Method for evaluating machined electrodes
An improved measurement method and system particularly suited for graphite electrodes which correlates point cloud measurements collected from a CMM probe and laser scanner with an optimized model of the measured electrode to confirm the electrode is within tolerance or identify out of tolerance areas. The innovative method and system include a CMM probe either controlled by the operator or other forms of robotic automation, a laser scanner, and optimized models measured against the measured electrode and a computer server controlling a processing program for sorting and processing the collected measurements and optimized models. The described system and method therefore integrates a blend of technologies to precisely check the electrode for defects and to predict the performance within an electric arc furnace.
1. A method for determining a machining tolerance of a machined electrode having a threaded section and an unthreaded section, comprising the steps of:
collecting a set of probe measurements of the unthreaded section of the machined electrode and the threaded section of the machined electrode via a coordinate measuring machine;
collecting a set of scanned measurements of the unthreaded section of the machined electrode and the threaded section of the machined electrode via a three-dimensional laser scanner;
receiving in a processing program running on a computer processor an optimized model of the machined electrode having a reference feature, the set of probe measurements and the set of scanned measurements;
roughly aligning within the processing program the set of probe measurements with the optimized model without clocking the threaded section of the machined electrode relative to the reference feature; and
precisely aligning within the processing program the set of scanned measurements with the optimized model by clocking the threaded section of the machined electrode relative to the reference feature.
2. The method of claim 1 further comprising the steps of:
determining within the processing program a best fit between the set of scanned measurements and the optimized model while clocking the threaded section of the machined electrode relative to the reference feature, wherein the best fit comprises an aligned 3D model of the machined electrode; and
determining within the processing program the machining tolerance between the aligned 3D model and the optimized model.
3. The method of claim 2 , wherein the threaded section comprises a set of tapered threads having a crest, a root, a flank, a thread pitch and a thread angle, and wherein the reference feature comprises a two-dimensional dataset having a reference pitch and a reference angle generally corresponding with the thread pitch and the thread angle.
4. The method of claim 3 , wherein the step of determining the best fit while clocking the threaded section of the machined electrode relative to the reference feature further comprises the steps of:
identifying a group of measurements in the set of scanned measurements which correspond to a portion of the threaded section that are within a threshold distance of the reference feature;
translating the set of scanned measurements relative to the reference feature until at least some of the group of measurements intersect with the reference feature;
determining a deviation between the set of scanned measurements and the optimized model at the unthreaded section; and
translating and rotating the set of scanned measurements by a movement factor corresponding to the deviation until the deviation is within a threshold value to get the aligned 3D model of the machined electrode.
5. The method of claim 4 , further comprising the step of verifying that of the set of scanned measurements at a center point of the unthreaded section is coaxial with a corresponding center point of the unthreaded section of the optimized model.
6. The method of claim 4 , wherein at least a portion of the two-dimensional dataset of the reference pitch and the reference angle are embedded in a three-dimensional portion of at least one of the tapered threads, wherein the movement factor comprises a translation parameter and a rotation parameter respectively corresponding to the translation and the rotation of the set of scanned measurements by the movement factor, wherein the translation parameter is equal to the deviation, and wherein the rotation parameter is equal to the deviation divided by the thread pitch multiplied by three hundred and sixty degrees.
7. The method of claim 3 , wherein the step of collecting the set of probe measurements further comprises the steps of:
collecting the set of probe measurements of the threaded section by placing a probe of the coordinate measuring machine onto a plurality of locations of the threaded section at an interior surface of the machined electrode, wherein each of the plurality of locations are spaced substantially equidistant between the flanks of adjacent threads at a first distance away from the root of adjacent threads; and
collecting the set of probe measurements of the unthreaded section by placing the probe of the coordinate measuring machine onto a plurality of locations of the unthreaded section at an exterior surface of the machined electrode, wherein a first set of locations from the plurality of locations are positioned on a front plane of the machined electrode, and wherein a second set of locations from the plurality of locations are positioned around an outer diameter of the machined electrode.
8. The method of claim 1 , wherein the coordinate measuring machine and the three-dimensional laser scanner have a standard calibration with the processing program.
9. The method of claim 2 , further comprising the step of displaying the machining tolerance on a user interface with at least one of a color map visually outlining the variance between the aligned 3D model and the optimized model and a numerical table statistically outlining the variance between the aligned 3D model and the optimized model.
10. The method of claim 1 , further comprising the step of sorting the optimized model, the set of probe measurements and the set of scanned measurements into a plurality of smaller datasets within the processing program, wherein each of the steps carried out within the processing program further comprise the step of processing with a corresponding smaller dataset.
11. The method of claim 1 , wherein the set of scanned measurements is at least five orders of magnitude larger than the set of probe measurements.
