Abstract: An electric arc GMAW welder is provided, which welder includes a high speed switching power supply with a controller for creating a first or second weld process across the gap between a workpiece and a welding wire advanced toward the workpiece. The first process uses a first current waveform and the second process uses a second current waveform. A circuit is provided for shifting between the first and second weld processes. The shifting circuit includes a counter for counting the waveforms in the first and second processes and a circuit to shift from the process being processed to the other weld process when the waveform count of the weld process being processed reaches a preselected number for such weld process.

Abstract: Process for the arc welding in pulsed mode of one or more workpieces made of carbon steel, stainless steel, aluminum or aluminum alloy, with the use of a gas shield, in which an electric arc welding torch is supplied with at least one consumable wire at a wire feed speed (Vwire) and the consumable wire is subjected to current pulses, in order to melt the end of the consumable wire in which, for a given pulse frequency, a wire feed speed (Fwire), a mean current (Imean) value and an rms current (Irms) value are chosen, so as to detach one drop of molten metal per current pulse and to obtain a low degree of spatter.

Abstract: A method and apparatus for MIG welding is disclosed. When in an ac mode the output is unbalanced, or the balance may be controlled. The balance may be controlled to provide a desired deposition rate and/or to obtain a desired dilution. The frequency may be any frequency, for example 30 Hz, 60 Hz, 90 Hz, or more. The weld path may have groove with angle of less than 50 degrees. A consumable, cored, wire may be used, and provide at rates of 30 or 35 pounds per hour using a single arc. In various embodiments the balance may have a negative portion of at least 1.5 times the positive portion. The process may be started using an extended negative portion, for example 0.5 or 0.75 seconds.

Abstract: An electric arc welding system for creating an AC welding arc between an electrode and a workpiece wherein the system comprises a first controller for a first power supply to cause the first power supply to create an AC current between the electrode and workpiece by generating a switch signal or command with polarity reversing switching points in the first controller, with the first controller operated at first welding parameters in response to first power supply specific parameter signals to the first controller. The system has at least one slave controller for operating a slave power supply to create an AC current between the electrode and workpiece by reversing polarity of the AC current at switching points where the slave controller is operated at second welding parameters in response to second power supply specific parameter signals to the slave controller.

Abstract: An electric arc GMAW welder is provided, which welder includes a high speed switching power supply with a controller for creating a first or second weld process across the gap between a workpiece and a welding wire advanced toward the workpiece. The first process uses a first current waveform and the second process uses a second current waveform. A circuit is provided for shifting between the first and second weld processes. The shifting circuit includes a counter for counting the waveforms in the first and second processes and a circuit to shift from the process being processed to the other weld process when the waveform count of the weld process being processed reaches a preselected number for such weld process.

Abstract: A method of designing a series of waveforms for current cycles generated by a waveform generator to control the waveforms of a welding process performed by an electric arc welder, where the waveforms are stored in a memory stack by work points. The method comprises: integrating the arc current of the waveform designed for each of the many work points to obtain an integrated amount; plotting the integrated amounts for each of the work points; creating a regression curve statistically matching the plotted amounts to reveal outlier amounts; selecting an outlier amount; and, changing the waveform corresponding to the selected outlier amount to decrease the deviation of the integrated amount of the changed waveform from the regression curve.

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: An IGBT (16) intermittently interrupts a current from a positive terminal (12P) of a DC supply (2) to a workpiece (24). An IGBT (20) intermittently interrupts a current from a negative terminal (12N) of the DC supply (2) to the workpiece (24). A control circuit (32) and a drive signal generating circuit (34) ON-OFF control the IGBTs (16, 20). The control circuit (32) causes the drive signal generating circuit (34) to control the IGBTs (16, 20) in such a manner as to provide a repetition of a cycle consisting of an AC period during which the IGBTs (16, 20) are alternately rendered conductive, and a DC period following the AC period during which the IGBT (16) is rendered continuously conductive.

