EP3685930B1 - Local varying of the roll gap in the area of the edges of a rolled strip - Google Patents

Description

Field of technology

The present invention relates to the technical field of rolling mill technology, specifically the hot rolling of a metallic material, in particular steel or aluminum, to form a rolled strip in a rolling stand.

State of the art

From the WO 2017/215595 A1 it is known that the upper and the lower work roll of a roll stand each have a conical section, an inwardly extending running surface and a cylindrical shoulder. The upper work roll is installed in the roll stand in the opposite direction to the lower work roll. To extend a rolling campaign, it is provided that the work rolls are moved in opposite axial directions during rolling. One edge of the rolled strip always rests on the edge between the conical section and the running surface. With this measure, the service life of the work rolls during a rolling campaign can be extended to 150 km and more without changing or regrinding the work rolls. How the roll gap between the upper and the lower work roll can be specifically changed locally in the area of the strip edges of the rolled strip is not apparent from the document.

Summary of the invention

The object of the invention is to provide a method and a device for locally changing the roll gap in the area of the strip edges of a strip rolled in a roll stand. The roll gap should be able to be increased or decreased in a targeted manner locally in the area of the strip edges of the strip during hot rolling without changing the roll gap globally. A local change in the roll gap should lead to a local change in the decrease in thickness in the area of the strip edges of the strip. The local change in the roll gap should be able to influence the flatness or the profile of the strip. Nevertheless, it should be possible to maintain the uninterrupted hot rolling of the strip in the roll stand over a long period of time without the work rolls having to be changed or reground.

The object according to the invention is achieved by a method according to claims 1 to 4 and by a device according to claim 7. Preferred embodiments are in each case the subject matter of the dependent claims.

• eine obere Arbeitswalze und eine untere Arbeitswalze, wobei jede Arbeitswalze zwei Enden aufweist zum rotatorischen Lagern der Arbeitswalze in Einsatzstücken,
• wobei jede Arbeitswalze in axialer Richtung einen kegelförmigen Abschnitt und nachfolgend eine Lauffläche aufweist,
• wobei die obere Arbeitswalze in umgekehrter Richtung zur unteren Arbeitswalze eingebaut ist,
• wobei jede Arbeitswalze eine separate Verschiebeeinrichtung zum axialen Verschieben der Arbeitswalze aufweist, umfassend die Verfahrensschritte:
• Warmwalzen eines Walzguts in dem Walzgerüst, wobei die radiale Erstreckung der Lauffläche einer Arbeitswalze während des Walzens um Δr abnimmt,
• axiales Verschieben der Arbeitswalzen in entgegengesetzte Richtungen um einen Verschiebeweg $s>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$
  
  , wobei Δr den Verschleiß der Lauffläche in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts der jeweiligen Arbeitswalze angibt.

A local change in the roll gap means a local change (reduction or enlargement) of the roll gap, ie a change (reduction or enlargement) of the roll gap which affects the area of the strip edges of a rolled strip. As a result, the roll gap can be changed locally in the area of the strip edges without changing the global roll gap - which is set, for example, by the vertical distance between the upper and the lower work roll. The local area of the band edges can make up, for example, up to 20% of the band width. In the case of a non-local, ie global, change in the roll gap, the roll gap is changed over the entire width of the strip. An increase in the roll gap leads to a smaller decrease in thickness; a reduction in the roll gap leads to a greater decrease in thickness. On the one hand, the object according to the invention is achieved by a method for the local enlargement of a roll gap in the area of the strip edges of a rolled strip in a roll stand according to claim 1, wherein the roll stand comprises:

• an upper work roll and a lower work roll, each work roll having two ends for the rotational mounting of the work roll in inserts,
• wherein each work roll has a conical section in the axial direction and subsequently a running surface,
• with the upper work roll installed in the opposite direction to the lower work roll,
• wherein each work roll has a separate displacement device for axially displacing the work roll, comprising the process steps:
• Hot rolling of a rolling stock in the roll stand, the radial extent of the running surface of a work roll decreasing by Δr during rolling,
• axial displacement of the work rolls in opposite directions by a displacement path $s>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$
  
  , where Δr indicates the wear of the running surface in the radial direction and α indicates the angle of inclination of the conical section of the respective work roll.

In relation to the work rolls, a local enlargement of the roll gap in the area of the strip edges is accompanied by a reduction of at least one local roll diameter of the work rolls in the area of the strip edges.

verschoben, wird der lokale Walzspalt im Bereich der Bandkanten des Bands vergrößert, wodurch das Profil bzw. die Planheit des gewalzten Bands gezielt beeinflusst werden kann. Durch das lokale Vergrößern des Walzspalts im Bereich der Bandkanten wird das Band in diesem Bereich etwas dicker als in anderen Bereichen (mit anderen Worten wird der sog. edge drop im Bereich der Bandkanten reduziert), was sich direkt und unmittelbar auf das Profil bzw. die Planheit des Bands auswirkt. Vereinfacht ausgedrückt werden die Bandkanten bzw. der Bereich der Bandkanten des Bands durch das lokale Vergrößern des Walzspalts im Bereich der Bandkanten entlastet. Δr gibt den Verschleiß der Lauffläche einer Arbeitswalze in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts der jeweiligen Arbeitswalze an.The roll stand and the work rolls of the roll stand are, for example, according to FIG WO 2017/215595 educated. In the present invention, however, it is not absolutely necessary for the running surfaces of the work rolls to run inwards are. The rolling stock is hot-rolled in the roll gap between the upper and lower work rolls of the roll stand, the work rolls being worn out by contact with the rolling stock. Specifically, the running surfaces of the work rolls are worn, with the radius of the running surfaces decreasing by Δr. In order to avoid wear edges in the running surfaces of the work rolls, the work rolls are shifted in opposite axial directions, for example the upper work roll to the right and the lower work roll to the left. If a respective work roll is moved by a displacement path $s>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

