PROCEDE ET APPAREIL POUR ETALONNER UN SYSTEME POSITIONNEUR DE CYLINDRE

1312662 Automatic control of rolling WESTINGHOUSE ELECTRIC CORP 15 May 1970 [27 May 1969] 23597/70 Heading G3R A rolling mill control system of the type having screwdown position control for the stands is provided with means to periodically determine the mill spring modulus for one or more of the stands, to compare this modulus with a previously determined modulus for that stand and to initiate alarm and/or corrective action should the result of the comparison indicate a change in modulus beyond certain limits, resulting from a faulty component in the control for that stand. The invention is applied to a known on-line digital computer control system shown in Fig.1, in which the computer is programmed to store the value of the modulus for each stand and to periodically determine the modulus, for example after a shut-down or a change of work rolls, by adjusting the rolls to obtain two pairs of roll force and screwdown position values on the linear portion of the mill spring characteristic, Fig.2, (not shown). A change in the modulus due to a faulty component, stated to be most likely the load cell 26, is used to initiate the following actions:- (1) alarm the operator to turn off the gauge control for the stand and any roll force gauge control operation for the stand by the computer 12, if the modulus has changed by more than Π30%. (2) alarm the operator to check the load cell 26 and position detector 24 if the change is more than Π10%. In addition the roll force feedback signal is adjusted by the computer in dependence on the value of the change limits Π10%. (3) adjust the roll force feedback signal by a factor equal to the ratio of the present to the previous modulus, if the change is more than Π3% (no adjustment is made if the change is within Π3%). Typical computer control programmes to effect the above procedure are described. Fig.3 and 4, (not shown), which programmes also provide information to obtain the calibration offset, which is added to the screwdown position to obtain the unloaded roll opening of the stand, and the roll eccentricity deadband.