Patent Description:
Prior to autoclave processing, composite components are enclosed in vacuum bag for the duration of a cure cycle. Vacuum bagging processes for large and/or complex composite sections, such as that of a fuselage or a wing, remain cumbersome manual processes, and vacuum bags that cover large-scale preforms may experience undesirable stretching, rips or tears (e.g., during application, prior to autoclave processing or during autoclave processing). A seal failure, rip, or tear introduces the possibility of compromised performance of the vacuum bag, which may result in a need for reworking or rejecting a resulting part. To address concerns related to a seal failure, ripping, and/or tearing, often "double bagging" and a variety of pressure checks are involved, which may further increases cycle time, material costs, and associated labor. All of these factors result in an undesirable increase in the overall cost of the composite component.

The abstract to <CIT> states: "A method and an apparatus for manufacturing a panel, the panel comprising a composite skin and at least one composite stiffener, the method comprising: positioning first and second mandrels on opposite sides of the stiffener; positioning first and second compaction tools on opposite sides of the skin; and compacting the skin between the first and second compaction tools by moving one or both of the compaction tools, wherein the movement of the compaction tool(s) causes the first and second mandrels to move towards the stiffener along inclined paths so as to compact the stiffener between the mandrels.

The abstract of <CIT> states: "An object is to provide a device and method for manufacturing a fiber-reinforced plastic molded article, whereby two members can be accurately positioned with respect to each other upon integral molding of the members via a VaRTM method. A device for manufacturing a fiber-reinforced plastic molded article comprises a skin mold in which a skin, which is a cured fiber-reinforced composite member, is mounted; a stringer mold that is configured to accommodate a stringer, which is a fabric to be joined to the skin; and a folded plate that is configured to accommodate the stringer mold and includes a positioning portion for positioning with respect to a positioning portion provided on the skin.

The abstract of <CIT> states:"A method is specified for consolidating a fiber composite structure with at least one thermoplastic and / or thermoelastic polymer, comprising arranging the fiber composite structure between a plate-shaped base and a plate-shaped cover , wherein the cover is sealed against the base displaceably with respect to the base by a sealing element, generating a negative pressure in the space between the base and the Cover so that the ambient pressure presses the cover against the base and the fiber composite structure between the cover and the base is pressed and heating of the fiber composite structure by means of electromagnetic radiation, preferably at least up to the range of the melting temperature of the at least one thermoplastic and / or thermoelastic polymer.

The method further comprises the steps: bringing about a bend in the cover, so that the cover, optionally with additional lowering of the cover, the surface of the fiber composite structure touches in a section; and further bending and / or lowering of the cover until the cover touches the entire surface of the fiber composite structure and the fiber composite structure is between the cover and the base is pressed.

The abstract of <CIT> states: Composite sections for aircraft fuselages and methods and systems for manufacturing such sections are disclosed herein. A composite section configured in accordance with one embodiment of the invention 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 of the invention 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.

The abstract of <CIT> states: A method of preparing a stringer and panel lay-up comprising the steps of providing a stringer preform, a panel preform, a filler and a mould. The mould is adapted to define an inner surface of a stringer. The method further comprises the steps of arranging the stringer preform to contact the mould, placing filler material between the mould surface and stringer preform, and bringing the reinforcement material into contact with the panel preform. The shape of the mould is configured to control filler placement and/or filler shape and/or filler volume.

Embodiments described herein provide caul plates that themselves form a vacuum seal with a mandrel in order to apply consolidation pressure while hardening a preform for a composite part. By utilizing the caul plate itself in a role normally reserved for vacuum bags, vacuum bags themselves can be foregone. Thus, methods and apparatus described herein advantageously reduce the amount of labor and material involved in the hardening process. The methods include applying a preform to a mandrel, covering the preform with a caul plate, sealing the caul plate to the mandrel, pushing the caul plate toward the preform and the mandrel and hardening the preform into a composite part while the caul plate is held against the preform.

In one aspect, an apparatus for hardening a preform of fiber reinforced material may include a mandrel, a caul plate which defines a surface of a preform, and where the caul plate may include a rigid material and seals disposed between the mandrel and the caul plate. In an additional aspect, an apparatus for consolidating a preform of fiber reinforced material may include a sealed chamber with a mandrel and a caul plate and a circumferential seal between the mandrel and the caul plate.

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. It is noted that the term 'mandrel' as used in the application refers to a mandrel upon which parts, for example aircraft parts, can be positioned. The term mandrel is thus meant as a surface or structure upon which parts and/or materials and/or layers of material and/or combinations thereof may be positioned. For the purpose of this application, the word 'mandrel' is considered interchangeable with the word 'tool' as used in the claims. It is noted that the term 'caul plate' is a tool that at least partially conforms to the shape of workpiece to be cured and is used in curing. The term 'caul plate' encompasses tools that are capable of use in such applications, notwithstanding the fact that in some embodiments according to the disclosure differences are mentioned with regard to known caul plates that are used in conjunction with vacuum bags as disclosed above.

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 caul plates and mandrels described herein are utilized to fabricate composite parts. Composite parts, such as Carbon Fiber Reinforced Polymer (CFRP) parts, are initially laid-up in multiple layers of carbon fiber reinforced material 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> depicts an aircraft is in which an illustrative embodiment may be implemented. Aircraft <NUM> is an example of an aircraft which can be formed with caul plate <NUM>, <NUM>-<NUM> of <FIG> and <FIG>, respectively. Aircraft <NUM> is an example of an aircraft <NUM> which is formed of in a half barrel shape as half barrel sections <NUM> of fuselage <NUM>.

In this illustrative example, aircraft <NUM> has wing <NUM> and wing <NUM> attached to body <NUM>. Aircraft <NUM> includes engine <NUM> attached to wing <NUM> and engine <NUM> attached to wing <NUM>.

Body <NUM> has tail section <NUM>. Horizontal stabilizer <NUM>, horizontal stabilizer <NUM>, and vertical stabilizer <NUM> are attached to tail section <NUM> of body <NUM>.

Fuselage <NUM> is fabricated from half barrel sections <NUM> with an upper half barrel section <NUM> joined to a lower half barrel section <NUM> to form a full barrel section <NUM> (e.g., <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>). The full barrel sections are joined serially to form fuselage <NUM>.

Wing <NUM> and <NUM> are formed of wing panels <NUM> comprising upper wing panel <NUM> and a lower wing panel <NUM> joined together. Section cut <NUM> is a cut-through of wing panel <NUM> and prior to being hardened corresponds to preform <NUM>, <NUM>-<NUM> (<FIG>). Section cut <NUM> is orientated chord wise roughly perpendicular to stringer <NUM>.

