance from the powder bed. The vertical movement may result in movement of the powder dispensing assembly (e.g., upward) away from the powder bed by a distance equal to the thickness of the dispensed powder layer after portions of the dispensed powder layer have bonded together. To remove the remaining powder, movement of the build platform may include rotating, tilting, inverting, shaking, vibrating, and / or micro-vibrating. As a result of these movements, the powder bed on the build platform may fall into a hopper below the build platform due to the weight of the powder bed. A vacuum system, mechanical arm, and / or gas atomizer may be used to further remove the remaining powder on the build platform. Therefore, most of the powder material may be collected in the hopper for recycling or storage. In some embodiments, an auger and / or conveyor may be used to transport the collected powder in the hopper to one or more storage chambers. In another process embodiment, the bulk of the powder material can be sealed in one or more reservoir chambers with an atmosphere suitable for the powder material, which may include vacuum, air, nitrogen, argon, helium, other inert gases, or noble gases.

[0102] 12A and 12B illustrate a system for manufacturing long parts. Many current 3D printers have significant and frequent downtime when the build chamber must be emptied of powder and printed parts and reset for the next print job. In the following description, a unified coordinate system 1211 is defined. Accordingly, some systems may correspond to mutually orthogonal longitudinal, lateral, and transverse directions 1211a, 1211b, and 1211c. The longitudinal direction 1211a may correspond to the long axis of the system. Thus, during additive manufacturing, the long axis of the long part 1210 may be fully aligned with the longitudinal direction 1211a. The transverse direction 1211b may be combined with the longitudinal direction 1211a to define a horizontal plane. That is, both the longitudinal and transverse directions may extend within a horizontal plane. The transverse direction 1211b may extend up and down in line with gravity.

[0103] In select embodiments, systems and methods according to the present invention may enable or support fully continuous additive manufacturing without the downtime described above, as evident with reference to FIGS. 12A and 12B . This may be achieved by partially manufacturing the part 1210. For example, the system may (1) manufacture a first section 1212 a of the part 1210, (2) advance the part 1210 a selected distance via a lower conveyor 1216, (3) manufacture a second section 1212 b of the part 1210, (4) advance the part 1210 a selected distance via a lower conveyor 1218, and (5) repeat until all sections of the part 1210 are completed. In this manner, additive manufacturing and cleaning (e.g., separating and / or recycling unused or unfused granular material) may be performed in parallel (e.g., simultaneously) at separate locations or zones on the conveyor. Therefore, additive manufacturing according to the present invention does not need to be stopped for removal of particulate material and / or parts.

[0104] The system may define or include multiple zones 1236a-c. Different operations may be performed in different zones. In select embodiments, the different zones may correspond to different positions along the conveyor. Thus, the conveyor may advance (translate in the direction indicated by arrow 1232) the part through various zones of the system. In some embodiments, the system may include three zones 1236a, 1236b, 1236c. The first zone 1236a may correspond to, include, or span the portion of the conveyor where additive manufacturing occurs. Thus, the first zone 1236a may correspond to an area on the conveyor where various layers of granular material 144 are produced and where the granular material maintains intimate contact with the part.

[0105] The second region 1236b may directly follow the first region 1236a. The second region 1236b may be characterized by a substantial portion of the unfused portion of the granular region leaving the part. For example, in the second region 1236b, one or more walls may be terminated or removed such that the unfused portion of the granular material can no longer be contained in the lateral direction 1211b. As a result, some of the unfused portion of the granular material may spill off the sides of one or more plates, a conveyor, or the like. The spilled granular material may fall into one or more containers where it can be collected or recycled.

[0106] The third region 1236c may directly follow the second region 1236b. The third region 1236c may be characterized by the revealing of a portion of the part 1210 within the third region 1236c (e.g., completely, substantially, or partially revealed by the removal or displacement of a substantial portion of the unfused portion of the granular material) without the part 1210 changing its position in the lateral and transverse directions 1211b, 1211c.

