SYSTEMS, METHODS, AND APPARATUSES FOR MONITORING WELD QUALITY

• US 20110114615A1
• Filed: 05/07/2010
• Published: 05/19/2011
• Est. Priority Date: 11/13/2009
• Status: Active Grant

• Current Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Original Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Inventors: Chantry, Bruce J., Daniel, Joseph A.
• Granted Patent: US 8,569,646 B2
• Time in Patent Office: Days
• US Class Current: 219/137.R
• CPC Class Codes: B23K 31/02 relating to soldering or welding dip or wave soldering in the manufacture of printed circuits H05K3/34
• CPC Class Codes: B23K 31/12 relating to investigating the properties, e.g. the weldability, of materials
• CPC Class Codes: B23K 9/095 Monitoring or automatic control of welding parameters
• CPC Class Codes: B23K 9/0953 using computing means
• CPC Class Codes: B23K 9/0956 using sensing means, e.g. optical
• CPC Class Codes: G09B 19/24 Use of tools

Abstract

An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Claims

1. A method of quantifying a weld'"'"'s quality by monitoring an electric arc welder as the welder performs a selected arc welding process by creating actual welding parameters between an advancing wire and a workpiece, said selected process controlled by command signals to a power supply of said welder, said method comprising:

(a) generating a series of rapidly repeating wave shapes, each wave shape constituting a weld cycle with a cycle time;

(b) dividing said wave shapes into states;

(c) measuring a plurality of selected weld parameters occurring in one or more of said states at an interrogation rate over a period of time repeatedly during said welding process; and

(d) calculating a plurality of quality parameters for each of said states based on said measurements of said selected weld parameters during said welding process,

wherein said quality parameters represent an overall quality measurement of said weld.

2. The method of claim 1, further comprising:

(e) comparing a value of each of said quality parameters calculated for each period of time to a corresponding expected quality parameter value to determine if a difference between said calculated quality parameter value and said expected quality parameter value exceeds a predetermined threshold; and

(f) if said difference exceeds said threshold, weighting said calculated quality parameter value with a magnitude weight based on said difference, and weighting said calculated quality parameter value with a time contribution weight based on a time contribution of its state to the wave shape including said state.

3. The method of claim 1, wherein said interrogation rate is 120 kHz.

4. The method of claim 1, wherein said period of time is approximately 250 ms.

5. The method of claim 1, wherein said selected weld parameters are measured for all of said states.

6. The method of claim 1, wherein said selected weld parameters include, for each of said states, a count of said measurements taken for each of said selected weld parameters in said period of time, a mean voltage voltage in said period of time, a root mean square voltage RMSV in said period of time, a voltage variance V_var in said period of time, a mean current current in said period of time, a root mean square current RMSI in said period of time, and a current variance I_var in said period of time,

wherein voltage=a sum of voltages measured in said period of time/said count of voltage measurements,

wherein

7. The method of claim 6, wherein said quality parameters include a quality count average QCA for each state calculated as:

8. The method of claim 7, wherein said quality parameters include a quality count standard deviation QCSD for each state calculated as one of:

9. The method of claim 6, wherein said quality parameters include a quality voltage average QVA for each state calculated as:

10. The method of claim 9, wherein said quality parameters include a quality voltage standard deviation QVSD for each state calculated as one of:

11. The method of claim 6, wherein said quality parameters include a quality current average QIA for each state calculated as:

12. The method of claim 11, wherein said quality parameters include a quality current standard deviation QISD for each state calculated as one of:

13. The method of claim 6, wherein said quality parameters include a quality voltage variance average QVVA for each state calculated as:

14. The method of claim 13, wherein said quality parameters include a quality voltage variance standard deviation QVVSD for each state calculated as one of:

15. The method of claim 6, wherein said quality parameters include a quality current variance average QIVA for each state calculated as:

16. The method of claim 15, wherein said quality parameters include a quality current variance standard deviation QIVSD for each state calculated as one of:

17. The method of claim 1, further comprising:

(e) using said quality parameters in a metric to evaluate subsequent welds.

18. A method of evaluating a plurality of welds performed under substantially the same conditions and according to substantially the same arc welding process by monitoring an electric arc welder as the welder performs the welds according to the arc welding process by creating actual welding parameters between an advancing wire and a workpiece, said selected process controlled by command signals to a power supply of said welder, said method comprising:

during each weld;

(a) generating a series of rapidly repeating wave shapes, each wave shape constituting a weld cycle with a cycle time;

(b) dividing said wave shapes into states;

(c) measuring a selected weld parameter occurring in one of said states at an interrogation rate over a period of time to obtain a data set for said selected weld parameter;

(d) for each period of time, calculating a quality value for said selected weld parameter from said data set;

(e) comparing each quality value to an expected quality value to determine if a difference between said quality value and said expected quality value exceeds a predetermined threshold;

(f) if said difference exceeds said threshold, weighting said quality value with a magnitude weight based on said difference, and weighting said quality value with a time contribution weight based on a time contribution of said state to its wave shape; and

(g) using all of said quality values, including any weighted quality values, obtained during said welding process to determine a quality score for said weld.

19. The method of claim 18, further comprising:

(h) rejecting said weld if its quality score is within a first predefined range of quality scores; and

(i) accepting said weld if its quality score is within a second predefined range of quality scores.

