Acoustic monitoring method for additive manufacturing processes

• US 9,989,495 B2
• Filed: 11/19/2015
• Issued: 06/05/2018
• Est. Priority Date: 11/19/2015
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Gold, Scott Alan, Spears, Thomas Graham
• Primary Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US14/946,401
• Publication Number:
  US 20170146488A1
• Time in Patent Office: 929 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 10/38 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 12/90 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 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• 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 2291/0252 Melting, molten solids
• 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 29/2418 : 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: G01N 29/2431 : using other means for acoustic excitation, e.g. heat, microwaves, electron beams sound producing devices not otherwise provided for G10K15/04
• CPC Class Codes: G01N 29/4427 : with stored values, e.g. threshold values
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method of monitoring 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 method including measuring acoustic energy generated by the weld pool to generate a measured acoustic profile.

Claims

1. A method of monitoring 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 method comprising:

measuring acoustic energy generated by the weld pool to generate a measured acoustic profile; and

controlling at least one aspect of the additive manufacturing process in response to the measured acoustic profile,

wherein the step of controlling includes taking a discrete action in response to the acoustic signal profile deviating from a baseline acoustic profile.

2. The method of claim 1 further comprising comparing the measured acoustic profile to the baseline acoustic profile.

3. The method of claim 2 wherein the baseline acoustic profile is representative of a known good workpiece.

4. The method of claim 2 wherein a difference between the measured acoustic profile and the baseline acoustic profile indicates the presence of a defect in the workpiece.

5. The method of claim 1 further comprising monitoring a position of the weld pool while measuring the acoustic signal.

6. The method of claim 5 wherein the position of weld pool is monitored by two or more spaced-apart acoustic sensors positioned at known locations relative to the mass of powdered material.

7. The method of claim 1 further comprising storing a record of the measured acoustic profile.

8. The method of claim 1 wherein the discrete action is stopping the additive manufacturing process.

9. 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;

measuring acoustic energy generated by the weld pool to generate a measured acoustic profile; and

controlling at least one aspect of the method of making the workpiece in response to the measured acoustic profile,

wherein the step of controlling includes taking a discrete action in response to the acoustic signal profile deviating from a baseline acoustic profile.

10. The method of claim 9 further comprising comparing the measured acoustic profile to the baseline acoustic profile.

11. The method of claim 10 wherein the baseline acoustic profile is representative of a known good workpiece.

12. The method of claim 10 wherein a difference between the measured acoustic profile and the baseline acoustic profile indicates the presence of a defect in the workpiece.

13. The method of claim 12 further comprising 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.

14. The method of claim 9 further comprising monitoring a position of the weld pool while measuring the acoustic signal.

15. The method of claim 14 wherein the position of the weld pool is monitored by two or more spaced-apart acoustic sensors positioned at known locations relative to the mass of powdered material.

16. The method of claim 9 further comprising storing a record of the measured acoustic profile.

17. The method of claim 9 wherein the discrete action is stopping the additive manufacturing process.