Online monitoring system and method for a short-circuiting gas metal arc welding process

• US 6,744,011 B1
• Filed: 11/26/2002
• Issued: 06/01/2004
• Est. Priority Date: 11/26/2002
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company), University of Michigan
• Inventors: Hou, Wenkao, Hu, Shixin Jack, Marin, Samuel Paul, Chu, Yunxian, Wang, Pei-Chung
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US10/305,377
• Publication Number:
  US 20040099648A1
• Time in Patent Office: 553 Days
• Field of Search: 219/130.01, 219/130.21, 219/130.31, 219/130.32, 219/130.33
• US Class Current: 219/130.01
• CPC Class Codes: B23K 31/12 relating to investigating the properties, e.g. the weldability, of materials
• CPC Class Codes: B23K 9/0953 using computing means

Abstract

The present invention generally relates to a useful online monitoring system and method of user thereof for monitoring a welding process to determine weld quality, weld process stability, and weld geometry for each weld formed during a welding process. More particularly, the online monitoring system has a computer having a graphical user interface (GUI); at least one welding machine; a communication interface for interfacing communication between the at least one welding machine and the computer; a data acquisition system for acquiring welding signal data, the data acquisition system having an associated memory means; a quality management database for managing and storing acquired welding signal data; and a statistical signal processing system in communication with the data acquisition system for processing welding signal data stored in the data acquisition system associated memory means, and in further communication with the communication interface for communicating processed welding signal data to the GUI.

Claims

1. An online monitoring system for monitoring a short-circuiting gas metal arc welding process, the online monitoring system comprising:

(a) a computer having

(i) a controlling microprocessor, and

(ii) a graphical user interface comprising at least one monitoring window having a plurality of selectable sub-displays, said sub-displays comprising,

(A) an online monitoring display for graphically displaying acquired data and signal processing results and for real time monitoring of weld quality based upon signal information received by the computer from a welding machine via a data acquisition system, said monitoring display comprising sub-displays of weld information, statistical signal processing results, and welding stability analysis;

(B) a parameter setup display for setting up welding parameters and data acquisition parameters used in a data acquisition process during a welding process; and

(C) an advanced set-up display;

(b) at least one welding machine in operable communication with the computer, the welding machine having at least one welding gun in further operable communication with the welding machine;

(c) a communication interface for interfacing communication between the at least one welding machine and the computer;

(d) a data acquisition system adapted for acquiring welding signal data from the welding machine, wherein the data acquisition system is in operable communication with the controlling microprocessor and is in further communication with the at least one welding machine for acquiring welding signal data from the at least one welding machine, and wherein the data acquisition system has an associated memory means;

(e) a quality management database for storing at least one of welding signal data, monitoring results, and diagnostic results in the data acquisition system associated memory means; and

(f) a statistical signal processing system in communication with the data acquisition system for processing the welding signal data stored in the data acquisition system associated memory means and in further communication with the communication interface for communicating processed welding signal data to the graphical user interface.

2. The online monitoring system of claim 1, wherein the online monitoring display comprises:

(a) a weld information sub-display, the weld information sub-display outputs real-time measurable data about a specific weld under consideration;

(b) a real-time acquired welding signal sub-display, the real-time acquired welding signal sub-display tracks a welding voltage applied by the at least one welding machine based upon time or by location along a weld;

(c) a statistical signal processing results sub-display, the statistical signal processing results sub-display displays results of statistical processing algorithms performed on acquired welding data, wherein the acquired data is acquired by the data acquisition system;

(d) a stability analysis sub-display, the stability analysis sub-display displays a time-frequency spectrum analysis of short-circuiting occurrences occurring during a welding cycle;

(e) a user interface sub-display, the user interface sub-display provides at least one selectable drop-down menu and at least one selectable button which allow a user to selectively display acquired and signal processed welding signal data on the at least one on-line monitoring window.

3. The online monitoring system of claim 1 wherein the parameter setup display comprises:

(a) a welding conditions field for obtaining information about actual or expected welding conditions for a desired welding application;

(b) a workpiecc information field for defining information about a workpiece to be welded;

(c) a data acquisition parameter portion for allowing a user to specify parameters over which sampling of a welding operation is to be monitored, the data acquisition parameter portion allows a user to define a sample rate for acquiring welding signal data for a desired weld length; and

(d) a data log portion for allowing a user to selectively store data, create files, and access files.

4. The online monitoring system of claim 3 wherein the welding conditions field defines specific welding conditions for a user-identified welding process, the welding conditions defined comprise:

(a) a type of joint to be welded;

(b) a type of power source for the welding operation;

(c) an electrode flux wire feed rate;

(d) a value for a welding voltage supplied to the at least one welding machine;

(e) a welding speed of the at least one welding machine;

(f) a stick out value of a wire flux electrode from an electrode wire flux cover;

(g) a gas flow rate of a shielding gas supplied to the at least one welding gun in communication with the welding machine; and

(h) an angle of a welding gun in communication with the at least one welding gun in communication with the welding machine relative to a base metal being welded.

5. The online monitoring system of claim 3, wherein the advanced set-up display comprises:

(a) a configurable calibration coefficient portion for selectively entering calibration coefficients into corresponding current sensor and voltage sensor calibration fields; and

(b) a variables threshold portion having

(i) fields corresponding to operating parameters selected from voltage, current, arc-time, short-circuit time, and heat input, the fields each having an associated help button located within the advanced set-up display for accessing a database of pre-programmed values that help to guide a user in the selection of process parameters, and

(ii) a configurable condition number portion having an associated help button for selectably defining a threshold value used in signal conditioning of current and voltage signals acquired by the data acquisition system.

