Patent Application
20240227016
The present disclosure relates generally to additive manufacturing, and more particularly, to systems and methods of dynamically shaping laser beams during additive manufacturing.
Powder-bed fusion (PBF) systems can produce structures (referred to as build pieces) with geometrically complex shapes, including some shapes that are difficult or impossible to create with conventional manufacturing processes. PBF systems include additive manufacturing (AM) techniques to create build pieces layer-by-layer. Each layer or slice can be formed by a process of depositing a layer of powder and then fusing (e.g., melting and cooling), via a laser beam, areas of the powder layer that coincide with the cross-section of the build piece in the layer. The process may be repeated to form the next slice of the build piece, and so on until the build piece is complete. Because each layer is deposited on top of the previous layer, PBF may be likened to forming a structure slice-by-slice from the ground up.
However, these AM systems lack optimized control of the laser beam across the layer such that the material in front of the processing beam melts and consolidates in an efficient manner. Further, these AM systems lack optimized, dynamic beam shaping of the laser beam to optimize various resulting properties of the build piece.
Several aspects of a variable beam geometry laser-based PBF and systems, methods, and non-transitory computer-readable mediums for additively manufacturing a build piece will be described more fully hereinafter.
In an aspect of the present disclosure, an apparatus for additively manufacturing a build piece is presented. The apparatus includes a powder bed depositor configured to deposit a layer of powder material in a powder bed. The apparatus also includes a laser beam source configured to produce a laser beam. The apparatus further includes a beam shaping component configured to adjust an energy profile of the laser beam to obtain a beam energy profile. Additionally, the apparatus includes a controller.
In one or more embodiments, the controller can be configured to obtain information of the layer of powder material, the information including a plurality of tiles of the layer and a tile energy profile associated with each of the tiles. For example, the tile energy profile can include one or more parameters. The parameters can include at least a length, a width, a depth, a power density, or a time. Further, the tile energy profile can include an energy profile based on a geometry of the build piece. The geometry of the build piece can include a geometry of an edge of the build piece. Additionally, the tile energy profile can include an energy profile that varies over time. The energy profile that varies over time can include a melting period and at least a pre-heating period or a post-heating period. Also, the tile energy profile associated with each of the tiles can include an energy profile based on at least a residual stress of the tile, a microstructure of the tile, or a speed of the pulse.
In one or more embodiments, the controller can be configured to control the beam shaping component to adjust the beam energy profile to correspond to a tile energy profile of a first tile of the plurality of tiles to obtain a first beam energy profile. In one or more embodiments, the controller can be configured to apply a pulse of the laser beam with the first beam energy profile to the first tile to fuse a portion of the build piece corresponding to the first tile. In one or more embodiments, the controller can be configured to control the beam shaping component to adjust the beam energy profile to correspond to a tile energy profile of a second tile of the plurality of tiles to obtain a second beam energy profile, in which the second beam energy profile is different than the first beam energy profile. In one or more embodiments, the first beam energy profile and the second beam energy profile have different power densities over time. In one or more embodiments, a portion of the first tile and a portion of the second tile overlap. In one or more embodiments, the controller can be configured to apply a pulse of the laser beam with the second beam energy profile to the second tile to fuse a portion of the build piece corresponding to the second tile.
In one or more embodiments, the apparatus can include a sensor configured to measure a temperature of the first tile after the controller applies the pulse of the laser beam to the first tile. The apparatus can also include a camera configured to capture an image of the first tile after the controller applies the pulse of the laser beam to the first tile. The images captured by the camera can be used to observe how particular tiles or the layer of powder material generally has shifted from pre-fusing to the current status of the build piece fusing. In other words, the camera images can provide information on what parts of the layer of powder material have cooled, shifted, or otherwise moved positionally. The apparatus can further include a steering system having the laser beam source.
In another aspect of the present disclosure, a method of additively manufacturing a build piece is presented. The method includes depositing a layer of powder material in a powder bed. The method further includes obtaining information of the layer of powder material, the information including a plurality of tiles of the layer and a tile energy profile associated with each of the tiles. In one or more embodiments, the tile energy profile includes one or more parameters. For example, the parameters can include one or more of at least a length, a width, a depth, a power density, or a time. In one or more embodiments, the tile energy profile associated with each of the plurality of tiles includes an energy profile based on a geometry of the build piece.
