Fastener in which sealant dose incorporated for addition of wet sealant is applied in advance, and method

Abstract

To provide a fastener with an added sealing material that prevents corrosion and / or leakage in a region of the fastener.SOLUTION: Disclosed are a fastener 20 to which a curable sealant encased in a rupturable protective shell is added in advance, the protective shell cured at least partially, and a method for adding a selected curable sealant dose 30 to an aircraft assembly, the sealant dose supplied to an aircraft assembly location simultaneously during installation of the fastener 20.SELECTED DRAWING: Figure 3B

Description

[Technical field]

[0001]

[0001] The present disclosure relates generally to the field of sealants and sealing processes. In particular, the present disclosure relates to the field of sealants and seals present at a fastener / substrate interface. [Background technology]

[0002]

[0002] The manufacture of aircraft, including aircraft assemblies and subassemblies, may require the installation of large numbers (e.g., several thousand or more in total) of fasteners to join components together, join segments of components together, and / or join components, subassemblies, and / or assemblies to larger structures, etc. Depending on the type of component in which the fasteners are installed, the installation of such fasteners may involve the addition of a sealant to the installation area to prevent corrosion and / or leakage in the area of ​​the fastener being installed.

[0003]

[0003] Unless expressly stated otherwise, statements in this specification are not admitted to be prior art by virtue of being included merely in the technical field and / or background art. Summary of the Invention

[0004]

[0004] One aspect is directed to a fastener for use in an assembly of an aircraft, the fastener including a fastener exterior surface, a hardenable sealant dose configured to coat a fastener exterior surface region of the fastener exterior surface, the hardenable sealant dose including a first chemical composition, and an at least partially cured protective shell including the first chemical composition in an at least partially cured state and configured to substantially completely encase the hardenable sealant dose within the at least partially cured protective shell, where the hardenable sealant dose is stored in an uncured state within the at least partially cured protective shell.

[0005] In another aspect, the curable sealant dose and the at least partially cured protective shell include at least one of a first chemical composition and a chemically compatible material.

[0006] In another aspect, the curable sealant dose and the at least partially cured protective shell comprise the same material.

[0007] In another aspect, the fastener is made from at least one of a metal, a thermoplastic material, a composite material, and combinations thereof.

[0008] In another aspect, the fastener further includes a curable sealant / at least partially cured protective shell interface.

[0009] In another aspect, the curable sealant dose and the at least partially cured protective shell comprise a light curable sealant.

[0010] In another aspect, the curable sealant dose and the at least partially cured protective shell comprise a UV curable sealant.

[0011] In another aspect, the curable sealant dose includes a polysulfide-based sealant and the at least partially cured protective shell includes a polysulfide-based sealant detackifier.

[0012]

[0012] In another aspect, the curable sealant dose comprises a UV-curable sealant in an uncured state, and the at least partially cured protective shell comprises a UV-curable sealant in a partially cured state.

[0013] In another aspect, the fastener further includes a UV curable sealant / at least partially UV cured material protective shell interface.

[0014] In a further aspect, the curable sealant dose comprises an average thickness ranging from about 1 / 8 inch to about 1 / 4 inch.

[0015] In another embodiment, the at least partially cured protective shell comprises an average thickness in the range of about 1 mm to about 2 mm.

[0016] In another aspect, the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 240 psi to about 400 psi.

[0017] In another aspect, the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 365 psi.

[0018] In another aspect, the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 400 psi.

[0019]

[0019] A further present aspect is directed to an aircraft pre-assembly including a substrate, where the substrate includes a plurality of components, where the plurality of components are configured to receive a curable sealant loaded fastener to join the plurality of components in a fastener installation operation to form an installed fastener. The aircraft pre-assembly further includes an installed curable sealant loaded fastener, where the installed curable sealant loaded fastener is dimensioned to join the plurality of components. The installed curable sealant loaded fastener includes a dispensed curable sealant dose including a first chemical composition. In that case, the released hardenable sealant dose is released from the ruptured at least partially cured protective shell, the ruptured at least partially cured protective shell is configured to rupture substantially simultaneously during installation of the fastener to be installed into the aircraft pre-assembly, and the at least partially cured ruptured protective shell is configured to release the hardenable sealant from the at least partially cured ruptured protective shell during installation of the fastener to be installed into the aircraft pre-assembly. The ruptured at least partially cured protective shell includes at least one of a first chemical composition and a chemical composition compatible with the first chemical composition.

[0020]

[0020] In another aspect, the curable sealant dose comprises a polysulfide-based sealant and the at least partially cured sealant protective shell comprises a polysulfide-based sealant detackifier.

[0021]

[0021] In another aspect, the curable sealant dose includes a first UV-curable sealant in an uncured state, and the at least partially cured protective shell includes a layer of the first UV-curable sealant in an at least partially cured state.

[0022]

[0022] In another aspect, the rupturable at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 400 psi during installation of a fastener having the installed curable sealant added thereto.

[0023]

[0023] Another present aspect is directed to a method for making a fastener for an aircraft assembly, the method including applying a hardenable sealant dose to a fastener exterior region of the fastener to form a hardenable sealant loaded fastener, the hardenable sealant loaded fastener including a hardenable sealant loaded fastener exterior region, the method further including forming an at least partially cured protective shell in the hardenable sealant loaded fastener exterior region configured to encase the hardenable sealant dose.

