A method and apparatus for feeding wire in a welding system include one or more motors disposed adjacent the wire to drive it. A wire feed motor is also disposed along the wire path, and is closer to the source of wire than the torch, and closer to the source than the one or more motors. The motors may be a pair motors disposed on opposite sides of the wire and move the wire to and away from an arc end of a torch. They preferably reversing the direction of the wire within one process cycle. The or more motors may be a stepper motor, a servo motor, a zero backlash motor, a gearless motor, a planetary drive motor, or a linear actuator (such as a piston), in various embodiments.

Method and apparatus for feeding wire to a welding arc

A method and apparatus for controlling a welding-type power supply includes providing a current wave form having an arc current portion and a short circuit current portion. An arc state is entered by retracting a welding wire, and a short circuit state is entered by advancing the wire. The current enters the arc current portion prior to the creation of the arc and the current enters the short circuit current portion prior to the creation of the short, by coordinating the wave form with the wire retraction. This may be preformed on a wire having a diameter of 2.4 mm or more to a weld and applying a welding current of less than 100 amps, or of less than 35 amps. One current waveform during the arc state includes at least three segments, and the last segment is entered into prior to the short circuit state being entered, and is the same current magnitude as the current magnitude at the start of the short circuit state. Penetration and/or bead formation may be controlled by controlling the advancement of the wire into the weld pool. The balance may be user set.

Method and apparatus for controlling a welding system

A method and apparatus for feeding wire from a source of wire to a weld includes one or more motors disposed adjacent the wire to drive the wire to the weld. A buffer is disposed between the source and an arc end of the torch. Another motor may be disposed near the wire source. A wire tension controller may be provided. The one or more motors advance and retract the wire, and wire is stored, or the path length altered, when the wire is retracted.

Method and apparatus for welding with mechanical arc control

A method and apparatus for providing welding-type power include a wire feeder that provides wire to an arc and a power supply that provides power to the arc. A reversible wire feed motor moves the wire to and away from the arc. A controller controls the reversible wire feeder motor to reverse at least once per process cycle, and/or controls the power source to provide a desired mean arc current, and/or controls the reversible motor in response to short detection and short clearing, and/or controls the reversal frequency in response to pool oscillation frequency. A wire feed motor output is slaved to an average of the reversible motor output. The controller may include various control modules, such as a mean arc current control module, and/or a short detection feedback circuit. The reversible motor is a stepper motor, that incrementally turns in a series of steps having a given angle in another embodiment. The controller includes a step size output and the given angle is varied in response to the step size output.

Method and apparatus for braking and advancing a welding wire

A process for buttwelding metal workpieces (12) having bevelled joint preparations using an automatic GTAW welder (20) using filler wire (32) includes preparing the bevelled workpieces (12) with bevelled joint areas having minimal land thickness at the root extremities; placing the prepared workpiece joint sections together with an open gap between their adjacent root extremities, the gap having a minimum dimension that avoids harmful compression stress between the workpieces due to weld shrinkage and a maximum dimension that avoids filler wire penetration of the gap; fusion welding the open root area of the adjacent workpieces (12) with a root pass weld using an automatic GTAW welder (20) supplied with filler wire (32) and a shield gas including 1 to 10 % hydrogen and the balance inert gas; and then promptly overlaying the root pass weld with at least one additional filler weld pass using an automatic GTAW welder (20) supplied with filler wire (32) and hydrogen-free shield gas.

Method of welding

A method for butt welding a pair of vertically disposed tubular members having a wall thickness of more than 12 mm in end-to-end relationship by multi-pass shielded arc welding with a consumable electrode, comprising the steps of preparing the opposed edges of the tubular members by forming a root face the width of which being in the range of 0.5 mm to 3.0 mm and beveling the edges adjacent to the root face to a bevel angle in the range of 40° to 50°, coaxially aligning said tubular members so that the gap between the root faces is not larger than 1.5 mm, performing a root pass by continuously feeding an electrode having a diameter not larger than about 1.0 mm into the groove between the prepared edges supplying a shielding gas consisting of 0-40% carbon dioxide and the balance argon, energizing an arc between the electrode and the root face alternately changing the voltage supplied to the arc between a low value and a high value, adjusting the low voltage to produce a droplet metal transfer during short circuit periods, adjusting the high voltage to produce a spray metal transfer, adjusting the welding speed and the electrode feeding speed to deposit metal in the groove in the range of 0.15 to 0.35 grams per mm length of the pass, and successively depositing overlapping passes for filling the groove.

Malm Anders Lennart

Papers

Method for tube welding