Abstract:
An exemplary component measuring method includes determining a position of an aperture of a component using a computed tomography scan of a gage and a component. The gage is inserted into the aperture of the component during the computed tomography scan.

Description:
BACKGROUND 
     This disclosure relates to locating apertures within a component and, more particularly, to using computed tomography scans to locate the apertures. 
     It is often desirable to determine the dimensions of a physical component. The dimensions are used to create a computer model of the physical component, for example. Many measurement techniques have developed for determining such dimensions. Some components have relatively complex features and geometries, which makes determining dimensions difficult. 
     Turbomachines, such as gas turbine engines, are well known. Turbomachines typically include a compressor that compresses air and delivers it downstream into a combustion section. The compressed air is mixed with fuel and combusted. The products of combustion pass downstream through a turbine. The compressor and turbine each include rotors. Arrays of removable blades are mounted to the rotors. The blades include apertures used to communicate cooling fluid to the outwardly facing surfaces of the blades. 
     Turbomachine components are one example component having relatively complex geometries. Determining the dimensions of the apertures in the blades is particularly difficult. 
     SUMMARY 
     An exemplary component measuring method includes determining a position of an aperture of a component using a computed tomography scan of a gage and a component. The gage is inserted into the aperture of the component during the computed tomography scan. 
     Another exemplary component measuring method includes inserting a plurality of gages into respective apertures of a component. The method then uses computed tomography scanning of the gages and the component to determine the positions of the apertures. 
     An exemplary component measuring system includes a controller module that determines a position of an aperture within a component using a computed tomography scan of the component and a gage inserted into the aperture. 
    
    
     
