Method for powder removal in additive manufacturing systems

Abstract

Improved methods and apparatus are provided for removing powder in an additive manufacturing system. [Solution] In one embodiment for removing unpatterned powder from a substrate having patterned powder portions, at least one laser having beam parameters is irradiated to the unpatterned powder for a time sufficient to remove the unpatterned powder from the substrate.

Description

[Technical field]

[0001] The present disclosure relates to improved methods and apparatus for removing powder in an additive manufacturing system. [Background technology]

[0002] Traditional AM systems, such as 3D printing systems, have used manual devices such as brushes and end mills to remove loose or loosely compressed powder from 3D printed parts. Residual powder can be further removed by air knives, and vacuum ports can be used to aid in the extraction of the removed powder. Air can be used to remove portions of material that were not exposed to the bonding material and were not cured. These techniques can be combined with rotation, tilting, and / or vibration of the substrate to optimize the powder removal process. Vibration without air can also be used, and physical rocking of the part is an option. However, these physical removal methods are time consuming and prone to damage of fixed portions of material (whether firmly or partially clamped), especially edges or surfaces that can be manually disturbed and peeled off. Depending on the manual device used, it may also be that the device is unable to reach all corners or crevices where loose or uncured material may be present. Additionally, there are limitations to the physical size of the brushes or end mills that can be incorporated into a 3D printing system.

[0003] In some cases, liquid immersion has been used to remove the unsolidified portions of the material, typically using a fluid stream to wash away the portions of the material that were not exposed to the bonding material and did not harden. The portions of the material that were not exposed to the bonding material and did not harden may be dissolved in a solution and washed away. Alternatively, the part may be immersed in a fluid bath and a transducer may be used to generate ultrasonic waves that ultimately remove the debris from the part. One drawback of this method is that the part is immersed in a liquid. Another drawback is that the removed powder is now useless and cannot be reused without significant processing.

[0004] It can be seen that all of the powder removal methods discussed above require improvement in removing uncured material exposed to the bonding material. Summary of the Invention

[0005] The present invention is a method for removing unpatterned powder from a substrate having patterned and unpatterned powder portions deposited thereon, comprising irradiating the unpatterned powder with at least one laser beam having beam parameters for a time sufficient to remove the unpatterned powder from the substrate such that a top surface of the substrate where the unpatterned powder was located is free of the unpatterned powder, while leaving the patterned powder portions on the substrate.

[0006] The drawings illustrate one or more embodiments in accordance with the present teachings, by way of example only, and not by way of limitation. In the drawings, like reference numbers refer to the same or similar elements. It should also be understood that the drawings are not necessarily to scale. [Brief description of the drawings]

[0007] [Figure 1A] 1A-1D illustrate substrates having patterned and non-patterned powders deposited thereon and undergoing a laser powder removal process, according to aspects of the present disclosure. [Figure 1B] FIG. 1B illustrates the substrate of FIG. 1A after the laser powder removal process of FIG. 1A, according to an embodiment of the present disclosure. [Figure 2A] 1A-1C show alternative implementations of substrates having patterned and non-patterned powder deposition that have been subjected to a laser powder ablation process according to aspects of the present disclosure. [Figure 2B] FIG. 2B illustrates the substrate of FIG. 2A after the laser powder removal process of FIG. 2A, according to an embodiment of the present disclosure. [Diagram 3]1A-1C show substrates according to further embodiments having patterned and non-patterned powder deposited thereon that have been subjected to a laser powder removal process and another powder removal technique according to aspects of the present disclosure. [Figure 4A] 1A-1C illustrate substrates according to another alternative embodiment having patterned and non-patterned powder deposited thereon that have been subjected to a laser powder ablation process according to aspects of the present disclosure. [Figure 4B] FIG. 4B illustrates the substrate of FIG. 3A after the laser powder removal process of FIG. 4A, according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 illustrates a planar substrate having a release agent thereon according to another embodiment of the present disclosure. [Figure 6] FIG. 1 illustrates a schematic diagram of a laser station for laser powder ablation processing of a substrate having a powder layer deposited thereon and mounted on a carrier plate, according to an aspect of the present disclosure. [Figure 7] FIG. 7 illustrates a flowchart of an overall printing process using powder deposited on a substrate, including laser powder removal using the laser station shown in FIG. 6, according to an embodiment of the present disclosure. [Figure 8] FIG. 7 illustrates an alternative flow chart of an overall printing process using powder deposited on a substrate, including laser powder removal using the laser station shown in FIG. 6, according to an embodiment of the present disclosure. [Figure 9] 1A-1C show substrates according to further embodiments having patterned and non-patterned powder deposited thereon that have been subjected to a laser powder removal process and another powder removal technique according to aspects of the present disclosure. [Figure 10] FIG. 1 illustrates a substrate, e.g., a continuous web or roll of material upon which a series of objects are created. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, numerous specific details are set forth by way of example to provide a thorough understanding of the disclosed subject matter. However, upon reading this disclosure, it may become apparent to one skilled in the art that one or more of the disclosed aspects may be practiced without such details. Furthermore, the description of various exemplary embodiments according to the present disclosure may include references to or to one or more known techniques or operations, and such references may be at a relatively high level to avoid obscuring various concepts, aspects, and features thereof with details that are not specific to the present disclosure and are not necessary to fully understand the present disclosure.

