US2753605A - Apparatus for metering of molten metal by weight - Google Patents

Description

July 10, 1956 R. .1. cARLEToN, JR 2,753,605

APPARATUS FOR METERING OF MOLTEN METAL BY WEIGHT Filed NOV. 29, 1952 5 Sheets-Sheet l July lo, 1955 R. J. CARLI-:TON JR 2,753,505

APPARATUS FOR METERING OF MOLTEN METAL BY WEIGHT Filed Nov. 29, 1952 5 Sheets-Sheet 2 IND/(3470A7 INVENTOR. L@ @Marfil/WMM, 54' B gaat /MJ July 10, 1956 R. J. cARLEToN, JR

APPARATUS FOR METERING OF MOLTEN METAL. BY WEIGHT 5 Sheets-Sheet 3 Filed Nov. 29, 1952 BY/w: nuew/ July 10, 1956 R. J. cARLEToN, JR

APPARATUS FOR METERING OF MOLTEN METAL BY WEIGHT Filed NOV. 29, 1952 5 Sheets-Sheet 5 APPARATUS FR lJllllErRHilG @il MLTIEN METAL Bit WEIGHT Richard J. Carleton, Sir., Chagrin Fails, tibio, assigner to Republic Steel Corporation, lleyeland, (Ehio, corpo ration of N ew Jersey Application November 29, i952, denial No. 323,248 7 Claims. (Cl. ZZ-SZjt This invention relates to a method and apparatus for controlling the pouring of molten metal and more particularly for' automatically regulating the amount and the rates of flow of such metal from a metal containing ladle in accordance withV changes in total weight of the metal and ladle as the metal is poured therefrom, the apparatus being especially designed for automatic pouring of ingots or the like with a predetermined amount of metal and in a manner governed for each ingot, by a predetermined schedule of flow rates and quantities of metal.

ln devices for pouring molten metal, such as steel, into ingot molds7 a bottom-pour type of ladle is frequently employed. The bottom of the ladle is provided with an orifice or nozzle. A stopper is used to close the nozzle and to control the flow of metal from the ladle into the mold. ln order to pour the metal the ladle is positioned over a mold and the steel or other metal is poured at a rate determined by the nozzle size, the position of the stopper with respect to the nozzle, and the head of molten metal in the ladle. Because the stopper is usually con trolled manually, it is difficult to control the pouring rate accurately and to determine the total weight of metal poured into each mold. Accurate control of the pouring rate and the weight of each ingot are important factors affecting the yield and ingot quality.

For example, if the metal is permitted to dow too rapidly into the mold initially, the metal splashes up on the inside faces of the mold and hardens prematurely thereby producing a poor ingot surface when the ingot is completed. A poor ingot surface requires additional scarfing, chipping and grinding expense on the billet to assure a product free from surface defects.

Rapid or poorly controlled pouring may cause the entrapment of gases and thereby cause defects in the ingot. Furthermore, rapid flow of metal when the mold is almost full causes metal to splash out of the mold with a resulting loss of metal and danger to personnel.

When a small number of units are produced from each ingot and the weight of each ingot has not been accurately controlled, weight variations result in insufiicient metal for the last of the units thereby reducing the yield of usable pieces from each ingot.

In usual practice, the molds are filled in succession with sizes arranged as requested by the order department of the mill. The molds are poured successively until the ladle has been emptied and slag appears in the nozzle stream. With no knowledge of the exact weight of the steel in the ladle or the exact weight of steel poured into each ingot, the pouring cannot be accurately planned. The result is that in most instances the last ingot is a butt of varying height which must be scrapped.

It will therefore be appreciated that control of the pouring operation is important to eicient steel making operations.

Therefore, a chief object of this invention is to provide a method and apparatus for controlling the pouring operations to obtain the advantage of increased yield and improved ingot quality.

2,753,605 Patented July 10, 1956 Another object of the invention is to provide a novel and effective means for continuously indicating the weight of molten metal in the ladle; for regulating the weight of metal poured from the ladle; and for regulating the rate of flow of the metal from the ladle into the ingot mold.

A further object of the invention is to provide for automatically controlling a power operated stopper for both the pouring rate and the ingot weight.

Another and further object is to provide means of operating the controls for the pouring rate and ingot weight according to a predetermined schedule or pattern,

The foregoing and other additional. objects will be appreciated from the following and further description, herein, of the improved control system.

The invention, e. g. in its complete and preferred form, includes a control system adapted for use with a ladle having a nozzle therein and a stopper to close the nozzle and to regulate the flow therefrom. The ladle is suspended by means which include a weight sensing device for the control system. The weight sensing device is con nested to a means for indicating the weight of the ladle and metal contained therein. The weight sensing device is also connected to a measuring means which in conjunction with a programming means regulates a pouring rate control and an ingot weight control. These last mentioned controls are connected to means for raising and lowering the stopper to close the nozzle or regulate the flow of metal therefrom. The combination provides a continuous indication of the weight and a control of the pouring for each ingot and permits the planning of the number and size of ingot molds so that incomplete butts are not left over, and other objects of the invention are realized.

For a more complete and detailed description of the various elements of the invention, reference is made to the drawings illustrating embodiments of the invention.

In the drawings:

Fig. l is a schematic view of one form of control system embodying the invention;

Fig. 2 is a diagram of the measuring circuit, indicator and related parts which are shown generally in the schematic showing in Fig. l;

Fig. 3 is a diagrammatic showing of the ingot weight control circuit, the program control circuit, and the pouring rate control circuit, shown generally in Fig. 1;

Fig. 4 is a diagram of one form of detector circuit which may be used in the program control and pouring rate control circuits;

Fig. 5 is a chart indicating effects of changes in voltage input on the detector circuit;

Fig. 6 is a schematic showing of an alternate form of ingot weight control system;

Fig. 7 is an elevational view partly in section of the cam arrangement for the alternate form shown in Fig. 6;

Fig. 8 is a schematic showing of an alternate form of program control; and

Fig. 9 is an elevational View partly in section of the cam arrangement for the alternate form of program control.

Referring to Fig. l, which is a general schematic arrangement showing the combination, a ladle lil, e. g. for holding a large quantity of molten steel, is provided with a bottom pour nozzle il. A vertically movable stopper l2 is adapted to be seated against the upper part of the nozzle to close it. The relative position of the stopper with respect to the nozzle controls the flow of metal from the ladle lll into the mold i3, e. g. an ingot mold, above which the ladle is suspended. rl`he ladle is provided with a supporting bail or bar l5 which is engaged by a hook 16 of a Weighing apparatus 17. The weighing apparatus may be connected to the conventional crane or other suitable lifting device, not shown, by means of a hook 18 or other connecting means.

The position of the stopper 12 is controlled by a hydraulic Ycylinder which is operated by a hydraulic system consisting of conventional elements, such as a motor 2,1, a pump 2,2, a reservoir 23, and connecting pipes (i. e. the several lines described below), and also including a three-position, four-way valve 25. The four-Way valve electrically controlled by a pair of solenoids designated as up solenoid 26 and down solenoid 2.7. VThese solenoids are operated by suitable control circuits which will be described in greater detail below, so as to position the stopper and therebyV control the flow of metal from the ladle.

