Abstract:
A method for assembling wings includes supporting a pair of wing spars, which include a plurality of coordination features, upon a pair of stanchions in a generally horizontal position. A plurality of ribs and wing panels are accurately fastened to the pair of wing spars at a first workstation using the coordination features to position accurately the parts. The combination is transferred to downstream workstations via a ground transport vehicle for further processing and assembly to define a pulsed flow wing assembly system.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a method of assembling aircraft systems and, more particularly, relates to a method of assembling aircraft wings, stabilizers, or other major aircraft systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    Conventional manufacturing techniques for assembling components and subassemblies to produce airplane wings to a specified contour rely on fixtured “hardpoint” tooling techniques utilizing floor assembly jigs and templates to locate and temporarily fasten detailed structural parts together to locate the parts correctly relative to one another. This traditional tooling concept usually requires primary assembly tools for each subassembly produced, and two large wing major assembly tools (left and right) for final assembly of the subassemblies into a completed wing.  
           [0003]    The assembly tooling is intended to accurately reflect the original engineering design of the product, but there are many steps between the original design of the product and the final manufacture of the tool, so it is not unusual that the tool as finally manufactured produces missized wings or wing components that would be outside of the dimensional tolerances of the original wing or wing component design unless extensive, time consuming and costly hand work is applied to correct the tooling-induced errors. More seriously, a tool that was originally built within tolerance can distort out of tolerance from the hard use it typically receives in the factory. Moreover, dimensional variations caused by temperature changes in the factory can produce a variation in the final part dimensions as produced on the tool, particularly when a large difference in the coefficient of thermal expansion exists between the tooling material and the wing material, as in the usual case where the tooling is made of steel and the wing components are made of aluminum or titanium. Since dimensions in airplane construction are often controlled to within 0.005″, temperature induced dimensional variations can be significant.  
           [0004]    Wing major tooling is expensive to build and maintain within tolerance, and requires a long lead-time to design and build. The enormous cost and long lead-time to build wing major tooling is a profound deterrent to redesigning the wing of an existing model airplane, even when new developments in aerodynamics are made, because the new design would necessitate rebuilding all the wing major tools and some or all of the wing component tooling.  
           [0005]    The capability of quickly designing and building custom wings for airline customers having particular requirements not met by existing airplane models would give an airframe manufacturer an enormous competitive advantage. Currently, that capability does not exist because the cost of the dedicated wing major tooling and the factory floor space that such tooling would require are prohibitively expensive. However, if the same tooling that is used to make the standard wing for a particular model could be quickly and easily converted to building a custom wing meeting the particular requirements of a customer, and then converted back to the standard model or another custom wing design, airplanes could be offered to customers with wings optimized specifically to meet their specific requirements. The only incremental cost of the new wing would be the engineering and possibly some modest machining of headers and other low cost tooling that would be unique to that wing design.  
           [0006]    The disadvantages of manufacturing processes using hard tooling are inherent. Although these disadvantages can be minimized by rigorous quality control techniques, they will always be present to some extent in the manufacture of large mechanical structures using hard tooling. A determinant assembly process has been developed and is in production for airplane fuselage manufacture, replacing hardpoint tooling with self-locating detail parts that determine the configuration of the assembly by their own dimensions and certain coordinating features incorporated into the design of the parts. This new process, shown in U.S. Pat. No. 5,560,102 entitled “Panel and Fuselage Assembly” by Micale and Strand, has proven to produce far more accurate assemblies with much less rework. Application of the determinant assembly process in airplane wing manufacture should yield a better process that eliminates or minimizes the use of hard tooling while increasing both the production capacity of the factory and increasing the quality of the product by reducing part variability while reducing the costs of production and providing flexibility in making fast design changes available to its customers. These improvements would be a great boon to airframe manufacturers and its customers and would improve the manufacturer&#39;s competitive position in the marketplace. The present invention is a significant step toward such a process.  
         SUMMARY OF THE INVENTION  
         [0007]    According to the principles of the present invention, an advantageous method of assembling an aircraft wing is provided. The method employs modular vehicles in an autonomous, ground-based transportation system to reduce cycle time. These vehicles operate synchronously relative to each other and increase flexibility and reduce the amount of necessary floor space. Variation between parts and the associated costs of assembly are reduced through this method of progressive assembling the aircraft wing through a number of assembly stations using single piece flow and determinant assembly for part to part indexing. Additionally, the present invention provides a method of horizontally building an aircraft wing, which eliminates the high costs associated with scaffolding, tools, and fall protection associated with conventional build methods.  