Section cut <NUM> is a cut-through composite panel <NUM> and prior to being hardened corresponds to preform <NUM>, <NUM>-<NUM> (<FIG>). Section cut <NUM> is orientated longitudinally through a contour <NUM>-<NUM> along a stringer.

<FIG> is a block diagram of an assembly system <NUM> that directly vacuum seals a caul plate <NUM> to a mandrel <NUM> (e.g., a layup mandrel) in an illustrative embodiment. The caul plate <NUM> is made from a rigid material <NUM>, such as metal, composite material, etc. The caul plate <NUM> remains rigid against a preform <NUM> at hardening temperatures and compression forces. In this embodiment, the caul plate <NUM> defines a mold line <NUM> such as an Outer Mold Line (OML) <NUM> for the preform <NUM>, and the mandrel <NUM> forms an Inner Mold Line (IML) <NUM> for the preform <NUM>. In some examples, a release film <NUM> is located between mandrel <NUM> and the preform <NUM>. Release film <NUM> is disposed at the mandrel <NUM> to facilitate demolding after hardening in an autoclave <NUM> has been performed. In some examples, a breather treatment <NUM> facilitates hardening processes by enabling trapped gas to exit the preform <NUM> and to facilitate evacuated gas distribution across the preform during hardening.

In this embodiment, the mandrel <NUM> includes a rigid body <NUM>-<NUM> that forms a half barrel shape, which appears rectangular from this cross-sectional view point (i.e., wherein one half of the half barrel is shown). In this embodiment, the mandrel <NUM> defines an IML <NUM> for the preform <NUM>. The mandrel <NUM> includes a layup surface <NUM> that defines a contour <NUM>-<NUM> for a preform <NUM> comprising multiple layers <NUM> of fibers <NUM> and resin <NUM>. The mandrel <NUM> further includes an indexing feature <NUM> that mates with an indexing feature <NUM> of a strongback <NUM> that transports the caul plate <NUM> to the mandrel <NUM>. This enables a location of the caul plate <NUM> relative to the mandrel <NUM> to be precisely enforced each time a caul plate <NUM> is placed at the mandrel <NUM>.

The mandrel <NUM> further includes vacuum system <NUM>. Vacuum system <NUM> controllably or otherwise applies vacuum to vacuum holes <NUM> via vacuum line <NUM>, which acts as a type of manifold distributor of vacuum to selected locations of the mandrel <NUM>. Vacuum holes <NUM> are disposed at the mandrel <NUM>, and apply vacuum beyond the layup surface <NUM>. That is, vacuum holes <NUM> directly apply vacuum to sealed chamber <NUM> including locations <NUM> at the caul plate <NUM>. Vacuum system <NUM> evacuates air from a sealed chamber <NUM> bound by caul plate <NUM>, seal <NUM> and mandrel <NUM>. Evacuating sealed chamber <NUM> along with atmospheric pressure outside of the caul plate <NUM>, seal <NUM> and mandrel <NUM> enclosure, results in pushing the caul plate <NUM> towards the mandrel <NUM> and consolidating preform <NUM>. To reiterate, by reducing pressure under the caul plate <NUM> to less than the atmospheric pressure of the autoclave, the caul plate <NUM> is pushed down via atmospheric pressure onto the mandrel <NUM>. In a further embodiment, a vacuum is introduced into the sealed chamber <NUM> through the caul plate <NUM> instead of, or in addition to, through the mandrel <NUM> and/or through the seal <NUM> and seal <NUM>.

Seals <NUM> and <NUM> are disposed between the mandrel <NUM> and the caul plate <NUM>, along a periphery of an intersection <NUM> between the mandrel <NUM> and the caul plate <NUM>. In this embodiment, the seals <NUM> and <NUM> comprise a first circumferential seal <NUM>, and a second circumferential seal <NUM> that is disposed entirely within the first circumferential seal <NUM>. However, in further embodiments a triple seal or even more seals may be implemented, and each seal is pressure tested to ensure that it forms a sealed chamber <NUM>. The seal <NUM> and seal <NUM> seal off a chamber <NUM> there between.

Multiple seals provide a fall back of redundant seals <NUM> and <NUM> in case one of the seals fails. The remaining seal <NUM> or <NUM> will help to maintain the vacuum in sealed chamber <NUM> and prevent the preform from being exposed to atmospheric pressure within sealed chamber <NUM> during processing. The circumferential seals <NUM> and <NUM> run along the entire circumference of the caul plate <NUM>, but are shown at discrete cross-sectional locations in <FIG> for the sake of clarity. These components enable the caul plate <NUM> to be circumferentially sealed to the mandrel <NUM>. The seals <NUM> and <NUM> can be implemented as expendable or reusable components. Hence, the boxes referring to seal <NUM> both represent a first seal <NUM>, and the boxes referring to seal <NUM> both represent a second seal <NUM> that is distinct from the first seal <NUM>. In some embodiments a third seal <NUM>, not shown in <FIG>, may be included. Some intermediary materials and layers between caul plate <NUM> and mandrel <NUM>, such as breather treatments, release films, etc., are not illustrated in <FIG> for the sake of ensuring clarity.

<FIG> further depicts one or more of bladders <NUM>, which are placed within stringer preforms <NUM> to provide inflation pressure to resist crushing during hardening while the caul plate <NUM> presses against the preform <NUM>. The interior <NUM>-<NUM> of bladders <NUM> are opened to atmospheric pressure <NUM> which is the pressure inside or outside of the autoclave <NUM>. When the bladders <NUM> are open to the atmospheric pressure <NUM> it inflates the bladder <NUM> when sealed chamber <NUM> is evacuated. That is, the bladders <NUM> operate as internal tooling that maintains structural support for stringer preforms <NUM> during hardening. Specifically, the bladders <NUM> resist crushing forces applied to the stringer preforms <NUM> during processing, which enables the stringer preforms <NUM> to retain their shape. Bladders <NUM> include inflation ports <NUM> to pressurize and shape one or more portions of the stringer preform <NUM>. Bladders <NUM> are disposed between the caul plate <NUM> and the mandrel <NUM>, and the caul plate <NUM> includes openings disposed at inflation ports <NUM> for the bladders <NUM>. Inflation port <NUM> aligns with opening <NUM> at the caul plate <NUM>. The inflation ports <NUM> are fastened through openings in the caul plate <NUM>. A banjo bolt <NUM> seals the caul plate <NUM> to the bladder <NUM>, and provides a passageway for air to enter the bladder <NUM> through the caul plate <NUM>. The seal <NUM>-<NUM> prevents air from leaking/escaping via opening <NUM>.

