JP3094904B2 - Apparatus and method for melting and solidifying material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling type crucible in which induction heating, control of the shape of a melt and electromagnetic stirring are simultaneously realized, whereby a solid material is continuously melted and then solidified. And a method using the same.

[0002]

2. Description of the Related Art In general, when a solidified body is continuously obtained by cooling a molten metal, it is necessary to precisely control the starting position of solidification in order to reduce surface layer inclusions and surface cracks and to improve product quality. It is valid. In this case, the control of the starting position of solidification is in a front-to-back relationship with the control of the height of the molten metal surface (hereinafter, referred to as a molten metal surface).

[0003] Conventionally, distance meters such as ultrasonic waves, microwaves, lasers, and eddy current sensors have been used to detect the level of the molten metal inside a mold or crucible. However, ultrasonic waves and microwaves have a problem in accuracy and are hardly used at present.

[0004] Among these sensing methods, lasers and eddy current sensors are mainly used. However, with a laser, the brightness of the molten metal is so high that it is difficult to distinguish it from the reflected light of the laser, so that the measurement accuracy is poor. Further, when the molten metal surface is covered with the flux, the problem due to the luminance is solved, but the measurement accuracy cannot be expected to be improved because of the influence of the thickness of the flux layer. On the other hand, in the eddy current sensor,
The output value varies depending on the shape of the mold and the crucible, but the accuracy is good as well as the response.

For this reason, the eddy current sensor is becoming mainstream as a sensor for detecting the level of the molten metal in many continuous solidifying apparatuses. However, the eddy current sensor also has a disadvantage that it is susceptible to disturbances such as an electromagnetic field.

Japanese Patent Application Laid-Open No. 1-266952 discloses a coil embedded in a mold, a measuring device for inductance connected to the coil, and a device for detecting the level of the molten metal in the mold based on the measured value. A method for controlling a supply amount of molten metal for a continuous casting machine including an apparatus is disclosed. In this apparatus for detecting the position of a molten metal surface, a coil as a sensor is embedded in a mold. Therefore, when a current having a frequency on the order of several kHz is applied, the magnetic field is significantly attenuated in the copper mold, and the level of the molten metal cannot be measured, and the usable frequency is limited.

The inventor of the present invention disclosed in Japanese Unexamined Patent Publication No. Hei 3-275257 discloses a method of arranging a coil on the outer periphery of a continuous casting mold, supplying a high-frequency current to the coil, and resonating an LC circuit constituted by a high-frequency power supply including the coil. Detect the frequency, adjust the material supply speed so that the value becomes a predetermined value,
A continuous casting method to maintain the static pressure of the liquid metal at a constant value and to keep the position of the molten metal level constant was shown. However, in this method, a study on how to determine a value of a predetermined resonance frequency is still insufficient.

[0008] JP-A-6-22056 discloses a method disclosed in JP-A-3-2752.
Measure the inductance, coil current, voltage, power factor and impedance with a configuration almost similar to the method of No. 57,
A method for controlling the level of the molten metal is shown. In any case, in this method, control is performed by measuring the voltage or current of the circuit system, so that a change in the measured value is caused by a change in the output of the high-frequency power supply and a portion caused by a change in the level of the molten metal. There is an annoyance that it must be separated into Further, it does not disclose how to obtain a value such as an inductance as a control target.

[0009]

The problem to be solved by the present invention is that the value of the resonance frequency corresponding to the level of the molten metal to be controlled in the conductive crucible is used as a control parameter and the accuracy is determined before starting the operation. It is an object of the present invention to provide an apparatus for solidifying or melting and solidifying a material with a new means which can be easily obtained, and a method using the same.

[0010]

The gist of the present invention is as follows.
The apparatus of (1) and the method of using this in (2).

(1) A vertical conductive crucible having a slit having an insulating function along the drawing direction of the solidified body and having a water cooling function, and is disposed near the slit so as to spirally surround the crucible. Coil, solidified body extraction device, solid or molten material supply device to crucible, cooling water supply device, high-frequency power supply, frequency meter for detecting the resonance frequency of high-frequency current flowing from this power supply to coil, detected resonance frequency Control device for controlling the supply of solid or molten material with the value of
A material comprising : a device for inserting a solid having an uncooled or cooled structure (hereinafter, referred to as a simulated melt) simulating electric conductivity and the shape of a molten metal into a crucible, and an atmosphere adjusting chamber as necessary. Solidification or melting, solidification equipment.