The method also includes controlling a beam shaping component to adjust a beam energy profile associated with a laser beam to correspond to a tile energy profile of a first tile of the plurality of tiles to obtain a first beam energy profile. Additionally, the method includes applying a pulse of the laser beam with the first beam energy profile to the first tile to fuse a portion of the build piece corresponding to the first tile. The method can include controlling the beam shaping component to adjust a beam energy profile associated with the laser beam to correspond to a tile energy profile of a second tile of the plurality of tiles to obtain a second beam energy profile, in which the second beam energy profile is different than the first beam energy profile. In one or more embodiments, the first beam energy profile and the second beam energy profile have different power densities over time. In one or more embodiments, a portion of the first tile and a portion of the second tile overlap. Moreover, the method can include applying the pulse of the laser beam with the second beam energy profile to the second tile to fuse a portion of the build piece corresponding to the second tile.
In one or more embodiments, the method further includes determining a processing order of each of the plurality of tiles. In one or more embodiments, the method also includes determining a shape of the laser beam to be applied to each of the plurality of tiles. In one or more embodiments, the method can include determining a size of each of the plurality of tiles. In one or more embodiments, the method additionally includes determining a beam speed of the laser beam to be applied to each of the plurality of tiles.
In another aspect of the present disclosure, non-transitory computer-readable mediums storing computer-executable instructions for additively manufacturing a build piece executable by a processor to carry out the methods disclosed herein are further provided.
Other aspects will become readily apparent to those skilled in the art from the following detailed description, wherein is shown and described only several exemplary embodiments by way of illustration. As will be realized by those skilled in the art, concepts described herein are capable of other and different embodiments, and several details are capable of modification in various other respects, all without departing from the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Various aspects of the concepts described herein will now be presented in the detailed description by way of example, and not by way of limitation, in the accompanying drawings, wherein:
The detailed description set forth below in connection with the appended drawings is intended to provide a description of various exemplary embodiments of the concepts disclosed herein and is not intended to represent the only embodiments in which the disclosure may be practiced. The term “exemplary” used in this disclosure means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments presented in this disclosure. The detailed description includes specific details for the purpose of providing a thorough and complete disclosure that fully conveys the scope of the concepts to those skilled in the art. However, the disclosure may be practiced without these specific details. In some instances, well-known structures and components may be shown in block diagram form, or omitted entirely, in order to avoid obscuring the various concepts presented throughout this disclosure.
While this disclosure is generally directed to laser-based PBF (L-PBF) systems, it will be appreciated that such L-PBF systems may encompass a wide variety of AM techniques. Thus, the L-PBF process may include, among others, the following printing techniques: Direct metal laser sintering (DMLS), Selective laser melting (SLM) and Selective laser sintering (SLS). Still other PBF processes to which the principles of this disclosure are pertinent include those that are currently contemplated or under commercial development. While the specific details of each such process are omitted to avoid unduly obscuring key concepts of the disclosure, it will be appreciated that the claims are intended to encompass such techniques and related structures.
L-PBF systems can produce metal and polymer structures (referred to as build pieces) with geometrically complex shapes, including some shapes that are difficult or impossible to create using conventional manufacturing processes. L-PBF systems create build pieces layer-by-layer, i.e., slice-by-slice. Each slice may be formed by a process of depositing a layer of powder and fusing (e.g., melting and cooling) areas of the powder layer that coincide with the cross-section of the build piece in the slice. The process may be repeated to form the next slice of the build piece, and so on, until all the layers are deposited and the build piece is complete.
In conventional L-PBF systems, the path a laser takes across the top layer of powder (i.e., the scan pattern) is typically in patterns of parallel lines drawn back and forth across the current build layer. The orientation of the lines can vary in patches or be uniform for an entire layer. The L-PBF system then moves to the next layer and continues directing the laser beam in a pattern of stripes. For each layer, conventional L-PBF systems apply a constant energy profile.
Aspects of the present disclosure are directed to advantageous laser beam scan apparatuses, methods, and non-transitory computer readable mediums for L-PBF systems in which the build layer (e.g., a layer slice) is subdivided into identified areas (i.e., tiles), and then a customized energy profile of the laser beam is applied to each individual tile in the build layer. In one or more embodiments, the tiles are two-dimensional areas of the layer of powder. In one or more embodiments, the tiles are three-dimensional voxels of the layer of powder. The energy flux applied to each tile depends on one or more variables of the laser beam including the location of the application of the beam in two- or three-dimensions, the power of the beam, and the duration that the beam is activated and focused at a given tile. Thereafter, the L-PBF systems disclosed herein scan additional tiles and apply customized energy profiles to those respective tiles in order fuse those portions of the build piece in the build layer. Further, the systems and methods disclosed adjust the energy profiles of the laser beam to take into account the properties of different tiles in order to optimize a processing order of the tiles. For example, the adjustments of the energy profiles from tile to tile can improve the properties of the resulting build piece such as improved residual stress, improved fusing speed, or a desired microstructure in the build piece.
