Abstract: A resistance-type welder employing a three phase, pulsed power supply and a pair of opposed electrodes which a workpiece may be clamped under pressure, includes a microcomputer based control system for allowing precise selection and control of welding sequences such as the duration during which the workpiece is clamped, the duration during which current is supplied to the electrodes and the duration during which the workpiece remains clamped between the electrodes after current flow is terminated. A plurality of switchable input devices allows data corresponding to a plurality of process variables to be input to a random access memory. A central processor enabled by a manually operable control switch produces control signals for operating a control and firing circuit in accordance with programmed instructions and the data stored in the random access memory in order to control each step in a welding cycle for precise time periods.

Abstract: A power supply for a pulse type electrical resistance welder includes an A.C. source of electrical power, a firing circuit for delivering spikes of current to a pair of welding electrodes and a precharging circuit for precharging the firing circuit with a quantity of electrical energy sufficient to produce satisfactory welds in the first cycle or first few cycles of power. The precharging circuit is controlled by control circuit which includes a thumb wheel switch for presetting the voltage to which the firing circuit is to be precharged. A relay circuit automatically disconnects the precharging circuit from the firing circuit before the latter discharges its energy to the welding electrodes. A safety circuit is provided for automatically discharging the firing circuit in the event of a power failure.

Abstract: A resistance-type welder employing a pulsed power supply and a pair of opposed electrodes between which a workpiece may be clamped under pressure, includes a microcomputer based control system for allowing precise selection and control of welding sequences such as the duration during which the workpiece is clamped, the duration during which current is supplied to the electrodes and the duration during which the workpiece remains clamped between the electrodes after current flow is terminated. A plurality of switchable input devices allows data corresponding to a plurality of process variables to be input to a random access memory. A central processor enabled by a manually operable control switch produces control signals for operating a control and firing circuit in accordance with programmed instructions and the data stored in the random access memory in order to control each step in a welding cycle for precise time periods.