Patent Grant
11000888
The present application is a 371 of International application PCT/EP2017/050950, filed Jan. 18, 2017, which claims priority of DE 10 2016 222 122.1, filed Nov. 10, 2016, and DE 10 2016 015 414.4, filed Dec. 23, 2016, the priority of these applications is hereby claimed and these applications are incorporated herein by reference.
The invention relates to a method for producing a metallic strip in a cast-rolling installation, wherein the cast-rolling installation comprises:
The requirements set for the flexible operation of thin-slab cast-rolling installations (CSP installations) are ever-increasing. It is pursued here in that various operating conditions are capable of being set. For example, adapting to the rolled finished strip thickness or to the casting speed is also desirable for reasons of quality and energy consumption.
Thin-slab cast-rolling installations for rolling single strips or for continuous rolling are already well known in the prior art. Reference is made, for example to DE 195 18 144 C2, to DE 196 13 718 C1, to EP 0 870 553 B1, to WO 2007/073841 A1, to WO 2009/012963 A1, and to EP 2 569 104 B1. Further solutions, some of which also involve different operating modes, are known from US 2011/272116 A1 and WO 00/10741 A1.
However, the previously known solutions do in some instances have disadvantages in terms of the aspect of flexibility.
The invention is therefore based on the object of refining a method of the type mentioned above such that an increased degree in terms of flexibility is possible; it is intended herein that a flexible response to various operating conditions is in particular to be possible. The proposed installation concept and the operating mode are thus to be distinguished by a high degree of flexibility.
The achievement of said object by the invention is characterized in that one of the following operating modes is chosen for the production of the strip:
At least one slab herein is preferably placed in the first furnace and/or in the first rolling table damping section. At least one slab or one rough strip is preferably also placed in the second furnace and/or in the second rolling table damping section.
The above-mentioned operating modes a), b), c), and/or d) herein can be chosen as a function of the final thickness of the strip. It is also possible for the operating modes a), b), c), and/or d), to be chosen as a function of the start-up process of the cast-rolling installation. It is furthermore possible for the operating modes a), b), c), and/or d), to be chosen as a function of a roll change taking place in the roughing train and/or in the finishing train.
One of the operating modes mentioned is first chosen, and the production is then carried out using said mode; accordingly, only one of the mentioned possibilities a), b), c), or d) is implemented at any one time. However, a change between the various operating modes mentioned can also be performed in a temporally successive manner.
The mean slab temperature at the outlet of the first furnace is preferably at least 1000° C., particularly preferably at least 1100° C.
The mean rough strip temperature at the outlet of the second furnace is preferably at least 1100° C., particular preferably at least 1150° C.
One refinement provides that the forming ratio of the strip in the finishing train is:
ε=(hV−hF)hV×100≥96%
hV being the rough strip thickness, and hF being the finished strip thickness. It is preferably provided especially in this case that the mean rough strip temperature at the outlet of the second furnace is at least 1150° C., wherein the product from the thickness of the strip (hB) and the speed of the strip (vB) is at least 350 mm m/min, preferably at least 500 mm m/min.
It is preferably provided that no inductive heating of the slab or/and the rough strip is performed in the procedure described.
The temperature in the last active stand of the finishing train is preferably above the γ-α phase transition, in particular above 820° C.
An exemplary embodiment of the invention is illustrated in the drawing.
The only FIGURE schematically shows the lateral view of a single-strand cast-rolling installation for the production of a strip.
The thin-slab cast-rolling concept proposed is composed of the following main components which are derived from the FIGURE:
The cast-rolling installation 2 for the production of the strip 1 first has a casting machine 3. A first furnace 4 in the conveying direction F of the material is disposed behind the casting machine 3; a roughing train 5 which has a number of roll stands R1 and R2 follows the first furnace 4 in the conveying direction F. A second furnace 6 follows behind the roughing train 5, a finishing train 7 having a plurality of roll stands F1, F2, F3, F4, F5, F6 in turn following said second furnace 6. A cooling section 8 which is followed by a reel 9 is disposed behind the finishing train 7.
A first shear S1 is disposed between the casting machine 3 and the first furnace 4. A second shear S2 is situated behind the roughing train 5 and ahead of the second furnace 6. A third shear S3 is finally situated just ahead of the reel 9.
At least one single slab fits into the first furnace 4 or/and into the first rolling table damping section; it is furthermore provided the least one single slab fits into the region between the first shear S1 and the first roll stand R1 of the roughing train 5. The roughing train 5 preferably consisting of 1 to 4 stands, wherein two stands are particularly preferably provided.
