Patent Description:
Large composite parts, such as those spanning more than several meters (i.e. tens of feet), occupy substantial space within a factory floor. Preforms for these parts are laid up on a layup mandrel in a stationary work cell. The work cell includes an Automated Fiber Placement (AFP) machine, comprising a massive end effector for a large robot arm. The end effector proceeds traverse the cell and to add fiber-reinforced material on a tow-by-tow basis. Thus, the lone AFP machine traverses the entire layup mandrel singularly according to an optimized layup pattern.

<CIT> states in the abstract that composite sections for aircraft fuselages and methods and systems for manufacturing such sections are disclosed. A composite section configured in accordance with one embodiment of the disclosure includes a skin and at least first and second stiffeners. The skin can include a plurality of unidirectional fibers forming a continuous surface extending <NUM> degrees about an axis. The first stiffener can include a first flange portion bonded to an interior surface of the skin and a first raised portion projecting inwardly and away from the interior surface of the skin. The second stiffener can include a second flange portion bonded to the interior surface of the skin and a second raised portion projecting inwardly and away from the interior surface of the skin. A method for manufacturing a section of a fuselage in accordance with one embodiment includes positioning a plurality of uncured stiffeners on a mandrel assembly. The method can further include applying a plurality of fiber tows around the plurality of uncured stiffeners on the mandrel assembly.

<CIT> states in the abstract that a method for manufacturing a fibre composite component comprising a skin portion and a backing structure is disclosed. Initially, a single-piece foam body or the parts of a multi-part foam body, which comprises at least one recess which is open towards a first side of the foam body, are prepared and positioned. Prior to, during or after the positioning of the foam body or the parts thereof, a rigidifying element for the backing structure or a preform or first semi-finished product for forming the rigidifying element is arranged in the recess at least in portions. A skin portion or a second semi-finished product for forming the skin portion is provided, and brought into contact, in regions, with the foam body on the first side thereof and with the rigidifying element or preform or first semi-finished product, causing the skin portion or second semi-finished product to be placed against the foam body at least in portions and the rigidifying element or preform or first semi-finished product to be positioned relative to the skin portion or second semi-finished product. The skin portion or second semi-finished product and the rigidifying element or preform or first semi-finished product in contact therewith are processed further in such a way that a fibre composite component is obtained in which the skin portion and the rigidifying element are interconnected. The disclosure additionally relates to a fibre composite component and to a structural component for an aircraft or spacecraft.

<CIT> states in the abstract a method for fabricating a one-piece composite fuselage section that minimizes out-of-plane fiber distortion. This is accomplished by fabricating a mandrel having a coefficient of thermal expansion in the hoopwise direction that is sufficiently greater than that of the laid-up composite ply assembly. As a result of this differential in the coefficients of thermal expansion in the hoopwise direction, the laid-up composite ply assembly is stretched circumferentially as the mandrel expands radially during cure, thereby eliminating or reducing out-of-plane fiber distortion. At the same time, the mandrel and part being fabricated should have substantially the same coefficient of thermal expansion in the lengthwise direction. As the outer surface of the mandrel increases in circumference, the circumferentially oriented reinforcing fibers of the inner plies are stretched, while the circumferentially oriented reinforcing fibers of the outer plies do not reduce in circumference and thus do not form waves or wrinkles.

<CIT> states in the abstract a vacuum bag that is placed around the inner forming surface (IML) of an inner mandrel with radially retractable sectors having parallel longitudinal slots. Stringers of composite material are positioned in the slots. A respective elongated inner support is placed in each stringer, covered by an impermeable tubular bag. A skin of composite material is laminated around the stringers, the coated supports and the inner forming surface (IML). An outer curing tool closes around the skin defining an outer forming surface (OML) for the fuselage barrel, leaving an annular gap (G) of predetermined radial width between the outer surface of the skin and the outer forming surface (OML). Vacuum is applied to the volume enclosed between the vacuum bag and the outer tool, so as to enlarge the diameter of the uncured barrel, causing the barrel to be released from the inner mandrel and bringing the outer surface of the skin into contact with the inner surface (OML) of the outer tool.

Present techniques for fabricating large composite parts therefore require a substantial amount of time in order for the layup mandrel to be indexed and then for a preform to be laid-up.

Embodiments described herein provide assembly-line systems and techniques for fabricating preforms that will be hardened into sections of fuselage for an airframe of an aircraft. The systems include stations that are arranged in a process direction traveled by a layup mandrel. The layup mandrel continues along the process direction to receive additional fiber reinforced components as it travels, until a completed preform for a section of fuselage is fabricated at the layup mandrel. By subdividing the operations of layup and compaction across the stations of the assembly line, overall fabrication speed is rapidly increased without the need for specialized machinery. Furthermore, this arrangement ensures that transportation of the laminate includes value-added time during which layup, compaction, and other operations can occur.

One embodiment is a method for fabricating a preform for a fuselage section of an aircraft. The method includes advancing a series of arcuate mandrel sections in a process direction through an assembly line; placing stringer preforms onto the arcuate mandrel sections via stringer placement stations; uniting the series of arcuate mandrel sections into a combined mandrel; and laying up fiber reinforced material onto the combined mandrel and the stringer preforms.

In another aspect, a system for fabricating a preform for a fuselage section of an aircraft is provided. The system includes a series of arcuate mandrel sections that are advanced in a process direction through an assembly line, at least one stringer placement station operable to place stringer preforms onto the arcuate mandrel sections, at least one mandrel assembly station operable to unite the series of arcuate mandrel sections into a combined mandrel, and at least one layup station operable to layup fiber reinforced material onto the combined mandrel and the stringer preforms.

Other illustrative embodiments (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.

The figures and the following description provide specific illustrative embodiments of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within the scope of the disclosure. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the disclosure is not limited to the specific embodiments or examples described below, but by the claims.

The fuselage sections described herein comprise one or more composite parts. Composite parts, such as Carbon Fiber Reinforced Polymer (CFRP) parts, are initially laid-up in multiple layers that together are referred to as a preform. Individual fibers within each layer of the preform are aligned parallel with each other, but different layers exhibit different fiber orientations in order to increase the strength of the resulting composite part along different dimensions. The preform includes a viscous resin that solidifies in order to harden the preform into a composite part (e.g., for use in an aircraft). Carbon fiber that has been impregnated with an uncured thermoset resin or a thermoplastic resin is referred to as "prepreg. " Other types of carbon fiber include "dry fiber" which has not been impregnated with thermoset resin but may include a tackifier or binder. Dry fiber is infused with resin prior to hardening. For thermoset resins, the hardening is a one-way process referred to as curing, while for thermoplastic resins, the resin reaches a viscous form if it is re-heated, after which it can be consolidated to a desired shape and solidified. As used herein, the umbrella term for the process of transitioning a preform to a final hardened shape (i.e., transitioning a preform into a composite part) is referred to as "hardening," and this term encompasses both the curing of thermoset preforms and the forming/solidifying of thermoplastic preforms into a final desired shape.

<FIG> illustrates an assembly line <NUM> that fabricates a preform <NUM> for a section of fuselage in an illustrative embodiment. In this embodiment, the assembly line <NUM> performs a variety of fabrication processes that together result in a preform <NUM> for hardening into a composite part. Movement proceeds along process directions <NUM>-<NUM> through <NUM>-<NUM> during these operations. Assembly line <NUM> includes stringer fabrication lines <NUM>, which create stringer preforms <NUM>. The stringer preforms <NUM> are placed onto arcuate mandrel sections <NUM>, which are later assembled together to form a combined mandrel <NUM>. In one embodiment, placing the stringer preforms <NUM> is performed during pauses between pulses of the arcuate mandrel sections <NUM>. In another embodiment, placing the stringer preforms <NUM> is performed during continuous processing of the arcuate mandrel sections <NUM>.