shifted, the local roll gap is enlarged in the area of the strip edges of the strip, whereby the profile or the flatness of the rolled strip can be influenced in a targeted manner. Due to the local enlargement of the roll gap in the area of the strip edges, the strip becomes somewhat thicker in this area than in other areas (in other words, the so-called edge drop in the area of the strip edges is reduced), which has a direct and immediate effect on the profile or the Affects the flatness of the belt. To put it simply, the strip edges or the area of the strip edges of the strip are relieved by the local enlargement of the roll gap in the area of the strip edges. Δr indicates the wear of the running surface of a work roll in the radial direction and α the angle of inclination of the conical section of the respective work roll.

eingestellt werden. Δ̇r gibt die Geschwindigkeit des Verschleißes der Lauffläche einer Arbeitswalze in radialer Richtung an. Hierbei ist es möglich, dass die Verschiebegeschwindigkeit v über eine längere Zeit auf einen Wert größer als $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

eingestellt wird, oder dass die Verschiebegeschwindigkeit v nur innerhalb eines begrenzten Zeitfensters während des Betriebs auf einen Wert größer als $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

eingestellt wird.In a manner equivalent to this, for the local enlargement of a roll gap in the area of the strip edges of a rolled strip, the axial displacement speed v, ie the first time derivative of the displacement path s, of the work roll can be set to a value $v\equiv \dot{s}>\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

can be set. Δ̇r indicates the speed of wear of the running surface of a work roll in the radial direction. It is possible that the displacement speed v over a longer period of time to a value greater than $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is set, or that the displacement speed v is only within a limited time window during operation to a value greater than $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is set.

• eine obere Arbeitswalze und eine untere Arbeitswalze, wobei jede Arbeitswalze zwei Enden aufweist zum rotatorischen Lagern der Arbeitswalze in Einsatzstücken,
• wobei jede Arbeitswalze in axialer Richtung einen kegelförmigen Abschnitt und nachfolgend eine Lauffläche aufweist,
• wobei die obere Arbeitswalze in umgekehrter Richtung zur unteren Arbeitswalze eingebaut ist,
• wobei jede Arbeitswalze eine separate Verschiebeeinrichtung zum axialen Verschieben der Arbeitswalze aufweist, umfassend die Verfahrensschritte:
• Warmwalzen eines Walzguts in dem Walzgerüst, wobei die radiale Erstreckung der Lauffläche einer Arbeitswalze während des Walzens um Δr abnimmt,
• axiales Verschieben der Arbeitswalzen in entgegengesetzte Richtungen um einen Verschiebeweg $s<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$
  
  , wobei Δr den Verschleiß der Lauffläche in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts der jeweiligen Arbeitswalze angibt.

On the other hand, the object according to the invention is achieved by a method for locally reducing a roll gap in the area of the strip edges of a rolled strip in a roll stand according to claim 3, the roll stand comprising:

• an upper work roll and a lower work roll, each work roll having two ends for the rotational mounting of the work roll in inserts,
• wherein each work roll has a conical section in the axial direction and subsequently a running surface,
• with the upper work roll installed in the opposite direction to the lower work roll,
• wherein each work roll has a separate displacement device for axially displacing the work roll, comprising the process steps:
• Hot rolling of a rolling stock in the roll stand, the radial extent of the running surface of a work roll decreasing by Δr during rolling,
• axial displacement of the work rolls in opposite directions by a displacement path $s<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$
  
  , where Δr indicates the wear of the running surface in the radial direction and α indicates the angle of inclination of the conical section of the respective work roll.

In relation to the work rolls, there is a local reduction in the roll gap in the area of the strip edges of the strip an increase in at least one local roll diameter of the work rolls in the area of the strip edges.

verschoben. Dadurch wird der lokale Walzspalt im Bereich der Bandkanten des gewalzten Bands verkleinert, wodurch das Profil bzw. die Planheit des gewalzten Bands gezielt beeinflusst werden kann. Durch das lokale Verkleinern des Walzspalts im Bereich der Bandkanten wird das Band in diesem Bereich etwas dünner als in anderen Bereichen (mit anderen Worten wird der sog. edge drop im Bereich der Bandkanten gesteigert), was sich direkt und unmittelbar auf das Profil bzw. die Planheit des Bands auswirkt. Vereinfacht ausgedrückt werden die Bandkanten bzw. der Bereich der Bandkanten des Bands durch das lokale Verkleinern des Walzspalts im Bereich der Bandkanten belastet. Δr gibt wiederum den Verschleiß der Lauffläche einer Arbeitswalze in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts der jeweiligen Arbeitswalze an.Also in the embodiment according to claim 3, the roll stand or the work rolls of the roll stand can, for example, according to FIG WO 2017/215595 be trained. Here, too, it is not absolutely necessary for the running surface of the work rolls to run inwards. In contrast to claim 1, a respective work roll is displaced by a distance $s<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