(2) A method for solidifying, melting, or solidifying a material using the solidifying or melting and solidifying apparatus according to (1) above, wherein a simulated molten material is inserted into a crucible before starting operation of the apparatus. The relationship between the position of the melt and the resonance frequency of the high-frequency current flowing through the coil is measured in advance, and during operation of the apparatus, the position of the melt in the crucible is estimated from the value of the resonance frequency measured in advance. A method for solidifying or melting and solidifying a characteristic material.

The above “material” is metal, glass or Si
Ceramics and semiconductor materials such as O ₂ , Al ₂ O ₃ , MgO, ZrO _{2 and} GaAs.

As disclosed in JP-A-3-275257,
In a system in which there is a slit with an insulating function along the direction in which the solidified body is pulled out and the coil is arranged so as to spirally surround the outer periphery of a vertical conductive crucible with a water cooling function, When a current is supplied, the resonance frequency of the high-frequency current slightly changes with the change in the molten metal level in the crucible.

In this case, however, the relationship between the value of the molten metal level and the corresponding value of the resonance frequency of the high-frequency power supply differs depending on the size of the crucible, the molten material, the capacitance and output of the high-frequency power supply, and the like. It is necessary to determine in advance depending on the method.

As an example, a solid material is melted in a crucible, and the resonance frequency is used together with the immersion method (a method in which a thin metal plate is inserted from the surface of a molten metal and the molten metal level is evaluated from an unmelted shape). There is a method for measuring. However, it is troublesome and inefficient to melt the metal and determine the position of the molten metal surface by the immersion method.

As an alternative, the present inventor inserts a simulated melt into a crucible and measures the relationship between the position of the simulated melt and the resonance frequency of the high-frequency current flowing through the coil before starting operation. It has been found that the method is suitable.

Since the simulated melt is a solid, the insertion position (equivalent to the level of the molten metal) can be easily known if a distance meter is provided in the insertion device.

The simulated melt needs to be cooled so as not to be melted by Joule heat when the output of the high frequency power supply is large.

Another condition required for the simulated melt is that physical properties, particularly electric conductivity, are almost equal to those of the melt, and further, the shape of the upper part thereof is almost equal to the shape of the molten metal surface.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration example of the apparatus of the present invention will be described with reference to FIGS.

FIG. 1 is a conceptual vertical sectional view showing a configuration example of the apparatus of the present invention.

This apparatus example is provided with a simulated melt, a device for inserting the simulated melt and an atmosphere control chamber, and is used for processing a solid material. The apparatus comprises a vertical conductive crucible 2 having a water-cooling function, a coil 3 arranged in a spiral shape around the crucible 2, a device 4 for extracting a solidified body 10, and a device 5 for supplying a solid material 5'-1. A cooling water supply device 6, a high-frequency power supply 7, a frequency meter 7 'for detecting a resonance frequency of a high-frequency current flowing from the power supply 7 to the coil 3, and a solid material 5'-1 using the detected resonance frequency value as input data. And a material supply amount control device 8 for controlling the supply amount of the material.

The coil 3 is electrically connected to a high frequency power supply 7 and a frequency meter 7 'by a circuit as shown.
As the supply device 5 for the solid material 5'-1, for example, a vibration feeder system having a hopper as shown in the drawing is used.
And is electrically coupled to the material supply control device 8. A control circuit as shown in the figure is set up so that at least the value of the resonance frequency of the high-frequency current obtained from the high-frequency power supply 7 is input to the material supply amount control device 8 via the frequency meter 7 '.

A method for controlling the material supply amount is described in, for example,
LC using a capacitor as shown in 275257
A resonance circuit method may be used. The material supply amount control device 8 is not limited to the vibration feeder system as long as the above-described control is achieved.

The device 4 for pulling out the solidified body 10 is disposed below the crucible 2 as shown. The cooling water is supplied to the crucible 2, the coil 3, and the high-frequency power source 7 from a cooling water supply device 6 through a water channel as illustrated.

In FIG. 1, reference numeral 9 denotes a molten material, 12 denotes a molten metal surface (free surface), and 13 denotes a solid-liquid interface (the molten material 9 and the solidified material).
Boundary 10) and 17 are dummy heads.

