CA1264916A - Valve mechanism for metal casting machine - Google Patents
Valve mechanism for metal casting machineInfo
- Publication number
- CA1264916A CA1264916A CA000511200A CA511200A CA1264916A CA 1264916 A CA1264916 A CA 1264916A CA 000511200 A CA000511200 A CA 000511200A CA 511200 A CA511200 A CA 511200A CA 1264916 A CA1264916 A CA 1264916A
- Authority
- CA
- Canada
- Prior art keywords
- magnetic field
- molten metal
- pipe
- coil assembly
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/08—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like for bottom pouring
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D39/00—Equipment for supplying molten metal in rations
- B22D39/003—Equipment for supplying molten metal in rations using electromagnetic field
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Continuous Casting (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The flow of molten metals, for example, molten steel, from one location to another, typically from the ladle to the tundish and from the tundish to a casting machine of a steel continuous casting procedure, is controlled by the application of a magnetic field to the metal. A magnetic field-producing device surrounds a tube conveying the molten metal between two locations.
The magnetic field produces a restriction in the molten metal by interaction with eddy currents induced in the molten metal. The restriction is of variable cross-sectional dimension, depending on the strength of the magnetic field, and thereby controls the flow rate of the molten metal.
The flow of molten metals, for example, molten steel, from one location to another, typically from the ladle to the tundish and from the tundish to a casting machine of a steel continuous casting procedure, is controlled by the application of a magnetic field to the metal. A magnetic field-producing device surrounds a tube conveying the molten metal between two locations.
The magnetic field produces a restriction in the molten metal by interaction with eddy currents induced in the molten metal. The restriction is of variable cross-sectional dimension, depending on the strength of the magnetic field, and thereby controls the flow rate of the molten metal.
Description
12~49~6 VALVE MECHANISM FOR METAL CASTING MACHINE
he present invention relates to the casting of metals, particularly steel, and more particularly to a novel valve mechanism for utilization in such casting.
In the continuous casting of steel, molten steel from the ladle is fed into a tundish from where the molten steel is fed to a vertical or inclined mold in which the steel solidifies and from which it is removed as a solid bar for further processing.
lC The control of flow of molten steel from ladle to tundish and from tundish to mold often is non-existent, which leads to inconsistent flows, entrapment of air in the steel and contaminated product as a result.
One method of counteracting this problem has been 15 to employ variable flow valves at the exit of both the ladle and the tundish, which restrict the flows to maintain desired levels of molten steel in the mold and the tundish.
Such valves are conventionally constructed of 20 ceramic material and comprise a gate-like structure wherein an orifice in a sliding gate member is moved relative to an orifice in a fixed gate member to provide a variable volume opening through from one side of the two members to the other, thereby controlling the molten 25 metal flow.
The ceramic material of the gate valves tends to wear in use. Throttling ceramic gate valves tend to aspirate air which leads to steel contamination. The aspirated air may be replaced by an inert gas, such as 30 argon, but at considerable expense. Ultimately expensive replacement of the valves is required and, in the meantime, the expense of the use of the inert gas must be incurred. Even in the presence of the inert gas shroud, some air ingress occurs and product 35 contamination, therefore, is unavoidable.
p. ~, 126~916 2 It has previously been described in French Patent No, 2,467,730 that a stream of molten metal may be constricted by means of a coil surrounding a tube co~taining the molten metal provided that alternating current is passed through the coil at a frequency which is below the inverse of the product of the magnetic permeability of the molten metal, the electrical conductivity o~ the metal and the square of the radius of the metal after constriction. An electroconductive screen preferably also is provided, arranged concentrically of the coil and penetrating the coil from above, to provide a defined commencement of the constriction.
The present invention also utilizes a magnetic field-producing coil to achieve constriction of a metal stream and the constriction achieved thereby is employed to control the flow rate of molten metal from one vessel to another. The present invention lies in the specific method adopted and also in the equipment employed.
In accordance with one a~pect of the present invention, there is provided as apparatus for controlling the flow of molten metal through a pipe of fixed diameter, which comprises a tubular -oil assembly surrounding the pipe and capable of generating a magnetic field, a core surrounding and enclosing the tubular coil assembly at its radially-outer extremity and at its upper and lower ends, so as to confine and concentrate the magnetic field radially-inwardly of the tubular coil assembly, and means for applying an alternating current to the tubular coil assembly to generate the magnetic field, whereby the radially-inward confinement of the magnetic field causes molten metal flowing through the pipe to be constricted by the action of the magnetic field directly on the molten metal to a degree determined by the strength of the magnetic field.