' The hydraulic cylinder 2t) is provided with a piston 28 and a piston rod 30 which is rigidly fixed to the lower end of a guide rod 32 by a horizontal crosshead 31. The guide Arod 32 is Slidably mounted in a vertically disposed sleeve 33 which is suitably `fixed to the side of the ladle. The hydraulic cylinder 2t) is fixed to the side of the sleeve 33 in any desired manner. The upper end of guide rod 32 is rigidly connected to the stopper 12 by means of a crosshead 35.

An auxiliary linkage system may also be provided to permit the mechanical operation of the stopper in the event of a power failure or other breakdown; the linkage system including pivotally connected links 3d and 36 between the side of the ladle 1d and the lower end of the guide rod 32. The end 37 of the link member 36 may be adapted to receive a manually operated lever (not shown) bywhich the stopper may be raised or lowered.

The'operation of the hydraulic stopper system is as follows: when the up solenoid 26 is energized, the slidable core 38 of the four-way valve 25 will be moved from left to right, as viewed in Fig. l, so as to bring the portion A of the core into alignment with hydraulic lines 40 and 41, in such manner that the line 40 from the pump is connected by means of the bore 42 (in the valve core) with line 43 which, in turn, is connected to the lower end of the hydraulic cylinder 20. ln this position, the line 45 connected to the upper end of the hydraulic cylinder 20 is connected by means of the bore 46 (in the valve core) with exhaust line 41 for returning hydraulic fluid (for example, oil or other suitable liquid) to the reservoir 23. Thus, with the valve in the position now described, the piston `28 moves upward in the cylinder 20 because of the uid pressure at the lower end of the cylinder acting` against the underside of the piston, `and the huid above the piston flows out through the lines 45, 41 into the reservoir 23. The piston rod 30, the guide rod 32 and the stopper 12 also move upward, permitting metal to tlow from'the nozzle 11, or increasing such flow.

When the down solenoid 27 is energized, the core 38 of the valve 25 moves from right to left so that the B position of the core is in alignment with the hydraulic lines. The line 40 from the pump 22 is then connected through the bore 47 to the line 45 thereby causing hydraulic iiuid to be pumped into the upper end of the hydraulic cylinder 20 and the line 43 from the lower end of the cylinder 20 is connected to the exhaust line 41 by means of the bore 48. Withthe valve in this position (the connections of the hydraulic lines being reversed relative to their connections through the A section), the piston 28, `piston rod 30, guide rod 32 and stopper 12 move downward to reduced or stop the ow of metal from the nozzle v11.

When neither solenoid 26 nor 27 is energized, the ,slidable core 38 of the valve 25 is caused to move to or remain in the neutral position (as shown in Fig. l) by means of springs Si) which are suitably attached to the `,core 38 as shown. ln the neutral position, the line do from the pump 22 is connected directly with the exhaust line 41 to the reservoir by means of the U-shaped bore ,51,V and the piston 2li is held in the hydraulic cylinder in the .position to which it was last moved, since the lines 43 and 4S are blocked by the core 3S of the valve 25. It will be understood that with this type of valve arrangement the pump may be continuously driven during the operation of the apparatus so that the piston 2S and the stopper 12 will therefore respond rapidly and positively to changes in the position of the valve. it will also be understood that in practice the bores d2, 46, 47, 48, and 51 may be arranged in closer, overlapping localities (i. e. with the A, neutral and B sections overlapping each other); however, for clarity of illustration they are shown in widely spaced portions of the core In the presently preferred arrangement shown, the solenoids Sie and 22" of the hydraulic stopper system are selectively energized by an automatic control system which is adjusted prior to pouring to control the number and size of the ingcts to be poured from a given ladle load in accordance with a desired schedule. rhe control system is also adjusted to regulate the rate of tlow during the pouring of each of the desired ingots. The control is based on changes in weight as the ingots are poured, causing changes in voltage which are compared with predetermined voltages.

Prior to the pouring the ladle receives a quantity of molten metal from the furnace. When the ladle is positioned over vthe iirst mold to be poured, the automatic control system is actuated through a remote control 59 to index the system to the tirst weight increment (which represents the weight of the first ingot) in the ingot weight control 117. The indexing of the rst weight increment by movement ot arrn 132 (Fig. 3) provides a given voltage which initially is not balanced by a similar voltage that is proportionally controlled by the reading of the measuring circuit ott, which registers voltage changes evidenced by the weighing cell assembly 17. The unbalance voltage from the ingot weight control 117 is fed `to the program control which controls the pouring rate control circuit 113 and the stopper control 192.

The several elements of the control system, as embodied in the speciiic form here illustrated, are now considered in detail: I

Weighing apparatus The weighing apparatus 17 which is schematically shown in Fig. 1 includes a weighing or load cell 55 which is disposed between the transverse arms of yoke members l56 and 57. The arrangement of the yokes 56 and 57 converts the tensile forces of the ladle load into a compressive force on the weighing cell 55. This arrangement permits the use of compression weighing in a crane weighing application. ln the weighing operation, the arrangement should very preferably be such (for example, as shown) that there are no varying frictional forces between the lower and upper yoke units 57 and 56 respectively of the apparatus. Unless otherwise compensated, such varying frictional forces would introduce errors in the load applied to the cell or cells and thereby cause weighing errors. As shown, for simplicity of illustration, only one weighing cell is disposed between the yokes 57 and 56. However, in actual practice, several cells may be used, the number depending upon the load to be weighed and the type of yoke design employed.

[t will be appreciated that in a mill installation of this type the entire weighing apparatus 17 is desirably surrounded by a heat shield (diagrammatically indicated by dotted lines 58) to maintain the load cell or cells at proper operating temperatures, e. g. preferably within a given, limited range.

It will be understood that any electrical weight-- responsive instrumentality having an electrical output (e. g. as voltage or as convertible to voltage) which can be made proportional to the weight of the ladle to may be employed in the illustrated system. Although in some cases tension type weighing cells (in which the tensile force may be directly measured) can thus be .used in substitution for the illustrated yoke arrangement whereby the applied tensile force of the load is converted to force ot compression, the compressive-type load cells such as indicated at 55 (which are well known devices and therefore require no detailed description here as, for example, devices of the type shown in U. S. Patent No. 2,488,349) are unusually suitable, especially in that they are of very rugged structure and provide an accurate and highly reliable electrical response to large loads. As will now be understood, the load or force supported by each such cell causes it, when suitably energized, to develop a voltage output correspond ing to its load; thus the total produced voltage, whether from a single cell or from a plurality of cells (carrying the weight in parallel and having their output terminals connected additively) corresponds to the entire compressive load imposed upon the cell or cells. This electrical voltage is then fed to or established in a measuring circuit designated generally at 60, where it is interpreted or translated for the controlling operations described below, and also (if desired) directly as Well as inferentially in terms of pounds or other Weighing units.

Measuring circuit Reference is made to Fig. 2 in which (again, for simplicity of illustration) a single weighing cell 55 is shown connected to the measuring circuit. The circuit of the weighing cell itself (shown schematically in Fig. 2) is essentially a Wheatstone bridge in which the resistance ,J

of one or more legs changes when a load is applied to the cell. r)This resistance change causes an unbalance in the bridge which in turn produces an output voltage proportional to the applied load. Specifically, a fixed input voltage (conveniently an alternating voltage, as shown) is carried from the secondary winding 61 of transformer 64 through the lines i. e. conductors 62 and 63 to the points 65 and 66 of the bridge, resistors 67 and 68 being provided in the lines 62 and 63. Changes in the resistance of one of the arms 75, 76, 77 and 78 causes an unbalance in the bridge which produces an output voltage at 69 and 74 proportional to the applied load.

