JPS58100956A - Electromagnetic stirrer - Google Patents

Abstract

PURPOSE:To improve stirring force and electromagnetic stirring efficiency per set of magnetic poles by providing magnetic field generating means of which the magnetic poles are faced to one side surface on the long side of the section of an ingot spacially in plural positions in the drawing direction of the ingot and generating the magnetic fields in parallel with the long sides. CONSTITUTION:In an electromagnetic stirrer 5, permanent magnets 51, 52 are disposed by facing the end faces of their magnetic poles S, N to one side surface on the long sides of an ingot 10 in such a way that the magnetic fluxes pass in the ingot 10 in the direction parallel with the long sides thereof. The poles S and N are reversed with the magnet 51 and the magnet 52. The magnets 51, 52 are spaced thoroughly to the extent of not giving any magnetical influence upon each other, and roll electrodes 55, 56 contacting rollably the solidified shell are disposed above the magnet 51 and below the magnet 52 to conduct electricity in the drawing direction of the ingot. Then, electromagnetic forces in short-side directions act in opposite directions above and below upon the unsolidified molten steel, and generate convection in the drawing direction of the ingot 10 as shown by arrows of alternate long and two short dashes lines, whereby the molten steel is stirred over a wide range and the quality of the ingot 10 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic stirring device attached to a continuous casting machine.

A static magnetic field or a moving IJ magnetic field is applied to an unsolidified slab, that is, a slab with unsolidified molten steel inside, and the electric current induced or directly applied to the unsolidified part and the above-mentioned current are applied. A Lorentz force is generated by the magnetic field, which stirs the unsolidified g-steel, destroys crystals in the process of solidification by the stirring flow, and eliminates macro-segregation by equalizing the temperature of the molten steel and developing equiaxed crystals. The electromagnetic force to be added: a is attached to the continuous supplementary device %t. 'Figure 7 is an elevational view schematically showing an example of a conventional device using a static magnetic field, and Figure 8 is a schematic cross-sectional view of the part of a slab affected by a static magnetic field using the conventional device.
ii + figure, when the slab 10 below the g-type is in an unsolidified state, Ni
A pair of two permanent magnets (electromagnets may also be used>71.72) are placed so that t and 54 face each other, and electrodes 77.78 of rollers are placed above and below them to be in rolling contact with the solidified shell of the slab IO.
is arranged so that electricity is applied in the direction of drawing out the slab. Then, an electromagnetic force is generated in the slab width direction (direction parallel to the long side) as indicated by the white arrow (4) in FIG. 8, and the unsolidified molten steel is stirred.

However, in the conventional device d, the direction of the magnetic flux is not aligned in one direction, which hinders effective use of the magnetic field.

The present invention has been made in view of certain circumstances, and provides an electromagnetic stirring system that enables efficient electromagnetic stirring with increased stirring force by directing the magnetic field in a direction parallel to the long side of the cross section of the slab. The present invention will now be described in detail with reference to drawings showing embodiments of the invention.

Fig. 1 shows a continuous slab casting machine, in which molten steel is charged from a droplet 2 on a ladle talent 1 to a tundish 3, and from there, steel is poured into a mold 4 for slabs. After passing through a first stage where an electromagnetic stirrer 5 is installed, the steel is bent as it passes through a bending zone 6, passes through a bending section 7, is extracted by pinch rolls 8, and is transferred to the next stage. .

Figure WJ2 shows an enlarged portion of the electromagnetic stirring device 5. U-shaped permanent magnets (electromagnets may also be used) 51 and 52 are attached to the side surface of the long side of the slab 10 so that the magnetic flux passes through the slab 10 in a direction parallel to the long side. The upper permanent magnet 51 and the lower permanent 4H stone 5
2, the S and N poles are reversed. Both permanent magnets 51.52
are spaced far enough apart to have no magnetic influence on the active layer.

Electromagnetic rollers 55 and 56 for rolling contact with the solidified shell of the slab 10 are arranged above the permanent magnet 51 and below the permanent magnet 52 so as to be energized in the direction of drawing out the slab. The unsolidified molten steel is energized from top to bottom by a certain energizing circuit.
The electromagnetic force acts in the direction of
Since the arrangement of the N and Sj dragons in 1.52 is reversed, the upper and lower rotations are reversed, and during that time, as shown by the double-dashed arrow in Fig. 3, convection is generated in the direction of drawing out the slab 1o. A wide range of areas will be stirred.

Next, the magnetic flux density contributing to the electromagnetic stirring force in the apparatus of the present invention and the conventional apparatus will be compared based on FIG. 5 of the fourth article.

