Dabbing pulsed welding system and method

• US 10,040,143 B2
• Filed: 11/11/2013
• Issued: 08/07/2018
• Est. Priority Date: 12/12/2012
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Davidson, Robert R., Schuh, Richard J., Palmer, Matthew Alex
• Primary Examiner(s): PAIK, SANG YEOP
• Application Number:
  US14/076,705
• Publication Number:
  US 20140158669A1
• Time in Patent Office: 1,730 Days
• Field of Search: 21913001-137 PS
• CPC Class Codes: B23K 9/092 characterised by the shape of the pulses produced
• CPC Class Codes: B23K 9/1012 characterised by parts of the process
• CPC Class Codes: B23K 9/1043 characterised by the electric circuit B23K9/1012 takes precedence

Abstract

A pulsed welding regime includes a peak phase in which energy is added to an electrode and a weld puddle, and a molten ball begins to detach from the electrode, followed by a dabbing phase in which current is significantly reduced to place the ball in the weld puddle with addition of little or no energy. The resulting short circuit clears and the system proceeds to a background phase. The current in the dabbing phase is lower than the current during the background phase. The process may be specifically adapted for particular welding wires, and may be particularly well suited for use with cored wires. The dabbing phase allows for lower energy to be transferred to the sheath of such wires, and resets the arc length after each pulse cycle.

Claims

1. A welding system comprising:

processing circuitry configured to provide a control waveform for a pulsed welding regime, the control waveform comprising a peak phase followed immediately by a dabbing phase followed immediately by a background phase, wherein a first voltage level and a first current level of the control waveform during the dabbing phase are less than a second voltage level and a second current level, respectively, of the control waveform during the background phase, wherein during the peak phase, a ball of molten metal begins to detach from a welding electrode, during the dabbing phase a short circuit is established between the ball and a workpiece, and during the dabbing phase the short circuit is broken; and

power conversion circuitry configured to provide welding power output based upon the control waveform.

2. The system of claim 1, wherein during the background phase the welding power output has a current level of between approximately 25 amps and approximately 125 amps.

3. The system of claim 2, wherein during the dabbing phase the welding power output has a current level of less than approximately 25 amps.

4. The system of claim 3, wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds.

5. The system of claim 1, wherein a peak current level of the control waveform during the peak phase is greater than the first current level during the dabbing phase and the second current level during the background phase.

6. The system of claim 1, wherein the dabbing phase resets an arc length between an end of a welding electrode and a weld puddle into which a ball of molten metal is deposited.

7. The system of claim 1, wherein during the peak and background phases the welding output power is closed-loop controlled to maintain target voltages.

8. A welding method comprising:

generating a pulsed waveform for welding power output, the pulsed waveform comprising a peak phase followed immediately by a dabbing phase followed immediately by a background phase, wherein a first voltage level and a first current level of the pulsed waveform during the dabbing phase are generated at a level lower than a second voltage level and a second current level, respectively, of the pulsed waveform during the background phase, wherein during the peak phase a ball of molten metal begins to detach from a welding electrode, during the dabbing phase a short circuit is established between the ball and a workpiece, during the dabbing phase the short circuit is broken, and during the dabbing phase the first current level of the pulsed waveform is maintained between when the short circuit is established and when the short circuit is broken; and

converting incoming power to welding power based upon the pulsed waveform.

9. The method of claim 8, wherein during the background phase the welding power output has a current level of between approximately 25 amps and approximately 125 amps.

10. The method of claim 9, wherein during the dabbing phase the welding power output has a current level of less than approximately 25 amps.

11. The method of claim 10, wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds.

12. The method of claim 8, wherein a peak current level of the pulsed waveform during the peak phase is greater than the first current during the dabbing phase and a second current level during the background phase.

13. The method of claim 8, wherein during the peak and background phases the welding output power is closed-loop controlled to maintain target voltages.

14. A welding method comprising:

generating a first peak phase of a first pulsed waveform of a welding power output, wherein a first ball of molten metal begins to detach from a welding electrode during the first peak phase;

generating a dabbing phase of the first pulsed waveform of the welding power output, wherein the dabbing phase immediately follows the first peak phase, a short circuit is established during the dabbing phase, and the short circuit is broken during the dabbing phase;

generating a background phase of the first pulsed waveform of the welding power output, wherein the background phase immediately follows the dabbing phase, a current level of the first pulsed waveform during the background phase is less than the current level of the first pulsed waveform during the first peak phase, and the current level of the first pulsed waveform during the background phase is greater than the current level of the first pulsed waveform during the dabbing phase; and

generating a second peak phase of a second pulsed waveform of the welding power output, wherein a second ball of molten metal begins to detach from the welding electrode during the second peak phase, and the second peak phase immediately follows the background phase.

15. The welding method of claim 14, comprising maintaining a voltage level of the first pulsed waveform during the first peak phase using a closed-loop control regime, maintaining the voltage level of the first pulsed waveform during the background phase using the closed-loop control regime, and controlling the current level of the pulsed waveform during the dabbing phase.

16. The welding method of claim 15, wherein controlling the current level of the first pulsed waveform during the dabbing phase comprises adding no current to break the short circuit.

17. The welding method of claim 14, wherein the welding electrode comprises a cored wire.

18. The welding method of claim 14, wherein during the background phase the current level is between approximately 25 amps and approximately 125 amps.

19. The method of claim 14, wherein during the dabbing phase the current level is less than approximately 25 amps.

20. The method of claim 14, wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds.