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Sommaire du brevet 2461912 

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L'apparition de différences dans le texte et l'image des Revendications et de l'Abrégé dépend du moment auquel le document est publié. Les textes des Revendications et de l'Abrégé sont affichés :

  • lorsque la demande peut être examinée par le public;
  • lorsque le brevet est émis (délivrance).
(12) Demande de brevet: (11) CA 2461912
(54) Titre français: PROCEDE DE FINISSAGE PAR IMMERSION A CHAUD
(54) Titre anglais: METHOD FOR HOT-DIP FINISHING
Statut: Morte
Données bibliographiques
(51) Classification internationale des brevets (CIB):
  • C23C 2/24 (2006.01)
(72) Inventeurs :
  • BRISBERGER, ROLF (Allemagne)
  • TRAKOWSKI, WALTER (Allemagne)
(73) Titulaires :
  • SMS DEMAG AKTIENGESELLSCHAFT (Allemagne)
(71) Demandeurs :
  • SMS DEMAG AKTIENGESELLSCHAFT (Allemagne)
(74) Agent: FETHERSTONHAUGH & CO.
(74) Co-agent:
(45) Délivré:
(86) Date de dépôt PCT: 2002-09-25
(87) Mise à la disponibilité du public: 2003-04-10
Requête d'examen: 2007-06-26
Licence disponible: S.O.
(25) Langue des documents déposés: Anglais

Traité de coopération en matière de brevets (PCT): Oui
(86) Numéro de la demande PCT: PCT/EP2002/010741
(87) Numéro de publication internationale PCT: WO2003/029507
(85) Entrée nationale: 2004-03-26

(30) Données de priorité de la demande:
Numéro de la demande Pays / territoire Date
101 48 158.6 Allemagne 2001-09-28

Abrégés

Abrégé français

La présente invention concerne un procédé et un dispositif destinés au revêtement de la surface de matériaux notamment en forme de feuillard, par exemple d'un feuillard métallique non ferreux ou d'un feuillard en acier comprenant au moins un revêtement métallique, en passant par au moins un réservoir contenant le matériau de revêtement en fusion. Le feuillard métallique à revêtir passe par le bain de fusion de matériau de revêtement contenu dans le réservoir du haut vers le bas. A cet effet sont utilisés des éléments de guidage appropriés. La fermeture du réservoir dans sa partie inférieure s'effectue au moyen d'aimants permanents circonférentiels.


Abrégé anglais




The invention relates to a method and a device for coating the surfaces of, in
particular, strip-like material, for example, a non-ferrous metal strip or a
steel strip, with at least one metallic coating by running through at least
one container filled with the liquid melt coating material. The metal strip
for coating runs through the molten bath of coating material within the
container from bottom to top, suitable guide means are provided for the above.
The sealing of the container base is achieved by means of circumferential
permanent magnets.

Revendications

Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.





CLAIMS

1. Method for coating the surface of a product, especially
a strip-shaped product, for example, nonferrous metal strip or
steel strip (1), with at least one metal coating by passing the
product through at least one molten metal bath space that
contains the molten coating material (3), in which method, the
molten coating material is fed from a reservoir (8) into a gap
(7) between two counterrotating rotors (5, 5'), and the strip
(1) is conveyed from top to bottom through the melt (3) and
between the rotors (5, 5'), characterized by the fact that the
bottom of the gap (7) is sealed by rotating permanent magnets,
and rotating rollers (4, 4'), in which the permanent magnets are
incorporated, are installed inside the rotors (5, 5').

2. Method in accordance with Claim 1, characterized by the
fact that the rotors (5, 5') are formed from materials that are
resistant to heat and molten metal, especially nonmagnetic
materials, preferably with the use of ceramic tubes (6, 6').

14


3. Method in accordance with Claim 1 or Claim 2,
characterized by the fact that the molten metal (3) is conveyed
in controlled amounts by a metal pump (12) from a reservoir (8)
into the gap (7).

4. Method in accordance with one or more of Claims 1 to 3,
characterized by the fact that the rotating permanent magnets
simultaneously serve to adjust the desired thickness of the
coating on the metal strip (1).

