JP2003525129A - Apparatus for supplying molten metal to continuous casting ingot mold and method of using the same - Google Patents

Abstract

(57) Abstract: The present invention includes an immersion nozzle 6 having at least two types of outlets 7 and 8 having different outflow directions associated with two inductors 14 and 15 facing each other on a main casting surface P. With respect to the device, an inductor is provided on each of the large faces of the cast ingot mold, forms a limited air gap at the location of the nozzle and forms a magnetic field covering at least one outlet 7 and Means are provided for changing the distribution of the total flow of molten metal between the outlets by adjusting the strength of the magnetic field or by moving the magnetic field. In particular, carrying out the method can always produce a part of the metal flow towards the free surface 9 relative to the main surface, which is directed towards the bottom of the ingot mold. The invention is advantageously used for continuous casting of steel slabs.

Description

Detailed Description of the Invention

The present invention relates to continuous casting of metals, especially steel. In particular, the present invention relates to supplying molten metal into the continuous casting mold from above, and more specifically, using a magnetic field applied to the mold, the molten metal is introduced into the mold at the time of introduction of the molten metal. Related to the technology to change the flow.

By applying a magnetic field to a continuous casting mold when electromagnetic action is carried out in a suitable manner, the metallurgical quality of the resulting cast product is maintained or improved, resulting in the production of a casting plant. It is known that the sex can be improved. In this regard, particularly in the case of a cast product having a long cross section such as a slab, when the casting speed is high, due to the circulating flow that occurs with the increase of the speed in the mold,
It has already been clarified that hydrodynamic turbulence is a problem.

In continuous casting of slabs, molten metal is fed into the mold from a tundish located a certain distance above the mold, through a submerged tube called an “immersion inlet nozzle”, and The outlet of the inlet nozzle is opened below the free surface of the molten steel in the mold, approximately in the plane of the main casting surface parallel to the wide surface.
In this case, the free surface is conventionally covered with a liquid layer of activated slag.

It has been demonstrated that when the casting speed reaches from about 1 m / min to 1.5 m / min, the flow velocity of the liquid metal flowing out of the nozzle outlet increases to several meters per second. The resulting circulating flow in the mold actively agitates the metal-slag interface. Such fluctuations in the free surface of the cast metal cause irregular solidification of the initial shell of the cast product, which can be problematic or unacceptable defects in the final product (
Swelling, peeling, etc.). Also, some of the covering slag may be drawn in the mold exactly in the center of the cast product, reducing the cleanliness of the resulting solidified metal.

Faced with the problems caused by these hydrodynamic turbulences, steelmakers today have basically two types of solutions available. One solution of them is to use available magnetohydrodynamic tools suitable for continuous casting of metal, another solution is based on the actual geometry of the casting nozzle.

The electromagnetic actuator developed for this purpose has an effect on the circulating flow of the liquid metal in the mold after the liquid metal flows out of the nozzle, whether with a static magnetic field or with a moving magnetic field. To accelerate or circulate the circulating flow,
Alternatively, the circulation flow is symmetrical on both sides of the immersion inlet nozzle.

Therefore, initially, the moving magnetic field (tra) is set at a predetermined height in the internal space of the mold.
An electromagnetic brake has been developed in which a moving magnetic field is applied, and a braking force (Laplace force) is generated on the moving metal by the moving magnetic field when the metal passes through this region. For this purpose, on each of the wide sides of the mold,
It has been proposed to use magnetic poles shaped like coiled salient pole electromagnets.
In this case, the coiled protruding pole electromagnet has the form of protrusions arranged on both sides of the nozzle between the nozzle and the narrow end face of the mold (EP-A-0040383).
, Or in the form of a horizontal bar extending over the entire width of the wide surface (WO92 /
12814), or in the form of two parallel bars located laterally of the nozzle outlet, spaced from each other in the height direction (WO96 / 26029 and WO9).
8/53936). The purpose is the same no matter what geometrical configuration is adopted. That is, one purpose is to use a similar magnetic pole of opposite polarity that is placed opposite the other side of the mold to create a moving magnetic field that acts to dampen the highly active flow rising to the free surface. Forming and another purpose is to better distribute the major flow of the downward flowing liquid metal over the entire cross section of the mold.

