Patent Description:
The mechanical structure of an aircraft is referred to as an airframe. An airframe is made from discrete components such as stringers, spars, skins, and frames which, when assembled together, define a shape of the aircraft. An individual aircraft may be fabricated from many such components, all or some of which may be fabricated as composite parts. For example, an aircraft may utilize a large number of curved or contoured frames to reinforce its fuselage. Ideally, the frames are fabricated at a rate sufficient to meet with a desired assembly timing for a desired production rate for the aircraft, otherwise the fabrication of the aircraft may be undesirably delayed.

The abstract of <CIT> states that systems and methods are provided for controlling flexible tracks. One embodiment is a system for conveying plies of laminate to a forming device. The system includes a flexible track assembly comprising a first portion of track and a second portion of track, each of the portions defining a groove dimensioned to receive a slider that transports a ply, the second portion arranged to transport the ply into the forming device. The track assembly also includes a guide in which ends of the portions are disposed. The system further includes a retraction line that applies a contracting force that biases the end of the second portion towards contact with the end of the first portion, the retraction line being extendable to enable the second portion to separate from the first portion, thereby accommodating extension of the track assembly in response to forces applied by the forming device during forming.

Therefore, it would be desirable to have a method and system that take into account at least some of the issues discussed above, as well as other possible issues.

Embodiments described herein provide assembly lines for rapidly fabricating curved composite parts (e.g., frames) for aircraft via the use of assembly lines. The assembly lines include track systems that dynamically deliver individual plies to a variety of Ply-By-Ply (PBP) forming stations that are clustered together. By dynamically delivering plies for forming to multiple PBP forming stations in a Just-in-Time (JIT) manner, a greater work density can be achieved. That is, curved composite parts can be fabricated rapidly via a unique arrangement of stations that occupies less space on the factory floor than used by conventional assembly techniques. There is disclosed a method for fabricating a curved preformed as recited in claim <NUM>.

There is further disclosed a system for for fabricating curved preforms as recited in claim <NUM>.

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, the scope of the invention being defined by the appended claims.

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 a fabrication system <NUM> for curved preforms of fiber reinforced material in an illustrative embodiment. Lamination stations <NUM> lay up one or more plies <NUM> onto carriers <NUM> of flexible material (discussed below with regard to <FIG>). Fabrication system <NUM> includes multiple Ply-By-Ply (PBP) forming stations <NUM>. Each PBP forming station <NUM> fabricates curved preforms <NUM> by iteratively shaping individual plies <NUM> delivered on carriers <NUM> of flexible material <NUM> into conformance with a mandrel <NUM> (e.g., a contoured mandrel). In one embodiment, PBP forming stations <NUM> comprise forming stations which apply clamping force along an arc, such as those described in <CIT>. In further embodiments, the PBP forming stations <NUM> form complex shapes by draping plies over corners of a mandrel <NUM> before shaping the plies <NUM>.

<FIG> illustrates that the PBP forming stations <NUM> are arranged in a curved pattern <NUM> (e.g., an arc or circle), and are accessible via a rail system <NUM>. Rail system <NUM> includes tracks <NUM>, which are contoured and form one or more loops (e.g., inner concentric circle <NUM>, outer concentric circle <NUM>) between the lamination stations <NUM> and the PBP forming stations <NUM>. In further embodiments, other means of accessibility, such as automated vehicles and tracks, are utilized. The inner concentric circle <NUM> is adjacent to multiple Ply-By-Ply (PBP) forming stations <NUM>, and the outer concentric circle <NUM> is adjacent to at least one lamination station <NUM>. Thus, the tracks <NUM> couple the lamination stations <NUM> to the PBP forming stations <NUM>. In a further embodiment, routing the carriers <NUM> comprises advancing the carriers <NUM> through.

The concentric circles are coupled via spurs <NUM>, which comprise junctions <NUM> at the outer concentric circle <NUM> and the inner concentric circle <NUM>. That is, the tracks <NUM> form the spurs <NUM> that couple the outer concentric circle <NUM> and inner concentric circle <NUM> together. The spurs <NUM> include portions of track <NUM> disposed between the outer concentric circle <NUM> and the inner concentric circle <NUM>. The track <NUM> is elevated, and is held in place by supports <NUM> (e.g., posts). In this embodiment, the supports <NUM> are positioned between the outer concentric circle <NUM> and the inner concentric circle <NUM>. This arrangement permits access to the track <NUM> of the rail system <NUM> by a technician <NUM> operating in a work space <NUM> inside of the fabrication system <NUM> (e.g., within the inner concentric circle <NUM> and hence defined by the rail system <NUM>), and also permits access (e.g., ingress and egress) to the track <NUM> by a technician <NUM> disposed outside of the fabrication system <NUM>. That is, a technician <NUM> within the work space <NUM> can walk up to materials at the inner concentric circle <NUM>, and a technician <NUM> outside of the fabrication system <NUM> can walk up to materials at the outer concentric circle <NUM>. In other embodiments, the supports <NUM> are positioned in other locations relative to the outer concentric circle <NUM> and the inner concentric circle <NUM>.

The spurs <NUM> enable transitions between different portions of track <NUM> and couple the outer concentric circle <NUM> and the inner concentric circle <NUM> together. Hence, backups do not exist at the outer concentric circle <NUM> as a carrier <NUM> (e.g., as shown in <FIG>) can be routed to the inner concentric circle <NUM>. In a similar fashion, if a carrier <NUM> at the inner concentric circle <NUM> is currently being loaded onto a PBP forming station <NUM>, an upstream carrier <NUM> at the outer concentric circle <NUM> can be routed to a next spur <NUM> that is downstream of the carrier <NUM> that is being loaded, in order to arrive at a PBP forming station <NUM> without waiting. Each of the spurs <NUM> may therefore be utilized to move materials between the outer concentric circle <NUM> and the inner concentric circle <NUM>. Movement to the inner concentric circle <NUM> places plies <NUM> (e.g., as shown in <FIG>) within easy ergonomic reach of a technician <NUM> within a work space <NUM> for inspection, or other work and/or movement assistance. In further embodiments, routes between the outer concentric circle <NUM> and the inner concentric circle <NUM> and between the lamination stations <NUM> and the PBP forming stations <NUM> may go clockwise or counterclockwise. Routes on the outer concentric circle <NUM> and the inner concentric circle <NUM> may go clockwise or counterclockwise. The spurs <NUM> are effectively off ramps from the outer concentric circle <NUM> and on-ramps to the inner concentric circle <NUM>. In still further embodiments, switching operations at the spurs <NUM> are controlled based upon received RFID information.

