JPS608899B2 - Electromagnetic continuous casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for electromagnetic continuous casting of prismatic products with a rectangular cross section, such as steel slugs.

The invention particularly relates to electromagnetic mixing of molten metal within a mold. It is known that proper grading in the mold improves the quality of continuous casting products.

At the same time, a brocade method is already known in which a moving magnetic field is used to move molten metal in the same direction as the magnetic field.

Furthermore, it is known to generate a magnetic field by means of a multiphase stationary inductor placed in close proximity to the mold, in particular preferably on the mold itself.

In the case of continuous casting of products with small cross-sections, such as small steel bars, billets, ring shapes, or squares, a cylindrical inductor surrounding the mold is used to create a magnetic field around its axis.
Casting by rotating molten metal is known as kikami.

(See French Patent No. 2315344 - IRSID)
As discussed in this specification, separation techniques have been successful in continuous casting of products such as slags, such as prisms of rectangular cross section.

However, it is inherently difficult to place molten metal in a non-circular container and rotate it. This problem is not only due to the lack of vortices on the rotating surface, but also poses a safety issue, with the risk of molten metal spilling over the surface of the mold. . The molten metal is directed along a vertical axis before solidification by a moving magnetic field extending longitudinally to the barley face of the mold parallel to the mold axis.

This magnetism is generally created by a fixed electromagnetic inductor (inductor), which functions similar to the stator of a planar linear induction motor.

It has a barley face with a plurality of parallel electrical conductors fed by a polyphase power supply and oriented perpendicular to the axis of the mold. Generally, one piece is provided on the outside of the barley side of the mold, and these pieces are used without being divided. (See French Patents Nos. 2,324,395 and 2,324,397.) In current casting technology, it is not possible to reach the desired quality by vertical imitation of the slag mold, i.e. by rotating the mold with twill or copper pieces. proved difficult. Metallurgical analysis generally indicates poor internal properties, significant metal segregation along the axis, or only superficial or apparent purity. The object of the present invention is to obtain by continuous casting an elongated product of a quality that is completely comparable to that obtained by electromagnetic centrifugation when casting billets or rods.

The present invention also relates to a mold for continuous casting of a prismatic product having a rectangular cross section.

The barley face of the mold is equipped with a flat fixed electromagnetic inductor (inductor) on the outside, which has a plurality of parallel electrical conductors fed by a multiphase power supply. Arranged in a direction parallel to the axis of the casting, the inductor has a series of basic electromagnetic induction units above the barley surface, each unit having four magnetic fields extending in the opposite direction to the magnetic field formed by the adjacent unit. The size of each electromagnetic induction unit is approximately 0.5 to the size of the wheat surface of the mold.
It is characterized by being doubled. Further, the present invention is characterized in that the inductor of the mold is oriented and arranged so as to create an electromagnetic field extending in a direction perpendicular to the axis of the flowing casting.

That is, the inductor is divided into a plurality of small inductors depending on the size of the large surface of the mold. More preferably, each successive unit is operated individually and independently to form two oppositely oriented magnetic fields. The combined effect of this magnetic field on the molten metal in the mold results in a "chain" (circular series) of two mutually rotating motions in opposite directions.

Each of these rotational movements is
It occurs one after another. In order to produce this rotational movement, it is preferable to install two inductors, each of which is arranged on the outside of the large surface of the mold, and a set of electromagnetic inductions placed on opposite sides of one inductor. The direction of the magnetic field produced by the units is such that juxtaposed units operate so as to produce moving magnetic fields in opposite directions, as do the individual guiding units.

In order to perform electromagnetic mixing, in the present invention, a rectangular prism with a rectangular cross section that is continuously cast in a certain shape is divided into units.

On the other hand, small-sized basic smelted products, such as small grains, are continuously cast as several pieces in parallel. These are caused by rotational motion observed from the shape of vortices formed on the surface.
When this method is used, the internal properties are incomparably better than those made by conventional smelting techniques such as centrifugal separation, such as smelts and slabs. .

In particular, it reduces the risk of metal segregation and central porosity. Rather than the actual mechanism related to smelted products, we will consider a mechanism that causes rotational motion transmitted to the flowing molten metal in the mold due to the inertia of the mold.

In the case of the well-known distortion caused by a vertically extending magnetic field, the movement of convection within the molten metal is sensitively transmitted to the mold. The following conditions must be met for the work of the present invention. The diameter of the vortex (equal to the size of the basic electromagnetic induction unit) must be between the upper and lower limits depending on the thickness of the smelt; rotations outside these limits are not suitable.

