KR100751021B1 - Apparatus for supplying molten metal to a continuous cast ingot mold and how to use it - Google Patents

Abstract

The apparatus is distinguished by the output direction with two or more outlets 7, 8 coupled to two inductors 14, 15 facing each other at each wide face 22 of the casting mold forming an air gap in the nozzle. A device comprising a locked nozzle (6) having an outlet in a plane (P), wherein the magnetic field can be moved or the strength of the magnetic field can be adjusted to correct the distribution between the outlets of the entire flow of molten metal. Means are provided.

In particular, when the method of the invention is implemented, it is always possible to add the ratio of the metal flow towards the free surface 9 to the main surface towards the bottom of the mold.

Advantageously, the present invention applies to the continuous casting of steel slabs.

Description

Equipment for supplying molten metal to a continuous casting ingot mold and method for using same}

The present invention relates to the continuous casting of metals, in particular iron. The present invention is particularly concerned with the use of a magnetic field applied to a mold for the injection of molten metal from the upper part into a continuous casting mold, in particular to alter the flow of molten metal when molten metal enters the mold.

It is known that when electromagnetic effects are carried out in a suitable manner, applying a magnetic field to a continuous casting mold can increase the productivity of the casting plant while still maintaining or improving the metallurgical quality of the obtained casting product. . In this respect, hydrodynamic turbulence due to recycling built up with increasing force in the mold is a problem when the casting rate is increased, especially for casting products of long cross-sectional area.

In the continuous casting of slabs, the molten metal is substantially in the casting plane parallel to the broad sides below the free surface covered with a locking pipe called a "submerged inlet nozzle", a liquid layer of traditionally active slag of molten metal in the mold. It is fed into the mold from a tundish located at a certain distance above it through the outlet openings.

The velocity of the flows of liquid metal leaving the outlets of the nozzle has been demonstrated to increase several m / sec as soon as the casting speed reaches about 1-1.5 m / min. The resulting recirculation flows in the mold strongly stir the metal / slag interface. These fluctuations in the free surface of the cast metal cause irregularities in the solidification of the initial shell of the cast product, which are known to cause problems in the final product or cause unacceptable defects (bubble formation, peeling, etc.). Cause. In addition, debris of the covered slag can be transferred into the very casting model of the casting product in the mold, thus resulting in an impairment of the cleanliness of the solidified metal.

In the face of these hydrodynamic perturbations, today's steel manufacturers have essentially two types of solutions in their processing, one that uses valid magnetohydrodynamic tools suitable for the continuous casting of metals and casting nozzles. The other things that depend on the actual geometry of the.

Electromagnetic actuators that have been developed for this purpose have a static or moving magnetic field, or after leaving the nozzle to stop or accelerate the recirculating flows of liquid metal, or to make them symmetrical with respect to each side of the inlet nozzle that locks them. It has an effect on the recycle flows of the liquid metal in the mold.

Thus, electromagnetic braking has been developed fundamentally to consist of applying a transverse magnetic field that generates a braking force (laplace force) to the moving metal as it moves through the area at a predetermined height level in the interior space of the mold. . For this purpose, a coiled protruding pole electromagnet (EP-A-0040383) having any shape of a protrusion located on each side of the nozzle between the nozzle of the mold and the narrow end faces on each wide side of the mold, or Such as a wide bar (WO 92/12814) or a horizontal bar (WO 96/26029 and WO 98/53936) that extends over the entire width of two parallel bars that are located beyond the height to lie on the sides of the nozzle outlets It is proposed to use the designed stimulus. Whatever geometry is accepted, the objective is the same: on the one hand, the equivalent pole of the opposite pole placed opposite to the other side of the mold, creating a transverse magnetic field with the effect of braking excessively strong flows towards the free surface. On the other hand, to better distribute the main flow of liquid metal flowing downwards over the entire cross-sectional area of the mold.

In order to achieve greater coordination flexibility with this type of technology, it has been proposed to use a moving magnetic field, which is no longer static, and it is known that the magnetic field has the ability to entrain liquid metals when moving (EP-A-0 151 648). , WO 83/02079, JP-B-1 534 702). Two inductors with a horizontally moving field (perpendicular to the direction of the conductors) allow the nozzle and narrower to create a moving magnetic field that holds the molten metal in the middle as soon as the molten metal enters the region of the mold's moving magnetic field. It is located on each wide side of the mold of each side of the locked inlet nozzle with outlets on the side between the end faces. Thus, the ability to locally adjust the electromagnetic action by simply adjusting the operating parameters of the inductors, for example the intensity of the first supply current, or the angular frequency, etc., and thus the speed of movement of the magnetic field. By having it, it becomes possible to accelerate (or brake depending on the direction of relative movement given the moving magnetic field) the flow of liquid metal providing the mold.

