ARTICULATED ROBOT CARRYING AN ELECTRIC RESISTANCE WELDING HEAD WITH ELECTRODES LOCATED ON THE SAME SIDE ; CORRESPONDING METHOD OF RESISTANCE ELECTRIC WELDING ON A COMPONENT TO BE WELDED

It is described an electric resistance welding head with electrodes (3, 4) located on the same side, which comprises a support structure (1), an electric transformer, a ground electrode (3) and a welding electrode (4). The ground electrode (3) and the welding electrode (4) have respective main axes parallel to and spaced from each other and said electrodes (3,4) are movably-mounted with respect to said support structure (1) along the respective main axes. An elastic device is operatively interposed between the ground electrode (3) and the support structure (1) and a detecting device for detection of the load of the elastic device is associated to the elastic device. The head comprises also one or more electronic units for controlling the robot carrying the head and for controlling the welding head, wherein said one or more electronic control units are configured for controlling the movement of the robot in order to move an end portion of the ground electrode (3) in contact with a component to be welded. The aforementioned one or more electronic control units are also configured for causing increase of the load of the elastic device until stopping the movement of the robot when the load of the elastic device reaches a predetermined threshold value and for actuating the actuator (12) to advance the welding electrode (4) through a predetermined length, until reaching a predetermined position with respect to the support structure (1). Once reached the predetermined position of the welding electrode (4), the electronic control unit is also configured for continuing to actuate the actuator (12) for pushing the welding electrode (4) in contact with the component to be welded, controlling current absorption of the electric motor as an index of the force applied by the welding electrode (4) to the component. Finally, after reaching a predetermined value of said force, the aforementioned one or more electronic units are configured for supplying electrical current to said electrodes (3, 4) by means of said electric transformer for executing a resistance electric welding on said component.