Abstract: A method and apparatus for preventing catastrophic melting of the contact be in continuously-fed consumable electrode arc welding due to wire feed interruptions by monitoring the movement of the wire electrode with a high frequency sensor such as all optical encoder having a resolution on the order of <0.1 second and switching off the power to the welding apparatus if the wire electrode speed falls below a predetermined threshold.

Abstract: Method and apparatus for splicing together the ends of metal webs by TIG welding. In the method and apparatus, since the tapered end portion of an electrode disposed at the leading end of a welding torch for use in TIG welding is formed in a semi-spherical shape or in a circular flat surface, arc can remain stable even if the length of the arc in the TIG welding is changed suddenly at the welding starting or terminating end portion of the weldedly spliced portion of the metal webs.

Abstract: A variable polarity device reverses the polarity of an electrically conductive workpiece and an electrode, having opposite polarities, between positive and negative in a low D.C. range of about 0.5-45 amps. Combined with the device is a control means which schedules a frequency of time rate of the reversing in the low time frequency of about 1-1000 cycles per second as well as the electric current at each polarity to provide a series of time and current defined polarity cycles for D.C. arc welding apparatus.

Abstract: A capacitor discharge process for welding a braided cable formed from a plurality of individual cable strands to a solid metallic electrically conductive member comprises the steps of: (a) preparing the electrically conductive member for welding by bevelling one of its end portions while leaving an ignition projection extending outwardly from the apex of the bevel; (b) clamping the electrically conductive member in a cathode fixture; (c) connecting the electrically conductive member clamped in the cathode fixture to a capacitor bank capable of being charged to a preselected voltage value; (d) preparing the braided cable for welding by wrapping one of its end portions with a metallic sheet to form a retaining ring operable to maintain the individual strands of the braided cable in fixed position within the retaining ring; (e) clamping the braided cable and the retaining ring as a unit in an anode fixture so that the wrapped end portion of the braided cable faces the ignition projection of the electrically cond

Abstract: An inverter power supply for use with various voltage inputs is provided. The inverter power supply generally receives 208 VAC single-phase, 208 VAC three-phase, 230 VAC three-phase, 230 VAC single-phase, 460 VAC single-phase, or 460 VAC three-phase power and provides a DC output current for welding, heating or cutting applications. The power inverter circuit includes a first tank circuit and a second tank circuit which are configured in serial or parallel according to a particular voltage input. Contactors, relays, or semiconductor switches respond to control signals from an AC sense circuit in order to configure the inverter power supply for the appropriate voltage input.

Abstract: Increasing the rate of deposition of the molten metal droplets formed on the end of a wire electrode used in a gas-metal-arc welding process by advancing the electrode towards the weld deposit pool during the formation of a molten metal droplet on the end of the electrode, and applying a normal level of current to the electrode. The electrical level is momentarily substantially increased at a time when the individual droplet is almost ready to melt off the end of the electrode for free-flight transfer to the weld deposit pool. The momentarily applied increased current melts off the electrode drop prematurely so that the drop is propelled to the pool. Therefore, although smaller drops are produced than in the normal shielded gas, plasma-type, are welding process, the rate of drop formation and the more rapid separation of the drops and positive propulsion of the drops to the pool, results in substantially increased molten metal deposition in the weld pool.

Abstract: A welding power supply having a multiphase alternator and a thyristor rectifier using a control circuit to selectively prevent firing of thyristors when a short circuit occurs. Reliable operation of an alternator welding power supply under short circuit conditions is achieved.

Abstract: A method of TIG welding with alternating current with a welding apparatus (10) which is arranged in such a manner that the polarity of the welding current is controlled by an electronic control circuit (20), which is also arranged so that it continuously registers whether or not the arc is lit, and in that the welding apparatus comprises a controllable inverter (16) and means for re-igniting the arc in the positive period, and arranged so that the length of the positive period is shortened if the arc is not re-ignited in the positive period. The invention also relates to a welding apparatus which can be equipped with a logical circuit or a programmable circuit which instantly ensures that the positive welding period is shortened if the arc is not re-ignited in this period.

Abstract: A method of welding comprises forming an alternating current electric arc between an electrode (32) of a tungsten inert gas welding torch (30) and a metallic substrate (10). The alternating current has a square wave form which is self supporting and does not require intercycle high frequency support. The square wave alternating current has a wave bias ratio equal to or greater than 90% forward current to 10% reverse current. A metal welding rod (38) is supplied into the electric arc for depositing a weld deposit (40) on the metallic substrate (10). The welding method is used to apply a metallic wear resistant coating (40) to an edge surface (20 or 22) on a shroud (18) of a turbine blade (10) and is used to seal a cooling passage of a turbine blade or turbine vane.

