Abstract:
An example finishing tool form assembly includes a base and a superabrasive bonded to a surface of the base. The superabrasive is configured to be reciprocated with the base relative to a longitudinally extending recess of a component to finish at least one surface of the component.

Description:
BACKGROUND 
       [0001]    This disclosure relates generally to a finishing tool. More particularly, this disclosure relates to a finishing tool having a superabrasive that is used to finish a turbomachine component. 
         [0002]    Turbomachines, such as gas turbine engines, are known. A typical turbomachine includes multiple sections, such as a fan section, a compression section, a combustor section, and a turbine section. During stable operation, the fan section moves air into the turbomachine. Some of the air is compressed. The compressed air is then mixed with fuel and combusted in the combustor section. Products of the combustion are expanded in the turbine section to rotatably drive the turbomachine. 
         [0003]    Many turbomachines include blades mounted within rotor slots. The blades rotate with the rotors in the compression section and the turbine section, for example. Nonconformances and variations in the surfaces of the rotor slots can affect performance of the turbomachine. For example, a surface of a rotor slot that varies from a desired dimension can introduce stress concentrations in the rotor or in a blade mounted within that slot. Nonconformances and variations within the surface of the rotors defining the blade slots are often difficult to identify and eliminate. Nonconformances include geometric and metallurgical. 
       SUMMARY 
       [0004]    An example finishing tool form assembly includes a base and a superabrasive bonded to a surface of the base. The superabrasive is configured to be reciprocated with the base relative to a longitudinally extending recess of a component to finish at least one surface of the component. 
         [0005]    An example turbomachine component finishing tool assembly includes a fixture and a form mountable to the fixture. The form includes an abrasive bonded to a base. The fixture is configured to reciprocate the form relative to a surface of a turbomachine component. 
         [0006]    An example turbomachine surface finishing method includes reciprocating a base relative to a surface of a turbomachine component. The method finishes the surface with an abrasive bonded to the reciprocating base. 
         [0007]    These and other features of the disclosed examples can be best understood from the following specification and drawings, the following of which is a brief description: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a cross-section of an example gas turbine engine. 
           [0009]      FIG. 2  shows an example turbomachine component finishing tool assembly and a rotor of the  FIG. 1  turbomachine. 
           [0010]      FIG. 3  shows a close-up view of a portion of a rotor slot of the  FIG. 2  rotor. 
           [0011]      FIG. 4  shows a perspective view of an example finishing tool form used in the  FIG. 2  assembly. 
           [0012]      FIG. 5  shows another example turbomachine component finishing tool assembly and rotor. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  schematically illustrates an example aircraft gas turbine engine  10 , which is an example type of turbomachine. The example gas turbine engine  10  includes (in serial flow communication) a fan section  14 , a low pressure compressor  18 , a high pressure compressor  22 , a combustor  26 , a high pressure turbine  30 , and a low pressure turbine  34 . The gas turbine engine  10  is circumferentially disposed about an engine centerline X. 
         [0014]    During operation, air is pulled into the gas turbine engine  10  by the fan section  14 . Some of the air moves through a flow path  36  to a core of the gas turbine engine  10 . The air moving through the flow path  36  is pressurized by the compressors  18  and  22 , mixed with fuel, and burned within the combustor  26 . The turbines  30  and  34  extract energy from the hot combustion gases flowing from the combustor  26 . 
         [0015]    In a two spool design, the high pressure turbine  30  utilizes the extracted energy from the hot combustion gases to power the high pressure compressor  22  through a high speed shaft  38 , and the low pressure turbine  34  utilizes the extracted energy from the hot combustion gases to power the low pressure compressor and the fan section  14  through a low speed shaft  42 . 
         [0016]    The examples described in this disclosure are not limited to the two spool engine architecture described, however, and may be used in other architectures, such as single spool axial design, a three spool axial design, and still other architectures. Further, although the examples described herein are described with regard to the gas turbine engine  10 , those having skill in this art and the benefit of this disclosure will understand that other examples include other types of turbomachines. 
