Dabbing Pulsed Welding System And Method

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.

1 . A welding system comprising:
 a processing circuit configured to provide a control waveform for a pulsed welding regime, the control waveform comprising a peak phase followed by a dabbing phase followed 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 dabbing phase the short circuit is broken; and   a power conversion circuit configured to provide welding power output based upon the control waveform.   
     
     
         2 . The welding 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 welding 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 welding system of  claim 3 , wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds. 
     
     
         5 . The welding 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 welding 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 welding system of  claim 1 , wherein the welding output power is closed-loop controlled during the peak and background phases to maintain one or more target voltages. 
     
     
         8 . A welding system comprising a processing circuit configured to:
 generate a pulsed waveform for welding power output, the pulsed waveform comprising a peak phase followed by a dabbing phase followed by a background phase, wherein a short circuit is established between a ball of molten metal from a welding electrode and a workpiece during the dabbing phase, the short circuit is broken during the dabbing phase, and the first current level of the pulsed waveform is maintained between when the short circuit is established and when the short circuit is broken during the dabbing phase; and   convert incoming power to welding power based upon the pulsed waveform.   
     
     
         9 . The welding system 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 welding system of  claim 9 , wherein during the dabbing phase the welding power output has a current level of less than approximately 25 amps. 
     
     
         11 . The welding system of  claim 10 , wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds. 
     
     
         12 . The welding system 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 welding system of  claim 8 , wherein the welding output power is closed-loop controlled during the peak and background phases to maintain one or more target voltages. 
     
     
         14 . A welding system comprising a processing circuit configured to:
 generate 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;   generate a dabbing phase of the first pulsed waveform of the welding power output, wherein the dabbing phase follows the first peak phase, a short circuit is established during the dabbing phase, and the short circuit is broken during the dabbing phase;   generate a background phase of the first pulsed waveform of the welding power output, wherein 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   generate 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 system of  claim 14 , wherein the processing circuit is further configured to:
 control a voltage level of the first pulsed waveform during the first peak phase using a closed-loop control regime;   control the voltage level of the first pulsed waveform during the background phase using the closed-loop control regime; and   control the current level of the pulsed waveform during the dabbing phase.   
     
     
         16 . The welding system of  claim 15 , wherein the current level of the first pulsed waveform is not increased to break the short circuit during the dabbing phase. 
     
     
         17 . The welding system of  claim 14 , wherein the welding electrode comprises a cored wire. 
     
     
         18 . The welding system of  claim 14 , wherein the current level is between approximately 25 amps and approximately 125 amps during the background phase. 
     
     
         19 . The welding system of  claim 14 , wherein during the dabbing phase the current level is less than approximately 25 amps. 
     
     
         20 . The welding system of  claim 14 , wherein the dabbing phase has a duration of between approximately 1 millisecond and approximately 5 milliseconds.