US3378061A

US3378061A - Continuous casting arrangement

Info

Publication number: US3378061A
Application number: US450570A
Authority: US
Inventors: Alt Rolf Von; Viessmann Klaus
Original assignee: Kreidler Werke GmbH
Current assignee: Kreidler Werke GmbH
Priority date: 1964-04-07
Filing date: 1965-04-06
Publication date: 1968-04-16
Anticipated expiration: 1985-04-16
Also published as: GB1094501A; DE1458083B2; DE1458083A1; BE662131A; CH438591A; SE314478B

Description

ROLF VON ALT ETAL 3,378,061

CONTINUOUS CASTING ARRANGEMENT 5 Sheets-Sheet l N WW TL 1 1 i l I N m w H WH HUP M QQ Mm k S U A L DnK Q Q 4 mw Q %N fih Q, Q m a E, N Q L Q m? 1 Q Q: /& Q Q B W m% \h Q .N l an R g @N\ M N A ril 16, 1968 Filed April 6, 1965 ATTORNEYS ROLF VON ALT ETAL 3,378,061

CONTINUOUS CASTING ARRANGEMENT 5 Sheets-Sheet 2 N/mTm MS l N S N Y O A E TU M A r S R AS 0 J E ww w mV @A April 16, 1968 Filed April 6, 1965 A ril 16, 1968 Filed April 6. 1965 ROLF VON ALT ETAL 3,378,061

CONTINUOUS CASTING ARRANGEMENT 5 Sheets-Sheet 3 INVENTORS ROLF VON ALT KLAUS VIESSMANN BY April 16, 1968 ROLF VON ALT ETAL 3,373,061

CONTINUOUS CASTING ARRANGEMENT Filed April 6, 1965 5Sheets-Sheet 4 /53a fwd INVENTORS. ROLF VON ALT Fl 6 4 By KLAUS VIESSMANN ATTORNEYS United States Patent 3,378,051 CONTINUOUS CASTING ARRANGEMENT Rolf Von Alt, Remscheid-Luttringhausen and Klaus Viessmann, Kornwestheim, Germany, assignors to Krel'dlers Metallund Drahtwerke G.rn.b.H., Stuttgart-Zulfenhausen, Germany Filed Apr. 6, 1965, Ser. No. 450,570 Claims priority, application Germany, Apr. 7, 1964, K 52,591 16 Claims. (Cl. 164-156) ABSTRACT OF THE DISCLOSURE A continuous casting installation wherein a control means is operatively connected to the tilting means of a container for automatically actuating the latter successively through a series of cycles each of which includes a tilt interval during which the container is tilted in the given direction through a given increment and a dwell interval during which the container remains at the inclination to which it has been tilted during the tilt interval. This control means responds automatically to the elevation of the surface of the molten material at the receiving end of the mold for determining the ratio between these intervals of each cycle.

The present invention relates to continuous casting installations.

As is well known, in continuous casting installations material in a molten state is poured from the spout of a suitable container into the open receiving end of a mold in which the molten material solidifies while it is continuously advanced through the mold. The container for the molten material is tilted from time to time so as to deliver additional molten material into the mold as the solidified material advances therethrough.

It is already known, in an installation of the above type, to control the periodic tilting of the container for the molten material in accordance with the elevation of the surface of the molten material in the mold. Customarily the periodic tilting of the container for the molten material is brought about when the elevation of the surface of the molten material in the mold moves below a given elevation. In one known installation, for example, an arbitrarily adjustable timer is provided for determining the time interval during which the container is tilted While a second timer which commences to operate at the same instant as the first timer but which has a longer time interval than the first timer will automatically prevent a second tilting of the container'during the time interval which elapses from the expiration of the time interval determined by the first timer until the expiration of the time interval determined by the second timer. Both of these timers are set into operation when the surface of the molten material reaches a given lower limit, and the actuation of the timers is automatically brought about by electrical contacts which move up and down or by a suitable float control which floats on the surface of the molten material at the mold.

It has been found in practice that installations of the above type provide an exceedingly coarse control of the elevation of the surface of the molten material in the mold. These installations provide undesirably large fluctuations in the elevation of the surface of the molten material in the mold, with the result that even though the mold is provided with a height intended to compensate for these fluctuations, nevertheless the casting which issues from the mold does not have a uniform structure which would be achieved from uniform solidifying conditions in the mold. It has, therefore, been attempted to provide a finer control, with a device which has vertically movable contacts, by providing for the tilting of the container of the molten material two dilferent time periods depending upon whether the contacts are out of engagement with each other for a relatively short period of time while the contacts are in an upper position or whether they are out of contact with each other for a longer period of time while in a lower position. However, as yet it has not been possible to reduce the fluctuations in the elevation of the surface of the molten material in the mold to the desired extent.

It is therefore a primary object of the present invention to provide a continuous casting installation of the above type which makes it possible to reduce the fluctuations in the elevation of the surface of the molten material in the mold to an extent which is far greater than has heretofore been possible.

It is also an object of the present invention to reduce the time during which the surface of the molten material fluctuates in elevation to an extent greater than has heretofore been possible.

In particular, it is an object of the present invention to provide a continuous casting installation capable of automatically responding to the elevation of the surface of the molten material in the mold for controlling the tilting of a container from which the molten material pours into the mold in a manner which will achieve the above objects.

The objects of the present invention also include a continuous casting structure which will reliably prevent the possibility of the mold being left without any molten material therein during operation of the continuous casting installation.

The objects of the present invention also include the provision of a continuous casting installation which will reliably prevent rising of the elevation of the surface of 'the molten material in the mold to an undesirably high elevation.

Furthermore, the objects of the present invention include the provision of an exceedingly simple structure which will respond to variations in the elevation of the surface of the molten material in the mold for accurately actuating the control structure of the invention to bring about the required addition of molten material to the mold in a manner which will achieve the above objects.

