SYSTEM AND HEAD FOR CONTINUOUSLY MANUFACTURING COMPOSITE STRUCTURE
1. A system for additively manufacturing a composite structure, comprising:
- a print head, including;
a discharge outlet configured to discharge a continuous reinforcement; and
an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge;
a support configured to move the print head during discharging; and
a controller configured to selectively activate the support based on known specifications for the composite structure.
A print head is disclosed for use in an additive manufacturing system. The print head may include a discharge outlet configured to discharge a continuous reinforcement, and an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge. The print head may also include a cure enhancer configured to soften the solid film after discharge.
- 1. A system for additively manufacturing a composite structure, comprising:
a print head, including; a discharge outlet configured to discharge a continuous reinforcement; and an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge; a support configured to move the print head during discharging; and a controller configured to selectively activate the support based on known specifications for the composite structure.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- 15. A print head for an additive manufacturing system, comprising:
a discharge outlet configured to discharge a continuous reinforcement; an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge; and a cure enhancer configured to soften the solid film after discharge.
- View Dependent Claims (16, 17, 18, 19, 20)
This application is based on and claims the benefit of priority from U.S. Provisional Application No. 62/656,866 that was filed on Apr. 12, 2018, the contents of which are expressly incorporated herein by reference.
The present disclosure relates generally to a manufacturing system and, more particularly, to a system and print head for continuously manufacturing composite structures.
Continuous fiber 3D printing (a.k.a., CF3D™) involves the use of continuous fibers embedded within a matrix discharging from a moveable print head. The matrix can be a traditional thermoplastic, a powdered metal, a liquid resin (e.g., a UV curable and/or two-part resin), or a combination of any of these and other known matrixes. Upon exiting the print head, a head-mounted cure enhancer (e.g., a UV light, an ultrasonic emitter, a heat source, a catalyst supply, etc.) is activated to initiate and/or complete curing of the matrix. This curing occurs almost immediately, allowing for unsupported structures to be fabricated in free space. When fibers, particularly continuous fibers, are embedded within the structure, a strength of the structure may be multiplied beyond the matrix-dependent strength. An example of this technology is disclosed in U.S. Pat. No. 9,511,543 that issued to Tyler on Dec. 6, 2016 (“the '"'"'543 patent”).
Although CF3D™ provides for increased strength, compared to manufacturing processes that do not utilize continuous fiber reinforcement, improvements can be made to the structure and/or operation of existing systems. The disclosed additive manufacturing system is uniquely configured to provide these improvements and/or to address other issues of the prior art.
In one aspect, the present disclosure is directed to a print head for an additive manufacturing system. The print head may include a discharge outlet configured to discharge a continuous reinforcement, and an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge. The print head may also include a cure enhancer configured to soften the solid film after discharge.
In another aspect, the present disclosure is directed to a system for additively manufacturing a composite structure. This system may include a print head having a discharge outlet configured to discharge a continuous reinforcement, and an applicator disposed upstream of the discharge outlet and configured to apply a solid film to the continuous reinforcement prior to discharge. The system may also include a support configured to move the print head during discharging, and a controller configured to selectively activate the support based on known specifications for the composite structure.
Head 16 may be configured to receive or otherwise contain a matrix material. The matrix material may include any type of matrix material (e.g., a liquid resin, such as a zero-volatile organic compound resin, a powdered metal, etc.) that is curable. Exemplary resins include thermosets, single- or multi-part epoxy resins, polyester resins, cationic epoxies, acrylated epoxies, urethanes, esters, thermoplastics, photopolymers, polyepoxides, thiols, alkenes, thiol-enes, and more. In one embodiment, the matrix material inside head 16 may be pressurized, for example by an external device (e.g., by an extruder or another type of pump—not shown) that is fluidly connected to head 16 via a corresponding conduit (not shown). In another embodiment, however, the pressure may be generated completely inside of head 16 by a similar type of device. In yet other embodiments, the matrix material may be gravity-fed into and/or through head 16. For example, the matrix material may be fed into head 16, and pushed or pulled out of head 16 along with one or more continuous reinforcements. In some instances, the matrix material inside head 16 may need to be kept cool and/or dark in order to inhibit premature curing or otherwise obtain a desired rate of curing after discharge. In other instances, the matrix material may need to be kept warm for similar reasons. In either situation, head 16 may be specially configured (e.g., insulated, temperature-controlled, shielded, etc.) to provide for these needs.