         [0017]    Referring to  FIGS. 2-4  with continuing reference to  FIG. 1 , a rotor  46  within the low pressure compressor  18  of the engine  10  includes a plurality of slots  50 . As can be appreciated, the slots  50  are configured to receive the root section of the blades (not shown). The blades rotate with the rotor  46  within the low pressure compressor  18  of the engine  10 . The blades pressurize air moving through the flow path  36  in a known manner. 
         [0018]    During a forming operation, the rotor  46  is milled to establish the slots  50 . The slots  50  are finished, in this example, to remove nonconformances from a surface  54  after the milling. The surface  54  of the rotor  46  defines portions of the slots  50 . 
         [0019]    A form  58  is received within one of the slots  50   a  during finishing. After inserting the form  58  in the slot  50   a , a fixture  62  reciprocates the form  58  along an axis X 1 . The slot  50   a  extends along an axis X 2  that is parallel to the axis X 1 . After finishing the slot  50   a , the rotor  46  is rotated relative to the fixture  62 , and the form is received within another of the slots  50 . 
         [0020]    In this example, portions of the form  58  corresponding to the surface  54  includes an abrasive  66  bonded to a base  70 . As the form  58  reciprocates relative to the slot  50   a , the abrasive  66  finishes the surface  54  of the slot  50   a.    
         [0021]    The fixture  62  reciprocates the form  58  for a controlled stroke and for an established length of time. Increasing the length of time increases the amount of material removed from the rotor  46 , for example. 
         [0022]    Finishing, in this example, removes or reduces nonconformances in the surfaces  54  of the slot  50  by removing about 0.001 inches of material from the surface  54  of the rotor  46 . In other examples, finishing removes nonconformances in other areas of the slot  50   a , such as a surface  56 , a surface  57 , or removes a different amount of material. 
         [0023]    Example nonconformances include geometric nonconformances or variations in the position of the surface  54  of the slot  50   a  from a desired position of the surface  54 . Other example nonconformances are the result of the interfaces between portions of the slot  50   a  machined by different milling cutters. 
         [0024]    The example slots  50  have an enlarged portion  74  and a narrower neck portion  78 . During operation of the engine  10 , the root portions of the blades having a similar shape are received within the slots  50 . As can be appreciated, the shape of the slots  50  limits movement of the blades radially away from the rotor  46 . 
         [0025]    In this example, the form  58  has a cross-sectional profile similar to the cross-sectional profile of the base of the blade. That is, the form  58  includes an enlarged portion  82  and a narrowed portion  86 . 
         [0026]    In this example, the base  70  of the form  58  is a cast iron material, and the abrasive  66 , which is mounted to the enlarged portion  74  of the finishing form, is a superabrasive. More specifically, the example abrasive  66  is a cubic boron nitride abrasive that is 400 grit ASTM. Superabrasives, as is known in this art, are typically harder than conventional abrasives. As an example, conventional abrasives include pumice, stand, and silicon carbides. Superabrasives, by contrast, include diamond and the aforementioned cubic boron nitride. 
         [0027]    A plating process, such as a nickel plating process, is used to bond a layer of the example abrasive  66  to the base  70 . The base  70  is about 0.0015 inches (0.0381 mm) undersized relative to the slots  50 . The abrasive  66  has a thickness of about 0.0015 inches (0.381 mm) when bonded to the base  70 . Adding the abrasive  66  makes the thickness of the enlarged portion  82  of the form  58  to be about the same as the enlarged portion  74  of the slots  50 . 
         [0028]    In this example, a spring  90  housed within the fixture is used to bias the form  58  toward a radial center of the rotor  46 . This facilitates the form  58  maintaining contact with the surface  54 . Material removal rates can be controlled via variations in spring compression and spring stiffness. 
         [0029]    Referring to  FIG. 5 , in another example, a spring  90   a  is biased toward a roller  94 , which biases a form  58   a  toward a radial center of a rotor  46   a    
         [0030]    Features of the disclosed examples include a low cost, high precision process that can rework slots and other turbomachine components rather than rebroaching an entire rotor slot, for example. Another feature of the disclosed examples is reducing the scrap rate of turbomachine components due to nonconformances in their surfaces. 
         [0031]    Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.