6. The online monitoring system of claim 3, wherein the data acquisition system further comprises:

(a) at least two sensors, the at least two sensors having

(i) at least one voltage sensor for measuring analog voltage signals communicated from the at least one welding machine to the at least one voltage sensor, and

(ii) at least one current sensor for measuring current signals communicated from the at least one welding machine to the at least one current sensor; and

(b) a digital signal processor in operable communication with the at least two sensors and in further operable communication with both the online monitoring controlling microprocessor and the statistical signal processing system.

7. The online monitoring system of claim 6, wherein the at least two sensors comprise:

a plurality of sensors, the plurality of sensors may be used to monitor a plurality of welding signals associated with the welding parameters defined in the welding parameter setup display; and

a digital signal processor in operable communication with the at least two sensors and in further operable communication with both the online monitoring controlling microprocessor and the statistical signal processing system.

8. The online monitoring system of claim 7, wherein the digital signal processor is in operable communication with the online monitoring system microprocessor for processing signals acquired during data acquisition and is in further operable communication with the graphical user interface for graphically displaying acquired and processed signals on the online monitoring display, the digital signal processor comprises:

(a) a signal conditioner for conditioning signals received from the at least two sensors, respectively; and

(b) an analog to digital converter board for digitizing conditioned signals and for communicating the digitized conditioned signals to the quality management database for storage in the data acquisition system associated memory means.

9. The online monitoring system of claim 8 wherein the signal conditioner comprises:

(a) an input port for receiving analog current and voltage signals from the at least two sensors, respectively; and

(b) an output port for outputting conditioned analog signals received from the input port to the analog to digital converter board, wherein the signal conditioner is capable of attenuating and discriminating voltage and current welding signals measured by the at least two sensors.

10. The online monitoring system of claim 9 wherein the analog to digital converter board is used for

(a) sampling conditioned analog signals at a predefined data acquisition sample rate;

(b) digitizing the analog signals transmitted from the signal conditioner output port into discrete values representing a signal strength of signals sensed by the at least two sensors during a welding cycle; and

(c) storing the discrete values in the data acquisition system associated memory means.

11. The online monitoring system of claim 6, wherein the data acquisition system begins acquiring data when the at least one voltage sensor receives a triggering signal from the at least one welding machine.

12. The online monitoring system of claim 11 wherein the triggering signal comprises a first rising edge of a welding voltage signal.

13. The online monitoring system of claim 3 wherein the statistical signal processing system cooperates with the graphical user interface to selectively process the welding signal data communicated from the data acquisition system associated memory means to the statistical signal processing system by performing predefined algorithms to determine quality, stability, and geometry estimation of welds made during a welding process.

14. The online monitoring system of claim 13 wherein the predefined algorithms comprise:

a spectrum analysis algorithm for determining a spectrum analysis for frequency and timing of short-circuiting signals occurrences occurring during a monitored welding process;

a moving mean algorithm for filtering out signals not falling within predefined variable thresholds;

a standard deviation algorithm for determining a standard deviation of the, acquired welding data; and

a weld bead geometry algorithm for estimating weld bead geometry of a weld formed during the GMAW process.

15. The online monitoring system of claim 13, wherein statistically signal processed data results of the statistical processed signals are processed according to a user-defined graphical display format and are communicated to the graphical user interface for selectively displaying the signal processing results on the online monitoring display.

16. The online monitoring system of claim 1, wherein the short-circuiting gas metal arc welding process monitors welding operations performed using low carbon sheet steel.

18. A method of using the online monitoring system of claim 1 to monitor and control a gas metal arc metal welding process according to a user defined format, the method comprising the steps of:

a) setting welding and data acquisition parameters;

b) setting a welding voltage'"'"'s first rising edge as a triggering signal to start a data acquisition process,

c) determining whether the triggering signal was received;

d) waiting for a triggering signal if a triggering signal was not received;

e) determining whether to perform an off-line signal analysis if a triggering signal was not received;

f) repeating steps c)-e) if an off-line signal analysis is not needed;

g) performing an off-line signal analysis if an off-line signal analysis is needed;

h) loading existing voltage and current data stored in a data acquisition memory means when an off-line signal analysis is performed;

i) acquiring current and voltage from an active welding cycle upon receiving a triggering signal;

j) performing signal processing algorithms on the acquired or the loaded current and voltage data.

17. An online monitoring system for monitoring a short-circuiting gas metal arc welding process, the online monitoring system comprising:

(a) a computer having

(i) a controlling microprocessor, and

(ii) a graphical user interface for providing a configurable interface for a user of the computer, the graphical user interface having a monitoring window, the monitoring window having configurable sub-displays, the configurable sub-displays having

(A) an online monitoring display for graphically displaying acquired data and signal processing results,

(B) a parameter setup display for setting up welding parameters and data acquisition parameters used in a data acquisition process during a welding process, and

(C) an advanced-set-up display having

(I) a configurable calibration coefficient portion for selectively entering calibration coefficients into corresponding current sensor and voltage sensor calibration fields, and

(II) a variables threshold portion for defining threshold operating parameters to be used during a welding process;

(b) at least one welding machine in operable communication with the computer;

(c) a communication interface for interfacing communication between the at least one welding machine and the computer;

(d) a data acquisition system in operable communication with the controlling microprocessor and in further communication with the at least one welding machine for acquiring welding signal data from the at least one welding machine, the data acquisition system having an associated memory means;

(e) a quality management database for storing at least one of welding signal data, monitoring results, and diagnostic results in the data acquisition system associated memory means; and

(f) a statistical signal processing system in communication with the data acquisition system for processing the welding signal data stored in the data acquisition system associated memory means and in further communication with the communication interface for communicating processed welding signal data to the graphical user interface.