Further, <FIG> is a cross-sectional view through a longitudinal length of a trough <NUM> of mandrel <NUM>. The mandrel <NUM> includes trough <NUM> holding stringer preform <NUM> enveloping bladder <NUM> and located under preform <NUM> and mandrel <NUM>. A cross-section <NUM>, shown in <FIG> between troughs <NUM>, would have the same cross-section components as shown in <FIG> from strongback <NUM> to mandrel <NUM>, with the exception of trough <NUM> and its content including the stringer preform <NUM> and enveloped bladder <NUM>. This cross-section is located between troughs <NUM> and is an embodiment illustrated in <FIG>.

An autoclave <NUM>, (of which only a portion is shown) receives the mandrel <NUM>, and applies heat and pressure to harden preform <NUM> into a composite part <NUM>. After hardening has been completed, the caul plate <NUM> is removed. Indexing features and other components may be added to the composite part <NUM>, and/or a manufacturing excess thereof. The composite part <NUM> is demolded from the mandrel <NUM>, and the mandrel <NUM> and the caul plate <NUM> are re-used to fabricate another composite part <NUM>. In further embodiments, the mandrel <NUM> and the caul plate <NUM> are advanced in pulses or continuously through the various stations described herein.

<FIG> is a block diagram of an assembly system or apparatus <NUM>-<NUM> that directly vacuum seals a caul plate <NUM>-<NUM> to a mandrel <NUM>-<NUM>, such as a layup mandrel, in an illustrative embodiment. The caul plate <NUM>-<NUM> is made from a rigid material <NUM>-<NUM>, such as metal, composite material, etc. The caul plate <NUM>-<NUM> remains rigid against a preform <NUM>-<NUM> at hardening temperatures and compression forces. In this embodiment, the caul plate <NUM>-<NUM> defines a mold line <NUM>-<NUM> such as an Inner Mold Line (IML) <NUM> for the preform <NUM>-<NUM>, and the mandrel <NUM>-<NUM> forms an Outer Mold Line (OML) <NUM> for the preform <NUM>-<NUM>. In some examples, release film <NUM> is located between mandrel <NUM>-<NUM> and the preform <NUM>-<NUM>. Release film <NUM> is disposed at the mandrel <NUM>-<NUM> to facilitate demolding after hardening has been performed. In some examples, a breather treatment <NUM> facilitates hardening processes by enabling trapped gas to exit the preform <NUM>-<NUM> and to facilitate evacuated gas distribution across the preform during hardening.

In this embodiment, the mandrel <NUM>-<NUM> includes a rigid body <NUM>-<NUM> that forms a half cylindrical shape complementary to a half barrel section <NUM> of <FIG>. When two half barrel sections <NUM> are joined to form a full barrel section <NUM>. The mandrel <NUM>-<NUM> appears rectangular in the <FIG> cross-sectional view. In this embodiment, the mandrel <NUM>-<NUM> defines an OML <NUM> for the preform <NUM>-<NUM>. The mandrel <NUM>-<NUM> includes a layup surface <NUM> that defines a contour <NUM>-<NUM> for a preform <NUM>-<NUM> comprising multiple layers <NUM> of fibers <NUM> and resin <NUM>. The mandrel <NUM>-<NUM> further includes an indexing feature <NUM> that mates with an indexing feature <NUM> of a strongback <NUM> that transports the caul plate <NUM>-<NUM> to the mandrel <NUM>-<NUM>. This enables a location of the caul plate <NUM>-<NUM> relative to the mandrel <NUM>-<NUM> to be precisely enforced each time a caul plate <NUM>-<NUM> is placed at the mandrel <NUM>-<NUM>.

An embodiment has a vacuum system <NUM>-<NUM> evacuating sealed chamber <NUM>-<NUM> through the seal <NUM> and seal <NUM>. Vacuum system <NUM>-<NUM> controllably or otherwise applies vacuum to vacuum holes <NUM>-<NUM> and <NUM>-<NUM> via vacuum lines <NUM>-<NUM> and <NUM>-<NUM>, respectively. Vacuum holes <NUM>-<NUM> are disposed through seal <NUM> and <NUM> and/or through caul plate <NUM>-<NUM>, and apply vacuum to sealed chamber <NUM>. That is, vacuum holes <NUM>-<NUM> and/or <NUM>-<NUM> directly apply vacuum to sealed chamber <NUM> including locations <NUM>-<NUM> at the caul plate <NUM>-<NUM>. Vacuum system <NUM>-<NUM> evacuates air from a sealed chamber <NUM> that directly borders the caul plate <NUM>-<NUM> and the mandrel <NUM>-<NUM>. Evacuating sealed chamber <NUM> along with atmospheric pressure outside of the caul plate <NUM>-<NUM>, seal <NUM> and mandrel <NUM>-<NUM> enclosure, results in pushing the caul plate <NUM>-<NUM> towards the mandrel <NUM>-<NUM> and consolidating preform <NUM>-<NUM>. To reiterate, by reducing pressure under the caul plate <NUM>-<NUM> to less than the atmospheric pressure of the autoclave, the caul plate <NUM>-<NUM> is pushed down via atmospheric pressure onto the mandrel <NUM>-<NUM>. In a further embodiment, a vacuum is introduced into the sealed chamber <NUM> through the caul plate <NUM>-<NUM> instead of, or in addition to, through the mandrel <NUM>-<NUM> as shown in <FIG> and/or through the seal <NUM> and seal <NUM>.

Seals <NUM> and <NUM> are disposed between the mandrel <NUM>-<NUM> and the caul plate <NUM>-<NUM>, along a periphery of an intersection <NUM> between the mandrel <NUM>-<NUM> and the caul plate <NUM>-<NUM>. In this embodiment, the seals <NUM> and <NUM> comprise a first circumferential seal <NUM>, and a second circumferential seal <NUM> that is disposed entirely within the first circumferential seal <NUM>. However, in further embodiments a triple seal or even more seals may be implemented, and each seal is pressure tested to ensure that it forms a sealed chamber <NUM>. The seal <NUM> and seal <NUM> seal off a chamber <NUM>-<NUM> there between. Multiple seals provide a fall back of redundant seals <NUM> and <NUM> in case one of the seals fails. The remaining seal <NUM> or <NUM> will help to maintain the vacuum in sealed chamber <NUM> and prevent the preform from being exposed to atmospheric pressure within sealed chamber <NUM> during processing. The circumferential seals <NUM> and <NUM> run along the entire circumference of the caul plate <NUM>-<NUM>, but are shown at discrete cross-sectional locations in <FIG> for the sake of clarity. These components enable the caul plate <NUM>-<NUM> to be circumferentially sealed to the mandrel <NUM>-<NUM>. The seals <NUM> and <NUM> can be implemented as expendable or reusable components. Hence, the boxes referring to seal <NUM> both represent a first seal <NUM>, and the boxes referring to seal <NUM> both represent a second seal <NUM> that is distinct from the first seal <NUM>. In some embodiments a third seal <NUM>, not shown in <FIG>, may be included. Some intermediary materials and layers between caul plate <NUM> and mandrel <NUM>, such as breather treatments, release films, etc., are not illustrated in this <FIG> for the sake of ensuring clarity.