[0009] In traditional additive manufacturing (AM), layers are built on top of each other or on a conveyor belt and stacked on top of each other in the final stage. However, as described in the applicant's related provisional application No. 63 / / 299,867, entitled "Printing Method and Apparatus for Additive Manufacturing, Including In-situ Powder Regeneration", filed on January 14, 2022, a platform for AM manufacturing has been developed that is a modular base machine that builds each layer separately. Each individual layer passes through several stations, each station having a unique function. To handle the layers between stations in this new platform, a carrier plate is required to transport the individual layers of the multi-layer product to be manufactured. Thus, carrier plates are disclosed herein that are particularly adapted for the new platform described in the related application mentioned above. In particular, the disclosure relates to the use of these carrier plates to support the individual layers in a 3D printing system and to subject these individual layers to a laser powder removal step in a laser station. Further features of the carrier plate relevant to the present application are described in the applicant's related application Ser. No. 18 / 074,298, entitled "Carrier Plate and Method of Use Thereof," filed Dec. 2, 2022.

[0010] The above-mentioned related application also describes an improved method and system for additive manufacturing, including an in-situ powder regeneration system. An exemplary method described in the related application includes applying powder to a substrate at a powder application station, removing a first portion of the powder and collecting the first portion of the removed powder in a clean powder collection container, moving the powder remaining on the substrate to a wetting station where the powder is moistened with a wetting agent, removing a second portion of the powder after wetting and collecting the second portion of the removed powder in a moist powder contamination collection container, moving the powder after wetting and removing the second portion to a binder application station where a binder is applied to the powder, and removing a third portion of the powder after the binder is applied and collecting the third portion of the removed powder in a binder contamination powder collection container.

[0011] The above-mentioned related application also describes a system and method for applying powder to a substrate at a powder application station, removing a first portion of the powder to create a clean portion of the substrate between the portions of the deposited powder, moving the portions of the deposited powder remaining on the substrate to a wetting station, wetting the powder with a wetting agent at the wetting station, passing the wetted portions of the deposited powder through a calendar roller to compress the powder, cutting the substrate at the clean portions to create substrate segments each including one of the portions of the deposited powder, moving the substrate segments with the portions of the deposited powder to a binder application station, applying a binder to the powder at the binder application station to harden the deposited powder into layers, transferring the substrate segments with the attached layers to respective carrier plates, moving the carrier plates with the substrate segments with the attached layers to a lamination station, separating the layers from the substrate segments, and flipping each of the carrier plates to laminate the layers individually on top of each other to form a multi-layered product. The present disclosure can be incorporated into the systems described in the above-mentioned related application as part of the overall removal of excess unpatterned powder in the entire 3D printing operation. It should be noted that although a particular order of steps is described above, the order of steps can be changed as desired without departing from the scope of the present disclosure.

[0012] The present disclosure relates to improved methods and apparatus for removing powder in an additive manufacturing system. In particular, the present disclosure provides methods and systems that can remove powder or material that has not been exposed to a binder and hardened (material that is not fixed in place, fused, or melted). The methods and systems can also be implemented to remove a portion of the powder that has a binder while not removing another portion of the powder that also has a binder. For example, in one embodiment, the removed powder or material may not have been exposed to the same binder material as other powders that have been fixed in place and fused or melted. In other embodiments, one or more additives may be included to inhibit powder removal in the patterned areas and promote / enhance powder removal in the non-patterned areas by the laser removal process. The additives may be added to either the powder or the substrate. The distinction between the materials may allow one material to be removed while the other material remains in place. In other embodiments, the distinction between the materials may allow one material to be removed while the other material remains in place until a later time when it may be removed under different powder removal conditions, e.g., different laser power or frequency. Removal by the techniques described herein takes less time than existing conventional powder removal methods and does not require the inclusion of physical equipment that may disturb or damage the bonded product (e.g., powder that is subjected to a bonding material and cured and solidified to form a patterned powder layer).

[0013] For example, in one embodiment shown in FIG. 1A and FIG. 1B, after the bonding step of the 3D printing operation is performed on the powder 110 deposited on the substrate 100 to provide the patterned portion 120 of the powder 110, the laser beam 115 is directed toward the adjacent unpatterned loose powder region 125, i.e., the region where the powder 110 has not been exposed to the bonding material and has not been hardened. It should be noted that although only one laser beam 115 is shown, multiple laser beams generated from multiple lasers can be used to simultaneously remove powder from different regions. Also, different powder removal devices, such as air knives, vacuum devices, etc., can be used with one or more lasers to simultaneously remove powder from different regions. The unpatterned material 125 is essentially loose powder, or at least not fixed. The selection of the beam parameters (profile, beam size, beam diameter, divergence, wavelength, power / energy, operating time, pulse duration, repetition rate, application area, absorption depth, etc.) of the laser 115 and various materials are such that the energy is absorbed by the unpatterned material 125 (e.g., unconsolidated powder) but not by the substrate 100 on which it is placed. The energy provided by the laser 115 is absorbed by the loose / unconsolidated powder 125, which experiences an increase in temperature. As a result of the absorption of the energy, the loose / unconsolidated powder 125 dissipates, further separating it from the hardened material portion 120 of the adjacent powder (e.g., patterned powder). The laser parameters can be adjusted such that power is provided at a specified amount to a point just outside the layer of patterned powder material 120 for a time sufficient for the unconsolidated (unpatterned) powder 125 to reach the temperature required to remove the unconsolidated powder 125 from the substrate 100. FIG. 1B shows the result after the laser processing shown in FIG. 1A is completed, with only the bonded patterned powder 120 remaining.