The measuring circuit receives the output voltage from the weighing cell 55 and interprets it, so to speak, in pounds or other weight units. The measuring circuit is a continuous balance system which is diagrammatically shown in Fig. 2 and consists of a slide wire potentiometer 80, a zero control potentiometer 81, arm 91 of which may be manually adjusted prior to the loading of the ladle, and resistors 82, 33, 34 and 8S, all connected in a bridge circuit as shown, such that the movable arms constitute one pair of terminals of the bridge, i. e. its output terminals. A tixed voltage input, again an alternating voltage, is carried from secondary winding 79 of transformer 6d through lines iid and S7 to the input points or terminals 8? and 9i) of the measuring circuit, i. e. the bridge last described. The voltage output of the measuring circuit is the voltage between arms 91 and 52 of the two potentiometers S0 and Sil. The Voltage output of the measuring circuit is thereafter compared to that of the weighing cell by connecting them in series opposition, the arm 91 being connected to output point 69 of the weighing cell. The resultant voltage is fed through primary winding 93 of an input transformer 94 by lines 9S and 96 from weighing cell output point 74 and arm 92 respectively and is then amplified, as by the electronic tube 97. Although multi-stage or other amplifying means may be used if desired or necessary, a single vacuum tube amplifier is here shown for simplicity of illustration.

Grid 98 of the tube is connected to one output terminal of the transformer 94. Cathode 102. (energized by a suitable heater and current source therefor, not shown) and the other output terminal of the transformer are connected together and likewise to the return terminal of the plate current supply, here simply indicated by the battery ldd. The plate i053 and the other terminal of the battery are connected to motor winding lilo. The amplifier, represented by the tube 97, establishes an alternating current (in response to unbalance of the cell and measuring circuits) in the motor Wind- 'ing M6 which is one winding of a two-phase, reversible induction motor 107. Winding 19d, which is the other winding of the motor 107, is energized through a phaseshifting network which receives an alternating current input from secondary winding of transformer 64 through lines lill and 112. The phase-shifting network consists of resistor illl and condenser ille? connected in series across the secondary winding il@ by lines lll and i12. The motor winding Mld is connected into the phaseshifting network by lines ltitl and lill across the resistor The action of the phase-shifting network causes a 90 phase displacement between the two winding currents and thereby produces rotation of motor shaft M6. Thus, it will be appreciated that the motor windings iii-6 and tiS are connected so as to rotate the shaft 116 and the arm 92 of the slide wire potentiometer 80 (which is connected or coupled to the shaft) in a direction to make the amplifier tube input voltage approach zero. The amplifier tube input voltage will be zero when the voltage outputs of the measuring circuit and the weighing cell :75' are the same. As this point the winding 106 of the motor 1617 will receive no alternating current from the tube 97 and the motor shaft lilo will be stationar.

Any change in the voltage of the weighing cell 55 caused by a load change causes the motor to function as described above; the arrangement is thus in effect a continuous balance system because the measuring circuit is always being adjusted to malte the voltage output of the measuring circuit equal that of the weighing cell circuit.

Power is provided, for the output or secondary windings 6i, 7i and Mtl, of the transformer 64 from a suitable source (such as a conventional supply of 69-cycle alternating current) through lines 69 and lili) to the primary winding loll.

The angular position of the motor shaft 3.16 and of the arm 92 of the slide wire potentiometer 80 vary directly with the load applied to the cell. Thus, the angular position of the motor shaft is a direct indicator or measure of the load applied to the Weighing cell. lt will be understood that the motor N37 may constitute any suitable type of device for translating the output signal into corresponding rotation of the shaft M6, and is preferably a phase-controlled, reversible A. C. motor, i. e. especially a motor controllable in direction by the phase of a supplied A. C. signal relative to line current which also energizes the motor and controllable in speed by the magnitude of such signal.

Referring to Figs. l and 2, the measuring circuit is coupled mechanically by means of the motor shaft 116 to an indicator i. The shaft is also connected to the ingot weight control circuit i117 and the pouring rate control circuit 118 (see Figs. l and 3).

Indicator The indicator l2@ is a device which provides a Visual indication of the load applied to the weighing cell arrangement. For purposes of illustration, a simple indicator is shown in Fig. 2 and comprises an indicator dial 120 disposed concentrically with the motor shaft 116 and an indicator arm i951 which is xed to the motor shaft 116 and rotates with respect to the dial 12u as the motor shaft lilo is rotated. The dial may be calibrated directly in weight units because the angular position of the motor shaft varies with the weight applied to the weighing cell arrangement.

Ingolf weight control The ingot weight control M7 (see Figs. l and 3) includes three factors:

(a) Measuring the ingot weight;

(b) Determining when an ingot has reached a predetermined Weight;

(c) Operating the ladle stopper to interrupt the pouring when the ingot weight has reached the predetermined value.

Although these functions may be performed by any of various mechanical or electrical means, for purposes of illustration a simple but unusually effective electrical means for performing the functions is described herein, the corresponding circuit for the ingot weight control being shown in the upper part of Fig. 3.

T he ingot weight control circuit thus shown in Fig. 3 includes a slide wire potentiometer 122 having an arrn 123 which may be fixed on the motor shaft 116 and be adapted to rotate with said motor shaft. Voltage is supplied -to the potentiometer through lines 12S and 126 to the ends of the potentiometer resistance from a suitable, fixed source, such source being conveniently and simply represented here (as likewise other sources mentioned below) by a battery, specifically in this instance the battery 127. The weight indicating potentiometer 122 thus develops a voltage between its movable arm 123 and its fixed terminal 122er, corresponding to the instantaneous value of the ladle load, as a result of the potentiometer arm 123 being coupled to the motor shaft 116. The voltage level is a relative measure of the indicator position and the load Weight.

The ingot weight control circuit also includes an initial weight potentiometer 130, voltage being supplied across its lxed terminals, as by a battery 123. ri`his establishes a voltage reference (between the arm 131 of the potentiometer and its terminal 139g) corresponding to the initial ladle load before the pouring of the first ingot.

The general function of the ingot Weight control circuit is as follows:

A voltage divider network 129 provides voltage standards corresponding to the desired ingot weights of successive ingots, and a detector circuit 145 compares the voltage output of the weight indicator potentiometer 122 with the combined voltage output of the initial weight potentiometer and the voltage divider network. The voltage difference between these two voltage outputs determines whether the stopper control circuit is energized by the detector circuits (as will be described below) to permit the flow of steel from the ladle.

The network 129 comprises an ingot selector switch 132, and a plurality of resistors 136, 137, 13S, 139 connected in series across an adjustable voltage supply consisting of the variable resistor 135 in series with a battery 141, the zero contact of the switch being connected to the arm 131 of the initial weight potentiometer 13) and the resistors 136 to 139 being connected between successive pairs of the switch contacts t? to 4 inclusive. Thus a voltage is added to the output of the potentiometer 130 which is adjustable stepwise (from zero upward) by the switch 132. As explained above, this combined voltage output is to be compared (i. e. by connection in series opposition) with the output of the potentiometer 122, the return or fixed terminals 130e, 12de (of like polarity) of the potentiometers being connected by the conductor 140 and the above-mentioned, resulting voltage difference (if any) being then derived between the potentiometer arm 123 and the arm of the switch 132.

