Abstract:
A method for fabricating a structure to include at least a portion of a conduit retention system is described. The method includes receiving parameters for the structure and the portion of the conduit retention system associated with the structure via a user interface, providing the parameters to a machine configured to fabricate the structure and incorporate the portion of the conduit retention system, the machine using a direct manufacturing process, and operating the machine to integrally fabricate the structure and the portion of the conduit retention system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to manufacturing of composite structures, and more specifically, to methods for system component installation utilizing direct manufactured components. 
         [0002]    Components of various systems, for example, components of aircraft systems, are typically installed by attaching such components to a structure of the device into which they are being installed. This attachment is typically accomplished using, for example looped band clamps, or clamp blocks with cylindrical pockets. These clamp examples and other embodiments are sometimes collectively referred to as retention devices. Such retention devices are typically sized to match, for example, an outside diameter of the system components which they are to retain. Examples of these system components include, but are not limited to, one or more of hydraulic lines, electrical conduit, pneumatic lines, and air handling ductwork. These system components, which for ease of illustration and description are collectively referred to herein as conduit, are typically installed by attaching at least a portion of the retention devices to a fuselage or other structure, and then operating the retention device to retain the conduit in a desired position. 
         [0003]    One conventional retention method utilizes angle brackets that are attached to a structure of the device into which they are being installed (e.g., the fuselage or other aircraft structure). The angle brackets are oriented in such a manner as to facilitate the routing path of the conduit. Installation of these angle brackets is time consuming as installation usually entails determining a proper location for installation, drilling of fastener holes through the angle bracket and structure, and installation of fasteners through the drilled holes. Typically, attachment of angle brackets to the structure is accomplished utilizing rivet fasteners, though other fasteners may be used. Continuing with the example, plate nuts are mounted on the angle brackets which provide a way to attach respective portion of the looped band clamps or clamp blocks with another fastener, such as a captive screw or bolt. Clamp blocks are typically utilized where a plurality of conduit lines are routed together along the same path. However, these clamp blocks are typically fabricated using a solid metallic material and therefore are not a lightweight solution for conduit restraint. Installation of such retention devices is considered a secondary operation. Secondary operations add costs, time, weight, and usually result in increased part counts. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In one aspect, a method for fabricating a structure to include at least a portion of a conduit retention system is provided. The method includes receiving parameters for the structure and the portion of the conduit retention system associated with the structure via a user interface, providing the parameters to a machine configured to fabricate the structure and incorporate the portion of the conduit retention system, the machine using a direct manufacturing process, and operating the machine to integrally fabricate the structure and the portion of the conduit retention system. 
         [0005]    In another aspect, a conduit retention system is provided that includes a conduit support saddle formed integrally with a directly manufactured structure, and a conduit clamp configured to engage the conduit support saddle and retain at least one conduit therebetween. 
         [0006]    In still another aspect, a conduit retention system is provided. The conduit retention system includes a conduit support saddle comprising at least one substantially semi-circular conduit support area and a relatively flat surface area, and a conduit clamp comprising at least one substantially semi-circular perimeter and at least one clip. The semi-circular conduit support area and semi-circular conduit support area are configured to substantially surround a diameter of a conduit when the at least one clip is engaged with the flat surface area in a snap fit relationship. The conduit support saddle is formed integrally as a portion of a directly manufactured structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is an illustration of a system utilized in the direct manufacture of composite structures. 
           [0008]      FIG. 2  is an illustration of a retention device which attaches cylindrical members, such as conduit, to a structure. 
           [0009]      FIG. 3  is an illustration of a structure that includes a portion of a retention device directly manufactured therein. 
           [0010]      FIG. 4  is an illustration of a structure that includes support saddles directly manufactured as a portion of the structure. 
           [0011]      FIG. 5  is an enlarged illustration of a conduit clamp. 
           [0012]      FIG. 6  is an exploded view of the direct manufactured retention system of  FIGS. 3-5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Described herein are methods that fill the need for lightweight and inexpensive composite structures while also reducing a need for the above described secondary operations for the installation and retention of conduit and other “routing” type structures. In practice, utilization of the described methods result in structures that typically include integrally formed saddles that form a portion of a retention mechanism. These retention mechanisms may also include a separately fabricated clamp that attaches to the saddle to retain the conduit in a desired location. Such a retention mechanism provides a lightweight and cost effective solution to the secondary operations that are described above while also reducing the labor needed to install the conduit. 
