Apparatus and methods for repairing compressor airfoils in situ

Abstract

The apparatus includes a track mounted in the inlet of a compressor. A manipulator is mounted for movement about the track and carries three modules, the last of which mounts a tool head for movement in a Cartesian coordinate system and about the track. A measuring head measures the location of the airfoil surface. An abrading tool mounted on the third module removes surface material from the airfoil. Subsequently, a shot-peening device, either a flapper with embedded shot or free shot is impacted against the abraded surface to strengthen the surface. Final inspection is performed by a light and camera head mounted on the third module.

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       35 . A method for repairing a surface of a selected airfoil of a compressor in situ, comprising the steps of: 
 (a) mounting a manipulator adjacent an inlet of the compressor;    (b) moving a tool carried by the manipulator into the compressor past a circumferential array of fixed vanes into proximity with a selected airfoil mounted on a rotor of the compressor;    (c) displacing the tool in three dimensions for following a contour of a portion of the selected airfoil;    (d) while following the contour of the selected airfoil portion, removing material from the selected airfoil portion by applying the tool thereto; and    (e) subsequent to step (d), strengthening the surface of the selected airfoil portion.    
   
   
       36 . A method according to  claim 35  including prior to steps (b) (e), determining the location of the selected airfoil portion using a measuring head mounted on the manipulator and inserted past the array of vanes, recording the location and subsequent to step (d), measuring the location of a corresponding selected airfoil portion and comparing the measurements to determine a magnitude of a removed material.  
   
   
       37 . A method according to  claim 35  including subsequent to step (d), visually inspecting the selected airfoil portion using a camera mounted on the manipulator and inserted past the first stator vanes.  
   
   
       38 . A method according to  claim 35  wherein step (e) includes shot peening the selected airfoil in situ.  
   
   
       39 . A method according to  claim 38  wherein the step of shot peening includes impacting a flapper containing captive shot against the selected airfoil portion to strengthen the surface.  
   
   
       40 . A method according to  claim 38  wherein the step of shot peening includes impacting free shot against the selected airfoil portion.  
   
   
       41 . A method according to  claim 40  including subsequent to step (e), removing the free shot from about the selected airfoil portion.  
   
   
       42 . A method according to claim  4 Q including enclosing at least part of the selected airfoil portion in situ to provide a collection chamber for the free shot impacted against the airfoil section and collecting the free shot in the chamber  
   
   
       43 . A method according to  claim 42  including removing the free shot from the collection chamber.  
   
   
       44 . A method according to  claim 35  including displacing the manipulator about the inlet of the compressor to locate the tool into proximity with another selected airfoil.  
   
   
       45 . A method for repairing a surface portion of a selected airfoil of a turbine, comprising the step of shot peening the airfoil section in situ.