EP4249146A1 - Electromagnetic stirring and braking device for a mould for producing metal slabs - Google Patents

Abstract

The invention relates to an electromagnetic stirring and braking device (1) for a mold (2) for casting metal slabs, comprising a first and second coil arrangement (11) arranged on a first and second broadside plate (5, 5') of the mold (2). , 11 '), each comprising a plurality of individual coils (31,...,38,31',...,38'), which are supplied by a three-phase direct and alternating current system for generating moving in the mold (2). fed by electromagnetic traveling fields can be operated in a stirring mode or a braking and acceleration mode. For a quick change between these modes, the stirring and braking device (1) has first and second connection terminals (50, 50'), to which the electrical connection lines of the three-phase direct and alternating current system can be reversibly connected, as well as switchable terminals (60, 60 ') with connecting elements (70, 71, 72), each connecting element (70, 71, 72) being reversibly electrically connectable to two switchable terminals (60, 60').

Description

The invention relates to an electromagnetic device for influencing the flow of liquid metal melt in a continuous casting mold using electromagnetic traveling fields.

Continuous casting systems for an endless casting operation for producing a metal slab, in particular continuous casting systems that are operated in an endless casting operation, comprise as a casting mold at least one so-called continuous casting mold, hereinafter also simply referred to as a 'mold'. Such molds are generally formed - in accordance with the dimensions of the metal slabs produced with them - from two broad side plates that run essentially parallel to one another and two narrow side plates oriented perpendicular to the broad side plates, with the four mold plates forming a casting mold that is open on both sides. At the inlet end of the mold, liquid metal melt - for example liquid steel - is introduced into the mold using an immersion tube and at its outlet end a partially solidified metal strand is withdrawn from the mold. The direction of passage of the molten metal through the mold, which is also referred to as the 'pouring direction', is essentially vertically oriented, which is why the entry-side area of the mold is also referred to as the 'upper' area and the exit-side area as the 'lower' area of the die become.

In a horizontal plane, the extent of the broad side plates of a continuous casting mold is usually a multiple of the extent of the narrow side plates. A horizontal direction parallel to a broad side plate is referred to as the 'transverse direction' of the mold, while a horizontal direction parallel to a narrow side plate is referred to as the 'narrow side direction' or 'Thickness direction' of the mold is referred to. The free surface of the molten metal within the mold is called the 'casting surface' and is usually permanently covered with a layer of casting powder several centimeters thick during the casting process.

During the casting process, the molten metal is introduced into the mold using an immersion tube, the immersion tube having one or more outflow openings for the molten metal to be introduced at its lower, outlet end, and the outlet end being located below the casting level. In the area of the mold, electromagnetic braking and stirring devices are used to generate static magnetic fields as well as special spatially and temporally variable electromagnetic fields - so-called electromagnetic traveling fields - by means of which a flow of molten metal within the mold can be slowed down or a direction of the flow velocity can be changed .

On the one hand, slowing down the flow calms the casting level in the mold and reduces the number of non-metallic inclusions (such as

Inclusions of casting powder), which are introduced into the strand by high flow velocities of the molten metal. On the other hand, stirring compensates for temperature differences within the metal melt passing through the mold, so that excessive cooling of the melt near the inner walls of the mold is prevented and the so-called 'washing effect' prevents non-metallic inclusions from adhering to the strand shell.

Depending on the desired effect, different characteristics of the electromagnetic fields are required, which requires appropriate interconnections and controls of coils by means of which the fields are generated. The spatial arrangement formed by a current-carrying coil at a certain point in time magnetic field strength lines are hereinafter referred to as magnetic field strength configuration Ĥ. Furthermore, the temporal development of the field strength configuration Ĥ(t) can be determined from the respective coil geometry, any yoke of the coil, the materials surrounding the coil (such as molten metal or a mold plate) and the current with which the coil is controlled.

Fields are referred to as 'traveling electromagnetic fields' whose magnetic field strength configuration - repeats itself periodically over time, but shifts in a spatial direction. The generation of such traveling fields on molds is achieved by controlling coils arranged next to one another, which are fed with three-phase alternating currents. Although these alternating currents each have the same frequency, they are out of phase with each other. Such three-phase alternating currents can be generated, for example, by separate power sources or a frequency converter. The specific form of an electromagnetic traveling field generated by such a coil arrangement depends on the spatial arrangement of the individual coil groups, the frequency of the alternating current and the phase shift between the individual coil groups.

The so-called 'stirring mode' refers to a control of a coil arrangement arranged on both broad side plates of a mold, in which the electromagnetic traveling fields generated by the coils move along the circumferential direction of the mold in time. In a stirring mode, the magnetic field strength configurations formed on the respective broad side plates of the mold shift opposite to one another in the transverse direction of the mold. Such electromagnetic traveling fields are subsequently also referred to as 'stirring fields'.

In contrast, a coil arrangement is operated in a so-called 'braking and acceleration mode' when the magnetic field strength configurations generated on the two broadside plates move synchronously towards or away from the dip tube in time sequence along the transverse direction of the mold. The electromagnetic traveling fields generated in this process are also referred to as braking or acceleration fields, since they have a braking or accelerating effect on the flowing metal melt depending on their relative speed. For example, a flow pattern in the form of a pair of upwardly directed loops can be formed in the mold for the molten metal emerging from the immersion tube, with the near-surface flow sections of the loops directed towards the immersion tube: in this case, the acceleration mode and the braking mode are formed by traveling fields, the Movement is also directed towards or away from the dip tube. Furthermore, such a braking and acceleration mode can also counteract the formation of standing waves on the casting surface.

Furthermore, electromagnetic traveling fields are limited to a range with very low frequencies due to the so-called skin effect, which increasingly weakens the penetration of alternating electromagnetic fields into an electrically conductive medium with increasing frequency. For this reason, a static magnetic field, which is generated either by permanent magnets or by coils fed with direct current, is particularly suitable as a means for braking a flow of liquid molten metal in a mold. Such devices are also referred to as 'brake coils' or 'DC brakes'.

A wide variety of devices for braking and accelerating molten metal in molds are known from the prior art. For example, from the WO 2021/132821 A1 a device is known in which im Four coil groups are arranged in the area of the casting level, which are powered by a four-phase alternating current system and can be operated in a braking and acceleration mode, and brake coils that can also be controlled with track current are arranged in an area below the dip tube.

