EP1525060B1 - Method and device for the continuous production of metallic strips - Google Patents

Abstract

The invention relates to a method and a device for the continuous production of a metallic, preferably cold-rolled strip ( 1 ), especially a high-grade steel. The strip ( 1 ) which is to be finished is guided by a device ( 2 ) into a conveyor device (R), wherein the strip ( 1 ) undergoes a rolling process, a heating process and chemical treatment. According to the inventive method, in order to improve productivity, the rolling process is carried out primarily after heating the strip and after chemical treatment.

Description

The invention relates to a method for continuously producing a metallic, preferably cold-rolled strip, in particular a stainless steel strip, wherein the strip to be produced is guided in a conveying direction through a device in which the strip is subjected to a rolling process, a heating and a chemical treatment. Furthermore, the invention relates to a suitable system.

In the production of cold-rolled strips, in particular of stainless steel strips, a metal strip passes through a production device in which various processes are carried out on the strip. In this case, the strip is reduced in a rolling process in its thickness. Furthermore, a heat treatment can be followed, which gives the band special material properties. Furthermore, the tape must have a scale-free surface, which is why it passes through a pickling line in which the scale is removed by means of a chemical treatment.

For further processing - eg. For example, by cold rolling, for a metallic coating or the direct processing into a final product - the hot-rolled steel strip must have a scale-free surface. Therefore, the scale formed during hot rolling and subsequent cooling must be removed completely. This is usually done by a pickling process, wherein the consisting of the various iron oxides (FeO, Fe ₃ O ₄ , Fe ₂ O ₃ ) or in stainless steels also chromium-rich iron oxides existing scale depending on the steel quality by means of various acids (eg., Hydrochloric acid, sulfuric acid , Nitric acid or mixed acid) is dissolved at elevated temperatures by chemical reaction with the acid. Before pickling, normal steel usually has an additional mechanical treatment Stretch bends are required to break up the scale and thus allow faster penetration of the acid into the scale layer. For the stainless steels, austenitic and ferritic steels, which are much more difficult to pickle, annealing and mechanical descaling of the strip during the pickling process are used upstream to achieve the best possible strip surface.

A method or a system of the generic type is known from DE 100 22 045 C1. There, it is disclosed that a strip is passed through a pickling device, wherein in front of and behind the pickling device a respective rolling unit is arranged. In the conveying direction of the belt behind the second roller unit, the belt passes through an annealing furnace and then a pickling tank in which the scale is removed from the surface of the belt. Before winding up the tape that has been completed so far, it can be finally finished in a temper rolling mill.

WO 00/37189 and WO 00/37190 disclose a device for producing a metal strip, in which the strip is first reduced in its thickness to a multi-stand rolling course. Subsequently, the tape enters an annealing furnace; in the further course, the strip is passed through a pickling device. Before the tape is wound up, a rolling operation can follow, but only a slight reduction of the thickness on the belt is required.

US 2001/0037667 A1 discloses a similar apparatus for producing a metal strip. Here, however, no heating of the band is provided. The strip is passed through a rolling mill only after descaling in a pickling line.

The previously known methods have the disadvantage that it is necessary to roll partially on scaled or on only partially demineralized surfaces. By rolling on these belt surfaces occurs a significantly higher roller wear as when rolling on a descaled surface. Furthermore, this can not produce the surface quality, as it is often required, so that expensive post-treatments are necessary.

Furthermore, it is very disadvantageous in view of the economic viability of the process in question that the rolling mill following facilities, and in particular the annealing furnace and the pickling line, must be adjusted in their dimensions of the reduced by the rolling process typically 30 to 40% band thickness ; Since the strip is already thinner, but longer, the annealing furnace and the pickling line must be designed to be correspondingly long, which leads to high costs of the system.

The invention is therefore based on the object to provide a method and an associated system of the type mentioned, with which or with which it is possible to avoid the disadvantages mentioned, which in particular achieves a higher productivity and efficiency in the production of a strip to be Furthermore, the surface quality of the finished strip is to be improved.

The solution of this problem by the invention according to the method is characterized in that the rolling process is carried out only after the heating of the belt and after the chemical treatment.