It has been proposed to use a moving magnetic field rather than a static magnetic field to increase the degree of freedom of control using this type of technique. It is known that this moving magnetic field has the ability to cause the liquid metal to follow its movement (EP-A-0151648, W
O83 / 02079, JP-B-1534702). Two inductors (vertically oriented conductors) with a horizontally moving magnetic field are provided between the nozzle and the narrow end face to widen the mold on either side of a dipping inlet nozzle with lateral outlets. Placed on each side of. This causes the moving magnetic field to disturb the molten metal as it enters these regions of the mold. It is therefore supplied to the mold by simply adjusting the operating parameters of the inductor, for example the strength of the primary supply current, the angular frequency and thus the speed of movement of the magnetic field, so that the electromagnetic action can be controlled locally. The flow of liquid metal can be accelerated (or decelerated, depending on the direction of the relative motion imparted to the moving magnetic field).

Such a moving magnetic field is generally formed by an inductor having a plurality of independent phase windings of the “polyphase linear motor stator” type (generally two-phase or three-phase type), and also the inductor Is arranged opposite the wide face of the mold, i.e. parallel to the main casting face (FR-A-2,324,395 and FR-A-2,32).
4, 397). Each winding is connected to the different phases of the polyphase power supply in the proper connection order so that the magnetic field is in the direction perpendicular to the conductors and the active surface of the inductor.
face) can be moved in a desired state.

This time, in order to reduce the observed phenomenon of waves propagating on the free surface from one narrow side of the mold to the other narrow side, the molten metal entering the mold in the regions on either side of the nozzle. The flow symmetry can be improved by the movable magnetic poles and the position of the movable magnetic poles can be mechanically adjusted, or the position of two adjacent predetermined magnetic poles whose action on the moving metal is correlated can be mechanically adjusted. It is already known that it can be adjusted (EP-A-0,832,704 and JP-A-0327525.
6).

Another type of solution consists in optimizing the geometry of the submerged part of the pouring nozzle, in particular the outlet of the molten metal. Its purpose is always the same, that is to control the distribution of the flow of liquid metal introduced into the mold.

For example, a solution of this kind includes a nozzle of the “box” type (U
S-A-464,698 and JP-A-63,76753). The submerged portion of this "box" type nozzle is generally spherical in shape, reminiscent of a decorator's brush, or a flat spray head shape, and it is assumed that the functions are similar.

[0013] These nozzles are fairly wide open towards the bottom in order to advantageously flow out in the main casting plane of the casting flow over a slow but large flow area. Therefore, its main characteristic is to try to feed the liquid metal to the mold in a uniform flow, which is close to the ideal flow called the "plug" flow. In this case, the velocity gradient of the flow between any two points in the cross section is close to zero and the cross section rapidly approaches the cross section of the mold as closely as possible. These box-shaped nozzles are beginning to be widely used in industry, especially in thin slab continuous casting plants. Therefore, the circulating flow of metal flowing towards the free surface of the cast metal is greatly dampened and, where appropriate, another opening is provided along the top or side of the box to allow the flow of molten metal to flow upwards. To the extent that more uniform heat can be applied to the free surface. It is known that this is necessary for the casting to proceed properly.

A solution of this kind also has a straight nozzle with two pairs of different lateral outlets, which are oriented in the main casting surface parallel to the wide surface of the mold. The outlet, located at the bottom position on the axis of the nozzle, is generally downward and supplies the main stream of metal withdrawn from the mold. The other outlet is located at the top and supplies heat to the free surface by supplying "fresh" molten metal, which has just been introduced into the mold, at a uniform and low flow rate, and thus a high enthalpy. Gives secondary flow. Nozzles of this type are relatively inexpensive to manufacture and are therefore of great economic benefit if worn components of this kind have to be replaced regularly.

From the above, no matter what structure (straight or box-shaped) the nozzle is used, the nozzle has a fixed geometrical configuration and therefore relates to one way of performing a casting operation. Alternatively, it may be optimized only for the particular shape of the cast product. Therefore, this type of method, whether unintentional or intentional, involves unavoidable work variations or work changes inherent in current continuous casters, such as changes in casting speed or changes in product geometry. Seems not suitable for.

