JPH0137229B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rotating device used in multi-strip continuous casting equipment to stir, by electromagnetic induction, molten steel in the copper walls of a mold or unsolidified molten steel in the shell of a slab drawn from the mold. This invention relates to a magnetic field type electromagnetic stirring device. (Prior art) In continuous casting equipment, when a stirring force is applied by electromagnetic induction to the molten steel inside the copper mold wall or the unsolidified molten steel inside the shell of a slab drawn from the mold, the surface properties of the slab change due to the floating of inclusions. It is well known that it has great effects on continuous casting of undeoxidized steel by raising air bubbles on the surface of the slab, and improving the internal quality of the slab by improving the equiaxed crystal structure of the slab and reducing center segregation. be. In multi-strip continuous casting, the spacing between slabs is restricted, so it is impossible to stir multiple strips at the same time and in the same position using conventional salient pole rotating magnetic field type or concentric winding rotating magnetic field type. Conventionally, a pair of linear inductors are installed above and below two strands so as to sandwich them, and magnetic fields traveling in opposite directions are generated to apply rotational force to the unsolidified molten copper inside the shell. However, sufficient power could not be obtained for stirring molten steel within the copper mold wall or for stirring molten steel in areas with small unsolidified thickness. On the other hand, as a method to eliminate these drawbacks, a device as shown in Fig. 5 is proposed in which the inductor cores are arranged in the shape of glasses, windings are applied to each side of the inductor cores to generate a rotating magnetic field, and the cast sides are passed through the holes of the glasses. It has been proposed (Tokugansho
59-189391). This method made it possible for the first time to use electromagnetic stirring with sufficient power even in multi-strip continuous casting. (Problem to be solved by the invention) However, the windings 2, 2a,
As a result of applying step 3, the winding is 7 when passing two strips of slab.
In order to obtain the required power, it is necessary to prepare a large capacity power source. Note that Japanese Patent Publication No. 58-32025 shows an electromagnetic stirrer using a concentric winding method in which a coil is wound around each side of a slab passage, but in this case, there is no casting wire between two slab passages. The ear-shaped winding section that detours around the single passage overlaps four times on the upstream side and four times on the downstream side.As a result, when installing equipment on a cast roll band with a thickness of 800 mm, the possible iron core thickness is only 100 mm. Therefore, it is virtually impossible to design a spectacle-type core. (Means and effects for solving the problems) The present invention has been made to overcome the drawbacks of the above-mentioned glasses-type electromagnetic stirrer, and its gist is that each of the at least two slab passages is In an electromagnetic stirrer for multi-filament continuous casting in which the sides are wound, the windings are applied to each side of each corresponding side of the adjacent mouth, with the sides that are adjacent to each other approximately on an extension line as one set. This is a unique electromagnetic stirring device. This makes it possible to reduce the number of windings applied to the inductor and, as a result, to reduce the power supply capacity required to obtain a given power. The details of the invention will be explained below by way of example shown in the drawings. FIG. 1 shows the basic type of the device of the present invention, in which it has two slab passages, 1 is an iron core, and 2 and 3 are windings arranged in the same manner as in the prior art. With reference to FIG. 6, the addition of current to the windings and the rotationally induced magnetic field generated thereby will be explained. First, an alternating current having a frequency f is applied to the windings 2 and 3, and an alternating current having the same frequency f and having a phase shift of about 90 degrees with respect to the windings 2 and 3 is applied to the winding 4. At a certain moment, current flows in the direction shown by the arrow in the windings 2 and 3 as shown in FIG. 6a, and as a result, an induced magnetic field is generated in the direction shown by the white arrow. In this case, no current flows through the winding 4. Next, FIG. 6b shows the state after 1/4 period (1/4f time) has elapsed from FIG. 6a. At this point, the current in the windings 2 and 3 disappears, and instead, a current flows in the direction of the arrow in the winding 4. As a result, an induced magnetic field shown by the white arrow is generated. Further, after 1/4 cycle is shown in Fig. 6c. In this way, a clockwise rotating magnetic field is generated in the slab passage on the right side facing the iron core 1, and a counterclockwise rotating magnetic field is generated in the slab passage on the left side in one direction. Rotational force is generated in the unsolidified molten steel part of the inner slab. FIG. 2 shows another example of the device according to the invention. In contrast to the above-described example shown in FIG. 1, a portion of each of the sides that are adjacent to each other substantially on an extension line by the winding 5 may be made in a different manner as described above. In this case windings 2 and 5
overlap, so if there is a restriction on the installation space, the thickness of the iron core 1 must be reduced, but it is effective when there is no restriction on the installation space. In the example shown in FIG. 2, windings 2 and 3 are connected to AC power supplies having the same phase. The other windings 4 and 5 are connected to an AC power source whose phase is approximately 90 degrees behind the AC power source for the windings 2 and 3. In the portion where the windings 4 and 5 are on the same plane and face the slab passage, they are connected so that the currents flowing through the windings 4 and 5 are in the same direction. 3 and 4 show that the present invention is applied to a case where there are three slab passages. In the case of FIG. 3, a combination of windings 4 and 5 is used, and in the case of FIG. and winding 2a
Depending on the combination. In any case, the present invention is based on the winding 4. In the example shown in FIG. 3, windings 2 and 3 are connected to AC power supplies having the same phase. The windings 4 and 5 include the winding 2,
Connect an AC power source whose phase is approximately 90 degrees behind the AC power source in step 3. The windings 4 and 5 or 4 and another 4 are connected so that the currents flowing through the windings flow in the same direction at the portions facing the slab passage on the same plane. In the example shown in FIG. 4, windings 2 and 3 are connected to AC power supplies having the same phase. The windings 2a and 4 are connected to an AC power source whose phase is delayed by approximately 90 degrees from the AC power sources for the windings 2 and 3. (Example) Table 1 shows examples of the present invention. This is a case of installation on a casting roll band with a center-to-center distance of two slab passages of 1200 mm, a possible installation interval between slab passages of 500 mm, and a possible thickness of 800 mm in the casting direction.