In one or more embodiments, tiles overlap at one or more edges of adjacent tiles. For example, where adjacent tiles share a border, the area or volume of each tile would extend slightly into the area or volume of each adjacent tile in order to provide a “stitch” design in which the build layer has no areas without tile coverage. The power of the L-PBF system may be tuned to permit fine overlap between the tiles. In one or more embodiments, tiles do not overlap the edges of adjacent tiles and instead the edges of adjacent tiles abut one another.
In the L-PBF systems disclosed herein, the laser beam may be configured to use variable beam or spot geometries (i.e., beam shaping) to increase build rate and provide additional control and flexibility of the manufacturing process. A laser spot is the area of a surface illuminated by a laser. Rather than use a laser beam configured as terminating in a tiny, almost point-like spot with a small radius that remains constant over time, a laser beam may instead be configured to use variable beam or spot geometries according to the direction of the scan based on the energy profile of the tile to be fused or the build piece. For example, the beam geometry—that is, the area of the surface of the print material illuminated by the laser—may be a line, a square, a rectangle, a triangle, an asymmetrical shape, or any other two-dimensional shape. The identified beam geometry can then be applied to the surface of the print material using two- or three-dimensional scanning. In so doing, the laser beam may be applied in a PBF print operation such that a larger contiguous area of the powder-bed may be processed at any given time. In an embodiment, the beam geometry can be dynamically altered during a 3-D print operation. Thus, for example, the L-PBF 3-D printer may fuse larger areas using a correspondingly large beam geometry, and subsequently or periodically, the 3-D printer may alter the beam geometry to a small line or an ordinary point-like shape to scan corner portions of the object and/or to fuse details of the build piece on a smaller scale.
In one or more embodiments, dynamic beam shaping as disclosed herein may be performed by varying beam focal length or beam intensity via a beam shaping component in order to change the beam shape using programmable laser beam sources. The beam shaping component may include one or more fixed or motorized optical elements of any necessary or suitable physical form. The beam shaping component may also include multiple diffracting, reflecting and refracting apparatus, such as diffractive beam splitters, diffractive diffusers, phase plates, lenses and mirrors. These laser beam sources can be programmed to output pulsed-type laser beams whose beam shapes vary according to the tile to be processed.
In accordance with aspects of the present disclosure, the laser beam geometry may be adapted based on the energy profiles of the object (build piece) to be produced according to the tile energy profile associated with each of a plurality of tiles in a build layer. The laser beam geometry may be adapted at the beginning of a scan, on a slice-by slice basis, on a tile-by-tile basis, at a designated time within a slice, or dynamically on the fly. Further, the laser beam geometry may also be varied continuously as the laser scans across the powder-bed, whose variance is in accordance with the contemplated structure of the object as identified in a computer aided design (CAD) profile, for example.
Employing the variable beam shaping may beneficially increase the throughput of the L-PBF process. Additionally, adapting the beam shaping as described herein may allow for application of laser power over a larger area to the powder bed, meaning that energy flux can be kept small to reduce vaporization of materials. Furthermore, given the nature of the adapted laser spot geometry, the energy profile of the spot geometry may be adjusted according to the scan vector (direction of scanning), to provide heating and cooling rate control. Controlling the cooling rate during the solidification process may allow reduction of thermal stresses and alterations of microstructure in the resultant component to achieve desired material properties. Further, the addition of three-dimensional energy flux in a particular powder layer also improves residual stress and the microstructure of the build piece.
In one or more embodiments, the process order of tiles that are fused can be optimized for various variables such as residual stress, build time speed, or material distribution on the build layer. For example, to manage residual stress in a tile, the laser beam can be pulsed according to different parameters to heat portions of the tile at different lengths, widths, or depths. The heating may occur below, at, or above the melting point of the powder in order to build portions of the build piece in respective tiles at that layer and stitch those portions to portions in adjacent layers (i.e., in the Z-axis) to manage residual stress during laser beam exposure. Further, the process order the of tiles can take into account the properties of adjacent tiles, including temperature, status of the build piece structure in those tiles, and the like. In one or more embodiments, the process order of the tiles is dynamically determined in substantially real-time.
