Welding head and welding head assembly for an arc-welding system

1. An electric arc-welding welding head comprising:

at least one fusible, continuously-fed hot wire electrode configured to be consumed in an arc during a welding operation;

a fusible, continuously-fed cold wire electrode that is configured to be consumed without an arc by being in continuous short-circuit contact with a weld pool during the welding operation; and

a contact device including a conductive body through which electrical power is delivered to the at least one hot wire electrode, the contact device being entirely included in or on the electric arc-welding head and including an electrically insulated duct that extends through the conductive body and at least one additional duct that is defined by the conductive body, wherein the at least one hot wire electrode extends through the at least one additional duct while the at least one additional duct delivers electrical power to the at least one hot wire electrode, and the cold wire electrode extends through the electrically insulated duct so that the cold wire electrode is electrically insulated from the at least one hot wire electrode.

2. The welding head of claim 1 , wherein the cold wire electrode is melted by one or more of:

a weld pool generated by melting the at least one hot wire electrode; and

heat generated when melting the at least one hot wire electrode.

3. The welding head of claim 2 , wherein the weld pool melts the cold wire electrode via resistance heating.

4. The welding head of claim 1 , further comprising:

a motor driven wire straightening unit for straightening the at least one hot wire electrode, the motor driven wire straightening unit including an electrically insulating portion for the cold wire electrode that electrically insulates the cold wire electrode from the at least one hot wire electrode while the motor driven wire straightening unit straightens the at least one hot wire electrode.

5. The welding head of claim 4 , wherein the motor driven wire straightening unit is a first motor driven wire straightening unit and the welding head further comprises:

a second motor driven wire straightening unit for straightening the cold wire electrode.

6. The welding head of claim 1 , further comprising:

a motor driven wire feeder unit for feeding the at least one hot wire electrode towards the contact device, the motor driven wire feeder unit including an electrically insulating portion for the cold wire electrode that electrically insulates the cold wire electrode from the at least one hot wire electrode while the motor driven wire feeder unit feeds the at least one hot wire electrode towards the contact device.

7. The welding head of claim 6 , wherein the motor driven wire feeder unit is a first motor driven wire feeder unit and the welding head further comprises:

a second motor driven wire feeder unit for feeding the cold wire electrode towards the contact device.

8. The welding head of claim 7 , wherein the first motor driven wire feeder unit has a first speed control unit, the second motor driven wire feeder unit has a second speed control unit, and the first speed control unit and the second control unit separately control feed speeds of the at least one hot wire electrode and the cold wire electrode, respectively.

9. The welding head of claim 7 , wherein the insulated portion of the first motor driven wire feeder unit receives the cold wire electrode from the second motor driven wire feeder unit via at least an electrically insulated wire conduit extending substantially between the second motor driven wire feeder unit and the first motor driven wire feeder unit.

10. The welding head of claim 9 , wherein the insulated portion of the first motor driven wire feeder unit receives the cold wire electrode directly from a motor driven wire straightening unit and the electrically insulated wire conduit extends between the second motor driven wire feeder unit and the motor driven wire straightening unit.

11. The welding head of claim 1 , wherein the contact device includes a tip and the electrically insulated duct extends longitudinally through the contact device to provide an outlet for the cold wire electrode at an opening provided by the tip of the contact device.

12. The welding head of claim 11 , wherein the outlet is disposed in a central position of within the opening of the tip.

13. The welding head of claim 11 , wherein the outlet is disposed in an eccentric position within the opening of the tip.

14. The welding head of claim 1 , wherein the electrically insulated duct comprises an electrically insulating tube.

15. The welding head of claim 1 , wherein the at least one hot wire electrode is arranged in alignment with and ahead of the cold wire electrode with respect to a welding direction.

16. The welding head of claim 1 , wherein the at least one hot wire electrode is arranged in alignment with and behind the cold wire electrode with respect to a welding direction.

17. The welding head of claim 1 , wherein the at least one hot wire electrode includes two or more hot wire electrodes arranged ahead of and behind the cold wire electrode with respect to a welding direction.

18. A welding head comprising:

a fusible, continuously-fed cold wire electrode that is configured to be consumed without an arc by being in continuous short-circuit contact with a weld pool during a welding operation;

at least one fusible, continuously-fed hot wire electrode configured to be consumed in an arc during the welding operation;

a contact device including a conductive body through which electrical power is delivered to the at least one hot wire electrode, the contact device being entirely included in or on the welding head and including an electrically insulated duct that extends through the conductive body and at least one additional duct that is defined by the conductive body, wherein the at least one hot wire electrode extends through the at least one additional duct while the at least one additional duct delivers electrical power to the at least one hot wire electrode, and the cold wire electrode extends through the electrically insulated duct so that the cold wire electrode is electrically insulated from the at least one hot wire electrode;

a first motor driven wire feeder unit for feeding the at least one hot wire electrode towards the contact device; and

a second motor driven wire feeder unit for feeding the cold wire electrode towards the contact device.

19. The welding head of claim 18 , further comprising:

a first motor driven wire straightening unit for straightening the at least one hot wire electrode; and

a second motor driven wire straightening unit for straightening the cold wire electrode.

20. The welding head of claim 19 , wherein:

the second motor driven wire feeder unit receives the cold wire electrode from the second motor driven wire straightening unit and feeds the cold wire electrode towards the first motor driven wire straightening unit;

the first motor driven wire straightening unit includes a first electrically insulating portion for the cold wire electrode that electrically insulates the cold wire electrode from the at least one hot wire electrode while the first motor driven wire straightening unit straightens the at least one hot wire electrode, the first electrically insulating portion allowing the cold wire electrode to pass to the first motor driven wire feeder unit; and

the first motor driven wire feeder unit includes an electrically insulating portion for the cold wire electrode that electrically insulates the cold wire electrode from the at least one hot wire electrode while the first motor driven wire feeder unit feeds the at least one hot wire electrode towards the contact device.