Arcuate mandrel sections <NUM> are structurally united into a combined mandrel <NUM>. While in the illustrated embodiments the combined mandrel <NUM> is illustrated as being for a half-barrel section of fuselage, there are embodiments for a full-barrel section of fuselage as well as embodiments for something other than a half-barrel or full-barrel fuselage section.

The combined mandrel <NUM> has one or more layers of fiber reinforced material <NUM> laid-up onto it. These layers of fiber reinforced material <NUM> unite stringer preforms <NUM> at the combined mandrel <NUM> into an integral whole, resulting in a preform <NUM> for an arcuate section of fuselage. A caul plate <NUM> is sealed to the combined mandrel <NUM> around the preform <NUM>, and the preform <NUM> is hardened within an autoclave <NUM> (e.g., a pass-through autoclave) into a composite part <NUM> (e.g., during an autoclave curing cycle). Thus, in this embodiment the caul plate <NUM> operates as a vacuum bag as well as a caul plate. The composite part <NUM> is demolded, and the combined mandrel <NUM> is disassembled and cleaned in order to enable re-use of arcuate mandrel sections <NUM> on the assembly line <NUM>. That is, after cleaning, the arcuate mandrel sections <NUM> return to position A indicated on the left side of the page, in order to receive another iteration of work.

The various stations illustrated in <FIG> are each designed to perform their work within a specific period of time. For example, the amounts of work assigned to the stations may be tailored so that each station can perform its work during a uniform pause (e.g., a pause shared by/synchronized across multiple stations at the assembly line <NUM>) between pulses of a stringer preform <NUM>, an arcuate mandrel section <NUM>, and/or a combined mandrel <NUM>. In one embodiment, an integer number of the pauses (which are equal, and performed synchronously across stringer preforms <NUM>, arcuate mandrel sections <NUM>, and/or combined mandrels <NUM>) is equal to a hardening time for the stringer preform <NUM>. In further embodiments, pauses are synchronized for stations working on the same components, but are not shared across different types of components. For example, stations that perform stringer fabrication synchronize to pauses, stations that perform layup onto an arcuate mandrel section <NUM> synchronize to different pauses, and stations that perform work on combined mandrels <NUM> synchronize to other pauses. In some embodiments, the larger pauses are integer multiples of the smaller pauses. In still further embodiments, some portions of the assembly line <NUM> are continuously operated, while others are pulsed.

All of the operations discussed above are performed in conformance with desired takt times for the preforms <NUM>. Enforcing a uniform work time across multiple stations enables operations between the stations to be coordinated and synchronized according to a common schedule.

In one embodiment, advancing comprises enforcing a uniform work time across multiple stations within which the laying up, uniting, and splicing is performed enabling operations between the stations to be coordinated and synchronized according to a common schedule.

In one embodiment, each of the stations performs an amount of work based on the time span of a heating cycle of autoclave <NUM>. Thus, in one embodiment the amount of time spent by a stringer preform <NUM>, arcuate mandrel section <NUM>, or combined mandrel <NUM> during a pause at each station is equal to the expected hardening time for the preform <NUM> at the autoclave <NUM> (or is equal to a period of time that the hardening time is evenly divisible by). This enables various components to be advanced synchronously, either continuously or in a pulsed fashion, across a number of stations in lock step with hardening processes performed at the autoclave <NUM>. Subdividing the fabrication of large structures into fabrication of smaller structures for processing and assembly allows for implementation of parallel processing and assembly of the smaller structures, increasing overall throughput and fabrication speed for the large structures.

In still further embodiments, components that are utilized as inputs to the stations of assembly line <NUM> are fabricated in a Just-In-Time (JIT) manner by feeder lines, further described below, that supply the components directly to the stations. Providing components JIT to the stations reduces the amount of space needed at the factory for storage, as well as the amount of space needed for lanes that transport materials from storage to the stations. In some embodiments, the components provided by a single line (e.g., stringer preforms <NUM>) vary slightly from each other, and the specific type of component needed at a point in time is provided in a JIT manner.

With this broad understanding of the assembly line <NUM> in place, further details of individual components of the assembly line <NUM> are provided below. In this embodiment, stringer fabrication lines <NUM> each include lamination stations <NUM>, which lay up and trim flat charges <NUM> of fiber reinforced material (e.g., unhardened CFRP). These flat charges <NUM> may additionally receive Fluorinated Ethylene Propylene (e.g., FEP) layers, isolation plies (e.g., fiberglass plies that electrically insulate carbon fiber from aluminum components), etc. The flat charges <NUM> advance in process direction <NUM>-<NUM> to forming stations <NUM>.

The flat charges <NUM> are shaped into stringer preforms <NUM> by forming stations <NUM> onto mandrels <NUM>. After forming, the stringer preforms <NUM> are moved in process direction <NUM>-<NUM> and placed onto trays <NUM> which proceed along track <NUM> (e.g., a powered conveyor or other component). The track <NUM> can be linear or can be arranged in a race track (e.g., a loop) layout wherein one or more stringer preforms <NUM> enter the track <NUM> and exit when layup and forming is complete (e.g., after layup continues during one or more traversals of the loop by a stringer preform <NUM>). In one embodiment, multiple lamination stations <NUM> are followed by multiple forming stations <NUM>, respectively aligned along the track <NUM>. Within the track <NUM> mandrels <NUM> cycle through the same lamination station <NUM> followed by the same forming station <NUM> multiple times before exiting the track <NUM>. Further details of this arrangement are depicted with respect to <FIG> below. Depending on design, the trays <NUM> store either one or a plurality of stringer preforms <NUM>.

Stringer placement stations <NUM>, such as Pick and Place (PNP) stations <NUM>, place the stringer preforms <NUM> from the trays <NUM> and onto arcuate mandrel sections <NUM> in process direction <NUM>-<NUM>. In one embodiment, the PNP stations <NUM> (comprising PNP machines <NUM>) pick and place a single stringer preform <NUM> at a time, while in other embodiments, the PNP stations <NUM> each pick and place a batch of stringer preforms <NUM> at once onto an arcuate mandrel section <NUM> advancing in a process direction <NUM>-<NUM>. Additional ones of the stringer preforms <NUM> are held in storage <NUM> for later use by the PNP stations <NUM> or other stations. In still further embodiments, the PNP stations <NUM> apply frame fillers (e.g., pad-ups for accommodating frames) while applying the stringer preforms <NUM>, and the frame fillers are kitted with the stringer preforms <NUM> onto the trays <NUM> at desired locations. In still further embodiments, the stringer preforms <NUM> and the frame fillers are picked up in groups that are applied at once to the arcuate mandrel section <NUM>.