[0024] In another aspect, the method includes multiple aspects of the method and further includes coating the fastener exterior area to which the curable sealant has been added with a sealant detackifier layer, where the at least partially cured protective shell includes the sealant detackifier layer.

[0025] In another aspect, the curable sealant dose comprises a polysulfide-based material and the detackifier layer comprises a polysulfide-based material.

[0026] In another aspect, the curable sealant dose comprises a UV curable material.

[0027]

[0027] In another aspect, a method includes multiple aspects of the method and further includes at least partially curing an outer region of the curable sealant dose of UV curable material to form an at least partially cured protective shell.

[0028]

[0028] A further aspect of the present invention is directed to a fastener made according to the method, which includes applying a hardenable sealant dose to a fastener exterior region of the fastener to form a hardenable sealant loaded fastener, where the hardenable sealant loaded fastener includes a hardenable sealant loaded fastener exterior region, and the method further includes forming an at least partially cured protective shell in the hardenable sealant loaded fastener exterior region configured to encase the hardenable sealant dose.

[0029]

[0029] A further aspect of the present invention is directed to at least one of an aircraft assembly and an aircraft preassembly including a fastener made according to the method, which includes applying a hardenable sealant dose to a fastener exterior region of the fastener to form a hardenable sealant loaded fastener, where the hardenable sealant loaded fastener includes a hardenable sealant loaded fastener exterior region, and the method further includes forming an at least partially cured protective shell in the hardenable sealant loaded fastener exterior region configured to encase the hardenable sealant dose.

[0030]

[0030] A further aspect of the present invention is directed to an aircraft including a fastener made according to the method, which includes applying a hardenable sealant dose to a fastener exterior region of the fastener to form a hardenable sealant loaded fastener, where the hardenable sealant loaded fastener includes a hardenable sealant loaded fastener exterior region, and the method further includes forming an at least partially cured protective shell in the hardenable sealant loaded fastener exterior region configured to encase the hardenable sealant dose.

[0031]

[0031] Another aspect of the present invention is directed to a method for assembling an aircraft assembly. In that case, the method includes providing a plurality of components, the plurality of components configured to receive a fastener installed to join the plurality of components, and providing a fastener configured to join the plurality of components. The fastener includes a fastener outer surface including a hardenable sealant dose. In that case, the hardenable sealant dose includes an at least partially cured protective shell configured to completely encase the hardenable sealant dose in an uncured state. The method further includes installing the fastener to join the plurality of components, and substantially simultaneously with installing the fastener, rupturing the at least partially cured protective shell during installation of the fastener to form an ruptured protective shell. The method further includes expelling at least a portion of the curable sealant dose from the ruptured protective shell to generate an expelled curable sealant dose, and curing the expelled curable sealant dose to form the aircraft assembly. In that case, the curable sealant dose and the at least partially cured protective shell include a common compound.

[0032]

[0032] Another aspect of the present invention is directed to an aircraft assembly made according to the method. The method includes providing a plurality of components, the plurality of components configured to receive a fastener installed to join the plurality of components, and providing a fastener configured to join the plurality of components. The fastener includes a fastener outer surface including a hardenable sealant dose. In that case, the hardenable sealant dose includes an at least partially cured protective shell configured to completely encase the hardenable sealant dose in an uncured state. The method further includes installing the fastener to join the plurality of components, and substantially simultaneously with installing the fastener, rupturing the at least partially cured protective shell during installation of the fastener to form a ruptured at least partially cured protective shell. The method further includes ejecting at least a portion of the hardenable sealant dose from the at least partially cured ruptured protective shell to generate an ejected hardenable sealant dose, and curing the ejected hardenable sealant dose to form the aircraft assembly. In that case, the curable sealant dose and the at least partially cured protective shell comprise the same and / or compatible chemical compositions.

[0033]

[0033] Another aspect of the present invention is directed to an aircraft including an aircraft assembly made according to the method. The method includes providing a plurality of components, the plurality of components configured to receive a fastener installed to join the plurality of components, and providing a fastener configured to join the plurality of components. The fastener includes a fastener outer surface including a hardenable sealant dose. In that case, the hardenable sealant dose includes an at least partially cured protective shell configured to completely encase the hardenable sealant dose in an uncured state. The method further includes installing the fastener to join the plurality of components, and substantially simultaneously with installing the fastener, rupturing the at least partially cured protective shell during installation of the fastener to form a ruptured at least partially cured protective shell. The method includes expelling at least a portion of the hardenable sealant dose from the ruptured at least partially cured protective shell to generate an expelled hardenable sealant dose, and curing the expelled hardenable sealant dose to form the aircraft assembly. In that case, the curable sealant dose and the at least partially cured protective shell comprise the same and / or compatible chemical compositions.

[0034]

[0034] The above-described features, functions, and advantages can be realized alone in various aspects or can be combined in further multiple aspects, details of which can be ascertained by reference to the following description and accompanying drawings.

