Process and apparatus for locating coated cooling holes on turbine vanes

1. A process for locating cooling holes on a part comprising the steps of:

providing a part having a region of cooling holes covered by a coating;

using a heater to heat said part substantially uniformly so as to exploit thermal conductivity properties of different portions of said part; and

identifying the locations of said coated cooling holes by generating a high contrast thermal image of said part and said region of coated cooling holes.

2. A process according to claim 1 , wherein said part providing step comprises providing a turbine vane having a plurality of cooling holes coated by a thermal barrier, coating.

3. A process according to claim 1 , wherein said identifying step comprises providing a thermal imaging camera having a pixel frame and spacing said cooling hole region of said part from said camera so that when a thermal image is taken, said image substantially fills the pixel frame of said camera.

4. A process according to claim 1 , wherein said identifying step comprises generating two dimensional geometry information about the location of each cooling hole in said region and one dimensional temperature information for each cooling hole in said region.

5. A process according to claim 4 , wherein said identifying step further comprises calculating the position of each said cooling hole in said region using said two dimensional geometry information and said one dimensional temperature information.

6. A process according to claim 1 , wherein said heater using step comprises using a radiant heater to heat said part.

7. A process according to claim 1 , wherein said heater using step comprises using a device for blowing hot air onto said part.

8. A process for locating coated cooling holes on a part comprising the steps of:

providing a part having a region of coated cooling holes;

heating said part;

identifying the locations of said coated cooling holes by generating a high contrast thermal image of said part and said region of coated cooling holes;

said identifying step comprises generating two dimensional geometry information about the location of each cooling hole in said region and one dimensional temperature information for each cooling hole in said region;

said identifying step further comprising calculating the position of each said cooling hole in said region using said two dimensional geometry information and said one dimensional temperature information; and

said calculating step comprising drawing isothermal lines and connecting points at the same temperature; determining slopes between adjacent ones of said isothermal lines; and determining a Z-depth at a given location from the temperature at said location.

9. A process according to claim 8 , wherein said calculating step further comprises:

determining the X-Y location of the surface of the part from its corresponding pixel location on the camera picture frame; and

creating a three dimensional model by matching said Z dimension with a corresponding X-Y location.

10. A system for locating coated cooling holes in parts which comprises:

a heater for substantially uniformly heating a part having a surface with a plurality of cooling holes;

an infra red camera for scanning said surface of said part and for generating a thermal image of said scanned surface; and

a computer for determining the locations of said cooling holes from said thermal image.

11. A system according to claim 10 , wherein said heater comprises a radiant heater.

12. A system according to claim 10 , wherein said heater comprises a device for blowing hot air onto said part.

13. A system according to claim 10 , wherein said infra red camera has a frame area defined by a finite number of pixels and wherein said camera is spaced from said part by a distance such that when a thermal image of a scanned surface is taken, the image completely fills the pixels in said frame area.