Patent Application
20240140042
The invention relates to an apparatus and method for 3D printing with partial part rotation and reinforcement.
Typically, fused-filament fabrication (FFF) 3D printing involves printing filament in the X-Y plane, in a layer-by-layer fashion that creates successive layers to form the part. Optionally, continuous fibers can also be printed to reinforce the parts greatly increasing mechanical properties in the X-Y plane. Apparatuses and methods for printing continuous fiber are described, for example, in U.S. Pat. Nos. 10,076,876, 9,579,851, 9,694,544, 9,370,896, 11,237,542, 9,186,846, 9,186,848, and 9,688,028, each of which is incorporated by reference herein in its entirety.
FFF may suffer from poor strength in the Z direction. That is, a filament used in FFF-style planar 3D printing generally has anisotropic strength, wherein strength in the Z-axis is weaker compared to its strength in the X-Y axis. This is due to interlayer adhesion between successive layers.
FFF continuous fiber parts can exhibit high strength in the X-Y directions, such as more than 700 MPa. However, these materials when formed in parts also exhibit very low strength in the Z-direction (e.g., about 7 MPa). Continuous fiber parts can also exhibit significantly lower Z-strength than a comparable Z-strength of plastic matrix parts (e.g., about 20 MPa).
A length of fiber for a continuous fiber part is oriented perpendicular to the applied load. Composite stress concentrations are often concentrated at faces perpendicular to the applied load, that is for continuous fiber parts in the z-direction. Therefore, high stress concentrations and premature failure often present perpendicular to the applied load.
FFF with continuous fiber printing may suffer from poor strength in the Z direction to a greater relative extent. This is due to the high discrepancy in strength between continuous fibers (e.g., carbon fiber, glass fiber, and kevlar) and traditional thermoplastics (e.g., nylon, PET, PLA, PC, PEI). Continuous fibers may have strengths in the range of several thousand MPa, while plastics, even those reinforced with discontinuous fiber fillers, typically have strengths in the 50-150 MPa range. Thus even with ideal plastic interlayer adhesion, a 10× or greater difference in strength may exist between X-Y and Z direction.
Therefore, one constraint in conventional 3D printing, especially when utilizing continuous fiber printing, is that while produced parts may possess relatively strong tensile strength in bending or tension modes along the X and Y directions, the parts still have relatively weak tensile strength in the Z direction. 3D printed parts that require strength in multiple directions that may not be achievable with existing 3D printing methods.
Therefore, a need exists to print a 3D part that applies a filament to the partially-printed part in different orientations.
A need also exists to print a 3D part that is reinforced with continuous fiber oriented in different orientations.
One aspect of the present invention relates to an apparatus comprising at least one processor; and at least one memory, wherein the at least one memory stores computer-readable instructions which, when executed by the at least one processor, cause the processor to: control a 3D printer to perform a first 3D print operation to print one or more first layers of a part to form a partial part, the partial part being oriented at a first orientation; determine whether the partial part has been reoriented to a second orientation different from the first orientation; and after determining that the partial part has been reoriented to the second orientation, control the 3D printer to perform a second 3D print operation to print one or more second layers of the part on the partial part oriented at the second orientation.
Another aspect of the present invention relates to an apparatus comprising at least one processor; and at least one memory, wherein the at least one memory stores computer-readable instructions which, when executed by the at least one processor, cause the processor to: control a 3D printer to perform a first 3D print operation to print an alignment component; control the 3D printer to perform a second 3D print operation to print one or more first layers of a part to form a partial part, the partial part being oriented at a first orientation; control the re-orientation of the partial part to a second orientation, using the alignment component; and after determining that the partial part has been reoriented to the second orientation, control the 3D printer to perform a third 3D print operation to print one or more second layers of the part on the partial part oriented at the second orientation.