The arcuate mandrel sections <NUM> are advanced in a process direction (P) indicated by the arrows of <FIG>. In one embodiment, the arcuate mandrel sections <NUM> are moved continuously in the process direction, while in further embodiments, the arcuate mandrel sections <NUM> are pulsed in the process direction, which can depending on the direction of the next station. Movement of the arcuate mandrel sections <NUM> by less than their length is referred to as a "micro pulse," while movement of the arcuate mandrel sections <NUM> by equal to or greater than their length is referred to as a "full pulse. " In pulsed embodiments, the stations are capable of performing work on the arcuate mandrel sections <NUM> during pauses between pulses, and multiple stations perform work on the same arcuate mandrel section <NUM> during the same pause between pulses. In continuous motion embodiments, the stations can perform operations during motion of the arcuate mandrel sections <NUM>. In further embodiments, two separate versions can be implemented. A first version is a "drive by" version wherein station tooling is fixed and performs work on an arcuate mandrel section <NUM> while the arcuate mandrel section <NUM> advances through or past the station. A second version is a "hitch hiker" version, wherein station tooling is physically connected to the arcuate mandrel section <NUM> and performs work at the arcuate mandrel section <NUM> while both are advancing, until a point is reached where the connection is broken and the station tooling returns to a beginning of the station. Both versions can be implemented to perform work on the same arcuate mandrel section <NUM> at the same time, depending on the type of fabrication process and work being performed. This discussion pertaining to the arcuate mandrel sections <NUM> is also applicable to fabrication processes relating to the stringer preforms <NUM>, the combined mandrel <NUM>, and other components that are moved at assembly line <NUM>.

The arcuate mandrel sections <NUM> are advanced in process direction <NUM>-<NUM> and are assembled together into a combined mandrel <NUM> at mandrel assembly station <NUM>, and the location of joining arcuate mandrel sections <NUM> can comprise a circumferential position of a stringer, depending on design. In embodiments where the location of joining is a circumferential position of a stringer, after assembly/joining is completed, additional ones of the stringer preforms <NUM> are placed at intersections between arcuate mandrel sections <NUM> that form the combined mandrel <NUM>. The combined mandrel <NUM> is advanced in process direction <NUM>-<NUM> and process direction <NUM>-<NUM> to one or more layup stations <NUM>, where a series of end effectors <NUM> layup fiber reinforced material <NUM> for one or more skin plies in order to create a preform <NUM> for a section of fuselage (e.g., a <NUM> meter (twenty-five foot) or <NUM> meter (forty foot) section of fuselage). The fiber reinforced material <NUM> is laid up upon the combined mandrel <NUM> and over stringer preforms <NUM> placed into the combined mandrel <NUM>. The skin plies unite fiber reinforced material from the stringer preforms <NUM>, causing the individual stringer preforms <NUM> to be integrated together by the skin plies, resulting in the preform <NUM>. Each of the end effectors <NUM> and/or layup stations <NUM> lays up a different combination of plies and fiber orientations in order to complete the preform <NUM>. Each layup station <NUM> is operable to layup fiber reinforced material <NUM> at a number of different orientations. Alternatively, multiple layup stations <NUM> are implemented that each layup is at a particular orientation. In one embodiment, the combined mandrel <NUM> is advanced continuously according to a takt time, and laying up fiber reinforced material <NUM> onto the combined mandrel <NUM> and laying up fiber reinforced material for the stringer preforms <NUM> is performed during advancement of the combined mandrel <NUM>. In such an embodiment, multiple layup stations <NUM> may perform work on the combined mandrel <NUM> during the continuous advancement.

The preform <NUM> is advanced in process direction <NUM>-<NUM> to an Interwoven Wire Fabric (IWWF) and surfacer station <NUM>, which lowers an IWWF <NUM>-<NUM> and a surfacer <NUM>-<NUM> (which may also be collectively referred to as "IWWF and surfacer <NUM>"). These components can be placed at the same time, or separately, or can even be placed in combination as part of a placement/compaction step or together with a caul plate <NUM> and/or vacuum bag. In this embodiment, the IWWF <NUM>-<NUM> and surfacer <NUM>-<NUM> are placed onto the preform <NUM> for the fuselage section via a port <NUM>. In the illustrated embodiment, the port <NUM> is disposed in a mezzanine <NUM>, and the caul plate <NUM>/vacuum bag, and the IWWF <NUM>-<NUM> and surfacer <NUM>-<NUM> are moved into place onto the preform <NUM> from a feeder line, by lowering from the elevation of the mezzanine <NUM>. In this embodiment, instead of a feeder line providing feeder products at ground level, feeder lines may provide materials for the IWWF <NUM>-<NUM> and surfacer <NUM>-<NUM> at the height of the mezzanine <NUM>. Input and output are therefore received from feeders into the station that are elevated. The IWWF <NUM>-<NUM> and the surfacer <NUM>-<NUM> are applied to (e.g., made integral with) the preform <NUM>, such that after hardening the IWWF <NUM>-<NUM> and the surfacer <NUM>-<NUM> are an integral component of the resulting composite part <NUM>.

After the preform <NUM> advances further in a process direction <NUM>-<NUM>, a caul loading station <NUM> utilizes a port <NUM> in the mezzanine <NUM>, to lower a caul plate <NUM> into place onto the preform <NUM>. This enables the caul plate <NUM> to enter from a "third side" <NUM> (i.e., neither from the left nor the right of the preform <NUM>). The caul plate <NUM> is sealed to the combined mandrel <NUM> onto which the preform <NUM> has been laid-up, and the caul plate <NUM> applies pressure during hardening that consolidates and ensures conformance with a desired Outer Mold Line (OML) for the composite part <NUM>.

After the caul plate <NUM> is placed, the preform <NUM> is advanced in process direction <NUM>-<NUM> through an entrance <NUM> of the autoclave <NUM> and sealed into the autoclave <NUM>. In one embodiment, the combined mandrel <NUM> itself forms a boundary of the autoclave <NUM> when moved into place, resulting in a "right sized" autoclave. The autoclave <NUM> operates at heat (e.g., a desired hardening temperature, such as above <NUM> (i.e. hundreds of degrees Fahrenheit)) and pressure (e.g., a desired compaction pressure, such as <NUM> kPa (i.e. ninety pounds per square inch)) to harden the preform <NUM> into a composite part <NUM>. The composite part <NUM> is moved from the autoclave <NUM> in process direction <NUM>-<NUM> through a boundary <NUM> out of a clean room environment <NUM> and into a main factory floor <NUM>. In one embodiment, the boundary <NUM> is disposed at the autoclave exit, and therefore the autoclave <NUM> functions as a doorway out of the clean room environment <NUM>. In some embodiments, indexing features <NUM> such as holes are added to a manufacturing excess <NUM> of the composite part <NUM> at a demold station <NUM>.

The combined mandrel <NUM> is then moved to a demold station <NUM> in a post hardening assembly environment (e.g., a non-clean room environment), wherein the composite part <NUM> is removed and sent to another assembly line to receive installation of frames, window surrounds, and other features. The caul plate <NUM> is cleaned and returned to the clean room environment via process direction <NUM>-<NUM>. This can be achieved via a pulsed, micro pulsed or continuous line for cleaning and prepping, for reintroduction to the clean room environment <NUM> at the mezzanine <NUM>. In a similar fashion, the combined mandrel <NUM> is advanced to a disassembly station <NUM> in process direction <NUM>-<NUM>, where it is separated into individual arcuate mandrel sections <NUM> moving in process directions <NUM>-<NUM>. The arcuate mandrel sections <NUM> move (e.g., are pulsed) along a return line <NUM> in process directions <NUM>-<NUM> that returns the arcuate mandrel sections <NUM> from a factory floor <NUM> to a clean room environment <NUM> at the start of the assembly line <NUM> as indicated by process direction <NUM>-<NUM>. Return line <NUM> can be a pulsed, micro pulsed or continuous line for the clean and prep for reintroduction to the clean room. At the return line <NUM>, the arcuate mandrel sections <NUM> are resurfaced and cleaned at one or more cleaning stations <NUM>, which may comprise disassembly stations, cleaning stations, and resurfacing stations, and then returned to the clean room environment <NUM> for re-use in the assembly line <NUM> (as indicated by nodes "A"). In still further embodiments, a mandrel <NUM> for a stringer preform <NUM> is also pulsed, micro pulsed, or moved continuously along a line for the cleaning and preparation of the mandrel <NUM> prior to reintroduction into the clean room environment <NUM>. This line can be all or partially outside of the clean room environment <NUM>.