<FIG> further depicts one or more of bladders <NUM>-<NUM>, which are placed within stringer preforms <NUM> to provide inflation pressure to resist crushing during hardening while the caul plate <NUM>-<NUM> presses against the preform <NUM>-<NUM>. The interior <NUM>-<NUM> of bladders <NUM>-<NUM> are opened to atmospheric pressure <NUM> which is the pressure inside or outside of the autoclave <NUM>. Bladders <NUM>-<NUM> are opened to atmospheric pressure <NUM> which is the pressure inside or outside of the autoclave <NUM>. When the bladders <NUM>-<NUM> are open to the atmospheric pressure <NUM>, the bladders <NUM>-<NUM> inflate when sealed chamber <NUM> is evacuated. That is, the bladders <NUM>-<NUM> operate as internal tooling that maintains structural support for stringer preforms <NUM> during hardening. Specifically, the bladders <NUM>-<NUM> resist crushing forces applied to the stringer preforms <NUM> during processing, which enables the stringer preforms <NUM> to retain their shape. Bladders <NUM>-<NUM> include inflation ports <NUM> to pressurize and shape one or more portions of the stringer preform <NUM>-<NUM> during hardening. Bladders <NUM>-<NUM> are disposed between the caul plate <NUM>-<NUM> and the mandrel <NUM>-<NUM>. In one embodiment shown in <FIG>, inflation port <NUM>-<NUM> passes through seal <NUM> and <NUM> and provides a passageway for air to enter the bladder <NUM>.

Further, <FIG> is a cross-sectional view through a longitudinal length of a trough <NUM>-<NUM> of caul plate <NUM>-<NUM>. The caul plate <NUM>-<NUM> includes a trough <NUM>-<NUM> holding the stringer preform <NUM> enveloping the bladder <NUM>-<NUM> and located under the preform <NUM>-<NUM> and mandrel <NUM>-<NUM>. A cross-section <NUM>-<NUM>, shown in <FIG> between troughs <NUM>-<NUM>, would have the same cross-section components as shown in <FIG> from strongback <NUM> to mandrel <NUM>-<NUM>, with the exception of trough <NUM>-<NUM> and its content including the stringer preform <NUM> and enveloped bladder <NUM>-<NUM>. This cross-section <NUM>-<NUM> is located between troughs <NUM>-<NUM> and is an embodiment illustrated in <FIG>. An autoclave <NUM> (shown in greater detail at autoclave <NUM> in <FIG>) receives the mandrel <NUM>-<NUM>, preform <NUM>-<NUM> and caul plate <NUM>-<NUM>, and applies heat and pressure to harden preform <NUM>-<NUM> into a composite part <NUM>. After hardening has been completed, the caul plate <NUM>-<NUM> is removed. Indexing features and other components may be added to the composite part <NUM>, and/or a manufacturing excess thereof. The composite part <NUM> is demolded from the mandrel <NUM>-<NUM>, and the mandrel <NUM>-<NUM> and the caul plate <NUM>-<NUM> are re-used to fabricate another composite part <NUM>. In further embodiments, the mandrel <NUM>-<NUM> and the caul plate <NUM>-<NUM> are advanced in pulses or continuously through the various stations described herein.

<FIG> corresponds with view arrows 2B of <FIG>, and illustrates a section cut view of the various components discussed above. As shown in <FIG>, the bladder <NUM> is placed within a stringer preform <NUM> in trough <NUM>, and positively pressurized when the caul plate <NUM> is sealed to mandrel <NUM> and sealed chamber <NUM> is evacuated around the stringer preform <NUM>. The bladder <NUM> helps to maintain structural support for the stringer preform <NUM>, which prevents the stringer preform <NUM> from altering shape during the hardening process. In this embodiment, the mandrel <NUM> defines an IML <NUM> and the caul plate <NUM> defines the OML <NUM> for the preform <NUM>. This embodiment facilitates placement of the stringer preforms <NUM> and bladders <NUM> upon the mandrel <NUM> and then preform <NUM> is laid upon the stringer preforms <NUM>, bladder <NUM> and mandrel <NUM>.

This embodiment supports IML <NUM> tooling for a half barrel section <NUM>.

<FIG> corresponds with view arrows 2C of <FIG>, and illustrates a section cut view of the various components discussed above. As shown in <FIG>, the bladder <NUM>-<NUM> is placed within a stringer preform <NUM> in trough <NUM>-<NUM>, and positively pressurized when the caul plate <NUM>-<NUM> is sealed to mandrel <NUM>-<NUM> and sealed chamber <NUM> is evacuated around the stringer preform <NUM> and preform <NUM>-<NUM>. The bladder <NUM>-<NUM> helps to maintain structural support for the stringer preform <NUM>, which prevents the stringer preform <NUM> from altering shape during the hardening process. In this embodiment, the mandrel <NUM>-<NUM> defines an OML <NUM> and the caul plate <NUM>-<NUM> defines the IML <NUM> for the preform <NUM>-<NUM>. An embodiment facilitates layup of preform <NUM>-<NUM> upon mandrel <NUM>-<NUM> and then placement of the stringer preforms <NUM> and bladders <NUM> upon the mandrel <NUM> and then caul plate sealed to the mandrel <NUM>-<NUM> to complete the assembly prepared for hardening in an autoclave <NUM>. This embodiment supports OML <NUM> tooling for a half barrel section <NUM>.

<FIG> illustrates a caul plate <NUM> for a wing panel preform <NUM> in an illustrative embodiment. Wing panel preform <NUM> is laid up upon mandrel <NUM>. Then blade stringers <NUM> are placed upon preform <NUM>. Then support tooling <NUM> and <NUM>-<NUM> is placed upon blade stringers <NUM> and upon preform <NUM>. A caul plate <NUM>, having a custom shape to provide an IML <NUM>-<NUM>, is overlaid atop blade stringers <NUM> and support tooling <NUM> and <NUM>-<NUM> such as stringer mandrels. Seals <NUM> and <NUM> are disposed at the periphery of the caul plate <NUM> and the mandrel <NUM> and provide seal redundancy. As shown in <FIG>, vacuum system <NUM> controllably or otherwise applies vacuum to vacuum holes <NUM> via vacuum line <NUM>, which acts as a type of manifold distributor of vacuum to selected locations of the mandrel <NUM>. Vacuum holes <NUM> are disposed at the mandrel <NUM>-<NUM>, and apply vacuum beyond the layup surface <NUM>. That is, vacuum holes <NUM> directly apply vacuum to sealed chamber <NUM> including locations <NUM> at the caul plate <NUM>. As shown in <FIG>, an embodiment has a mandrel <NUM> which includes passageway <NUM> through seals <NUM> and <NUM>, which controllably or otherwise applies vacuum to evacuate sealed chamber <NUM>-<NUM> formed of caul plate <NUM>, seals <NUM>, <NUM> and mandrel <NUM> facilitating atmospheric pressure outside of sealed chamber <NUM>-<NUM> pushing the caul plate <NUM> towards the mandrel <NUM> thus consolidating wing panel preform <NUM>. Preform <NUM> is laid up upon layup surface <NUM>-<NUM> on mandrel <NUM>. The caul plate <NUM> therefore consolidates stringers <NUM> as well as wing panel preform <NUM>. In this embodiment, the mandrel <NUM> defines an OML <NUM> and the caul plate <NUM> defines the IML <NUM> for the wing panel preform <NUM>. The wing panel preform <NUM> corresponds to cross-section <NUM> of wing panel <NUM> when wing panel preform <NUM> is hardened. Therefore, the mandrel <NUM> for <FIG> provides the OML <NUM>-<NUM> with the caul plate <NUM> providing the IML <NUM>-<NUM>.