Electromagnetic actuators (brakes, accelerators, harmonics) inherently have a high degree of freedom of use and are therefore suitable for following such variations. However, electromagnetic actuators are not optimized for any particular mode of operation. The electromagnetic actuator controls the flow of the liquid metal as it is introduced into the mold and then acts as an accelerator in some cases and as a flow brake in some cases. However, unlike the specific nozzles described above, the electromagnetic actuator distributes the inflow of molten metal between the top region (the region toward the free surface) and the bottom region (the region in which the cast product is pulled out) of the mold. It has no ability to do it. In addition, the electromagnetic actuator is very expensive in terms of investment cost and electric energy consumption, and the molding technology for receiving the electromagnetic actuator is accompanied by complicated and economically heavy improvements.

It is an object of the invention, in particular, to provide a continuous casting mold in which the incoming metal flow is distributed between the top region and the bottom region of the mold, which is easy and quick and precise to control. It is an object of the present invention to provide a steel manufacturing apparatus having means for supplying molten metal.

In view of this object, the object of the present invention is an apparatus for supplying molten metal to a mold of a plant for continuous casting of products having a rectangular cross section such as a slab, which is of wide mold width. A submerged inlet nozzle having an outlet for the molten metal in the plane of or substantially in the plane of the main casting parallel to the plane, said outlet being at least two distinct types of outlets with different outflow directions, the device comprising: Further, magnetic poles having different polarities facing each other on both sides of the main casting surface are formed on a wide surface, and a moving magnetic field for covering at least one type of outlet of the type is formed in a gap substantially surrounding the nozzle. In order to achieve this, it is possible to change the distribution of the total flow rate of the molten metal between the induction unit arranged over the wide surface of the mold and all the outlets of the nozzle. And means for adjusting the relative magnetic field strength of the one type of outlet region covered by the moving magnetic field with respect to the other type of outlet.

In one embodiment, the induction unit is an electromagnetic unit comprising at least one electromagnet.

In another embodiment, the induction unit has a plurality of “winding field” type windings, and each of the windings has an inductor facing each other on both sides of the main casting surface. And a means for individually adjusting the relative magnetic field strength, the means for moving the position of the magnetic poles in the gap of the electromagnetic unit.

It is also conceivable to use inductors (electromagnets or “moving field” type inductors) on only one side of the mold, but in this case the available electromagnetic power may be lost. . In any case, in the present invention the inductor poles must always provide a magnetic field oriented perpendicular to the wall of the mold in which the inductor is mounted. Otherwise, the desired effect cannot be obtained. Therefore, when the two inductors face each other, the polarities of the facing magnetic poles are different from each other in order to form the moving magnetic field. That is, the magnetic field lines extend perpendicularly to the main casting surface where the metal flow is formed through the outlet of the nozzle located in the gap between the two inductors,
Connect the two magnetic poles.

The magnetic pole of the inductor is defined as the working surface area of the inductor in which the magnetic field formed is maximum. In the case of electromagnets, the poles are the often protruding ends of the wire-wound ferromagnetic metal that characterizes the device. In the case of a moving field type inductor with multiple phase windings, the magnetic poles do not have a fixed concrete configuration mounted on a given ferromagnetic material of the yoke, but the AC phase supplied to the conductor. Depending on the instantaneous strength of the currents and their phase difference, they can move across the working surface of the inductor. Similarly, it may be said that the magnetic field “covers” the nozzle outlet when the nozzle outlet is located in the spatial region within the mold where the magnetic induction formed by the magnetic field is maximized.

