Abstract: A method for gas shielded arc welding steel rails spaced from each other to define a transverse gap comprising the steps of positioning an elongated steel barrier plate in the gap at the bottom of the spaced rails and filling the gap above the barrier plate with a molten steel from an advancing filler metal electrode by a gas shielded electric arc welding process initiated by an arc between the electrode and the barrier plate. A root pass is laid using the spray arc welding process, a second layer is laid using the pulsed arc welding process in part and the spray welding process in part, and the remainder of the base gap and the gaps between the webs and heads are filled by the continuous sequential laying of weld beads in the gaps using the pulsed arc process.

Abstract: An electric arc welding apparatus for depositing molten metal from an advancing welding wire into a weld puddle in an open root between two juxtapositioned plates where the root extends in a welding path and is formed by converging walls terminating in generally parallel walls spaced to define a gap, which apparatus comprises a contact holder with a wire outlet, a switching power supply directing welding current to the wire as the wire passes from the outlet toward the open root, with the advancing wire defining an electrode stick out between the contact holder and the weld puddle, a circuit for sensing the length of the stick out, and control means for adjusting the welding current as a function of the sensed stick out length.

Abstract: An arc length controlling method that is used in the practice of the pulsed welding in which welding is carried out by feeding an consumable electrode at a substantially constant speed while the pulse frequency f is set to a predetermined value. This method is carried out by effecting a welding after the counting time Tr and the target short-circuiting frequency Nr have been set, detecting the detected short-circuiting frequency Nk, and controlling the output voltage Vt to a value effective to allow the detected short-circuiting frequency Nk to be equal to the target short-circuiting frequency Nr.

Abstract: In a welding power supply for creating welding current in a succession of current pulses with a maximum current level and a trailing off state which current pulses passing through a series circuit including an inductor and electrode in welding relationship with a workpiece wherein the power supply has (a) an inverter stage with an input to be connected to a power source, a first terminal at a first electrical polarity when the inverter is on, a second terminal at a second electrical polarity when the inverter is on, and a control to generate an off signal to turn the inverter off and remove current from the terminals to shift said current pulse toward an off state; and, (b) a power switching stage including a transistor based switch having a conduction condition passing current from the first terminal upon creation of a first logic signal and a non-conduction condition blocking current upon creation of a second logic signal, the improvement comprising: a sensor for measuring the instantaneous value of the wel

Abstract: A process and a device for the gas-shielded MIG welding in modulated-spray mode, of aluminum, particularly aluminum alloys, or stainless steels, in which the current is modulated at a modulation frequency of less than 60 Hz. The shielding gas contains at least 90% helium, argon or a mixture thereof and at most 1.95% of at least one minor gaseous component chosen from oxygen and carbon dioxide. This process allows effective degassing of most of the diffusible hydrogen liable to be found in the pool of molten metal and improves the appearance and quality of the weld beads thus produced on workpieces or equipment intended for the rail, sea, air, road or space transport industry or for the chemical, petrochemical, electronic, nuclear or agrochemical industries.

Abstract: A hand carried, or hand-held, portable, arc welding apparatus. Designed to provide a variable square waveform welding current output. Powered by sealed high discharge rate, gel-cell, rechargeable batteries that, are sealed for safety. A new form of welding technology is provided for saving energy and making automated tack welds. A new self-diagnostic feature is provided for safe operation. A remote control option is provided as well as a way to control the heating and cooling of the weld. Duty cycle control and frequency control are provided for efficient control of the welding process.

Abstract: A method for manufacturing a fuel rod of the present invention includes a welding step of welding a cladding tube of said fuel rod to a plug by arc discharge; and a post welding step of subsequently discharging an arc to a welded portion by a predetermined arc current lower than that of the welding step. In the welding step and in the post welding step, the cladding tube and the plug are rotated with respect to an electrode for discharging the arc. The rotation speed of the cladding tube and the plug in the post welding step is higher than that in the welding step.

Abstract: A method of welding the ends of two pipes at the open root between the spaced ends by an STT electric arc welder, which comprises: selecting a welding wire having 0.06-0.15% by weight carbon, 0.90-1.40% by weight manganese, and 0.45-0.75% by weight silicon, as well as phosphorous, copper, stainless steel alloys and sulfur; maintaining the sulfur at a given percentage level of the selected wire in the specific range of 0.015 to 0.035% by weight; and maintaining said phosphorous at a given percentage level of said selected wire in the specific range of less than about 0.015%.