The matrix material may be used to coat any number of continuous reinforcements (e.g., separate fibers, tows, rovings, socks, and/or sheets of continuous material) and, together with the reinforcements, make up a portion (e.g., a wall) of composite structure 12. The reinforcements may be stored within or otherwise passed through head 16. When multiple reinforcements are simultaneously used, the reinforcements may be of the same material composition and have the same sizing and cross-sectional shape (e.g., circular, square, rectangular, etc.), or a different material composition with different sizing and/or cross-sectional shapes. The reinforcements may include, for example, carbon fibers, vegetable fibers, wood fibers, mineral fibers, glass fibers, metallic wires, optical tubes, etc. It should be noted that the term “reinforcement” is meant to encompass both structural and non-structural types of continuous materials that are at least partially encased in the matrix material discharging from head 16.
The reinforcements may be exposed to (e.g., at least partially coated with) the matrix material while the reinforcements are inside head 16, while the reinforcements are being passed to head 16, and/or while the reinforcements are discharging from head 16. The matrix material, dry reinforcements, and/or reinforcements that are already exposed to the matrix material may be transported into head 16 in any manner apparent to one skilled in the art. In some embodiments, a filler material (e.g., chopped fibers) may be mixed with the matrix material before and/or after the matrix material coats the continuous reinforcements.
One or more cure enhancers (e.g., a UV light, an ultrasonic emitter, a laser, a heater, a catalyst dispenser, a chiller, etc.) 18 may be mounted proximate (e.g., within, on, or adjacent) head 16 and configured to enhance a cure rate and/or quality of the matrix material as it is discharged from head 16. Cure enhancer 18 may be controlled to selectively expose portions of structure 12 to energy (e.g., a positive or negative energy such as UV light, electromagnetic radiation, vibrations, heat, a chemical catalyst, a chilled medium, etc.) during the formation of structure 12. The energy may increase a rate of chemical reaction occurring within the matrix material, sinter the material, harden the material, or otherwise cause the material to cure as it discharges from head 16. The amount of energy produced by cure enhancer 18 may be sufficient to cure the matrix material before structure 12 axially grows more than a predetermined length away from head 16. In one embodiment, structure 12 is completely cured before the axial growth length becomes equal to an external diameter of the matrix coated reinforcement.
The matrix material and/or reinforcement may be discharged from head 16 via at least two different modes of operation. In a first mode of operation, the matrix material and/or reinforcement are extruded (e.g., pushed under pressure and/or mechanical force) from head 16 as head 16 is moved by support 14 to create the 3-dimensional trajectory within a longitudinal axis of structure 12. In a second mode of operation, at least the reinforcement is pulled from head 16, such that a tensile stress is created in the reinforcement during discharge. In this mode of operation, the matrix material may cling to the reinforcement and thereby also be pulled from head 16 along with the reinforcement, and/or the matrix material may be discharged from head 16 under pressure along with the pulled reinforcement. In the second mode of operation, where the matrix material is being pulled from head 16 with the reinforcement, the resulting tension in the reinforcement may increase a strength of structure 12 (e.g., by aligning the reinforcements, inhibiting buckling, equally distributing loads, etc.), while also allowing for a greater length of unsupported structure 12 to have a straighter trajectory. That is, the tension in the reinforcement remaining after curing of the matrix material may act against the force of gravity (e.g., directly and/or indirectly by creating moments that oppose gravity) to provide support for structure 12.