postponed. As a result, the local roll gap in the area of the strip edges of the rolled strip is reduced, whereby the profile or the flatness of the rolled strip can be influenced in a targeted manner. By locally reducing the roll gap in the area of the strip edges, the strip becomes somewhat thinner in this area than in other areas (in other words, the so-called edge drop in the area of the strip edges is increased), which has a direct and immediate effect on the profile or the Affects the flatness of the belt. To put it simply, the strip edges or the area of the strip edges of the strip are stressed by the local reduction of the roll gap in the area of the strip edges. Δr in turn indicates the wear on the running surface of a work roll in the radial direction and α the angle of inclination of the conical section of the respective work roll.

eingestellt werden. Δ̇r gibt die Geschwindigkeit des Verschleißes der Lauffläche einer Arbeitswalze in radialer Richtung an. Auch hierbei ist es möglich, dass die Verschiebegeschwindigkeit v über eine längere Zeit auf einen Wert kleiner als $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

eingestellt wird, oder dass die Verschiebegeschwindigkeit v nur innerhalb eines begrenzten Zeitfensters während des Betriebs auf einen Wert kleiner als $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

eingestellt wird.In a manner equivalent to this, for local reduction of a roll gap in the area of the strip edges of a rolled strip, the axial displacement speed v, ie the first time derivative of the displacement path s, of the work roll can be set to a value $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

can be set. Δ̇r indicates the speed of wear of the running surface of a work roll in the radial direction. Here, too, it is possible that the displacement speed v over a longer period of time to a value less than $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is set, or that the displacement speed v only within a limited time window during operation to a value less than $\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is set.

Thus, the methods according to claims 1 and 2 cover opposite objectives compared with claims 3 and 4. According to claims 1 and 2, the local roll gap in the area of the strip edges is increased and the strip edges are relieved, whereas according to claims 3 and 4 the local roll gap in the area of the strip edges is reduced and the strip edges are loaded. In both cases, the area of the band edges can comprise up to 20% of the band width.

In particular when hot rolling very thin strips, for example with a thickness between 0.5 and 2 mm, in a roll stand, the method according to the invention influences primarily the flatness and, to a lesser extent, the profile of the strip. This is due to the fact that the so-called cross flow is low in the case of very thin strips. In contrast, when the method according to the invention is used in the case of strips with a thickness of> 2 mm, it is primarily the profile and, to a lesser extent, the flatness of the strip that is influenced.

bzw. einer Verschiebegeschwindigkeit $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

zu einer lokalen Verkleinerung des Walzspalts im Bereich der Bandkanten des Bands und zu einer Belastung der Bandkanten führt. Andererseits hat sich herausgestellt, dass ein axiales Verschieben einer Arbeitswalze um einen Verschiebeweg $\mathit{\Delta s}>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

bzw. einer Verschiebegeschwindigkeit v ≡ ṡ > $\frac{\Delta \dot{r}}{\tan \left(\alpha \right)}$

zu einer lokalen Vergrößerung des Walzspalts im Bereich der Bandkanten des Bands und zu einer Entlastung der Bandkanten führt.Investigations by the applicant have shown that the profile and / or the flatness of the rolled strip can be influenced in a targeted manner via the axial displacement path s or the axial displacement speed v of the work rolls as a function of the wear Δr or the speed of wear Δ̇r. It has been found that an axial displacement of a work roll by a displacement path $\mathit{\Delta s}<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

or a shift speed $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

leads to a local reduction of the roll gap in the area of the strip edges of the strip and to a load on the strip edges. On the other hand, it has been found that an axial displacement of a work roll by a displacement path $\mathit{\Delta s}>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

or a displacement speed v ≡ ṡ > $\frac{\Delta \dot{r}}{\tan \left(\alpha \right)}$

leads to a local enlargement of the roll gap in the area of the strip edges of the strip and to a relief of the strip edges.

• eine obere Arbeitswalze und eine untere Arbeitswalze, wobei jede Arbeitswalze zwei Enden aufweist zum rotatorischen Lagern der Arbeitswalze in Einsatzstücken,
• wobei jede Arbeitswalze in axialer Richtung einen kegelförmigen Abschnitt und nachfolgend eine Lauffläche aufweist,
• wobei die obere Arbeitswalze in umgekehrter Richtung zur unteren Arbeitswalze angeordnet ist,
• je eine separate Verschiebeeinrichtung für die obere und die untere Arbeitswalze zum axialen Verschieben der Arbeitswalze,
• eine Einrichtung zur Bestimmung des Verschleißes Δr oder der Geschwindigkeit des Verschleißes Δ̇r der Lauffläche in radialer Richtung,
• ein Messgerät zur Bestimmung des Profils und/oder der Planheit des gewalzten Bands, wobei das Messgerät in Massenflussrichtung nach dem Walzgerüst angeordnet ist,
• eine Regeleinrichtung zum axialen Verschieben der Arbeitswalzen in entgegengesetzte Richtungen in Abhängigkeit des Verschleißes Δr oder der Geschwindigkeit des Verschleißes Δ̇r der Arbeitswalzen, sowie des gemessenen Profils PR_Ist und/oder der gemessenen Planheit PL_Ist des gewalzten Bands, wobei die Regeleinrichtung mit der Einrichtung zur Bestimmung des Verschleißes Δr oder der Geschwindigkeit des Verschleißes Δ̇ r und dem Messgerät zur Bestimmung des Profils und/oder der Planheit des gewalzten Bands signaltechnisch verbunden ist.