Abstract: The invention comprises a control system for Arc Welding for steady and pulsed direct current welding with a single three-phase bridge converter (1) For steady direct current welding, output DC voltage (V.sub.d) and current (1.sub.d) are varied through the tapping of transformer (2). Finer voltages can be obtained through the variation of firing angles .alpha. of the thyristors of the converter (1). The contemplated control system can also be used for pulsed DC current welding with an impured dynamic response with less effort. The background current, which lies between the maximum and minimum firing angle .alpha. of the thyristors of the converter (1), is set by the transformation ratio of the transformer (2) and the pulsed current is superimposed thereon through the relatively rapid changing of the firing angle .alpha..

Abstract: A controller and method for adjusting an output welding parameter of a D.C. electric arc welder for controlling a welding process wherein a welding wire is advanced toward a workpiece while an arc voltage is applied across the advancing wire and the workpiece, the control and method comprise measuring the rate of spatter events and then adjusting the output parameter to maintain the measured rate of spatter events at a selected rate in the range of 10-30 spatter events per second.

Abstract: A plasma arc utilizing apparatus includes a power supply unit disposed in a housing. The power supply unit converts an AC voltage to a DC voltage, which is applied to load for generating an arc therein. A compressor is disposed in the same housing for supplying the load with compressed gas that is to be ionized by the arc. The compressor has a leg by which the compressor is secured to the housing. The leg is embedded in an elastic material secured in the housing.

Abstract: An apparatus and method of short circuit arc welding two spaced ends of two pipe sections at a groove between the two pipe sections. The method and apparatus include the use of a cored metal electrode and moving the electrode toward the groove as the electrode is moved along the groove and about the outer peripheral surface of the pipe sections during the welding operation. The cored electrode is melted by an electric cycle which comprises a transfer portion and a plasma portion. The plasma portion is controlled to bridge the gap between the pipe sections for laying a root bead along the groove. The cored electrode is preferably a self-shielding electrode and includes alloying components in the core to form a root bead having a substantially similar composition as the composition of the two pipe sections. The apparatus and method has a selector to control the polarity of the individual cycles of a total welding procedure.

Abstract: In a power supply for creating a voltage to cause a current pulse between a consumable electrode and a workpiece to melt the end of the electrode into a droplet and propel the droplet toward the workpiece, where the power supply has a plurality of pulse controlling parameters, the improvement comprising: means for determining the real time dv/dt of the voltage during the current pulse; means for creating a detect signal in response to the real time dv/dt shifting from a negative value to a positive value; and means for adjusting at least one of the welding parameters in response to the detect signal.

Abstract: A method and apparatus for stopping a welding process includes monitoring the status of the arc. The output current is commanded to a level sufficient to clear a short if a short circuit forms when the process is stopping. A low current level is commanded after the short has cleared. The low current level is sufficiently low to prevent the forming of a large ball. This is repeated until a short does not form. The wire feed speed is monitored, and the stopping process begins when the wire feed speed drops below a threshold. The stopping process is performed with, a MIG process, a pulsed spray process, and a short circuit transfer welding process. The arc voltage is monitored to determine the status of the arc. The motor is commanded to stop in response to receiving a user provided stop command, and the braking of the motor is controlled. At least one output parameter may be reduced before the threshold is reached, but after receiving the stop signal in another alternative embodiment.

Abstract: In an electric arc welder for creating an electric arc for melting and depositing metal from an advancing welding wire onto a workpiece, said welder including a power supply having a switch operated by a pulse width modulator for creating a series of current pulses having a fixed frequency and a conduction width determined by the command voltage of a control signal driving said pulse width modulator and an error amplifier for generating the command signal in accordance with a set point voltage, the improvement comprising: first set point means for creating a fixed set point voltage, second set point means for creating a ramp set point voltage increasing at a selected rate from a starting voltage to create a selected slope, a toggle means having a first toggled condition for connecting said first set point means to the error amplifier and a second toggled condition for connecting said second set point means to the error amplifier, means for creating a short signal when the wire shorts against the workpiece and

Abstract: An improved method of gas metal arc welding (GMAW) utilizing relatively low current levels. The method includes providing a variable current to form and detach a droplet from a consumable wire electrode. During the welding process, the current is sufficient to produce a droplet at the end of a consumable electrode wire, but not to independently detach the droplet. After the droplet reaches a desired diameter, the current is lowered to induce an oscillation in the droplet. At a selected oscillation of the droplet, the current is increased. The combination of the momentum created by the oscillation of the droplet and the electromagnetic force caused by the increased current serves to detach the droplet from the electrode wire.

