EP3025799B2 - Rolling mill - Google Patents

Description

The invention relates to a rolling mill with at least a first and a second roll stand, at least one inductor arranged between the first and the second roll stand for heating a metal strip moved by the inductor, the inductor being an upper induction coil which is arranged above the metal strip to be heated and a lower induction coil, which is arranged below the metal strip to be heated and opposite to the upper induction coil. In addition, the rolling mill comprises an energy supply device for supplying the upper and the lower induction coil with electrical energy. In addition, the invention relates to a casting and rolling system with a casting machine for producing the metal strip and a rolling system according to the invention downstream of the casting machine in the material flow direction. Finally, the invention also relates to a method for producing a metal strip.

Inductors for heating metal strip are basically known in the prior art, for. B. from the GB 770 548 , of the JP 022 07 481 , of the JP 06122928 , of the JP 2000-252050 , of the JP 2004 306069-71 , of the WO 2010 036987 A2 and the WO 2014 021596 , the cited documents describing more distant prior art.

Furthermore, reference is made to the JP 4172122 which discloses vertically adjustable inductor halves which are moved vertically when a ski is detected on the head of a metal strip with the aid of a camera in order to avoid a collision of the metal strip with the inductor. The upper and lower induction coils are moved vertically according to a measured tape position. However, the said Japanese application only speaks of an inductor, without distinguishing between cross-field or longitudinal field inductors.
The US 5,495,094 discloses inductor loops with a 180 ° phase shift, which in this respect represent a longitudinal field inductor. The inductor loops can each be adjusted independently of one another perpendicular to a stationary workpiece to be heated. The use of longitudinal and transverse field inductors in a rolling mill is disclosed in EP 2 416 900 B1 . The WO 2012 045585 A2 discloses a laterally open cross-field inductor for entering or leaving the line of a metal strip in a rolling mill.
The EP 0 721 813A1 discloses a C-shaped inductor between two adjacent mill stands in a finishing train.
In said prior art, a distinction is made between longitudinal field and cross-field inductors. Cross-field inductors are primarily used for heating thin strips with thicknesses <12 mm, while longitudinal field inductors are used for heating thicker strips with thicknesses> 6 mm, for example. Depending on the design and boundary conditions as well as a selected frequency range, there is a transition range in the practical use of the two types of induction heating; please refer EP 2 416 900 B1 .

Figure 9 shows the construction and mode of operation of a known cross-field inductor 180. It comprises an upper cross-field induction coil 182, which is assigned to the top of the metal strip 200. In addition, the cross-field inductor comprises a lower cross-field induction coil 184, which is assigned to the underside of the metal strip 200. As in Figure 9 shown, the opening cross sections of the upper and lower transverse field inductor coils lie opposite one another and in each case parallel to the metal strip 200. The magnetic field lines generated during operation of the inductor are shown in FIG Figure 9 also represented symbolically. The upper and the lower cross-field inductor coils 182, 184 can each be moved, ie adjusted, independently of one another perpendicular to the plane of the metal strip 200. As the course of the field lines shows, the magnetic field or the magnetic flux acts primarily perpendicular to the plane of the metal strip. The divided arrangement of the coils advantageously enables the two induction coils, ie in the case of both inductor halves, to be adjusted independently of one another perpendicular to the plane of the metal strip and that the inductor can be designed to be open on the side. In the event of a fault, the distance between the coils and the metal strip can therefore be slightly increased and / or the inductor can be moved out of the line of the metal strip.

Figure 8 shows an example of a known longitudinal field inductor, which is typically designed as a closed frame. The metal strip to be heated therefore runs through a closed rectangular gap when it passes the known longitudinal field inductor. As in Figure 8 It can be seen that the longitudinal field inductor essentially generates a magnetic field in the transport direction of the metal strip to be heated.

The said definitions and the shape of transverse and longitudinal field inductors are also from the WO 2014 021596 known.

The Japanese patent application JP 61195708 discloses a cross-field inductor with coils opposite the top and bottom of a metal strip to evenly heat the metal strip. The part of the inductor assigned to the upper side of the metal strip and the part of the inductor assigned to the underside of the metal strip are each assigned moving devices in order to move the respective parts of the inductor perpendicular to the surface of the metal strip as a function of detected unevenness or curvatures in the metal strip perpendicular to its surface to proceed.
The European patent application EP 2 340 897 A1 discloses a rolling mill with a roughing stand and at least one stand of a finishing mill and with a longitudinal field inductor arranged between the two stands for heating the metal strip moved by the longitudinal field inductor. The longitudinal field inductor has an upper induction coil, which is assigned above the metal strip to be heated, and a lower induction coil, which is arranged below the metal strip to be heated, opposite the upper induction coil. At least implicitly, the EP 2 340 897 A1 also an energy supply device for supplying the induction coils of the longitudinal field inductor with electrical energy. The preamble of claims 1 and 14 is based on the WO2014 / 135710A1 . The invention has for its object to develop a known rolling mill and a known casting-rolling plant for producing a metal strip such that in particular thicker metal strip with thicknesses> 6 mm, for example, is heated and rolled particularly effectively, ie using as little electrical energy as possible .

This object is achieved by the rolling mill according to main claim 1 and a casting and rolling plant. Claim 14 solved.