       DESCRIPTION OF THE FIGURES 
       The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
         FIG. 1  shows a section view of an example turbomachine. 
         FIG. 2  shows a perspective view of a blade from the  FIG. 1  turbomachine. 
         FIG. 3  shows a perspective view of the  FIG. 2  blade with gage pins inserted into cooling holes of the  FIG. 2  blade. 
         FIG. 4  shows a partially schematic view of the  FIG. 3  blade during a computed tomography scan. 
         FIG. 5  shows a model of the  FIG. 2  blade generated using the computed tomography scan. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an example turbomachine, such as a gas turbine engine  10 , is circumferentially disposed about an axis A. The gas turbine engine  10  includes a fan  14 , a low-pressure compressor section  16 , a high-pressure compressor section  18 , a combustion section  20 , a high-pressure turbine section  22 , and a low-pressure turbine section  24 . Other example turbomachines may include more or fewer sections. 
     During operation, air is compressed in the low-pressure compressor section  16  and the high-pressure compressor section  18 . The compressed air is then mixed with fuel and burned in the combustion section  20 . The products of combustion are expanded across the high-pressure turbine section  22  and the low-pressure turbine section  24 . 
     The low-pressure compressor section  16  and the high-pressure compressor section  18  each include rotors  28  and  30 , respectively. The example rotors  28  and  30  include alternating rows of rotatable blades and static blades. 
     The high-pressure turbine section  22  and the low-pressure turbine section  24  each include rotors  36  and  38 , respectively. The example rotors  36  and  38  include alternating rows of rotatable blades and static blades. 
     The rotors  36  and  38  rotate in response to the expansion to rotatably drive rotors  28  and  30 . The rotor  36  is coupled to the rotor  28  with a spool  40 , and the rotor  38  is coupled to the rotor  30  with a spool  42 . 
     The examples described in this disclosure is not limited to the two-spool gas turbine architecture described, and may be used in other architectures, such as a single-spool axial design, a three-spool axial design, and still other architectures. That is, there are various types of gas turbine engines, and other turbomachines, that can benefit from the examples disclosed herein. 
     Referring to  FIG. 2 , a blade  50  of the  FIG. 1  turbomachine includes a root  54  and an airfoil portion  58  extending from the root  54 . The airfoil portion  58  includes a plurality of cooling holes  62 . The cooling holes  62  are apertures and are, in this example, concentrated near a radial tip  66  of the airfoil portion  58 . 
     Passages (not shown) through the airfoil portion  58  communicate a cooling fluid from a cavity within the blade  50  to the cooling holes  62 . The cooling fluid cools the blade  50 . The diameters and orientations of the passages and the cooling holes  62  may vary, as is known. 
     Referring to  FIGS. 3 to 5  with continued reference to  FIG. 2 , dimensioning and modeling the example blade  50  involves first inserting gage pins  70  into some or all of the cooling holes  62 . A person having skill in this art and the benefit of this disclosure would understand how to select a suitable gage pin for insertion into a particular cooling hole. 
     The inner diameters of the gage pins  70  correspond to the diameters of the associated cooling holes  62 . The diameter of the gage pins  70  corresponds to the diameter of the cooling holes  62 . The orientation of the gage pins  70  corresponds to the orientation of the passages. 
     Gage pins  70  are used in this example. Other examples may use other types of gages, such as gage blocks. 
     After inserting the gage pins  70  into the cooling holes  62 , a water-soluble wax  74  is applied to outer surfaces of the blade  50  in the areas holding the gage pins  70 . The wax  74  is applied at a relatively low temperature (say 150° F. or 65.55° C.) and hardens to hold the gage pins  70  within the cooling holes  62 . The application of the wax  74  is concentrated at the interfaces between the gage pins  70  and the blade  50 . 
     The example blade  50  is then scanned by a computed tomography scanner assembly  78 . The blade  50  is held within a moveable fixture  80  during the scanning. 
     The computed tomography scanner  78  includes an x-ray source  82  that projects an x-ray fan beam  86  against a detector  90 . The fixture  80  and the blade  50  (with the gage pins  70  and wax  74 ) are moved through the fan beam  86  in various directions to scan different areas of the blade  50 . The wax  74  holds the gage pins  70  during such movements. The wax  74  is removed from the blade  50  and gage pins  70  after the scanning. 
     A computer  94  associated with the computed tomography scanning assembly  78  captures the geometry of the blade  50  and the gage pins  70 . The example computed tomography scan performed by the scanning assembly  78  is performed at a high resolution (0.25 mm spacing) and at both high and low thresholds. The high threshold scanning accurately captures the geometry of the blade  50  and the gage pins  70 . The low threshold scanning allows better definition of the gage pin  70 . The computed tomography scan captures portions of the gage pins  70  within the blade  50  and portions of the gage pins  70  outside the blade  50 . 
     A controller portion  98  of the computer  94  utilizes point clouds created from the scanning assembly  78  scan of the blade  50 . The controller portion  98  combines the point clouds in a modeling program to extract vector information about the cooling holes  62 . The example point cloud data is collected in an .asc format file. 
     The controller portion  98  generates a model  100  of the blade  50  using the vector information. The model  100  includes accurately dimensioned cooling holes  104 . The model  100  also includes accurately dimensioned, and oriented, cooling passages. The controller portion  98  may use a program, such as Geomagic, to filter inaccurate data from the scan. In one example, all point data associated with the blade  50  is removed from the low threshold scans, and data associated with the gage pins  70  is removed from the high threshold scans. The modified point clouds are then wrapped individually to provide an .stl file for the gage pins  70  and an .stl file for the blade  50 . Both files are in the same coordinate system. 
     The point cloud is triangulated, which lays a ‘quilt’ made up of triangles over the point cloud to create a solid body. The high resolution point cloud resulting from the computed tomography scan allows for accurate wrapping of the points to create a geometrically accurate solid body. A modeling program will facilitate taking measurements from the solid body. 
     In terms of hardware architecture, the computer  94  can include one or more input and/or output (I/O) device interface(s) that are communicatively coupled via a local interface. The local interface can include, for example but not limited to, one or more buses and/or other wired or wireless connections. The local interface may have additional elements, which are omitted for simplicity, such as additional controllers, buffers (caches), drivers, repeaters, and receivers to enable communications. Further, the local interface may include address, control, and/or data connections to enable appropriate communications among the aforementioned components. 
     An example processor used within the controller portion  98  executes software code, particularly software code stored in a memory portion of the computer  98 . The processor can be a custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the computing device, a semiconductor based microprocessor (in the form of a microchip or chip set) or generally any device for executing software instructions. 
     The memory portion of the computer  98  can include any one or combination of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and/or nonvolatile memory elements (e.g., ROM, hard drive, tape, CD-ROM, etc.). The memory portion may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory portion can also have a distributed architecture, where various components are situated remotely from one another, but can be accessed by the processor. 
     The software in the memory portion may include one or more additional or separate programs, each of which includes an ordered listing of executable instructions for implementing logical functions. A system component embodied as software may also be construed as a source program, executable program (object code), script, or any other entity comprising a set of instructions to be performed. When constructed as a source program, the program is translated via a compiler, assembler, interpreter, or the like, which may or may not be included within the memory. 
     The Input/Output devices that may be coupled to system I/O Interface(s) may include input devices, for example but not limited to, a keyboard, mouse, scanner, microphone, camera, proximity device, etc. Further, the Input/Output devices may also include output devices, for example but not limited to, a printer, display, etc. Finally, the Input/Output devices may further include devices that communicate both as inputs and outputs, for instance but not limited to, a modulator/demodulator (modem; for accessing another device, system, or network), a radio frequency (RF) or other transceiver, a telephonic interface, a bridge, a router, etc. 
     A feature of the disclosed example includes accurately dimensioning an aperture within a part utilizing a computed tomography scan. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.