EP1314339B1 - Device for inductively heating metallic strips - Google Patents

Abstract

For optimum induction heating of metallic strips (1) of differing widths-particularly in the edge region-one multicoil transverse field inductor is positioned both above and below the strip (1) to be heated, whose coil axes are positioned vertically to the strip surface. In this case, each inductor comprises at least one inductor segment (2, 3; 7; 15; 17), which is constructed as a coil composite of multiple approximately rectangular coils (8, 9, 10; 16; 18) which extend predominantly transversely to the transport direction of the strip (1), the coils (8, 9, 10; 16; 18) having different, stepped transverse extensions and the coil having the highest transverse extension extending at most up to the lateral edges of the widest strip and the coil having the lowest transverse extension extending at most up to the lateral edges of the narrowest strip. Each inductor segment (2, 3; 7; 15; 17) is connected to a circuit for defined clocking of its coils (8, 9, 10; 16; 18), and each inductor segment (3; 7; 15; 17) below the strip is assigned an identical inductor segment (2; 7; 15; 17) above the strip. Through the device according to the present invention, overheating of the edges of metal strips (1) is prevented during induction heating-independently of the strip width.

Description

The invention relates to a device for inductive heating of metallic bands different width, each with a mehrspuligen Querfeldinduktor above and below the strip to be heated, the coil axes normal to the strip surface are arranged.

US-A-4 595 813 relates to a device for heating particularly long, thick-walled metal parts that are transported by rollers. With distance above the rollers are substantially transverse to the transport direction of the metal parts extending windings of successive in this direction inductors intended. The windings are edged by laminated parts of a magnetic circuit, the metal parts to be heated across and finally over below this good running rollers and support plates back to the respective inductor closes. This Overall, the device is set to a specific bandwidth. An adaptation to other bandwidths is not provided and hardly seems a la possible.

From DE 3928629 A1 discloses a device for inductive heating of flat metallic Well known, which has at least two inductors, which above and below the Metal good lying in pairs are assigned to each other. In this device, the Iron cores of at least one inductor in the transport direction of the material zigzag or wavy extending grooves, are inserted in the conductor. The adaptation of the inductor power to the respective bandwidth is done mainly by switching off selected Coil conductor. A major disadvantage of this known device is that a Optimized edge heating of the bands due to the winding coil conductor course not can be guaranteed because the conductors that lie in the edge region of the tape, a part the conductor is closer to the edge area of the band than the other part.

The object of the present invention is now to provide a device of the initially mentioned type so that the disadvantages of the known relevant device avoided be, so that with varying Gutbreiten over the respective width and in particular in the edge areas a uniform heating image with a simple construction of the inductors is reached.

The solution to this problem is inventively in a device of the aforementioned Art achieved in that for optimized edge heating of the bands, the inductors respectively consist of at least one inductor segment, as a coil assembly of several approximate rectangular coil is constructed, which is mainly transverse to the transport direction of the tape extend, wherein the coils have different, stepped transverse extensions and the Coil with the highest transverse extent is maximum up to the side edges of the widest Bandes extends and the coil with the lowest transverse extent up to the maximum Side edges of the narrowest band extends. In addition, each inductor segment with a Circuit connected to the defined timing of its coils and each inductor segment below of the band associated with an equal inductor segment above the band.

Operators of heating devices are able by means of the above device, as possible wide range of tapes - especially in terms of bandwidth, but also in Regarding the tape thickness and the material treat. Through the different, graded coils, which can be switched on, the energy consumption is optimized and a uniform heating image regardless of the width of the tape used achieved with maximum temperature fluctuations of ± 15 ° C. The usual heating temperatures are here for aluminum strips at about 400 ° C and brass bands at about 500-600 ° C. The defined timing of the coils selected for the respective bandwidth acts in particular Overheating the tape edges and thus prevents distortions or other Loss of quality; It can be within a coil assembly in addition to the clocking coils at least one coil also be switched on permanently. The coil conductors of the upper inductor segments are with the below the band exactly or approximately opposite coil conductors to build up a uniformly penetrating magnetic field in the same direction connected. The subdivision of the inductors in Induktorsegmente and the simple structure of the same By using approximately rectangular coils reduces the cost and the Susceptibility. Should it nevertheless come to a failure, then the affected Induktorsegment be replaced individually. A long downtime and high repair costs are thus avoided.

