Patent Description:
Cauls are sometimes placed on a composite part layup in preparation for vacuum bag compaction and curing in order to achieve a desired part finish and/or to evenly apply compaction pressure over part. A flexible vacuum bag is placed over the caul and is sealed around its periphery to an underlying cure tool using a sealant tape. The process of draping the vacuum bag over a caul on a part layup and sealing the periphery of the bag to the tool can be a time-consuming process, particularly where the part is large-scale, such as the composite aircraft fuselage, or a fuselage section or a panel. Following curing of the part, either using autoclave or out-of-autoclave processes, the bag and sealant tape are removed and discarded. The bag material and sealing tape are thus consumable items that increase production costs, including cost for materials and manpower needed for vacuum bagging and sealing the bag to the mandrel.

It would therefore be desirable to be able to more easily and quickly cover a part layup and form a vacuum tight seal over a mandrel.

The abstract of <CIT> states 'A method for manufacturing pieces of composite material by vacuum-bagging, wherein a laminate of uncured plies of composite material is layered up on a molding surface, and the upper surface of the laminate is then covered with one or more caul plates to assure smoothness of the outer surface of the final piece. According to the invention, local vacuum bags are provided in the form of elongated strips or bands to locally seal the edges of the caul plates such as the area of the local vacuum bags is smaller than the area of any of the caul plates. Due to the use of local vacuum bags, the amount of the material used is significantly reduced, thus, production times and manufacturing cost are significantly reduced.

The disclosure relates in general to processes and equipment for manufacturing composite structure, and more specifically to methods and equipment for sealing a caul over a composite part layup on a tool.

According to one aspect, an apparatus is provided for sealing a caul over a composite part layup on a tool. The apparatus includes an edge seal extending around a perimeter of the caul and configured to form a substantially vacuum tight seal between the caul and the tool.

According to another aspect, an apparatus is provided for sealing the least first and second cauls over a composite barrel part layout on a mandrel. The apparatus includes a first edge seal and a second edge seal. The first caul seal extends around the perimeter of the first caul and is configured to form a vacuum tight seal between the first caul and the mandrel. The second edge seal extends around the perimeter of the second caul, and is configured to form a vacuum tight seal between the second caul and the mandrel. The first and second caul seals overlap each other and are configured to form a vacuum tight seal between the first and second cauls.

According to still another aspect, a method is provided of making at least a section of a composite barrel. The method includes forming a composite barrel part layup on the mandrel, placing at least a first caul on the composite part layup, and forming a vacuum tight seal between the first caul and the mandrel, including sealing a perimeter of the first caul to the mandrel.

One of the advantages of the disclosed embodiments is that consumables such as large vacuum bags and sealant tape are reduced or eliminated, thus reducing production costs. Another advantage is that materials required to form a vacuum tight seal between a caul placed over a part layup and a tool are integrated into the caul, allowing the caul to be installed and sealed over the part layup more quickly. Another advantage is that the need for draping, positioning and sealing large vacuum bags over the cauls is eliminated, thus reducing processing time and allowing increased production rates.

According to another aspect of the present disclosure, an apparatus for sealing a caul over a composite part layup on a tool, comprising:
an edge seal extending around a perimeter of the caul and configured to form a vacuum tight seal between the caul and the tool.

Advantageously, the apparatus is one wherein the edge seal is permanently attached to the caul and is removably attached to the tool to allow the caul and the edge seal to be removed together from the tool.

Preferably, the apparatus is one wherein the edge seal includes a strip of material that overlaps the perimeter of the caul and a portion of the tool.

Preferably, the apparatus is one wherein the edge seal is adhesively bonded to the caul.

Preferably, the apparatus is one wherein the edge seal includes a flexible membrane configured to be formed over the caul and onto the tool.

Preferably, the apparatus further comprises a clamp configured to clamp the edge seal to the tool.

According to another aspect of the present disclosure, an apparatus for sealing at least first and second cauls over a composite barrel part layup up on a mandrel, comprising:.

Advantageously, the apparatus is one wherein the first edge seal is attached to the first caul and includes a flap configured to be placed over and sealed to the second edge seal.

Preferably, the apparatus is one wherein:.