If necessary, such a moving magnetic field is produced by an inductor with several independent phase windings of the generally "polyphase linear motor stator" type (typically two-phase or three-phase type), which is opposite to the broad side of the mold. Thus, parallel to the casting plane (FR-A-2,324,395 and FR-A-2,324,397) will be associated. Each winding is connected to the other phase of the polyphase power supply in a suitable connection order that ensures that the magnetic field travels in a direction perpendicular to the conductors along the working surface of the inductor in a preferred manner.

At this time their relative movement of movable magnetic studs or moving metals, which are mechanically adjustable positions, for the purpose of inhibiting the observed phenomenon of propagation of waves on the free surface from one narrow face of the mold to another. It has already been proposed to exploit the symmetry of the flow of molten metal entering the mold in the regions on each side of the nozzle by two adjacent magnetic poles (EP-A-0,832,704 and JP-A-03275256) that are internally interrelated in the have.

Another type of solution consists in utilizing the geometry of the outlets of the nozzles, especially the outlets for the molten metal, that teeming the molten metal. The purpose is always to regulate the distribution of the flows of liquid metal entering the mold.

For example, this type of solution is reminiscent of a decorator's brush or flat spray nozzle, the "box" type of nozzles being a locking part with a generally bulbous shape, the function of which is more likely to be more similar (US-A-464,698). And JP-A-63,76753).

These nozzles have a low velocity but open very broadly towards the bottom to facilitate ejection of the casting flows from the casting plane over a wide flow area. Their main characteristic is that the liquid metal is a uniform flow approaching an ideal flow called "Plug" flow, where the velocity gradient at any two points in the cross section approaches zero and the area approaches as close as possible to the speed of the mold. Is to try to discharge the mold into a mold. These box nozzles are beginning to be widely used in the industry, in particular in continuous casting plants of thin slabs. Recirculation flows of the metal flow towards the free surface of the cast metal allow the flow of molten metal to flow upwards to provide additional uniform heat supply to the free surface known to be necessary for the casting to proceed properly. It can be very weakened to such a point that it may be possible to provide additional openings at or along the side.

This type of solution inside is also straight nozzles with two different pairs of side outlets parallel to the broad side of the mold oriented in the casting plane. The outlets, which are usually located at the bottom position on the shaft of the nozzle in the downward direction, discharge the main flow of metal from the mold. The other outlets are arranged at the top to discharge a second flow which is intended to supply heat to the free surface through the supply of a low flow rate of "fresh" molten metal having a uniform but barely into the mold and thus a high enthalpy. The relatively low manufacturing cost of this type of nozzle can be a significant economic benefit in the case of this type of wear components that are regularly replaced.

Thus, whatever structure is used for a nozzle, whether straight or box-shaped, it may only be utilized for one form of casting operation or only for a particular form of casting product, since its geometry needs to be fixed. . Thus, this type of approach, whether intentional or not, does not appear to be suitable for changing the operation inevitably peculiar to modern continuous casters, such as changes in casting speed or changes in product shape.

Electromagnetic actuators (braking, accelerators, symmetrics) are inherently easy to use and are therefore more suitable for the following variants. However, electromagnetic actuators are not utilized for any particular mode of operation. Electromagnetic actuators, once in the mold, sometimes act as accelerators and sometimes as flow brakes to regulate the flow of liquid metal. However, unlike the specific nozzles mentioned above, electromagnetic actuators have absolutely no ability to distribute the inflow of molten metal between the upper region of the mold (toward the free surface) and the bottom (the direction of extraction of the casting product). Moreover, electromagnetic actuators are relatively expensive in terms of investment cost and consumption of electrical energy, and include financially burdensome changes in the plant complex and the technology of the molds that accommodate them.

It is an object of the present invention, in particular, to provide steel producers a means for injecting molten metal into a continuous casting mold which facilitates quick and accurate adjustment of the incoming metal flow distribution between the top and bottom of the mold.