Abstract: An improved method of gas metal arc welding (GMAW) is disclosed. The method includes utilizing a pulsed current having a variable waveform to ensure the detachment of one-droplet-per-pulse of current. During the welding process, the current is sufficient to produce a droplet at the end of a consumable electrode wire. After the droplet reaches a desired size, the current is lowered to induce an oscillation in the droplet. The current is then increased which, in combination with the momentum created by the oscillation, effects droplet detachment. The oscillation may be monitored by observing the arc voltage to determine a preferred detachment instant. A computer implemented method allows for the adaptive control of the current waveform to accommodate for anticipatable variations in the welding conditions, while maintaining ODPP transfer and a constant pulse period. An accompanying system is disclosed for implementing the method of adaptive welding.

Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.

Abstract: A microprocessor based controller with a JAVA virtual machine used to control a specific electric arc welder having a switching type power supply for creating a welding cycle with a real time current waveform constituting several control parameters by rapidly switching a D.C. current in a controlled fashion by a pulse width modulator, which controller displays a waveform generated on an electrically operated waveform screen; allowing manual adjustment of at least a portion of the waveform displayed on the waveform screen to generate a new waveform on the waveform screen; and, operating the pulse width modulator to cause the power supply to create a real time waveform corresponding to the new waveform to execute the control parameters by the electric arc welder.

Abstract: A dual stage power supply for creating a D.C. welding current through an arc welding gap, the power supply comprising an input inverter stage with a full wave rectified A.C. voltage source and an output capacitor; and, an output chopper stage connected across the output capacitor, with the chopper including output leads connected across the arc welding gap, a switch for gating the output current of the inverter stage at a controlled rate through the leads and through the arc welding gap, an output inductor in one of the leads between the switch and the arc welding gap and a free wheeling diode across the leads between the switch and the output inductor.

Abstract: An improved method of arc welding uses a single power supply connected to opposed welding torches placed on both sides of a workpiece. Each torch is connected to a different polarity lead of the power supply and forms a separate arc with the workpiece. When a current is supplied to the first torch, it is guided from the first electrode, through the first arc, the workpiece, the second arc, and to the electrode of the second torch. This guiding function improves the penetration, concentration, as well as the directional stability of the arc. This permits the effective and efficient welding of relatively thick workpieces using existing equipment at low current levels.

Abstract: A new system for welding sections of pipe together to form a long, continuous pipeline. A welding bug is mounted on a guide track which goes around the circumference of the pipe. The welding bug is provided with a wire feeder, a motor to drive the wire feeder, and driving motor for driving the bug around the track. One may vary the speed of the bug and the wire feeder while the bug is continuously driven around the track. The welding head on the welding bug is powered by a surface-tension-transfer power source. The initial or root pass is made external of the pipe. In one embodiment there is a dual welding wire feeder for driving two welding wires simultaneously at the same speed.

Abstract: A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof.

Abstract: An apparatus and method of short circuiting arc welding two spaced ends of two pipe sections at a groove between the two pipe sections. The method and apparatus include the use of a cored metal electrode and moving the electrode toward the groove as the electrode is moved along the groove and about the outer peripheral surface of the pipe sections during the welding operation. The cored electrode is melted by an electric wave which comprises a transfer portion and a controlled melting portion. The melting portion is controlled to bridge the gap between the pipe sections for laying a root bead along the groove. The cored electrode is preferably a self-shielding electrode and includes alloying components in the core to form a root bead having a substantially similar composition as the composition of the two pipe sections.

Abstract: A method of arc welding to build the thickness of a high sulfur, low alloy steel workpiece comprises the steps of preparing the surface of the high sulfur, low alloy workpiece; applying a layer of metal over the prepared surface using a low energy arc; and applying additional layers of metal using a high energy welding arc.

Abstract: A method of welding together two steel plates with a thickness greater than about 3/8 inches from one side of the plates, the method comprising the steps of: tapering a generally straight edge of the plates to form an included angle in the range of about 40-60.degree. with a nose at the protruding portion of each edge; positioning the plates with the edges spaced from each other to define an elongated channel with the nose of each edge at the bottom of the channel and spaced from each other to define an elongated generally straight gap with a width g; moving an electrode having a diameter of less than approximately 0.

