Abstract:
A method and system for assisting in the manufacture of composite parts such as those used for various high-strength assemblies such as aircraft wings, vertical stabilizers, racing car shells, boat hulls, and other parts which are required to have a very high strength to weight ratio. The system uses laser technology to measure the resultant surfaces of a first manufactured composite part. A computer system analyzes and compares the as-built dimensions with the required production specifications. Supplemental composite filler plies are designed including shape and dimensions. These plies are nested together into a single composite sheet and manufactured to minimize wasted material. The plies are then cut out and applied to the first part guided by a laser projection system for locating the plies on the part. The part is then re-cured. The final assembly is then re-measured for compliance with production dimensions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional patent application is a continuation of U.S. patent application Ser. No. 12/965,786 entitled “COMPOSITE MANUFACTURING PLY COMPENSATION SYSTEM AND METHOD” filed on Dec. 10, 2010 and which claims a priority benefit to US Provisional Application No. 61,285,191 entitled “COMPOSITE MANUFACTURING PLY COMPENSATION SYSTEM AND METHOD” filed in the United States Patent and Trademark Office on Dec. 10, 2009, the entirety of each of which is incorporated by reference hereby. 
     
    
     DESCRIPTION OF RELATED TECHNOLOGY 
       [0002]    The present invention relates to the fabrication and manufacture of composite parts, and more particularly to a system for measuring manufactured dimensions of a first as-built part and generating additional uniquely shaped plies for layup and re-curing so that the final part meets production requirements. 
       SUMMARY 
       [0003]    A laser radar measuring system scans and captures the surface geometry of a first build of a composite part. The as-built measurement data is compared against production specifications. Additional plies of composite material are then designed for placement on the sub-standard part. The plies may be layered and tapered depending on the area to be built up. Once the plies are calculated, they are laid out in an optimum manner on a composite material sheet for markup and cutting. This nesting saves material costs by putting the plies together in a layout that creates the least amount of waste. The plies are then located onto the as-built part guided by lasers for precise location. The as-built part and additional plies are then cured together. Finally the revised part is re-measured to confirm that the newly as-built dimensions are within production tolerances. 
         [0004]    The advantages and features discussed above and other advantages and features will become apparent from the detailed description of the best mode for carrying out the invention that follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0006]      FIG. 1  is a block diagram of the invention; 
           [0007]      FIGS. 2A-2B  are block diagrams of the ply compensation software architecture; 
           [0008]      FIG. 3  shows a particular arrangement of the compensation plies being applied to a deficient part; 
           [0009]      FIG. 4  is a computer screen shot showing how the compensation plies are nested to minimize waste; 
           [0010]      FIGS. 5A-5B  are computer screen shots showing the trace paths that the laser projection system will draw on the deficient part to assist in the ply layout; 
           [0011]      FIG. 6A  shows a flowchart for the major processes of the invention; 
           [0012]      FIG. 6B  is a side elevation view of a composite part showing the application of compensation plies to achieve a nominal surface; 
           [0013]      FIG. 7  shows a large industrial kiln for curing composite parts; 
           [0014]      FIG. 8  is a computer screen shot illustrating the reporting feature of the invention; 
           [0015]      FIG. 9  is a computer screen shot illustrating a coverage map generated by the invention  FIG. 10  shows a composite airfoil being worked on. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0016]    In an embodiment, the steps of the ply compensation system and method include:
       a) compare the “as-built” composite part data to the “as-designed” specification;   b) determine and identify the zones not within engineering tolerances;   c) calculate the shape and quantity of compensation plies required to build the part into engineering tolerances;   d) automatically nest and cut the compensation plies;   e) automatically generate the laser projection files to position compensation plies accurately;   f) re-cure the composite part; and   g) test the finished composite part for compliance with engineering tolerances       
 
         [0024]    Another embodiment comprises:
       a) compare “as built” composite part to “as designed;”   b) determine zones out of engineering tolerances;   c) calculate shape and quantity of compensation plies required to build part into engineering tolerance;   d) automatically generate the nest and NC code to cut the compensation plies; and   e) automatically generate the laser projection files to accurately position compensation plies.   f) Automatically Generate Plots and Reports for Statistical Analysis, Cutting and Laser lay-up process.       
 
         [0031]    Referring to  FIG. 1 , a block diagram illustrating a process overview is shown. First, at block  10 , a laser radar scans the surface of an as-built part, and at block  12  creates a three-dimensional data set representing the surface of the as-built part. Data sets can be created using laser radar with a spatial analyzer. Laser radar works with the part compensation software by capturing the surface geometry of composite parts in a point cloud metrology system. Advantages include a fully automatic measurement without requiring SMR or other targets, and all required geometry information can be captured in one go. 
         [0032]    Based on the data acquired the laser radar&#39;s scan of a composite part and creation of a point cloud of a tool&#39;s or part&#39;s surface, embodiments of the ply compensation system and method described herein manages the definition and creation of multi-layer compensation plies. 