The object according to the invention is also achieved by a device for locally changing a roll gap in the area of the strip edges of a rolled strip in a roll stand according to claim 7, the roll stand comprising:

• an upper work roll and a lower work roll, each work roll having two ends for the rotational mounting of the work roll in inserts,
• wherein each work roll has a conical section in the axial direction and subsequently a running surface,
• the upper work roll being arranged in the opposite direction to the lower work roll,
• a separate shifting device each for the upper and the lower work roll for the axial shifting of the work roll,
• a device for determining the wear Δr or the speed of wear Δ̇r of the running surface in the radial direction,
• a measuring device for determining the profile and / or the flatness of the rolled strip, the measuring device being arranged in the direction of mass flow after the roll stand,
• a control device for the axial displacement of the work rolls in opposite directions depending on the wear Δr or the speed of wear Δ̇ r of the work rolls, as well as the measured profile PR _actual and / or the measured flatness PL _{actual of} the rolled strip, the control device with the device for Determination of the wear Δr or the speed of wear Δ̇ r and the measuring device for determining the profile and / or the flatness of the rolled strip is connected by signaling.

The device according to the invention is suitable both for the local enlargement and also for the local reduction in size of a roll gap in the area of the strip edges of a rolled strip in a roll stand. By enlarging or reducing the roll gap in the area of the strip edges, the profile and / or the flatness of the strip can be influenced in a targeted manner.

The device for determining the radial wear or the rate of wear Δ̇ r of the running surface of the work rolls determines the wear on the running surface in the radial direction. The determination can be made either by measurement, or preferably with the aid of a wear model, which _{takes into account, for example, the rolling force F, the distance covered by the work roll s circumference} and / or the rolling time. The path covered by the work roll is _{determined according to s circumference} = r.ϕ, where ϕ indicates the angle in radians for the revolutions covered by the work roll. For further details on the wear model, please refer to the EP 2 548 665 B1 referenced.

The measuring device for determining the profile or the flatness of the rolled strip can either contact the measured variables, eg optically or electromagnetically, or with contact, eg by means of a measuring roller. Here, the measuring device is arranged in the direction of mass flow after the roll stand, but preferably before a cooling section for cooling the hot-rolled strip.

In an advantageous embodiment, the means for determining the wear .DELTA.R or the speed of wear of Δ r of the tread with a thickness measuring device for measuring the thickness of the rolled strip, and means for determining the distance between the upper and lower work rolls, respectively. The wear or the rate of wear can be determined from the, typically vertical, distance between the work rolls and the measured thickness of the strip.

According to an alternative embodiment, the device for determining the wear Δr or the rate of wear Δ̇ r of the running surface has a wear model (see FIG EP 2 548 665 B1 ), wherein the wear model is connected to at least one of the group of a rolling force measuring device for determining the rolling force F, the distance covered by the work _{roll s circumference} and a clock for determining the rolling time.

The displacement device itself can be, for example, an electromechanical (e.g. a ball screw with an electric motor) or a hydraulic drive.

Brief description of the drawings

• Fig 1 eine schematische Darstellung eines Walzgerüsts mit einer oberen und einer unteren Arbeitswalze zur lokalen Veränderung des Walzspalts im Bereich der Bandkanten eines gewalzten Bands
• Fig 2 eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zur lokalen Veränderung des Walzspalts im Bereich der Bandkanten eines gewalzten Bands mit dem Walzgerüst nach Fig 1
• Fig 3a...3d eine Darstellung eines nicht erfindungsgemäßen Verfahrens zum Warmwalzen eines gewalzten Bands in einem Walzspalt eines Walzgerüsts
• Fig 4a...4d eine Darstellung eines nicht erfindungsgemäßen Verfahrens zum Warmwalzen eines Bands in einem Walzspalt eines Walzgerüsts, wobei das Verschieben der Arbeitswalzen dem Verschleiß folgt
• Fig 5a...5d eine Darstellung eines erfindungsgemäßen Verfahrens zur lokalen Vergrößerung eines Walzspalts im Bereich der Bandkanten eines gewalzten Bands
• Fig 6a...6d eine Darstellung eines erfindungsgemäßen Verfahrens zur lokalen Verkleinerung eines Walzspalts im Bereich der Bandkanten eines gewalzten Bands
• Fig 7 eine schematische Darstellung eines Abschnitts einer Arbeitswalze
• Fig 8 einer schematische Darstellung der Bereiche der Bandkanten eines gewalzten Bands

Further advantages and features of the present invention emerge from the following description of non-restrictive exemplary embodiments, the figures showing:

