The welding equipment of the welding robot adopts an integrated welding tongs, and the welding transformer is installed behind the welding tongs, so the transformer must be as small as possible. For transformers with smaller capacity, 50Hz power frequency AC can be used, while for transformers with larger capacity, inverter technology has been used to change 50Hz power frequency AC into 600-700Hz AC, so that the volume of the transformer is reduced and lightened. After the voltage is transformed, it can be welded directly with 600-700Hz alternating current, or it can be rectified twice and welded with direct current. The welding parameters are adjusted by a timer. The new timer has been microcomputerized, so the robot control cabinet can directly control the timer without an additional interface. The welding tongs of spot welding robots usually use pneumatic welding tongs. The opening between the two electrodes of the pneumatic welding tongs is generally only two-stage stroke. Moreover, once the electrode pressure is set, it cannot be changed at will. In recent years, a new type of electric servo spot welding tongs has appeared, as shown in Figure 4. The opening and closing of the welding tongs are driven by a servo motor, and the encoder feedback, so that the opening degree of the welding tongs can be arbitrarily selected and preset according to actual needs. Moreover, the pressing force between the electrodes can also be steplessly adjusted.
This new electric servo spot welding gun has the following advantages:
1) The welding cycle of each welding spot can be greatly reduced, because the opening degree of the welding tongs is precisely controlled by the robot, and the robot can start to close when the robot moves between the points; and the welding tongs can start to close; Later, when the welding tongs are opened, the robot can move at the same time. It is not necessary to wait for the welding tongs to close after the robot is in place or the robot to move after the welding tongs are fully opened;
2) The opening degree of the welding tongs can be adjusted arbitrarily according to the condition of the workpiece, as long as there is no collision or interference, the opening degree is reduced as much as possible to save the opening of the welding tongs and the time occupied by the opening and closing of the welding tongs.
3) When the welding tongs are closed and pressurized, not only the pressure can be adjusted, but also the two electrodes are closed gently when closing, reducing impact deformation and noise.