An arc welding method preforms reciprocating wire feed so as to alternately perform forward feed and reverse feed. The arc welding method includes a normal arc welding step, a normal short circuit welding step, and an abnormal arc welding step. In the abnormal arc welding step, a short circuit state occurs at a second time point, which is before a lapse of a second period from a first time point at which an arc state occurs. Further, in the abnormal arc welding step, the reciprocating wire feed continues until a third time point after a lapse of a first period from the second time point. At the third time point, the reciprocating wire feed is stopped and the abnormal arc welding step is completed. From the third time point, the welding wire is decelerated and the reciprocating wire feed is restarted.

A system and method to correct for height error during a robotic additive manufacturing process. One or both of an output current, output voltage, output power, output circuit impedance and a wire feed speed are sampled during an additive manufacturing process when creating a current layer. A plurality of instantaneous contact tip-to-work distances (CTWD's) are determined based on at least one or both of the output current, output voltage, output power, output circuit impedance and the wire feed speed. An average CTWD is determined based on the plurality of instantaneous CTWD's. A correction factor is generated, based on at least the average CTWD, which is used to compensate for any error in height of the current layer.

In thin sheet welding, when a heat input amount relative to a sheet thickness is too large, a welding defect such as a deviation from aim due to occurrence of a strain or burn through may easily occur. When a welding current is decreased to reduce the heat input amount, there is an issue in which an arc tends to become unstable. In arc welding in which short-circuit and arcing are repeated, first heat input period (Th) and second heat input period (Tc) having a heat input amount less than that of first heat input period (Th) are periodically repeated and a welding current during an arc period in second heat input period (Tc) is decreased to extinguish the arc. This reduces the heat input amount into a welding object and suppresses burn through or a strain upon welding, while making the arc stable.

In thin sheet welding, when a heat input amount relative to a sheet thickness is too large, a welding defect such as a deviation from aim due to occurrence of a strain or burn through may easily occur. When a welding current is decreased to reduce the heat input amount, there is an issue in which an arc tends to become unstable. In arc welding in which short-circuit and arcing are repeated, first heat input period (Th) and second heat input period (Tc) having a heat input amount less than that of first heat input period (Th) are periodically repeated and a welding current during an arc period in second heat input period (Tc) is decreased to extinguish the arc. This reduces the heat input amount into a welding object and suppresses burn through or a strain upon welding, while making the arc stable.

A control method for gas-shielded arc welding includes providing a normal arc period in which the welding current is maintained at a setting current Icc set in advance, and providing a separation control period after the separation timing of the molten droplet is detected in the normal arc period, the separation control period including a current decreasing section, a current maintaining section, and a current increasing section. In the separation control period, at least one of the following controls for preventing a short circuit is performed: control of an output voltage, control of a feeding speed, and control of a gas ratio.

A control method for gas-shielded arc welding includes providing a normal arc period in which the welding current is maintained at a setting current Icc set in advance, and providing a separation control period after the separation timing of the molten droplet is detected in the normal arc period, the separation control period including a current decreasing section, a current maintaining section, and a current increasing section. In the separation control period, at least one of the following controls for preventing a short circuit is performed: control of an output voltage, control of a feeding speed, and control of a gas ratio.

Welding is performed by alternately switching a pulse arc welding period (where welding is performed by forward feeding a welding wire by a rotation for the forward feeding of a push side feeding motor and a rotation for the forward feeding of the pull side feeding motor and feeding a peak current and a base current) and a short-circuiting transition arc welding period (welding is performed by forward/backward feeding the welding wire by the rotation for the forward feeding of the push side feeding motor and a rotation for the forward/backward feeding of the pull side feeding motor and feeding a short-circuiting current and an arc current). During the short-circuiting transition arc welding period, a forward feeding peak value Wsp and/or a backward feeding peak value Wrp of a pull feeding speed Fw are compensation-controlled based on a wire storage amount of an intermediate wire storage.

Systems and methods to provide welding-type arc starting and stabilization with reduced open circuit voltage are disclosed. An example welding-type power supply includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to: control the power conversion circuitry to output a voltage pulse at a first voltage; determine whether the power conversion circuitry outputs current during the voltage pulse; in response to determining that there is less than a threshold output current during the voltage pulse, control the power conversion circuitry to turn off an output or output a second voltage that is less than the first voltage; and in response to determining that the power conversion circuitry outputs at least the threshold output current during the voltage pulse, control the power conversion circuitry to output the welding-type power.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.