CA1219725A - Process and apparatus of automatically controlling changes of surface level of a melt - Google Patents
Process and apparatus of automatically controlling changes of surface level of a meltInfo
- Publication number
- CA1219725A CA1219725A CA000456968A CA456968A CA1219725A CA 1219725 A CA1219725 A CA 1219725A CA 000456968 A CA000456968 A CA 000456968A CA 456968 A CA456968 A CA 456968A CA 1219725 A CA1219725 A CA 1219725A
- Authority
- CA
- Canada
- Prior art keywords
- probe
- melt
- impedance
- mold
- boundary layer
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
- B22D11/186—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by using electric, magnetic, sonic or ultrasonic means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/245—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid with a probe moved by an auxiliary power, e.g. meter, to follow automatically the level
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
- Control Of Non-Electrical Variables (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A method of automatically controlling changes in surface level of a melt in a continuous casting mold wherein a boundary layer including a gas phase without abrupt impedance change is provided between the melt and an overlying fluid medium. The method comprises the steps of: providing a bath of molten metal, forming the melt in a continuous casting mold overlain by the fluid medium; periodically thrusting a probe through the boundary layer toward the melt without contacting same and retracting the probe away from the melt so that the probe lies in the gas phase out of any cover of the melt; during the periodic advance and retraction of the probe measuring the electrical impedance between the melt and the probe to provide a control signal; and controlling the level of the melt in the mold in response to the control signal, reversing the direction of movement of the probe in a vertical sense when a selected value of the impedance has been reached.
And an apparatus for carrying out the method.
A method of automatically controlling changes in surface level of a melt in a continuous casting mold wherein a boundary layer including a gas phase without abrupt impedance change is provided between the melt and an overlying fluid medium. The method comprises the steps of: providing a bath of molten metal, forming the melt in a continuous casting mold overlain by the fluid medium; periodically thrusting a probe through the boundary layer toward the melt without contacting same and retracting the probe away from the melt so that the probe lies in the gas phase out of any cover of the melt; during the periodic advance and retraction of the probe measuring the electrical impedance between the melt and the probe to provide a control signal; and controlling the level of the melt in the mold in response to the control signal, reversing the direction of movement of the probe in a vertical sense when a selected value of the impedance has been reached.
And an apparatus for carrying out the method.
Description
s The present invention relates to a process and apparatus of automatically controlling changes in surface level of a melt in a continuous casting mold.
It is known that the surface level of a bath of molten metal can be directly monitored by means of mechanical systems comprising floats. Such systems are subjected to high mechanical and thermal stresses, e.g., in machines for con-tinuous casting, and such stresses will adversely affect the reliability of the measurement. For this reason, indirect methods of measuring distances have been disclosed and are more reliable and require less servicing. Known indirect measuring methods comprise radiometric, optical, acoustic and electrical methods.
`5 ',,` `
~Z~917Z5i In radiometric methods, Co60 radiators for emitting gamma radiation are used in most cases in conjunction with receivers consisting of scintillation counters. In said methods the changing area within the measuring range is proportional to the gamma quanta which are received. Whereas advantages are afforded by such measurement, which is non-contacting, requires no maintenance and has a small time lag, the handling of the radiator and the potential hazard for the personnel must be regarded as important disadvan-tages.
Thermographic methods may be carried out in thesimplest case by a chain of thermocouples or may use strain gages or permeabllity detectors or thermography and usually require expensive equipment and involve long time lag because a dealy of one to several seconds must be tolerated, which is a disadvantage.
Optical methods, e.g., a supervision by means of line-scanning television cameras or by means of infrared receivers, effect a measurement from a relatively large distance and observe the surface, so that th3 level of cove-ring powders and/or slag is detected rather than the surface level of the metal bath proper. In that case, changes of the covering layer will be detected whereas the metal bath surface level that i8 to be maintained constant may be per-mitted to change.
Indirect acoustic methods using -transmitted or reflected sound also require expensive equipment because high acoustic energies are necessary for the penetration of a plurality of boundary surfaces.