The device according to the invention can also be designed such that one inductor consists of several Induktorsegmenten consists, in the transport direction of the tape at a distance one behind the other are arranged. In lack of space in too short ovens, but the inductor segments can also be arranged directly behind one another. By a divided inductor gives the possibility To switch each segment individually and therefore separately contribute the required power. Thus, e.g. the segments at the beginning of the heating device that still Cold must heat well, bring a higher performance than the subsequent segments.

The device according to the invention can also be designed such that each inductor segment is a coil composite of three to eight coils. A coil assembly of three to eight coils per inductor segment is easy to design and manufacture. The in their transverse extension stepped coils have gradations of 4 to 10 cm on each side of the belt. This distance is chosen low enough to make a band whose edge is not satisfactory from him on The next coil is heated to optimally heat by clocking several coils.

The device according to the invention can also be designed so that the difference of the transverse extent a coil for transverse extension of the next smaller or larger coil at least 50 mm and a maximum of 200 mm. Such a graded coil composite allows the operator of a plant the treatment of different widths tapes. So he is not only set to a bandwidth, but can heat a variety of commercial tapes. If high demands are placed on the temperature accuracy, a coil assembly must be used be selected with small transverse extent differences. Does the operator want bands of a width treat, which does not optimally heated by the coil assembly already used in the oven can easily replace the segments in the device, e.g. by Segments with coils of smaller transverse extensions and / or transverse extension differences replace.

The device according to the invention may also be designed such that a coil composite a plurality of nested coils of different transverse extent is constructed, wherein the coils have a common axis.

The device according to the invention can also be designed such that the coils of a coil composite in the transport direction of the tape offset from each other are placed.

The above arrangements serve to optimize the temperature distribution, especially in the edge area of the band. There is the possibility within an inductor inductor segments install different design.

The device according to the invention can also be designed such that within a conductor groove the coil conductors are arranged one above the other or side by side. It is also possible that in a Leitemut only one coil conductor is located

The device according to the invention can also be designed such that per inductor segment at least two coils selected in response to the bandwidth so clocking are switched that only one coil is turned on. It may be e.g. 500 or 1000 switching operations per second can be achieved. By such a clocking of the coils Overheating of the band is prevented, especially in the edge region. It is also it is conceivable to let one coil on continuously while two other coils are clocking be switched. In borderline cases, it may also be useful to turn on only one coil. The Power is supplied by one or more inverters. The original 100% The power of the converter can then be connected via thyristors to the coils of an inductor segment be passed that e.g. a coil is constantly supplied with 70% of the total power while two more clocked coils allocate 10% and 20% of the power, respectively to get. Within an inductor, there is the possibility of the coils of each inductor segment to be individually timed.

The device according to the invention can also be designed such that the frequency and / or Duration of switching operations for each coil is variably adjustable. The use of different Frequencies and switching times for the coils can be uniform heating over the Promote bandwidth.

The device according to the invention can also be designed such that a scanner for Determination of the temperature profile over the bandwidth is provided. This can be done as fast as possible any unforeseen deviations of the temperature profile z. B. by defects Coils are determined.

The device according to the invention can also be designed such that a circuit for automatic timing of the selected coils under evaluation by the scanner determined temperature profile is provided. This will cause deviations from the intended Temperature value recorded immediately. By changing the timing can then be the desired Temperature profile can be reached again.

