Abstract: An actuator assembly for a welding gun is provided that has at least three positions in the example. The actuator assembly includes separate working and retract actuators. The working actuator includes a working rod movable between first and second positions. The retract actuator includes a retract rod independently movable relative to the working rod between third and fourth positions. The retract actuator is external to and non-concentrically arranged relative to the working actuator in the example shown. Actuation of the working and retract actuators is coordinated to provide at least three positions while enabling the actuators to be changed or modified independently from one another. A latching device is configured to selectively interlock the working and retract actuators to one another automatically in response to movement the working rod from the first position to the second position.

Abstract: An actuator assembly for a welding gun is provided that has at least three positions in the example. The actuator assembly includes separate working and retract actuators. The working actuator includes a working rod movable between first and second positions. The retract actuator includes a retract rod independently movable relative to the working rod between third and fourth positions. The retract actuator is external to and non-concentrically arranged relative to the working actuator in the example shown. Actuation of the working and retract actuators is coordinated to provide at least three positions while enabling the actuators to be changed or modified independently from one another. A latching device is configured to selectively interlock the working and retract actuators to one another automatically in response to movement the working rod from the first position to the second position.

Abstract: A method and apparatus for resistance spot welding aluminum comprises polishing the electrode tips periodically after a number of welds. During the spot welding, a coating or dust builds up on the electrode tips and this has been generally assumed to be pure aluminum. However, it has been found that the coating or dust is aluminum oxide which is nonconductive. Consequently, when power is applied to the electrodes there is a slight spitting or explusion at the electrode tips which are in contact with the aluminum surfaces. The electrodes thus become pitted or arced out after a few welds. To overcome this problem, the electrode tips are polished intermittently after a predetermined number of welds. This can be accomplished by a polishing wheel which is moved between the electrodes when they are in an open position.