Abstract:
A composite layup is formed on a tool and placed on a contoured part. The tool is contoured to substantially match the contour of the part. A set of location data is generated which represents the location of the part in space relative to the tool. An automated manipulator uses the location data to move the tool into proximity to the part and place the contoured layup on the part.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to co-pending U.S. patent application Ser. No. 11/829,900 filed Jul. 28, 2007, and Ser. No. 12/242,477 filed Sep. 30, 2008, which applications are incorporated by reference herein in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure generally relates to fabrication of composite parts, and deals more particularly with a method and apparatus for forming and applying composite layups such as doublers, to part surfaces having complex geometries. 
       BACKGROUND 
       [0003]    Automated fiber placement (AFP) machines may be used to layup composite laminate structures comprising multiple plies of one of more fiber orientations. Where the entire structure is fabricated using an AFP machine, the build rate may be dependant upon the speed of the AFP machine, since the plies are normally formed sequentially. In order to accelerate the build process, certain segments of the structure may be built by hand and applied to the structure as preassembled kits. For example, doublers may be preassembled and applied by hand as a subtask during the AFP build sequence. However, preassembling doubler layups by hand can be time consuming and difficult, particularly where the doublers must be applied to a structure having surface complex geometries, such as a multi-contoured nose or tail section of an airplane. Prior attempts to preassemble doublers using automated equipment have been limited to layups that are either flat or which have a constant curvature in one dimension. 
         [0004]    Accordingly, there is a need for a method and apparatus for forming and applying layups such as doublers to composite structures having complex surface geometries which include multiple contours. 
       SUMMARY 
       [0005]    The disclosed embodiments provide a method and apparatus for forming and applying layups on composite structures having complex shapes, such as multi-contoured parts. Layup, application and compaction requirements are integrated into a process that may use a single tool. The layups may be quickly formed to match the geometry of the part surface using an AFP machine to layup composite material on a tool having a multi-contoured tool face substantially matching the part surface. The tool may also be used to place and compact the layup on the part surface. The disclosed method and apparatus allows layups such as doublers to be fabricated off a main assembly line, thus permitting them to be reworked as necessary and inspected without slowing down the main assembly process. 
         [0006]    According to one disclosed embodiment, a method is provided of forming and placing a composite layup on a contoured part. The method includes forming a contoured composite layup on a tool contoured to substantially match the contour of the part. The method also includes generating a set of location data representing the location of the part relative to the tool. The method uses a manipulator and the location data to move the tool into proximity to the part and place the contoured layup on the part. Forming the contoured composite layup may be performed using an automatic fiber placement machine to automatically place composite material on the tool. The layup may be compacted against the part by inflating a bladder on the tool and/or by inflating a bag on the tool. The bag may be separated away from the compacted layup by deflating the bag. Generating the location data may be performed by determining the three-dimensional (3-D) position of the tool contour relative to the 3-D position of the part contour in a common 3-D reference system. 
         [0007]    According to another embodiment, a method is provided of applying composite doublers on a part having a multi-contoured surface. The method includes drawing a vacuum bag down onto a multi-contoured face of a tool substantially matching the contours of the part surface. Composite plies are laid up on the tool face over the bag. The method includes generating a set of location data representing the location of the tool face relative to the surface of the part. The method further comprises using the location data and a manipulator to automatically move the tool into proximity to the part and place the layup against the part surface. The method also includes compacting the layup against the part surface by inflating the bag. Drawing the bag down onto the tool face is performed by drawing a vacuum in the bag. 
         [0008]    According to still another embodiment, a method is provided of applying a layup on a part having a multi-contoured surface. The method includes drawing a flexible bag down onto a multi-contoured face of a tool substantially matching the contours of the parts surface. The method includes placing a composite layup on the bag-covered tool face and moving the tool into proximity to the part and using the tool to place the layup on the parts surface. The method also includes compacting the layup against the parts surface by inflating the bag and separating the bag from the compacted layup by drawing a vacuum in the bag. The method may further comprise compacting the layup against the parts surface by inflating a bladder between the tool face and the bag. 