A controller <NUM> manages the operations of stations at the assembly line <NUM>, and coordinates actions along the assembly line <NUM> to ensure actions are performed synchronously by the stations as desired. In some illustrative examples, the controller <NUM> is operable to enforce uniform work times across the at least one layup station <NUM>, the at least one mandrel assembly station <NUM>, and such that the laying up and uniting is coordinated and synchronized according to a common schedule. However, one or more controllers may be implemented to coordinate actions, and controller <NUM> does not have to be one centralized device. In some embodiments, controller <NUM> maintains and supplies Numerical Control (NC) programs to the stations, and tracks the timing of operations defined in such NC programs to ensure a desired level of synchronization in operations. In one embodiment, controller <NUM> is implemented as custom circuitry, as a hardware processor executing programmed instructions stored in memory, or some combination thereof.

<FIG> depicts a conceptual assembly arrangement <NUM> in an illustrative embodiment. In <FIG>, feeder lines <NUM>-<NUM> through <NUM>-<NUM> and <NUM>-<NUM> feed a variety of other assembly lines according to a takt time (e.g., a desired production time for a product, such as an airplane or wing), and are synchronized to provide components to the other assembly lines just in time for fabrication. Specifically, feeder lines <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> provide layup material such as tows of CFRP or broad goods, respectively, to feeder line <NUM>-<NUM> for fabricating a half-barrel or full-barrel section, feeder line <NUM>-<NUM> for laying up frames, and feeder line <NUM>-<NUM> for laying up surrounds, respectively. In this embodiment, feeder line <NUM>-<NUM> is also fed by a feeder line <NUM>-<NUM> for stringer preforms, which itself is fed via a feeder line <NUM>-<NUM> for layup materials.

Feeder line <NUM>-<NUM> feeds frames to a feeder line <NUM>-<NUM> for frames section (e.g., after hardening), and feeder line <NUM>-<NUM> feeds surrounds to a feeder line <NUM>-<NUM> for surrounds (e.g., door and window surrounds). The various components discussed above are fed to a feeder line <NUM>-<NUM> that performs serial assembly using input from feeder line <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. The feeder line <NUM>-<NUM> also receives fasteners from feeder line <NUM>-<NUM>, sealant from feeder line <NUM>-<NUM>, and miscellaneous material from feeder line <NUM>-<NUM>. Outflow <NUM>-<NUM> removes trimmed off or machined debris, scrap, etc. from the feeder line <NUM>-<NUM>. Any of the feeder lines <NUM>-<NUM> through <NUM>-<NUM> and/or outflows discussed herein may be operated in a micro-pulsed, continuous, or full-pulsed manner according to the same or different takt time.

<FIG> depicts a conceptual assembly arrangement in an illustrative embodiment. This arrangement depicts an alternative embodiment for stringer layup to that depicted in <FIG>. According to <FIG>, mandrels <NUM>-<NUM> enter a track <NUM>-<NUM> (e.g., an oval track, rectangular track with square ends, etc.) along direction <NUM>-<NUM> and receive fiber reinforced material <NUM>-<NUM> from lamination station <NUM>-<NUM>. The fiber reinforced material <NUM>-<NUM> is shaped by a forming station <NUM>-<NUM> that is downstream from the lamination station <NUM>-<NUM> and the forming station <NUM>-<NUM>, and proceeds in directions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. The mandrels <NUM>-<NUM> each proceed for multiple laps of the track <NUM>-<NUM> until a completed stringer preform in the same configuration as stringer preform <NUM>) has been fabricated, at which time the mandrels <NUM>-<NUM> exit the track via direction <NUM>-<NUM> for further processing. In the embodiment depicted in <FIG>, laying up the fiber reinforced material comprises cycling the mandrels <NUM>-<NUM> through a lamination station <NUM>-<NUM> followed by a forming station <NUM>-<NUM> for multiple laps to form a preform for a stringer. In some illustrative examples, lamination station <NUM>-<NUM> may be referred to as a layup station.

Illustrative details of the operation of assembly line <NUM> will be discussed with regard to <FIG>. Assume, for this embodiment, that stringer preforms <NUM> have been fabricated via stringer fabrication lines <NUM> and await placement onto arcuate mandrel sections <NUM>.

<FIG> is a flowchart illustrating a method <NUM> for operating the assembly line of <FIG> in an illustrative embodiment. The steps of method <NUM> are described with reference to assembly line <NUM> of <FIG>, but those skilled in the art will appreciate that method <NUM> may be performed in other systems. The steps of the flowcharts described herein are not all inclusive and may include other steps not shown. The steps described herein may also be performed in an alternative order.

The method <NUM> includes dispensing <NUM> fiber reinforced material for a preform (e.g., for preform <NUM>) onto a first arcuate mandrel section <NUM>. In this embodiment, dispensing <NUM> fiber reinforced material comprises picking and placing the stringer preforms <NUM> onto an arcuate mandrel section <NUM>. However, in further embodiments this further comprises applying ply packs, frame fillers ("postage stamps"), barrier plies, etc., or laying up one or more plies of material directly onto the arcuate mandrel section <NUM>. Thus, the dispensing <NUM> step includes placing whatever materials are needed for placement onto the arcuate mandrel section <NUM> prior to laying up a skin for a fuselage. The arcuate mandrel section <NUM> may then proceed further down the assembly line <NUM>.

The method <NUM> includes dispensing <NUM> fiber reinforced material <NUM> for the preform <NUM> onto a second arcuate mandrel section <NUM>. The dispensing <NUM> step may be performed in a similar manner to the dispensing <NUM> step recited above. However, the arrangement of stringer preforms <NUM> and the type of stringer preforms <NUM> that are placed at the second arcuate mandrel section <NUM> may be different from those placed on the first arcuate mandrel section <NUM>, depending for example, on whether the second arcuate mandrel section <NUM> receives layup for a crown portion or lateral portion of fuselage. In one embodiment, the dispensing <NUM> step comprises picking and placing stringer preforms <NUM> onto a next arcuate mandrel section <NUM> that immediately follows the first arcuate mandrel section <NUM> down the assembly line <NUM>. However, in further embodiments this further comprises applying ply packs, frame fillers ("postage stamps"), barrier plies, etc., or laying up one or more plies of material directly onto the arcuate mandrel section <NUM>. Thus, dispensing <NUM> includes placing whatever materials are needed for placement onto the arcuate mandrel section <NUM> prior to laying up a skin for a fuselage.