For example, they reveal JP 4910357 B2 and the JP 2006255759 A each a device for a continuous casting mold comprising a total of four coil groups, which can be operated in a braking and acceleration mode as well as in a stirring mode, with two coil groups each being arranged along the broad side plates of the mold and at the height of the casting level. Also is from the CN 205816758 U a device is known which comprises twelve coils in the transverse direction on each broad side plate of a mold, which are powered by a three-phase power system and can be operated in different braking, acceleration and stirring modes.

Electromagnetic traveling fields can also be directly overlaid with static fields. This is how it reveals EP 2 500 121 B1 In addition to an inner yoke with a coil arrangement that can be operated in a stirring mode to generate a traveling field, an outer yoke arranged at the same height of a mold for a static magnetic field, the coils of which are fed with direct current. Both the coils and the respective yoke for generating the traveling field or the static magnetic field are each independent of one another or structurally separated.

The invention is based on the object of further developing the prior art and of specifying a device for influencing the flow of liquid metal melt in a continuous casting mold, the device being operable in both a braking and acceleration mode as well as in a stirring mode, with a simple structural design at the same time has high efficiency and at the effort required to convert or switch between the individual modes is as low as possible.

The object is achieved according to the invention by an electromagnetic stirring and braking device with the features of claim 1 and a method with the features of claim 12.

Advantageous embodiments of the invention are the subject of the subclaims.

An electromagnetic stirring and braking device according to the invention for a mold for casting metal slabs comprises a first coil arrangement arranged on a first broad side plate of the mold and a second coil arrangement arranged on a second broad side plate of the mold. The first and second coil arrangements are arranged in a first plane, which runs normal to the casting direction of the mold, and each include a plurality of coils that can be fed by a three-phase direct and alternating current system and whose axes are normal to the first and second, respectively Broadside plate of the mold are oriented. In the following, a three-phase direct and alternating current system is understood to mean a power source which comprises three phase lines and provides either alternating currents or alternating currents superimposed with a direct current component in the phase lines for feeding the first and second coil arrangements. The frequency of the alternating currents in such a power system is adjustable, but has the same value for all phase lines. The alternating currents of the individual phase lines have a fixed phase shift from one another.

Any direct current component is required under certain production conditions and causes a static field component that exerts a braking effect on the molten metal at the level of the first and second coil arrangements. This may be necessary, for example large casting widths to limit the vertical flow speed of the metal melt in order to prevent the ingress of unmelted casting powder.

Through the aforementioned first and second coil arrangements, the electromagnetic stirring and braking device is set up to generate moving electromagnetic traveling fields and/or stationary magnetic fields in the mold.

Furthermore, the first and second coil arrangements each have a number of 3m+1 coils on both sides of a second center plane ε ₂ , which runs parallel to the casting direction of the mold and normal to the first broadside plate, where m is a natural number. For example, in the case of m equal to 1, 2 or 3, the first and second coil arrangements each have a total of 8, 14 or 20 coils. Those two coils in each group which, due to their arrangement on the mold, have the smallest or largest distance from the second center plane ε ₂ (and which are referred to below as the 'innermost' or 'outermost' coils) can each be of the same phase line are fed, whereby the current flow direction of these two coils can be the same or opposite relative to each other.

The above-mentioned coil arrangement and number of coils mean that the number of coils per coil group that are powered with the same phase line is not the same, but that the number of those coils that are controlled with the same phase line as the aforementioned innermost and outermost coils is increased by 1 is greater than the number of coils that are each fed with one of the other two phase lines. For example, if m = 2 is chosen, a total of 14 coils are arranged on each broad side plate of the mold, with seven coils being placed on both sides of the second center plane ε ₂ . Of these seven coils, three coils (namely - as described above - the innermost and outermost as well as a middle coil), for example, is fed by a first phase line of the three-phase direct and alternating current system, while two coils are fed by a second and third phase line of the three-phase direct and alternating current system. The direction of current flow through the coils is irrelevant in this consideration.

In order to advantageously achieve electromagnetic traveling fields that are as uniform as possible, it is necessary, on the one hand, that these are composed in as equal parts as possible of the contributions of those coils that are each fed with the same phase line. The term 'uniform' refers to both the spatial distribution and the force effect of the traveling fields on the molten metal in the mold.

On the other hand, the electromagnetic fields generated by the 'innermost' and 'outermost' coils are subject to a spatial scattering effect and are consequently weakened in their effect because the 'innermost' and 'outermost' coils are only directly adjacent to a single other coil. Due to the flow conditions within the mold - for example due to the effect of the immersion tube - the two 'innermost' coils on one and the same broad side of the mold are further apart from one another than an immediately adjacent coil on the same side of the second center plane ε ₂ .

The two effects described - a higher number of coils with the same phase feed as the 'innermost' and 'outermost' coils on the one hand and the weakening of the effect of these coils due to their edge location on the other hand - largely compensate for each other, so that as much as possible Uniform electromagnetic traveling fields in the aforementioned sense generally require no further design measures. At most, the width needs to be adjusted slightly the 'innermost' and/or 'outermost' coil is necessary, but no change in the number of turns or the thickness of the current-carrying conductor forming the coil. Thus, through the aforementioned choice of the number of coils and coil arrangement, uniform electromagnetic traveling fields can advantageously be achieved with at best little design effort.

Furthermore, the electromagnetic stirring and braking device comprises a first and a second magnetically conductive, one-piece outer yoke. Each coil of the first and second coil arrangements is arranged on a respective magnetically conductive coil yoke of the stirring and braking device according to the invention. The ends of each coil yoke of the first coil arrangement facing away from the mold are connected to one another via the first outer yoke and the ends of each coil yoke of the second coil arrangement facing away from the mold are connected to one another via the second outer yoke. In other words: the stirring and braking device according to the invention has its own coil yoke per coil and an outer yoke per broadside plate, although the outer yoke on one broadside plate is not connected to the outer yoke on the opposite broadside plate and therefore does not form a yoke surrounding the mold.

Furthermore, the electromagnetic stirring and braking device comprises magnetically conductive pole pieces on the side facing the mold of each coil yoke of the first and second coil arrangement, the pole pieces being arranged in a first or second support plate of the mold. The first plane can be defined, for example, by the geometric centers of the end-side, mold-facing cross-sectional area of the pole shoes of the first and second coil arrangements on the respective outer surfaces of the first and second broadside plates.

The described arrangement of the outer yoke as well as the coil yoke and pole piece per coil results in the magnetic flux generated by the first coil arrangement Electromagnetic traveling fields are advantageously guided in the direction of the casting volume of the mold and stray fields are largely avoided.

Furthermore, the electromagnetic stirring and braking device on the first and second broadside plates each comprises a switching device with terminals and connecting elements arranged on the first and second coil arrangement, each connecting element being reversibly electrically connectable to two terminals.

