EP2496728B1 - Device for coating a metal strip and method therefor - Google Patents

Description

The invention relates to a device for coating a metallic strip with a coating material comprising a coating container filled with a liquid coating material through which or from which the coated strip is discharged vertically upwards, wherein above the coating container, a scraper for stripping still liquid coating material is arranged from the strip surface, wherein above the wiping nozzle, an electromagnetic device for stabilizing the position of the tape is arranged in a central position, wherein the device comprises at least two magnets arranged on both sides of the metal strip at the same height. Furthermore, the invention relates to a method for coating a metallic strip with a coating material.

From the publication DE 10 2007 045202 A1 a device for strip edge stabilization of a belt is known which has at least one sensor for detecting the position of the at least one band edge and at least one adjusting device is provided, with which a means for band edge stabilization can be positioned transversely to the band depending on the band edge position.

Devices for stabilizing the run of a metal strip are also known from the documents DE 10 2006 052000 A1 and DE 10 2005 060058 A1 known. In order to adjust and stabilize the distance of the belt in the transverse direction between the blow-off nozzles, a belt stabilizing device is provided.

A device of this type and a corresponding method are known. The DE 10 2008 039 244 A1 shows a device for hot dip coating, in which the metal strip is passed through the coating bath and discharged from this vertically upwards. Above the coating container, a wiping nozzle is arranged, with the excess coating material is blown off the belt surface. Above the wiping nozzle, a band stabilization is arranged at a defined distance, with which the band is to be held centrally in the center plane of the plant.

A similar solution is from the WO 02/14574 A1 known. Details of hot-dip coating processes are also shown by the WO 01/11101 A1 , the EP 0 659 897 B1 , the EP 0 854 940 B1 and the JP 11006046 ,

In hot-dip coating plants, especially in hot-dip galvanizing plants, different requirements are imposed on the strip layer and the strip run. Particularly in the area of wiping nozzles, non-contact systems, the so-called electromagnetic band stabilization systems, are intended to reduce band vibrations and influence the band shape.

In systems with a stripper nozzle downstream inductive heating system (Galvannealer) guide rollers are additionally used above the wiper prior to the heating device, which ensure a smooth tape between the heating coils and to avoid defects both on the system and on the tape by contact of the tape with these ,

Likewise, a stable central belt run in systems with and without downstream heating inductors is of great importance for the strip cooling devices following the wiping nozzle, in order to achieve a uniform cooling effect. Again, it is important to avoid damage to the system and the belt surface.

Various systems have become known which exert additional forces on the steel strip without contact, namely electromagnetically, in order to minimize band movements in the form of vibrations. Furthermore, with these systems, the band shape can be influenced transversely to the transport direction.

The belt position normal to the belt surface is measured in the belt stabilization system by means of displacement sensors and regulated in a closed loop. In this case, further measuring devices can be used within the downstream devices as additional signals for the band position control.

As a disadvantage, the following has been found: The position of the belt stabilization is defined by design and concentrated in the previously known solutions mostly on a spatial proximity to the scraper. Thus arises dependent from design a distance of the belt stabilization magnets from the nozzle lip of the wiper (air outlet from the nozzle).

As a result, the distance to the downstream facilities, such. B. to the heating inductors or to the downstream strip cooling, very large. This results in no or only a minimal effect of the belt stabilization magnets on the local belt movement and consequently no possibility of influencing the belt stability in the region spaced from the wiper.

However, if the belt stabilization magnets are installed directly in front of the heating inductor or the belt cooling, a significantly reduced effect on the belt centering in the area of the scraping nozzle results accordingly.

In the case of the previously known systems, therefore, there is always only one selected position, which is usually matched to the effect in the area of the wiping nozzle, ie. H. The band-stabilizing magnets are usually arranged in the region of the wiping nozzle.

However, this means that the requirements for a modern strip galvanizing line can not be met or only partially met.

The invention is in the light of these disadvantages, the object of developing a device for coating a metallic strip with a coating material and a corresponding method so that it can be responded to the different demands on the tape guide in an improved and simpler manner. Accordingly, the quality of the hot dip coating, in particular the hot dip galvanizing, should be increased.

This object of the invention is achieved by the device technology by the subject of claim 1.

The means for adjusting the vertical distance may include at least one hydraulic or pneumatic actuator; they may also comprise at least one mechanical actuator, in particular a spindle-nut system.

According to a first embodiment of the invention, the means for adjusting the vertical distance may comprise at least one lifting element, which is directly or indirectly connected to the wiper. The wiping nozzle can have a frame structure or be connected to such, on which the at least one lifting element is arranged.

