Method for inspecting components having complex geometric shapes

Claim 1

A method for inspecting a component having a plurality of similarly shaped structural portions, comprising the steps of: (a) scanning a surface of at least one of the similarly shaped structural portions with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the at least one portion from eddy current signals received during scanning, the image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) preprocessing the image to substantially reduce any signals caused by geometrical characteristics and background noise common to all of the similarly shaped structural portions; (d) identifying any suspected defect regions in the two-dimensional image from corresponding regions in the preprocessed image of step (c); (e) determining a defect signal from the gray scale intensities for each suspected defect regions in the two-dimensional image; and (f) rejecting the component if any defect signal exceeds a predetermined reference value, wherein step (c) comprises the steps of: (c1) repeating steps (a) and (b) to generate a two-dimensional image for a second and third similarly shaped structural portion; (c2) selecting a test portion and an associated test image, a first reference portion and an associated first reference image, and a second reference portion and an associated second reference image from the three similarly shaped portions; (c3) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (c4) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between gray scale intensities of corresponding pixels of each image; (c5) converting each of the first and second reference images from a gray scale image to respective first and second binary images; and (c6) combining the first and second binary images by a logic AND operation to provide a preprocessed composite binary image.

Claim 2

A method for inspecting a component having a plurality of similarly shaped structural portions, comprising the steps of: (a) scanning a surface of at least one of the similarly shaped structural portions with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the at least one portion from eddy current signals received during scanning, the image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) preprocessing the image to substantially reduce any signals caused by geometrical characteristics and background noise common to all of the similarly shaped structural portions; (d) identifying any suspected defect regions in the two-dimensional image from corresponding regions in the preprocessed image of step (c); (e) determining a defect signal from the gray scale intensities for each suspected defect regions in the two-dimensional image; and (f) rejecting the component if any defect signal exceeds a predetermined reference value, wherein step (c) comprises the steps of: (c1) repeating steps (a) and (b) to generate a two-dimensional image for a second and third similarly shaped structural portion; (c2) selecting a test portion and an associated test image, a first reference portion and an associated first reference image, and a second reference portion and an associated second reference image from the three similarly shaped portions; (c3) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (c4) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between gray scale intensities of corresponding pixels of each image; (c5) converting each of the first and second reference images from a gray scale image to respective first and second binary images; and (c6) combining the first and second binary images by a logic AND operation to provide a preprocessed composite binary image.

Claim 15

A method for inspecting a component having a complex geometric shape, comprising the steps of: (a) scanning a surface of the component with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the component from eddy current signals received during scanning, the image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) preprocessing the image to substantially reduce any signals caused by geometrical characteristics and background noise common to all components having substantially the same geometric shape by subtracting a reference image of a substantially identically shaped component from the image generated in step (b); (d) identifying any suspected defect regions in the two-dimensional image from corresponding regions in the preprocessed image of step (c); and (e) determining a defect signal from the gray scale intensities for each suspected defect region in the two-dimensional image; (f) rejecting the component if any defect signal exceeds a predetermined reference value, converting the preprocessed image from a gray scale image to a binary image; identifying any sections within the binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; and identifying any suspected defect regions in the preprocessed image which correspond to the identified sections in the preprocessed composite binary image.

Claim 16

A method for inspecting a component having a complex geometric shape, comprising the steps of: (a) scanning a surface of the component with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the component from eddy current signals received during scanning, the image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) preprocessing the image to substantially reduce any signals caused by geometrical characteristics and background noise common to all components having substantially the same geometric shape by subtracting a reference image of a substantially identically shaped component from the image generated in step (b); (d) identifying any suspected defect regions in the two-dimensional image from corresponding regions in the preprocessed image of step (c); and (e) determining a defect signal from the gray scale intensities for each suspected defect region in the two-dimensional image; (f) rejecting the component if any defect signal exceeds a predetermined reference value, converting the preprocessed image from a gray scale image to a binary image; identifying any sections within the binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; and identifying any suspected defect regions in the preprocessed image which correspond to the identified sections in the preprocessed composite binary image.