The main advantage of the invention of a new induction heater for a rolling mill, in particular a hot strip mill, is to combine the advantages of the above-described inductor types, namely the possibility of placing the upper or lower inductor coils and the efficient heating of thicker strips or slabs.

The adjustability or the method of the upper and / or lower longitudinal field inductor coils perpendicular to the metal strip is particularly important if the metal strip thickness in the area of the longitudinal field induction heaters of e.g. B. 6-20 mm - d. H. at z. B. ΔH = 14 mm - or in another application between z. B. 32-70 mm - d. H. at z. B. ΔH = 38 mm - varies. In general, the adjustability of the divided longitudinal field inductors makes sense for thickness variations of ΔH ≥6 mm or particularly preferably of ΔH ≥ 15 mm.

When using a roughing stand within a z. B. conventional rolling mill, the roughing strip between the roughing stand and the first rolling stand of the finishing train loses temperature particularly quickly. In particular, the "waiting" end of the strip cools down because it has to linger longer before the finishing mill or is simply colder. This requires higher rolling forces in the finishing mill when rolling the strip end. The provision according to the invention of an induction heater in the form of an inductor advantageously makes it possible to raise the temperature level at the end of the strip, but also over the entire length of the strip, as far as necessary. Controlling the inductor with currents in opposite phases, so that the inductor can be operated as a longitudinal field inductor between the roughing stand and the first stand of the finishing mill, offers the advantage of more efficient heating, particularly in the case of thicker strips. Finally, the still claimed movability of the upper and lower induction coils perpendicular to the plane of the metal strip enables the advantage that the distance of the two coils from the metal strip can be optimally adjusted individually with regard to the respective metal strip thickness, so that heat transfer into the metal strip is as effective as possible . In practice, in a working position, i.e. H. if the metal strip runs through the inductor without malfunction during operation of the rolling mill, a distance of less than 60 mm, preferably less than 20 mm, in each case of an induction coil from the metal strip is sought. A minimum distance of 15 mm has been shown to be advantageous.

Due to the claimed combination of the above-mentioned measures, in particular thicker metal strips with thicknesses of, for example, greater than 6 mm are optimally heated before entering a finishing mill.

The terms “inductor coil” and “induction coil” are used interchangeably in the description.

According to a first exemplary embodiment, the energy supply device has upper capacitors which are connected to the upper induction coil to form an upper partial resonant circuit, and the energy supply device has lower capacitors which are connected to the lower induction coil to form a lower partial resonant circuit. The upper longitudinal field inductor traversing device is then designed to move the upper partial resonant circuit perpendicular to the top of the metal strip and / or the lower longitudinal field inductor traversing device is then designed to move the lower partial resonant circuit perpendicular to the underside of the metal strip.

The above claimed operation of the inductor's upper and lower inductors with antiphase electrical currents allows the inductor, i. H. the longitudinal field inductor can be made C-shaped. This advantageously also enables the transverse movement of the longitudinal field inductor into and out of the line of the metal strip. The possibility of moving out of the line of the metal strip is particularly advantageous in the event of a malfunction in the rolling mill or if there is a shaft in the metal strip or if there is a ski on the head of the metal strip.

The upper and the lower induction coil can each be formed from a single turn or from a plurality of partial turns connected in parallel and preferably crosswise. The provision of a single turn is often chosen at high frequencies. To ensure that the current is distributed as evenly as possible when the windings are connected in parallel, a fall, ie a crossover connection of the windings, must be provided. This technology, known from electric motor technology, ensures that an external partial conductor is arranged in the outgoing conductor and on the inside in the return conductor. Through this crosswise connection, the current load of the parallel conductor. Since the conductors must cross at the winding overhangs, these should be designed with particularly little stray field. The same partial inductances are also achieved by the cross-connection.

The energy supply device is advantageously designed to operate the induction coils and the partial resonant circuits - depending on the thickness of the metal strip - with current or voltage frequencies between 2 kHz and 30 kHz. The frequency increases as the band thickness decreases.

The number of partial turns per induction coil is between 3 and 15, depending on the frequency. The greater the number of partial turns, the finer the distribution of the current. But the complexity of the inductor also increases with a larger number of partial turns. The inductor windings are typically covered with laminated cores made of laminated, layered electrical sheets to reduce the stray field. This measure is useful and necessary because the upper and lower induction coils are installed in close proximity to other rolling mill components. Since the other rolling mill components are almost exclusively made of ferrous materials, no stray field may emerge from the induction coils of the longitudinal field or transverse field inductors and the other rolling mill components may also heat up.

In addition to the claimed longitudinal field inductor between the at least one roughing stand and the first rolling stand of the finishing train, at least one transverse field inductor can also be provided in the rolling mill, which can then be operated in addition to the at least one longitudinal field inductor. With the cross-field inductors, not only is the strip center to be heated, but at the same time the strip edges are heated up to efficiently produce a uniform strip temperature across the finished strip width.

An upper cross-field inductor coil or an upper cross-field inductor partial resonant circuit and a lower cross-field inductor coil or a lower cross-field inductor partial resonant circuit of the cross-field inductor are then likewise perpendicular to the plane spanned by the metal strip and / or transverse to the longitudinal direction of the metal strip, with the aid of associated cross-field inductor displacement devices .

The upper and lower transverse field inductor traversing device and / or the upper and / or lower longitudinal field inductor traversing device are controlled by a control device.

