Non-contact acoustic inspection method for additive manufacturing processes

• US 10,073,060 B2
• Filed: 11/19/2015
• Issued: 09/11/2018
• Est. Priority Date: 11/19/2015
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Redding, MacKenzie Ryan, Gold, Scott Alan, Spears, Thomas Graham
• Primary Examiner(s): Surin, J M Saint
• Application Number:
  US14/946,451
• Publication Number:
  US 20170146489A1
• Time in Patent Office: 1,027 Days
• Field of Search: 73645
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 10/366 Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/38 to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
• CPC Class Codes: B22F 10/85 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B22F 12/44 characterised by the configuration of the radiation means
• CPC Class Codes: B22F 12/67 Blades
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B22F 2202/01 Use of vibrations
• CPC Class Codes: B22F 2203/03 for feed-back
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B28B 1/001 Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• 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 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/267 : Welds
• CPC Class Codes: G01N 29/02 : Analysing fluids using acoustic emission techniques G01N29/14 ; constructional or flow details for analysing fluids G01N29/222; optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/043 : in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/0672 : by acoustic tomography medical tomography A61B8/13
• CPC Class Codes: G01N 29/221 : Arrangements for directing or focusing the acoustical waves electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35
• CPC Class Codes: G01N 29/2418 : using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method for inspecting an additive manufacturing process in which a directed energy source is used to create a weld pool at an exposed build surface of a mass of powdered material, and selectively fuse the powdered material to form a workpiece. The inspection method includes: using a noncontact method to generate an acoustic wave in the build surface; using a noncontact method to measure displacement of the build surface in response to the acoustic wave; and determining at least one sub-surface material property of the workpiece by analyzing the displacement of the build surface.

Claims

1. A method of inspecting an additive manufacturing process in which a directed energy source is used to create a weld pool at an exposed build surface of a mass of powdered material, and to selectively fuse the powdered material to form a workpiece, the method comprising:

using the directed energy source to generate an acoustic wave in the build surface by modulating the directed energy source to a lower power level compared to a power level used to create the weld pool;

using a noncontact method to measure displacement of the build surface in response to the acoustic wave; and

determining at least one sub-surface material property of the workpiece by analyzing the displacement of the build surface.

2. The method of claim 1 wherein the acoustic wave is generated and displacement is measured subsequent to the completion of one or more layers during the additive manufacturing process.

3. The method of claim 1 wherein the surface displacements are measured using a monitoring laser separate from the directed energy source.

4. The method of claim 1 wherein:

a single beam steering apparatus is used to steer a build beam from the directed energy source and a monitoring beam from a monitoring laser.

5. The method of claim 1 wherein the sub-surface property comprises at least one defect in the workpiece.

6. The method of claim 1 further comprising controlling at least one build process parameter in response to the determined sub-surface property of the workpiece.

7. The method of claim 1 further comprising:

identifying a defect of the workpiece by analyzing the displacement of the build surface; and

repairing the defect by using the directed energy source to create a weld pool over the defect, permitting previously-fused material to flow into and fill the defect.

8. The method of claim 1 further comprising controlling at least one build process parameter in response to the determined sub-surface property of the workpiece, in combination with data from at least one other process sensor.

9. The method of claim 1 further comprising comparing the at least one sub-surface material property to a model representative of a known good workpiece.

10. The method of claim 1 wherein the acoustic wave is generated and displacement is measured during the building of a layer in the additive manufacturing process, by alternating between the lower power level used to generate the acoustic wave and a higher power level used to create the weld pool.

11. A method of making a workpiece, comprising:

depositing a powdered material so as to define a build surface;

directing a build beam from a directed energy source to create a weld pool in the build surface, and selectively fuse the powdered material in a pattern corresponding to a cross-sectional layer of the workpiece;

using the directed energy source to generate an acoustic wave in the build surface by modulating the directed energy source to a lower power level compared to a power level used to create the weld pool;

using a noncontact method to measure displacement of the build surface in response to the acoustic wave; and

determining at least one sub-surface material property of the workpiece by analyzing the displacement of the build surface.

12. The method of claim 11 further comprising repeating in a cycle the steps of depositing and fusing to build up the workpiece in a layer-by-layer fashion.

13. The method of claim 11 where the acoustic wave is generated and displacement is measured subsequent to the completion of one or more layers during the additive manufacturing process.

14. The method of claim 11 where the surface displacement is measured using a monitoring laser separate from the directed energy source.

15. The method of claim 11 wherein:

a single beam steering apparatus is used to steer the build beam from the directed energy source and a monitoring beam from a monitoring laser.

16. The method of claim 11 further comprising comparing the at least one sub-surface material property to a model representative of a known good workpiece.

17. The method of claim 11 wherein the acoustic wave is generated and displacement is measured during the building of a layer in the additive manufacturing process, by alternating between the lower power level used to generate the acoustic wave and a higher power level used to create the weld pool.