         [0009]    According to still another embodiment, apparatus is provided for applying composite layups on a contoured substrate. The apparatus includes a tool, first and second compactors, and means for controlling the first and second compactors. The tool is adapted to be mounted on a manipulator for moving the tool into proximity to the substrate and includes a contoured tool face substantially matching the contour of the substrate. The first flexible compactor covers the tool face and is adapted to have a composite layup placed thereon. The second flexible compactor is disposed between the first compactor and the tool face for compacting the layup onto the substrate. The first compactor may include a vacuum bag sealed to the tool, and the second compactor may include a flexible, inflatable Bladder. The means for controlling the first and second compactors may include a pressure source, a vacuum source, and a controller for selectively pressurizing and depressurizing the first and second compactors using the pressure source and the vacuum source. 
         [0010]    In accordance with another embodiment, apparatus is provided for forming and applying composite layups on a part having a multi-contoured surface. The apparatus includes a tool having a multi-contoured face substantially matching the contours of the part surface, a flexible bag on the tool, a manipulator, and a controller. The flexible bag covers and conforms to the contours of the tool face and is adapted to have a layup placed thereon and pressurized to compact the layup against the part surface. The manipulator manipulates the tool into proximity to the part and places the layup on the part surface. The controller controls the operation of the manipulator and pressurization of the bag. The apparatus may further comprise an inflatable bladder between the tool face and the bag for compacting the layup against the part surface. In one embodiment, the tool is formed of structural foam. 
         [0011]    According to still another embodiment, apparatus is provided for forming and applying composite layups on a part having a multi-contoured surface. The apparatus includes a tool, a robotic manipulator, an automatic composite fiber placement machine, a locator system, a compactor, and control means. The tool includes a multi-contoured face substantially matching the contours of the part surface. The robotic manipulator has the tool mounted thereon for manipulating the tool. The automatic composite fiber placement machine includes a fiber placement head for forming a multi-ply composite layup on the tool face. The locator system generates a set of location data that locates the fiber placement head, the tool face and the part surface relative to each other in a common spatial reference system. The compactor on the tool compacts the layup against the part surface, and the control means controls the operation of the manipulator, the automatic fiber placement machine and the compactor, based on the location data. 
     
    
     
       BRIEF DESCRIPTION OF THE ILLUSTRATIONS 
         [0012]      FIG. 1  is an illustration of a functional block diagram of apparatus for forming and applying composite layups having complex geometries. 
           [0013]      FIG. 2  is an illustration of a perspective view of a multi-contoured nose section for an airplane having a composite doubler applied and compacted thereon in accordance with the disclosed embodiments. 
           [0014]      FIG. 3  is an illustration of an isometric view of a tool used to form and apply the doubler shown in  FIG. 2 , a compaction bag and bladder not shown for clarity. 
           [0015]      FIG. 4  is an illustration of a side view of apparatus for forming and applying composite layups having complex geometries to the nose section shown in  FIG. 2 . 
           [0016]      FIG. 5  is an illustration of a combined sectional and diagrammatic view of the tool and locator system. 
           [0017]      FIG. 6A  is a sectional view of the tool when initially assembled. 
           [0018]      FIG. 6B  is an illustration of a perspective view of the tool shown in  FIG. 6B . 
           [0019]      FIG. 7A  is an illustration similar to  FIG. 6A  but showing the bag having been drawn down against the tool surface. 
           [0020]      FIG. 7B  is an illustration similar to  FIG. 6B  but showing the bag having been drawn down against the tool surface. 
           [0021]      FIG. 8A  is an illustration of a sectional view of the tool showing an automatic fiber placement head forming a layup on the tool face. 
           [0022]      FIG. 8B  is an illustration of a perspective view of the tool, showing a layup having been partially formed on the tool face. 
           [0023]      FIG. 9A  is an illustration of a sectional view of the tool showing the layup having been placed on the part surface, and the tool bladder having been inflated to compact the layup against the part surface. 