Preferably, the apparatus is one wherein the first edge seal is configured to remain attached to the first caul upon removal of the first caul from the composite barrel part layup.

Preferably, the apparatus is one wherein the first edge seal includes a flap configured to overlie the second edge seal.

Preferably, the apparatus includes a clamp configured to clamp and seal the flap against the second edge seal.

Preferably, the apparatus is one wherein the clamp includes magnets on the flap configured to be attracted to the mandrel and clamp the flap against the first edge seal.

Preferably, the apparatus is one wherein the clamp includes carbon fiber stiffeners attached to and extending across the flap, the carbon fiber stiffeners being configured to press the flap down into positive engagement with the second edge seal.

Preferably, the apparatus is one wherein the clamp comprises a plurality of collapsible seals interposed between the flap and the second edge seal and configured to press the flap down into positive engagement with the second edge seal.

According to another aspect of the present disclosure, a method of making at least a section of a composite barrel, comprising:.

forming a vacuum tight seal between the first caul and the mandrel, including sealing a perimeter of the first caul to the mandrel.

Advantageously, the method is one wherein forming a vacuum tight seal includes sealing a strip of elastomeric material around the perimeter of the first caul.

Preferably, the method further comprises placing at least a second caul on the composite barrel layup;
forming a vacuum tight seal between the second caul and the mandrel, including sealing a perimeter of the second caul to the mandrel; and
forming a vacuum tight seal between the first caul and the second caul, including sealing a perimeter of the second caul to a perimeter of the first caul.

Preferably, the method is one wherein forming a vacuum tight seal between the first caul and the second caul includes:.

Preferably, the method is one wherein forming a vacuum tight seal includes:
integrating edge seals around the perimeters of each of the first and second cauls,.

The features, functions, and advantages can be achieved independently in various examples of the present disclosure or may be combined in yet other examples in which further details can be seen with reference to the following description and drawings.

The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative examples of the present disclosure when read in conjunction with the accompanying drawings, wherein:.

Referring first to <FIG>, an aircraft <NUM> includes a fuselage <NUM>, wings <NUM>, horizontal stabilizers <NUM>, and a vertical stabilizer <NUM>. In the illustrated example, the fuselage <NUM> is substantially cylindrical, however, in other examples the cross-sectional shape of the fuselage <NUM> may have an oval or similar cross sectional shape. Referring also to <FIG>, the fuselage <NUM> may comprise a plurality of barrel sections <NUM> joined together end-to-end. Each of the barrel sections <NUM> comprises barrel halves <NUM> joined together along a belt line <NUM>, each of which comprises an outer skin <NUM> formed of a composite laminate and reinforced by circumferentially extending, longitudinally spaced frames <NUM>, and longitudinally extending stringers <NUM>. The outer skin <NUM>, frames <NUM> and stringers <NUM> may each comprise a composite material, such as a carbon fiber reinforced plastic (CFRP) laminate. In other examples, the barrel sections <NUM> may be produced as a single cylindrical structure, rather than in two barrel halves <NUM>.

Referring now to <FIG>, in one production example, each of the barrel halves <NUM> is produced by laying up composite material on a mandrel <NUM> that may be formed of a metal and has a half barrel shape. Layup of the composite material may be performed by automatic fiber placement machines (not shown) or similar robotic manipulators that lay down layers of composite tape or split tape over the mandrel <NUM>. Prior to laying up the composite material on the mandrel <NUM>, stringers <NUM> are placed in longitudinal recesses (not shown) in the surface of the mandrel <NUM>. With the stringers <NUM> having first been installed on the mandrel <NUM>, the outer skin <NUM> is then laid up on the mandrel <NUM> in direct contact with the stringers <NUM>. The outer skin <NUM> and the stringers <NUM> are then cocured. For convenience of description, the outer skin laid up on the mandrel <NUM> will sometimes be referred to herein as a part layup <NUM>.

