JPS62203648A - Electromagnetic coil apparatus for continuous casting mold - Google Patents

Abstract

PURPOSE:To adjust to the demanded steel quality by arranging at least three electromagnetic coils at outer part of a Cu-plate mold for a continuous casting and supplying selectively a polyphase AC current, DC current or superimposed AC to DC current to generate stirring force, controlling force or combination force of the both in the molten steel. CONSTITUTION:The cases 3 storing the electromagnetic coils are arranged at side parts of the long side of the Cu-plate mold for the continuous casting and they having tau1 and tau2 lengths and each three exciting magnetic coils 40a1-40c1, 40a2-40c2, 41a1-41c1, 41a2-41c2, are arranged. Next, star- connection or delta-connection is executed to the power source and the polyphase AC current, DC current or superimposed AC to DC current is selectively supplied, and the electromagnetic stirring force, electromagnetic controlling force or combination force of the both is selectively generated in the molten steel in the mold. Therefore, in accordance with the steel kind to be cast, and the steel quality to be demanded, adjusting in them is executed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to an electromagnetic stirring system and an active method for actively horizontally flowing /8 steel injected into a continuous casting mold. The present invention relates to an electromagnetic coil device that can individually or simultaneously perform electromagnetic braking to bring the device to a standstill.

[Conventional technology]

When molten steel with a low degree of deoxidation is poured into a mold for continuous casting,
CO gas and a small amount of H2 gas, 7N2 gas, etc. are generated in the mold. If solidification begins while these gases remain in the molten steel, it will cause defects such as pinholes in the product. Therefore, in the field of continuous casting, a method has long been employed in which molten steel poured into a mold is electromagnetically stirred so that it actively flows horizontally within the mold.

In the conventional i% magnetic stirring method, molten steel is poured into a mold housed as an electromagnetic stirring device (↑ device), and a multiphase inductor that acts similarly to the stator of a linear motor is injected into a mold, and the electric stirrer is heated with three-phase or two-phase alternating current. By supplying electric power, an electromagnetic force is applied to 8 yen to generate a horizontal flow of about 0.1 to 1.0 m/sec (Japanese Patent Laid-Open No. 53-28034, Japanese Patent Publication No. 58-52456). Publication, Japanese Patent Publication No. 58-52457, Japanese Patent Publication No. 5B-35787, Japanese Patent Publication No. 59-5
Publication No. 057, Special Publication No. 59-7536, Special Publication No. 5
No. 8-7537, Japanese Patent Application Laid-open No. 56-41054,
(See Japanese Patent Application Laid-Open No. 60-223649, etc.).

Furthermore, the molten steel injected into the mold is accompanied by minute inclusions, and flux is caught in the molten steel during injection. If such inclusions or flux remain in the molten steel and start solidifying, it will similarly cause defects in the product. Therefore, electromagnetic braking has been used for a long time as a method for quickly floating and absorbing these inclusions and flux into the absorption flux above the molten steel in the mold.

As such an electromagnetic braking method, a static magnetic field is applied to the molten steel flow being injected into the mold using a permanent magnet placed between the molten steel poured into the mold or :rL (41 stones). By actively slowing down the flow velocity, it is possible to prevent accompanying minute inclusions and entangled flux from penetrating deep into the ?8 steel, and to encourage them to surface due to buoyancy. (Refer to JP-A-57-17356, JP-A-58-188555, etc.).

[Problem that the invention seeks to solve]

The electromagnetic stirring method and electromagnetic braking method listed above use independent electromagnetic stirring devices and electromagnetic braking devices, respectively, and have different effects to solve different problems.

However, in actual operations, when manufacturing shell materials, there are steel types to which the electromagnetic stirring method is applied and steel types to which the electromagnetic braking method is applied, and these steel types are usually not the same. Furthermore, in the production of high-grade steel grades, it may be desirable to use both electromagnetic stirring and electromagnetic braking in combination.

However, having a dedicated continuous casting machine for each type of steel not only requires a large amount of equipment cost, but also does not necessarily allow for a high operating rate of the equipment. Therefore, this dedicated continuous casting machine for each type of steel cannot be called an industrial solution. Therefore,
A mold for electromagnetic stirring and a mold for electromagnetic braking are prepared together with respective control devices, and these molds for electromagnetic stirring and mold for electromagnetic braking are rearranged and used depending on the type of steel. However, this rearrangement requires a great deal of time and effort to remove and install each mold, and continuous casting must be suspended during that time. As a result, the productivity of continuous casting equipment decreases. In addition, the number of deceleration-stops and start-up accelerations increases in response to this rearrangement, which causes changes in the cooling rate, solidification coefficient, etc., resulting in variations in the quality of the slabs and problems such as a decrease in yield. Furthermore, since the electromagnetic stirring mold and the electromagnetic braking mold cannot be used at the same time,
It was unsuitable for producing high-grade steel. In other words, recombining and using magnetic stirring molds and electromagnetic braking molds is economical, effective, etc. when trying to improve the quality of slabs and the quality yield of products to be manufactured. This includes problems.