Also, the objects of the present invention include the provision of an apparatus which while being quite simple and rugged nevertheless is capable of reliably responding to the control structure of the invention for delivering the molten material to the mold in a manner which will achieve the above objects of the present invention.

The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a highly simplified schematic illustration of an installation which incorporates the basic principles of the present invention;

FIG. 2 is a schematic, fragmentary partly sectional illustration of part of the mechanical structure of an installation which has been operated successfully according to the present invention;

FIG. 3 is a schematic illustration of light-responsive units and mechanical and electrical structure associated therewith to achieve part of the controls of the present invention;

FIG. 4 shows the details of a multivibrator which forms part of the control means of the invention; and

FIG. 5 schematically illustrates hydraulic structure of the invention together with electrical controls therefor,

3 FIG. 5 together with FIGS. 2-4 showing the details of a structure which has proved to be successful in practice.

Referring to the schematic illustration of FIG. 1, the positive bus bar is electrically connected through a conductor 18 with a multivibrator 19 which forms part of the control means of the invention and which has its negative conductor 28 electrically connected to the negative bus bar 30. Moreover, a conductor 21 serves t electrically interconnect the positive bus bar 15 Mb a solenoidoperated switch 55 which in one position will connect the positive bus bar 15 to the conductor 56 which is electrically connected with the solenoid 24a of a solenoid valve 24 and which in another position will connect the bus bar 15 with the conductor 57 which is electrically connected with the solenoid 25a of a solenoid valve 25, so that the solenoids 24a and 252 can be alternately connected with the positive bus bar 15. Both of the

solenoids

24a and 25a are electrically connected through the conductor 58 with the negative bus bar 30.

The left branch of the multivibrator 19 of FIG. 1 serves the function of controlling tilt intervals of a container of the molten material, these tilt intervals being maintained substantially constant for all of the successive operating cycles of a tilting means which is described below. This left branch of the multivibrator 19 is'provided with the emitter 43 of the transistor 44 as well as with the collector circuit 45 and the base circuit 46 of the transistor 44. This base circuit 46 includes a fixed resistor 46a and a fixed capacitance 47. The collector circuit 45 is provided with a resistor 48.

The right branch of the multivibrator 19 cf FIG. 1, which serves to determine variable dwell intervals which alternate with the tilt intervals of the container for the molten material, includes an emitter circuit 49 connected with the transistor 50. This right branch also includes the collector circuit 51 and the base circuit 52 which is provided with the resistor 52a and with the variable capacitor 53. The capacitor 53 is actuated, in response to variations in the elevation of the surface of the molten material at the receiving end of the mold, in such a way that as the elevation of the surface of the molten material in the mold rises the capacitance of the variable capacitor 53 also rises. The collector circuit 51 is provided with the solenoid 54 which is operatively connected to the switch 55 so as to control the position thereof.

The tilta-ble container for the molten material is tilted with a tilting means which includes the cylinder 4 shown at the upper right of FIG. 1 and containing a hydraulic liquid which acts to displace a piston within this cylinder.

The hydraulic tilting means also includes a conduit 59 which communicates with the cylinder 4 so as to deliver the hydraulic liquid thereto as well as to permit the hydraulic liquid to flow out of the cylinder 4, and this conduit 59 communicates with the reservoir 60 which may contain a hydraulic liquid such as oil. A pump 61 is connected to the conduit 59 so as to pump the liquid from the reservoir 60 along the conduit 59 into the cylinder 4, and a valve 25 is located in the conduit 59 to open and close the latter. A second conduit 65 communicates with the conduit 59 as well as with the reservoir 60 to form a return flow conduit for the hydraulic liquid, and this return flow conduit 65 is provided with a valve 24 which opens and closes the conduit 65. These

valves

24 and 25 are actuated by the

solenoids

24a and 25a, respectively.

Assuming now that initially the base circuit 46 of the left branch of the multivibrator 19 is suppied with current, then the collector current flows through the resistor 48 without any power output, and this operation will continue until the capacitor 47 of the base circuit is charged by the base current. During this time the solenoid 54 is without any current. As a result an unillustrated spring holds the armature of the solenoid in a position displaced to the right from the position thereof shown in FIG. 1, so that the switch 55 is now in the dotted line position of FIG. 1, and thus at this time the conductor 57 is connected to the positive bus bar 15 so that the solenoid 25a is energized. When the solenoid 25a is energized its armature is pulled to the left, as viewed in FIG. 1, in opposition to an unillustrated spring, so that the valve 25 will be shifted to the left from the position thereof shown in FIG. 1 to a position where this valve 25 will open the conduit 59. In the position illustrated in FIG. 1 the solenoid 25a is unenergized and the valve 25 is in a position closing the conduit 59 so that no oil can flow to the cylinder 4. However, when the solenoid 25a is energized oil will flow through the open valve 25 to the cylinder 4. Of course, when the switch 55 is in the dotted line position of FIG. 1 the solenoid 24a is disconnected from the circuit and is unenergized, so that the spring which is connected to the armature of the solenoid 24a shifts the valve 24 to the right to its closed posi;ion where the return flow conduit 65 is closed. Therefore, at this time the pump 61 will deliver oil under pressure from the reservoir 60 through the valve 25 along the conduit 59 to the cylinder 4 so as to raise he piston therein and tilt the container which contains the molten material, as will be apparent from the description below.