Before the first ingot is poured, the electrical circuit of the ingot weight control 117 is adjusted so that the following four conditions are satisfied:

(1) The contact arm 123 of the weight indicator potentiometer 122 is located at the upper end of the slide wire potentiometer, as shown in Fig. 3, since the ladle is full and ready for pouring.

(2) Contact arm 131 of the initial weight potentiometer 130 is positioned so that its voltage level is equal to that of the contact arm 123 of the weight indicating potentiometer 122, the respective voltages being compared by voltmeter 133 connected to line 124 from contact arrn 123 and line 134 from arm 131 through ingot selector switch 1.32. This may be done by locating ingot selector switch 132 in the zero position, as shown in Fig. 3, and then adjusting the arm 131 of the initial weight potentiometer 131i until voitmcter 133 reads 0.

(3) ingot weight setting resistor 135 is adjusted so that the current, from battery 141, fiowing through the equal resistors 136, 137, 133, and 13@ develops a voltage corresponding to the ingot weight desired, the proper setting of the ingot weight setting resistor being determined on .the basis of a suitable calibration which can be previously made by simple tests. That is to say, the voltage developed across each of the resistors 136 to 132 should be equal to the voltage change which will be produced in the `output or potentiometer 122 (by operation of the weighing cell 55, measuring circuit 6i) and motor 107) when the ladle weight is decreased by the weight of metal desired for a single ingot.

(4) The voltage input to the program control circuit is 0 with the ingot weight selector switch 132 set at the G position; this condition lis reached by the adjustment, under section (2) above, to obtain zero reading of the voltmeter 133.

When the above conditions have been set, the circuit is ready for controlling the pouring of the first ingot. For pouring the first ingot, the ladle is positioned over the ingot mold as shown in Fig. l and the ingot weight selector switch 132 is moved lfrom the O position to the l position (Fig. 3). This action immediately makes the potential of the arm of the ingot selector switch 132 more positive than the arm 123 of the weight indicating potentiometer 122. The magnitude of this yinitial voltage difference corresponds to the desired weight of the first ingot to be poured.

The voltage difference between the arms 123 and 132 is fed to the program control detector circuit 145. The positive voltage input to the Acircuit 145 acts to energize the pouring rate control circuit 118 which, in turn, energizes a control relay to energize solenoid 25 of the stopper control 192 for a sufficient time, whereby the stopper 12 is moved upward thereby allowing the metal to flow from the ladle 1,0 into the ingot mold 13. The action of the program control detector circuits will be described more fully below, and likewise, further below, the pouring rate control circuit.

As molten steel fills the ingot mold 13, the weight of the ladle decreases causing the arm 123 fixed on the motor shaft 116 of the weight indicating potentiometer 122, to move clockwise as viewed in Fig. 3. This action, increasing the positive potential of the line 12d, decreases the voltage difference between the arm 123 and the arm 132 of the ingot selector switch. The voltage dierence which is the signal output of the ingot weight control 117 and is thus the signal input to the program control detector circuits indicated generally at 145, approaches zero as the ingot approaches the predetermined weight corresponding to the voltage across the resistor 139, i. e. when arm 132 is in the l position. When the voltage output of the ingot weight control 117 reaches Zero, then, through suitable means described below, an energizing circuit for the down solenoid 27 is closed thereby moving the stopper 1 2 downward, shutting off the iiow of metal from the ladle.

To pour a second ingot, the ladle is moved into position over a second `ingot mold and the ingot selector switch arm 132 is moved from the l position to the 2 position, thereby re-initiating the cycle which has been described above. The switching to the 2 position establishes a voltage input to the program control and pouring rate control detector circuits, 145 and 118 respectively, and energizes the control relay 155 to raise the stopper and permit the molten metal to ow from the ladle into the second ingot mold. The metal fills the second mold to a weight corresponding to the voltage existing across the resistor 138, after which the stopper is moved downward to shut off the metal iiow. The above described operations are repeated for the remaining number of ingots. .As shown in the circuit, provision is made for the pouring of four ingots. However, this number may be increased or decreased (e. g. by providing a greater or less number of resistors lltwilw, and contact points of the switch 132) depending upon the number of ingots to be poured from the ladle.

The above ingot Weight control circuit as shown is designed to control pouring of a given weight standard for all ingots to be poured from the ladle. However, it will be appreciated that the circuit may be modified readily so that ingots of different weights may be poured from the ladle during any given pouring by changing the size of one or more of the re. istors 13o-13d, as desired, or by changing the setting of resistor 135'.

Whereas the ingot weight control circuit 117' determines the weight of each ingot through the program control 145 and the pouring rate control 11S determines the rate at which each ingot is poured (all in manner which will be explained in further detail below), a detector circuit suitable for use in the program control circuit and the pouring rate control circuit is first described below.

Detector circuit While the selective response means may be used, the electrical circuit of an especially suitable detector which may be taken as typical for the stated control circuits, is set forth in Fig. 4. The circuit includes a conversion stage, a voltage amplifier and a relay circuit. The conversion stage consists of converter 161i and a transA former 161 and coil 162 connected to a secondary wind ing 163 of transformer 173 for vibrating the armature 164 of the converter. The converter 161i is a single pole, double throw, switch operating in synchronism with the line voltage frequency of the transformer 17d, which may be energized, for example, from a conventional 60-cycie supply. lt converts the D. C. input voltage (i3/1) to a proportional A. C. voltage (E-2). The transformer 161 feeds the alternating signal to the amplifier tube 165. The phase of this A. C. input voltage (relative to any given voltage derived from the transformer 173) depends upon the polarity of the D. C. voltage [ed into the converter. For simplicity of illustration, the representation of E-Z in Fig. 5 shows this voltage essentially as it appears across the secondary of transformer 161, without taking into account the effect of the steady bias supply 171.

The voltage relationships in the detector circuit are i1- lustrated in Fig. 5. It will be noted how the phase relationships depend upon `the D. C. voltage input to the detector circuit, i. e. a positive D. C. signal input at E-1 causes an A. C. voltage of a given phase and a negative D. C. input signal causes an A. C. voltage of a phase opposite to that of the first mentioned given phase.

The voltage amplifier portion of the detector circuit multiplies the grid input voltage to a high level and also changes the phase of the signal 180 relative to the input signal voltage. The amplifier circuit consists of the amplifier tube 165, a grid resistor 166, a plate resistor 167, a plate voltage supply 16S and a bias voltage sup ply 171. The amplifier is designed for high gain operation so that the voltage output at low input signal levels is large. At high input signal levels, the tube 165 will supply a relatively constant square wave voltage to the following stage because of the grid limiting resistor 166 andthe setting of the bias voltage 171.

Thus, the amplifier supplies a large relatively constant A. C. signal voltage to the following stage except for very small signal levels fed into the amplifier.

The relay portion of the detector circuit receives a signal from the amplifier portion described above and determines by phase and magnitude measurement whether its associated relay shall operate. Relay 176 is in circuit with tube 172 which has a grid circuit that consists of a grid resistor 175 and a bias voltage supply 177 (returning to the cathode 180 through the relay 176, which iS functionally in the plate circuit) and that is connected to the tube 165 through coupling condenser 173. The plate circuit of tube 172 includes a secondary winding 179 of transformer 17S, and the winding of relay 176.