The reinforcement may be pulled from head 16 as a result of head 16 moving away from an anchor point 20. In particular, at the start of structure formation, a length of matrix-impregnated reinforcement may be pulled and/or pushed from head 16, deposited onto anchor point 20, and cured such that the discharged material adheres (or is otherwise coupled) to anchor point 20. Thereafter, head 16 may be moved away from anchor point 20, and the relative movement may cause the reinforcement to be pulled from head 16. It should be noted that the movement of reinforcement through head 16 could be assisted (e.g., via internal head mechanisms), if desired. However, the discharge rate of reinforcement from head 16 may primarily be the result of relative movement between head 16 and anchor point 20, such that tension is created within the reinforcement. It is contemplated that anchor point 20 could be moved away from head 16 instead of or in addition to head 16 being moved away from anchor point 20.
A controller 22 may be provided and communicatively coupled with support 14, head 16, and any number of cure enhancers 18. Each controller 22 may embody a single processor or multiple processors that are configured to control an operation of system 10. Controller 22 may include one or more general or special purpose processors or microprocessors. Controller 22 may further include or be associated with a memory for storing data such as, for example, design limits, performance characteristics, operational instructions, tool paths, and corresponding parameters of each component of system 10. Various other known circuits may be associated with controller 22, including power supply circuitry, signal-conditioning circuitry, solenoid driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, controller 22 may be capable of communicating with other components of system 10 via wired and/or wireless transmission.
One or more maps may be stored in the memory of controller 22 and used during fabrication of structure 12. Each of these maps may include a collection of data in the form of lookup tables, graphs, and/or equations. In the disclosed embodiment, the maps may be used by controller 22 to determine the movements of head 16 required to produce the desired size, shape, and/or contour of structure 12, and to regulate operation of cure enhancers 18 in coordination with the movements.
As shown in
Continuous reinforcements (R) may enter matrix chamber 23 via inlet valve 26 and be selectively coated with a matrix (M) therein. Inlet valve 26 may allow passage of the continuous reinforcements into head 16, while at the same time inhibiting matrix from passing out of matrix chamber 23. It is contemplated that the continuous reinforcements may already be at least partially coated with the same or a different matrix upstream of head 16 (e.g., via a stand-alone bath and/or dedicated jets—not shown), if desired. The dry or pre-coated continuous reinforcements may be coated for the first time or receive additional coatings of matrix and/or filler material (e.g., chopped fibers, powdered metal, powdered thermoplastics, etc.) during passage through matrix chamber 23. In the disclosed embodiment, any number of applicators (e.g., low- and/or high-pressure jets) 28 may be used for this purpose. One or more rollers (e.g., a pair of opposing rollers) 30 may be located at an outlet end of matrix chamber 23 and selectively activated (e.g., by controller 22) to pull the matrix-coated continuous reinforcements past applicator(s) 28.
After exiting matrix chamber 23, the matrix-coated continuous reinforcements may pass through another valve 32 into a vacuum chamber 34, in which air bubbles entrained in the matrix may be removed from the composite material. Although a reduced atmospheric pressure within vacuum chamber 34 may be sufficient alone to remove the air bubbles, an optional compactor 36 may be available within vacuum chamber 34 to help press the air bubbles out of the composite material. In addition, compactor 36 may help to consolidate (e.g., to press together) the continuous reinforcements and/or to achieve a precise dimension (e.g., thickness and/or width) of the composite material. In the embodiment of
In some embodiments, in addition to facilitating bubble removal and/or compaction of the composite material, compactor 36 may also be used to apply a film 38 (shown as F in
It is contemplated that the film (e.g., the thermoplastic ribbon) could be specially formulated for integration with and bonding to the matrix (e.g., a thermoset resin) coating the continuous reinforcements, thereby reducing the formation of a potential separation zone. For example, the film could be porous (see
In order to help maintain a low-porosity (i.e., a reduced concentration of air bubbles) within the composite material, it may be necessary to preserve the reduced atmospheric pressure imparted by vacuum chamber 34. This may be achieved, for example, by sealing transverse edges of the film. For this purpose, a ribbon edge fuser 40 may be provided. Ribbon edge fuser 40 may embody, for example, an ultrasonic welder, a heated die or roller, etc. that applies vibrations, heat, light, and/or pressure to cause the transverse sides of opposing film layers to bond to each other and thereby create an enclosed bag around the internal composite core.
