Series arc welder
First Claim
1. An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece, said welder comprising a leading electrode driven toward a point in said groove by a first wire feeder operated at a first speed by a first motor with a speed control input, a trailing electrode driven toward said point by a second wire feeder operated at a second speed by a second motor with a speed control input, and a power source for creating an arc between said leading and trailing electrodes to melt said leading and trailing electrodes, only one of said motors having a tachometer to generate a feedback WFS signal, said power source having a wire feed speed controlling device for creating a control WFS signal directed to said speed control input of said first motor to maintain said first motor at a set speed based upon said feedback WFS signal, said wire feed speed controlling device including a slave circuit that includes a converter and is connected to said control WFS signal to control said speed control input of said second motor, wherein said second motor is operated at a speed below or a speed above said set speed based upon said feedback WFS signal, said control WFS signal independent of a speed of said second motor, said second motor not providing any signal for use in controlling a WFS of said first motor.
1 Assignment
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Accused Products
Abstract
An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece. The welder comprises: a leading electrode driven toward a point in the groove by a first wire feeder operated at a first speed by a first motor with a speed control input and a tachometer derived first feedback signal, a trailing electrode driven toward the same point by a second wire feeder operated at a second speed by a second motor with a speed control input and a tachometer derived second feedback signal, a first power source directing a first current to flow through the leading electrode and a second power source causing a second current to flow through the trailing electrode with the current flow being in a series arc circuit. The second power source being grounded to the workpiece to modify the series arc current so ground current flows to the workpiece whereby the second current is generally equal to the first current minus the ground current.
17 Citations
52 Claims
- 1. An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece, said welder comprising a leading electrode driven toward a point in said groove by a first wire feeder operated at a first speed by a first motor with a speed control input, a trailing electrode driven toward said point by a second wire feeder operated at a second speed by a second motor with a speed control input, and a power source for creating an arc between said leading and trailing electrodes to melt said leading and trailing electrodes, only one of said motors having a tachometer to generate a feedback WFS signal, said power source having a wire feed speed controlling device for creating a control WFS signal directed to said speed control input of said first motor to maintain said first motor at a set speed based upon said feedback WFS signal, said wire feed speed controlling device including a slave circuit that includes a converter and is connected to said control WFS signal to control said speed control input of said second motor, wherein said second motor is operated at a speed below or a speed above said set speed based upon said feedback WFS signal, said control WFS signal independent of a speed of said second motor, said second motor not providing any signal for use in controlling a WFS of said first motor.
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18. An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece, said welder comprising first and second power sources, a leading electrode driven toward a point in said groove by a first wire feeder operated at a first speed by a first motor with a speed control input and a tachometer derived first feedback signal,
a trailing electrode driven toward said point by a second wire feeder operated at a second speed by a second motor with a speed control input and a tachometer derived second feedback signal, said first power source directing a first current to flow through said leading electrode and said second power source causing a second current to flow through said trailing electrode with said current flow being in a series arc circuit, said second power source is grounded to said workpiece to modify said series arc current so ground current flows to said workpiece whereby said second current is generally equal to said first current minus said ground current, said tachometer derived first feedback only controlling said first motor and not providing any control signal to said second motor, said tachometer derived second feedback only controlling said second motor and not providing any control signal to said first motor, and a voltage sensing circuit and a controller associated with each power source that detects a given voltage associated with each one of said electrodes and accordingly adjusts each said corresponding speed control input.
Specification