A temperature measuring device is provided for detecting the distribution of the temperature of the metal strip over its width, and the control device is designed to control the upper and / or lower longitudinal field inductor displacement device so that the longitudinal field inductor positions in response to the measured temperature distribution can be that the difference between the measured temperature distribution and a predetermined target temperature distribution across the width of the metal strip behind the finishing mill is minimal. Several longitudinal field or transverse field inductors can preferably be arranged distributed over the length of the system.

In addition, a sensor device is provided for detecting an irregularity in the metal strip, such as a ski on the head of the metal strip, a shaft or an arc in the metal strip, or another disturbance in the rolling process. In this case too, the control device is designed to control the upper and / or lower longitudinal field inductor displacement device in such a way that the distance of the induction coils from the top or the bottom of the metal strip is suitably changed in the area of the irregularity and / or the inductors from the line of the Metal strip can be moved out.

Furthermore, at least one touch sensor can be provided for detecting a contact of the longitudinal field inductor and / or transverse field inductor by the metal strip. In this case, the control device is designed to control the moving devices in such a way that the longitudinal field inductor and / or the transverse field inductor is opened in the thickness direction and / or is moved laterally out of the line of the metal strip.

By using Liquid Core Reduction, d. H. a change in the slab thickness within the casting plant, the thicknesses change with which the metal strip from the casting plant enters an oven or the at least one roughing stand of the rolling plant. The thickness of the metal strip also changes within the rolling mill behind a roughing stand or between the individual rolling stands on a finishing mill. Because of their adjustability across the plane of the metal strip, the claimed longitudinal field and cross-field inductors can be optimally adjusted to the individual thickness of the metal strip at the points mentioned. Because the inductors, in particular the longitudinal field inductors, are each C-shaped or laterally open, they can also be used well with larger tolerances with regard to the lateral course of the metal strip.

The above object is achieved with respect to the casting and rolling plant by the subject matter of claim 14. The advantages of this solution correspond to the advantages mentioned above with reference to the rolling mill claimed.

A furnace can be connected between the casting machine and the rolling train, and advantageously a further longitudinal field inductor and / or the transverse field inductor can then advantageously be connected between the furnace and the roughing stand for further heating. The arrangement of the further is particularly advantageous Longitudinal field inductor between the furnace and the at least one roughing stand, also the arrangement of the longitudinal field inductor between the roughing stand and the first stand of the finishing rolling mill and the arrangement of a transverse field inductor between individual stands of the finishing rolling mill.

Further advantageous refinements of the rolling plant and the casting-rolling plant are the subject of the dependent claims.

Further general statements on the subject matter of the invention:

The use of split, adjustable induction coils of the longitudinal field inductor is particularly suitable for thicknesses of the metal strip> 6 mm, because in this thickness range the non-closed longitudinal field inductor according to the invention offers better efficiency than the transverse field inductor and / or the closed longitudinal field inductor designed with a frame structure. The adjustable, adjustable longitudinal field inductor according to the invention is preferably used at a strip temperature range of> 750 ° C. It is particularly suitable for continuous rolling (see definition below) or also for conventional rolling of flat products in a hot strip mill. The distance d of the inductor surface from the metal strip, i.e. H. the distance between the side or surface of the induction coil facing the metal strip and the metal strip is, as said, preferably less than 20 mm during active operation of the longitudinal field inductor. When starting up the system or troubleshooting, the safety distance between the induction coils and the metal strip can be more than 100 mm, in exceptional cases even more than 500 mm.

The split, adjustable longitudinal and transverse field inductors are preferably used in an endless casting and rolling process. In this mode of operation, the casting installation and the rolling installation are connected via the casting strand. Both systems are then coupled and work with the same mass flow. This process has to be started at some point and then an induction heater consisting of divided inductors (top, bottom), which can be turned on and is open at the side, is particularly advantageous. This design is also advantageous in the start-up and unthreading process or in a fault situation.

• Bei diesem Einfädelvorgang des Bandkopfes ist/sind die teilbaren Längsfeldinduktoren weiter geöffnet oder/und alternativ in Warteposition neben dem Band, weil mit einem Band-Ski oder Bandwellen bzw. -bögen gerechnet werden muss.
• Nach Passieren des jeweiligen Induktors oder nach Aufbau eines Bandzuges zwischen den zwei Gerüsten oder zwischen einem Gerüst und Treiber werden die geöffneten Induktoren auf den engen Betriebsabstand, d. h. eine enge Arbeitsposition angestellt oder erst in die Walzlinie gebracht und dann angestellt.
• Erst in Betriebsposition oder nahe der Betriebsposition wird der jeweilige Induktor aktiviert und das Band durch den Induktor geheizt.
• Bei Verstellung (z. B. Verminderung) der Dicke werden die Induktorpositionen entsprechend nachgefahren (z. B. enger gestellt).

Starting the continuous casting and rolling process using split, adjustable longitudinal field inductors:

• In this threading process of the tape head, the separable longitudinal field inductors are / are opened further or / and alternatively in the waiting position next to the tape, because a tape ski or tape waves or sheets must be expected.
• After passing through the respective inductor or after building a strip tension between the two stands or between a stand and driver, the opened inductors are set to the narrow operating distance, ie a close working position, or first brought into the rolling line and then set on.
• The respective inductor is only activated and the strip is heated by the inductor only in the operating position or close to the operating position.
• When adjusting (e.g. reducing) the thickness, the inductor positions are adjusted accordingly (e.g. tightened).