;`
' ' G.
','`'.'~`~ ~
1~6~6 In the present invention, therefore, a tubular magnetic field-generating coil assembly is provided surrounding a pipe through which a molten metal flows and the coil is surrounded on its radially-outer side - ' and top and bottom by a suitable electromagnetic core.
In this way, the magnetic field produced by the coil is concentrated in the flow pipe. The magnetic field results in constriction of the rod of molten metal flowing through the pipe to a degree dependent on the strength of the field.
The present invention, therefore, provides a novel valve structure which does not require the use of moving parts and yet is effective in controlling the flow therethrough of molten steel or other molten metal, at 1~ any desired flow rate.
Since the present invention does not rely on the relative movement of orifices to control flow rate, the wear of the ceramic material of construction of the gate and the necessity to employ an inert gas shroud to 20 minimize air ingress are avoided. In addition, the structure provided enables the magnetic field to be i efficiently employed over a wide range of frequencies, ; usually high frequencies, not restricted to low frequencies as in the prior art.
In the present invention, an electromagnetic molten metal flow control device is provided surrounding the molten metal flow pipe extending between the ladle and the tundish and/or surrounding the molten flow pipe extending between the tundish and the mold.
As the liquid metal, usually steel, flows through the pipe, the eddy currents induced in the molten steel passing through the field tend to cause the metal to move away from the field and thus contract on itself.
The extent to which such contraction is effected and the 35 cross-sectional dimension of the resulting constriction depends on the strength of the magnetic field.
:
., , ~ i` ~
lZ64916 sy varying the strength of the magnetic field surrounding the flow pipe, the degree of contraction of the molten metal is varied and thereby the flow rate of molten metal through the magnetic field is varied.
The presen~ invention, therefore, relies on the variation of magnetic field strength to vary the flow rate between ladle and tundish and/or between tundish and casting mold. The invention involves no more wear to refractory components, such as the ladle, the 1~ tundish, the castlng mold and the transfer pipes, than occurs in the absence of any flow control mechanism.
The present invention also includes a method of controlling the flow of molten metal through a pipe, which comprises surrounding ~he pipe with a tubular 15 magnetic coil assembly which is confined by an electromagnetic core on all sides except its radially-inner side, and generating a magnetic field which is confined and concentrated radially-inwardly of the pipe by the electromagnetic core to penetrate the molten 20 metal and to cause the molten metal to be constricted by the magnetic field to a degree determined by the strength of the field, whereby the control of molten metal flow through the pipe is achieved by the action of the magnetic field directly on the molten metal and the 25 degree of constriction resulting from the strength of the magnetic field.
~ his invention is described further, by way of illustration with reference to the accompanying drawings, in which:
Figure 1 is a general schematic representation of a molten steel vertical casting machine including the valve mechanism of the invention;
Figure 2 is a sectional view of an electromagnetic valve constructed in accordance with one embodiment of 35 the invention, taken on line X-X of Figure 3;
Figure 3 is a sectional view of an electromagnetic valve constructed in accordance with one embodiment of the invention, taken on line Y-Y of Figure 2; and , ;, ~' ~ ....
1;264~3~6 Figure 4 is schematic representation of the electrical circuit of the electromagnetic valve of Figures 2 and 3.
Referring first to Figure 1, there is shown therein a typical continuous steel casting operation 10 comprising a ladle 12 having a body of molten steel 14 therein and having a ceramic flow pipe 16 communicating with the bottom of the ladle 12 for flow of molten steel out of the ladle. The ceramic flow pipe 16 communicates with a tundish 18 which has a body of molten steel 20 therein whlch has flowed from the ladle 12. The tundish 18 has a ceramic flow pipe 22 communicating with the bottom of the tundish 18 for flow of molten steel out of the tundish 13. The ceramic flow pipe 22 communicates with a vertical continuous caster 24 of the oscillating type to form a cooled steel bar 26 which is then processed further. The elements thus far described are conventional and their structures are well known and well understood by those skilled in the art.
In accordance with the present invention, the rate of flow of molten steel from the ladle 12 to the tundish 18 through the ceramic pipe 16 is controlled by an electromagnetic valve 28 and the rate of flow of molten steel from the tundish 18 to caster 24 through the ceramic pipe 22 is controlled by an electromagnetic valve 30.