However, when the base circuit 46 no longer has any current flowing therethrough, after charging of the capacitor 47, so that the left branch of the multivibrator 19 no longer operates, the right branch of the multivibrator comes into operation, and this latter operation continues until the flow of current through the base circuit of the right branch terminates after charging of the variable capacitor 53. During this interval the solenoid 54 is energized so as to displace the switch 55 to the solidline position shown in FIG. 1, and thus the solenoid 24a is energized so as to pull the valve 24 to the left to the position illustrated in FIG. 1 where the return flow conduit 65 is open. Of course, at this time the solenoid 25a is unenergized so that the unillustrated spring returns the valve 25 to its illustrated closed position closing the supply conduit 59 of the cylinder 4. Therefore, the tilting of the container for the molten material is interrupted by the closing of the conduit 59 and the container dwells at the inclination to which it was previously tilted. The duration of the dwell interval is the same as the duration of time required for charging of the variable capacitor 53, and this latter period of time is determined by the instantaneous position or capacitance of the capacitor 53. The capacitance of the variable capacitor 53 is determined by the elevation of the surface of the molten material within the receiving end of the mold. Upon termination of the charging of the variable capacitor 53, the right branch of the multivibrator 19 stops operating and the left branch again comes into operation. Thus, the dwell interval in the tilting of the container is terminated and the container is again tilted through a further angular increment, so that with the control means of the invention the tilting means is actuated to operate through a succession of cycles each of which includes a tilt interval followed by a dwell interval.

It is apparent that with the above-described controls of the tilting means which tilts the container for the molten material, the fluctuations in the elevation of the molten material at the receiving end of the mold will take place at a much slower rate and will have smaller amplitudes than in the case where, as has heretofore been conventional, the pouring of additional molten material into the mold is initiated merely in response to lowering of the elevation of the surface of the molten solid in the mold below a given lower elevation limit.

In FIGS. 2-5 are illustrated details which have proved to be successful in practice, and those parts which are illustrated in FIGS. 2-5 and which correspond to parts shown in the simplified schematic illustration of FIG. 1 are indicated by the same reference characters increased by 100. In the illustrated examples the variable capacitor in the base circuit of the transistor assembly of the multivibrator branch which determines the dwell intervals takes the form of a plurality of capacitors which are connected in parallel and which are connected into or cut out of the circuit by means of a light-operated assembly which responds to the momentary elevation of the surface of the molten material at the receiving end of the mold for controlling the connection of the plurality of capacitors into or out of the circuit. Moreover, the structure includes a pair of timers which, when the cyclical operation is interrupted in the manner described below, serve to initiate a tilting of the container of the molten material toward an upright position and then to initiate a tilting of the molten material container back toward its tilted position, these timers respectively responding to movement of the surface of the molten material at the receiving end of the mold above a given upper limit and below this latter given upper limit.

Referring to FIG. 2, the mechanical parts, insofar as they are pertinent to the present invention, include the container 101 for the molten material which is to be poured into the receiving end of the mold. This container 101 may take the form of a tilt-furnace in which the solid material is heated so as to be placed in a molten condition and so as to be maintained in this molten condition, although, if desired, the container 101 could also take the form of a simple ladle into which the molten material is poured so as to be transferred from the container 101 into the mold. The container 101 has a pouring spout 102 which is mounted for turning movement about a horizontal axis. Thus, a pivot means 103 is operatively connected with the pouring spout 102 so as to mount the container 101 for tilting movement about the horizontal axis determined by the pivot means 103. In order to tilt the container 101, a tilt means is provided, and this tilting means is hydraulic and includesthe cylinder 104 which receives a hydraulic liquid under pressure. A piston 104a is slidably received within the cylinder 104 and is pivotally connected at 105 to the container 101. It will be noted that this connection of the hydraulic tilting means 104 to the container 101 is situated at the side of the container 101 which is opposite from the tilting axis thereof. The mold structure includes, at the receiving end of the mold, an elongated trough or runner S aligned with the spout 102 so that the latter is oriented with respect to the mold to direct the molten material into the receiving end of the mold when the container 101 is tilted in a clockwise direction, as viewed in FIG. 2. The right end of the runner 106 discharges directly into the open top end of the mold 107 which is of a conventional construction. The molten material at the receiving end of the mold has the surface 108 on which a float 109 is located, this float being made of a material which will not melt at the molten temperature of the material in the receiving end of the mold. The float 109 forms part of the control means and carries an opaque plate 110 which is situated in the region of the lightoperated assembly 111. The molten material in the mold 107 will, as is well known, solidify therein, and in a manner which is well known in the art and which is not illustrated since it forms no part of the present invention, the solidified material in the mold moves along the intetior thereof at a substantially constant rate, so that an elongated solid body of metal of predetermined cross sectional confi uration will continuously discharge from the mold. Of course, instead of orienting the spout 102 of the container 101 with respect to the receiving end of a single mold so as to direct the molten material into the latter mold, it is possible to orient the spout 102 with respect to a header which receives the molten material and rom which the molten material flows to a plurality of molds.

FIGS. 3-5 illustrate the electrical and hydraulic details of the structure.

Referring to FIG. 3, it will be seen that the positive pole of a power supply unit 112, which serves to maintain the voltage constant, is connected to a main switch 113 which in turn is electrically connected to a selecting switch 113a which enables the operator to select between manual and automatic operation. Thus, the selecting switch 113a can be manually placed either in electrical connection with the positive bus bar 114, to provide hand operation, or in electrical connection with the positive bus bar 115 to provide automatic operation. The main switch 113 additionally serves to connect the positive pole of the power supply unit 112 to a conductor 116. The

conductors

117, 118, 120, 121, 122, and 123 are electrically connected with the positive bus bar 115.