Referring to <FIG> and <FIG>, following material layup, one or more cauls 60a, 60b are placed on the part layup <NUM> in preparation for compacting and curing the part layup <NUM> in an autoclave <NUM>. The cauls 60a, 60b function to provide a desired profile and/or surface roughness or finish on the OML (outer mold line) of the outer skin <NUM>, while also applying even compaction pressure to the part layup <NUM> under autoclave pressure. In the illustrated example, two cauls 60a, 60b are placed over the part layup <NUM>, however in other examples, a single, half barrel shaped caul (not shown) may be placed over the part layup <NUM>. As will be discussed below in greater detail, the part layup <NUM> and the cauls 60a, 60b are not vacuum bagged in the usual manner, but rather a vacuum tight seal is formed over the part layup <NUM> by sealing the cauls 60a, 60b to each other and to the mandrel <NUM> using edge seals 62a, 62b (discussed later in connection with <FIG>) which are clamped together and to the mandrel <NUM>. The edges seals 62a, 62b effectively form localized sealing zones between the cauls 60a, 60b, as well as between the cauls 60a, <NUM> and the mandrel <NUM>. The combination of the cauls 60a, 60b and integrated edge seals 62a, 62b form a vacuum tight enclosure over the part layup <NUM>, thereby eliminating the need for a separate, all-encompassing vacuum bag, and saving the time required to install a vacuum bag, while reducing consumables. In some examples, the mandrel <NUM> may comprise a full barrel shape, rather than a half barrel in which case cauls <NUM> are installed over the full barrel part layup and are sealed to each other and to the mandrel <NUM>. In fact, in some applications, depending on the size and geometry of the part layup <NUM>, n number of cauls <NUM> (e.g. <NUM>, <NUM> or <NUM>) may be installed and sealed over the part layup <NUM>. Moreover, the n number of cauls <NUM> may be arranged side-by-side in the longitudinal direction <NUM> (<FIG>) as well as in the circumferential direction <NUM> of the part layup <NUM>. As used herein the term "caul" is used in its broadest sense and is defined as any type of vacuum integral tooling that provides profile control and/or surface finish or treatment of the OML of the part layup <NUM>.

Attention is now directed to <FIG>, <FIG> and <FIG>, which illustrate additional details showing how the cauls 60a, 60b are sealed to each other and to the mandrel <NUM> in order to form a vacuum tight enclosure over the part layup <NUM>. The cauls 60a, 60b have IMLs (inner mold lines) complementing the OML (outer mold line) of the barrel sections <NUM> and are separated by a gap <NUM>, which allows them to expand relative to each other when heated to processing temperatures. The cauls 60a, 60b, sometimes, referred to herein as first and second cauls respectively, have edge seals 62a, 62b that overlie and are attached to their entire outer perimeters. Thus, the edge seals 62a, 62b are respectively integrated into the cauls 60a, 60b and remain attached to the cauls 60a, 60b upon removal of the cauls 60a, 60b from the part layup <NUM>. Each of the edge seals 62a, 62b includes a longitudinal section <NUM> extending in a longitudinal direction <NUM> along the gap <NUM> between the two cauls 60a and 60b, and a circumferential section <NUM> extending in a circumferential direction <NUM> along the circumference of the mandrel <NUM>. The longitudinal sections <NUM> and the circumferential sections <NUM> of the edge seals 62a, 62b intersect each other to form a T-junction <NUM>. The edge seals 62a, 62b extend over the top of vacuum ports <NUM> and pressure sensor ports <NUM> in the mandrel <NUM> which are respectively used to draw and sense a vacuum beneath the cauls 60a, 60b to aid in compaction of the part layup <NUM>.

Each of the edge seals and 62a, 62b is a strip of material comprising a relatively thin, flexible membrane-like elastomer, such as silicone rubber or. Viton© that is sufficiently durable to permit repeated use. The ability to reuse the edge seals 62a, 62b and the fact that they are permanently attached to the cauls 60a, 60b, reduces installation labor costs as well as expendables. The elastomer selected is capable of withstanding the temperatures and pressures normally used to compact and cure fiber reinforced polymer materials, such as CFRP. The longitudinal section <NUM> of edge seals 62a includes a flap <NUM> that overlaps the longitudinal section <NUM> of the adjacent edge seal 62b, and spans the gap <NUM> between the cauls 60a, 60b.

