Pipe seam tack welding methods and apparatus using modified series arc welding
First Claim
1. A modified series arc welder for depositing weld metal along a groove proximate two edges of a metal workpiece using a plurality of welding cycles having a short-circuit condition and an arc condition, said welder comprising:
- first and second wire feeders respectively adapted to direct first and second electrodes toward a point proximate said workpiece;
a first power source having a first output terminal coupled with said first electrode to provide a first current thereto according to a selected first waveform in a welding cycle; and
a second power source having a first output terminal coupled with said second electrode to provide a second current thereto according to a selected second waveform in said welding cycle;
said power sources and said electrodes being coupled in a series circuit to provide electrical power to said electrodes as a plurality of said welding cycles for depositing molten metal in the form of a pool along said groove during a welding operation, each of said welding cycles including an arc condition during which said first electrode is spaced from said pool and energy applied to said first electrode causes a first molten metal to form on an end of said first electrode and a short-circuit condition during which said first molten metal on said end of said first electrode contacts said pool and then transfers from said first electrode to said pool by a necking action;
wherein said first power source provides said first current having a first polarity during said arc condition and at least a portion of said short-circuit condition, and provides said first current having a second opposite polarity during a reverse boost portion of said welding cycle according to said first waveform to transfer molten metal from said second electrode to said first electrode prior to a short-circuit condition of a subsequent welding cycle.
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Accused Products
Abstract
Welders and methods are presented for short-circuit arc welding a workpiece using a modified series arc welding configuration with two electrodes via a sequence of welding cycles, in which each cycle includes an arc condition a short-circuit condition, wherein one or both electrode currents are selectively reversed during a reverse boost portion of the welding cycle to transfer molten metal from the second electrode to the first electrode prior to a short-circuit condition of a subsequent welding cycle.
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Citations
101 Claims
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1. A modified series arc welder for depositing weld metal along a groove proximate two edges of a metal workpiece using a plurality of welding cycles having a short-circuit condition and an arc condition, said welder comprising:
- first and second wire feeders respectively adapted to direct first and second electrodes toward a point proximate said workpiece;
a first power source having a first output terminal coupled with said first electrode to provide a first current thereto according to a selected first waveform in a welding cycle; and
a second power source having a first output terminal coupled with said second electrode to provide a second current thereto according to a selected second waveform in said welding cycle;
said power sources and said electrodes being coupled in a series circuit to provide electrical power to said electrodes as a plurality of said welding cycles for depositing molten metal in the form of a pool along said groove during a welding operation, each of said welding cycles including an arc condition during which said first electrode is spaced from said pool and energy applied to said first electrode causes a first molten metal to form on an end of said first electrode and a short-circuit condition during which said first molten metal on said end of said first electrode contacts said pool and then transfers from said first electrode to said pool by a necking action;
wherein said first power source provides said first current having a first polarity during said arc condition and at least a portion of said short-circuit condition, and provides said first current having a second opposite polarity during a reverse boost portion of said welding cycle according to said first waveform to transfer molten metal from said second electrode to said first electrode prior to a short-circuit condition of a subsequent welding cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- first and second wire feeders respectively adapted to direct first and second electrodes toward a point proximate said workpiece;
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22. A method of short-circuit arc welding a workpiece, the method comprising:
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(a) directing first and second electrodes toward a point proximate a workpiece;
(b) providing first and second currents to said first and second electrodes according to selected first and second waveforms, respectively, to deposit molten metal from at least one of said electrodes onto said workpiece in a sequence of welding cycles, each of said welding cycles including an arc condition during which said first electrode is spaced from said workpiece and energy applied to said first electrode causes a first molten metal to form on an end of said first electrode and a short-circuit condition during which said first molten metal on said end of said first electrode contacts said workpiece and then transfers from said first electrode to said workpiece; and
(c) selectively reversing an electrical polarity of said first current during said welding cycle such that said first current has a first polarity during said arc condition and at least a portion of said short-circuit condition, and a second opposite polarity during a reverse boost portion of said welding cycle according to said first waveform to transfer molten metal from said second electrode to said first electrode prior to a short-circuit condition of a subsequent welding cycle. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for welding a pipe seam, the method comprising:
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engaging two pipe seam edges to one another to form a cylindrical pipe structure having an inside and an outside, said cylindrical pipe structure having a seam at the two engaged seam edges with an outer groove and an inner groove;
welding a portion of the outer groove using a series welding process to tack the two seam edges together, said series welding process comprising a plurality of welding cycles individually having a short-circuit condition and an arc condition;
welding the inner groove after the two seam edges have been tacked together to essentially fill the inner groove and form an inner seam; and
welding the outer groove after welding the inner groove to essentially fill the outer groove and form an outer seam. - View Dependent Claims (29, 30, 31, 32)
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33. A modified series arc welder for depositing weld metal along a groove proximate a pipe seam using a plurality of welding cycles individually having a short-circuit condition and an arc condition, said welder comprising:
- first and second wire feeders respectively adapted to direct first and second electrodes toward a point proximate said workpiece;
a first power source providing a first current to said first electrode;
a second power source providing a second current to said second electrode, said power sources and said electrodes being connected in a series circuit;
a short-circuit detection circuit coupled with at least one of said power sources, said short-circuit detection circuit detecting a beginning of said short-circuit condition in which molten metal from one of said electrodes connects with a weld pool along said groove and providing a short-circuit signal to at least one of said power sources in response to said beginning of said short-circuit condition; and
a premonition circuit coupled with said at least one of said power sources, said premonition circuit detecting an imminent fuse condition in which said molten metal separates from said one of said electrodes, and said premonition circuit providing a premonition signal to said at least one of said power sources in response to said imminent fuse condition. - View Dependent Claims (34, 35, 36, 37)
- first and second wire feeders respectively adapted to direct first and second electrodes toward a point proximate said workpiece;
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38. An arc welding system, comprising:
- a wire feeding system adapted to direct first and second electrodes toward a workpiece, said first and second electrodes being connected in a series circuit; and
a source of electrical power providing a first current to said first electrode and a second current to said second electrode to deposit material from said first and second electrodes in a short-circuit arc welding process having an arc condition and a short-circuit condition in each of a plurality of welding cycles. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
- a wire feeding system adapted to direct first and second electrodes toward a workpiece, said first and second electrodes being connected in a series circuit; and
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70. An arc welding system, comprising:
- a wire feeding system adapted to direct first and second electrodes toward a workpiece; and
a source of electrical power energizing said electrodes to deposit material from said electrodes in a short-circuit arc welding process having an arc condition and a short-circuit condition in each of a plurality of welding cycles, said source of electrical power providing a first current to said first electrode and a second current to said second electrode to establish a first arc between said first electrode and said workpiece and a second arc between said first and second electrodes. - View Dependent Claims (71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85)
- a wire feeding system adapted to direct first and second electrodes toward a workpiece; and
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86. A method for welding a workpiece, said method comprising:
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(a) directing first and second electrodes toward a point; and
(b) providing first and second currents to said first and second electrodes, respectively, to establish a first arc between said first electrode and a workpiece and a second arc between said first and second electrodes in order to transfer material from said electrodes to said workpiece in a plurality of welding cycles, each welding cycle including an arc condition and a short-circuit condition. - View Dependent Claims (87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101)
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Specification