Abstract: A high frequency power supply for supplying a welding current through a choke to a welding station including an electrode element and a workpiece element. The power supply includes a first transformer with a first core and means for receiving on said first core a first secondary winding with the first core being magnetized in a first flux direction upon creation of first current pulse and a second transformer with a second core and means for receiving on said second core a second secondary winding with said second core being magnetized in a second flux direction upon creation of a second current pulse in the direction opposite to the first pulse. The first transformer is operated by a first capacitor means for applying a first voltage to the first transformer upon operation of a first switch means and the second transformer is operated by a second capacitor means for applying second voltage to the second transformer upon operation of a second switch means.

Abstract: A consumable electrode gas shielded AC arc welding method and an apparatus to practice the method applies alternating current across a consumable electrode and a base metal. During a first period, the electrode is positive and a current of a first level higher than a specified critical level is furnished. During a second period, the electrode is kept positive and current is reduced to a second level lower than the first level. During a third period, the electrode is kept negative at a third current level. These periods are periodically repeated. If during the frist period, the arc voltage drops below a predetermined voltage, current of a fourth level higher than the first level is furnished until the arc voltage exceeds the predetermined level.

Abstract: An inverter power supply for use with various voltage inputs is provided. The inverter power supply generally receives 208 VAC single-phase, 230 VAC three-phase, 230 VAC single-phase, 460 VAC single-phase, 208 VAC three-phrase or 460 VAC three-phase power and provides a DC output current for welding, heating or cutting applications. The power inverter circuit includes a first tank circuit and a second tank circuit which are configured in serial or parallel according to a particular voltage input. Contactors, relays, or semiconductor switches respond to control signals from an AC sense circuit in order to configure the inverter power supply for the appropriate voltage input.

Abstract: Both a system and a method for converting two AGTAW welders into a AGMAW welder is provided. The system generally comprises a MIG weldhead for replacing the TIG weldhead of one of the AGTAW welders, a pulser multiplier circuit for increasing the frequency of the power supply output current from 10 to between 300 and 800 pulses per second, and a wire feed motor and motor control circuit capable of feeding weld wire at a rate compatible with a AGMAW welding operation. In the method of the invention, the control circuit assembly of one of the AGTAW welders is connected in parallel to the power supplies of both of the two AGTAW welders, and the outputs of these power supplies are likewise connected in parallel. The TIG weldhead of one of the AGTAW welders is replaced with the MIG weldhead, and the pulser multiplier circuit is selectively connected to the current pulser of the single control circuit assembly which controls both power supplies.

Abstract: A method and apparatus for reducing energy consumption and minimizing martensite formations when joining a connecting piece of metal with a metal surface by pin brazing.

Abstract: A TIG weld produced from a rapidly solidified dispersion strengthened aluminum base alloy exhibits attributes of the alloy's microstructure extant prior to formation of the weld. TIG welding power is adjusted to minimize energy input into the weld. An arc gas contacts the weld to maximize rapid quenching thereof, while a second gas contacts the undersurface of the weld so that the undersurface of the weld is quenched. Cooling of the weld is further enhanced by a trailing gas selected from the group consisting of argon, nitrogen, helium, carbon dioxide and mixtures thereof. The weld is shot peened to homogenize the weldment and heat effected zone, and induce residual compressive stresses and cold working therein.

Abstract: A TIG weld produced from a rapidly solidified dispersion strengthened aluminum base alloy exhibits attributes of the alloy's microstructure extant prior to formation of the weld. TIG welding power is adjusted to minimize energy input into the weld. An arc gas contacts the weld to maximize rapid quenching thereof, while a second gas contacts the undersurface of the weld so that the undersurface of the weld is quenched. Cooling of the weld is further enhanced by a trailing gas selected from the group consisting of argon, nitrogen, helium, carbon dioxide and mixtures thereof.

Abstract: An arc welding machine includes a transformer a diode for rectification connected to the secondary winding of the transformer, two capacitors connected in series with each other and in parallel with the diode, and the first and second switching elements connected in series with each other and in parallel with the diode. This machine also includes an electrode having one end connected at a location intermediately of the two switching elements and the other end opposed to an object to be welded, first and second drive circuits connected to the first and second switching elements, respectively, an oscillating circuit for determining the width of pulses of the first and second drive circuits, and a timer circuit for inputting to the oscillating circuit signals required to make the oscillating circuit periodically repeat oscillating and stop operations. The object is connected at a location intermediately of the two capacitors. The second drive circuit outputs inverted signals of the first drive circuit.