German Patent Specification 29 51 097 discloses an electrical measuring method, which is used for the auto-matic control of the surface level of molten metal in a mold for continuous casting and in which eddy currents are used for a detection of changes of the surface level of 7~
the molten bath. In that method, an alternating magnetic fleld is generated by a transmitter coil and is used to induce voltages in two secondary receiver coils. The resul-ting dif~erential voltage across said secondary coils will be offset to zero when the bath surface is on the desired level. The resulting voltage which will be obtained in case of a deviation of the bath surface from the desired level is used for an automatic control. A disadvantage of that known method resides in that the transmitter coil and the receiver coils must be mounted in the wall of the mold on the level of the bath surface or is mounted above the mold.
For this reason it is an object of the invention to provide for the automatic control of the surface level of a bath of molten metal a process which is particularly useful in conjunction with rnolds of all types and all , dimensions for continuous casting and in conjuction with a very wide range of alloys to be cast.
According to the presnet invention, there is pxovided a method of automatically controlling changes in surface level of a melt in a continuous casting mold wherein a boundary layer including a gas phase without abrupt impedance change is provided between said melt and an overlylng fluid medium, said method compxising the steps of:
providing a bath of molten metal, forming said melt in a continuous casting mold overlain by said fluid medium;
periodically thrusting a probe through said boundary layer toward said melt without contacting same and retracting said probe away from said melt so that said probe lies in said gas phase out of any cover of said melt;
during the periodic advance and retraction of said probe measuring the electrical impedance between said melt and said probe to provide a control signal; and controlling the level of said melt in said mold in response to said control signal, reversing the direction of movement of said probe in a vertical sense when a selected value of said impedance has been reached.
Preferably, the method comprises the further step of converting the displacement of said probe into an electrical signal and storing the value of said electrical signal repre-senting the point of reversal in the direction of movement of said probe.
According to the present invention, there is also provided an apparatus for measuring and controlling the height of the level of a melt comprising:
a continuous casting mold receiving said melt;
a probe;
means for thrusting said probe in said mold toward and withdrawing it away from a surface of the melt through a boundary layer between an overlying fluid medium and said melt 12~9~
with said probe being withdrawn from any covering on said melt into a gas phase thereabove;
means for measuring electrical impedance between said probe and said melt;
a comparator connected to said means for measuring said electrical impedance and a set point generator for comparing the measured electrical impedance with a set point electrical impedance representing a desired level of said melt in said mold;
means connected to said comparator and responsive to said comparator for reversing the direction of movement of said probe when the measured electrical impedance equals said set point electrical impedance;
a position indicator connected to said probe; and means responsive to said position indicator and to said comparator for registering the positlon of said probe upon a change in direction thereof for generating a control signal for automatically controlling the level of said melt in said mold.
In the method according to the invention the molten metal is used a reference electrode and the impedance above the surface of the molten metal is measured. It has been found that there is no abrupt change of the electrical imped-ance at the boundary between the surface of the molten metal and the medium disposed above the molten metal but there is a nonlinear virtually continuous, nonlinear change of the im-pedance at said boundary. This is due to the presence of boundary layer between the surface of the material and the overlying medium.
The medium which overlies the surface of the molten metal and defines the boundary layer may be formed, e.g., by a covering which is provided on the bath and consists, e.g., of salts, pine black, slags or oxide layers. But even if the surface of the molten metal is bright, the boundary layer in J~
"~
3~Z~72~
which the impedance is measured will always be formed as a result of ionization processes taking place in the atmosphere near the molten metal if the molten metal bath is at a rela-tively high temperature. This is the case, e~g., during casting operations under a protective gas atmosphere.
A probe may be used which is made of a material that has a high electrical conductivity and, if desired, a high heat resistance. Such materials include, e.g., chrome steel, chromium-nickel alloys or graphite.
From a region having a very high impedance in the medium the probe is preferably substantially vertically moved toward the surface of the molten material. During that movement the impedance between the surface of the molten metal bath (ground potential) and the probe is continually or continuously measured. At the same time the displacement of the probe is represented by an electric signal in known manner, e.g., by means of a potentiometer.