The conductor 116 is electrically connected with a plurality of

lamps

126, 126a, 126k 126g of the lightoperated assembly 111, and it will be noted that these lamps are arranged in a vertical row. The conductor 116 is also connected electrically with a light-responsive unit 127g of the light-operated assembly 111, and it will be noted that this latter light-responsive unit is horizontally aligned with the lamp 126g, so that if there is no interruption in the light path from the lamp 126g to the unit 127g, the latter will receive light from the lamp 126g. The parts are shown in FIG. 3 in a position where the opaque plate interrupts the transmission of light from the lamp 126g to the unit 127g. A unit 142 carries a control lamp 142a, and this unit 142 is connected by the conductors 140g to the light-responsive unit 127g. When the latter receives light from the lamp 126g the unit 142 is energized to illuminate the lamp 142a. The unit 142 forms an indicating means which by illumination of or extinguishing of the lamp 142a indicates to the operator certain information with respect to the installation, as will be apparent from the description below. The several lamps 126, 126:: 126g as well as the light-responsive unit 127g are electrically connected to the negative pole of the power supply unit 112 through a conductor 128. Thus, it will be seen that this conductor 128 is electrically connected with the negative bus bar 130 which is in turn connected to the negative pole of the power supply unit 112.

The conductor 117 electrically connects the positive bus bar with the several light-

responsive units

127, 127a 127; which are arranged in a vertical row above the lowermost unit 127g, and it will be noted that the several light-

responsive units

127, 127a 127 are respectively in horizontal alignment with the

lamps

126, 126a 126 so as to respectively receive light therefrom unless the light paths are interrupted by the opaque plate 110. This opaque plate 110 is of course situated in a vertical plane which extends between the vertical rows of lamps and light-responsive units, and the plate 110 moves vertically within this plane in response to changes in the elevation of the surface 108 of the molten material at the receiving end of the mold 107. The negative conductor 129 for the light-

responsive units

127, 127a 12'7f is connected to the negative bus bar 130. The

conductors

120, 121, 122, and 123 are electrically connected with the

solenoids

124a and 125a which control the

valves

124 and 125 which form part of the hydraulic assembly of the installation, as indicated in FIG. 5. The conductor 118 serves to connect the multivibrator 119 into the electrical circuit (FIG. 4), and the negative conductor for the multivibrator 119 is formed by the conductor 123.

The

several units

127, 127a 127i receive light from the

lamps

126, 126a 1267, respectively, and convert the light impulses into electrical impulses. The uppermost unit 127 is connected by conductors 131 and 132 with

timers

133 and 134, respectively, and the timer 133 is automatically set into operation when the opaque plate 110 interrupts the path of light from the lamp 126 to the unit 127 while the timer 134 is set into operation when the light from the lamp 126 can again reach the unit 127, which is to say when the upper edge of the plate 110 moves below the elevation of the light path from the lamp 126 to the unit 127. When the timer 133 is energized it actuates the

switches

135 and 136 connected with the

conductors

120 and 122, while when the timer 134 operates the

switches

137, 138, and 139 which are connected with

conductors

120, 121, and 123, respectively, are actuated (see FIG. also). The several light-responsive units 127a, 127b 127 which respectively receive light from the lamps 126a, 126b 126f are respectively connected by conductors 140a, 1401) 140 to the solenoids 141a, 141b 141] (FIG. 4), and these solenoids serve to actuate switches for connecting the several capacitors of the variable capacitor into or out of the circuit.

As may be seen from FIG. 4, the variable capacitor includes the

several capacitors

153, 153a, 153b 153) all of which are connected in parallel. The solenoids 141a, 141b 141i when they are energized will connect the capacitors 153a, 153b 153 into the circuit, respectively, and, of course, when the solenoids 141a, 141b 141i are unenergized the capacitors 153a, 153b 153 will be cut out of the circuit. In the illustrated position of the parts the capacitor 153i is connected into the circuit, and it will be noted from FIG. 3 that the opaque plate 110 interrupts the path of light from the lamp 126i to the light-responsive unit 127 The several light-

responsive units

127, 127a 127g may take any well known construction which will open or close a circuit in response to receiving light or in response to an interruption in the transmission of light. For example, each of these units may include a photocell and a moving coil instrument, such as a galvanometer, connected to the photocell so that the moving coil will swing in one direction when light is received by the photocell and in an opposite direction when the transmission of light is interrupted. When the photocell of the unit 127g receives light, the moving coil of this unit will swing to a position where it closes a switch for closin the circuit of the lamp 142a so that this lamp is illuminated when the unit 127g receives light from the lamp 126g. When the light transmission to the unit 127g is interrupted, the mo ing coil is turned by a spring thereof back to a rest position where the switch is opened and thus the lamp 142a is extinguished.

In the case of the units 127a 127], the moving coil of each of these units, when it is in its rest position where the photocell does not receive light, closes a switch so as to energize the corresponding solenoid 141a 141). When light is received by any of the units 127a 127 the moving coil thereof is swung to apposition opening the switch so as to deenergize the corresponding solenoids 141a 141 Thus, it will be noted that in the illustrated position of the parts all of the solenoids 141a 141:: are unenergized, and all of the units 127:: 127a receive light from the lamps 126a 1262, respectively. Since the transmission of light to the unit 127f is interrupted, the switch of this unit is closed and thus the solenoid 141i is energized to connect to the capacitor 153 into the circuit of the multivibrator 119.

The uppermost unit 127 includes a pair of switches which are actuated by the moving coil in both of its end positions. When the transmission of light from the lamp 126 to the unit 127 is interrupted the moving coil automatically is displaced by the spring connected thereto to its rest position closing a switch which initiates the operation of the timer 133. This timer 133 includes a clockwork, for example, which operates for a given period of time and then automatically stops operating and opens a switch so as to terminate the operation of the timer 133 automatically after it has operated for the predetermined period. When the timer is operating, the closed switch thereof energizes a solenoid which displaces the

switches

135 and 136 to their closed positions, respectively, and at the end of the predetermined period of time for which the timer 133 is set, the solenoid thereof becomes unenergized and a spring which is connected to the armature'ot this latter solenoid displaces the arma- 8 ture to the position illustrated in FIG. 3 where the switches and 136 are open.

