A pulsed arc welding system includes a current pulse generating circuit and a background current generating circuit. The lowest arc voltage across the arc load is detected during a predetermined time period immediately preceeding the onset of each current pulse. The pulse repetition rate is controlled on the basis of this detected voltage so that the detected arc voltage becomes constant.

Pulsed arc welding

A method of determining the impedance, inductance, and resistance of the network connecting an electrical power supply to an electric arc welding station including an electrode and a workpiece, wherein the method comprises: shorting the electrode to the workpiece; creating at least one waveform including a first state operating the power supply at constant current of a selected value and a second state operating the power supply at a low value of current or open circuit voltage whereby the current decays from the selected value along a decay path indicative of di/dt; obtaining the average current Iavg and average resistance Ravg during the first state; selecting a portion of the decay path; sampling the instantaneous current for a number of times on the path during the second state to read the rate of the decay; and, using the average current and the average resistance with the rate of decay to obtain the inductance of the network.

Method of determining cable impedance

The invention provides a gas-shielded arc welding system using two side-by-side electrodes each of which is provided with current pulses superimposed on a respective background current level to maintain the desired controlled spray transfer mode of the weld metal without overheating effects. The pulses are supplied to the two arcs out of phase with one another to minimize interaction of their magnetic fields, but this alone is not sufficient to assure stability of the two arcs. In the system of the invention, one arc is designated as the master arc and the other as the slave arc. The master arc is stabilized by means of a feedback loop controlling its master pulse frequency. Each master pulse triggers a respective slave pulse after a preset time delay, in this way keeping corresponding master and slave pulses in synchronism. This is not necessarily sufficient to stabilize the slave arc and independent stabilization is therefore provided for it by a feedback loop controlling its pulse duration or its background current, but preferably by controlling both simultaneously.

Twin pulsed arc welding system

An arc welder control in which the current is pulsed between a high level and a low level. The high level pulse is maintained until a selected energy condition is satisfied. The low level pulse is maintained to satisfy an average energy condition. A proximity control moves the torch head and the feed wire tip toward and away from the work to stabilize a parameter of welder operation which may deviate with the current pulse energy control.

Control for gas metal arc welding system

A method of sensing and controlling an arc welding process employs a high equency rate of sampling of electrical signals from the welding circuit The sampled signals are operated upon by predetermined processes to determine electrical resistance, shielding gas quality, and short circuit frequency The process measurements are compared to a predetermined set of tolerance levels and evaluated using a window technique that updates the evaluation of the data samples at the sampling rate

Sensing ARC welding process characteristics for welding process control

A method of pulsed arc welding and an apparatus for carrying out the method, employ welding current pulses having an amplitude greater than the value of a background current. The arc voltage is sensed to provide a signal for controlling the frequency of the welding current pulses to counteract variations in electrode wire feed speed or spacing of the electrode from the workpiece.

Pulsed arc welding apparatus

A B S T R A C T A method of pulsed arc welding and an apparatus for carrying out the method, employ welding current pulses having an amplitude greater than the value of a background current. The arc voltage is sensed to provide a signal for controlling the frequency of the welding current pulses to counteract variations in electrode wire feed speed or spacing of the electrode from the workpiece.

Brian A. Graville

Papers

Pulsed arc welding apparatus

Welding method and apparatus