Plasma gun diagnostics using real time voltage monitoring

Patent metadata

Field	Value
Publication number	US-11609967-B2
Application number	US-201816607591-A
Country	US
Kind code	B2
Filing date	May 24, 2018
Priority date	May 25, 2017
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

Method and apparatus for monitoring and diagnosing gun performance is derived that can determine proper gun operation and if not operating properly diagnose potential causes for abhorrent operation. The voltage produced by the gun is sampled in real time and the frequency spectrum produced analyzed using FFT and then reducing the FFT pattern down to a set of numerical values or a signature that can be compared to known signatures for both correct operation and abnormal operation. Using best fit techniques the cause of any abnormal behavior can then be identified. The method can also be used to predict the end of hardware life and aid in production scheduling and spare parts acquisition by providing advanced notice of wear and usage.

First claim

What is claimed:

1. A method for monitoring behavior of a plasma gun having a process controller, the method comprising:
sampling a gun voltage of the plasma gun;
analyzing the sampled gun voltage;
identifying amplitude peaks in the analyzed sampled gun voltage;
producing a pattern representing the identified amplitude peaks; and
comparing the produced pattern to stored known patterns,
wherein, when the comparing indicates that the behavior of the plasma gun is abnormal, a corrective action is performed, and
wherein the producing of the pattern representing the identified amplitude peaks comprises determining a total area of an identified amplitude peak, determining a frequency and amplitude of the identified peak at maximum amplitude, determining a frequency and amplitude of the identified peak at 50% of the total area of the identified peak, determining a frequency and amplitude of the identified peak at 10% of the total area of the identified peak, and determining a frequency and amplitude of the identified peak at 90% of the total area of the identified peak.

2. The method according to claim 1 , wherein the sampling, analyzing, identifying, producing and storing are performed separately from the process controller.

3. The method according to claim 1 , wherein the sampling, analyzing, identifying, producing and storing are performed in the process controller.

4. The method according to claim 1 , wherein the process controller performs the corrective action.

5. The method according to claim 1 , wherein the stored known patterns include at least a set of known normal operation patterns and a set of known abnormal operation patterns.

6. The method according to claim 5 , wherein a data recorder compares the produced pattern to known normal operation patterns in the set of known normal operation patterns, and
wherein, when the produced pattern corresponds to a known normal operation pattern, the behavior of the plasma gun is indicated as normal and the method is repeated.

7. The method according to claim 6 , wherein, when the produced pattern does not correspond to any of the known normal operation patterns in the set of known normal operation patterns, the data recorder compares the produced pattern to known abnormal operation patterns in the set of known abnormal operation patterns, and
wherein, when the produced pattern corresponds to a known abnormal operation pattern, the behavior of the plasma gun is indicated as abnormal and the correct action is transmitted to the process controller.

8. The method according to claim 6 , wherein each stored known abnormal operation pattern is associated with a known cause of abnormal operation and an associated corrective action to return operation to normal, and the method further comprises,
when the produced pattern corresponds to the known abnormal operation pattern, the data recorder provides the associated corrective action to the process controller to return the behavior of the plasma gun to normal operation.

9. The method according to claim 1 being performed at least one of before, during and after a use of the plasma gun.

10. The method according to claim 1 , wherein the sampling of the gun voltage is performed in real time.

11. The method according to claim 1 , wherein the analyzing voltage comprises performing a fast Fourier transform on the sampled gun voltage.

12. An apparatus for monitoring behavior of a plasma gun, comprising:
a process controller structured and arranged to control operational parameters of the plasma gun;
a voltage sensor structured and arranged to sample a gun voltage of the plasma gun;
a data processor configured to analyze the sampled gun voltage, to identify amplitude peaks, and to produce a pattern representing the identified amplitude peaks;
a memory configured to store known gun operating patterns; and
a comparer configured to compare the produced pattern to the stored known gun operating patterns,
wherein, when the comparing indicates that the behavior of the plasma gun is abnormal, the process controller is instructed to perform a corrective action,
wherein the data processor at least one of:
is configured to execute a program to analyze the sampled gun voltage; and
is configured to execute firmware of digital signal processors to analyze the sampled gun voltage, and
wherein the pattern representing the identified amplitude peaks is produced by determining a total area of an identified amplitude peak, determining a frequency and amplitude of the identified peak at maximum amplitude, determining a frequency and amplitude of the identified peak at 50% of the total area of the identified peak, determining a frequency and amplitude of the identified peak at 10% of the total area of the identified peak, and determining a frequency and amplitude of the identified peak at 90% of the total area of the identified peak.

13. The apparatus according to claim 12 , wherein the stored known gun operating patterns include at least a set of known normal operation patterns and a set of known abnormal operation patterns.

14. The apparatus according to claim 13 , wherein the produced pattern is compared to known normal operation patterns in the set of known normal operation patterns, and
wherein, when the produced pattern corresponds to a known normal operation pattern, the behavior of the plasma gun is indicated as normal.

15. The apparatus according to claim 14 , wherein, when the produced pattern does not correspond to any of the known normal operation patterns in the set of known normal operation patterns, the produced pattern is compared to known abnormal operation patterns in the set of known abnormal operation patterns, and
wherein, when the produced pattern corresponds to a known abnormal operation pattern, the behavior of the plasma gun is indicated as abnormal and the correct action is transmitted to the process controller.

16. The apparatus according to claim 14 , wherein each stored known abnormal operation pattern is associated with a known cause of abnormal operation and an associated corrective action to return operation to normal, and
wherein, when the produced pattern corresponds to the known abnormal operation pattern, the associated corrective action is provided to the process controller to return the behavior of the plasma gun to normal operation.

17. The apparatus according to claim 12 being configured to monitor plasma gun behavior at least one of before, during and after a use of the plasma gun.

Assignees

• Oerlikon Metco Us Inc

Inventors

• Molz Ronald J
• Hawley Dave
• Hermosillo Samrawit
• Colmenares Jose

Classifications

• G01N29/46

  by spectral analysis, e.g. Fourier analysis {or wavelet analysis (spectral signal processing per se G06F17/14)} · CPC title

• B23K10/006

  Control circuits therefor · CPC title

• H05H1/34

  Details, e.g. electrodes, nozzles · CPC title

• B05B7/226

  the material being originally a particulate material · CPC title

• G01F1/66

  by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters · CPC title