Yet another aspect of the present invention relates to a method comprising controlling a 3D printer to perform a first 3D print operation to print one or more first layers of a part to form a partial part, the partial part being oriented at a first orientation; determining whether the partial part has been reoriented to a second orientation different from the first orientation; and after determining that the partial part has been reoriented to the second orientation, controlling a 3D printer to perform a second 3D print operation to print one or more second layers of the part on the partial part oriented at the second orientation.
These and other aspects of the invention will become apparent from the following disclosure.
The present invention relates to an apparatus and method of printing a part that provides fiber alignment along multiple planes. Such printing may be accomplished by, for example, rotating a partially-printed part before continuing printing, according to the present invention.
Printing in multiple directions via part rotation provides multiple benefits. For example, such printing may provide greater flexibility in producing a 3D part. In some instances, it is difficult to print in small corners or tight spaces without the print head undesirably contacting the part. One solution achieved by the present invention is to print a partial part, rotate the partial part, print a shell, and then rotate back and continue printing the base part. Of course, it will be recognized that the ability to use this functionality may depend on the part design. This approach may be combined with printing a continuous fiber shell (e.g., in different fiber orientation), which may further improve, for example, tensile strength, flexural strength, stiffness, wear resistance, and/or impact strength.
Another benefit of part rotation functionality improved strength by reinforcement in orientations other than the X-Y plane. For example, continuous fiber (e.g., carbon (CCF), glass, or kevlar fiber)) may be printed on the side of parts to reinforce and improve the Z-strength of plastic-only and fiber-reinforced 3D printed materials.
One benefit of this functionality is an improvement in Z-strength of 3D printed parts in a composite system. Based on experiments conducted by the inventors (such as that described below), printing CCF on the outside of the part in the Z-direction may improve the strength, e.g., from 6 MPa to >250 MPa.
3D Printer Apparatus
The apparatus 1000 includes a gantry 1010 that supports the print heads 10, 18. The gantry 1010 includes motors 116, 118 to move the print heads 10, 18 along X and Y rails in the X and Y directions, respectively. The apparatus 1000 also includes a build platen 16 (e.g., print bed) on which an object to be printed is formed. The height of the build platen 16 is controlled by a motor 120 for Z direction adjustment. Although the movement of the apparatus has been described based on a Cartesian arrangement for relatively moving the print heads in three orthogonal translation directions, other arrangements are considered within the scope of, and expressly described by, a drive system or drive or motorized drive that may relatively move a print head and a build plate supporting a 3D printed object in at least three degrees of freedom (i.e., in four or more degrees of freedom as well). For example, for three degrees of freedom, a delta, parallel robot structure may use three parallelogram arms connected to universal joints at the base, optionally to maintain an orientation of the print head (e.g., three motorized degrees of freedom among the print head and build plate) or to change the orientation of the print head (e.g., four or higher degrees of freedom among the print head and build plate). As another example, the print head may be mounted on a robotic arm having three, four, five, six, or higher degrees of freedom; and/or the build platform may rotate, translate in three dimensions, or be spun.
The filament 2 is fed through a nozzle 10a disposed at the end of the print head 10, and heated to extrude the filament material for printing. In the case that the filament 2 is a fiber reinforced composite filament, the filament 2 is heated to a controlled push-pultrusion temperature selected for the matrix material to maintain a predetermined viscosity, and/or a predetermined amount force of adhesion of bonded ranks, and/or a surface finish. The push-pultrusion may be greater than the melting temperature of the polymer 4, less than a decomposition temperature of the polymer 4 and less than either the melting or decomposition temperature of the core 6.
