JPH0471759A - Method for controlling fluidity of molten metal - Google Patents

Abstract

PURPOSE:To continuously cast a clean steel having extremely little inclusion by independently controlling coil current conducted to each of plural pairs of electric magnet coils set to outer surface of a tundish, changing magnetic field distribution and executing control of fluidity. CONSTITUTION:By setting the electric magnets 8 at between a molten metal supplying part (ladle nozzle) 3 and a discharging part (tundish nozzle) 7 in the tundish 1, the fluidity of molten metal 5 is controlled. Then, at both outsides of the tundish 1, plural pairs of electric magnets 8 formed with small sized coil, are set. The coil current conducted to the individual magnet coil 8 can be independently controlled. Then, according to variation of the fluidity of molten metal 5 in the tundish 1, distribution of the magnetic field is varied to control the fluidity. By this method, flow of the molten metal can be freely controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for controlling the flow of molten metal in a tundish in continuous casting.

<Prior art> In general, in continuous casting, as shown in Fig. 5, the ladle 2
A weir 6 is disposed inside the tundish 1 to float and separate inclusions or ladle slag in the molten metal supplied from the ladle nozzle 3 to the tundish 1, thereby controlling the flow of the molten metal 5. The flow is made to rise or become laminar. However, arranging a weir at Tanditshu had problems such as high cost and difficulty in laminarizing the flow of molten metal with a weir, making it impossible to obtain sufficient effects. .

As a solution to the above problems, Japanese Patent Application Laid-Open No. 63-1407
The technology disclosed in Publication No. 45, as shown in Figure 6,
Instead of this weir, a pair of electromagnets 8 are arranged on both sides of the tundish 1 to brake the flow of the molten metal 5 and create a laminar flow to promote floating and separation of the inclusions and ladle slag. It's a method.

A pair! In the method of controlling the °ζ flow using a magnet, when the flow changes due to an increase or decrease in the injection amount,
! Various problems such as the difficulty of controlling the strength of the molten metal flow by changing the strength of the magnet and the impossibility of instantly changing the position of the electromagnet to control the direction of the flow. was there. In addition, when the gap between the electromagnetic coils is wide, the magnetic field strength is the lowest in the middle between the coils, and there is a problem in that it is difficult to completely control the strong flow that occurs in that area.

<Problems to be Solved by the Invention> In order to solve the above problem, the present invention provides a flow control method that can freely control the flow of molten metal and reduce inclusions in molten steel by providing a plurality of electromagnets. It was done in order to

Means for Solving the Problems〉 The present invention provides a means for solving the problems of the present invention.
! In the method of controlling the flow of molten metal by arranging one magnet, multiple pairs of tift stones formed by small coils are arranged on both sides of the tundish, and the coil current flowing through each electromagnetic coil is independently controlled. This method is characterized by controlling the flow of molten metal by changing the magnetic field distribution in response to changes in the flow of molten metal in a tundish.

Effect> The flow of molten metal in the tundish is braked (electromagnetic braking) by applying electromagnetic force to the flow of molten metal in the tundish by applying static magnetic fields generated by electromagnets installed on both sides of the tundish.

As shown in FIGS. 1 to 3, in the present invention, the electromagnet is divided into a plurality of small electromagnets. This makes it possible to control the flow by selectively applying a strong magnetic field to areas where the flow is strong and braking the strong flow, and not applying a magnetic field and not braking the flow to areas where the flow is weak. .

In addition, for the attenuation of the magnetic field in the center between the coils, by increasing the current flowing through one coil, a mlJ% distribution as shown in Figure 4 is created, and the electromagnets installed in order in the direction of flow are The problem can be solved by setting the lever distribution to alternate.

In this way, by freely controlling the direction and strength of the flow within the tundish, it becomes possible to create a uniform flow in both the vertical and width directions that is optimal for floating inclusions.

<Example> FIG. 7 is a diagram showing an embodiment of the present invention.

Comparative Example 1 in which 1itiff braking is not applied, Comparative Example 2 in which a pair of conventional electromagnets are used, and an example in which the small size of the present invention is equipped with magnets to control the flow are arranged on the horizontal axis, and the vertical axis is The amount of inclusions in the mold inner bay Jll (low carbon aluminum killed steel) was compared to Comparative Example 2 using a conventional electromagnetic brake.
It is expressed as an index. In the example, the amount of current applied to each small coil was set from the ladle nozzle 3 side toward the direction of flow: the smallest in the upper right coil in the first stage, the largest in the lower left coil, and the largest in the left lower coil in the second stage. The lower coil was the smallest, the upper right coil was the largest, and in the third stage, the same amount of current was passed through the six coils on the left, right, top, and bottom. The power used in both Comparative Example 2 and Example is 400 kll.

Here, the casting conditions are as follows.

Tundish capacity: 30 2 strand casting Molten steel temperature: 2 t/min・Strand kundish temperature: 1560°C As is clear from Fig. 7, compared to the conventional electromagnetic brake (comparative example 2), It is clear that the 1i magnetic brake according to the present invention has a large effect of reducing the amount of inclusions.

<Effects of the Invention> According to the present invention, since the flow of molten metal can be freely controlled, inclusions in molten steel can be reduced, and clean steel with very few inclusions can be continuously cast.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of a tundish for explaining the present invention, FIG. 2 is a schematic top view of the tundish for explaining the present invention, and FIG.
4 is a graph showing an example of the magnetic flux density distribution between Y and Y in FIG. 3, FIG. 5 is a sectional view of a main part of a conventional weir installation example, and FIG. 6 is a graph of a conventional electromagnet. FIG. 7, which is a sectional view of the main part of the installation example, is a graph showing the inclusion index in the comparative example and the example. ...Tanditshu, 2...Ladle,...
・Ladle nozzle, ・・・Tandins Franks, ・・・molten metal, 6...Weir,...
Tanditshu nozzle, 8...tm stone.

Claims (1)

[Scope of Claim] A method for controlling the flow of molten metal by disposing electromagnets between a hot water supply part and a discharge part of a tundish, comprising a plurality of pairs of electromagnets formed of small coils on both sides of the tundish. A molten metal melting system characterized in that the coil current flowing through each electromagnetic coil can be independently controlled, and the magnetic field distribution is changed in response to changes in the flow of molten metal in the tundish to control the flow. Metal flow control method.