[0035]

[0035] Having described the present disclosure in general terms, reference is now made to the accompanying drawings, which are not necessarily drawn to scale. [Brief description of the drawings]

[0036] [Figure 1]

[0036] FIG. 1 is a diagram of a vehicle taking the form of an aircraft according to the present embodiment. [Diagram 2]

[0037] FIG. 2 is a side view, not necessarily drawn to scale, of a fastener according to the present embodiment; [Figure 3A]

[0038] FIG. 2 is a perspective view of a fastener including an applied dose of hardenable sealant according to the present embodiment; [Figure 3B]

[0039] FIG. 3B is a perspective view of a fastener, which may be of the type shown in FIG. 3A, further including a layer of hardenable material that may be at least partially hardened to become a protective shell layer according to the present embodiment. [Figure 3C]

[0040] FIG. 4 is a perspective view of a fastener, which may be of the type shown in FIG. 3A and / or FIG. 3B, according to the present embodiment. [Figure 3D]

[0041] 3D is a cross-sectional view of a fastener, which may be of the type shown in FIG. 3C, according to the present embodiment. [Figure 4A]

[0042] FIG. 1 is a perspective view of an aircraft pre-assembly including a substrate component according to the present embodiment; [Figure 4B]

[0043] FIG. 1 is a perspective view of an aircraft pre-assembly including a substrate component having fasteners installed thereon according to the present aspects. [Diagram 5]

[0044] 1 is a flow chart outlining a method according to the present embodiment. [Figure 6]

[0045] 1 is a flow chart outlining a method according to the present embodiment. [Figure 7]

[0046] 1 is a flow chart outlining a method according to the present embodiment. [Figure 8]

[0047] 1 is a flow chart outlining a method according to the present embodiment. [Figure 9]

[0048] 1 is a flow chart outlining a method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037]

[0049] Addition of sealant for the large number (e.g., thousands or more) of fasteners installed on an aircraft is time consuming and expensive, at least in terms of man hours, labor, materials, inspection of fastener installation sites, etc. Additionally, the sealant may have a pot life that requires that the addition be done before the sealant hardens or begins to harden. Ultimately, production times and / or delays related to fastener installation may result in large amounts of sealant wasted, further contributing to increased costs. Additionally, adding sealant to fastener sites in aircraft manufacturing may require transporting the sealant to the "point of use," which may be affected by spatial constraints including, for example, enclosed spaces, which may include, for example, fuel tanks, etc.

[0038]

[0050] Additionally, properly applying an amount of sealant to fastener sites in aircraft assemblies, subassemblies, and the like can be an imprecise endeavor that can result in either or both of an insufficient amount of sealant at various fastener sites and / or excess sealant that needs to be wiped or otherwise removed from surfaces of the assemblies and / or subassemblies before the applied sealant cures.

[0039]

[0051] Additionally, for example, the application of wet sealant to fastener sites during manufacture of an aircraft can further result in the introduction of foreign object debris (FOD), which may precipitate on or in the batch of wet sealant before or when it is added to the assembly, which may precipitate on or in the fastener installation site, or which may precipitate in the sealant during preparation of the batch of sealant.

[0040]

[0052] Several present aspects target and address these and other challenges that may complicate and / or exacerbate the application of sealants, including applying sealants to areas that will be fastened during manufacture of the aircraft.

[0041]

[0053] FIG. 1 shows a vehicle in the form of an aircraft 10 having a fuselage 12 attached to a wing 14 having a fuel tank 14a disposed internally within the wing 14 of the aircraft.

[0042]

[0054] Although FIG. 2 is a side view of a fastener 20 in the form of a bolt, present embodiments contemplate nearly any type of fastener that would benefit from the sealant delivery embodiments described herein. In this regard, contemplated fasteners include, for example, screws, rivets, and the like. The fastener 20 shown in FIG. 2 includes a fastener head 22. A shank section 26 extends from an underside of the fastener head 22 to a thread section 24. The shank section 26 is further illustrated as including a fastener exterior surface region 26a. Although the fastener shown in FIG. 2 and described herein may include modifications to a fastener exterior section located primarily on the shank of the fastener (when the fastener is, for example, a bolt), present embodiments further contemplate modifications to the fastener exterior surface that also extend into the thread section and to and / or above the fastener head. However, such embodiments may not be explicitly shown in the drawings.

[0043]

[0055] 3A, 3B, and 3C illustrate several present and alternative fastener processing progressions that modify typical fasteners of the type used in aircraft manufacturing into processed fasteners (equivalently referred to herein as "pre-applied fasteners"). This can significantly simplify the wet sealing process and eliminate or eliminate the wet sealant application step (and multiple steps in the wet sealant application and clean-up steps, etc.). This can result in significant time and cost savings in terms of at least man hours, material costs, rework time, clean-up, maintenance time, and can significantly reduce production time and / or the amount of time an aircraft may be out of service for rework requiring the addition of sealant.

[0044]

[0056] The significant time and cost savings provided by aspects of the present disclosure are in addition to the significant improvement of aspects in increasing overall manufacturing flow by providing a "right sized" amount of wet sealant dose delivered for a specific sealing application at a specific sealing location in, for example, aircraft manufacturing, in a process that provides a "right sized" dose of wet sealant substantially simultaneously with the installation of a pre-applied fastener.

[0045]

[0057] The delivery of a selected "right-sized" wet sealant dose simultaneously with the installation of a pre-loaded fastener eliminates the problem of providing insufficient sealant to the area or region to be sealed. Insufficient sealant can lead to poor or insufficient sealing which can cause resealing resulting in added manufacturing costs. Additionally, the delivery of a selected "right-sized" wet sealant dose eliminates the problem of providing an excessive amount of sealant to the area or region to be sealed. An excessive amount of sealant can result in a large amount of wasted material (sealant) that needs to be removed, further resulting in additional manufacturing costs, time, etc.