The device according to the invention can also be designed such that at least one upper Inductor with respect to the associated lower inductor segment transverse to the transport direction the band is arranged offset. Also in this way can the equalization the temperature profile can be optimized.

The device according to the invention can also be designed so that the offset between upper and associated lower inductor segment is variably adjustable.

The device according to the invention can also be designed such that at least some of the Inductor segments are stored interchangeable in the device. This can be at failure inductor segments are removed and replaced individually. This is true even if tapes should be treated, due to their width of the currently available in the oven Inductor segments can not be heated ideally. Here can by fast replacement the inductor segments of the furnace for other bandwidth ranges are converted. In addition is conceivable that with sufficiently long ovens inductor segments for heating narrower Bands are arranged in front of or behind inductor segments of broader bands in the oven. At a such embodiment, e.g. in the treatment of broad ligaments, the corresponding Inductor segments are turned on and the others are turned off. Thus, in one Oven tapes of two bandwidth ranges are treated.

The device according to the invention can be provided for, bands with a width of to heat at least 200 mm.

The device according to the invention may further be provided for taping with a Width of maximum 2000 mm to heat. These are usually in a furnace at Use of different width bands of the bandwidth range chosen such that the widest band to be treated is twice or 3 times as wide as the narrowest band, e.g. is the Width of the narrowest band 400 mm and that of the widest band 800 or 1200 mm.

Finally, it can be provided that the device for heating metallic bands Aluminum, steel, copper or brass is applied.

Fig. 1

eine schematische Ansicht zweier ohne Versatz einander zugeordneter Induktorsegmente mit zu erwärmendem Band,

Fig. 2

eine schematische Ansicht zweier mit Versatz einander zugeordneter Induktorsegmente mit zu erwärmendem Band,

Fig. 3

einen Schnitt durch Spulenleiternuten und Spulenleiter eines Induktorsegmentes,

Fig. 4

einen weiteren Schnitt durch Spulenleitemuten und Spulenleiter eines Induktorsegmentes,

Fig. 5

eine schematische Darstellung eines Induktorsegmentes mit elektrischen Anschlüssen, Scanner und zu erwärmendem Band,

Fig. 6

eine schematische Darstellung zweier in Transportrichtung hintereinander angeordneter Induktorsegmente,

Fig. 7

eine weitere schematische Darstellung zweier in Transportrichtung hintereinander angeordneter Induktorsegmente, und

Fig. 8

ein Diagramm für die Temperaturverteilung über die Bandbreite eines Aluminiumbandes bei unterschiedlicher Spulentaktung.

In the following part of the description embodiments of the device according to the invention will be described with reference to 8 drawings. It shows:

Fig. 1

a schematic view of two without offset each other associated inductor segments to be heated with tape,

Fig. 2

a schematic view of two mutually associated with offset inductor segments with tape to be heated,

Fig. 3

a section through Spulenleiternuten and coil conductor of an inductor segment,

Fig. 4

a further section through Spulenleitemuten and coil conductor of an inductor segment,

Fig. 5

a schematic representation of an inductor segment with electrical connections, scanner and belt to be heated,

Fig. 6

a schematic representation of two in the transport direction successively arranged inductor segments,

Fig. 7

a further schematic representation of two successively arranged in the transport direction Induktorsegmente, and

Fig. 8

a diagram for the temperature distribution over the bandwidth of an aluminum strip with different reel timing.

FIG. 1 shows a schematic view of a band 1 and above and below the band 1 mirror-symmetrically associated inductor segments 2,3. The inductor segments 2,3 have Coil conductor grooves 4 for not shown here coil conductor. The inductor segments 2,3 are switched in the same direction. The arrow indicates the transport direction of the belt 1. It can in each case a plurality of inductor segments 2,3 arranged in the transport direction of the belt 1 one behind the other his. In this case, identically or differently designed inductor segments can be provided his. With such an arrangement, metallic bands of different widths be annealed. Usual bandwidths are between 200 and 2000 mm. They are e.g. Aluminum, Steel or copper tapes treatable.

