Patent Application
20080006387
This application is the U.S. National Stage of International Application No. PCT/EP2005/056534, filed Dec. 6, 2005 and claims the benefit thereof. The International Application claims the benefits of German application No. 10 2004 061 939.5 filed Dec. 22, 2004, both of the applications are incorporated by reference herein in their entirety.
The present invention relates to a continuous casting and rolling plant for a metal strip, in particular a steel strip, having a casting device, a hot-rolling device, and a cooling section,
The present invention relates further to a production method for a metal strip, in particular a steel strip,
The present invention finally relates also to a metal strip, in particular a steel strip.
Continuous casting and rolling plants of the aforementioned type and the corresponding production methods for a metal strip are generally known. For continuous casting and rolling plants of said kind it is known inter alia to house the casting device up to the hot-rolling device and to flood it with a protective gas so that scaling of the metal strip before it reaches the hot-rolling device is avoided. The metal strip will, however, scale after being hot-rolled.
According to the prior art the scaled metal strip is first pickled then fed to a cold-rolling device or otherwise processed. The metal strip cannot, though, be further processed until the layer of scale has been removed.
The object of the present invention is to provide a possibility of avoiding scaling of the metal strip after hot rolling.
Said object is achieved for the continuous casting and rolling plant through its having a housing that surrounds the casting device, hot-rolling device, and cooling section and being able to be flooded with a protective gas.
The object in respect of the production method is correspondingly thereto achieved through the metal strip's being ducted at least from where it exits the casting device to where it exits the cooling section in a housing flooded with a protective gas.
The metal strip will then be characterized in having been produced in a continuous casting and rolling plant of said type, with the continuous casting and rolling plant having been operated according to a production method of said type while the metal strip was being produced.
What can in particular be considered as protective gas are nebulized water, nitrogen, argon, or a combination of said substances. An additional, oxygen-depleting substance can therein possibly be admixed with the protective gas. Examples of such additional substances are carbon monoxide and many salts. Salts must therein of course be admixed in pulverized form.
The casting device is preferably embodied in such a way that the metal strip can be produced thereby having an initial thickness of at most 10 mm. If the casting device is therein embodied as a two-roller casting device, then the cast metal strip can have a particularly small initial thickness of, for instance, only one to two millimeters.
Owing to the small initial thickness of the metal strip it will fully suffice for the hot-rolling device to have at most two roll stands. Frequently even only a single roll stand will suffice.
The cooling section preferably has a feeder device for feeding an additional substance counteracting scaling into the coolant. That is because the risk of scaling will then be reduced still further.
A reeling device is as a rule located downstream of the cooling section. Said device usually has at least one reel and one shearing device.
The metal strip most usually already has relatively low temperatures upon entering the reeling device. The reeling device can therefore be located outside the housing.
The continuous casting and rolling plant will work especially effectively if a cold-rolling device is located downstream of the cooling section because the strip can first be hot-rolled directly and immediately after being cast and immediately thereafter also cold-rolled. If the continuous casting and rolling plant therein also has the reeling device, then the cold-rolling device is preferably located between the cooling section and reeling device.
If the cold-rolling device is present, it is preferably located inside the housing. That is because scaling prior to cold rolling will then be particularly reliably avoided.
Analogously to the hot-rolling device, in the case also of the cold-rolling device it will as a rule fully suffice for it to have two roll stands. Frequently even only a single roll stand will suffice.
Thanks to the inventive embodiment of the continuous casting and rolling plant it is possible for there to be no descaling device located between the hot-rolling device and cold-rolling device. So the metal strip will not be descaled between being hot-rolled and cold-rolled.
Further advantages and specifics will emerge from the following description of an exemplary embodiment in conjunction with the drawing. The single
FIGURE shows a continuous casting and rolling plant.
According to the FIGURE, a continuous casting and rolling plant has in its minimum configuration a casting device 1, a hot-rolling device 2, and a cooling section 3. The casting device 1, the hot-rolling device 2, and the cooling section 3 are therein surrounded by a housing 4.
By means of a customary feed device 5, for example a tundish with an immersion pipe arranged thereon, liquid metal 6 (for example liquid steel 6) is fed to the casting device 1 and cast by the casting device 1 to produce a metal strip 7. According to the FIGURE, the casting device 1 is therein embodied (by way of example) as a two-roller casting device 1. A very thin metal strip 7 having an initial thickness d1 of only about 1 to 10 mm, for example between 1.5 and 3 mm, can therefore be cast by said device.
The metal strip 7 is fed to the hot-rolling device 2 via pinch rolls 8 immediately after casting, so without first being buffered or otherwise intermediately stored. The hot-rolling device 2 is therefore located downstream of the casting device 1. The metal strip 7 is hot-rolled in the hot-rolling device 2 so that it exits the hot-rolling device 2 having an intermediate thickness d2. Rolling in the hot-rolling device 2 therein takes place, as can be seen in the FIGURE, at a temperature T above 723° C.
According to the FIGURE, the hot-rolling device 2 has a single roll stand. It could, though, also have two roll stands.
The hot-rolled metal strip 7 is thereupon fed to the cooling section 3. The cooling section 3 is therefore located downstream of the hot-rolling device 2. After being hot-rolled, the metal strip 7 is cooled in the cooling section 3 by means of a coolant 8. The coolant 8 is therein as a rule water, preferably heated water. It can, as indicated in the FIGURE, possibly be admixed with an additional substance that counteracts scaling. The cooling section 3 has for that purpose a corresponding feeder device 9.
According to the FIGURE, the entire housing 4 is flooded with a protective gas. From where it exits the casting device 1 to where it exits the cooling section 3, the metal strip 7 is thus ducted in the housing 4 that has been flooded with the protective gas. What can in particular be considered as protective gas are nebulized water, nitrogen, argon, or a combination of said substances. An additional, oxygen-depleting substance can furthermore be admixed with the protective gas. Examples of such additional substances are carbon monoxide and suitable, oxygen-depleting pulverized salts. A combination of said substances is possible here, too.
According to the FIGURE, the inventive continuous casting and rolling plant can have further devices 10, 11, namely a reeling device 10 and a cold-rolling device 11. Both devices 10, 11 are located downstream of the cooling section 3. If both devices 10, 11 are present, then the cold-rolling device 11 is furthermore located between the cooling section 3 and reeling device 10.
The reeling device 10 has at least one reel 12. According to the FIGURE, it even has two reels 12. It furthermore has a shearing device 13. The reeling device 10 is located preferably outside the housing 4.
The cold-rolling device 11 is embodied as required. It is located preferably inside the housing 4. According to the FIGURE, just like the hot-rolling device 2 it has only a single roll stand. It could, though, also have two roll stands. The metal strip 7 is reduced in the cold-rolling device 11 to a final thickness d3.
Because the cold-rolling device 11 is located inside the housing 4 it is not necessary for a descaling device to be located between the hot-rolling device 2 and cold-rolling device 11. Said descaling device can therefore be omitted. That is because the metal strip 7 does not have to be descaled between being hot-rolled and cold-rolled.
A high-grade metal strip 7 can thus be produced simply and in particular economically by means of the inventive continuous casting and rolling plant.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 061 939.5 | Dec 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/56534 | 12/6/2005 | WO | 6/14/2007 |
