REDUCED ENERGY WELDING SYSTEM AND METHOD

• US 20160167151A1
• Filed: 12/11/2014
• Published: 06/16/2016
• Est. Priority Date: 12/11/2014
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Uecker, James Lee, Mehn, Peter Donald, Haven, Caleb, Hutchison, Richard Martin
• Granted Patent: US 10,189,106 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23K 9/091 characterised by the circuits
• 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 9/0953 using computing means
• CPC Class Codes: B23K 9/0956 using sensing means, e.g. optical
• CPC Class Codes: B23K 9/1062 with computing means
• CPC Class Codes: B23K 9/173 and of a consumable electrode

Abstract

A welding regime may implements cyclic short circuits under a closed loop voltage control approach. Upon clearing or imminent clearing of the short circuit, a current recess is implemented. The current recess reduces the current that would otherwise be applied to the weld, resulting in multiple benefits. The recess may be implemented by suspending voltage command signals. Following the current recess, normal control is resumed with the then-current voltage command.

Claims

1. A welding system comprising:

power circuitry configured to convert incoming power from a source to welding power;

control circuitry coupled to the power circuitry and configured to implement a control regime to control the welding power output by the power circuitry in a welding operation, the control regime comprising closed loop control of voltage, detection of a predetermined rate of change of a welding parameter, suspension of closed loop control of voltage and implementation of a current recess, followed by resumption of closed loop control of voltage.

2. The system of claim 1, wherein the power circuitry is configured to implement a gas metal arc welding process under the control of the control circuitry, and wherein the system comprises a wire feeder that receives the welding power and applies the welding power to a wire electrode advanced during the welding operation.

3. The system of claim 1, wherein the control circuitry is configured to detect a predetermined rate of change of welding voltage for suspension of the closed loop control of voltage and the implementation of the current recess.

4. The system of claim 1, wherein the current recess reduces current from a level that would result from continued closed loop control of voltage.

5. The system of claim 1, wherein the welding operation comprises an electrode positive regime.

6. The system of claim 1, wherein the welding operation comprises an electrode negative regime.

7. The system of claim 1, wherein the current recess is of a predetermined duration.

8. The system of claim 1, wherein during the current recess the control circuitry is configured to continue to compute command signals that would have been applied to the power circuitry but for the current recess, but not to apply the computed command signals to the power circuitry during the current recess.

9. The system of claim 8, wherein following termination of the current recess, the control circuitry applies then-current command signals to the power circuitry continuing as if the current recess had not occurred.

10. A method comprising:

implementing a voltage closed loop control of welding power in a welding regime;

monitoring welding power parameters;

identifying a rate of change of at least one welding power parameter;

suspending voltage closed loop control of the welding power upon determination that the rate of change of the at least one welding power parameter has reached or exceeded a threshold to create a current recess; and

resuming voltage closed loop control of welding power following the current recess.

11. The method of claim 10, comprising, during the current recess, continuing to compute command signals that would have been used to control the welding power but for the current recess.

12. The method of claim 11, comprising, following termination of the current recess, the control circuitry utilizing the then-current command signals to control the power circuitry.

13. The method of claim 10, wherein the rate of change comprises a first time derivative of weld voltage.

14. The method of claim 10, wherein during the welding regime the weld current comprises a generally saw-tooth profile versus time, and wherein the current recess produces a current gap formed in each tooth of the saw-tooth profile.

15. The method of claim 10, wherein the welding operation comprises an electrode positive regime.

16. The system of claim 10, wherein the welding operation comprises an electrode negative regime.

17. The system of claim 10, wherein the current recess is of a predetermined duration.

18. A method comprising:

implementing a voltage closed loop control of welding power in a welding regime;

monitoring weld voltage;

identifying a rate of change of weld voltage to identify when rate of change of weld voltage exceeds a predetermined threshold;

based upon the weld voltage parameter exceeding the predetermined threshold, suspending voltage closed loop control of the welding power to create a current recess; and

resuming voltage closed loop control of welding power following the current recess.

19. The method of claim 18, wherein during the welding regime the weld current comprises a generally saw-tooth profile versus time, and wherein the current recess produces a current gap formed in each tooth of the saw-tooth profile.

20. The system of claim 18, wherein the current recess is of a predetermined duration.