Patent Application
20090283640
The disclosure relates to techniques for attaching structural elements to each other. More particularly, the disclosure relates to an attachment system and method which are particularly suitable for attaching hardware or systems supports to a composite structure.
Conventional methods of attaching hardware and systems supports to a composite structure may require the use of either removable fasteners (bolts) or permanent hi-lock style fasteners (bolts) to attach a support bracket to the composite structure. The fasteners may each have a smooth shaft with a threaded portion. Using this approach, an installer may need to ensure that the smooth shaft portion of each fastener extends beyond the stack-up between the support bracket and the composite structure. In some cases, depending on the combination of fasteners used and fastener length, an additional washer may be required to ensure that no threads are in bearing common to the fastener openings in the support bracket and composite structure and to ensure that the fastener can be torqued as required. If removable fasteners are used, installation may require that a driver and a wrench be positioned on opposite sides of the assembly to torque the fastener and prevent rotation of the nut on the fastener, respectively.
Utilization of hi-lock style fasteners may allow torquing from one side of the structure but require a special hi-lock wrench tool. Regardless of the fastener used, the existing method may take longer to gather the proper hardware for various structure gages. Furthermore, the existing method may render it easier to drop the hardware during installation and may require more parts for installation.
Composite structures throughout an airplane may vary in gauge due to weight efficiency initiatives which may gauge the structure up only where needed to support load paths. This may render difficulty in using shanked bolts using the traditional method of attaching hardware and systems supports to a composite structure. Much time may be necessary to ensure that the varying stack-ups of the components were accounted for in the specific fastener length call out and washer stack-up in both design and manufacturing processes.
The disclosure is generally directed to an attachment system. An illustrative embodiment of the attachment system includes a dual sleeve nut comprising at least two spaced-apart nut housings; at least two interiorly-threaded fastener openings extending through the nut housings, respectively; a sleeve extending from the base of the nut housing and a nut base connecting the nut housings. At least two threaded fasteners extend through the fastener openings, respectively, of the nut housings.
The disclosure is further generally directed to a method of attaching a bracket or system support to a composite structure. An illustrative embodiment of the method includes providing a dual sleeve nut comprising spaced-apart nut housings, a nut base connecting the nut housings, nut sleeves extending from the nut housings, respectively, and interiorly-threaded fastener openings extending through the nut housings and the nut sleeves, respectively; providing a composite structure having at least two fastener openings; providing a bracket having at least two fastener openings; inserting the nut sleeves of the dual sleeve nut through the fastener openings, respectively, of the composite structure; providing at least two threaded fasteners; and inserting the threaded fasteners through the fastener openings of the bracket, through the sleeves of the dual sleeve nut and threading the threaded fasteners in the interiorly-threaded fastener openings in the nut housings, respectively, of the dual sleeve nut.
Referring initially to
The attachment system 1 may include a generally elongated dual sleeve nut 2 which may be a single monolithic piece and may be a thermoplastic or composite material. The dual sleeve nut 2 may include at least two spaced-apart, generally cylindrical nut housings 3, each having an fastener opening 4 which further extend through each corresponding nut sleeve 6. A threaded insert 4a may be provided in the insert opening 4. A nut base 5 may connect the nut housings 3. As shown in
As shown in
In typical application, the attachment system 1 attaches the bracket 16 to the composite structure 12. Accordingly, the bracket 16 may be placed against a first surface A of the composite structure 12 with the fastener openings 17 in the bracket 16 disposed in alignment with the respective fastener openings 13 in the composite structure 12. The nut sleeves 6 of the dual sleeve nut 2 may be inserted through the respective fastener openings 13 in the composite structure 12, as shown in
It will be appreciated by those skilled in the art that the nut sleeves 6 of the dual sleeve nut 2 may seal off the composite structure 12 and protect the composite structure 12 from the threads of the respective threaded fasteners 20. Each nut sleeve 6 may also provide indexing common to the fastener openings 13 in the composite structure 12 which aide in holding in place during installation. The nut sleeves 6, in combination with the nut base 5 and the reinforcing rib 8 of the dual sleeve nut 2, also provides an anti-rotation feature that provides a shop aide for torquing of the fasteners 20 during installation of the bracket 16 on the opposite surface of the composite structure 12. Installation of the dual sleeve nut 2 may allow the installer to torque the fasteners 20 from one side of the composite structure 12 using standard tools (such as a nut driver or socket wrench, for example and without limitation).
The attachment system 1 may enable an installer to torque the fasteners 20 without having to secure the dual sleeve nut 2 with a wrench such as must be done for a conventional method with a standard nut. Furthermore, the attachment system 1 may protect and seal the composite structure 12 from full-threaded fasteners 20 and incompatible metallic materials and finishes. The attachment system 1 may provide fewer parts in the assembly process and reduce the possibility of dropping and losing parts during the installation.
Referring next to
Referring next to
Referring next to
Each of the processes of method 78 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
The apparatus embodied herein may be employed during any one or more of the stages of the production and service method 78. For example, components or subassemblies corresponding to production process 84 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 94 is in service. Also, one or more apparatus embodiments may be utilized during the production stages 84 and 86, for example, by substantially expediting assembly of or reducing the cost of an aircraft 94. Similarly, one or more apparatus embodiments may be utilized while the aircraft 94 is in service, for example and without limitation, to maintenance and service 92.
Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.
