JPH0394967A - Method for discharging molten metal from bottom pouring type vessel - Google Patents

Abstract

PURPOSE:To control discharge rate of molten metal discharged from a nozzle per unit time by arranging controlling means for frequency and voltage of electric power supplied to an induction coil or tap switching means for number of turns in the induction coil. CONSTITUTION:At the time of discharging the molten metal from the nozzle part 21, forced cooling means in the nozzle is stopped. Successively, AC power is supplied to the induction coil 25 set at the outer circumference of the nozzle part 21 from an electric power source through a frequency converter 27 and matching device 26. By this method, the discharge of molten metal from the nozzle part 21 is executed by induction-heating and melting a metal piece 22 in the nozzle. After starting the discharge of molten metal, the supplying power to the induction coil 25 is reduced. Further, at the time of heating the nozzle part 21 with the induction heat, by executing the adjustment of frequency and voltage in the supplied electric power, control of the discharging rate of molten metal per unit time from the nozzle can be attained.

Description

[Detailed Description of the Invention] A. FIELD OF THE INVENTION The present invention relates to a method for discharging molten metal from a nozzle in a bottom pouring vessel for storing and tapping molten metal (molten and semi-molten metal).

B. SUMMARY OF THE INVENTION This invention has a wide variety of methods for discharging molten metal from a bottom-pour container, by disposing an induction coil around the outer periphery of a nozzle part, and by adjusting the frequency and voltage of the electric power supplied to the induction coil. By controlling the amount of molten metal discharged from the nozzle by switching the tap on the coil, it is easy to create a bottom-pour container without using a nozzle opening/closing mechanism such as a stopper or sliding method. I can do it,
This makes it possible to dispense high-quality molten metal or semi-molten metal without any slag or oxides being rolled up, and to control the extraction from the nozzle.

C. Conventional technology Metals are melted and then subjected to composition adjustment and refining, semi-molten metals are produced or stored, and then poured into molds, or metals in a molten or semi-molten state are melted. In the process of continuously casting to obtain intermediate products and rolling them into primary products, after melting and adjusting the metal, the furnace body and storage container are not tilted. A method is used in which the molten metal (molten and semi-molten metal) is tapped from the bottom or near the bottom and poured into a mold or poured into a tundish. This method is shown in FIG. In Figure 6, the melting furnace body! Form a nozzle part II at the bottom of the nozzle.

The nozzle l1 is a stopper body 12 usually made of fireproof material.
When the molten metal 13 in the melting furnace main body IO is to be discharged, the stopper main body 12 should be raised using an operating device (not shown).

As a result, the molten metal I3 is discharged from the nozzle portion l1. In addition, in FIG. 6, 14 is a heating coil.

In the case of a bottom-pour melting furnace body (Yongxe) as shown in Figure 6, impurities such as slag and oxides floating on the surface of the melt can be prevented from getting mixed into the discharged molten metal. In addition, since the furnace body can be left fixed without tilting, it is easier to pour into a mold or pour water into a dandelion in a vacuum or inert gas atmosphere, compared to when the furnace is tilted. It is also extremely easy.

D. Problems to be Solved by the Invention However, the stopper body 12 shown in FIG. 6, which controls the tapping of metal by the bottom-pouring melting furnace, has a problem in that its use is limited due to the fire resistance and lifespan of the stopper body. For example, when performing high-temperature processing such as in a melting furnace or an oxygen-blown smelting furnace, unreliable and expensive refractory materials must be used. Furthermore, in the case of semi-molten metal, temperature control at the discharge port of the nozzle section 11 is important, and it is necessary to avoid the inability to raise the stopper body I2 due to solidification near the nozzle section 11 and the stopper body I2 due to temperature drop. If the stopper body 12 or the operation l4 is not maintained, the inability to maintain the semi-molten state resulting in overheating or the agitation in the furnace body IO, which is often used in the semi-molten metal processing process, may cause overheating. l
]2a, slider frame 12b that slidably holds the operating handle 12a
i″7: positionally inhibited by presence, i.e.
Mechanically insert a stirrer (not shown) into the furnace main body IO,
By rotating the stirrer by U°, the stirrer does not collide with the stopper body 12 and the like during stirring (it is necessary to set the stirrer in the t position), which poses a problem of insufficient stirring in the vicinity of the stopper body 12.

In addition to the above-mentioned problems, while the stopper body 12 is melting the metal in the furnace body 1O, the stopper body I2 is also ripened together with the metal in the furnace body, causing thermal expansion. Therefore, an excessive compressive load (thermal stress) is generated in the stopper body l2 due to thermal expansion, and this stress is applied to the operating rod 12a of the stopper body l2, causing the operating rod 12a to buckle or deform in extreme cases. may break or break. Furthermore, if the operating rod 12a is broken, a problem arises in that the stopper main body l2 cannot be raised and hot water cannot be tapped.

