Abstract:
A system and method for reconfiguring a turbine vane. In at least one embodiment, the system may be used to straighten an airfoil of a turbine vane segment to remove lean, twist, or racking, or any combination thereof. The airfoil may be straightened by fixing portions of the forward and aft hooks of the inner and outer shrouds of the turbine vane, restricting other portions of the forward and aft hooks of the inner and outer shrouds of the turbine vane to only move rotationally about a centerline of the inner or outer shrouds, and applying a load to various portions of the inner and outer shrouds and the airfoil to return the turbine vane to be within predetermined specifications.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention is directed generally to turbine vanes, and more particularly to turbine vane restoration systems. 
       BACKGROUND 
       [0002]    Airfoils of turbine vane segments often distort during use in a turbine engine in one or more of four ways. For instance, airfoils may lean, which is downstream deflection. Airfoils may twist, which is rotation of the inner shroud about a longitudinal axis extending between the inner and outer shrouds. Airfoils may also be subjected to racking, which is inner shroud circumferential rotation about an engine centerline relative to the outer housing. Airfoils may also droop, which occurs when down stream portions of the outer housing deflect into the gas path. Such distortion conditions negatively affect performance of the turbine engine and may severely affect the lifecycle of the airfoil and of the inner and outer shrouds. 
         [0003]    Conventional systems exist for removing twist from airfoils. However, conventional systems are time consuming. For instance, twist may be removed from an airfoil using a furnace cycle; yet, a furnace cycle is very time consuming. In addition, restoring a damaged airfoil to satisfactory tolerances is very difficult using conventional systems. Thus, a need exists for a more efficient airfoil repair system. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention relates to a system for reconfiguring an airfoil of a turbine vane segment. In at least one embodiment, the system may be used to straighten an airfoil of a turbine vane. The system for reconfiguring a turbine vane may be used to straighten an airfoil of a turbine vane to remove lean, twist, or racking, or any combination thereof. The airfoil may be straightened by applying a force to various portions of the airfoil and by restricting various portions of the airfoil. The airfoil may be worked up to approximately two degrees without incurring surface microcracks and up to approximately four degrees before incurring cracks visible with liquid penetrant testing inspection such as florescent penetrant inspection (FPI). 
         [0005]    The system may be formed from a fixture that may be any device capable of supporting the turbine vane segment. In one embodiment, the fixture may be configured to support one or more retention arms that may be configured to be attached to a base to limit movement of certain portions of the turbine vane when loaded. The retention arms may be configured to be attached to projections on an outer surface of an outer shroud and inner shroud of the turbine vane to position the turbine vane within the system. In particular, the turbine vane may be formed from the elongated airfoil having the inner shroud attached at one end the outer shroud attached at the other end. The inner shroud may include one or more forward inner hooks and one or more aft inner hooks extending from the inner shroud away from the elongated airfoil. The outer shroud may include one or more forward outer hooks and one or more aft outer hooks extending from the inner shroud away from the elongated airfoil. The retention arms may be configured to rigidly support the forward or aft inner hooks, or both, or the forward or aft outer hooks, or both. In at least one embodiment, the turbine vane may be a TLes VX 4.3A Vane formed from RENE 80 material. The system may also include a force application device, which may be, but is not limited to being, a hydraulic jack or other appropriate device. The force application device may be positioned in various positions to apply a desired load to the turbine vane. 
         [0006]    The system may be used by loading a turbine vane into the fixture. A forward outer hook of the turbine vane may be attached to the fixture via a retention arm to substantially prevent movement of the forward outer hook. An aft outer hook of the turbine vane may be coupled to a rotational movement device that restricts the aft outer hook of the turbine vane such that the aft outer hook may only rotate about a centerline of the outer shroud. The inner shroud of the turbine vane may be positioned in contact with a force application device such that a force may be applied to the inner shroud. The force may be applied to the turbine vane while the turbine vane is at room temperature. In at least one embodiment, the force application device may be used to apply a force to the forward outer hook on the outer shroud to induce a twisting of the forward outer hook about the centerline of the outer shroud. 
