US 4,301,355 A · Gas metal arc welding system

Abstract

Power delivered to the welding arc from a constant current rapid response power supply is controllable to maximize arc stability particularly in out-of-position welding operations. A first control modulates the output current from the power supply between a high value close to the maximum output value and a minimum value just sufficient to maintain the welding arc. The modulation is effected at a given frequency appropriately adjusted in accordance with the electrode material and diameter to maintain optimum spray metal transfer in the welding arc. A further control is effected by pulse width modulating the output from the power supply in accord with a set-in current programmed signal which is compared with a current feedback signal or, alternatively, a set in voltage programmed signal which is compared with a voltage feedback signal. This latter control provides for operation of the power supply in a constant current control mode or alternatively, a constant voltage control mode. Still further control of the power in the welding arc is effected by pulsing the current between base and peak levels at a relatively low frequency which enables control of the weld puddle in out-of-weld positions.

Claims18

Dependent claims

A method for maximizing weld arc stability, puddle control and deposition rate on a work especially in but not limited to out-of-position welding for a given power level and given feed wire electrode material of given diameter, including the steps of:

(a) passing power from a constant current rapid response power supply to the feed wire electrode;
(b) providing a current feedback signal corresponding to the value of the current at the welding arc;
(c) providing a voltage feedback signal corresponding to the value of the voltage at the welding arc;
(d) providing a current reference control signal at a given frequency and given amplitude to modulate the power to provide a current varying between a relatively high output current of the power supply and relatively low output current;
(e) providing a pulse width modulator control signal corresponding to the amplified difference between said current feedback signal and a current programmed signal;
(f) controlling the pulse width of said current reference control signal with said pulse width modulator control signal to provide a constant current control mode of the power supply;
and
(g) controlling the rate of feed of said feed wire material in accordance with a signal corresponding to the amplitude difference between said voltage feedback signal and a voltage programmed signal.

5 more elements

A gas metal arc welding control system for maximizing weld arc stability between the arc head and work, puddle control in the work and deposition rate especially in out-of-position welding for a given power level and a given feed wire electrode material of given diameter, including in combination:

(a) a constant current rapid response power supply for passing power to the weld head to provide a welding arc;
(b) an arc current responsive means to provide a current feedback signal;
(c) an arc voltage responsive means to provide a voltage feedback signal;
(d) a pulse width pulse amplitude modulator for generating a current reference control signal for said constant current rapid response power supply to modulate the current between a high output current and a low output current from said power supply at a given frequency;
(e) means for providing a current programmed signal;
(f) means for providing a voltage programmed signal;
(g) means for generating a pulse width modulator control signal for pulse width modulating said current reference control signal as a function of the amplified difference between said current programmed signal and said current feedback signal to thereby provide a constant current control mode of said power supply;
and
(h) demand means for controlling the rate of feeding of said feed wire electrode material in accordance with a signal corresponding to the amplified difference between said voltage feedback signal and said voltage programmed signal.

6 more elements

Dependencies are inferred from the claim text.

Gas metal arc welding system

Life of this patent

Gas metal arc welding system

Life of this patent

Abstract

Claims18