• Kurz bevor das Bandende das Gerüst vor der jeweiligen Induktorstrecke verlässt und der Bandzug abgebaut wird, wird der teilbare Längsfeldinduktor wieder geöffnet oder/und der Induktor herausgefahren, um auch dort eine Beschädigung oder Berührung der Induktoren zu vermeiden. Diese Fahrweise muss nicht zwangsläufig stattfinden, die Anlage kann aber sicherheitshalber so betrieben werden.

Unthreading the end of the slab or strip after the end of casting or the end of the continuous casting and rolling process:

• Shortly before the end of the strip leaves the stand in front of the respective inductor section and the strip tension is removed, the separable longitudinal field inductor is opened again and / or the inductor is pulled out in order to avoid damage or contact with the inductors there as well. This mode of operation does not necessarily have to take place, but the system can be operated as a precaution.

• Kommt es zu einem Walzunfall oder andere Massenflussstörungen im Filetteil des Bandes so besteht die Gefahr, dass sich ein Bandbogen im Bereich des Induktors bildet und eine Berührung des Bandes am Induktor stattfindet. Auch in diesem Fall wird der geteilte Längsfeldinduktor geöffnet.
• Zur Störungsbeseitigung wird der Längsfeldinduktor ggf. auch aus der Walzlinie heraufgefahren.
• Eine eventuelle Berührung des Bandes an dem Induktor wird durch optische oder mechanische Sensoren detektiert. Vorteilhafterweise werden Bewegungssensoren z. B. Beschleunigungsgeber am Längsfeldinduktor oder an einer Längsfeldinduktorgruppe angebracht (oben oder/und ggf. unten). Bei einem Berührungssignal oder Berührungsgefahr wird die Längsfeldinduktionsheizung entsprechend oben, unten oder beidseitig aufgefahren.

Interference protection during the rolling process:

• If there is a roll or other mass flow disturbances in the fillet part of the strip, there is a risk that a strip arc will form in the area of the inductor and that the strip will touch the inductor. In this case too, the divided longitudinal field inductor is opened.
• To rectify the fault, the longitudinal field inductor may also be brought up from the rolling line.
• Any contact with the strip on the inductor is detected by optical or mechanical sensors. Advantageously, motion sensors such. B. Accelerator attached to the longitudinal field inductor or to a longitudinal field inductor group (above or / and possibly below). In the event of a touch signal or danger of contact, the longitudinal field induction heating is opened up, down or on both sides.

The above procedure or use of adjustable inductors is preferably used in continuous strip casting processes in particular between two finishing stands, which have a stand spacing of 5 m to <40 m and which are operated in endless mode.

A process model is used to control the start-up and removal strategy in the continuous strip casting process, which controls the settlement of the roll stands and activation of the inductors.

In particular, the strip areas of different strip temperatures are also tracked by the rolling mill and the effect of the temperature differences on the stand loading and stand setting is taken into account. That is, the cold strip head is set to a higher strip thickness or the decreases are limited and so z. B. also kept the scaffolding load within permissible limits.

Figur 1

eine Walzanlage mit eingebauten erfindungsgemäßen Induktoren;

Figur 2

die Wirkungsweise des erfindungsgemäßen Längsfeldinduktors zwischen dem Vorgerüst und dem ersten Gerüst der Fertigwalzstraße;

Figur 3

einen Längsfeldinduktor gemäß der vorliegenden Erfindung;

Figur 4

Verfahreinrichtungen für einen Längsfeld- oder Querfeldinduktor senkrecht zur Ebene des Metallbandes sowie einen Induktionswagen zum Verfahren des Längs- oder Querfeldinduktors quer zum Metallband;

Figur 5

die Verwendung einer Temperaturmesseinrichtung und Sensoreinrichtungen zum Detektieren einer Unregelmäßigkeit in dem Metallband zum geeigneten Verfahren der Induktoren;

Figur 6

eine Gieß-Walz-Anlage mit einem Beispiel für den Einsatz der erfindungsgemäßen Längsfeld- und Querfeldinduktoren;

Figur 7

den Wirkungsgrad der erfindungsgemäßen geteilten anstellbaren Längsfeldinduktoren in Abhängigkeit der Banddicke und im Vergleich zu Längsfeldinduktoren mit geschlossener Rahmenstruktur und zu Querfeldinduktoren;

Figur 8

einen Längsfeldinduktor mit geschlossener Rahmenstruktur gemäß dem Stand der Technik; und

Figur 9

einen Querfeldinduktor gemäß dem Stand der Technik

zeigt.The invention is accompanied by nine figures

Figure 1

a rolling mill with built-in inductors according to the invention;

Figure 2

the mode of operation of the longitudinal field inductor according to the invention between the roughing stand and the first stand of the finishing mill;

Figure 3

a longitudinal field inductor according to the present invention;

Figure 4

Moving devices for a longitudinal field or transverse field inductor perpendicular to the plane of the metal strip and an induction trolley for moving the longitudinal or transverse field inductor transverse to the metal strip;

Figure 5

the use of a temperature measuring device and sensor devices for detecting an irregularity in the metal strip for the appropriate method of the inductors;

Figure 6

a casting and rolling plant with an example of the use of the longitudinal field and transverse field inductors according to the invention;

Figure 7

the efficiency of the divided adjustable longitudinal field inductors according to the invention as a function of the strip thickness and in comparison to longitudinal field inductors with a closed frame structure and to transverse field inductors;

Figure 8

a longitudinal field inductor with a closed frame structure according to the prior art; and

Figure 9

a cross-field inductor according to the prior art

shows.