Therefore, an object of the present invention is to solve these problems and to economically and efficiently manufacture slabs of excellent quality.

[Means for solving problems]

In order to achieve the object, the present invention disposes at least three independent electromagnetic coils outside a continuous casting mold copper plate along the width direction of the mold, and applies an electromagnetic stirring force to the molten steel in the mold. , multiphase alternating current, series current, or AC/DC superposition for selectively applying electromagnetic braking force or a combination of both.
Each of the electromagnetic coils is connected to a power source that can selectively supply clear liquid, and the three or three pairs of Tl electromagnetic coils are used in Y-connection or Δ-connection to the power source. be able to.

[Function] According to experiments and studies conducted by the present inventor using the known electromagnetic stirring device shown in FIG. Weak deoxidation injected into the mold by generating a magnetic field with a magnetic flux distribution as shown in fa+,
Magnetic stirring was performed on non-sedated molten steel. As a result,
It was confirmed that the bubble generation prevention results were as good as any of the conventional techniques. In the H1 device with such a configuration, a direct current of /A was applied to each coil as shown in Figure 3 (b), a magnetic field with a magnetic flux distribution as shown in Figure 4 fbl was generated, and the magnetic field was injected into the mold. Deoxidation, sedation, and braking operations were performed. As a result, as shown in FIG. 5(8), the number of inclusions was reduced to 1710 by about 100%.

Furthermore, an operation was performed in which electromagnetic stirring and electromagnetic braking were performed simultaneously by passing an alternating current with a DC bias as shown in Figure 3 (C) and generating a magnetic field with a magnetic flux distribution as shown in Figure 4 tc+. When it is done, l00
7! The number of inclusions on the order of II+/Q was reduced to 1/100 or less.

In addition, when an electromagnetic braking force is applied to each discharge part of the immersion nozzle to control the discharge amount, that is, the amount of injection into the mold, about 100 units per 10 kg of molten E and about 7 units per 40 units are inserted. Detection of objects has become virtually non-existent.

This is considered to be due to the synergistic effect of the effect of reducing the injection flow rate and the effect of completely blocking outside air from entering the molten steel in controlling the discharge amount.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

In this example, first, a power supply device capable of supplying each of multiphase alternating current, direct current, and a superimposed current of both was prepared.

Figure 1 (al and (bl) shows the state in which the electromagnetic coil, which is operated by being connected to this power supply device, is placed in the tR mold for continuous casting.

The inside of the continuous casting mold is equipped with a long piece copper plate 1 and a short side copper plate 2. A frost 3 for housing an electromagnetic coil is arranged on the side of the long side copper plate 1. Each electromagnetic coil is equally divided into 2n pieces (n is l or 2). Second
The illustrated example shows an example where n=1, and is divided into distances rl+τ2 along the long side direction. This distance τ1 and te2 are
They shall have the same length, and are set in the range of approximately 200 to 1000 mm.

Within this distance ^+tr,,τ2, the magnetic paths of m independent excitation coils (m is an integer multiple of 3) are connected to the core 5 of the silicon steel plate.
Connect at. FIG. 1 shows three (m=3) excitation coils 40a+ with lengths τ1 and τ2.

40b+, 40c+, 40ax, 40bt,
40cz, 41a +, 41b+, 41c
+, 41az.

An example is shown in which 41bg and 41c4 are wound and arranged in a direction perpendicular to a long piece of copper plate l. FIG. 1fbl shows another example of the arrangement of excitation coils, in which three (m=3) excitation coils 40ao, 40bo, 4
0c+.

41ao, 41bo, and 41c0 are wound and arranged in a direction parallel to the long copper plate l.

FIG. 2 (al), (a2), and (b) show each of the coils 40a++40b++40C+, 4 in the storage box 3.
0az, 40bz+40Cg+41a+, 41bz4
The wiring diagram of 1cz41at, 41bz, and 41Cz is shown.

In the wiring diagram, 40a1 and 40az, 40b+ and 40b.

and 40c, and 40c2 are each connected in series,
(al) further performs a foot-shaped connection with the 0 point as the midpoint, and (
b) Cut terminals 40a, 40b, and 40c from point 0 to Wlt L, and connect terminals S and I? respectively. , connect to T and Δ
It shall be possible to perform wiring. Here coil 40
The connection or winding method of a1 and 40at is jil + Ki'
i Wind the coils in the same direction and reverse the connection direction as shown in Figure 2 (al) so that the current flows in the opposite direction, or wind the coils in the opposite direction as shown in Figure 2 (a2). It shall be wrapped around. The same applies to 40b1 and 40bt, 40c+ and 40c2. Points R, S, and T indicate the coil terminals after connection at the 0 point.

11, +5. IT indicates a three-phase AC excitation current that excites each coil. 41a+, 41tl+, 41C+, 4
1az, 41bz.

Similar connections are made for 41Cz.

FIG. 3 (al indicates the excitation current used to excite the coil with three-phase alternating current).

