JPS62207543A - Electromagnetic stirring method for continuous casting - Google Patents

Abstract

PURPOSE:To obtain the excellent stirring effect by arranging one pair of iron cores at both end of mold as facing each other along the long side face and winding polyphase coil for two-poles rotating magnetic field generation, on this iron core, to give a rotating force to molten steel, which is not yet solidified at the central part of the both end. CONSTITUTION:At the time of impressing three-phase AC source to three-phase coils 2a, 2b, 2 of U, V, W two-poles rotating magnetic field is generated at the both end of the mold 5, and in the other side, the liner magnetic fields 6a, 6b toward reversed direction for each side are generated at the center part of the molds 5. The eddy currents are induced in the molten steel 3 at near the end parts in the mold 5, and the rotating forces as shown in the arrow marks (a)-(c) are generated to stir the molten steel 3. In this way, the casting quality is improved and the electromagnetic efficiency to the fluidity of the molten steel 3 is improved, and the compact stirring apparatus and the reduction of the power consumption are obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention particularly relates to an electromagnetic stirring method for continuous casting in continuous casting equipment in which a mold having a ratio of long side to short side in a cross section of at least 3 or more is used. Regarding.

[Prior Art] The planar configuration of a conventional moving magnetic field type electromagnetic stirrer is shown in FIG. 4. This moving magnetic field type electromagnetic stirrer includes iron cores 1a and 1b facing each other at a predetermined distance, and Two or more sets of U, V, and W wound around the iron cores 1a and 1b, respectively.
It consists of a coil 2 consisting of a three-phase winding, a solidified slab shell 4 containing molten steel 3 to be stirred, and a mold 5 surrounding this shell 4. As the three-phase alternating current cycle in the three-phase winding 2 progresses, a moving magnetic field is formed within the molten steel 3 that moves in the directions of arrows 5a and ab. This moving magnetic field induces an eddy current in the melt #A3, and a thrust is generated in the same direction as the moving direction of the magnetic field. That is, each of the above coils 2
The moving magnetic fields 5a and 5b generate a reverse thrust force on the surface of the molten steel 3, and the relative action of the two causes the molten steel 3 to be stirred.

[Problems to be Solved by the Invention] However, in the moving magnetic field type electromagnetic stirring device having the above configuration, the moving magnetic field 6a, 6b acts, but no direct thrust acts on the molten steel 3 along the corners and short sides of the mold 3. For this reason, the flow of the molten steel three-sided metal body takes a rotational motion due to the relative motion of the moving magnetic fields 6a and 6b, but uniform flow cannot be expected as a whole and the stirring efficiency is poor. That is, this causes non-uniform solidification of the molten steel 3 and deteriorates casting quality.

An object of the present invention is to provide an electromagnetic stirring method for continuous casting that prevents uneven flow of molten steel in a mold having a rectangular cross section and provides an excellent stirring effect. .

[Means and effects for solving the problem] That is, the electromagnetic stirring method for continuous casting according to the present invention has a pair of iron cores arranged oppositely along the long sides of each end of the mold, and each pair of iron cores A multiphase coil for generating a two-pole rotating magnetic field is wound around each of the molds, and a rotational thrust is applied to the unsolidified molten steel at the center of both ends of the mold.

[Example] Fig. 1 shows the configuration. First, a ring core (not shown) is divided into two parts, and a pair of cores 11a and 11b, each of which is an arc-shaped core stretched on a plane, is shown in cross section. Both ends of a rectangular mold 5 are arranged to face each other along its long side surfaces. And each pair of iron cores 11a, 11
For b, U.

(2) The three-phase windings 2a and 2b of W are wound using a ring winding method. In this way, linear moving magnetic field type coils similar to those shown in the conventional example in FIG. 3 are arranged oppositely between each divided coil along the long side surface of the mold 5, in which a pair of divided coils are arranged at each end. . Here, each of the above three-phase windings 2a.

A three-phase AC power supply is connected to 2b and 2, but the A of each phase
, T, (ampere turns) can each be adjusted arbitrarily. The arrangement of the phases of the three-phase windings 2a and 2b in the split coil is symmetrical with respect to the mold 5. In addition, in FIG. 1, the shapes of the divided iron cores 11a and 11b are rectangular for convenience, but
The important point of the present invention is to generate a two-pole rotating magnetic field between the cores 11a and 11b, and the shape of the divided core itself is not specified.