When the impedance assumes during the movement of the probe a very small value, which is still different from zero, this indicates that the probe is now only slightly spaced above the surface level of the molten metal and the movement of the probe is then reversed under electric and/or electronic control. The location of the point of reversal is detected by means for measuring the displacement of the probe and is stored.
Thereafter when the probe has reached the region of high im-pedance above the boundary layer, the described cycle of operations is repeated. Alternatively, the measurements next cycle may be initiated under the control of a timer. In either case, the measurements will be taken periodically. By means of electric circuitry known per se, the period and velocity of the movement of the prove and its travel can be varied within wide limits in adaptation to the desired measuring and auto-matic control function.
A special advantage afforded by the method according L97~
to the invention resides in that the measuring probe, which in the simplest case may consist of a wire having a thickness of a few millimeters, can be used for a measurement and control of changes of the surface level of a molten metal bath even in containers which have a very small inside diameter, which may be less than 50 mm. The method according to the invention is particularly well suited for application in conjunction with molds, particularly molds for continuous casting, which are smaller in diameter than 150 mm so that only a narrow gap defined by the inflowing molten metal is available for the measurement. ~nother important advantage of the method according to the invention resides in that heights from a few millimeters to several meters can be measured.
A preferred embodiment of the invention will now be described having reference to the attached drawings, wherein:
Figure l, diagrammatically shows the change of the electrical impedance in the boundary layer between the surface of a metal bath and the ovelying medium, Fic~ure 2 is an illustrative block circuit diagram of a system for carrying out the method according to the invention.
The container l shown in Figure 2 contains molten metal 2 and an overlying medium 5. A boundary layer 4 has formed above the surface 3 of the bath. ~y means of a dis-placing mechanism 7, a prove 6 is reciprocated toward and away from the molten material 2.
a7~,~
There are also shown - an impedance-measuring circuit 8, - a comparator 9, - means 10 for adjusting a limiting or set i~mpe-dance, - a gating and latching circuit 11, - a motor controller 12, - a servomotor 13, - a displacement-measuring device 14.
A measured-value signal 15 is generated and is used to control the surface level of the metal bath by a supply of molten metal (not shown on the drawing).
The output slgnal controls, e.g., a device for changing the flow rate oE molten metal at a high tempera-ture in a completely enclosed, linear passage. That devicecomprises a plurality of solenoid coils, which surround respective magnetic cores (Laid-open German Applications 29 24 116 and 30 24 970). The output signal may also be used to control flow control devices, such as ceramic valves for the control oE molten metal streams (Variocast R ) In the method according to the invention, the switching and control system operates as follows:
In the initial position shown in Figure 2, the probe 6 is disposed above the boundary layer, above the point designated A in Figure 1.
It is assumed that the set point adjuster 10 has been adjusted to an impedance which corresponds to the point B in Figure 1. In that case the comparator 9 detects a difference between the output of the impedance-measuring circuit 8 and the set impedance correspondingto point B, and through the intermediary of the motor con-troller 12 will cause the servomotor 13 to move by means of the displacing mechanism 7 the probe 6 toward the surface of the bulk material.
7;~S
When the probe reaches the boundary layer, the latter is traversed by the probe from point A toward point B. When the impedance measured by the circuit 8 reaches the set point correspondlng to the point B, the comparator 9 acting through 12, 13 and 7 will reverse the movement of the probe so that the latter now moves from point B
toward point A in Figure 1. The position of the probe 6 at the time at which its movement is reversed is detected by the displacament-measuring device 14, which delivers a corresponding electric signal to the gating and latching circuit 11, which now stores the value C, which adjust as the ouptut signal derived therefrom is proportional to the position of point B. The output signal 15 is used to control a suitable feeder, which is not shown in the drawing.
If point B is very close to the interface between the boundary layer and the molten material, the output signal will be proportional to the position oE the surface of the molten material in the container in sufficient appro-ximation.
The motor controller 12 is so designed that the reversal is effected very quickly when the set impedance corresponding to point B has been reached and that the probe which has been reversed will perform a certain travel toward higher impedance values before the nex-t measuring cycle can be initiated, which will then be performed as described so that a periodic measurement is effected with a period which can be adjusted within wide limits.