[0046]

[0058] According to several present aspects, before a fastener is installed in an assembly or subassembly that may require the addition of a wet sealant (and that previously typically required a separate step for the addition of the wet sealant, such as before, during, and / or after fastener installation), the fastener is pre-treated (equivalently referred to herein as "pre-added") with a selected amount of wet sealant (configured to be curable and remain in an uncured state until actual installation) to form a fastener that includes an appropriate amount or selected "dose" of wet sealant. The wet sealant is in an uncured state, stored in an uncured state, and maintained in an appropriate location on the pre-added fastener, and is not released from the fastener until the pre-treated fastener is installed in a location in a subassembly, assembly, or the like. That is, according to several present aspects, the fastener has been treated to function not only as a fastener, but also as a controlled delivery device for a selected dose of uncured wet sealant at the time and location of actual fastener installation.

[0047]

[0059] As shown in Figure 3A, a fastener 20 of the type shown in Figure 2 (but fastener 20 may represent any fastener type including, for example, a screw, a rivet, etc.) is shown having a curable sealant dose 30 applied to an outer fastener surface region 26a of the fastener 20. The curable sealant dose is a wet sealant suitable for wet sealant application and may be applied to the fastener by an application method that may include spraying, brushing, dipping, etc. Figure 3A shows an applicator 34 used to apply the curable sealant dose to the outer fastener surface region 26a.

[0048]

[0060] 3B illustrates one embodiment of this. A curable wet sealant coating or pre-measured "dose" is treated with a material that, when at least partially cured, results in an at least partially cured protective shell. The at least partially cured protective shell is configured to maintain the underlying curable sealant dose in an uncured and / or uncured "wet" sealant state (e.g., maintained uncured under the at least partially cured protective shell).

[0049]

[0061] According to one embodiment, depending on the requirements and properties of the end use of the wet sealant, when a curable polysulfide-based wet sealant is selected, the selected protective shell material will be selected to have a high degree of chemical compatibility with the underlying wet sealant. Referring back to this embodiment, when the selected curable sealant dose includes, for example, a polysulfide-based curable sealant dose, the selected protective shell material will be a polysulfide-based material. This material will, for example, cure under ambient conditions and maintain the underlying curable sealant dose as a "wet" and uncured sealant under the at least partially cured protective shell until the protective shell is ruptured at the point of fastener installation. At this point, the wet polysulfide sealant is released from the ruptured protective shell to the surface to be sealed by the wet sealant.

[0050]

[0062] Once the "wet" and uncured sealant is released from the at least partially cured ruptured protective shell during and contemporaneous with installation of the fastener, the wet sealant may begin to undergo its curing regimen. The curing regimen may be curing under ambient environmental conditions (ambient pressure, ambient temperature, etc.) and / or, if a UV-curable sealant is selected, the released wet UV-curable sealant may undergo (e.g., be exposed to) a UV curing regimen such that the released UV-curable wet sealant is cured.

[0051]

[0063] Figure 3B shows a fastener 20 of the type shown in Figure 3A including a curable sealant dose that is now coated with an additional layer of material that will form an at least partially cured protective shell. According to some present embodiments, the material of the at least partially cured protective shell is a material that is at least chemically compatible with the sealant. That is, the sealant and protective shell materials may share a common chemical composition, be from the same family of compounds, and possess compatible chemistries.

[0052]

[0064] The applied protective shell material is configured to form an at least partially cured protective shell 32 when the protective shell material is at least partially cured (e.g., the protective shell material cures in place over the curable sealant dose). The protective shell 32 will keep the underlying curable sealant dose as "wet" and uncured sealant underneath the at least partially cured protective shell. As shown in FIG. 3B, the protective shell material can be applied to the curable sealant dose by methods that may include, for example, spraying, and may include other selected material deposition methods.

[0053]

[0065] FIG. 3C shows the fastener 20 of FIGS. 3A, 3B now coated with both, i.e., a curable sealant dose 30 coated with an at least partially cured protective shell material, thereby forming a sealant-loaded fastener 36 having an at least partially cured protective shell 32 that covers, protects, and maintains the curable sealant dose 30 (not shown in FIG. 3C) in a "wet" and uncured state.

[0054]

[0066] Figure 3D is a cross-sectional view of a sealant-loaded fastener 36, which may be of the type shown in Figure 3C, taken along line 3D-3D. As shown in Figure 3D, the sealant-loaded fastener 36 comprises a fastener 20 including a curable sealant dose 30 coating the fastener 20 (an uncoated fastener) having an at least partially cured protective shell 32 covering, encasing (e.g., coating) the curable sealant dose 30 at a curable sealant dose / at least partially cured protective shell interface 33.

[0055]

[0067] In an alternative embodiment, referring back to FIG. 3A, when a photocurable sealant is selected, which may be, for example, a UV-curable wet sealant, depending on the end-use requirements and the properties of the wet sealant, a selected protective shell may be formed without adding a separate material to the curable sealant dose. That is, according to this current embodiment, when the curable sealant dose is a UV-curable sealant dose, the UV-curable sealant may be subjected to an initial and short UV-curing regimen selected to cure only the surface of the UV-curable sealant to form an at least partially cured protective shell of a selected thickness (on the outer and / or exposed surfaces of the UV-curable sealant dose), while the remainder of the UV-curable sealant dose is left in a wet and uncured state "protected" by the protective shell. In this embodiment, the at least partially UV-cured protective shell and the uncured underlying UV-curable sealant dose may be the same UV-curable material.

