JPH07270349A - Solidification sensor - Google Patents

Abstract

PURPOSE:To provide a solidification sensor which can surely detect an internal liquid phase in real time and is inexpensive. CONSTITUTION:The sensor is provided with coils 21, 22 for generating and impressing a static magnetic field to a cast piece 2, a coil 24 for impressing an alternating magnetic field to the cast piece 2 in the static magnetic field, an alternating current source 29 for varying a frequency of a current fed to the coil 24 continuously and then outputting the current, a wattmeter 27 for measuring electricity consumed at the coil 24, and a detector 28 for detecting a volume or an area of a liquid phase of the cast piece 2. The detector 28 sequentially stores values of consumed electricity measured for every variable frequency, detects a width of the frequency when the consumed power is not, smaller than a threshold value, thereby to detect the volume or area of the liquid phase of the cast piece 2 from the width of the frequency. Width (width of a frequency) of a resonance point generated when the static magnetic field and alternating magnetic field are impressed to the cast piece 2 expands if a liquid phase is present. Therefore, the presence/absence of a liquid phase inside the cast piece 2, the volume and the area of the liquid phase can be obtained by detecting the expansion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidification sensor for detecting the presence, volume, or area of a liquid phase of a cast piece drawn from a mold in a casting facility, for example.

[0002]

2. Description of the Related Art In a conventional continuous casting facility, as shown in FIG. 4, a slab 2 drawn from a mold 1 continuously flows along a slab drawing path 3 as indicated by an arrow A, In the process, it solidifies from the outer peripheral portion, is water-cooled by the cooling water supplied from the water cooling device 4 on the way and is completely solidified to the inside, and is cut by the cutter 5. When cutting with the cutter 5, cutting with the liquid phase remaining inside is very dangerous because the molten slab will flow out. Therefore, the solidification sensor 6 is provided upstream of the position where the cutter 5 is provided. Is detected.

When the solidification sensor 6 is not provided, for safety, the slab drawing path 3 is lengthened and the cutter 5 is installed at a position far away from the mold 1. As a principle used for the coagulation sensor 6, an electromagnetic ultrasonic method and a transverse electromagnetic ultrasonic method are known.

[0004] In the coagulation sensor 6 using the electromagnetic ultrasonic method, paying attention to the fact that the permeation speed of ultrasonic waves in the metal is delayed in the liquid phase rather than in the solid phase, and the ultrasonic wave permeation time in the metal is measured. The presence or absence of the liquid phase inside and the thickness of the liquid phase are calculated.

Further, in the coagulation sensor 6 using the transverse electromagnetic wave ultrasonic method, the transverse ultrasonic wave cannot pass through the liquid phase portion of the metal. Therefore, the presence or absence of the internal liquid phase is detected depending on whether or not the transverse ultrasonic wave is transmitted. is doing.

As a method for simply detecting coagulation,
There is a tack method. This tacking method is a method in which a metal tack is hit on a metal, the cross section is cut after cooling, and the cross section is inspected to detect whether or not a liquid phase is present inside depending on how the tack is melted.

[0007]

However, in the solidification sensor 6 using the conventional electromagnetic ultrasonic method, a metal crystal which is almost solid is generated in the metal liquid phase, and it functions as an ultrasonic silencer. Therefore, it is very difficult to measure the transmitted ultrasonic waves at the arrival point, and it is necessary to generate as large an ultrasonic wave as possible. Therefore, the device becomes considerably large and inevitably becomes an expensive device. There was a problem. Further, since the speed of the sound wave greatly varies depending on the temperature, there is a problem that the thickness of the liquid phase portion cannot be obtained only from the permeation time and the surface temperature.

Further, in the solidification sensor 6 using the conventional transverse wave electromagnetic ultrasonic wave method, it is difficult to generate only the transverse wave in the metal and to detect only the transverse wave, and the outer circumference of the metal is a solid phase. Therefore, even if the inside is in the liquid phase, the transverse wave may propagate along this outer peripheral portion. In addition, there is a problem that the device becomes quite large and cannot be replaced by an expensive device.

