Provided is a current control method for resistance spot welding in which a plurality of overlapped metal plates are welded together by being sandwiched between a pair of electrodes and energized while applying pressure. The current control method includes sequentially acquiring an electrical resistance between the pair of electrodes during welding; sequentially calculating an expansion amount caused by the welding using a strain calculated from the pressure applied by the electrodes and a stroke of the electrode; sequentially calculating a computational nugget diameter by using the electrical resistance and the expansion amount, the computational nugget diameter being a diameter of a nugget formed during the welding; and sequentially determining a current to be applied between the pair of electrodes during the welding using a difference between the computational nugget diameter and a master computational nugget diameter calculated in master welding in which no gap exists between the metal plates and a nugget with a target diameter is obtained by the welding.

A resistance spot welding method includes sandwiching metal plates put on top of one another between a pair of electrodes and performing resistance spot welding sequentially on a plurality of welding points close to each other on the metal plates by performing a current application between the electrodes so as to join the metal plates to each other. A welding current value to form a welding nugget at a welding point to be subjected to the resistance spot welding second or later among the welding points is set to be higher than a first welding current value to form a first welding nugget at a first welding point to be subjected to the resistance spot welding first among the welding points.

This disclosure relates to weldability of steel alloys that provide weld joints which retain hardness values in a heat affected zone adjacent to a fusion zone and which also have improved resistance to liquid metal embrittlement due to the presence of zinc coatings.

A resistance spot welded joint of an aluminum material is obtained by joining a stack of a plurality of aluminum materials by spot welding. A nugget formed by the spot welding includes a solidified part of the aluminum materials and a shell having a different solidification structure from the solidified part. The shell is formed annularly in a cross-section of the nugget in a stacking direction of the aluminum materials. The solidified part and the shell are alternately arranged from an outer edge of the nugget toward a nugget central part.

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 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 programmable polarity module that permits rapid on-demand control of the polarities assigned to the welding electrodes retained on a welding gun is disclosed. The programmable polarity module is electrically connectable to the welding gun and a direct current power supply unit to provide direct current to the welding electrodes for exchange during spot welding. A first interchangeable polarity output lug and a second interchangeable polarity output lug of the programmable polarity module permit the polarities of the welding electrodes to be switched without having to electrically disconnect the module from the welding gun.

A resistance spot welding method able to form a welded joint having delayed fracture resistance, includes, in order, applying a pressing force P1 (kN) to the plurality of steel sheets by welding electrodes while supplying a supplied current I1 (kA), while applying the pressing force P1, supplying a current Ic (kA) during a cooling time tc (s), repeating two times or more a pressure force raising and lowering cycle of supplying a supplied current I2 (kA) to the welding electrodes while applying a pressing force P2 (kN) to the plurality of steel sheets by the welding electrodes during a pressing time tf (s), then immediately applying a pressing force P3 (kN) during a pressing time ti (s), applying the pressing force P2 during the pressing time tf, and releasing the pressing force and ending the supply of current, satisfying 0Ic<I1, 0.3I2/I1<1.0, P2/P12, tf0.2, P3<P2, and ti0.2.

This disclosure relates to weldability of steel alloys that provide weld joints which retain hardness values in a heat affected zone adjacent to a fusion zone and which also have improved resistance to liquid metal embrittlement due to the presence of zinc coatings.

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.