<FIG> illustrates a caul plate <NUM>-<NUM> for a wing panel preform <NUM>-<NUM> in an illustrative embodiment. A caul plate <NUM>-<NUM> having a custom shape to provide an OML <NUM>-<NUM> is overlaid atop preform <NUM>-<NUM>. Blade stringers <NUM> and support tooling <NUM>-<NUM>, <NUM>-<NUM>, such as stringer mandrels, are placed against mandrel <NUM>-<NUM>. In one embodiment, preform <NUM>-<NUM> is then laid upon stringers <NUM> and support tooling <NUM>-<NUM>. Caul plate <NUM>-<NUM> is then placed upon preform <NUM>-<NUM>. Seals <NUM> and <NUM> are disposed at the periphery of the caul plate <NUM>-<NUM> and the mandrel <NUM>-<NUM> to provide seal redundancy. In <FIG>, vacuum system <NUM>-<NUM> controllably or otherwise applies vacuum to vacuum holes <NUM> via vacuum line <NUM>, which acts as a type of manifold distributor of vacuum to selected locations of the caul plate <NUM>-<NUM>. Vacuum holes <NUM>-<NUM> are disposed at the caul plate <NUM>-<NUM>, and apply vacuum beyond the layup surface <NUM>. That is, vacuum holes <NUM> directly apply vacuum to sealed chamber <NUM>. As shown in <FIG>, an embodiment has a mandrel <NUM>-<NUM> and caul plate <NUM>-<NUM> with a passageway <NUM> through seals <NUM> and <NUM>. A vacuum travels through passageway <NUM> from vacuum system <NUM>-<NUM> to evacuate sealed chamber <NUM>-<NUM> formed by caul plate <NUM>-<NUM>, seals <NUM>, <NUM> and mandrel <NUM>-<NUM>. The caul plate <NUM>-<NUM> slips relative to mandrel <NUM>-<NUM> when atmospheric pressure outside of sealed chamber <NUM>-<NUM> pushes the caul plate <NUM>-<NUM> towards the mandrel <NUM>-<NUM>, thus consolidating wing panel preform <NUM>-<NUM>. The caul plate <NUM>-<NUM> therefore consolidates blade stringers <NUM> as well as wing panel preform <NUM>-<NUM>. In this embodiment, the mandrel <NUM>-<NUM> defines an IML <NUM>-<NUM> and the caul plate <NUM>-<NUM> defines the OML <NUM>-<NUM> for the wing panel preform <NUM>-<NUM>. Preform <NUM>-<NUM> is laid up upon layup surface <NUM>-<NUM> created by blade stringers <NUM>, support tooling <NUM>-<NUM>, and mandrel <NUM>-<NUM>. The wing panel preform <NUM>-<NUM> corresponds to cross-section <NUM> of wing panel <NUM> when wing panel preform <NUM>-<NUM> is hardened.

Therefore, the mandrel <NUM>-<NUM> for <FIG> provides the IML <NUM>-<NUM> with the caul plate <NUM>-<NUM> providing the OML <NUM>-<NUM>.

<FIG> illustrates a process direction <NUM>-<NUM> for a caul plate <NUM> in an illustrative embodiment. Caul plate <NUM> comprises caul plate <NUM> and <NUM>-<NUM> as well as caul plate <NUM>, <NUM>-<NUM>. Mandrel <NUM> comprises mandrel <NUM>, <NUM>-<NUM> as well as mandrel <NUM>, <NUM>-<NUM>. As shown in <FIG>, preform <NUM> is processed in autoclave <NUM> on mandrel <NUM> and with caul plate <NUM> positioned over preform <NUM>. After autoclave processing, caul plate <NUM> is separated from composite part <NUM> and mandrel <NUM>.

Caul plate <NUM> is then cleaned and reconditioned at a cleaning station <NUM>-<NUM> and reconditioning station <NUM> located outside of the clean room environment <NUM>-<NUM>. In one embodiment, this comprises returning the caul plate <NUM> to a condition where it is capable of installation over a preform <NUM> and onto a layup mandrel <NUM> at caul installation station <NUM>. Preform <NUM> comprises preform <NUM>, <NUM>-<NUM>, and preform <NUM>, <NUM>-<NUM>. The caul plate <NUM> is then placed onto the layup mandrel <NUM> and preform <NUM> at a caul installation station <NUM>. In one embodiment, the layup mandrel <NUM> defines a shape for a preform <NUM> that will be hardened into a wing panel <NUM> of wing <NUM>, <NUM>. In another embodiment, the layup mandrel <NUM> defines a shape for a preform <NUM> that will be hardened into the half barrel sections <NUM> of the fuselage <NUM>.

