ADDITIVE MANUFACTURING SYSTEM HAVING IN-SITU FIBER SPLICING Related Applications

[0001] This application is based on and claims the benefit of priority from United States Provisional Application No. 62/383,801 that was filed on September 6, 2016, the contents of all of which are expressly incorporated herein by reference

Technical Field

[0002] The present disclosure relates generally to a manufacturing system and, more particularly, to an additive manufacturing system having in-situ fiber splicing.

Background

[0003] Extrusion manufacturing is a known process for producing continuous structures. During extrusion manufacturing, a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) is pushed through a die having a desired cross-sectional shape and size. The material, upon exiting the die, cures and hardens into a final form. In some applications, UV light and/or ultrasonic vibrations are used to speed the cure of the liquid matrix as it exits the die. The structures produced by the extrusion manufacturing process can have any continuous length, with a straight or curved profile, a consistent cross-sectional shape, and excellent surface finish. Although extrusion manufacturing can be an efficient way to continuously manufacture structures, the resulting structures may lack the strength required for some applications.

[0004] Pultrusion manufacturing is a known process for producing high-strength structures. During pultrusion manufacturing, individual fiber strands, braids of strands, and/or woven fabrics are coated with or otherwise impregnated with a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) and pulled through a stationary die where the liquid matrix cures and hardens into a final form. As with extrusion manufacturing, UV light and/or ultrasonic vibrations are used in some pultrusion applications to speed the cure of the liquid matrix as it exits the die. The structures produced by the pultrusion manufacturing process have many of the same attributes of extruded structures, as well as increased strength due to the integrated fibers. Although pultrusion manufacturing can be an efficient way to continuously manufacture high-strength structures, the resulting structures may lack the form (shape, size, and/or precision) required for some applications. In addition, conventional pultrusion manufacturing may lack precise control over curing and the ability to dynamically change fibers during manufacture.

[0005] The disclosed system is directed to addressing one or more of the problems set forth above and/or other problems of the prior art.

Summary

[0006] In one aspect, the present disclosure is directed to an additive manufacturing system. The additive manufacturing system may include a head configured to discharge a composite material, including a matrix and a first reinforcement. The system may also include a splicing mechanism configured to selectively swap out the first reinforcement with a second reinforcement.

[0007] In another aspect, the present disclosure is directed to another additive manufacturing system. This additive manufacturing system may include a head configured to discharge a composite material including a matrix and a first reinforcement, and a support configured to move the head in multiple dimensions during discharging by the head. The additive manufacturing system may also include a splicing mechanism configured to at least one of dynamically swap out or supplement the first reinforcement with a second reinforcement during discharging by the head. The additive manufacturing system may further include a controller configured to receive information regarding a structure to be manufactured with the composite material, and to coordinate operation of the splicing mechanism with movement of the head based on the information.

[0008] In yet another aspect, the present disclosure is directed to a head for an additive manufacturing system. The head may include a housing, and a nozzle located at a discharge end of the housing. The head may also include a cutter disposed inside the housing, an adhesive dispenser disposed inside the housing and adjacent the cutter, and an internal cure enhancer disposed inside the housing and downstream of the adhesive dispenser. Brief Description of the Drawings

[0009] Figs. 1 and 2 are diagrammatic illustrations of exemplary disclosed manufacturing systems; and

[0010] Fig. 3 is a diagrammatic illustration of an exemplary disclosed head that may be used in conjunction with the manufacturing systems of Figs. 1 and 2.

Detailed Description

[0011] Figs. 1 and 2 illustrate different exemplary systems 10 and 12, which may be used to continuously manufacture composite structures 14 having any desired cross-sectional shape (e.g., circular, polygonal, etc.). Each of systems 10, 12 may include at least a support 16 and a head 18. Head 18 may be coupled to and moved by support 16. In the disclosed embodiment of Fig. 1, support 16 is a robotic arm capable of moving head 18 in multiple directions during fabrication of structure 14, such that a resulting longitudinal axis of structure 14 is three-dimensional. In the embodiment of Fig. 2, support 16 is an overhead gantry also capable of moving head 18 in multiple directions during fabrication of structure 14. Although supports 16 of both embodiments are shown as being capable of 6-axis movements, it is contemplated that any other type of support 16 capable of moving head 18 in the same or in a different manner could also be utilized, if desired. In some embodiments, a drive may mechanically couple head 18 to support 16, and may include components that cooperate to move and/or supply power or materials to head 18.