After being heated in the nozzle 10a and having its material substantially melted, the filament 2 is applied onto the build platen 16 to build successive layers 14 to form a three dimensional structure. One or both of (i) the position and orientation of the build platen 16 or (ii) the position and orientation of the nozzle 10a are controlled by a controller 20 to deposit the filament 2 in the desired location and direction. Position and orientation control mechanisms include gantry systems, robotic arms, and/or H frames, any of these equipped with position and/or displacement sensors to the controller 20 to monitor the relative position or velocity of nozzle 10a relative to the build platen 16 and/or the layers 14 of the object being constructed. The controller 20 may use sensed X, Y, and/or Z positions and/or displacement or velocity vectors to control subsequent movements of the nozzle 10a or platen 16. The apparatus 1000 may optionally include a laser scanner 15 to measure distance to the platen 16 or the layer 14, displacement transducers in any of three translation and/or three rotation axes, distance integrators, and/or accelerometers detecting a position or movement of the nozzle 10a to the build platen 16. The laser scanner 15 may scan the section ahead of the nozzle 10a in order to correct the Z height of the nozzle 10a, or the fill volume required, to match a desired deposition profile. This measurement may also be used to fill in voids detected in the object. The laser scanner 15 may also measure the object after the filament is applied to confirm the depth and position of the deposited bonded ranks. Distance from a lip of the deposition head to the previous layer or build platen, or the height of a bonded rank may be confirmed using an appropriate sensor.
Various 3D-printing aspects of the apparatus 1000 are described in detail in U.S. Patent Application Publication No. 2019/0009472, which is incorporated by reference herein in its entirety.
3D Printing Operation with Rotation
In step S220, the controller 20 instructs the user to remove the partially-printed part from the build platen, re-orient the part to a predetermined different orientation (e.g., rotation by 90°), and place the partially-printed part back on the build platen. For example, a part may have been initially partially printed in the X-Y orientation, and in this step, the controller 20 instructs the user to rotate the part by 90° so that the Z-X orientation faces upward and is parallel to the X-Y plane.
The partially-printed part may be placed back on the build platen in a variety of different ways. In one embodiment, the partially-printed part is simply placed on the build platen (e.g., if the bottom surface of the part and/or the build platen is rough or textured to provide sufficient grip). In one embodiment, an adhesive (e.g., double-sided tape) or other fastening mechanism is used to retain the partial part on the build platen. In one embodiment, the build platen includes one or more alignment features, such as side or corner rail(s) (or other topographical feature), to receive a portion of the partially-printed part and aid in alignment. In one embodiment, one or more alignment features (e.g., alignment frame(s) or bracket(s)) is printed to aid in alignment and/or support the partially-printed part, prevent movement during printing, and allow easy removal. The user then utilizes the feature to align the partial part when placing the partially-printed part back on the build platen. In one embodiment, a custom build platen with clamps is used to retain the part. In one embodiment, a breadboard-style build platen with a variety of different mounting points (similar to an optical breadboard plate or a build plate used in machining) may be used.
In step S230, the controller 20 controls a sensor to scan the build platen to determine positioning of the partially-printed part and to confirm accurate rotation. For example, the scanning may be performed using the laser scanner 15 and/or a camera vision component. The scanning of the build platen may allow for compensation of any reorientation that is not exactly as specified (e.g., 90° rotation that is slightly off in reality). In this step, the controller may utilize the scan data to detect any warp in the partially-printed part.
In step S240, the controller 20 controls the apparatus 1000 to continue printing the partially-printed part. In one embodiment, the continued printing may compensate for any deviations determined in step S230 (e.g., one or more of translational deviations, rotational deviations, and warp)
In step S250, the controller 20 determines whether any further rotations are required to complete the printing of the part. If one or more further rotations are required, the operation returns to step S220. If no further rotations are required and the part has been fully printed, the operation ends.
3D Printing Operation with Rotation and Reinforcement
In step S310, the controller 20 initiates the 3D-printing operation of a part and prints a partial part.
In step S320, the controller 20 instructs the user to remove the partially-printed part from the build platen, re-orient the part to a predetermined different orientation (e.g., rotation by 90°), and place the partially-printed part back on the build platen (similar to step S220). When placing the partially-printed part back on the build platen, the part is optionally adhered (e.g., glued) to the build platen 16. Then printing resumes.
In step S330, the controller 20 controls a sensor to scan the build platen to determine positioning of the rotated partially-printed part and to confirm accurate rotation (similar to step S230). For instance, the controller 20 may utilize the laser scanner 15 and/or a camera vision system (not shown) as the sensor.