         [0014]      FIG. 1  is an illustration of a system  10  utilized in the direct manufacture of structures  12  in accordance with the methods described herein. In one embodiment, system  10  includes a direct manufacturing assembly  14 , for example, a selective laser sintering assembly, to generate the desired structure (or structures)  12  in a single build run which is controlled utilizing a computer assembly  15 . At least in the selective laser sintering example, direct manufacturing assembly  14  incorporates a laser  16  to integrally fabricate solid structures within a build chamber  18  during the build run. 
         [0015]    Selective laser sintering (SLS) is a process for generating a material from a powdered sintering compound, and is one type of direct manufacturing process. In the SLS process, the powdered compound is distributed onto a surface within build chamber  18 , and laser  16 , is directed onto at least a portion of the powder, fusing those powder particles together to form a portion of a sintered material. Successive layers of the powder are distributed onto the surface, and the laser sintering process continues, fusing both the particles of the powdered material together into layers and the adjacent layers together, until the fused layers of laser sintered material are of a shape and thickness as appropriate for the intended use of the material. 
         [0016]    Through laser sintering of polymer materials, integral features may be incorporated into structures including, but not limited to complex shapes and integrated external features that may be utilized to replace the above described angled brackets and clamping blocks. Although laser sintering has been described, other layer build, or direct manufacturing methodologies are contemplated. 
         [0017]    However, to appreciate the benefits of direct manufacturing and directly manufactured structures, a description of a conventional structure and associated conduit attachment and retention methods is illustrative. To that end,  FIG. 2  is an illustration of a fuselage or other similar structure  60  that includes integrally formed ribs  62  that provide strengthening for structure  60 .  FIG. 2  also includes two hollow cylindrical members  70  and  72 . Cylindrical members  70  and  72  are representative of one or more of hydraulic lines, electrical conduit, pneumatic lines, and air handling ductwork which for ease of description are simply referred to herein as conduit. To maintain a position of conduits  70  and  72  they are to be attached to structure  60 . To accomplish this attachment, angle brackets  80  are attached to one or more of ribs  62 , and clamp blocks  82  consisting of an angle bracket engaging member  84  and a retaining member  86  are attached to each angle bracket  80 . As seen from the illustration of  FIG. 2 , both angle bracket engaging member  84  and retaining member  86  are fabricated with semi-circular indentations  90  in their respective perimeters for holding conduits  70  and  72  in place once installed. Retaining member  86 , in the embodiment illustrated, includes a captive fastener  92  which interfaces with angle bracket engaging member  84 . As captive fastener  92  is tightened, retaining member  86  is drawn to angle bracket engaging member  84  providing the retention for conduits  70  and  72 . 
         [0018]    The embodiment of  FIG. 2  is one typically utilized retention system. As described above, aircraft systems such as hydraulic lines, electrical conduit, pneumatic lines, and air handling ductwork are typically installed using either looped band clamps or clamp blocks with cylindrical pockets sized to match the tubing or system diameter being retained. Consistent with the illustration of  FIG. 2 , these conventional attachment methods generally require angle brackets attached to the aircraft structure and oriented in such a manner as to facilitate the routing of the members that are similar to conduits  70  and  72 . While described as cylindrical, it is understood that conduits that are retained by these retaining structures may be of nearly any shape. However, angle brackets  80 , and similarly functioning devices, typically require time consuming positioning, drilling of fastener holes through the angle bracket and structure, and then installation of fasteners to attach the angle bracket to the structure as above described. 
         [0019]    While these methods and structures illustrated by  FIG. 2  have suited the needs for restraining routed system components such as conduits  70  and  72 , emerging technologies such as the direct manufacturing process described above introduces the possibility of an alternative conduit retention methodology. For example, elegant, lightweight and inexpensive solutions to these otherwise accepted conduit retention conventions may be fabricated utilizing direct manufacturing processes. An example directly manufactured embodiment, similar in function to the conventional structure described with respect to  FIG. 2 , is further described below. More specifically, the direct manufacturing process utilizes a laser beam, in one embodiment, to sinter a media, or compound, such as titanium or a variety of polymers. Alternatively, the media can include fused polymers deposited in a three-dimensional form as dictated by the definition of the structure(s) to be fabricated. 
         [0020]    Particularly,  FIG. 3  is an illustration of a structure  100  that includes a portion of a retention device directly manufactured therein. More specifically and as further explained below, ribs  102  of structure  100  are configured with support saddles  104 , which in the illustrated embodiment are semi-circular for at least partial insertion and retention of conduits  70  and  72 . A conduit clamp  106  also includes one or more substantially semi-circular perimeters  110  and  112  and a clip  120 , respectively, for engagement of conduits  70  and  72  and attachment of the conduit clamp  106  to the support saddle  104 . In the illustrated embodiment, a clip  120  is included on each side of conduit clamp  106 . 