[0107] For example, in some embodiments, the leading portion of the part 1210 may reach the third zone while the trailing portion of the part 1210 is still being manufactured within the first zone 1236a. Thus, in select embodiments, a conveyor, one or more plates, one or more temporary supports 1223, or one or more walls, etc., or any combination or sub-combination thereof, may cooperate to maintain the leading portion of the part 1210 in the same position in the lateral and transverse directions 1211a, 1211c as the leading portion occupying the first zone 1236a and the second zone 1236b. Therefore, the position of the leading portion of the part 1210 may not unduly disrupt, distort, etc., the additive manufacturing occurring on the trailing portion of the part 1210 in the first zone 1236a.

[0108] In select embodiments, all of the unfused portions of the granular material outside of the part 1210 may be removed in the second zone 1236b, or in some combination of the second and third zones 1236b, 1236c. However, in some alternative embodiments, the floor may be removed from the conveyor with all four walls intact. Thus, all or some of the unfused portions of the granular material may be removed at a station spaced some distance away from the first zone 1236a.

[0109] In another embodiment, a ramp may be used to transition from a lower section or region to a subsequent higher section or region. For example, a ramp allows a trailing wall corresponding to a lower section to be built higher by an additive manufacturing process than the majority of the lower section, so that the trailing wall can become the leading wall of a subsequent higher section. Building a ramp may be much faster than constructing a finished layer (e.g., a layer covering the entire lower section) if only the trailing wall is built.

[0110] The slope may include multiple layers of granular material that gradually change length in one or more directions (e.g., the longitudinal direction 1211a). For example, within the slope, each successive layer may be shorter in length than the immediately preceding layer. The angle that the slope makes with respect to the horizontal may be less than the critical angle of repose for the granular material. Thus, the granular material forming the slope may be stable and may not peel or move due to gravitational accelerations experienced by it.

[0111] During operation, a first layer of particles of the granular material may be dispensed, and radiant energy may be directed at all particles in the first layer that form a portion of the selected particles. A second layer of particles of the granular material may be dispensed over the top of the first layer, and radiant energy may be directed at all particles in the second layer that form a portion of the selected particles. The first layer may define a first plane, and the second layer may define a second plane that is parallel to the first plane. In some embodiments, the first and second planes are both horizontal. In other embodiments, the first and second planes both extend at an angle relative to the horizontal that is greater than zero and less than or equal to a critical angle of repose of the granular material, forming a slope.

[0112] 13A illustrates an additive manufacturing system 1300 that includes a powder chamber 1302 with a powder bed 1304. The system 1300 may also include a processing platform 1320, which is a designated processing area, another powder chamber, a coating station, a conveyor, a shipping container, or other necessary manufacturing system components. The system 1300 also includes a robotic arm 1310 with a remote manipulator 1312 capable of grasping a part 1330 with its additive manufacturing operation point 1332. A sensor system 1334 may be mounted on the robotic arm 1310 or may be mounted on, in, or near the powder chamber 1302.

[0113] While a single robotic arm with six levels of freedom with clamping appendages is the illustrated manipulation device, other automated, mechanical, or manual embodiments may be used. For example, a crane, lift, hydraulic arm, clamp, track or rail, pinning device, or any other type of manual or automatic controllable manipulation device may be used. The manipulation device may be mounted beside, on, near, or within the powder chamber 1302. Alternatively, the manipulation device may be movably mounted on a rail located above, near, or within the powder chamber. In some embodiments, multiple manipulation devices may be used.

[0114] The manipulation device may include a position, depth, laser scanning, or similar sensor system 1314. The sensor may be mounted on or near the remote manipulator, or may be mounted on, near, or within the robotic arm, powder chamber, or processing platform 1320. In some embodiments, the sensor may be moved on a hinged rail, hydraulic piston, or other suitable actuator used to rotate, lift, depress, vibrate, or laterally scan the sensor. In some embodiments, a conventional RGB CMOS or CCD sensor may be used alone or in combination with a dedicated depth sensor or optical edge tracking detection system. Embodiments may be selected to improve the three-dimensional location of the part, including identification and use guides, markers, or other detectable positioning indicia.

[0115] 13B illustrates the system described with respect to FIG. 13A with a robotic arm 1310 that lifts and reorients a part 1330 through one of its additive manufacturing operation points 1332. In some embodiments, the part 1330 can be lifted, rotated, translated linearly, and placed back onto the powder bed 1304 for further processing.

