Patent GB-884737-A (GB)
Title: Apparatus and method for detecting and regulating for roll deflection on a rolling mill
IPC: G01B13/16
Filed: 1958-07-08
Abstract: 884,737. Automatic control systems for rolling mills. YOUNGSTOWN RESEARCH & DEVELOPMENT CO. July 8, 1958 [May 9, 1958], No. 21833/58. Class 38 (4). [Also in Group XXII] Bowing of a roll in a metal rolling mill with or against the direction of travel of the metal is automatically maintained constant by controlling a driving motor in dependence on the length of the gap between a fixed point and the surface of the roll. In a metal strip rolling mill of the reversing type, the strip 9, Fig. 1, passes between small work rolls 2 and 3 which are frictionally driven by backing rolls 4 and 5 respectively. Jets of air under pressure from a source 20 are directed on to opposite sides of lower work roll 2 from nozzles 25 and 26 located centrally in safety bars 27 and 28 so that any bowing of the roll alters the relative spacing between the roll and the two nozzles thereby creating different pressures in conduits 11 and 12. Such a pressure difference operates a diaphragm 36 to move a pivoted hydraulic jet 43 relative to fixed conduits 49, 50 so that an hydraulic servomotor 51 acts in the sense necessary to eliminate bowing by adjusting a rheostat 17 which, as shown in Fig. 3, controls the excitation of a generator 18 supplying D.C. motors 6 and 7 driving backing rolls 4 and 5 respectively. Forward tension on the strip is provided by a pair of motors 61, 62 coupled through a clutch 104 and driving a wind-up reel 8. Back tension is provided by a drag generator 106 associated with a feed reel 10. During reverse runs reel 10 is driven by motors 105, 106 coupled through a clutch 107, and machine 62 associated with reel 8 serves as a drag generator. Manual regulation of the mill to eliminate bowing of the roll as indicated on a differential pressure gauge is referred to. Bowing of the roll may alternatively be detected by a single jet of air, pressure changes of which adjust the pivoted hydraulic jet against the action of a spring. Diaphragm 36 or mercury in a U-tube responsive to the difference in pressure between conduits 11 and 12 may position the core of a differential transformer output from which operates an A.C. servomotor system adjusting rheostat 17. Instead of the pneumatic system transformers or inductances, mounted so that bowing of the roll alters air gaps in their magnetic circuits may control an A.C. servo motor system adjusting rheostat 17. Rheostat 17 may control the excitation of the generator supplying the motors driving the wind-up reel instead of or as well as controlling the excitation of generator 18. If the work rolls bow in opposite directions the excitation of separate generators supplying the motors driving the backing rolls may be adjusted in opposite senses by rheostat 17 or a separate rheostat controlling each generator may be arranged to respond to bowing of each work roll. Application to mills having different numbers of rolls between the backing rolls and to tandem mills having several sets of rolls is described. In some cases the drive to one backing roll only is controlled.