[0014] The mechanism of this absorption of the laser energy by the unconsolidated powder 125 is due to a possible liquid phase explosion around the particles, i.e. a thin liquid water layer condensed on the particles and on the rapidly heated substrate 100. The pressure generated during the subsequent phase explosion generates cleaning forces that exceed the adhesion forces of the particles. The pulse energy from the laser 115 also displaces the particles. This phenomenon is explained in the paper entitled "Infrared steam laser cleaning" (First publ. in: Applied Physics / A, Materials Science and Processing, 93 (2008), 1, pp.1-4, P. Frank. F. Lang. M. Mosbacher. J. Boneberg, P. Leiderer). In other words, the liquid water layer can be considered as a conditioning agent that, in effect, allows control of the process.

[0015] As shown in FIG. 1A, the laser 115 can be moved along the contour of the patterned powder 120, to a corner, or directed away from the patterned powder 120 to remove additional unbound powder 125. The laser removal step can be performed at the end of the creation of each layer, rather than at the end of the entire 3D printed object as in conventional powder bed systems. In some implementations, the laser 115 can be moved across the patterned powder areas 120 as well as the unpatterned powder 125 throughout the layer. In this way, all unbound or unpatterned powder 125 in the entire layer can be removed. Each patterned powder layer 120 or object can then be separated from the substrate 100 and stacked individually on top of each other to form a multi-layer part. With regard to the characteristics of the laser 115 for performing powder removal, further details regarding the laser cleaning process using agents to control the laser penetration depth are again referred to the above-mentioned “Infrared Vapor Laser Cleaning” paper, the aspects of which may be modified. As shown in Figures 1A, 2A, and 4A, if desired, multiple lasers 115 can be used to speed up the powder removal process by performing powder removal at multiple locations where unpatterned powder is present.

[0016] In some embodiments, an air stream (see air knife 1080 in FIG. 10) can be optionally applied to the area where the laser 115 is currently being directed, or to an area where the laser was previously directed and is now stopped. Also, a camera system can be integrated (with a corresponding control system, such as control system 650 in FIG. 6) to monitor the volume of unpatterned powder 125 remaining around the patterned powder 120, and the laser 115 can be directed accordingly in terms of intensity, direction, exposure time, etc. For example, by overlaying coordinates from the jetted binder onto an image of the patterned powder 120, the volume of unpatterned powder 125 can be determined from the image, and the laser 115 can be directed towards a larger volume of area around the patterned powder 120, taking into account the distance the laser 120 must travel, so that the laser does not "jump."

[0017] According to an aspect of the present disclosure, the laser 115 is operated below a first threshold where the binder material and powder combination is connected / bonded / fused / melted, and with a second threshold where it does not affect the substrate 110. Since there is no physical contact made to facilitate powder removal, damage to the patterned portion is minimized and time is saved.

[0018] In the embodiment shown in FIG. 1A, the laser beam 115 is applied from above the substrate 100 and the powder 110. However, according to an alternative embodiment, the laser beam 115 is applied from below the substrate 100 such that the laser beam 115 passes through the substrate 100 and is absorbed by the unpatterned powder 125 (see, for example, FIG. 2A). As mentioned above, the parameters of the laser beam 115 and the materials used for the powder 110 and the substrate 100 are selected such that the laser light 115 is absorbed by the unpatterned powder 125 and not the substrate 100. This flexibility in terms of placement of the laser 115 above or below the substrate 100 allows this laser powder removal system to be incorporated into a variety of 3D printing systems of different designs.

[0019] In an embodiment of the present disclosure, the time it takes to remove powder from the printed layer can be optimized by modifying one or more parameters of the laser based on the area where the laser is irradiated or by using multiple lasers. These multiple lasers can be substantially identical to each other in terms of their properties and characteristics, or can have different properties and characteristics from each other. FIG. 3 shows a substrate 300 with a material or powder 310 applied extending the length of the substrate 300. This powder layer 310 has a patterned region 320 where a binder is applied to harden the deposited powder, the patterned region 320 having a first boundary 330. The powder layer 310 also includes a feature 340, in this case an opening, with a second boundary 350. The non-patterned regions 325, i.e., material or powder that has not been exposed to the binder material, hardened, fixed in place, and fused or melted, include the non-patterned powder regions outside the first boundary 330, including the fill region 360 to the right of the patterned region 320. In one example, the laser 115 (see, e.g., FIGS. 1A and 1B) may be operated using a first set of operating parameters to slowly and precisely remove powder from the first boundary 330 and the second boundary 350, and a second set of operating conditions to more quickly and potentially less precisely remove powder inside and / or outside these boundaries. In one embodiment of the disclosure, the first set of operating parameters may include a more focused or less diverging beam, and the second set of operating parameters may include a less focused or more diverging beam, one of a larger beam diameter as it intersects with the powder on the substrate. In another embodiment of the disclosure, two or more lasers 115 may be utilized rather than varying the operating parameters of a single laser.

[0020] In another embodiment, a combination of powder removal techniques, for example using one or more of an air knife, vibration technique, or another powder removal technique, can be combined with a laser removal technique to optimize the time it takes to remove unpatterned or loose powder. The one or more powder removal techniques may be selected based on the resolution required at a particular location / area on the substrate, the resolution required for a location / area on the final printed object, the resolution required to allow a subsequent layer to be printed, or the resolution required to allow a subsequent processing step to be performed.