[0056]

[0068] In this embodiment, after formation of the UV-cured protective shell, a sealant-loaded fastener 36 is formed having an at least partially UV-cured protective shell. In this embodiment, the step of separately adding an additional chemically compatible material to cover or encase the wet sealant may be eliminated or replaced by an initial UV-curing step of the outer surface of the UV-curable sealant dose only. Figures 3A, 3C, and 3D also apply to this embodiment. In that case, as shown in Figure 3D, the sealant-loaded fastener 36 comprises a fastener 20 including a curable sealant dose 30 (which may be a UV-curable sealant dose) coating the fastener 20 (an uncoated fastener), and having an at least partially cured protective shell 32 covering, encasing (e.g., coating) the UV-curable sealant dose 30 at a curable sealant dose / at least partially cured protective shell interface 33. Again, in this embodiment, an initial at least partial UV cure of the outer surface of the UV curable sealant is performed, and the at least partially UV cured protective shell and the remaining uncured UV curable wet sealant can be the same UV curable material, in which case the protective shell is formed from the outside or outer surface of the UV curable wet sealant dose.

[0057]

[0069] The selected UV-curable sealant may be, for example, an acrylic-based material. The acrylic-based material may be applied as a sealant dose to the fastener outer surface area of ​​the fastener in a selected amount, whereby the average thickness of the sealant dose may range from about 1 / 8 inch to about 1 / 4 inch. When the outer surface of the UV-curable sealant dose is subjected to an initial UV-curing regimen to form an at least partially UV-cured protective shell, the selected thickness of the at least partially UV-cured protective shell may be from about 1 mm to about 2 mm, and may be achieved with a controlled UV-curing regimen having an elapsed UV-curing time ranging from about 5 seconds to about 10 seconds, for example. The UV-curing regimen and the UV-curable sealant may be selected to both: produce the selected protective shell thickness, while leaving the remainder of the UV-curable sealant dose uncured and in a "wet" and uncured state. In that case, the uncured sealant dose is effectively enclosed, encased, etc., within the protective shell.

[0058]

[0070] As used herein, the term "encapsulated" means that the entire outer region of the uncured curable sealant dose is entirely or completely surrounded by the protective shell, e.g., in a leak-proof configuration. Several present embodiments recognize that after formation of the protective shell, the wet UV-curable sealant contained (e.g., encapsulated) within the protective shell remains curable but uncured. In that case, the uncured sealant dose is bounded by the protective shell and further bounded by the fastener exterior surface region.

[0059]

[0071] 4A and 4B illustrate a number of installation progressions according to the present disclosure, where sealant-loaded fasteners 36 are provided to a preassembly (e.g., an unfastened preassembly) and installed therein to form a fastened assembly. FIG. 4A illustrates an aircraft preassembly 40 including substrate components 40a, 40b joined together at fastening sites 44 by sealant-loaded fasteners 36. As shown in FIGS. 4A and 4B, the fastening sites 44 are configured to extend through the aligned substrate components 40a, 40b. The aligned fastening sites 44 are thereby configured to receive the sealant-loaded fasteners 36 therethrough to join the fastened substrate components 40a, 40b together and to each other.

[0060]

[0072] As shown in Figures 4A and 4B, the fastening sites 44 pass through openings (e.g., "holes"). The openings each have a close tolerance for the fastener to be inserted and may have slight or clearance spaces between the inserted fastener and the fastening site (e.g., the cavity walls of the fastening site, etc.). Depending on the location of the substrates being joined, it may be desirable to have the fastening site leak-proof or the addition of a sealant to the fastening site to make the fastening site "leak-proof."

[0061]

[0073] As shown in FIG. 4B , the sealant-loaded fastener 36 is inserted or otherwise installed within the fastening site 44 to form a joined aircraft assembly 42 including a first assembly component 42a joined to a second assembly component 42b. According to some present embodiments, simultaneously and / or substantially simultaneously with the installation operation of the sealant-loaded fastener 36 into the fastening site 44, a force on the sealant-loaded fastener 36 generated by the insertion of the sealant-loaded fastener 36 into the fastening site 44 ruptures and / or otherwise breaks the at least partially cured protective shell 32 containing the uncured sealant dose. In that case, the uncured and curable sealant dose is released from the protective shell (e.g., the now-ruptured protective shell), with the released curable sealant occupying what may have been a gap location previously present between the fastener exterior surface and the fastening site.

[0062]

[0074] According to some embodiments, the pressure applied to the sealant-loaded fastener during installation is selected to be the pressure required to rupture the at least partially cured protective shell. In one embodiment, when the average thickness of the at least partially cured protective shell is in the range of about 1 mm to about 2 mm, the force on the protective shell sufficient to rupture the protective shell may be in the range of about 240 psi to about 400 psi. In another embodiment, the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 400 psi. In another embodiment, the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 365 psi.

