Sensing and Control of Additive Manufacturing Processes

• US 20190118300A1
• Filed: 08/27/2018
• Published: 04/25/2019
• Est. Priority Date: 08/25/2017
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Penny, Ryan Wade, Hart, Anastasios John
• Granted Patent: US 11,511,373 B2
• Time in Patent Office: Days
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/0626 Energy control of the laser beam B23K26/0622 takes precedence
• CPC Class Codes: B23K 26/073 Shaping the laser spot
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/0821 using multifaceted mirrors, e.g. polygonal mirror
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B23K 26/70 Auxiliary operations or equipment
• CPC Class Codes: B23K 26/702 Auxiliary equipment
• CPC Class Codes: B23K 31/125 Weld quality monitoring
• CPC Class Codes: B29C 64/30 Auxiliary operations or equipment
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/95 characterised by the material or shape of the object to be examined G01N21/89 - G01N21/91, G01N21/94 take precedence
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

Systems, devices, and methods for additive manufacturing are provided that allow for components being manufactured to be assessed during the printing process. As a result, changes to a print plan can be considered, made, and implemented during the printing process. More particularly, in exemplary embodiments, a spectrometer is operated while a component is being printed to measure one or more parameters associated with one or more layers of the component being printed. The measured parameter(s) are then relied upon to determine if any changes are needed to the way printing is occurring, and if such changes are desirable, the system is able to implement such changes during the printing process. By way of non-limiting examples, printed material in one or more layers may be reheated to alter the printed component, such as to remove defects identified by the spectrometer data. A variety of systems, devices, and methods for performing real-time sensing and control of an additive manufacturing process are also provided.

Claims

1. A system for manufacturing a three-dimensional object, comprising:

an additive manufacturing printer configured to fuse or deposit a plurality of layers to manufacture a three-dimensional object according to a build plan;

an imaging spectrometer configured to measure one or more parameters while the plurality of layers are fused or deposited by the additive manufacturing printer and transmit one or more signals that correlate to the one or more measured parameters; and

a controller configured to receive the signals that correlate to the one or more measured parameters, determine if any changes to the build plan are desirable in view of the one or more measured parameters, and, if changes are determined to be desirable, adjust the build plan in view of the one or more measured parameters while the additive manufacturing printer is still in the process of manufacturing the three-dimensional object.

2. The system of claim 1,

wherein the build plan includes at least one of a scan speed, a laser power, a laser scan path, a spot size, or a rate of heating or cooling a material being fused or deposited in one or more layers of the plurality of layers, and

wherein an adjustment to the build plan by the controller includes at least one of adjusting the scan speed, the laser power, the toolpath, the spot size, or the rate of heating or cooling a material being fused or deposited in one or more layers of the plurality of layers in response to the one or more measured parameters.

3. The system of claim 1, wherein the one or more measured parameters includes at least one of a temperature distribution, emissivity, band ratios, radiation transport characteristics, or a melt pool shape.

4. The system of claim 3,

wherein the controller is configured to determine statistical moments of the one or more parameters, and

wherein the controller is configured to extract at least one of spatial derivatives, temporal derivatives, or spectral derivatives, and process the at least one of spatial derivatives or temporal derivatives to generate at least one of a quality control assessment or a process control signal.

5. The system of claim 4, wherein the statistical moments of the one or more parameters further comprises at least one of averages or variance, the at least one of averages or variances being along at least one of spatial, temporal, or spectral dimensions of recorded data.

6. The system of claim 1, wherein the controller is configured to perform temperature-emissivity separation on the one or more measured parameters, the one or more measured parameters comprising one or more spectrally resolved radiance measurements.

7. The system of claim 6, wherein the one or more spectrally resolved radiance measurements comprises a first spectrally resolved radiance measurement and a second spectrally resolved radiance measurement, and the temperature-emissivity separation is performed using a two temperature method.

8. The system of claim 6, wherein the one or more measured parameters comprises a spectrally resolved radiance measurement, an in-band emissivity of the three-dimensional object is designated as an arbitrary value that is identical for a single pair of spectral bands that include the spectrally resolved radiance measurement, and the temperature-emissivity separation is performed using a grey body method.