5. Method in accordance with one or more of Claims 1 to 4,
characterized by the fact that, after it has been deflected in
the preheating furnace (2) under conditions of air exclusion,
preferably in a protective gas atmosphere, the metal strip (1)
is conveyed vertically downward through the molten metal (3).

6. Method in accordance with one or more of Claims 1 to 5,
characterized by the fact that the coated strip (1) is air-
stabilized and/or water-cooled as short a distance as possible
below the seal of the molten metal bath space or the molten
metal (3) or the rotors (5, 5').

7. Device for carrying out the method in accordance with
any of the preceding claims, which comprises at least one molten
metal bath space for holding a molten coating material for

15




strip-shaped metal products (1), with the formation of a gap (7)
between two counterrotating rotors (5, 5'), which seal the gap
at the bottom, characterized by the fact that rotating rollers
(4, 4'), on whose cylindrical surface permanent magnets are
mounted, are installed inside the rotors (5, 5').

8. Device in accordance with Claim 7, characterized by the
fact that the molten metal bath space that holds the hot dip
bath (3) is formed by the upper central space between the rotors
(5, 5' ).

9. Device in accordance with Claim 7 or Claim 8,
characterized by the fact that at least the rotors (5, 5') are
surrounded by a housing to form a protective gas atmosphere.

10. Device in accordance with one or more of Claims 7 to
9, characterized by the fact that the rotor housing is connected
with an upper chamber (14) for the purpose of feeding the metal
strip (1) to the rotor housing from above, with a reservoir (8)
for molten metal, with arrangements for air stabilization (15)
and water cooling (16) of the strip (1) installed below the
rotor housing, and possibly with another water bath (9).

16




Figure 1: Method 1.

KEY : K~hlung = cooling
Ofen = furnace
Band = strip
Abstreifd~sen = stripping jets
Schmelzgefäi.beta. mit flussigem Metal = hot dip coating tank with
molten metal
Schmelze = melt
Umlenk-/Stabilisierungsrollen = deflecting/stabilizing rollers
Figure 2: Method 2.

KEY: Khlung = cooling
Ofen = furnace
Nachgliih-Ofen = reannealing furnace
Abstreifdiisen = stripping jets
Schmelzgefaf~ mit Induktionskanal = hot dip coating tank with
induction duct
Ofengehause = furnace housing
Umlenk-/Stabilisierungsrollen = deflecting/stabilizing rollers

17




Figure 3: Method in accordance with the invention.

KEY: Ofen = furnace
Spannrolle = tension roller
Schleuse = lock
Verzinkungskammer = galvanizing chamber
konstanter Betrieb -- Band lauft = constant operation -- strip
is running
Rotoren drehen = rotors are rotating
Spalt geoffnet = gap open
Ofenkammer geschlossen = furnace chamber closed
Schmelze = melt
Spalt = gap
Rotoren mit Permanentmagneten = rotors with permanent magnets
Beschichtungssektion = coating section
Keramikrohre = ceramic tubes
Schmelze = melt
Pumpe = pump
Vorlagebehalter = reservoir
Luftstabilisierung = air stabilization
Wasserkuhlung = water cooling
is



Wasserbad = water bath
Spannrolle = tension roller
Figure 4: Method in accordance with the invention.
KEY: Anfahrsituation -- Band lauft = start-up situation --
strip is running
Rotoren drehen = rotors are rotating
Spalt geschlossen = gap closed
Schmelze wird zugefuhrt = melt is fed in
ofenkammer geschlossen = furnace chamber closed
otherwise see Figure 3, i.e.:
KEY: ofen = furnace
Spannrolle = tension roller
Schleuse = lock
Verzinkungskammer = galvanizing chamber
konstanter Betrieb -- Band lauft = constant operation -- strip
is running
Rotoren drehen = rotors are rotating
Spalt geoffnet = gap open
Ofenkammer geschlossen = furnace chamber closed
Schmelze = melt