           [0024]      FIG. 9B  is an illustration of a perspective view showing the tool placing the layup on the part surface. 
           [0025]      FIG. 10  is an illustration similar to  FIG. 9A  but showing the bag on the tool having been inflated to further compact the layup against the part surface. 
           [0026]      FIG. 11  is an illustration similar to  FIG. 10 , but showing the bag having been separated from the layup as a result of a vacuum being applied to the bag. 
           [0027]      FIG. 12  is an illustration of a flow diagram showing a method of forming and placing layups having complex geometries on a multi-contoured part surface. 
           [0028]      FIG. 13  is an illustration of a flow diagram of aircraft production and service methodology. 
           [0029]      FIG. 14  is an illustration of a block diagram of an aircraft. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Referring first to  FIGS. 1-3 , the disclosed embodiments relate to a method and apparatus for forming and placing a composite layup  20  on a substrate  22  having a complex geometry, which may comprise a multi-contoured surface  22  of the part  24  shown in  FIG. 2 . In the illustrated embodiment, the part  24  comprises the nose section of an airplane, and the layup  22  comprises a doubler  20  that reinforces an area  34  of the nose section  24 . The apparatus includes a tool assembly  25  mounted on a suitable manipulator  36  that is operated by one or more controllers  35 . The manipulator  36  may comprise a robot or similar automated device that moves the tool assembly  25  along multiple axes in a reference system  55  based on set of programmed instructions used by the controller  35 . 
         [0031]    The tool assembly  25  includes a tool  26  having a multi-contoured tool face  28  that substantially matches the multi-contoured part surface  22  in the area  34  where the layup  20  is to be applied to the part  24 . The tool assembly  25  also includes first and second compactors  54 , respectively for compacting the layup  20  against the part surface  22 . The tool assembly  25  further includes a tool base  30  upon which the tool  26  is mounted. Each of the compactors  54 ,  56  respectively, is inflated and deflated respectively using a pressure source  62  and a vacuum source  64  operated by the controller(s)  35 . 
         [0032]    The layup  20  may be formed on the multi-contoured tool face  28  by an automatic fiber placement machine (AFP) which may also operated by the controller(s)  35 . A locator system  45  generates a set of location data  45   a  that locates the position and orientation of the tool face  28  relative to the part surface  22  in the three dimensional special reference system  55 . Similarly, the locator system may be used by the controller  35  to locate and coordinate the movement of the AFP machine  42  relative to the tool face  28 . 
         [0033]    Attention is now directed to  FIGS. 4 and 5  which illustrate additional details of the apparatus. In this embodiment, the manipulator  36  comprises a robot  36  mounted for linear movement along a pair of rails  38 . The robot  36  includes a robot arm  40  having the tool assembly  25  mounted on the end thereof by means of a quick-change adapter  32  ( FIG. 5 ). The quick-change adapter  32  allows differently configured tools  26  to be quickly mounted on the arm  40  in order to place differently configured layups  20  on different areas of the part  24  that have differing geometries. As previously mentioned, the robot  36  is operated by one or more programmed controllers  35  ( FIG. 1 ) and is capable of displacing the tool assembly  25  along multiple axes within spatial reference system  55  ( FIG. 5 ). The robot  36  manipulates the tool assembly  25  to place a doubler or other layup  20  in a targeted area  34  on the multi-contoured surface  22  of the part  24 . 
         [0034]    The AFP machine  42  may comprise a second robotic device  42   a  mounted for linear movement along the rails  38  and includes an automatic fiber placement head  44  mounted on the end of a robotic arm  46 . As will be discussed below, the head  44  lays down multiple strips or courses of composite fiber tape or tows on the tool face  28  to form a multi-contoured layup  20  which is then placed and compacted onto the tool surface  22  by the tool assembly  25  positioned by the robot  36 . In an alternate embodiment, the layups  20  may be kitted and delivered to the robot on a conveyor (not shown) or carousel (not shown). 