[0021] In one example, optimization of the time it takes to remove all non-patterned powder 325 from an entire layer of substrate 300 can be achieved using a combination of powder removal techniques. For example, in the fill area 360 to the right of the patterned area 320, where there are no patterned areas, objects, or features with any particular detail that needs to be retained, where resolution is not particularly important, non-patterned powder 325 may be removed using, for example, an air knife. In areas where patterned areas 320 and openings 340 are located, where higher resolution is required, laser removal techniques may be more appropriate. To minimize the possibility that any lower resolution powder removal technique will disturb, destroy, or damage the patterned areas 320 or openings 340, a lower resolution powder removal technique may be used up to a margin 370 to leave a safety zone 380 of unpatterned powder 325 around the edges of any patterned areas 320 or boundaries 330. The width of the safe zone 380 may depend on one or more powder properties (both chemical and physical), binder formulation, curing technique, and powder removal technique utilized. In one embodiment, the width of the safe zone 380 can be selected to correspond to potential bleeding areas that occur after the patterning process. Bleeding is the result of solidification of areas / portions of material that were not intended to be solidified due to (for example) binder propagating into the surrounding powder. In other implementations, the safe zone 380 can be selected by the user from one or more preset values, e.g., 0.2-0.5 mm outside the patterned area 320 or boundary 330. Alternatively, the value of the safe zone 380 may be automatically determined from the CAD data, including metadata.

[0022] In a further embodiment, once the unpatterned powder 325 has been removed from a particular area, for example forming an opening 340, the opening can be filled with a second material. A precise method can be used to remove the unpatterned powder 325 from the opening 340 and precisely define the boundary 350 of the opening, allowing subsequent processing to be based on precise feature definition.

[0023] The combination of powder removal techniques used may be directed by the user or may be determined based on information contained in a database or data table provided by the system. Additionally, the order in which the powder removal techniques are applied, including the option to perform operations substantially simultaneously, may also be directed by the user or based on information contained in a database or data table provided by the system.

[0024] In one embodiment, a control system for an additive manufacturing system can include a graphical user interface that provides a mechanism by which a user can instruct the system which powder removal techniques to utilize on which regions of the printed layer, and optionally the order in which to do so. Data may be imported or extracted from a CAD drawing of the printed object, and software is provided to allow the user to indicate or outline the regions in which the selected powder removal techniques should be utilized. Analysis can be performed to extract feature data, identify regions of different resolution, and / or determine margins and safety zones, as well as associated coordinate data. In another embodiment, the software can automatically identify which techniques are best suited for which areas of the patterned printed layer based on the coordinate data, resolution data contained within the CAD drawing, or metadata associated therewith. Once determined, this information can be used to direct the operation of the appropriate powder removal technique in each area or region of the patterned printed layer. In some embodiments, a graphical user interface can be utilized to suggest which powder removal techniques can be applied to which regions, and the user is provided with the option to accept or modify the proposed powder removal techniques, the regions to which they are applied, and / or the order in which the techniques are applied. In some embodiments, two or more techniques can be applied at least partially simultaneously.

[0025] In another embodiment shown in Figures 4A and 4B, after patterning a substrate such as the substrate 300 of Figure 3, the substrate 300 is rotated 180 degrees along the thickness direction (i.e., inverted or flipped) before activating the laser 415. By rotating the substrate 300 so that the patterned layer 320 "hangs" above the powder container 400, the unpatterned powder 325 exposed to the laser beam 420 can fall into the lower container 400. In this way, the unpatterned powder 310 falls into the lower container 400 and can be recycled for subsequent use. It is noted that mounting the substrate 300 on a carrier plate (see Figure 6) helps to facilitate the 180 degree rotation of the substrate. In one embodiment, the powder container 400 into which the unpatterned powder falls can depend on the powder removal technique utilized. For example, when utilizing an air knife in region 340 (see, e.g., FIG. 3), unpatterned powder 325 may fall into container 400 for "clean" powder, i.e., powder that has not been exposed to a binder. Unpatterned powder 325 removed using laser removal techniques may fall into container 400 for "contaminated" powder, i.e., powder 310 that may have been exposed to a binder. This is especially true for unpatterned powder 325 in areas outside of patterned region 320, up to edges 370, where bleeding may occur. In this manner, the "contaminated" and "clean" powders may each be subjected to an appropriate level of processing to clean them prior to subsequent use.

[0026] In embodiments in which the substrate 300 is not rotated 180 degrees, recycling of the powder 310 may be accomplished using other methods, such as extracting the unpatterned powder 325 via vacuum into a suitable container.

[0027] In a further embodiment as shown in FIG. 5, a release layer 510 may be provided between the substrate 520 and the powder layer 530. The release layer 510 is configured to improve separation of the patterned layer 540 from the substrate 520 when the laser 550 is applied through the substrate 520. In one aspect of the present disclosure, the release layer 510 may include a wetting agent. Absorption of the laser energy by the wetting agent creates pressure within the release layer 510, which in turn causes the patterned powder 540 to separate from the substrate and improves separation of the patterned powder therefrom. In addition, absorption of the laser energy by the non-patterned powder 560 affects the non-patterned powder 560 being removed from the patterned powder 540. In another aspect of the present disclosure, the release layer 510 may include a binder material. Similarly, absorption of the laser energy by the binder increases the temperature, causing the binder to vaporize and / or substantially evaporate, leaving a surface, thereby causing the patterned powder 540 to separate from the substrate 520. Additionally, the absorption of laser energy by non-patterned powder 560 affects the non-patterned powder 560 being removed from patterned powder 540 .