Lamination stations <NUM> lay up plies <NUM> onto carriers <NUM> of flexible material <NUM> (discussed below with regard to <FIG>) that are themselves disposed over layup mandrels <NUM>. The carriers <NUM> are then transported to place the plies <NUM> onto PBP forming stations <NUM>. While two lamination stations <NUM> are shown, more or less lamination stations <NUM> are possible depending on design considerations. Feeder lines <NUM> supply fiber reinforced material <NUM> of <FIG> to the lamination stations <NUM> in a Just in Time (JIT) manner. The carriers <NUM> advance along the rail system <NUM> towards the PBP forming stations <NUM> for application to a mandrel <NUM> and integration/compaction into a preform <NUM> for a composite part. In PBP forming processes used by the PBP forming stations <NUM>, a single ply (or small group of plies) <NUM> is shaped according to a desired contour into a base of a preform <NUM>, then additional plies <NUM> are added to the preform <NUM> and shaped until the preform <NUM> is completed. In yet further embodiments, each lamination station <NUM> is different. For example, different lamination stations <NUM> may produce plies <NUM> of different fiber orientations as desired. Plies <NUM> laid-up by the lamination stations <NUM> are arranged into flat pattern, and each flat pattern may be associated with a different identifier provided by a Radio Frequency Identifier (RFID) chip <NUM> on the carrier <NUM>. In further embodiments, there are additional inner concentric circles which each have a lamination station thereat.

Portions of track <NUM> can be disposed at different heights/elevations above the shop floor. Therefore, up to four lamination stations <NUM> could have four rail systems <NUM> including outer concentric circle <NUM>, spur <NUM> and the inner concentric circle <NUM> at four different heights/elevations above the shop floor. Each rail system <NUM> can deliver plies to the PBP forming stations <NUM> and be tracked along the way using an RFID system. The order of application of the plies <NUM> from the rail systems <NUM> is predetermined prior to the plies <NUM> leaving on carriers <NUM> from the lamination stations <NUM>.

Depending on the embodiment, each of the lamination stations <NUM> may lay up plies to supply one or more PBP forming stations <NUM>. In one embodiment, the lamination stations <NUM> remain stationary while performing layup onto the carriers <NUM>. However, in further embodiments, the lamination stations <NUM> move along or next to the carriers <NUM> and/or track <NUM> (e.g., via actuators or other motorized elements not shown) during layup as desired to form a ply. The laminations stations <NUM> may lay up plies via automated lamination techniques (e.g., automated taping, laying, or fiber placement), via a combination of a composite cutting machine and pick and place techniques, or via any suitable means onto a carrier (e.g., carrier <NUM> of <FIG>) disposed at a layup mandrel <NUM>. Furthermore, lamination stations <NUM> may perform lamination at a horizontal orientation or vertical orientation as desired, by placing fiber reinforced material <NUM> onto a horizontal layup surface or a vertical layup surface, respectively. After layup for a preform <NUM> has been completed, a new layup mandrel (e.g., for another design of preform <NUM>) may replace the current layup mandrel <NUM> at a lamination station <NUM>. Because the carrier <NUM> is conformable, it adapts to the geometry of the current layup mandrel <NUM>.

In one embodiment, the lamination stations <NUM> dynamically lay up plies (e.g., ply <NUM> of <FIG>) for multiple preforms, according to the design of the current preform (e.g., preform <NUM> of <FIG>) being shaped by each PBP forming station <NUM>. For example, a first PBP forming station <NUM> may fabricate a preform <NUM> by applying plies onto a carrier <NUM> until the preform <NUM> is completed for a frame of an aircraft, a second PBP forming station <NUM> may fabricate a preform for a frame of a different design for an aircraft, and a third PBP forming station <NUM> may fabricate a preform <NUM> for a door surround or window surround. Each ply <NUM> for each preform <NUM> being fabricated may therefore be shaped differently or exhibit different fiber orientations in order to facilitate the design. Thus, different plies <NUM> may include different configurations of fiber-reinforced material, placed at different fiber orientations. Phrased another way, the PBP forming stations <NUM> iteratively shape individual plies <NUM> into conformance with a mandrel <NUM>.

Even in embodiments where plies <NUM> are being laid up for PBP forming stations <NUM> that are fabricating preforms of the same design, the plies <NUM> used for each layer of those preforms <NUM> may vary throughout the thickness of the preform <NUM>. Thus, the ply <NUM> laid-up for one PBP forming station <NUM> at a first stage of fabrication may be different from a ply <NUM> laid-up for a PBP forming station <NUM> at a second stage of fabrication for a preform of the same design. Furthermore, while only one preform <NUM> is shown in <FIG>, it will be appreciated that a preform <NUM> may be fabricated at each of the forming stations <NUM> at the same time (e.g., resulting in four preforms <NUM> being formed at the same time at the forming stations of <FIG>.

In one embodiment, the lamination stations <NUM> dynamically determine a ply <NUM> to lay up, based on a progress of each of the PBP forming stations <NUM>. In further embodiments, the order of plies <NUM> being laid-up is predetermined. In either case, carriers <NUM> that carry plies intended for distant PBP forming stations <NUM> may route through the outer concentric circle <NUM> in order to advance past carriers <NUM> that are paused at other PBP forming stations <NUM>. In some embodiments, the carriers <NUM> are advanced continuously through the rail system <NUM>, while in further embodiments the carriers <NUM> are "pulsed" in the direction indicated by the arrows <NUM> of <FIG>, and may be pulsed clockwise, counterclockwise, or in different directions at each of the concentric circles. The carriers <NUM> are pulsed by advancing the carriers <NUM> synchronously and then pausing the carriers <NUM> synchronously at regular intervals according to a desired takt time. Pulsed motion along arrows <NUM> may be implemented as a "micro pulse" wherein the carriers <NUM> are moved by less than their length per movement, or as a "full pulse" wherein the carriers <NUM> are advanced by at least their entire length per pulse, in either a manual or automated process.