         [0035]    The locator system  45  ( FIG. 1 ) monitors and updates the position of the tool  26 , and thus the tool face  28  ( FIG. 1 ), relative to the part  24 , and specifically the part surface  22 . The use of the locator system  45  allows the tool assembly  25  and the robot  36  to be mobile, rather than being mounted in fixed positions. This mobility may improve placement accuracy while contributing to a lean manufacturing process. As previously mentioned, the locator system  45  ( FIG. 1 ) generates a set of location data  45   a  ( FIG. 1 ) in order to coordinate the movements of the AFP machine  42 , the tool assembly  25  and the part  24  within the common spatial reference system  55  ( FIG. 5 ). The location data  45   a  may be constantly updated and used in a closed feedback loop by the controller(s)  35  to achieve placement accuracy of the layup  20  on the part surface  22 . 
         [0036]    The locator system  45  may comprise one or more laser trackers  48  which develops position data by directing a laser beam  52  onto reflective targets  50  placed on the tool assembly  25  and the part  24 . The locator system  45  may optionally further include photogrammetry cameras  33  which record the location of laser beam light reflected off of the reflectors  50  in order to measure the position of the tool assembly  25  relative to the parts surface  22  in the spatial coordinate system  55 . The photogrammetry cameras may comprise, for example and without limitation, commercially available cameras such as commercially available V-Star cameras. Using a combination of photogrammetry and laser tracker measurements of multiple targets  50 , a determination may be made of the position of the tool face  20   a  relative to the part surface  22  in the common spatial reference system  55 . The photogrammetry and laser tracking measurements of the locations of the targets may be integrated together utilizing one or more computers and software programs which may comprise a part of the controllers  35 . The locator system  45  including the reflective targets  50  may be similar to that disclosed in U.S. Pat. No. 7,5897,258 issued Sep. 8 2009 which is incorporated by reference herein in its entirety. 
         [0037]    Referring now particularly to  FIG. 5 , the tool  26  may comprise, for example and without limitation, a light-weight structural foam in which the tool face  28  may be formed by any of several well-known fabrication techniques such as, without limitation, machining and molding. The tool  26  may be fabricated from other low cost materials using low cost fabrication methods to reduce the cost of the tool  26 . The first compactor  54  may comprise an inflatable bladder  54  which may be positioned on the tool face  28  or recessed slightly within the tool face  28 , as shown at  54   a . The second compactor  56  may comprise a flexible vacuum bag  56  which is sealed around its periphery  56   a  to the tool  26 , thereby forming a pressurizable, substantially vacuum tight chamber  65  over the tool face  28 . A breather  58  may be provided between the tool face  28  and the bag  56  to allow air movement under the bag  56  during evacuation. The bag  56  and the breather  58  both cover the tool face  28  thereby protecting the tool face  28  from damage, and facilitating removal of the layup  20  from the tool  26 . The bag  56  may have a surface texture that allows composite layup pre-preg to adhere to its surface during the layup process without distortion, yet is sufficiently elastic to inflate, compact and release the layup  20  onto the part surface  22 . The bag  56  may be formed from, for example and without limitation, latex film, poly packaging film, or urethanes having textured or non-textured surfaces. 
         [0038]    In the embodiments illustrated in  FIGS. 5, 6A, 7A, 8A, 9A and 10 , the bladder  54  is illustrated as a series of generally parallel, separate but interconnected bladders  54   b  that operate as a single bladder  54 . However in other embodiments, the bladder  54  may comprise a single bladder extending over substantially the entire tool face  28 . The bladder  54  may be shaped, sized and have its inflation sequenced to optimize compaction against the part surface  22 . The bladder  54  and the bag  56  are each connected through a series of flow control valves  72  and three way control valves  70  to a pressure source  62  and a vacuum source  64 . The control valves  70  are operated by the controller  74  which may be the same or different from the previously discussed controller(s)  35  ( FIG. 1 ), and function to selectively couple either the pressure source  62  or the vacuum source  64  to the bladder  54  and the bag  56 . Thus, the automatically operated control valves  70  may couple either or both the bladder  54  and the bag  58  with the pressure source  62  in order to pressurize and thereby inflate either the bladder  54  or the bag  56 . Similarly, the control valves  70  may couple the vacuum source  64  to either the bladder  54  or the bag  56  in order to deflate the bladder  54 , or evacuate the bag  56  which draws the bag  56  down onto the tool face  28 . In some embodiments, the tool face  28  may be provided with vacuum grooves  60  that may also be coupled with the control valves  70  in order to assist in pressurizing/depressurizing the chamber  65 . 