In this context, 'reversible' is understood to mean a positive or non-positive electrical connection (e.g. in the form of a clamp, a screw or a plug connection) between two elements, but not a material connection (e.g. by soldering or welding). It follows that the connection of a first reversibly connectable electrical connection point to a second electrical connection point can be changed (e.g. during a maintenance operation) in such a way that after the change has been made, the first connection point is no longer electrically connected to the second, but to a different connection point is ("enclose"). In contrast, a permanently installed electrical line between two electrical connection points cannot be reversibly connected and is therefore not intended to be "enclosed" in the sense described.

By changing the connection configuration of the connecting elements of the switching device, the electromagnetic stirring and braking device can be reconfigured in a particularly simple manner for a subsequent casting campaign simply by the aforementioned enclosing, so that the first and second coil arrangements for the casting campaign can either be in a stirring mode or in a braking and Acceleration mode can be operated. A casting campaign involves the casting of one or more metal slabs using the mold while maintaining certain casting parameters, but in any case maintaining them the casting mode for the first and second coil arrangements is understood.

The switching device of the electromagnetic stirring and braking device according to the invention thus advantageously enables the change between a stirring mode and a braking or acceleration mode directly on the mold itself, without it having to be removed. When manually enclosing the connecting elements of the switching device, for example, it is usually only necessary to remove the mold cover and change the connections in the manner described, which saves a lot of time.

Furthermore, especially for a change between a braking mode and an acceleration mode, the described change in the electrical connection configuration itself can also be omitted, since in this case only the electrical control of the individual coils of the first and second coil arrangement has to be changed, for example by reversing a phase shift ϕ between the individual phase lines of the three-phase direct and alternating current system.

In a preferred embodiment of the stirring and braking device according to the invention, one or more coils of the first coil arrangement and one or more coils of the second coil arrangement are combined to form a coil group. This means that the coils of a coil group are electrically connected to one another in such a way that all coils of a coil group can be powered by the same phase line of the three-phase direct and alternating current system. A coil group can include both coils of the first coil arrangement and coils of the second coil arrangement. Furthermore, the coils of a coil group can be connected to one another in series or parallel as well as in a combination of series and parallel connection. Each coil group is connected to a different phase line three-phase direct and alternating current system. The alternating currents of all phase lines each have the same frequency, which lies in a range between 0 and 5 Hz. There is a fixed phase shift ϕ between the alternating currents of the individual phase lines. At frequencies in the range mentioned, the attenuation of the magnetic field in the mold caused by eddy currents is relatively small, so that the individual modes of the stirring and braking device can be carried out with a high degree of efficiency.

According to a further preferred embodiment, a value greater than or equal to 2 is selected for m, so that both the first and the second coil arrangement of the stirring and braking device according to the invention each comprise at least two coils of each coil group. By increasing the number of coils per coil group or per coil arrangement, the electromagnetic traveling fields can be set with a correspondingly higher spatial resolution along the circumferential direction of the mold. Different coil groups can have coils of different designs - for example with different extensions along a width plate of the mold.

According to a further preferred embodiment of the invention, the pole pieces of the first and second coil arrangement are designed such that the end-side cross-sectional area of the pole pieces facing the mold is reduced to a value reduced by at least 30% compared to the cross-sectional area of the associated coil yoke, in this context one Cross-sectional area runs parallel to the respective broad side plate of the mold. One or more of the magnetic pole pieces can consist of a magnetically highly permeable material made of a cobalt-iron alloy, the highly permeable material having a mass-related cobalt content greater than or equal to 17%.

On the outside of a broadside plate of a mold there are a large number of molds at small distances from one another Support elements for mechanical support of the same, for example screws, and cooling channels for the passage of a coolant are arranged. For structural reasons, these support elements or cooling channels are also designed or continue in a support plate that directly contacts the broadside plate. In order to bring the pole pieces as close as possible to the outer surface of the broad side plate in question and thereby keep the spread of the magnetic fields generated by the stirring and braking device according to the invention as low as possible, a reduction in the cross-section of the pole pieces - in particular in the width direction of the mold - is required in order to achieve this to be able to arrange the tapered ends of the pole pieces in recesses between the mentioned interference structures of the support plate. Furthermore, since an aforementioned highly permeable material has a higher magnetic saturation flux density than pure iron, a correspondingly higher magnetic flux can be introduced into the mold using tapered pole pieces made from this material compared to pole pieces that have the same shape or taper, but made of conventional are made of iron.

In a particularly preferred embodiment of the device according to the invention, one or more pole pieces of the first and second coil arrangement are guided upwards at their ends facing the mold, so that the end cross-sectional area of such a pole piece facing the mold is offset in the vertical direction to the corresponding cross-sectional areas of the associated coil yoke. The support plate for a broadside plate of a mold is arranged below a casting platform, usually below a corresponding mold cover. For structural reasons, the space for arranging additional structures, such as a coil arrangement of the device according to the invention, is therefore limited in the vertical direction. The above-mentioned design of the upwardly guided ends of the pole pieces allows the voltage generated by the coil arrangement magnetic flux in the vertical direction within the support plate to a desired position of or near the casting level of the mold, so that a stirring or braking effect of the device according to the invention can advantageously be effected on or near the casting level.

According to a further preferred embodiment of the invention, the connecting elements and the terminals can be arranged such that it is possible to switch between a stirring mode and a braking and acceleration mode. This is advantageous because the mode in which the device according to the invention is operated essentially depends on the casting parameters and the product quality to be achieved or the specified steel type of the molten metal.

The switching device can be designed as an electrical switch, which can be controlled remotely, for example by a system automation. As a result, manual intervention is no longer necessary for switching, so that there is no need to remove the mold cover for this purpose. This configuration is particularly advantageous because it enables switching between the individual casting modes when changing between successive casting campaigns (for example when changing the casting width) without requiring manual operator intervention on the mold itself. A new casting for a changed casting mode during such a change between successive casting campaigns can also be advantageously avoided with this embodiment.

According to a further preferred embodiment of the invention, the coils of the first and second coil arrangements are designed as waveguides into which a cooling medium - for example water - can be fed or passed through. In this context, a waveguide is therefore an electrical conductor carrying a coolant and not an electrical waveguide for generating TE or TM waves to understand. For example, the inlets and outlets of the individual coils of the first coil arrangement and the second coil arrangement can each be combined by means of collecting lines to form a common feed point or outlet point on the mold, which reduces the number of coolant lines leading to the mold.