The controller 102 or other processing system may coordinate the L-PBF additive manufacturing process. The controller 102 can be a central processing unit or other type of processor as is known. In one or more embodiments, the controller 102 may be operatively coupled to the positioning systems controlling the L-PBF system 100 based structures (e.g., depositor 101, laser beam source 103, beam shaping component 104, etc.). In this way, an organized timing of operations can be carefully coordinated by a central controller.
While the laser beam source 103 and the beam shaping component 104 have been generally identified as separate components, in some exemplary embodiments the functionality of both components may be included as part of a single integrated structure without departing from the scope of the disclosure.
In one or more embodiments the laser beam source 103 is contained within or coupled to a steering system or a Gantry system.
The L-PBF system 100 may also include a build floor 111 positioned within a powder bed receptacle. The walls of the powder bed receptacle 112 may generally define the boundaries of the powder bed receptacle, which is defined between the walls 112 from the side and a portion of the build floor 111 below. The build floor 111 may progressively lower build plate 107 such that depositor 101 may deposit a next layer of powder material. The L-PBF system 100 may additionally include a chamber 113 that may enclose the other components of L-PBF system 100 (e.g., controller 102, laser beam source 103, beam shaping component 104 and deflector 105), thereby protecting such other components, enabling atmospheric and temperature regulation and mitigating contamination risks. Further, the L-PBF system 100 may include a temperature sensor 122 to monitor the atmospheric temperature, the temperature of the powder 117 and/or components of the L-PBF system 100. Depositor 101 may include a hopper 115 that contains a powder 117, such as a metal powder, for example. The depositor 101 may also include a leveler 119 that may level the top of each layer of deposited powder (see e.g., powder layer 125 of
Referring specifically to
In one or more embodiments, information about the powder layer 125 can be obtained by one or more sensors 126 of the L-PBF system 100. Sensors 126 may capture information about powder layer 125 and other conditions within the chamber 113. For example, sensors 126 can collect information regarding the amount of powder in portions of the powder layer, the temperature of the layer at different portions of the powder layer, and other (including depth), or other characteristics of the layer. In one or more embodiments, sensors 126 are operatively coupled to controller 102 such that information collected by the sensors can be processed by the controller. In one or more embodiments, the controller 102 can receive information dividing the layer of powder material into a plurality of tiles or areas of the layer. In one or more embodiments, a tile energy profile is associated with each of the tiles. The tiles can form a grid, can overlap adjacent tiles, or be other shapes and sizes as necessary for the build piece.
In automated embodiments where temperature is closely monitored (e.g., using temperature sensors adjacent to the build piece), the order of tiles for printing may occur on the fly. That is, the controller may determine the order after printing has begun, based on the temperature of the deposited layers, the intended geometry of the finished build piece, or other factors.
Thereafter, the controller 102 can be configured to apply a pulse of the laser beam with the first beam energy profile to the first tile to fuse a portion of the build piece corresponding to the first tile. Deflector 105 may apply the laser beam 127 in the selected geometric shape to fuse the identified first tile in build piece 109. In various embodiments, the deflector 105 may include one or more gimbals and actuators that can rotate and/or translate the laser beam source 103 and/or beam shaping component 104 to position the laser beam 127. In various embodiments, laser beam source 103, beam shaping component 104 and/or deflector 105 can modulate the laser beam, e.g., turn the laser beam on and off as the deflector scans such that the laser beam is applied only in the appropriate areas of the powder layer. For example, in various embodiments, the laser beam can be modulated by a digital signal processor (DSP).
In some aspects, the controller 102 can be configured to control the beam shaping component 104 to adjust the beam energy profile to correspond to a tile energy profile of a second tile of the plurality of tiles to obtain a second beam energy profile. For example, the second beam energy profile is different than the first beam energy profile. Thereafter, the controller 102 can be configured to apply a pulse of the laser beam source 103 with the second beam energy profile to the second tile to fuse a portion of the build piece corresponding to the second tile.
