GB1346878A - Rollmill control system - Google Patents

Abstract

1346878 Electric correspondence control systems WEAN UNITED Inc 6 Sept 1972 [7 Oct 1971] 41398/72 Heading G1N The roll gap of a rolling mill is set up to produce a desired strip thickness based on a noload roll gap and an estimated mill stretch, and the actual mill stretch is calculated from the roll pressure, the difference between the estimated and calculated stretch being used to change the roll gap in order to produce the desired strip thickness. As shown, each of two housings 9 supports work rolls 11, 12, back-up rolls 13, 14 and chock assemblies 18, 19, the upper chock assemblies 18 being set by screw 21 adjustable by motor 23, and the lower chock assembly 19 being adjustable by a hydraulic piston cylinder arrangement 27 controlled by a servovalve 29. A control unit 53 is fed with the known parameters of the rolling mill and the product to be rolled and develops a first signal representing the initial roll gap, which is fed via position control 24 to motor 23, and a second signal representing the predicted mill stretch. During rolling, a load cell 42 associated with the upper back-up chock 18 measures the rolling load and its output P is combined at 49 with a signal M m representing the known modulus of the mill to produce a signal P/M m representing the actual mill stretch. This is compared at 32 with the predicted mill stretch signal from unit 53 to produce a signal #P/M m representing the change in mill stretch, which is used to cause servovalve 29 to adjust the roll gap accordingly, via the piston cylinder arrangement 27. A feedback loop for the adjustment of the lower rolls 12, 14 is provided by a displacement transducer 28.