Abstract:
An assembly used in performing a manufacturing process on a turbine engine component includes a turbine engine component and a fixture including an opening shaped to receive a portion of the turbine engine component. The assembly includes a non-metallic cover placed over at least a portion of an external surface of the fixture. The non-metallic cover is visible when positioned over the at least a portion of the external surface of the fixture and is visible when the turbine engine component is received in the fixture opening of the fixture.

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 12/034,849 filed on Feb. 21, 2008 now U.S. Pat. No. 8,151,458. 
    
    
     BACKGROUND OF THE INVENTION 
     This application relates to a non-metallic cover that is positioned on a fixture that holds a turbine engine component during a manufacturing process, the cover protecting the turbine engine component from scratches. 
     Gas turbine engines typically include turbine rotors having a plurality of removable turbine blades and a plurality of static vanes. Before a manufacturing process, a metal turbine blade is installed in a metal fixture. The turbine blade must be accurately aligned with an opening in the fixture to prevent scratching of the turbine blade during installation. The metal to metal contact between the turbine blade and the fixture can scratch the turbine blade. If the manufacturing process is a laser drilling process, laser splatter can collect on the fixture, which can be difficult to remove. 
     There is a need in the art for a cover that protects a turbine engine component from scratches and that overcomes the other drawbacks and shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     An assembly used in performing a manufacturing process on a turbine engine component includes a turbine engine component and a fixture including an opening shaped to receive a portion of the turbine engine component. The assembly includes a non-metallic cover placed over at least a portion of an external surface of the fixture. The non-metallic cover is visible when positioned over the at least a portion of the external surface of the fixture and is visible when the turbine engine component is received in the fixture opening of the fixture. 
     In another aspect, a method of performing a manufacturing process on a turbine engine component includes the steps of installing a turbine engine components in a fixture opening of the fixture and positioning a non-metallic cover over at least a portion of an external surface of a fixture. The non-metallic cover is visible when positioned over the at least a portion of the external surface of the fixture and is visible when the turbine engine component is received in the fixture opening of the fixture. The method further includes the steps of installing a turbine engine component in a fixture opening of the fixture. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a simplified cross-sectional view of a standard gas turbine engine; 
         FIG. 2  illustrates a turbine blade as is generally known in the prior art; 
         FIG. 3  illustrates a fixture that holds a turbine blade; 
         FIG. 4  illustrates a cover that is to be placed on the fixture; 
         FIG. 5  illustrates the cover positioned on the fixture; 
         FIG. 6  illustrates a perspective view of the cover positioned on the fixture; and 
         FIG. 7  illustrates the cover positioned on the fixture with the turbine blade installed in the fixture. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A gas turbine engine  10 , such as a turbofan gas turbine engine, circumferentially disposed about an engine centerline (or axial centerline axis  12 ) is schematically shown in  FIG. 1 . The gas turbine engine  10  includes a fan  14 , compressors  16  and  17 , a combustion section  18  and turbines  20  and  21 . This application extends to engines without a fan, and with more or fewer sections. As is well known in the art, air is compressed in the compressors  16  and  17 , mixed with fuel and burned in the combustion section  18 , and expanded in turbines  20  and  21 . The turbines  20  and  21  include rotors  22  which rotate in response to the expansion, driving the compressors  16  and  17  and the fan  14 . The turbines  20  and  21  include alternating rows of rotating airfoils or turbine blades  24  and static airfoils or vanes  26 . In  FIG. 1 , the turbine blades  24  are removable from the rotors  22 . It should be understood that this schematic view is included simply to provide a basic understanding of the sections in the gas turbine engine  10  and is not limiting. The exemplary assemblies, covers and methods described herein apply to all types of gas turbine engines for all types of applications. 
       FIG. 2  shows a known turbine blade  24 . A platform  42  is provided at a radially inner portion of the turbine blade  24 , while an airfoil  40  extends radially (as seen from the axial centerline axis  12 ) outward from the platform  42 . A base  44 , located under the platform  42 , has a dovetail shape including a hill  46  and a valley  50 . In one example, there are two hills  46  and  48 , and the valley  50  is located between the two hills  46  and  48 . The valley  50  defines a groove  52  that extends along a length  54  of the base  44  of the turbine blade  24 . The valley  50  has a width  56 , and the hills  46  and  48  have a width  58 . It should be appreciated to a person of ordinary skill in the art that the base  44  may include various configurations. 
     Before a manufacturing process, the turbine blade  24  may be installed in a fixture  60  that holds the turbine blade  24  during the manufacturing process. In one example, the manufacturing process can be a laser hole drilling process. In one example, the fixture  60  is a serration fixture. In one example, the fixture  60  is made of metal. 
     As shown in  FIG. 3 , the fixture  60  includes an opening  62  having a shape that generally corresponds to the shape of the base  44  of the turbine blade  24 . The fixture  60  includes an elongated projection  64 . In one example, the fixture  60  includes two projections  64 , and one of the projections  64  is located on each side of the opening  62 . A distance  66  is defined between the projections  64 . The fixture  60  also includes a stop  68  and an alignment feature  70 . In one example, the alignment feature  70  is a circular head. In another example, the fixture  60  includes two alignment features  70 . 