A filler <NUM> (<FIG>) formed from a suitable material such as an elastomer is placed in the gap <NUM> to prevent undesired sagging of the flap <NUM> within the gap <NUM> during autoclave processing, and to apply compaction pressure to the part layup <NUM> across the gap <NUM>. Use of the filler <NUM> results in even compaction pressure being applied to the part layup <NUM> between the cauls 60a, 60b, despite the presence of the gap <NUM>. <FIG> shows the filler <NUM> having been compressed by the flap <NUM> due to vacuum and/or autoclave pressure, causing the filler <NUM> to deform, fill the gap <NUM>, and apply compaction pressure to the part layup <NUM> between the cauls 60a, 60b. A breather <NUM> is placed between the flap <NUM> and the underlying edge seal 62b to allow escape of air and volatiles from the part layup <NUM>, and to assist in spreading the vacuum applied to the part layup <NUM> throughout the area beneath the cauls 60a, 60b.

In one example, shown in <FIG>, a vacuum source (not shown) may be coupled to the longitudinally extending edge seals 62a over the breathers <NUM> using a vacuum fitting <NUM> that is external. The vacuum source that is coupled with the vacuum fitting <NUM> may be any suitable vacuum generating device, including those normally used to evacuate typical vacuum bags. The vacuum fitting <NUM> allows a vacuum to be applied through the breather <NUM> to those areas beneath the edge seal 62a, or in other words, to those areas that are not covered by the cauls <NUM>. If desired, the vacuum fitting <NUM> may be integrated into the edge seal 62a such that it remains attached to the edge seal 62a and thus may be reused when the cauls <NUM> are removed from the part layup <NUM>. Referring to <FIG>, in another example, the breather <NUM> may extend longitudinally beyond the outer edges of the cauls <NUM>, onto the mandrel <NUM> so that it overlies one or more of the vacuum ports <NUM> in the mandrel <NUM>. In this example, air and volatiles are drawn through the breather <NUM> into the vacuum ports <NUM> where vacuum is applied. As is also shown in <FIG>, the breather <NUM> may be extended longitudinally beyond the cauls <NUM> to intersect breather <NUM> at the T-junction, allowing a vacuum to be drawn beneath both edge seals 62a, 62b through the vacuum ports <NUM> in the mandrel <NUM>. The longitudinal extension of the breather <NUM> in this manner allows a vacuum to be applied through both of the breathers <NUM>, <NUM> to those areas beneath the edge seal 62a, 62b that are not covered by the cauls <NUM>.

Referring to <FIG> and <FIG>, the inboard side <NUM> of the edge seal 62a is adhesively attached around its entire perimeter to the underlying caul 60a along an adhesive bond line <NUM>. Likewise, edge seal 62b is adhesively attached around its entire perimeter to the underlying caul 60b along an adhesive bond line <NUM>. Other techniques for attaching the edge seals 62a, 62b to the cauls 60a, 60b are possible.

Referring to <FIG> and <FIG>, the circumferential sections <NUM> of the edge seals 62a, 62b are draped down over the outer edges of the cauls 60a, 60b, and then down over the cross sectional profile of the mandrel <NUM>, including a ramp <NUM> along the outer periphery <NUM> of the mandrel <NUM>. Breather <NUM> and breather <NUM> are provided between the circumferential sections <NUM> of the edge seals 62a, 62b, and the underlying mandrel <NUM>, typically located above the vacuum ports <NUM> (<FIG>) to allow the escape of the air, and volatiles during processing. In one example, breather <NUM> and breather <NUM> as well as breather <NUM> (<FIG>) may comprise individual pieces that are installed separate from the edge seals 62a, 62b that cover them. However, in other examples, breather <NUM>, breather <NUM> and breather <NUM> may be integrated into the edge seals 62a, 62b, as by molding. As will be discussed below in more detail, the flap <NUM> is sealed to the underlying longitudinal section of the edge seal 62b by any of a variety of clamping techniques. Similarly, the circumferential sections <NUM> of both edge seals 62a, 52b are sealed to the mandrel <NUM> using any of a variety of clamping techniques.