[0116] 13C illustrates the system described with respect to FIG. 13A with a robotic arm 1310 that lifts and reorients a part 1330 through one of its additive manufacturing operation points 1332. In this embodiment, the part 1330 can be lifted, rotated, and placed back onto the processing platform 1320 for further processing.

[0117] FIG. 14 illustrates a part 1400 that includes various possible additive manufacturing robotic manipulation points. Part 1400 supports various protruding structures (i.e., 1402, 1404, 1406, 1408, and 1414) along with internal structures or cavities (i.e., 1410, 1412, and 1416) that can serve as robotic manipulation points. In the illustration, structure 1402 is a crescent-shaped tab with two narrow connection points to part 1400. The tab portion allows for easy engagement by a remotely operated machine with a pinching or gripping accessory tool, while the narrow connection points facilitate removal of structure 1402 by mechanical cutting, cutting, punching, or drilling, or by a directed energy beam. Similarly, pin 1404 is a small protruding structure that can be engaged by a pinching or gripping accessory tool or by a “low-volume” retention-type engagement system that clamps and tightens around pin 1402 to retain it. The rectangular tab 1406 is attached at a single narrow point, allowing the remote control in some embodiments to twist and release the tab after the part has been moved to the desired area / position. The plate 1408, which is reattached at two points to facilitate later removal by mechanical cutout or energy beam, is relatively long and wide for easy engagement by the remote control.

[0118] The additive manufacturing of part 1400 can be designed to include recesses, lands, cavities, holes, or other structures defined within it that improve the secure fit with a robotic arm but do not significantly affect the function of the part. For example, a prismatic fixation cavity 1410 can guide a pin or fastening system into engagement with the cavity. Alternatively, a divergent gripper can be used to engage a notch 1412 defined in part 1400. Optionally, a cavity or opening 1416 can also be defined in a removable protruding tab. In some embodiments, the cavity or opening in a corresponding additively manufactured part can be defined by subtractive machining, drilling, punching, or etched material removal or a directed energy beam. In some embodiments, after use, the cavity can be filled using an additive manufacturing system, by the use of a thermosetting plastic, or any other suitable filling technique.

[0119] In some embodiments, the two-dimensional or three-dimensional location of the part may be enhanced by the use of imaging or other optical sensors that use the protruding tabs or cavity locations to pinpoint the exact location of the part. In other embodiments, marking optical guides or indicia may be additionally formed, machined or laser engraved on the protruding structures or the part itself to enhance guidance for mating three-dimensional location after movement.

[0120] In one embodiment, processing may occur with the following steps: In an initial step, material is placed on a powder bed in a powder chamber. Then, a part containing one or more operating points is fabricated using a directed beam of two-dimensional patterned energy. A remote manipulator may engage the operating points and lift the part off the powder bed. The part may be repositioned on the powder bed for reprocessing or moved away from the powder bed and chamber to a new processing area. In an optional step, the operating points may be removed (e.g., a protruding tab is mechanically cut off) or plugged (e.g., an additionally defined hole or cavity is filled with epoxy resin).

