Patent GB-760593-A (GB)
Title: Improvements in or relating to metering of molten metal by weight
IPC: B22D39/04
Filed: 1953-11-05
Abstract: 760,593. Ingot-casting machines. REPUBLIC STEEL CORPORATION. Nov. 5, 1953 [Nov. 29, 1952], No. 30604/53. Class 83 (1). [Also in Groups XXXV, XXXVIII and XL (c)] An apparatus for controlling pouring of molten metal from a ladle comprises means to detect reductions of weight of the loaded ladle during pouring, means for starting the pouring and means for automatically stopping the pouring when a predetermined weight reduction is detected. The apparatus shown for regulating the flow into moulds in accordance with a predetermined programme, comprises a resistancebridge weighing-cell 55 sensitive to the ladle weight in a self-balancing circuit, Fig. 2, the balancing-motor 107 of which drives a tachogenerator 190 giving an output proportional to the pouring rate, and the tapping-point of potentiometer 123 giving an output proportional to the total amount of metal poured from the ladle. The tachogenerator output is fed with an opposing voltage derived from one of a series of rate potentiometers 205-207 (the outputs of which correspond to pouring rates suitable for the initial, main and final stages of pouring an ingot), to a pair of relay-circuits, one responsive to positive and the other to negative inputs. These operate relays 156, 155 respectively to energize solenoids 27, 26 to position to threeway valve 38, supplying hydraulic-pressure from pump 22 to one or other side of piston 28 controlling the position of flow-valve 12, so as to adjust the flow-rate until the tachogenerator output equals a value set by the rate potentiometer. The appropriate rate-potentiometer is selected, in accordance with the weight of metal already poured from the ladle into a mould, by a pair of relays 212, 213 in the outputs of circuits 202, 203, responsive to positive inputs. During pouring of the first ingot the common inputvoltage thereto is the difference between a preset voltage developed across one of the resistors 139 &c. which corresponds to the desired ingotweight, and the output of potentiometer 122 corresponding to the weight already poured. Preset bias-voltages corresponding to suitable fractions of the ingot-weight are also applied to the inputs so that relays 212, 213 are successively released to select different rate potentiometers when the metal reaches the levels in the ingotmould, marked in Fig. 1. The voltage to circuits 202, 203 is also supplied to circuit 226, responsive to positive inputs, to release relay 227 and close the circuit to solenoid 27 when the input is zero. The latter thus operates to stop the pouring when the desired ingot-weight has been poured. A suitable circuit for 202, 203, &c. is shown in Fig. 4 (not shown, see Group XL (c)). In a modification, Fig. 8, the switch for closing the circuit of solenoid 27 is operated by a stepped cam angularly positioned on the balancing-motor shaft so that the angle of rotation occurring before the switch operates corresponds to the required ingot-weight. The circuits 202, 203 are omitted and their associated relays replaced by two-position switches operated by stepped cams angularly positioned on the motor-shaft so that the switches operate after predetermined weight changes have taken place, to replace one rate-potentiometer by the next. In a modified arrangement, (Fig. 6, not shown), the switching-means for altering the pouring-rate is omitted, a single rate being used. A tilting type of ladle may be used in conjunction with hydraulic means to alter the angle of tilt.