Series arc welder

• US 20070158324A1
• Filed: 01/09/2006
• Published: 07/12/2007
• Est. Priority Date: 01/09/2006
• Status: Active Grant

• Current Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Original Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Inventors: Myers, Russell, O'Donnell, Timothy
• Granted Patent: US 9,579,742 B2
• Time in Patent Office: Days
• US Class Current: 219/137.710
• CPC Class Codes: B23K 9/1068 Electric circuits for the supply of power to two or more arcs from a single source
• CPC Class Codes: B23K 9/124 Circuits or methods for feeding welding wire
• CPC Class Codes: B23K 9/1735 making use of several electrodes
• CPC Class Codes: B23K 9/188 making use of several electrodes

Abstract

An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece. The welder comprises: a leading electrode driven toward a point in the groove by a first wire feeder operated at a first speed by a first motor with a speed control input and a tachometer derived first feedback signal, a trailing electrode driven toward the same point by a second wire feeder operated at a second speed by a second motor with a speed control input and a tachometer derived second feedback signal, a first power source directing a first current to flow through the leading electrode and a second power source causing a second current to flow through the trailing electrode with the current flow being in a series arc circuit. The second power source being grounded to the workpiece to modify the series arc current so ground current flows to the workpiece whereby the second current is generally equal to the first current minus the ground current.

Claims

1. An electric arc welder for depositing weld metal along a groove between two edges or a metal workpiece, said welder comprising:

a leading electrode driven toward a point in said groove by a first wire feeder operated at a first speed by a first motor with a speed control input, a trailing electrode driven toward said point by a second wire feeder operated at second speed by a second motor with a speed control input and a power source for creating an arc between said electrodes to melt said electrodes, said first motor having a tachometer to generate a feedback WFS signal, said power source having a wire feed speed controlling device for creating a control WFS signal directed to the control input of one of said motors to maintain said one motor at a set speed based upon said feedback WFS signal and a slave circuit to connect said control WFS signal to the control input of the other of said motor.

2. A welder as defined in claim 1 wherein said first and second speed are generally the same with said control WFS connected directly to both said control input of said first motor and said control input of said second motor.

3. A welder as defined in claim 2 wherein one of said trailing electrode is grounded to said workpiece.

4. A welder as defined in claim 1 wherein one of said electrodes is grounded to said workpiece.

5. A welder as defined in claim 4 including a short detector to detect a short between said trailing electrode and said workpiece and a circuit to maintain the current in said second electrode generally constant during at least a portion of said short.

6. A welder as defined in claim 5 wherein said constant current is maintained during most of said short.

7. A welder as defined in claim 4 including a short detector to detect a short between said trailing electrode and said workpiece and a circuit to increase the current in the second electrode during at least a portion of said short.

8. A welder as defined in claim 7 wherein said increased current is maintained during most of said short.

9. A welder as defined in claim 1 including a short detector to detect a short between said trailing electrode and said workpiece and a program to maintain the current in said power source generally constant during at least a portion of said short.

10. A welder as defined in claim 9 wherein said constant current is maintained during most of said short.

11. A welder as defined in claim 1 including a short detector to detect a short between said trailing electrode and said workpiece and a program to decrease the current of said power source during at least a portion of said short.

12. A welder as defined in claim 11 wherein said decreased current is maintained during most of said short.

13. A welder as defined in claim 1 wherein said slave circuit includes a device for decreasing the level of said control WFS signal before it is connected to said control input of said second motor.

14. A welder as defined in claim 13 wherein said device is a buck converter.

15. A welder as defined in claim 1 including a device for reducing the level of said control WFS signal before it is connected to said control input of said first motor.

16. A welder as defined in claim 1 wherein said motors have different ratio gear reducers to drive said wire feeders at different speeds.

17. A welder as defined in claim 1 wherein said one of said motors is said first motor.

18. An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece, said welder comprising:

a leading electrode driven toward a point in said groove by a first wire feeder operated at a first speed by a first motor with a speed control input and a tachometer derived first feedback signal, a trailing electrode driven toward said point by a second wire feeder operated at a second speed by a second motor with a speed control input and a tachometer derived second feedback signal, a first power source directing a first current to flow through said leading electrode and a second power source causing a second current to flow through said trailing electrode with said current flow being in a series arc circuit.

19. A welder as defined in claim 18 wherein said second power source is grounded to said workpiece to modify said series arc current so ground current flows to said workpiece whereby said second current is generally equal to said first current minus said ground current.