         [0007]    In another embodiment, a turbine vane may be loaded into a fixture. An aft outer hook of the turbine vane may be locked with one or more retention arms to substantially prevent movement of the aft outer hook. An forward outer hook of the turbine vane may be coupled to a rotational movement device that restricts the forward outer hook of the turbine vane such that the forward outer hook may only rotate about a centerline of the outer shroud. The inner shroud of the turbine vane may be positioned in contact with a force application device such that a force may be applied to the inner shroud. The force may be applied to the turbine vane while the turbine vane is at room temperature. In at least one embodiment, the force application device may be used to apply a force to the aft outer hook on the outer shroud to induce a twisting of the aft outer hook about the centerline of the outer shroud. 
         [0008]    In another embodiment, a turbine vane may be loaded into a fixture. Forward and aft inner hooks of the inner shroud of the turbine vane may be locked to the fixture to substantially prevent movement of the forward and aft inner hooks of the inner shroud. The forward outer hook of the turbine vane may be fixed to prevent rotation or axial movement of the forward outer hook. An outer surface of the outer shroud may be in contact with a damper. A second damper may be in contact with a center region of the elongated airfoil to limit movement. A force may be applied to the aft outer hook with a force application device turbine vane. The force may be applied to the turbine vane while the turbine vane is at room temperature. Applying a force in this manner may correct a problem with droop in the inner shroud. 
         [0009]    The turbine vane may be in a solution annealed state before being subjected to a load, such as having undergone about 1200 degrees Celsius for two hours, to achieve the greatest movement and to minimize cracking. An aging heat treatment may also be applied to the turbine vane after applying the force to the turbine vane. For instance, the turbine vane may also be subjected to stabilization annealing of temperatures of about 1,095 degrees Celsius for about four hours, followed by a first precipitation hardening stage including exposure of the turbine vane to temperatures of about 1080 degrees Celsius, and followed by a second precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 870 degrees Celsius for about 12 hours. 
         [0010]    An advantage of this invention is that a turbine vane may be reconfigured to be within predetermine physical specifications without preheating the turbine airfoil. 
         [0011]    These and other embodiments are described in more detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention. 
           [0013]      FIG. 1  is a front view of a fixture of the system of this invention. 
           [0014]      FIG. 2  is a left side view of the fixture of the system shown in  FIG. 1 . 
           [0015]      FIG. 3  is a perspective view of two turbine vanes positioned adjacent to each other in an inspection gauge such that an inner shroud gap is formed between the adjacent inner shrouds of the turbine airfoils. 
           [0016]      FIG. 4  is a perspective view of a turbine vane positioned in a fixture of the system and fixed at the forward outer hooks of the outer shroud and limited to only rotational movement about a centerline of the turbine vane at the aft outer hooks. 
           [0017]      FIG. 5  is a perspective view of a turbine vane positioned in a fixture of the system and fixed at the inner and outer shroud with a force applied to the outer shroud generally aligned with the centerline of the airfoil. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    As shown in  FIGS. 1-5 , this invention is directed to system  10  for reconfiguring a turbine vane segment  12 . In at least one embodiment, the system  10  may be used to realign the turbine vane  12  by moving the outer shroud  18 . The turbine vane  12  may be straightened by applying a force to various portions of the turbine vane  12  and by restricting various portions of the turbine vane  12 . The turbine vane  12  may be worked up to approximately two degrees without incurring surface microcracks and up to approximately four degrees before incurring cracks visible with liquid penetrant testing inspection such as FPI. 