First, in the device according to the present invention shown in FIG. is the magnetic field I of the north pole
If H is F, then ΦX-1 ・
...(1) 1(X RX = l(e+ -(2)
However, RX: N, S warm magnetic circuit resistance 1, : N, magnetic circuit length between S pole k: expressed as magnetic resistance per unit length of solidified shell; The magnetic flux density #Y in the magnetic circuit rotating in the direction is Ry = k (1(+412+2 l!3)
...(4) di L, Ry: N bypassing the opposite side of the direct measurement of the permanent magnet 51, di rotation between 51 = 4)
Raku resistance 1: N, length of the magnetic circuit between the S pole and the edge of the slab 1 pi 11 side 1 moe! 3: Expressed as the length of the magnetic circuit in the thickness direction of the slab. and l,, 12. Dimension ratio of 13: 1, 2: 12:
j? If 3= 1: 0.5: n, then Ry=
kl, (3+2n)-Rx(3+2n)...-(
s). Therefore, the magnetic flux density Φx+y in the same direction (long side direction) of the slab lO is expressed as follows.

Next, in the conventional device as shown in FIG. 5, if the strength of the magnetic field of one permanent magnet 71 is F, then this
Magnetic flux i'M l'f in the width direction on the side of 1 (JIX
' is expressed as Rx=kl, (8) as in the device of the present invention, and on the other hand, 4rB in the thickness direction of the slab 10 from the magnet 71ON <i to S +i of the other magnet 72,
East density - Y' is Rr' = k (21t + 13)...
(Sup. 11=] L, RY/', opposing M, s+ are expressed as the magnetic circuit resistance between them. Then, l, :12:
The size ratio of 13 is ll: 12: 13=l: 0.
5: When n, Ry' = k (A'++n
l,) = kl, (1+n)-Rx(1+n)
...It is expressed as (6), and it becomes from this. Therefore, the composite magnetic flux density ΦXY (vector phase) of the negative piece 10 is expressed as Φxy −(lJx"+1ily").

Equation (6) and (1lffi'k n of n in Equation 1 =
The composite magnetic flux densities of the device A of the present invention and the conventional device when the angle is 0.2.0.3.0.4°0.5 are as shown in Table 1.

From Table 1 q< l i, n'r O, 3 is 111X+Y
> *) (Y), the effective + + a flux density per magnetic set is higher in this @ Ming device d than in the conventional device. That is, specifically, the thickness dimension is 370 *tx and the width dimension is 600
In the intercept that is my friend, l, = 300 minutes, l! , -15
0 fin, 13 = 370 fins, and when n = 1.23 (n meeting 0.:3), then 1'X”Y is Φxy
The effective magnetic flux density No. 1 increases by 8.3%, which is the main difference!
This means that the electromagnetic stirring force will be increased compared to the 1 device and the 4t id conventional device.

Graph V in Figure 6 shows that when the continuous casting machine is equipped with the electric 4 & 1 stirring device according to the present invention (■), when the conventional electromagnetic stirring device is attached (■), when the electromagnetic stirring device is attached Regarding (4) quality of slab products, the abscissa axis represents superheat degree (Δ'r) and the ordinate axis represents equiaxed crystal thickness (fin). As is clear from this graph, the degree of development of equiaxed crystals in the slab produced by the continuous casting machine equipped with the apparatus of the present invention was the highest, and the same quality of the slab was assured.

As described in detail above (4), the electromagnetic stirrer surface according to the present invention is used in an electromagnetic stirrer disposed in an uncondensed bar passage area of a continuous casting machine that casts slabs with a rectangular cross section. A magnetic field generating means having magnetic poles arranged on one side of the long side in order to generate a magnetic field parallel to the long side is spaced apart in the drawing direction of the slab.
Since the pieces are arranged at several locations, the stirring force per magnetic block is increased, and stirring is carried out over a wide range, resulting in the production of cast slabs. Furthermore, even if it is not possible to install permanent magnets on both sides of the slab due to the layout of the equipment, efficient AM loading can be achieved by installing permanent magnets only on one side of the slab. The present invention produces excellent young fruit, as shown by the fact that the yield is Of+7.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of a continuous casting machine, FIG. 2 is a perspective view schematically showing the configuration of the main parts of the device of the present invention, and FIG. Written by IJj LIri
Figures 4.5 and 4.5 are diagrams for explaining the comparison of the stirring forces of the device d of the present invention and the conventional device, Figure 6 is a graph explaining the effects of the device d of the present invention, and Figure 7 is a schematic illustration of an example of the conventional device. Elevation, No. 8
The figure is a schematic sectional view thereof. 10... Slab 51, 52... Permanent magnet 55.56
...Roller electrode patent applicant: Sumitomo Metal Industries Co., Ltd. agent, patent attorney Noboru Kono Dog special opening U58-10095G (4) 14 Opening day A58-10095G (6) Calculation 4 Fig. 8 Book ■ Diagram thin 8 K

Claims (1)

[Claims] 1. In the electromagnetic stirring device 1, which is placed in the area where the unsolidified slab passes through a continuous casting machine that casts slabs with a rectangular cross section, a magnetic stirrer on the long side is used to generate a magnetic field parallel to the long side of the slab cross section. 1. Magnetic field generating means with magnetic poles raised I on one screen. An electromagnetic stirring device characterized in that the electromagnetic stirring device is arranged at a plurality of locations spaced apart in the direction in which both pieces are pulled out.