Coating apparatus – Immersion or work-confined pool type – Work extending through pool-confining wall area
Reexamination Certificate
1999-02-09
2001-07-03
Lamb, Brenda A. (Department: 1734)
Coating apparatus
Immersion or work-confined pool type
Work extending through pool-confining wall area
C118S419000
Reexamination Certificate
active
06254680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for coating a metal strip that is passed through a container which holds the melted coating material and, underneath the melt bath level, has a channel which encloses the material in the form of strip, in which channel currents are induced in the coating material by means of inductors and cause an electromagnetic force in order to hold the coating material back.
2. Description of the Prior Art
A system of this generic type prior art apparatus for coating a metal strip is described, for example, in German Patent 43 44 939. The container which holds the coating material in the form of a melt there is provided with an opening ac the base for the strip to be coated to pass through. This opening is sealed by an electromagnet pump with produces an electromagnetic force equal in magnitude to or greater than the metallostatic pressure in the opening of the through-channel. In consequence, the liquid coating material is prevented from running out through the through-channel.
The through-channel is subject to stringent thermal requirements and, accordingly, is subject to wear. For this reason, the channel has to be replaced. Replacement of an integral channel requires that there no longer is any strip in the channel and that the strip must be threaded through the channel once again after replacement of the worn components. The separation and renewed threading in of the strip is very time-consuming and difficult, and considerably interferes with the productivity of the system as a result of long down times.
SUMMARY OF THE INVENTION
The object of the present invention is to improve an apparatus of this generic type for coating material in the form of strip, such that the channel can be replaced quickly with minimized system down times, without the strip having to be cut through.
In order to achieve this object, it is proposed according to the invention that the channel is attached to the base of the container such that it is easily detachable and comprises a plurality of parts which can be separated in the strip running direction. The plurality of parts are sealed with respect to one another and can individually be moved away from the strip, transversely with respect to the strip running direction, in order to replace the channel with the strip located in it, after releasing the separation connection.
The essence of the present invention is to design the channel from parts which can be separated from one another and can be moved away from the strip for replacement of the channel, without the strip itself having to be separated or unthreaded. The channel or the parts of the channel are thus attached to the base of the container which holds the coating material such that they are easily detachable and can be moved away in a very short time once the container has been emptied. In the same way, new channel parts can be brought into position and joined together to form a new channel, so that a closed channel surrounding the strip is produced. The separable parts are sealed with respect to one another by means of suitable sealants and, in the operating state, close the channel in a liquid-tight manner.
In one embodiment of the invention, the channel is composed of an electrically insulating material having a good surface wetting capability, the channel preferably being formed ceramic material. In terms of its surface characteristic and structure, the ceramic material is designed such that the surface is wetted by the liquid coating metal. The inductors, which enclose the channel on both sides, ire particularly highly effective when the electrically insulated ceramic material is used.
In order to replace the channel parts, they may be attached to the inductors and moved or displaced together with them. This means that, in order to replace the channel parts and to open the sealed channel, the inductors (for example guided on rollers) may be moved transversely with respect to the strip and carry the separated channel parts with them when they move.
According to another embodiment of the invention, the channel parts may also be arranged such that they can be moved or displaced in the system independently of the inductors arid, for example for replacement of the channel, the inductors may be moved first, with the channel parts being displaced in a second process step.
For the coating process, it is advantageous if the channel is sealed such that It can be closed in a gastight manner with barrier gas applied to it.
The channel, maybe held on the container base by means of wedges or eccentrics for quick detachment. Once the wedges have been released or the eccentrics moved out of the way, the channel can quickly be moved to its removed position. In any case, the strip remains in its central position, while the channel is removed by splitting it into channel parts.
A further feature of the invention includes a roller arrangement for guiding and centering the strip provided underneath the channel.
The present invention allows the channel parts to be replaced quickly without previously removing the strip, and considerably reduces the system down times. In consequence, system productivity can be improved, with the quality of the coated strip metal being increased at the same time since the simplified quick replacement of the worn channel parts means that non-uniformities in the coating caused by channel replacement are kept at a very low level.
BRIEF DESCRIPTION OF THE DRAWINGS
An exemplary embodiment of the invention is described in the following text and illustrated in the drawing, in which:
FIG. 1
is a schematic diagram showing a longitudinal section of an apparatus according to the invention for hot-dip coating of strips,
FIG. 2
shows the apparatus according to
FIG. 1
along section line II—II.
FIGS. 3
a-d
show cross sections along line III—III of FIG.
2
through various embodiment of split channels, and
FIG. 4
shows an embodiment of an attachment of the channel on the container base.
REFERENCES:
patent: 3090352 (1963-05-01), Knapp
patent: 5702528 (1997-12-01), Paramonor et al.
patent: 5827576 (1998-10-01), Carter et al.
patent: 5965210 (1999-10-01), Tada et al.
patent: 4344939 (1995-02-01), None
patent: 9603533 (1996-02-01), None
Fligge Aribert
Frommann Klaus
Ottersbach Walter
Cohen & Pontani, Lieberman & Pavane
Lamb Brenda A.
Mannesmann AG
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