12. A method for determining a machining tolerance of a machined part having a threaded section and an unthreaded section, comprising the steps of:
collecting a set of probe measurements of the unthreaded section of the machined part and the threaded section of the machined part via a coordinate measuring machine;
collecting a set of scanned measurements of the unthreaded section of the machined part and the threaded section of the machined part via a three-dimensional laser scanner;
receiving in a processing program running on a computer processor an optimized model of the machined part, a reference feature corresponding with the threaded section, the set of probe measurements and the set of scanned measurements;
roughly aligning the set of probe measurements with the optimized model within the processing program without clocking the threaded section of the machined part relative to the reference feature; and
precisely aligning the set of scanned measurements with the optimized model within the processing program by clocking the threaded section of the machined part relative to the reference feature to get a best fit therebetween, wherein the best fit comprises an aligned 3D model of the machined part;
determining with the processing program the machining tolerance between the aligned 3D model and the optimized model.
13. The method of claim 12 , wherein threaded section comprises a set of tapered threads having a crest, a root, a flank, a thread pitch and a thread angle, and wherein the reference feature comprises a two-dimensional dataset having a reference pitch and a reference angle generally corresponding with the thread pitch and the thread angle in the optimized model.
14. The method of claim 13 , wherein the step of determining the best fit while clocking the threaded section of the machined part relative to the reference feature further comprises the steps of:
identifying a group of measurements in the set of scanned measurements which correspond to a portion of the threaded section that are within a threshold distance of the reference feature;
translating the set of scanned measurements relative to the reference feature until at least some of the group of measurements intersect with the reference feature;
determining a deviation between the set of scanned measurements and the optimized model at the unthreaded section; and
translating and rotating the set of scanned measurements by a movement factor corresponding to the deviation until the deviation is within a threshold value to get the aligned 3D model of the machined part.
15. The method of claim 12 , wherein the step of collecting the set of probe measurements further comprises the steps of:
collecting the set of probe measurements of the threaded section by placing a probe of the coordinate measuring machine onto a plurality of locations of the threaded section at an interior surface of the machined part, wherein each of the plurality of locations are spaced substantially equidistant between the flanks of adjacent threads at a first distance away from the root of adjacent threads; and
collecting the set of probe measurements of the unthreaded section by placing the probe of the coordinate measuring machine onto a plurality of locations of the unthreaded section at an exterior surface of the machined part, wherein a first set of locations from the plurality of locations are positioned on a front plane of the machined part, and wherein a second set of locations from the plurality of locations are positioned around an outer diameter of the machined part.
16. A method for determining a machining tolerance of a machined part having a threaded section and an unthreaded section, comprising the steps of:
collecting a set of probe measurements of the threaded section by placing a probe of a coordinate measuring machine onto a plurality of locations of the threaded section at an interior surface of the machined part, wherein the threaded section comprises a set of tapered threads having a crest, a root, a flank, and wherein each of the plurality of locations are spaced substantially equidistant between the flank of adjacent threads at a first distance away from the root of adjacent threads;
collecting another set of probe measurements of the unthreaded section by placing the probe of the coordinate measuring machine onto a plurality of locations of the unthreaded section at an exterior surface of the machined part;
collecting a set of scanned measurements of the unthreaded section of the machined part and the threaded section of the machined part via a three-dimensional laser scanner;
receiving in a processing program running on a computer processor an optimized model of the machined part, a reference feature corresponding with the threaded section, the set of probe measurements and the set of scanned measurements;
determining within the processing program a relative position of the unthreaded part and the threaded part using the first set of measurements;
roughly aligning the set of probe measurements with the optimized model within the processing program without clocking the threaded section of the machined part relative to the reference feature; and
precisely aligning the set of scanned measurements with the optimized model within the processing program by clocking the threaded section of the machined part relative to the reference feature to get a best fit therebetween, wherein the best fit comprises an aligned 3D model of the machined part;
determining with the processing program the machining tolerance between the aligned 3D model and the optimized model.
17. The method of claim 16 , wherein threaded section further comprises a thread pitch and a thread angle, and wherein the reference feature comprises a two-dimensional dataset having a reference pitch and a reference angle generally corresponding with the thread pitch and the thread angle in the optimized model.
18. The method of claim 17 , wherein the step of determining the best fit while clocking the threaded section of the machined part relative to the reference feature further comprises the steps of:
identifying a group of measurements in the set of scanned measurements which correspond to a portion of the threaded section that are within a threshold distance of the reference feature;
translating the set of scanned measurements relative to the reference feature until at least some of the group of measurements intersect with the reference feature;
determining a deviation between the set of scanned measurements and the optimized model at the unthreaded section; and
translating and rotating the set of scanned measurements by a movement factor corresponding to the deviation until the deviation is within a threshold value to get the aligned 3D model of the machined part.
19. The method of claim 16 , further comprising the step of displaying the machining tolerance on a user interface with at least one of a color map visually outlining the variance between the aligned 3D model and the optimized model and a numerical table statistically outlining the variance between the aligned 3D model and the optimized model.
20. The method of claim 16 , wherein the set of scanned measurements is at least five orders of magnitude larger than the set of probe measurements.