Electrical circuit

Abstract

Abstract A METHOD AND APPARTUS FOR RESISTANCE WELDING CONTROL FOR SENSING THE CONTACT RESISTANCE AT THE WELDING POSITION, TERMINTING WELD CURRENT WITHIN A PREDETERMINED TIME RANGE AND AT A PREDETERMINED FRACTION OF THE VALUE OF THE CONTACT RESISTANCE IF SUCH IS REACHED WITHIN SAID TIME RANGE AND PROVIDING ALARMS INDICATIVE OF PRESENT WELD CONDITION AND IMPENDING DEGRADATION. THE CONTACT RESISTANCE IS DETERMINED BY DETECTING THE AMPLITUDE PEAK OF THE WELD CURRENT WAVEFORM AND THEREUPON CHARGING A STORAGE DEVICE AT A RATE PROPORTIONAL TO THE INSTANTANEOUS ELECTRODE VOLTAGE FOR A RELATIVELY SHORT INTERVAL INVERSELY PROPORTIONAL TO THE PEAK WELD CURRENT AMPLITUDE TO PRODUCE A PULSE OF HEIGHT PROPORTIONAL TO THE INSTANTANEOUS CONTACT RESISTANCE. WELD TERMINATION MEANS RESPONSIVE TO THE INSTANTANEOUS CONTACT RESISTANCE TERMINATES THE WELD CURRENT WHEN THE CONTACT RESISTANCE REACHES A PREDETERMINED FRACTION OF ITS PEAK VALUE OR AT LEAST WITHIN A SELECTED TIME RANGE. A PLURALITY OF TIMERS CAUSE THE WELD TERMINATION MEANS TO TERMINATE WELD CURRENT AT THE BEGINNING OF SAID RANGE IF THE CONTACT RESISTANCE IS LESS THAN SAID PREDETERMINED FRACTION OR AT THE END OF SAID TIME RANGE IF THE INSTANTANEOUS CONTACT RESISTANCE HAS NOT THEN REACHED SAID FRACTIONAL VALUE. ALARMS ARE ACTUATED TO INDICATE QUESTIONABLE OR DOUBTFUL PRESENT WELDS AND IMPENDING PROCESS DEGRADATION.

Inventors

• 👤 Peter W Vanderhelst

Bibliographic Details