Abstract: DC power from a smoothing capacitor is converted into high frequency power by an inverter, and then lowered by an output transformer. The lowered high frequency power is converted into DC power by an output rectifier and a DC reactor, and then supplied to a load. The load is short-circuited and then opened to initiate arcing. The short-circuiting and the arcing alternate. An auxiliary rectifier provides a load-voltage representative signal, and a current detector detects a load current. A load-current representative signal is differentiated by a differentiation circuit. The signals from the auxiliary rectifier, the current detector and the differentiation circuit, and a reference signal are applied to an operational amplifier. A control circuit controls the inverter such that the output of the operational amplifier can be zero.

Abstract: A welding apparatus includes a welding torch and a workpiece support. The welding apparatus also includes a circuit for creating a first voltage drop between the welding torch and the workpiece support so as to generate heat which melts a quantity of weld wire, the creating circuit having a power supply. The apparatus system further includes a power cable which is electrically interposed between the power supply and the welding torch. Additionally, the welding apparatus includes a circuit for measuring a second voltage drop across the power cable at the same time the first voltage drop is being created by the creating circuit. A method of operating a welding system is also disclosed.

Abstract: A welding power control apparatus that removes the effects of shorting and noise to accurately detect droplet separation, thereby reducing spatter during droplet separation and when shorting occurs, and stabilizing welding results is achieved. Welding conditions such as welding voltage, welding current, shorting, and droplet separation are detected. Based on thus detected welding conditions, a pulse wave configuration unit generates a steady-state pulse wave and a compensation pulse wave. The steady-state pulse wave is defined by a pulse height for a pulse period and a base height lower than the first pulse height for a base period. The compensation pulse wave defined by a compensation pulse height lower than the pulse height for a compensation period followed by the pulse wave based on said detected welding conditions.

Abstract: A multi-stage down chopper for arc welding by creating current flow between an electrode and a workpiece, the chopper includes a D.C. input source, a first switching stage, with a first switch device and a first choke, this first stage selectively connects the D.C. input source across the electrode and workpiece at a controlled duty cycle and switching rate and a second switching stage, with a second switch device and a second choke, the second stage also selectively connects the D.C. input source across the electrode and workpiece at the aforesaid controlled duty cycle and switching rate, wherein the chopper is improved by the first and second chokes onto a single core and by providing a minimum current override feedback circuit.

Abstract: A "hot start" method for arc welding includes selecting a first weld current, setting a time interval, striking an arc, flowing a second, higher weld current through the welding rod and then, after a brief time interval, reducing the current through the rod to the value of the first weld current. Also disclosed is a new arc welder stator having two groups of slots around a core. The group of larger slots contains the weld current windings and slots in the group of smaller slots contain windings for timing, gate voltage, battery charging, auxiliary power and the like. A new cooling apparatus for an arc welder has an air duct and a "double-bladed" fan for flowing air along several paths and cooling both the welder control section and the generating section. A new method for electronically controlling engine speed in an engine-driven arc welder is also disclosed.

Abstract: A welding process of repairing a ferrous NiMoV low alloy steel turbine component. A first and a second layer of weld material are welded to the turbine component at electrical current levels chosen so as to prevent a substantial decrease and a substantial increase in the hardness of the component. This method involves selecting these electrical current levels. Additionally, this invention relates to selecting appropriate electrical current levels that minimizes the difference between a maximum and a minimum level of hardness while welding a first and a second layer of weld material. This invention also includes a method for preventing a substantial decrease in the hardness of the component as a result of the welding process.

Abstract: An engine driven welding power supply is disclosed. The power supply produces a welding output having a plurality of volt-ampere curves. Each of the curves is associated with a selected current output and includes a slope over usable welding range. The magnitude of the slope over the usable welding range is dependent on the selected current output, particularly at a middle range of output currents. The power supply includes a AC generator that provides an AC signal. A rectifier rectifies the AC signals and provides a DC output. The DC output is provided to an output inductor that provides a smooth DC output. The V-A curves are produced by phase control in the rectifier.

Abstract: A power source for a plasma cutting tool includes first and second power switching circuits and a controller. Each power switching circuit includes a switch for switching electrical power to a respective output, and the outputs of the power switching circuits are connected in parallel. The controller controls the switches in response to a desired output for the power source. The controller also includes a synchronizer for synchronizing the first and second switches so that both of the switches switch electrical power at a common duty cycle. The synchronizer can also maintain a 180 degree phase relationship between switching of the first and second switches. Related methods are also discussed.

