Tool and repair method for removing a thermal barrier coating

Abstract

A tool for removing a coating from an interior surface of a component. The tool includes a rotary device; a grinding attachment attached to the rotary device; a tool holder configured to: set an axial position of the grinding attachment coupled to the rotary device over the coating on the interior surface of the component; and set a radial position of the grinding attachment coupled to the rotary device, the radial position defining a cutting depth of the grinding attachment into the coating on the interior surface of the component; and a wheel assembly coupled to the tool holder for guiding the tool holder about an interior perimeter of the component. The tool holder has a base coupled to a collet assembly that has upper and lower sections and first and second handwheels that adjust grinding attachment axial position and cutting depth, respectively.

What is claimed is: 
     
         1 . A tool for removing a coating from an interior surface of a component, comprising:
 a rotary device;   a grinding attachment attached to the rotary device; and   a tool holder configured to:
 set an axial position of the grinding attachment coupled to the rotary device over the coating on the interior surface of the component; and 
 set a radial position of the grinding attachment coupled to the rotary device, the radial position defining a cutting depth of the grinding attachment into the coating on the interior surface of the component; and 
   a wheel assembly coupled to the tool holder for guiding the tool holder about an interior perimeter of the component,   wherein the tool holder includes:
 a base; and 
 a collet assembly coupled to the base for securing the rotary device, wherein the collet assembly includes:
 an upper section; 
 a lower section; 
 a first handwheel coupled to a first threaded shaft for selectively displacing the upper section of the collet assembly toward or away from the lower section of the collet assembly to set the axial position of the grinding attachment; and 
 a second handwheel coupled to a second threaded shaft for selectively displacing the collet assembly toward or away from the base to set the radial position of the grinding attachment to set the cutting depth of the grinding attachment into the coating on the interior surface of the component, wherein the second threaded shaft extends through the collet assembly to the base. 
 
   
     
     
         2 . The tool according to  claim 1 , further comprising at least one biasing member for coupling the collet assembly to the base, wherein the at least one biasing member is configured to spring load the collet assembly toward the base. 
     
     
         3 . The tool according to  claim 1 , wherein the collet assembly further comprises a depth limiter for setting a maximum cutting depth of the grinding attachment into the coating on the interior surface of the component. 
     
     
         4 . The tool according to  claim 1 , wherein the component includes a flange extending about an interior perimeter of the component, and wherein the wheel assembly coupled to the tool holder is configured to guide the tool holder along the flange. 
     
     
         5 . The tool according to  claim 4 , wherein the wheel assembly further comprises:
 at least one first wheel rotatably mounted to the tool holder for engaging the interior surface of the component;   at least one second wheel rotatably mounted to the tool holder for engaging an outside edge of the flange; and   at least one pair of third wheels rotatably mounted to the tool holder for engaging opposing sides of the flange.   
     
     
         6 . The tool according to  claim 1 , wherein the component comprises a combustion component of a gas turbine system. 
     
     
         7 . The tool according to  claim 6 , wherein the combustion component includes a unibody component or a liner. 
     
     
         8 . The tool of  claim 1 , wherein the coating comprises a thermal barrier coating (TBC). 
     
     
         9 . A method for removing a thermal barrier coating (TBC) from an interior surface of a combustion component of a gas turbine system, comprising:
 positioning a tool within an interior of the combustion component, wherein the tool comprises:
 a rotary device; 
 a grinding attachment attached to the rotary device; and 
 a tool holder coupled to the rotary device and configured to:
 set an axial position of the grinding attachment coupled to the rotary device over the TBC on the interior surface of the combustion component; and 
 set a radial position of the grinding attachment coupled to the rotary device, the radial position defining a cutting depth of the grinding attachment into the TBC on the interior surface of the combustion component; and 
 
 a wheel assembly coupled to the tool holder for guiding the tool holder about an interior perimeter of the combustion component, 
 wherein the tool holder includes:
 a base; and 
 a collet assembly coupled to the base for securing the rotary device, wherein the collet assembly includes:
 an upper section; 
 a lower section; 
 a first handwheel coupled to a first threaded shaft for selectively displacing the upper section of the collet assembly toward or away from the lower section of the collet assembly to set the axial position of the grinding attachment; and 
 a second handwheel coupled to a second threaded shaft for selectively displacing the collet assembly toward or away from the base to set the radial position of the grinding attachment to set the cutting depth of the grinding attachment into the TBC on the interior surface of the combustion component, wherein the second threaded shaft extends through the collet assembly to the base; 
 
 
   using the first handwheel, setting an initial axial position of the grinding attachment of the rotary device within the interior of the combustion component;   using the second handwheel, setting a radial position of the grinding attachment of the rotary device within the interior of the combustion component to form an initial cut into the TBC; and   using the first handwheel and the second handwheel, adjusting the axial position and the radial position of the grinding attachment of the rotary device within the interior of the combustion component to form additional cuts into the TBC.   
     
     
         10 . The method according to  claim 9 , further comprising, after forming the initial cut and the additional cuts into the TBC:
 attaching a polishing attachment to the rotary device; and   removing additional TBC using the polishing attachment.   
     
     
         11 . The method according to  claim 9 , further comprising:
 displacing the tool about the interior perimeter of the combustion component when forming the initial cut and the additional cuts.   
     
     
         12 . The method according to  claim 9 , wherein the initial cut defines a maximum axial distance from an edge of the TBC, and wherein the additional cuts are formed between the initial cut and the edge of the TBC. 
     
     
         13 . The method according to  claim 9 , further comprising tapering an edge of the TBC. 
     
     
         14 . The method according to  claim 9 , wherein the combustion component includes an internal feature that extends about the interior perimeter of the combustion component, and wherein the wheel assembly is further configured to guide the tool holder along the internal feature of the combustion component. 
     
     
         15 . The method according to  claim 9 , further comprising providing a constant downward pressure of the grinding attachment against the TBC. 
     
     
         16 . The method according to  claim 9 , further comprising performing the method at an operational site of the gas turbine system. 
     
     
         17 . The method according to  claim 9 , wherein the combustion component includes at least one of a unibody component or a liner.