Claim 18

A method for inspecting dovetail slots of a gas turbine engine component, comprising the steps of: (a) scanning a surface of a dovetail slot with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the dovetail slot surface from eddy current signals received during scanning, each image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) repeating steps (a) and (b) to generate a two-dimensional image for three dovetail slots; (d) selecting a test slot and an associated test image, a first reference slot and an associated first reference image, and a second reference slot and an associated second reference image from the three dovetail slots; (e) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (f) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between gray scale intensities of corresponding pixels of each image; (g) converting each of the first and second resulting images from a gray scale image to respective first and second binary images by thresholding; (h) combining the first and second binary images by a logic AND operation to provide a composite binary image; (i) identifying any sections within the composite binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; (j) identifying any suspected defect regions in one of the first and second resulting images of step (e) which correspond to the identified sections of step (i); (k) calculating a defect signal for each suspected defect region; and (l) comparing the defect signal for each region with a predetermined reference value to determine whether a defect is present in the test slot at a location corresponding to the suspected defect region.

Claim 19

A method for inspecting dovetail slots of a gas turbine engine component, comprising the steps of: (a) scanning a surface of a dovetail slot with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the dovetail slot surface from eddy current signals received during scanning, each image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the two-dimensional matrix array; (c) repeating steps (a) and (b) to generate a two-dimensional image for three dovetail slots; (d) selecting a test slot and an associated test image, a first reference slot and an associated first reference image, and a second reference slot and an associated second reference image from the three dovetail slots; (e) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (f) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between gray scale intensities of corresponding pixels of each image; (g) converting each of the first and second resulting images from a gray scale image to respective first and second binary images by thresholding; (h) combining the first and second binary images by a logic AND operation to provide a composite binary image; (i) identifying any sections within the composite binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; (j) identifying any suspected defect regions in one of the first and second resulting images of step (e) which correspond to the identified sections of step (i); (k) calculating a defect signal for each suspected defect region; and (l) comparing the defect signal for each region with a predetermined reference value to determine whether a defect is present in the test slot at a location corresponding to the suspected defect region.

Claim 31

A method for inspecting gear teeth and the like of a component, comprising the steps of: (a) scanning a surface of a gear tooth with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the gear tooth surface from eddy current signals received during scanning, each image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the matrix array; (c) repeating steps (a) and (b) to generate a two-dimensional image for three gear teeth; (d) selecting a test tooth and an associated test image, a first reference tooth and an associated first reference image, and a second reference tooth and an associated second reference image from the three gear teeth; (e) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (f) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between the gray scale intensities of corresponding pixels of each image; (g) converting each of the first and second resulting images from a gray scale image to respective first and second binary images by thresholding; (h) combining the first and second binary image by a logic AND operation to provide a composite binary image; (i) identifying any sections within the composite binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; (j) identifying any suspected defect regions in one of the first and second resulting images of step (e) which correspond to the identified sections of step (i); (k) calculating a defect signal for each suspected defect region; and (l) comparing the defect signal for each region with a predetermined reference value to determine whether a defect is present in the test tooth at a location corresponding to the suspected defect region.

Claim 32

A method for inspecting gear teeth and the like of a component, comprising the steps of: (a) scanning a surface of a gear tooth with an eddy current probe means to induce eddy currents in the component; (b) generating a two-dimensional image of the gear tooth surface from eddy current signals received during scanning, each image including a multiplicity of pixels arranged in a two-dimensional matrix array and each pixel having a gray scale intensity responsive to the eddy current induced in the component at a component location corresponding to a position of the pixel in the matrix array; (c) repeating steps (a) and (b) to generate a two-dimensional image for three gear teeth; (d) selecting a test tooth and an associated test image, a first reference tooth and an associated first reference image, and a second reference tooth and an associated second reference image from the three gear teeth; (e) taking a difference between the first reference image and the test image to provide a first resulting image by taking a difference between the gray scale intensity of each pixel of the first reference image and the gray scale intensity of a corresponding pixel of the test image; (f) taking a difference between the second reference image and the test image to provide a second resulting image by taking a difference between the gray scale intensities of corresponding pixels of each image; (g) converting each of the first and second resulting images from a gray scale image to respective first and second binary images by thresholding; (h) combining the first and second binary image by a logic AND operation to provide a composite binary image; (i) identifying any sections within the composite binary image which contain a cluster of pixels with predominantly all pixels having a predetermined binary value; (j) identifying any suspected defect regions in one of the first and second resulting images of step (e) which correspond to the identified sections of step (i); (k) calculating a defect signal for each suspected defect region; and (l) comparing the defect signal for each region with a predetermined reference value to determine whether a defect is present in the test tooth at a location corresponding to the suspected defect region.