GB966990A - Improvement to screw position control in rolling mills - Google Patents

Abstract

966,990. Automatic thickness control systems. STEELWORKS AUTOMATION Ltd. Nov.26, 1962 [Dec. 6, 1961], No. 43771/61. Heading G3R. The invention relates to a servo positioning system for the screw-down in rolling mills, and provides for corrections introduced by the operators manual control, and an automatic gauge control. As shown Fig. 2, a synchro link S1, S2 supplies a control signal to motor M1 through amplifier A1 to drive the screws into correspondence with the position indicator 1234. Differential synchro S3 provides for zero adjustment (i.e. zero gap corresponds to zero position of S1). Operators control. During rolling, operators ' override the servo system directly controlling the screw-motor to provide rapid correction for e.g. roll wear, or thermal expansion. The resulting error signal from S2 is fed back over switch SW1 down to amplifier A2 and motor M2 to realign synchro S1 with S2, thus incorporating the operators corrections in the system. A. G. C. When the mill is operating with automatic gauge control of the thickness, the A. G. C. corrections are not required to be retained in the system after each item has been rolled. To this end, the A. G. C. corrections as indicated by the error signal from S2 are "recorded" in a further synchro S4, so that the combined output of S2 and S4 is zero. Thus when a manual correction, which is retained in the system, is to be made to alter the angular position of M2 and S2, SW1 is set to the upper position. The A. G. C. signal shift of S2 is cancelled by the output of S4, and only the operators correction is transferred to S1. After rolling each item S2 is connected to M1 to reset the screws to their initial position plus the operators modifications, while S4 is connected to A3 and resets itself to zero.