FIG. 2 shows a modification of the inductor segment construction known from FIG. The top Inductor segment 2 and the lower inductor segment 3 are offset transversely to the transport direction arranged to each other that the outer longitudinal edge regions 5 of the band 1 only from are each dominated by an inductor segment 2.3. This allows the temperature profile Slightly smoothen over the bandwidth and thus uniform. It can each a plurality of inductor segments 2,3 arranged in the transport direction of the belt 1 one behind the other his. In this case, all upper or lower Induktorsegmente 2,3 individually offset each other or individual inductor segments 2,3 may be arranged without dislocation. This transfer can be adjusted with little effort. In addition, individual inductor segments be removed individually for maintenance purposes.

FIG. 3 schematically shows a detail of an inductor segment 2, 3 with three coil conductor slots 4 shown. In the Spulenleitemuten 4 two coil conductors 6 are arranged one above the other. It is also conceivable to provide only one coil conductor per coil conductor groove. As Coil conductor can be used with VA pipe with a wall thickness of 0.1 - 0.2 mm.

FIG. 4 shows a modification of the schematic inductor segment cutout from FIG. 3. Here are the two coil conductors 6 in the two Spulenleitemuten 4 side by side, d. H. arranged parallel to a band, not shown here.

FIG. 5 shows a schematic plan view of an inductor segment 7, which serves as a coil composite of several is constructed approximately rectangular coils. The coils have a common Axle up. A band 1 to be guided along the inductor segment 7 is indicated. An arrow indicates the transport direction of the belt 1. Three coils 8,9,10 of the inductor segment 7 are with Current direction (arrows) shown. A common coil assembly has 3 to 8 coils. The coil 8 has the highest and the coil 10 has the smallest transverse extent. The difference of Transverse extension of a coil 8,9,10 to the transverse extent of the next smaller or larger Spool 8,9,10 is 100 mm. The transverse extent of the coil 8 is greater than that of the band. 1 The transverse extensions of the coils 9, 10 are smaller than those of the band 1. The coil 8 surrounds in this case the coil 9 and these two coils 8.9 turn the coil 10. Next smaller nested Coils are not shown. For the coils 8 and 9 is the electrical circuit located. For the sake of clarity, the coil 10 has been omitted. The Coil 8 or 9 is connected via a thyristor switch 11 or 12 to a common converter 13 connected. The thyristor switches 11, 12 serve for clocking the coils 8, 9. The frequency and / or duration of the switching operations is variably adjustable for each coil 8.9. In transport direction of the band 1 behind the inductor segment 7 is a scanner 14 for determining the temperature profile arranged over the width of the band 1. Should the tape 1 be e.g. because of a Spool defect heated irregularly, so this error is detected immediately and can automatically e.g. by another clocking involving other coils or by a Offset the inductor segment 7 are compensated until the repair of the coil defect. It is conceivable to work with two or more inverters to be variable in power and timing to be. The plant performance may e.g. 1050kW and the frequency 500 - 1000 Hz.

Figure 6 shows schematically two in the transport direction (arrow) of a belt, not shown successively arranged inductor segments 15. Both inductor segments 15 are similar and executed without offset to each other. However, it is also conceivable two or more different types Induktorsegmente 15 with or without offset to arrange one behind the other. A common equipment could e.g. above and below the belt 1 in the transport direction of Bandes 1 each seven inductor segments with a total length of 7 * 360mm = 2520 mm include. The five coils 16 are arranged for each inductor segment 15 such that the coils 16 are offset with decreasing transverse extent in the transport direction of the tape. In addition, a displacement of one or more of the coils 16 to the band is conceivable. The Power can be introduced into the inductor segments 15 individually. It is conceivable that all or individual of the inductor segments 15 of an inductor are mounted interchangeably.