For this purpose, the object of the present invention is a mold feeding device of a plant for the continuous casting of products of rectangular cross section, such as slabs, with molten metal. It is characterized by the following configuration.

A submerged inlet nozzle lying on a casting plane parallel to the broad side of the mold and provided with outlets for molten metal that differ in outflow direction and are divided into two or more.

Located on the large side of the mold to create opposite pole magnetic poles which face each other on each side of the casting plane and transmit a transverse magnetic field covering at least one of the outlets in the gaps surrounding the nozzles; Induction unit.

Means for adjusting the relative strength of the magnetic field relative to the other outlet in the region of one outlet covered by the transverse magnetic field so that the distribution of the total flow of molten metal between all outlets of the nozzle can be modified.

According to one embodiment, the induction unit is an electromagnetic unit composed of at least one electromagnet.

According to yet another embodiment, the induction unit comprises: an inductor having a plurality of phase windings of the "moving magnetic field" type facing each other on each side of the casting plane; A combined power supply, which supplies a direct current directly to each of the windings, wherein the means for adjusting the relative strength of the magnetic field comprises means for moving the position of the magnetic pole in the gap of the electromagnetic unit.

It is understandable to use an inductor (electromagnets or inductors of the "moving magnetic field" type) only on one side of the mold, but in this case, the effective electromagnetic force is lost. In any case, according to the present invention the magnetic pole of the inductor must always carry the magnetic field in a direction perpendicular to the opposite mold wall on which the inductor is mounted. Otherwise, the desired effect is not obtained. Thus, if two inductors face each other, the opposite stimuli are opposite poles to create a moving magnetic field, that is, the magnetic field lines of the moving magnetic field pass through the outlets of the nozzle where the flow of metal is located in the gap between the two inductors. The two poles are connected by extending perpendicular to the casting plane created.

The stimulus of the inductor is confined to the area of the plane of action of the inductor whose maximum magnetic field is generated. In the case of an electromagnet, the pole is the projecting end of the wound ferromagnetic metal body which characterizes the device. In the case of a moving magnetic field type inductor with multiple phase windings, the stimulus does not have a fixed physical entity attached to the ferromagnetic body of a given yoke, but depending on the instantaneous strength of the alternating currents supplying the conductor, and the phase difference Can move in the plane of action of the inductor. Likewise, when the outlet is placed in a spatial region in the mold where the magnetic induction generated by the magnetic field is maximum, it can be said that the magnetic field "covers" the nozzle outlets.

From the foregoing, according to the present invention, by appropriately adjusting the strength of the magnetic field in the area in question (relative to the possible action exerted in the area of other outlets), the effect of the magnetic field in the area of the nozzle outlets covered by the magnetic field is reduced. It will be appreciated that it is easy to change. This action is achieved by changing (decreasing or increasing) the strength of the magnetic field without changing the position of the magnetic pole carrying the magnetic field, or by changing the position of the magnetic pole in the broad plane of the mold while maintaining the strength. The first method of operation mentioned above would be desirable if the two outlets were very far above the body of the nozzle, with respect to the size and distance of the magnetic poles used, so that the value of magnetic induction in each area was very different. On the other hand, the second method mentioned above, which is inevitably the most frequent, would be more suitable if all the outlets were covered and only the movement of the pole could provide a difference in the magnetic field, which would be necessary to obtain the results required by the present invention. Suffice.

Of course, in the case of an electromagnet, the movement of the magnetic pole can be achieved by mounting an electromagnet that can move in the frame, the frame being fixed to the casting hole, and also slidably moved on the surface of the mounting mold and stopped at a selected point. Means are provided in the frame.

In some cases the benefit is obtained by dividing the inductor into two induction parts, each of which is located side by side along the same side of the mold, and thus controls the outlets on one side of the nozzle independently of the outlets on the other side. It is also possible.

Whichever embodiment is used, it will already be clearly understood that the basic idea of the present invention consists in using a magnetic field as a kind of non-physical valve to close the path provided by one nozzle outlet to change the discharge from another outlet. will be. Because the injection rate into the nozzle is constant, i.e. hardly affected in any case by the action of the magnetic field, the action directly acting on one type of outlet regulates the distribution of the part of the overall flow between the two outlets. Will have effect. What is produced is a kind of submerged inlet nozzle, whose geometry can be changed without changing its shape.

