Fundamental Study of Roll Eccentricity Control using the Correlation method. Control of Hydraulic Screw Down Apparatus. 1st report.

BISRA GAGE METER plate thickness control method is currently main stream in rolling mill hydraulic screw down apparatus. By this method, precise plate thickness control was established.But, this method is known to worsen plate thickness accuracy by amplification of roll eccentricity effect which is an inner disturbance in hydraulic servo loop of screw down control.For this situation, at present, the method of fourier analysis of roll separating force to detect roll eccentricity vector is attempted.Despite this, the control equipment is said to be apt to become complicated regarding at gain and phase adjustment for analog outputting.We devised a new correlation method for roll eccentricity detection, consideringthat roll eccentricity has periodic signal synchronization with roll revolution, in contrast with input plate thickness variation that is random in nature.Further, both digital and analog methods of correlation analysis are compared. Latter method which uses SIN and COS two reference signals is proven to be superior to the former.As roll eccentricity control method (elimination method) two types are studied.The first is command method, and the second is feedback method which lessens rolling mill stiffness by a control scheme, for roll eccentricity frequency only.The latter feedback method is proven to have sufficient control ability.By these studies, an economical analog correlation type roll eccentricity eliminator with high performance was developed.