The whole of the crucible 2 and the like are housed in an atmosphere adjusting chamber 11 in the arrangement shown in the figure. But,
The atmosphere adjusting chamber 11 is necessary when the melt 9 and the solidified body 10 are easily oxidized metals. For example, when the solid material 5′-1, the melted body 9 and the solidified body 10 are glass, etc. Is not necessarily required.

The simulated melt 14 is placed above the crucible 2 (in the example of FIG. 1, further outside the atmosphere adjustment chamber 11).
There is provided an insertion device 16 with a distance meter 15 for insertion therein.

In the case of FIG. 1, the insertion device 16 of the simulated melt 14 is configured to be inserted from the upper part of the crucible 2, but it is not necessarily required to be inserted from the upper part, and may be configured to be inserted from the lower part. This is because it is not necessary to mount the dummy head 17 yet when the simulated melt 14 is being inserted.

The material of the simulated melt 14 is generally a solid metal such as stainless steel, and may or may not have a cooling function. Cooling is performed by the high frequency power supply 7
May be performed when there is a possibility of melting due to Joule heat. In the case of having a cooling function, a tubular structure or the like can be considered as a cooling structure, and water or the like is used as a coolant. When selecting water, the cooling water may be supplied from the supply device 6.

If necessary, a cooling means may be provided in a portion corresponding to the solidified body 10 below the crucible 2 to supply cooling water.

Although the necessity of cooling the simulated melt 14 also depends on the output of the high-frequency power source 7 as described above, it is generally preferable that the simulated melt 14 has a water-cooled structure.

The simulated melting resistance 14 makes the physical property value, particularly the electric conductivity, substantially equal to that of the melting resistance 9, and furthermore, as shown in FIG. It is necessary to make them equal. This is because the values of the resonance frequencies are different for the melts 9 having different physical property values or the molten metal surface shape.

It is not easy to realize that the shape of the upper side of the simulated melt 14 is almost equal to that of the molten metal surface 12 of the melt 9. However, for example, by assuming that the shape of the molten metal surface 12 of the melt 9 is formed from the equilibrium condition of the static force relating to gravity, electromagnetic force and surface tension acting on the melt 9, the shape can be theoretically determined. Can be predicted (Ref T.
Tanaka, K. Kurita and A. Kuroda: ISIJ Int., 31 (1991),
350).

FIG. 2 is a conceptual bird's-eye view showing an example of the configuration of the crucible 2 used in the apparatus shown in FIG. Crucible 2 contains solidified body 10
(See Fig. 1) Pulling direction (vertical direction in Fig. 2)
A plurality of slits 1 having an insulating function are arranged along. Around the crucible 2, there are multiple coils 3 arranged in the vicinity of the slit 1 so as to surround the crucible 2 as described above, particularly so that the slit 1 exists inside the coil 3. The coil 3 is electrically connected to a high-frequency power supply 7.

The crucible 2 has two upper and lower openings.
While supplying the solid material 5′-1 from the upper opening, the solidified material that has been melted, molded, stirred and solidified in the crucible 2 is pulled out of the crucible 2 from the lower opening using the drawing device 4 shown in FIG. The solid material 5'-1 is treated by continuous drawing. As a result, as shown in FIG. 1, the melt 9, the molten metal surface 12, the solid-liquid interface 13, and the solidified body 10 are present in the crucible 2.

In order for the solid material 5'-1 charged in the crucible 2 to undergo a series of processes, generally, the solid material 5'-1
Is desirably one having relatively high electric conductivity. Thus, solid material 5'-1 to which the present invention a method is often is a metal, glass or SiO _2, Al
Ceramics and semiconductor materials such as ₂ O ₃ , MgO ₂ , ZrO ₂ or GaAs may be used.

Next, the method of the present invention will be described.

When processing a solid material using the apparatus having the structure shown in FIGS. 1 and 2, the following is performed.

According to this method, the relationship between the position of the simulated melt in the crucible and the resonance frequency of the high-frequency current flowing through the coil is measured before starting the operation, and during the operation of the apparatus, the resonance frequency of the previously measured resonance frequency is measured. The position of the melt in the crucible is estimated from the value to melt and solidify the material.