By designing the coils as waveguides in the aforementioned sense, the thermal load on the coil material, which is caused on the one hand by ohmic losses in the coil material itself and by casting heat derived from the mold, can be controlled. In particular, the temperatures of the relevant coils can be regulated to a predetermined value, for example by using the temperature and/or the coolant flow passed through the coils as manipulated variables. Since the ohmic resistance of the coil material - for example copper - is temperature-dependent, a constant strength of the magnetic field generated by the coils can be achieved - for a given current strength - through temperature control or thermal damage to the coils can be prevented.

According to a further preferred embodiment, the stirring and braking device according to the invention comprises a third and a fourth coil arrangement for generating at least two static magnetic fields in a second plane which extends normal to the casting direction of the mold, the third coil arrangement being on the first broad side plate and the fourth coil arrangement is arranged on the second broad side plate of the mold. The third and fourth coil arrangements can each also include more than two coils. Some of the coils of the third and fourth coil arrangements can - viewed in the transverse direction of the mold - be arranged in front of or behind the immersion tube of the mold.

In this context, 'a' static magnetic field is understood to mean a field that is generated by two coils directly opposite one another on the mold, the first of the two coils being a coil from the third coil arrangement and the second coil being a coil from the fourth coil arrangement . In other words, 'a' static magnetic field in this sense is formed by a pair of coils whose coil axes are arranged on different broadside plates and are directly opposite each other.

The coils of the third and fourth coil arrangements each comprise at least two coils and can be powered by a common or several separate direct current sources. Furthermore, the coils of the third and fourth coil arrangements are each arranged on their own magnetically conductive coil yoke. Each coil yoke is connected on the mold side to a magnetically conductive pole piece, which is arranged in the first or second support plate of the mold in the second level. The ends of each coil yoke of the third coil arrangement facing away from the mold are connected to one another via a third, one-piece, magnetically conductive outer yoke. Likewise, the ends of each coil yoke of the fourth coil arrangement facing away from the mold are connected to one another via a fourth, one-piece, magnetically conductive outer yoke. The outer yoke of the third coil arrangement is not mechanically connected to the outer yoke of the fourth coil configuration. This configuration advantageously allows the magnetic flux to be guided exclusively outside the mold within magnetically conductive materials without using a yoke surrounding the mold.

Depending on the position of the pole pieces of the third and fourth coil arrangement, the static magnetic field generated is directed into the interior of the mold in the second level, where it exerts a desired braking effect on the flow of the melt within the mold against the casting direction. The second level can be, for example, through the geometric centers of the support surfaces of the pole shoes of the third and fourth coil arrangements on the respective outer surfaces of the first and second broadside plates are defined. In the simplest case, the third and fourth coil arrangements each comprise two coils.

According to a preferred development, the second level is spaced 450mm to 800mm in the casting direction from the inlet end of the mold. As a result, the braking effect of the third and fourth coil arrangement develops in an area which, in the case of a substantially vertically oriented mold, is usually below the outlet openings of the dip tube of the mold.

According to a particularly preferred development, in the case of a third and fourth coil arrangement each comprising several coils, one or more coils of the third coil arrangement and one or more coils of the fourth coil arrangement can each be fed from a separate direct current source. In other words: each individual coil of the third and fourth coil arrangement can be fed from a separate direct current source, but in this embodiment several coils of the third and fourth coil arrangement can also be fed together from the same direct current source. In particular, coils of the third and fourth coil arrangements that are opposite one another on the first and second broadside plates can be connected in series with one another or can each be fed from the same direct current source. This configuration makes it possible, viewed in the casting direction, to generate magnetic fields with different strengths in the left and right parts of the mold and thus to exert an asymmetrical braking effect on the molten metal, for example to compensate for an asymmetrical flow of the molten metal within the mold.

In the method according to the invention for casting a metal slab in a mold with a mold according to the invention In a first step, the electromagnetic stirring and braking device is used to reversibly electrically connect the electrical connection lines of the three-phase direct and alternating current system to the connection terminals. Furthermore, the connecting elements are reversibly electrically connected to the switchable terminals of the switching device. The electrical connection lines and the connecting elements for the first and second coil arrangements are connected in accordance with a previously defined casting mode, in which the first and second coil arrangements are controlled in the manner described above either in a stirring mode or in a braking and acceleration mode.

In a subsequent step of the method according to the invention, a casting strand is cast onto the mold, which can be done, for example, with the aid of a cold strand through the mold. The casting strand can be the first casting strand of a casting campaign. At the same time, by feeding the first and second coil arrangements from the three-phase direct and alternating current system, electromagnetic traveling fields are generated in accordance with a predetermined stirring mode or a braking and acceleration mode for the first and second coil arrangements. In addition, one or more static magnetic fields can be generated in the second level by feeding the third and fourth coil arrangements from the one or more direct current sources.

In a further embodiment of the method according to the invention with an electromagnetic stirring and braking device according to the invention, in which the switching device is designed as an electrical switch that can be controlled remotely, electromagnetic traveling fields are generated by feeding the first and second coil arrangements from the three-phase direct and alternating current system, which move in the mold - or relative to it - and correspond to either a first or a second stirring or braking and acceleration mode. For the purpose of When changing from the first to the second stirring or braking and acceleration mode, the reversible electrical connection of the connecting elements to the switchable terminals takes place remotely, for example via control of the switching device by a system automation. The connection between the electrical connection lines of the three-phase direct and alternating current system with the connection terminals of the stirring and braking device according to the invention remains, but the direct and alternating current system is preferably de-energized during this switching process in order to avoid electrical flashovers.

• Figur 1 (FIG 1) einen Schnitt durch ein schematisches Ausführungsbeispiel der erfindungsgemäßen elektromagnetischen Rühr- und Bremseinrichtung,
• Figur 2 (FIG 2) eine Schrägansicht einer baulichen Hälfte des Ausführungsbeispiels von FIG 1,
• Figur 3 (FIG 3) eine Verschaltung des erfindungsgemäßen Ausführungsbeispiels aus FIG 1 zum Betrieb in einem Brems- und Beschleunigungsmodus,
• Figur 4 (FIG 4) eine Verschaltung des erfindungsgemäßen Ausführungsbeispiels zum Betrieb in einem Rührmodus, und
• Figur 5 (FIG 5) einen Schnitt des erfindungsgemäßen Ausführungsbeispiels in einer zweiten Ebene.