         [0033]    At block  14  the as-built surface is compared with and against a second data set that represents the as-designed surface. A third data is set is created representing the differential dimensions between the as-built surface and the as-designed surface. Any areas which are considered to be out of tolerance are then targeted for ply compensation. The software program using parameter inputs such as ply thickness, fiber orientation, stepping protocol, and other parameters for generating the appropriate number and thickness of plies, creates a series of patterns of plies which are to be cut out of a bolt of the ply cloth for layup on the substandard part. 
         [0034]    A nesting module is configured to build nests of compensation plies and automatically cuts them out to be laid up. At block  16  the nesting software module takes the series of plies and assembles them into an optimum configuration which when laid out on the ply cloth will minimize material waste. The layout configuration may be printed on thin tracing paper for overlay on the ply cloth or alternatively the patterns may be projected onto the cloth for marking and subsequent cut out. For example, in an embodiment, a laser module kits the compensation plies while still on the cutting table and projects the exact location of where on the deficient part they need to be placed, and in keeping with all grain constraints. 
         [0035]    At block  18 ,once the compensation plies have been cut out from the cloth, a laser projection program illuminates trace patterns on the substandard part to identify the location and orientation for placement of the compensation plies. The part is then cured a second time in an oven. After curing, the part is once again scanned with laser radar to create a new data set to be compared with the as designed data set. 
         [0036]    Finally a quality reporting module compares the second as-built data set with the as-designed data set to generate a report showing the final as-built dimensions in compliance with the design specification. The finished composite part is then tested for tolerance. 
         [0037]    Now referring to  FIGS. 2A-2B  a block diagram of the ply compensation software data architecture is shown. The first set of inputs is the non-recurring data which is data particular to the design specifications of the part to be built. As shown in  FIG. 2A , inputs for non-recurring set up include “Part” Information  20  (e.g.: part number P/N, number of plies allowed, etc.), Flat Patterns  21 , Laser Files  22 , and part analysis file such as a VGLR File  23  (.csv) with nominal thickness. In an embodiment as shown in  FIG. 2B , the inputs for the non-recurring set-up can also include CAD files  52  and Zone Data  53  for the part  11 . A Non-Recurring set-up module  25  includes a part template setup including segmenting flat patterns and laser files into sub-zones based on the part file, for example the VGLR file (shown as an .xls version of the VGLR) as shown in  FIG. 2A  or the CAD file and Zone Data as shown in  FIG. 2B . 
         [0038]    The second set of input data is the data collected by the laser radar representing the as-built dimensions and three-dimensional surface of the part being manufactured, such as Part Information (e.g serial no., etc.)  26  and part and tool measurement files (e.g. ASCII text files from laser radar  27  as shown in  FIG. 2A  or a Point Cloud File  54  as shown in  FIG. 2B ). These inputs are for a recurring production process module  28  configured to perform recurring production processes including calculation of number of plies required in each sub-zone and modification of flat patterns and laser files. The two data sets are compared to determine and locate surface areas that are not within desired tolerances. Those noncompliant areas are then targeted for build up with compensation plies. The compensation plies are shaped so as to match, fill and fit into the noncompliant areas of the composite part. Depending upon the depth and shape of the deficiency, one or more plies may be required in a stacking fashion to fill in that area which is non compliant. Further as plies are stacked, their perimeter dimension may be incrementally reduced or increased as to create the appropriate three-dimensional shape as required by the design specification. Such stacked shaped may be thought of as pyramidal, and depending upon the deficient area, may be right side up or inverted. 
         [0039]    The ply compensation software outputs modified flat patterns  29   a  and nested flat patterns  29   b , modified laser files  31 , and reports  30 . The laser files are modified so as to project the areas where the compensation plies will be applied. A multitude of reports  30  are generated to document the manufacturing, surveying, compensation, re-scanning, and final as-built dimensions. 
         [0040]      FIG. 3  shows a particular arrangement of the compensation plies being applied to a deficient part. The embodiments are described employing the example of manufacturing a car hood, however embodiments can be used for any composite part manufacture. Composite materials are widely used in manufacture, for example in aviation components (tails, wings, fuselages, propellers), space vehicles, boat hulls, racecar bodies, storage tanks, turbine blades and even baseball bats. For example  FIG. 10  shows a composite airfoil  71  being worked on. This horizontal stabilizer is a typical airframe part to which the process may be applied. As shown in  FIG. 3 , a deficient area  33  is being built up on the left-hand side of the part. Several layers of compensation plies are being stacked to bring the composite part within design tolerances. A smaller ply indicated by the dark area  34  is stacked upon a larger ply area  35 , which is further stacked upon and even larger ply area  36 . This pyramidal stacking brings the substandard part into compliance with the design specification. 