In the operation of the apparatus, first, cooling water is supplied to the high frequency power supply 7, the coil 3, and the crucible 2. If necessary, cooling water is also supplied to a portion corresponding to the solidified body 10 below the crucible 2.

After supplying the cooling water, the output of the high-frequency power source 7 is increased to approximately a normal operation state, and the simulated melt 14 is inserted into the crucible 2. At this time, the insertion depth of the simulated melt 14 is changed while being measured using the distance meter 15.

In this way, after obtaining data on the relationship between the upper surface of the simulated melt 14, that is, the height of the molten metal surface and the value of the resonance frequency of the high frequency power supply 7 by the frequency meter 7 ′, the simulated melt 14 is removed. It moves out of the crucible 2 and stops the output of the high frequency power supply 7.

The preliminary test before the start of the operation is completed at this stage, and then the normal operation is started.

The pulling device 4 for the solidified body 10 is reversed, and the upper end of the dummy head 17 is inserted from below the crucible 2 to a predetermined position in the crucible 2, for example, to the upper end of the coil 3. If necessary, the atmosphere of the crucible 2 is adjusted to an inert gas atmosphere such as Ar gas using the atmosphere adjustment chamber 11.

Next, the value of the resonance frequency (target frequency) corresponding to the target level of the molten metal is read from the data of the previous test, and the value is inputted to the control unit 8 for the material supply amount. 7 is increased to a predetermined value. Eventually, the dummy head 17 is melted, and if the drawing device 4 of the solidified body 10 is driven at a predetermined speed thereafter, the solid material 5'-1 corresponding to the drawing mass is automatically supplied into the crucible 2. As a result, the height of the molten metal surface 12 is maintained at a constant position during operation.

FIG. 3 is a conceptual vertical sectional view showing another example of the configuration of the apparatus of the present invention.

This apparatus example is provided with an atmosphere control chamber and is for processing a molten material. Also in this apparatus, an insertion device 16 having a distance meter 15 for inserting the simulated melt 14 shown in FIG. 1 into the crucible 2 is provided (however, not shown in FIG. 3). Melt 14
Of the upper surface, that is, the height of the molten metal surface and the value of the resonance frequency of the high frequency power supply 7 by the frequency meter 7 '. The structures of the crucible 2 and its peripheral devices are the same as those in FIGS.

Melt material 5'-2 charged in crucible 2
Is the same as the solid material described above. If the melt material 5'-2 is easily oxidized, an atmosphere adjusting chamber is provided as appropriate.

The material supply device 5 for the melt material 5'-2
For example, it comprises a tundish 19 provided with a dipping nozzle 20 and a ladle 18 as shown. The immersion nozzle 20 has a sliding gate 21 for controlling the supply of the melt material 5'-2.

The sliding gate 21 is electrically connected to the controller 8 for controlling the material supply. A control circuit as shown in the figure is set up so that at least the value of the resonance frequency of the high-frequency current obtained from the high-frequency power supply 7 is input to the material supply amount control device 8 via the frequency meter 7 '.

In FIG. 3, reference numeral 22 is a molten flux and 23 is an unmelted flux.

The processing of the molten material using the apparatus having the structure shown in FIGS. 2 and 3 is performed as follows.

After the same preliminary test as above has been completed,
By moving the insertion device 16 of the simulated melt 14, the melt material 5 '
-2 material supply device 5 and dummy head 17
Attach.

In this state, the output of the high-frequency power source 7 is adjusted, and the control device 8 for the supply amount is driven. On the other hand, the resonance frequency is adjusted so that the height of the molten metal surface 12 corresponds to the upper end of the stack height of the coil 3. Set to.

When the temperature of the molten material 5'-2 in the ladle 18 reaches a predetermined degree of superheating, charging of the molten material 5'-2 into the tundish 19 is started, and the high frequency power supply 7 Is increased to a predetermined value. The melt material 5'-2 flows into the crucible 2 via the tundish 19 and the sliding gate 21, and the molten metal surface 12 in the crucible 2 rises and is eventually stabilized. At a stage before the molten metal surface 12 almost reaches the upper end of the coil 3, the drawing device 4 is driven to obtain the solidified body 10.

The shape of the molten metal surface 12 depends on the number of turns and the current value of the coil 3, the size of the crucible 2, and the like. In addition,
The shape of the liquid interface 13 varies depending on the drawing speed and the cooling speed of the solidified body 10.