Otherwise, even under the same conditions, there is a risk that the mold will be too long and slender, molten metal will overflow, and there will be anger. Experiments have shown that such a risk may occur with rectangular grain sizes where the unit length is greater than 2 or less than 0.5 relative to the width of the mold.

Therefore, the working conditions of the present invention are expressed by two inequalities.

Hot d ■ (1) As shown in Figure 2a, d is the horizontal dimension when looking at the basic electromagnetic induction unit from the front, that is, the length direction, and e is the height (width) of the smelted product. shall be.

nIf L is the total length of the smelted product, then L=Z di, where n is the number of electromagnetic induction units that make up the inductor, and this number is the number of vortices appearing on the surface of the smelted product. equals number.

In this case, all di are equal and n is set as follows. Back<n<reeds (2) By giving the value of the number n of basic electromagnetic induction units, the mold of the smelted product becomes difficult.

The extreme values of the above relationships are not exact, but are determined by measurements to avoid possible dangers.

Using these equations, e and L, which represent the size of the smelted product, are determined, and if the longitudinal size that determines the standard gauge of the mold is given, these values can be given as approximate values. The thickness of this mold is generally greater than the size of the smelted product. The error of these formulas does not exceed 10%. The present invention will be explained below with reference to the drawings.

The mold 1 of the present invention shown in FIG. 1 has a rectangular inner cylindrical partition 2 and two cooling water cases 3, 3' disposed opposite to each other at both ends of the partition 2.

In order to confine the metal poured into the mold to a channel with a vertical axis 5, this mold 1 is made up of four plates of copper or copper alloy, namely two slopes 6, 6' (only 6 is visible in the figure). )
and two large plates (or barley surfaces) 4, 4', which are effectively cooled by water circulation in grooves 7 provided on their outer surfaces. The cooling water cases 3 and 3' are
The metal plate 8 also has a large surface 4 that covers the sides of the groove 7,
4'. Assemble the whole by passing a connecting beam (not shown) across the cooling water cases 3, 3' without crossing the green of the outer shell 10 and into the boss 9 delimiting the groove 7. . In the normal arrangement, cooling water case 3,
3' is the internal part of the cooling water introduction part and its drainage part.
It is divided into two small rooms. Furthermore, each end of the groove 7 is connected to each other. In the specially provided spaces 11, 11',
Fixed electromagnetic inductors (windings) 12, 12' having a planar structure are provided and connected to a multi-purpose power source (not shown).

Each inductor also has a yoke consisting of laminated sheets 13, and on its large surface facing towards the inner cylindrical partition 2 parallel notches 14, each of which has an electrical conductor of copper rods. It has 15.

Details of the inductors 12 and 12' are given in the specification of French Patent No. 2 317 258 relating to continuous casting. In the present invention, the electrical conductor 15 is parallel to the axis 5 of the casting.

The electrical conductors 15 are advantageously arranged on both sides of the groove 7 with regular spacing.

This is to reduce the thickness of the metal material between the molten metal and the inductor, and also to form an electromagnetic shield against the green part of the stray magnetic field, as is well known. Similarly, the metal plate 8 that closes the groove 7 is preferably made of non-magnetic stainless steel (copper), is preferably as thin as possible, about a few millimeters thick, and has strong durability under the water pressure of the groove 7. Things are good. In the present invention, the required number of electrical conductors 15 arranged in series is preferably the same as the number of phases of the power supply or a multiple thereof, and the basic electromagnetic guiding unit is determined by this number.

This electromagnetic induction unit is connected in a suitable manner to a polyphase power supply to create a moving magnetic field. This magnetic field is applied to the electrical conductor 15
and perpendicular to the axis 5 of the casting, the distance over which the magnetic field is extended limits the size of each electromagnetic induction unit. The outside of each inductor is divided by parallel electromagnetic induction units, and each unit creates a moving magnetic field that extends perpendicular to the axis of the casting, but the magnetic fields formed by two adjacent units alternate in opposite directions. Supply current as follows.

The mass of molten metal placed between the two units is therefore subjected to the resultant force of the parallel forces of the large plates 4 and 4' and the movement parallel to the axis 5 of the casting.