Abstract: A method of modifying surfaces of metal parts comprises melting an area of metal surface by high-density energy irradiation, sensing the temperature (t) of the melted area, and of carrying out the build-up welding by using a wire (8) containing a heat-resistant alloying element (25).

Abstract: A battery-powered welder delivers limited DC current to a workpiece without substantial reduction in applied voltage. The DC current is limited by utilizing a tungsten member in series between the battery and an arcing electrode. There is specifically disclosed a TIG welder embodiment.

Abstract: In a consumable electrode gas shielded arc welding system, alternating current power is applied across the electrode and the base metal. The period during which the electrode is kept negative is varied to correspond to the electrode feeding rate. In addition, the levels of the output power during the negative and positive periods are individually set.

Abstract: A method and apparatus for submerged arc welding with four electrodes positioned along a line from front to rear. The first of the electrodes is supplied with direct current, and the remaining three electrodes are supplied with alternating current. The direct current electrode generate an arc that penetrates the base metal and initiates a weld. The other electrodes are supplied with alternating current having a 90.degree..+-.15.degree. current separation between the leading and trailing AC electrodes, and the trailing and middle AC electrodes. Alternating current is supplied between electrodes the trailing and middle AC electrode, having a 180.degree..+-.30.degree. current separation. The AC electrodes combine to generate an arc that deposits a filler and shapes the weld.

Abstract: An AC arc welding circuit for controlling current supplied to a welding electrode for welding thin metal pieces. A coupling circuit connects a capacitance circuit between a terminal of the secondary winding of a power supply transformer and the welding electrode. The other terminal of the secondary transformer is connected to the common electrode of the secondary winding which is, in turn, connected to a thin metal piece to be welded. The control circuit is provided with a sensing coil to sense the current flowing in the thin metal piece and to initiate a trigger pulse to switch a TRIAC to short-circuit the capacitance circuit during a predetermined short time as determined by the timing circuit so as to provide for a high voltage high current supply to the welding electrode during arc initiating when the electrode is spaced from the metal piece.

Abstract: The present invention provides a GMAW control system for balancing wire burnoff rate with wire feed speed at a weld site. A power source applies a pulsed current to the consumable wire. The width of the peak pulse current is calculated and adapted to maintain a constant optimum arc length as selected by the operator. The controller provides a reference voltage to the power source and the power source provides the pulsed current having a magnitude responsive to the reference voltage signal.

Abstract: A microprocessor-controlled arc welding power supply is disclosed. An silicon controlled rectifier ("SCR") bank is used to generate a direct current arc welding current under program control. Positive sychronization is provided by the microprocessor using a phase locked loop and a polarity detector, so that the gating signals applied to the SCRs are correctly timed. Optimum tradeoffs between hardware and software are accomplished by using look up tables to store correction factors that can be quickly accessed during execution, and by using timers as smart interface chips to fire the SCRs at the same angle during each cycle until changed or updated by the microprocessor. The arc welding power supply is capable of operating in a constant current or constant voltage mode without rewiring the circuit.

Abstract: There is provided an improvement in a short circuiting arc welding system comprising a work station with a consumable electrode and workpiece, a D.C. power supply with a positive and a negative terminal, high frequency current control means for applying a welding circuit with a given time-based profile across the work station while the electrode is short circuited and while the electrode is spaced from the workpiece, a welding current circuit means including a first means for creating a first inductive reactance in series with the current control means and work station whereby the welding current follows the time-based profile in accordance with the first inductive reactance. The improvement comprises a background current circuit means between the power supply and the work station and in parallel with the current control means and first means for applying continuously a background current across the work station.

Abstract: A method and apparatus for submerged arc welding using five-electrodes having direct current (DC) connected to one electrode and alternating current (AC) connected to the other four electrodes. The electrodes are aligned in a row with predetermined angles to the direction of the weld. Alternating current is supplied to the electrodes so that a 90.degree. phase difference is applied to adjacent electrodes and a 180.degree. phase difference is applied between alternating electrodes. With such power application and the electrical connections of the electrodes, the welding process has a more stable weld puddle that suppresses welding defects at higher speeds than previously achievable.