[0063]

[0075] Without being bound by any theory, the force applied to the fastener with the present sealant during installation may generate an inward pressure on the protective shell. Additionally, as the pressure in the protective shell increases, the elastic force of the uncured wet sealant in the protective shell may exert an outward force on the protective shell with an outward pressure from inside the location of the wet sealant contents in the protective shell. Regardless of whether the pressure exerted on the protective shell is inward, outward, or a combination thereof, the defined pressures described herein are achieved by and are brought about simultaneously with the installation process of the fastener into the fastening site of the assembly. Additionally, according to several present embodiments, the force / pressure required to rupture the protective shell exceeds the forces that a fastener with the sealant typically encounters during handling, shipping, storage, etc. According to several present aspects, the protective shell of a fastener loaded with a curable sealant may be selected to be robust enough to allow such fastener to be set in an automated installation procedure (e.g., robot-assisted assembly, etc.). Such fasteners may then be "picked up," placed, inserted, and otherwise handled by machines during such automated procedures. This wet sealant loaded fastener not only enables and facilitates assembly manufacturing via automated fastener installation, but may also enable automated sealing functions. This sealing function may significantly and advantageously increase the opportunities for automated sealant addition in areas that may have dimensional limitations or be located areas that may otherwise be difficult or impossible to access by operating personnel, including, for example, aircraft fuel tanks, etc.

[0064]

[0076] Once released from the protective shell, the selected curable sealant may begin to cure in the ambient environment according to a selected sealant curing regimen. In another embodiment, once the UV-curable sealant is released from the protective shell, UV light may be directed to the fastening site to UV-cure the released UV-curable sealant. FIG. 4B further illustrates the installed fastener 36a in place at the fastening site 44 and joined substrate components in the form of first assembly component 42a and second assembly component 42b. In that case, the curable sealant has now been released from the ruptured protective shell into a location (e.g., a "space") within the fastening site 44 that will be sealed by the released sealant as it cures.

[0065]

[0077] Many sealant application benefits are realized by pre-adding a selected, protected, appropriately sized "dose" of a curable wet (and uncured) sealant to the fastener. According to several present aspects, the term "dose" means a selected and / or measured quantity or amount, which may be measured by volume or mass. The selected curable sealant dose is then selected to produce a desired selected seal (when cured) or to otherwise complete a selected sealing process of a space, void, surface, etc., of a component of an assembly, which may be, for example, an aircraft assembly within an aircraft.

[0066]

[0078] As described herein, fasteners preloaded with a selected amount of a curable sealant may eliminate the step of adding sealant that was previously performed as a separate fastener installation / sealing step and process. By providing the present preloaded fasteners according to several present embodiments, there is no amount of separate sealant required to perform and / or complete the sealing process, as the amount of sealant required for the selected sealing process is provided entirely by the sealant dose contained within the protective shell of the preloaded fastener.

[0067]

[0079] Additionally, previous challenges present in the manufacturing environment with regard to foreign object debris (FOD) contaminating a batch of sealant or contaminating the location being sealed are significantly minimized or eliminated because the sealant applied to a structural location (e.g., a subassembly, assembly, etc. in a manufacturing setting) is not exposed to the manufacturing environment prior to application to the selected sealing location. That is, according to several present aspects, the sealant remains isolated or otherwise protected from the manufacturing environment until the protective shell on the pre-applied fastener releases the sealant from the ruptured protective shell at the precise moment of actual fastener installation at the precise location within the fastener assembly where the application of sealant is required.

[0068]

[0080] Additionally, according to some present embodiments, the selection of materials of the hardenable sealant dose and the at least partially cured protective shell having the same, similar, or compatible chemical composition further prevents the formation, accumulation, and ingress of FODs that would otherwise result from materials of dissimilar chemical composition contaminating the released sealant dose from the encapsulation of the protective shell. That is, according to some present embodiments, when the curable sealant dose is released from the ruptured protective shell, fragments of the protective shell may be acceptably present in the released curable sealant dose in the area to be sealed, for example, without adversely affecting or otherwise interfering with the quality of the final seal when the released curable sealant dose is cured. Without being bound to any particular theory, it is believed that the selection of compatible or identical chemistry of the shell and the hardenable dose results in the absorption and / or assimilation of fragments of the at least partially cured ruptured protective shell into the sealant dose. This is because both the at least partially cured ruptured protective shell and the curable (but uncured) dose released from the ruptured protective shell undergo further and final curing, which may be ambient curing, UV curing, etc.

[0069]

[0081] According to some present aspects, the pre-loaded fasteners may be made from at least one of metals, thermoplastics, composites, and combinations thereof, with the understanding that a dose of hardenable sealant contacting the fastener exterior surface does not adversely affect the fastener material.

[0070]

[0082] According to further aspects herein, the hardenable sealant dose and the at least partially cured protective shell may be made of the same or different material(s), as described herein. When the hardenable sealant dose and the at least partially cured protective shell are made of different materials, according to aspects herein, the hardenable sealant dose and the at least partially cured protective shell will share a common chemical nature. In that case, the hardenable sealant dose, the uncured wet sealant, and the at least partially cured protective shell will include similar and compatible chemical nature or have the same chemical nature (e.g., include the same compound "class" or include the same compounds, compositions, etc.).

[0071]

[0083] 5, 6, 7, 8, and 9 are flow charts outlining methods according to several present embodiments.

