Described herein are methods and system for welding, for example, girders. The method may include activating a homopolar generator. The method may include applying a force to two metal girders at a desired coupling joint. The method may include generating an electrical pulse using the homopolar generator and conducting the electrical pulse to the desired coupling joint to increase a temperature of the girders. The method may include forming a weld at the desired coupling joint attaching the two metal girders at the desired coupling joint. In some embodiments, the homopolar generator may include a radial bearing rotor including a rotatable shaft and a bearing assembly. The bearing assembly may include nonmagnetic bearings. The homopolar generator may include a field coil. The homopolar generator may include a brush actuation mechanism which when activated engages a plurality of brush devices to the radial bearing rotor.

Provided is an evaluation system including: an analog-to-digital converting section comprised of a programmable circuit and configured to convert an analog signal, the analog signal being acquired by a physical quantity acquiring section and indicative of a time-series change of at least one of (i) welding current, welding voltage, or load applied to pieces to be welded and (ii) a displacement, during welding, of a welding head; and an evaluating section configured to determine, based on a digital signal, whether or not the time-series change satisfies a predetermined condition, wherein configuration data for configuring the programmable circuit is arranged to be changeable by a user.

A resistance spot welding method of galvanized high-strength steel with good joint performance, in which three welding pulses are used within one spot welding schedule. The method includes applying a first welding pulse and a second welding pulse which are used for generating a nugget and suppressing the generation of liquid metal embrittlement (LME) cracks, respectively. The first welding pulse generates a nugget having a diameter of 3.75T.sup.1/2-4.25T.sup.1/2 in which T represents a plate thickness. The second welding pulse causes the nugget to grow at a rate less than a rate of growth during the first welding pulse. A third welding pulse, which is a tempering pulse, is applied for improving plasticity of a welding spot.

A method of controlling highly regulated power and frequency from a high frequency power supply system to provide a highly regulated power and frequency to a workpiece load where the highly regulated power and frequency can be independent of the workpiece load characteristics by inverter switching control and an inverter output impedance adjusting and frequency control network that can include precision variable reactor pairs with a geometrically-shaped moveable insert core section and a stationary split-bus section with a complementary geometrically-shaped split bus section and a split electric terminal bus section where the insert core section can be moved relative to the stationary split-bus section to vary the inductance of the variable reactors.

A metallic member bonding device includes a pressurizing unit, a current supply unit, and a deformation suppressing unit. The pressurizing unit pressurizes a first metallic member toward a hole portion of a second metallic member to press the first metallic member therein. The current supply unit supplies a welding current between the first metallic member and the second metallic member. The deformation suppressing unit suppresses deformation of one of the first metallic member and the second metallic member, the one member having a constituent metallic material with at least one of a proof stress and a melting temperature lower than that of the other member, the deformation being in a direction of a cross section crossing a direction of the press-in. Then, the deformation suppressing unit is provided in a region covering at least a plastic flow range in the press-in direction.

An example welding-type power supply includes: power conversion circuitry configured to convert input power to welding-type power, and to output the welding-type power via a welding-type circuit; a temperature sensor configured to measure a temperature of at least one component of the welding-type power supply; and stray current detection circuitry configured to detect stray welding-type current based on the measured temperature of the at least one component.

A flat, electrically and thermally conductive flat surface group is formed in the common connection region 32 of the secondary coil 13. The flat conductive surface group is directly and mechanically joined to the connecting surfaces of the first conductor plate 42, the second conductor plate 44, and the third conductor plate 46, respectively. The first conductor plate 42, the second conductor plate 44, and the third conductor plate 46 cover the entire common connection region 32. The annular first conductor plate 42 occupies the maximum area. The refrigerant can be circulated in the annular cavity provided inside the first conductor plate 42 to efficiently cool the whole.

Provided is a spot welding method capable of reliably welding a metal sheet laminate while suppressing occurrence of expulsion. In the spot welding method, a pulse current is applied in a first current application step and a second current application step by a DC chopping control method. In the DC chopping control method, a pulse waveform of the pulse current is generated by switching between current application and current application stop to a pair of electrodes 12 and 22 by a current switch 28, a peak current value of the pulse current in the first current application step is set to a value A1 equal to that of the pulse current in the second current application step, and a power of the pulse current in the first current application step is set to a value larger than that of the pulse current in the second current application step.

A bonding system is used for bonding a cover sheet to a core to form or repair a dual wall structure. The bonding system includes a plurality of bonding probes and controller circuitry. The bonding probes include a three dimensional (3D) contoured tip configured to align with a predetermined area of a 3D contoured cover sheet of a dual wall structure. The controller circuitry comprises processor circuitry and sensor circuitry. The sensor circuitry provides a location of an area of the 3D contoured cover sheet for bonding. The processor circuitry identifies a bonding probe having a contacting area that aligns with the 3D contour of the cover sheet in the location provided by the sensor circuitry.

A current source module for joining methods with current-generated heat support that includes a base body formed monolithically as a single component, having a first immovable attachment element for connecting a first joining tool and at least one formed first receiving space. In the first receiving space, a control element is disposed including a linearly movable second attachment element for connecting to a second joining tool, and in the first or additional receiving space a transformer unit for electrical supply is disposed. Furthermore, a welding gun is provided that includes such current source module, and a first joining tool formed as an immovable electrode arm, and a second joining tool formed as a movable electrode arm, wherein the immovable arm is connected to the first attachment element and the movable arm is connected to the second linearly movable attachment element, wherein the electrode arms include electrodes connected to the transformer.