When the transmission of light from the lamp 126 to the unit 127 is resumed, the moving coil swings to its other end position to close a second switch which energizes the timer 134 which now starts to operate for the particular period of time for which this timer is set, and in the same way the energizing of the timer 134 will close a switch thereof so as to energize a solenoid which opens the

switches

137 and 138 and closes the switch 139. After the time for which the timer 134 is set has elapsed, the solenoid of the timer becomes unenergized and the spring which is connected to the armature of the solenoid returns the armature to the position illustrated in FIG. 3 where the

switches

137 and 138 are closed While the switch 139 is opened.

The multivibrator 119 of FIG. 4 has the branches which respectively determine the tilt intervals and the dwell intervals of the operating cycles of the tilting means 104 which serves to tilt the container 101. The left branch of FIG. 4. includes the emitter circuit 143, the transistor 144, the collector circuit and the base circuit 146, and it is this branch which controls the tilt intervals of the several operating cycles. The tilt intervals of all of these cycles are of identical duration, and therefore the base circuit 146 includes, in addition to the resistor 146a, the fixed capacitance 147. The potential is consumed by the resistor 148 in the collector circuit 145.

The right branch of the multivibrator 119 of FIG. 4 includes the emitter circuit 149, the transistor 150, the collector circuit 151, and the base circuit 152. This branch of the multivibrator controls the dwell intervals of the several operating cycles of the tilting means, in such a way that in accordance with the particular elevation of the surface 108 of the molten material in the mold 107 a shorter or longer dwell interval will be provided for each cycle which consists of a tilt interval followed by a dwell interval. The base circuit 152 includes the capacitor 153 as well as the resistor 152a, and the several capacitors 153a, 153b 153f which are connected in parallel with the capacitor 153 and which are controlled by the solenoids 141a, 141b 141 respectively, as described above. The greater the number of capacitors which are connected into the circuit, the greater is the total capacitance and thus the greater the dwell interval. The circuit is so arranged that when the light from the second lowermost lamp 126 is interrupted by the opaque plate 110, the first additional capacitor 153 will be connected into the circuit, while when the light from the third lowermost lamp 126a is interrupted, the second additional capacitor 1532 will be connected into the circuit, and so on. The collector circuit 151 includes the solenoid 154 which controls the switch 155. This switch 155 willserve to al ternately connect the conductor 121 to the conductor 156 of the solenoid 124a and to the conductor 157 of the solenoid 125a (FIG. 5). In this way the container 161 is tilted or maintained in its tilted position. Whenever the collector circuit 151 of the right branch of the multivibrator receives current, the solenoid 154 is energized so as to place the switch 155 in the solid-line position shown in FIG. 4 where the conductor 156 will serve to energize the solenoid 124a, and this position of the switch 155 is of the base circuit to charge the particular capacitors 153, V

153 153e which happen to be connected into the circuit. The conductor 158 serves to connect the

solenoids

124a and 125a to the negative bus bar 130.

As may be seen from FIG. 5, the solenoid valve 125 is situated in the conduit 159 through which the oil is pumped from the reservoir 160, by the pump 161, to the cylinder 104. The conduit 159 includes a non-return valve 162, and between the valve 162 and the pump 161 is a safety valve 164 which automatically opens when the pressure exceeds a certain limit so that the oil will then flow through the safety valve to the return flow conduit 163 which returns the oil back to the reservoir 160. Between the non-return valve 162 and the solenoid valve 125, the conduit 159 is in communication with the return flow conduit 165 to which the solenoid valve 124 is connected. Between the valve 125 and the cylinder 104 the conduit 159 communicates with an additional return flow conduit 166 which is provided with a manually operable valve 167 as well as with a solenoid valve 168. The valve 168 is actuated by a solenoid 168a which is connected to the positive bus bar 114 by the conductor 169, this bus bar 114 being used for manual operation. The conductors 170 and 158 serve to connect the solenoid 168a to the negative bus bar 130. An additional conductor 171 electrically connects the solenoid 125a to the bus bar 114, so that the valve 125 can be manually operated.

When the switch 113a is placed by the operator in the solid line position shown in FIG. 3, the installation is set for automatic operation and the solenoid 168a does not receive any current. The spring which is connected to the armature of this solenoid displaces the armature to the illustrated position where the valve 168 closes the conduit 166. On the other hand, if the operator places the switch 113a in the dotted line position shown in FIG. 3, then the bus bar 114, which is provided for hand operation, receives current and the bus bar 115 for the automatic operation does not receive any current, and at this time the solenoid 168a is energized so as to pull the valve 168 to its open position where oil can flow through the conduit 166. At the same time the solenoid 124a becomes unenergized and the solenoid 125a is energized by way of the conductor 171. The deenergizing of the solenoid 124a displaces the valve 124 to its closed position, while the energized solenoid 125a displaces the valve 125 to its open position. As a result, the pump 161 can deliver oil to the cylinder 104 so as to raise the piston 104a for tilting the container 101, and by manual operation of the valve 167 the rate of return of the oil to the reservoir 160 can be regulated at this time, so that it is possible by operation of the valve 167 to control the tilting movement of the container 101 manually.

Therefore, in order to start the operation of the continuous casting installation, the main switch 113 is closed and the manually operable selecting switch 113a is placed in the dotted line position of FIG. 3 for manual operation of the installation, and the container 101 is tilted in a manner controlled by operation of the valve 167, so that the continuous casting operations can commence. The tilting of the container 101 is continued until the surface 108 of the molten material in the mold 107 rises to an elevation where the float 109 situates the opaque plate 110 in the path of light from the lamp 126g to the unit 127g of the light-operated assembly 111. The interruption in the transmission of light to the unit 127g at this time will extinguish the indicating lamp 142a, so that the operator knows that the surface 108 has reached an elevation where the operator can move the switch 113a to the solid line position of FIG. 3 for automatic operation. From the moment when the operator notices that the lamp 142a is extinguished until the switch 113a is placed in the solid line position of FIG. 3 the molten material will of course continue to flow into the mold, and in this way the surface 108 will continue to rise until it has an elevation, approximately, where the opaque plate 110 also interrupts the path of light from the lamp 126] to the unit 127 f.