I The electromagnetic valves 28 and 30 controlled the - molten steel flow rate by applying a magnetic field to the steel in the respective pipe 16 or 22 of an intensity to provide the desired flow rate. Sensors 32 may be provided in association with the tundish 18 to sense that the bath 20 of molten steel in the tundish 18 is at desired level or between minimum and maximum levels. The sensed signal may be transmitted to a controller 34 which then signals the electromagnetic valve 28 to provide the required magnetic field intensity. As the molten steel level in the ladle 12 becomes lower, the intensity of the magnetic field ~Z649~6 provided by the electromagnetic valve 28 is decreased in accordance with the control signal to maintain the flow of molten steel through the pipe 16 from the ladle 12 to the tundish 18. Similarly, sensors 36 sensed the molten steel level in the continuous caster 24 and a controller 38 provides appropriate signals to the electromagnetic valve 30 to increase or decrease the intensity of the magnetic field for decreased or increased flow rate of molten steel through the pipe 22 from the tundish 18 to the continuous caster 24, as required.
Details of the structure of the electromagnetic valves 28 and 30 are shown in Figures 2 and 3. The structure of valve 28 is illustrated but that of valve is identical. As may be seen therein, electromagnetic valve 28 has a generally circular cross section and surrounds the ceramic pipe 16 through which a rod 40 of molten steel passes. The valve 28 has an inner cylindrical sleeve 42, constructed of ceramic or other high temperature-resistant material, which may have protrusions or spacers 44 extending therefrom to engage the tube 16.
The ceramic sleeve 42 forms the inner wall of an annular circularly-cross-sectioned housing 46 having an outer cylindrical sleeve 48 and top and bottom closure plates 50 and 52 respectively. Located adjacent the ceramic sleeve 42 is a cylindrical inductor assembly 54, comprising a plurality of electrical coils capable of producing a magnetic field when energized. The inductor 54 may be laminated to decrease eddy current losses to a low level.
; The inductor assembly 54 is surrounded on the three sides not adjacent the ceramic tube 42 by a metallic core 56 of any convenient type to increase magnetic efficiency and, in effect, focus the magnetic field produced, upon energization, of the inductor assembly 54 radially into the ceramic tube 16 and the molten steel rod 40 and within the confined area adjacent the coils.
' - .
-, 6.,~
.; ~
~2649~6 A cylindrical capacitor assembly 58 is arranged outwardly radially exteriorally of the core 56 and is integrated into the assembly.
The inductor 54, core 56 and capacitor 58 are S electrically connected to each other and to a high frequency electrical power source 60 as illustrated in Figure 4. As may be seen, the capacitor 58 and coil 54 are arranged in a parallel circuit which itself is in series with the power source 60. In this way, for the same strength of magnetic field produced by the inductor 54, the power source 60 need provide only for power losses in the inductor-capacitor circuit. To change the intensity of the magnetic field, however, a change in the applied power is required.
The housing 46 of the electromagnetic valve 28 also includes heat exchange channels 62 and 64, through which flow cooling water from a header 66 which is divided into two compartments 68 and 70, one (68) for receipt of cooling water by pipe 72 and the other (70) for removing water by pipe 74. The compartment 68 communicates with the heat exchange channels 62 and 64 through openings 76 and 78 respectively while the compartment 70 communicates with the heat exchange channels 62 and 64 through similar openings.
In operation, the electromagnetic valve 28 uses a magnetic field produced by the inductor 54 to control the flow of the rod 40 of molten steel through the ceramic pipe 16. The magnetic field produced by the inductor 54 is directed radially-inwardly and enters the steel rod 40. Since liquid steel is an electrical conductor, the magnetic field produces eddy currents in the steel which produce a magnetic field to oppose that of the inductor 54. This opposition of magnetic fields produces a tendency for the fields to separate and thereby for the molten steel rod 40 to move radially inwardly and away from the inner wall of the tube 16.
With an increasing intensity of magnetic field produced by the inductor 54, the tendency for the molten .
~; , s, ~Z6~9~6 steel rod 40 to move radially inwardly increases while, with a decreasing intensity of magnetic field produced by the inductor 54, the tendency for the molten steel rod 40 to move radially inwardly decreases. Radial inward movement of the molten steel rod 40 produces a flow restriction or neck 80 in the steel rod 40, which limits the flow rate of molten steel through the pipe 16 to the quantity of steel which can pass through the restriction 80.
