This invention is related to machines for spot welding aluminum, and more particularly to such a machine having a pair of shunts connected between the electrodes and the transformer in a close, side-by-side relationship to reduce the reaction normally developed when the electrodes are fired.
Spot welding machines have long been employed for welding steel. However, a special problem arises when such machines are employed for welding aluminum because low resistance aluminum requires two to three times the current required for steel. Usually 440 voltage is supplied to a transformer which reduces the electrode voltage to about 7 volts with an amperage build-up of approximately 30,000 amps. A U-shaped low reactance connection is necessary to accomodate the high amperage welding current. When such amperage is applied to the electrodes, a magnetic force build-up tends to drive conventionally arranged shunts apart as the transformer is fired.
Such a reaction not only reduces the life of the machine, but results in considerable current loss.