• Fig 1 a schematic representation of a roll stand with an upper and a lower work roll for local modification of the roll gap in the area of the strip edges of a rolled strip
• Fig 2 a schematic representation of a device according to the invention for locally changing the roll gap in the area of the strip edges of a rolled strip with the roll stand Fig 1
• Fig 3a ... 3d an illustration of a method not according to the invention for hot rolling a rolled strip in a roll gap of a roll stand
• Fig 4a ... 4d an illustration of a method not according to the invention for hot rolling a strip in a roll gap of a roll stand, the displacement of the work rolls following the wear
• Fig 5a ... 5d a representation of a method according to the invention for the local enlargement of a roll gap in the area of the strip edges of a rolled strip
• Fig 6a ... 6d a representation of a method according to the invention for local reduction of a roll gap in the area of the strip edges of a rolled strip
• Fig 7 a schematic representation of a section of a work roll
• Fig 8 a schematic representation of the areas of the strip edges of a rolled strip

Description of the embodiments

the Figure 1 shows schematically a roll stand 2 as part of a device for locally changing a roll gap in the area of the strip edges 10 of a rolled strip 1. By specifically changing the roll gap in the area of the strip edges 10, the profile and / or the flatness of the strip 1 during hot rolling to be influenced. The rolling stock is hot-rolled in the roll gap between the upper work roll 3 and the lower work roll 4. Each work roll 3, 4 has two ends 5, each of which is slidably installed in a chock 6 in a roll stand, not shown, of the roll stand 2. In addition, each work roll 3, 4 comprises a conical section 7 and a running surface 8 (see also Fig 7 ). The upper work roll 3 is installed in the roll stand 2 in the opposite direction to the lower work roll 4. The upper and lower work rolls 3, 4 can be displaced in the axial direction via separate displacement devices 9 during operation. The upper work roll 3 is shifted to the right during operation; the lower work roll 4, however, to the left (see arrows). In addition, the global roll gap between the upper and lower work rolls 3, 4 can be adjusted by adjusting devices 16. In order to be able to detect the wear of the running surface 8 of the upper work roll 3 during operation, the upper work roll has a device for determining the wear 11 or a wear model. A single device 11 or a single wear model is sufficient if the work rolls 3, 4 are made of the same material. Of course, it is also possible that the upper and the lower work roll 3, 4 each have a separate one Have device for determining the wear 11 or a wear model. The measurement of the wear Δr or the speed of wear Δ̇ r of the running surface 8 of the work rolls 3, 4 in the radial direction can be carried out with contact, for example by a roller that touches the running surface 8, or without contact, for example optically. Since the axial displacement of the work rolls in the roll stand to compensate for wear is already from the WO 2017/215595 A1 is known, this document is incorporated by reference. However, it is not known from this document how the local roll gap in the area of the strip edges of the strip can be changed in a targeted manner.

In the following figures, the representation of the backup rolls has been omitted for the sake of clarity. It is known to every person skilled in the art of rolling mill technology that backup rolls are common and counteract sagging of the work rolls.

In Fig 2 a device for locally changing the roll gap in area b of the strip edges of a rolled strip in a roll stand 2 of a five-stand finishing mill, for example in a casting-rolling compound system, is shown schematically. The rolling stock, not shown, is fed to the finishing rolling train with the rolling stands 2a to 2f via a roller table 17 and is finish-rolled there in the warm state. In the last roll stand 2, 2f, the wear Δr or the wear speed Δ̇ r of the running surfaces 8 of the work rolls 3, 4 is measured by the device 11 (see FIG Fig 1 ). Alternatively, it is also possible not to record the acquisition of Δr or Δ̇ r by measurement, but rather using a so-called wear model. The device further comprises a measuring device 12 for determining the profile or the flatness of the rolled strip. This measuring device is arranged after the roll stand 2 in the direction of mass flow. In the specific case, the actual profile PR _{ist is} fed to a control device 13. In addition to the actual profile, the control device 13 is also supplied with _{the target profile PR Soll.} The controller 13 computes, taking into account the wear .DELTA.R or the wear rate delta r, the measured profile _Pr and the target profile PR _to the displacement s, and the shifting speed s for the upper and the lower work roll 3, 4 (see Fig 1 ). As a result of the faster or slower axial displacement of the work rolls 3, 4, the local roll gap in the area of the strip edges of the strip can be changed in a targeted manner. In the case of very thin strips, this mainly affects the flatness of the strip; In contrast, the local change in the roll gap in the area of the strip edges in the case of thicker strips mainly affects the profile of the rolled strip. After finishing rolling, the rolled strip is cooled in a cooling section 18 and then conveyed out.

The methods for locally changing a roll gap in area b of the strip edges 10 of a rolled strip are described below with reference to FIG Figures 3a-3d , 4a-4d , 5a-5d and 6a-6d discussed.

In Figure 3a a strip 1 is hot-rolled in the roll gap between the upper work roll 3 and the lower work roll 4. At the beginning, the tape has a thickness D ₀ . Both work rolls 3, 4 each have two ends 5, a conical section 7 and a running surface 8. The upper work roll 3 is installed in the opposite direction to the lower work roll 4.

After a certain rolling time, the running surfaces 8 of the work rolls 3, 4 are worn in the radial direction by an amount Δr (see Fig 3b ). If the vertical distance between the two work rolls 3, 4 is kept constant, the rolled strip 1 then has a thickness of D ₀ + 2Δr. By continuing hot rolling, the running surfaces 8 of the work rolls 3, 4 are worn by the amount 2.Δr (see Fig 3c ), so that the thickness of the band 1 is then D ₀ + 4Δr.

