JP2003501262A - Austenitic rolling method and equipment for thin strip - Google Patents

Abstract

A drawback in the production of thin strips by austenitic rolling in a hot rolling line is that very thin strips are fed at high speeds (V _W ) which can create difficulties in continuous processing steps. According to the invention, the strip is wound on the rotor winder (8) as a winding strip (11) immediately after leaving the last roll stand of the rolling line (5) at a high discharge speed (V _W ). The strip is then rewound as a rewind strip (12) at a low transport speed (V _T ).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The invention comprises a rolling line consisting of a multi-roll stand, a discharge roller table with a device for cooling the rolled strip, and a winding machine for winding the strip which is arranged subsequently. It relates to a method for austenitic rolling of thin strips in hot rolling lines, preferably CSP-equipment.

[0002]

[Prior art]

Hot rolling installations for the formation of strips today are generally set up and operated in such a way that the deformation in the individual rolling roll stands takes place in the austenitic state. The rolling temperature at each rolling roll stand is the same as that of GO in the iron-carbon phase diagram.
It is ensured that it is located above the S-line. Only after the last rolling hole die is cooling to the reel temperature accompanied by a structural change in the cooling section.

In the above method, the final rolling temperature is about 8 depending on the high carbon content of the strip.
90 ° C to 930 ° C. The holding of the final rolling temperature is controlled by changing the final rolling speed, and the final rolling speed has an influence on the heat supply by the normal cooling and rolling process.

This is applicable without problems to strip thicknesses above the minimum strip thickness, which is of the order of 1.3 mm according to the rolling line type. Below this strip thickness, the required rolling speed reaches a value of 12 m / s and above, which value can no longer be suppressed in free discharge on the discharge roller table behind the rolling line, because of the heat The interstitial strip is no longer completely guided on the discharge roller table at this high speed and cannot be subsequently wound.

Furthermore, the rolling process is characterized by a non-constant strip temperature (strip width and strip thickness at the end of the rough strip compared to the rough strip tip during rolling on the finishing line, rapid cooling). is there.

A development trend is toward reducing the strip thickness to 1.3 mm or less. In this case, in particular, in order to achieve a final rolling speed which can be suppressed by this method, it is required to lower the final rolling temperature.

German Patent Application No. 195 38 341 describes a production facility for the production of thin strips with a thickness of up to 1 mm, in which austenitic rolling is first carried out to 5 to 15 mm and After that, at a temperature of 850 ° C or higher, approximately 1 mm
Ferrite state rolling is performed to the strip thickness. For this purpose, firstly, the first roll stand of the rolling line is formed as a reversible roll stand, on which at least one reel furnace is arranged in each case, front and rear, which is followed by the reel furnace carried out before it. A controllable cooling device is provided between it and the reversible roll stand.

In the unpublished European patent application No. 97120406.0, in order to make the strip temperature uniform-so that the hot strip can be rolled to a thickness of 1 mm or less) -Reversible roll stand It has been proposed to arrange an equilibrium furnace between the hot strip finishing line and the hot strip finishing line, the equilibrium furnace being provided for each rough strip having a rough strip thickness with a large number of receiving spaces for the strips being able to be heated sufficiently. The heating time is secured and the total heating time contributes to the multiplexing of rolling time in the hot strip finishing line. A rough strip of uniform temperature is thus formed, which creates the best premise for rolling the strip with the minimum final strip thickness.

In order to be able to roll austenitic thin strips in CSP-equipment, extremely high discharge speeds (approximately 20 m / s) are required. However, reliable transport of the rolled strip on the discharge roller table is possible only at a maximum of 12 m / s and until the tip of the strip discharged from the last roll stand is gripped and wound by the underfloor reel. Is. Only then can the rolling line be accelerated to a higher discharge rate. In such a rolling strategy, different rolling conditions and different rolling conditions between the last roll stand and the underfloor reel are:
This leads to the fact that the rolled strip leading edge does not have the desired mechanical material properties. This is only achieved if it has already been rolled around 130 m, which reduces the yield of the rolling line.

