JPS58119437A - Stirring method of molten metal - Google Patents

Abstract

PURPOSE:To provide rotating forces differing in a central part and a peripheral part to molten metal and to stir the molten metal efficiently without contacting by acting inductive rotating magnetic fields consisting of 2-pole magnetic fields and multipole magnetic fields of >=4 poles which differ mutually in rotating directions simultaneously upon the molten metal. CONSTITUTION:Two-pole rotating magnetic fields are acted upon the molten metal 10 in a ladle 12 having linings 13 consisting of refractories by means of magnetic cores 14a to apply large rotating force in an arrow A direction. On the other hand, magnetic cores 14b generate 6-pole rotating magnetic fields which rotate the peripheral parts of the molten metal 10 in an arrow B direction. The 6-pole magnetic fields are small in inter-pole spacings l, and the effects of the magnetic fields concentrate in the peripheral parts. The combined forces of the rotating forces thereof and the rotating forces by the 2-pole magnetic fields are small in the peripheral parts and are large in the central parts; therefore, the damage of the above-mentioned linings are reduced. On the other hand, the inclusion of slag is accelerated by the rotation in the central parts and vigorous turbulence is generated by the shearing forces between the rotating areas differing in directions, whereby the effect of stirring is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stirring molten metal, and is particularly suitable for use in ladle refining of hot metal or molten steel, or stirring of molten steel in a slab during continuous casting. The present invention relates to an improvement in a method for stirring molten metal in which the molten metal is rotatably stirred without contact by applying the full action of an induced rotating magnetic field to the molten metal.

When refining molten steel in a ladle, the molten steel stirring function is indispensable. The applicant has already proposed a molten steel stirring device using an induced rotating magnetic field.

This corresponds to the stator of an electric motor, and when molten steel is put inside it, it rotates and is stirred, and at the same time, dents are created on the surface. Therefore, by holding the activated slag in this recess and vigorously stirring it, the slag-metal reaction can be carried out at high speed. Moreover, since there is almost no contact between the refractory and the slag, it has the excellent feature that damage to the refractory is relatively small and deterioration of the slag properties due to the mixing of the refractory material is also small.

The present invention is a further improvement on the above-mentioned proposal, and it is possible to further reduce the damage to the refractory by reducing the flow velocity of the molten metal in front of the refractory, and also to create turbulence in the molten metal. It is an object of the present invention to provide a method for stirring molten metal that can strengthen the mixing and further promote the falling flow of molten metal on the surface to promote slag entrainment at the center.

The present invention provides a method for rotationally stirring molten metal in a non-contact manner by applying all the induced rotating magnetic fields to the molten metal. This object is achieved by applying different rotational forces to the center and periphery of the molten metal.

Further, the two or more kinds of induced rotating magnetic fields are a bipolar magnetic field having mutually different rotational directions and a multipolar magnetic field having four or more poles.

The present invention was made based on the fact that a rotating magnetic field type stirrer can rotate and stir in a groove in the center, whereas a traveling magnetic field type stirrer stirs only the surface layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of a molten metal stirring apparatus employing the molten metal stirring method according to the present invention will be described in detail below with reference to the drawings.

In this embodiment, as shown in FIGS. 1 and 2, molten metal 1
A ladle 12 made of a non-basic metal and lined with a refractory material 13, in which 0 is contained, a magnetic core 14 for generating a rotating magnetic field, disposed around the ladle 12, a bipolar power source 16 for generating a bipolar rotating magnetic field by the magnetic core 14;
Similarly, the magnetic core 14 has r) multiple poles of 4 or more, for example 6
It consists of a six-pole power supply 18 for generating a polar rotating magnetic field.

The magnetic core 14f"!, as shown in detail in FIG. They are placed at different heights so that they are not obscured.

The operation will be explained below with reference to FIG.

First, the magnetic core 14a creates a bipolar rotating magnetic field by the current supplied from the bipolar power source 16, and rotates the molten metal 10 clockwise to the center as shown by arrow k.At this time, In order to minimize the rotational force, it is advantageous for the magnetic field to have two poles.