The movement of the switch 113a to the automatic position has of course interrupted the flow of current through the bus bar 114, so that the solenoid 168a is unenergized and the valve 168 closes the return fiow conduit 166. On the other hand, the bus bar 115 is now connected into the circuit, with the result that the solenoid 141 becomes energized by the interruption in the transmission of light to the unit 127f, so that in the base circuit 152 of the right branch of the multivibrator 119 the first additional capacitor 153f is connected in parallel with the capacitor 153.

Assuming that the right branch of the multivibrator 119 first comes into operation, then the current will flow through the collector 151 until the current of the base circuit has charged both

capacitors

153 and 153 The solenoid 154, therefore, pulls the switch 155 to the solid line position shown in FIGS. 4 and 5, with the result that the solenoid 124a is energized through the conductor 156. The valve 124 is therefore pulled to the left, as viewed in FIG. 5, to its open position where the oil pumped by the pump 161 can return to the reservoir 160 through the return flow conduit 165. On the other hand, at this time the solenoid 125a is unenergized so that the valve 125 remains in its closed position preventing delivery of oil through the conduit 159 to the tilting means 104. Therefore, at this time the oil simply circulates from the pump back to the reservoir 160. It is to be noted that since the

valves

125 and 168 are both closed at this time, no oil can flow out of the cylinder 104, so that the container 101 dwells at its tilted position.

This dwell interval is automatically maintained until both of the

capacitors

153 and 153 are charged. Then the current of the base circuit of the right branch of the multivibrator 119 is interrupted. The collector 151 and thus the solenoid 154 no longer are supplied with current, so that the switch 155 automatically is displaced to the dotted-line position shown in FIGS. 4 and 5. As a result the solenoid 124a becomes unenergized and the valve 124 returns to the right, as viewed in FIG. 5, to its position closing the return flow conduit 165. The solenoid 125a is simultaneously energized through the conductor 157, and thus the valve 125 is displaced to the left, as viewed in FIG. 5, to its open position permitting the oil to be pumped through the conduit 159 to the cylinder 104 so that the container 101 is further tilted. This tilt interval continues as long as the right branch of the multivibrator 119 does not operate while the left branch continues to operate, which is to say until the capacitance 147 in the base circuit 146 becomes charged. As soon as the charging of the capacitor 147 is completed, the right branch of the multivibrator 119 commences to operate so that the container 101 remains in the position to which it has been tilted, until the capacitor 153 and whatever additional capacitors 153 153e according to the elevation of the surface 108, become charged. Then the next cycle commences with a tilt interval of a duration equal to the previous tilt interval followed by a dwell interval determined by the elevation of the surface 108. Thus, with the structure of the invention, the fixed capacitance of the capacitor 147 will provide for each operating cycle a predetermined tilt interval which is identical for all of the cycles, while the dwell intervals of the several cycles will be determined by the particular number of parallel-connected capacitors which are connected into the circuit of the right branch of the multivibrator 119. Of course, this latter factor will be determined by the elevation of the surface 108 of the molten material at the receiving end of the mold 107.

In order to guarantee that the installation will not operate without any molten material in the mold 107, the structure is designed so that the tilt intervals and dwell intervals have with respect to each other a relationship which will result in a gradual rise in the elevation of the surface 108 during the operation of the tilting means through successive cycles. When the surface 108 reaches an elevation where the opaque plate 110 interrupts the path of light from the lamp 126 to the unit 127, the timer 133 is automatically set into operation, and the

switches

135 and 136 are closed at this time. Therefore, irrespective of the particular position of the switch when the path of light from the lamp 126 to the unit 127 is interrupted, the solenoid 124a will be energized and the valve 124 will be opened and will remain in its open position for the period of time which is determined by the timer 133. Thus, as may be seen from FIG. 5, the closing of the switch 135 electrically connects the bus bar 115 through the conductor 156 to the solenoid 124a. At the same time the solenoid 12511 is also ener gized, since the switch 136 serves to connect the conductor 122 to the solenoid 125a. Therefore, during operation of the timer 133 the valve 125 is also maintained in its open position. The result is that the pump 161 not only is no longer capable of pumping oil to the cylinder 104, but in addition the oil can flow from the cylinder 104 back into the reservoir 160. Therefore, the weight of the container 101 will displace the piston 104a back into the cylinder 104 while oil flows out of the latter back through the

conduits

159 and 165 to the reservoir 160, and thus the operation of the timer 133 serves to actuate the tilting means 104 to tilt the container 101 back toward its upright position. Therefore, as long as the timer 133 operates the container 101 tilts back toward its upright position and the cyclical operation of the tilting means is interrupted for a substantial period of time. Because the flow of molten material to the mold 107 is interrupted, while the solidified material therein continues to move at the same rate through the mold, the elevation of the surface 108 rapidly drops, and the opaque plate 110 will also drop, so that when the upper edge of the plate 110 moves below the path of light from the lamp 126 to the unit 127, this unit 127 again receives light and thus the timer 134 will be set into operation, in the manner described above.