Abstract: An electric arc welder for creating a welding cycle with a real time current waveform constituting several control parameters by a microprocessor that controls a power supply by a signal so the output of the power supply traces a desired waveform and dynamic reaction behavior to arc conditions defined by the control parameters. The welder has a controller for creating the signal and reading the parameters, a graphic user interface program controlled by input from a graphic user interface computer, a system with a first interface for an interactive display for displaying the desired waveform and dynamic behavior and at least one manipulative control parameter, a second interface for a manual data entry device to change the waveform and/or the parameters and a digital communication link from the graphic user interface to the welder microprocessor controller for causing the welder to perform the desired waveform by controlling the signal.

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: A power supply apparatus for a welder includes a rectifier (104) and a smoothing reactor (106) which operate together to convert a commercial AC supply voltage to a DC voltage. The DC voltage is converted to a high-frequency voltage by an inverter (108), which, in turn, is voltage-transformed by a voltage-transformer (110). The voltage-transformed, high-frequency voltage is converted to a DC voltage by a rectifying diode (112) and a smoothing reactor (114), and the resulting DC voltage is applied to a workpiece (118a) and a torch (118b). A current detector (120) develops a load current representative signal, and a control circuit (122) so controls a drive circuit (126) which drives the inverter (108) that the load current representative signal becomes equal to a reference current signal provided by a reference source (124). When a small load current is used, a pulse forming switch (140) is repetitively turned on and off to produce a pulse current from a pulse current setting source (139).

Abstract: A method and apparatus for MIG welding is disclosed. When in an ac mode the output is unbalanced, or the balance may be controlled. The balance may be controlled to provide a desired deposition rate and/or to obtain a desired dilution. The frequency may be any frequency, for example 30 Hz, 60 Hz, 90 Hz, or more. The weld path may have groove with angle of less than 50 degrees. A consumable, cored, wire may be used, and provide at rates of 30 or 35 pounds per hour using a single arc. In various embodiments the balance may have a negative portion of at least 1.5 times the positive portion. The process may be started using an extended negative portion, for example 0.5 or 0.75 seconds.

Abstract: The present invention relates to an apparatus for assessing start-of-weld and steady state welding stability in pulsed arc consumable electrode gas-shielded welding. According to the present welding stability assessment apparatus, in order to obtain a pass/fail decision on start-of-weld welding stability for pulsed arc welding, an irregularity value is computed by a computer means, based on detected values from a detector means; and a pass/fail decision is made by an assessment means, thus making it possible to perform accurate assessment of start-of-weld welding stability in pulsed-arc welding.

Abstract: A method and apparatus for welding, and particularly for clearing a short while welding is disclosed. If a short occurs, output current is increased from a first magnitude to a second magnitude and the short is monitored. If the short has not cleared after the current has reached the second magnitude the current is increased to a third magnitude. The difference between the second and first magnitudes is less than the difference between the third and second magnitudes. The current may be is increased from a fourth magnitude (which may be the normal operating magnitude) to the first magnitude before the increase to the second magnitude. The difference between the first and fourth magnitudes is less than the difference between the third magnitude and the second magnitude. The current is increased to the second magnitude only if the short has not cleared after the current is increased to the first magnitude.

Abstract: Welding controller 1 has CPU 1a, ROM1 1b, ROM2 1c and RAM 1d. Programs and data are written into the ROM1 1b and can be rewritten. Sequential welding data is written into the RAM 1d and can be rewritten. A write program for writing programs or data or sequential welding data into the ROM1 1b or the RAM 1d is stored in the ROM2 1c. When a welding control program or data or sequential welding data is input into the CPU 1a from an input device 10 or a computer 12, the CPU 1a executes the write program to write the inputted program or data or sequential welding data into the ROM1 1b or the RAM 1d. Preferably, ROM 1b is an in situ programmable memory, such as a flash memory or EEPROM.