Other desirable conditions in the present invention are:
It is as follows.

Material of crucible: copper, silver, stainless steel Shape of crucible: height 50-500 mm, inner diameter 50-500 mm, standard outer diameter 80-600 mm Slit length: 50-300 mm Number of slits: 10-50 Slit gap: 0.01 ~ 1.0mm Coil: 90 ~ 610mm inside diameter, 100 ~ 670mm outside diameter, 2 ~ 30 turns High frequency power supply: output 5 ~ 5000kW, frequency 0.01 ~ 1000kHz
z Coil current: 0.01 to 1000 kAT Processing speed: 0.0001 to 10 m / min

[0061]

【Example】

(Invention Example 1) Titanium scrap was melted and solidified using the apparatus of the present invention shown in FIGS. The main specifications of the device are as follows.

Crucible: material is copper, height is 240mm, inner diameter is 10
0mm, standard outer diameter is 125mm, slit length is 150mm number of slits: 16 slit gap: 0.2mm coil: inner diameter of winding is 30mm, outer diameter of winding is 150mm, number of turns is 6 times High frequency power supply: output is 150kW, frequency is 30kHz coil Current: 4 kAT Cooling water pump: water volume 150 liter / min, discharge pressure 7
000hPa Material supply device: Vibration feeder system with hopper on top Maximum particle size of titanium scrap: 10 mm square Control method of material supply amount: Almost the same as the method shown in FIG. 12 of JP-A-3-275257. However, the capacitance of the LC resonance circuit is 56 μF, the resistance is 0.1 Ω, and the inductance of the resonance coil is 1.4 μH.

Method for charging the simulated melt: charging from above the crucible Processing speed: 1.6 cm / min The processing procedure was as follows.

First, the shape in which the molten metal of titanium placed in the crucible was molded by the action of the electromagnetic force was theoretically predicted. The method is the same as that described in the above-mentioned document.

FIG. 4 shows an example of the prediction result.

FIG. 4 is a diagram showing an example of a longitudinal sectional shape of a molten material predicted when a coil current value and a molten metal level are used as parameters.

In FIG. 4, the arrows indicate the magnetic pressure acting on the molten metal surface 12 and its distribution, and the maximum value MAX (Pm) is 2.6 k
Pa. When the coil current value and the height of the molten metal surface 12 are different, the shape of the molten metal surface 12 is different depending on conditions as shown in cases (C) to (H). Therefore, it is necessary to produce a simulated melt according to each processing condition. Next, as an example, the case in FIG.
A simulated melt having a shape corresponding to (C) was prepared from a stainless steel material. At that time, in order to prevent melting by Joule heat, the inside was made to be a water-cooled structure, and the thickness of the outer skin was set to 20 mm. The thickness of the outer skin is about six times the skin depth of the electromagnetic field, and the electromagnetic interaction is the same as when the inside is filled. The difference between the electrical conductivity of the titanium metal melt and the electrical conductivity of the water-cooled stainless steel is within 1.5 times, and no significant error occurs in the measurement of the resonance frequency.

After supplying the cooling water, a high-frequency power supply is operated to supply a predetermined coil current to the coil, the simulated melt is gradually inserted from the upper end of the crucible, and the top of the simulated melt obtained from the distance meter is obtained. The relationship between the position and the resonance frequency of the high frequency power supply obtained from the frequency meter was recorded. FIG. 5 shows the result.

FIG. 5 shows the position of the apex of the simulated melt with respect to the upper end of the coil, which affects the resonance frequency of the high frequency power supply.
That is, it is a diagram showing the effect of the height equivalent to the molten metal level.

As shown in the figure, the resonance frequency of the high-frequency power supply generally decreased as the height equivalent to the molten metal surface (the position of the top of the simulated melt) decreased. In this way, the relationship between the molten metal surface height and the corresponding resonance frequency was predicted.

Next, once the output of the high-frequency power supply was stopped, the simulated melt was taken out of the crucible, and instead, a dummy head was inserted from the lower end of the crucible to a position corresponding to the uppermost coil stacking height in the crucible. . Next, the scrap was charged into a hopper, and the atmosphere of the crucible was adjusted to an Ar gas atmosphere using an atmosphere chamber.