The characteristics, features and advantages of this invention described above, as well as the manner in which these are achieved, will be more clearly and clearly understood in connection with the following description of an exemplary embodiment, which will be explained in more detail in connection with the figures. Show:

• Figure 1 (FIG 1 ) a section through a schematic embodiment of the electromagnetic stirring and braking device according to the invention,
• Figure 2 (FIG 2 ) an oblique view of a structural half of the exemplary embodiment of FIG 1 ,
• Figure 3 (FIG 3 ) an interconnection of the exemplary embodiment according to the invention FIG 1 to operate in a braking and acceleration mode,
• Figure 4 (FIG 4 ) an interconnection of the exemplary embodiment according to the invention for operation in a stirring mode, and
• Figure 5 (FIG 5 ) a section of the exemplary embodiment according to the invention in a second level.

Corresponding parts are provided with the same reference numbers in the figures.

FIG 1 shows schematically a section through an embodiment of the electromagnetic stirring and braking device 1 according to the invention, which is arranged on a mold 2 for casting metal slabs. Continues to show FIG 1 a first, second and third spatial direction X, Y and Z, which together form an orthogonal tripod. The image plane of FIG 1 is aligned normal to the transverse direction of the mold 2, the transverse direction coinciding with the first spatial direction X. The casting direction of the mold is opposite to the third spatial direction Z.

The mold 2 comprises a first broadside plate 5 and a second broadside plate 5′, which are oriented essentially normal to the second spatial direction Y and are spaced apart from one another at a distance which corresponds to the thickness of a metal slab cast with the mold 2 and is also referred to as the casting thickness. The first and second broadside plates 5, 5' are mounted on a respective first and second support plate 7, 7', which ensure the stability and cooling of the first and second broadside plates 5 and 5' required during a casting process. For example, cooling channels run in or between the broad side plates 5, 5' and the respective support plates 7, 7', through which a coolant can be passed to remove the casting heat from the mold 2 (in FIG 1 not shown). Such configurations of cooling and arrangements of broadside and support plates are known to those skilled in the art and are not the subject of the invention.

Liquid molten metal 9 is introduced into the mold 2 via a dip tube 3, which protrudes into the interior of the mold 2 at the pouring-side end 2 ', with the molten metal 9 emerging essentially parallel to the broad side plates 5 and 5' through one or more outlet openings 4 flows out of the dip tube 3. The molten metal 9 is introduced during the casting process - apart from a short pouring phase - in such a way that the outlet openings 4 are completely below of the casting level 19, which is formed by the surface of the molten metal 9 introduced into the mold 2. A partially solidified casting strand (in FIG 1 not shown) is supported by support rollers 16, 16 ', 16", which, viewed in the casting direction, are behind the first and second broadside plates 5, 5' or behind (in FIG 1 Also not shown) narrow side plates of the mold 2 are arranged, mechanically supported when exiting the mold 2. Furthermore, the first and second broad side plates 5, 5 'together with the first and second support plates 7, 7' as well as the narrow side plates (not shown) are permanently moved up and down ("oscillated") in the casting direction by an oscillation device 18 during the casting process to prevent the solidifying molten metal 9 from adhering to the inner surfaces of the mold 2.

An electromagnetic stirring and braking device 1 according to the invention is arranged on the mold 2 and has a first coil arrangement 11 on the first broadside plate 5 and a second coil arrangement 11 'on the second broadside plate 5'. The first and second coil arrangements 11, 11' of the exemplary embodiment are each arranged in or along a first plane 10, which is oriented normal to the casting direction of the mold 2. Furthermore, the first and second coil arrangements 11, 11' each comprise a plurality of individual coils 31...38 and 31'...38', the axes of which are each normal to the first and second broadside plates 5, 5' of the mold 2 are oriented. Each of the coils 31...38 or 31'...38' is arranged on its own magnetically conductive coil yoke 30 or 30', the ends of each coil yoke 30 of the first coil arrangement 11 facing away from the mold being connected to one another via a first, magnetically conductive outer yoke 13 and the ends of each coil yoke 30' of the second coil arrangement 11' facing away from the mold are connected to one another via a second, magnetically conductive outer yoke 13'.

On the side facing the mold of each coil yoke 30, 30 'of the first and second coil arrangements 11, 11' are magnetically conductive pole shoes 39, 39 'arranged ( FIGS. 2 to 4 , in FIG 1 not shown), each pole piece 39, 39 'is arranged in the first or second support plate 7, 7' of the mold and mechanically contacts the outside of the first or second broadside plate 5, 5'. The magnetically non-conductive support plates 7, 7' have corresponding recesses through which the magnetically conductive pole pieces 39, 39' are passed. The first plane 10 is defined by the geometric centers of the end cross-sectional areas of the pole shoes 39, 39 'facing the mold on the respective outer surfaces of the first and second broadside plates 5, 5'.

Furthermore, there are FIG 1 a third coil arrangement 21 on the first broadside plate 5 and a fourth coil arrangement 21 'on the second broadside plate 5' of the electromagnetic stirring and braking device 1 according to the invention are shown.

The third and fourth coil arrangements 21, 21' of the exemplary embodiment shown are each arranged in or along a second plane 20, which in turn is oriented normal to the casting direction of the mold 2. The third and fourth coil arrangements 21, 21' each comprise a plurality of individual coils 41, 42 and 41', 42', the axes of which are oriented normal to the first and second broadside plates 5, 5' of the mold 2. Each of the coils 41, 42 and 41'...42' is arranged on its own magnetically conductive coil yoke 40 or 40', the ends of each coil yoke 40 of the third coil arrangement 21 facing away from the mold being connected to one another via a third, magnetically conductive outer yoke 23 and the ends of each coil yoke 40' of the fourth coil arrangement 21' facing away from the mold are connected to one another via a fourth, magnetically conductive outer yoke 23'.

Again, there are magnetically conductive pole pieces 49, 49' on the side facing the mold of each coil yoke 40, 40' of the third and fourth coil arrangements 21, 21'. arranged ( FIGS. 2 to 4 , in FIG 1 not shown), each pole piece 49, 49 'is arranged in the first or support plate 7, 7' of the mold and mechanically contacts the outside of the first or second broadside plate 5, 5'. The magnetically non-conductive support plates 7, 7' in turn have corresponding recesses through which the magnetically conductive pole pieces 49, 49' are passed. The second level 20 is defined by the geometric centers of the contact surfaces of the pole shoes 49, 49 'on the respective outer surfaces of the first and second broadside plates 5, 5'.

Figure 2 (FIG 2 ) shows an oblique view of the structural half of the electromagnetic stirring and braking device 1 according to the invention according to the exemplary embodiment of FIG 1 , which is on the first broadside plate 5 of the mold 2 (in FIG 2 not shown). The other half of the device according to the invention is designed in mirror image and in FIG 1 arranged on the second broadside plate 5 '.