This procedure ensures that the three process steps of rolling the strip to the desired thickness, carrying out a heat treatment of the strip by an annealing process and descaling the strip by means of pickling are carried out in the production plant, the above-mentioned disadvantages not being apparent Bandes of the original to the reduced, final thickness takes place only in the conveying direction after annealing and pickling, both the annealing furnace and the pickling line can be made smaller in their respective dimensions. Furthermore, said rolling process takes place only on a completely descaled strip surface, so that the roller wear remains low. Furthermore, the proposed procedure results in improved strip surface quality without the need for further measures.

It is suggested that preferably the heating of the belt, the chemical treatment of the belt and the rolling process are performed in this order. The rolling process is preferably a tandem rolling process. In general, rolling process is to be understood here as meaning that the strip is substantially reduced in its thickness, preferably by at least 20%. As already mentioned above, the chemical treatment of the strip is preferably a pickling process.

The device according to the invention for the continuous production of a metal, cold-rolled strip has a device for heating, i. H. in particular for annealing the strip, means for chemically treating the strip, and means for rolling the strip. According to the invention, the device for rolling the strip in the conveying direction is arranged behind the device for heating the strip and the device for chemically treating the strip, wherein the device for rolling the strip has at least one tandem rolling train. This consists of several rolling stands, which can be designed as a rolling mill of the type 6-high or as a rolling mill of the Z-high type. In addition to this rolling device no further device for the purpose of reducing the thickness of the tape is required.

In order to improve the quality further, a draft straightening unit can be arranged between the device for heating the strip (annealing furnace) and the device for chemically treating the strip (pickling line). Furthermore, a metal grain jet unit can be arranged between the annealing furnace and the pickling line.

In the conveying direction downstream of the device for the chemical treatment of the strip, a trimming unit may further be arranged to laterally trim the strip.

The maintenance of the smoothest possible running of the belt through the manufacturing facility is facilitated by the fact that the device has at least one, preferably three band memory.

Depending on the production volume of the strip, the described manufacturing device can also be operated as a combined hot and cold strip annealing and pickling line with integrated rolling train (tandem mill). In order to favor this, a degreasing device can additionally be arranged in the conveying direction before the device for heating the strip, in particular in front of the inlet strip store.

In the drawing, an embodiment of the invention is shown. The single figure shows schematically a device for producing a stainless steel strip.

In the figure, a device 2 can be seen, on which a metal strip 1 (metal strand) is processed. In this case, the band 1 in the conveying direction R - d. H. in the figure from left to right - guided by the device 2, wherein a continuous passage of the belt 1 (pass with a substantially constant belt speed) is sought.

In an inlet section 13, not shown, the tape 1 of the device 2 is supplied. The belt 1 is unwound from an unwinding unit, not shown, and directed into the device 2. In the conveying direction R, a degreasing device 12 follows, in which the strip surface is cleaned. Subsequently, the tape 1 enters a tape storage 9 (inlet storage), which is positioned below a device 3 for heating the strip 1 (annealing furnace). About the tape storage 9 can be achieved that even with minor external disturbances in the tape feed a continuous run of the tape is achieved.

In the annealing furnace 3, the strip 1 is subjected to a heat treatment. Anschießend it comes to a stretcher straightening unit 6, in which the band 1 is smoothed. Downstream of the drafting straightening unit 6 is a metal-grain jet unit 7.

In the conveying direction R behind the metal grain jet unit 7, a device 4 for the chemical treatment of the belt 1 is arranged, namely a pickling line, in which the belt 1 is passed through tanks, which are filled with acid. By means of the pickling process, the scale layer on the surface of the belt 1 can be removed and the belt 1 can thus be given an improved surface quality.

Below the pickling line 4, a tape storage 11 (buffer) is arranged. From this, the tape 1 runs in a Besäumeinheit 8, in which the sides of the tape 1 are cut. From the trimming unit 8, the belt 1 passes through a further belt store 10 (discharge storage) to the device 5 for rolling the belt 1. This device 5 is designed as a tandem rolling mill. There are three consecutively arranged rolling stands 5a, 5b and 5c, in which the strip 1 is rolled and thereby reduced in thickness.

Behind the tandem rolling train 5, an outlet section 14 is arranged, which has a winding unit, not shown, with which the finished tape 1 can be wound.

As already mentioned, the tandem rolling train 5 has three rolling stands 5a, 5b and 5c, which may be designed in the form of a multi-roll cold rolling mill, a 6-high rolling mill or a Z-high rolling mill. Due to the fact that the reduction in the thickness of the strip 1 takes place only in the only device 5 for rolling the strip 1 at the end of the device 2, the strip 1 has before the tandem rolling mill 5 still a relatively large thickness, namely the thickness at which the tape 1 enters the device 2, on. This has the consequence that the length of both the annealing furnace 3 and the pickling line 4 can be kept relatively low.