[0072]

[0084] 5 outlines a method 100 according to some present embodiments, where method 100 includes adding 102 a hardenable sealant dose to a fastener at a fastener facing region, and forming 104 a fastener loaded with hardenable sealant. Method 100 further includes forming an at least partially cured protective shell at a hardenable sealant dose / at least partially cured protective shell interface to completely encase (equivalently referred to herein as "encapsulating") the hardenable sealant dose within the at least partially cured protective shell at the hardenable sealant dose / at least partially cured protective shell interface. According to method 100, the hardenable sealant dose and the at least partially cured protective shell include materials having a common chemistry, as described herein.

[0073]

[0085] As described herein, when it is desired to provide a polysulfide curable sealant as a sealant for a substrate (e.g., aircraft pre-assembly, aircraft assembly, etc.), the curable polysulfide sealant may be used as a "dose" to coat a fastener. Accordingly, FIG. 6 outlines a method 200 according to several present embodiments. In that case, the method 200 includes applying 102 a curable sealant, which may be a curable polysulfide sealant, to the fastener in the fastener facing region, and forming 104 a fastener doped with the curable sealant. The method 200 further includes coating 202 the curable sealant of the fastener doped with the curable sealant with a sealant detackifier (which may be, for example, a polysulfide sealant detackifier layer) that forms an at least partially cured protective shell.

[0074]

[0086] 7 outlines the method 300. The method 300 includes applying 302 a dose of UV-curable sealant to an exterior region of the fastener, and forming 304 a fastener loaded with the UV-curable sealant. The method 300 further includes forming 306 an at least partially UV-cured protective shell, e.g., by exposing an exterior surface of the UV-curable sealant dose to a short-term UV curing regimen to form an at least partially UV-cured protective shell having a thickness, e.g., in the range of about 1 mm to about 2 mm, while the remainder of the UV-curable sealant remains "wet" and uncured within the UV-cured protective shell.

[0075]

[0087] Figure 8 outlines a method 400 that includes the method 300 shown in Figure 7. The method 400 further includes at least partially UV curing 402 an outer region of the UV curable sealant dose to form an at least partially UV cured protective shell.

[0076]

[0088] The terms "at least partially cured" and "at least partially UV cured" refer to a state of cure where the cured material is not permitted to proceed to the point where the curing regimen has not progressed to a point where the material has undergone a near-complete or complete polymerization as evidenced by a near-complete or complete degree of cross-linking. According to some present embodiments, the degree of "partial cure" of the protective shell is selected to be sufficient to allow a pre-loaded fastener including the protective shell (e.g., a fastener including a dose of curable sealant having a protective shell formed thereon) to be handled, manipulated (including packaged, shipped, stored, etc.), and positioned for installation without the handling resulting in or otherwise risking rupture of the protective shell.

[0077]

[0089] The present embodiments recognize that full curing of the protective shell, whether UV cured or ambient (e.g., ambient / room temperature and temperature ranges, etc.), may not be necessary or desirable for the present purposes of facilitating the application of the sealant by preparing and installing a fastener loaded with the sealant. Indeed, as described herein, the inward force on the at least partially cured protective shell during fastener installation must be sufficient to rupture the protective shell, whereby installation of the fastener and rupture of the protective shell occur simultaneously and / or substantially simultaneously. That is, over-curing or fully curing the UV-curable material may result in the protective shell becoming robust enough to prevent proper release of the curable sealant dose, which should be avoided.

[0078]

[0090] 9 is a flow chart outlining a method 500 for assembling an aircraft assembly, where the method 500 includes providing 502 a plurality of components to be joined, e.g., in a subassembly, assembly, etc., and providing 504 a sealant-loaded fastener including a hardenable sealant dose and an at least partially cured protective shell configured to hold the hardenable sealant dose in an uncured state within the protective shell of the sealant-loaded fastener. The method 500 further includes placing 506 the sealant-loaded fastener, e.g., in an assembly, subassembly, etc., to join the plurality of components, substantially simultaneously rupturing 508 the at least partially cured protective shell, substantially simultaneously releasing 510 a quantity of the curable sealant dose from the ruptured protective shell into the joined components, and curing 512 the released curable sealant dose.

[0079]

[0091] According to some present embodiments, the methods outlined in Figures 5, 6, 7, 8, and 9 may employ pre-loaded fasteners of at least the type shown in Figures 3C and 3D, which may be installed in assemblies of at least the type shown in Figures 4A and 4B, where such assemblies are installed in vehicles, including aircraft of at least the type shown in Figure 1.

[0080]

[0092] The term "substantially" as used herein means that a particular characteristic, parameter, or value need not be exactly achieved, but rather deviations or variations (including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those skilled in the art) may occur to the extent that they do not eliminate the effect intended to be brought about by the feature.

[0081]

[0093] As used herein, the term "substantially simultaneously" means that a particular event occurs "concurrently" with or "substantially simultaneously" with another event, where the two events occur together in real time, or at least very close together in time.