From the above description, according to the present invention, by appropriately adjusting the magnetic field strength in the area of the nozzle outlet (to the effect of the magnetic field that can reach other outlet areas), the nozzle outlet covered by the magnetic field It can be seen that the action of the magnetic field can be easily changed within the region. This action can be achieved by changing (increasing or decreasing) the strength of the magnetic field without changing the position of the magnetic pole that applies the magnetic field, or by changing the position of the magnetic pole on the wide surface of the mold while maintaining the strength of the magnetic field. It is achieved by changing.
Regarding the size and distance of the magnetic poles used, the two types of outlets are widely separated in the nozzle body and the values of the magnetic induction in their respective regions are significantly different, while for example across the nozzle outlet covered by the magnetic field. When the strength of the magnetic field is maximum, the former mode of action described above is preferable. On the other hand, this is probably the most common case, where all the outlets are covered and a magnetic field difference is obtained between the outlets only by moving the magnetic poles, which in a clear way is sufficient to achieve the desired result according to the invention. If it is possible, the latter mode of action mentioned above is very suitable.

Of course, in the case of an electromagnet, the movement of the magnetic poles is a frame fixed to the caster, and the caster can be moved over the surface of the mold on which the caster is mounted, and the caster is stopped at a predetermined place. It is obtained by movably mounting an electromagnet on a frame provided with means capable of causing the electromagnet.

Also, in some cases, it may be beneficial to split the inductor into two inductor portions. In this case, the inductor parts are arranged side by side along the same face of the mold, so that each inductor part controls the outlet on one side of the nozzle independently of the outlet on the other side of the nozzle. .

Whatever the embodiment used, a kind of non-physical valve for closing the passage formed by one type of nozzle outlet and changing the outflow from the other type of outlet. It will be appreciated, of course, that the use of a magnetic field as a is a basic idea of the invention. This effect, acting directly on one type of outlet, is due to the fact that the supply to the nozzle is constant or, in any case, is almost unaffected by the action of the magnetic field. This has the effect of changing the distribution of the total flow rate between the two. What is manufactured is a type of immersion inlet nozzle whose geometry can be changed without changing its shape.

[0027] Preferably, the main outlet, ie the outlet with the highest outflow of molten metal (generally the downwardly directed outlet), is covered by the magnetic field. This is because the change in the effect of this magnetic field on the outflow at the main outlet is significantly larger than that at the outlet with less metal flow. In the following description, for the sake of clarity it is assumed that the magnetic field covers the downwardly directed main outlet.

In a preferred embodiment of the invention, a moving magnetic field is used which is vertically movable in the nozzle area and which is formed by a given guiding unit. In this case, the induction unit is a pair of inductors facing each other, and each inductor is of the "linear motor stator with moving magnetic field" type in which the phases of the inductors are opposite and the magnetic field lines are the same. A directional magnetic field can be formed (an inherent condition for obtaining a so-called "moving magnetic field"), the phase windings of which are connected to each DC power supply which can be adjusted independently of each other. As is known, such inductive units are capable of forming magnetic poles of opposite polarity and thus a moving static magnetic field that can be located at a desired point in the gap. Such a change in the position of the magnetic poles can be achieved by selectively adjusting the operating parameters of each power supply, that is, by actually adjusting the strength of the current supplied by the power supply, and selectively adjusting the windings of the inductor. It is obtained by exciting. These adjustments
If necessary, in actual casting, quickly, at a distance from the casting equipment, in a totally safe and transparent manner for the operator, i.e. without risk and precisely without interfering with the proper execution of the casting operation, Can be done. Recall that this type of inductor construction has long been known, in practice, as used in continuous casting of slabs as a means of moving molten metal across the height of the mold ( For example, the aforementioned patents FR-A-2,324,395 and FR-A.
-2,324,397).

The subject of the invention therefore also lies in the process for operating the preferred device described above. In this process, by moving the position of the magnetic pole of the induction unit, or by changing the strength of the current supplied to the induction unit,
The strength of the magnetic field is adjusted.

The present invention may be fully understood, and further aspects and advantages may be further understood, considering the description of non-limiting examples given below by way of example only, with reference to the accompanying drawings, in which: Become obvious.

[0031]

DETAILED DESCRIPTION OF THE INVENTION

  In the drawings, the same components are designated by the same reference numerals.