19



Spalt = gap
Rotoren mit Permanentmagneten = rotors with permanent magnets
Beschichtungssektion = coating section
Keramikrohre = ceramic tubes
Schmelze = melt
Pumpe = pump
Vorlagebehalter = reservoir
Luftstabilisierung = air stabilization
Wasserkuhlung = water cooling
Wasserbad = water bath
Spannrolle = tension roller
Figure 5: Method in accordance with the invention.
KEY: Stillstand nach Betrieb = shutdown after operation
Rucklauf der Schmelze = return of the melt
Rotoren drehen = rotors are rotating
Spalt geschlossen = gap closed
Ofenkammer geoffnet = furnace chamber open
Otherwise see Figure 3, i.e.:
KEY: Ofen = furnace
Spannrolle = tension roller
Schleuse = lock




Verzinkungskammer = galvanizing chamber
konstanter Betrieb -- Band lauft = constant operation -- strip
is running
Rotoren drehen = rotors are rotating
Spalt geoffnet = gap open
Ofenkammer geschlossen = furnace chamber closed
Schmelze = melt
Spalt = gap
Rotoren mit Permanentmagneten = rotors with permanent magnets
Beschichtungssektion = coating section
Keramikrohre = ceramic tubes
Schmelze = melt
Pumpe = pump
vorlagebehalter = reservoir
Luftstabilisierung = air stabilization
Wasserkuhlung = water cooling
Wasserbad = water bath
Spannrolle = tension roller

21

Description

Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.



CA 02461912 2004-03-26
TRANSLATION (HM-566PCT-original):
WO 03/029,507 Al
PCT/EP02/10,741
METHOD FOR HOT DIP COATING
The invention concerns a method for coating the surface of
a product, especially a strip-shaped product, for example,
nonferrous metal strip or steel strip, with at least one metal
coating by passing the product through at least one molten metal
bath space that contains the molten coating material. The
invention also concerns a device for carrying out the method.
In conventional hot dip coating of strip (referred to here
as Method 1) with Zn, Zn-A1, A1, or A1-Si alloys, the strip runs
in the coating section from an annealing furnace under
conditions of air exclusion into the molten metal and is
deflected vertically and stabilized by various arrangements of
nondriven rollers (see Figure 1). This applies to all of the
specified coating metals/alloys used in hot dip coating.
A disadvantage of Method 1 is that the rollers and the
bearings of the rollers are located within the molten material,
and all parts are exposed to chemical attack by the molten
1


CA 02461912 2004-03-26
material. The service life of the parts that are used within
the molten material is limited. In addition, a large volume of
molten material with a correspondingly large dip bath is
necessary to accommodate the rollers and all of the bath
equipment. 200 to 400 t of molten zinc are customary in hot dip
galvanizing. Due to this large volume, rapid regulation of the
temperature and alloy composition of the melt is not possible.
Large fluctuations of the specified parameters must be accepted
and sometimes result in loss of quality, since measures related
to the production of the alloy and those related to influencing
the strip quality are carried out in the same tank and thus
affect one another.
Another disadvantage is that the production speed cannot be
increased to realize an economical plant output (about 180
m/min), especially in the case of thin strip < 0.5 mm. One
reason for this is that relative motion can develop between the
rollers located in the bath and the strip. If the tension is
increased in an effort to avoid this problem, there is the risk
of strip breakage. This results in scrap and prolonged plant
shutdowns.
2


CA 02461912 2004-03-26
The jet stripping system located above the zinc hot dip
bath further limits the maximum strip advance speed of a hot dip
galvanizing installation (see Figure 1). The coating thickness
is adjusted by air or nitrogen, and the minimum coating
thickness that can be produced increases with increasing strip
speed. This means that thin coatings cannot be produced at high
strip speeds. However, certain demanding applications require
thin coatings
(< 25 g/mz on one side in hot dip galvanized sheet).
So-called vertical hot dip galvanizing is well known as an
advanced method for the hot dip coating of ferritic steel strip
made of soft unalloyed steels and is described in various
patents, such as EP 0 630 421 B1, EP 0 630 420 B1, and EP 0 673
444 B1.
In this method (referred to here as Method 2), the strip
passes from bottom to top through a working tank filled with
molten metal composed of zinc and/or A1 alloys after it has been
subjected to a heat treatment. The strip enters the molten bath
under conditions of air exclusion. The volume of molten metal
(about 2-5 t of molten zinc) is much smaller than in Method 1.
The qualitative problems described above also do not occur,
3