         [0039]      FIGS. 6-11  illustrate use of the tool assembly  25  and sequential steps used to form a multi-contoured layup  24 , and then place and compact it onto the part surface  22 . Referring initially to  FIGS. 6A and 6B , after securing the tool  26  on the tool base  30 , the bag  56  and breather  58  are installed over the tool face  28 , and the perimeter  56   a  of the bag  56  is sealed to the tool  26 , forming a substantially vacuum tight, pressurizable chamber  65  ( FIGS. 5 and 6 ) between the bag  56  and the tool  26 . Vacuum lines  66  and pressure lines  68  ( FIG. 5 ) are then installed and connected with both the bladder  54  and the bag  58 . At this point, neither line  75  nor line  77  is connected to either the pressure source  62  or the vacuum source  64  through control valves  70  ( FIG. 5 ), but rather are open to the atmosphere, consequently the bladder  54  and the chamber  65  are substantially at atmospheric pressure. 
         [0040]    Referring now to  FIGS. 7A and 7B , the tool assembly  25  is readied by connecting the vacuum source  64  to both lines  75  and  77  using control valves  70 , which results in substantially full deflation of the bladder  54  and evacuation of air from the chamber  65 . Evacuation of air from the chamber  65  causes the bag  56  to be drawn down onto the tool surface  28  so that the bag  56  conforms substantially to the multiple contours of the tool face  28 . 
         [0041]    Referring to  FIGS. 8A and 8B , with the bag  56  drawn down onto the tool face  28 , the fiber placement head  44  may commence laying down composite fiber material onto the bag according to a prescribed ply schedule. The plies conform to the contours of the tool face  28  as they are being formed by the AFP machine  42 , consequently the layup  20  possesses contours substantially matching those of the part surface  22 . Lines  75  and  77  remain coupled with the vacuum source  64  as the layup  20  is being formed on the tool face  28 . 
         [0042]    Referring to  FIGS. 9A and 9B , after the layup  20  has been formed on the tool  26 , the robot  36  moves the tool assembly  25  into proximity with the part  24 , and applies the layup  20  at the desired position  34  (see  FIG. 4 ) on the part surface  22 . With the layup  20  applied to and contacting the part surface  22 , the pressure source  62  is coupled with lines  75 , while the vacuum source  64  remains coupled with line  77 . Pressurization of lines  75  result in inflation of the bladder  54 , causing the bladder  54  to inflate and apply pressure to the layup  20  which compacts the layup against the part surface  22 . During this compaction of the layup  20  by the bladder  54 , the bag  56  remains deflated as a result of the vacuum applied through line  77 . 
         [0043]    Next, as shown in  FIG. 10 , the pressure source  62  is coupled with the line  77  which pressurizes and inflates the bag  56 , causing it to expand and apply pressure to the layup  20  which further compacts the layup  20  against the part surface  22 . 
         [0044]      FIG. 11  illustrates the next step in the process in which the vacuum source  64  is coupled with both lines  75  and  77 , resulting in deflation of both the bladder  54  and the bag  56 . Deflation of bag  56  causes the bag  56  to separate and retract away from the layup  20 . Upon separation of the bag  56  from the layup  20 , the robot  56  returns the tool assembly  25  to a standby position (not shown) in readiness for the next layup/application cycle. 