A heating element for heating the strip can be arranged above the wiping nozzle in order to be able to carry out a so-called galvannealing process. The heating element is preferably formed as an inductive element. The means for adjusting the vertical position are preferably formed for adjusting the vertical distance of the magnets in the entire region of the height extension between the wiper and the heating element.

Above the heating element, a cooling section can furthermore be arranged. Between the heating element and the cooling section, a holding furnace can be arranged.

The object of the invention is procedurally achieved by the method according to claim 10.

The claimed method of coating a metallic strip with a coating material wherein the strip is passed through liquid coating material contained in a coating container and then discharged vertically upwardly from the coating container, wherein above the coating container still liquid coating material is removed by a wiping nozzle of the Strip surface is stripped and wherein above the wiping the tape by means of an electromagnetic device stabilized to stabilize the position of the tape in a central position, wherein the device comprises two magnets disposed on both sides of the belt at the same height, according to the invention is characterized in that the vertical distance of the magnets is adjusted by the wiper according to a predetermined value, wherein Setting the distance means for adjusting the vertical distance to be operated by a controller.

The magnets are preferably kept centered in the center position when setting the vertical distance.

The essence of the invention thus depends on the fact that the position of the belt stabilization magnets is not stationary, but can be adapted to the respective requirements by means of a suitable lifting device. In this case, the aligned (centered) and optimized position of the belt stabilization magnets to the continuous steel belt - in the direction normal to the belt - by mechanical coupling of the belt stabilization magnets with the wiper remains always exist.

From physical considerations it follows that the belt stabilization system must be positioned as close as possible to the respective device or effective point for optimum function and thus for the purpose of reducing the belt movements (principle of St. Vernant). This is, for example, for optimizing the coating with liquid metal a position as close as possible to the wiping, wherein for a central and quiet tape within the Nacherwärmungseinrichtung the position of the non-contact tape stabilization should be selected as close to this device. Thus, it makes sense to be able to approach by means of a suitable auxiliary device both positions (once close to the scraper and once near the heating device) without loss of stabilization function. Furthermore, other positions can be approached, which allow influencing both parts of the system (scraper and heating device) with the belt stabilization.

By means of a lifting device according to the invention, therefore, the vertical position of the belt stabilizing magnets, which are part of a belt stabilizing unit, can be flexibly adjusted to a desired value. This is done depending on the operating state or the desired non-contact Bandlagenbeeinflussung. The positioning preferably takes place between the wiping nozzle and the downstream in the conveying direction of the belt heating inductors for galvannealing operation or a downstream strip cooling.

The actuating means for the height adjustment of the magnets always remain centered to the scraper, since they are mechanically coupled thereto.

Thus, the invention enables a variable, selectively adjustable position of the belt stabilizing magnets above the scraper in a hot-dip galvanizing plant.

Accordingly, the vertical adjustment of the belt stabilizing magnets relative to the scraper nozzle allows any position to obtain optimum operation between the extreme positions directly on the scraper nozzle and directly in front of the downstream heating elements or before the belt cooling.

In combined applications, where both tape position control in the wiper nozzle and in the downstream equipment is important, the effects on the respective equipment are determined by means of a mathematical model taking into account the stress distribution in the tape; Accordingly, a vertical position of the belt stabilization magnets is set, which is optimized for the application.

Fig. 1

schematisch eine Schmelztauchbeschichtungsanlage gemäß einer ersten Ausführungsform der Erfindung,

Fig. 2

in der Darstellung von Fig. 1 eine alternative Ausführungsform der Erfindung,

Fig. 3

in perspektivischer Darstellung einen Halterahmen für die Abstreifdüse der Schmelztauchbeschichtungsanlage, auf dem Magnete für die Bandstabilisierung höhenveränderlich angeordnet sind, und

Fig. 4

in perspektivischer Darstellung die Magnete für die Bandstabilisierung, angeordnet an einer Höhenverstelleinrichtung.

In the drawings, embodiments of the invention are shown. Show it:

Fig. 1

1 is a schematic representation of a hot-dip coating installation according to a first embodiment of the invention,

Fig. 2

in the presentation of Fig. 1 an alternative embodiment of the invention,

Fig. 3

a perspective view of a support frame for the Abstreifdüse the hot dip coating system, are arranged on the magnets for the belt stabilization height, and

Fig. 4

in a perspective view, the magnets for the belt stabilization, arranged on a height adjustment.