After the film is fused to the underlying matrix-coated (or dry) continuous reinforcements, the resulting feedstock may be stiffer than the matrix-coated (or dry) continuous reinforcements alone. This increased stiffness may allow for the feedstock to be pushed out of head 16, in some applications, without the risk of the feedstock buckling and/or clogging discharge outlet 24. A feeder 42 (e.g., an additional set of rollers) may be located immediately upstream of discharge outlet 24 (and/or inside of discharge outlet 24) to push the feedstock through discharge outlet 24.
In some applications, a cutter 44 may be located downstream of feeder 42. Cutter 44 may embody, for example, an angled blade that is configured to move through the film-coated composite material and against an associated anvil. It is contemplated, however, that other types of cutters 44 (e.g., ultrasonic cutters, lasers, opposing blades, plasma cutters, etc.) may alternatively be used for this purpose, if desired. One or more actuators (not shown) could be associated cutter 44 and configured to move and/or energize cutter 44 when commanded to do so by controller 22 (referring to
Upon being extruded from discharge outlet 24, cure enhancers 18 may be used to soften (e.g., melt) the film and/or initiate a hardening reaction of the matrix inside of the film. In the disclosed example, cure enhancers are UV lights, lasers, or IR heaters. It should be recognized, however, that other cure enhancers (e.g., microwave cure enhancers, ultrasonic cure enhancers, etc.) could be used in addition to or in place of the depicted cure enhancers 18 of
It is contemplated that the film described above could be used selectively, in some applications. For example, it may be necessary to use the film only during startup of a new discharging path (e.g., after operation of cutter 44). This may allow head 16 to push a new lead of material from discharge outlet 24, without the risk of buckling or clogging described above. Thereafter (e.g., after bonding of the new lead of material to anchor point 20 or a previously discharged layer), the rollers of compactor 36 may be moved out of the way, allowing the composite material to thereafter be pulled from discharge outlet 24 without the film coating during movement of head 16 away from the anchoring location.
It is also contemplated that the film could be removed from the composite core after discharge from head 16, if desired. For example, the film may be only temporarily applied, and taken back up by external rollers (not shown) located adjacent the tip end of discharge outlet 24. In this manner, the film may support pushing of the composite material, while not affecting bonding between adjacent layers of the composite material. In this embodiment, the film may be made from any suitable material.
Finally, while the disclosed embodiments are described as utilizing a reinforcement-coating matrix inside of one or more film layers, it is contemplated that the film layers may be applied to the continuous reinforcements without any internal matrix (i.e., dry reinforcements), if desired. That is, the composite material discharging from head 16 could simply include continuous reinforcements cladded with a film, which is softened and/or melted during discharge.
The disclosed systems may be used to continuously manufacture composite structures having any desired cross-sectional shape and length. The composite structures may include any number of different fibers of the same or different types and of the same or different diameters, and any number of different matrixes of the same or different makeup. Operation of system 10 will now be described in detail.
At a start of a manufacturing event, information regarding a desired structure 12 may be loaded into system 10 (e.g., into controller 22 that is responsible for regulating operations of support 14 and/or head 16). This information may include, among other things, a size (e.g., diameter, wall thickness, length, etc.), a contour (e.g., a trajectory), surface features (e.g., ridge size, location, thickness, length; flange size, location, thickness, length; etc.), connection geometry (e.g., locations and sizes of couplings, tees, splices, etc.), desired surface textures, texture locations, etc. It should be noted that this information may alternatively or additionally be loaded into system 10 at different times and/or continuously during the manufacturing event, if desired. Based on the component information, one or more different reinforcements, matrix materials, and/or film reels may be selectively installed and/or continuously supplied into system 10.
The component information may then be used to control operation of system 10. For example, the reinforcements may be pulled and/or pushed along with the matrix material and/or film from head 16. Support 14 may also selectively move head 16 and/or anchor point 20 in a desired manner, such that an axis of the resulting structure 12 follows a desired three-dimensional trajectory. Once structure 12 has grown to a desired length, structure 12 may be severed from system 10.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed systems. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.