EP1915469B1 - Apparatus for hot-dip coating a metal bar - Google Patents

Abstract

The invention relates to an apparatus for hot-dip coating a metal bar (1), especially a steel strip, in which the metal bar (1) is vertically guided through a vessel (3) accommodating the melted coating metal (2) and through a conduit (4) that is mounted upstream thereof. At least two inductors (5) generating an electromagnetic field are disposed in the vessel (3) in the region of the conduit (4) on both sides of the metal bar (1) so as to retain the coating metal (2) in the vessel (3) while an increased volume of the coating metal (2) is provided in some sections. In order to kill the coating bath, the increased volume is located in the area of the magnetic field of the inductors (5).

Description

The invention relates to a device for hot dip coating a metal strand, in particular a steel strip, in which the metal strand is passed vertically through a container receiving the molten coating metal and through an upstream guide channel, in the region on both sides of the metal rod at least two inductors for generating an electromagnetic field for retention of the coating metal are arranged in the container.

Such a device is known from German Offenlegungsschrift DE 103 12 939 A1 known.

Such a device is also the subject of the earlier German patent application ( 103 30 656.0 from 08.07.2004). The local, underlying the preamble invention invention has for its object to provide a device for hot dip coating of a metal strand, the certain disadvantages of the prior art mentioned therein, in particular the EP 0 673 444 B1 , of the WO 96/03533 and the JP 5086446 , overcomes. This is to ensure that the immersion bath remains quiet when using an electromagnetic shutter, whereby the quality of the coating is to be increased.

Because it has been found that the bath surface of the coating metal is relatively restless, which is attributed to the electromagnetic forces through the magnetic closure. However, a prerequisite for an accurate adjustment of the coating thickness is a quiet metal bath surface.

For this purpose, it is provided in the older proposal, inter alia, to arrange either between the guide channel and the bottom of the container or in the guide channel itself a cross-sectional widening, in which the coating metal can penetrate from above. Accordingly, in the last-mentioned embodiment, this cross-sectional widening leads to an increased volume of the coating metal in the region of the guide channel, and forms the starting point of the present invention.

The invention has for its object to provide further measures that cause the immersion bath when using an electromagnetic shutter remains calm, thereby increasing the quality of the coating.

This object is solved by the subject matter of the new patent claim 1. This is characterized in that in the region of the upper half to the upper third of the inductors and their magnetic field, an increased volume of the coating metal is present and that the increased volume is formed by a lateral bulging of the walls of the guide channel.

In this embodiment, retrofitting by replacing the guide channel with little effort is possible.

The above object is further achieved by the subject matter of claim 2. This is characterized in that in the region of the upper half to the upper third of the inductors and their magnetic field, an enlarged volume of the coating metal is present and that the enlarged volume is formed by a lateral feed of additional coating metal.

Here, therefore, an additionally introduced into the guide channel volume flow of coating metal for, possibly also additional, volume increase.

In the earlier patent application, the increased volume of the coating metal is either in the bottom region of the container or in the guide channel, but always above the inductors. Thus, the increased volume there is at least predominantly outside the effective magnetic field of the inductors. In the invention, however, the increased volume is targeted in the range of the magnetic field of the inductors, which results in that the area of increased volume is exposed to the influence of the magnetic field.

In continuation of the fourth embodiment, an effective increase in volume is achieved in that the lateral feed takes place by at least two tubes, which preferably occur on the narrow sides of the rectangular guide channel.

With the proposed measures it is achieved that the surface of the coating metal bath within the container remains relatively quiet, so that a high quality of the dip coating is achieved.

In the drawings, embodiments of the invention are shown.