[0028] FIG. 6 shows a schematic diagram of a laser station 600 for laser powder ablation processing of a substrate 605 as described above having a powder layer 610 deposited thereon and mounted on a carrier plate 612, according to an embodiment of the present disclosure.

[0029] As can be seen in FIG. 6, the laser station 600 includes a drawer 622 loaded with a carrier plate 612 having a substrate 605 and powder 610 attached thereto. In an embodiment, loading of the carrier plate 612 may be performed by a robotic arm or similar automated solution. According to one aspect of the present disclosure, the carrier plate 612 with the powder 610 thereon is inverted before loading into the drawer 622, such that the powder layer 610 faces downward, as shown, for example, in FIG. 4A. After the carrier plate 612 is loaded, the drawer 622 is pushed into the laser station 600 until it contacts a stop mechanism (not shown) in the laser station 600. When a sensor (not shown) at the end of a drawer guide track (not shown) in the laser station 600 determines that the drawer 622 (with the carrier plate 612 inserted) is fully inserted, the laser 615 mounted on the top of the laser station 600 is programmed for a laser powder removal operation. This programming may include determining appropriate laser beam parameters based on information provided to the control system 650 of the laser station 600 regarding the powder material and the substrate material to determine appropriate laser beam intensity, area, and position for the laser 615 to remove the unpatterned powder of the powder 610 without the laser beam generated by the laser 615 being absorbed by either the substrate 605 or the patterned powder that must remain after the laser powder removal process, and with the laser beam being absorbed by the unpatterned powder. These laser beam parameters may be set by the control system 650 to enhance the resolution of the patterned areas and remove bleed areas of binder material from the target pattern areas. As mentioned above, the control system 650 may include a camera system to monitor the amount of powder to determine the appropriate level of the laser beam.

[0030] Once the drawer 622 is fully inserted into the laser station 600, the carrier plate 612 loaded in the drawer 622 is lifted into the powder removal range and sealed in the laser station 600 under the laser 615. Once the sealing of the carrier plate 612 is confirmed (by the laser control system 650), the laser 615 is turned on and removes the powder 610 based on the programming of the laser 615. To complement the laser powder removal operation, an air knife can be positioned in the laser station, also controlled by the control system 650, which moves back and forth to remove powder loosened by the laser beam.

[0031] In one embodiment, the laser beam from laser 615 is directed by control system 650 to a point on the non-patterned powder that is directly adjacent to the boundary between the non-patterned and patterned powders. In another embodiment, a user or a computing system (e.g., control system 650 including a computer system) can determine an appropriate contour for the laser beam to follow, for example, the contour being a predetermined distance away (in either direction) from the boundary between the non-patterned and patterned powders.

[0032] In another embodiment, the laser beam from laser 615 may be directed by control system 650 (one or more times using the same or different laser parameter settings) to follow the contour of the boundary between the non-patterned and patterned powders and then directed outwardly away from the boundary from a point on the non-patterned powder directly adjacent the boundary between the non-patterned and patterned powders. The outward movement may be linear or may include one or more non-linear (e.g., curvilinear, spiral, circular, or loop-like) motions.

[0033] As the unpatterned powder falls from the inverted substrate (see, for example, FIG. 4A), it falls into a powder container, specifically a vacuum removal duct 660 provided beneath the inverted carrier plate 612, as shown in FIG. 6. Once the powder 610 has been removed by either the laser 615 or a combination of the laser 615 and airflow (not shown), applied either while the laser beam is applied or after the laser beam is applied and then stopped, the drawer 622 can be withdrawn and the carrier plate 612 with the substrate 605 with only the patterned powder remaining can be removed.

[0034] In another embodiment, the carrier plate 612 may be transported on a conveyor belt or similar mechanism as part of an automated system, with the control system 650 configured to interact with the laser 615 of the laser powder ablation system. The interaction may include, for example, terminating the movement of a conveyor belt or similar feature when the conveyor belt or similar feature is in an appropriate position so that the laser ablation operation can be performed to remove unpatterned powder when the laser 615 is operated. Additionally, a robotic arm under the control of the control system 650 may be utilized to enable flipping of the carrier plate 612 as needed.

[0035] FIG. 7 shows an example of the integration of the laser powder removal process into an overall system for 3D printing. As shown in FIG. 7, the powder removal step 750 can be integrated after the steps of depositing powder in step 710, applying a conditioning agent (or wetting material) to the deposited powder in step 720, compressing the powder in step 730, and patterning the powder in step 740, resulting in a substrate having sections of patterned and unpatterned powder, as shown in FIG. 1A, FIG. 2A, and FIG. 4A. As also shown in FIG. 7, after the laser powder removal step 750, further processing can include further patterning in step 760, stacking of processed powder layers in step 770, and recycling (step 780) the powder removed and collected during the various processing steps. Further details regarding the overall processing system and operation, as well as powder regeneration, are disclosed in the related applications listed above. 8 (laser powder removal step 750 may be incorporated into the overall printing operation following powder compaction in step 730 and prior to patterning with a binder in step 740) may be accomplished such that an overall reduction in production time may be expected. Alternatively, powder removal step 750 may be performed both before and after patterning step 640 if desired for more complete powder removal.