In optional step S340, the controller 20 controls the print head 10 and/or print head 18 to apply one or more planarizing layers on the rotated partially-printed part. The planarizing layer(s) provides a leveling of the current top surface, thereby allowing the generation of an exact Z-height and compensation for variations in Z-height due to warping or differences in coefficient of thermal expansion. The planarizing layer(s) may also provide easier adhesion to such top surface in subsequent printing of additional layers. In one embodiment, the planarizing layer(s) may be formed as one or more plastic layers totaling between 100-250 m in height.
In step S350, the controller 20 controls the print head 10 and/or print head 18 to apply one or more reinforcement layers (e.g., CCF) on the rotated partially-printed part. In the case that one or more planarizing layers was applied in step S340, the reinforcement layer(s) may be applied on the planarizing layer(s). In the case that no planarizing layer was applied, the reinforcement layer(s) may be applied on the print material forming the partially-printed part. For example, the reinforcement layer(s) may reinforce the vulnerable Z-strength areas by providing a continuous fiber shell, allowing continuous fiber reinforcement in additional orientations beyond simply the X-Y orientation (from the perspective of the frame of reference of the original partially-printed part).
In optional step S360, the controller 20 controls the print head 10 and/or print head 18 to apply one or more additional layers of print material on the rotated partially-printed part. For example, these additional layers may form the outer layer(s) of the final part. In one embodiment, the print material used for these additional layers is plastic and/or polymer, to provide a desired outer part surface quality. Depending on where the reinforcement is provided within the part, this step may involve the application of multiple layers to complete this portion of the part.
In step S370, the controller 20 determines whether any further rotations are required in order to complete the printing and/or reinforcement of the part. If further rotations are needed to continue printing the part, the operation returns to step S320. If no further rotations are needed to continue printing the part, the part is completed and the operation ends.
Alignment/Support Components
As described above, one or more alignment/support features may be employed to assist in accurately re-positioning the part after it is removed from and placed back on the build platen 16. Examples of such features are illustrated in
In one embodiment, the apparatus 1000 prints the alignment/support features 510 directly onto the build platen 16 prior to printing of the part 550, and the printed alignment/support features 510 are used for aligning and/or supporting the part 550 during printing of the part 550.
In one embodiment, the alignment/support features 510 are integrated with the surface of the build platen 16. For example, the build platen 16 may be configured as a custom-designed component having alignment/support features 510 specific to the dimensions and geometry of the part to be printed.
It will be recognized that while alignment/support features provided on the build platen may be used to align the part on the built platen, these features in some circumstances may not be able to sufficiently fix or hold the part in place during the printing process for certain part geometries (e.g., tall parts). Therefore, another approach to align/support the part may incorporate a clamping mechanism.
A benefit of using alignment frame(s) is that the alignment frame(s) 540 provide full assistance in the user's efforts to re-orient the part 550, in that the alignment frame(s) 540, rather than the user's control, establishes proper alignment. For example, the user does not need to position or adjust the alignment frame(s) 540, but instead simply inserts the part 550 into the alignment frame(s) 540, which is configured to receive the part 550 in a specific orientation, thereby re-orienting the part 550. That is, the alignment frame(s) 540 are already in correct alignment with respect to the build platen 16, such that the inserted partially-printed part 550 is correctly oriented once inserted. Yet another benefit of using such an alignment frame 540 is that such frame 540 may abut/fix the part 550 in multiple locations to hold the part 550 steady during the printing process.
While the retention mechanism 530 depicted in
Advantages of using the build platen 16 and/or a build platen extension 520 include a faster overall printing operation compared to using an alignment bracket (such as that described below), which may need to be separately 3D-printed. Software may also be employed for an automated design of a custom build platen extension that fits the specific geometry of the part to be printed. An additional benefit of using such a custom build platen extension 520 is that such extension 520 may further be designed to abut/fix the part at multiple locations to hold the part 550 steady during the printing process.