         [0021]      FIG. 4  is a further illustration of structure  100 . As inferred above, structure  100  is representative of a portion of an airframe fuselage or other similar structure.  FIG. 4  provides a clear view of support saddles  104  which are integrally manufactured as a portion of structure  100 . As can be seen in the illustration, support saddles  104  are substantially wider than the ribs  102 , thereby providing a larger area of engagement between the conduits ( 70  and  72 ) to be supported and the support saddles  104 . Referring specifically to support saddles  104 , each includes a first conduit support area  114  and a second conduit support area  116  which are substantially semi-circular. Between conduit support areas  114  and  116  is a relatively flat surface area  118  which is utilized for engagement of a clip as further described below. The direct manufacturing process, an example of which is selective laser sintering, can be utilized to integrally fabricate saddles or pockets into a structure that, in conjunction with a conduit clamp, engages and retains in position, for example, conduits  70  and  72 , shown in  FIG. 3 . 
         [0022]      FIG. 5  is an enlarged illustration of conduit clamp  106 . As described above, conduit clamp  106  includes portions that are semi-circular in cross-section. These portions are referred to herein as semi-circular perimeters  110  and  112  and are configured for retention of conduits  70  and  72 . Again, while described herein as semi-circular it is understood that clip  106  may be configured to retain items that have any different cross-sectional shape. Each clip  120  includes a barbed protrusion  122  extending therefrom which is operable for attachment of the conduit clamp  106  to the flat surface area  118  (shown in  FIG. 4 ) of the support saddle  104  between support areas  114  and  116  in a snap-fit relationship. Conduit clamp  106  is strengthened by a rib  126  that extends between an outer diameter of perimeters  110  and  112 , substantially down a center of conduit clamp  106 . It is to be noted that conduit clamp  106  can also be fabricated using the direct manufacturing techniques described herein. 
         [0023]      FIG. 6  is an exploded view of the direct manufactured retention system described with respect to  FIGS. 3-5 . As can be seen, in one embodiment, conduits  70  and  72  are configured with dampening cushions  130  that are “sandwiched” between the conduit support areas  114  and  116  of support saddle  104  and the semi-circular perimeters  110  and  112  of conduit clamp  106 . In a specific embodiment, dampening cushions  130  are fabricated from rubber. 
         [0024]    With regard to SLS, fabrication of structure  100  is accomplished in successive layers being “sintered” together. Assuming the structure  100  is fabricated from the bottom up, relative to the illustrations shown in the figures, the sintering compound would be distributed in a rectangular pattern within build chamber  18  (shown in  FIG. 1 ), to begin formation of a base  140  of the structure  100 . The rectangular distribution of sintering compound and successive sintering continues until base  140  is completed. The distribution of powder gradually is changed until the ribs  102  are being formed along with a back  150  of structure  100 . At a certain point the powder distribution is changed to begin fabrication of support saddles  104 . Once the layers that include portions of support saddles  104  are completed, the sintering compound is distributed to complete ribs  102  and gradually begin fabrication of a rectangular top  160  of structure  100 . The process continues and successive layers are built up until fabrication of the structure  100  is complete. It should be noted that structure  100  could be fabricated in any “direction” including from top to bottom, from front to back, or from back to front, depending on the dimensions of structure  100  and the dimensions of build chamber  18 . A similar process is easily applicable to conduit clamp  106 , which also may be fabricated through a direct manufacturing process such as SLS. 
         [0025]    In an exemplary embodiment, the components described herein are fabricated utilizing selective laser sintering and a powdered compound that is configured to be utilized in the selective laser sintering process. This process allows for fabrication of structures and components that are directly manufactured while also including elegant attachment components that typically cannot be directly manufactured with conventional machining methods. The SLS process allows for subcomponents, for example, tubing clamps to be embedded into the structure providing a lower overall profile since there are no angle brackets and additional clamp mechanisms that require space. 
         [0026]    The embodiments described herein provide a self-locating and maintainable configuration for attaching parts to the structure of an aircraft, for example. While sometimes described in terms of attaching components to an aircraft or the fuselage of an aircraft, it is understood that the methods are transferable to other applications. The described structures and substructures are manufactured using an additive manufacturing process, which is sometimes referred to as a direct manufacturing process. In the specific embodiments described herein, the receiving structure is directly built into the substructure (e.g., support saddles  104  and structure  100 ). The mating clamps, (i.e., for example conduit clamps  106 ) can also be fabricated utilizing an additive manufacturing process. 
         [0027]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.