Abstract: A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a welding gap between an electrode and a workpiece, the power supply comprises a high capacity transformer that converts said line voltage to an AC output voltage, and a rectifier that converts the AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero volts and a negative terminal and the common terminal. The power supply has a first switch that connects the positive terminal to the common terminal across the gap when a gate signal is applied to the first switch, a second switch for connecting the negative terminal to the common terminal across the gap when a gate signal is applied to the second switch and a pulse width modulator operated for generating pulses at a frequency of at least about 18 kHz.

Abstract: In a method and an apparatus for controlling AC pulse arc welding executed by supplying a welding current flowing between a welding wire and an object to be welded with feeding the welding wire at a feeding speed corresponding to a predetermined feeding speed setting signal, a one-period process for supplying the welding current is repeatedly executed. The one-period process includes a first process during a peak time interval, a second process during a negative electrode time interval, and a third process during a base time interval. The one-period process further includes a fourth process during a switching current interval, inserted between the peak time interval and the negative electrode time interval, for supplying a welding current having a switching current for stopping growth of droplet which is smaller than a threshold current with a positive electrode polarity.

Abstract: In an arc welding method and apparatus, a plasma (13) is generated at a welding intended position on a base material (2) by a laser (16) irradiated to the base material (2). When a discharge electrode (12) is at a minus potential, an arc discharge (4) takes place in the direction of the plasma (13) and is induced at a position irradiated with the laser (16). When the electrode (12) is at a plus potential, arc electrons are generated from a laser irradiated point and discharged to the electrode (12). When a voltage applied between the electrode (12) and the base material (2) is alternating, the polarities of the electrode (12) and the base material (2) alternately change so that the foregoing phenomena alternately occur. When the base material (2) is at a minus potential, an arc discharge (4) takes place from a laser spot.

Abstract: A system for creating an actual waveform at the output of an electric arc welder and caused by a waveform generator where the welder has a display and customizing screen to design a commanded waveform for processing by the waveform generator. The system includes a program to display a target waveform on the screen, a program to display the commanded waveform on the screen, a computer terminal to manually customize the commanded waveform to generally match the target waveform controlling the waveform generator to cause the actual waveform produced by the welder to match with the target waveform.

Abstract: A narrow gap welding method by which V-shaped or single-bevel grooved multi-layer build-up welding is carried out, comprises the steps of welding a first layer by applying a welding current by which a globule transfer pattern is made into a spray pattern by a waveform in which a direct current and a pulse current are caused to overlap, and thereafter welding the second layer by applying a direct current.

Abstract: An electric arc welder including a high speed switching power supply with a controller for creating high frequency current pulses through the gap between a workpiece and a welding wire advancing toward the workpiece, where the pulses and a background current defining a series of weld cycles. A wave shape generator defines the shape of the pulses and the background current including a controlled ramp up and/or ramp down in each of said cycles and a circuit to change the shapes of the pulses and/or background current in a repeating pattern in each of the weld cycles. The shape change in a cycle can be between first and second shapes or by a rhythmic AC modulation.

Abstract: An electric arc welding system for creating an AC welding arc between an electrode and a workpiece wherein the system comprises a first controller for a first power supply to cause the first power supply to create an AC current between the electrode and workpiece by generating a switch signal or command with polarity reversing switching points in the first controller, with the first controller operated at first welding parameters in response to first power supply specific parameter signals to the first controller. The system has at least one slave controller for operating a slave power supply to create an AC current between the electrode and workpiece by reversing polarity of the AC current at switching points where the slave controller is operated at second welding parameters in response to second power supply specific parameter signals to the slave controller.

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: The present invention relates to an apparatus for assessing start-of-weld and steady state welding stability in pulsed arc consumable electrode gas-shielded welding. According to the present welding stability assessment apparatus, in order to obtain a pass/fail decision on start-of-weld welding stability for pulsed arc welding, an irregularity value is computed by a computer means, based on detected values from a detector means; and a pass/fail decision is made by an assessment means, thus making it possible to perform accurate assessment of start-of-weld welding stability in pulsed-arc welding.