The invention is described in detail below in the form of exemplary embodiments with reference to the figures mentioned. The same technical elements are denoted by the same reference symbols in all the figures.

Figure 1 shows an exemplary embodiment of the rolling mill 400 according to the invention. It comprises a roughing stand 420 and a finishing mill 440 downstream of the roughing stand in the material flow direction with the finishing stands F1-F _N. In the material flow direction R, the rolling mill 400 comprises a cooling device 450 and a reel device 460 behind the finishing mill 440.

A longitudinal field inductor 170 designed according to the invention is arranged between the roughing stand 420 and the first rolling stand F1 of the finishing mill 440. In addition, cross-field inductors 180 or further longitudinal field inductors 170 can be arranged in front of the finishing mill and / or between individual stands of the finishing mill 440.

Figure 2 illustrates the mode of operation of the longitudinal field inductor 170: Without the presence of the longitudinal field inductor 170, the temperature of the metal strip in z. B. the conventional rolling mill according to the solid line in Figure 2 before entering the first stand F1 of the finishing mill 440, drop sharply from the strip head to the strip end. This would result in the disadvantages mentioned in the general part of the description. The longitudinal field inductor according to the invention between the roughing stand 420 and the first stand F1 of the finishing mill 440 advantageously has the effect that the temperature of the metal strip 200 from the strip head to the end of the strip can be kept constant at a high level, as shown in FIG Figure 2 is indicated by the horizontal dashed line.

The belt head can run out of the roughing stand with a ski. According to the prior art, this is eliminated or reduced before the induction heating with a roller straightening machine. If this does not succeed and a ski is still detected, the strap is retracted and pushed off. This is a disadvantage.

A split, adjustable longitudinal field inductor whose opening width can be increased (lifting the upper inductor and / or lowering the lower inductor) can ensure safe transport through the induction heating section, primarily at the head. The inductor spacing is increased depending on whether a ski or ribbon bow is detected or whether a rolling fault occurs or generally without a ribbon shape detection. After passing through the strip head (e.g. with a ski), the inductor can then be closed again and the pre-strip heated. A roller straightening machine or other measures in front of a divided, adjustable longitudinal field induction heating can thus be dispensed with if the inductor gap is enlarged on each strip head which is not to be heated and is heated.

Figure 3 shows the construction of the longitudinal field inductor 100, 170 according to the invention. It comprises an upper induction coil 110, which is arranged above the metal strip 200 to be heated, and a lower induction coil 120, which is arranged below the metal strip to be heated, opposite the upper induction coil 110. The two induction coils 110, 120 are supplied by a power supply device 130 with electrical energy, more precisely with electrical currents in opposite phases. Due to this operation of the upper and lower induction coils with opposite phase currents, the inductor 100 acts as a longitudinal field inductor 170. In contrast to traditional longitudinal field inductors, the in Figure 3 described design of the longitudinal field inductor the advantage that the upper induction coil 110 and the lower induction coil 120 are independently vertically displaceable, so that the distance of the upper induction coil to the top of the metal strip 200 and the distance of the lower induction coil 120 to the bottom of the metal strip 200 individually in the desired Way and depending on the thickness of the metal strip 200 can be adjusted.

Figure 4 illustrates that an upper capacitor 115 is typically assigned to the upper induction coil 110, the upper induction coil and the upper capacitor 115 being connected to form an upper partial resonant circuit. Similarly, the lower induction coil is connected to an associated capacitor 125 to form a lower resonant circuit. An upper longitudinal field inductor travel device 140 is assigned to the upper partial oscillating circuit for moving the upper partial oscillating circuit or at least the upper coil 110 perpendicular to the plane formed by the metal strip 200. Analogously, a lower longitudinal field inductor moving device 150 is assigned to the lower partial oscillating circuit for moving the lower partial oscillating circuit or at least the lower induction coil 120 perpendicular to the plane spanned by the metal strip 200.

The upper and lower induction coils 110, 120 of the longitudinal field inductor 100, 170 or their housing are, as in FIG Figure 4 shown, C-shaped for transverse movement of the inductor with the aid of the inductor carriage 142 or a similar transverse movement mechanism into or out of the line of the metal strip 200. The line corresponds to the material flow direction R, which in Figure 4 is directed into or out of the plane of the drawing.

As already with reference to Figure 1 mentioned, the rolling mill 400 can have a transverse field inductor 180 in addition to the at least one longitudinal field inductor 100, 170 between the roughing stand 120 and the first stand F1 of the finishing mill 440. The cross-field inductor is in a known manner as in the prior art above with reference to FIG Figure 9 described, trained. The arrangement described above with reference to the longitudinal field inductor 100, 170 according to FIG Figure 4 applies equally to the cross-field inductor 180. Specifically, the cross-field inductor 180 comprises an upper cross-field inductor coil 182 assigned to the top of the metal strip 200 and a lower cross-field inductor coil 184 assigned to the underside of the metal strip 200. Capacitors 115, 125 can also be assigned to the cross-field inductor coils 182, 184 Form partial resonant circuits together with the inductor coils. An upper cross-field inductor travel device 186 is provided for moving the upper cross-field inductor coil 182 or the upper cross-field inductor partial resonant circuit perpendicular to the plane spanned by the metal strip. Likewise, a lower cross-field inductor travel device 188 is provided for moving the lower cross-field inductor coil 184 or the lower cross-field inductor partial resonant circuit, likewise perpendicular to the plane spanned by the metal strip.