[0121] FIG. 15 illustrates an exemplary process 1500 for collecting and characterizing powder samples of powder material during a printing process. Process 1500 can be used to collect powder samples from a powder bed or powder dispensing assembly and characterize the powder samples in real time in a laboratory according to the present disclosure. At 1510, process 1500 can include controlling an ingester to collect multiple powder samples of the powder material as it forms a print during a print cycle. The powder material may include metal, ceramic, plastic powder, or other suitable powders capable of bonding together upon exposure to thermal energy. The ingester can collect powder samples at predetermined intervals, irregularly, or periodically at predetermined stages during the printing process. For example, powder samples can be collected every 10 minutes or only at 1 / 5 and 4 / 5 completion of the printing process. The ingester includes a device for diverting incoming powder from the powder bed or powder dispensing assembly. The ingester can also control the amount of powder being diverted according to how many tests are required for analysis. At 1520, process 1500 includes controlling a test chamber to perform one or more tests. In some embodiments, one or more specific properties of the powder material may need to be tightly controlled within certain ranges to ensure the mechanical, electrical, or optical properties of the printed object. In other embodiments, the characteristics of the powder during the printing process may need to be maintained for audit purposes. The test chamber may include equipment capable of performing one or more tests. By way of illustration and not limitation, a first test may measure the powder size distribution with a particle size analyzer, a second test may measure the density of the powder sample with a pycnometer, and a third test may identify substances within the powder sample with gas chromatography-mass spectrometry. At 1530, process 1500 may include determining whether to change a set of printing parameters used in the printing process or whether to stop the printing process according to the characterization results from the tests. The determination may include a computer simulation based on a set of models using the characterization results as input. The powder sample may have undergone unwanted changes to the powder without evidence or insufficient processing conditions.Testing may provide real-time feedback on powder properties during the printing process. One or more printing parameters may be altered according to the results of the testing. For example, the energy incident beam intensity may be increased or decreased if gas chromatography measures deviations from a particular powder density, which may affect the energy per unit required to melt or sinter the powder. The dwell time of the input beam delivered by the print head or the thickness of the powder layer dispensed by the powder dispensing assembly may also be controlled to adjust for the required change in energy. If the distribution of energy per unit volume for a particular powder density is too high, the printing process may be stopped or aborted because the energy source internal to the print head is not meeting the requirements for powder melting. In another example, contaminants in powder samples may be detected by gas chromatography, which may affect one or more electrical, mechanical, and optical properties of the printed object. In yet other embodiments, the printing process may be stopped if characterization indicates the use of unauthorized or unsafe powders, including unauthorized powders that result in poor additive manufacturing results.

[0122] In some embodiments, prediction of final print quality based on the results of in-process (real-time or in-situ) characterization of powder samples may be performed by simulation using a set of models. For example, dimensional control of a printed object may depend on the resolution of the input beam and the temperature gradient of the powder across the boundary of the fused portion. The fused portion may extend beyond the intended boundary if the temperature does not drop quickly enough across the boundary, resulting in dimensional requirements that are not within the acceptable range. The temperature gradient may be simulated by a heat transfer model that calculates the heat transfer rate based on powder properties such as powder composition and size. If the predicted dimensions of the printed object according to the simulation model exceed the acceptable range of dimensional requirements, the printing process may be stopped.

[0123] At 1540, the process 5100 may include storing the powder samples in a plurality of sample containers. The sample containers may be stored for analysis that may not be suitable for in-process characterization or later audit purposes. The storage containers may be capable of packaging the powder samples in an atmosphere substantially equivalent to the in-process (real-time or in-situ) atmosphere inside the sample containers. The atmosphere may be a vacuum, airspace, or an inert gas such as nitrogen, carbon dioxide, argon, helium, or other noble gases.

[0124] 16 , a manufacturing facility 1624 according to the present invention may include one or more machines 1610 contained within an enclosure 1626. Such an enclosure 1626 may control one or more environmental conditions as desired or necessary. For example, the enclosure 1626 may protect printed or to-be-printed materials from unwanted thermal, chemical, photonic, radioactive, or electronic reactions or interactions, and the like, or any combination or subcombination thereof. The enclosure 1626 may also protect a human operator or other nearby personnel from potentially harmful aspects of the machines or machine powder 1610, such as heat, UV light, chemical reactions, radioactive decay products, and laser exposure.

[0125] One or more machines 1610 contained within a particular enclosure 1626 may be the same size within a range of sizes. Similarly, one or more machines 1610 contained within a particular enclosure 1626 may be the same size within a range of sizes. For example, in select embodiments, one or more machines 1610 within the enclosure 1626 may each fuse (e.g., combine, bond, melt, sinter, fuse, etc.) a particular granular material in a single operation. In other embodiments, one or more machines 1610 within the enclosure 1626 may each fuse a particular granular material in successive operations. In still other embodiments, one or more machines 1610 within the enclosure 1626 may fuse a particular granular material in a single operation, while one or more machines 1610 within the enclosure 1626 may fuse a particular granular material in successive operations.