           [0008]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a perspective schematic view illustrating an assembly method for an aircraft wing in accordance with the principles of the present invention;  
         [0011]    [0011]FIG. 2 is a perspective schematic view illustrating the assembly method of the pair of wing spars and ribs;  
         [0012]    [0012]FIG. 3 is a perspective schematic view illustrating the moving of the lower wing panel on the automated ground vehicle;  
         [0013]    [0013]FIG. 4 is a perspective schematic view illustrating the positioning of the lower wing panel below the egg crate assembly;  
         [0014]    [0014]FIG. 5 is a perspective schematic view illustrating the drilling of the lower wing panel and egg crate assembly;  
         [0015]    [0015]FIG. 6 is a perspective schematic view illustrating the positioning of the upper wing panel above the egg crate assembly;  
         [0016]    [0016]FIG. 7 is a perspective schematic view illustrating the drilling of the upper wing panel and egg crate assembly;  
         [0017]    [0017]FIG. 8 is a perspective schematic view illustrating the separation of the upper wing panel and the lower wing panel from the egg crate assembly;  
         [0018]    [0018]FIG. 9 is a perspective schematic view illustrating the loading of the lower wing panel and egg crate assembly upon the automated ground vehicle;  
         [0019]    [0019]FIG. 10 is a perspective schematic view illustrating the moving of the lower wing panel on the automated ground vehicle to the third workstation;  
         [0020]    [0020]FIG. 11 is a perspective schematic view illustrating the finishing and fastening of the lower wing panel to the egg crate assembly;  
         [0021]    [0021]FIG. 12 is a perspective schematic view illustrating the finishing and fastening of the upper wing panel to the egg crate assembly;  
         [0022]    [0022]FIG. 13 is a perspective schematic view illustrating the moving of the wing to the fourth workstation;  
         [0023]    [0023]FIG. 14 is a perspective schematic view illustrating the boring and machining of the wing; and  
         [0024]    [0024]FIG. 15 is a perspective schematic view illustrating the fastening of fittings and the like to the wing. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. That is, it is contemplated that this invention has general application to the assembly of parts into major assemblies where adherence to a specified set of dimensional tolerances is desired, particularly where some or all of the parts and subassemblies or flexible or semi-flexible.  
         [0026]    Referring now to the drawings, where like reference numerals designate identical or corresponding parts, perspective schematic drawings illustrate the major process steps in the wing assembly system  10  according to the principles of the present invention. The process begins with building the major components of the wing, including upper and lower wing panels  30  and  32 , a rear spar  34 , a front spar  36 , and in-spar ribs  38 . The major components are brought together on an automated ground vehicle  40  and assembled as a wing or stabilizer  42  in the horizontal position at a plurality of workstations. The present invention provides a number of advantages over conventional methods. For example, the present invention is capable of employing determinant assembly to limit the need for large tooling, such as wing majors and the like, which may reduce cost by more than 50 percent. Additionally, the present invention is capable of eliminating duplicate processes through the use of a single piece flow, which further enables a one-day manufacturing rate. Still further, the present invention reduces recurring costs through the use of reconfigurable mechanisms. Moreover, the present invention is capable of being quickly and conveniently modified in order to cost effectively manufacture custom wing designs.  
         [0027]    According to the present embodiment, the assembly of horizontal stabilizer  42  is completed at four separate and distinct workstations. Each workstation is responsible for the assembly, processing, and/or preparation of the horizontal stabilizer  42 . Each of the workstations is described in detail with reference to the following figures.  
         [0028]    With particular reference to FIG. 2, it should be appreciated that the following assembly method employs the determinant assembly process described in detail in U.S. Pat. Nos. 5,560,102 and 6,314,630, which are commonly assigned to the assignee of the present application. The disclosures of which are incorporated herein by reference. A rear spar  34  and front spar  36  are each coupled to and supported by a plurality of support stanchions  44 . Support stanchions  44  each includes at least one support bracket  46  that is coupled to rear spar  34  or front spar  36  at connection points  48 . Support stanchions  44  may be of any shape sufficient to support to the weight of the wing spar. Preferably, support stanchions  44  support rear spar  34  and front spar  36  in a generally horizontal position. This position provides a number of advantages over conventional assembly methods in that it reduces the need for large tooling, which typically extends vertically and requires the associated large-scale buildings and floor space.  
         [0029]    Rear spar  34  and front spar  36  each includes a plurality of holes  50  formed therethrough that are adapted to receive a fastener, such as an interference fastener. The plurality of holes  50  are preferably formed according to a predetermined tolerance such that at least some may be used to properly position in-spar ribs  38  relative thereto according to a predetermined layout, such as engineering drawings. As the plurality of support stanchions  44  support rear spar  34  and front spar  36 , in-spar ribs  38  are assembled therebetween according to known methods. That is, in-spar ribs  38  are mounted in a generally orthogonal position relative to rear spar  34  and front spar  36  and fasten thereto via a plurality of fasteners (not shown).  