[0012] Head 18 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, epoxy resins, polyester resins, cationic epoxies, acrylated epoxies, urethanes, esters, thermoplastics, photopolymers, polyepoxides, and more. In one embodiment, the matrix material inside head 18 may be pressurized, for example by an external device (e.g., an extruder or another type of pump - not shown) that is fluidly connected to head 18 via a corresponding conduit (not shown). In another embodiment, however, the pressure may be generated completely inside of head 18 by a similar type of device. In yet other embodiments, the matrix material may be gravity-fed through head 18. In some instances, the matrix material inside head 18 may need to be kept cool and/or dark to inhibit premature curing; while in other instances, the matrix material may need to be kept warm for the same reason. In either situation, head 18 may be specially configured (e.g., insulated, chilled, and/or warmed) to provide for these needs.

[0013] The matrix material may be used to coat, encase, or otherwise surround any number of continuous reinforcements (e.g., separate fibers, tows, rovings, and/or sheets of material) and, together with the reinforcements, make up at least a portion (e.g., a wall) of composite structure 14. The reinforcements may be stored within (e.g., on separate internal spools - not shown) or otherwise passed through head 18 (e.g., fed from external spools). When multiple reinforcements are simultaneously used, the reinforcements may be of the same type and have the same diameter and cross-sectional shape (e.g., circular, square, flat, etc.), or of a different type with different diameters 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 encased in the matrix material discharging from head 18.

[0014] The reinforcements may be exposed to (e.g., coated with) the matrix material while the reinforcements are inside head 18, while the reinforcements are being passed to head 18, and/or while the reinforcements are discharging from head 18, as desired. The matrix material, dry reinforcements, and/or reinforcements that are already exposed to the matrix material (e.g., wetted reinforcements) may be transported into head 18 in any manner apparent to one skilled in the art.

[0015] One or more cure enhancers (e.g., a UV light, an ultrasonic emitter, a laser, a heater, a catalyst dispenser, etc.) 20 may be mounted proximate (e.g., within or on) head 18 and configured to enhance a cure rate and/or quality of the matrix material as it is discharged from head 18. Cure enhancer 20 may be controlled to selectively expose surfaces of structure 14 to energy (e.g., UV light, electromagnetic radiation, vibrations, heat, a chemical catalyst, etc.) during the formation of structure 14. 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 18. In the depicted embodiments, cure enhancer 20 includes multiple LEDs (e.g., 6 different LEDs) that are equally distributed about a center axis of head 18. However, it is contemplated that any number of LEDs or other energy sources could alternatively be utilized for the disclosed purposes and/or arranged in another manner (e.g., unequally distributed, arranged in a row, etc.). The amount of energy produced by cure enhancer 20 may be sufficient to cure the matrix material before structure 14 axially grows more than a predetermined length away from head 18. In one embodiment, structure 14 is completely cured before the axial growth length becomes equal to an external diameter of the matrix-coated reinforcement.

[0016] The matrix material and reinforcement may be discharged from head 18 via at least two different modes of operation. In a first mode of operation, the matrix material and reinforcement are extruded (e.g., pushed under pressure and/or mechanical force) from head 18, as head 18 is moved by support 16 to create the 3-dimensional shape of structure 14. In a second mode of operation, at least the reinforcement is pulled from head 18, 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 18 along with the reinforcement, and/or the matrix material may be discharged from head 18 under pressure along with the pulled reinforcement. In the second mode of operation, where the matrix material is being pulled from head 18, the resulting tension in the reinforcement may increase a strength of structure 14, while also allowing for a greater length of unsupported material to have a straighter trajectory (i.e., the tension may act against the force of gravity to provide free-standing support for structure 14).

[0017] The reinforcement may be pulled from head 18 as a result of head 18 moving away from an anchor point 22. In particular, at the start of structure-formation, a length of matrix- impregnated reinforcement may be pulled and/or pushed from head 18, deposited onto an anchor point 22, and cured, such that the discharged material adheres to anchor point 22. Thereafter, head 18 may be moved away from anchor point 22, and the relative movement may cause the reinforcement to be pulled from head 18. It should be noted that the movement of reinforcement through head 18 could be assisted (e.g., via internal head mechanisms), if desired. However, the discharge rate of reinforcement from head 18 may primarily be the result of relative movement between head 18 and anchor point 22, such that tension is created within the reinforcement. It is contemplated that anchor point 22 could be moved away from head 18 instead of or in addition to head 18 being moved away from anchor point 22.