[0036] More specifically, although a particular order of operations is shown in FIG. 7, the order of operations can be changed as needed. For example, as shown in FIG. 8, it is possible to use the laser powder removal operation 750 described above on the powder deposited on the substrate after compaction 730 and before patterning 740. In this case, the laser powder removal step 750 is used to remove the loose powder present on the substrate after the application and compaction of the powder, but before the actual patterning operation. Since the unnecessary loose powder is removed, the binder bleeding problem during the binder deposition step can be minimized. In this way, the binder deposition allows the patterning to extend all the way to the very edge of the deposited powder, but does not leach any further because there is no powder to leach there. This allows further optimization in terms of processing time, since it is no longer necessary to remove the powder after patterning. Similarly, the compaction step 730 can be performed before the application of the binder material, if needed. Also, as discussed in the related application above, the powder can be collected and recycled at various points during the process instead of waiting until the end of the process to recycle the powder.

[0037] FIG. 9 shows a substrate 900 with a material or powder 910 applied over the length of the substrate 900. It is desired to process this powder layer 910 to define a patterned region 920 having features 940, in this case apertures, disposed therein. In one example, optimization of processing can be achieved by performing a laser powder removal step prior to patterning under the control of a control system such as that shown in FIG. 6. For example, an air knife can be utilized to remove unpatterned powder in region 960 to the right of the desired patterned region 920. In the desired patterned region 920, and in the region where the apertures 940 are located, higher resolution is required and in these regions laser removal techniques are more suitable. After powder removal is performed and the region is defined, the region 920 is patterned and the patterned layer may be removed from the substrate and stacked onto another layer or build platform as part of a multi-layer part.

[0038] In some embodiments of the present disclosure, one or more sensors may provide data that can be used to determine how successful the powder removal operation was. For example, an image capture device may be utilized to provide digital information regarding the location of the remaining unpatterned powder. Based on this information, including the location information, the control system 650 (see FIG. 6) may determine that the laser needs to be operated one or more successive times to complete the powder removal procedure. Alternatively, one or more additional "trains" of lasers may be utilized to remove the unpatterned powder missed by the first laser.

[0039] To maximize throughput with respect to removal of unpatterned powder from multiple objects or multiple areas containing both patterned and unpatterned powder, another embodiment of the present disclosure allows at least a portion of the powder removal process to be performed substantially simultaneously on at least two or more objects. FIG. 10 shows a substrate 1000, e.g., a continuous web or roll of material with powder 1010 deposited thereon, on which a series of objects are created. The objects may be identical to each other or different from each other. In this particular example, objects A1 and A2 are the same, feature 1040A takes the form of an elongated slot that partially traverses objects A1, A2, and object B1 comprises feature 1040B in the form of an aperture. However, each object A1, A2, B1 includes an area of ​​patterned powder 1020 and features 1040A, 1040B. Reference marks or fiducials on the substrate 1000 correspond to the location of each type of object on the substrate 1000: cross-shaped fiducials 1050A correspond to objects A1, A2 having elongated slots, and moon-shaped fiducials 1050B correspond to object B1 having a circular aperture.

[0040] In one particular embodiment, the substrate 1000 is transported on a conveyorized platform or conveyor belt moving in a direction 1070 from right to left. When the objects A1 and B1 are transported to the desired position relative to the powder removal device 1080, 1090, the movement of the conveyor belt is stopped and operation is allowed. The air knife 1080 is operated to remove material or powder that has not been exposed to the bonding material from the substrate, with care being taken to operate the air knife 1080 around the object B1 but not within the boundaries of the safety zone or patterned area 1020. The air knife 1080 does not operate in the localized area where the objects A1 or A2 are present. The moon-shaped reference 1050B may be sensed by a sensor associated with the controller of the air knife 1080 to provide operation information for the air knife. At substantially the same time, the laser powder removal device 1090 is operated to remove material or powder that has not been exposed to the bonding material from the object A1. The cross-shaped reference 1050A can be sensed by a sensor associated with the controller of the laser powder removal apparatus 1090 to provide operational information for the laser powder removal apparatus. In one example, the laser powder removal device 1090 can be controlled to first remove powder from the border of the patterned area 1020 and then remove powder from the entire layer of powder in the localized area where object A1 is present. The laser powder removal apparatus 1090 does not operate in the localized area where objects B1 and A2 are present. In this way, two powder removal techniques can be applied to different areas of the substrate substantially simultaneously. In one configuration, the conveyor belt is stationary when the powder removal apparatus 1080, 1090 operate in their respective operating areas. Once powder is removed from the respective areas where objects A1 and B1 are present, the conveyor belt operates to move the objects in the direction 1070 such that the operation of the laser powder removal apparatus 1090 can remove powder from object B1 and the operation of the air knife 1080 can remove powder from object A2. In another configuration, the conveyor belt can move substantially continuously. All of the above operations shown in FIG. 10 may be performed using a control system 650 such as that shown in FIG.