         [0045]    Attention is now directed to  FIG. 12  which broadly illustrates the steps of a method of forming and applying composite layups to a multi-contoured part surface. Beginning at step  76 , a tool  26  is fabricated which, in the illustrated example, may be performed by forming a structural foam into the desired shape having a multi-contoured tool face  26  that substantially matches the part surface  22 . As previously mentioned, the structural foam may be formed into the desired tool shape using any of various known fabrication processes including but not limited to machining and molding. Next, at step  78 , the vacuum/pressure lines  75 ,  77  are placed in the tool  26  and coupled with the flow control valves  72 . At step  80 , a set of location data is generated, using photogrammetry and/or laser tracking techniques previously described, or other techniques, in order to locate the tool face  26  relative to the part surface  22 . At step  82 , vacuum is applied to both the bladder  54  and the bag  56 , causing the bag  56  to be drawn down onto the multi-contoured tool face  26 . At step  83 , a composite layup is formed on the tool face  26  by using the AFP machine  42  to form one or more plies over the bag  56  which conforms to the tool face  26 . 
         [0046]    With the multi-contoured layup  20  having been formed, then, at step  84 , the robot  36  or other manipulator moves the tool assembly  25  into proximity with the part  24 , and places the layup  20  onto the part surface  22 . Next, as shown at step  86 , the bladder  54  is pressurized, causing it to inflate and apply compaction pressure to the layup  20  while the vacuum bag  56  remains deflated. Then, at step  88 , the bag  56  is also pressurized, causing it to inflate and apply additional compaction pressure to the layup  20  which further compacts the layup  20  against the part surface  22 . Following compaction, vacuum is applied first to the bag  56  and then to the bladder  54 , causing each of them to deflate and draw away from the layup  20 . In one practical embodiment of the method, the bladder  54  is inflated for one minute while vacuum is applied to the bag  56 . Then, the bag  56  is inflated for one minute, following which vacuum is applied to the bag  56  assist in pulling the bag  56  away from the compacted layup  20 . Finally, at step  92 , the tool assembly  25  is retracted to a standby position, in readiness to repeat the layup formation and placement cycle. 
         [0047]    Embodiments of the disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine and automotive applications. Thus, referring now to  FIGS. 13 and 14 , embodiments of the disclosure may be used in the context of an aircraft manufacturing and service method  94  as shown in  FIG. 13  and an aircraft  96  as shown in  FIG. 14 . Aircraft applications of the disclosed embodiments may include, for example, a wide variety of assemblies and subassemblies such as, without limitation, structural members and interior components. During pre-production, exemplary method  94  may include specification and design  98  of the aircraft  96  and material procurement  100 . During production, component and subassembly manufacturing  102  and system integration  104  of the aircraft  96  takes place. Thereafter, the aircraft  96  may go through certification and delivery  106  in order to be placed in service  108 . While in service by a customer, the aircraft  96  is scheduled for routine maintenance and service  110  (which may also include modification, reconfiguration, refurbishment, and so on). 
         [0048]    Each of the processes of method  94  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. 
         [0049]    As shown in  FIG. 14 , the aircraft  96  produced by exemplary method  94  may include an airframe  112  with a plurality of systems  114  and an interior  116 . Examples of high-level systems  114  include one or more of a propulsion system  118 , an electrical system  120 , a hydraulic system  122 , and an environmental system  124 . Any number of other systems may be included. The disclosed method may be employed to fabricate components, structural members, assemblies or subassemblies used in the interior  116  or in the airframe  112 . Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine and automotive industries. 
         [0050]    Systems and methods embodied herein may be employed during any one or more of the stages of the production and service method  94 . For example, components, structural members, assemblies or subassemblies corresponding to production process  102  may be fabricated or manufactured in a manner similar to those produced while the aircraft  96  is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages  102  and  104 , for example, by substantially expediting assembly of or reducing the cost of an aircraft  96 . Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft  96  is in service, for example and without limitation, to maintenance and service  110 . 
         [0051]    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.