[0126] In some embodiments, the manufacturing facility 1624 includes one or more airtight chambers 1628 that form one or more antechambers to a corresponding enclosure 1626. The airtight chambers 1628 may allow parts, materials 144, personnel, etc. to pass in and out of the enclosure 1626 without compromising the environment (e.g., a low-oxygen or inert gas environment) within the enclosure 1626. The airtight chamber 1628 may include at least two airtight (or sufficiently airtight) doors 1630 a, 1630 b. The first door 1630 a of the airtight chamber 1628 may allow parts, materials 144, personnel, etc. to pass between the interior of the airtight chamber 1628 and the interior of the corresponding enclosure 1626. A second door 1630b of the airtight chamber 1628 may allow parts, materials 144, personnel, etc., to pass between the interior of the airtight chamber 1628 and the external environment surrounding the corresponding enclosure 1626. The airtight chamber 1628 may also include a gas exchange system (not shown) that may purify and / or vent the airtight chamber 1628 as desired or necessary to effectively transition the gaseous environment within the airtight chamber 1628 between a condition compatible with the interior of the enclosure 1626 and a condition compatible with the environment external to the enclosure 1626.

[0127] One or more machines 1610 may be disposed in an enclosure 1626 such that sufficient space may be maintained around the machine 1610 for one or more human operators, robots, etc. to connect to the machine 1610, remove parts therefrom, or vacuum up unfused granular material 144 for recycling, etc. Alternatively, or in addition, the enclosure 1626 may include various gantries or catwalks that allow one or more human operators, robots, etc. to connect (e.g., visually, physically) to the machine 1610. This may be useful when the enclosure 1626 includes one or more large machines 1610 that may have insufficient end or side connections for certain operations.

[0128] In some embodiments, the manufacturing facility 1624 may include one or more gas management systems 1632 that control the composition of gases within the enclosure 1626. The gas management systems 1632 may maintain a concentration of an inert or sufficiently inert gas (e.g., vacuum, nitrogen, argon, carbon dioxide, or the like, or any combination or subcombination thereof) above a desired concentration (e.g., about 99.9% or more argon by volume). Alternatively, or in addition, the gas management systems may maintain concentrations of oxygen and / or water vapor below atmospheric concentrations. For example, in one embodiment, the desired concentrations may be below 0.05% by volume for gaseous oxygen and below 0.05% by volume for water vapor.

[0129] The gaseous environment within the enclosure 1626 may be incompatible with the respiratory conditions of one or more humans who may need to enter and work within the enclosure 1626. Therefore, to work within an enclosure 1626 according to the present invention, one or more humans may wear personal protective equipment (PPE). The PPE may then create a barrier between the humans and the working environment within the enclosure 1626 when the humans enter the enclosure 1626.

[0130] In select embodiments, the PPE worn by one or more workers may include a self-contained breathing apparatus (SCBA). The SCBA may be a closed-circuit device that filters, captures, recirculates, or stores exhaled gases (e.g., re-exhaled gases). Alternatively, the SCBA may be an open-circuit device that exhausts at least some exhaled gases (e.g., nitrogen, carbon dioxide, oxygen, water vapor, or any combination or subcombination thereof) into the surrounding environment. In embodiments in which an open-circuit device is used, the amount exhausted by one or more workers within the enclosure 1626 may be extremely small relative to the oversized size of the enclosure 1626. Thus, emissions of oxygen, water vapor, etc. into the interior of the enclosure 1626 may be negligible, or at least small enough to be within acceptable limits (e.g., within the ability of the gas management system 1632 to regulate).

[0131] Referring to FIG. 17 , in select embodiments, a manufacturing facility may include multiple work areas 1724 connected by one or more interface devices 1728 to form a network 1740. One or more of the work areas 1724 forming the network 1740, etc. may be contained within an enclosure 1726. One or more of the work areas 1724 forming the network 1740, etc. may not require, and therefore may not be contained within, an enclosure 1726. One or more of the work areas 1724 forming the network 1740, etc. may be contained within one or more buildings. For example, in select embodiments, all of the various work areas 1724 forming the network 1740, etc. may be contained within a single building. In such embodiments, any work area 1724 contained within an enclosure 1726 may be a work area 1724 that requires better environmental conditions than those provided by the building.