Abstract: This invention relates to a method for noise reduction and stabilization of the welding arc in TIG-ac-welding machines with self-commutated inverter current sources where the alternating frequency of the welding current is preferably changed in the inverse direction as a function of the amount of the welding current.

Abstract: A welding station for welding thin-walled copper-nickel pipe. An electronic welding station (10) has an output circuit (13) which provides arc welding power having the arc characteristics specified by a weld parameter selection circuit (12). A welding torch and feeder assembly (11) has a controller (20) which is responsive to a predetermined event, such as the passage of time since the start of the arc, or the average temperature of the pipe (25) as indicated by two temperature-measuring devices (30, 32). The controller (20) adjusts the wire feed speed, the pulse frequency, the pulse width, the welding voltage, the welding current and/or other parameters so as to cause the arc to have the parameters most desired for welding copper-nickel pipe. The present invention provides for a hotter arc for starting the welding operation, thereby obtaining good penetration and bonding, and a cooler arc for continuing the welding operation, thereby preventing burn-through of the pipe (25).

Abstract: A method and apparatus for starting the electric arc of a welder by applying a high frequency, high voltage starting signal across the spark gap between the electrode and workpiece of the welder. This device and method comprises a series resonant circuit having a capacitive reactance element and an inductive reactance element combining to establish a resonant frequency for the series circuit, electrical drive means for energizing the series circuit at a driving frequency near a harmonic of the resonant frequency and means for converting the voltage developed across at least a portion of a designated one of the elements, generally the inductive reactance, into the starting signal.

Abstract: A method for reducing the generation of noise during arc welding by alternating current with welding machines with clocked current sources is disclosed. By modifying the curent set value on the control side with temporally non-linear functions by a digital-analog converter, a flow of the welding current which has limited upper tones can be generated.

Abstract: An apparatus and method are presented that optimize the output voltage and output current provided by an electronic welding station to a welding operation. A value for a specified welding operation parameter is selected and the values for other welding operation parameters that produce optimum welding results are recorded. These values are used to implement a control system which automatically varies these other parameters as a function of the adjustment of the selected parameter. Therefore, an operator need only adjust a single control parameter for a welding operation and the control system automatically selects the optimum values for the other parameters. This reduces the number of controls that an operator must adjust for a welding operation and results in higher operator efficiency and optimum welding results.

Abstract: An improved electronic welding station is disclosed. The welding station provides for an improved arc striking capability by providing a higher arc striking voltage and a large arc striking current and, once the arc is struck, automatically switches over to preselected parameters for conducting the welding operation. Also disclosed are a method for preventing transistor failure due to loads which tend to cause a very large instantaneous current flow and an apparatus for protecting the driver circuit and the remaining output transistors in the event that one of the output transistors should suffer a collector-to-base short. The welding station also describes a method of operating the cooling fan at a speed commensurate with the cooling requirements and periodically reversing the voltage to the cooling fan so as to extend the operating lifetime of the fan brushes.

Abstract: An improved electronic welding station is disclosed. The welding station provides for an improved arc striking capability by providing a higher arc striking voltage and a large arc striking current and, once the arc is struck, automatically switches over to preselected parameters for conducting the welding operation. Also disclosed are a method for preventing transistor failure due to loads which tend to cause a very large instantaneous current flow and an apparatus for protecting the driver circuit and the remaining output transistors in the event that one of the output transistors should suffer a collector-to-base short. The welding station also describes a method of operating the cooling fan at a speed commensurate with the cooling requirements and periodically reversing the voltage to the cooling fan so as to extend the operating lifetime of the fan brushes.

Abstract: In a pulse arc welding machine which is adapted to feed at a constant speed a welding wire as a waste electrode to turn the molten lump of the wire tip end into a spray state with a pulse current so as to effect a welding operation, the risetime and falltime of the pulse current influence the bead outer appearance, the gas shielding property and welding function and are varied independently of the other parameters controlled by the machine in accordance with the material quality of the welding wire, the wire diameter, and the wire feeding speed.

Abstract: Apparatus and method to reduce splatter and allow better semi-automatic welding in short circuiting arc welding of the type using a single D.C. power supply for causing a welding current to pass through a welding wire extending variable distances from a holder and between the welding wire and a workpiece at a molten pool on the workpiece. The welding current flows in response to an arc voltage while the welding wire is fed from the holder toward the workpiece whereby the welding wire is subjected to a succession of welding cycles each of which include an arcing condition during which the wire is spaced from the pool and a short circuit condition during which a molten metal ball formed on the end of the wire contacts the metal pool and then transfers from the wire to the workpieced by a necking action. A preselected, constant amount of energy is applied to the wire during the arcing condition for each welding cycle.