[0010]

[Problems to be Solved by the Invention]

Starting from this known prior art, the object of the present invention is that the high final rolling rate or discharge rate, which occurs in the production of thin strips of 1.2 mm or less, is associated with additional heating or cooling, for example poor yield. It is an object of the present invention to provide such a method that the drawbacks of known methods and equipment, such as rate or high equipment cost, can be largely avoided.

[0011]

[Means for Solving the Problems]

This problem is solved by the characterized features of claim 1 in a hot rolling line, preferably a CSP-equipment. Advantageous configurations of the invention are described in the dependent claims.

For the rolling of extremely thin strips, according to the invention, a winder, for example a roller reel, is swiveled in behind the last roll stand and in front of the discharge roller table of the rolling line. It The first strip is wound at its high discharge speed onto a first coil on a first winding shaft of a rotor reel, and then the winding shaft of the rotor reel is
It is turned 80 degrees. On the other hand, the first strip has a gentle transport speed (up to 12.5 m /
When rewound in s) and conveyed to the underfloor reel via the discharge roller table, the next strip is wound on the second coil at its high discharge speed on the second winding shaft of the rotor reel. To be turned. The winding shaft of the rotor reel can then be swiveled 180 ° and the next strip wound. In this way winding and unwinding can be carried out continuously.

Immediately after the strip leaves the last rolling roll stand, it is wound up at its high final rolling speed or discharge speed, but—ie with a clearly slower conveying speed—
By being immediately rewound, the rolling line is interrupted from the discharge roller table, whereby a high final rolling or discharge speed and a low conveying speed are possible at the same time and a discharge speed of 12.5 m / s or more, for example 20 m / s. And, even if the transport speed is clearly slower than or equal to 12.5 m / s, the drawbacks and problems due to the too high discharge speed no longer occur.

The effect on the bloom or coil train is not affected by the winding and unwinding measures, since according to the invention the winding of the next strip is already carried out during the unwinding. Since the winding, which takes place on the basis of the high speed, ends earlier than the simultaneous unwinding of the preceding strip, the rotor reel is swiveled 180 ° only at the end of the unwinding stroke. In the subsequently wound coil, a small pause is provided, which leads advantageously to the temperature equilibration of the different strip areas. Another advantage of the invention is that the strip ends are exchanged with each other after winding and unwinding and the original strip ends are first guided on the discharge roller table for cooling.

The rolling installation for carrying out the method according to the invention comprises a winder, for example a rotor reel, which is swiveled into the rolling line immediately after the last rolling roll stand and before the discharge roller table. 2 and the rotor reel was shifted 180 °
It is configured by using one winding shaft and is formed so as to be rotatable by 180 ° by the winding shaft.

Other advantages, details and characteristics of the invention are explained in more detail below on the basis of the embodiments represented in the schematic drawings.

[0017]

EXAMPLES FIG. 1 shows a continuous casting installation 1, which is intended for 2-strand installations,
One shear 2, an equilibrium furnace 3, another shear 4, and a multi-roll stand rolling line 5 are connected to the 2-strand facility. Behind the rolling line 5 there is a discharge roller table 10 with a cooling device 6 and a turning roller 9 with a subsequently arranged underfloor reel 7 for winding up the finished strip.

According to the present invention, in this conventional hot rolling line, immediately after the last roll stand of the rolling line 5, the rotor reel 8 provided with the two winding shafts 8 ′, 8 ″ is provided on the rolling line. It turns and is charged. The strip coming out of the rolling line, i.e. from the roll stand, passes through the first turning roller 9'in this rotor reel 8 on the winding shaft 8 '.
Guided as a winding strip 11 on top. 180 for the first winding shaft 8 '
By means of the second winding shaft 8 ″ that has been displaced, the strip as the winding strip 12 is returned to the rolling line for the discharge roller table 10 again via the second turning roller 9 ″. Since both winding shafts 8 ', 8''of the rotor reel 8 are drivable independently of each other, different winding and unwinding speeds are possible according to the invention.

FIG. 1 depicts the strip speed controlled in the hot rolling line in FIG.
Is schematically adapted to. A thin bloom is cast by V _Bramme or V _B and sent to the equilibrium furnace 3 and rolling line 5. This is done at the discharge speed V _Walzen or W _W , at which speed the thin strip 11 finished rolling is wound up on the rotor reel 8. The preceding strip from the rotor reel 8 is conveyed as a rewinding strip 12 at a speed V _Transport or V _T to the underfloor rotor reel 7 via a discharge roller table 10.