[0018] An exemplary control arrangement is shown in Fig. 3 that may be used to regulate operation of system 10 and/or 12 (referring to Fig. 1). As can be seen in this figure, a controller 24 is provided and shown as being communicatively coupled with support 16, head 18, and any number and type of cure enhancers 20. Controller 24 may embody a single processor or multiple processors that include a means for controlling an operation of system(s) 10 and/or 12. Controller 24 may include one or more general- or special-purpose processors or microprocessors. Controller 24 may further include or be associated with a memory for storing data such as, for example, design limits, performance characteristics, operational instructions, matrix characteristics, reinforcement characteristics, characteristics of structure 14, and corresponding parameters of each component of system(s) 10 and/or 12. Various other known circuits may be associated with controller 24, including power supply circuitry, signal- conditioning circuitry, solenoid/motor driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, controller 24 may be capable of communicating with other components of system(s) 10 and/or 12 via wired and/or wireless transmission.

[0019] One or more maps may be stored in the memory of controller 24 and used during fabrication of structure 14. 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 are used by controller 24 to determine desired characteristics of cure enhancers 20, the associated matrix, and/or the associated reinforcements at different locations within structure 14. The characteristics may include, among others, a type, quantity, and/or configuration of reinforcement to be discharged at a particular location within structure 14. Controller 24 may then correlate operation of support 16 (e.g., the location and/or orientation of head 18) and/or the discharge of material from head 18 (a type of material, desired performance of the material, cross-linking requirements of the material, a discharge rate, etc.) with the operation of cure enhancers 20 such that structure 14 is produced in a desired manner.

[0020] As can be seen in Fig. 3, a splicing mechanism 26 may be associated with head 18 and regulated by controller 24. Splicing mechanism 26 may be located inside of or upstream of head 18 (e.g., within a housing of head 18 and upstream of a discharge nozzle), and include components that cooperate to dynamically change the number and/or types of reinforcements discharging from head 18. Specifically, when creating structure 14, certain portions may call for a first type, amount, and/or configuration of reinforcement (e.g., 6k tow of carbon fiber), while another portion may call for a second type (e.g., 24k braid of fiberglass) of and/or additional reinforcement. The disclosed arrangement of Fig. 3 may allow for the first type of reinforcement to be dynamically swapped (and/or supplemented) with the second type of reinforcement without halting of structure manufacturing. The components of slicing mechanism 26 may include, among other things, a cutter 28, a driver 30, an adhesive dispenser 32, and an internal cure enhancer 34.

[0021] Cutter 28 may embody, for example, one or more blades, and an actuator configured to push the blade(s) through one or more of the reinforcements at a time when the dynamic reinforcement change is commanded by controller 24. In the disclosed embodiment, cutter 28 is shown in association with only one reinforcement. It should be noted, however, that another cutter 28 could additionally be associated with each of any different reinforcements available within head 18.

[0022] Driver 30 may embody, for example, one or more rollers that are powered (e.g., via a motor) to drive the replacing reinforcement toward cure enhancer 34. In most embodiments, the reinforcement being replaced may be pulled from head 18 during manufacture of structure 14 and, thus, not require the use of a driver. However, during reinforcement replacement, the replacing reinforcement, since it may not yet be pulled from head 18, may require the use of driver 30 to drive the replacing reinforcement through head 18. It is contemplated that a dedicated driver 30 could be associated with each type of reinforcement, as desired. Driver 30 may be configured to push the replacing reinforcement to abut or overlap (e.g., directly overlap, overlap at an angle and/or scarf interface, etc.) the reinforcement being replaced before, during, and/or after the reinforcement being replaced has been severed by cutter 28.

[0023] At some point in time, before the severed reinforcement and/or the replacing reinforcement reaches internal cure enhancer 34, an adhesive may be applied to one or both of the reinforcements by adhesive dispenser 32. The adhesive may be of the same composition as the matrix material that later coats the reinforcement being discharged, or a different adhesive. For example, the adhesive may be a more flexible adhesive that allows the spliced joint to bend as it exits head 18. Internal cure enhancer 34 may be selectively activated by controller 24 to then cure the adhesive, thereby bonding the new upstream and severed downstream reinforcements to each other at the abutment or overlap. Thereafter, the replacing reinforcement may be pulled from head 18 (e.g., by pulling on the existing reinforcement already protruding from head 18) and used to manufacture structure 14. Internal cure enhancer 34 may be of the same type as external cure enhancer 34, or different, as desired. [0024] It is contemplated that, during splicing in some applications, the existing and new reinforcements may need to be pressed together and/or shaped during curing to enhance the bond between the reinforcements and to make sure that the spliced joint can fit through the nozzle tip of head 18. This may be accomplished, for example, by a die, a funnel, an actuator, a squeegee, or another similar device 36. It is contemplated that, as the nozzle tip of head 18 is swapped out for another nozzle tip, mechanism 36 may also need to be swapped out to accommodate a different internal shape and/or diameter of the orifice in the nozzle tip.