CA 02461912 2004-03-26
since the measures related to the production of the alloy are
carried out in a reservoir located alongside the line, while
measures to influence the strip quality are carried out
separately in the working tank.
The working tank and the furnace chamber located below it
are connected by a gastight ceramic duct, which is about 800 mm
high and has a passage width for the strip of only a maximum of
20 mm. The working tank is sealed at the bottom to prevent
molten metal from flowing down into the furnace chamber by means
of a seal produced within this duct by two inductors arranged at
the side of the duct or strip. These inductors induce an
electromagnetic traveling field, which produces an upwardly
directed force that prevents the molten metal from flowing down.
This inductive system acts like a pump, so that exchange of the
melt in the duct is ensured.
Method 2 is characterized by the fact that, at least in the
coating area up to the hot dip bath, significantly higher strip
speeds on the order of 300 m/min can be realized even with thin
steel strip, since there are no rollers in the coating tank.
After the strip has passed through the coating unit from
bottom to top at a temperature, e.g., in the case of hot dip
4


CA 02461912 2004-03-26
galvanizing, of about 460°C, the desired thickness of the metal
coating is adjusted a short distance above the hot dip bath by
the jet stripping process, as in Method 1. This process is
comparable to the process used in Method 1 and involves the
blowing of compressed air or nitrogen.
As in Method 1, the jet stripping process in Method 2 also
limits the maximum possible strip speed when thin coatings are
being applied. However, Method 2 offers greater degrees of
freedom for the galvanizing parameters of melt temperature and
viscosity and alloy composition, which likewise affect the
coating thickness. For this reason, it is to be expected that a
higher strip speed can be selected in Method 2 than in Method 1
for the same coating thickness. In contrast to Method 1, Method
2 has not yet been tested on the industrial scale. So far only
pilot plant trials with narrow strip have been conducted. These
trials were successful.
However, an obstacle to an increase in speed is presented
by the fact that the strip subsequently must be cooled below
300°C in the upwardly traveling strand before the first
deflection. If the temperature is higher, there is the danger
that metallic particles will grow on the first contact roller or


CA 02461912 2004-03-26
deflecting roller in the cooling tower and cause irreparable
surface defects on the material.
The cooling is usually produced by several successive air
cooling lines. However, the cooling effect or, more precisely,
the cooling rate, is limited by the medium and cannot be
increased at will on a fixed length of line (e.g., two times 15
m) with the use of air as the cooling medium. With increasing
strip speed or with increasing mass throughput, the cooling
lines must be lengthened. However, it then becomes necessary to
raise the upper deflecting roller in the cooling tower of a hot
dip coating installation.
In installations that are operated by Method 1, the height
of the upper deflecting roller is usually 30-60 m. In the case
of Method 2, it would be necessary, at high strip speeds, to
lengthen the cooling lines accordingly, and the height of the
cooling tower would have to be increased to about 80-90 m. This
requires higher capital expenditures for buildings and
foundations.
The free-running, unstabilized strip length in the tower
would thus increase, and the strip flow would be destabilized,
so that vibrations may occur, and the product quality may be
6


CA 02461912 2004-03-26
adversely affected. The use of other cooling media in the
upwardly traveling strand is problematic, and so far this
problem has not been solved on the industrial scale.
Another problem, which concerns the electromagnetic seal
used in Method 2, is that the forces that act on the liquid melt
also act on the ferritic strip. Undesired contact of the strip
with the duct due to the magnetic forces of the sealing
inductors is possible only by additional expensive measures.
This requires additional stabilizing coils and expensive
automatic control technology.
The objective of the present invention is to avoid the
specified disadvantages of Methods 1 and 2 and to create a high-
speed hot dip coating installation without a cooling tower,
which combines the least possible construction expense with
optimized capital investment costs and high plant output with
the best production quality.
This objective is achieved with a method of the type
described in the introductory clause of Claim 1 by sealing the
molten metal bath space by means of rotating permanent magnets.
The sealing of the molten metal bath space by rotating permanent
magnets is considerably more reliable and less expensive than an
7


