GB692267A - Improvements in and relating to the production of metal and other sheet and strip - Google Patents

Abstract

692,267. Automatic control systems; thickness. BRITISH IRON & STEEL RESEARCH ASSOCIATION. June 27, 1951 [July 5, 1950], No. 16787/50. Class 38 (iv). [Also in Groups V and XXII] A method of manufacturing sheet or strip material by rolling or by drawing through adjustable aperture dies, comprises adjustment of the roll or die setting with any variation in separating force so that an increase or decrease in separating force is accompanied by a decrease or increase respectively in roll or die setting which is equal to the change in separating force divided by the mill spring, whereby the thickness of the issuing sheet or strip is maintained substantially constant. A rolling mill comprises pass adjusting, fluid-operated rams 14 bearing on members 16 carrying electric resistance strain gauges 17, whose resistance varies with changes in the roll separating force. Meters 18 mounted at each end of the rolls between roll chocks 11 and the roll frame 13 respond to changes in the roll setting and comprise a rod 19 engaging cantilever arms 22 carrying electrical resistance strain gauges 23, whose resistance changes with changes in the roll setting due to flexing of the arms 22 by movement of the rod 19. A water-cooling jacket 24 surrounds the meter housing 20. The strain gauges 17 and 23 are incorporated in temperature compensated Wheatstone bridge networks 25, 26 respectively, whose amplified and demodulated outputs are combined in opposition and fed to a coil 32 wound on a spring-loaded core 33 movable in the field of a permanent magnet 34. Any change in separating force occasioned by a variation in outgoing thickness from the desired value will result in an out-of-balance voltage in the coil 32 causing a movement of the piston 35 of a differential fluid valve 36 controlling supply of low pressure fluid to one side or the other of a double-acting piston 38, the pressure acting on said piston being modified by a fluid intensifier 39 connected to the rams 14, thereby causing a change in roll setting in a sense to restore the out-ofbalance voltage to zero and maintain the desired relationship between separating force and roll setting. The method may be applied independently to each of the roll adjusting mechanisms which act on the two ends of the roll, to ensure that the thickness of the two edges of the strip remain equal to one another. Specification 626,206, [Group XXXVI], is referred to. The Provisional Specification refers to Specification 681,373.