A spatter detection method for accurately determining whether or not spatter has been generated when resistance spot welding is performed is provided. A spatter detection method including: a welding step for welding a plurality of welding materials by sandwiching parts to be welded of the welding materials between a pair of electrodes and then pressurizing the parts to be welded while simultaneously energizing the pair of electrodes; a calculation step for calculating an amount of expansion of the parts to be welded based on a pressurizing force and a stroke between the pair of electrodes; and a determination step for determining that the spatter has been generated when a magnitude of an inclination of an expansion amount waveform falls below a determination threshold, in which in the determination step, determination thresholds different from each other are applied to respective sections obtained by dividing a target period of the determination.

A nugget diameter estimation method of a welded material bonded by resistance spot welding includes: a reference welding process of bonding a test material while measuring an expansion amount of the test material; a nugget diameter measurement process of measuring a nugget diameter of the bonded test material; a relational formula determination process of determining a relational formula between the measured nugget diameter of the test material and the expansion amount of the test material; a main welding process of measuring an expansion amount of the welded material, and bonding the welded material through energization while pressurizing the welded material with the pair of electrodes; and a nugget diameter estimation process of estimating a nugget diameter of the bonded welded material using the expansion amount of the welded material and the relational formula.

A flawless aluminum resistance welding system includes a welding gun that includes a gun body to engage a first welding tip and a second welding tip with an upper panel and a lower panel of an object to be welded. The welding gun further includes: a pressing actuator to press the upper panel of the object at a high pressure by the first welding tip during spot welding, a welding transformer to supply a welding current for the spot welding, an air balance cylinder to adjust an air pressure to make the second welding tip in a no-load balance state, and a linear guide unit to guide the second welding tip in up and down directions. The welding gun has an equalizing function and a bidirectional pressing structure in which the second welding tip rises with a reaction force when the first welding tip presses the upper panel.

The invention relates to the welding robot controller system, which will instantly check that the welding at each welding point in the resistance welding robot cells is performed according to the correct welding parameters and will instantly inform the robot and the operator in case of a nonconformity detection.