Additive manufacturing method and apparatus

Patent metadata

Field	Value
Publication number	US-10933468-B2
Application number	US-201615767475-A
Country	US
Kind code	B2
Filing date	Nov 14, 2016
Priority date	Nov 16, 2015
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A method of monitoring an additive manufacturing apparatus. The method includes receiving one or more sensor signals from the additive manufacturing apparatus during a build of a workpiece, comparing the one or more sensor signals to a corresponding acceptable process variation of a plurality of acceptable process variations and generating a log based upon the comparisons. Each acceptable process variation of the plurality of acceptable process variations is associated with at least one state of progression of the build of the workpiece and the corresponding acceptable process variation is the acceptable process variation associated with the state of progression of the build when the one or more sensor signals are generated.

First claim

The invention claimed is:

1. A method of monitoring an additive manufacturing apparatus comprising receiving one or more sensor signals from the additive manufacturing apparatus during a build of a workpiece, comparing the one or more sensor signals to a corresponding acceptable process variation of a plurality of acceptable process variations and generating a log based upon the comparisons, wherein each acceptable process variation of the plurality of acceptable process variations is associated with at least one state of progression of the build of the workpiece, wherein the at least one state of progression of the build of the workpiece comprises a time from a set event in the build, and the corresponding acceptable process variation is the acceptable process variation associated with the state of progression of the build when the one or more sensor signals are generated.

2. A method according to claim 1 , wherein the at least one state of progression of the build of the workpiece comprises a position on the workpiece/in a build volume.

3. A method according to claim 1 , wherein each acceptable process variation of the plurality of acceptable process variations is associated with at least one build time and the method comprises determining the corresponding acceptable process variation to which the sensor signal is compared from a build time at which the sensor signal is generated.

4. A method according to claim 1 , wherein the acceptable process variation comprises acceptable variations in one or more of:
a) a temperature in a build chamber of the additive manufacturing apparatus
b) a temperature of flowable material to be consolidated
c) a temperature of a melt pool
d) intensity of light collected by a sensor
e) spectral emission from the melt pool
f) dimensions of the melt pool
g) a comparison of images of adjacent layers
h) a gas pressure in the build chamber
i) oxygen concentration in the build chamber
j) pump speed of a pump for recirculating gas through the build chamber
k) elevator position, speed and/or acceleration
l) wiper position, speed and/or acceleration of the wiper
m) load on the wiper
n) a predicted temperature of current or future portions of the workpiece/build from a thermal model based upon sensor signals
o) dosing of material
p) acoustic signals
q) images of a powder bed
r) images of the consolidated material, and/or
s) a rate of change of any one of (a) to (r).

5. A method according to claim 1 , wherein there is a one-to-one correlation between each acceptable process variation of the plurality of acceptable process variations and each state of progression of the build of the workpiece for which sensor signals are generated.

6. A method according to claim 1 , wherein at least one of the acceptable process variations is associated with a plurality of states of progression of the build of the workpiece.

7. A method according to claim 1 , wherein the plurality of acceptable process variations only apply to one or more portions of the workpiece, as specified by the associated state of progression of the build of the workpiece.

8. A method according to claim 1 , wherein the sensor signals comprise signals or are derived from signals from one of more of the following sensors of the additive manufacturing apparatus:
a) a pyrometer,
b) an acoustic sensor,
c) a thermal camera,
d) a visible light camera,
e) a photodiode,
f) a spectrometer
g) a force feedback device
h) a pressure sensor,
i) a mass flow sensor,
j) an oxygen sensor,
k) an encoder, and/or
l) accelerometer.

9. A method according to claim 1 , wherein the acceptable process variation is a variation in a difference between two sensed values.

10. A method according to claim 1 , comprising controlling the additive manufacturing apparatus during the build based upon the comparison of the sensor signals to the corresponding acceptable process variation.

11. A method according to claim 1 , comprising controlling parameters of the build on the additive manufacturing apparatus to return the sensor signals to and/or maintain the sensor signals within the corresponding acceptable process variations.

12. A method according to claim 1 , comprising halting build of the workpiece if the sensor signals fall outside of the acceptable process variation.

13. A method according to claim 12 , wherein halting build of the workpiece comprises halting the entire build.

14. A method according to claim 12 , wherein halting the build of the workpiece comprises suppressing build of the workpiece whilst continuing with a build of other workpieces of the build.

15. A method according to claim 1 , comprising only storing a subset of sensor data derived from the sensor signals based upon sensor signals that fall outside of the corresponding acceptable process variation.

16. A method according to claim 1 , comprising storing the sensor data together with coordinate data localising the sensor data in the coordinate system of the workpiece or build volume and using the coordinate data to identify regions of the workpiece in which the sensor data falls outside the acceptable process variation.

17. A method according to claim 1 , comprising controlling the additive manufacturing apparatus to repair a region of the workpiece based on sensor signals for that region falling outside the corresponding acceptable process variation.

18. A method according to claim 1 , comprising controlling the additive manufacturing apparatus to carry out a further inspection of a region of the workpiece based on sensor signals for that region falling outside the corresponding acceptable process variation.

19. A non-transient data carrier having instructions therein, which, when executed by a processor, cause the processor to carry out the method of claim 1 .

20. A method of monitoring an additive manufacturing apparatus comprising receiving one or more sensor signals from the additive manufacturing apparatus during a build of a workpiece, comparing the one or more sensor signals to a corresponding acceptable process variation of a plurality of acceptable process variations and generating a log based upon the comparisons, wherein each acceptable process variation of the plurality of acceptable process variations is associated with at least one state of progression of the build of the workpiece, wherein the at least one state of progression of the build of the workpiece comprises an order in which the sensor signals are generated and the corresponding acceptable process variation is the acceptable process variation associated with the state of progression of the build when the one or more sensor signals are generated.

21. A method according to claim 20 , wherein a specified order of the plurality of acceptable process variations corresponds to an order in which the sensor signals are generated during the build and the method comprises determining the corresponding acceptable process variation to which the sensor signal is compared from an order in which the sensor signals are generated during the build.

22. A non-transient data carrier having instructions therein, which, when executed by a processor, cause the processor to carry out the method of claim 20 .

23. A controller for monitoring an additive manufacturing apparatus, the controller comprising a processor arranged to receive one or more sensor signals from the additive manufacturing apparatus during a build of a workpiece, compare the one or more

Assignees

• Renishaw Plc

Inventors

• Jones Nicholas Henry Hannaford
• Brown Ceri
• Revanur Ramkumar
• Mcfarland Geoffrey

Classifications

• B29C64/393 Primary

  for controlling or regulating additive manufacturing processes · CPC title

• B22F10/322

  of the gas flow, e.g. rate or direction · CPC title

• B22F12/90

  Means for process control, e.g. cameras or sensors · CPC title

• B22F12/70

  Gas flow means · CPC title

• B22F12/49

  Scanners · CPC title