Preferably, the main outlet (usually the downwardly directed outlet), where so-called molten metal is the largest, is covered by the magnetic field, since the change in the action of the magnetic field in the exhaust is more apparent than where the flow of metal is smaller. to be. In the description that follows, it will be clearly appreciated that the magnetic field covers the main outlet facing down.

In a preferred embodiment, it will also be appreciated that the present invention uses a transverse magnetic field that is movable vertically in the nozzle area but is produced by a fixed induction unit: each of the "molded motor stator with moving magnetic fields" type. A pair of inductors facing each other match each other so that the inductors are in opposite phases and each inductor can produce magnetic fields in which the magnetic field lines are directed in the same direction (the so-called "cross" magnetic field). It is connected to a DC power supply that can be adjusted independently. And this induction unit can generate magnetic poles with opposite poles and thus generate a transverse static magnetic field that can be located at the required point within the gap. This change in the position of the poles is obtained by simply activating the windings of the inductor by simply manipulating the parameters of the individual power supply, ie by adjusting the strength of the transmission current. Such adjustments can be made immediately, if necessary, during the actual casting, away from the foundry hole, safely, clearly, in other words for the operator, without any risk of hindering the proper execution of the casting operation. It will be recalled that this type of structure of inductors has been known for as long as there has been the use of inductors in continuous slab casting as a means of moving molten metal at the height of the mold (see, for example, the above mentioned). Patents FR-A-2,324,395 and FR-A-2,324,397)

Accordingly, the object of the present invention is also to adjust the strength of the magnetic field by either one of the methods for manipulating the preferred devices defined above, by changing the position of the poles of the induction unit or by changing the intensity of the current supplied to the induction unit. How it is constructed.

The invention may be understood and further features and advantages will be more apparent from the following description provided by way of illustrative and non-limiting examples with reference to the accompanying drawings.

1 shows in the casting plane the front of a mold for the continuous casting of steel slabs provided on top of the mold with devices for the injection of molten metal in accordance with the invention according to one embodiment with one inductor per mold face; A schematic representation of the vertical part of

FIG. 2 is a partial select view of the dotted portion of FIG. 1 illustrating the structure of a conventional type flat inductor that may be connected to a direct current power supply for purposes suitable for practicing the present invention; FIG.

FIG. 3 is a vertical cross sectional view of the vertical R-R plane of FIG. 1 illustrating the "cross magnetic field" operating mode of the present invention as seen from the side of the mold; FIG.

4 is a horizontal cross-sectional view showing the horizontal Q-Q plane of FIG. 1, illustrating the "cross-sectional magnetic field" operating mode of the present invention seen along the casting axis;

FIG. 5 is a schematic diagram illustrating an embodiment of the invention similar to FIG. 1 but having two inductors side by side per mold side.

In these figures, like elements will be denoted by like reference numerals.

The mold (1), made of copper or copper alloy and strongly cooled by the circulation of water around its outer wall, is in the form of a semi-finished iron or steel product (3), which can be thought of as a steel slab, in the downward direction. A particular flow of molten metal 2 discharged is received from the top. Leaving the mold, the slab 3 still liquid in the core 4 but in contact with the cooled inner wall of the mold and already solidified around the surface 5 passes through the lower stage of the casting plant along the casting axis S. As it progresses, the solidification is completed, especially by water sprayed directly onto the surface. The inflow of “fresh” metal into the mold takes place via the inlet nozzle 6 which is locked, with the top of the inlet nozzle not shown in the drawing, the tapped hole being formed at the bottom of the tundish located at a certain distance above it. Fixed around, the bottom of the inlet nozzle is immersed in the mold. This lower part consists of outlets 7, 8 which open under the free surface 9 of the liquid metal covered by the cover layer 10 of the cover slag. As shown, these outlets in the casting plane are of two different types:

The main outlets 7 which are inclined downwards and which discharge the main part of the steel flow entering the mold by the flow 11 in the total direction lying on the casting plane (face of the drawing) and generally towards the bottom of the mold .

-Discharging the remainder of the metal flow somewhat upwards by a flow 12 which tilts upwards and brings the inflow of heat necessary on the surface 9 to prevent the solidification of vortices in the meniscus (such as a solidification hook), Second outlets 8 on top.

It is recalled that the expression "casting plane" is understood to mean a vertical mid-plate surface P which passes through the casting axis S at the center of the mold and is parallel to the wide faces 22. 1 and 5 lie exactly in the casting plane P. In this case, FIG. The other plate, which is similar but parallel to the narrow sides 13 of the mold, is called the second casting plane. 3 is in the second casting plane.