The mold 1 is made of copper or a copper alloy, and is actively cooled by circulating water around its outer wall, and receives a constant flow of the molten metal 2 from above. Molten metal 2 in the form of semi-finished iron or steel product 3 is recovered downward by mold 1. Here, it is assumed that the molten metal 2 is recovered as a steel slab. When the steel slab 3 is removed from the mold, the center 4 is in a liquid state, but as a result of being brought into contact with the cooled inner wall of the mold,
Its outer periphery 5 is already solidified, in particular water is sprayed directly onto its surface and is completely solidified as it travels along the casting axis S through the lower stage of the casting plant. Through the immersion inlet nozzle 6, “fresh” metal flows into the mold. An upper portion of the inlet nozzle 6 (not shown) is fixed around a tap hole formed on the upper side of the inlet nozzle and at the bottom of the tundish which is spaced apart from the inlet nozzle by a certain distance. The bottom of the inlet nozzle 6 is immersed in the mold. The lower part of the nozzle is provided with outlets 7, 8 which open below the free surface 9 of liquid metal covered by a blanket 10 of cover slag. As shown, these outlets are oriented in the main casting surface and are of two different types. That is, the main flow portion of the steel that is supplied to the mold by all the flow 11 that is inclined toward the lower side and that is in the direction of the main casting surface (the plane in the figure) and toward the approximate bottom of the mold. And the main outlet 7 for delivering the heat to the surface 9 and inclining toward the upper side, and heat required for preventing a meniscus-like parasitic solidification phenomenon (solidification hook etc.) in the surface 9 A secondary outlet 8 which delivers the remaining flow portion of the metal by means of a stream 12 directed towards

As can be seen from the above, the expression “main casting surface” means a vertical center plane P passing through the casting axis S in the center of the mold and parallel to the broad surface 22 of the mold. In this case, FIGS. 1 and 5 are exactly in the main casting plane P. The other similar plane, which is parallel to the narrow side surface 13 of the mold, is referred to as a sub casting surface. 3 and 4 are on the sub-cast surface.

Of course, according to the fluid conservation law, the flow rate of the metal drawn through the bottom of the mold is equal to the flow rate of the entirely liquid metal flowing into the mold through the nozzle 6.
Since the drawing speed V is a casting parameter, this drawing speed V determines the inflow speed and thus the outflow speed of the liquid metal from the nozzle outlet in the product 3 having a predetermined cross section. As described above, when the casting plant is a high-productivity plant (threshold value V of the drawing speed V is about 1.5 m / min), the extraction speed and the metal flow output by the nozzle outlet are 100 times or more. Due to the magnitude of the difference in velocity, the circulating flow that is necessarily formed in the mold becomes rapidly violent. Therefore, the violently disturbed circulation loop adds reflection of the metal flow on the narrow surface 13 of the mold, and disturbs the free surface 9 greatly. These disturbances are harmful and must be suppressed or eliminated altogether. However, suppressing the turbulence should not adversely affect the inflow of heat transferred to the free surface 9 by the secondary flow 12. The operating method of continuous casting is, among other things, of the "temporary" type, especially due to changes in casting speed, so the requirement for a flat and quiet free surface and the "new" molten metal flowing from the nozzle. Maintaining the desired balance with the requirement to heat the free surface by means of a nearly permanent task.

Therefore, in the present invention, the induction unit including the pair of electromagnetic inductors 14 and 15 is arranged on each of the wide surfaces 22 of the mold so as to face the end portion of the nozzle. In these two inductors, the magnetic poles facing each other have different signs, and a transverse magnetic field perpendicular to the wide surface 22 is formed. As shown in FIGS. 1 and 3, this transverse magnetic field is located at the lower end M of the gap,
It covers an outlet 7 of the type at the lower end of the body of the nozzle 6. However, these inductors are formed so that their magnetic poles can move together in the gap. The direction of movement in this case is vertical along the mold. This is the conductor 16. ． ． ． This is because 17 'is arranged horizontally. About 10c like this
With the integral movement of the magnetic poles of the inductor over a distance of m or 15 cm, the transverse magnetic field also moves in the gap, correspondingly the local magnetic state in the region of the different outlets 7, 8 of the nozzle Change. As a result, the metal flow exiting these two types of outlets is again in the desired distribution and its overall flow is unchanged or almost unchanged. For this reason, in FIG. 3, M indicates the first lower end position of the magnetic field in the gap, and N is perpendicular to the outlet 8 which directs the metal flow upwards, over a distance d. It shows the final top position after moving to.