In the tack method, since the internal state is clarified after the metal is solidified and the cross section is inspected, real-time measurement cannot be performed, and the tack, cutting, and inspection operations are not possible. There was a problem that it required a lot of labor.

The present invention solves the above problems,
It is an object of the present invention to provide an inexpensive coagulation sensor that can reliably detect the internal liquid phase in real time.

[0011]

In order to solve the above-mentioned problems, the solidification sensor of the first invention comprises a static magnetic field generating coil for applying a static magnetic field to the slab, and an alternating magnetic field to the slab in the static magnetic field. An AC magnetic field generating coil, an AC power supply that generates a current supplied to the AC magnetic field generating coil by continuously varying its frequency, and a power meter that measures the power consumed by the AC magnetic field generating coil. And, input the power consumption value measured from the power meter, input the frequency value being output from the AC power supply, store the power consumption value in order for each frequency value, and the power consumption value is equal to or more than the threshold value. It is characterized in that a detector is provided for detecting the width of the frequency value which has become smaller and detecting the volume or the area of the liquid phase of the slab from the width of the frequency value.

The solidification sensor according to the second aspect of the invention comprises a static magnetic field generating coil for applying a static magnetic field to the slab, and an AC magnetic field generating coil for applying an AC magnetic field to the slab in the static magnetic field.
A current supplied to the coil for AC magnetic field generation, an AC power source that continuously varies its frequency, and an electric power meter that measures the power consumed by the coil for AC magnetic field generation,
A power consumption value measured from the wattmeter is input and stored in order, a peak value of the stored power consumption value is detected, and a detector is provided to determine the presence or absence of the liquid phase of the slab based on this peak value. It is characterized by that.

Further, the solidification sensor of the third invention is a static magnetic field generating coil for applying a static magnetic field to the slab, an AC magnetic field generating coil for applying an AC magnetic field to the slab in the static magnetic field, and this AC magnetic field generating coil. An AC power supply that generates a current to be supplied to the coil by continuously varying its frequency, a power meter that measures the power consumed by the AC magnetic field generating coil, and a power consumption value measured from the power meter. Is added and sequentially added, and a detector is provided for judging the volume or area of the liquid phase of the slab based on the added electric energy.

[0014]

With the structure of the first aspect of the invention, since there is a magnetic moment due to a nucleus, a non-closed shell electron having a magnetic quantum number, an electron spin, etc. inside the slab, resonance occurs when a static magnetic field is applied from the static magnetic field generating coil. A resonance phenomenon occurs when an AC magnetic field having a point and having an AC magnetic field generation coil having a resonance frequency is applied. When a current of the resonance frequency is supplied from the AC power supply to the coil for generating the AC magnetic field, the AC magnetic field of the same frequency fluctuates, and the energy of the AC magnetic field is precession of the magnetic moment (the magnetic moment is centered in the direction of the magnetic field The energy of this precession will be lost due to the relaxation mechanism inside the slab, so when the resonance phenomenon occurs, a large amount of energy is consumed. It will be. Therefore, if the static magnetic field strength is kept constant and the frequency of the AC power supply is changed, and the power consumption is measured with a wattmeter, if there is a liquid phase inside the slab, metal atoms in the liquid phase do not form a crystal structure and are free. Since it is in motion, the frequency range at the resonance point widens due to the Doppler effect. This spread of the frequency width increases with the volume of the liquid phase inside the slab, so by detecting the spread of the frequency width of this resonance point in the detector, that is, the frequency at which the power consumption value is equal to or greater than the threshold value. By detecting the range of values, the presence / absence of a liquid phase inside the cast slab and the volume of the liquid phase can be determined. If the cross-sectional shape is approximated to be constant in the measurement range, the volume is proportional to the area, so the area of the liquid phase can be estimated. It can also be detected in real time.