Fig. 1

in schematischer Darstellung den unteren Teil einer Vorrichtung zur Schmelztauchbeschichtung, mit einem durch diese hindurch geführ- ten Metallstrang im mittigen Schnitt längs des Metallstrangs, wobei lediglich der Bereich des Bodens des Behälters für das Beschich- tungsmetall und der sich nach unten anschließende Führungskanal mit den Induktoren dargestellt ist, mit einer ersten Ausgestaltung der Erfindung in Form einer trichterförmigen Erweiterung des Führungs- kanals,

Fig. 2

eine zweite Ausgestaltung der Erfindung, entsprechend der Fig. 1, in Form einer stufenförmigen seitlichen Erweiterung des Führungska- nals,

Fig. 3

eine dritte Ausgestaltung der Erfindung, entsprechend der Fig. 1, mit einer Unterbrechungswand,

Fig. 4

eine erste Ausbildung des Querschnitts der Unterbrechungswand in Fig. 3,

Fig. 5

eine zweite Ausbildung des Querschnitts der Unterbrechungswand in Fig. 3,

Fig. 6

eine dritte Ausbildung des Querschnitts der Unterbrechungswand in Fig. 3,

Fig. 7

eine vierte Ausbildung des Querschnitts der Unterbrechungswand in Fig. 3,

Fig. 8

eine vierte Ausgestaltung der Erfindung, entsprechend der Fig. 1, jedoch im mittigen Schnitt quer zum Metallstrang, in Form einer Aus- bauchung, und

Fig. 9

eine fünfte Ausgestaltung der Erfindung, entsprechend der Fig. 1, jedoch in Form einer seitlichen Zuführung von Beschichtungsmetall in den Führungskanal.

Show it:

Fig. 1

a schematic representation of the lower part of a device for hot dip coating, with a guided through this metal strand in the central section along the metal strand, wherein only the region of the bottom of the container for the coating metal and the downwardly adjoining guide channel with the inductors is shown, with a first embodiment of the invention in the form of a funnel-shaped extension of the guide channel,

Fig. 2

a second embodiment of the invention, according to the Fig. 1 , in the form of a step-shaped lateral extension of the guide channel,

Fig. 3

a third embodiment of the invention, according to the Fig. 1 , with a break wall,

Fig. 4

a first embodiment of the cross section of the interruption wall in Fig. 3 .

Fig. 5

a second embodiment of the cross section of the interruption wall in Fig. 3 .

Fig. 6

a third embodiment of the cross section of the interruption wall in Fig. 3 .

Fig. 7

a fourth embodiment of the cross section of the interruption wall in Fig. 3 .

Fig. 8

A fourth embodiment of the invention, according to the Fig. 1 , but in the middle section across the metal strand, in the form of a bulge, and

Fig. 9

A fifth embodiment of the invention, according to the Fig. 1 but in the form of a lateral feed of coating metal into the guide channel.

At the in Fig. 1 only partially shown device is to be coated metal strand 1 in the form of a steel strip vertically through a molten metal coating 2 preferably upwards, in the conveying direction R, deducted. The coating metal 2 may in particular be zinc or an aluminum and is accommodated in a suitable, only indicated container 3 with exclusion of air.

In the bottom 3a of the container. 3, a passage opening 3b for the metal strand 1 is arranged. At the bottom 3a is connected to the passage opening 3b down a guide channel 4 in the form of a narrow in principle, rectangular tube. The band-shaped metal strand 1 is guided with all-round play through the guide channel 4, wherein the free cross-section of the guide channel 4 is filled in the form of an annular gap RS over a certain vertical distance with coating metal 2, so that the metal strand 1 in the upper portion 4a of the guide channel 4th surrounded by coating metal 2. The Coating metal 2 thus represents in the upper region 4a a kind of liquid ring seal, which fills the annular gap RS down to U.

To ensure the sealing effect of this ring seal, d. H. for permanently secure sealing of the annular gap RS in the guide channel 4 down inductors 5 are arranged on both sides of the longitudinal walls 6 of the guide channel 4. The inductors 5 generate a strong magnetic field in the region of the guide channel 4, which counteracts the gravity of the annular coating metal 2 there so far that the coating metal 2 can not run down from the guide channel 4, but remains substantially stationary at point U.