Any of the above-described build platen or extension components may include one or more of (i) a retention mechanism 530 for retaining the component(s) to the build platen 16 (as illustrated in
The build platen extension 560 may be similar to the build platen extension 520 described above with reference to
Furthermore, in one embodiment, a bolt 570 is inserted through the bolt hole 560a of the build platen extension 560 and through the bolt hole 16a of the build platen 16, thereby securing the alignment between (and also coupling) the build platen extension 560 and the build platen 16.
In one embodiment, a build plate (e.g., having a circular or other profile) may be 3D-printed as a solid or hollow frame and configured with a custom geometry to fit and receive the partially-printed part. The build plate may be configured allow for rotation in multiple axes, thereby also rotating the partially-printed part contained therein. Following the rotation of the build plate, printing of the partially-printed part resumes.
Experimental Results
The benefits of adding reinforcement shells/layers to a printed part include an increase in strength, stiffness, toughness, and/or hardness in the Z-direction. Additional potential benefits include, but are not limited to, improved thermal conductivity, electrical conductivity, electrical dissipation, radiative emissions or absorption, aesthetics, sensing, chemical resistance, flame resistance, etc.
It will be appreciated that while adding reinforcement shells to simple parts provided these benefits, the inventors also experimented as to whether this approach likewise provided improvements for complicated parts with complex features.
The results from strength-testing of these plates are shown in
In this experiment, the brackets were printed in the X-Y orientation (as illustrated in
In addition, as a bracket, the example part can be easily tested for strength by providing a metal bar that spans across the center and through the two vertical holes, as illustrated in
There are various approaches available in printing the part for comparison in the experiment. A first approach involves 3D printing the part in an X-Y orientation, including variants with and without reinforcement. Under this approach, the sides loaded in tensile are reliant on the part's Z-strength, and therefore have relatively low strength.
A second approach involves 3D printing the part in an Z-X orientation, including variants with and without reinforcement. Under this approach, the flexural base is dependent on Z-strength and has low strength. While this print orientation may be preferable to printing in the X-Y direction under the first approach, this approach may only provide for reinforcement of one side, rather than both sides.
A third approach involves 3D printing the part in an X-Z direction, including variants with and without reinforcement. This approach achieves similar plastic strength in the sides and the base as the second approach, but does not support continuous reinforcement. As such, the overall strength may not be sufficient.
A fourth approach involves printing the base and side components separately, and then manually coupling the two components together afterwards (as described below in operation S900). This approach may overcome poor strength issues suffered in the previously-described approaches. However, the approach requires an extra assembly step and therefore may not be universally suitable.
A fifth approach involves 3D printing the part that incorporates rotation of the partially-printed part, according to the present invention. By having access to each side through the rotation(s), reinforcement may be provided on both the base and the sides. The entire part also may be printed at once as a single component, rather than as separate components which requires assembly as in the fourth approach. Additionally, the printing of the entire part provides improved thermal bonding, thereby providing an advantage over the fourth approach where the coupling of the base and the sides may require adhesives or fasteners that reduce thermal bonding. One example of printing the bracket under this approach may include printing one side and reinforcing that side, rotating the partial part, printing an adjacent side and reinforcing that side, rotating the partial part, and printing the remaining side and reinforcing that side.
As explained above, the testing of these approaches involved loading the respective bracket with a single bar through the center of the bottom and a cross bar at the top through two vertical holes, as illustrated in
In the case that printing of the bracket is limited to the X-Y orientation, continuous fiber reinforcement may only be placed in the bottom, and the sides lack reinforcement. Printed sides were reinforced with continuous fiber shells in accordance with the methods disclosed herein
One aspect of the invention relates to compensation for warp when applying reinforcement. For example, some part geometries may warp if reinforcement shells are added in an unsymmetrical fashion (e.g., a flat plate may begin to warp once the shell is added to one side). The warping may, for example, be caused by differences in coefficient of thermal expansion (CTE) between the base part and the CCF shell, from non-symmetrical or offset part geometries (e.g., non-symmetric sandwich panels or inward warping of tall vertical sides), or based on other causes.