Abstract: A welding power supply that includes a series resonant converter, including at least one switch and at least one capacitor is disclosed. The converter includes a switching circuit including an enable input. A voltage sensing circuit that determines the earliest safe switching time of the switch is provided. The safe switching time is the time that will prevent a peak voltage on the capacitor from exceeding a predetermined threshold for a next cycle of the converter. The voltage sensing circuit provides an enable signal to the enable input when the earliest switching time has passed, to enable the switching circuit. A pair of welding output terminals connected to the series resonant converter receives the output. A controller including a curve shaper, for providing a constant current output in the welding range is also disclosed. The controller also provides an adaptive hot start that provides varying amounts of energy in response to the welders skill.

Abstract: Methods are disclosed for gas shielded arc welding steel railroad rails spaced from each other to define a transverse gap, one of which methods comprises the steps of providing an elongated steel barrier plate wedged into the gap at the bottom of the spaced rails and filling gap above said steel barrier plate with a molten steel from an advancing filler metal electrode by a gas shielded electric arc welding process initiated by an arc between the electrode and the barrier plate. A second method comprises the continuous sequential laying of weld beads in the gap between rail heads along paths extending in laterally opposite directions for the beads to have first ends extending outwardly of an edge of the head in cantilever relationship thereto and which first ends are vertically thicker than second ends of the beads which are spaced from the first ends in the direction toward the opposite edge of the head.

Abstract: A power source for a welding or cutting system is provided which preferably includes a power switching circuit, a switching cessation detector, and overshoot reducing means. The power switching circuit switches electrical power to provide an electrical power output signal of the power source to an electric arc tool operatively coupled thereto. The switching cessation detector is responsive to the power switching circuit. The cessation detector generates a switching cessation signal responsive to detecting electrical power being supplied to an electric arc tool operatively coupled to the power source when the power switching circuit ceases switching. The overshoot reducing means is responsive to the switching cessation signal and reduces excess current output from the power switching circuit upon resumption of switching. Related methods are also discussed.

Abstract: A method of and welder for welding a corrosion resistant, wallpaper alloy to the inside surface of a vessel wall formed from a corrosion susceptible steel sheet after the wallpaper alloy has been affixed to the inside to provide an exposed seam of wallpaper alloy extending in a given path wherein the method and welder comprising moving a welding wire toward the seam, melting and depositing the welding wire onto the seam along the path by a short circuit arc welding process of the type having a welding cycle with a short condition and an arcing condition, which arcing condition constitutes a plasma boost portion with a set peak current level followed by a plasma portion with a current decreasing from said peak current level toward a set background current level with a given time between the plasma boost portion and the short condition andsetting the length of time of the plasma portion of the arcing condition to a value greater than 25% of the given time or greater than 2.0 ms.

Abstract: A method and apparatus for arc welding, particularly starting an arc is disclosed. A welding power source that provides a welding current to an electrode and a workpiece includes a source of welding current having an inductor. The inductor and current source are connected to a pair of outputs, such as the output studs, and form a welding current path including the source of current, the output inductor, the outputs and the electrode and workpiece. A source of a high frequency voltage, such as a high frequency coupling coil is included in the welding current path. An arc starting circuit provides a controllable current path for current flow in the inductor prior to the application of high frequency voltage. The arc starting current path is not the welding current path.

Abstract: An apparatus and method for computerized interactive control, measurement and documentation of are welding utilizing a single power source that facilitates continuous precision welding. Operational interactivity between the welding operations and the workpiece operations, in connection with predetermined optimum welding operational parameters, provides contemporaneous feedback of critical welding operational parameters to the welding operator, producing an alarm if welding is attempted outside a first predetermined range of deviation from optimum welding operational parameters and temporarily interrupting power to the welding operation if welding is attempted outside of a second predetermined range of deviation from the optimum welding operation parameters. A complete log of the welding operational parameters is stored for subsequent retrieval and display, providing training and evaluation of welding operators as well as verification of compliance with required welding practices and procedures.

Abstract: A method is indicated for igniting a welding arc between a fixed electrode and a metal workpiece to be welded, whereby a covering protective gas is supplied by a nozzle that extends into the welding area. Before a welding power source is switched on for the welding arc, an auxiliary arc supplied by an auxiliary power source is ignited, which ignites the welding arc after the welding power source is switched on. To better ionize the welding area and ensure the ignition of the auxiliary welding arc, a high-frequency electric arc is produced in the welding area between the nozzle and the workpiece by means of a pulse generator which produces high-frequency high-voltage pulses.

Abstract: Variable polarity welding is used to repair coated articles, particularly gas turbine engine components. The variable polarity welding process is found to remove the coating during the welding process. This permits the elimination of costly steps which would otherwise be needed in the repair process.