FIG 2 3 accordingly shows the first and third coil arrangements 11 and 21 with the first and third outer yokes 13 and 23. In the exemplary embodiment shown, the first coil arrangement 11 comprises eight coils 31 to 38, each of which is arranged on its own coil yoke 30. From each coil yoke 30 extends along the second spatial direction Y - ie normal to the first broadside plate 5 (in FIG 2 not shown) - a magnetically conductive pole piece 39. Furthermore, in FIG 2 the geometric center points of the end cross-sectional areas of the pole shoes 39 facing the mold are indicated on the first broad side plate 5 in the form of crosses, these center points defining the position of a first plane 10 normal to the third spatial direction Z.

Furthermore, there are FIG 2 the coils 41, 42 of the third coil arrangement 21 are shown, which are arranged below the first coil arrangement 11 with respect to the third spatial direction Z. The coils 41, 42 are each on one magnetically conductive coil yoke 40 arranged and axially aligned in the direction of the second spatial direction Y. A magnetically conductive third outer yoke 23 connects each coil yoke 40 of the coils 41, 42 of the third coil arrangement 21 to one another. Likewise, a magnetically conductive fourth outer yoke 23' connects each coil yoke 40' of the coils 41', 42' of the fourth coil arrangement 21' to one another (in FIG 2 not shown).

A pole piece 49 extends from each coil yoke 40 along the second spatial direction Y through a corresponding recess in the first support plate 7 in the direction of the first broadside plate 5 in order to bring the magnetic flux generated by the coils 41, 42 as close as possible to the molten metal in the mold and thus develop the best possible braking effect. In an analogous manner, a pole piece 49' extends from each coil yoke 40' of the coils 41', 42' of the fourth coil arrangement 21' along the second spatial direction Y through a corresponding recess in the second support plate 7' in the direction of the second broad side plate 5' (in FIG 2 not shown). The centers of the contact surfaces of the pole pieces 49 are in FIG 2 each shown with a cross and define a second plane 20 normal to the third spatial direction Z.

FIG 3 shows a section through the exemplary embodiment of the electromagnetic stirring and braking device 1 according to the invention along the first plane 10 normal to the third spatial direction Z. Liquid molten metal is introduced into the interior of the mold 2 via the dip tube 3, which passes through the first and second broad side plates 5, 5 ' and by two narrow side plates (in FIG 3 not shown). Along the first support plate 7 (in FIG 3 not shown), the coils 31 to 38 of the first coil arrangement 11 are each arranged on their own magnetically conductive coil yoke 30. Each coil yoke 30 is contacted by a pole piece 39, which transmits the magnetic flux generated by the coils 31 to 38 through corresponding recesses in the non-magnetic first support plate 7 the first broadside plate 5 approaches. On the side facing away from the first broadside plate 5 or the first support plate 7, the coil yoke 30 of each coil 31 to 38 is contacted by the first outer yoke 13.

The arrangement of the coils 31' to 38' of the second coil arrangement 11' on a respective coil yoke 30' with a corresponding pole piece 39' and connecting second outer yoke 13' along the second broadside plate 5' of the mold 2 is a mirror image with respect to a plane normal to the second Spatial direction Y to the coils 31 to 38 of the first coil arrangement 11 or their pole pieces 39 and first outer yoke 13.

Each of the coils 31 to 38 or 31' to 38' of the first and second coil arrangements 11, 11' comprises two electrical connection points, each of these connection points being connected via a permanent electrical line (in FIG 3 each symbolized by a solid line) is connected either to a first or second connection terminal 50, 50', to a first or second switchable terminal 60, 60' or to a connection point of a further coil 31 to 38 or 31' to 38'.

The first connection terminals 50 are in FIG 3 marked with L1, L2 or L3 and each with a first connecting line of a first, second or third phase line of a three-phase direct and alternating current system (in FIG 3 not shown) electrically connectable. The second connection terminals 50' are analogous to this FIG 3 marked with L1', L2' or L3' and can each be connected to a second connection line of a first, second or third phase of the three-phase direct and alternating current system. The first and second connecting lines of the first, second and third phase lines of the three-phase direct and alternating current system are each fed from a separate power source, whereby the electrical potentials of the first, second and third phase lines are separated from each other.

Furthermore, there are FIG 3 the first and second switchable terminals 60 and 60 'are shown in the form of rectangular symbols without identification or with the designation A and B. Each of the switchable terminals 60, 60' is connected via a permanent electrical line (solid line) either to one of the connection terminals 50, 50' or to a connection point of one of the coils 31 to 38 or 31' to 38'. In addition, each of the switchable terminals 60, 60' can be connected via a connecting element 70, 71, 72 (in FIG 3 shown as dashed lines) can be reversibly (in the sense defined above) electrically connected to another of the switchable terminals 60, 60 '. The first and second switchable terminals 60, 60', together with the connecting elements 70, 71, 72, are part of a first and second switching device 80, 80', respectively, which are switched, for example, manually by an operator in accordance with a stirring or braking and acceleration mode can be. Alternatively, the first and second switching devices 80, 80 'can be controlled remotely by a system automation system (in FIG 3 not shown).

Specifically, in the in FIG 3 illustrated embodiment, the coils 31 to 38 and 31 'to 38' of the first and second coil arrangements 11 and 11' are connected in series to form three different coil groups U, V, W, the in FIG 3 top, fourth and fifth top and bottom coils 38, 38', 35, 35', 34, 34', 31 and 31' of the first and second coil arrangements 11 and 11' form the coil group U with the aid of four switchable first and second coils Terminals 60 and 60 'and four connecting elements 70 form. Furthermore, the second highest and second lowest coils 37, 37 ', 32 and 32' of the first and second coil arrangements 11 and 11' together form the coil group V with the aid of four switchable first and second terminals 60 and 60 ', four Connecting elements 70 and the connecting element 71, which connects the switchable first terminal 60 designated B with the switchable second terminal 60 'designated B. Likewise, the third highest and third lowest coils 36, 36 ', 33 and 33' of the first and second coil arrangements 11 and 11' form the coil group W with the aid of four switchable first and second terminals 60 and 60 ', four connecting elements 70 and the connecting element 72 , which connects the switchable first terminal 60 designated A with the switchable second terminal 60 'designated A.