[0082] The present aspects can, of course, be embodied in other ways than those specifically set forth herein without departing from the essential characteristics of the disclosure. The present aspects are to be considered in all respects as illustrative and non-restrictive, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. A fastener (40) for use in the manufacture of an aircraft assembly (41), comprising: a fastener outer surface (21) including a fastener outer surface region (26a); a dose of hardenable sealant (30) configured to coat at least a portion of said fastener exterior surface area (26a); an at least partially cured protective shell (32) comprising a first chemical composition in an at least partially cured state and configured to substantially completely encapsulate the hardenable sealant dose (30) within the at least partially cured protective shell (32); the curable sealant dose (30) is stored in an uncured state within the at least partially cured protective shell (32); The fastener, wherein the hardenable sealant dose and the at least partially cured protective shell comprise at least one of the same material and chemically compatible materials.

2. The fastener of claim 1 , wherein the fastener is made from at least one of a metal, a thermoplastic material, a composite material, and combinations thereof.

3. The fastener of claim 1 further comprising a curable sealant / at least partially cured protective shell interface (33).

4. The fastener of claim 1 , wherein the hardenable sealant dose and the at least partially cured protective shell comprise a hardenable material.

5. The fastener of claim 4 , wherein the curable sealant dose comprises a polysulfide and the at least partially cured protective shell comprises a polysulfide-based sealant detackifier.

6. 5. The fastener of claim 4, wherein the curable sealant dose comprises a UV-curable sealant in an uncured state and the at least partially cured protective shell comprises the UV-curable sealant in a partially cured state.

7. The fastener of claim 6, further comprising a UV curable sealant / at least partially UV cured material protective shell interface (33).

8. The fastener of claim 1 , wherein the curable sealant dose comprises an average thickness ranging from about ⅛ inch to about ¼ inch.

9. The fastener of claim 1 , wherein the at least partially cured protective shell comprises an average thickness in the range of about 1 mm to about 2 mm.

10. The fastener of claim 1 , wherein the at least partially cured protective shell is configured to rupture upon application of a pressure in the range of about 275 psi to about 400 psi.

11. An aircraft preassembly (40), comprising: a substrate (40c) including a plurality of components (40a, 40b), the plurality of components being configured to receive fasteners installed to join the plurality of components; and (b) an installed curable sealant loaded fastener (36a), the fastener (36a) being sized to join the plurality of components, the installed curable sealant loaded fastener (36a) comprising: a rupturable at least partially cured protective shell configured to rupture simultaneously during installation of the installed curable sealant loaded fastener into the aircraft preassembly, the rupturable at least partially cured protective shell including a first chemical composition; and an expelled dose of hardenable sealant configured to be expelled from the ruptured at least partially cured protective shell, the expelled dose of hardenable sealant including the first chemical composition.

12. 12. The aircraft preassembly of claim 11, wherein the burstable at least partially cured protective shell is configured to burst upon application of a pressure in the range of about 275 psi to about 400 psi during installation of the installed curable sealant loaded fastener.

13. 12. The aircraft preassembly of claim 11, wherein the curable sealant comprises a polysulfide-based sealant and the ruptured at least partially cured protective shell comprises a polysulfide-based sealant detackifier.

14. 12. The aircraft preassembly of claim 11, wherein the curable sealant comprises a first UV curable sealant in an uncured state, and the ruptured at least partially cured protective shell comprises a layer of the first UV curable sealant in an at least partially cured state.

15. A method (100) for making a fastener for an aircraft assembly, comprising: applying a dose of a hardenable sealant to a fastener facing region of the fastener (102); forming a fastener loaded with a hardenable sealant (104), the fastener loaded with a hardenable sealant including a fastener facing region loaded with a hardenable sealant (104); forming (106) an at least partially cured protective shell configured to encase the dose of curable sealant in an uncured state in an area of ​​a fastener exterior to which the curable sealant has been applied.

16. 16. The method (200) of claim 15, further comprising coating (202) the fastener exterior area to which the curable sealant has been added with a sealant detackifier layer, wherein the at least partially cured protective shell comprises the sealant detackifier layer.

17. 20. The method (300) of claim 15, wherein the curable sealant dose comprises a UV curable material.

18. 20. The method (200) of claim 16, wherein the curable sealant dose comprises a polysulfide-based material and the sealant detackifier layer comprises a polysulfide-based material.

19. 20. The method (400) of claim 17, further comprising partially curing (402) an outer region of the UV curable material curable sealant dose to form the at least partially cured protective shell.

20. A fastener made according to the method of claim 15.

21. 16. An aircraft assembly comprising a fastener made according to the method of claim 15.

22. An aircraft comprising a fastener made according to the method of claim 15.

23. A method (500) for assembling an aircraft assembly, comprising: Providing (502) a plurality of components, the plurality of components configured to receive fasteners installed to join the plurality of components; Providing (504) a fastener configured to join the plurality of components, the fastener comprising: providing a fastener (504) including an outer fastener surface including a dose of a hardenable sealant, the fastener further including an at least partially cured protective shell configured to completely encase the dose of hardenable sealant in an uncured state; Installing the fastener (506) to join the components; and rupturing the at least partially cured protective shell (508) simultaneously with installing the fastener; and expelling (510) a selected amount of the curable sealant dose from the ruptured protective shell to produce an expelled curable sealant dose; and curing (512) the dispensed dose of curable sealant to form the aircraft assembly; The method, wherein the curable sealant dose and the at least partially cured protective shell comprise a common chemical compound.

24. An aircraft assembly (41) made according to the method of claim 23.

25. An aircraft (10) comprising an aircraft assembly (41) made according to the method of claim 23.

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