Closed-loop process control for electron beam freeform fabrication and deposition processes
A closed-loop control method for an electron beam freeform fabrication (EBF 3 ) process includes detecting a feature of interest during the process using a sensor(s), continuously evaluating the feature of interest to determine, in real time, a change occurring therein, and automatically modifying control parameters to control the EBF 3 process. An apparatus provides closed-loop control method of the process, and includes an electron gun for generating an electron beam, a wire feeder for feeding a wire toward a substrate, wherein the wire is melted and progressively deposited in layers onto the substrate, a sensor(s), and a host machine. The sensor(s) measure the feature of interest during the process, and the host machine continuously evaluates the feature of interest to determine, in real time, a change occurring therein. The host machine automatically modifies control parameters to the EBF 3 apparatus to control the EBF 3 process in a closed-loop manner.
1. A closed-loop control method for an electron beam freeform fabrication (EBF 3 ) process wherein, using an EBF 3 apparatus, a wire is fed via a wire feeder, melted, and progressively deposited as a molten pool, the molten pool being cooled in layers on a substrate, the method comprising:
melting the wire via an electron beam within a vacuum chamber to thereby form the molten pool on the substrate;
detecting a feature of interest of the molten pool during the EBF 3 process using at least one sensor, wherein the feature of interest includes at least one of a height of the molten pool, a distance between the molten pool and the wire feeder, and a temperature of the layers;
continuously evaluating the feature of interest to determine, in real time, a change occurring therein; and
using a host machine to automatically modify, in a closed-loop manner, a set of control parameters of a master process controller used to control an operation of the EBF 3 apparatus.
2. The method of claim 1 , wherein the at least one sensor includes a camera, and wherein detecting a feature of interest additionally includes capturing an image of a location of the wire relative to the molten pool and a shape and area of the molten pool during the EBF 3 process using the camera.
3. The method of claim 1 , wherein the apparatus includes an infrared (IR) band-pass filter, and wherein detecting a feature of interest includes using the IR band-pass filter to thermally image the layers.
4. The method of claim 1 , wherein the at least one sensor comprises an electron detector, and wherein detecting a feature of interest comprises using the electron detector to image the EBF 3 process.
5. The method of claim 2 , further comprising an electron detector, wherein detecting a feature of interest comprises using the electron detector to further image the EBF 3 process.
6. The method of claim 3 , further comprising an electron detector, and wherein detecting a feature of interest comprises using the electron detector to further image the EBF 3 process.
7. The method of claim 1 , wherein continuously evaluating the feature of interest to determine, in real time, a change occurring therein includes automatically assessing at least one of a magnitude and a speed change of a wire feed during the EBF 3 process.
8. The method of claim 1 , wherein automatically modifying a set of input parameters includes automatically modifying one of; a position and a temperature of a component of the apparatus.
9. A closed-loop control method for an electron beam freeform fabrication (EBF 3 ) wherein, using an EBF 3 apparatus, a wire is melted via an electron beam in a vacuum chamber and progressively deposited as a molten pool, the molten pool being cooled in layers on a substrate, the method comprising:
collecting images of a feature of interest of the molten pool during the EBF 3 process using at least one camera positioned inside of the vacuum chamber;
continuously evaluating the images using a host machine to determine, in real time, a magnitude and a rate of change occurring in the feature of interest, including at least a height of the molten pool; and
automatically modifying a set of control parameters to the EBF 3 apparatus, via the host machine, in a closed-loop manner to thereby control the EBF 3 process.
10. The method of claim 9 , wherein the camera is equipped with one of: a charge-coupled device and a complementary metal-oxide semiconductor.
11. The method of claim 9 , wherein the camera is equipped with an infrared (IR) band-pass filter, and wherein collecting images of a feature of interest includes thermally imaging the EBF 3 process using the IR band-pass filter.
12. The method of claim 9 , wherein collecting images of a feature of interest further comprises using an electron detector to further image the EBF 3 process from within the vacuum chamber.
13. The method of claim 11 , further comprising an electron detector to further image the EBF 3 process from within the vacuum chamber.
14. The method of claim 9 , wherein collecting images of a feature of interest comprises imaging at least one of: a size-related property of the wire, a position of the wire relative to the molten pool, a size-related property of the molten pool, a temperature of at least one of the layers, and a temperature of the molten pool.
15. An apparatus for providing closed-loop control method of an electron beam freeform fabrication (EBF 3 ) process, wherein a wire is melted via an electron beam and progressively deposited onto a substrate as a molten pool, and wherein the molten pool is cooled in layers on the substrate, the apparatus comprising:
a vacuum chamber;
an electron gun positioned in the vacuum chamber and adapted for generating the electron beam;
a wire feeder adapted for feeding the wire toward a substrate;
a main process controller adapted to control the electron gun and the wire feeder via a set of control parameters, wherein the wire is melted into a molten pool and progressively deposited in layers onto the substrate to form a product;
at least one sensor adapted for measuring a feature of interest of the molten pool during the EBF 3 process, wherein the feature of interest includes at least one of a height of the molten pool, a distance between the molten pool and the wire feeder, and a temperature of at least one of the layers; and
a host machine having an algorithm for continuously evaluating the feature of interest to determine, in real time, a change occurring therein;
wherein the host machine is configured to execute the algorithm and thereby automatically generate a set of input parameters that modifies the set of control parameters, thereby controlling the EBF 3 process in a closed-loop manner.
16. The apparatus of claim 15 , wherein the at least one sensor includes a camera adapted for imaging the feature of interest.
17. The apparatus of claim 16 , wherein the camera is equipped with one of: a charge-coupled device and a complementary metal-oxide semiconductor.
18. The apparatus of claim 16 , wherein the camera is equipped with an infrared (IR) band-pass filter, and is adapted for thermally imaging the layers as they cool using the IR hand-pass filter.
19. The apparatus of claim 16 , wherein the at least one sensor further comprises an electron detector, wherein measuring a feature of interest comprises using the electron detector to further image the EBF 3 process.
20. The apparatus of claim 16 , wherein the at least one sensor further comprises an electron detector, wherein measuring a feature of interest comprises using the electron detector to further image the EBF 3 process.
21. The apparatus of claim 15 , wherein the at least one sensor comprises an electron detector adapted for measuring a feature of interest.
22. The apparatus of claim 15 , wherein the sensors are further adapted for collecting images of the feature of interest by imaging: a size-related property of the wire, a position of the wire relative to the molten pool, a size-related property of the molten pool, and a temperature of the molten pool.
23. The apparatus of claim 15 , wherein the set of input parameters includes: a feed rate of the wire, a translation speed of the wire, and a power value of the electron beam.