Method and system for gas metal arc welding

A computer implemented method of adaptive arc welding using a pulse of current having a variable waveform supplied to a consumable electrode wire being fed towards a workpiece, comprising the steps of:

• inputting a first arc voltage;
• supplying a first level of current for a constant period sufficient to grow a droplet to a desired size at an end of the consumable electrode wire;
• reading a second actual arc voltage;
• lowering the current to a second level for a duration sufficient to cause the droplet to oscillate;
• raising the current to a third level having a constant period sufficient to detach the droplet from the consumable electrode wire;
• determining an average current required to maintain the first arc voltage;
• and
• adjusting the current to a fourth level for a duration sufficient to maintain the average current and a constant period for the pulse of current,
• whereby a single droplet is detached per constant pulse period to provide a constant droplet transfer frequency.

A system for welding a workpiece using a pulse of current having a constant period and a adaptively controlled variable waveform, comprising:

• a consumable electrode wire;
• a wire feed controller for feeding said consumable electrode wire toward the workpiece;
• a power supply for providing a current sufficient to both maintain an arc between said consumable electrode wire and the workpiece and form a droplet at the end of said electrode;
• a controller having a memory for receiving and storing a set of instructions, including a first voltage for said arc, an initial wire feed speed, and a current sufficient to grow said droplet to a desired size;
• said controller including means for (a) reading a second arc voltage upon growing said droplet to said desired size, (b) lowering said current for a duration sufficient to induce an oscillation in said droplet, (c) raising said current sufficient to detach said droplet, (d) calculating an average current required to maintain said first arc voltage substantially constant, and (e) adjusting said current level and duration sufficient to maintain said average current and a constant period for the pulse of current,
• whereby a single droplet is detached per constant pulse period to provide a constant droplet transfer frequency.

A system for arc welding a workpiece using a pulse of current having an adaptively controlled variable waveform, comprising:

• a consumable electrode wire;
• a wire feed controller for feeding said electrode wire towards the workpiece;
• a power supply for supplying a current sufficient to maintain an arc between said electrode wire and the workpiece, the heat of said arc forming a droplet at the end of said wire electrode;
• a central controller for setting a first arc voltage, an initial wire feed speed and a set of parameters for the pulse of current to maintain said first arc voltage;
• a waveform controller for implementing a first constant pulse period of peak current based on the initial parameters sufficient to grow said droplet to a desired size and a second variable pulse period of base current sufficient to cause said droplet to oscillate;
• a feedback controller for reading a second arc voltage and comparing the second arc voltage with the first arc voltage, said feedback controller further determining an average current required to maintain said first arc voltage and providing the average current to said waveform controller;
• a detachment controller for monitoring the arc voltage to determine the oscillation of said droplet and signaling said waveform controller to implement a third constant period of current sufficient to detach said droplet;
• said waveform controller providing a fourth variable pulse period of variable current to maintain both the average current and a constant pulse period,
• whereby a single droplet is detached per constant pulse period to provide a constant droplet transfer frequency.