The following two conditions must exist to operate the relay 176 which, as described, is connected in the plate circuit of tube 172:

(a) The input voltage to the relay circuit from amplier tube 165 must be sufficiently positive to raise the grid voltage of the tube 172 above the cut-off voltage to permit conduction of current through the tube. The cutoff voltage is determined by the negative bias voltage (1L-5) from battery 177, the grid resistor 175, and the characteristics of the tube 172. As shown in column l5-4 of Fig. 5, the voltage actually applied to the grid of the tube 172 oscillates about a value (El-5) more negative than (or at least as negative as) the cut-off value indicated by the line 17251; only on the less negative half of each cycle does the grid of the tube 172 rise above cutoli.

(b) The phase of the grid input voltage to the tube 172 must be the same as that applied to plate 131 of the tube 172. These relationships are illustrated in Fig. 5 in columns designated iE-3 and l-d.

Thus a large input signal in phase with the A. C. plate voltage (El-4i) will cause the relay 176 to be energized, by the pulsating (half-wave) current which then dows `in the plate circuit of the tube. This situation exists when the input 'to the detector circuit is a positive D. C. signal voltage as illustrated in line A of Fig. 5.

The relations shown graphically on lines B and C in Pig. 5, demonstrate the relay circuit action when the input signal to the detector circuit is zero or negative. As there illustrated, the tube 172 will be non-conducting so that the relay 176 will be tie-energized.

By changing the phase of the A. C. plate voltage supply to the tube 172 (e. g. by reversing the connections to the transformer secondary 179), the same circuit will energize the relay 176 only when the input signal to the W detector circuit is negative. Thus, zero input signal or positive input signals will not energize the relay if this change is made. The relay 176 corresponds to each of the relays and 156 of the pouring rate control circuit 1115 which selectively closes the circuits of the stopper control and energizes the solenoids 26 and 27 for positioning the stopper to control the flow of molten metal from the ladle.

The relay 176 also corresponds to each of relays 212 and 213 of the program control circuit 145, the functions of which will be described below.

By way of example, the relay 176 is shown in Fig. 4 as closing a circuit connected to lines 182 and 183 upon energization, it being understood that with appropriate contact arrangements such a relay may perform any number of circuit closing or opening operations or combinations of such operations, or more specifically as will be described in relation to the program control and pouring rate control circuits.

Pouring rate control The pouring rate control involves the following three factors:

(o) Measuring the rate at which the ladle weight is changing, such rate also reecting the changing weight of the ingot that is beinfr poured.

(b) Comparing the measured rate of change with a standard or predetermined rate of change.

(e) Automatically controlling the stopper position so that the actual measured rate of ow is equal to the predetermined rate of flow.

Altl'iough these junctions can be performed by any of various electrical and mechanical means, for purposes of illustration one notably advantageous electrical system is shown in Fig. 3 and described below. The pouring rate control means shown in the circuit in Fig. 3 includes a.

l i. rate generator 190 which provides a voltage proportional to the rate of change of weight in the ladle load during pouring; a reference potentiometer which provides a voltage reference corresponding to the desired or predetermined ow rate; and a rate control circuit which compare-s the voltage output of the rate generator 190 with that of the rate reference potentiometer and determines the change required in the Stopp :r position to obtain the desired flow rate. The rate control circuit energizes the stopper control circuit 192 to e'lect 'the required change in the stopper position for obtaining the desired ilow rate from the ladle. As pointed out elsewhere herein, an accurate control of pouring rate is highly desirable, e. g. to obtain as rapid pouring as possible with due regard to avoidance of splashing and other adverse effects, and indeed to enable a program of pouring rates to be followed, in a manner which will be explained in more detail below.

Referring to Fig. 3, the rate generator 19t) is coupled mechanically to the motor shaft 116. The rate generator is essentially a tachometer (sometimes called a tacho-gen erator) which generates a D. C. voltage proportional to its rotational speed which in turn is proportional to the rate of change of weight measured by the measuring circuit. The rate generator may thus consist of a suitable tacho-generator of known character, requiring no detailed description here.

The voltage output of the rate generator it? is compared to that of a rate reference potentiometer. This potentiometer gives a voltage reference corresponding to the desired rate of ow. ln the complete system of Fig. 3, a plurality of such potentiometers are shown at 295, 2.66 and 297 for a programmed control of successively differing pouring rates as explained more fully hereinbelow, but for the here immediately following description of the rate control circuit lili, it may be simply assumed that a single rate reference potentiometer is used, for example, lthe potentiometer Ztl, and is connected with its output voltage in series opposition to the output voltage of the rate generator lil/i9, so that the resulting difference (it any) of the voltages appears across the lines 191i., 194i. The difference thus appearing between the voltage output of the rate generator i912 and Ythe rate reference potentiometer is ted to the rate control circuit which includes a ratti: inc cuit 157 and a rate decrease detector circuit 3.58. `5When the rate of metal flow is higher than the predetermined rate, the voltage output of the rate generator will be more positive than that of the rate reference potentiometer. This causes the input voltage to the pouring rate control circuit including the detectors i557 and to be positive.

Conversely, when the rate of metal liow is lower than the predetermined rate, the voltage output of the rate generator will be negative compared to that of the rate reference potentiometer. This causes the voltage input to the rate control circuit to be negative.

Thus, a positive signal input to the pouring rate control circuit 113 corresponds to a higher rate of metal flow than is desired and a negative signal corresponds to a lower rate of metal flow than desired.

As noted above, the rate control circuit ildincludes the rate increase detector circuit 157 and the rate decrease detector circuit The rate increase detector circuit 157 is the same as the detector circuit shout/n in Fig. 4 and described above except that the phase of the plate supply voltage i722 for the relay portion of the circuit has been changed 180. This makes the rate increase circuit sensitive to a negative input signal rather than a positive input signal voltage. Thus when the rate of ow is lower than the desired or predetermined rate, the negative signal input to the rate increase circuit 157 causes this circuit to energize its relay t' thereby closing contacts 195. The contacts E95 energize the up solenoid 26 of the stopper control E92. Thus, the

me detector cir- L stopper 12 is moved upward, thereby causing the rate E95 to open, which in turn deenergizes the up solenoid 26 thereby stopping the upward :notion of the stopper 12.

Rate decrease circuit 158 is the same as the detector circuit described and shown in Fig. l. Thus when the rate ot flow is higher than the desired or predetermined rate, the positive voltage signal input to the rate decrease circuit S causes this circuit to energize its relay 56 thereby closing contacts 197. The contacts M7 energize the down solenoid 27 of the stopper control down relay 192. Thus, the stopper 12 is moved downward thereby causing the rate of flow to decrease. As the rate of tlow decreases the positive signal input to the rate decrease detector circuit also decreases until the signal is zero. When the input voltage to the rate decrease detector circuit 158 is zero, the relay 156 will be deenergized, opening contacts 197 and in consequence deenergizing the down solenoid 27 thereby stopping the downward motion of the stopper l2. The above action (of the rate ldecrease circuit) thus operates to cause the rate of flow to equal the desired or predetermined rate of ow.

it will be appreciated, of course, that if the rate of ow is lower than the desired rate, the above circuit which controls the relay will not operate to raise the stopper since the corresponding negative signal input (at the lines 191, 194) has no effect on this rate decrease circuit. Such negative signal input, however, will aiect the rate increase detector circuit l5? to suitably increase the ilow. ln similar 'fashion the rate increase detector 157 is insensitive to a positive signal, but the latter will cause the rate decrease circuit 58 to function for the required decrease of pouring rate. The combined action of the rate increase detector circuit 157 and the rate decrease detector circuit Lii is therefore such that they maintain the stopper at a position where the rate of tlow corresponds to the predetermined rate of flow set by a given rate reference potentiometer.

lt will be appreciated that the above described circuitr', permits programming of the rate of flow according to some schedule which if desired may involve only a single rate reference potentiometer providing a fixed voltage output (which is compared with the rate generator output, as in the described series Opposition) during the pouring of an ingot. However, to eTect a change in the controlled rate of flow, it is necessary to change the voltage output of the rate reference potentiometer to the required value at the required time. @ne effective mode of achieving this control is by replacing a single rate reference potentiometer having a fixed voltage output (such as assumed to be used, in the foregoing description of the rate control lll) with a set of potentiometers and then switching in the proper one of them at the proper time to function as the rate reference potentiometer. This operation is achieved automatically by a program control circuit which is shown in Fig. 3 and described below.