The movement of the magnetic field comprises convex magnetic poles which serve as supports for the conductors wound around it and which are mounted for translational movement along a frame fixed to the casting plant. May be obtained by a pair of "electromagnetic" inductors. Therefore, such a configuration requires the guidance unit to physically move.

Given such general conditions, it is preferable to select a magnetic field that can move within a given gap. It is known that the possibility of such selection is provided by an inductive unit, for example as shown schematically in FIG. The induction unit of FIG. 2 consists of one or two "moving magnetic field" type inductors provided on opposite sides of the wide face 22 of the mold, facing each other and having windings of multiple phases. The inductor illustrated here is a "linear motor stator" type flat inductor and has two phases (and thus two phase windings). The conductors of these inductors are four straight copper bars 16, 17, 16 ', 17', which are parallel to one another and arranged horizontally with a spacing. Each winding comprises two bars connected in series in opposite directions to allow current to flow in these bars in opposite directions. Whether the bars to be joined are immediately adjacent to each other, eg bar 17 and bar 16 'or bar 16 and bar 17' (inductors with adjacent poles), and as shown, for example It is immaterial whether the coupled bars are offset, such as bar 16 and bar 16 'or bar 17 and bar 17' (inductors with pole distribution).

However, no matter what configuration is selected, it is important to note that each phase winding is an individual direct current (or rectified) power supply and is not the power supply for the other windings. It is only connected to unrelated power sources. These individual power supplies, shown in FIG. 2 at 18, 19 may have their common neutral for convenience. These power supplies 18, 19 are the power supply unit 2 provided with the means 21a, 21b.
It may be integrated with 0. The means 21a, 21b automatically adjust the strength of the currents supplied by the respective power sources 18, 19 to maximize the strength of the current flowing in one winding and to prevent the other winding from flowing, for example. All intermediate adjustments can be made so that they can be used (zero current) and vice versa. Under these conditions, the flat inductor 14 (15) forms a static magnetic field instead of a moving magnetic field, as in the normal case, simply by appropriately changing the intensity of the current flowing through the two windings, The magnetic pole forming this static magnetic field can move in the direction perpendicular to the conductor over the working surface of the inductor. If necessary, a detailed description of this type of inductor and its mobile and static magnetic field mode of operation can be found in PCT International Patent Application WO 99/30856 published in the name of the Applicant.

In FIG. 3, at the lower end position “M” of the magnetic pole, the current flowing through the windings 16 and 16 ′ becomes maximum, and the current flowing through the windings 17 and 17 ′ becomes zero. On the contrary, at the upper end position “N” in FIG. 3, the current flowing through the windings 17 and 17 ′ becomes maximum,
This corresponds to the current flowing through the windings 16 and 16 'becoming zero. Of course, power supply 20
By using the adjusting means 21 provided in the
The position of the magnetic poles of the inductor can also be adjusted to any height between these two maximum positions.

As clearly shown in FIG. 4, the two fitted flat inductors 14, 15 are configured such that their respective magnetic poles facing each other have opposite polarities. As a result, one magnetic field is added to the other at any point in the gap between the two inductors. This configuration is of the "moving magnetic field" type. That is, as shown by the arrow B, the magnetic field lines intersect the magnetic pole of one of the inductors by intersecting the main casting surface P perpendicularly, that is, by intersecting the flow direction of the molten metal exiting the nozzle perpendicularly. It is coupled to the magnetic pole of the other inductor.

Viewed from another angle, this same type of configuration is shown in FIG. The moving magnetic field formed by the magnetic poles of each of the inductors 14 and 15 decreases from the lower end position “M” where the magnetic braking action on the flow from the main outlet 7 is maximum, and the magnetic braking action decreases at the main outlet 7 and the auxiliary outlet 8 Distance "d" to the upper end position "N" corresponding to increasing with
It may be moved vertically only.

Of course, the present invention is not limited to the embodiments described above, but covers many variants or equivalents which meet the restrictions stated in the enclosed claims.