The individual coils 31 to 38 and 31 'to 38' are in FIG 3 marked according to its membership in one of the groups U, V, W, whereby a negative sign means that the magnetic flux it generates at a certain moment is oriented spatially opposite to the magnetic flux of a coil of the same group without a negative sign. FIG 3 thus shows an embodiment according to the invention with the value m = 1 in relation to the number of coils per coil group.

Through the in FIG 3 shown electrical connection of the coils 31 to 38 and 31 'to 38' of the first and second coil arrangements 11 and 11 ', the electromagnetic stirring and braking device 1 can be operated in a 'braking and acceleration mode': the direction of movement of the magnetic flux strength ( specifically: an absolute value of the vector magnetic flux, for example its maximum absolute value) of the electromagnetic traveling fields generated in this mode is represented by arrows which are oriented in the same direction along the insides of the first and second broadside plates 5, 5 '. In this context, the same direction means that the direction of movement of the magnetic flux strength on the first broadside plate 5 is synchronous with the direction of movement of the magnetic flux strength on the second broadside plate 5 'and on both broadside plates 5, 5' either the dip tube 3 is directed towards or away from the dip tube 3 (in FIG 3 the latter is shown).

FIG 4 shows the identical exemplary embodiment FIG 3 with the difference that in FIG 4 there is an electrical connection of the coils 31 to 38 and 31 'to 38' of the first and second coil arrangements 11 and 11', by means of which the electromagnetic stirring and braking device 1 can be operated in a 'stirring mode' in which the direction of movement of the magnetic flux strength the electromagnetic traveling fields are oriented in opposite directions, which in FIG 4 is shown by corresponding arrows along the insides of the first and second broadside plates 5, 5 '. In other words: the movement of the magnetic flux strength along the first broadside plate 5 is at all times opposite to the movement of the magnetic flux strength along the second broadside plate 5 '.

A difference to the connection according to FIG 3 is that in the connection according to FIG 4 six connecting elements 70 each connect two first switchable terminals 60 and another six connecting elements 70 each connect two second switchable terminals 60 'in a changed configuration. A further difference is that the connecting element 71 contacts that second switchable terminal 60' (identifier B) which is connected to the third lowest coil 33' of the second coil arrangement 11' and that the connecting element 72 contacts that second switchable terminal 60' (identifier A ) contacted, which is connected to the second lowest coil 32 'of the second coil arrangement 11'. In contrast, according to in FIG 3 In the circuit shown, the connecting elements 71 and 72 are connected to the second-lowest coil 32' or second-lowest coil 33' via a respective second switchable terminal 60 '.

In short, you can choose between a circuit for a 'braking and acceleration mode' according to FIG 3 and an interconnection for a 'stirring mode' FIG 4 be changed by six connecting elements 70 between two first switchable terminals 60 and a further six connecting elements 70 between two second switchable terminals 60 'in the aforementioned sense and by exchanging the connection points of two further connecting elements 71 and 72 with each other. Both - enclosing the connecting elements 70 and swapping the connection points of the connecting elements 71 and 72 - can be done both manually by an operator and purely remotely.

FIG 5 shows a section through the exemplary embodiment of FIG 1 in a second plane 20 normal to the third spatial direction Z, which comprises a third coil arrangement 21 along the first broadside plate 5 and a fourth coil arrangement 21 'along the second broadside plate 5' of the mold 2. Continues to show FIG 5 a first and a second center plane ε ₁ and ε ₂ through the geometric center of the mold 2, the first center plane ε ₁ being normal to the second spatial direction Y and the second center plane ε ₂ being normal to the first spatial direction X.

The third coil arrangement 21 comprises two coils 41 and 42, each of which is arranged on its own magnetically conductive coil yoke 40. At the end facing the first broad side plate 5, a magnetically conductive pole piece 49 is arranged on each coil yoke 40, which extends through recesses in the magnetically non-conductive first support plate 7 (in FIG 5 not shown) extends directly to the outside of the first broadside plate 5. The ends of each coil yoke 40 facing away from the first broadside plate 5 are connected to one another via a third outer yoke 23.

The fourth coil arrangement 21' includes two coils 41' and 42' on a respective coil yoke 40' and, together with corresponding magnetically conductive pole pieces 49' and a connecting fourth outer yoke 23', is a mirror image of the first coil arrangement 21 along the second broadside plate 5' the first center plane ε ₁ is arranged.

With the help of the third and fourth coil arrangements 21, 21 ', static magnetic fields can be generated inside the mold 2, which exert a braking force on the molten metal flowing in the casting direction of the mold 2. Specifically, opposing coils 41 and 41' or 42 and 42' of the first and second coil arrangements 21 and 21' are electrically connected in such a way that - as in FIG 5 shown by solid arrows - in relation to the second center plane ε ₂ results in an opposite magnetic field course. For this purpose, the coils 41, 41', 42, 42' of the third and fourth coil arrangements 21, 21' can be powered, for example, from a single direct current source (in FIG 5 not shown). However, in order to be able to independently control the strength of the magnetic fields that are generated on both sides of the second center plane ε ₂ , it is also possible to pass through the coils 41, 41', 42, 42' of the third and fourth coil arrangements 21, 21' to feed two separate and separately controllable direct current sources.

Reference symbol list

1

Electromagnetic stirring and braking device

2

mold

2'

pouring end

3

Dip tube

4

Exit opening

5, 5'

first, second broadside plate

7, 7'

first, second support plate

9

molten metal

10

first floor

11, 11'

first, second coil arrangement

13, 13'

first, second outer yoke

16, 16', 16"

Support rollers

18

Oscillating device

19

casting mirror

20

second level

21, 21'

third, fourth coil arrangement

23, 23'

third, fourth outer yoke

30, 30'

Coil yoke

31...38

Kitchen sink

31' ... 38'

Kitchen sink

39, 39'

Pole shoe

40, 40'

Coil yoke

41, 42,

Kitchen sink

41', 42'

Kitchen sink

49, 49'

Pole shoe

50, 50'

first, second connection terminals

60, 60'

switchable terminal

70, 71, 72

connecting element

80, 80'

Switching device

ε1, ε2

first, second middle level

AND MANY MORE

Coil group

X, Y, Z

orthogonal spatial directions

Claims (14)