In FIG. 3, the partial cutaway of FIG. 1 is represented in a schematic plan view. The strip discharged from the rolling roll stand 5 at the winding speed V _W is as follows:
1- It is wound up on the winding shaft 8 ′ of the rotor winding frame 8. At the same time, the unwinding strip is unwound at the transport speed V _T by the second winding shaft 8 ″ of the rotor reel 8 which is arranged behind the winding shaft 8 ′ in the transport direction.

As soon as the unwinding strip 12 has completely left the winding shaft 8 ″, the winding strip 11 has already been completely wound up in advance due to the high winding speed V _W- wound around the rotation point 15. 180 degree rotation of the take-up shafts 8'and 8 "is performed,
Thereby, both winding shafts 8'and 8 "exchange their positions. Empty rewind 8 '
′ Is then in the position of the preceding winding shaft 8 ′ and the filled winding shaft 8 ′ is in the position of the preceding rewinding shaft 8 ″.

Since this position exchange can take place on the winding shafts 8 ′ and 8 ″,
Both winding shafts 8'and 8 '' are arranged offset from each other by 180 °, so that each winding shaft 8 ', 8''is in the same alignment position as the preceding winding shaft after the position change. .

The swiveling of the winding shafts 8 ′, 8 ″ for the position exchange can be carried out in any direction corresponding to the double arrow 14, but also in only one direction, eg clockwise. .

The reel 8 corresponds to the arrow direction 13 because the measures of the invention are not necessary when rolling hot strips with a low discharge speed V _W and the strips can be fed directly to the cooling section. It is arranged so that it can be swung into the rolling line laterally, and can be swung out and discharged. However, charging and discharging-not shown-can also be carried out in the rolling line from below.

In plan view in FIG. 4, another possible embodiment of the invention is represented. In this example of FIG. 4, both winding shafts 8 ′ and 8 ″ are arranged side by side rather than front and rear as in FIG. The position exchange is again carried out by the rotation of both winding shafts 8 ', 8 "in the direction of the arrow 180 by 180 DEG, but around the rotation point 16 which is arranged laterally of the winding strips 11 and 12. Be seen.

Subsequently, in the table, the time required during the production of the thin strip is compared as an example.

┌───────────┬───────────┬──────────┐ │Bloom casting │ rolled to 0.8 mm │ winding Return / Cooling │ │ 50 × 50mm │ Wrapping │ │ ├───────────┼───────────┼──────────┤ │ V _B = 5.5 m / min│ V _W = 20 m / s │V _T = 12.5 m / s│ ├───────────┼───────────┼ ──────────┤ │ 9min / Bloom │ Winding 2.6min │ Swiveling = 0.3min │ │ (2-continuous casting equipment) │ Pause 1.6min │ Rewinding = 4.2min │ │ │ Turn 0.3min │ │ ├───────────┼───────────┼──────────┤ │Bloom row │Coil row │ Coil row | | = 4.5 mi │ = 4.5min │ = 4.5min │ └───────────┴───────────┴──────────┘

[0028] From the table, the measures of the invention make it possible to understand only for the time shifts corresponding to the bloom train in which the rolled strip is fed to the cooling section.

The invention is not limited to the examples shown and described, but depending on the design of the hot rolling line present or to be envisaged, the thin strip is wound up immediately after rolling at its high discharge rate and is suitable. Given the basic idea of the invention of rewinding due to the low speeds that have been applied, it is possible to adapt to a given situation.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional rolling line provided with a rotor reel corresponding to the present invention.

FIG. 2 is a diagram showing a state where strip speeds are different in a process of a rolling line.

[Figure 3]     FIG. 3 is a plan view of a fractured part of the rolling line according to FIG.

[Figure 4]     FIG. 4 is a plan view of a broken portion of a rolling line according to another embodiment of the present invention.