[0132] The various work areas 1724 of network 1740 may be defined and / or arranged to correspond to certain manufacturing-related processes, which may include manufacturing a part via additive manufacturing, removing a part from a machine that created the part, removing unfused particulate material, separating a part from a substrate or floor, one or more support structures (e.g., one or more temporary structures printed to support a part during additive manufacturing that are not included in the finished part, one or more moving wall exterior portions that extend through the part, etc.), heat treating, peening, powder coating, painting, or anodizing, packaging for shipping, or any combination or subcombination thereof.

[0133] For example, in select embodiments, the network 1740 may include a first working area 1724a for powder bed fusion in an inert environment provided by the enclosure 1726, a second working area 1724b for removing granular material 144 from the build platform 146 in the enclosure 1726, a third working area 1724c for shot peening to improve the surface finish in the enclosure 1726, a fourth working area 1724d for heat treating to anneal the metal parts in the enclosure 1726, a fifth working area 1724e for removing the parts from the build platform in the enclosure 1726, a sixth working area 1724f for packaging and shipping, etc., or any combination or subcombination thereof.

[0134] In first working area 1724a, one or more machines may be contained within enclosure 1726. The machines may all be the same size among various sizes. Similarly, one or more machines may all be the same size among various sizes. For example, in select embodiments, one or more machines within enclosure 1726 may each fuse (e.g., combine, bond, melt, sinter, fuse, etc.) a particular granular material in a single operation. In other embodiments, one or more machines within the enclosure may each fuse a particular granular material in successive operations. In still other embodiments, one or more machines within the enclosure may fuse a particular granular material in a single operation, while one or more machines within the enclosure may fuse a particular granular material in successive operations.

[0135] One or more machines in first working area 1724a may be positioned such that sufficient space can be maintained around the machine for one or more human workers, robots, etc. to connect to the machine, remove parts therefrom, vacuum unfused granular material for recycling, etc. Alternatively, or in addition, first working area 1724a may include various gantries or narrow aisles that allow one or more human workers, robots, etc. to connect (e.g., visually, physically) to the machine from above. This may be useful when first working area 1724a includes one or more large machines that may have insufficient end or side connections for certain operations.

[0136] In the second work area, unfused granular material may be removed from the build platform via various methods. For example, a manually or robotically controlled (e.g., moved) sweeper having a collector may be used to collect unfused granular material from around the part and remove it from the build platform, floor, etc. Alternatively, or in addition, one or more manually or robotically controlled (e.g., targeted) pressurized gas streams may be used to remove unfused granular material from crevices, sweep it off the build platform or floor, and / or move it to one or more locations where it can be connected by sweeping.

[0137] In select embodiments, the first and second work areas 1724a, 1724b may be contained within separate enclosures 1726 as shown. In other embodiments, the first and second work areas 1724a, 1724b may be contained within the same enclosure 1726. Furthermore, in some embodiments, the first and second work areas 1724a, 1724b may be temporally separated in time (e.g., one or more operations corresponding to one work area 1724a may be performed at a different time than one or more operations corresponding to the other work area 1724b), but may overlap geographically at least at some stage.

[0138] Alternatively, the first and second working areas 1724a, 1724b may be geographically adjacent to one another, although they may overlap temporarily at some stages (e.g., one or more operations corresponding to one working area 1724a may be performed simultaneously with one or more operations corresponding to the other working area 1724b). In such an embodiment, the first section of the machine may correspond to or be the first working area 1724a, and the second section (or a combination of the second and third sections) may correspond to or be the second working area 1724b.

[0139] In the third working area 1724c, a peening process may be applied manually or robotically to one or more parts. For example, in select embodiments, a manual or robotic system may use the same granular material as the shot (i.e., the same granular material used to create the part) in the peening process to improve the surface finish of the part. In the fourth working area 172d, an enclosure 1726 may be or may include an oven for heat-treating one or more parts. Such an enclosure 1726 may therefore generate, maintain, or control a significant amount of heat. The exact amount of heat may vary depending on the size of the enclosure 1726, the nature of the parts being heat-treated, etc.