According to the configuration of the second invention, when the static magnetic field is kept constant as described above, the frequency of the AC power source is changed, and the power consumption is measured by the wattmeter, it is found that there is a liquid phase inside the slab. In the liquid phase, the metal atoms move freely without forming a crystal structure, so the frequency range at the resonance point widens due to the Doppler effect, but when there is a liquid phase, the power consumption value (peak value) at the resonance point is also increased. ) Also decreases. Therefore, the peak value of the power consumption values stored in the detector can be detected, and the presence or absence of the liquid phase of the slab can be determined by the peak value.

Further, according to the structure of the third invention, when the static magnetic field strength is made constant and the frequency of the AC power source is changed as described above, and the power consumption is measured by the wattmeter, it is found that there is a liquid phase inside the slab. In the liquid phase, the metal atoms move freely without forming a crystal structure, so that the frequency range of the resonance point is widened by the Doppler effect, and thus the power consumption is also increased. Therefore, in the detector, the volume or area of the liquid phase of the cast piece can be determined by the power consumption.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same configurations as those of the conventional example shown in FIG.

FIG. 2 is a block diagram of a continuous casting facility using the solidification sensor of the present invention. 11 is a solidification sensor of the present invention installed near the solidification end position of the slab 2 instead of the conventional solidification sensor 6. , 12 are controllers for controlling the amount of cooling water supplied from the cooling device 4 by an area detection signal (described later) of the liquid phase inside the cast piece 2 detected by the solidification sensor 11.

A block diagram of the coagulation sensor 11 is shown in FIG. A first coil 21 and a second coil 22 installed above and below the slab drawing path 3 of the slab 2, respectively, and the first coil 2
1. DC power supplies 23A and 23B for supplying DC current to the first and second coils 22, respectively, and a third coil 24 wound between the first and second coils 21 and 22 along the outer circumference of the slab 2. When,
An oscillator 25 that oscillates by continuously varying the frequency, an amplifier 26 that supplies a high-frequency current to the third coil 24 by the frequency oscillated by the oscillator 25, and power that measures the power consumed by the third coil 24. 27, and the power consumption value measured from the power meter 27 is input, the frequency value during oscillation is input from the oscillator 25, the power consumption value is stored in sequence for each frequency value, and the area of the liquid phase of the slab 2 is stored. And a resonance point width detector 28 (details of which will be described later). The oscillator 25 and the amplifier 26 form an AC power supply 29.

A static magnetic field is applied to the slab 2 by supplying a direct current to the first coil 21 and the second coil 22 from the DC power supplies 23A and 23B, and a high frequency current is supplied to the third coil 24 by the amplifier 26. As a result, an alternating magnetic field (high frequency magnetic field) is applied to the slab 2. Further, the power meter 25 detects the power consumption of the third coil 24.

The principle of the coagulation sensor 11 having the above structure will be described. Since there is a magnetic moment due to nuclei, non-closed shell electrons having magnetic quantum numbers, electron spin, etc. inside the slab 2, it has a resonance point when a static magnetic field is applied, and a resonance phenomenon when an AC magnetic field equal to this resonance frequency is applied. Cause The resonance frequency is shown by the following equation 1.

F = k · M · H (1) f; Resonance frequency k; Constant M; Magnetic moment H; Static magnetic field strength In FIG. 1, when a signal of resonance frequency is oscillated from the oscillator 25, the third coil An AC magnetic field with the same frequency fluctuates inside 24, and the energy of the AC magnetic field is transferred to the precession motion of the magnetic moment (the magnetic moment makes a conical rotation motion around the direction of the magnetic field). Become. Since the energy of this precession motion is lost due to the relaxation mechanism inside the slab 2, when the resonance phenomenon occurs, the amplifier 26 consumes a large amount of energy. Therefore, by changing the frequency of the oscillator 25 while keeping the strength of the static magnetic field constant and measuring the power consumption by the power meter 27, the frequency-power consumption characteristics as shown in FIG. 3 can be obtained.