Continuing, the first arcuate mandrel section <NUM> and the second arcuate mandrel section <NUM> are structurally united <NUM> to form a combined mandrel <NUM>. The uniting <NUM> step is performed after the first arcuate mandrel section <NUM> and the second arcuate mandrel section <NUM> have received the fiber reinforced material <NUM> as discussed in the preceding paragraphs. In one embodiment, structurally uniting <NUM> the arcuate mandrel sections <NUM> is performed by placing the arcuate mandrel sections <NUM> onto a frame such that the arcuate mandrel sections <NUM> are adjacent to each other. In a further embodiment, structurally uniting <NUM> the arcuate mandrel sections <NUM> comprises bolting or fastening the arcuate mandrel sections <NUM> to each other while the arcuate mandrel sections <NUM> are chordwise adjacent. In one embodiment, each arcuate mandrel section <NUM> comprises a roughly sixty-degree portion of a full-barrel, and three arcuate mandrel sections <NUM> are assembled together to form the combined mandrel <NUM>. Any suitable number of arcuate mandrel sections <NUM>, each comprising any suitable arc segment, may be assembled together in this step to form the combined mandrel <NUM>. Thus, while only three arcuate mandrel sections <NUM> are shown per combined mandrel <NUM> in <FIG>, in further embodiments, different numbers of segments are used. The combined mandrel <NUM> then receives additional stringer preforms <NUM> (e.g., at intersections between constituent arcuate mandrel sections), and is moved to a layup station <NUM>. In a further embodiment, only underlying material is applied when dispensing <NUM>, <NUM>, but in further embodiments underlying material is applied, then a skin is applied prior to joining arcuate mandrel sections <NUM> together. The skins are then spliced together when the arcuate mandrel sections <NUM> are assembled together. Thus, the uniting <NUM> step may include splicing dispensed fiber reinforced material <NUM> for the preform <NUM> on a first arcuate mandrel section <NUM> with fiber reinforced material <NUM> on a second arcuate mandrel section <NUM>.

Finally, fiber reinforced material <NUM> that completes the preform <NUM> is dispensed <NUM>, by making the fiber reinforced material <NUM> dispensed <NUM> onto the first arcuate mandrel section <NUM> integral with fiber reinforced material <NUM> dispensed onto the second arcuate mandrel section <NUM>. In one embodiment, this comprises layup station <NUM> laying up one or more skin plies atop a surface of the combined mandrel <NUM> that defines an Inner Mold Line (IML) for the preform <NUM>. The skin plies form an arc that covers the stringer preforms <NUM>, and therefore after hardening, the skin plies and the stringer preforms <NUM> form part of the same composite part <NUM> for a section of fuselage. In a further embodiment, dispensing <NUM> comprises picking and placing additional preforms, ply packs, or other components onto the combined mandrel <NUM>.

Method <NUM> provides a substantial benefit over prior techniques because it enables large composite parts <NUM> to be laid up on a piecewise basis at a variety of smaller mandrels (e.g., arcuate mandrel sections <NUM>, mandrels <NUM>) via standardized processes. The smaller mandrels are then united and made integral with additional plies to form a completed preform <NUM>. This streamlines layup processes by increasing speed while also reducing layup difficulty. This also facilitates parallel processing, which increases fabrication rates.

<FIG> is a flowchart illustrating a further method <NUM> for operating the assembly line of <FIG> in an illustrative embodiment. Method <NUM> describes fabrication processes in a similar, but distinct manner from method <NUM> of <FIG>.

Initially, a series of arcuate mandrel sections <NUM> are advanced <NUM> (e.g., pulsed) in a process direction through an assembly line <NUM> (i.e., the same assembly line, feeder line <NUM>-<NUM> of <FIG>, etc.). As discussed above, the arcuate mandrel sections <NUM> can be micro-pulsed or full-pulsed along the assembly line <NUM> as desired, depending on design considerations. In one embodiment, the arcuate mandrel sections <NUM> are advanced <NUM> along a powered track (e.g., a conveyor, or a series of stanchions that each are topped with a powered roller), while in further embodiments the arcuate mandrel sections <NUM> are carried by Automated Guided Vehicles (AGVs) or other conveyances. The arcuate mandrel sections <NUM> (or lengthwise portions thereof) are indexed to the stations at the assembly line <NUM> during pauses between the pulses.

In one embodiment, the arcuate mandrel sections <NUM> are pulsed by less than a length of the arcuate mandrel sections <NUM> in a process direction along the assembly line <NUM>. In a further embodiment, the arcuate mandrel sections <NUM> are pulsed by at least a length of the arcuate mandrel sections <NUM> in a process direction along the assembly line <NUM>. In yet another embodiment, the arcuate mandrel sections <NUM> are continuously advanced in a process direction along the assembly line <NUM>.

Stringer preforms <NUM> are supplied <NUM> via stringer fabrication lines <NUM> (e.g., feeder line <NUM>-<NUM> of <FIG>) to the stringer placement stations <NUM> (e.g., PNP stations <NUM>) at the assembly line <NUM> (e.g., feeder line <NUM>-<NUM> of <FIG>). In one embodiment, the stringer preforms <NUM> are supplied <NUM> JIT to the PNP stations <NUM>, and an end of the stringer fabrication lines <NUM> couples with an input for the PNP stations <NUM>. Because the dimension and shape of each stringer preform <NUM> may vary depending on the section of fuselage being fabricated, JIT supply <NUM> of stringer preforms <NUM> that match the shape and size requirements of the PNP stations <NUM> as those requirements change across time is highly beneficial. Thus, coordination of stringer fabrication processes with PNP processes is useful in order to ensure that the correct stringer preform <NUM> is fabricated and supplied <NUM> at the correct time to a PNP station <NUM>. In a further embodiment, stringer preforms <NUM> from the stringer fabrication lines <NUM> are kept in storage <NUM> and then retrieved JIT for use by the PNP stations <NUM>.

The stringer preforms <NUM> are placed <NUM> onto the arcuate mandrel sections <NUM> via the stringer placement stations <NUM> (e.g., the PNP stations <NUM>). In embodiments where the arcuate mandrel sections <NUM> are pulsed, the stringer preforms <NUM> are placed <NUM> during pauses between pulses of the arcuate mandrel sections <NUM>. In one embodiment, the PNP stations <NUM> each place <NUM> entire batches of stringer preforms <NUM> at once onto the arcuate mandrel section <NUM>. Thus, the stringer preforms <NUM> are placed <NUM> in batches that include multiple stringer preforms <NUM>. In further embodiments, the PNP stations <NUM> place <NUM> the stringer preforms <NUM> singularly to the arcuate mandrel section <NUM>. Thus, desired materials and components (e.g., stringer preforms, etc.) are placed <NUM> onto the arcuate mandrel sections <NUM> prior to skin layup.

The arcuate mandrel sections <NUM> are united <NUM> into a combined mandrel <NUM>. In one embodiment, structurally uniting <NUM> the arcuate mandrel sections <NUM> is performed by placing the arcuate mandrel sections <NUM> onto a frame such that the arcuate mandrel sections <NUM> are chordwise adjacent to each other (i.e., joined along adjacent longitudinal edges). In a further embodiment, structurally uniting <NUM> the arcuate mandrel sections comprises bolting or fastening the arcuate mandrel sections <NUM> to each other.