Abstract: An improvement in a short circuiting arc welding apparatus of the type including a power supply for causing a welding current of different levels to pass through a welding wire extending at variable extension distances from a holder and between the wire and a workpiece at a molten metal pool on the workpiece. This improvement includes control means for maintaining a generally constant wattage in the wire during the plasma boost portion of the arcing condition as the extension distance from the holder changes. Further, the improvement involves controlling the plasma or arcing condition after a plasma boost by a current curve gradually decreasing from the plasma boost portion toward the background current level for the system.

Abstract: A pulse arc discharge welding apparatus comprising a pulse current waveform control circuit for periodically outputting a pulse current group consisting of a plurality of pulses, pulse arc current supplying means for outputting a pulse arc current according to an output of said pulse current waveform control circuit and an arc welding means for performing pulse arc discharge with an output of said pulse arc current supplying means, to carry out a pulse arc welding operation. In such a pulse arc discharge welding apparatus, with a discharge current waveform provided in the form of high frequency pulses, the discharge light and the gas in pulse discharge and the electrode are regulated and controlled with high accuracy.

Abstract: A method of rehabilitating a hub body of a controllable pitch propeller of the type having port openings with threads for the bearing rings and seating surfaces for the O-rings of the blade-mounting assemblies comprises the steps of removing the threads, material underlying the threads and material at the O-ring seating surface to expose clean base metal at the port opening, excavating any casting defects in the exposed base metal area of the port opening, filling the excavated areas and all dowel holes with weld metal, grinding the weld metal flush with the adjacent clean base metal surfaces, positioning the hub such that the axis of the port opening is vertical, and applying weld filler material to the port opening by successive passes, starting at the bottom of the port opening and working upwardly, using an automatically and mechanically manipulated welding torch by pulse arc welding so as to lay down a multiplicity of adjacent beads of weld filler material extending circumferentially of the port opening

Abstract: A welding method and shielding gas therefor which enables the use of gas metal arc welding to produce smooth welds with little or no surface oxidation and without encountering arc instability during the metal deposition.

Abstract: An improvement in a short circuiting arc welding apparatus comprising a single D.C. power supply causing a welding current to pass through a welding wire extending from a holder and between said wire and workpiece at a molten metal pool on the workpiece, wherein the current flows in response to an arc voltage and the welding wire is subjected to a succession of welding cycles. Each of the welding cycles includes an arcing condition during which said wire is spaced from the pool and the energy applied to said wire exceeds a given value raising the temperature at the end of the wire to a molten temperature to form a molten metal ball on the end of the wire and a short circuit condition during which the molten metal ball on the end of the wire first contacts said molten metal pool and then transfers from the wire to the workpiece by a necking action breaking the molten metal ball from the wire to initiate an arc in a subsequent welding cycle. The welding cycles have a generally fixed frequency of repetition.

Abstract: Disclosed is a variable polarity power supply for arc welding that quickly switches between polarities in order to more easily re-establish the arc. The variable polarity power supply includes a current-limited boost circuit for providing increased open circuit voltage to re-establish the arc, while limiting the re-establishment current. The variable polarity power supply is particularly suitable for computer-controlled welding applications because it periodically restarts the arc in either direction without using high frequency radiation, and provides quick switching times along with a low reverse current to reduce the heat in the torch, thereby increasing the longevity of the torch.

Abstract: A method and device for controlling a power supply for arc welding in a manner to reduce spatter when the power supply is employed for depositing metal from a welding wire or electrode onto a workpiece by the short circuiting transfer mode wherein a welding current causes the welding wire to alternate between a short circuit condition and an arc condition with metal transfer occurring during a short circuit condition. This method and device includes the concept of shifting the welding current to a background current value in response to a short circuit condition, holding the welding current generally at the background current level for a preselected time, then allowing the welding current to reach the normal unimpeded current level, and causing the holding step to be terminated before the selected time in response to a detected arc condition.

Abstract: A method of bonding an insulated and coated wire which has an insulated coating on the outside of an electrically conductive wire is disclosed which consists in connecting one end of said insulated and coated wire to the anode side of an arc power source and connecting a discharge torch to the cathode side of said arc power source with an arc discharge performed between the tip of said insulated and coated wire and the discharge torch to form a ball at said end, and said ball being positioned with respect to the bonding pad of an electrically conductive electrode and bonding being performed with a specified pressure applied to said ball.