That in the Fig. 1 shown game, and thus the annular gap RS are the clear representation of greatly enlarged and not shown to scale. The volume of the annular coating metal 2 acting as a ring seal in the upper region 4a of the guide channel 4 can actually be kept very small.

The nature of the inductors 5 and their mode of action, as well as the use of correction coils, not shown, and other features of the device are described in detail in said earlier German patent application.

In order to ensure a calming of the bath surface in the container, in the region of the magnetic field of the inductors 5, in particular immediately adjacent to the inductors 5, an enlarged volume of the coating metal 2 is arranged in the guide channel 4.

This is in the in Fig. 1 illustrated first embodiment of the invention, the upper, in the passage opening 3b of the bottom 3a opening area 4a of the guide channel 4 funnel-shaped expanded by the lower width B1 of the longitudinal walls 6 increases upwards to the width B2. The resulting Inclination of the narrow transverse walls 7 at an acute angle to the vertical is about 1 to 15 degrees.

The widening of the longitudinal walls 6 of the guide channel 4, and thus the area 4 a, begins at about half height H / 2 height H of the inductors 5 and extends beyond the height H, then into the longitudinal sides of the rectangular passage opening 3 b in To pass bottom 3a of the container 3. The volume of the coating metal is increased here in the region of the annular gap RS, specifically on the narrow transverse sides of the metal strand 1.

Due to the described funnel-like design of the guide channel 4 and its spatial assignment to the magnetic field of the inductors 5, the induced by the magnetic field turbulence in the molten metal coating 2 are decisively reduced and calms the bath especially on its surface.

In all subsequent figures, like parts with the same but indexed reference numerals are used. In Fig. 2 a second embodiment of the invention is shown. Here, the increased volume of the coating metal 2 is achieved by a step-shaped widening portion 4a 'of the guide channel 4'. For this purpose, the longitudinal walls 6 'of the lower width B1' stepwise increased to the upper width B2 'and thereby form the step-shaped, in the passage opening 3b' of the bottom 3a 'opening area 4a'.

The stepped broadening of the longitudinal walls 6 'of the guide channel 4', and thus of the area 4a ', begins at the bottom at a distance X to half height H / 2 and thus approximately in the upper third H / 3 of the height H.etwa half height H / 2 the height H of the inductors 5 and extends beyond the height H, and then in the longitudinal sides of the rectangular passage opening 3b 'in the bottom 3a' of the container 3 'transition.

The effect of the stepped portion 4a 'and its arrangement is the same as that of FIG Fig. 1 described funnel-like formation of the area 4a.

• Innerhalb des Abschnitts 4a' und nahe der oberen Induktorkanten 8 ist je eine senkrechte Unterbrechungswand 9 angeordnet. Diese Unterbrechungswand 9 dient zur Strömungslenkung und Badberuhigung, insbesondere auch im Zusammenwirken mit Maßnahmen, die in der älteren Patentanmeldung näher beschrieben sind.

In Fig. 3 a third embodiment of the invention is shown. It essentially corresponds to the training Fig. 2 , except for the following additions:

• Within the portion 4a 'and near the upper Induktorkanten 8 each a vertical interrupt wall 9 is arranged. This interruption wall 9 is used for flow control and bath calming, especially in conjunction with measures that are described in more detail in the earlier patent application.

In the Fig. 4 to 7 are possible cross-sectional shapes of an interruption wall 9, 9 ', 9 "and 9'" shown. The interruption wall 9 to 9 '"may consist of suitable electrically conductive or non-conductive material, in particular of metal or ceramic, and edged in cross-section, such as rectangular, single or double bevelled, in particular at an angle of 15 to 60 degrees to the vertical, or also, enclosing an angle of 15 to 60 degrees, tapered or funnel-shaped upwards and / or downwards.