In most cases the time required for the top edge of the plate 110 to move down to the elevation of the lamp 126 will be greater than the period for which the timer 133 is set, so that by the time the transmission of light to the unit 127 is resumed, the timer 133 has stopped operating and the

switches

135 and 136 have been opened, so that the tilting of the container 101 back toward its upright position has terminated. If at this time the switch 155 is in the solid line position of FIG. 5, then the valve 125 is closed and the valve 124 remains open, so that the oil which is pumped by the pump 161 will flow through the conduit 165 back into the reservoir 160. However, if at this time the switch 155 is in the dotted line position of FIG. 5, then the valve 125 will be open while the valve 124 will be closed. The container 101 therefore begins its stepwise tilting movement, or, in other words, until the moment when the relay 134 is actuated the control of the operation by the multivibrator is resumed with the longest dwell intervals being provided between the tilt intervals, inasmuch as the elevation of the opaque plate 110 is such that all of the lamps have the transmission of light therefrom to the light-responsive units interrupted. However, there will Ibe no delivery of molten material to the mold because the container 101 has previously been returned to a substantially upright position. Therefore, this tilting operation will take place just for the time required for the continuous casting operations to lower the elevation of the surface of the molten material until the top edge of the opaque plate 110 is low enough to permit light again to reach the uppermost unit 127 from the uppermost lamp 126.

The resumption in the transmission of light to the unit 127 from the lamp 126 when the top edge of the opaque plate 110 reaches the lamp 126 will cause the timer 134 to be set into operation, as pointed out above, with the result that the

switches

137 and 138 are opened and the switch 139 is closed, for the period of time which is determined by the timer 134. The opening of the switch 138 will of course prevent energizing of the solenoid 124a, irrespective of the position of the switch 155, so that the return flow conduit 165 is automatically closed upon initiation of the operation of the timer 134. On the other hand, the closing of the switch 139 energizes the solenoid 125a, so that the valve 125 opens and the oil can now be pumped back into the cylinder 104, so that the tilting of the container 101 again in a clockwise direction, as viewed in FIG. 2, takes place, but it is to be noted that during the initial tilting of the container 101 at this time the flow of molten material to the mold 107 may not be immediately resumed, so that the surface 108 will continue to drop until the container 101 reaches a position where the molten material starts to flow back into the mold 107. The tilting of the container 101 in the same direction in which it is tilted during the tilt intervals of the several cycles during cyclical operation continues for a period of time which is determined by the setting of the timer 134. The

timers

133 and 134 are adjusted so that at the end of the operation of the timer 134 the surface 108 will have an elevation below the intermediate or average elevation of this surface during operation, so that at the end of the operation of the timer 134 the surface 108 is situated at an elevation where, for example, the light from the lamp.

126e to the unit 1272 is still interrupted. Of course, if it should happen that the top edge of the opaque plate 110 moves down to the elevation of the lamp 126 before the period of operation of the timer 133 has expired, then the opening of the switch 137 will still guarantee that the solenoid 124a will become unenergized even though the switch 135 should'happen to be closed at this instant, and thus the operations initiated by the start of the operation of the timer 134 will still be carried out in the above described manner. Of course, while the switch 136 energizes the solenoid a, this solenoid 125a will remain energized upon opening of the switch 136 because the switch 139 will be closed during operation of the timer 134.

As soon as the timer 134 stops operating the

switches

137 and 138 close while the switch 139 opens, and the timer 133 will under all circumstances have terminated its operation before the termination of the operation of the timer 134. At the instant when the timer 134 stops operating, the multivibrator 119 again comes into operation, so that the cyclical operation of the tilting means with a predetermined tilt interval and a variable dwell interval at each cycle again starts. Only when the surface 108 again reaches an elevation where the opaque plate 110 interrupts the path of light from the lamp 126 to the unit 127 is the cyclical operation again interrupted so that the container 101 will again turn back toward its upright position and will then be tilted back toward its tilted position, in the manner described above.

We claim:

1. In a continuous casting installation, a mold having an open receiving end for receiving material which is in a molten state, which is adapted to solidify in said mold, and which is adapted to :be moved during solidification at a substantially constant rate along the interior of said mold, a container for the molten material, said container having a discharge spout oriented with respect to said receiving end of said mold to discharge the molten material into said receiving end of said mold upon tilting of said container in a given direction, tilting means operatively connected to said container for tilting the latter in said direction, and control means operatively connected to said tilting means for automatically actuating the latter successively through a series of cycles each of which consists of a tilt interval during which said container is tilted in said direction through a given increment and a dwell interval during which said container remains at the inclination to which it has been tilted during said tilt interval, said control means responding automatically to the elevation of the surface of the molten material at said receiving end of said mold for determining the ratio between said intervals of each cycle.

2. In a continuous casting installation as recited in claim 1, said control means providing substantially identical tilt intervals for all of said cycles and providing for said cycles dwell intervals whose duration is determined according to the elevation of the surface of the molten material in said receiving end of said mold.

3. In a continuous casting installation as recited in claim 1, said control means while determining said ratio between said intervals of each cycle according to the elevation of the surface of the molten material, also operating said tilting means to provide a gradually rising elevation of the surface of the molten material during the successive cycles of operation of-said tilting means.

4. In a continuous casting installation as recited in claim 3, said control means, when the elevation of the surface of the molten material moves upwardly beyond a predetermined upper limit, interrupting the successive cycles of operation of said tilting means and automatically actuating the latter to tilt said container in a direction opposite to said given direction back toward an upright position during a first predetermined time period and then actuating said tilting means to tilt said container again in said given direction during a second predetermined time period, and said control means then resuming the cyclical control of said tilting means, so that at least during said first time period the elevation of the surface of the molten material will drop.

5. In a continuous casting installation as recited in claim 4, said control means commencing said second time period during which said container is again tilted in said given direction in response to dropping of the elevation of the surface of the molten material to said upper limit.