The direction of this movement is reversed when the guiding unit passes through the adjacent unit, so the molten metal creates a rotational movement (vortex), and the molten metal continuously rotates in pairs on the slug in opposite directions. The rotational motion is “chain-like” (a continuous circular motion)
It leads to From a mechanical standpoint, the effectiveness and effectiveness of these movements depends on the magnitude of electromagnetic induction on the molten metal.

The strength of the current passed through the electrical conductor 15 is approximately 200
It becomes 0A or more. Therefore, the electrical conductor 15 must be sized accordingly. This current is of low frequency (generally between 2 and 15 Hz) for the same reasons discussed above for the non-magnetic metal material placed between the inductor and the molten metal. Here, an actual working example of the present invention will be explained in detail using the following figures. Note that the present invention is not limited to these. FIGS. 2 and 3 show a cross section of an inner cylindrical partition 2 made of copper that constitutes a mold 1 for continuous casting of slag containing molten metal. In the first figure, the total length of the internal cross section of the partition 2, that is, the total length L of the smelted product (lateral dimension in the figure) is 160c, and the thickness e is 20cm. Therefore, writing = 8. Inductors producing a magnetic field similar to those described above are placed opposite the mold 1 on both sides 4 and 4'. In this case, each inductor has 18 electrical conductors 15 parallel to the vertical axis 5 of the casting and kept at a constant spacing.
A cross section of this electrical conductor 15 is shown. The mutual spacing of the electrical conductors 15 for one electromagnetic induction unit is represented by the distance D and is 9 cm.

Note that the spacing between each electrical conductor 15 is not shown to scale. This is because the cross-sections of the conductors are sized so that the numerical symbols 1, 2, and 3 can be written thereon to indicate the connection between the multiphase power source and the electrical conductor 15. Note that this polyphase power supply is not shown. In the case of a three-phase power supply, each phase is indicated in the order of increasing numbers.

(Phase 1 is the first phase among the three phases.)
Illustrated by three phases 1, 2 and 3, phase shifted by 12 steps, symbols 1, 2 and 3 indicate that the corresponding electrical conductors 15 are connected to phases 1, 2 and 3 of the current, respectively, and that the three currents are This means that both flow in the same direction, that is, toward the front. Conversely, symbols 1, 2 and 3 mean that the current is flowing in the electrical conductor 15 in the opposite direction (away from the reader).

Each figure is arranged as follows to make it easier to understand.

For 3-phase power supply, from left to right in the diagram [1, 3, 2, 1, 3
, 2], and [1, 2, 1, 2] for a two-phase power supply.
The symbol above the number represents the direction of the current. If you replace the two numbers, the direction of the magnetic field will be opposite.

For example, the substitution of 2 and 3 in the above form is a new form (1, 2, 3
, 1, 2, 3), it changes in response to the magnetic field directed from right to left.

In the figure, the direction of the magnetic field is indicated by a horizontal arrow placed between the inductor and the mold 1.

Moreover, the basic electromagnetic induction unit is divided by a vertical axis, which is the cross section of the molded part, and each part has a rotational movement. In FIG. 2a, each electromagnetic induction unit, now designated by the number 25a, is bounded by adjacent units on both sides belonging to the same inductor.

Then, a magnetic field in the opposite direction to the magnetic fields on both sides is induced. In addition, the opposing guidance units 25 of the same group
'a is placed on the opposite side of the inductor and also forms a magnetic field in the opposite direction. As a result, Konit 25
'a creates a rotating magnetic field together with the corresponding in-phase 25a. This is the symbol [1, 2] of the current flowing through the unit 25a.
and the symbol [1, 2] of the current flowing through unit 25'a, create one complete rotating magnetic field [1, 2/1, 2] while maintaining the continuity of the magnetic field spread between the two units. It means that. As a result, the combined action of 25a and 25'a on the molten metal is combined with the action of an adjacent opposing pair to perform the same action as a general rotating magnetic field.

This action is similar to the electromagnetic foundation of successive small castings, and the molten metal is separated in response to the rotational movement of the units 25a and 25'a around the vertical axis 5. Moreover, this action is as illustrated by the arrow in the molten metal. The above example is general and applicable to all other diagrams.

In each figure, those corresponding to L, e and D are constants,
On the other hand, d is a variable.

For explanation purposes, d in Figure 2a is d false, and d in Figure 2b is d.
2b, and the same applies hereinafter.

According to this, the following explanation holds true.

Figure 2a shows the following items:

The power supply for the inductor is two-phase.

