GB1317750A - Continuous casting control system using vessel pressurization - Google Patents

Abstract

1317750 Continuous casting USS ENGS & CONSULTANTS Inc 23 July 1970 [25 July 1969] 35818/70 Heading B3F [Also in Division G3] In a continuous casting system in which molten metal flows from the bottom of a vessel into a mould, the level in the latter is maintained constant by automatic control of the withdrawal rate of the casting in dependence on the level, and a valve controlling the supply of pressure gas to the vessel is automatically controlled in dependence on the volume cast to maintain a constant effective head in the vessel. In Fig. 1, a vessel 2 containing molten metal is closed and evacuated through a conduit 10 and then suplied with gas through a conduit 70 from a pressurized source 68 to maintain a constant effective head when a gate 8 is opened and the metal flows out to continuous casting moulds such as 14. The level in mould 14 is automatically maintained constant by a detector 20 which controls a speed regulator 24 for a motor 26 driving pinch rolls 16 withdrawing the casting. The signal from a tachometer generator 28 representing the rate of withdrawal is applied to a potentiometer 34 set to correspond with the cross-section of the casting so that a signal representing the volume cast is combined in an integrator 38 with similar signals from potentiometers 34<SP>1</SP>-34<SP>111</SP> representing volumes cast in other moulds (not shown). The output of integrator 38 is modified by a diode function generator 42 to correspond to the pressure required in the vessel to maintain a constant effective head. This required pressure signal is compared with an actualpressure signal from the transducer 48 and any difference is effective through a proportional controller 58 and actuator 64 to adjust a valve 66 so that the required pressure is obtained. Signals representative of the casting rates are also applied to potentiometers 36-36<SP>111</SP> so that deviations of the average rate of casting from a desired rate set at 44 are applied through a PI controller 46 to controller 58 to modify the pressure in vessel 2 so that a desired rate of casting is maintained. If the pressure in vessel 2 should exceed a value determined by a potentiometer 52, a relay 56 is operated to disable control of valve 66. When gate 8 is shut, a switch 60 operates to close valve 66. In a modification, the signal representing volume cast is derived from load cells responsive to the total weight of vessel 2 and a potentiometer set to allow for the tare weight.