In the example shown in <FIG>, the edge seals 62a, 62b are permanently attached to the underlying cauls 60a, 60b by the adhesive bond lines <NUM>, <NUM>, allowing each of the cauls <NUM> and their edge seals <NUM> to be removed together as an assembly. However some applications it may be desirable to have the ability to easily remove the edge seals 62a, 62b for any of various reasons. One technique for removably attaching the edge seals 62a, 62b to the cauls 60a, 69b is illustrated in <FIG>, and <FIG>. In this example, zippers <NUM> are employed to releasably attach the inner edges of the edge seal 62a to the caul 60a. The zippers <NUM> each comprises a first toothed member <NUM> attached by a layer of adhesive <NUM> to the underlying caul 60a, and a second toothed member <NUM> similarly attached to the edge seal 62a. Each of toothed member <NUM> and toothed member <NUM>, may be formed of any suitable material such as silicone. Toothed member <NUM> and toothed member <NUM> friction fit together in interlocking relationship. In some examples, it may be necessary or desirable to provide a filler ramp <NUM> along an edge of the zipper <NUM> in order to smoothly ramp down the edge seal 62a from the zipper <NUM> to the surface of the caul 60a. The use of a zipper <NUM> allows the edge seal 62a to be easily removed when desired for cleaning, repair, and/or replacement. Other techniques for releasably attaching the edge seal 62a to the caul 60a are possible. In some examples, a zipper <NUM> may also be used to releasably attach either or both of the edge seals 62a, 62b to a caul <NUM> that is adjacent or to the mandrel <NUM>. For example, in <FIG> the flap <NUM> may be releasably attached and sealed to the caul 60b by a zipper <NUM> (not shown), and in <FIG>, the outer edge <NUM> (<FIG>) of the edge seal 62a may be similarly releasably attached and sealed to the caul 60b by a zipper <NUM>.

A wide variety of techniques can be employed to releasably clamp or attach the flap <NUM> of edge seal 62a down over the edge seal 62b in order to form a vacuum tight seal between these two edge seals 62a, 62b. These same clamping techniques can be used to clamp and seal the longitudinal sections of the edge seals 62a, 62b to the mandrel <NUM>. For example, referring to <FIG>, the outer end <NUM> of the flap <NUM> can be permanently attached to a carbon fiber mounting strip <NUM> that is bonded by a layer of adhesive <NUM> to caul 60a. The outer end <NUM> of the flap <NUM> can be clamped to caul 60b by a series of magnets <NUM> and/or ferromagnetic materials that are placed on top of or embedded into the flap <NUM>. The magnets <NUM> are attracted to the mandrel <NUM> or to ferromagnetic materials (not shown) embedded in the mandrel <NUM>, thereby clapping the flap <NUM> down against the caul 60b. In some applications, it may also be possible to attach the edge seal 62a to the caul 60a using magnets <NUM> in lieu of the use of an adhesive.

<FIG> illustrates another form of clamping devices in which spring members <NUM> such as carbon fiber stiffeners are bonded to the outer end <NUM> of the flap <NUM>. It may be possible to fabricate the spring member <NUM> from materials other than carbon fiber, such as spring steel. The spring member <NUM> has a preformed curved shape that causes the outer extremities 64a of the flap <NUM> to be forced down onto positive engagement and seal against the caul 60b.

<FIG> illustrates another technique for sealing the flap <NUM> against the caul 60b. In this example, a strip <NUM> of flexible spring material, such as a metal or carbon fiber is attached by adhesive <NUM> to the caul 60b. The strip <NUM> forces a pressure concentrator <NUM> such as a rod-like member which forces the outer end <NUM> of the flap <NUM> to seal against the edge seal 62b.

A further example of sealing the flap <NUM> against the caul 60b is shown in <FIG>. In this example, the outer end <NUM> of the flap <NUM> includes a stiffener <NUM> secured by a layer of adhesive <NUM> to a flexible seal <NUM> having the cross sectional shape of an inverted "<NUM>". An inflatable hose <NUM> is positioned between the top of the flap <NUM>, and a strongback <NUM> which may comprise, for example and without limitation, a rigid frame. Inflation of the hose <NUM> forces the flap <NUM> downwardly, causing the flexible seal <NUM> to collapse and form a vacuum tight seal between the flap <NUM> and the edge seal 62b. Alternatively, the strongback <NUM> may be displaced downwardly, causing a preinflated hose <NUM> to force the flexible seal <NUM> to collapse.