Furthermore, there is another problem in that the discharge air (discharge speed) of the melt discharged from the nozzle ffill cannot be adjusted during discharge. This also means that the flow of the molten metal discharged from the nozzle (discharge speed) changes as the agitation (height of the scene) of the molten metal in the furnace body and storage container changes. Another problem is that it is difficult to discharge the molten metal without maintaining the discharge amount.

Additionally, a sliding nozzle opening/closing mechanism has been used in the past, but it has the same problems as the stopper type described above.

This invention solves the problems in non-tilting bottom pouring furnaces, etc., makes it possible to discharge molten metal without using a stopper or a sliding nozzle opening/closing mechanism, and makes it possible to reduce the amount of molten metal discharged during discharge. (discharge speed) can also be adjusted.

However, it is an object of the present invention to provide a method for discharging molten metal from a bottom pouring type container, which is suitable for discharging not only molten metal but also semi-molten metal.

E. Means for solving the problem (1) Discharging molten metal from a bottom-pour container equipped with a nozzle for discharging molten metal at the bottom of the container used for melting, refining, or storing molten metal. In the method, 67
In addition to the arrangement of the induction coil around the outer periphery of the nozzle section in item 7,
The frequency and voltage (current) of the power supplied to the induction coil are provided with one or more of means for reducing the frequency and voltage of the power supplied to the induction coil and means for changing the tap of the number of turns of the induction coil. The amount of molten metal discharged from the nozzle per unit time is controlled by adjusting the number of turns of the induction coil or changing the tap of the number of turns of the induction coil, or a combination thereof.

F. Put the metal to be melted into the working container and before starting to melt the metal, or before injecting the molten metal into the container, place the metal in the nozzle in advance and cool the nozzle so that the metal in the container melts. The inside of the nozzle is closed so that molten and semi-molten metal does not flow out from the nozzle even after starting. In addition, if metal is not placed in the nozzle in advance, molten or semi-molten metal solidifies in the nozzle at an early stage, thereby clogging the nozzle (7). The metal inside the nozzle is heated by an induction coil.This heating melts the metal inside the nozzle and starts discharging (discharging) the metal from inside the container.

When melting the molten and semi-molten metal in the container as described above, if the molten and semi-molten metal in the container is Even when hot water is tapped with metal pieces, metal from the pond will not be mixed in. Also, when heating the nozzle part with induction heating, by adjusting the frequency and voltage of the supplied power, the water from the nozzle can be adjusted. It is also possible to control the amount of hot water dispensed per unit time.

G. Example Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, a container 20 is a melting furnace made of a refractory material, and a nozzle portion 2l is formed at the bottom of the container 20. A metal piece as a dummy plug made of metal having the same composition as the metal to be melted in the container 20 is provided inside the nozzle 2l. This metal piece 22 is brought into contact with a water-cooling fitting 23 from below that serves as a forced cooling means. 24 is a heating coil disposed around the outer periphery of the container 20, and 25 is an induction coil that heats the nozzle portion 2l. The induction coil 25 is connected to a frequency converter 27 via a matching device 26 . 2
Reference numeral 8 indicates a voltage adjustment setting device connected to the frequency converter 27, and numeral 29 indicates a frequency adjustment setting device connected to the frequency converter 27. 30 is a molten metal (molten and semi-molten metal).

In the embodiment configured as described above, first, at the start of melting or before entering the molten metal (in a ladle or tundish), a metal piece 22 as a dummy par is inserted into the nozzle part 2l, and the metal piece 22 is inserted into the nozzle part 2l. 21 is forcedly cooled through a water cooling fitting 23.

The metal piece 22 preferably has the same composition as the molten metal at the time of tapping. Molten toothpick enters the gap between the metal piece 22 and the inner wall of the nozzle portion 2l and is solidified by the forced cooling means, so that the nozzle portion 2l is completely blocked.

In addition, when the melting progresses gradually from the cold material, or when molten metal at a low temperature close to the melting temperature or metal in a semi-molten state is injected, it may be omitted to insert the metal piece 22 in advance. This is because by cooling the nozzle part 21 by a forced cooling means, the low temperature molten metal 30 at the early stage of melting and the injected semi-molten metal immediately enter the nozzle part 21. This is because it solidifies and completely blocks the nozzle portion 2l.

Note that in the case of semi-molten metals, etc., cooling is not performed as described above, and the inside of the nozzle will naturally become clogged and the nozzle hole 2 will become clogged.
Occlusion of l is often realized.