[Table] An example of the device of the present invention is shown in FIG. 1, a conventional device 1 is a conventional device shown in FIG. It was disclosed in Comparing the device of the present invention shown in FIG. 1 and the conventional device 1 shown in FIG. Equivalent power can be obtained with a small capacity power supply. Alternatively, when using the same 300 kVA, 3 Hz power source, the center magnetic flux density is 690 Gauss for the device of the present invention and 520 Gauss for the conventional device 1. Considering that the thrust is proportional to the square of the magnetic flux density, the device array of the present invention is similar to that of the conventional device 1. It is possible to exert twice the thrust. Also, according to measurements, the power supply voltage required to obtain a predetermined ampere turn at the same frequency for conductors on each side adjacent to each other on a substantially extended line is the same as that of the conventional 5
It was confirmed that the voltage required is approximately 1/3 lower than that of the device shown in the figure in which the winding 2a is wound around a spectacle-shaped iron core. (Effects of the Invention) As described above in detail, according to the present invention, it is possible to reduce the number of windings compared to the prior art, and the same thrust can be obtained with a small capacity power source. Also, if the power supply capacity is the same, stronger thrust can be exerted.

[Brief explanation of drawings]

1 to 4 are diagrams showing examples of windings of the electromagnetic stirring device according to the present invention, FIG. 5 is a diagram showing examples of windings of a conventional device, and FIG. 6 is a diagram showing windings of the device shown in FIG. 1. This is a diagram showing the relationship between the current flowing through the windings and the induced magnetic field. Figure 6a shows the moment when the current is flowing only through windings 2 and 3, Figure 6b shows the moment 1/4 cycle has passed, and Figure 6c shows the current and magnetic field at a point 1/4 period after that. 1... Iron core, 2, 2a, 3, 4, 5... Winding wire.

Claims (1)

[Claims] 1. In an electromagnetic stirring device for multi-strip continuous casting, which includes windings on each side of at least two slab passages,
Among the corresponding sides of the adjacent mouths,
An electromagnetic stirring device characterized in that a wire is wound as a set of adjacent sides that are substantially on an extension line.