         [0030]    As best seen in FIGS. 3 and 4, once rear spar  34 , front spar  36 , and the plurality of in-spar ribs  38  are coupled together to form an egg crate assembly  52 , lower wing panel  32  may then be brought into position below egg crate assembly  52 . More particularly, as seen in FIG. 3, lower wing panel  32  is positioned upon and supported by automated ground vehicle  40 . According to the present embodiment, automated ground vehicle  40  is operably coupled to a drive track  54  formed within the floor of the building. Automated ground vehicle  40  may include a plurality of contoured support fins  56 , which are configured to support a specific lower wing panel configuration. As should be appreciated from FIG. 4, the plurality of support stanchions  44  are configured such that automated ground vehicle  40  and lower wing panels  32  may be easily and conveniently positioned below egg crate assembly  52 .  
         [0031]    Lower wing panel  32  further includes a plurality of holes formed therein to properly position lower wing panel  32  relative to egg crate assembly  52 . Once lower wing panel  32  and automated ground vehicle  40  are positioned below egg crate assembly  52 , lower wing panel  32  is raised so as to come generally in contact with egg crate assembly  52 . At this point, lower wing panel  32  and egg crate assembly  52  may be further processed, which may include the drilling of lower wing panel  32  relative to egg crate assembly  52  using numerically controlled track drills. Finally, as each drilling zone is completed as seen in FIG. 5, lower wing panel  32  may be temporarily fasten to egg crate assembly  52  using temporary fasteners to form a wing box  58  for further processing at subsequent workstations.  
         [0032]    With particular reference to FIGS. 6 and 7, automated ground vehicle  40  transfers wing box  58  from workstation  1  to workstation  2  for the assembly of upper wing panel  30 . To this end, automated ground vehicle  40  positions wing box  58  generally adjacent an overhead material handling systems  60 . As best seen in FIGS. 1, 6, and  7 , overhead material handling system  60  is adapted to support upper wing panel  30  between workstations  2  and  3 . Overhead material handling system  60  includes a pair of outrigger supports  62  extending generally horizontal above wing box  58 . A plurality of support tethers  64  releasably couple upper wing panel  30  to the pair of outrigger supports  62 .  
         [0033]    Once automated ground vehicle  40  and wing box  58  are generally in position, overhead material handling systems  60  lowers upper wing panel  30  down on to wing box  58 . Upper wing panel  30  may now be drilled or otherwise finished using conventional finishing tools, such as numerically controlled track drills and the like.  
         [0034]    Following the finishing of upper wing panel  30 , upper wing panel  30  and lower wing panel  32  are removed from egg crate assembly  52 , as seen in FIG. 8. Upper wing panel  30  and lower wing panel  32  are removed from egg crate assembly  52  so as to enable the cleaning and deburring of upper wing panel  30  and lower wing panel  32 . During this time, egg crate assembly  52  is supported by support stanchions  44 ; however, is important to note that support stanchions  44  are taller than those used at the preceding workstation to provide additional workspace.  
         [0035]    Following the cleaning and deburring of the assembly parts, and any additional finishing that may be required, automated ground vehicle  40  is then actuated to raise lower wing panel  32  back into position adjacent egg crate assembly  52  and raise egg crate assembly  52  off support stanchions  44 . To this end, automated ground vehicle  40  includes a plurality of scissor-like linkages  66  that are power actuated to extend and to retract to facilitate such raising and lowering of lower wing panel  32  and egg crate assembly  52 .  
         [0036]    As best seen in FIG. 10, automated ground vehicle  40 , together with lower wing panel  32  and egg crate assembly  52 , is moved to workstation  3 . Simultaneously, overhead material handling systems  60 , together with upper wing panel  30 , is similarly moved to workstation  3 . Automated ground vehicle  40  is actuated to raise lower wing panel  32  and egg crate assembly  52 . Lower wing panel  32  and egg crate assembly  52  are then lowered upon precision index cones  68 . As seen in FIG. 11, automated ground vehicle  40  may then be removed to provide additional work area below lower wing panel  32 . Still referring to FIG. 11, lower wing panel  32  is then fay sealed and fasten to egg crate assembly  52  via permanent fasteners. This process can be conveniently completed from below lower wing panel  32  and egg crate assembly  52 .  
         [0037]    As seen in FIG. 12, upper wing panel  30  may then be fay sealed and fasten to egg crate assembly  52  via permanent fasteners. Following completion of the attachment of upper wing panel  32  to egg crate assembly  52 , automated ground vehicle  40  is then repositioned below now assembled wing  42  and actuated to raise wing  42  off precision index cones  68 .  
         [0038]    Automated ground vehicle  40  then transports wing  42  to workstation  4  and positions wing  42  upon additional precision index cones  68 . Automated ground vehicle  40  may then be removed to provide additional work area below and/or around wing  42  as shown in FIG. 13. With particular reference to FIGS. 14 and 15, a boring fixture  70  is then actuated and positioned adjacent to wing  42 . Boring fixture  70  bores rear spar  34  or front spar  36  for the attachment of hinge ribs, fittings, and/or the like.  
         [0039]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.