Fiber reinforced material <NUM> is laid-up <NUM> onto the combined mandrel <NUM> and the stringer preforms <NUM> via layup stations <NUM>, resulting in a fuselage section preform <NUM> that includes the stringer preforms <NUM>. Fiber reinforced material <NUM> is laid-up <NUM> onto the combined mandrel <NUM> and the stringer preforms <NUM> to form a skin layup. This step forms the fuselage skin of the section (e.g., composite part <NUM>). This step is performed via one or more layup stations <NUM>. In one embodiment, each of the layup stations <NUM> lays up <NUM> a different combination of plies and fiber orientations. In one embodiment, where the combined mandrel <NUM> is pulsed, the operations are performed during pauses between pulses of the combined mandrel <NUM>. The operations of the layup stations <NUM> result in a fuselage section preform (i.e., preform <NUM>) that includes the stringer preforms <NUM>. In one embodiment, this comprises operating the end effectors <NUM> to dispense tows of fiber reinforced material <NUM>, or to place sheets of fiber reinforced broad goods onto the combined mandrel <NUM>. In some illustrative examples, the at least one layup station <NUM> comprises at least one end effector <NUM>, the at least one end effector <NUM> operable to dispense tows of fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM>. In some illustrative examples, the at least one layup station <NUM> comprises at least one end effector <NUM>, the at least one end effector <NUM> operable to place sheets of fiber reinforced broad goods onto the arcuate mandrel sections <NUM>. In some illustrative examples, laying up <NUM> the fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM> comprises at least one of: operating at least one end effector <NUM> to dispense tows of fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM>; and placing sheets of fiber reinforced broad goods onto the arcuate mandrel sections <NUM>.

A caul plate <NUM> is applied <NUM> to the fuselage section preform <NUM>. This comprises lowering the caul plate <NUM> over the combined mandrel <NUM>, and sealing the caul plate <NUM> (which also operates as a vacuum bag) to the combined mandrel <NUM> just beyond the perimeter of the preform <NUM>. When a vacuum is applied to a space between the caul plate <NUM> and the combined mandrel <NUM>, the caul plate <NUM> is drawn tightly against the preform <NUM>, which enforces a desired OML shape onto the preform <NUM> during hardening.

The fuselage section preform <NUM> is hardened <NUM> into a composite part <NUM>. This is performed by inserting the combined mandrel <NUM> into an autoclave <NUM> (e.g., in a right-sized autoclave that is bounded in-part by the combined mandrel <NUM>) and operating the autoclave <NUM> at a hardening temperature (e.g., a curing temperature for thermoset resins, or a melt temperature for thermoplastics) and pressure while a vacuum is drawn between the caul plate <NUM> and the combined mandrel <NUM> for a desired period of time (e.g., four hours, eight hours, etc.).

The combined mandrel <NUM> exits the autoclave <NUM>, and a resulting composite part thereon receives additional operations such as adding indexing features to a manufacturing excess <NUM> of the composite part <NUM>, and trimming an edge of the composite part <NUM> to form a bearing edge. Thus, the composite part <NUM> is demolded <NUM> from the combined mandrel <NUM> at demold station <NUM>. In one embodiment, demolding <NUM> comprises iteratively and variably flexing the composite part <NUM> by increasing amounts in order to dislodge the composite part <NUM> from the combined mandrel <NUM>. The composite part <NUM> then proceeds to a post-hardening assembly line for further processing and integration into an airframe.

The combined mandrel <NUM> is separated <NUM> into the arcuate mandrel sections <NUM> (e.g., by unbolting or unfastening the arcuate mandrel sections <NUM> from each other or an underlying frame). The arcuate mandrel sections <NUM> are then cleaned/resurfaced and returned to the assembly line <NUM>.

Method <NUM> provides a substantial benefit over prior techniques because, in a similar manner to method <NUM>, it enables large composite parts to receive layup on a piecewise basis at a variety of smaller mandrels, which are then united and made integral with layup to form a completed preform <NUM>. This streamlines layup processes by increasing speed while also reducing layup difficulty.

<FIG> is a flowchart illustrating a further method <NUM> for operating the assembly line of <FIG> in an illustrative embodiment. Method <NUM> includes advancing <NUM> a series of arcuate mandrel sections <NUM> in a process direction through an assembly line (e.g., feeder line <NUM>-<NUM> of <FIG>). The method includes supplying <NUM> stringer preforms <NUM> via stringer fabrication lines <NUM> (e.g., feeder line <NUM>-<NUM> of <FIG>) to stringer placement stations <NUM> at the assembly line <NUM>. The stringer preforms <NUM> are placed <NUM> onto the arcuate mandrel sections <NUM> via stringer placement stations <NUM> at the assembly line (e.g., feeder line <NUM>-<NUM> of <FIG>). Fiber reinforced material <NUM> is laid up <NUM> onto the arcuate mandrel sections <NUM> and the stringer preforms <NUM> via layup stations <NUM> disposed prior to the mandrel assembly station <NUM>. In some illustrative examples, laying up <NUM> the fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM> comprises simultaneously laying up <NUM> the fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM> via a plurality of layup stations <NUM>. In some illustrative examples, laying up <NUM> the fiber reinforced material <NUM> onto the arcuate mandrel sections <NUM> comprises advancing the arcuate mandrel sections <NUM> through a plurality of layup stations <NUM> via one or both of a continuous advancement or a pulsed advancement.

In one embodiment, this comprises operating layup stations <NUM> disposed along the assembly line <NUM>. The arcuate mandrel sections <NUM> are united <NUM> into a combined mandrel <NUM>. Fiber reinforced material <NUM> is spliced <NUM>, that is, laid-up onto the arcuate mandrel sections <NUM>, and may be performed via the layup stations <NUM> discussed above, or additional layup stations <NUM> that may receive layup materials from a feeder line <NUM>-<NUM>. This results in a fuselage section preform <NUM>.

With a discussion provided above of the fabrication process for a preform <NUM> for a section of fuselage, the following <FIG> illustrate specific components and systems for performing one or more steps of these processes. Specifically, <FIG> depicts further details of layup for a flat charge <NUM>, <FIG> depict operations of a forming machine that shapes a flat charge <NUM> into a stringer preform <NUM>, <FIG> depict placement of stringer preform <NUM> onto an arcuate mandrel section <NUM>, <FIG> depicts a fully formed combined mandrel <NUM>, in a half-barrel configuration, <FIG> depicts layup processes onto the combined mandrel <NUM> to fabricate a preform <NUM>, <FIG> depict placement of IWWFs <NUM>-<NUM>, surfacers <NUM>-<NUM>, and caul plates <NUM> onto a preform <NUM>, and <FIG> depict hardening processes at an autoclave <NUM>.

<FIG> illustrates a lamination station <NUM> for stringer preforms <NUM> in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. In this embodiment, the lamination station <NUM> includes multiple heads <NUM> that each dispense tows of material to form a flat charge <NUM>. The heads <NUM> are mounted to a frame <NUM>, and move along the frame <NUM> (which in one embodiment is a gantry) to desired locations for laying up material. The frame <NUM> provides structural strength to the lamination station <NUM> while also enabling movement of the heads <NUM>. A conveyor <NUM> moves flat charges <NUM> into and/or out of the page via belt <NUM>). By iteratively moving a flat charge <NUM> into and out of the page, the conveyor <NUM> enables each of the heads <NUM> to lay up multiple layers of fiber reinforced material <NUM> at any desired combination of fiber orientations (e.g., +/-<NUM>°, <NUM>°, <NUM>°).

<FIG> illustrate operation of a forming station <NUM> for stringer preforms <NUM> in an illustrative embodiment, and correspond with view arrows <NUM> of <FIG>. In this embodiment, the forming station <NUM> drives a forming head <NUM> onto a flat charge <NUM> that rests at a shaped mandrel <NUM>. This shapes a portion of the flat charge <NUM> into a desired shape for a stringer preform <NUM>. While <NUM> plies are shown, this can be achieved by placing and forming two or a few plies, followed by placing and forming additional plies in an iterative manner until the full layup is placed and formed. Another portion of the flat charge <NUM> is then advanced into the page and formed, and the process continues iteratively (e.g., back and forth on a track) until the entire flat charge <NUM> has been shaped into a stringer preform <NUM>. In further embodiments, the stringer preform <NUM> also includes additional layers, shaped components, and/or flat charges <NUM> (e.g., in order to form a hat stringer, Z stringer, C stringer, etc.) that are placed after leaving the forming station <NUM>.