Electromagnetic stirring and/or braking device (1) for a mold (2) for casting metal slabs, - the electromagnetic stirring and/or braking device (1) set up to generate traveling electromagnetic fields and/or stationary magnetic fields moving in the mold (2). - a first coil arrangement (11) arranged on a first broad side plate (5) of the mold (2) and a second coil arrangement (11') arranged on a second broad side plate (5 ') of the mold (2), - wherein the first and second coil arrangements (11, 11') are arranged in a first plane (10) normal to the casting direction of the mold (2) and each comprise a plurality of coils (31,...38') which are of can be supplied with a three-phase direct and alternating current system and whose axes are oriented normal to the first and second broadside plate (5, 5 '), - wherein the first and second coil arrangements (11, 11') each have a group of 3m+ ₁ coils (31...34 ; 35...38; 31'...34';35'...38'), where m is a natural number and where those two coils ({31,34}, {35,38}, { 31',34'}, {35',38'}) of a group, which have the smallest or the largest distance from the second center plane (ε ₂ ), can each be fed from the same phase line, - a first and a second outer yoke (13, 13') and a coil yoke (30, 30') for each coil (31,...38') of the first and second coil arrangements (11, 11') on which the respective coil (31,...38') is arranged, the ends of each coil yoke (30) of the first coil arrangement (11) facing away from the mold being connected to each other via the first outer yoke (13) and the ends of each coil yoke (30') of the second coil arrangement (11) facing away from the mold ') are connected to each other via the second outer yoke (13'), - a magnetically conductive pole piece (39, 39') on the side facing the mold of each coil yoke (30, 30') of the first and second coil arrangements (11, 11'), which are in a first and second support plate (7, 7') the mold (2) are arranged, and - a switching device (80, 80') arranged on the first and second coil arrangements (11, 11') with terminals (60, 60') and connecting elements (70, 71, 72), each connecting element (70, 71, 72) can be reversibly electrically connected to two terminals (60, 60'). Electromagnetic stirring and braking device (1) according to claim 1, wherein one or more coils (31,...38) of the first coil arrangement (11) and one or more coils (31',...38') of the second coil arrangement ( 11 ') are connected to a coil group (U, V, W), with all coils (31,...,38, 31',..., 38') of a coil group (U, V, W) from the same phase line of the three-phase direct and alternating current system can be fed and each coil group (U, V, W) is fed by a different phase line of the three-phase direct and alternating current system, the alternating currents of all phase lines each having the same frequency in a range between 0 to 5 Hz and where There is a fixed phase shift (ϕ) between the alternating currents of the individual phase lines. Electromagnetic stirring and braking device (1) according to claim 1 or 2, where m is greater than or equal to 2. Electromagnetic stirring and braking device (1) according to one of the preceding claims, wherein one or more of the magnetic pole pieces (39, 39 ') of the first and second coil arrangements (11, 11') are made of magnetically highly permeable material made of a cobalt-iron alloy a mass-related cobalt content greater than or equal to 17%. Electromagnetic stirring and braking device (1) according to one of the preceding claims, characterized in that the pole pieces (39, 39 ') of the first and second Coil arrangement (11, 11') are designed in such a way that an end-side, mold-facing cross-sectional area of the pole pieces (39, 39') is reduced to a value of a cross-sectional area of the associated coil yoke that is reduced by at least 30%. Electromagnetic stirring and braking device (1) according to one of the preceding claims, wherein one or more pole pieces (39, 39') of the first and second coil arrangements (11, 11') are guided upwards at their ends facing the mold. Electromagnetic stirring and braking device (1) according to one of the preceding claims, wherein the connecting elements (70, 71, 72) and the terminals (60, 60 ') are arranged such that it is possible to switch between a stirring mode and a braking and acceleration mode . Electromagnetic stirring and braking device (1) according to one of the preceding claims, wherein the switching device (80, 80') is designed as an electrical switch which can be controlled remotely. Electromagnetic stirring and braking device (1) according to one of the preceding claims, wherein the coils (31,..., 38') of the first and second coil arrangements (11, 11') are designed as waveguides into which a cooling medium can be fed . Electromagnetic stirring and braking device (1) according to one of the preceding claims, further comprising - a third and a fourth coil arrangement (21, 21') for generating at least two static magnetic fields in a second plane (20) normal to the casting direction of the mold (2), the third coil arrangement (21) having at least two coils (41, 42) comprises and is arranged on the first broadside plate (5) and the fourth coil arrangement (21 ') has at least two coils (41', 42') comprises and is arranged on the second broadside plate (5 '), the coils (41,..., 42') of the third and fourth coil arrangements (21, 21') being able to be fed by one or more direct current sources, - a third and a fourth outer yoke (23, 23') and a coil yoke (40, 40') per coil (41,...42') of the third and fourth coil arrangement (21, 21') on which the respective coil (41,...42') is arranged, the ends of each coil yoke (40) of the third coil arrangement (21) facing away from the mold being connected to each other via the third outer yoke (23) and the ends of each coil yoke (40') of the fourth coil arrangement (21) facing away from the mold ') are connected to each other via the fourth outer yoke (23'), and - a magnetically conductive pole piece (49, 49') on the side facing the mold of each coil yoke (40, 40') of the third and fourth coil arrangement (21, 21'), which is arranged in the first or second support plate (7, 7'). . Electromagnetic stirring and braking device (1) according to claim 6, wherein the second level (20) is spaced 450mm to 800mm in the casting direction from a pouring-side end (2') of the mold (2). Electromagnetic stirring and braking device (1) according to claim 6 or 7, wherein one or more coils (41, 42) of the third coil arrangement (21) and one or more coils (41 ', 42') of the fourth coil arrangement (21') respectively can be fed from a separate direct current source. Method for casting metal slabs in a mold (2) with an electromagnetic stirring and braking device (1) according to one of the preceding claims, comprising the steps - reversible electrical connection of the electrical connection lines of the three-phase direct and alternating current system to the connection terminals (50, 50') and reversible electrical connection of the connecting elements (70, 71, 72) to the switchable terminals (60, 60') of the switching device (80, 80') corresponding to a predetermined stirring or braking and acceleration mode for the first and second coil arrangements (11, 11'), - Casting a casting strand onto the mold (2), - Generating traveling electromagnetic fields moving in the mold (2) by feeding the first and second coil arrangements (11, 11') from the three-phase direct and alternating current system in accordance with the predetermined stirring or braking and acceleration mode. Method for casting metal slabs in a mold (2) with an electromagnetic stirring and braking device (1) according to one of claims 8 to 12, comprising the steps - generating traveling electromagnetic fields moving in the mold (2) by feeding the first and second coil arrangements (11, 11') from the three-phase direct and alternating current system in accordance with a first or a second stirring or braking and acceleration mode, - Wherein, for the purpose of changing from the first to the second stirring or braking and acceleration mode, the reversible electrical connection of the connecting elements (70, 71, 72) to the switchable terminals (60, 60 ') takes place using remote switching technology.

Images