In one or more embodiments, the beam energy profile can be adjusted based on a customized time profile. In other words, the controller can configure the laser beam to activate for a duration of t0 to t1 at an initial power, then from a duration of t1 to t2 at a revised power. For example, the controller can configure the laser beam to activate at a particular tile at 400 watts for a selected duration, then activate at that same tile at 600 watts for a different duration. Further, the controller can configure the system to scan the laser across the tile as the applied laser beam power is varied. In this way, the systems herein can time vary the energy input to achieve a desired microstructure in the build piece.
As shown in
With reference now to
As illustrated by
Each of the plurality of tiles 205 has an energy profile associated with each tile. An energy profile is a representation of the scanning to performed by the laser beam at the tile. These respective energy profiles correspond with the portion of the build piece to be fused in the respective tile area. These energy profiles can be different from tile to tile or may be the same. For example, as illustrated by
In one or more embodiments, in shaping the laser beam, an energy profile associated with a laser beam may be configured such that the energy levels may be adjusted along the three-dimensions of a respective tile 205. This laser beam energy profile represents the power density of the laser beam as applied to the tile 205 over time. In other words, the laser beam source can be tuned to produce a laser beam that is applied as a pulse to a particular tile at a certain power, at a certain location of the tile, and tuned to penetrate to a depth that matches the energy profile of the tile. As shown in
In one or more embodiments, the laser beam energy profile can be configured to preheat the powder material before heating the powders to melting, thermal fluctuation. Accordingly, resultant thermal stresses may be reduced.
Thereafter, the method 300 continues by obtaining information of the layer of powder material, the information including a plurality of tiles of the layer and a tile energy profile associated with each of the tiles, step 320. In one or more embodiments, a processing order of each of the plurality of tiles is determined. For example, the processing order of the tiles may be determined by optimizing tile processing order to generate a build piece having a desired residual stress or microstructure at particular tiles. In one or more embodiments, the processing order of the plurality of tiles takes into account the energy profile of adjacent tiles.
At step 325, the method 300 controls the beam shaping component to adjust the beam energy profile to correspond to a tile energy profile of a first tile of the plurality of tiles to obtain a first beam energy profile. Thereafter, a pulse of the laser beam is applied with the first beam energy profile to the first tile to fuse a portion of the build piece corresponding to the first tile, step 330. For example, the pulse of the laser beam can be applied at the first tile by scanning the laser beam across the tile in the horizontal plane of the tile. In some embodiments, the pulse of the laser beam can be turned off after the pulse is applied for a period of time, then the laser beam spot is moved to a different location in the tile according to the first tile energy profile and the pulse of the laser beam is applied again. In one or more embodiments, the pulse of the laser beam is fixed at a beam spot at the tile. In one or more embodiments, the pulse of the laser beam can have some slight movement about the beam spot at the tile. In one or more embodiments, the application of the pulse of the laser beam is carried out in view of the shape of the tile to be fused. For example, the pulse of the laser beam may be applied to the perimeter of a circular tile before applying the laser beam to the interior of the tile.
Optionally, the method 300 continues by measure, by a sensor, a temperature of the first tile after the controller applies the pulse of the laser beam to the first tile, step 335. Based on the temperature information, the pulse of the laser beam can be adjusted to optimize fusing portions of the build piece. Optionally, at step 340, the method 300 can include capturing, by a camera, an image of the first tile after the pulse of the laser beam has been applied to the first tile. By capturing images, the progress of the build piece can be reviewed and checked for possible fusing errors.
Thereafter, at step 345, the beam shaping component can be controlled to adjust the beam energy profile to correspond to a tile energy profile of a second tile of the plurality of tiles to obtain a second beam energy profile. In one or more embodiments, the second beam energy profile is different than the first beam energy profile. At step 350, the method 300 applies a pulse of the laser beam with the second beam energy profile to the second tile to fuse a portion of the build piece corresponding to the second tile.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these exemplary embodiments presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be applied to other support structures and systems and methods for removal of support structures. Thus, the claims are not intended to be limited to the exemplary embodiments presented throughout the disclosure, but are to be accorded the full scope consistent with the language claims. All structural and functional equivalents to the elements of the exemplary embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f), or analogous law in applicable jurisdictions, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
This application claims the benefit of U.S. Patent Application No. 63/417,983, entitled “TILE-BASED PRINTING WITH DYNAMIC BEAM SHAPING” and filed on Oct. 20, 2022, which is expressly incorporated by reference herein in its entirety as if set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 20240131589 A1 | Apr 2024 | US |
| Number | Date | Country | |
|---|---|---|---|
| 63417983 | Oct 2022 | US |
