Medar, Inc.

Reno C Boilard

A method of controlling a resistance welder of the type having a weld controller provided with memory lookup tables, a source of AC electrical power coupled to a welding transformer through a switch operated by the controller and welding electrodes for delivering pulses of electrical energy to a workpiece to be welded. A first set of data is stored in a first one of the memory lookup tables which corresponds to a set of firing angles that are related to a set of DC current values representing the percentage of the maximum amount of DC current that can be delivered to the worpiece based on a particular power factor for the circuit. A second set of data is stored in the second memory lookup table which is similar to the data in the first memory except that stored current values are for portions of AC pulses of weld energy. In the case of the first memory, the stored values of the DC current are corrected values that bear a nonlinear relationship to the actual values of the DC current that is delivered to the workpiece. The method allows the user to select which of the two memory lookup tables are used, based on the confirguration the welder being employed.

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Windsor, Canada

Reno C Boilard