FIG. 7 shows schematically a modification of the coil arrangement of the two inductor segments from FIG. 6. Here, the two inductor segments 17 are the same and without offset from one another educated. In addition, the inductor segments 17 without spacing behind each other in the transport direction a not dargstellten tape arranged. But it is also conceivable, the inductor segments 17 to arrange with distance. The five coils 18 are nested in each other, that smaller coils are surrounded by the larger coils. Of course is also a larger or smaller number than five coils conceivable. Also, an offset is individual Coils 18 to the tape, not shown here conceivable.

Such inductor segments 17 may be e.g. for heating sheets with belt widths of 1200 to 1800 mm are used. If narrower sheets are to be heated, then so For example, the inductor segments can be easily removed from the device and narrower inductor segments be inserted into the device.

FIG. 8 shows in diagram form a temperature distribution over the bandwidth of one at 545 ° C. annealed aluminum strip 1 mm high and 1300 mm wide. It is due to the symmetrical Temperature distribution over the strip transverse extent only half a bandwidth shown. The transport speed of the belt is 30 m per minute.

Curve A shows a temperature profile that is achieved when only coils of an inductor segment be turned on, the transverse extent is significantly smaller than the transverse extent of the band. It can also be turned on only a single coil. That also the turned on coil with the highest transverse extent has in such a case a clear shorter, e.g. 10 cm shorter transverse extent than the transverse extent of the band. Such Coil represents coil 10 in Figure 5. The band is largely homogeneous over the bandwidth heated. However, the lateral band edges are about 50 ° C lower than the band center area annealed.

The curve B shows the temperature profile that is achieved when only coils of an inductor segment be turned on, the transverse extent of which is smaller than the transverse extent of the heating belt is, but with the switched coil with the highest transverse extent approximately the transverse extent of the band, e.g. a shortened by 3cm transverse extent, has. Such a coil represents coil 9 in Figure 5. The coil 9 is the next larger coil after the coil 10. The band is heated largely homogeneously over the bandwidth. Indeed The band edges show an abrupt rise in temperature of 80 ° C compared to rest of the band. As a result, significant quality losses, e.g. in the form of dislocations arise in the band.

Curve C shows an approximately ideal temperature profile over the bandwidth. This will be done Achieved that only one coil or more coils, which has a much smaller transverse extent as the transverse extent of the band, are constantly turned on. This then results in a heating according to the course of the curve A. In addition, a coil, which has approximately the transverse extent of the band, e.g. the coil 9 of Figure 5, temporarily switched on. Coils having a larger transverse extent than the band usually become not switched on, as they would cause a significant overheating of the edge zone. It is conceivable, the two coils 9,10 of Figure 5, whose transverse extensions of the transverse extent closest to the band, switching alternately, while none, one or more shorter coils (not shown in FIG. 5) are permanently switched on. In this case, e.g. the shorter coil 10 has twice as long cycle times as the larger one Coil 9. Similarly, three or more coils can be switched clocking. It can the coils of the opposing and / or successively arranged Induktorsegmente be clocked the same or different. By such optimized clocking are maximum temperature differences across the bandwidth of plus / minus 5 to 10 ° C and thus uniform band qualities can be realized. Optionally, at certain bandwidths also be dispensed with a clock if, due to a good ratio bandwidth / transverse extent Even without clocking the desired temperature distribution can be achieved can.

LIST OF REFERENCE NUMBERS

1.

tape

Second

inductor

Third

inductor

4th

Spulenleiternut

5th

Strip longitudinal edge region

6th

coil conductor

7th

inductor

8th.