T he program control'V of the pouring rate Programming the pouring rate according to a predetermined schedule may conveniently be governed oy appropriate, detectable quantity or variable. lt is found that this variable, which is to control thc sequence of pouring operations (i. e. the sequence of pouring rates), may very advantageously be a weight or time factor. The variable, for example weight (i. e. to effect changes of pouring rate upon reaching predetermined weight values), is thus measured in terms of a signal which can be fed to a rate control circuit which in turn controls the pouring rate from the ladle. i

One means of effecting this program control is shown in Fig. 3 and described below. In such arrangement, programming of the pouring rate is made with regard to the ingot weight. For example, to attain certain special results as will now be explained, the pouring rate schedule is divided into the following three phases:

l. initial slow pouring rate Ato minimize splashing as the molten metal is poured into the empty mold;

il'. Medium pouring rate which will be the normal pouring rate tor any given ingot;

lll. Medium slow pouring rate at the end of each ingot to assure accurate weight control and also to minimize splashing as the level of molten metal approaches the top of the mold.

The areas in which the three phases of the pouring rate may be used with respect to the mold are indicated in Fig. l (the lonian numerals l-lli on the mold i3 corresponding to the phases l-III above). The three phases are also indicated at the right-hand side of the program control circuit M5 in Fig. 3.

T he programming of the pouring rate is accomplished through the ingot weight control circuit ll'l, the program control circuit M5 and the pouring rate control circuit lllll. These circuits function as follows:

The ingot weight control circuit, at its output leads 12e', .t3/i, provides a voltage signal corresponding to the weight of molten metal in the ingot mold. This voltage signal is used not only to determine the beginning and end of pouring, but also specifically to determine the pouring rate required at various intervals during the pouring of the ingot.

rfhe program control circuit receives the voltage output of the ingot weight control circuit. At predetermined voltage levels, this circuit selects a predetermined rate reference voltage which is fed to the pouring rate control circuit, i. e. in comparison with the Voltage of the rate generator 19t).

The pouring rate control circuit il@ receives the signal determined by the rate reference voltage from the program control circuit and automatically adjusts the pouring rate (as detected by the rate generator lill?) to 'the level of the rate reference voltage. In Fig. 3, for ex ample, the ingot weight control circuit lll? feeds the voltage indicated by voltmeter l to the program control circuit M5. This voltage is a positive signal corresponding at the outset to the total weight of the ingot to be poured, and at following times, to the amount of metal which yet remains to be poured. Hence this voltage decreases as molten metal is poured into the ingot mold so that it reaches zero when the mold has been filled to the desired weight, all as noted above in the description ot the ingot weight control circuit.

The program control circuit 14S consists of a selecting detector A 202 and a selecting detector B Zili and three rate reference potentiometers 20S, 2do and 2L?. Selecting detectors 202 and 2d?, may each advantageously have the same circuitry as the detector cicuit shown in Fig. fl and described above with respect to that figure; they are each sensitive to a positive input signal and insensitive to a zere or negative signal. Bias voltage supplies 2l@ and 2li in the selector input circuits, being respectively dilierent voltages each connected in opposed relation to the applied signal in the line i3d, regulate the level of input voltage required for energizing the relay of a given selecting detector.

At the start of pouring the positive voltage input to the selecting detectors 202 and 2tl3 exceeds both of the bias voltages 2li@ and Zll thereby causing the relays 2li?. and

of selectors M32 and 233 respectively to be energized. This action closes contacts 216 and 2l@ and opens contacts 217 and 219. The energizing of both selector relays causes the voltage supplied by battery 2do through rate potentiometer 2M (i. e. as reduced to a predeter ruined value by such potentiometer) to be fed through contacts 2id to the comparison circuit that includes the rate generator 190, for supplying a control signal to` the pouring rate control circuit 11S. Voltmeter Zini indi cates the amount of voltage from rate reference potentiorneter 205. The voltmeter 222 indicates the output voltage of the program control circuit MS and that output voltage is compared with the output voltage of the rate generator 19t) indicated by the voltineter As explained above, the dierence between these two voltage outputs as indicated by the voltmeters 2212 and 223 is the signal fed to the pouring rate control circuit lit.

The pouring rate control circuit then adjusts the pour ing rate (in this instance, after it first initiates pouring) so that the rate generator voltage is equal to the reference voltage. Thus, the pouring rate depends upon the magnitude of voltage output of the program control circuit, snd is maintained at a predetermined value determined 'oy such voltage.

lt may be explained that at the outset of pouring operation i'or a given ingot, the ladle stopper has been closed and the rate generator isy therefore at rest, producing no voltage. Hence the signal initially supplied to the lines Mil, we (upon the energization of both program control relays 212 and 2l3 as explained above) represents the entire output voltage of the rst rate reference poH tentiometer 265. Furthermore, the initial application of this positive voltage to the rate increase detector thus effects the first opening displacement of the ladle stopper, as well as prompt, continuing upward adjustment of the stopper until the pouring rate (detected with the rate generator wil, now running) reaches the desired value represented by the voltage of the rstselected potentiometer 21Go'. In other words, the described instrumentalities (including the circuits M5 and 118) not only etfectuate the desired pouring rate control but also constitute the channel through which the initial appearance of voltage in the ingot weight control circuit lili causes the lirst energization of the up solenoid, to start the pour ing ot the given ingot.

As metal liows from the ladle, the voltage input on the lines 24-, lill (indicated by the Voltrneter i3d) to the program control circuit decreases. When this volt-- age is equal to that of the bias voltage supply 210, the relay 212 ot' the selecting detector A 292 will be deenergized (the relay of detector E remaining energized, since bias voltage 2li is smaller than bins voltage 2in). This action opens the contacts 2id and closes the contacts 217 thereby supplying a new reference voltage from the rate potentiometer 206 to the rate control circuit lili. This voltage is indicated by the voltrneter 21M.

The pouring rate control is then automatically adjusted to a value corresponding to the new reference voltage, that is to say, the relay ld is actuated to close the contacts @E to operate the up solenoid 26 of the stopper control to raise the stopper whereby the pouring rate is increased to correspond to the reference voltage of phase Il (medium pouring rate).