The upper and lower transverse field inductor traversing devices 186, 188 and / or the upper and lower longitudinal field inductor traversing devices 140, 150 can form a structural unit. This structural unit is preferably assigned an inductor carriage 142 for moving the longitudinal field inductor and / or the transverse field inductor transversely to the longitudinal direction of the metal strip from the line of the metal strip or into the line of the metal strip 200.

The cross-field inductor travel devices 186, 188 and / or the longitudinal field inductor travel devices 140, 150 or the inductor carriage 142 are controlled by a control device 187; please refer Figure 4 .

Figure 5 shows a plan view of the metal strip 200. A temperature measuring device 190 and possibly 550 for detecting the distribution of the temperature over its width can be seen. The temperature measuring device 190 is preferably arranged behind the last rolling stand F _{N of} the finishing mill 440. The measured temperature distribution is fed as an input variable to the control device 187, so that in response to the temperature distribution the upper and / or the lower longitudinal field inductor displacement device 140, 150 and / or the upper and / or the lower transverse field inductor displacement device 186, 188 and / or suitably controls the inductor carriage 142. In this case, suitable means that the inductor 100, ie the longitudinal field inductor 170 or the transverse field inductor 180, is positioned in response to the necessary energy input and to the measured temperature distribution such that the difference between the measured temperature distribution behind the finishing mill 440 and a predetermined one Target temperature distribution at the same position across the material width is minimal. By taking into account the effects on the inductors and in the rolling mill, the properties of the finished product can be optimally adjusted across the width.

For the appropriate control of the inductors (Power, inductor settings) with the help of a process model, the input temperature distribution 550 is also optionally taken into account.

Furthermore, a sensor device 195 can be provided for detecting an irregularity in the metal band 200, such as a ski. B. on the head of the metal strip, a shaft or an arc in the metal strip or other disruption of the rolling process. In response to a signal from the sensor device, which represents the irregularity, the sensor device 187 is then designed to control the longitudinal field inductor moving devices 140, 150 and / or the transverse field inductor moving devices 186, 188 or the inductor carriage 142 such that the distance d between the inductor coils is suitably changed from the top / bottom of the metal strip in the area of the irregularity and / or the inductors are moved out of the line of the metal strip.

Furthermore, at least one touch sensor 198 can be provided, e.g. B. in the form of a motion sensor or an accelerometer for detecting a touch of the longitudinal field inductor 170 and / or the transverse field inductor 180 by the metal strip 200. The control device 187 is then designed in response to a signal from the touch sensor, which represents the eventual touch, to control the Longitudinal field inductor moving devices 140, 150 and / or the transverse field inductor moving devices 186, 188 and / or the inductor carriage 142 such that the longitudinal field inductor 100, 170 and / or the transverse field inductor 180 opens in the thickness direction when touching the metal strip 200 and / or laterally from the Line is pulled out.

Figure 6 shows the casting and rolling plant 500 according to the invention. It comprises a casting machine 300 for producing the metal strip 200 as well as the previously described rolling plant 400 downstream of the casting machine 300 in the material flow direction R. According to a first embodiment, there is a furnace between the casting machine 300 and the rolling train 400 350 switched. As already described above, the rolling mill 400 has a longitudinal field inductor 170 and / or transverse field inductor 180 between the at least one roughing stand 420 and the first stand F1 of the finishing rolling mill 440.

A further longitudinal field inductor 170 and / or the transverse field inductor 180 can be connected between the furnace 350 and the at least one roughing stand 420.

Specifically, the further longitudinal field inductor 170 can also be connected between the furnace 350 and the roughing stand, and the transverse field inductor 180 can be connected between individual ones of the finishing stands of the finishing rolling mill.

Figure 7 illustrates the preferred field of application of the divided longitudinal field inductor according to the invention without a frame structure, ie with an upper and lower induction coil which can be adjusted individually perpendicular to the plane of the metal strip. The dashed lines show the course of the electrical efficiency for a longitudinal field inductor with a closed inductor frame, the upper and lower induction coils of which cannot be adapted to the respective thickness ratios of the metal strip. The dash-dotted line shows the course of the efficiency for a transverse field inductor and the two solid lines show the course of the electrical efficiency depending on the strip thickness for a longitudinal field inductor with advantageously individually adjustable upper and / or lower induction coil depending on the strip thickness. Both the dashed lines for the closed longitudinal field inductor and the solid lines for the longitudinal field inductor, which can be set in a split manner, are each indicated for two different frequencies f _j f _i , f _m and f _n , the different frequencies being chosen optimally with regard to the band thickness application areas become. In general, the diagram illustrates according to Figure 7 that the electrical efficiency is particularly high when using cross-field inductors (dash-dotted line) for strip thicknesses <6 mm. In contrast, for strip thicknesses of z. B. 100 mm, the efficiency is particularly large when using longitudinal field inductors, it then doesn't matter whether split adjustable longitudinal field inductors or closed longitudinal field inductors are used. Regardless, it can be seen that for medium strip thicknesses between approx. 6 and z. B. 100 mm the use of longitudinal field inductors with individually adjustable upper and lower induction coil (solid lines) is particularly effective electrically; see the vertical hatched area in Figure 7 .