It is known that the surface level of a bath of molten metal can be directly monitored by means of mechanical systems comprising floats. Such systems are subjected to high mechanical and thermal stresses, e.g., in machines for con-tinuous casting, and such stresses will adversely affect the reliability of the measurement. For this reason, indirect methods of measuring distances have been disclosed and are more reliable and require less servicing. Known indirect measuring methods comprise radiometric, optical, acoustic and electrical methods.
`5 ',,` `
~Z~917Z5i In radiometric methods, Co60 radiators for emitting gamma radiation are used in most cases in conjunction with receivers consisting of scintillation counters. In said methods the changing area within the measuring range is proportional to the gamma quanta which are received. Whereas advantages are afforded by such measurement, which is non-contacting, requires no maintenance and has a small time lag, the handling of the radiator and the potential hazard for the personnel must be regarded as important disadvan-tages.
Thermographic methods may be carried out in thesimplest case by a chain of thermocouples or may use strain gages or permeabllity detectors or thermography and usually require expensive equipment and involve long time lag because a dealy of one to several seconds must be tolerated, which is a disadvantage.
Optical methods, e.g., a supervision by means of line-scanning television cameras or by means of infrared receivers, effect a measurement from a relatively large distance and observe the surface, so that th3 level of cove-ring powders and/or slag is detected rather than the surface level of the metal bath proper. In that case, changes of the covering layer will be detected whereas the metal bath surface level that i8 to be maintained constant may be per-mitted to change.
Indirect acoustic methods using -transmitted or reflected sound also require expensive equipment because high acoustic energies are necessary for the penetration of a plurality of boundary surfaces.
German Patent Specification 29 51 097 discloses an electrical measuring method, which is used for the auto-matic control of the surface level of molten metal in a mold for continuous casting and in which eddy currents are used for a detection of changes of the surface level of 7~
the molten bath. In that method, an alternating magnetic fleld is generated by a transmitter coil and is used to induce voltages in two secondary receiver coils. The resul-ting dif~erential voltage across said secondary coils will be offset to zero when the bath surface is on the desired level. The resulting voltage which will be obtained in case of a deviation of the bath surface from the desired level is used for an automatic control. A disadvantage of that known method resides in that the transmitter coil and the receiver coils must be mounted in the wall of the mold on the level of the bath surface or is mounted above the mold.
For this reason it is an object of the invention to provide for the automatic control of the surface level of a bath of molten metal a process which is particularly useful in conjunction with rnolds of all types and all , dimensions for continuous casting and in conjuction with a very wide range of alloys to be cast.
According to the presnet invention, there is pxovided a method of automatically controlling changes in surface level of a melt in a continuous casting mold wherein a boundary layer including a gas phase without abrupt impedance change is provided between said melt and an overlylng fluid medium, said method compxising the steps of:
providing a bath of molten metal, forming said melt in a continuous casting mold overlain by said fluid medium;
periodically thrusting a probe through said boundary layer toward said melt without contacting same and retracting said probe away from said melt so that said probe lies in said gas phase out of any cover of said melt;
during the periodic advance and retraction of said probe measuring the electrical impedance between said melt and said probe to provide a control signal; and controlling the level of said melt in said mold in response to said control signal, reversing the direction of movement of said probe in a vertical sense when a selected value of said impedance has been reached.
Preferably, the method comprises the further step of converting the displacement of said probe into an electrical signal and storing the value of said electrical signal repre-senting the point of reversal in the direction of movement of said probe.
According to the present invention, there is also provided an apparatus for measuring and controlling the height of the level of a melt comprising:
a continuous casting mold receiving said melt;
a probe;
means for thrusting said probe in said mold toward and withdrawing it away from a surface of the melt through a boundary layer between an overlying fluid medium and said melt 12~9~
with said probe being withdrawn from any covering on said melt into a gas phase thereabove;
means for measuring electrical impedance between said probe and said melt;
a comparator connected to said means for measuring said electrical impedance and a set point generator for comparing the measured electrical impedance with a set point electrical impedance representing a desired level of said melt in said mold;
means connected to said comparator and responsive to said comparator for reversing the direction of movement of said probe when the measured electrical impedance equals said set point electrical impedance;
a position indicator connected to said probe; and means responsive to said position indicator and to said comparator for registering the positlon of said probe upon a change in direction thereof for generating a control signal for automatically controlling the level of said melt in said mold.