[0140] In the fifth working area 1724e, one or more build platforms or floors may be separated from the parts they supported, one or more outer portions of one or more moving walls extending through the part may be removed, one or more temporary structures printed to support the part during additive manufacturing that are not included in the finished part may be removed, or a combination thereof. In select embodiments, this may enhance a wire electrical discharge machining (EDM) process. In such an embodiment, the part may be submerged in a bath of partially deionized water where the amount of ions is carefully controlled as part of the EDM process. An enclosure for the fifth working area 1724e may be included or omitted as desired or necessary.

[0141] In sixth work area 1724f, one or more parts may be prepared for shipment and shipped. For example, in sixth work area 1724f, one or more parts may be painted, packaged, wrapped in plastic, placed in one or more pallets, or the like, and loaded onto a truck for shipment. An enclosure for sixth work area 1724f may be included or omitted as desired or necessary.

[0142] In select embodiments, the network 1740 may include multiple work areas 1724 connected in series by one or more interface devices 1728. Such interface devices 1728 may enable the smooth and efficient flow of one or more parts from one work area 1724 to the next. Thus, the work areas 1724 may be arranged in the network 1740 such that the work associated therewith may be performed in a required or desired order.

[0143] Any of the described enclosures may maintain a concentration of inert or fully inert gas (e.g., vacuum, nitrogen, argon, carbon dioxide, etc., or a combination or subcombination thereof) above a desired concentration (e.g., about 99.9% or more argon by volume). Alternatively, or in addition, the enclosure may maintain a concentration of oxygen and / or water vapor below atmospheric concentrations (e.g., below 0.05% by volume for gaseous oxygen, below 0.05% by volume for water vapor).

[0144] A vehicle may be used to transport print floors, parts, or other materials via interface device 1728 by rolling or moving on a path (e.g., a concrete floor), a conveyor system, rails, or a combination of multiple rails using traditional railroad concepts, linear movement on tracks using encoders, linear motion provided by a pulley system, motion and / or levitation provided by magnetic levitation rails, motion via a conveyor system or belt, or any combination or subcombination thereof. Large parts weighing 2000 kilograms or more may be transported. The vehicle may have wheels that roll on a support surface. The support surface may be a floor (e.g., a floor with a visually, electronically, or magnetically detectable path applied to or implemented within it). The support surface may also be one or more rails. Such rails may be located below the parts being transported by the vehicle. Alternatively, such rails may be located above the parts being transported by the vehicle. That is, the rail may be an elevated rail, and the transport device may be a dolly or trolley that rotates on the elevated rail with the part suspended underneath.

[0145] Vehicles or other vehicles may be controlled and / or operated manually, automatically, autonomously, or semi-autonomously. For example, in select embodiments, one or more vehicles may be pushed and / or steered by one or more human operators. In other embodiments, various on-board or off-board control systems may sense what is happening to the vehicle and instruct the vehicle when to move, when to stop, how to maneuver, etc.

[0146] Many modifications and other embodiments of the invention will occur to those skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. It is understood, therefore, that the invention is not limited to the specific embodiments disclosed, and that all such modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of the invention may be practiced that exclude elements / steps not specifically disclosed herein.

Claims

1. emitting two or more beams of light, each of the two or more beams of light being polarized; splitting each of the two or more beams of light into two split beams corresponding to a majority or minority polarization state, respectively; spatially stacking a first individual split beam of each of the two or more beams corresponding to the majority of polarization states to provide a first beam of light corresponding to the majority of polarization states; spatially stacking second individual split beams of each of the two or more beams corresponding to the minority polarization states to provide a second beam of light corresponding to the minority polarization states; applying a plurality of polarization patterns onto a first beam of light to provide a first patterned beam of light; applying a small number of polarization patterns onto the second beam of light to provide a second patterned beam of light; combining the first and second patterned beams of light to provide a single beam of light; directing said single beam of light onto a powder bed; 1. An additive manufacturing method comprising:

2. at least one light source configured to emit two or more beams of light, each of the two or more beams of light being polarized; splitting each of the two or more beams of light into two split beams corresponding to a majority or minority polarization state, respectively; spatially stacking a first individual split beam of each of the two or more beams corresponding to the majority of polarization states to provide a first beam of light corresponding to the majority of polarization states; spatially stacking second individual split beams of each of the two or more beams corresponding to the minority polarization states to provide a second beam of light corresponding to the minority polarization states; a polarizer configured to perform an operation including: applying a plurality of polarization patterns onto a first beam of light to provide a first patterned beam of light; applying a small number of polarization patterns onto the second beam of light to provide a second patterned beam of light; a spatial polarization valve configured to perform operations including: combining the first and second patterned beams of light to provide a single beam of light; directing said single beam of light to a location; a set of optics configured to perform operations including: an optical system comprising:

3. The optical system of claim 2 , wherein the set of optical systems includes a wavelength-selective mirror, a diffractive element, a beam homogenizer, or a combination thereof.

4. The optical system of claim 2 , wherein the optical system set includes reflective optical elements that are insensitive to wavelength-dependent refractive effects and that are configured to direct a single beam of light.

5. a high energy photon source configured to produce a beam; a reflective patterning unit configured to receive the beam and reflect a two-dimensional patterned beam; an image relay configured to receive the two-dimensional patterned beam and focus the two-dimensional patterned beam as a two-dimensional image on a powder bed; Additive manufacturing systems, including:

6. 6. The additive manufacturing system of claim 5, wherein the high-energy photon source comprises a plurality of semiconductor lasers.

7. The additive manufacturing system of claim 5 , wherein the reflective patterning unit is optically addressed.

8. 6. The additive manufacturing system of claim 5, wherein the reflective light patterning unit comprises a highly transmissive layer, a twisted nematic (TN) liquid crystal layer, and a photoconductor layer.

9. The additive manufacturing system of claim 5 , wherein the reflective patterning unit is cooled.

10. 6. The additive manufacturing system of claim 5, further comprising the powder bed configured to hold a powder material.

11. a plurality of lens assemblies including interchangeable portions configured to provide a plurality of magnifications that proportionally increase or decrease the size of an image of incident light; an electromechanical assembly configured to select one of the lens assemblies to provide one of the magnifications for converting a first image of the incident light into a second image of the incident light according to one of the magnifications; and 1. An apparatus comprising:

12. 12. The apparatus of claim 11, wherein the electromechanical assembly comprises a shape-changing dynamic lens, an electronic lens exchange system, a beam redirection system, an electro-optically controlled refractive beam steering device, or a combination thereof.

13. A powder bed; a build platform gantry; a final beam steering device mounted on the build platform gantry, the final beam steering device configured to hold powder material and direct the incident light emanating from one or more of the lens assemblies to form a second image of the light at the location of the powder bed supported by the build platform gantry; and The apparatus of claim 11 further comprising:

14. one or more sets of compensation gantries; controlling one or more sets of the plurality of lens assemblies, the electromechanical assembly, the powder bed, the build platform gantry, the final beam steering device, and the compensation gantry; obtaining information regarding the one of the magnifications and image distance related to the intensity and pixel size of the incident light on a top surface of the powder bed during a three-dimensional (3D) print job; configuring one of the plurality of lens assemblies including a first plurality of sets of optical lenses and a second plurality of sets of optical lenses interchangeable from the lens assemblies to provide the incident light having the one of the magnifications; a processor configured to perform operations including: The apparatus of claim 13 further comprising:

15. The processor controls one or more sets of the plurality of lens assemblies, the electromechanical assembly, the powder bed, the build platform gantry, the final beam steering device, and the compensation gantry to: performing multiple rotations of one or more sets of mirrors mounted on the one or more sets of compensation gantries and a final set of mirrors mounted on the build platform gantry to direct the incident light from a prior image to a final image plane location on the top surface of the powder bed; performing a plurality of translational movements of the one or more sets of compensation gantries and the build platform gantry to control the distance of the incident light from the initial image location to the location of the top surface of the powder bed so as to substantially maintain the image resolution at the desired location; The apparatus of claim 14 , further configured to perform operations including:

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