This results in a relatively compact design of the device 2, which keeps the investment costs for the device 2 low. Both the annealing furnace 3 and the pickling line 4 can therefore be designed for the original thickness of the strip 1, with which the strip 1 enters the device 2.

At least for the austenitic and simple ferritic materials, a reduction in thickness can be made without prior annealing, resulting in a smaller maximum thickness reduction of a maximum of 30 to 40%.

The maximum thickness reduction of the belt 1 per pass through the device 2 depends only on the materials and the performance of the tandem rolling mill 5; no consideration has to be given to the unannealed tape.

A rolling stand of the tandem rolling train 5 can be designed so that the band 1 can be dressed during a final annealing.

The descaled and preferably already edged strip can - following the device 2 - without intermediate storage under constant tension continuously in a follow-up device (hot dip galvanizing, etc.) enter. The finished tape can be wound behind the Nachfolgeeinrichtung alternately with two reels and divided with a pair of scissors.

LIST OF REFERENCE NUMBERS

1

Ribbon (metal strand)

2

contraption

3

Device for heating the strip (annealing furnace)

4

Device for the chemical treatment of the strip (pickling device)

5

Device for rolling the strip (tandem rolling mill)

5a

rolling mill

5b

rolling mill

5c

rolling mill

6

Tension leveling unit

7

Metal grain blowing unit

8th

trimming shear

9

Tape storage (infeed storage)

10

Tape storage (discharge storage)

11

Tape storage (cache)

12

degreasing

13

entry section

14

exit section

R

conveying direction

Claims (12)

1. Method for continuous production of a cold-rolled, metallic strap (1), particularly a stainless steel strip, wherein a hot-rolled metal strip is unwound from an unwinding unit and the strip (1) to be produced is led in conveying direction (R) through a device (2) in which the strip (1) is subjected to a rolling process, a heating and a chemical treatment, characterised in that the rolling process is carried out only after the heating of the strip and after the chemical treatment.
2. Method according to claim 1, characterised in that the heating of the strip (1), the chemical treatment of the strip (1) and the rolling process are carried out in this sequence.
3. Method according to claim 1 or 2, characterised in that the rolling process is a tandem rolling process.
4. Method according to one of claims 1 to 3, characterised in that the strip (1) is substantially reduced in its thickness by the rolling process, preferably by at least 20%.
5. Method according to one of claims 1 to 4, characterised in that the chemical treatment is a pickling process.
6. Plant with an unwinding unit and a device (2) for continuous production of a cold-rolled metallic strip (1), particularly a stainless steel strip, particularly for carrying out the method according to one of claims 1 to 5, wherein a hot-rolled metal strip is unwound from the unwinding unit and the strip (1) to be produced transits the device (2) in conveying direction (R) and the device (2) comprises equipment (3) for heating the strip (1), equipment (4) for chemical treatment of the strip (1) and equipment (5) for rolling the strip (1), characterised in that the equipment (5) for rolling the strip (1) is arranged behind, in conveying direction (R), the equipment (3) for heating the strip (1) and the equipment (4) for chemical treatment of the strip (1), and the equipment (5) for rolling the strip (2) comprises a tandem rolling train (5a, 5b, 5c).
7. Plant according to claim 6, characterised in that the roll stands (5a, 5b, 5c) are constructed as a multi-roll cold-rolling mill with six-high or Z-high roll arrangement.
8. Plant according to claim 6 or 7, characterised in that the equipment (4) for chemical treatment of the strip (1) is pickling equipment.
9. Plant according to one of claims 6 to 8, characterised in that a stretch-levelling unit (6) is arranged between the equipment (3) for heating the strip (1) and the equipment (4) for chemical treatment of the strip (1).
10. Plant according to one of claims 6 to 9, characterised in that a metal grain blast unit (7) is arranged between the equipment (3) for heating the strip (1) and the equipment (4) for chemical treatment of the strip (1).
11. Plant according to one of claims 6 to 10, characterised in that a trimming unit (8) is arranged behind, in conveying direction (R), the equipment (4) for chemical treatment of the strip (1).
12. Plant according to one of claims 6 to 11, characterised in that degreasing equipment (12) is arranged in front, in conveying direction (R), of the equipment (3) for heating the strip (1).

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