Abstract: The invention provides a welding system capable of freely controlling the dispersion and concentration of arc heat over the groove face with an extreamly narrow gap and a high strength and high quality welded joint structure which is formed by this welding system and which is capable of preventing softening/hardening of the structure, the lowering of the toughness thereof and the generation of a crack. According to the welding system, the melting rate of a welding wire is controlled relative to the welding wire feeding rate by changing the characteristic of an arc current so that the range of behavior and the transfer rate of the arc pole (the arc generating main point at a groove surface) are controlled. Further, the welded joint structure consists of a high strength steel having a superfine grain structure with a carbon equivalent of as low as less than 0.

Abstract: A pulse power system includes an energy storing device for storing electric energy; a high power arc switch comprising: a cylindrical housing having a central axis and defining a predetermined discharging region; a first electrode disposed within the cylindrical housing to be movable in a direction of the central axis; a second electrode disposed within the cylindrical housing and spaced away from the first electrode at a predetermined distance, an arc generating between the first and second electrodes as the first electrode approaches the second electrode; an insulating member formed at a portion between the first and second electrodes except for the discharging region; and a solenoid coil for forming a magnetic field within the discharging region in a direction of the central axis, the arc formed between the first and second electrodes being spirally moved in a direction of the central axis by a magnetic field formed in a circular direction by the arc and the magnetic field formed by the solenoid coil in th

Abstract: Process for the arc welding in pulsed mode of one or more workpieces made of carbon steel, stainless steel, aluminum or aluminum alloy, with the use of a gas shield, in which an electric arc welding torch is supplied with at least one consumable wire at a wire feed speed (Vwire) and the consumable wire is subjected to current pulses, in order to melt the end of the consumable wire in which, for a given pulse frequency, a wire feed speed (Fwire), a mean current (Imean) value and an rms current (Irms) value are chosen, so as to detach one drop of molten metal per current pulse and to obtain a low degree of spatter.

Abstract: A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a welding gap between an electrode and a workpiece, the power supply comprises a high capacity transformer that converts said line voltage to an AC output voltage, and a rectifier that converts the AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero volts and a negative terminal and the common terminal. The power supply has a first switch that connects the positive terminal to the common terminal across the gap when a gate signal is applied to the first switch, a second switch for connecting the negative terminal to the common terminal across the gap when a gate signal is applied to the second switch and a pulse width modulator operated for generating pulses at a frequency of at least about 18 kHz.

Abstract: The invention comprises a method and an arrangement for pulsed gas metal-arc welding with an electrode fed to the welding site continuously at a given rate, the fusion conditions being adapted in such a manner that the material transfer from the electrode (7) to the workpiece (8) takes place essentially without short-circuiting drops by the welding current being periodically increased to a pulse current of such size and duration that the current density in the electrode causes sufficient electromagnetic forces in order to separate one drop for each pulse, and where the arc length is stabilized by regulating the power supply for the arc by means of a regulator mainly on the basis of a measured arc voltage, characterized in that short-circuiting of the arc is detected as arc-voltage decreases and/or current increases, and in that the fusion power supplied is increased by the arc-length regulator being given an additional increase for each short-circuit detected.

Abstract: A method and a device for pulsed arc welding in which the electric current has conductance with pulse drops and/or pulse rises between 50 A/ms and 1000 A/ms, and more particularly between 100 A/ms and 500 A/ms, with the exception of a triangular pulse. The invention is applicable to MIG or MAG welding.

