Automatic gauge control system for rolling mills

Claim 1

IN APPARATUS FOR PERFORMING WORK UPON A MOVING STRIP BY A PAIR OF ROLLS BETWEEN WHICH SAID STRIP IS ADVANCED; GAUGING MEANS POSITIONED ALONG THE PATH OF SAID STRIP AT SOME DISTANCE FROM THE BITE OF SAID ROLLS FOR MEASURING THE THICKNESS OF THE STRIP AFTER IT LEAVES THE ROLLS AND FOR PRODUCING AN ELECTRICAL SIGNAL RESPRESENTATIVE OF THE THICKNESS BEING MEASURED; SAID GAUGING MEANS MEASURING THE THICKNESS OF THE STRIP AT A TIME INTERVAL AFTER REDUCTION THEREOF AND THEREBY INTRODUCING A TRANSPORT DELAY IN THE CONTROL SYSTEM; MEANS FOR GENERATING A FIRST ELECTRICAL SIGNAL REPRESENTATIVE OF THE RATE OF CHANGE OF ROLL SEPARATING FORCE; FIRST CIRCUIT MEANS HAVING A TIME CONSTANT APPROXIMATELY EQUAL TO ONE HALF SAID TRANSPORT DELAY FOR CONVERTING SAID FIRST SIGNAL TO A DECAYING SIGNAL HAVING A GENERALLY EXPONENTIAL WAVE FORM; MEANS FOR GENERATING A SECOND ELECTRICAL SIGNAL REPRESENTATIVE OF THE RATE OF CHANGE OF SEPARATION OF SAID ROLLS; SECOND CIRCUIT MEANS HAVING A TIME CONSTANT APPROXIMATELY EQUAL TO ONE HALF SAID TRANSPORT DELAY FOR CONVERTING SAID SECOND SIGNAL TO A DECAYING SIGNAL HAVING A GENERALLY EXPONENTIAL WAVE FORM; AND MEANS FOR SUMMING SAID EXPONENTIAL SIGNALS AND COMPARING THE SUM THEREOF WITH THE ELECTRICAL SIGNAL FROM SAID GAUGING MEANS, THE SIGNAL OUTPUT FROM SAID LAST MENTIONED MEANS SUBSTANTIALLY ELIMINATING THE EFFECTS OF SAID TRANSPORT DELAY AND THEREFORE A SIGNAL USEFUL IN SAID CONTROL SYSTEM FOR CONTROLLING GAUGE AUTOMATICALLY.