CA 02461912 2004-03-26
electromagnetic solution, and significantly less power is needed
for the rotation than for an electromagnetic seal, which is an
advantage especially in the event of a power failure.
Refinements of the method are described in the dependent
claims. A device and refinements of this device for carrying
out the method of the invention are the objects of additional
claims.
The invention is described below with reference to several
embodiments shown schematically in the drawings.
-- Figure 1 shows a conventional strip coating method.
-- Figure 2 shows an advanced coating method in accordance
with the state of the art.
-- Figure 3 shows the coating method of the invention and a
correspondingly designed high-speed hot dip coating installation
in operation.
-- Figure 4 shows the installation in Figure 3 in a start-
up situation.
-- Figure 5 shows the installation in Figure 3 during
shutdown after operation.
In accordance with Figure 3, after a deflection in the
furnace under conditions of air exclusion, strip 1 runs
8


CA 02461912 2004-03-26
vertically downward into a molten metal bath space that contains
the hot dip bath. This hot dip bath is sealed towards the
bottom. This requires forces, but these forces are not
electromagnetic in nature, but rather are produced by rotating
permanent magnets. The sealing of the melt with permanent
magnets is well known in itself, but the prior art involved the
use of rectangular ducts. A duct shape like this cannot be
changed with respect to clearance and shape.
By contrast, the present invention proposes two adjacent
rotors 5, 5'. The rotors are tubes 6, 6' made of materials that
are resistant to heat and molten metal, preferably ceramic
materials. Rollers, on whose cylindrical surface permanent
magnets 4 are mounted, rotate inside these tubes 6, 6', whose
diameters may be freely selected. The rotors 5, 5' can be
adjusted to the melt or to the strip. It is also possible to
close the gap 7 when the installation is shut down or is being
started up.
Permanent magnets are significantly less expensive than
electromagnetic sealing by means of coils or inductors, and much
less power is required for the rotation than for an
electromagnetic seal, which is an advantage especially in the
9


CA 02461912 2004-03-26
event of a power failure.
In addition, much higher field strengths can be produced
with permanent magnets (by a factor of 3) than by the
electromagnetic method. These high field strengths and the
resulting higher forces are needed for the stripping process for
adjusting the desired coating thickness on the steel strip. In
the previously known methods, this adjustment must be
accomplished by additional stripping jets.
Additional measures within the magnetic seal and stripping
are no longer required in the method of the invention, since the
region of the narrowest passage of the strip 1 through the
sealing unit is now only a few millimeters. Furthermore, the
strip can be supported at much shorter lengths than in the
previously known Methods 1 and 2, since the strip 1 can be
immediately cooled and deflected into a water bath 9 directly
below the sealing unit. The support length in the present
invention is preferably only about 5,000 mm, whereas in Method 1
it is about 8-10 times greater, and in Method 2 it is greater
still.
Another advantage of the method of the invention is that
the surface of the molten metal, preferably the molten zinc, in


CA 02461912 2004-03-26
the coating area is within a protective gas atmosphere, which
preferably consists of a nitrogen/hydrogen mixture, so that
interfering oxidation of the molten zinc cannot occur. In the
previously known Methods 1 and 2, this can be accomplished only
with considerable additional expense. Furthermore, in the
previous methods, it is necessary for the surface of the zinc
bath to be accessible for certain types of manual work. In the
present invention, access to the surface of the hot dip bath for
the purpose of removing particles of oxidized metal is
unnecessary.
In the embodiment in Figure 3, the installation for the hot
dip coating of a nonferrous metal strip or a steel strip 1 is
shown in continuous operation.
The incoming strip 1 to be coated passes through a tension
roller 17 and then through a lock 18, which hermetically seals
the protective gas atmosphere prevailing inside the hot dip
coating installation from the ambient, oxygen-containing
atmosphere.
In the galvanizing chamber 14 which follows, the strip 1 is
vertically deflected by guide rollers 13 towards the coating
section 19. Upon entering the coating station 19, the strip 1
11