<FIG> further depicts a controller <NUM>, which in this embodiment is coupled for communication with lamination stations <NUM> and PBP forming stations <NUM>, and/or track <NUM> and RFID scanners <NUM> of <FIG>. In this embodiment, controller <NUM> coordinates the actions of the depicted devices, as well as movement of carriers <NUM> along the rail system <NUM> in a coordinated and synchronous manner, wherein the carriers <NUM> are prevented from creating traffic jams with respect to other carriers <NUM> at the rail system <NUM>. This may be performed, for example, by coordinating the actions of the lamination stations <NUM>, PBP forming stations <NUM>, and/or carriers <NUM> in accordance with one or more Numerical Control (NC) programs. In one embodiment, controller <NUM> is implemented as custom circuitry, as a hardware processor executing programmed instructions stored in memory, or some combination thereof.

In further embodiments, the fabrication system <NUM> is utilized for Just In Time (JIT) delivery of preforms <NUM> for frames or components to a moving line, wherein plies <NUM> are delivered as they are needed to PBP forming stations <NUM> without a need to maintain an inventory of the plies <NUM> at the PBP forming stations <NUM>. Frames are delivered by the fabrication system <NUM> as they are needed to subsequent fabrication system (such as for assembly of an aircraft fuselage), without a need for the subsequent fabrication system to maintain an inventory of those frames.

Components moving along the line can be pulsed by their length or less than their length, and then paused. Alternatively, the components can be moved continuously. The various elements moved along the rail system <NUM> can be moved via automated or manual processes in a process direction. In on embodiment, up to four preforms <NUM> are fabricated at the same time, and progress of each of the preforms <NUM> is tracked by controller <NUM> via input from the PBP forming stations <NUM> and/or the lamination stations <NUM>. Based on received input, the controller <NUM> determines the order and/or orientation of plies <NUM> that have applied, as well as the order and/or orientation of plies <NUM> yet to be applied to each of the PBP forming stations <NUM>.

In further embodiments, carriers <NUM> include identifiers such as markings, barcodes, or Radio Frequency Identifier (RFID) chips <NUM>, which are used to track plies laid-up thereon, as well as the movement of the carriers <NUM> from the lamination stations <NUM> to the PBP forming stations <NUM> and back. In such embodiments, tracking systems <NUM> (e.g., laser scanners, optical devices, RFID scanners <NUM>, etc.) detect the progress of the carriers <NUM> through the rail system <NUM>. In one embodiment, lamination stations <NUM> and/or PBP forming stations <NUM> are disposed directly above or below the rail system <NUM> in order to facilitate attachment/detachment operations. This may also eliminate concerns related to traffic stacking or bagging up. In one embodiment, the rail system <NUM> progresses the carriers <NUM> continuously in an elevation above a shop floor.

<FIG> depict movement of a carrier <NUM> and ply <NUM> through the fabrication system <NUM> of <FIG> in an illustrative embodiment. Assume, for this embodiment, that a lamination station <NUM> has laid-up a ply <NUM> onto a carrier <NUM>, which is made from a flexible material, such as a flexible fabric, deformable film that elastically returns to its original shape after deformation, a material discussed in <CIT>, a material discussed in <CIT>, etc. The ply <NUM> is tacked or otherwise affixed to the carrier <NUM>, which means that the ply <NUM> is retained in contact with the carrier <NUM>, and bends with the carrier <NUM> as the carrier <NUM> travels along the track <NUM>. That is, bending/flexing of the carrier <NUM> during movement of the carrier <NUM> is not the same as the PBP forming processes discussed above, but rather occurs during transport prior to the ply <NUM> undergoing PBP forming. Newly received carriers <NUM> may be disengaged from the track <NUM> prior to presentation to a lamination station <NUM> or PBP forming station <NUM>.

After layup (e.g., for one to two plies for shaping together onto a preform <NUM> at a PBP forming station <NUM>) has been completed, the carrier <NUM>, is placed onto a track <NUM> of the rail system <NUM> as shown in <FIG>. The carrier <NUM> is then advanced through the rail system <NUM>. Because the rail system <NUM> includes tracks <NUM> that are curved, the carrier <NUM> flexibly curves as it follows the tracks <NUM>. The ply <NUM> at the carrier <NUM> is originally laid down in a flat pattern that suits the contour of a preform <NUM>. While the ply <NUM> conforms to the curvature of the track <NUM> during transport to a PBP forming station <NUM>, the act of transport does not permanently impart a contour to the ply <NUM>.

The dynamic changes in shape of the carrier <NUM> caused by the tracks <NUM> cause the carrier <NUM> to exhibit an inner curvature <NUM> and an outer curvature <NUM>. In this embodiment, the ply <NUM> occupies the inner curvature <NUM> of the carrier <NUM> while the carrier <NUM> is disposed at the outer concentric circle <NUM>. In <FIG>, the carrier <NUM> switches tracks at a junction <NUM>, and proceeds into the inner concentric circle <NUM>. Because the carrier <NUM> is flexible, and because the ply <NUM> remains tacked or otherwise retained by the carrier <NUM>, the ply <NUM> and the carrier <NUM> conform to the curvature of the portion of the track <NUM> that they traverse. For this reason, the track <NUM> is dimensioned to provide a geometry wherein a radius of curvature is always at least equal to or greater than a predefined amount (e.g., ten inches, two feet, etc.). In one embodiment, the radius of curvature is always directly related to a radius of a finally fabricated preform <NUM>. The track <NUM> is of a contour or arc such that the ply <NUM> and the carrier <NUM> stay adhered (i.e., is not tighter than a threshold radius of curvature), but is also able to support a range of geometries for a lamination station <NUM>. The range of geometries allows for the fabrication of preforms <NUM> having different radii of curvature. This curvature can ensure that the carrier <NUM> and ply <NUM> are not pinched in a manner that would result in the ply <NUM> separating from the carrier <NUM> during transport via manual or automated processes.