6. In a continuous casting installation as recited in claim 1, said control means providing substantially constant tilt intervals for all of said cycles and providing for said cycles dwell intervals determined by the elevation of the surface of the molten material in said receiving end of said mold, and said control means also providing a gradual rise in the elevation of the surface of the molten material during operation of said tilting means through successive cycles of operation, said control means, when said surface of said molten material in said receiving end of said mold rises beyond a predetermined upper limit, automatically interrupting said cycles and actuating said tilting means to tilt said container in a direction opposite to said given direction during a first predetermined time period, so that the elevation of the surface of the molten material will drop during said first time period, and said control means responding to lowering of the elevation of said surface of said molten material to said upper limit for automatically tilting said container again in said given direction during a second predetermined time period, after which said control means automatically resumes the cyclical operation of said tilting means.

7. In a continuous castinginstallation as recited in claim 1, said control means including a multivibrator having a pair of branches one of which determines the tilt intervals and the other of which determines the dwell intervals of said cycles, said one branch of said multivibrator of said control means providing substantially constant tilt intervals for all of said cycles and the other branch of said multivibrator determining said dwell intervals according to the elevation of the surface of the molten material at said receiving end of said mold.

8. In a continuous casting installation as recited in claim 7, said control means actuating said tilting means for providing a gradual rise in the elevation of the surface of the molten material during actuation of said tilting means through said cycles, and said other branch of said multivibrator including a variable capacitance which automatically increases during a rise in the elevation of the surface of the molten material.

9. In a continuous casting installation as recited in claim 8, said other branch of said multivibrator including a transistor assembly provided with a base circuit which includes said variable capacitance.

10. In a continuous casting installation as recited in claim 1, said control means also actuating said tilting means to provide a gradual rise in the elevation of the surface of the molten material, and said control means, when said elevation passes above a given upper limit,

automatically interrupting the successive cycles of op eration of said tilting means and actuating the latter to tilt said container in a direction opposite to said given direction during a first predetermined time period and said control means then actuating said tilting means to again tilt said container in said given direction during a second predetermined time period, whereupon said control means resumes the cyclical operation of said tilting means, said control means including a first automatic timer which responds to movement of the surface of the molten material above said upper limit for initiating said first time period and a second automatic timer which responds to lowering of said elevation of said surface of said molten material to said upper limit for initiating said second time period.

11. In a continuous casting installation as recited in claim 1, said control means including a multivibrator hav- 1 ing one branch which determines the tilt intervals of said cycles and another branch which determines the dwell intervals of said cycles, said one branch of said multivibrator providing substantially constant tilt intervals for all of said cycles and said other branch of said multivibrator determining the dwell intervals in accordance with the elevation of the surface of the molten material at the receiving end of said mold, said other branch having a variable capacitance for determining said dwell intervals and said variable capacitance being composed of a plurality of electrically interconnected capacitances and a light-operated assembly for connecting given capacitances into or cutting said given capacitances out of said other branch, said light-operated assembly including a plurality of lamps situated in a vertical row and a plurality of light-responsive units also situated in a vertical row at the same elevations as said lamps, respectively, and a float member floating on the surface of the molten material and carrying an opaque plate situated in a vertical plane between said rows so that as the elevation of the surface of the molten material changes said opaque plate will interrupt given light paths extending from said lamps to said light-responsive units, said units being operatively connected with said capacitances for connecting them into or cutting them out of said other branch depending upon whether said units respectively receive light from said lamps.

12. In a continuous casting installation as recited in claim 11, said other branch including a transistor assembly provided with a base circuit which includes said variable capacitance, and said plurality of capacitances being connected in parallel, said light-responsive units responding to interruption in the receiving of light thereby for connecting capacitances respectively connected to said units into said other branch.

13. In a continuous casting installation as recited in claim 11, an additional lamp and light-responsive unit situated in horizontal alignment with each other respectively above said vertical rows of lamps and light-respon sive units, a pair of automatic timers operatively connected to said additional light-responsive unit to be actuated thereby, one of said timers being set into operation by movement of said plate into the path of light from said additional lamp to said additional light-responsive unit and the other of said timers being automatically set into operation during lowering of said plate beneath the path of light from said additional lamp to said additional lightresponsive unit so that said other timer starts operating when said additional light-responsive unit again receives light from said additional lamp, said control means responding to operation of said one timer for actuating said tilting means to tilt said container in a direction opposite to said given direction during the time period which is determined by said one timer and said control means actuating said tilting means to tilt said container again in said given direction during the time period determined by said other timer.

14. In a continuous casting installation as recited in claim 1, said tilting means including a hydraulic assembly operatively connected to said container for tilting the latter, and said hydraulic assembly including regulating elements which determine the operation of said hydraulic assembly and which are controlled by said control means.

15. In a continuous casting installation as recited in claim 1, manually operable means operatively connected to said tilting means for manually controlling the latter, and selecting means operatively connected to said control means and said manually operable means for rendering said control means inoperative and said manually operable means operative or said manually operable means inoperative and said control means operative at the option of the operator, so that the operator can select be tween automatic and manual operation of said tilting means.

16. In an installation as recited in claim 15, said tilting means being hydraulically actuated, and a hydraulic circuit including a pump for pumping hydraulic liquid to 2 said tilting means and a return flow conduit for receiving hydraulic liquid from said tilting means, and a manually operable valve in the latter return flow conduit for con- 1 trolling the rate of flow of liquid therethrough while said pump means pumps hydraulic liquid to said tilting means, said valve and return flow conduit forming part of said manually operable means so that by manipulating said valve the operator can manually control said tilting means.

References Cited UNITED STATES PATENTS 2,380,109 7/1945 Hopkins 164156 2,385,206 9/1945 Hopkins 164'156 2,905,989 9/1959 Black 164-281 2,962,778 12/1960 Peak et a1. 164156 FOREIGN PATENTS 728,144 4/1955 Great Britain.

1. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.