CA 02461912 2004-03-26
passes vertically from top to bottom through the bath of molten
metal 3 maintained in the gap 7 between the rotors 5, 5' and
thus receives the desired coating.
At the lower end of this hot dip bath 3, in a gap formed
between spaced rotors 5, 5', the molten metal is prevented from
running out at the bottom by magnetic forces of magnetic fields
or traveling magnetic fields of the rotating permanent magnets
4. The rotors 5, 5' are located inside the tubes 6, 6' that
surround them. The coating station 19 is surrounded on the
outside by a duct-like housing and holds the rotors 5, 5, which
are spaced a variable distance apart. They are surrounded by
the tubes 6, 6', which are made of materials that are resistant
to heat and molten metal, especially nonmagnetic materials and
preferably ceramic materials.
The permanent magnets 4 rotate inside these tubes 6, 6'.
The molten metal required for coating, which must be
continuously replenished, is conveyed in controlled amounts by a
metal pump 12 from a reservoir 8, in which it is conditioned,
into the gap 7 between the rotors 5, 5'. The strip 1, which is
coated in the gap 7, passes through the gap at the lower end and
then passes in succession through an arrangement 15 for air
12


CA 02461912 2004-03-26
stabilization and an arrangement 16 for water cooling.
After it has passed through the water bath 9 and a tension
roller 20, it is removed from the installation for further use
or treatment.
The additional Figures 4 and 5 show the method of the
invention
(a) in a start-up situation, and
(b) during shutdown after operation.
(a) Start-U~ Situation:
-- strip not running
-- rotors rotate
-- gap between rotors closed
-- melt is supplied
-- furnace chamber closed.
(b) During Shutdown after Operation:
-- return of melt
-- rotors rotate
-- gap closed
-- furnace chamber opened.
13

Dessin représentatif
Une figure unique qui représente un dessin illustrant l'invention.
États administratifs

Pour une meilleure compréhension de l'état de la demande ou brevet qui figure sur cette page, la rubrique Mise en garde , et les descriptions de Brevet , États administratifs , Taxes périodiques et Historique des paiements devraient être consultées.

États administratifs

Titre Date
Date de délivrance prévu Non disponible
(86) Date de dépôt PCT 2002-09-25
(87) Date de publication PCT 2003-04-10
(85) Entrée nationale 2004-03-26
Requête d'examen 2007-06-26
Demande morte 2009-09-25

Historique d'abandonnement

Date d'abandonnement Raison Reinstatement Date
2008-09-25 Taxe périodique sur la demande impayée

Historique des paiements

Type de taxes Anniversaire Échéance Montant payé Date payée
Le dépôt d'une demande de brevet 400,00 $ 2004-03-26
Enregistrement de documents 100,00 $ 2004-05-14
Taxe de maintien en état - Demande - nouvelle loi 2 2004-09-27 100,00 $ 2004-08-19
Taxe de maintien en état - Demande - nouvelle loi 3 2005-09-26 100,00 $ 2005-08-23
Taxe de maintien en état - Demande - nouvelle loi 4 2006-09-25 100,00 $ 2006-08-22
Requête d'examen 800,00 $ 2007-06-26
Taxe de maintien en état - Demande - nouvelle loi 5 2007-09-25 200,00 $ 2007-09-25
Titulaires au dossier

Les titulaires actuels et antérieures au dossier sont affichés en ordre alphabétique.

Titulaires actuels au dossier
SMS DEMAG AKTIENGESELLSCHAFT
Titulaires antérieures au dossier
BRISBERGER, ROLF
TRAKOWSKI, WALTER
Les propriétaires antérieurs qui ne figurent pas dans la liste des « Propriétaires au dossier » apparaîtront dans d'autres documents au dossier.
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Description du
Document 
Date
(yyyy-mm-dd) 
Nombre de pages   Taille de l'image (Ko) 
Abrégé 2004-03-26 1 16
Dessins 2004-03-26 5 115
Revendications 2004-03-26 8 186
Description 2004-03-26 13 407
Dessins représentatifs 2004-06-01 1 15
Page couverture 2004-06-02 2 49
Correspondance 2004-05-27 1 25
PCT 2004-03-26 13 519
Cession 2004-03-26 2 84
PCT 2004-03-26 3 124
Cession 2004-05-14 2 95
Poursuite-Amendment 2007-06-26 1 44
Taxes 2007-09-25 1 44