<FIG> illustrates that the carrier <NUM> follows a "U" shape <NUM> while being transported via manual or automated processes while traversing spur <NUM>. In an embodiment where the carrier <NUM> hangs vertically from the track <NUM>, the carrier <NUM> may have its orientation altered from horizontal to vertical (e.g., by rotating the carrier <NUM>). Thus, in such an embodiment, laying up the plies <NUM> is performed while the carriers <NUM> are oriented horizontally, and loading the carriers <NUM> comprises orienting the carriers <NUM> vertically. The "U" shape <NUM> is followed as the carrier <NUM> bends to transition from a rotating outer concentric circle <NUM> onto an inner concentric circle <NUM> that counter-rotates via a manual or automated process. This causes the ply <NUM> to occupy an outer curvature of the carrier <NUM>, which enables the ply <NUM> to be directly placed into contact with a mandrel <NUM>, thereby applying a first ply for a preform <NUM>, or adding material to a preform <NUM> already placed thereupon. However, in further embodiments as shown in <FIG>, an "S" shape <NUM> is followed as the carrier <NUM> bends to transition from the outer concentric circle <NUM> into the inner concentric circle <NUM> when both are rotating in the same direction via a manual or automated process. In an embodiment where the carrier <NUM> hangs vertically from the track <NUM>, the carrier <NUM> may have its orientation altered from horizontal to vertical (e.g., by rotating the carrier <NUM>). Thus, in such an embodiment, laying up plies <NUM> is performed while the carriers <NUM> are oriented horizontally, and loading the carriers <NUM> comprises orienting the carriers <NUM> vertically. In this embodiment a rotation or flipping step is required prior to presentation of the ply <NUM> to the mandrel <NUM>, although in further embodiments the preform <NUM> is applied to the carrier <NUM> in a manner such that after following the "S" shape <NUM>, the preform <NUM> faces the mandrel <NUM>.

In <FIG>, the carrier <NUM> has completed its traversal through the spur <NUM> via a manual or automated process, and has arrived at PBP forming station <NUM>. The portions of track <NUM> over which the carrier <NUM> has traveled may be referred to as a first track <NUM> that leads from the lamination station <NUM> to location <NUM> prior to placement at the PBP forming station <NUM>. The ply <NUM> has not moved relative to the carrier <NUM>, but because of the curvature of track <NUM>, now occupies an outer curvature <NUM> of the carrier <NUM>, can be directly placed onto the mandrel <NUM> of the PBP forming station <NUM>.

<FIG> illustrates the carrier <NUM> and the ply <NUM> separated from the rail and pressed into contact with a mandrel <NUM> and/or preform <NUM> of the PBP forming station <NUM> via manual or automated processes. In further embodiments, the PBP forming stations <NUM> additional perform draping and/or rotation of the carriers <NUM> and the plies <NUM>, in order to form the plies <NUM> to desired complex contours. The carrier <NUM> is then removed from the ply <NUM> (e.g., by peeling the carrier <NUM> away via manual or automated means), and placed back onto the rail system <NUM> in <FIG>. The peeling may be performed via a manual or automated process. The ply <NUM> now exhibits an outer frame portion <NUM> and an inner frame portion <NUM>. The carrier <NUM> then proceeds via the rail system <NUM> (e.g., transitioning via a spur <NUM> as described above with regard to <FIG>, only in reverse) from the inner concentric circle <NUM> to the outer concentric circle <NUM> for cleaning, replacement, or re-use at the lamination station <NUM>. The portions of track <NUM> over which the carrier <NUM> has traveled to return for re-use may be referred to as a second track <NUM> that leads from the PBP forming station <NUM> to the lamination station <NUM>. The ply <NUM> is then formed onto a mandrel <NUM>, or onto preform <NUM> that is already disposed at the mandrel <NUM>.

<FIG> depicts multiple carriers <NUM> traversing the fabrication system of <FIG> in an illustrative embodiment. As shown in <FIG>, the rail system <NUM> supports the use of multiple carriers <NUM> at once. The carriers <NUM> may be advanced in the same direction <NUM> through each of the concentric circles of track <NUM>, in order to ensure a continuous flow of materials without blocking or interference between different carriers. Carriers <NUM> return to the lamination station <NUM> along the outer concentric circle <NUM> for the carrier <NUM>. Thus, layup is placed upon the carrier <NUM> and the carrier <NUM> traverses to the inner concentric circle <NUM> where it is detached and moved into alignment with a PBP forming station <NUM>, the carrier <NUM> then moves back to the inner concentric circle <NUM>, and proceeds to the outer concentric circle <NUM> to return to the lamination station <NUM> for joining to a ply <NUM>. Throughout the entire process, the carrier <NUM> is tracked via technicians <NUM> and/or components of rail system <NUM>.

In a similar way, a multilevel track system could also be employed with up to four lamination stations <NUM> per level of track <NUM> that moves carriers <NUM> (which bear plies <NUM>) through outer concentric circle <NUM>, to spur <NUM>, to inner concentric circle <NUM>, to location <NUM> for placement at a PBP forming station <NUM>. A technician <NUM> may move the carriers <NUM> onto the PBP forming station <NUM> via manual or automated systems from one of the multiple levels one at a time. More than one technician <NUM> may be working within work space <NUM> at the same time.

Upon completion of a preform <NUM>, the preform <NUM> may exit the rail system <NUM> for hardening into an autoclave dimensioned to the preform <NUM>, or hardening at any suitable processing device. The preform <NUM> may exit the fabrication system <NUM> via any suitable direction, such as via travel underneath or above the rail system <NUM>.

In further embodiments, rail system <NUM> comprises any number of levels of any suitable combination of rails, spurs, and/or concentric or nested portions of track that enable multiple carriers <NUM> to traverse back and forth from lamination stations <NUM> to PBP forming stations <NUM> without interference in a synchronized manner. In such embodiments, the spurs <NUM> operate as a plurality of modular connection points that facilitate transitioning between concentric portions of track <NUM>, nested portions of track <NUM>, etc..