The inside of the nozzle appears to be blocked by solid metal.
Melting, smelting, and pouring molten and semi-molten metal into containers. To discharge metal (discharge of molten metal or semi-molten metal) from the nozzle section 2I, the forced cooling means inside the nozzle must be stopped (
(e.g., removing the water cooling fitting 23, stopping water flow to the water cooling coil described later, or stopping the spraying of cooling fluid, etc.). An induction coil 2
5 is supplied with alternating power from a power source via a frequency converter 27 and a matching device 26. This causes the metal piece 2 inside the nozzle to
2 by induction heating and melting the nozzle part 2.
Take hot water from l.

After the hot water starts being tapped, the power supplied to the induction coil 25 is reduced. Note that when tapping metal in a semi-molten state, the nozzle portion 2
Smooth hot water can be ensured from 1.

Even when using the metal piece 22 as a dummy bar to block the nozzle portion 2l before injection of molten metal and semi-molten metal, the component of the metal piece 22 is almost the same as the composition of the molten metal and semi-molten metal to be tapped. If it is, the initially tapped molten metal and semi-molten metal can be used as molten metal and semi-molten metal of the same composition. Otherwise, even if metal pieces 22 with different compositions are used, a small amount of the initial molten metal and semi-molten metal is discarded,
Subsequent molten metals and semi-molten metals may be used.

Next, as described above, the guide film 2 is placed around the outer periphery of the nozzle part 2I.
5 and continue to supply alternating power to the coil 25,
The molten metal and semi-molten metal passed through the nozzle and discharged are discharged through a magnetic field generated by an alternating current flowing through an induction coil 25 in the nozzle, as shown in FIG. Then, an induced current in the opposite direction to the current flowing through the induction coil 25 is induced in the molten metal and semi-molten metal, and flows in the molten metal and semi-molten metal in the nozzle. Then, due to the interaction with the magnetic field, a force toward the center of the nozzle 21 acts on this induced current. Therefore, a pinch effect acts on the molten metal and semi-molten metal passing through the nozzle. This pinch effect works to narrow the passage of molten metal and semi-molten metal in the nozzle, so when the coil current is increased by increasing the voltage of the power applied to the induction coil 25, the magnetic field in the nozzle is strengthened and the pinch occurs. Due to the increased efficiency, the discharge ffl/hour (one discharge speed) of molten metal and semi-molten metal can be reduced.

Note that increasing the coil current will also increase the induction maturing effect of the molten metal and semi-molten metal in the nozzle, which will also lead to an increase in the tapping temperature, so if you want to avoid this, increase the frequency of the power supplied to the coil. You may change it. Note that lowering the frequency increases the binge effect. Further, the adjustment may be made by combining the frequency, the applied voltage, the number of turns of the coil (the number of turns to which power is applied), etc.

Next, the tapping (discharging) is stopped in the middle of tapping by cooling the nozzle section 21 again and solidifying the metal itself within the nozzle. In particular, in the case of molten metal in a semi-molten state or at a low temperature close to the melting point, the viscosity of molten metal and semi-molten metal is high, and it will solidify with a small amount of heat radiation, so it is necessary to continue smooth tapping. In many cases, it is necessary to continue supplying a reduced amount of electric power to the induction coil 25 even during hot water dispensing. In such a case, simply stopping the supply of power to the induction coil will stop the discharge of molten metal and semi-molten metal.

Furthermore, according to the present invention, molten metal and semi-molten metal can be easily and reliably tapped from the bottom of a furnace, etc., without using a stopper body, etc. It is also easy to use casting and pouring in gas.

In FIG. 3, a tapping nozzle portion 2l is provided on the side of the container (melting 78, side-drawing), and an induction coil 25 for heating is provided around the outer periphery of the nozzle portion 2l.

In addition, as means for forcibly cooling the inside of the nozzle, in addition to using the water cooling fitting 23 shown in FIG. It is possible to use a method of cooling the metal piece 22 from the outer periphery thereof, or a method of forcibly cooling the metal piece 22 in the nozzle by spraying a cooling fluid (gas) with a vibrator 36 as shown in FIG. In addition, when tapping semi-molten metal or low-temperature molten metal or semi-molten metal during the semi-solidification process, the inside of the nozzle may naturally become clogged and clogged, so in such cases, Cooling means may not be necessary.

Furthermore, even in conventional bottom-pouring furnaces and storage containers equipped with the above-mentioned stopper and sliding nozzle opening/closing mechanism, an induction coil is arranged around the nozzle part, and 07j
As shown in the figure, a means for reducing the current value, frequency, etc. of the alternating power supplied to the induction coil is provided, and by adjusting the current value, frequency, etc., the discharge amount (discharge speed) of the molten metal discharged from the nozzle is controlled. Can be adjusted.