[0025] It should be noted that the location along structure 14 at which splicing occurs may be important, for example for reasons of structural integrity (e.g., fatigue) and/or cosmetic appearance. Accordingly, the splicing location may be determined and/or correlated by controller 24 with the location of particular features (e.g., corners, recesses, contour changes, etc.) of structure 14.

Industrial Applicability

[0026] 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, diameters, shapes, configurations, and consist. In addition, the fibers used to make the composite structures may be dynamically changed (swapped out, combined, supplemented, etc.) during manufacture of the structures. Operation of systems 10 and 12 will now be described in detail.

[0027] At a start of a manufacturing event, information regarding a desired structure 14 may be loaded into systems 10 and 12 (e.g., into controller 24 that is responsible for regulating operations of support 16 and/or head 18). 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 weave patterns, weave transition locations, location-specific matrix stipulations, location-specific fiber stipulations, etc. It should be noted that this information may alternatively or additionally be loaded into systems 10 and 12 at different times and/or continuously during the manufacturing event, if desired. Based on the component information, one or more different reinforcements and/or matrix materials may be selectively installed and/or continuously supplied into systems 10 and 12. In some embodiments, the reinforcements may also need to be connected to a pulling machine (not shown) and/or to a mounting fixture (e.g., to anchor point 22). Installation of the matrix material may include filling head 18 and/or coupling of an extruder (not shown) to head 18.

[0028] The component information may then be used to control operation of systems 10 and 12. For example, the reinforcements may be pulled and/or pushed from head 18 (along with the matrix material), while support 16 selectively moves head 18 in a desired manner, such that an axis of the resulting structure 14 follows a desired trajectory (e.g., a free-space, unsupported, 3-D trajectory). Once structure 14 has grown to a desired length, structure 14 may be disconnected (e.g., severed) from head 18 in any desired manner.

[0029] During the growth of structure 14, the information received at the start of the manufacturing process may dictate a change in reinforcements. For example, the information may require the use of a thicker reinforcement (e.g., a 24k tow instead of a 6k tow), the use of another type of reinforcement (e.g., carbon instead of glass), the use of combined fibers (e.g., carbon + optical tubes), the use of another form of reinforcement (e.g., ribbon or sheets instead of fibers), etc. at a particular location within structure 14. Responsive to the manufacturing progress of head 18, relative to the spatial requirements of structure 14, controller 24 may selectively activate splicing mechanism 26 to provide for the change in reinforcements.

[0030] For example, structure 14 may need greater strength at a critical area (e.g., at a neck or mounting area), as compared to a non-critical area (e.g., at a non-structural fill area). As head 14 reaches the critical area, controller 24 may selectively activate cutter 28 to sever the reinforcement currently being discharged from head 18. At about this same time, controller 24 may selectively activate driver 30 to advance the new reinforcement to either abut the severed end of the existing reinforcement or to overlap the severed end by a predetermined distance. Adhesive dispenser 32 may be selectively activated by controller 24 to dispense a desired amount of adhesive onto one or both of the existing reinforcement (e.g., at the severed end) and the new reinforcement (e.g., at a leading end). The adhesive dispensing may be performed before or after severing of the existing reinforcement and advancing of the new reinforcement. The abutted or overlapped reinforcements may then be at least partially cured as they pass near internal cure enhancer 34, thereby joining the reinforcements to each other. Thereafter, continued movement of head 18 away from anchor point 22 (and/or away from previously dispensed and cured portions of structure 14) may cause the replacing reinforcement to be pulled from head 18. A similar process may be used to switch to another reinforcement and/or to return to the original reinforcement, as desired.

[0031] It should be noted that the new reinforcement could be dispensed from head 18 without first severing the existing reinforcement, if desired. For example, when the structure information stipulates a change in reinforcement mix and/or quality, the new reinforcement may be advanced to overlap the existing reinforcement, coated with adhesive, and cured, without ever severing the existing reinforcement. This may allow for a greater amount and/or a different mix of reinforcements to be discharged from head 18. At any point thereafter, the new and/or the existing reinforcement may be selectively severed by cutter 28 to again change the amount and/or mix of reinforcements discharging from head 18.

[0032] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed systems and head. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed systems and heads. 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.