Needless to say, for the invention to be applicable, the nozzle must have an outlet in the main casting surface of the mold, although other nozzles, for example arranged diagonally in the direction of the corners of the mold The outlet may be provided at another place of the nozzle. In fact, the more orthogonal the outflow direction is to the magnetic field lines, the greater the effect of the present invention. This is because the effectiveness of the resulting electromagnetic effect is directly proportional to the vector product of the velocity vector of the flow exiting the nozzle exit and the magnetic field.

Similarly, the configuration of the present invention primarily seeks to allow good control of the heat transferred to the free surface from the actual molten metal reaching the mold and is therefore directed downwards. It is preferable to provide the nozzle with a specific outlet and another upwardly directed outlet. Nevertheless, the invention is generally applicable to any nozzle whose outlets do not all have the same orientation. This is 2
If the directions of the two outlets differ slightly, for example if the angles of the outlets differ by a few degrees,
This is because the present invention can be applied strictly. However, if the two outlets are still far enough apart that the transverse magnetic field can cover one outlet and not the other, or at least the transverse magnetic field covers both outlets. However, at the same time, the invention is applicable if the two outlets are sufficiently far apart so that they can be covered with clearly different induction values from each other. Therefore, it goes without saying that this causes a difference in the magnetic field strength between any two points of the internal space of the mold for the continuous casting of elongated shape, which is just the basis of the inventive idea. Can be made.

As described above, according to the present invention, good results can be obtained in the case of the above-mentioned “box” type nozzle, and the present invention can be applied to a straight nozzle. The point is that the immersion inlet nozzle used for casting has at least two types of outlets (usually upper and lower) that differ in direction, and these outlets emerge from this outlet parallel to the wide face. It is exposed to the flow of metal. In other words, the invention is also applicable to straight nozzles, for example with different lateral outlets at the upper and lower ends along the axis of the nozzle.

Also, in the above description, it was implicitly assumed that the magnetic field strength B remained constant. However, as already mentioned, it is also possible to change the strength of the magnetic field by changing the strength of the supply current and by moving the magnetic field itself in the gap, either simultaneously or separately.

Similarly, as shown in FIG. 5, the inductor 14 (of course, the inductor 15 is also the same) is
It may be divided into two identical portions 14a and 14b. These same parts 14a,
14b are arranged in parallel on the same face of the mold on both sides of the casting axis S, and as is conventional, the casting nozzle is centered on the casting axis S. In this way, the lateral areas of the nozzle are provided with a stream of pouring metal 11, 1 leaving these areas.
For 2, they are “covered” independently of each other by the magnetic fields that can act on the selection. By independently adjusting the guide portions 14a, 14b, the symmetrical flow of the molten metal in the mold can be further optimized so that the molten metal is acted upon at the very moment it emerges from the nozzle. . Of course, such a result is
By adjusting the magnetic poles vertically at 4a, 14b, the main effect of the invention of distributing the total outflow of metal at the various nozzle outlets is complemented and completed. In such a version, each induction section is supplied with current by its own power source (not shown), and the various pole heights of each induction section can be adjusted, if desired, and The strength of the current flowing through the induction part can be changed individually.

Further, as described above, a natural or artificial permanent magnet or electromagnet can be selected instead of the “moving magnetic field” type inductor.

Furthermore, the expression “individual DC power supply” as used in the text of the description does not necessarily mean an additional structurally independent individual power supply, but two or three phases and a DC A multi-phase power supply with a variable frequency set to zero frequency in order to obtain This type of polyphase power supply is well known. Such multi-phase power supplies are of the type consisting of inverters with variable chopping thresholds and are usually used to operate electric motors with rotating or moving magnetic fields. In the operation of such a power supply which supplies power to the windings of the inductor 14 using one phase per winding, the inverter is tuned to zero frequency and such adjustment is performed a predetermined number of times. Thus, the strength of the current in each phase is desired to be obtained with the windings connected to these phases.

Although the preferred field of application of the present invention is that of continuous casting of steel slabs, as described above, the present invention is also applicable to the continuous casting of general metals, and is also particularly thin slab. It is also applicable to continuous casting of.