         [0019]    As shown in  FIGS. 1-4 , the system  10  may be formed from a fixture  20  that may be any device capable of supporting the turbine vane segment  12 . In one embodiment, the fixture  20  may be configured to support one or more retention arms  22 . The retention arms  22  may be configured to be attached to a base  23  to limit movement of certain portions of the turbine vane  12  when loaded. The retention arms  22  may be configured to be attached to projections  24  on a surface  26  of an outer shroud  18  and inner shroud  16  of the turbine vane  12  to position the turbine vane  12  within the system  10 . In particular, the turbine vane  12  may be formed from the elongated airfoil  14  having the inner shroud  16  attached at one end the outer shroud  18  attached at the other end. The inner shroud  16  may include one or more forward inner hooks  26  and one or more aft inner hooks  28  extending from the inner shroud  16  away from the elongated airfoil  14 . The outer shroud  18  may include one or more forward outer hooks  30  and one or more aft outer hooks  32  extending from the outer shroud  18  away from the elongated airfoil  14 . The retention arms  22  may be configured to rigidly support the forward or aft inner hooks  26 ,  28 , or both, or the forward or aft outer hooks  30 ,  32 , or both. In at least one embodiment, the turbine vane  12  may be a TLes VX 4.3A Vane formed from RENE 80 material. 
         [0020]    As shown in  FIGS. 1 and 2 , loads may be applied to the turbine vane  12  with a force application device  34 , which may be, but is not limited to being, a hydraulic jack or other appropriate device. The force application device  34  may be positioned in various positions to apply a desired load to the turbine vane  12 . 
         [0021]    As shown in  FIG. 4 , a turbine vane  12  may be loaded into a fixture  20 . A forward outer hook  30  of the turbine vane may be attached to the fixture  20  via a retention arm  22  to substantially prevent movement of the forward outer hook  30 . An aft outer hook  32  of the turbine vane  12  may be coupled to a rotational movement device  36  that restricts the aft outer hook  32  of the turbine vane  12  such that the aft outer hook  32  may only rotate about a centerline  36  of the outer shroud  18 . The inner shroud  16  of the turbine vane  12  may be in contact with a force application device  34 . A force may be applied to the inner shroud  16  to reconfigure the turbine vane  12 . The force may be applied to the turbine vane  12  while the turbine vane  12  is at room temperature. The turbine vane  12  may be in a solution annealed state, such as having undergone about 1200 degrees Celsius for two hours, to achieve the greatest movement and to minimize cracking. An aging heat treatment may also be applied to the turbine vane  12  after applying the force to the turbine vane  12 . For instance, the turbine vane  12  may also be subjected to stabilization annealing of temperatures of about 1095 degrees Celsius for about four hours, followed by a first precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 1080 degrees Celsius, and followed by a second precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 870 degrees Celsius for about 12 hours. The load application device may be a hydraulic ram rated to about 15,000 pounds. 
         [0022]    In another embodiment, as shown in  FIG. 4 , a turbine vane  12  may be loaded into a fixture  20 . An aft outer hook  32  of the turbine vane  12  may be locked with one or more retention arms  22  to substantially prevent movement of the aft outer hook  32  in the direction of arrow  46 . A forward outer hook  30  of the turbine vane  12  may be coupled to a rotation limiting device  35  that restricts the forward outer hook  30  of the turbine vane  12  such that the forward outer hook  30  may only rotate about a centerline  36  of the outer shroud  18  in the direction of arrow  50 . The inner shroud  16  of the turbine vane  12  may be in contact with the force application device  34 . A force may be applied to the inner shroud  16  with the force application device  34 . The force may be applied to the turbine vane  12  while the turbine vane  12  is at room temperature. The turbine vane  12  may be in a solution annealed state, such as having undergone about 1200 degrees Celsius for two hours, to achieve the greatest movement and to minimize cracking. An aging heat treatment may also be applied to the turbine vane  12  after applying the force to the turbine vane  12 . For instance, the turbine vane  12  may also be subjected to stabilization annealing of temperatures of about 1095 degrees Celsius for about four hours, followed by a first precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 1080 degrees Celsius, and followed by a second precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 870 degrees Celsius for about 12 hours. The load application device may be a hydraulic ram rated to about 15,000 pounds. 