Finally, the invention relates to a method for producing a metal strip with a rolling installation 400 according to the invention or a casting-rolling installation 500 according to the invention. The rolling installation and the casting-rolling installation each comprise at least one longitudinal field inductor 170 and optionally additionally at least one transverse field inductor 180 The method provides that the distance d between the upper and lower adjustable inductor coils of the longitudinal field inductor or the transverse field inductor is adjusted to a suitable operating distance d <60 mm depending on the respective thickness of the metal strip during the rolling of the fillet of the metal strip 200. This operating distance is preferably kept constant at a distance of d <20 mm during the rolling of the fillet. A minimum distance of 15 mm has been shown to be advantageous.

The upper and / or the lower adjustable inductor coil of the longitudinal field inductor and possibly also that of the transverse field inductor are either moved to a predefined safety distance during the threading process of the head of the metal strip into a roll stand or are moved outside the strip line. The induction coils only become synonymous after completion of the threading process with inductor coils, set to the appropriate operating distance. Only when the desired operating distance d to the metal strip is reached or comes close to it, are the inductors 100, 170, 180 activated, that is to say supplied with electrical energy. The energy supply device 130 according to the invention is designed to supply all electronic components, ie in particular the induction coils and the displacement devices and the inductor carriage, with electrical energy.

The upper and lower induction coils 110, 120, 184, 186 of the longitudinal field inductor 170 and / or the transverse field inductor 180 are again raised to the predefined safety distance, e.g. B. shortly before the end of the metal strip 200 leaves a roll stand in front of the respective longitudinal field inductor or transverse field inductor or when a previously existing strip tension is broken down or when a roll accident has happened or in another disturbance of the mass flow. As an alternative to moving up to the predefined safety distance, the induction coils can also be moved out of the line of the metal strip.

The casting and rolling plant is preferably operated in an endless mode and / or in a semi-endless mode. A definition of "endless mode" is given above in the general part of the description. The term "semi-endless mode" means casting a long slab that can be stored in the furnace 350, and then rolling and separating the strips in front of the reel into a few coils. Depending on the length of the furnace, e.g. B. 5 connected slabs successively rolled one after the other (similar to endless) and only shared with scissors behind the finishing train and z. B. 5 individual coils.

Reference list

100

Inductor

110

upper longitudinal field inductor

115

upper capacitors

120

lower longitudinal field inductor

125

lower capacitors

130

Power supply facility

140

upper longitudinal field inductor traversing device

142

Inductor trolley

150

lower longitudinal field inductor traversing device

170

Longitudinal field inductor

180

Cross-field inductor

182

upper cross-field inductor coil

184

lower cross-field inductor coil

186

upper cross-field inductor traversing device

187

Control device

188

lower cross-field inductor traversing device

190

Temperature measuring device

195

Sensor device

198

Touch sensor

200

Metal strap

300

Casting machine

350

oven

400

Rolling mill

420

Scaffold

430

Separator

440

Finishing mill

450

Cooling device

460

Decoiler

500

Casting and rolling plant

550

Temperature measuring device

F ₁

Second roll stand = first finish roll stand

F ₁ -F _n :

Finishing mill

d

distance

R

Material flow direction

ΔH

Variation of the metal strip thickness

Claims (16)