Illustrative details of the operation of fabrication system <NUM> will be discussed with regard to <FIG>. Assume, for this embodiment, that fabrication system <NUM> is preparing to fabricate multiple preforms <NUM> at once via PBP forming stations <NUM>.

<FIG> is a flowchart depicting a method <NUM> for operating a fabrication system for preforms <NUM> (e.g., curved preforms) of fiber reinforced material <NUM> in an illustrative embodiment. The steps of method <NUM> are described with reference to fabrication system <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.

In step <NUM>, one or more lamination stations <NUM> identify a set of curved preforms being fabricated by PBP forming stations <NUM>, which are disposed at rail system <NUM>. In one embodiment, step <NUM> comprises operating the lamination stations <NUM> according to Numerical Control (NC) programs that have been designed to complement NC programs that control the PBP forming stations <NUM>. In a further embodiment, the lamination stations <NUM> detect progress information from the PBP forming stations <NUM> or another source, and determine which plies <NUM> are needed next on an ongoing basis. In yet another embodiment, a controller <NUM> managing the PBP forming stations <NUM> and the laminations stations <NUM> selects plies for layup based on a predetermined schedule.

In step <NUM>, a lamination station <NUM> lays up at least one ply onto carrier <NUM>, which is made of a flexible material. In one embodiment, lamination stations <NUM> lay up plies <NUM> for the preforms <NUM> (e.g., curved preforms) onto carriers <NUM> at a lamination station <NUM>. Each of the plies <NUM> is placed in a flat pattern upon the carrier <NUM> in a configuration that facilitates matching to a desired contour during forming at a PBP forming station <NUM>. In one embodiment, each lamination station <NUM> lays up a ply <NUM> (e.g., a single ply) onto a carrier <NUM>, while in further embodiments, the lamination stations <NUM> lay up multiple plies <NUM> at a time onto a carrier <NUM> (e.g., one ply on top of the other. Each ply may have a slightly different flat pattern configuration to facilitate forming to a contour and forming to a contour over multiple plies). In still further embodiments, each of the lamination stations <NUM> performs lay up onto multiple carriers <NUM> at once. In yet further embodiments, more or fewer lamination stations <NUM> and/or PBP forming stations <NUM> operate at the same time to fabricate a number of preforms <NUM> equal to the number of PBP forming stations <NUM> during the same period of time. In one embodiment, he carriers <NUM> may be horizontally oriented and flat during ply layup. In a further embodiment, the lamination station <NUM> performs lamination of the ply <NUM> onto a horizontal orientation or vertical orientation as desired, by placing fiber reinforced material <NUM> onto a horizontal layup surface or a vertical layup surface, respectively.

The lamination stations <NUM> may lay up the ply <NUM> via automated lamination techniques (e.g., automated taping, laying, or fiber placement), via a combination of a composite cutting machine and pick and place techniques, or via any suitable means. In one embodiment, the ply <NUM> comprises a piece of fiber reinforced material <NUM> having a desired fiber orientation (e.g., <NUM>° +/-<NUM>°, <NUM>°), such as a piece of CFRP. In a further embodiment, the ply <NUM> comprises a fabric of pre-impregnated woven fiber reinforced material, pre-impregnated random fibers, or pre-impregnated discontinuous fibers. The ply <NUM> may comprise cut pieces of broad goods formed via hand layup techniques, may be fabricated from tows via Automated Tape Layup Machines (ATLMs), Advanced Fiber Placement (AFP) machines, etc. In one embodiment, the lamination stations <NUM> apply compaction and/or heat that tacks resin at the ply <NUM> to the carrier <NUM>. This tacks the ply <NUM> into place at the carrier <NUM> sufficiently enough to facilitate the flexibility of the combination of ply <NUM> and carrier <NUM> as it proceeds through the outer concentric circle <NUM>, spurs <NUM> and the inner concentric circle <NUM>.

In step <NUM>, the carrier <NUM> is loaded onto the rail system <NUM>. In one embodiment, this comprises attaching the carrier <NUM> to the track <NUM> of the rail system <NUM> at an outer concentric circle <NUM>, such that the carrier <NUM> hangs from the track <NUM> and is capable of sliding or rolling along the track <NUM>, lengthwise relative to the track <NUM> (as depicted in <FIG>). For example, in one embodiment the carrier <NUM> includes multiple attachment points that are inserted into the track <NUM> or hung from the track, enabling the carrier <NUM> to hang from the track <NUM> as described in <FIG>. Furthermore, in step <NUM>, an orientation of the carriers <NUM> may be altered to accommodate placement onto the track <NUM>. In an embodiment (as depicted in <FIG>) where the carrier <NUM> hangs vertically from the track <NUM>, the carrier <NUM> may have its orientation altered from horizontal to vertical (e.g., by rotating the carrier <NUM>. Thus, in such an embodiment, laying up plies <NUM> is performed while the carriers <NUM> are oriented horizontally, and loading the carriers <NUM> comprises orienting the carriers <NUM> vertically (as depicted in <FIG>).

In step <NUM>, the carrier <NUM> is routed to a particular forming station <NUM> (e.g., depending on the preform <NUM> that the at least one ply <NUM> at the carrier <NUM> is intended for), based on a characteristic of the at least one ply <NUM> carried by the carrier <NUM>. In one embodiment, carriers <NUM> are routed to different ones of the PBP forming stations <NUM> based on plies <NUM> carried by the carriers <NUM>. Characteristics of a ply <NUM> may comprise a flat pattern size, an orientation of fibers of the ply <NUM>, etc. Thus, based on these characteristics, a ply <NUM> may be suitable for a specific layer of a specific preform <NUM> being currently fabricated at a specific PBP forming station <NUM>. Thus, based on these characteristics of a ply <NUM>, a carrier <NUM> may be routed to different PBP forming stations <NUM>.