20. The method of claim 18, further comprising:

(h) permanently associating each weld with its corresponding quality score.

21. The method of claim 18, wherein said interrogation rate is 120 kHz.

22. The method of claim 18, wherein said period of time is approximately 250 ms.

23. The method of claim 18, wherein said selected weld parameter is arc current.

24. The method of claim 18, wherein said selected weld parameter is arc voltage.

25. A monitor for monitoring an electric arc welder as the welder performs a selected arc welding process by creating actual welding parameters between an advancing wire and a workpiece to form a weld, said process involving an arc and being defined by a series of rapidly repeating wave shapes of command signals for said parameters, each wave shape constituting a weld cycle with a cycle time, said monitor comprising:

a logic state controller for segmenting each of said wave shapes into a series of time segmented states;

a circuit for selecting a specific wave shape state;

a reader device for reading a plurality of selected weld parameters occurring in one or more of said states at an interrogation rate over a period of time repeated during the welding process to obtain a data set for said selected weld parameter;

a circuit for calculating a plurality of quality parameters for each of said states based on said selected weld parameters,

wherein said quality parameters represent an overall quality measurement of said weld.

26. The monitor of claim 25, further comprising:

a circuit for comparing a value of each of said quality parameters calculated for each period of time to a corresponding expected quality parameter value to determine if a difference between said calculated quality parameter value and said expected quality parameter value exceeds a predetermined threshold; and

a circuit for weighting said calculated quality parameter value with a magnitude weight based on said difference, and weighting said calculated quality parameter value with a time contribution weight based on a time contribution of its state to the wave shape including said state, if said difference exceeds said threshold.

27. The monitor of claim 25, wherein said interrogation rate is 120 kHz.

28. The monitor of claim 25, wherein said period of time is approximately 250 ms.

29. The monitor of claim 25, wherein said selected weld parameters are read for all of said states.

30. The monitor of claim 25, wherein said selected weld parameters include, for each of said states, a count of said measurements taken for each of said selected weld parameters in said period of time, a mean voltage voltage in said period of time, a root mean square voltage RMSV in said period of time, a voltage variance V_var in said period of time, a mean current current in said period of time, a root mean square current RMSI in said period of time, and a current variance I_var in said period of time,

wherein voltage=a sum of voltages measured in said period of time/said count of voltage measurements,

wherein

31. The monitor of claim 30, wherein said quality parameters include a quality count average QCA for each state calculated as:

32. The monitor of claim 31, wherein said quality parameters include a quality count standard deviation QCSD for each state calculated as one of:

33. The monitor of claim 30, wherein said quality parameters include a quality voltage average QVA for each state calculated as:

34. The monitor of claim 33, wherein said quality parameters include a quality voltage standard deviation QVSD for each state calculated as one of:

35. The monitor of claim 30, wherein said quality parameters include a quality current average QIA for each state calculated as:

36. The monitor of claim 35, wherein said quality parameters include a quality current standard deviation QISD for each state calculated as one of:

37. The monitor of claim 30, wherein said quality parameters include a quality voltage variance average QVVA for each state calculated as:

38. The monitor of claim 37, wherein said quality parameters include a quality voltage variance standard deviation QVVSD for each state calculated as one of:

39. The monitor of claim 30, wherein said quality parameters include a quality current variance average QIVA for each state calculated as:

40. The monitor of claim 39, wherein said quality parameters include a quality current variance standard deviation QIVSD for each state calculated as one of:

41. The monitor of claim 25, further comprising:

(e) using said quality parameters in a metric to evaluate subsequent welds.

42. A method of evaluating a plurality of operators performing an arc welding process by monitoring an electric arc welder associated with each of the operators, as each welder is used by its respective operator to perform said arc welding process by creating actual welding parameters between an advancing wire and a workpiece with said arc welding process controlled by command signals to a power supply of said welder, said method comprising:

for each operator,

(a) generating a numerical score indicating a quality measurement of a weld formed according to said arc welding process relative to a predetermined baseline weld;

(b) measuring an amount of time said operator spends performing said arc welding process; and

(c) associating said numerical score and said welding time with said operator.

43. The method of claim 42, wherein step (a) comprises:

(a1) generating a series of rapidly repeating wave shapes, each wave shape constituting a weld cycle with a cycle time;

(a2) dividing said wave shapes into states;

(a3) measuring a selected weld parameter occurring in one of said states at an interrogation rate over a period of time to obtain a data set for said selected weld parameter;

(a4) for each period of time, calculating a quality value for said selected weld parameter from said data set;

(a5) comparing each quality value to an expected quality value to determine if a difference between said quality value and said expected quality value exceeds a predetermined threshold;

(a6) if said difference exceeds said threshold, weighting said quality value with a magnitude weight based on said difference, and weighting said quality value with a time contribution weight based on a time contribution of said state to its wave shape; and

(a7) using all of said quality values, including any weighted quality values, obtained during said arc welding process to determine said numerical score.

44. The method of claim 42, wherein step (b) comprises, for each operator, determining a percentage of an evaluation period said operator spends performing said arc welding process.

45. The method of claim 42, wherein each of said operators is performing substantially the same arc welding process under substantially the same conditions.