[0041] In alternative embodiments, a series of air knives 1080 and laser powder removal devices 1090 can be provided, achieving higher throughput. In this manner, a technical solution is provided for speeding up the powder removal process by configuring and operating the powder removal techniques in a synchronized manner. The synchronization may be between the powder removal techniques and / or the position of the object on the substrate. In some embodiments, the synchronization may also allow for adjustment of their respective operations and / or positions of operations based on the duration of the operation of the powder removal devices and / or the movement speed of the substrate motion.

[0042] It should be noted that while the above description has been presented primarily with respect to removing powder from a substrate having a deposited layer in an additive manufacturing environment such as 3D printing, the apparatus and methods of the present disclosure are not limited to only such configurations, but may be used in any situation where it is desirable to remove powder in conjunction with the processing of the powder at multiple different stations.

[0043] Further features, characteristics and advantages of the present application are described by headings below.

[0044] Item 1: A method for removing unpatterned powder from a substrate having patterned powder portions and unpatterned powder portions deposited thereon, the method comprising irradiating the unpatterned powder with at least one laser having beam parameters for a time sufficient to remove the unpatterned powder from the substrate such that a top surface of the substrate where the unpatterned powder was located is free of unpatterned powder, while leaving the patterned powder portions on the substrate.

[0045] Item 2: The method of item 1, wherein at least one beam parameter of the laser and the materials of the powder and substrate are preset such that power from the laser is absorbed by the unpatterned powder but not by the substrate.

[0046] Item 3: The method of item 1 or 2, wherein the at least one laser beam parameter includes a laser profile, a laser wavelength, a laser power, an operation time of application of the laser to the non-patterned powder, an application area of ​​the laser, and a depth of absorption of the laser in the non-patterned powder.

[0047] Item 4: The method of any one of items 1 to 3, wherein at least one laser is applied to the non-patterned powder to raise the temperature of the non-patterned powder for a time sufficient to reach a temperature required for a certain amount of the non-patterned powder to separate the non-patterned powder from the patterned powder.

[0048] Item 5: The method of any one of items 1-4, wherein at least one laser is applied to a point on the non-patterned powder immediately adjacent to the boundary between the non-patterned powder and the patterned powder.

[0049] Item 6: The method of any one of items 1-5, wherein at least one laser is first applied from a point on the non-patterned powder directly adjacent the boundary between the non-patterned powder and the patterned powder, and is moved outward away from the boundary.

[0050] Item 7: The method of any one of items 1 to 6, further comprising monitoring a volume of the non-patterned powder while at least one laser is applied to the non-patterned powder to control laser operation and movement.

[0051] Item 8: The method according to any one of items 1 to 7, wherein the laser is irradiated from above the substrate and the non-patterned powder.

[0052] Item 9: The method of any one of items 1 to 8, wherein the laser is applied from below the substrate and the non-patterned powder such that the substrate is located between the laser source and the non-patterned powder.

[0053] Item 10: The method according to any one of items 1 to 9, wherein the substrate is inverted such that the non-patterned powder is suspended above a powder container, and a laser is irradiated from above the substrate and the non-patterned powder such that the substrate is located between the laser source and the non-patterned powder, and a powder container is located below the substrate and the non-patterned powder to collect the non-patterned powder that falls from the substrate during irradiation with the laser.

[0054] Item 11: The method according to any one of items 1 to 10, wherein the substrate and powder are mounted on a carrier plate inserted into a laser station including a laser source located above the carrier plate and a powder container located below the carrier plate.

[0055] Item 12: The method of any one of items 1 to 11, further comprising recycling the unpatterned powder after removal from the substrate.

[0056] Item 13: The method of any one of items 1 to 12, further comprising applying an air stream to the non-patterned powder while the at least one laser is applied to the non-patterned powder.

[0057] Item 14: The method of any one of items 1 to 13, further comprising applying an air stream to the non-patterned powder after the at least one laser is applied to the non-patterned powder.

[0058] Item 15: The method of any one of items 1 to 14, wherein beam parameters are set to increase resolution of the patterned areas and remove bleed areas of binder material from the target pattern area toward which the at least one laser is directed.

[0059] Item 16: The method of any one of items 1 to 15, wherein the beam parameters are configured to allow a user to determine the contour the laser beam will follow and where to direct the laser beam.

[0060] Item 17: The method according to any one of items 1 to 16, wherein the contour can be a line or a spiral.

[0061] Item 18: A method according to any one of items 1 to 17, wherein the beam parameters are configured to enable multiple contours of the laser beam using multiple sets of laser parameters.

[0062] Item 19: The method of any one of items 1 to 18, further comprising applying multiple lasers to generate multiple laser beams and applying one or more additional powder removal techniques to remove unpatterned powder from the substrate.

[0063] Item 20: The method according to any one of items 1 to 19, wherein the powder is removed from an entire layer on the substrate.

[0064] Item 21: The method of any one of items 1 to 20, wherein the multiple lasers and the one or more additional powder removal techniques are applied to substantially simultaneously remove the unpatterned powder at multiple locations from the substrate.

[0065] Item 22: The method of any one of items 1 to 21, wherein the one or more additional powder removal techniques include at least one of an air knife or a vibration technique.

[0066] Item 23: The method of any one of items 1 to 22, further comprising transferring the patterned layer to a build plate after removing the non-patterned powder from the substrate.

[0067] Item 24: The method of any one of items 1 to 23, further comprising a release layer located between the substrate and both the patterned and non-patterned powder portions of the powder.