That is, the carriers <NUM> are routed to the PBP forming stations <NUM> which will be utilizing their plies <NUM>. In one embodiment, routing a carrier <NUM> to a PBP forming station <NUM> comprises identifying a junction <NUM> prior to (e.g., adjacent to or disposed upstream of) the PBP forming station <NUM>, advancing the carrier <NUM> to the junction <NUM>, and switching the carrier <NUM>, at the junction <NUM>, to a track <NUM> that leads directly to the PBP forming station <NUM>. During routing, a junction <NUM> just before a desired PBP forming station <NUM> is used to transition from an outer concentric circle <NUM> to an inner concentric circle <NUM>, as shown in <FIG>. In one embodiment, routing the carrier <NUM> to a particular PBP forming station <NUM> at the rail system <NUM> based on a characteristic of plies <NUM> carried by the carriers <NUM>. Characteristics of a ply <NUM> include a flat pattern size and the orientation of fibers of the ply <NUM>.

Each carrier <NUM> is routed to a PBP forming station <NUM> that will utilize a ply <NUM> carried by that carrier <NUM> next during the PBP forming process for a preform <NUM> currently being fabricated by the PBP forming station <NUM>. In one embodiment, routing the carriers <NUM> comprises bending/deforming/flexing a shape of a carrier <NUM> as the carrier <NUM> moves along the rail system <NUM>. Bending/flexing the shape of the carrier <NUM> facilitates movement of the carrier <NUM> and ply <NUM> along the rail system <NUM>, and does not impart a permanent change in shape. The rail system <NUM>, because of its shape and because of the length of the carriers <NUM>, bends the carriers <NUM> into temporary compliance with the track <NUM> as the carriers <NUM> move. In a further embodiment, routing the carriers <NUM> comprises advancing the carriers <NUM> through one or more loops (e.g., inner concentric circle <NUM>, outer concentric circle <NUM>) between the formed by the rail system <NUM> between the lamination stations <NUM> and the PBP forming stations <NUM>.

In step <NUM>, the at least one ply <NUM> is separated from the carrier <NUM>. In one embodiment, plies <NUM> are applied from the carriers <NUM> to corresponding ones of the PBP forming stations <NUM>. This comprises transferring the plies <NUM> to mandrels <NUM> and/or preforms <NUM> of the PBP forming stations <NUM>. In one embodiment, this comprises pressing a carrier <NUM> towards a mandrel <NUM> until a ply <NUM> at the carrier <NUM> comes into contact with and adheres to the mandrel <NUM> or a preform <NUM> shaped thereon. In further embodiments, upon application of each ply <NUM>, controller <NUM> directs a technician to apply a particular ply <NUM> and/or separate the carrier <NUM> from the ply <NUM> (e.g., according to timing information, or feedback from a PBP forming station <NUM>).

The carrier <NUM> is removed (e.g., peeled) from the ply (or preform), for example by removing the tack between the carrier <NUM> and the ply <NUM> such as via mechanical or manual peeling. The carrier <NUM> is then placed back onto a track <NUM> of the rail system <NUM>, and moved via the rail system <NUM> back to a lamination station <NUM> for re-use, moved to a cleaning station for cleaning, or removed from the rail system <NUM> entirely.

In step <NUM>, the at least one ply <NUM> is made into a preform <NUM> via the particular PBP forming station <NUM>. Once received at the PBP forming station <NUM>, the ply <NUM> is shaped. That is, after each ply <NUM> has been transferred to a PBP forming station <NUM>, the PBP forming station <NUM> forms the ply <NUM> over an existing preform (or mandrel <NUM>, if the ply <NUM> is the first ply of the preform). This may be performed while the carrier <NUM> remains in contact with the ply <NUM>, or after separation of the carrier <NUM>, depending on embodiment. This operation (e.g., a compacting operation) makes the ply <NUM> integral with the underlying preform <NUM>, if one exists at the PBP forming station <NUM>. The operation also tacks the ply <NUM> to the preform <NUM>. In some embodiments, upon completion of step <NUM>, further step <NUM> including returning carrier <NUM> to the lamination stations <NUM> via the rail system <NUM>. Returning step <NUM> may be performed via a spur <NUM> in rail system <NUM>.

Method <NUM> provides a substantial benefit over prior systems and techniques, because it enables a greater work density than those systems. Multiple lamination stations <NUM> are concentrated closer to forming stations <NUM> than before, thereby greatly increasing work density. Specifically, a greater number of PBP forming stations <NUM> may be placed within close proximity in order to form preforms <NUM> (e.g., curved preforms) for composite parts, and multiple PBP forming stations <NUM> (e.g., four stations), may be overseen by a single technician, which increases the efficiency of labor. Specifically, a single technician <NUM> can provide support for automated or semi-automated operation of the PBP forming stations <NUM>, such as by removing carriers <NUM>, performing visual inspection, etc..

<FIG> depicts a further arrangement of lamination stations and PBP forming stations in an illustrative embodiment. In this embodiment, fabrication system <NUM> includes lamination stations <NUM> and <NUM>, which lay up plies of fiber reinforced material onto carriers <NUM> for distribution to PBP forming stations <NUM>, <NUM>, <NUM>, and <NUM>. The lamination station <NUM> is fed by a feeder line <NUM> for fiber reinforced material, and the lamination station <NUM> is fed by a feeder line <NUM> for fiber reinforced material.

The carriers <NUM> travel along track <NUM> in the direction indicated by the arrows, providing plies on an as-needed basis to the PBP forming stations <NUM>. Although two lamination stations <NUM> and four PBP forming stations <NUM> are shown, in further embodiments any suitable number of each may be utilized (e.g., four lamination stations and four PBP stations). In a further embodiment, each of the lamination stations <NUM> is dedicated to layup at a different fiber orientation (e.g., +<NUM>°, -<NUM>°, <NUM>°, <NUM>°). This may reduce the complexity of the lamination stations <NUM> while also increasing throughput.

<FIG> is a diagram <NUM> depicting flow of materials through the fabrication system <NUM> of <FIG> for curved preforms of fiber reinforced material in an illustrative embodiment. In <FIG>, materials such as plies <NUM> flow from lamination station <NUM> and lamination station <NUM> to PBP forming station <NUM>, PBP forming station <NUM>, PBP forming station <NUM>, and PBP forming station <NUM>. According to diagram <NUM>, lamination station <NUM> and lamination station <NUM> determine a next ply for a preform being fabricated at the PBP forming stations <NUM>. In this embodiment, all of the PBP forming stations <NUM> are at the same stage of fabrication for preforms <NUM> of the same design. This means that a ply <NUM> which has been newly created can be supplied to any of the PBP forming stations <NUM>.