In some embodiments, cleaning station <NUM>-<NUM>, and reconditioning station <NUM> and/or caul installation station <NUM> are disposed at a mezzanine <NUM> that overlooks a factory floor <NUM>-<NUM>. This increases an amount of available space at a factory floor <NUM>-<NUM>. In another embodiment, cleaning station <NUM>-<NUM>, and reconditioning station <NUM> are disposed on the factory floor <NUM>-<NUM>. The preform <NUM> is hardened into a composite part <NUM> at an autoclave <NUM>. The caul plate <NUM>, preform <NUM>, mandrel <NUM> and composite part <NUM> are then removed from autoclave <NUM>. Then the caul plate <NUM> is separated from mandrel <NUM>. The composite part <NUM> remains on the mandrel <NUM> after the caul plate <NUM> is removed. The composite part <NUM>, after caul plate <NUM> is removed, has a manufacturing excess <NUM>-<NUM> consisting of a flash edge extending out from the composite part <NUM> and the bearing edge <NUM>-<NUM> material prior to trimming. The trimming occurs as part of the demolding process <NUM>-<NUM>. The composite part <NUM> is trimmed upon the mandrel <NUM>, <NUM>-<NUM>. The manufacturing excess <NUM>-<NUM> on composite part <NUM> is then trimmed to separate flash edge <NUM>-<NUM> from bearing edge <NUM>-<NUM>. The composite part <NUM> is then separated from mandrel <NUM> and the composite part <NUM> with bearing edge <NUM>-<NUM>. Trimmed off flash edge <NUM>-<NUM> is then discarded. The composite part <NUM> is sent onward in direction <NUM> for assembly with other parts. The caul plate <NUM> may then be lifted onto mezzanine <NUM> and returned from a non-clean room <NUM>-<NUM> to a clean room <NUM>-<NUM> after passing through at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM>. Another embodiment has the caul plate <NUM> returned from a non-clean room <NUM>-<NUM> to a clean room <NUM>-<NUM> after passing through at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> and lifted onto mezzanine <NUM>. The at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> are located on the factory floor <NUM>-<NUM> or on the mezzanine <NUM> or both. An embodiment has a portion of the mezzanine <NUM> in the clean room <NUM>-<NUM> and non-clean room <NUM>-<NUM>. Using the mezzanine <NUM> reduces the factory floor <NUM>-<NUM> foot print for the caul plate <NUM> cycle from placement at caul installation station <NUM>, separation from mandrel <NUM> through at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> to return back to caul installation station <NUM>. While an embodiment has the at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> inside clean room <NUM>-<NUM>, the illustrated embodiment has the at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> located in non-clean room <NUM>-<NUM>. In one embodiment, the caul plate <NUM> is mated to a strongback, such as. , strongback <NUM> of <FIG> and <FIG> prior to returning through the at least one cleaning station <NUM>-<NUM> and at least one reconditioning station <NUM> to return back to caul installation station <NUM>.

Further details of the operation of the assembly system <NUM> will be discussed with regard to <FIG>. Assume, for this embodiment, that the mandrel <NUM> is in a clean room (for example clean room <NUM>-<NUM>), and is ready to be used to fabricate a composite part <NUM>. Further, assume that, in some examples, a release film <NUM> has been applied to the layup surface <NUM> of the mandrel <NUM>.

<FIG> is a flowchart illustrating a method for operating an assembly system <NUM> to harden a preform <NUM> in an autoclave <NUM> of an illustrative embodiment. The steps of method <NUM> are described with reference to assembly 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. Furthermore, although the steps herein are described for fabricating half barrel sections of fuselage, they may be applied to any suitable arcuate sections of fuselage, such as full barrel sections, half barrel sections <NUM>, <NUM>, one-quarter barrel sections, or other segment sizes. In addition, the steps herein as described are capable of use in fabricating a wing panel <NUM>, <NUM>.

Step <NUM> includes applying a preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In one embodiment, applying the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM> comprises laying up tows of CFRP onto the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> via an Automated Fiber Placement (AFP) machine, a Flat Tape Layup Machine (FTLM), a Contour Tape Layup Machine (CTLM), end effector, or other device in order to form a multi-layer charge of material having a desired shape. In a further embodiment, applying the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> comprises picking up and placing a completed preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> or components of a completed preform <NUM> onto the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>.

After the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> has been applied, the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> is covered with breather treatment <NUM> that facilitate uniform evacuation within sealed chamber <NUM>, <NUM>-<NUM> and to a lesser extent degassing the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> during hardening. Furthermore, in some examples, bladders <NUM>, <NUM>-<NUM> (or other internal mandrels) are placed at desired locations to selectively support stringer preform <NUM> of the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>, such as preforms for hat stringers). The bladders <NUM>, <NUM>-<NUM> are inflated via atmospheric pressure which is typically autoclave pressure. Seals <NUM> and <NUM> are located between caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> and mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>, and may be adhesively secured into place.

Step <NUM> comprises indexing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In one embodiment, covering the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> comprises transporting the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> with a strongback <NUM>, and aligning indexing feature <NUM> at the strongback <NUM> with an indexing feature <NUM> at the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. This action indexes the strongback <NUM> to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. Since the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is transported at a precisely known position and orientation relative to the strongback <NUM>, the location of the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> relative to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> is also indexed. In another embodiment, aligning indexing feature <NUM> at the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> with an indexing feature <NUM> at the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In further embodiments, indexing comprises aligning the openings <NUM> at the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> with ports <NUM> at bladders <NUM>, <NUM>-<NUM> disposed at the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. This provides for a two-stage indexing process wherein indexing the strongback <NUM> to mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> provides for initial indexing, and indexing the ports <NUM> and openings <NUM> provide for fine indexing. Alternatively, a two-stage indexing process can include indexing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> provides for initial indexing, and indexing the ports <NUM> and openings <NUM> provide for fine indexing. That is, the openings <NUM> at the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> also facilitate indexing of the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> relative to the bladders <NUM>, <NUM>-<NUM>. Thus, in one embodiment, method <NUM> includes applying a bladder <NUM>, <NUM>-<NUM> at the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> prior to covering the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> with the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>, and aligning an opening <NUM> in the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> with an inflation port <NUM> for the bladder <NUM>, <NUM> to facilitate circumferential and/or fore/aft alignment.

In step <NUM>, the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> is covered with the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>. This comprises lowering the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> into place atop the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>.

In step <NUM>, the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is sealed to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In one embodiment, sealing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> comprises applying a first circumferential seal <NUM>, and applying a second circumferential seal <NUM> that is disposed entirely within the first circumferential seal <NUM>. In a further embodiment, sealing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> comprises applying a third circumferential seal <NUM> that is disposed entirely within the second circumferential seal <NUM>. Step <NUM> further includes placing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> against the seals <NUM> and <NUM>, and may involve applying adhesives or other compounds that ensure an airtight bond between the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> and the seals <NUM> and <NUM>. Further, the volume between he first circumferential seal <NUM> and the second circumferential seal <NUM> may be subdivided into quadrants (as will be further discussed in <FIG>) thus providing a further level of seal redundancy. Banjo bolts <NUM>, which include threading that is complementary to threading at each inflation port <NUM>, are secured to/installed at inflation ports <NUM> of the bladders <NUM>. This serves to seal the openings <NUM> of the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> along with other seals if needed, thereby preventing air from escaping the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> via the openings <NUM>.

In short, step <NUM> may comprise sealing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to one or more bladders via banjo bolts <NUM>, and inflating the bladders <NUM>, <NUM>-<NUM> while hardening the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. Thus, in at least one embodiment, sealing the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to the bladder <NUM>, <NUM>-<NUM> is performed by screwing a banjo bolt <NUM> into the inflation port <NUM>.