In Fig. 1 is sketched a hot-dip coating plant, which serves for coating a strip 1 with a coating metal. The tape 1 is introduced in the embodiment in a known manner in a coating container 2, in which liquid coating material is contained. In the present case, a deflection of the belt 1 in the vertical direction V by means of a deflection roller 14 is made. Of course, the CVGL method can also be used in the same way, in which the band 1 enters the coating container 2 vertically from below and the bottom opening is sealed by means of an electromagnetic shutter.

After the coated tape 1 has exited vertically upward from the coating container 2, excess coating metal is blown off by a wiping nozzle 3. Above the wiping nozzle 3 there is a device 4 for stabilizing the band 1. This device 4 has as its core two electro-magnets 6 arranged on both sides of the belt 1. With these devices it is achieved that the belt is deliberately subjected to magnetic forces such that it is held in a symmetrical center position 5 of the device.

It is essential that means 7 are provided with which the vertical distance H of the magnets 6 can be set by the wiper 3 targeted. This is indicated in Fig. 1 with the double arrows next to the magnets 6 and in that the magnets 6 are sketched once (in a middle position) with solid lines and in two further alternative positions with dashed lines, namely in a lower position near the wiping nozzle 3 and in an upper position at the upper end of the movement, which can be accomplished with the means 7.

The distance of the magnets 6 from the upper end of the wiper 3 is indicated by H and indicates how far the magnets 6 are lifted by the means 7.

Above the device 4 for stabilization is in Fig. 1 a cooling section 11 is provided for the band 1. Above the cooling section 11, the band 1 is deflected by a deflection roller 13 in the horizontal.

In Fig. 2 is an alternative solution outlined here compared with Fig. 1 an inductive heating device 10 is provided above the belt stabilization 4, with a Galvannealing process can be performed in a conventional manner. Between the heating element 10 and the cooling section 11 is still a holding furnace 12th

An idea of the structural design of the proposed device goes out Fig. 3 out. Here it can be seen that the wiping nozzle 3 is arranged on a frame structure 9, on which four lifting elements 8 are fastened, with which the magnets 6 can be raised or lowered relative to the wiping nozzle 3.

Further details of the structural design go out Fig. 4 out. Here you can see how four lifting elements 8 - in the present case designed as mechanical actuators in the form of spindle-nut systems - are used to the Move magnets 6 in the vertical direction V or adjust. The wiping nozzles 3 are not shown here; they are in the lower part of the illustration according to Fig. 4 ,

If strip layer changes occur which lead to a readjustment of the stripper nozzle, the position of the strip stabilization is also tracked by the mechanical coupling of the strip stabilization magnets.

• Für den optimalen Galvannealing-Betrieb (GA-Betrieb) wird die Bandstabilisierung 4 und namentlich die Magnete 6 mittels der Mittel 7 (Hebevorrichtung) direkt unterhalb der induktiven Heizelemente 10 positioniert. Da die Beschichtungsdicke für GA-Produkte sehr dünn ist (maximal 90 g/m²) und daher durch die Bandstabilisierungswirkung nur geringe Verbesserungen im Schichtaufbau erzielt werden können, wird der Schwerpunkt der Stabilisierungswirkung auf den Bandlauf im Heizelement 10 (GA-Induktor) und damit auf die Qualität der GA-Beschichtung gelegt. Durch die mechanische Kopplung zur Abstreifdüse 3 stehen die Abstreifdüse 3 und die Magnete 6 der Bandstabilisierung jederzeit zentriert zum Band 1.

The continuous height adjustment of the magnets 6 of the belt stabilization allows the following procedure:

• For optimum galvannealing operation (GA operation), the belt stabilizer 4 and, in particular, the magnets 6 are positioned directly below the inductive heating elements 10 by means 7 (lifting device). Since the coating thickness for GA products is very thin (maximum 90 g / m ² ) and therefore only slight improvements in the layer structure can be achieved by the band stabilization effect, the focus of the stabilizing effect on the tape run in the heating element 10 (GA inductor) and thus placed on the quality of the GA coating. Due to the mechanical coupling to the wiping nozzle 3, the wiping nozzle 3 and the magnets 6 of the belt stabilization are always centered to the belt 1.

The effect of band stabilization in the region of the wiper nozzle 3 is reduced in this case, but it does not go away because of the optimal position calculation by a mathematical model used here. The magnets 6 are positioned closer to the heating elements 10 (GA inductors) than to the wiping nozzle 3, but taking into account the physical action in both directions.

For other coating products, the focus of the stabilizing effect is on minimizing tape movement within the wiping die 3. For this purpose, the position of the magnets 6 of the belt stabilization in the region of the wiping nozzle 3 is selected.