         [0023]    In another embodiment, as shown in  FIG. 5 , a turbine vane  12  may be loaded into a fixture  20 . Forward and aft inner hooks  26 ,  28  of the inner shroud  16  of the turbine vane  12  may be locked to the fixture  20  to substantially prevent movement of the forward and aft inner hooks  26 ,  28  of the inner shroud  16 . The forward outer hook  30  of the turbine vane may be fixed to prevent rotation or axial movement. The aft outer hook  28  of the turbine vane  12  may be attached to a force application device  34  that may be used to move the aft outer hook toward or away from the inner shroud  16 . An outer surface  37  of the outer shroud  18  may be in contact with a damper  39 . A second damper  41  may be in contact with a center region  40  of the turbine vane  12  to limit movement. The dampers  39 ,  41  may be used for safety during the bending process. The force may be applied to the turbine vane while the turbine vane is at room temperature. The force may be applied in this manner to produce bending of the airfoil  14  to correct misalignment of the inner shroud  16  without affecting the fit between the outer shroud hooks  18  and an inspection gage shown in  FIG. 3 . 
         [0024]    The turbine vane  12  may be in a solution annealed state, such as having undergone about 1200 degrees Celsius for two hours, to achieve the greatest movement and to minimize cracking. An aging heat treatment may also be applied to the turbine vane  12  after applying the force to the turbine vane  12 . For instance, the turbine vane  12  may also be subjected to stabilization annealing of temperatures of about 1095 degrees Celsius for about four hours, followed by a first precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 1080 degrees Celsius, and followed by a second precipitation hardening stage including exposure of the turbine vane  12  to temperatures of about 870 degrees Celsius for about 12 hours. 
         [0025]    In operation, a turbine vane  12  may be solution annealed, as previously mentioned, before any loads are applied to work the turbine vane  12 . The load application portion of the straightening process may be performed before coating and heat treatments are applied to the airfoil  14 . A turbine vane  12  that is to be repaired may be slid into an inspection gage as far as the turbine vane  12  will do without force. A master part may be slide into the inspection gage adjacent to the turbine vane  12  to measure the gap  44  between the inner shroud seal gap. The measurement provides a general indication of how much bending is needed at a forward outer hook  30 . The turbine vane  12  may be installed in any of the manners previously described. A load may be applied to the turbine vane  12  to correct various problems with the turbine vane  12 . The load may be applied by bending the turbine vane  12  in steps with small movements in the same direction to achieve a desired movement. The proper amount of adjustment is determined using a dial indicator and limiting movement of the turbine vane to about 0.7 inch. 
         [0026]    In at least one embodiment, the fixture  20  may enable movement at the forward outer hook  30  while allowing rotational movement at the aft outer hook  32 . Once the inner shroud gap is acceptable, the aft outer hook  32  may be aligned with the forward outer hook  30 . Twist may be removed from the aft outer hooks  32  by fixing the aft outer hooks  32 , allowing the forward outer hooks  30  to rotate about the centerline  36  of the inner shroud  16 , and applying a force to the pressure side  38  of the inner shroud  16 . If the forward or aft inner shroud hooks  26 ,  28  have an axial misalignment, such as lower then a master part, the misalignment can be corrected using the fixture  20  shown in  FIG. 5  and applying a force to the after outer hook  32  while locking the inner shroud  16  and forward outer hook  30 . The turbine vane  12  may then be inserted into an inspection gage and then may be subjected to a crack opening heat treatment and FPI. A bond coat may be applied to the turbine airfoil  12 . The turbine vane  12  may also be exposed to a diffusion heat treatment. The turbine vane  12  may be inspected using the inspection gage after undergoing the diffusion heat treatment. A thermal barrier coating (TBC) may be applied to the turbine vane  12 . The turbine vane  12  may finally be subjected to a heat treatment of about 870 degrees Celsius. The turbine vane  12  may be finally inspected using an inspection gage. 
         [0027]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.