GB1421997A - Temperature control in rolling mills - Google Patents

Abstract

1421997 Rolling mills WEAN UNITED Inc 1 Feb 1973 [2 March 1972] 5122/73 Heading B3M A system for controlling the temperature of a workpiece in a rolling mill including successive stands, comprises first and second coolant supply means along the path of the workpiece, means for computing the temperature of the workpiece at a point downstream of the first stand and producing a corresponding first signal, means comparing that signal with a signal representing the desired temperature at that point and supplying coolant from the first supply means to reduce any difference, means producing a third signal representing the measured temperature at the point, and means comparing the second and third signals and supplying coolant from the second supply means to reduce any difference. The Fig. shows the last stand R6 of a roughing train, a delay table 11, seven stands F1-F7 of a finishing train, and runout table 17. Also shown are a shear 15, high pressure descaling and cooling units 1, 2, 4, 5, 6, low pressure coolant units 3, 7, 8, 9, load cell 29, and X-ray device 16 measuring the thickness t 2 of the workpiece after finish rolling. The thickness t 1 on the table 11 is also measured, and the workpiece temperatures T R and T 2 downstream of the final roughing and finishing stands are measured by pyrometer. The temperature T 1 downstream of the shear may be measured, or computed in an analogue computer 49 having inputs representing T R , t 1 , the roughing train final speed V R , workpiece specific heat C V , and time, and produces a series of output signals CT 1 representing the temperature of successive portions A-E of the workpiece as they pass the point downstream of the shear. These are recorded in unit 50. An analogue computer 60 produces a computed value cT 2 of T 2 , from inputs representing t 1 , t 2 , C v , cT 1 , and the final workpiece speed V F . The correct cT 1 signal is derived from unit 50 by a switch operating amplifier 54 triggered by a signal from the load cell 29 and having an input from the unit 50 indicating which of A-E is effective and a signal on line 55 representing the effect of rolling on length. The output cT 2 is compared in amplifier 61 with the desired temperature T 2 AIM, and the difference fed to amplifier 62 which in response to rising error successively brings into operation the low pressure cooler 3 high pressure coolers 4, 5 and 6, and then starts and progressively increases the coolant flow from low pressure cooler 7 and finally starts and progressively increases the coolant flow from low pressure cooler 8. The flow control valves 33 of coolers 7 and 8 are controlled by amplifiers 37 having demand inputs and coolant flow feedback inputs. The measured temperature signal T 2 is compared with T 2 AIM in amplifier 65, and the error operates low pressure cooler 9, which is set to operate at the middle of its range by a bias signal fed to amplifier 43. An on/off signal on line 45 is also provided by computer 60. If the error output of amplifier 65 exceeds a predetermined value, amplifier 68 passes a signal to computer 60 to alter the cooling induced by amplifier 62 to bring the error within the correction scope of cooler 9. In an alternative version, coolers 6, 7, 8 and 9 are under the control of amplifier 65, and coolers 1-5 that of amplifier 62.