Of course, the law of "mass" flow preservation is that the flow of metal exiting the bottom of the mold is the same as the flow of metal entering the mold through the nozzle 6 in a completely liquid phase. Since the discharge velocity V is a measure of casting, this is the velocity that determines the inflow flow rate for a given cross-sectional area of the product 3 and thus the discharge flow rate of the liquid metal from the nozzle outlets. As already stated, if the casting plant is a high production plant (critical discharge velocity V of about 1.5 m / min), the mold is due to the difference between the extraction rate and the metal discharge flow rate by the nozzle outlets which is one hundred times faster. The recirculation flow, which is inevitably set within, quickly becomes intense. The intense and rough recycle loops added by the deflection of the metal flows out of the narrow faces 13 of the mold thus greatly disturb the free face 9. These disturbances are harmful and need to be reduced or eliminated. However, this reduction must not impair the heat entry into the free surface 9 carried out by the second flows 12. Since operating a continuous casting hole situation is above all a "transient" type, especially because of the variety of casting speeds, the need for a fixed and calm free surface and the free surface heated by the "fresh" molten metal coming from the nozzle The desired balance between the need and the need for this has thus been raised almost constantly.

This is why, according to the invention, in each wide face 22 of the mold, an induction unit consisting of a pair of electromagnetic inductors 14, 15 is located opposite the distal end of the nozzle. These two inductors are paired to produce opposite magnetic poles of opposite poles, respectively, to form a transverse magnetic field perpendicular to the wide faces 22. As can be seen in FIGS. 1 and 3, this transverse magnetic field is located at "M" in the bottom gap to "cover" the outlets 7 of the type placed at the bottom end of the nozzle 6 body. However, these inducers are designed so that their stimuli can be moved together in the gap. Here, the movement is vertical along the mold because the inductors 16 ... 17 'are laid horizontally. By joining the poles of the inductors together over a distance of about 10 or 15 cm, a corresponding movement of the transversal magnetic field is caused in the gap, so that local magnetic conditions in the region of the different outlets 7, 8 of the nozzle are interrelated and altered. . Eventually there is a desirable redistribution of the metal flows leaving these two outlets, where the whole flow itself is unchanged or hardly changed. Thus, in FIG. 3, M represents the initial bottom position of the magnetic field in the gap, and N represents the final upper position after the vertical movement above the distance “d” in the direction of the outlets 8 which discharge the flows of metal upwards. .

The movement of the magnetic field can be obtained by a pair of "electromagnet" type inductors, the pair of electromagnets being provided with a protruding stimulus which serves as a support for the wire conductor wound around it, and inducing the pair of electromagnets The chair is mounted to translate translationally along a frame that is coupled to the casting plant. This structure thus requires a physically inducing unit.

If general conditions permit, it would be desirable to select a magnetic field that can move within a fixed gap. Such a possibility is shown in the induction units consisting of two "moving magnetic field" type inductors with multiphase windings on each side of the wide sides 22 of the mold opposite each other and as shown schematically in FIG. 2. Provided by The inductors shown here are flat inductors of the "linear motor stator" type and have two phases (ie two phase windings). These conductors are four straight copper bars (16, 17, 16 ', 17'), placed horizontally and parallel to each other. Each winding consists of two bars connected in series in opposite directions, so that current flows in the opposite direction through the two bars. Connected rods are immediately adjacent bars such as 16 'and 17, and 17' and 16 (inductors with adjacent poles) as shown, or 16 'and 16, and 17' and 17 (with split poles). It doesn't matter whether they are fallen bars.

However, whatever structure is chosen, it is important that each phase winding is connected to each individual direct current (or rectified) power supply and connected to this power device independently of the other windings. These individual power supplies are neutrally shared for convenience, as shown by 18 and 19 of FIG. 2. The individual power supplies, together with all intermediate regulators, allow each current to flow at maximum intensity in one winding (or vice versa), for example while the other winding is inactive (zero current). Means 21a, 21b for automatically adjusting the intensity of the current discharged by the power devices 18, 19 can be integrated into the power supply unit 20 provided. Since the relative intensity of the magnetic field can be adjusted by adjusting the current intensity, the power supply unit 20 and the means for adjusting the intensity of the current 21a, 21b are means for adjusting the relative intensity of the magnetic field. Under these conditions, the flat inductor 14 or 15 can produce a static magnetic field rather than a moving magnetic field, and the stimulus of the static magnetic field, which generates the magnetic field, simply causes the induction of the inductor perpendicular to the conductor by simply altering the current strength in the two windings. Can be moved in terms of activity. If necessary, a more detailed description of this type of inductor and its moving and static magnetic field modes of operation is given. More can be found in the PCT international patent application published under the application number of WO 99/30856.