In addition, the magnetic core 14b generates a six-pole rotating magnetic field whose rotation direction is different from the two-pole rotating magnetic field by the current supplied from the six-pole power supply 18, and as shown by arrow B (the peripheral part of the molten metal 10 In other words, in this hexapole magnetic field, since the pole spacing j is relatively small, the magnetic field lines are bent toward the adjacent poles, and therefore the action of the magnetic field is concentrated near the front surface of the poles. It is known that the action of the magnetic field near the center becomes weaker.Therefore, the counterclockwise rotational force in Fig. 2 caused by the action of the sextupole magnetic field is expressed by the broken line arrow C.
This results in a radial distribution as shown in . On the other hand, since the bipolar magnetic field is uniformly distributed, a uniform rotational force of 5 is generated as shown by the thin solid line arrow in Fig. 2. Therefore, the rotational force that is finally synthesized and applied to the molten metal 10 is as shown by the thick solid arrow E in FIG. Therefore, the center portion can be rotated clockwise at high speed, and the vicinity of the container wall can be rotated counterclockwise in a nearly stationary state. Furthermore, by rotating the vicinity of the center and the vicinity of the container wall in opposite directions, it is possible to generate a shearing force between the two regions and to generate severe turbulence in this region (5). As a result, turbulence occurs on the surface of the molten metal, causing the molten metal on the surface to flow toward the central recess. Needless to say, all of these are convenient for refining molten metal, which is the purpose of using this apparatus.

In this embodiment, the magnetic core 14a for the 2N magnetic field and the magnetic core 14b for the hexapole magnetic field are arranged at different heights, so the upper and lower parts of the ladle 12 can be rotated in opposite directions. .

In the above embodiment, the central portion rotates quickly clockwise and the peripheral portion rotates counterclockwise at a low speed, but it is also possible to keep the peripheral portion stationary.

Further, in the above embodiment, the magnetic cores 14a, 1 having a double structure
4b to generate two types of induced rotating magnetic fields in the ladle 12, but the method of generating two types of induced rotating magnetic fields is not limited to this method, for example, using the same iron core, Two-pole and six-pole magnetic field power supplies supply current to each of the double-wound windings, or
It is also possible to use the same (a'+) magnetic core to supply current from a two-frequency superimposed power source.According to the latter method, the structure of the iron core and winding is simplified. be able to.

Although the above embodiments apply the present invention to ladle refining of hot metal and molten steel, the scope of application of the present invention is not limited to this, and may also be used for stirring molten steel in slabs during continuous casting. In this case, VC has the effect of dividing the tip of the tendrite.

As explained above, according to the present invention, it is possible to further reduce the damage to the refractory by reducing the flow velocity of the molten metal in front of the refractory, and also to reduce the turbulence in the molten metal. It has excellent effects such as being able to generate a flow and intensifying the mixing, and further promoting the falling flow of molten metal on the surface and promoting the entrainment of slag at the center.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the structure of an embodiment of a molten metal stirring lid in which the method of stirring molten metal according to the present invention is adopted, and FIG. ■- in Figure 1
■It is a cross-sectional view along the line. DESCRIPTION OF SYMBOLS 10... Molten metal, 12... Ladle, 13... Refractory, 14.14a, 14b-magnetic core, 16 - 2-pole power supply, 18... 6-pole power supply. Agent Takaya Ron (and 1 other person)

Claims (2)

[Claims] (1) In a molten metal stirring method in which the molten metal is rotated and stirred without contact by applying an induced rotating magnetic field to the molten metal, the molten metal is stirred by applying two or more types of induced rotating magnetic fields simultaneously. A method for stirring molten metal, characterized in that different rotational forces are applied to the center and periphery of the molten metal. (2) The method for stirring molten metal according to claim 1, wherein the two or more types of induced rotating magnetic fields are multipolar magnetic fields including a bipolar magnetic field and a quadrupole magnetic field having mutually different rotation directions.