The order of the current symbols, i.e. [1, 2] or [2,
1] defines the electromagnetic state of the basic electromagnetic induction unit.

These are made up of two electrical conductors 15.
Each inductor has the same basic electromagnetic induction unit 9 as 25a.
(Therefore, nine vortices are created.

) d Pine 2D 18C da=0. step shall be.

This is because the operational conditional expression {1} is satisfied.

From this basic symbol ([1, 2/1, 2]), electrical conductor 1
By changing the electrical connections in 5, the number of vortices can be easily increased or decreased.

This is illustrated in the following two figures. In Figure 2b, the electrical conductors at both ends of the induction unit are common.

That is, in units adjacent to the unit 25b (or 25'b), one of the common electric conductors 15 can be omitted to easily increase the number of vortices in common with each other. The basic symbol is always [1, 2/1, 2] (or its opposite [2, 1/2, 1]), and the number of electrical conductors electrically defining one induction unit is two. Then, both the number of units and the number of vortices will double.

Since the length of the inductor is fixed, the electric conductors 15 placed at both ends of the inductor cannot be common.

This means that the guide units placed at both ends will naturally be unbalanced in the length direction. The number of each other unit is then equal to the number of corresponding vortices. The electrical conductors at both ends of each of these units are common, and the calculation of the size d2b of each induction unit results in a value of only 1'2. In this case, d2bd(2-・)Dd9C, and d2b=0.4.

Since the operation of the present invention cannot be performed in an optimal manner under these conditions, the above-mentioned relational expression does not hold exactly in the order of ○.

In Figure 2c, where the number of induction units placed between two successive units of type 25a is reduced, the added electrical conductor has the same symbol as the nearest electrical conductor.

The basic shape ([1, 2/1, 2]) is now bisected by two electrical conductors with each phase symbol in succession. This is because the number of electrical conductors defining the basic induction unit 25c (or 25'c) has doubled. Additionally, all units have a common electrical conductor at the end. When d2c is (4-1)D, 1.3&, and the inequality '1} holds true.

Also, the basic unit can be modified even if it is the same type.

That is, by using the same symbol, the electrical conductors that are affected may be systematically divided into two parts, and some of them may be made common, or these two possibilities may be combined. In this case, the relational expression {1 is always true. It can be seen that current flows in the same direction in all electrical conductors that have the same arrangement of symbols as described above.

Figures 2d and 2e show examples of different symbol arrangements in this respect.

In FIG. 2d, the basic continuation symbol of the guiding unit 25d is shown in this case as [1, 2, 1, 2] or its symmetry [2, 1, 2, 1].

Each unit 25d is completely different from its neighbors on both sides (the electrical conductors are not common), and the unit is electrically defined by four electrical conductors each having a different power source and a different direction of flowing current. This difference is expressed by the fact that the size d of the basic guiding unit 25d (or 25'd) is 4D d=1.8.

Therefore, the relational expression [1} holds true here as well.

As before, with basic units of the same symbol, the number of individual vortices can be increased or decreased by sharing the electric conductor 15 or by bisecting the phase symbol.

FIG. 2e shows an example in which the electric conductors placed at both ends of each basic induction unit 25e (or 25'e) are common.

In this case, the basic Kendo unit is the same 4
It is electrically defined by two electrical conductors 15, the electrical conductors at both ends being compatible with each other.

Therefore, d false = (4-1) D = fox d number = 1.3 & becomes.

Also here, the relational expression (1} always holds true.

Two electrical conductors fed by the same phase are connected by a bridging wire connecting their ends placed on the same side of the inductor, resulting in a different shape (Figs. 2b and 2c) from the previous figures (Figs. It is advantageous to reduce the length of the pitch of the current circle in FIGS. 2d and 2e).

In order to produce a complete shape in the induction unit, it is advantageous for the magnetic field to be long.

Conversely, for a mold and a given inductor, the maximum number of vortices is the necessary minimum of 4. The following figures show various variations of the operation of the invention in the case of a three-phase power supply.

In FIG. 3a, the basic guidance unit 35a is represented by the continuation symbol [1, 3, 2] or the corresponding unit 3.
It is represented by [2, 3, 1] of 5'a.

Therefore, the basic form is [1, 3, 2/1, 3, 2] (or
It is represented by its symmetrical form [2, 3, 1/2, 3, 1]). Each induction unit has three electrical conductors, d sleeve = 3D
=1.3&, and the number of vortices is also 6.