20. A welder as defined in claim 19 wherein said first speed is generally equal to said second speed.

21. A welder as defined in claim 18 wherein said first speed is generally equal to said second speed.

22. A welder as defined in claim 21 including a short detector to detect a short between said trailing electrode and said workpiece and a program to maintain the current in said second power source generally constant during at least a portion of said short.

23. A welder as defined in claim 22 wherein said constant current is maintained during most of said short.

24. A welder as defined in claim 19 including a short detector to detect a short between said trailing electrode and said workpiece and a program to maintain the current in said second power source generally constant during at least a portion of said short.

25. A welder as defined in claim 24 wherein said constant current is maintained during most of said short.

26. A welder as defined in claim 18 including a short detector to detect a short between said trailing electrode and said workpiece and a program to maintain the current in said second power source generally constant during at least a portion of said short.

27. A welder as defined in claim 26 wherein said constant current is maintained during most of said short.

28. A welder as defined in claim 21 including a short detector to detect a short between said trailing electrode and said workpiece and a program to decrease the current of the second power source during at least a portion of said short.

29. A welder as defined in claim 28 wherein said decreased current is maintained during most of said short.

30. A welder as defined in claim 19 including a short detector to detect a short between said trailing electrode and said workpiece and a program to decrease the current in the second power source during at least a portion of said short.

31. A welder as defined in claim 30 wherein said decreased current is maintained during most of said short.

32. A welder as defined in claim 18 including a short detector to detect a short between said trailing electrode and said workpiece and a program to decrease the current in the second power source during at least a portion of said short.

33. A welder as defined in claim 32 wherein said decreased current is maintained during most of said short.

34. A welder as defined in claim 19 wherein each of said power sources includes a high speed switching output stage for creating one of said currents with selected output waveform generated by a waveform generator controlling a pulse width modulator circuit to determine the current operation of its output stage.

35. A welder as defined in claim 18 wherein each of said power sources includes a high speed switching output stage for creating one of said currents with selected output waveform generated by a waveform generator controlling a pulse width modulator circuit to determine the current operation of its output stage.

36. A welder as defined in claim 35 wherein said power sources are connected in series.

37. A welder as defined in claim 34 wherein said power sources are connected in series.

38. A welder as defined in claim 19 wherein said power sources are connected in series.

39. A welder as defined in claim 18 wherein said power sources are connected in series.

40. A welder as defined in claim 35 wherein said power sources are connected in parallel.

41. A welder as defined in claim 34 wherein said power sources are connected in parallel.

42. A welder as defined in claim 19 wherein said power sources are connected in parallel.

43. A welder as defined in claim 18 wherein said power sources are connected in parallel.

44. A welder as defined in claim 35 including a wire feed speed controller associated with each power source, and a voltage circuit to detect a given voltage associated with one of said electrodes and a controller with a circuit for adjusting said speed control input based upon said sensed voltage.

45. A welder as defined in claim 34 including a wire feed speed controller associated with each power source, and a voltage circuit to detect a given voltage associated with one of said electrodes and a controller with a circuit for adjusting said speed control input based upon said sensed voltage.

46. A welder as defined in claim 19 including a wire feed speed controller associated with each power source, and a voltage circuit to detect a given voltage associated with one of said electrodes and a controller with a circuit for adjusting said speed control input based upon said sensed voltage.

47. A welder as defined in claim 18 including a wire feed speed controller associated with each power source, and a voltage circuit to detect a given voltage associated with one of said electrodes and a controller with a circuit for adjusting said speed control input based upon said sensed voltage.

48. A welder as defined in claim 35 wherein said waveforms are AC waveforms in phase with each other.

49. A welder as defined in claim 19 including a short detector to detect a short between said trailing electrode and said workpiece and a circuit to clear said short by controlling the current of said second power source.

50. A welder as defined in claim 19 including a first sensing circuit to sense a first voltage associated with said first wire feeder and a circuit to adjust said first speed based upon said first voltage.

51. A welder as defined in claim 50 including a second sensing circuit to sense a second voltage associated with said second wire feeder and a circuit to adjust said second speed based upon said second voltage.

52. A welder as defined in claim 18 including a first sensing circuit to sense a first voltage associated with said first wire feeder and a circuit to adjust said first speed based upon said first voltage.

53. A welder as defined in claim 52 including a second sensing circuit to sense a second voltage associated with said second wire feeder and a circuit to adjust said second speed based upon said second voltage.