In this state, when the output of the high-frequency power supply was increased to a predetermined value, the dummy head melted and protruded in a dome shape. Subsequently, the supply amount control device was operated to set the molten metal level to a frequency corresponding to the upper end of the coil stacking height.
Thereafter, the drawing device was driven at a speed of 1.6 cm / min.

After the solidified material was pulled out by about 2 cm, titanium scrap was automatically supplied into the crucible from the material supply device. After continuous drawing for about 30 minutes, the supply of the material was stopped and the high-frequency power supply was stopped. As a result, a solid having a length of 50 cm was obtained.

When the inner wall of the crucible was carefully observed after the operation was stopped, the controlled level of the molten metal was equivalent to the level of the molten metal moving about 2 mm downward from the contact position between the target melt and the crucible. And the error was small. As a result of quality inspection of the obtained solidified material, no undissolved scrap was recognized,
No surface cracks were found.

(Example 2 of the Invention) Using the apparatus having the structure shown in FIGS. 1, 2 and 3, carbon steel in a molten state was supplied as a material through an immersion nozzle, and a solidified body was continuously formed. I got driving. The basic operating conditions are the same as those of the first embodiment of the present invention, but the main differences from the first embodiment of the present invention are as follows.

Crucible: material is copper, height is 1000 mm, inner diameter is 18
0mm, wall thickness 30mm Slit: 240mm length, 30 slits, 0.2mm slit gap Coil: 190mm inner diameter, 230mm outer diameter, 6 turns High frequency power: 200kW output, frequency 30kHz Coil current: 8kAT Cooling water pump: Water volume 450 liter / min, discharge pressure 80
00hPa Material supply device: Sliding gate control method Immersion nozzle inner diameter: 30mm Steel composition: C = 0.2%, Mn = 0.4%, Si = 0.3%, P = 0.02%, S =
0.02%, remainder = Fe Treatment speed: 2.2 m / min Superheat degree of molten carbon steel: 40 ° C. The treatment procedure was as follows.

First, the shape of the molten carbon steel placed in the crucible under the action of electromagnetic force was theoretically predicted. Although the density of carbon steel is higher than that of titanium, the longitudinal cross section of this shape roughly corresponded to the shape shown in FIG. 3 due to the presence of molten flux on the surface of carbon steel.

Next, a simulated melt having a shape corresponding to the case (F) in FIG. 4 was produced from a stainless steel material. At that time, in order to prevent melting by Joule heat, the inside was made to be a water-cooled structure, and the thickness of the outer skin was set to 20 mm. The thickness of the outer skin is about six times the skin depth of the electromagnetic field, and the electromagnetic interaction is the same as when the inside is filled. The difference between the electrical conductivity of the molten carbon steel and the electrical conductivity of the water-cooled stainless steel is within 1.5 times, and no significant error occurs in the measurement of the resonance frequency.

After supplying the cooling water, a high-frequency power supply is operated to supply a predetermined coil current to the coil, the simulated melt is gradually inserted from the upper end of the crucible, and the top of the simulated melt obtained from the distance meter is obtained. The relationship between the position of the radio frequency and the frequency of the high frequency power supply obtained from the frequency meter was recorded. As a result, the resonance frequency of the high-frequency power supply decreased as the height equivalent to the molten metal surface (the position of the top of the simulated melt) decreased, as in the case of Example 1 of the present invention. In this way, the relationship between the molten metal surface height and the corresponding resonance frequency was predicted.

Next, once the output of the high frequency power supply was stopped, the simulated melt was taken out of the crucible, and the dummy head was replaced from the lower end of the crucible with the uppermost coil stacking height.
It was inserted at a position in the crucible at the lower end of 250 mm. Subsequently, a ladle capped with a stopper and a tundish provided with a sliding gate were set on a crucible, and the molten carbon steel was charged into the ladle.

In this state, the output of the high-frequency power supply is adjusted to about 1/5 of a predetermined value and the control device for the supply amount is operated. Was set to a value corresponding to.

The temperature of the carbon steel melt in the ladle gradually decreased. When the temperature reached a predetermined degree of superheat, the stopper was opened, and the output of the high frequency power supply was increased to a predetermined value. The molten carbon steel in the ladle flowed into the crucible through the tundish and the sliding gate, and the level of the molten metal in the crucible rose. The drawer was driven at a speed of 2.2 m / min at a stage 30 mm before the molten metal surface almost reached the upper end of the coil. The water level in the crucible gradually increased, and eventually became stable.