Kitchen sink

9th

Kitchen sink

10th

Kitchen sink

11th

thyristor

12th

thyristor

13th

inverter

14th

scanner

15th

inductor

16th

Kitchen sink

17th

inductor

18th

Kitchen sink

A

Diagram "superheated band edge area"

B

Diagram curve "supercooled band edge area"

C

Diagram curve "ideal band (edge) warming"

Claims (17)

1. A device for the inductive heating of metal strip (1) of various widths, with a multi-coil cross field inductor each above and below the strip (1) to be heated up, with the coil axes of the strip to be heated up being arranged in the normal way in relation to the strip surface,
   characterised in that
   for optimum heating of the edge of the strip (1), each of the inductors comprises at least one inductor segment (2, 3; 7; 15; 17); which is designed as a combination of coils of several approximately rectangular coils (8, 9, 10; 16; 18) which predominantly extend across the direction of transport of the strip (1), wherein the transverse widths of the coils (8, 9, 10; 16; 18) are differently stepped and the coil with the largest transverse width extends at most to the lateral edges of the widest strip, and the coil with the smallest transverse width extends at most to the lateral edges of the narrowest strip;
   in that each inductor segment (2, 3; 7; 15; 17) comprises a circuit for defined cycling of its coils (8, 9, 10; 16; 18); and
   in that each inductor segment (3; 7; 15; 17) below the strip (1) is associated with an identical inductor segment (2; 7; 15; 17) above the strip (1).
2. The device according to claim 1, characterised in that an inductor consists of several inductor segments (2, 3; 7; 15; 17) which in the direction of transport of the strip (1) are arranged spaced apart, one behind the other.
3. The device according to claim 1 or 2, characterised in that each inductor segment (2, 3; 7; 15; 17) is a combination of coils comprising three to eight coils (8, 9, 10; 16; 18).
4. The device according to any one of claims 1 to 3, characterised in that the difference between the transverse width of a coil (8, 9, 10; 16; 18) and the transverse width of the next-smaller or next-bigger coil (8, 9, 10; 16; 18) is at least 50 mm and at most 200 mm.
5. The device according to any one of claims 1 to 4, characterised in that a combination of coils is designed of several coils (8, 9, 10; 18), nestled inside one another, of different transverse widths, wherein the coils (8, 9, 10; 18) have a common axis.
6. The device according to any one of claims 1 to 5, characterised in that the coils (16) of a combination of coils are placed so as to be offset in relation to each other in the direction of transport of the strip (1).
7. The device according to any one of claims 1 to 6, characterised in that within a conductor groove (4), the coil conductors (6) are arranged above each other or beside each other.
8. The device according to any one of claims 1 to 7, characterised in that for each inductor segment (2, 3; 7; 15; 17) at least two coils (8, 9, 10; 16; 18), which have been selected depending on the strip width, are switched to be cycling such that only one coil (8, 9, 10; 16; 18) is switched on at a given time.
9. The device according to claim 8, characterised in that the frequency and/or duration of the switching processes can be variably set for each coil (8, 9, 10; 16; 18).
10. The device according to any one of claims 1 to 9, characterised in that a scanner (14) for determining the temperature profile across the strip width is provided.
11. The device according to 10, characterised in that a circuit for automatic cycling of the selected coils (8, 9, 10; 16; 18) is provided which evaluates the temperature profile determined by the scanner (14).
12. The device according to any one of claims 1 to 11, characterised in that at least one upper inductor segment (2; 7; 15; 17) is arranged so as to be offset in relation to the associated lower inductor segment (3; 7; 15; 17) across the direction of transport of the strip (1).
13. The device according to claim 12, characterised in that the offset between the upper and the associated lower inductor segment (2, 3; 7; 15; 17) is adjustable.
14. The device according to any one of claims 1 to 13, characterised in that at least some of the inductor segments (2, 3; 7; 15; 17) are held in the device so as to be exchangeable.
15. The application according to any one of claims 1 to 14, characterised in that strip (1) with a width of at least 200 mm is heated up.
16. The application according to any one of claims 1 to 15, characterised in that strip (1) with a width not exceeding 2000 mm is heated up.
17. The application of the device according to any one of claims 1 to 16, characterised in that metal strip (1) made of aluminium, steel, copper or brass is heated up.

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