In step <NUM>, vacuum system <NUM>, <NUM>-<NUM> evacuates air from sealed chamber <NUM>, <NUM>-<NUM> that is between the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> and the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> , thereby using atmospheric pressure to push the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> towards/against the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In one embodiment, this comprises applying a vacuum at the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> that directly pulls the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> towards the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. The vacuum at the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> controllably or otherwise applies vacuum directly to the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>. In another embodiment, the evacuation of the sealed chamber <NUM>, <NUM>-<NUM> is accomplished through seals <NUM> and <NUM> and/or through caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>. This operation holds the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> tightly against the seals <NUM> and <NUM> and also consolidates the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. In one embodiment, the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is pushed towards the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> at <NUM> MPa (<NUM> pounds per square inch) of pressure or more. The mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> is then placed into the autoclave <NUM>, which is pressurized. The autoclave <NUM> pressure inflates the bladders <NUM>, <NUM>-<NUM> via the banjo bolts <NUM>, after which the autoclave <NUM> is heated to a hardening temperature. Thus the stringer preforms <NUM> are pressurized and shaped via the inflation of bladders <NUM>, <NUM>-<NUM> during the hardening.

In step <NUM> the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> is hardened into a composite part <NUM> while the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is held against the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. That is, after the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> has been vacuumed into place and during the holding of the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> in place, hardening occurs. In one embodiment, this comprises operating the autoclave <NUM> to maintain heat and pressure, while simultaneously operating the vacuum system <NUM>, <NUM>-<NUM> at the mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> , in order to consolidate and harden the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM> while enforcing a desired shape onto the preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>.

In step <NUM>, the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is removed from the composite part <NUM>, and in step <NUM> the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is cleaned, for example via the application of chemicals and fluids in order to remove composite materials, the use of scrubbing/scouring, etc. In some examples, the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is reconditioned or repaired as needed in step <NUM>. In step <NUM>, the caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> is returned to a clean room <NUM>-<NUM>, where it may be re-used to facilitate hardening of another preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>.

Method <NUM> provides a technical benefit over prior systems and techniques because it eliminates the need to vacuum bag preforms <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>, test the vacuum bags and then place a caul plate(s) and possibly again vacuum check the vacuum bags and then place the assembly into autoclave <NUM>. Thus, prior two-step processes which required placing and sealing a vacuum bag into position, testing the vacuum bag, and then indexing and placing a caul plate, is replaced with a single-step process of placing a caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>. Method <NUM> utilizes a caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM> to perform the same role for which vacuum bags were previously relied. This reduces the amount of labor and material used pertaining to the hardening process, which beneficially enhances efficiency. For example, the need for vacuum bags and other disposable components is reduced or eliminated, which results in material and labor savings before hardening occurs.

<FIG> is a side view of a mandrel <NUM> that includes a caul plate <NUM> which operates as a vacuum bag in an illustrative embodiment. From this view, the mandrel <NUM> appears to be rectangular such as half a cylinder appears rectangular when viewed from the side, but the mandrel <NUM> forms a half barrel shape <NUM> when hardened of which only one side is presently viewed. According to <FIG>, the caul plate <NUM> covers a preform <NUM>, and the bladders <NUM>, <NUM>-<NUM> are placed within stringer preforms <NUM> at the preform <NUM>. The bladders <NUM>, <NUM>-<NUM> include ports <NUM>, which are exposed via openings <NUM> into the caul plate <NUM>. Caul plate <NUM> corresponds to caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>, <NUM>-<NUM>. Mandrel <NUM> corresponds to mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>. Preform <NUM> corresponds to preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>, <NUM>.

The mandrel <NUM> includes vacuum holes <NUM>, which directly apply vacuum to the caul plate <NUM>, pressing the caul plate <NUM> into the preform <NUM>. The caul plate <NUM>, radial seals <NUM> and mandrel <NUM> together define a vacuum chamber <NUM> that is evacuated when vacuum is applied via vacuum holes <NUM>. The vacuum holes <NUM> are located beyond a preform perimeter <NUM>, but within a perimeter <NUM> of the radial seals <NUM>. Because the caul plate <NUM> is sealed, for example, at ramp <NUM>, air does not leak out into an autoclave <NUM> during hardening of the preform <NUM> into a composite part <NUM>. Furthermore, the mandrel <NUM> includes an indexing feature <NUM> that mates with a strongback <NUM> and facilitates placement and orientation of the caul plate <NUM> upon the mandrel <NUM>. Radial seals <NUM> and bottom seal <NUM> enable the mandrel <NUM> to be sealed into place within autoclave <NUM>.

<FIG> is a cut-through view of a mandrel <NUM> that includes a caul plate <NUM> which performs the function of a vacuum bag and caul plate in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. In <FIG>, ramp <NUM> of mandrel <NUM> is visible, as is caul plate <NUM>. Circumferential seals <NUM>, <NUM>, and <NUM> are disposed at channels <NUM> (e.g., channels having a half-circle cross-section) in the mandrel <NUM> to seal the caul plate <NUM> into three unique and independent chambers <NUM>, <NUM>, and <NUM>. Chamber <NUM> corresponds to sealed chamber <NUM>, <NUM>-<NUM>. This seal redundancy of circumferential seals <NUM>, <NUM>, and <NUM> helps to prevent the preform from encountering any vacuum leaks. That is, having independent chambers <NUM>, <NUM>, and <NUM> provides a technical benefit, because it enables hardening to be successfully performed at desired caul plate <NUM> compression even if a single circumferential seals <NUM>, <NUM>, and <NUM> fails during the hardening process. Furthermore, vacuum holes <NUM> apply vacuum via vacuum lines <NUM> that pull the caul plate <NUM> into contact with the seals. An elastomeric flap <NUM> extends from the caul plate <NUM> and lays flat against the mandrel <NUM>. The elastomeric flap <NUM> may be taped, glued, or otherwise sealed to the mandrel <NUM> if desired in order to provide additional seal protection against leakage, resulting in more redundancy. In further embodiments, no ramp <NUM> is utilized, in order to ensure that the mandrel <NUM> and caul plate <NUM> remain at a constant diameter. While seal <NUM> and <NUM> are shown in <FIG>, the three seal system of circumferential seals <NUM>, <NUM>, and <NUM> along with flap <NUM> could be used.