By varying the intensity of the magnetic field produced by the inductor 54, the cross-sectional dimension of the restriction 80 may be varied and hence the flow rate of molten steel through the pipe 16 may be varied. The electromagnetic valve 28, therefore, controls the flow of molten steel from the ladle 12 to the tundish 18 through the ceramic pipe 16 by the application of a magnetic field. Similarly, the electromagnetic valve 30 controls the flow of the molten steel from the tundish 18 to the continuous caster 24 by the application of a magnetic field.
Since the flow control in the present invention does not involve the interaction of mechanical devices with the molten metal stream, the wear problems and associated replacement costs attendant the prior art orifice valves are overcome. The molten steel flow is ^ readily controlled by variation of the strength of the ^~ magnetic field that is applied to the molten metal. The ; method of the invention is not restricted to steel but is applicable to any electromagnetic metal in which eddy currents are induced in a magnetic field.
In summary of this disclosure, the present invention provides novel method and apparatus for controlling the flow of~ molten electromagnetic metals, notably steel between two locations by passing the molten metal through a magnetic field. Variations in the strength of the magnetic field varies the flow rate.
Modifications are possible within the scope of this invention.
;
he present invention relates to the casting of metals, particularly steel, and more particularly to a novel valve mechanism for utilization in such casting.
In the continuous casting of steel, molten steel from the ladle is fed into a tundish from where the molten steel is fed to a vertical or inclined mold in which the steel solidifies and from which it is removed as a solid bar for further processing.
lC The control of flow of molten steel from ladle to tundish and from tundish to mold often is non-existent, which leads to inconsistent flows, entrapment of air in the steel and contaminated product as a result.
One method of counteracting this problem has been 15 to employ variable flow valves at the exit of both the ladle and the tundish, which restrict the flows to maintain desired levels of molten steel in the mold and the tundish.
Such valves are conventionally constructed of 20 ceramic material and comprise a gate-like structure wherein an orifice in a sliding gate member is moved relative to an orifice in a fixed gate member to provide a variable volume opening through from one side of the two members to the other, thereby controlling the molten 25 metal flow.
The ceramic material of the gate valves tends to wear in use. Throttling ceramic gate valves tend to aspirate air which leads to steel contamination. The aspirated air may be replaced by an inert gas, such as 30 argon, but at considerable expense. Ultimately expensive replacement of the valves is required and, in the meantime, the expense of the use of the inert gas must be incurred. Even in the presence of the inert gas shroud, some air ingress occurs and product 35 contamination, therefore, is unavoidable.
p. ~, 126~916 2 It has previously been described in French Patent No, 2,467,730 that a stream of molten metal may be constricted by means of a coil surrounding a tube co~taining the molten metal provided that alternating current is passed through the coil at a frequency which is below the inverse of the product of the magnetic permeability of the molten metal, the electrical conductivity o~ the metal and the square of the radius of the metal after constriction. An electroconductive screen preferably also is provided, arranged concentrically of the coil and penetrating the coil from above, to provide a defined commencement of the constriction.
The present invention also utilizes a magnetic field-producing coil to achieve constriction of a metal stream and the constriction achieved thereby is employed to control the flow rate of molten metal from one vessel to another. The present invention lies in the specific method adopted and also in the equipment employed.
In accordance with one a~pect of the present invention, there is provided as apparatus for controlling the flow of molten metal through a pipe of fixed diameter, which comprises a tubular -oil assembly surrounding the pipe and capable of generating a magnetic field, a core surrounding and enclosing the tubular coil assembly at its radially-outer extremity and at its upper and lower ends, so as to confine and concentrate the magnetic field radially-inwardly of the tubular coil assembly, and means for applying an alternating current to the tubular coil assembly to generate the magnetic field, whereby the radially-inward confinement of the magnetic field causes molten metal flowing through the pipe to be constricted by the action of the magnetic field directly on the molten metal to a degree determined by the strength of the magnetic field.
;`
' ' G.
','`'.'~`~ ~
1~6~6 In the present invention, therefore, a tubular magnetic field-generating coil assembly is provided surrounding a pipe through which a molten metal flows and the coil is surrounded on its radially-outer side - ' and top and bottom by a suitable electromagnetic core.