<FIG> illustrate an arcuate mandrel section <NUM> before and after placement of stringer preforms <NUM> in an illustrative embodiment. Specifically, <FIG> corresponds with view arrows 6A of <FIG>, and <FIG> corresponds with view arrows 6B of <FIG>. In <FIG>, the arcuate mandrel section <NUM> includes a body <NUM> that defines an IML surface <NUM> for a fuselage section preform <NUM>, and also includes troughs <NUM> for receiving stringer preforms <NUM>. In further embodiments, additional accommodations in the arcuate mandrel section <NUM> are provided for frame fillers ("postage stamps") or similar structures that are placed before the skin is laid-up. The arcuate mandrel section <NUM> also includes partial troughs <NUM>. The partial troughs <NUM> become full troughs after joining with other partial troughs <NUM> in other arcuate mandrel sections <NUM>. The resulting completed troughs <NUM> of <FIG> will receive stringer preforms <NUM> after the arcuate mandrel sections are assembled into a combined mandrel <NUM>. In <FIG>, stringer preforms <NUM> are placed into the troughs <NUM>. Outer edges of the stringer preforms <NUM> conform with the IML surface <NUM> after placement and compaction of the stringer preforms <NUM> at the arcuate mandrel section <NUM>. The OML side of the stringer preforms <NUM> provide a portion of a layup surface for the skin when the stringers are compacted into the arcuate mandrel section <NUM>.

<FIG> illustrate a combined mandrel <NUM>, assembled from arcuate mandrel sections <NUM>. While the arcuate mandrel sections <NUM>-<NUM> through <NUM>-<NUM> are of the same design in this embodiment, in further embodiments the arcuate mandrel sections for the left side (arcuate mandrel section <NUM>-<NUM>), right side (arcuate mandrel section <NUM>-<NUM>), and crown (arcuate mandrel section <NUM>-<NUM>) are not interchangeable. For example, the arc lengths, or the number of partial troughs <NUM>, or the number of stringer preforms <NUM> at different arcuate mandrel sections <NUM> can be varied as a matter of design that receives stringer preforms <NUM> in an illustrative embodiment. In this embodiment, the arcuate mandrel sections <NUM> have received the stringer preforms <NUM> prior to assembly into the combined mandrel <NUM>. The combined mandrel <NUM> is held together by bolting or otherwise affixing arcuate mandrel sections <NUM> to the elements <NUM> of frame <NUM>. After combined mandrel <NUM> has been assembled, partial troughs <NUM> from different arcuate mandrel sections <NUM> are united together, resulting in full completed troughs <NUM>. Stringer preforms <NUM> are then placed into these full completed troughs <NUM> as shown in <FIG>.

<FIG> depict layup of skin plies of fiber reinforced material <NUM> onto a combined mandrel <NUM> in an illustrative embodiment, and correspond with view arrows <NUM> of <FIG>. In <FIG>, end effectors <NUM> that are movably attached to a frame <NUM> of a layup station <NUM> are disposed over IML surface <NUM>. The end effectors <NUM> are adjustably mounted to frame <NUM> of the layup station <NUM> in order to enable dynamic motion vertically and laterally (as indicated by the various arrows of this FIG. ) and operation within the layup station <NUM>. The end effectors <NUM> dispense tows of fiber reinforced material <NUM> onto the IML surface <NUM>, resulting in one or more skin plies <NUM> shown in <FIG>. The skin plies <NUM> integrate the stringer preforms <NUM> from the different arcuate mandrel sections <NUM> together, and also integrate the stringers or the particular arcuate mandrel section <NUM> together. This results in a single integral preform <NUM> for a section of fuselage.

<FIG> illustrate layup of an Interwoven Wire Fabric (IWWF) layer <NUM>-<NUM> for a preform <NUM>, as well as placement of a caul plate <NUM> onto a preform <NUM> in an illustrative embodiment. The IWWF layer <NUM>-<NUM> facilitates dispersion of electrical energy that may be received by the airplane. <FIG> correspond with view arrows <NUM> of <FIG>, and depict a mezzanine <NUM> onto which one or more stations (i.e., IWWF and surfacer station <NUM> of <FIG>, caul loading station <NUM> of <FIG>) are disposed. In <FIG>, a first combined mandrel <NUM> having a preform <NUM> is disposed beneath an IWWF and surfacer station <NUM>, while a second combined mandrel <NUM> is disposed beneath a caul loading station <NUM>. Cables <NUM>, which are driven by actuated elements at gantries <NUM>, hold an IWWF <NUM>-<NUM> and a surfacer <NUM>-<NUM> and a caul plate <NUM> over the first combined mandrel <NUM> and second combined mandrel <NUM>, respectively. In further embodiments, the operations of the IWWF and surfacer station <NUM> are separated across multiple stations such that the IWWF <NUM>-<NUM> and the surfacer <NUM>-<NUM> are separately applied. In another embodiment as shown in <FIG>, these multiple steps are performed at the same IWWF and surfacer station <NUM>. In still further embodiments, the IWWF <NUM>-<NUM>, surfacer <NUM>-<NUM> and caul plate <NUM> are all placed at once in one station. In <FIG>, the IWWF <NUM>-<NUM> and the surfacer <NUM>-<NUM> are lowered (together or separately with respect to each other) until they are poised over a preform <NUM>, and then placed. For example, in one embodiment, the IWWF <NUM>-<NUM> is lowered and placed onto a combined mandrel <NUM>, and then the surfacer <NUM>-<NUM> is lowered and placed onto the combined mandrel <NUM>. The caul plate <NUM> is lowered via the caul loading station <NUM> until it is poised over a prior-applied IWWF <NUM>-<NUM> and surfacer <NUM>-<NUM>, and then is placed. The caul plate <NUM>, the IWWF <NUM>-<NUM>, and the surfacer <NUM>-<NUM> are installed at respective combined mandrels <NUM> that are directly beneath them in <FIG>, and the combined mandrels <NUM> each advance to the next station towards an autoclave, and a new combined mandrel <NUM> is moved into position below the IWWF and surfacer station <NUM>.

Mezzanine <NUM>, port <NUM>, and port <NUM> enable IWWF and surfacer station <NUM>, as well as the caul loading station <NUM>, to access the combined mandrels <NUM>, while also enabling materials such as caul plates <NUM> to be repeatedly looped back via the mezzanine <NUM> for reconditioning for re-use inside a clean room environment <NUM> after exiting the clean room environment <NUM>. Mezzanine <NUM> therefore helps to move a caul plate <NUM> (that also performs vacuum bagging functions) in the area around the autoclaves <NUM> from a demold station <NUM> back to the mezzanine <NUM>. The caul plate <NUM> is removed post autoclave <NUM> and then reconditioned as it transitions back into the clean room environment <NUM>, at least in part on the mezzanine <NUM> thus saving floor space. In further embodiments, the mezzanine <NUM> uses dedicated crane facilities which help to avoid overburdening roof/ceiling crane facilities.