Abstract: An consumable electrode AC pulsed arc welding is performed by repeatedly executing a cycle of supplying a peak current Ip in an electrode positive polarity, then supplying an electrode negative current Ien in an electrode negative polarity and finally supplying a base current Ib in the electrode positive polarity. During a base current supply time, the rate of increase dVb/dt of the base voltage Vb is detected. Should the base voltage increase rate dVb/dt detected be larger than a predetermined determining value &Dgr;Vu, it means that the arc interruption is likely to occur and, therefore, since that timing, the peak current Ip for the subsequent cycle is supplied to thereby prevent the arc interruption from occurring.

Abstract: A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a welding gap between an electrode and a workpiece, the power supply comprises a high capacity transformer that converts said line voltage to an AC output voltage, and a rectifier that converts the AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero volts and a negative terminal and the common terminal. The power supply has a first switch that connects the positive terminal to the common terminal across the gap when a gate signal is applied to the first switch, a second switch for connecting the negative terminal to the common terminal across the gap when a gate signal is applied to the second switch and a pulse width modulator operated for generating pulses at a frequency of at least about 18 kHz.

Abstract: In a method and an apparatus for controlling AC pulse arc welding executed by supplying a welding current flowing between a welding wire and an object to be welded with feeding the welding wire at a feeding speed corresponding to a predetermined feeding speed setting signal, a one-period process for supplying the welding current is repeatedly executed. The one-period process includes a first process during a peak time interval, a second process during a negative electrode time interval, and a third process during a base time interval. The one-period process further includes a fourth process during a switching current interval, inserted between the peak time interval and the negative electrode time interval, for supplying a welding current having a switching current for stopping growth of droplet which is smaller than a threshold current with a positive electrode polarity.

Abstract: Comprising means for feeding a welding wire, means for feeding a pulse current between the welding wire and base metal, and means for controlling this pulse current feeding means, the control means controls the pulse current feeding means so as to flare up the welding wire upon arc starting, and then controls the pulse current feeding means until the pulse current becomes lower in frequency than the pulse frequency of the main welding current.

Abstract: An arc welding control method and apparatus includes a voltage control loop in which a pulsation parameter such as pulse width, pulse amplitude, background amplitude between pulses, or frequency, is adjusted to compensate for deviations in the arc voltage, and a second, slower feedback loop which adjusts a second parameter of the system in order to cause the pulsation parameter to return to a desired value as a result of the effect of the adjusted second parameter on the arc voltage.

Abstract: The invention provides a welding system capable of freely controlling the dispersion and concentration of arc heat over the groove face with an extreamly narrow gap and a high strength and high quality welded joint structure which is formed by this welding system and which is capable of preventing softening/hardening of the structure, the lowering of the toughness thereof and the generation of a crack. According to the welding system, the melting rate of a welding wire is controlled relative to the welding wire feeding rate by changing the characteristic of an arc current so that the range of behavior and the transfer rate of the arc pole (the arc generating main point at a groove surface) are controlled. Further, the welded joint structure consists of a high strength steel having a superfine grain structure with a carbon equivalent of as low a less than 0.

Abstract: The number of cycles R of a fundamental frequency <SET>F (Hz) for a set value Tw (ms) of a set weld time [WELD] is first found as a real number. The number of cycles R conforms to the number of times (real number) of repetition of the fundamental frequency <SET>F cycle in the interval of the set weld time Tw and is given as Tw×<SET>F (step B1). An AC waveform cycle set value Ns (integer) for the set weld time Tw is then determined as an integer Min [N] that is equal to the number of cycles R or to the least one (i.e., the integer closest to R) of larger integers (N) than R (step B2). An AC waveform cycle set frequency Fs (Hz) and a period Ts (ms) for the set weld time Tw is then found from the set number of cycles Ns. The set frequency Fs and the period Ts are given as Fs=1/Ts and Ts=Tw/Ns, respectively (step B3).