In this way, the magnetic field produced by the coil is concentrated in the flow pipe. The magnetic field results in constriction of the rod of molten metal flowing through the pipe to a degree dependent on the strength of the field.
The present invention, therefore, provides a novel valve structure which does not require the use of moving parts and yet is effective in controlling the flow therethrough of molten steel or other molten metal, at 1~ any desired flow rate.
Since the present invention does not rely on the relative movement of orifices to control flow rate, the wear of the ceramic material of construction of the gate and the necessity to employ an inert gas shroud to 20 minimize air ingress are avoided. In addition, the structure provided enables the magnetic field to be i efficiently employed over a wide range of frequencies, ; usually high frequencies, not restricted to low frequencies as in the prior art.
In the present invention, an electromagnetic molten metal flow control device is provided surrounding the molten metal flow pipe extending between the ladle and the tundish and/or surrounding the molten flow pipe extending between the tundish and the mold.
As the liquid metal, usually steel, flows through the pipe, the eddy currents induced in the molten steel passing through the field tend to cause the metal to move away from the field and thus contract on itself.
The extent to which such contraction is effected and the 35 cross-sectional dimension of the resulting constriction depends on the strength of the magnetic field.
:
., , ~ i` ~
lZ64916 sy varying the strength of the magnetic field surrounding the flow pipe, the degree of contraction of the molten metal is varied and thereby the flow rate of molten metal through the magnetic field is varied.
The presen~ invention, therefore, relies on the variation of magnetic field strength to vary the flow rate between ladle and tundish and/or between tundish and casting mold. The invention involves no more wear to refractory components, such as the ladle, the 1~ tundish, the castlng mold and the transfer pipes, than occurs in the absence of any flow control mechanism.
The present invention also includes a method of controlling the flow of molten metal through a pipe, which comprises surrounding ~he pipe with a tubular 15 magnetic coil assembly which is confined by an electromagnetic core on all sides except its radially-inner side, and generating a magnetic field which is confined and concentrated radially-inwardly of the pipe by the electromagnetic core to penetrate the molten 20 metal and to cause the molten metal to be constricted by the magnetic field to a degree determined by the strength of the field, whereby the control of molten metal flow through the pipe is achieved by the action of the magnetic field directly on the molten metal and the 25 degree of constriction resulting from the strength of the magnetic field.
~ his invention is described further, by way of illustration with reference to the accompanying drawings, in which:
Figure 1 is a general schematic representation of a molten steel vertical casting machine including the valve mechanism of the invention;
Figure 2 is a sectional view of an electromagnetic valve constructed in accordance with one embodiment of 35 the invention, taken on line X-X of Figure 3;
Figure 3 is a sectional view of an electromagnetic valve constructed in accordance with one embodiment of the invention, taken on line Y-Y of Figure 2; and , ;, ~' ~ ....
1;264~3~6 Figure 4 is schematic representation of the electrical circuit of the electromagnetic valve of Figures 2 and 3.
Referring first to Figure 1, there is shown therein a typical continuous steel casting operation 10 comprising a ladle 12 having a body of molten steel 14 therein and having a ceramic flow pipe 16 communicating with the bottom of the ladle 12 for flow of molten steel out of the ladle. The ceramic flow pipe 16 communicates with a tundish 18 which has a body of molten steel 20 therein whlch has flowed from the ladle 12. The tundish 18 has a ceramic flow pipe 22 communicating with the bottom of the tundish 18 for flow of molten steel out of the tundish 13. The ceramic flow pipe 22 communicates with a vertical continuous caster 24 of the oscillating type to form a cooled steel bar 26 which is then processed further. The elements thus far described are conventional and their structures are well known and well understood by those skilled in the art.
In accordance with the present invention, the rate of flow of molten steel from the ladle 12 to the tundish 18 through the ceramic pipe 16 is controlled by an electromagnetic valve 28 and the rate of flow of molten steel from the tundish 18 to caster 24 through the ceramic pipe 22 is controlled by an electromagnetic valve 30.