[Brief description of drawings]

1 is a mold for continuous casting of steel slabs, viewed from the front, with a molten metal supply device according to an embodiment of the invention having one inductor per mold face provided at the upper end, FIG. The vertical section in the main casting plane is schematically shown.

FIG. 2 is a partial view of FIG. 1 showing the structure of a flat inductor of known type suitable for practicing the present invention, the flat inductor being connected to a DC power supply for implementation. .

3 is a vertical cross-sectional view taken along the vertical plane RR of FIG. 1, showing a “moving magnetic field” operation mode of the present invention when the mold is viewed from the side.

4 is a horizontal cross-sectional view taken along the horizontal plane Q-Q of FIG. 1, showing the “moving magnetic field” mode of operation of the present invention as viewed along the casting axis.

FIG. 5 is a schematic view similar to FIG. 1, showing an embodiment of the present invention with two inductors arranged in parallel on each side of the mold.

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Claims (12)

[Claims] 1. A device for supplying molten metal to a mold of a plant for continuously casting a product having a rectangular cross section such as a slab, the surface of a main casting surface (P) parallel to a wide surface of the mold. Alternatively, it comprises a submerged inlet nozzle (6) having an outlet for the molten metal which is approximately in the plane, said outlet being at least two distinct types of outlets (7, 8) with different outflow directions, the device further comprising A moving magnetic field that has magnetic poles of different polarities facing each other on both sides of the main casting surface (P) and has a wide surface, and covers at least one type of outlet (7, 8) of the type (7, 8). Between an induction unit (14, 15) arranged over a wide face of the mold to form a nozzle substantially in the gap surrounding the nozzle (6) and all outlets of the nozzle (6). Full flow of metal Means (20) for adjusting the relative magnetic field strength of the area of the one type of outlet (7) covered by the moving magnetic field to the other type of outlet (8) so that the distribution of the quantity can be changed.
, 21). 2. Device according to claim 1, characterized in that the induction unit is an electromagnetic unit comprising at least one electromagnet. 3. Inductors (14, 15) having windings of a plurality of phases of moving magnetic field type, said inductor units facing each other on both sides of said main casting surface (P),
Means (20, 21) for adjusting the relative magnetic field strength, each of which comprises a power supply coupled to each of the windings for supplying a direct current individually, for moving the position of the magnetic poles in the gap of the electromagnetic unit. A device according to claim 1, characterized in that it comprises means for 4. Device according to claim 1, characterized in that the induction unit comprises at least one permanent magnet. 5. The method according to claim 2, wherein the means for adjusting the relative magnetic field strength comprises a device for varying the strength of the current supplied to the induction unit. The device according to. 6. Device according to claim 2 or 4, characterized in that the means for adjusting the relative magnetic field strengths comprise a structure in which a magnet or an electromagnet can be slidably moved. 7. Means for moving the position of the magnetic poles in the gap includes an inductor (1
4. Device according to claim 3, characterized in that it comprises means for individually adjusting the intensity of the direct current supplied individually to the windings of phases 4, 15). 8. The guide unit is provided on both sides of the main casting surface (P) and comprises two similar parts (14a, 14b) arranged in parallel on both sides of the casting shaft. The device according to any one of claims 1 to 7. 9. A submerged inlet nozzle having a plurality of lower main outlets (7) directed to the bottom of the mold and an upper plurality of secondary outlets (8) directed upwards. 9. A device according to any one of claims 1 to 8, characterized in that it is a nozzle provided in (P). 10. Device according to claim 9, characterized in that the lower main outlets form exactly the same outlet. 11. A method for operating a device according to claim 1 to supply molten metal to a mold of a plant for continuously casting products having a rectangular cross section, the method being formed by magnetic poles of an induction unit. A method characterized in that the relative strengths of the magnetic fields are adjusted by moving the position of the magnetic poles. 12. A method for operating the apparatus according to claim 1 to supply molten metal to a mold of a plant for continuously casting products having a rectangular cross section, the method being formed by magnetic poles of an induction unit. A method, characterized in that the relative strength of the magnetic field is adjusted by varying the strength of the current supplied to the induction unit.