Abstract: In order to provide a welding system capable of freely controlling dispersion and concentration of arc heat input at a groove face of base material and enable to ensure melting of the base material while restraining excessive weld heat input by carrying out a control of a heat input distribution of arc, in arc welding by a wire consumable electrode system, at a groove between welded members, a position of a weld torch or feed speed of a wire is periodically varied and welding is carried out by controlling a phase difference between the variation and an arc current characteristic when it is changed.

Abstract: In an electric arc welder for creating an arc welding process between a consumable electrode advancing through a contact tip and a workpiece, the welder including a power supply to create an arc current and arc voltage and having a first lead connected to the contact tip and a second lead connected to the workpiece, the improvement comprising dividing the contact tip into an upper tip section and a lower tip section with an insulator electrically isolating the sections, a first switch selectively shiftable to a conductive state connecting one of the power supply leads to said upper tip section, a second switch selectively shiftable to a conductive state connecting the one lead to the lower tip section and a switch operating network creating a first switch signal to shift the first switch to its conductive state and/or a second switch signal to shift the second switch to its conductive state to control the effective CTWD of the arc welding process.

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: In a method for high frequency pulse welding and an apparatus therefor, a highly directive arc can be obtained by eliminating the effect of the inductance of the welding cable, which tends to make the high frequency electromagnetic pinch force large. In a method and an apparatus for high frequency pulse arc welding which is performed by generating an arc between an inconsumable electrode or a consumable electrode arranged near a portion of a base metal to be welded and the base metal with main pulse current, when the main pulse current is shifted from ON to OFF, a reverse pulse current having a polarity opposite to the polarity of the main pulse is supplied between the electrode and the base metal to improve the stiffness (directivity) of the arc by making the rising and falling edges of the pulses steeper. A rail-car and a nuclear power plant obtained by the method are also provided.

Abstract: When a welding voltage is lowered, a pulse period is shortened or a peak current is reduced so that an average of a pulse frequency is not changed. Therefore, short circuit is regularly generated and a quantity of generated spatter is reduced. When the welding voltage is changed immediately before a melting drop separates from a tip of a wire, separation of the melting drop is predicted and the pulse period is ended. Due to the foregoing, a melting drop is regularly shifted at each pulse, and a quantity of generated spatter is reduced.

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 consumable electrode type arc welding method, when short circuit shift welding is conducted at the start of an arc in the process of pulse arc welding and also when an inclinations of a rise or fall is decreased in the case of starting an arc in the process of pulse welding and also when an inclination of a short circuit current is increased, short circuit, which irregularly occurs at the start of an arc, can be released in a short period of time and the arc can be stabilized early. When the generation of a magnetic arc blow is suppressed, it becomes possible to form proper welding beads. Due to the foregoing, the efficiency of welding work can be enhanced.

Abstract: An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage tenninal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the

Abstract: An EP output voltage to be outputted during a period of EP polarity is set so that a welding current becomes equal to or lower than a critical current level, and an EN output voltage to be outputted during a period of EN polarity is set at a level lower than the EP output voltage. This makes it possible to substantially equalize a wire melting rate in the period of EN polarity and that in the period of EP polarity with each other. Even at such a short arc length as causing frequent short circuiting, gas-shielded AC arc welding making use of a consumable wire can be still performed stably so that high wire melting rate, shallow penetration, convex weld reinforcement and the like, which are characteristic features of AC welding, can each be set selectively at a desired level or in a desired shape depending on the application.

Abstract: An arc welding machine is disclosed for providing a continuous feed electrode to a weld site. The arc welding machine includes a line frequency transformer having a primary winding, a first secondary winding, and a second secondary winding (e.g., an extension winding, a separate winding, etc.). The first secondary winding provides a welding power having a first voltage at a welding power output terminal. The second secondary winding provides a second welding power having a second higher voltage at an input terminal of a switch, the switch being controlled to provide a pulsed power at the welding power output terminal. According to one feature, the arc welding machine produces a pulsed power having a fixed pulse width and a fixed frequency, the fixed pulse width and fixed frequency being substantially free of operator adjustment.