Next, the stirring action of the molten steel 3 in the electromagnetic stirring method according to this embodiment will be explained.

First, the three-phase winding 2a of U, V, and W in FIG.
When a three-phase AC power source is applied to 2b and 2 so that the current flows in the direction shown in the figure, a two-pole rotating magnetic field 12a and 12b is generated at both ends of the mold 5, as shown by the dashed line in FIG. 2(A). On the other hand, in the center of the mold, a linear magnetic field 6a moving backwards is generated.
, 5b occur. The illustrated magnetic fields 12a, 12b, 5a,
5bLt indicates the main magnetic field at the moment when the U-phase current reaches its maximum positive value. Here, the magnetic fields 5a and 5b are generated as shown in FIG. 2(A) to FIG. 2(D) as the three-phase AC 1/2 period progresses A to D as shown in FIG. Transition to.

Each state in Figure 3 is (A: LI phase current, maximum positive value)
→ (B: W phase current, maximum value of the angle) → (C: V phase current, maximum positive value) → (D: U phase current, maximum negative value) The bipolar rotating magnetic fields 12a and 12b generated at both ends of the mold 5 rotate once in one cycle of alternating current. As for the direction of rotation of the magnetic field, it is also possible to rotate it in the opposite direction to that shown in FIG. 2 by replacing any two phases of the three-phase alternating current.

That is, the rotating magnetic field 12a generated as described above,
12b induces an eddy current in the molten steel 3 in the vicinity of the inner end of the mold 5, generating rotational force as shown by arrows a to C in FIG. 1 and stirring the molten steel. In this case, the rotational direction of the molten steel 3 is the same as the rotational direction of the magnetic field accompanying the three-phase AC cycle.

Therefore, the magnetic field 6a moves linearly in the central part of the mold 5.

The molten steel 3 flowed along the long side surface by 6b is
A rotating magnetic field 12a generated near the mold end.

12b, it continues to flow along the corner (a-C) and is returned to the center of the mold 5 again. As a result, the molten steel 3 is stirred at a uniform flow rate throughout,
Casting quality can be improved. Moreover, the electromagnetic efficiency with respect to the flow of the molten steel 3 is improved, and the stirring device can be made more compact and the power consumption can be reduced.

Here, the molten steel 3 is a low melting point metal (Sn).

61 wood metal), a uniform flow velocity of about 20 m/min was obtained.

In the above embodiment, the linear moving magnetic field coil and the separated two-pole rotating magnetic field coils disposed at both ends thereof are iron cores 1a, 1b, and 11a, respectively.

Although the core is divided into three parts with the core 11b separated, the same stirring action can be obtained even if the cores are integrated.

[Effects of the Invention] As described above, according to the present invention, a pair of iron cores are disposed opposite each other along the long side surfaces of each end of the mold, and each pair of iron cores is provided with a polygon for generating a two-pole rotating magnetic field. Since the phase coil is wound to apply a rotational thrust to the unsolidified molten steel at the center of both ends of the mold, uneven flow of molten steel can be prevented, especially in the mold whose cross section is rectangular. , it is possible to provide an electromagnetic stirring method for continuous casting that allows excellent stirring effects to be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan configuration diagram showing an electromagnetic stirring device for explaining an electromagnetic stirring method for continuous casting according to an embodiment of the present invention, and FIGS. Figure 3 is a diagram showing the application state of three-phase alternating current by the above-mentioned electromagnetic stirring method for continuous casting, and Figure 4 is a diagram showing the conventional electromagnetic stirring method to explain the conventional electromagnetic stirring method. It is a diagram showing an electromagnetic stirring device. 1a, lb, 11a, 11b--iron core, 2.2a. 2b... coil, 3... molten steel, 4... solidified shell, 5... mold , 6a, 6b... linear moving magnetic field, 12
a. 12b...Two-pole rotating magnetic field. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] In an electromagnetic stirring method in continuous casting equipment in which a mold having a ratio of long side to short side in a cross section of at least 3 or more is used, a pair of iron cores are arranged oppositely along the long side surface at each of both ends of the mold, An electromagnetic stirring method for continuous casting, characterized in that a multiphase coil for generating a two-pole rotating magnetic field is wound around each pair of iron cores, and rotational thrust is applied to the unsolidified molten steel at the center of both ends of the mold.