I The electromagnetic valves 28 and 30 controlled the - molten steel flow rate by applying a magnetic field to the steel in the respective pipe 16 or 22 of an intensity to provide the desired flow rate. Sensors 32 may be provided in association with the tundish 18 to sense that the bath 20 of molten steel in the tundish 18 is at desired level or between minimum and maximum levels. The sensed signal may be transmitted to a controller 34 which then signals the electromagnetic valve 28 to provide the required magnetic field intensity. As the molten steel level in the ladle 12 becomes lower, the intensity of the magnetic field ~Z649~6 provided by the electromagnetic valve 28 is decreased in accordance with the control signal to maintain the flow of molten steel through the pipe 16 from the ladle 12 to the tundish 18. Similarly, sensors 36 sensed the molten steel level in the continuous caster 24 and a controller 38 provides appropriate signals to the electromagnetic valve 30 to increase or decrease the intensity of the magnetic field for decreased or increased flow rate of molten steel through the pipe 22 from the tundish 18 to the continuous caster 24, as required.
Details of the structure of the electromagnetic valves 28 and 30 are shown in Figures 2 and 3. The structure of valve 28 is illustrated but that of valve is identical. As may be seen therein, electromagnetic valve 28 has a generally circular cross section and surrounds the ceramic pipe 16 through which a rod 40 of molten steel passes. The valve 28 has an inner cylindrical sleeve 42, constructed of ceramic or other high temperature-resistant material, which may have protrusions or spacers 44 extending therefrom to engage the tube 16.
The ceramic sleeve 42 forms the inner wall of an annular circularly-cross-sectioned housing 46 having an outer cylindrical sleeve 48 and top and bottom closure plates 50 and 52 respectively. Located adjacent the ceramic sleeve 42 is a cylindrical inductor assembly 54, comprising a plurality of electrical coils capable of producing a magnetic field when energized. The inductor 54 may be laminated to decrease eddy current losses to a low level.
; The inductor assembly 54 is surrounded on the three sides not adjacent the ceramic tube 42 by a metallic core 56 of any convenient type to increase magnetic efficiency and, in effect, focus the magnetic field produced, upon energization, of the inductor assembly 54 radially into the ceramic tube 16 and the molten steel rod 40 and within the confined area adjacent the coils.
' - .
-, 6.,~
.; ~
~2649~6 A cylindrical capacitor assembly 58 is arranged outwardly radially exteriorally of the core 56 and is integrated into the assembly.
The inductor 54, core 56 and capacitor 58 are S electrically connected to each other and to a high frequency electrical power source 60 as illustrated in Figure 4. As may be seen, the capacitor 58 and coil 54 are arranged in a parallel circuit which itself is in series with the power source 60. In this way, for the same strength of magnetic field produced by the inductor 54, the power source 60 need provide only for power losses in the inductor-capacitor circuit. To change the intensity of the magnetic field, however, a change in the applied power is required.
The housing 46 of the electromagnetic valve 28 also includes heat exchange channels 62 and 64, through which flow cooling water from a header 66 which is divided into two compartments 68 and 70, one (68) for receipt of cooling water by pipe 72 and the other (70) for removing water by pipe 74. The compartment 68 communicates with the heat exchange channels 62 and 64 through openings 76 and 78 respectively while the compartment 70 communicates with the heat exchange channels 62 and 64 through similar openings.
In operation, the electromagnetic valve 28 uses a magnetic field produced by the inductor 54 to control the flow of the rod 40 of molten steel through the ceramic pipe 16. The magnetic field produced by the inductor 54 is directed radially-inwardly and enters the steel rod 40. Since liquid steel is an electrical conductor, the magnetic field produces eddy currents in the steel which produce a magnetic field to oppose that of the inductor 54. This opposition of magnetic fields produces a tendency for the fields to separate and thereby for the molten steel rod 40 to move radially inwardly and away from the inner wall of the tube 16.
With an increasing intensity of magnetic field produced by the inductor 54, the tendency for the molten .
~; , s, ~Z6~9~6 steel rod 40 to move radially inwardly increases while, with a decreasing intensity of magnetic field produced by the inductor 54, the tendency for the molten steel rod 40 to move radially inwardly decreases. Radial inward movement of the molten steel rod 40 produces a flow restriction or neck 80 in the steel rod 40, which limits the flow rate of molten steel through the pipe 16 to the quantity of steel which can pass through the restriction 80.
By varying the intensity of the magnetic field produced by the inductor 54, the cross-sectional dimension of the restriction 80 may be varied and hence the flow rate of molten steel through the pipe 16 may be varied. The electromagnetic valve 28, therefore, controls the flow of molten steel from the ladle 12 to the tundish 18 through the ceramic pipe 16 by the application of a magnetic field. Similarly, the electromagnetic valve 30 controls the flow of the molten steel from the tundish 18 to the continuous caster 24 by the application of a magnetic field.