It is possible to compensate for the change in thickness of the rolled strip 1 by adjusting at least one work roll 3 or 4 (see WO 2017/215595 A1 ).

As in Fig 3d can be seen that a detail of the Fig 3c shows, pronounced wear edges are formed in the work rolls 3, 4, which lead to a local reduction in the roll gap in the area of the strip edges 10 or a load on the strip edges of the rolled strip 1. As a result, the rolled strip 1 is thinner in the area of the strip edges 10 than in the central area of the strip 1. Since the work rolls 3, 4 are not axially displaced during hot rolling, the method is not according to the invention.

, wobei Δr den Verschleiß einer Arbeitswalze 3, 4 in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts angibt. In äquivalenter Weise kann die Verschiebung über die Geschwindigkeit des Verschleißes Δ̇r angeschrieben werden, wobei dann eine Arbeitswalze 3,4 mit einer axialen Geschwindigkeit $v\equiv \dot{s}=\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

in axialer Richtung verschoben wird. Gemäß Fig 4b beträgt der Verschleiß der Lauffläche 8 der Arbeitswalzen 3, 4 Δr ; daraus ergibt sich ein Verschiebeweg $s1=\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. Gemäß Fig 4c beträgt der Verschleiß der Lauffläche 8 der Arbeitswalze 3, 4 2.Δr ; daraus ergibt sich ein Verschiebeweg $2.s1=\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. Die obere Arbeitswalze 3 wird dabei nach rechts und die untere Arbeitswalze 4 nach links verschoben.In the Figures 4a-4d the work rolls 3, 4 are axially displaced so that an upper and a lower strip edge 10 of the strip 1 always rests on an edge between the conical section 7 and the newly formed (because worn) running surface 8 of the respective work roll 3, 4. The displacement path of a work roll 3, 4 in the axial direction follows the condition in this case $s=\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

, where Δr indicates the wear of a work roll 3, 4 in the radial direction and α indicates the helix angle of the conical section. In an equivalent way, the displacement can be determined by the speed of the wear Δ̇ r are written, then a work roll 3.4 with an axial speed $v\equiv \dot{s}=\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is shifted in the axial direction. According to Fig 4b is the wear of the running surface 8 of the work rolls 3, 4 Δ r ; this results in a displacement path $s1=\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. According to Fig 4c is the wear of the running surface 8 of the work roll 3, 4 2. Δ r ; this results in a displacement path $2.\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">s</figure-callout>}1=\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. The upper work roll 3 is shifted to the right and the lower work roll 4 to the left.

As from the Fig 4d As can be seen, this method results in the strip 1 having a constant thickness across the width in the case of a non-profiled work roll 3, 4. In other words, the rolled strip 1 is just as thin in the area of the strip edges 10 as in the central area of the strip 1. According to this method, which is not in accordance with the invention, the local roll gap in the area of the strip edges is not changed or the strip edges of the strip 10 are neither adjusted nor loaded relieved.

, wobei Δr den Verschleiß einer Arbeitswalze 3, 4 in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts angibt. In äquivalenter Weise kann die Verschiebung über die Geschwindigkeit des Verschleißes Δ̇r angeschrieben werden, wobei dann eine Arbeitswalze 3,4 mit einer axialen Geschwindigkeit $v\equiv \dot{s}>\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

in axialer Richtung verschoben wird. Gemäß Fig 5b beträgt der Verschleiß der Lauffläche 8 der Arbeitswalze 3,4 Δr ; daraus ergibt sich ein Verschiebeweg $s2>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. Gemäß Fig 5c beträgt der Verschleiß der Lauffläche 8 der Arbeitswalze 3,4 2.Δr ; daraus ergibt sich ein Verschiebeweg $2.s2>\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. Die obere Arbeitswalze 3 wird dabei nach rechts und die untere Arbeitswalze 4 nach links verschoben.In the Figures 5a-5d the work rolls 3, 4 are axially displaced in such a way that an upper and a lower strip edge 10 of the strip 1 always rests on the conical section 7 of the respective work roll 3, 4. The displacement path of a work roll 3, 4 in the axial direction follows the condition in this case $s>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

, where Δ r indicates the wear of a work roll 3, 4 in the radial direction and α indicates the angle of inclination of the conical section. In an equivalent manner, the shift can be written over the speed of wear Δ̇r, in which case a work roll 3, 4 is at an axial speed $v\equiv \dot{s}>\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is shifted in the axial direction. According to Fig 5b is the wear of the Running surface 8 of the work roll 3,4 Δ r ; this results in a displacement path $s2>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. According to Fig 5c the wear of the running surface 8 of the work roll is 3.4 2. Δ r ; this results in a displacement path $2.\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0003.png,imgf0004.png"\; state="\{\{state\}\}">s</figure-callout>}2>\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. The upper work roll 3 is shifted to the right and the lower work roll 4 to the left.