With continued pouring from the ladle the voltage input (to the program control circuit) as indicated by the voltrneter 133 decreases further until it is equal to the bias voltage supply 2li. At this point, the relay ZES of the selecting detector B 203 is deenergized, while the relay 2ll2 of detector A remains deenergized. This action opens contacts 2M and closes contacts Zw, thereby supplying a new reference voltage from the rate potentiometer 207 to the pouring rate control circuit lit. This voltage is indicated by the voltmeter 225 in the output circuit of the reference potentiometer 207. The pouring rate control clrcuit then automatically adjusts the pouring rate to a value corresponding to the new reference voltage, i. e. the relay i156 is actuated to close contacts 197 for operating the down solenoid 27 to lower the stopper l2 where by the pouring rate is decreased to correspond to the reference voltage of phase III (medium slow pouring rate).

As previously described, the ingot weight control finally operates the down solenoid 27 when the metal poured into the ingot mold has reached the desired nal height, and thereby shuts off the ow of metal from the ladle. That is to say, when the positive signal in the lines 124, 134 from the weight control circuit 117 disappears, appropriate control is exerted to close the circuit of the down solenoid 27 and keep it closed at least until the stopper has moved to fully closed position.

The appropriate control may be a detector 226 similar to that shown in Figure 4, in which relay 227 in the detector circuit is deenergized when the voltage input to the detector 226, through conductors 124i, 134 reaches zero. For this purpose the detector circuit 226 is similar to detectors A and B without any bias voltage supply imposed in the input line 134. With this arrangement when the voltage input is zero and the relay is deenergized the circuit for the down solenoid is closed through contacts 228, 229.

In the apparatus shown in Fig. 3 the ingot weight control circuit operates through the program control circuit and the pouring rate control circuit except at the cycle end when detector 226 operates to close the stopper.

However, it will be understood that the ingot weight control circuit may be directly connected to the stopper control. In such an arrangement the up solenoid 26 is connected so that its circuit is closed when there is any positive voltage input to the cycle detector 226. This is accomplished by providing conductors 214, 21S from the circuit of the up solenoid with contacts 220, 221 which are closed when the relay 227 is energized. The circuit connecting the up solenoid circuit to the cycle detector 226 is rendered operative by closing manual switch 209.

It will be appreciated that suitable means may be provided such as servo mechanisms in the stopper control circuit to arrest the movements of the stopper when it reaches its upward and downward limits to prevent damg age to the equipment. When the up and down solenoids are operated by the ingot weight control circuit directly, the connection of said circuit with the program control circuit and the pouring rate control circuit is rendered inoperative by opening switches 208. The alternative arrangement for connection of the ingot weight control to the up solenoid of the stopper control is also shown in Fig. l.

The schedule of the pouring programs depends upon the setting of the bias supply voltages 210 and 211 and the rate reference potentiometers 205, 206 and 207. The bias supply voltage determines when a given flow rate is to be had (i. e. represent weight values corresponding to the successively reached upper boundaries of the ingot portions I and Il in Fig. 1), and the settings of the rate reference potentiometers determine what the various pouring rates shall be. Voltage is supplied for the rate reference potentiometers 20S, 206 and 207 by suitable means, here exemplified as the batteries 20S. It will be appreciated that the several voltmeters shown in Fig. 3 facilitate setting of the corresponding reference or control voltages, e. g. to achieve accuracy in the intended controls of rate and amount of metal poured, it being understood that, if desired, appropriate potentiometer and voltmeter means (not shown) may be employed for voltage sources shown as fixed, such as the bias supplies 210, 211.

The mode of operation of the entire system has been fully explained in the course of the foregoing description and therefore need not be repeated. As will be understood, the various control or reference elements can be reset or adjusted as necessary as pouring operations are to be commenced with a full ladle. Then when the ladle is brought by its supporting crane over the first mold, the operator turns the selector switch 132 to position l and the pouring automatically proceeds, following the established program of pouring rates, until the desired weight of' metal has been deposited, whereupon the stopper is automatically closed. For each of the successive molds, the selector switch 132 has corresponding successive positions, with like automatic response o f thel pouring control. When the ladle has nally been emptied or is ready to be refilled, the electrical control elements can be disconnected or deenergized, if necessary, preliminary to refilling the ladle and re-setting the system. The shaft 116 and its associated parts can be turned back, or indeed allowed to be driven backwards by the motor 107 under control of the cell 55 and circuit 60 during or upon the filling of the ladle with molten metal; and when everything is again set in the manner explained above, a new series of pouring cycles may be commenced.

Weight Control-mechanical system Many of the previously described electrical control operations of the system here disclosed may be performed by mechanical means. To constitute such alternative embodirnent of the invention, one convenient means of ingot weight control and program control involves the use of cam operated switches. For purposes of illustration of a mechanical weight control means, reference is made to Figs. 6 and 7.

1n the mechanical control system, the up and down solenoid switches are actuated by a cam operated switch. Referring to Fig. 7 (which shows the cam in section along its axis of rotation), the cam operated ingot weight control includes a stop 230 (in the form of a collar secured on the shaft 116), a cam 231, a switch 232 (to be operated by the cam), a spring 233, and a washer 234. The assembly may be mounted on the motor shaft 116 which rotates in response to rotation of the motor 107 which is actuated by the weight cell and the measuring circuit as described above and shown schematically in Fig. 6. The angular position of the shaft 116 is a measure of the weight which has been poured from the ladle; thus, as metal is f poured from the ladle, the shaft 116 rotates, as indicated by the arrow in Fig. 6. The cam 231, which is held by the stop 230 and the spring 233, rotates with the shaft 116. The spring 233 is held in place and under compression against the cam by the washer 234 which is fixed on the shaft 116 by a screw 235 or other suitable means. The angular displacement of the cam is therefore a measure of the metal poured into the ingot mold.

At the start of the pouring, the cam 231 is positioned so that the distance D (see Fig. 6), which is a selected part of the high portion of the cam (terminating at the notch or step 238), corresponds to the weight of the metal to be poured. The cam 231 which is heldin place against the stop 23) by the action of the spring 233 may be reoriented with respect to the shaft 116 to vary the distance D by pressing it axially toward the Washer and rotating it as desired, i. e. when adjustment of the weight value is required.

As metal is poured from the ladle, the cam 231 rotates with the shaft 116 and, when the cam is rotated the distance D, the switch 232 is closed. Movable arm 236 of the switch is connected to cam follower 237 so that when the cam follower moves downward at the cam step 238, the switch arm 236 contacts terminal 239 to close the down solenoid circuit 27 to energize the solenoid as from a battery 240. When the switch 232 has thus energized the down solenoid 27, the stopper 12 is closed thereby shutting off the flow of metal from the ladle 10.

To pour the next ingot the cam 231 is repositioned so that the distance D corresponds to the weight of the ingot desired. Switch 243 of the up solenoid circuit is closed (e. g. manually, for an appropriate interval) to energize the up solenoid 26 and raise the stopper tostart the pouring of metal. Battery 244 is provided in the up solenoid circuit to supply power to energize the up solenoid 26. If desired, a suitable interlock switch (not shown) may be provided to open the up solenoid switch 243 when the down solenoid switch 232 is closed and vice-versa.

Mechanical means may also be provided for a program control, one form of switch means for such control being shown in Figs. 8 and 9. i

Program control-mechanical system The electrically operated program control system which has been described above (Fig. 3) feeds a Voltage to the pouring rate control 118 for comparison with the output voltage of the rate generator 190. The voltage difference between these two signals operates suitable control circuits for positioning the stopper to obtain the desired pouring rate.