[0068] Although various embodiments have been described, the description is intended to be illustrative rather than limiting, and it is understood that many more embodiments are possible. Although many possible combinations of features are shown in the accompanying drawings and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any embodiment may be used in combination with or in place of any other feature or element in any other embodiment, unless specifically limited thereto. Thus, it will be understood that any of the features shown and / or discussed in this disclosure may be implemented together in any suitable combination.

[0069] While the above has described what is believed to be the best mode and / or other examples, it will be understood that various modifications can be made therein and that the subject matter disclosed herein can be embodied in a variety of forms and examples and that the teachings can be applied to numerous applications, only a few of which are described herein.

[0070] Unless otherwise indicated, all measurements, values, ratings, positions, dimensions, sizes, and other specifications set forth herein are approximate and not exact, and are intended to have a reasonable range consistent with the functions to which they relate and that which is customary in the art to which they pertain.

[0071] It will be understood that the terms and expressions used herein have the ordinary meanings given to such terms and expressions with respect to their corresponding respective fields of study and research, unless a specific meaning is otherwise set forth herein. Relative terms such as first and second may be used merely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements may include other elements not expressly listed or inherent to such process, method, article, or apparatus, rather than including only those elements. An element preceded by "a" or "an" does not, without further constraints, preclude the presence of additional identical elements in the process, method, article, or apparatus that includes that element.

Claims

1. 1. A method of removing unpatterned powder from a substrate having patterned powder portions and unpatterned powder portions deposited thereon, comprising:

11. A method comprising: applying at least one laser having beam parameters to the non-patterned powder for a time sufficient to remove the non-patterned powder from the substrate such that no non-patterned powder is present on a top surface of the substrate where the non-patterned powder was disposed, while leaving patterned powder portions on the substrate.

2. 10. The method of claim 1 , wherein beam parameters of the at least one laser and materials of the powder and the substrate are preset such that power from the laser is absorbed by the non-patterned powder but not by the substrate.

3. 2. The method of claim 1 , wherein the beam parameters of the at least one laser include a profile of the laser, a wavelength of the laser, a power of the laser, an operating time of application of the laser to the non-patterned powder, an application area of ​​the laser, and a depth of absorption of the laser in the non-patterned powder.

4. 10. The method of claim 1 , wherein the at least one laser is applied to the non-patterned powder to raise a temperature of the non-patterned powder for a period of time sufficient for a certain amount of the non-patterned powder to reach a temperature necessary to separate the non-patterned powder from the patterned powder.

5. 5. The method of claim 4, wherein the at least one laser is irradiated at a point on the non-patterned powder that is immediately adjacent a boundary between the non-patterned powder and the patterned powder.

6. 6. The method of claim 5, wherein the at least one laser is moved from a point on the non-patterned powder directly adjacent a boundary between the non-patterned powder and the patterned powder, and the at least one laser is initially applied outwardly away from the boundary.

7. 10. The method of claim 1, further comprising monitoring a volume of the non-patterned powder while the at least one laser is applied to the non-patterned powder to control operation and movement of the laser.

8. The method of claim 1 , wherein the laser is irradiated from above the substrate and the unpatterned powder.

9. 10. The method of claim 1 , wherein the laser is irradiated from below the substrate and the unpatterned powder such that the substrate is located between the laser source and the unpatterned powder.

10. 10. The method of claim 1, wherein the substrate is inverted such that the non-patterned powder is suspended over a powder container, the laser is irradiated from above the substrate and the non-patterned powder such that the substrate is located between the laser source and the non-patterned powder, and the powder container is positioned below the substrate and the non-patterned powder to collect non-patterned powder that falls from the substrate during irradiation by the laser.

11. 11. The method of claim 10, wherein the substrate and the powder are mounted on a carrier plate, and the carrier plate is inserted into a laser station including a laser source located above the carrier plate and the powder container located below the carrier plate.

12. The method of claim 1 , further comprising recycling the unpatterned powder after removal from the substrate.

13. 10. The method of claim 1, further comprising applying an air flow to the non-patterned powder while the at least one laser is applied to the non-patterned powder.

14. 10. The method of claim 1, further comprising applying an air flow to the non-patterned powder after the at least one laser is applied to the non-patterned powder.

15. 10. The method of claim 1, wherein the beam parameters are set to increase resolution of the patterned areas and to remove bleed areas of binder material from a target pattern area toward which the at least one laser is directed.

16. The method of claim 1 , wherein the beam parameters are configured to allow a user to determine the contour the laser will follow and where to point the laser.

17. The method of claim 16 , wherein the contour can be a line or a spiral.

18. 20. The method of claim 17, wherein the beam parameters are configured to enable multiple profiles of the laser having multiple sets of laser parameters.

19. 10. The method of claim 1, further comprising applying one or more additional powder removal techniques to remove the unpatterned powder from the substrate.

20. The method of claim 19 , wherein the powder is removed from an entire layer on the substrate.

21. 20. The method of claim 19, wherein the at least one laser and the one or more additional powder removal techniques are applied to substantially simultaneously remove the unpatterned powder at multiple locations from the substrate.

22. 20. The method of claim 19, wherein the one or more additional powder removal techniques include at least one of an air knife or a vibration technique.

23. The method of claim 1 , further comprising transferring the patterned layer to a build plate after removing the non-patterned powder from the substrate.

24. 10. The method of claim 1 , further comprising a release layer located between the substrate and both the patterned and non-patterned powder portions of the powder.

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