In Fig. 8 is a fourth embodiment of the invention, according to the Fig. 1 , but in the central section across the metal strand 1, shown. Here, the guide channel 4 "in the height of the upper half H / 2 of the height H of the inductors 5 a lateral, approximately spherical bulge 10 of the longitudinal walls 6" and thus increases there the volume of the coating metal 2 in the annular gap, and here to the Longitudinal sides of the metal strand 1.

In Fig. 9 a fifth embodiment of the invention is shown according to the Fig. 1 but in the form of a lateral feed of coating metal 2 '' into the guide channel 4 ''. The supply takes place via two tubes 11, which in half Height H / 2 of the height H of the inductors 5 approximately horizontally in the guide channel 4 '"open and there increase the volume of the coating metal 2'" practically over the entire annular gap. The advantageous effect of the lateral supply via the tubes 11 and their arrangement is the same as that of the Fig. 1 described funnel-like design and arrangement of the area 4a.

As already indicated, the different measures of the invention described above can be combined with each other and also with those proposed in the earlier patent application.

LIST OF REFERENCE NUMBERS

1

metal strand

1'

metal strand

1"

Metalltstrang

1"'

metal strand

2

coating metal

2 '

coating metal

2 '

coating metal

2 ''

coating metal

3

container

3 '

container

3 '

container

3 ''

container

3a

ground

3a '

ground

3a "

ground

3a ' "

ground

3b

Through opening

3b '

Through opening

3b "

Through opening

3b ' "

Through opening

4

guide channel

4 '

guide channel

4 '

guide channel

4 ' "

guide channel

4a

Area

4a '

Area

4a "

Area

4a ''

Area

5

inductor

6

longitudinal wall

6 '

longitudinal wall

6 "

longitudinal wall

6 " '

longitudinal wall

7

partition

8th

upper inductor edge

9

interruption wall

10

bulge

11

pipe

B1

lower width

B1 '

lower width

B2

upper width

B2 '

upper width

H

height

H / 2

half height

H / 3

Third height

R

conveying direction

RS

annular gap

U

lower end

V

volume

X

distance

Claims (4)

1. Device for hot-dip coating of a metal strip (1, 1', 1", 1'"), particularly a steel strip, in which the metal strip (1,1', 1", 1'") is led vertically through a container (3, 3', 3", 3"'), which receives the molten coating metal (2, 2', 2", 2"'), and through an upstream guide channel (4, 4', 4", 4"'), in the region of which at least two inductors (5) for generating an electromagnetic field for retaining the coating metal (2, 2', 2", 2"') in the container (3, 3', 3", 3"') are arranged on either side of the metal strip (1, 1', 1", 1"'), characterised in that an increased volume of the coating metal (2, 2', 2", 2"') is present in the region of the upper half (H/2) to the upper third (H/3) of the inductors (5) and the magnetic field thereof and that the increased volume is formed by a lateral bulging out (10) of the walls (6") of the guide channel (4").
2. Device for hot-dip coating of a metal strip (1, 1', 1 ", 1"'), particularly a steel strip, in which the metal strip (1, 1', 1", 1"') is led vertically through a container (3, 3', 3", 3"'), which receives the molten coating metal (2, 2', 2", 2"'), and through an upstream guide channel (4, 4', 4", 4"'), in the region of which at least two inductors (5) for generating an electromagnetic field for retaining the coating metal (2, 2', 2", 2"') in the container (3, 3', 3", 3"') are arranged on either side of the metal strip (1, 1', 1 ", 1'"), characterised in that an increased volume of the coating metal (2, 2', 2", 2"') is present in the region of the upper half (H/2) to the upper third (H/3) of the inductors (5) and the magnetic field thereof and that the increased volume is formed by a lateral feed of additional coating metal (2"').
3. Device according to claim 2, characterised in that the lateral feed is provided by at least two pipes (11).
4. Device according to claim 3, characterised in that the guide channel (4"') has a rectangular cross-section and at least one pipe (11) opens at each narrow side.

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