Melt pool monitoring system and method for detecting errors in a multi-laser additive manufacturing process

Patent metadata

Field	Value
Publication number	US-11534961-B2
Application number	US-201916662662-A
Country	US
Kind code	B2
Filing date	Oct 24, 2019
Priority date	Nov 9, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A system and method of monitoring a powder-bed additive manufacturing process using a plurality of energy sources is provided. A layer of additive powder is deposited on a powder bed and is fused using a first energy source, a second energy source, or any other suitable number of energy sources. The electromagnetic energy emissions at a first melt pool are monitored by a melt pool monitoring system and recorded as raw emission signals. The melt pool monitoring system may also monitor emissions from the powder bed using off-axis sensors or from a second melt pool using on-axis sensors, and these emissions may be used to modify the raw emission signals to generate compensated emission signals. The compensated emission signals are analyzed to identify outlier emissions and an alert may be provided or a process adjustment may be made when outlier emissions exceed a predetermined signal threshold.

First claim

What is claimed is:

1. A method of monitoring a powder-bed additive manufacturing process utilizing a plurality of energy sources, the method comprising:
depositing a layer of additive material on a powder bed of an additive manufacturing machine;
selectively directing energy from a first energy source onto a first focal point on the layer of additive material;
simultaneously selectively directing energy from a second energy source onto a second focal point on the layer of additive material;
measuring raw emission signals from the powder bed at the first focal point using a melt pool monitoring system;
modifying the raw emission signals based at least in part on interactions between the raw emission signals and the operation of the second energy source to obtain a compensated emission signal;
identifying outlier emissions from the compensated emission signal where the compensated emission signal exceeds a predetermined signal threshold; and
generating an alert in response to identifying outlier emissions;
wherein modifying the raw emission signals comprises modifying the raw emission signals based at least in part on interactions between the raw emission signals and secondary emission signals, wherein the secondary emission signals are emitted from the powder bed at the second focal point.

2. The method of claim 1 , wherein modifying the raw emission signals to obtain the compensated emission signal comprises:
determining a position vector between the first focal point and the second focal point, the position vector representing a relative direction and distance between the first focal point and the second focal point;
measuring the secondary emission signals from the powder bed at the second focal point; and
modifying the raw emission signals based at least in part on the secondary emission signals and the position vector.

3. The method of claim 1 , wherein modifying the raw emission signals to obtain the compensated emission signal comprises:
determining a relative trajectory between the first energy source and the second energy source;
measuring the secondary emission signals from the powder bed at the second focal point; and
modifying the raw emission signals based at least in part on the secondary emission signals and the relative trajectory of the first energy source and the second energy source.

4. The method of claim 3 , wherein the relative trajectory is a difference between a first trajectory of the first energy source and a second trajectory of the second energy source, wherein each of the first trajectory and the second trajectory comprise:
an absolute position of a focal point;
a commanded tool path of the focal point; and
a projected velocity of the focal point along the commanded tool path.

5. The method of claim 4 , wherein the first trajectory is calculated based at least in part on a prior timestamp, a prior location of the first focal point, a present timestamp, and a present location of the first focal point.

6. The method of claim 3 , wherein the relative trajectory is determined based at least in part from a scan model defining commanded tool paths used to facilitate the additive manufacturing process.

7. The method of claim 1 , wherein modifying the raw emission signals to obtain the compensated emission signal comprises:
determining an emission correction factor that is used to modify the raw emission signals.

8. The method of claim 7 , wherein the emission correction factor is a function of at least one of a relative position between the first focal point and the second focal point, a relative trajectory of the first energy source and the second energy source, and a flow vector of a purge gas passing over the powder bed.

9. The method of claim 7 , wherein the emission correction factor is a probability that energy or byproducts emitted from a second melt pool generated by the second energy source are measured as light or byproducts emitted from a first melt pool generated by the first energy source.

10. The method of claim 1 , further comprising:
selectively directing energy from a third energy source onto a third focal point on the layer of additive material, wherein obtaining compensated emission signals comprises modifying the raw emission signals based at least in part on interactions between the raw emission signals and the operation of the third energy source.

11. The method of claim 1 , wherein the raw emission signals are obtained by at least one on-axis melt pool sensor.

12. The method of claim 1 , wherein modifying the raw emission signals to obtain the compensated emission signal further comprises:
measuring powder bed emission signals using an off-axis melt pool sensor; and
modifying the raw emission signals based at least in part on the powder bed emission signals.

13. An additive manufacturing machine comprising:
a powder depositing system for depositing a layer of additive material onto a powder bed of the additive manufacturing machine;
a first energy source for selectively directing a first energy beam onto a first focal point on the layer of additive material;
a second energy source for simultaneously selectively directing a second energy beam onto a second focal point on the layer of additive material;
a melt pool monitoring system for measuring electromagnetic energy emitted from the powder bed; and
a controller operably coupled to the melt pool monitoring system, the controller being configured for:
measuring first emission signals emitted from a first melt pool formed at the first focal point by the first energy beam;
measuring second emission signals emitted from a second melt pool formed at the second focal point by the second energy beam;
modifying the first emission signals based at least in part on the second emission signals to obtain a compensated emission signal;
identifying outlier emissions where the compensated emission signal exceeds a predetermined signal threshold; and
generating an alert in response to identifying outlier emissions;

wherein modifying the first emission signals comprises modifying the first emission signals based at least in part on interactions between the first emission signals and the second emission signals, wherein the second emission signals are emitted from the powder bed at the second focal point.

14. The additive manufacturing machine of claim 13 , wherein modifying the first emission signals comprises:
determining a position vector between the first focal point and the second focal point, the position vector representing a relative direction and distance between the first focal point and the second focal point; and
modifying the first emission signals based at least in part on the second emission signals and the position vector.

15. The additive manufacturing machine of claim 13 , wherein modifying the first emission signals comprises:
determining a relative trajectory between the first energy source and the second energy source; and
modifying the first emission signals based at least in part on the second emission signals and the relative trajectory of the first energy source and the second energy source.

16. The additive manufacturing machine of claim 15 , wherein the relative trajectory is determined based at least in part from a scan model defining commanded tool paths used to facilitate the additive manufacturing process.

17. The additive manufacturing machine of claim 13 , wherein modifying the first emission signals comprises:
modifying the first emission signals based at least in part on a flow vector of a purge gas passing over

Assignees

• Gen Electric

Inventors

• Gold Scott Alan

Classifications

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B22F10/32

  of the atmosphere, e.g. composition or pressure in a building chamber · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title

• B22F10/73

  of powder · CPC title

• B29C64/393

  for controlling or regulating additive manufacturing processes · CPC title