In the method according to the invention the molten metal is used a reference electrode and the impedance above the surface of the molten metal is measured. It has been found that there is no abrupt change of the electrical imped-ance at the boundary between the surface of the molten metal and the medium disposed above the molten metal but there is a nonlinear virtually continuous, nonlinear change of the im-pedance at said boundary. This is due to the presence of boundary layer between the surface of the material and the overlying medium.
The medium which overlies the surface of the molten metal and defines the boundary layer may be formed, e.g., by a covering which is provided on the bath and consists, e.g., of salts, pine black, slags or oxide layers. But even if the surface of the molten metal is bright, the boundary layer in J~
"~
3~Z~72~
which the impedance is measured will always be formed as a result of ionization processes taking place in the atmosphere near the molten metal if the molten metal bath is at a rela-tively high temperature. This is the case, e~g., during casting operations under a protective gas atmosphere.
A probe may be used which is made of a material that has a high electrical conductivity and, if desired, a high heat resistance. Such materials include, e.g., chrome steel, chromium-nickel alloys or graphite.
From a region having a very high impedance in the medium the probe is preferably substantially vertically moved toward the surface of the molten material. During that movement the impedance between the surface of the molten metal bath (ground potential) and the probe is continually or continuously measured. At the same time the displacement of the probe is represented by an electric signal in known manner, e.g., by means of a potentiometer.
When the impedance assumes during the movement of the probe a very small value, which is still different from zero, this indicates that the probe is now only slightly spaced above the surface level of the molten metal and the movement of the probe is then reversed under electric and/or electronic control. The location of the point of reversal is detected by means for measuring the displacement of the probe and is stored.
Thereafter when the probe has reached the region of high im-pedance above the boundary layer, the described cycle of operations is repeated. Alternatively, the measurements next cycle may be initiated under the control of a timer. In either case, the measurements will be taken periodically. By means of electric circuitry known per se, the period and velocity of the movement of the prove and its travel can be varied within wide limits in adaptation to the desired measuring and auto-matic control function.
A special advantage afforded by the method according L97~
to the invention resides in that the measuring probe, which in the simplest case may consist of a wire having a thickness of a few millimeters, can be used for a measurement and control of changes of the surface level of a molten metal bath even in containers which have a very small inside diameter, which may be less than 50 mm. The method according to the invention is particularly well suited for application in conjunction with molds, particularly molds for continuous casting, which are smaller in diameter than 150 mm so that only a narrow gap defined by the inflowing molten metal is available for the measurement. ~nother important advantage of the method according to the invention resides in that heights from a few millimeters to several meters can be measured.
A preferred embodiment of the invention will now be described having reference to the attached drawings, wherein:
Figure l, diagrammatically shows the change of the electrical impedance in the boundary layer between the surface of a metal bath and the ovelying medium, Fic~ure 2 is an illustrative block circuit diagram of a system for carrying out the method according to the invention.
The container l shown in Figure 2 contains molten metal 2 and an overlying medium 5. A boundary layer 4 has formed above the surface 3 of the bath. ~y means of a dis-placing mechanism 7, a prove 6 is reciprocated toward and away from the molten material 2.
a7~,~
There are also shown - an impedance-measuring circuit 8, - a comparator 9, - means 10 for adjusting a limiting or set i~mpe-dance, - a gating and latching circuit 11, - a motor controller 12, - a servomotor 13, - a displacement-measuring device 14.
A measured-value signal 15 is generated and is used to control the surface level of the metal bath by a supply of molten metal (not shown on the drawing).
The output slgnal controls, e.g., a device for changing the flow rate oE molten metal at a high tempera-ture in a completely enclosed, linear passage. That devicecomprises a plurality of solenoid coils, which surround respective magnetic cores (Laid-open German Applications 29 24 116 and 30 24 970). The output signal may also be used to control flow control devices, such as ceramic valves for the control oE molten metal streams (Variocast R ) In the method according to the invention, the switching and control system operates as follows:
In the initial position shown in Figure 2, the probe 6 is disposed above the boundary layer, above the point designated A in Figure 1.
