Electrode negative pulse welding system and method

• US 10,835,984 B2
• Filed: 09/17/2014
• Issued: 11/17/2020
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Marschke, Bryan Dustin, D'Arcy, Amanda Jean
• Primary Examiner(s): Abraham, Ibrahime A
• Assistant Examiner(s): Norton, John J
• Application Number:
  US14/489,322
• Publication Number:
  US 20150001197A1
• Time in Patent Office: 2,253 Days
• Field of Search: 21913051, 219137 PS
• CPC Class Codes: B23K 9/092 characterised by the shape of the pulses produced
• CPC Class Codes: B23K 9/095 Monitoring or automatic control of welding parameters
• CPC Class Codes: B23K 9/1006 Power supply

Abstract

A welding system includes a power source configured to generate power and deliver the power to a welding torch. The power is provided in accordance with an electrode negative pulse welding regime that includes a cyclic peak, followed by a stabilization phase, then a return to a background level. The stabilization phase has a generally parabolic current shape, and is performed in a current-closed loop manner until a transition point, where control becomes voltage-closed loop until the background level is reached. Resulting weld performance is improved, with a globular-like transfer mode, reduced shorts and enhanced arc stability.

Claims

1. A welding system, comprising:

a power source configured to generate welding power and deliver the welding power to a welding torch, wherein the welding torch is coupled to a negative output terminal of the power source;

a welding wire feeder configured to advance a metal cored electrode into the welding torch at a rate of advancement; and

control circuitry configured to implement an electrode negative pulse welding regime comprising;

closed loop control of the welding power to maintain the voltage output at a desired level during a peak phase and allowing the current output to float during the peak phase,

a transition from the closed loop control of the welding power during the peak phase to parabolic closed loop control of the welding power during a stabilization phase following the peak phase, and

a transition from the parabolic closed loop control of the welding power during the stabilization phase to closed loop control of the welding power during a return phase following the stabilization phase in response to a current signal indicating that an output current has achieved a predetermined value.

2. The welding system of claim 1, wherein the stabilization phase comprises a down ramp of current defined by a current-per-unit-time-squared relationship.

3. The welding system of claim 1, wherein the return phase comprises voltage-closed loop control with a proportional only gain on voltage.

4. The welding system of claim 1, wherein a leading edge of the peak phase comprises a linear current-closed loop ramp to a pre-determined transition point.

5. The welding system of claim 1, wherein the peak phase comprises a voltage-closed loop phase with a voltage command of the welding power during the peak phase is between 18 and 28 V.

6. The welding system of claim 1, wherein the predetermined value of the output current level at the transition between the stabilization phase and the return phase is programmable to a value between 25 and 325 A.

7. The welding system of claim 6, wherein the transition between the stabilization phase and the return phase is above 50 A.

8. The welding system of claim 1, wherein the transition between the stabilization phase and the return phase is above 100 A.

9. The welding system of claim 1, wherein the electrode negative pulse welding regime produces a globular transfer of molten metal from the electrode to a weld puddle.

10. The welding system of claim 1, wherein the parabolic closed loop control during the stabilization phase is a current-closed loop control, and the closed loop control during the return phase is a voltage-closed loop control.

11. The welding system of claim 1, wherein the closed loop control of the welding power during the return phase maintains the voltage output at a desired level and allows the current output to float during the return phase.