The second furnace 6 or/and the second rolling table damping section behind the roughing train 5 is/are configured such that at least one single rough strip in the horizontal position or extent, thereof, fits thereinto, or at least one single rough strip fits into the region between the second shear S2 and the first roll stand F1 of the finishing train 7. The finishing train 7 is in most instances composed of 1 to 7 stands; 4 to 6 stands are preferably provided.
The first shear S1 is a slab shear for separating the slabs which leave the casting machine 3. The second shear S2 is a rough strip shear for separating the rough strips behind the roughing train 5, and is preferably disposed ahead of the second furnace 6. The third shear S3 finally is a strip shear for separating the strips ahead of the reel 9.
Accordingly, the three shears S1, S2, and S3 are provided so as to be able to implement the above-mentioned dissimilar operating modes.
No rapid heating (in the form of induction heating, for example) is preferably provided in the cast-rolling installation 1, this being advantageous when using more cost-effective gas and under considerations in terms of energy.
Alternatively, rolling table damping sections into which at least one single slab or one single rough strip fits can be provided instead of the first furnace 4 or/and the second furnace 6 (for example, and preferably, in the form of a roller hearth furnace); in this case, inductive heating can optionally also be disposed behind said rolling table damping sections. An assembly of furnace parts and rolling table damping sections in an arbitrary sequence and combination is also possible ahead of and/or behind the roughing train.
The length of the first furnace (4), or the first rolling table damping section, or an assembly of first furnace parts (4) and rolling table damping sections in an arbitrary sequence and combination behind the first shear (S1), is preferably shorter than the length of the second furnace (6), or the second rolling table damping section, or an assembly of second furnace parts (6) and rolling table damping sections in an arbitrary sequence and combination behind the second shear (S2).
An individual slab or an individual rough strip is so long that one coil having a typically produced coil weight can be rolled or generated, respectively, from said individual slab or individual rough strip.
The cast-rolling installation (CSP installation) can be operated in a very flexible manner by way of an optimized operation of the main components mentioned. Various operating modes herein can be practically applied in the roughing train, in the finishing train, or in the overall installation.
According to the above-mentioned method mode a), continuous rolling in the roughing train 5 and continuous rolling in the finishing train 7 is initially possible, that is to say that the casting machine 3 as well as the roughing train and finishing train 5, 7 are connected to one another in this case. Rolling herein is performed by way of the casting machine mass flow, and the strips are separated by means of the third shear S3 at the reel 9.
According to the above-mentioned method mode b), continuous rolling in the roughing train 5 by way of the casting machine mass flow and single-strip rolling (batch operation) in the finishing train 7 is furthermore possible. The single rough strips herein are separated at the second shear S2. The mass flow in the finishing train 7 when rolling is higher than in the roughing train 5, or the connected casting machine 3, respectively. On account thereof, a combination of the advantages of continuous rolling in the relevant first stands, having relatively high forming ratios as well as an improved rough-strip geometry at the head and the tail, with the advantages of batch rolling in the finishing train 7 and the higher final rolling temperatures achievable therewith, results.
According to the above-mentioned method mode c), single strip rolling (batch operation) in the roughing train 5 and single strip rolling (batch operation) in the finishing train 7 is furthermore possible. The single slabs herein are separated at the first shear S1. The roughing train 5 and the finishing train 7 during the rolling procedure are both operated by way of a higher mass flow than the casting machine 3. The temperature management can be influenced in an arbitrary manner by individually choosing the speeds for the rolling trains.
According to the above-mentioned method mode d), a further operation is finally possible. When the first furnace 4 and the second furnace 6 are dimensioned such, or the spacings between the first shear S1 and the roll stand R1 of the roughing train 5, or/and between the second shear S2 and the roll stand F1 of the finishing train 7 are dimensioned, respectively, to be so long that said furnaces or spacings can receive more than one slab (for example, 2 or 3 slabs), semi-continuous strip rolling from the first furnace 4 or/and the second furnace 6, or the respective installation sections, respectively, is possible. A first separation of the semi-continuous slabs is performed at the first shear S1, or of the semi-continuous rough strips at the second shear S2, and a final separation to form individual strips is performed by way of the third shear S3 ahead of the reel 9.
The various operating modes can be chosen and set as a function of the final thickness or when starting-up the installation (at the beginning of casting) or prior to a roll change, or for temperature-related reasons. Warming-up the rolling installations in the roughing train and the finishing train can be performed, for example, in the batch mode. Firstly, a switch to the continuous mode can be carried out in the roughing train. In the case of increasingly thinner strips (preferably in the case of thicknesses of less than or equal to 1.2 mm), continuous strip rolling is expedient for the roughing train and the finishing train. When a roll change is planned only in the finishing train, switching to the batch mode takes place for the finishing train.