It is assumed that the set point adjuster 10 has been adjusted to an impedance which corresponds to the point B in Figure 1. In that case the comparator 9 detects a difference between the output of the impedance-measuring circuit 8 and the set impedance correspondingto point B, and through the intermediary of the motor con-troller 12 will cause the servomotor 13 to move by means of the displacing mechanism 7 the probe 6 toward the surface of the bulk material.
7;~S
When the probe reaches the boundary layer, the latter is traversed by the probe from point A toward point B. When the impedance measured by the circuit 8 reaches the set point correspondlng to the point B, the comparator 9 acting through 12, 13 and 7 will reverse the movement of the probe so that the latter now moves from point B
toward point A in Figure 1. The position of the probe 6 at the time at which its movement is reversed is detected by the displacament-measuring device 14, which delivers a corresponding electric signal to the gating and latching circuit 11, which now stores the value C, which adjust as the ouptut signal derived therefrom is proportional to the position of point B. The output signal 15 is used to control a suitable feeder, which is not shown in the drawing.
If point B is very close to the interface between the boundary layer and the molten material, the output signal will be proportional to the position oE the surface of the molten material in the container in sufficient appro-ximation.
The motor controller 12 is so designed that the reversal is effected very quickly when the set impedance corresponding to point B has been reached and that the probe which has been reversed will perform a certain travel toward higher impedance values before the nex-t measuring cycle can be initiated, which will then be performed as described so that a periodic measurement is effected with a period which can be adjusted within wide limits.
Claims (7)
1. A method of automatically controlling changes in surface level of a melt in a continuous casting mold wherein a boundary layer including a gas phase without abrupt impedance change is provided between said melt and an overlying fluid medium, said method comprising the steps of:
providing a bath of molten metal, forming said melt in a continuous casting mold overlain by said fluid medium;
periodically thrusting a probe through said boundary layer toward said melt without contacting same and retracting said probe away from said melt so that said probe lies in said gas phase out of any cover of said melt;
during the periodic advance and retraction of said probe measuring the electrical impedance between said melt and said probe to provide a control signal; and controlling the level of said melt in said mold in response to said control signal, reversing the direction of movement of said probe in a vertical sense when a selected value of said impedance has been reached.
providing a bath of molten metal, forming said melt in a continuous casting mold overlain by said fluid medium;
periodically thrusting a probe through said boundary layer toward said melt without contacting same and retracting said probe away from said melt so that said probe lies in said gas phase out of any cover of said melt;
during the periodic advance and retraction of said probe measuring the electrical impedance between said melt and said probe to provide a control signal; and controlling the level of said melt in said mold in response to said control signal, reversing the direction of movement of said probe in a vertical sense when a selected value of said impedance has been reached.
2. Method according to claim 1, wherein said probe is substantially vertically thrusted through said boundary layer toward said melt.
3. Method according to claim 2, further com-prising the step of:
converting the displacement of said probe into an electrical signal and storing the value of said electrical signal representing the point of reversal in the direction of movement of said probe.
converting the displacement of said probe into an electrical signal and storing the value of said electrical signal representing the point of reversal in the direction of movement of said probe.
4. A method according to claim 1, 2 or 3, charac-terized in that a probe is used which consists of a material that has a high electrical conductivity.
5. A method according to claim 1, 2 or 3, charac-terized in that a probe is used which consists of a material that has a high electrical conductivity and a high heat resistance.
6. A method according to claim 1, 2 or 3, charac-terized in that said medium has an electrical conductivity of another order of magnitude than said molten metal and said probe is electrically energized during the measurement of said impedance.