The guide rollers in front of the heating element, which are used in previously known systems to stabilize the belt, are no longer necessary, since now the stabilizing effect can be influenced in a targeted manner in the entire height range between the wiper and the heating element.

The means 7 (lifting device) also advantageously allow a manual cleaning of the wiper 3 during operation. The belt stabilization or the magnets 6 are moved to an elevated position, but without losing the stabilizing effect. This is not possible with previously known systems. Thus, the maintenance personnel obtains free access to the scraper nozzle 3 and therefore can clean the nozzle lips manually. This requirement is met with every hot dip galvanizing line.

The positioning of the belt stabilizing magnets 6 is as explained with a device which may have two guides, holders and corresponding clamping devices which cause the tensioning of the system and thus the parallel alignment of the belt stabilization (the magnets 6) to the belt or wiper support system. This band-stabilizing position changing device is fixedly mounted on the scraping nozzle 3, which includes a frame structure with alignment members.

The principle is thus a frame construction, which in turn is firmly connected to the basic frame construction of the wiper nozzle 3. This is done with the alignment of the wiper 3 to the band 1 also always a synchronous alignment of the magnets 6 of the band stabilization to the band. 1

LIST OF REFERENCE NUMBERS

1

tape

2

coating tank

3

wiping

4

Device for stabilization

5

Symmetry

6

magnet

7

Means for adjusting the vertical position

8th

lifting

9

frame structure

10

heating element

11

cooling section

12

holding furnace

13

idler pulley

14

idler pulley

V

vertical direction

H

distance

Claims (11)

1. A device for coating a metal strip (1) with a coating material which has a coating vessel (2) filled with a liquid coating material, through which or from which the coated strip (1) is discharged vertically (V) upwards, wherein a stripping nozzle (3) for wiping coating material that is still wet from the strip surface is arranged above the coating vessel (2), wherein an electromagnetic device (4) for stabilizing the position of the strip (1) in a central position (5) is arranged above the stripping nozzle (3) and wherein the mechanism (4) comprises at least two magnets (6) arranged at the same height on both sides of the metal strip (1) and a control mechanism for positioning the magnets (6),
   characterized by
   means (7) for the flexible adjustment of the vertical distance (H) of the magnets (6) from the stripping nozzle (3), wherein the means (7) comprise at least one hydraulic, pneumatic or mechanical actuator; and a control mechanism for actuating the means (7).
2. The device according to claim 1,
   characterized in that
   the means (7) for adjusting the vertical distance (H) comprise at least one lifting element (8) which is connected directly or indirectly to the stripping nozzle (3).
3. The device according to claim 2,
   characterized in that
   that the stripping nozzle (3) has a frame structure (9) on which the at least one lifting element (8) is arranged.
4. The device according to one of claims 1 to 3,
   characterized in that
   a heating element (10) for heating the strip (1) is arranged above the stripping nozzle (3).
5. The device according to claim 4,
   characterized in that
   the heating element (10) is designed as an inductive element.
6. The device according to claim 4 or 5,
   characterized in that
   the means (7) are designed to adjust the vertical distance (H) of the magnets (6) over the entire region of the height extent between the stripping nozzle (3) and the heating element (10).
7. The device according to one of claims 4 to 6,
   characterized in that
   a cooling section (11) is arranged above the heating element (10).
8. The device according to claim 7,
   characterized in that
   a holding furnace (12) is arranged between the heating element (10) and cooling section (11).
9. The device according to one of claims 1 to 8,
   characterized in that
   the mechanical actuator is configured in the form of a spindle-nut system.
10. A method for coating a metal strip (1) with a coating material in which the strip (1) is passed through liquid coating material which is located in a coating vessel (2) and then discharged vertically (V) upwards out of the coating vessel (2), wherein coating material that is still wet is wiped from the strip surface above the coating vessel (2) by a stripping nozzle (3) and wherein the strip (1) is stabilized above the stripping nozzle (3) by means of an electromagnetic mechanism (4) for stabilizing the position of the strip (1) in a central position (5), wherein the mechanism comprises at least two magnets (6) arranged on both sides of the strip (1) at the same height and
    the vertical distance (H) of the magnets (6) from the stripping nozzle (3) is set according to a predefined value,
    characterized in that
    the means (7) comprising a hydraulic, pneumatic or mechanical actuator for the flexible adjustment of the vertical distance (H) of the magnets (6) from the stripping nozzle (3) are actuated by a control mechanism.
11. The method according to claim 10,
    characterized in that
    the magnets (6) are constantly held centred in the central position (5) during adjustment of the vertical height (H).

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