FIG. 3A shows the case where there is no liquid phase in the slab 2, but when the slab 2 has a liquid phase, the slab atoms move freely in the liquid phase without forming a crystal structure. Therefore, due to the Doppler effect, the frequency width of the resonance point widens as shown in FIG. Since the spread of the frequency width increases with the volume of the liquid phase inside the cast piece 2, the presence or absence of the liquid phase inside the cast piece 2 and the volume of the liquid phase can be obtained from the spread of the frequency width of the resonance point.

Further, when the cross-sectional shape is approximated to be constant in the measurement range, the volume is proportional to the area, and therefore the area of the liquid phase can be estimated. Further, assuming that the liquid phase exists in a shape that is long in the lateral direction, the area is proportional to the thickness of the liquid phase.

Based on the above principle, the resonance point width detector 28 determines the width f _W of the frequency value at which the power consumption value sequentially stored for each frequency value becomes equal to or greater than the power consumption value (threshold value) P _{L at the} resonance point. The area (or volume) of the liquid phase of the slab 2 is detected from the width f _W of this frequency value.

The liquid phase area detection signal detected by the resonance point width detector 28 is input to the controller 12. Now,
In order to produce a good quality metal such as iron, it is necessary to keep the cooling conditions optimal, but it is extremely difficult due to changes in external conditions such as room temperature. If the amount of cooling water is controlled so that the solidification end position of the cast slab 2 (the position where the liquid phase area is "0") is constant, the cooling conditions are constant and the product quality is improved.

Therefore, the controller 12 responds to the inputted liquid phase area detection signal so that the area of the liquid phase increases so that the coagulation terminal position becomes constant, that is, when the coagulation terminal position moves downstream, the cooling water is cooled. Is output to the cooling device 4, and conversely, when the area of the liquid phase is decreased, that is, when the coagulation end position moves upstream, the cooling water decrease signal is output to the cooling device 4.

By configuring the solidification sensor 11 as described above, the presence / absence of a liquid phase, the volume of the liquid phase, or the area inside the slab 2 can be determined in real time, and a simple structure can be obtained. Therefore, the cost can be reduced.

Further, by controlling the area of the liquid phase detected by the coagulation sensor 11 or the position of the coagulation terminal based on the volume detection signal, the quality of the product can be improved,
Further, the continuous casting equipment and the cutter 5 can be installed close to each other, so that the slab drawing path 3 can be shortened and the equipment can be downsized. Further, since the cutting is performed with the freezing point kept constant, troubles such as the outflow of the molten slab can be eliminated.

In the solidification sensor 11 of the present embodiment, the presence or absence of the liquid phase in the slab 2 is determined from the spread of the frequency width f _W of the resonance point.
The area or volume of the liquid phase is calculated, but it is shown in Fig. 3 (a).
As shown in (b), the peak value P _{M of the} power consumption at the resonance point
Since the value becomes low when the liquid phase exists, the presence or absence of the liquid phase can be determined by the value of the peak value P _M. In this case, the resonance point width detector 28 determines the peak value P _M from the power consumption value stored in sequence for each frequency value and compares it with the peak value P _M when there is no liquid phase to determine the presence or absence of the liquid phase. To do.

Further, as shown in FIGS. 3 (a) and 3 (b), the liquid
Frequency width f at resonance point depending on phase volume _WThe spread of
The power consumption of the slab 2
Presence / absence of liquid phase or volume can be calculated
It In this case, the resonance point width detector 28 is measured by the power meter 27.
Input the power consumption value and add them in order.
Determine the volume or area of the liquid phase of slab 2 by the amount of electric power
In addition, in this embodiment, the frequency of the alternating magnetic field is variable.
However, it is necessary to fix this frequency and change the static magnetic field.
Is also possible.