1. Rolling mill (400) comprising
   at least one first roll stand (420) in the form of a roughing stand and a second roll stand in the form of a first roll stand consisting of a plurality of roll stands of a finishing rolling train;
   at least one longitudinal field inductor (100, 170), which is arranged between the first and second roll stands, for heating a metal strip (200) moved through the inductor, wherein the longitudinal field inductor comprises an upper induction coil (110), which is arranged above the metal strip (200) to be heated, and a lower induction coil (120), which is arranged below the metal strip to be heated and opposite the upper induction coil and wherein the longitudinal field inductor is constructed to be divided and laterally open;
   an upper longitudinal field inductor movement device (140) is provided for moving the upper induction coil (110) perpendicularly to the upper side of the metal strip (200) and/or a lower longitudinal field inductor movement device (150) is provided for moving the lower induction coil (120) perpendicularly to the lower side of the metal strip (200);
   a control device (187) is provided for activating the upper and/or lower longitudinal field inductor movement device (140, 150); and
   an energy supply device (130) for supplying the upper and lower induction coils of the longitudinal field inductor (100, 170) with electrical energy so that they are operated by opposite-phase electric currents;
   characterised in that
   the spacing (d) of the upper induction coil (110) from the upper side of the metal strip and/or the spacing (d) of the lower induction coil (120) from the lower side of the metal strip in a working position is d < 60 millimetres, preferably d < 20 millimetres;
   a temperature measuring device (190) is provided for detecting the distribution of the temperature of the metal strip over the width thereof;
   the temperature measuring device is arranged preferably behind the last roll stand of the finishing rolling train; and
   the control device (187) is constructed for activating the upper and/or lower longitudinal field inductor movement device (140, 150) so that the longitudinal field inductor (100) or a further longitudinal field inductor (170) is so positionable in response to the measured temperature distribution that the difference between the measured temperature distribution and a predetermined target temperature distribution is minimal over the metal strip width;
   a sensor device (195) is provided for detecting an irregularity in the metal strip, such as a ski at the head of the metal strip, a wave or a curve in the metal strip, or another disturbance of the rolling process; and
   the control device (187) is so constructed for activating the upper and/or lower longitudinal field inductor movement device (140, 150) that the spacing (d) of the inductor coils from the upper side / lower side of the metal strip in the region of the irregularity is suitably changed and/or the inductors are moved out of the line of the metal strip.
2. Rolling mill (400) according to claim 1, characterised in that
   the energy supply device (130) comprises upper capacitors (115), which together with the upper induction coil (110) are connected to form an upper part oscillator circuit, and lower capacitors (125), which together with the lower induction coil (120) are connected to form a lower part oscillator circuit; and
   the upper longitudinal field inductor movement device (140) is constructed for moving the upper part oscillator circuit perpendicularly to the upper side of the metal strip and/or the lower longitudinal field inductor movement device (150) is constructed for moving the lower induction coil (120) perpendicularly to the lower side of the metal strip (200).
3. Rolling mill (400) according to one of the preceding claims, characterised in that
   the upper and lower induction coils (110, 120) of the longitudinal field inductor (100) or the housing thereof are of C-shaped construction for transverse movement of the longitudinal field inductor into and out of the line of the metal strip (200).
4. Rolling mill (400) according to any one of the preceding claims, characterised in that
   the upper and lower induction coils (110, 120) are each formed from a single winding or from a plurality of sub-windings connected in parallel and preferably crosswise.
5. Rolling mill according to claim 2, characterised in that
   the energy supply device (130) is constructed to operate the induction coils (110, 120) and the part oscillator circuits at current or voltage frequencies between 2 kHz and 30 kHz depending on the respective thickness of the metal strip.
6. Rolling mill according to claim 4 or 5, characterised in that
   the number of sub-Windings per induction coil is between 3 and 15 depending on the respective frequency.
7. Rolling mill (400) according to any one of the preceding claims, characterised by at least one transverse field inductor (180) which is operable additionally to the at least one longitudinal field inductor in the rolling mill.
8. Rolling mill (400) according to claim 7, characterised in that
   the transverse field inductor (180) comprises an upper transverse field inductor part oscillator circuit, which is associated with the upper side of the metal strip, with a capacitor (115) and a transverse field inductor coil (182) and a lower transverse field inductor part oscillator circuit, which is associated with the lower side of the metal strip, with a capacitor (125) and a transverse field inductor coil (184); and
   an upper transverse field inductor movement device (186) is provided for moving the upper transverse field inductor part oscillator circuit and a lower transverse field inductor movement device (188) is provided for moving the lower transverse field inductor part oscillator circuit, in each instance perpendicularly to the plane spanned by the metal strip (200).
9. Rolling mill (400) according to claim 8, characterised in that
   the upper and lower transverse field inductor movement devices (186, 188) and/or the upper and lower longitudinal field inductor movement devices (140, 150) form a constructional unit.
10. Rolling mill (400) according to claim 9, characterised in that
    the constructional unit comprises an inductor carriage (142) for moving the longitudinal field inductor and/or the transverse field inductor transversely to the longitudinal direction of the metal strip out of or into the line of the metal strip (200).
11. Rolling mill (400) according to claim 10, characterised in that
    a control device (187) is provided for activating the upper and/or lower transverse field inductor movement device (186, 188) or the inductor carriage (142).
12. Rolling mill (400) according to claim 11, characterised in that
    at least one contact sensor (198) is provided, for example in the form of a movement sensor or an acceleration transmitter, for detecting contact with the longitudinal field inductor (170) and/or the transverse field inductor (180) by the metal strip 200; and
    the control device (187) is constructed for activating the upper and/or lower longitudinal field inductor movement device (140, 150) and/or the upper and/or lower transverse field inductor movement device (186, 188) and/or the inductor carriage (142) in such a way that the longitudinal field inductor (100) and/or the transverse field inductor (180) when contact with the metal strip (200) takes place is or are opened in thickness direction and/or moved laterally out of the line.
13. Rolling mill (400) according to any one of the preceding claims 7 to 12, characterised in that
    a further longitudinal! field inductor (170) and/or the transverse field inductor (180) is or are switched between individual roll stands of the finishing rolling train.
14. Casting and rolling plant (500) with a casting machine (300) for producing a metal strip (200); characterised by
    a rolling mill (400) according to any one of the preceding claims 1 to 13 downstream of the casting machine in material flow direction.
15. Casting and rolling plant (500) according to claim 14, characterised in that
    a furnace (350) is connected between the casting machine (300) and the rolling train (400); and
    at least one further longitudinal field inductor (170) and/or at least one transverse field inductor (180) is or are connected between the furnace (350) and the roughing stand (420).
16. Casting and rolling plant (500) according to claim 15, characterised in that
    the divided at least one further longitudinal field inductor (170) adjustable in the thickness direction of the metal strip is connected between the furnace (350) and the roughing stand and the at least one transverse field inductor (180) is connected between individual ones of the finishing roll stands (440-n).

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