7. An apparatus for measuring and controlling the height of the level of a melt comprising:
a continuous casting mold receiving said melt;
a probe;
means for thrusting said probe in said mold toward and withdrawing it away from a surface of the melt therein through a boundary layer between an overlying fluid medium and said melt with said probe being withdrawn from any covering on said melt into a gas phase thereabove;
means for measuring electrical impedance between said probe and said melt;
a comparator connected to said means for measuring said electrical impedance and a set point generator for comparing the measured electrical impedance with a set point electrical impedance representing a desired level of said melt in said mold;
means connected to said comparator and responsive to said comparator for reversing the direction of movement of said probe when the measured electrical impedance equals said set point electrical impedance a position indicator connected to said probe; and means responsive to said position indicator and to said comparator for registering the position of said probe upon a change in direction thereof for generating a control signal for automatically controlling the level of said melt in said mold.
a continuous casting mold receiving said melt;
a probe;
means for thrusting said probe in said mold toward and withdrawing it away from a surface of the melt therein through a boundary layer between an overlying fluid medium and said melt with said probe being withdrawn from any covering on said melt into a gas phase thereabove;
means for measuring electrical impedance between said probe and said melt;
a comparator connected to said means for measuring said electrical impedance and a set point generator for comparing the measured electrical impedance with a set point electrical impedance representing a desired level of said melt in said mold;
means connected to said comparator and responsive to said comparator for reversing the direction of movement of said probe when the measured electrical impedance equals said set point electrical impedance a position indicator connected to said probe; and means responsive to said position indicator and to said comparator for registering the position of said probe upon a change in direction thereof for generating a control signal for automatically controlling the level of said melt in said mold.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3323749.2 | 1983-07-01 | ||
| DE19833323749 DE3323749A1 (en) | 1983-07-01 | 1983-07-01 | METHOD FOR REGULATING THE BATH MIRROR LEVEL OF A METAL MELT |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219725A true CA1219725A (en) | 1987-03-31 |
Family
ID=6202897
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000456968A Expired CA1219725A (en) | 1983-07-01 | 1984-06-20 | Process and apparatus of automatically controlling changes of surface level of a melt |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0131979B1 (en) |
| JP (1) | JPH0671642B2 (en) |
| CA (1) | CA1219725A (en) |
| DE (2) | DE3323749A1 (en) |
| ES (1) | ES533568A0 (en) |
| FI (1) | FI74897C (en) |
| IN (1) | IN162783B (en) |
| ZA (1) | ZA844987B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4728875A (en) * | 1986-10-20 | 1988-03-01 | Allegheny Ludlum Corporation | Method and apparatus for monitoring a liquid level |
| CA2003796A1 (en) * | 1988-11-30 | 1990-05-31 | Makoto Takahashi | Continuous casting method and apparatus for implementing same method |
| JPH02205234A (en) * | 1989-02-02 | 1990-08-15 | Nippon Kinzoku Kogyo Kk | Method for detecting molten metal surface level in cast strip continuous casting |
| EP0459049A1 (en) * | 1990-06-01 | 1991-12-04 | China Steel Corporation | Apparatus and process for determining thickness of the slag formed on molten steel |
| GB9116657D0 (en) * | 1991-08-01 | 1991-09-18 | Sibley Dennis S | Strip casting machine |
| AT402569B (en) * | 1995-05-11 | 1997-06-25 | Meierhofer Guenter | METHOD FOR MEASURING THE HEIGHT OF THE LIQUID LEVEL |
| DE10207395B4 (en) * | 2002-02-21 | 2005-02-10 | Sms Demag Ag | A method and apparatus for determining the instantaneous liquid metal bath level in a metallurgical vessel |