As mentioned above, the number of vortices can be increased by commonizing the electrical conductors at both ends of each induction unit and reducing the width of the unit.

This is shown in Figure 3b. Basic guidance unit 35b
is defined by three electrical conductors, but the units at both ends are only 1/2 active.

Therefore d3b=(3-1)D=0.9 Mr. becomes.

Here too, the relational expression tl} holds true.

Similarly, in the following figure 3c, it is also possible to bisect each symbol of two successive electrical conductor phases to reduce the number of vortices.

In this case, each induction unit 35c is defined by six electrical conductors, dpine: mother D: 2-7e.

In this case, the relational expression ○- does not hold, and the present invention cannot perform a satisfactory operation under this condition.

Figure 3d shows a change in which the phase symbol is bisected with the commonality of the electrical conductors, thus commonizing the two electrical conductors on either side of the basic induction unit.

In all cases, the basic induction unit 35d (or 35'd) is defined by four electrical conductors.

It can be seen that the electrical conductors placed at both ends of each inductor are common.

The two basic electromagnetic induction units at each end are different from the intermediate unit and increase in size to accommodate the additional electrical conductors. In other words, the size is 2.2 steps.
In this case, the relational expression m does not hold true. What should be noted in this change is that even if relational expression (1) holds true for the internal guidance unit, that relationship does not hold true for the units at both ends.

The above example illustrates the great flexibility of the present invention.

The invention features an inductor that allows the number of desired rotational movements to be freely selected, the number of connections between electrical conductors and the number of power supplies to be easily changed, and the size regulations of the induction unit to be observed. do. Although not an absolute condition, the following additional conditions are advantageous. Each phase of the power supply must be electrically balanced.

To facilitate the operation of electrical equipment, each power source may have the same number of electrical conductors. Similarly, the change in each figure, 2a, 2b, 2c, 2d or 3a and 3c, is that the two inductors are perfectly balanced.

In 3b and 3d, there is more phase (3, 3) than in the other two, so there is no equilibrium.

This imbalance is due to the polyphase power supply, and for any number of casting rows equal to the number of polyphase power supplies (3 in this case) can be applied in the device of the invention, determining the induction unit for a given The metal is processed while continuously passing through the mold using a current circuit.

[Brief explanation of drawings]

FIG. 1 is an overall view from above of a mold for continuous casting of slugs equipped with a pair of inductors according to the present invention, and FIGS. 2a, 2b, 2c, 2d, and 2e are FIG. 3 shows each example of the operation of the present invention in the case of a phase power supply.
Figures a, 3b, 3c and 3d are explanatory diagrams of the operation in the case of a three-phase power supply. 1... Mold, 2... Partition, 3,3
′... Cooling water case, 4,. 6... Board, 5...
...Vertical axis, 7...Groove, 8...Metal plate, 9...Barley surface, 10...Outer thickness, 11...
Space, 12... Electromagnetic inductor, 14...
...Parallel notches, 15...Electric conductor. F'G-'-F's-20 F illusion-20 Fshio-2c F position-2d F uniform 28 F-ya-30 FC-30 F uniform 3 ko F-3d

Claims (1)

[Claims] 1. An electromagnetic inductor (inductor) with a planar structure fixed to the outside of a large surface of the mold, the electromagnetic inductor having a plurality of parallelly arranged electrical conductors supplied with power from a multiphase power source. In a mold for electromagnetic continuous casting of metal, the extension direction of the conductor is parallel to the axis of the casting, the electromagnetic inductor is electrically divided into electromagnetic induction units arranged continuously along the large surface, and the current is The supply causes each electromagnetic induction unit to generate a rotating magnetic field in the opposite direction to that of its one or more adjacent units, and furthermore, the longitudinal dimension of each electromagnetic induction unit is set relative to the dimension of the small surface of the mold. Approximately 0.5
An electromagnetic continuous casting mold characterized in that the mold is between . 2 Each electromagnetic inductor is arranged outside the two large surfaces, and each electromagnetic induction unit of each inductor is opposite to the equally spaced units of the electromagnetic inductor on the opposite side, which together produce a rotating magnetic field. 2. The mold according to claim 1, wherein the mold generates a directional magnetic field. 3. The mold according to claim 1, wherein the electrical conductors at both ends of the electromagnetic induction unit are formed of an electrically common conductor. 4. The mold according to claim 1, wherein the electromagnetic induction unit has an electrical conductor that can be electrically divided into two.