After continuous drawing for about 30 minutes, the supply of the carbon steel melt and the high frequency power supply were stopped.
As a result, a solid having a length of 66 m was obtained.

When the inner wall of the crucible was carefully observed after the operation was stopped, the controlled level of the molten metal was equivalent to the level of the molten metal moving about 2 mm upward from the contact position between the target molten metal and the crucible. Was. As a result of quality inspection of the obtained solid, no entrapment of flux was observed below the surface layer, and no crack was present on the surface.

(Comparative Example) Melting and solidification of titanium scrap were continuously performed in substantially the same manner as in Example 1 of the present invention, except that the resonance frequency of the high frequency power supply and the height of the simulated melt were measured in advance. I went. In this case, a resonance frequency corresponding to a predetermined level of the molten metal was determined by visual observation. No change in the resonance frequency and no noticeable change in the surface level were observed during the operation for 30 minutes.

After the operation was stopped, when the inner wall of the crucible was carefully observed, the level of the molten metal moved 15 mm downward from the target contact position between the molten metal and the crucible. As a result of quality inspection of the obtained solid, undissolved portions of the scrap were recognized, and it was presumed that Joule heat was not generated in the molten metal as desired. Further, surface cracks were observed at about 20 places per 10 cm in the solidified body. in this way,
When the level of the molten metal is specified by visual observation, there is an error in the height of the molten metal, and the quality of the obtained product is not stable.

[0087]

According to the present invention, the starting position of solidification can be accurately controlled. As a result, it is possible to achieve reduction in surface layer inclusions and surface cracks of the obtained solidified body and improvement in quality.

[Brief description of the drawings]

FIG. 1 is a conceptual vertical sectional view showing a configuration example of a device of the present invention.

FIG. 2 is a conceptual bird's-eye view showing a configuration example of a crucible 2 used in the apparatus of FIG.

FIG. 3 is a conceptual vertical sectional view showing another configuration example of the device of the present invention.

FIG. 4 is a diagram showing an example of a predicted longitudinal cross-sectional shape of a melt when a coil current value and a molten metal level are used as parameters.

FIG. 5 is a diagram showing the influence of the position of the apex of the simulated melt with respect to the coil upper end, that is, the height equivalent to the molten metal level, on the resonance frequency of the high-frequency power supply.

[Brief description of reference numerals]

1: slit, 2: crucible, 3: coil,
4: solidified withdrawal device, 5: material supply device, 5'-1: solid material, 5'-2: melt material, 6: cooling water supply device, 7: high frequency power supply,
7 ': frequency meter, 8: control device for material supply amount,
9: melt, 10: solidified, 11: atmosphere control chamber, 12: molten surface, 13: solid-liquid interface, 14: simulated melt, 15: distance meter, 16: insertion device for simulated melt, 17: Dummy head, 18: ladle,
19: Tundish, 20: Immersion nozzle,
21: Sliding gate, 22: molten flux, 23: unmelted flux

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22D 11/16

Claims (2)

(57) [Claims] 1. A vertical conductive crucible having a slit having an insulating function along a drawing direction of a solidified body and having a water cooling function, and a coil disposed in the vicinity of the slit so as to spirally surround the crucible. , Solid-state extraction device, solid or molten material supply device to crucible, cooling water supply device, high-frequency power supply, frequency meter for detecting the resonance frequency of high-frequency current flowing from this power supply to the coil, A control device that controls the supply of solid or molten material using the values as input data, and additionally the electrical transmission of the melt in the crucible.
Uncooled or cooled structures to mimic the Shirubedo and melt-surface shape
Apparatus for inserting a solid body in the crucible, and comprising the atmospheric adjustment chamber as required material solidifies or melting, solidifying device. 2. A method for solidifying or melting and solidifying a material using the solidifying or melting and solidifying apparatus according to claim 1, wherein
Before starting operation of the equipment, the electrical conductivity of the melt in the crucible and
The solid that simulates the fine melt surface shape is inserted into the crucible, the relationship between the resonance frequency of the high frequency current flowing to the position and the coil of the solid body of this measure in advance, during operation of the apparatus was measured in advance resonance A method for solidifying or melting and solidifying a material, comprising estimating a position of a melt in a crucible from a frequency value.