A first approach to reducing or eliminating warping during the application of a reinforcement shell is to keep the part warm until both shells have been added and/or using parts with a sparse isotropic infill (e.g., gyroid).
A second approach to compensate for part warp (e.g., especially if the warping is only a small amount) is to print a thicker planarizing plastic layer (e.g., 200 μm initial plastic layer instead of a 100 μm plastic layer that may be more sensitive to warp) as part of step S340 described above. Additionally, a smaller layer of polymer may be added in “low spots” to create a flat surface prior to depositing the CCF shell layers (e.g., as part of step S340 described above). For instance, the laser scanner 15 may be used to scan the top surface of the partially-printed part and create a topographical profile and identify any warping or “low spots” on the top surface.
Another aspect of the invention relates to forming a part by separately printing components of a part, each component having its own fiber orientation, and then combining the components as the complete part. That is, out-of-plane fiber inserts are separately printed and combined to form a part. In particular, different components of the part may be separately printed in multiple pieces, each component containing reinforcement (e.g., CCF). After the separate components are printed, the components are mechanically combined, resulting in a complete part where printed layers and the fibers they contain lie in multiple planes in the final assembly. This approach allows the final parts to possess high strength in all axes. Notably, this approach improves Z-axis strength, which is a significant drawback of conventional FFF-style 3D printing. This approach also allows for customization of part strength characteristics for target loads.
As one example, a part may be formed by printing a rectangular pin containing multiple fiber layers, each aligned along the X-Y plane. For example, the dimensions of the pin may be 10 cm (X)×2 cm (Y)×1 cm (Z). The pin is removed from the build platen, and another part is printed which contains a negative cutout of the pin with a long-axis in the Z direction (e.g., contains a 2 cm (X)×1 cm (Y)×10 cm (Z) void) and is printed as customary based on successive layers in the X-Y axis. Then, the pin is inserted into the void and mechanically coupled (e.g., with an adhesive). The resulting final part would contain fibers in both the X-Y and Y-Z planes, as opposed to solely in the X-Y plane in the case of conventional 3D printing.
In step S930, the apparatus 1000 instructs a user to couple together the first part component and the second part component. For example, the apparatus 1000 may display instructions and illustrations on a display as to the coupling process, including the orientation of each part component relative to the other part component. The coupling may be accomplished by, e.g., an adhesive or by mechanical coupling.
Additional functionality that may be combined with the operation S900 includes:
Incorporation by reference is hereby made to U.S. Pat. Nos. 10,076,876, 9,149,988, 9,579,851, 9,694,544, 9,370,896, 9,539,762, 9,186,846, 10,000,011, 10,464,131, 9,186,848, 9,688,028, 9,815,268, 10,800,108, 10,814,558, 10,828,698, 10,953,609, U.S. Patent Application Publication No. 2016/0107379, U.S. Patent Application Publication No. 2019/0009472, U.S. Patent Application Publication No. 2020/0114422, U.S. Patent Application Publication No. 2020/0361155, U.S. Patent Application Publication No. 2020/0371509, and U.S. Provisional Patent Application No. 63/138,987 in their entireties.
Although this invention has been described with respect to certain specific exemplary embodiments, many additional modifications and variations will be apparent to those skilled in the art in light of this disclosure. For instance, while reference has been made to an X-Y Cartesian coordinate system, it will be appreciated that the aspects of the invention may be applicable to other coordinate system types (e.g., radial). It is, therefore, to be understood that this invention may be practiced otherwise than as specifically described. Thus, the exemplary embodiments of the invention should be considered in all respects to be illustrative and not restrictive, and the scope of the invention to be determined by any claims supportable by this application and the equivalents thereof, rather than by the foregoing description.
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/419,827, filed Oct. 27, 2022, and titled “3D PRINTING WITH PARTIAL PART ROTATION AND REINFORCEMENT,” the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63419827 | Oct 2022 | US |
