A spot welding apparatus includes a spot welding gun and a welding gun control apparatus. The welding gun control apparatus includes a pressurizing force control part controlling the pressurizing force, a position control part controlling the position of at least one electrode, and a determination part determining whether or not the welding is performed in a normal state. The position control part controls an electrode drive motor so as to hold the electrodes, after the supply of the electric current is started, at positions when the initial pressurizing force is applied before the electric current is supplied. The determination part acquires the pressurizing force and determines whether or not the welding is performed in a normal state based on change tendency in the pressurizing force.

A resistance spot welding system includes a calculation unit that calculate and store a time variation of an instantaneous amount of heat generated, a division unit that divides a current pattern into a plurality of steps and stores a time variation of the instantaneous amount of heat generated and a cumulative amount of heat generated for each step as a target value, and an adaptive control unit that starts welding upon subsequent actual welding using, as a standard, a time variation curve of the instantaneous amount of heat generated that is stored as the target value, and adjusts welding current and voltage during welding, when a time variation amount of an instantaneous amount of heat generated deviates during any step from the time variation curve by a difference, so as to compensate for the difference during a remaining welding time in the step.

A resistance spot welding device for welding at least two overlapping steel sheets held between a pair of welding electrodes is provided. The resistance spot welding device includes the pair of electrodes, an electrode force gauge that measures an electrode force, and a controller that controls an electric current supply to the electrodes according to the electrode force measured by the electrode force gauge. The controller controls the electric current such that the electrode force F measured by the electrode force gauge after the start of the electric current supply is adjusted to a prescribed value.

A resistance spot welding method of squeezing a predetermined sheet combination by a pair of electrodes and passing a current while applying an electrode force to join the sheet combination includes: performing test welding; and performing actual welding after the test welding, wherein in each of the test welding and the actual welding, a current pattern is divided into two or more steps including a first current passage step and a second current passage step subsequent to the first current passage step, and, in the actual welding, a current that causes no expulsion is selected to perform welding by constant current control in the first current passage step, and adaptive control welding is performed from the subsequent second current passage step onward.

A welding process for the welding of aluminum includes a force sensor measuring a force between two welding electrodes on aluminum elements to be welded and transmitting its measured values to a welding control. Until the elapse of a set welding time, the welding control calculates and stores at least one absolute value and/or at least one increase in the measured force. The welding control compares the measured absolute value and/or the increase in the measured force with a reference value and/or a reference curve and calculates a control deviation from the comparison. After the elapse of the set welding time, the welding control subjects the welding electrodes to a constant current during a welding time extension that follows the set welding time, dependent on a magnitude of the control deviation that is measured at the point in time of the elapse and/or during the set welding time.

A method and an apparatus detects pressure changes at servo gun tips of a robotic welding system having a servo gun with a movable tip and an opposed fixed tip configured to weld a part. The method and apparatus observe a tip deflection value and convert the value to a current pressure value using a pressure estimator. The current pressure value is compared to a benchmark pressure value to detect any difference.

The present disclosure relates to a method for controlling a spot welding arrangement, the method comprising the steps of moving a welding tip portion of the spot welding arrangement between a first and a second position by applying a force to the welding tip portion; determining a distance moved between the first and second positions; determining a type of welding yoke connected to the spot welding arrangement based on the determined distance and the applied force; and controlling settings of the spot welding arrangement based on the welding yoke connected to the spot welding arrangement.

A resistance spot joining method includes: a protrusion forming step of forming a protrusion on at least one of a first workpiece and a second workpiece by pressing the first and second workpieces with a first load by a pressing shaft and a pressing member; a load reducing step of reducing an area of contact between the first and second workpieces by reducing a pressing force from the pressing shaft and the pressing member such that a second load is applied to the first and second workpieces; a current applying step of applying a current to the first and second workpieces; and a joining step of joining contact interfaces of the first and second workpiece to each other by pressing the first and second workpieces with a third load.

A solid state welding apparatus comprises a pair of compression bars, a pair of electrodes disposed around the pair of compression bars, respectively, and a controller. The controller controls the pair of compression bars to cause a first load to act on each of the first and second workpieces, subsequently controls the pair of compression bars to subject compressive force to load removal to cause a second load smaller than the first load to act on the first and second workpieces, and subsequently passes a current through the pair of electrodes to remove an impurity on a metal surface.

A solid state welding apparatus comprises a pair of compression bars, a pair of electrodes disposed around the pair of compression bars, respectively, and a controller. The controller passes a first current through the pair of electrodes while controlling the pair of compression bars to cause a first load to act on each of first and second workpieces to bring the workpieces into contact with each other, and subsequently passes a second current larger than the first current through the pair of electrodes while controlling the pair of compression bars to cause a second load to act on each of first and second workpieces.