According to the two consecutive examples, the following effects can be obtained.

(a) In the conventional bottom pouring method, the stopper body or sliding nozzle, etc. had to be used, so there were many problems with the fire resistance of the stopper body, the life of the stopper body, and the mechanism. Therefore, although the bottom pouring type is far superior, these problems have become a constraint, and the tilting type has often been adopted instead of the bottom pouring type. In the embodiment, the above-mentioned problem is solved without using a stopper main body, so the bottom pouring type can be easily adopted.

(b) Therefore, the bottom pouring method makes it easy to tap high-quality molten metal and semi-molten metal without entrainment of slag, oxides, etc.

(c) A part of the stopper body etc. will not melt or break and will not enter the molten metal or semi-molten metal as foreign matter.

(d) There is no need for a stopper main body, etc. and its operating mechanism, etc., and from this, it is possible to avoid complicating the structure of the furnace, etc., and create a simple furnace body similar to the tilting type. This is particularly advantageous when obtaining a bottom-pouring type induction melting furnace, when performing refining in a furnace, and when performing high-temperature melting.

(e) When it is necessary to obtain better quality molten metal and semi-molten metal by avoiding oxidation and gas absorption of the molten and semi-molten metal during tapping, tap tapping in a vacuum or atmospheric gas is performed. It is easy to do. .

(") As in the semi-solid processing process, metal in a semi-molten state or molten metal close to the melting point temperature is passed through a nozzle or S using a bottom lug method.
When discharging, etc., connect power to the induction coil in the nozzle and continue supplying it. Top 1: Discharge metals in a semi-molten state or near the melting point without clogging due to temperature drop inside the nozzle. It has a thick effect that makes it easy to hold it smoothly and stably. Moreover, since it is electrically controlled, the temperature and amount of the semi-molten metal discharged from the nozzle can be easily controlled to suitable conditions with high precision.

(g) During the discharge of molten metal and semi-molten metal from the nozzle, heating of the metal in the nozzle can be stopped, or discharging can be stopped by forced cooling means in the nozzle.

(h) There is no need for troublesome work such as replacing the stopper body every time or adjusting the joint between the stopper body and the nozzle to prevent leakage. In addition, it is possible to avoid accidents during melting due to failure of the spring 1, the spring body, etc. These factors can improve production efficiency.

II. As described in ``Effects of the Invention'', according to the present invention, an induction coil is disposed in the nozzle part, and means for adjusting the voltage (=current value), frequency, etc. of the alternating power supplied to the induction coil is provided. By adjusting the current value, frequency, etc. supplied to the induction coil, you can control the amount/time of hot water coming out of the nozzle. This also means that in processes where molten metal is continuously added to the molten metal, such as by continuous casting and rolling, or by extrusion, it is necessary to adjust the discharge amount of molten metal and keep it constant. This has particularly great effects, such as being able to easily maintain the emissions at a level of .

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the nozzle section, and Fig. 3 is a melting furnace in which the nozzle section is installed on the side of the furnace bottom. A schematic configuration diagram showing an actual example of heating, Fig. 4 is an enlarged sectional view of a nozzle section with an induction coil and a water cooling coil provided on the outer periphery, and Fig. 5 is a case where cooling fluid is sprayed to cool the inside of the nozzle. FIG. 6 is an enlarged cross-sectional view showing an actual example of this, and FIG. 6 is a cross-sectional view showing the schematic structure of a conventional bottom-pour container. 20... Container such as melting furnace, 2l... Nozzle part, 22...
- Metal piece, 23... Water cooling fitting, 24... Heating coil, 25... Induction coil, 30... Molten metal and semi-molten metal. Figure l - Js Sheep Curse 91 Oim Logi Jin 1h Text 020-...
・Ichigo I Drink Figure 2 Nozzle tpf) Hirodai is thinning edict Figure 3 橢 ``Tani Kaiguran■ Figure 4 A2 no fruit banro・l! ! FR side view Figure 5

Claims (1)

[Claims] (1) In a method for discharging molten metal from a bottom-pour container in which a nozzle section for discharging molten metal is disposed at the bottom of the container used for melting, refining, or storing molten metal, the outer periphery of the nozzle section is provided. An induction coil is disposed in the induction coil, and one or more of means for adjusting the frequency and voltage of the electric power supplied to the induction coil and means for changing the tap of the number of turns of the induction coil are provided, and the electric power is supplied to the induction coil. The bottom pouring method is characterized in that the amount of molten metal discharged from the nozzle per unit time is controlled by adjusting the frequency or voltage of the electric power, or by changing the tap of the number of turns of the induction coil, or by a combination thereof. Method for discharging molten metal in a type vessel.