As also indicated above, a cam operated control system may alternatively be provided for switching the desired reference voltages to the pouring rate control circuit, In the form shown in Figs. 8 and 9 the cam operated program control includes a cam stop 246 (secured on the shaft 116), cam 247, switches 248 and 249 (both to be controlled by the cam 247), cam 250, switches 251 and 252 (both to be controlled by the cam 250), spring 253 and washer 254. The assembly may be mounted (in the same manner as the assembly of Fig. 7) on the motor shaft 116 which is driven by the induction motor 107 in the measuring circuit 60. The angular position of the shaft is a measure of the weight which has been poured from the ladle. The shaft rotation varies directly with the weight of metal poured into a given ingot mold. As will now become apparent, these relationships allow the use of cam operated switch means for automatic switching of reference voltages to the pouring rate control circuit 118, which is indicated in Fig. 8 and will be understood to be identical with such circuit as shown in Fig. 3.

At the start of pouring, cam 247 is positioned so that the distance D-1 (see Fig. 8) which is a selected part of the high portion of the cam (terminating at the step 262), corresponds to the weight at which the switches 248 and 249 are operated. The cam 250 is positioned so that the distance D-2, again a selected part of the high portion, corresponds to the ingot weight at which the switches 251 and 252 are to be operated. The cams are easily rotated to the desired angular relationship on the shaft 116 and are held in such position by the spring 253. Spring 253 is maintained in compression by the washer 254 which is fixed on the shaft 116 by a screw 255 or other suitable means.

Initial voltage from potentiometer 258 is fed to pouring rate control circuit through the switch 248, closed at the outset by the cam portion D-1. This voltage is set so that the initial pouring rate is low enough to avoid splashing in the ingot mold, i. e. phase I. The pouring into the ingot may be initiated by closing switch 260 which may, if desired, be located in a remote control such as that indicated at 59 in Fig. l. The closing of switch 260 causes the entire initial positive voltage from the potentiometer 258 supplied by battery 256 to be fed to the pouring rate control circuit 118 thereby actuating the rate increase detector and energizing the relay 155 to close contacts 195. In consequence the up solenoid 26 is energized, to raise the stopper 12 for starting the flow of metal from the ladle. Thereafter the voltage from the potentiometer 268 is compared with the voltage from the rate generator 190, for regulation of the stopper to maintain pouring rate I, the signal thus supplied on lines 291, 292 being the same in nature and function as that appearing on lines 191, 192, in Fig. 3.

As metal is poured from the ladle, the shaft 116 rotates and when the cam 247 is rotated the distance D-1, cam follower 261 moves downward at cam step 262. The arms of the switches 248 and 249, which are attached to the cam follower 261, are therefore caused to move sothat the switch 248 is opened and switch 249 is closed. This action disconnects potentiometer 258 and feeds a new reference voltage supplied by battery 264 through potentiometer 263 to the pouring rate circuit 118 (switch 251 of the cam 250 being now closed).

This new reference voltage determines the pouring rate which is to be used during the next phase of the ingot pouring, indicated by Roman numeral II in Fig. l. Potentiometer 263 (across battery 264) supplies an increased voltage which, when fed to the pouring rate control circuit operates to raise the stopper 12 to increase the pouring rate in the manner described above.

When the cam 25) is rotated the distance D-2, cam follower 270 moves downward over cam step 271 thereby moving the arms of 279 to which the switches 251 and 252 are connected in such manner that switch 251 is opened and switch 252 is closed. This action disconnects the potentiometer 263 and feeds a new reference voltage from potentiometer 272 to the pouring rate control circuit 118. The voltage from potentiometer 272 is supplied by battery 274. This reference voltage deter mines the pouring rate during the latter part of the pouring, i. e. phase III during which a medium slow pouring rate is desired to obtain accurate weight control of the ingot.

It will be understood that the mechanical control means shown in Figs. 8 and 9 is an alternative means of program control and produces the same general results as the program control circuit shown in Fig. 3. The program control of Fig. 8, which in part involves a weight control system, is preferably used in conjunction with an ingot weight control circuit such as shown in Fig. 6, i. e. especially to interrupt the pouring. For example, with respect tothe arrangement in Fig. 6, the cams 247 and 250 may be mounted on the shaft 116 with cam 231 so that when the shaft has rotated the distance D (which is greater than D-2 by an amount corresponding to the Weight of ingot section III), indicated on cam 231, the

down solenoid is energized (by the separate circuit 239, 240, then connected in parallel with the circuit for the down solenoid 27 in Fig. 8), to close the stopper 12 and thereby arrest the pouring of the ingot, in the manner described.

When the circuit shown in Fig. 3 is used, the ingot weight control 117 may be operated from the remote control 59. Such an arrangement is indicated schematically in Fig. l. The control 59 may include the switch arm 132 (see Fig. 3) for manual operation thereof (e. g. specifically by a flexible, rotatable cable extending from the control boX 59 to the shaft of the switch arm 132) or have suitable relay switches for operating the member 132. The remote control 59 may be :a portable control boX which may be carried by the operator so that he may observe the progress of the pouring.

From the foregoing description, it will be appreciated that the apparatus of this invention may be utilized to elfect the various objects set forth e. g. of accurately controlling the size of ingots and regulating the rate of How, to obtain a number of important advantages, including increased yield, improved ingot quality (especially at the bottom, sides and top), and safer and more convenient operation.

The description of the method and apparatus for controlling the pouring of molten metal has been illustrated in an application to the bottom pour type of ladle. However, it will be understood that it may also be utilized for controlling other types of apparatus such as the tilting type ladle wherein the control outputs could be applied to a suitable motor which tilted the ladle for pouring.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of the invention, together with the elements which I now consider the best embodiments thereof, but I desire to have it understood that the structure disclosed is only illustrative and the invention can be carried. out by other means. Also, while it is designed to use the various features and elements in the combinations and relations described, some of these may be altered and modied without interfering with the more general results outlined.

Claims (1)

1. IN AN APPARATUS FOR AUTOMATICALLY CONTROLLING THE FLOW OF MOLTEN METAL IN ACCORDANCE WITH A PREDETERMINED PATTERN, MADE UP OF SUCCESSIVELY DIFFERENT CONSTANT FLOW RATES, THE COMBINATION, WITH A LADLE FOR CONTAINING MOLTEN METAL, NOZZLE MEANS IN THE BOTTOM OF THE LADLE THROUGH WHICH METAL MAY FLOW FROM THE LADLE, AND STOPPER MEANS IN THE LADLE FOR REGULATING AND STOPPING FLOW FROM THE NOZZLE MEANS, OF MEANS FOR AUTOMATICALLY ACTUATING THE STOPPER MEANS FOR CLOSING THE NOZZLE AND FOR REGULATING THE FLOW THEREFROM, SAID AUTOMATIC MEANS INCLUDING WEIGHT SENSING MEANS FOR CONTINUOUSLY SENSING WEIGHT CHANGES IN THE LADLE AND THE METAL CONTAINED THEREIN AND MEANS FOR ADJUSTING THE STOPPER MEANS IN ACCORDANCE WITH AND FOR MAINTAINING THE PREDETERMINED PATTERN OF SUCCESSIVELY DIFFERENT FLOW RATES AS WEIGHT CHANGES ARE CONTINUOUSLY SENSED.

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