Three-phase current that changes over time from terminals R, S, and T in Figure 2! By exciting each coil with Is, Iy, a magnetic field whose magnetic flux density changes over time is generated within the mold. FIG. 4+al shows the magnetic flux density distribution in the long side direction of the magnetic field inside the mold generated at this time.

The magnetic flux density distribution curve of the magnetic field moves in the long side direction a (or in the opposite direction to a) over time. An induced current is generated in the molten steel due to the movement of the magnetic flux density distribution, and due to the electromagnetic force generated by this induced current and the magnetic field, the molten steel in the mold is energized in the same direction as the movement direction of the magnetic flux density distribution. ■ Flow occurs in the molten steel as a result of the driving force.

The generation of the molten 1i1 flow f)+ suppresses the generation of CO bubbles during the solidification process during casting of non-n+h acid steel, and prevents the generation of pinholes under the surface of the slag.

Next, FIG. 3 (bl shows the excitation current when the coil is supplied with direct current. In other words, I + + + + I
By exciting with a DC excitation current that does not change over time, which sets IIT to 11g'' Its+It↑-0, a DC magnetic field whose Lit flux density does not change over time is generated within the υ1 type. Fig. 4 fbl represents the magnetic flux density distribution in the long side direction of the magnetic field generated within the mold at this time.

By generating a Gfi field having such a magnetic flux density distribution, it becomes possible to apply an electromagnetic braking force to the injection flow injected into the mold from the immersion nozzle. Moreover, 1
111. 11! , the value of IIT is I +++ +I
+i←11a=0, and by arbitrarily changing the ratio of DC current, the peak value of the magnetic flux density distribution of the 61 field generated in the mold, and the magnitude and position of (T: arbitrarily adjusted). This allows the braking force to be applied most effectively in accordance with the injection flow distribution from the immersion nozzle and the desired braking position.

Furthermore, by applying an excitation current that is a superimposition of three-phase alternating current and direct current shown in Fig. 3 ta+ and Fig. 3 tbl to the coil, the above electric tn driving force is generated simultaneously with 'TL 1 while applying the necessary braking force.
It is also possible to carry out the desired stirring.

Figure 3 (C1 shows an example of the excitation current at this time. Figure 4 (C1 shows the magnetic flux density distribution in the long side direction of the magnetic field in the mold at this time, and shows the basics of the braking force without moving in time. The magnetic flux density distribution Boc, which becomes
A strong magnetic flux density distribution for braking and stirring can be obtained.

In order to generate the three types of excitation currents as described above, the present invention prepares a power supply device that is known per se and is capable of supplying each of multiphase alternating current, direct current, and a superimposed current of both.

In addition, in the above embodiment, an example is shown in which the three-phase alternating current is applied to three excitation coils, but the excitation coils are
Needless to say, it is possible to use the above n number of elements and to flow an n-phase polyphase alternating current through them.

〔Effect of the invention〕

As described above, the present invention provides multiphase AC excitation or DC excitation, or DJ magnetism in which multiphase AC and DC are superimposed, to the excitation coil placed in the mold. Since it can be carried out in a large amount, one electromagnetic force generating device can be applied to the molten steel in the mold without interrupting the continuous casting operation. ii.
: The internal quality can be adjusted economically depending on the type of steel to be manufactured and the desired quality. As a result, it has become possible to provide steel materials that meet the desired material quality at low cost, which brings about great effects.

[Brief explanation of drawings]

Figure 1 t(l), tb) shows the electromagnetic coil placed in the mold, +81 is the coil wound in the direction perpendicular to the 1-no.
An example of winding the file is shown below. Also, Figure 2 (al), (a
2) and (b) respectively show the wiring diagrams of the coils in Fig. 1. Figure 3 (a+ indicates coil excitation current during multi-phase AC excitation, Figure 3 (bl indicates coil excitation during DC excitation), and tel indicates coil excitation when multi-phase AC and DC are superimposed. Figure 4 (al shows the magnetic excitation density distribution in the mold during multiphase AC excitation, and Figure 4 (b) shows the excitation density distribution in the Sli mold during DC excitation. Figure 4 (cl shows the mold-like magnetic flux density distribution when excitation is performed with multiphase alternating current and direct current superimposed. Figure 5 shows the relationship between the operating method and the amount of inclusions in molten steel in an experimental example of the device of the present invention.

Claims (1)

[Claims] 1. At least m pieces (m
2n electromagnetic coils (where n is an integer multiple of 3) are arranged along the width direction of the mold, and apply electromagnetic stirring force, electromagnetic braking force, or a combination of both to the molten steel in the mold. An electromagnetic coil device for a continuous casting mold, characterized in that each of the electromagnetic coils is connected to a power source that can selectively supply a multiphase alternating current, a series current, or an AC/DC superimposed current for selective operation. 2. Claim 1 characterized in that m electromagnetic coils are configured to be excited by Y-connecting them to a power supply terminal.
An electromagnetic coil device for continuous casting molds as described in 2. 3. Claim 1 characterized in that m electromagnetic coils are configured to be energized by being Δ-connected to a power supply terminal.
An electromagnetic coil device for continuous casting molds as described in 2.