Arc welding method and apparatus for arc welding

Patent metadata

Field	Value
Publication number	US-9132501-B2
Application number	US-200913146320-A
Country	US
Kind code	B2
Filing date	Feb 24, 2009
Priority date	Feb 24, 2009
Publication date	Sep 15, 2015
Grant date	Sep 15, 2015

Abstract

An electric arc welding method is provided, wherein an electrode assembly comprises at least two fusible continuous electrodes acting on a workpiece for generating a weld pool via electric arcs, wherein the at least two electrodes are arranged in sequential order relative to a welding direction and laterally separated relative to each other, wherein steps are performed of monitoring at least one stability parameter (Stab_par) for each electrode of the electrode assembly; determining if one electrode of the electrode assembly violates a stability criterion (Crit); separating at least temporarily the one electrode violating the stability criterion (Crit) from one or more adjacent electrodes when a violation of the stability criterion (Crit) of the one electrode is detected.

First claim

The invention claimed is:

1. An electrode assembly for electric arc welding, comprising
at least three fusible continuously-fed electrodes for generating a weld pool via electric arcs in a workpiece,
wherein a weld head jaw is arranged for each of the at least three electrodes wherein the at least three electrodes are arranged in sequential order with respect to a welding direction when the electrode assembly is in an operating mode, and
wherein at least one of the trailing electrodes is geometrically separated from its leading electrode laterally and/or transversally compared to one or more foregoing electrodes of the leading electrode, and
wherein an actuator is provided for separating the at least one trailing electrode from its leading electrode during welding by increasing a distance between the at least one trailing electrode and its leading electrode when a monitored stability parameter (Stab-par) of one of the electrodes of the electrode assembly is observed or expected to change by more than 5% with respect to the stability parameters (Stab_par) of one or more adjacent electrodes of the electrode assembly.

2. The electrode assembly according to claim 1 , wherein the trailing electrode is separated from its leading electrode by larger distance (d 1 ) than the leading electrode from its foregoing electrode.

3. The electrode assembly according to claim 2 , wherein a distance (d 0 ) is increased by a factor of at least 1.5.

4. The electrode assembly according to claim 1 , wherein separating the electrode is achieved by adjusting an angle (a) between the electrodes.

5. The electrode assembly according to claim 1 , wherein the trailing electrode is separated from its leading electrode by an offset transverse to the welding direction.

6. The electrode assembly according to claim 1 , wherein the separated electrode is selected based on an estimation of an instability during a welding process.

7. The electrode assembly according to claim 1 , wherein there are five electrodes and, wherein the fourth electrode is separated from the third electrode by a larger distance (d 1 ) than an equidistant spacing (d 0 ) between the other subsequent electrodes.

8. An electric arc welding method, wherein an electrode assembly comprises at least three fusible continuously-fed electrodes acting on a workpiece for generating a weld pool via electric arcs, wherein the at least three electrodes are arranged in sequential order relative to a welding direction and laterally separated relative to each other, comprising:
monitoring at least one stability parameter (Stab_par) for each electrode of the electrode assembly;
determining if the stability parameter (Stab_par) of one electrode of the electrode assembly violates a stability criterion (Crit), wherein violation of the stability criterion is detected when the stability parameter (Stab_par) of one or more of the electrodes changes by more than 5%, with respect to the stability parameters (Stab_par) of one or more adjacent electrodes;
separating at least temporarily the one electrode violating the stability criterion (Crit) from one or more adjacent electrodes when a violation of the stability criterion (Crit) of the one electrode is detected, by increasing a distance (d 0 ) between the one electrode violating the stability criterion (Crit) and its foregoing electrode.

9. The method according to claim 8 , comprising separating the one electrode by increasing the distance (d 0 ) in lateral direction.

10. The method according to claim 8 , wherein the distance (d 0 ) is increased by a factor of at least 1.5.

11. The method according to claim 8 , comprising separating the one electrode is performed by arranging one or more electrodes in a transverse direction with relation to the welding direction.

12. The method according to claim 8 , comprising separating the one electrode by adjusting an angle (a) between the electrodes.

13. The method according to claim 8 , comprising separating the one electrode by separating weld head jaws holding the electrodes.

14. The method according to claim 8 , wherein an electric current and/or through the electrodes is monitored as stability parameter (Stab_par).

15. The method according to claim 8 , wherein an arc voltage related to the electrodes is monitored as stability parameter (Stab_par).

16. The method according claim 8 , wherein violation of the stability criterion is detected when the stability parameter (Stab_par) of one or more of the electrodes changes by more than 5%, with respect to the stability parameters (Stab_par) of the trailing electrode compared to its foregoing electrode.

17. The method according to claim 8 , wherein the separation of the one electrode is performed during ongoing current flow through the electrodes.

18. An apparatus for performing an electric arc welding method, wherein an electrode assembly comprises at least three fusible continuously-fed electrodes acting on a workpiece for generating a weld pool via electric arcs, wherein the at least three electrodes are arranged in sequential order relative to a welding direction and laterally separated relative to each other, comprising:
a monitoring device for monitoring at least one stability parameter (Stab_par) for each electrode of the electrode assembly;
a unit for determining if the stability parameter (Stab_par) of one electrode of the electrode assembly violates a stability criterion (Crit) by determining whether the stability parameter (Stab_par) of one or more of the electrodes changes by more than 5%, with respect to the stability parameters (Stab_par) of one or more adjacent electrodes,
wherein the electrode assembly is adapted for separating at least temporarily the one electrode violating the stability criterion (Crit) from one or more adjacent electrodes when a violation of the stability criterion (Crit) of the one electrode is detected, by increasing a distance (d 0 ) between the one electrode violating the stability criterion (Crit) and its foregoing electrode.

19. The apparatus according to claim 18 , wherein the electrode assembly comprises adjustable weld head jaws for laterally and/or transversally adjusting the position of an individual electrode above a surface of the workpiece.

20. The apparatus according to claim 18 , wherein the electrode assembly comprises pivotable weld head jaws with adjustable angles (a).

Assignees

• Lennartsson Daniel
• Johansson Tomas
• Andrén Ulf
• Melin Bo
• Esab Ab

Inventors

• Lennartsson Daniel
• Johansson Tomas
• Andrén Ulf
• Melin Bo

Classifications

• B23K9/188 Primary

  making use of several electrodes · CPC title

• B23K9/095 Primary

  Monitoring or automatic control of welding parameters · CPC title

• B23K9/1735

  making use of several electrodes · CPC title

• B23K9/24

  Features related to electrodes · CPC title

• B23K9/18

  Submerged-arc welding · CPC title