| DE102004027194A1 (en) * | 2004-06-03 | 2005-12-22 | Norddeutsche Affinerie Ag | Method and device for measuring the level of a molten metal |
| CN101349923B (en) * | 2007-07-18 | 2010-09-08 | 宝山钢铁股份有限公司 | Method for controlling thin belt continuous casting molten pool fluid level |
| FR2977027B1 (en) * | 2011-06-24 | 2013-07-12 | Dev Electroniques Et Systemes Informatiques Desi | METHOD AND DEVICE FOR DETECTING A PHASE LEVEL IN A CONTAINER |
| CN106018169B (en) * | 2016-08-10 | 2019-01-11 | 山东豪迈机械科技股份有限公司 | It is a kind of for detecting the method and device of Modeling Material gas forming amount |
| CN209157081U (en) * | 2018-04-25 | 2019-07-26 | 西安麦特沃金液控技术有限公司 | A kind of cooling water is collected and sealing device and metal base vertical continuous casting equipment |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1248969B (en) * | 1967-08-31 | |||
| DE1208515B (en) * | 1957-06-21 | 1966-01-05 | Fielden Electronics Ltd | Device for determining the level of a liquid or a flowing medium |
| DE1156576B (en) * | 1959-02-03 | 1963-10-31 | Gilbert & Barker Mfg Co | Electronic level indicator for liquids |
| FR1331821A (en) * | 1962-08-22 | 1963-07-05 | Ind De L Aluminium Sa | Method and device for maintaining constant the level of a liquid metal flowing through a passageway |
| FR1463902A (en) * | 1965-10-05 | 1966-07-22 | Siderurgie Fse Inst Rech | Adjustment of a flow rate of liquid metal flowing through an orifice |
| DE2128706A1 (en) * | 1971-06-09 | 1972-12-21 | Stahl und Rohrenwerk Reisholz GmbH, 4000 Dusseldorf | Electro slag melting control - using molten slag resisting immersion electrodes |
| JPS5376926A (en) * | 1976-12-21 | 1978-07-07 | Nippon Kokan Kk | Molten metal level monitor controller of continuous casting machine that use eddy flow system range finder for measurement of molten metal level |
| US4175612A (en) * | 1977-11-15 | 1979-11-27 | Arbed Acieries Reunies De Burbach-Eich-Dudelange S.A. | Apparatus for measuring and controlling the level of molten steel in a continuous-casting mold |
| FR2439983A1 (en) * | 1978-10-23 | 1980-05-23 | Guibert Jean | Contactless measurement of liquid surface level - utilises capacitor electrode to provide control signal for motorised probe movement |
| DE2951097C2 (en) * | 1979-12-19 | 1982-07-22 | Wieland-Werke Ag, 7900 Ulm | Method and device for controlling the mold level in continuous casting molds |
| US4470446A (en) * | 1980-07-09 | 1984-09-11 | Kabushiki Kaisha Kobe Seiko Sho | Method and apparatus for detecting molten metal surface level in a mold |
| DE3277636D1 (en) * | 1981-06-11 | 1987-12-17 | Nippon Steel Corp | Apparatus for measuring a metal surface position |
| DE3141116C2 (en) * | 1981-10-16 | 1986-08-14 | Künzer GmbH Meß-, Prüf- und Regeltechnik, 6450 Hanau | Method and device for carrying out successive temperature measurements and / or sampling and / or thermal analyzes in iron and steel melts |
-
1983
- 1983-07-01 DE DE19833323749 patent/DE3323749A1/en not_active Withdrawn
-
1984
- 1984-06-07 FI FI842314A patent/FI74897C/en not_active IP Right Cessation
- 1984-06-09 EP EP84200831A patent/EP0131979B1/en not_active Expired
- 1984-06-09 DE DE8484200831T patent/DE3467407D1/en not_active Expired
- 1984-06-20 CA CA000456968A patent/CA1219725A/en not_active Expired
- 1984-06-20 ES ES533568A patent/ES533568A0/en active Granted
- 1984-06-22 IN IN438/CAL/84A patent/IN162783B/en unknown
- 1984-06-29 ZA ZA844987A patent/ZA844987B/en unknown
- 1984-07-02 JP JP59137071A patent/JPH0671642B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES8503262A1 (en) | 1985-02-16 |
| FI74897B (en) | 1987-12-31 |
| DE3323749A1 (en) | 1985-01-03 |
| JPS6037254A (en) | 1985-02-26 |
| FI74897C (en) | 1988-04-11 |
| EP0131979A3 (en) | 1985-03-13 |
| IN162783B (en) | 1988-07-09 |
| JPH0671642B2 (en) | 1994-09-14 |
| FI842314A (en) | 1985-01-02 |
| FI842314A0 (en) | 1984-06-07 |
| DE3467407D1 (en) | 1987-12-17 |
| ZA844987B (en) | 1986-02-26 |
| EP0131979A2 (en) | 1985-01-23 |
| ES533568A0 (en) | 1985-02-16 |
| EP0131979B1 (en) | 1987-11-11 |
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