The lamination stations <NUM> and <NUM> lay up plies of flat pattern onto a carrier <NUM>, and the carriers <NUM> advance through the PBP forming stations <NUM>. A perimeter configuration of the flat pattern is sized to the particular location the ply will be placed within the preform <NUM> and the contour designed for that ply <NUM>. Because the lamination stations <NUM> and <NUM> are disposed at different locations along a rail system <NUM>, when the carriers <NUM> are moved along the rail system <NUM>, they reach different PBP forming stations first. Specifically, carriers <NUM> from lamination station <NUM> reach PBP forming station <NUM> first, and while carriers <NUM> from lamination station <NUM> reach PBP forming station <NUM> first, as indicated by the uppermost "advance carrier" arrow from lamination station <NUM>, and the uppermost "advance carrier" arrow from lamination station <NUM>. The plies are then applied to those PBP forming stations <NUM> and <NUM>.

The laminations stations <NUM> and <NUM> prepare additional plies, which are laid-up onto carriers <NUM> and moved along a rail system <NUM>. In further embodiments, different ones of carriers <NUM> are disposed at different points of <FIG> than each other at a point in time (e.g., at a lamination station, on the track <NUM>, at a PBP forming station <NUM> or <NUM> prior to peeling, at a PBP forming station <NUM> or <NUM> after peeling.

Upon reaching PBP forming stations <NUM> and <NUM>, it is determined that the PBP forming stations are busy. Thus, the carriers <NUM> advance to PBP forming stations <NUM> and <NUM>, and plies are applied to those PBP forming stations <NUM> and <NUM>. Upon completion of PBP forming operations for individual plies, corresponding carriers <NUM> for those plies <NUM> are peeled from the plies <NUM> and are returned to the lamination stations <NUM> via the rail system <NUM>.

With a discussion of overall process flow discussed above, the following figures discuss illustrative implementations of tracks and carriers. <FIG> depicts a rail system <NUM>, wherein a carrier <NUM> travels along a track <NUM> that is curved in an illustrative embodiment. In this embodiment, supports <NUM> hold the track <NUM> in an elevated position. The track <NUM> may comprise a portion of an inner concentric circle <NUM>, outer concentric circle <NUM>, spur <NUM>, or other portion of a rail system <NUM>. The supports <NUM> include posts <NUM>, which support heads <NUM> from which arms <NUM> project. The carrier <NUM> includes multiple components, including a body <NUM> of flexible material, and a band <NUM> which is thicker than the body <NUM>. In this embodiment, the band <NUM> weighs more than the body <NUM>, and helps the carrier <NUM> to travel along the track <NUM> by ensuring that the carrier <NUM> consistently hangs from the track <NUM>. Attachment elements <NUM> are affixed to the carrier <NUM> enable slidable or rolling attachment of the carrier <NUM> to the track <NUM>, and may for example comprise wheels or rollers that fit within grooves or projections at the track <NUM>. In further embodiments, the attachment elements <NUM>, or the track <NUM>, include motorized wheels that enable automatic movement of the carrier <NUM> as desired. In any case, the attachment elements <NUM> slidably travel at the track <NUM>.

The carrier <NUM> is affixed to the attachment elements <NUM>, travels along the track <NUM> with the attachment elements <NUM>, and bends/flexes to match the contoured track while traveling. As the carrier <NUM> progresses along the track <NUM>, the carrier <NUM> hangs vertically from the track <NUM>, and flexes to conform with the contour of the track <NUM>. This feature is enabled by the flexible nature of the body <NUM> of the carrier <NUM>.

<FIG> depicts a coupling of a carrier to a track in an illustrative embodiment, and corresponds with view arrows 10B of <FIG>. As shown in <FIG>, a retention element <NUM>, disposed at a rod <NUM> of carrier <NUM> has been slid into a channel <NUM> defined by a body <NUM> at track <NUM>. Thus, the channel <NUM> is for receiving a retention element <NUM> of each attachment element <NUM>. The retention element <NUM> (e.g., a wheel or a static button) has been inserted from an end of the track <NUM>, or at a cut-out disposed within the track <NUM>. The retention element <NUM> slides within the channel <NUM> as the carrier <NUM> proceeds into or out of the page along the track <NUM>. In further embodiments, rollers <NUM> disposed at the track <NUM>, or at the carrier <NUM>, drive the retention element <NUM> through the track <NUM> (e.g., by rotating the rollers or the retention element <NUM>).

<FIG> depicts a carrier <NUM> transporting a ply <NUM> for application to a PBP forming station in an illustrative embodiment. The ply <NUM> is tacked to the carrier <NUM> (e.g., via the application of pressure during layup, causing a resin within the ply <NUM> to adhere to the surface of the body <NUM> in response to applied heat and compaction forces). The ply <NUM> itself is also flexible to a limited degree. Thus, as long as a radius (R) of curvature of the track <NUM> remains greater than a predetermined limit, the preform <NUM> remains adhered to the carrier <NUM>.

<FIG> depicts a carrier <NUM> and ply <NUM> rotating from a horizontal orientation to a vertical orientation in an illustrative embodiment. This means that <FIG> depicts a carrier <NUM> at a series of points in time during a transition between orientations, illustrated as a horizontal orientation <NUM>, orientation <NUM>, orientation <NUM>, and a vertical orientation <NUM>. The rotation facilitates transition of a carrier <NUM> from a horizontal orientation <NUM> for receiving a layup from lamination heads <NUM> at a lamination station <NUM>, to a vertical orientation <NUM> for performing transport at a track <NUM>. In one embodiment, the lamination station <NUM> lays up plies <NUM> onto carriers <NUM> while the carriers <NUM> are in a horizontal orientation <NUM>, and carrier <NUM> are in a vertical orientation <NUM> via a rotation machine <NUM> (e.g., an end effector or rotary element) after lay up for a ply has been completed. In one embodiment, the rotation machine <NUM> may effect a connection of carrier <NUM> to track <NUM> while in a horizontal orientation <NUM> and then allow the carrier <NUM> to fall into a vertical orientation <NUM>.