Further, in this embodiment, the solidification sensor 11 is used in the continuous casting equipment, but it can be used for confirmation of melting in the electric furnace or confirmation of solidification in simple casting.

[0033]

As described above, according to the first aspect of the invention, in the detector, the resonance point generated by externally applying the static magnetic field and the alternating magnetic field to the magnetic moment existing in the metal atom is
When the liquid phase exists, the width of the frequency spreads, and by detecting this spread, that is, by detecting the width of the frequency value at which the power consumption value is equal to or higher than the threshold value, the liquid phase inside the slab is Presence / absence / volume of liquid phase or area can be determined. Further, the structure can be simple, and the cost can be reduced. It can also be detected in real time.

According to the second aspect of the invention, when there is a liquid phase, the power consumption value (peak value) at the resonance point also decreases, so that the peak value of the stored power consumption value is detected, and this peak value is detected. The presence or absence of the liquid phase of the cast can be determined by determining

Further, according to the third aspect of the invention, when the liquid phase is present as described above, the frequency width of the resonance point is widened, and the power consumption is also increased. The volume or area of the liquid phase of the piece can be determined.

[Brief description of drawings]

FIG. 1 is a principle diagram of a coagulation sensor in one embodiment of the present invention.

FIG. 2 is a main part configuration diagram of a continuous casting facility using the solidification sensor.

FIG. 3 is a frequency-power consumption characteristic diagram detected by the solidification sensor according to the presence or absence of a liquid phase of the cast slab.

FIG. 4 is a main part configuration diagram of a continuous casting facility using a conventional solidification sensor.

[Explanation of symbols]

 1 Mold 2 Cast Piece 3 Cast Piece Extraction Path 4 Cooling Device 5 Cutter 11 Coagulation Sensor 12 Controller 21 1st Coil (Static Magnetic Field Generating Coil) 22 2nd Coil (Static Magnetic Field Generating Coil) 23A, 23B DC Power Supply 24 3rd Coil (Coil for AC magnetic field generation) 25 Oscillator 26 Amplifier 27 Power meter 28 Resonance point width detector 29 AC power supply

Claims (3)

[Claims] 1. A static magnetic field generating coil for applying a static magnetic field to a slab, an AC magnetic field generating coil for applying an AC magnetic field to the slab in the static magnetic field, and a current supplied to the AC magnetic field generating coil. An AC power supply for continuously varying and outputting the frequency, a power meter for measuring the power consumed by the AC magnetic field generating coil, and a power consumption value measured from the power meter are input, and the AC power supply is used. Input the frequency value being output from, and store the power consumption value for each frequency value in order, and detect the width of the frequency value where the power consumption value is equal to or greater than the threshold value.
A coagulation sensor comprising a detector for detecting the volume or area of the liquid phase of the slab from the width of the frequency value. 2. A static magnetic field generating coil for applying a static magnetic field to the slab, an AC magnetic field generating coil for applying an AC magnetic field to the slab in the static magnetic field, and a current supplied to the AC magnetic field generating coil. An AC power supply that continuously changes the frequency to generate the power, a power meter that measures the power consumed by the AC magnetic field generation coil, and a power consumption value measured from the power meter are input and stored in order. A solidification sensor, comprising: a detector that detects a peak value of the stored power consumption value and determines the presence or absence of a liquid phase of the slab based on the peak value. 3. A static magnetic field generating coil for applying a static magnetic field to the slab, an AC magnetic field generating coil for applying an AC magnetic field to the slab in the static magnetic field, and a current supplied to the AC magnetic field generating coil. An AC power supply that continuously changes the frequency and generates the power, a power meter that measures the power consumed by the AC magnetic field generation coil, and a power consumption value measured from the power meter are input and added in order. A solidification sensor comprising a detector for judging the volume or area of the liquid phase of the cast slab according to the added electric energy.