Welding system for ac welding with reduced spatter

Patent metadata

Field	Value
Publication number	US-2017113293-A1
Application number	US-201514923541-A
Country	US
Kind code	A1
Filing date	Oct 27, 2015
Priority date	Oct 27, 2015
Publication date	Apr 27, 2017
Grant date	—

Abstract

A welding system comprises a welding power source that provides an alternating current in a selected wave form having a set of positive and negative portions, the negative portion consisting of a peak, tailout, and background phase, and the positive portion consisting of a peak, tailout, and background; wherein the power source provides an upward ramping current during the pinch and detachment phase, switches to an electrode negative current during the negative peak, tailout, and background phases, and switches to a subsequent electrode positive portion; wherein, the positive portion may repeat prior to the next shorting event.

First claim

What is claimed is:

1 . A welding system comprising:
a welding power source that provides an alternating current in a selected wave form having a positive polarity pinch and detachment phase, a negative polarity portion consisting of a negative peak current phase, a negative tail out phase, a negative background phase, and a subsequent positive polarity portion consisting of a positive peak current phase, a positive tail out current phase, a positive background phase; wherein the power source provides an upward ramping current during the positive pinch and detachment phase.

2 . The welding system of claim 1 , wherein, the positive polarity portion may repeat multiple times prior to the next shorting event.

3 . The welding system of claim 1 , wherein the wave form is a surface tension transfer wave form.

4 . The welding system of claim 1 , wherein the welding power source includes a waveform generator adapted to provide the selected wave form, wherein the wave form generator is adapted to anticipate the end of a short circuit condition based on at least one of dv/dt, impedance, and timer based on a predictive model, wherein the power source switches to the electrode negative phase following the end of the detachment phase.

5 . The welding system of claim 1 , wherein the welding power source provides the pinch phase as electrode positive.

6 . The welding system of claim 1 , wherein the wave form includes a detachment phase, and wherein the welding power source reignites an arc during the detachment phase with an electrode positive current.

7 . The welding system of claim 6 , wherein after the detachment phase, the wave form switches to an electrode negative current adapted to push a distal end of the electrode away from a weld puddle.

8 . The welding system of claim 1 , wherein the wave form further includes a background phase and wet in phase before the pinch phase, wherein the background phase and wet in phase are electrode positive, the background phase being at a higher amperage than the wet in phase.

9 . The welding system of claim 1 , wherein the welding power source provides a current from about 20 amps to about 40 amps during the wet in phase.

10 . The welding system of claim 1 , wherein during the background phase, the welding power source provides a background current in the range of about 20 to 100 amps.

11 . The welding system of claim 1 , wherein during the peak current phase, the welding power source provides a current in the range of about 150 to 350 amps.

12 . The welding system of claim 1 , wherein each of the at least one of the positive polarity pulses has a duration in the range of about 0.5 to 2 milliseconds.

13 . The welding system of claim 1 wherein the welder power source includes a controller in communication with a state function generator, a digital signal processor in communication with the state function generator, an inverter in communication with the digital signal processor, wherein the inverter is electrically connected to a power source, a polarity switching circuit and a current reducer.

14 . The welding system of claim 13 , wherein the switching circuit is an H-bridge polarity switch.

15 . The welding system of claim 13 , wherein the state function generator is electrically connected to at least one of the torch and the workpiece to receive voltage or current feedback therefrom.

16 . A welding system comprising:
a. a welding power source adapted to provide an alternating current in a selected wave form to an electrode; b. wherein the electrode is consumable and wherein the wave form includes at least one phases during which the electrode produces a molten droplet at an exposed end thereof, wherein a short between the electrode and the workpiece occurs as the molten droplet detaches from the electrode; c. the welding power source being adapted to detect the short and provide an electrode negative peak current to the electrode following transfer of the molten droplet to the workpiece; d. the welding power source being adapted to switch the current from electrode negative to electrode positive prior to the next pinch phase. e. wherein the welding power source generates a jet force that pushes the distal end of the electrode away from the puddle.

17 . The welding system of claim 16 , wherein the welding power source is adapted to switch the current from electrode positive to electrode negative after the detachment phase.

18 . A welding system for performing an arc welding process by generating an electric welding waveform to produce a series of electric arc pulses between an advancing welding electrode and a metal workpiece, said system comprising:
a first configuration of electronic components to generate an alternating current, the first configuration of electronic components providing the alternating current in a set of positive and negative portions, the negative portion consisting of a peak, tailout, and background phase, and the positive portion consisting of a peak, tailout, and background phase, a second configuration of electronic components to generate a pinch current phase of said electric welding waveform, wherein said pinch current phase provides an increasing pinch current level; and a third configuration of electronic components to decrease a current level of said electric welding waveform below said background current level at an end of said background current phase in response to said electrode shorting to said workpiece, wherein said third configuration of electronic components applies an electrode positive current to reignite the arc after said electrode shorting; and wherein said first configuration of electronic components provides an electrode negative peak following the short detachment.

19 . The system of claim 18 further comprising a fourth configuration of electronic components to generate at least one positive polarity heat-increasing current pulse of said electric welding waveform after said negative portion.

20 . The system of claim 19 further comprising a fifth configuration of electronic components to decrease a current level of said electric welding waveform below said background current level at an end of said pinch current phase in anticipation of said electrode de-shorting from said workpiece.

Assignees

• Lincoln Global Inc

Inventors

• Henry Judah B
• Hearn James E

Classifications

• B23K9/092 Primary

  characterised by the shape of the pulses produced · CPC title

• B23K9/09

  Arrangements or circuits for arc welding with pulsed current or voltage · CPC title

• B23K9/1043 Primary

  characterised by the electric circuit (B23K9/1012 takes precedence) · CPC title

• B23K9/091

  characterised by the circuits · CPC title

• B23K9/164

  making use of a moving fluid · CPC title