<FIG> is a top view of a caul plate <NUM> and the mandrel <NUM> which corresponds with view arrows <NUM> of <FIG> and appears to be rectangular such as half a cylinder appears rectangular when viewed from the top. The caul plate <NUM> and the mandrel <NUM> includes peripheral chambers <NUM> and <NUM> that are subdivided into quadrants <NUM>, <NUM>, <NUM>, and <NUM> by a <NUM> seals in an illustrative embodiment. According to <FIG>, the caul plate <NUM> covers the circumferential seals <NUM>, <NUM>, and <NUM> of <FIG>, and further covers the seals <NUM>, which subdivide the circumferential seals <NUM>, <NUM>, and <NUM> into quadrants <NUM>, <NUM>, <NUM>, and <NUM>. Pressure sensors <NUM> are disposed at chambers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in each of the quadrants <NUM>, <NUM>, <NUM>, and <NUM>, and may be integrated into the caul plate <NUM> or the mandrel <NUM>. For example, in one embodiment a pressure sensor <NUM> is disposed in chambers <NUM> and <NUM> of quadrant <NUM>, chambers <NUM> and <NUM> of quadrant <NUM>, chambers <NUM> and <NUM> of quadrant <NUM>, and chambers <NUM> and <NUM> of quadrant <NUM>. Input from pressure sensors <NUM> is used to determine whether leaks exist in any of the chambers, and specifically what quadrant. Thus, seals <NUM> act as additional seals that subdivide a volume between the circumferential seals into quadrants <NUM>, <NUM>, <NUM>, and <NUM> or other segments. Vacuum holes <NUM> beneath the caul plate <NUM> are also depicted, and are used to evacuate air disposed between the caul plate <NUM> and an underlying mandrel <NUM>. The advantage of dividing into quadrants is a further level of seal redundancy. For instance, if a seal leak occurs in chamber <NUM>, it is isolated to that quadrant <NUM> and does not compromise chambers <NUM>, <NUM> or <NUM>. Without dividing into quadrants <NUM>, <NUM>, <NUM>, and <NUM> with seal <NUM>, a leak in the area of chamber <NUM> through seal <NUM> and a leak through seal <NUM> in the area of chamber <NUM> could otherwise lead to the preform <NUM> being subjected to atmospheric pressure during hardening.

<FIG> and <FIG> are views of a banjo bolt <NUM> that seals a caul plate <NUM> to a bladder <NUM> while also providing a passageway <NUM> for air to enter the bladder in an illustrative embodiment.

Bladder <NUM> corresponds to bladder <NUM>, <NUM>-<NUM>. Passageway <NUM> enables air at an autoclave pressure (P_AUTOCLAVE) to enter into the bladder <NUM>, causing the bladder <NUM> to inflate. The banjo bolt <NUM> includes head <NUM>, from which an annular seal <NUM> protrudes. The annular seal <NUM> seals the banjo bolt <NUM> to the caul plate <NUM> as the banjo bolt <NUM> is threaded into port <NUM> of the bladder <NUM>, which prevents air leaks from opening <NUM>. Seal <NUM> corresponds to seal <NUM>-<NUM>. Opening <NUM> corresponds to opening <NUM>. The banjo bolt <NUM> further includes shaft <NUM> having threading <NUM>, which is complementary to threading <NUM> at the port <NUM>. <FIG> corresponds with view arrows <NUM> of <FIG>, and provides additional detail illustrating the head <NUM>, passageway <NUM>, annular seal <NUM>, and other components of the banjo bolt <NUM> not illustrated in <FIG>. <FIG> and <FIG> are perspective views of insertion of a mandrel <NUM> into an autoclave <NUM> on a factory floor <NUM>-<NUM> in an illustrative embodiment. Mandrel <NUM> corresponds to mandrel <NUM>, <NUM>-<NUM>, <NUM>, <NUM>. As shown in <FIG>, the mandrel <NUM> forms a half barrel shape, upon which a caul plate <NUM> covers a preform (beneath the caul plate <NUM>) for hardening into a composite part. Caul plate <NUM> corresponds to caul plate <NUM>, <NUM>-<NUM>, <NUM>, <NUM>-<NUM>. Preform <NUM> corresponds to preform <NUM>, <NUM>-<NUM>, <NUM>, <NUM>. The caul plate <NUM> is held in place via a vacuum applied by the mandrel <NUM>. The mandrel <NUM> is moved into the autoclave <NUM> in <FIG>, and then sealed in place. The autoclave <NUM> is heated and pressurized, and the preform is hardened to a composite part <NUM>, which is demolded after the mandrel <NUM> is removed from the autoclave <NUM>. <FIG> and <FIG> illustrate but one autoclave arrangement out of numerous possibilities, and other arrangement for an autoclave <NUM> may be utilized with the systems and methods described herein.

In the following examples, additional processes, systems, and methods are described in the context of a caul plate that is directly vacuum sealed to a mandrel to apply consolidation forces to a preform during hardening.

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>. The airframe <NUM> includes a full barrel section <NUM> further comprising a half barrel section <NUM> and a wing assembly <NUM> further comprising a wing panel <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 hardening a preform (<NUM>, <NUM>-<NUM>) of fiber reinforced material, the method (<NUM>) comprising:
- applying (<NUM>) a preform (<NUM>, <NUM>-<NUM>) to a tool (<NUM>, <NUM>-<NUM>);
- covering (<NUM>) the preform (<NUM>, <NUM>-<NUM>) with a caul plate (<NUM>,<NUM>-<NUM>);
- sealing (<NUM>) the caul plate (<NUM>,<NUM>-<NUM>) to the tool (<NUM>, <NUM>-<NUM>);
- pushing (<NUM>) the caul plate (<NUM>,<NUM>-<NUM>) toward the preform (<NUM>, <NUM>-<NUM>) and the tool (<NUM>, <NUM>-<NUM>);
- hardening (<NUM>) the preform (<NUM>, <NUM>-<NUM>) into a composite part (<NUM>) while the caul plate (<NUM>,<NUM>-<NUM>) is held against the preform (<NUM>, <NUM>-<NUM>); and
- disposing one or more bladders (<NUM>, <NUM>-<NUM>) between the caul plate (<NUM>,<NUM>-<NUM>) and the tool (<NUM>, <NUM>-<NUM>)
- providing a two-stage indexing process comprising:
~ transporting the caul plate (<NUM>, <NUM>-<NUM>) with a strongback (<NUM>), and aligning indexing feature (<NUM>) at the strongback (<NUM>) with an indexing feature (<NUM>) at the tool (<NUM>, <NUM>-<NUM>) as initial indexing and indexing a port (<NUM>) of the bladder (<NUM>, <NUM>-<NUM>) and an opening (<NUM>) of caul plate (<NUM>, <NUM>-<NUM>) to provide for fine indexing; or
~ aligning an indexing feature (<NUM>) at the caul plate (<NUM>, <NUM>-<NUM>) with an indexing feature (<NUM>) at the tool (<NUM>, <NUM>-<NUM>) as initial indexing and indexing a port (<NUM>) of the bladder (<NUM>, <NUM>-<NUM>) and an opening (<NUM>) of caul plate (<NUM>, <NUM>-<NUM>) to provide for fine indexing.