<FIG> depicts an alternative illustrative embodiment of that shown in <FIG>, in which carrier <NUM> and ply <NUM> are rotated from a horizontal orientation to a vertical orientation in a direction opposite that shown in <FIG>. <FIG> depicts a carrier <NUM> at a series of points in time during a transition between orientations, illustrated as horizontal orientation <NUM>, orientation <NUM>, orientation <NUM>, and a vertical orientation <NUM>. In vertical orientation <NUM>, carrier <NUM> and plies <NUM> are positioned in an alternative arrangement relative to track <NUM>, as needed in alternative embodiments of the transportation and presentation of ply <NUM> and carrier <NUM> at a forming station.

<FIG> depicts a further fabrication system <NUM> for curved preforms in an illustrative embodiment. In this embodiment, the fabrication system <NUM> includes a track <NUM> that forms a curved "Serpentine" shaped pattern, in which two PBP forming stations <NUM> are supervised by technician <NUM> at a work space <NUM>. The PBP forming stations <NUM> are arranged at different orientations such that after each point of inflection <NUM> of the track <NUM>. The inner mold line (IML) surfaces <NUM>-<NUM> through <NUM>-<NUM> change from facing downwards relative to the page to upwards (or vice versa) to accommodate the work spaces <NUM>. The outer mold line (OML) surfaces, <NUM>-<NUM> through <NUM>-<NUM>, change from facing upwards relative to the page to downwards (or vice versa). This arrangement enables a single lamination station <NUM> to service multiple PBP forming stations <NUM> at once.

<FIG> depicts an elevated rail <NUM> that enables a technician <NUM> to pass under it in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. Specifically, the elevated rail <NUM>, which is held in position by supports <NUM>, is held such that carriers <NUM> are elevated at a height H from a factory floor <NUM>. Depending on embodiment, H may be set at the top of a range of expected maximum heights of workers (e.g., seven feet, eight feet, etc.), set to the height of a ceiling (e.g., eight or ten feet), etc. The spacing of the support <NUM>, together with the height H, form an exit <NUM> for a technician <NUM> to safely leave a work space. In a further embodiment, the height H plus a carrier width (Δ) adds to the height range. This enables a technician <NUM> to exit without the exit <NUM> being partially obscured by a carrier <NUM>. In further embodiments, the technician <NUM> utilizes an elevated work stand or other component to perform work in a work space, and then leaves the work stand to egress the work space and thereby passing under the elevated rail <NUM>.

<FIG> depicts a technician <NUM> at a fabrication system <NUM> that includes PBP forming stations <NUM> for semicircular preforms <NUM> in an illustrative embodiment. The PBP forming stations <NUM> form half-circles in this embodiment. However, in further embodiments the PBP forming stations <NUM> may form any suitable arcuate portions. In this embodiment, the PBP forming stations <NUM> surround a work space <NUM>, in which a technician <NUM> is disposed. The technician <NUM> may perform ingress and/or egress into the work space <NUM> via access pathways <NUM>. Note that a rail system is omitted in <FIG> for the sake of simplicity and clarity. However, the rail system may be elevated to enable the technician <NUM> to pass beneath it, or the technician <NUM> may be provided with a means of elevating over the rail system to egress above it. In still further embodiments, a portion of the rail system is hinged to enable pass through egress and ingress.

In the following examples, additional processes, systems, and methods are described in the context of a fabrication system for curved composite parts.

<FIG> is a block diagram of a fabrication system <NUM> for a curved preform in an illustrative embodiment. In this embodiment, fabrication system <NUM> includes rail system <NUM>, which includes an outer concentric circle <NUM> and an inner concentric circle <NUM> of track <NUM>. Tracks <NUM> are held in place by supports <NUM>, and spurs <NUM> include junctions <NUM> that couple the track <NUM> in the inner concentric circle <NUM> to track <NUM> in the outer concentric circle <NUM>. Lamination stations <NUM> lay up plies <NUM> of fiber reinforced material onto carriers <NUM>, although in further embodiments only one lamination station <NUM> is utilized to service the entire fabrication system <NUM>. Carriers <NUM> holding plies <NUM> travel through the rail system <NUM>, and reach PBP stations <NUM>. If the PBP stations <NUM> already have preforms <NUM>, then the plies <NUM> are applied to the preforms <NUM>. Alternatively, the plies are applied directly to the mandrels <NUM> of PBP stations <NUM>. The carriers <NUM> may return to cleaning station <NUM> for cleaning and residue removal, for repair, and/or for replacement before advancing back to lamination stations <NUM>.

<FIG> further depicts a controller <NUM> that controls operations of the rail system <NUM>, lamination stations <NUM>, and/or PBP stations <NUM> in accordance with sensor input, NC programs, a timed schedule and/or other factors. In one embodiment, controller <NUM> is implemented as custom circuitry, as a hardware processor executing programmed instructions stored in memory, or some combination thereof.

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>, 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 <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 invention 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 invention 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>, 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 <NUM>).

Claim 1:
A method (<NUM>) for fabricating a curved preform (<NUM>) of fiber reinforced material (<NUM>), the method comprising:
laying up (<NUM>) multiple plies (<NUM>) onto a carrier (<NUM>) of flexible material at a lamination station (<NUM>);
loading (<NUM>) the carrier (<NUM>) onto a rail system (<NUM>);
routing (<NUM>) the carrier (<NUM>) to a particular Ply-By-Ply, PBP, forming station (<NUM>) at the rail system (<NUM>) based on a characteristic of at least one ply (<NUM>) carried by the carrier (<NUM>);
separating (<NUM>) the at least one ply (<NUM>) from the carrier (<NUM>);
making (<NUM>) the at least one ply (<NUM>) into the curved preform (<NUM>) via the particular PBP forming station (<NUM>); and
routing (<NUM>) the carrier (<NUM>) to different ones of PBP forming stations (<NUM>) at the rail system (<NUM>) based on the characteristic of at least one ply (<NUM>) carried by the carrier (<NUM>).