In FIG. 3, the bottom position “M” of the magnetic pole corresponds to the case where the current in the windings 16, 16 ′ is maximum when the current in the windings 17, 17 ′ is zero. In contrast, the upper position "N" in FIG. 3 corresponds to the case where the current in the windings 17 and 17 'is maximum when the current in the windings 16 and 16' is zero. The power supply 20 is equipped with a means 21 for adjusting the strength of the current, by combining the strength of the current using the means 21 for adjusting the strength of the current, thereby adjusting the position of the pole of the inductor It can lead to some level between two extreme states. That is, it can be seen that adjusting the intensity of the current flowing in the winding is a means for moving the position of the magnetic pole.

In Figure 4 it can be seen that the inductors 14, 15 are configured such that two paired flat inductors 14, 15 facing each other have opposite poles. Finally, one magnetic field is added to the magnetic field of the other at some point in the gap between the two inductors. This configuration is of the "moving magnetic field" type: a magnetic field line, as represented by arrow B, crosses the casting plane P vertically, ie perpendicularly to the direction of the flows of molten metal leaving the nozzle. The stimulus of is connected to the stimulus of another inductor.
From another angle, the same type of configuration is again shown in FIG. 3. The transverse magnetic field generated by the poles of each inductor 14, 15 can be shifted vertically by the distance "d" from the bottom position "M" to the upper position "N", at which the main outlet 7 The magnetic interference action on the flow from is maximum and at "N" the magnetic interference action is reduced at the main outlet 7 but increased at the second outlet 8.

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The invention can be practiced with many different or equivalent variations provided as a limitation given to satisfy the claimed claims without being limited to the above illustrated embodiments.

Although the nozzle must have an outlet in the casting plane of the mold so that it can be applied to the present invention, it will be appreciated that other outlets can be provided that are placed elsewhere, for example placed diagonally in the corner direction of the mold. In fact, the more perpendicular the discharge direction becomes to the magnetic field lines of the magnetic field, the more effective the invention is. This is because the effect of the resulting electromagnetic force action is directly proportional to the velocity vector of the flow and the vector product of the magnetic field when leaving the nozzle outlet.

Likewise, it is an object of the present invention to better handle the heat inflow from the actual molten metal to the free surface arriving at the mold, and thus preferably provide the nozzle with a specific outlet facing down and another outlet pointing upward. However, the nozzles may be applied to the nozzles unless the outlets of the nozzles all have the same direction. This is because the present invention is very strictly applied even if the two outlets have different, even slightly different directions, immediately, for example, only a few degrees. However, this applies if the two outlets are far enough apart or cover at least both outlets but differ from each other at the same moment so that the transversal magnetic field covers one of the outlets but not the other. It was understood that the strength of the magnetic field could be different between two points in the mold interior space for continuously casting the elongated shaped product, which is the basis of the inventive concept of the present invention, which is the inventive concept of the present invention. Will be the basis.

Thus, although the present invention provides better results in the case of the "box" type mentioned earlier, the present invention also applies to straight nozzles, where the essential point is that the locked inlet nozzles used for casting are parallel to the wide side. It must have at least two different outlets by the direction applied to the flow of molten metal leaving it, ie usually in the upward and downward directions. In other words, for example, the present invention also applies to straight nozzles having side outlets distinguished from top and bottom relative to the shaft of the nozzle.

Furthermore, it is assumed above that the strength B of the magnetic field remains constant. However, as already pointed out, the magnetic field can be varied by changing the intensity of the alternating supply current, and the magnetic field itself can be moved simultaneously or separately within the gap.

