Abstract: A weld gun includes internal, external and structural devices that dissipate heat generated at electrode tips without requiring a continuous external source coolant. The internal devices utilize heat pipes within the electrodes to transfer heat to secondary heat removal features. A heat capacity on the weld gun contacts external heat sinks to directly conduct heat away from the weld gun after a completed weld cycle. Alternatively, the heat sink, the heat pipe and the secondary heat removal features are combined structurally on the weld gun arm by forming the arm from a plurality of plates separated by an air gap.

Abstract: A multiple arm weld includes at least two weld gun arms where one arm retracts away from mating work pieces while at least one other arm remains operational, thus allowing a multiple arm weld gun to act as a single arm weld gun. Once one or more weld gun arms is retracted, the remaining weld gun arms may be repositioned with respect to the work pieces in a space not previously accessible to the multiple arm weld gun before retraction of an arm.

Abstract: The present invention relates to an improved resistance weld-based gun assembly for use in an electric welding system without a need for plant-provided air and water-cooling circulation systems. In one aspect of the invention, a resistance-based force controller measures the resistance of a secondary circuit of the weld gun, the combined resistance of the secondary circuit in parallel with the circuit formed by the workpieces and opposing electrodes when sandwiched between the electrodes, and calculates the resistance of the workpieces. The measured resistance is compared to a predetermined resistance and the sandwiching force of the electrodes incrementally adjusted until the resistance of the workpieces is acceptable. The invention also relates to a closed loop coolant system having a coolant line, a coolant contained within the coolant line, a heat exchanger, and a mechanical coolant pump. One possible pump comprises an elastic bladder dependent upon the state change of the coolant.