<FIG> depict hardening of preforms <NUM> via multiple combined mandrels <NUM> within an autoclave <NUM> in an illustrative embodiment, and correspond with view arrows <NUM> of <FIG>. That is, the autoclave <NUM> is dimensioned to hold multiple combined mandrels <NUM> at once, while hardening the preforms <NUM> thereupon. The autoclave <NUM> includes a body <NUM> having a heater <NUM>, as well, as one or more pumps <NUM> that pressurize an interior <NUM> of the autoclave <NUM>. The autoclave <NUM> forms a boundary <NUM> between a clean room environment <NUM> and a non-clean room environment, for example factory floor <NUM>, such that travel from right to left in the illustration moves the combined mandrel <NUM> through the autoclave <NUM> out of the clean room environment <NUM> and into a non-clean room environment.

In <FIG>, a first door <NUM> of the autoclave <NUM> is opened. This exposes the interior <NUM> of the autoclave <NUM> for receiving the combined mandrels <NUM>. In <FIG>, the combined mandrels <NUM> advance into the interior <NUM>, and in <FIG>, the first door <NUM> and a second door <NUM> are closed, sealing the interior <NUM>. Heat (Δ) and pressure is applied via arrows <NUM> until preforms <NUM> upon the combined mandrels <NUM> are hardened. Then second door <NUM> is opened and the combined mandrels <NUM> and the now hardened composite part <NUM> proceed into the non-clean room environment, or factory floor <NUM>. The process is repeated to iteratively cycle multiple combined mandrels <NUM> through the autoclave <NUM> at a time.

<FIG> depict hardening of multiple preforms <NUM> upon combined mandrels <NUM> within an autoclave <NUM> in an illustrative embodiment, and correspond with view arrows <NUM> of <FIG>. <FIG> depict an alternate embodiment to that shown in <FIG>. The autoclave <NUM> does not include doors, because ends <NUM> of the combined mandrels <NUM>, in combination with seals <NUM> are used to seal preforms <NUM> upon the combined mandrels <NUM> into place for hardening. During operation, the combined mandrels <NUM> are inserted into an interior <NUM> of the autoclave <NUM> and the autoclave <NUM> is sealed to the combined mandrels <NUM> to form at least one vacuum chamber <NUM>. While the combined mandrels <NUM> are inserted into the autoclave <NUM>, the combined mandrels <NUM> and the autoclave <NUM>, along with seals <NUM>, define the vacuum chamber <NUM> for preforms <NUM>. That is, the seals <NUM> seal a perimeter of the combined mandrels <NUM> to an inner surface <NUM> of the autoclave <NUM>. The seals <NUM> may comprise rigid or other thermal barriers for sealing a gap (G) (e.g., an arcuate gap) by clamping to the autoclave <NUM> to form a pressure/vacuum chamber <NUM>. The seals <NUM> may form an arcuate shape and may comprise rigid segments of material between the combined mandrels <NUM> and the autoclave <NUM>.

The autoclave <NUM> is dimensioned to complement the combined mandrels <NUM>, and hence is right-sized for the components <NUM>, such as composite parts <NUM>, that it heats and hardens. Hence, the vacuum chamber <NUM> is smaller than traditional chambers (and smaller than the autoclave in <FIG>). This means that heat and pressure applied to the vacuum chamber <NUM> is applied to a smaller volume than in traditional autoclaves, which increases heating efficiency and hardening speed. This also means that the autoclave <NUM> has less thermal mass, and that smaller pieces of equipment may be used to pressurize the autoclave <NUM> (e.g., with air or nitrogen gas or other inert fluids).

The autoclave <NUM> can be operated according to a desired takt time (e.g., production rate) in order to fabricate composite parts. For example, if a desired fabrication rate for a fuselage segment is one per eight hours, the autoclave <NUM> may be operated to harden preforms <NUM> upon two combined mandrels <NUM> in tandem per sixteen hours. This in turn may dictate other takt times for other stations in the line that fabricate preforms <NUM> for hardening and/or a post hardening assembly line.

In the following examples, additional processes, systems, and methods are described in the context of an assembly line for fabricate fuselage section preforms.

Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of aircraft manufacturing and service in method <NUM> as shown in <FIG> and an aircraft <NUM> as shown in <FIG>. During pre-production, method <NUM> may include specification and design <NUM> of the aircraft <NUM> and material procurement <NUM>. During production, component and subassembly manufacturing <NUM> and system integration <NUM> of the aircraft <NUM> takes place. Thereafter, the aircraft <NUM> may go through certification and delivery <NUM> in order to be placed in service <NUM>. While in service by a customer, the aircraft <NUM> is scheduled for routine work in maintenance and service <NUM> (which may also include modification, reconfiguration, refurbishment, and so on). Apparatus and methods embodied herein may be employed during any one or more suitable stages of the production and service described in method <NUM> (e.g., specification and design <NUM>, material procurement <NUM>, component and subassembly manufacturing <NUM>, system integration <NUM>, certification and delivery <NUM>, in service <NUM>, maintenance and service <NUM>) and/or any suitable component of aircraft <NUM> (e.g., airframe <NUM>, systems <NUM>, interior <NUM>, propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, environmental system <NUM>).

As shown in <FIG>, the aircraft <NUM> produced by method <NUM> may include an airframe <NUM> with a plurality of systems <NUM> and an interior <NUM>. Examples of systems <NUM> include one or more of a propulsion system <NUM>, an electrical system <NUM>, a hydraulic system <NUM>, and an environmental system <NUM>. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the automotive industry.

As already mentioned above, apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service described in method <NUM>. For example, components or subassemblies corresponding to component and subassembly manufacturing <NUM> may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft <NUM> is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the subassembly manufacturing <NUM> and system integration <NUM>, for example, by substantially expediting assembly of or reducing the cost of an aircraft <NUM>. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft <NUM> is in service, for example and without limitation during the maintenance and service <NUM>. Thus, the disclosure may be used in any stages discussed herein, or any combination thereof, such as specification and design <NUM>, material procurement <NUM>, component and subassembly manufacturing <NUM>, system integration <NUM>, certification and delivery <NUM>, in service <NUM>, maintenance and service <NUM> and/or any suitable component of aircraft <NUM> (e.g., airframe <NUM>, systems <NUM>, interior <NUM>, propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, and/or environmental system <NUM>).

Claim 1:
A method (<NUM>) for fabricating a preform (<NUM>) for a fuselage section of an aircraft (<NUM>), the method (<NUM>) comprising:
advancing (<NUM>) a series of arcuate mandrel sections (<NUM>) in a process direction (<NUM>) through an assembly line (<NUM>);
placing (<NUM>) stringer preforms (<NUM>) onto the arcuate mandrel sections (<NUM>) via stringer placement stations (<NUM>);a
uniting (<NUM>) the series of arcuate mandrel sections (<NUM>) into a combined mandrel (<NUM>);
laying up (<NUM>) fiber reinforced material (<NUM>) onto the combined mandrel (<NUM>) and the stringer preforms (<NUM>); and
splicing the fiber reinforced material that is laid-up onto the arcuate mandrel sections, wherein:
- placing (<NUM>) stringer preforms (<NUM>) onto the arcuate mandrel sections (<NUM>) comprises placing (<NUM>) the stringer preforms (<NUM>) during pauses between pulses of the arcuate mandrel sections (<NUM>) along the assembly line (<NUM>); or
- placing (<NUM>) stringer preforms (<NUM>) onto the arcuate mandrel sections (<NUM>) comprises placing (<NUM>) the stringer preforms (<NUM>) as the arcuate mandrel sections (<NUM>) move continuously along the assembly line (<NUM>).