Abstract: A high quality, small-scale thermocouple is formed by the corona developed at the twisted ends of two wires connected to a high voltage, radio frequency source.

Abstract: A method and apparatus for TIG welding by passing an alternating current between a non-consumable electrode and a workpiece to form an arc, which apparatus comprises a single reactor with first and second coil portions and a common core, passing a direct current from a direct current power supply through the first coil portion of the reactor and in a negative direction from the workpiece to the electrode for creating a heating cycle, switchably disconnecting the direct current power supply from the circuit and immediately connecting the second coil portion of the reactor in a positive direction across the electrode and workpiece for creating a short cleaning cycle for cleaning the workpiece preparatory to the next heating cycle. These heating and cleaning cycles are continued to create a TIG welding process.

Abstract: An apparatus and method produces multi-level heat input for nuclear fuel rod weld formation using a single current level power supply. Different levels of electrical power are produced to achieve a low heat, high heat sequence by imposition of a sequence of inert atmospheric cover gases of different ionization energies at the welding site to regulate voltage drop and thereby electrical power level and heat input level for arc welding of the nuclear fuel rod to take place. A first cover gas, such as argon, is supplied to the weld chamber in a first welding pass for producing a high electrical current level and low heat input level, whereas a second cover gas, such as helium or a mixture of helium and argon, is supplied to the weld chamber in a second welding pass for producing low electrical current level and high heat input level.

Abstract: Method of welding aligned aluminum torque tube components, comprising (i) defining a stepped square-butt joint to be welded by preforming the ends of said torque tubes and assembling such ends together in the nested condition; (ii) establishing an electrical direct current arc between a positive consumable aluminum-based electrode and said joint as cathode, the arc being shrouded in a shielding gas consisting, by volume, of 2-5% oxygen and the remainder inert gas, the current to the arc being pulsed at a frequency of 40-60 cycles per second while maintaining an average current of at least 200 amps; and (iii) while holding the pulsed arc in a predetermined orientation (i.e., position angle 45.degree.-60.degree., lead angle 5.degree.-15.degree., transverse angle 12.degree.) to the joint, moving the arc along the joint in a single pass at a relative speed of at least 60 inches per minute.

Abstract: A welding apparatus for welding a new stud on to the end of a broken-off stud which comprises a conventional mig welding hose through which inert gas can pass and through which a mig welding wire can be fed, the hose having a conventional extension at one end thereof for attachment of a mig welding nozzle thereto, the extension also having a longitudinally extending contact tip guide attached thereto and through which the welding wire passes, the nozzle having an enlarged cylindrical portion which is received over the extension of the hose, and a reduced cylindrical portion extending over and beyond the contact tip guide in concentric relation thereto. The mig welding hose has a trigger for initiating the flow of inert gas through the hose and into the annular area between the guide and the nozzle, for supplying a d.c. welding voltage and for feeding the wire through the hose and through the contact tip guide.

Abstract: An unconsumable electrode such as tungsten is opposingly arranged with a base metal to be welded. An AC arc welding power supply is connected between the base metal and the unconsumable electrode. A filler wire such as of aluminum is fed by a wire feeder toward an arc-generated part between the base metal and the unconsumable electrode. Also included is a wire-heating power supply for producing a pulsed current. The wire heating power supply heats the filler wire by supplying thereto a pulsed current in accordance with a sync signal from the AC arc welding power supply or a detection signal of an arc current i.sub.A or an arc voltage of the AC arc power supply. The filler wire is thus heated by being supplied with a heating current i.sub.W in pulse form while the unconsumable electrode is kept negative by an AC arc formed between the unconsumable electrode and the base metal.

Abstract: A method of controlling the output of a power source in consumable electrode are welding in which a short circuiting phase and an arcing phase alternately take place between a consumable electrode and a workpiece in a shielding gas atmosphere, the method being characterized by repetition of a cycle of operation consisting of: a first stage of maintaining the output welding current at a first value of a relatively low level upon establishment of a short circuit across a gap between a consumable electrode and a workpiece; a second stage of maintaining the welding current at a second value of a relatively high level succeedingly to the first stage; a third stage of lowering the welding current to a third value of a low level upon detection of necking as a premonition of rupture of short circuiting molten metal between the electrode and workpiece; a fourth stage of, upon generation of an arc across a gap between the electrode and workpiece subsequent to the third stage, maintaining the welding current at a fourth