As in Fig 5d can be seen that a detail of the Fig 5c represents, the local roll gap in the area of the strip edges 10 of the rolled strip 1 is enlarged or the strip edges are relieved by this method. As a result, the rolled strip 1 is thicker in the area of the strip edges 10 than in the central area of the strip 1.

folgt, wobei Δr den Verschleiß einer Arbeitswalze 3, 4 in radialer Richtung und α den Steigungswinkel des kegelförmigen Abschnitts angibt. In äquivalenter Weise kann die Verschiebung über die Geschwindigkeit des Verschleißes Δr angeschrieben werden, wobei dann eine Arbeitswalze 3,4 mit einer axialen Geschwindigkeit $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

in axialer Richtung verschoben wird. Gemä6 Fig 5b beträgt der Verschleiß der Lauffläche 8 der Arbeitswalze 3, 4 Δr ; daraus ergibt sich ein Verschiebeweg $s3<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. Gemäß Fig 6c beträgt der Verschleiß der Lauffläche 8 der Arbeitswalze 3, 4 2.Δr ; daraus ergibt sich ein Verschiebeweg $2.s3<\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

Die obere Arbeitswalze 3 wird dabei nach rechts und die untere Arbeitswalze 4 nach links verschoben.In the Figures 6a-6d the work rolls 3, 4 are axially displaced so that the displacement path of a work roll 3, 4 in the axial direction of the condition $s<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

follows, where Δ r indicates the wear of a work roll 3, 4 in the radial direction and α indicates the helix angle of the conical section. In an equivalent manner, the shift can be written over the speed of wear Δ r , with a work roll 3, 4 then having an axial speed $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

is shifted in the axial direction. According to 6 Fig 5b is the wear of the running surface 8 of the work roll 3, 4 Δ r ; this results in a displacement path $s3<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

. According to Fig 6c is the wear of the running surface 8 of the work roll 3, 4 2. Δ r ; this results in a displacement path $2.\mathrm{<figure-callout\; id="3"\; label="s"\; filenames="imgf0005.png,imgf0006.png"\; state="\{\{state\}\}">s</figure-callout>}3<\frac{2\mathit{\Delta r}}{\tan \left(\alpha \right)}$

The upper work roll 3 is shifted to the right and the lower work roll 4 to the left.

As in Fig 6d can be seen that a detail of the Fig 6c represents, the local roll gap in the area of the strip edges 10 of the rolled strip 1 is reduced or the strip edges are loaded by this method. As a result, the rolled strip 1 is thinner in the area of the strip edges 10 than in the central area of the strip 1.

the Fig 7 shows the geometric definition of the helix angle α of the conical section 7 of a work roll.

Finally shows the Fig 8 schematically the areas b of the band edges 10 of a band 1. Typically, the longitudinal extent of the two areas b of the band edges is up to 10 or 20% of the band width B. That means that 1 area b of the band edges is up to 5 or 10% of the band width B can make out. Although the invention has been illustrated and described in more detail by the preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived from them by the person skilled in the art without departing from the scope of the invention as defined by the claims.

List of reference symbols

1

Band

2, 2a...2e

Walzgerüst

3

obere Arbeitswalze

4

untere Arbeitswalze

5

Ende einer Arbeitswalze

6

Einbaustück

7

kegelförmiger Abschnitt

8

Lauffläche

9

Verschiebeeinrichtung

10

Bandkante

11

Einrichtung zur Bestimmung des Verschleißes oder der Geschwindigkeit des Verschleißes

12

Messgerät zur Bestimmung des Profils und/oder der Planheit

13

Regeleinrichtung zum axialen Verschieben der oberen und der unteren Arbeitswalze

14

Dickenmesseinrichtung

15

Einrichtung zur Bestimmung des Abstands zwischen der oberen und der unteren Arbeitswalze

16

Anstelleinrichtung

17

Rollgang

18

Kühlstrecke

B

Breite des Bands

b

Bereich der Bandkante

D

Dicke des Bands

F

Walzkraft

PRsoll

Soll-Profil

PRIst

Ist-Profil

r

Radius

R

radiale Richtung

Δr

Verschleiß der Lauffläche in radialer Richtung

Δ̇r

Verschleißgeschwindigkeit der Lauffläche in radialer Richtung

s

Verschiebeweg

SUmfang

zurückgelegter Weg der Arbeitswalze

v

Verschiebegeschwindigkeit

X

axiale Richtung

α  Steigungswinkel des kegelförmigen Abschnitts

  erste zeitliche Ableitung

1

tape

2, 2a ... 2e

Roll stand

3

upper work roll

4th

lower work roll

5

End of a work roll

6th

Chock

7th

conical section

8th

Tread

9

Sliding device

10

Tape edge

11

Device for determining the wear and tear or the rate of wear

12th

Measuring device for determining the profile and / or flatness

13th

Control device for the axial displacement of the upper and lower work roll

14th

Thickness measuring device

15th

Device for determining the distance between the upper and the lower work roll

16

Adjusting device

17th

Roller table

18th

Cooling section

B.

Width of the band

b

Area of the belt edge

D.

Thickness of the tape

F.

