Reduced energy welding system and method

• US 10,189,106 B2
• Filed: 12/11/2014
• Issued: 01/29/2019
• Est. Priority Date: 12/11/2014
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Mehn, Peter Donald, Haven, Caleb, Hutchison, Richard Martin, Uecker, James Lee
• Primary Examiner(s): Jennison, Brian W
• Application Number:
  US14/567,665
• Publication Number:
  US 20160167151A1
• Time in Patent Office: 1,510 Days
• 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 conversion circuitry configured to convert incoming power from a source to welding power;

control circuitry coupled to the power conversion circuitry and configured to;

compute command signals via a control process to control the welding power output by the power conversion circuitry in a welding operation, the control process comprising closed loop control of voltage, detection of a predetermined rate of change of a welding parameter, suspension of the closed loop control of voltage and implementation of a current recess based at least in part on detection of the predetermined rate of change of the welding parameter, followed by resumption of closed loop control of voltage after termination of the current recess; and

during the current recess, continue to compute the command signals that would have been applied to the power conversion circuitry but for the current recess, without applying the computed command signals to the power conversion circuitry during the current recess.

2. The system of claim 1, wherein the power conversion 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 process.

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

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

8. The system of claim 1, wherein following the termination of the current recess, the control circuitry applies then-current command signals to the power conversion circuitry continuing as if the current recess had not occurred.

9. A method comprising:

computing command signals, via control circuitry executing a voltage closed loop control, to control welding power output by power conversion circuitry in a welding process during a welding operation;

monitoring, via the control circuitry, at least one welding power parameter;

identifying, via the control circuitry, a rate of change of the at least one welding power parameter;

suspending, via the control circuitry, 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;

during the current recess, continuing to compute, via the control circuitry, the command signals that would have been used to control the welding power but for the current recess; and

resuming, via the control circuitry, voltage closed loop control of the welding power following termination of the current recess.

10. The method of claim 9, comprising, following the termination of the current recess, the control circuitry utilizing then-current command signals to control the power conversion circuitry.

11. The method of claim 9, wherein the rate of change comprises a first time derivative of weld voltage.

12. The method of claim 9, wherein during the welding process 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.

13. The method of claim 9, wherein the welding operation comprises an electrode positive process.

14. The method of claim 9, wherein the welding operation comprises an electrode negative process.

15. The method of claim 9, wherein the current recess is of a predetermined duration.

16. A method comprising:

computing command signals, via control circuitry executing a voltage closed loop control, to control welding power output by power conversion circuitry in a welding process;

monitoring, via the control circuitry, weld voltage;

identifying, via the control circuitry, 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 exceeding the predetermined threshold, the control circuitry suspending voltage closed loop control of the welding power to create a current recess; and

during the current recess, continuing to compute, via the control circuitry, the command signals that would have been used to control the welding power but for the current recess;

resuming, via the control circuitry, voltage closed loop control of the welding power following termination of the current recess.

17. The method of claim 16, wherein during the welding process 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.

18. The method system of claim 16, wherein the current recess is of a predetermined duration.