[Explanation of symbols]

5 Rolling line 6 Cooling device 7 Winder 8 Winder 11 Winding strip 12 Rewinding strip V _W Strip exit speed V _T Strip transport speed

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] May 23, 2001 (2001.5.23)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Contents of correction]

[0008] The patent application (European patent application No. 97120406.0) describes a reversible roll in order to make the strip temperature uniform-so that the hot strip can be rolled to a thickness of 1 mm or less. It is proposed to arrange an equilibrium furnace between the stand and the hot strip finishing line, the equilibrium furnace being provided for each rough strip having a rough strip thickness with a large number of receiving spaces for the strips being sufficiently heatable. The total heating time is secured, and the total heating time contributes to the multiplexing of rolling time in the hot strip finishing line. A rough strip of uniform temperature is thus formed, which creates the best premise for rolling the strip with the minimum final strip thickness. Paper (London, GB of Bd226, Fuel u. Metallurg.
icical journals Ltd. CSP Thin Slab Around-Up, NO. 5, 175, 176, 178), a layout of a CSP-equipment consisting of two casting lines, one roll stand rolling line and a cooling section is described. The rolling section is followed by a reel with two winding shafts positioned horizontally on a vertical rotating disc. The take-up axis oriented towards the rolling line serves for winding the strip leaving the rolling line. After winding, both winding shafts are turned 180 °. On the other hand, when the strip is finish-wound into one coil on the winding shaft that is oriented in the direction opposite to the rolling line,
For the next strip-without a time delay-an empty winding shaft is used for winding.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Contents of correction]

In order to be able to roll austenitic thin strips in CSP-equipment, extremely high discharge speeds (approximately 20 m / s) are required. However, reliable transport of the rolled strip on the discharge roller table is possible only at a maximum of 12 m / s and until the tip of the strip discharged from the last roll stand is gripped and wound by the underfloor reel. Is. Only then can the rolling line be accelerated to a higher discharge rate. In such a rolling strategy, different rolling conditions and different rolling conditions between the last roll stand and the underfloor reel are:
This leads to the fact that the rolled strip leading edge does not have the desired mechanical material properties. This is only achieved if already about 130 m has been rolled, which reduces the yield of the rolling line.

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Claims (6)

[Claims] 1. A multi-roll stand rolling line (5), a discharge roller table (10) with a device (6) for cooling the rolled strip, and the winding of the strip that is arranged subsequently. In a hot rolling mill, preferably a CSP-equipment, for the austenite rolling of thin strips, the strips leaving the last rolling roll stand of the rolling line (5). Immediately after it is wound on the winder (8) as a winding strip (11) with its exit speed (V _W ), and immediately after that, the rewinding strip (12) is moved at a slow transfer speed (V _T ).
) Is rewound again as the austenite state rolling method. 2. The exit velocity (V _W ) is equal to or greater than 12.5 m / s and the conveying velocity (V _T ) is equal to or less than 12.5 m / s. The method of claim 1. 3. A continuous process stroke, in which the winding strip (11) at its exit speed (V _W ) on the winding shaft (8 ') of the winder (8), for example After being wound onto the rotor reel and subsequently swiveling the winder (8) by 180 °, it is rewound as a rewinding strip (12) with a modified transport speed (V _T ), at the same time. 3. The second strip (8 ") of the winder (8) is characterized in that the following strip is wound as a new winding strip (11) at its outlet speed ( _VW ). The method according to 1 or 2. 4. A discharge roller table (10) for carrying out the method according to claim 1, comprising a rolling line (5) of a multi-roll stand and a device (6) for cooling the rolled strip. ) And a winder (7) for winding the strip which is arranged subsequently, preferably in a rolling mill for the austenitic rolling of thin strips in a CSP-plant. A winding machine (8) rotatable by 180 °, preferably a rotor reel, is arranged between the last roll stand of the rolling line (5) of the plurality of roll stands and the discharge roller table (10). Said rolling equipment characterized by the above-mentioned. 5. Independent winding axes (8) offset from each other by 180 °
Rolling installation according to claim 4, characterized in that a winding machine (8) is provided which is provided with a ′ ′) and a rewinding shaft (8 ″). 6. Rolling equipment according to claim 4 or 5, characterized in that the winding machine (8) is formed so that it can be swung into the rolling line.