Since the flow control in the present invention does not involve the interaction of mechanical devices with the molten metal stream, the wear problems and associated replacement costs attendant the prior art orifice valves are overcome. The molten steel flow is ^ readily controlled by variation of the strength of the ^~ magnetic field that is applied to the molten metal. The ; method of the invention is not restricted to steel but is applicable to any electromagnetic metal in which eddy currents are induced in a magnetic field.
In summary of this disclosure, the present invention provides novel method and apparatus for controlling the flow of~ molten electromagnetic metals, notably steel between two locations by passing the molten metal through a magnetic field. Variations in the strength of the magnetic field varies the flow rate.
Modifications are possible within the scope of this invention.
;
Claims (6)
1. An apparatus for controlling the flow of molten metal through a pipe of fixed diameter, which comprises:
a tubular coil assembly surrounding said pipe and capable of generating a magnetic field, a core surrounding and enclosing said tubular coil assembly at its radially-outer extremity said at its upper and lower ends, so as to confine and concentrate the magnetic field radially-inwardly of the tubular coil assembly, and means for applying an alternating current to said tubular coil assembly to generate said magnetic field, whereby said radially-inward confinement of said magnetic field causes molten metal flowing through said pipe to be constricted by the action of the magnetic field directly on the molten metal to a degree determined by the strength of the magnetic field.
a tubular coil assembly surrounding said pipe and capable of generating a magnetic field, a core surrounding and enclosing said tubular coil assembly at its radially-outer extremity said at its upper and lower ends, so as to confine and concentrate the magnetic field radially-inwardly of the tubular coil assembly, and means for applying an alternating current to said tubular coil assembly to generate said magnetic field, whereby said radially-inward confinement of said magnetic field causes molten metal flowing through said pipe to be constricted by the action of the magnetic field directly on the molten metal to a degree determined by the strength of the magnetic field.
2. The apparatus of claim 1 including capacitor means connected in parallel with said coil assembly and wherein said means for applying an alternating current is applied in series with said parallel-connected capacitor means and coil assembly.
3. The apparatus of claim 2 wherein said tubular coil assembly, said core and said capacitor means are arranged in an annular housing having an inner cylindrical axial wall arranged to surround a pipe through which the molten metal flows.
4. The apparatus of claim 3 including cooling water inlet and outlet means for the introduction and removal of cooling water from said housing.
5. A method of controlling the flow of molten metal through a pipe, which comprises:
surrounding said pipe with a tubular magnetic coil assembly which is confined by an electromagnetic core on all sides except its radially-inner side, and generating a magnetic field which is confined and concentrated radially-inwardly of the pipe by said electromagnetic core to penetrate said molten metal and to cause said 8a molten metal to be constricted by the magnetic field to a degree determined by the strength of the field, whereby said control of molten metal flow through said pipe is achieved by the action of the magnetic field directly on the molten metal and the degree of constriction resulting from the strength of the magnetic field.
surrounding said pipe with a tubular magnetic coil assembly which is confined by an electromagnetic core on all sides except its radially-inner side, and generating a magnetic field which is confined and concentrated radially-inwardly of the pipe by said electromagnetic core to penetrate said molten metal and to cause said 8a molten metal to be constricted by the magnetic field to a degree determined by the strength of the field, whereby said control of molten metal flow through said pipe is achieved by the action of the magnetic field directly on the molten metal and the degree of constriction resulting from the strength of the magnetic field.
6. The method of claim 5 wherein said coil assembly is arranged in electrical parallel with a capacitor and an alternating current input is provided in series with the parallel arrangement of capacitor and coil assembly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000511200A CA1264916A (en) | 1986-06-10 | 1986-06-10 | Valve mechanism for metal casting machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000511200A CA1264916A (en) | 1986-06-10 | 1986-06-10 | Valve mechanism for metal casting machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1264916A true CA1264916A (en) | 1990-01-30 |
Family
ID=4133317
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000511200A Expired - Fee Related CA1264916A (en) | 1986-06-10 | 1986-06-10 | Valve mechanism for metal casting machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1264916A (en) |
-
1986
- 1986-06-10 CA CA000511200A patent/CA1264916A/en not_active Expired - Fee Related
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