     As shown in  FIG. 4 , a non-metallic cover  72  is placed over at least a portion of the fixture  60 . In one example, the cover  72  is placed over a front portion of the fixture  60 . In one example, the cover  72  is made of glass filled nylon. The cover  72  includes an opening  74  and an elongated projection  76 . In one example, the cover  72  includes two projections  76  that taper inwardly towards a longitudinal axis A of the opening  74  as the projections  76  extend from a front side  84  to a rear side  86  of the cover  72 , and one of the projections  76  is located on each side of the opening  74 . A distance  88  between the projections  76  is located near the front side  84  of the cover  72  and is greater than a distance  90  between the projections  76  located near the rear side  86  of the cover  72 . That is, the distance between the projections  76  is not constant. A flattened portion  92  is located under each of the projections  76 , and each of the flattened portions  92  also taper inwardly towards the rear side  86  of the cover  72 . The cover  72  also includes an alignment feature  94 . In one example, the alignment feature  94  is a hole. In another example, the cover  72  includes two alignment features  94 . 
     The cover  72  is produced using “Rapid Prototyping,” eliminating the need of complicated machining For example, the cover  72  can be made directly from a computer (CAD) model. 
     As shown in  FIGS. 5 and 6 , when the cover  72  is placed on the front portion of the fixture  60 , the alignment features  70  of the fixture  60  are aligned with the alignment features  94  of the cover  72 , aligning the cover  72  relative to the fixture  60 . In one example, the alignment features  70  of the fixture  60  are received in the alignment features  94  of the cover  72 . Each projection  76  of the cover  72  generally aligns with one of the projections  64  of the fixture  60 . That is, the distance  90  between the projections  76  of the cover  72  is generally equal to the distance  66  between the projections  64  of the fixture  60  at the location where these components meet. The opening  62  of the fixture  60  is exposed and not covered by the cover  72 . That is, the opening  74  of the cover  72  does not block access to the opening  62  of the fixture  60 . 
       FIG. 7  shows an assembly of the base  44  of the turbine blade  24  installed in the fixture  60 . When the turbine blade  24  is to be installed in the fixture  60  before a manufacturing process, the base  44  of the turbine blade  24  is aligned with the opening  62  of the fixture  60 . The turbine blade  24  is then slid in a rearwardly direction, and the projections  76  of the cover  72  are received in the grooves  52  of the turbine blade  24 . The distance  88  of the opening  74  of the cover  72  is greater than the width  56  of the base  44  of the turbine blade  24 , minimizing contact between the base  44  and the cover  72  and helping to locate the turbine blade  24  in the fixture  60 . 
     The turbine blade  24  is installed from the front portion of the fixture  60 . As the turbine blade  24  is slid rearwardly, a distance between the opening  74  of the cover  72  and the base  44  decreases as the projections  76  taper inwardly. As the turbine blade  24  continues to move rearwardly, the projections  64  of the fixture  60  are received in the grooves  52  of the base  44  of the turbine blade  24 . As the distances  66  and  90  are generally equal, the turbine blade  24  smoothly transitions from moving relative to the cover  72  to moving relative to the fixture  60 . The stop  68  of the fixture  60  prevents further rearward movement of the turbine blade  24  relative to the fixture  60 . 
     In the above-described example, the fixture  60  and the cover  72  include projections  64  and  76 , respectively, that engage grooves  52  of a turbine blade  24 . However, the fixture  60  and the cover  72  can include grooves that receive a projection of the turbine blade  24  (formed by one of the hills  46  and  48  as it extends along the length  54  of the base  44  of the turbine blade  24 ). Alternately, the alignment feature  70  of the fixture  60  can be a hole, and the alignment feature  94  of the cover  72  can be a circular head or any type of alignment feature. 
     The cover  72  is made of a non-metallic material and facilitates reducing the turbine blade  24  from being scratched or damaged as the turbine blade  24  is installed in the fixture  60 . The cover  72  facilitates reducing metal to metal contact between the turbine blade  24  and the fixture  60  that might nick, dent or scratch the turbine blade  24  as the turbine blade  24  is installed in the fixture  60 . Because the distance  88  of the opening  74  of the cover  72  is greater than the width  56  of the base  44  of the turbine blade  24 , the base  44  is easily inserted into the opening  74  of the cover  72 . 
     After the turbine blade  24  is installed, a manufacturing process is performed. For example, when the manufacturing process is a laser drilling process, the assembly is mounted in a laser machine and the turbine blade  24  is drilled with a drilling machine. During the laser drilling process, laser spatter can form. If the laser spatter accumulates on the cover  72  of the fixture  60 , the laser splatter can easily be removed from the non-metallic cover  72 . In the event that the cover  72  becomes covered with laser splatter, the cover  72  can be easily replaced with a new cover  72 . 
     The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.