         [0041]      FIG. 4  is a computer screen shots  40  showing how the compensation plies  41   a ,  41   b ,  41   c  . . .  41   n  are nested to minimize waste. Note that each ply  41   a ,  41   b ,  41   c  . . .  41   n  is labeled with a unique number which will be used to identify its location during placement on to the sub-standard part. Also note how the plies  41   a ,  41   b ,  41   c  . . .  41   n  have been arranged so as to minimize wasted material after they have been cut from the cloth. The nesting program generates the machine code instructions for the CNC machine to perform the cutting operation.  FIG. 7C  is a screenshot of the invention performing a calculation to determine the size and location of compensation plies. In the lower right-hand corner a series of very thin plies are required to compensate. In embodiments, different colors are used by the computer program to indicate the thickness required for compensation. The color scheme may be selected and or assigned by the operator. 
         [0042]      FIGS. 5A-5B  are computer screen shots showing the laser projection technology which draws illuminated shapes to assist in the placing and location of the compensation plies. The computer screen shots  50  show i the trace paths  51  that the laser projection system will draw on the deficient part to assist in the ply layout. These are the locations where the plies will be laid on to the substandard part. As shown in  FIG. 5B  the individual plies may be viewed separately or in a stacked manner. 
         [0043]      FIG. 6A  shows a block diagram flowchart for the major processes of the invention. The software program collects the standard part data and the substandard part data, compares the two data sets to find deficiencies, determines the size and location for compensation plies, automatically nests the plies to minimize waste of material, generates instructions to cut the plies, generates new laser files to project outlines for placing the plies onto the substandard part, and processes the rescan data after the part has been cured to verify final part compliance. As shown in  FIG. 6A , at block  60  the software is configured to compare the “as-built” composite part data to the “as-designed” specification and determine where the as built composite parts deviate from as-designed plans. At block  61  the software is configured to measure nominal part deviation. At block  62 , the software is configured to determine the size and location for compensation plies, for example as shown in the screen shot  40  of  FIG. 3 . Thus the software is configured to calculate the shape and quantity of compensation plies required to build the part into engineering tolerances as described above with respect to  FIG. 3 . At block  63  the software is configured to generate instructions to automatically nest and cut the compensation plies to bring the substandard part into compliance, as shown and described with respect to the screen shot of  FIG. 4 . At block  64  the software is configured to automatically generate the laser projection files to position compensation plies accurately as shown in the example of  FIG. 5 , and once the plies are positioned, re-cure the composite part. At block  65  the software is configured to test the finished composite part for compliance with engineering tolerances. In an embodiment, as shown in  FIG. 6A , if the re-cured composite part is not in compliance, the software can be configured to reiterate the process starting again at block  61  and repeats the process until compliance is verified as shown at block  65 .  FIG. 7  shows a large industrial kiln  70  for curing composite parts. An end cover swings away to open the end of the tubular chamber. Parts to be cured are slid into the oven for a predetermined number of heating cycles. 
         [0044]      FIG. 6B  is a side elevation view of a composite part  11  showing the application of compensation plies  41   a . . . n  to achieve a nominal surface  66 . Note the composite part&#39;s surface is significantly below the nominal surface  66  which creates the substandard part. The dimensional difference between the nominal surface  66  and the composite part surface  68  exceeds the specified tolerance for the final part  11 . Therefore, in those areas where the as-built part is noncompliant, compensation plies  41   a . . . . n  will be shaped and designed to fill in these deficient areas. The addition of the compensation plies  41   a . . . n  will raise the finished surface up to the desired nominal surface  66 , and thus the finished part will be within design tolerances. 
         [0045]      FIG. 8  is a computer screen shot  80  illustrating the reporting feature of the invention indicating those areas that required ply compensation. Various parameters are recorded and reported such as dimensional data, ply count, discrepancy amount, thickness, location, and orientation (alignment of fibers and/or fabric grain if required). As shown in  FIG. 8 , the report includes, for each location of the composite part  11 , inter alia, Zone  81 , Location  82 , Nominal  83 , Actual Delta  84 , Actual status  85 , Pdelta  86 , Plies  87 , Rounddown  88 , Rounded  89 , Deltatarget  90 , Maxply  91 , Maxdelta  92 , and so on. As shown in  FIG. 8 , a discrepancy Delta is shown for each zone location, and a status for the composite at that location indicating whether the composite is within tolerance (Good) or out of tolerance (e.g, “Thin” or “Thick”). For example, the report shows that row  93  for Zone AB0 Location 02 and the row  94  for Zone AB0 Location  04  of the composite part  11  are “Thin” and thus may require additional ply build up to meet tolerance, and also gives information how far out of tolerance the part is using report data categories above. 
         [0046]      FIG. 9  is a computer screen shot  100  illustrating a coverage map  95  generated by the invention. The coverage map  95  may be used to generate and or modify laser files to project location information onto the substandard part for the application of compensation plies. Information can include Zone  96 , Location  97 , Number of Plies  98 , nesting or layering of plies ( 1 - 12 )  99 , The coverage map  95  may also be used to generate graphical information for the operator and or to support the reporting functions of the invention. 
         [0047]    The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.