Referring to <FIG> and <FIG>, in another example, a pair of the flexible seals <NUM> are positioned at spaced apart locations between the flap <NUM> and the edge seal 62b. In this example, the flexible seals <NUM> are subjected to a vacuum and act as vacuum chucks which draw down the flap <NUM>, causing the flexible seals <NUM> to collapse (see <FIG>) against the edge seal 62b, creating a vacuum tight seal between the edge seals 62a and 62b.

Attention is now directed to <FIG>, which illustrates another example of a technique for sealing the flap <NUM> against the edge seal 62b. In this example, rather than overlapping the flap <NUM> over the edge seal 62b, the outer end <NUM> of the flap <NUM> and the inner end <NUM> of the edge seal 62b are arranged in face-to-face relationship and are seal together with magnets <NUM> or other means, such as a clamp (not shown). A spacer <NUM> may be placed between the ends of the flap <NUM> and the edge seal 62b to maintain their face-to-face orientation.

Referring to <FIG>, the longitudinal section <NUM> and the circumferential section <NUM> of the edge seals 62a, 62b intersect at a T-junction <NUM> as previously mentioned. In order to assure that there is no air leakage at the T-junction <NUM>, a clamp <NUM> may be provided to force the two edge seal 62a, 62b together against the mandrel <NUM> at the T-junction. The clamp <NUM> may comprise any of a number of mechanisms, but in the illustrated example, comprises a toggle mechanism <NUM>. The toggle mechanism includes a base <NUM> mounted on the mandrel <NUM> and a pressure plate <NUM>. The bottom of the pressure plate <NUM> includes a rectangular, gasket-like seal <NUM>. The toggle mechanism <NUM> forces the pressure plate <NUM> downwardly, causing the gasket-like seal <NUM> to apply pressure at the T-junction <NUM>, thereby creating a tight seal at this location between the edge seals 62a and 62b.

<FIG> illustrates another example of a technique for assuring that air leaks do not occur at the T-junction <NUM>. In this example, a vacuum bag <NUM> is placed over the area of the T-junction and sealed to the underlying edge seals 62a, 62b by a bead of sealant <NUM>.

Attention is now directed to <FIG>, which broadly illustrates the steps of a method of making at least a section of a composite barrel using cauls <NUM> having the edge seals <NUM> described above. Beginning at <NUM>, a composite barrel layup is formed on a mandrel <NUM>. At <NUM>, at least a first caul 60a is placed on the composite barrel layup. At <NUM>, a vacuum tight seal is formed between the first caul 60a and the mandrel <NUM>, thereby creating a local sealing zone. The seal at <NUM> may be formed by sealing the perimeter of the caul to the mandrel <NUM>, as by sealing a strip of elastomeric material to the caul. Although not shown in <FIG>, as previously described, cauls <NUM> may be installed on the composite barrel layup and sealed to the mandrel <NUM> and to each other using edge seals <NUM> that create localized sealing zones.

Examples of the disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine, and other applications where vacuum bag compaction of composite part layups utilize cauls. Thus, referring now to <FIG>, examples of the disclosure may be used in the context of an aircraft manufacturing and service method <NUM> as shown in <FIG> and an aircraft <NUM> as shown in <FIG>. Aircraft applications of the disclosed examples may include a variety of composite parts and structures, including sections of a fuselage <NUM>. During pre-production, exemplary manufacturing and service 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 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 maintenance and service <NUM>, which may also include modification, reconfiguration, refurbishment, and so on. The disclosed embodiments may be used in one or more of production process <NUM> or production process, or in the airframe <NUM> or in the fuselage <NUM>.

Each of the processes of manufacturing and service method <NUM> may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer).

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

Claim 1:
An apparatus for sealing at least first and second cauls (60a, 60b) over a composite barrel part layup (<NUM>) on a mandrel (<NUM>), comprising:
a first edge seal (62a) extending around a perimeter (<NUM>) of the first caul (60a) and configured to form a vacuum tight seal between the first caul (60a) and the mandrel (<NUM>); and
a second edge seal (62b) extending around a perimeter (<NUM>) of the second caul (60b) and configured to form a vacuum tight seal between the second caul (60b) and the mandrel (<NUM>),
wherein the first and second edge seals (62a, 62b) overlap and are configured to form a vacuum tight seal between the first and second cauls (60a, 60b).