In order for the change over time for the work roll change in the finishing train to be gained, rolling is advantageously performed at an increased strip speed and/or temperature speed-up in the finishing train, or/and the casting speed as well as the rolling speed in the roughing train is reduced. In order for dissimilar slab temperatures or/and rough strip temperatures across the strip length to be equalized when batch rolling, and in order for ideally constant finished strip temperatures to be generated behind the finishing train, the roughing train or/and the finishing train are operated by way of a temperature speed-up or, alternatively, the water quantity of at least one intermediate stand cooling is correspondingly modified.
An increase in terms of flexibility is thus possible by way of the proposed installation.
The cast-rolling installation (CSP installation) proposed is distinguished by various advantageous technical installations and operating conditions.
An optimal arrangement of slab cleaning (or descaling, respectively) is present at the outlet of the casting machine 3 (less than 2 m) behind the last strand roll. Alternatively, the slab is cleaned (descaled) between the last two strand roll pairs.
Rolling table damping between the casting machine 3, or slab cleaning up to the entry of the first furnace 4, is advantageous. The damping is inwardly pivotable in the region of the first shear S1. The losses in terms of energy or temperature, respectively, are thus minimized in this transporting region.
The use of single-row descaling beams of a compact construction having a minimized specific descaling water quantity vspec based on the following condition is preferred:
Vspec in m3/h/m<600×v, preferably vspec in m3/h/m<450×v
where v is the transporting speed of the rolled or cast product in the region of the descaling washer in m/s (“x” being the multiplication sign).
The number of active finishing roll stands n is preferably adapted to the finished strip thickness hF. To this end, the following approximation equation is used:
n≥5×hF−0.6
This means, in order for a correct finished strip final rolling temperature to be obtained in the case of comparatively thick final strip thicknesses, ramping up is performed by 1, 2, or 3 stands, commencing with the last finishing stands. In order for a good strip quality to be generated herein, strip cooling is preferably already commenced within the finishing train behind the last active stand. Pyrometers between the last finishing stands herein monitor the setting of the correct final rolling temperature and are used for closed-loop control purposes.
The respective first furnace 4 or/and second furnace 6, or corresponding rolling table regions having damping, can be subdivided into various regions (in the longitudinal direction) such that slabs or slab parts, respectively, or/and rough strips or rough strip parts, respectively, can be conveyed away. On account thereof, buffer times can be achieved, the cold strip be disposed of in a simple manner, or the elimination of malfunctions be simplified, for example. Moreover, flame cutting machines can be additionally provided ahead of or/and behind the furnace parts.
The mean slab temperature (definition: averaged across the thickness in the center) at the outlet of the first furnace 4 is ≥1000° C., preferably ≥1100° C.
The mean rough strip temperature at the exit from the second furnace 6 is ≥1100° C., preferably ≥1150° C.
By way of high-forming (overall finishing-train forming)
ε=(hV−hF)/hV×100≥96%
(hV=rough strip thickness, hF=finished strip thickness) in the finishing train, combined with a high rough strip temperature of ≥1150° C. (at the exit from the second furnace 6) and a high mass flow in m/min mm of hB×vB≥350 m/min mm (preferably hB×vB≥500 m/min mm), or generally with the condition, is a function of the number of stands
2.316×hB×vB×e(−0.167×n)≥480 m/min mm
(where n=number of stands, hB=slab thickness mm, vB=slab speed m/min), inductive post-heating within the finishing train can typically be dispensed with in continuous rolling, and the installation can be advantageously operated so that the forming takes place in the last active finishing stand above the γ-α phase transition (for example, 820° C.). Inductive heating within the finishing train, between the finishing stands for the operating mode of continuous rolling or semi-continuous rolling, is optionally considered for establishing higher final rolling temperatures (for example ≥850° C.) or/and targeted influencing of the mechanical finished strip properties or/and at low casting speeds.
High-forming in the finishing train (see above for definition) having effective rolling-gap lubrication preferably at all stands (optionally excluding the last active finishing stand) is also advantageous, this achieving a rolling force reduction of >10% per stand as a result of the lubrication.
The transition from continuous rolling to batch rolling can be performed by way of a cut without any transition wedge at the first shear S1. The first shear S1 cuts, and finishing rolling of the continuous slab is performed, without any modification of the setup in the roll stands R1/R2 of the roughing train 5. A gap which permits that the roll stand R1 and/or the roll stand R2 in the case of the following slab engage thereon by way of a new setup is created by either reducing the casting speed and/or accelerating the rolling of the continuous slab.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 222 122.1 | Nov 2016 | DE | national |
| 10 2016 015 414.4 | Dec 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/050950 | 1/18/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/086762 | 5/17/2018 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20200061685 A1 | Feb 2020 | US |