Similarly, as shown in FIG. 5, the inductor 14 (as well as the inductor 15) is two identical induction portions 14a, 14b located side by side on the same side of the mold on each side of the casting axis S. FIG. ), Furthermore the casting nozzle is centrally located. In this way, the side regions of the nozzle are covered by magnetic fields independently of one another so as to selectively act on the flow of metals 11 and 12 leaving this region. By spontaneously adjusting the induction parts 14a and 14b, the induction parts are actuated at the very moment leaving the nozzle, further optimizing the symmetry of the flow in the mold. Of course, this result is obtained as a complementary effect to the main effect of the invention of maintaining the distribution between the various nozzle outlets of the total metal discharge by vertically adjusting the magnetic poles of the respective induction parts 14a and 14b. In this respect, each inductive part is powered by its own individual power supply (not shown), which allows to vary the height of the stimulus as needed and to individually adjust the strength of the current. To make it possible.

Furthermore, instead of the "moving magnetic field" type inductors, it is possible to choose not only the already mentioned electromagnets, but also natural or industrial permanent magnets.

In addition, the expression "individual direct current power supply" described above not only adds structurally independent power devices, but also a single polyphase power having a variable frequency at which the frequency is set to zero to obtain direct current with two or three phases. It means adding a supply device. Multiphase power supplies of this type are well known. Polyphase power supplies are types that include inverters with various chopping thresholds and are generally used to operate electric motors having rotating or moving magnetic fields. Operation of a power device that provides power to the windings of the inductor 14 with one phase per winding consists of adjusting the inverter to zero frequency. Thereby, it is desirable that the current intensity of each phase is adjusted at a selected time to be obtained in the winding connected to it.

The reader should be aware that although the preferred magnetic field of the present invention is the continuous casting of the initially intended steel slab, it is generally applicable not only to the continuous casting of metal but also to the continuous casting of specifically thin slabs. .

Claims (12)

In a mold feeding device of a plant for continuously casting a product of rectangular cross section such as slab with molten metal, A submerged inlet nozzle 6 lying in the casting plane P parallel to the broad side of the mold and provided with at least two separate molten metal outlets 7, 8 with different outflow directions; Opposite poles which transmit transverse magnetic fields facing each other on each side of the casting plane P and covering at least one outlet 7 of the outlets 7, 8 in the gap surrounding the nozzle 6. An induction unit (14, 15) located on the broad side of the mold for generating stimuli; To adjust the relative strength of the magnetic field relative to the other outlet 8 in the region of the outlet 7 covered by the transverse magnetic field, so as to modify the distribution of the entire flow of molten metal between all outlets of the nozzle 6. Means (20, 21). The method of claim 1, And the induction unit is an electromagnetic unit consisting of one or more electromagnets. The method of claim 1, The induction unit comprises: an inductor (14, 15) having a plurality of phase windings of the "moving magnetic field" type facing each other at each side of the casting plane (P); A combined power supply device for supplying a direct current to each of said windings independently; The means (20, 21) for adjusting the relative strength of the magnetic field comprises means for moving the position of the magnetic pole in the gap of the electromagnetic unit. The method of claim 1, And the induction unit consists of one or more permanent magnets. The method of claim 2 or 3, Means for adjusting the relative strength of the magnetic field consists of a device for changing the strength of the current supplied to the induction unit. The method according to claim 2 or 4, Means for controlling the relative strength of the magnetic field comprises a device capable of sliding the magnet or electromagnet in a sliding manner. The method of claim 3, wherein And the means for shifting the position of the magnetic poles in the gap comprises means for independently adjusting the strength of the direct current supplied separately to the phase windings of the inductor (14, 15). The method according to any one of claims 1 to 4, Said induction unit is characterized in that on each side of the casting plane (P) it consists of two similar induction parts (14a, 14b) which are placed next to each side of the casting axis. The method according to any one of claims 1 to 4, The submerged inlet nozzle is characterized in that the nozzle is provided in the casting plane (P) with a lower main outlet (7) facing the bottom of the mold and an upper second outlet (8) facing upwards. The method of claim 9, The main outlet at the bottom forms one and the same outlet. A method of operating the apparatus of claim 1 to supply a mold of a plant for continuously casting a rectangular cross-section product into molten metal, wherein the relative strength of the magnetic field produced by the magnetic pole of the induction unit is determined by shifting the position of the magnetic pole. And controlled. A method of operating the apparatus of claim 1 to supply a mold of a plant for continuously casting rectangular cross-section products of molten metal, wherein the relative strength of the magnetic field produced by the magnetic pole of the induction unit is supplied to the induction unit. And controlled by varying the strength of the current.

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