9. The system of claim 1, wherein the one or more measured parameters comprises emissivity data, and the controller is configured to qualify the dimensions of the three-dimensional object in view of the emissivity data.

10. The system of claim 1, wherein the one or more measured parameters comprises anomalous spectral features, and the controller is configured to assess parameters of a melt pool of the additive manufacturing printer in view of the anomalous spectral features.

11. The system of claim 1, wherein an adjustment to the build plan by the controller comprises at least one of the following adjustments:

altering one or more laser scan parameters of the additive manufacturing printer to achieve at least one of a desirable thermal gradient or a time derivative temperature within a defined region of the three-dimensional object;

selectively re-heating at least a portion of at least one layer of the plurality of layers to achieve at least one of a desirable thermal profile, thermal gradient, or a time derivative of temperature within a defined region of the three-dimensional object;

or

adjusting a temperature of at least one of a melt pool of the additive manufacturing printer or at least a portion of at least one layer of the plurality of layers to alter at least one of a microstructure, residual stress, or surface roughness of a defined region of the three-dimensional object.

12. The system of claim 1, wherein an adjustment to the build plan by the controller comprises adjusting an energy profile of a first laser of the additive manufacturing printer to maintain a desired temperature gradient about a portion of one or more lasers of the plurality of lasers that is melted by a second laser of the additive manufacturing printer.

13. The system of claim 1, wherein the controller is configured to control at least one of a power or a scan pathway of a laser of the additive manufacturing printer to provide a substantially constant temperature along a desired region of a melt pool of the additive manufacturing printer as a beam of the additive manufacturing printer scans.

14. The system of claim 1, wherein the controller is configured to adjust an energy profile of one or more process lasers of the additive manufacturing printer using at least one of adaptive feed-forward control or feedback control.

16. The system of claim 14, wherein the controller is configured to adjust the energy profile of the one or more process lasers of the additive manufacturing printer in conjunction with at least one of a CAD code or an analysis of corresponding machine code to generate control signals.

17. The system of claim 1, wherein the one or more measured parameters are sufficient to allow the controller to detect one or more defects in the plurality of fused or deposited layers, and the controller is configured to adjust the build plan such that at least one defect of the one or more defects is remediated by the controller adjusting the build plan to allow for a portion of the plurality of fused or deposited layers to remelt material included as part of the portion of the plurality of fused or deposited layers.

18. The system of claim 17, wherein the controller being configured to adjust the build plan such that at least one defect of the one or more defects is remediated by the controller adjusting the build plan to allow for a portion of the plurality of fused or deposited layers to remelt material included as part of the portion of the plurality of fused or deposited layers further comprises the controller being configured to perform at least one of the following:

use one or more recovered control signals to quantify defect morphology;

deliver extra feedstock to the defect location;

calculate optimal scan parameters in view of defect and feedstock properties;

or

apply one or more scan parameters to the build plan.

19. The system of claim 1, wherein the controller is configured to terminate manufacture of the three-dimensional object prior to completion of the build plan in response to a defect detected by way of the one or more measured parameters.

15. (canceled)

20. A method for additive manufacturing, comprising:

depositing or fusing one or more layers of a plurality of layers of a three-dimensional object, the depositing or fusing being performed by an additive manufacturing printer;

measuring one or more parameters associated with the one or more layers using an imaging spectrometer, the measuring occurring prior to depositing or fusing all layers of the plurality of layers of the three-dimensional object;

communicating the one or more measured parameters to a controller for processing thereof;

processing the one or more measured parameters using the controller to determine if any adjustments to the deposited or fused one or more layers are desirable; and

if the controller determines one or more adjustments to the deposited or fused one or more layers is desirable, communicating commands to the additive manufacturing printer to institute the one or more adjustments to the one or more deposited or fused layers prior to depositing or fusing all layers of the plurality of layers of the three-dimensional object.

21-37. -37. (canceled)

38. A system for manufacturing a three-dimensional object, comprising:

an additive manufacturing printer configured to fuse or deposit a plurality of layers to manufacture a three-dimensional object; and

an imaging spectrometer configured to measure one or more parameters while the plurality of layers are fused or deposited by the additive manufacturing printer and transmit one or more signals that correlate to the one or more measured parameters so that the one or more measured parameters is recorded.

39. (canceled)