Abstract: A power supply for supplying a substantially square wave of current to a welding arc and including a source of A.C. power having a succession of positive and negative portions forming an input voltage cycle; first switch means for initiating a positive output current pulse at a selected first switching point during the positive portion of the input voltage cycle; second switch means for initiating a negative output current pulse at a selected second switching point during the negative portion of the input voltage cycle; means for sensing the output current through the arc; means responsive to the output current for creating a command signal as a voltage level which varies according to the desired instantaneous output current through the arc; and, control means for automatically selecting the first and second switching points in response to the voltage level.

Abstract: A drive shaft assembly includes an aluminum torque tube and aluminum yokes that are arc welded to the ends of the torque tube. The torque tube has a hollow cylindrical end portion at each end that is pressed onto an annular end portion of the respective yoke to form a narrow annular slit. The two parts are then arc welded together by forming an electric arc between the parts at the narrow annular slit and a consumable aluminum based electrode. The electric arc is sustained with a pulsed high amperage direct current to fill the narrow annular slit with aluminum based material from the consumable electrode in a single pass.

Abstract: An MAG arc welding method and apparatus is capable of achieving a welding bead in a regular ripple pattern or in a suitable sectional form. The welding power source generates the first welding current I1 and a second welding current I2 larger than the first welding current. The wire melting speed is changed by switching between the first and the second welding currents. The welding method or apparatus according to the invention generates the first arc length more than 2 mm and the second arc length more than the first arc length and switches between both arc length at a switching frequency F of 0.5 to 25 Hz. The ratio of the second to the first welding currents is made to be in 1.03 to 1.20. In addition to a welding method to change the arc length by switching the first and the second welding currents at a constant wire feeding rate, the present welding method makes it possible to carry out the lap welding or butt welding even when there is a large gap.

Abstract: An apparatus and method for detecting phase loss in a cutting or welding system is provided. The apparatus preferably includes a cutting or welding torch and a power source operatively connected to the torch. The power source for a cutting or welding system preferably has a power circuit which includes an electrical input line positioned to receive power from an external power supply, a transformer having a primary side connected to the input line and a secondary side, a rectifier operatively connected to the secondary side of the transformer, and an output line connected to the rectifier. The power source also has a phase loss detector operatively connected to the secondary side of the transformer for detecting phase loss responsive to a ripple voltage exceeding a predetermined threshold.

Abstract: A metal member, such as a metal mold, can be securely repaired by a welding machine and an arc melting machine. A proper volume of fine welding powder or a thin sheet-type welding material is provided on the portion of the metal member to be repaired. A primary electrode of the welding machine is pressed to a portion of the welding powder or the welding material. A large pulse current of 300-1500 amperes is applied to the primary electrode for a short period of 1/1000-4/1000 seconds to form dot-shaped welded metal nuggets on the metal member, which nuggets are made to couple or overlap continuously with other plural welded metal nuggets. Thus, a build-up welding with nuggets, lines of nuggets or layers of nuggets is established and the welded portion has a desired thickness in a desired area of the portion to be repaired. The build-up welded portion of the metal member to be repaired is enveloped in an inactive gas atmosphere.

Abstract: Methods and apparatus for the electric arc welding of metal workpieces utilize a current comprised of squared waveform high-amplitude current pulse groups alternated with squared waveform low-amplitude current pulse groups, the current pulse groups being developed or developed and algorithmically varied in response to detected welding arc voltage/current condition changes and with respect to pulse group periods, pulse group peak current amplitudes, pulse group repetition frequencies, and pulse group current rise/fall rates for particular applications.

Abstract: An apparatus and method for displaying data to a user of a cutting or welding system is provided. The apparatus preferably has an arc torch including at least an electrode having an arc discharge end and means for creating an electrical arc extending from the electrode to a workpiece and a cutting or welding power source operatively connected to the arc torch for supplying power to the arc torch. The cutting or welding power source preferably includes a power circuit having an electrical input line positioned to receive power from an external power supply, a transformer having a primary side connected to the input line and a secondary side, a rectifier connected to the secondary side of the transformer, and an output line connected to the rectifier.

Abstract: A process of depositing layers of weld metal onto a ferrous NiMoV low alloy steel turbine component. During a deposition of a first layer of weld metal, low levels of amperage are used to prevent a dramatic increase in a level of hardness of a heat affected zone produced during the deposition of the first layer of weld metal. During a deposition of a second layer of weld metal, higher levels of amperage are used to temper the heat affected zone but not high enough to overtemper the HAZ.