Patent ID: 6013891
Filing Date: 2000-01-11
Classification: B23K

Abstract:
A resistance welding apparatus, comprising:a consumer including an electrode, the electrode being operable to be supplied with electrical current so as to perform a welding operation upon a workpiece;a transformer having an output side connected to the consumer;a plurality of welding energy stores connected to an input side of the transformer for supplying current from each said energy store to the consumer, the welding energy stores all supplying current of the same predetermined polarity;an additional energy store connected to the input side of the transformer for supplying current to the consumer;a charging device coupled to the welding energy stores and to the additional energy store;switching devices coupled with the welding energy stores and the additional energy store so as to enable a selected one of the energy stores to be at least partially discharged to supply current to the consumer independently of the other energy stores;a sensor connected between the transformer and the consumer and operable to detect current flowing to the consumer; anda control device connected with the switching devices and operable to trigger the switching devices between two charging cycles for directly successive supply of current pulses from each of the energy stores to the consumer, the control device being connected with the sensor so as to detect the current flowing to the consumer from the additional energy store, the control device being operable to control operation of the welding energy stores based on the current detected by the sensor;the additional energy store supplying current having a polarity opposite to the predetermined polarity of the welding energy stores, whereby the current pulse from the additional energy store at least partially demagnetizes the transformer.