Rolling force

PRsoll

Target profile

PRIst

Actual profile

r

radius

R.

radial direction

Δr

Wear of the running surface in the radial direction

Δ̇r

Wear speed of the running surface in the radial direction

s

Displacement

Range

Distance covered by the work roll

v

Moving speed

X

axial direction

α angle of inclination of the conical section

first time derivative

Claims (10)

1. Method for locally increasing the size of a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2), the rolling stand (2) comprising:

   - an upper working roller (3) and a lower working roller (4), each working roller (3, 4) having two ends (5) for the rotational mounting of the working roller (2, 3) in chocks (6),

   - wherein each working roller (3, 4) has in the axial direction (X) a conical portion (7) followed by a running surface (8),

   - wherein the upper working roller (3) is fitted in the opposite direction to the lower working roller (4),

   - wherein each working roller has a separate displacing device (9) for axially displacing the working roller (3, 4), comprising the method steps of:

   - hot rolling a rolled stock in the rolling stand (2), the radial extent of the running surface (8) of a working roller (3, 4) decreasing by Δr during the rolling,

   - axially displacing the working rollers (3, 4) in opposite directions by a displacement distance $s>\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

   

   , where Δr indicates the wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).
2. Method for locally increasing the size of a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2), the rolling stand (2) comprising:

   - an upper working roller (3) and a lower working roller (4), each working roller (3, 4) having two ends (5) for the rotational mounting of the working roller (2, 3) in chocks (6),

   - wherein each working roller (3, 4) has in the axial direction (X) a conical portion (7) followed by a running surface (8),

   - wherein the upper working roller (3) is fitted in the opposite direction to the lower working roller (4),

   - wherein each working roller (3, 4) has a separate displacing device (9) for axially displacing the working roller (3, 4), comprising the method steps of:

   - hot rolling a rolled stock in the rolling stand (2), the radial extent of the running surface (8) of a working roller (3, 4) decreasing at a rate of Δ̇r during the rolling,

   - axially displacing the working rollers (3, 4) in opposite directions at a displacement rate of $v\equiv \dot{s}>\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

   

   , where Δ̇r indicates the rate of wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).
3. Method for locally reducing the size of a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2), the rolling stand (2) comprising:

   - an upper working roller (3) and a lower working roller (4), each working roller (3, 4) having two ends (5) for the rotational mounting of the working roller (3, 4) in chocks (6),

   - wherein each working roller (3, 4) has in the axial direction (X) a conical portion (7) followed by a running surface (8),

   - wherein the upper working roller (3) is fitted in the opposite direction to the lower working roller (4),

   - wherein each working roller (3, 4) has a separate displacing device (9) for axially displacing the working roller (3, 4), comprising the method steps of:

   - hot rolling a rolled stock in the rolling stand (2), the radial extent of the running surface (8) of a working roller (3, 4) decreasing by Δr during the rolling,

   - axially displacing the working rollers (3, 4) in opposite directions by a displacement distance $s<\frac{\mathit{\Delta r}}{\tan \left(\alpha \right)}$

   

   , where Δr indicates the wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).
4. Method for locally reducing the size of a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2), the rolling stand (2) comprising:

   - an upper working roller (3) and a lower working roller (4), each working roller (3, 4) having two ends (5) for the rotational mounting of the working roller (3, 4) in chocks (6),

   - wherein each working roller (3, 4) has in the axial direction (X) a conical portion (7) followed by a running surface (8),

   - wherein the upper working roller (3) is fitted in the opposite direction to the lower working roller (4),

   - wherein each working roller (3, 4) has a separate displacing device (9) for axially displacing the working roller (3, 4), comprising the method steps of:

   - hot rolling a rolled stock in the rolling stand (2), the radial extent of the running surface (8) of a working roller (3, 4) decreasing at a rate of wear Δ̇r during the rolling,

   - axially displacing the working rollers (3, 4) in opposite directions at a displacement rate of $v\equiv \dot{s}<\frac{\dot{\Delta }r}{\tan \left(\alpha \right)}$

   

   , where Δ̇r indicates the rate of wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).
5. Method according to one of Claims 1 to 4, wherein, in the case of very thin strips (1) with a thickness of between 0.5 and 2 mm, the planarity of the strip (1) is set.
6. Method according to one of Claims 1 to 4, wherein, in the case of strips (1) with a thickness of > 2 mm, the profile of the strip (1) is set.
7. Apparatus for locally changing a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2), in particular for carrying out the method according to one of Claims 1 to 6, the rolling stand (2) comprising:

   - an upper working roller (3) and a lower working roller (4), each working roller (3, 4) having two ends (5) for the rotational mounting of the working roller (3, 4) in chocks (6),

   - wherein each working roller (3, 4) has in the axial direction (X) a conical portion (7) followed by a running surface (8),

   - wherein the upper working roller (3) is arranged in the opposite direction to the lower working roller (4),

   - a separate displacing device (9) for the upper working roller (3) and the lower working roller (4) for axially displacing the working roller (3, 4),

   - a device (11) for determining the wear Δr or the rate of wear Δ̇r of the running surface (8) of at least one working roller (3, 4) in the radial direction,

   - a measuring instrument (12) for determining the profile and/or the planarity of the rolled strip (1), the measuring instrument (12) being arranged downstream of the rolling stand (2) in the direction of mass flow,

   - a control device (13) for axially displacing the working rollers (3, 4) in opposite directions in dependence on the wear Δr or the rate of wear Δ̇r of the working rollers (3, 4), and also the measured profile PR_actual and/or the measured planarity PL_actual of the rolled strip (1), the control device (13) being connected in signaling terms to the device (11) for determining the wear Δr or the rate of wear Δ̇r and the measuring instrument (12) for determining the profile and/or the planarity of the rolled strip (1).
8. Apparatus according to Claim 7, characterized in that the device (11) for determining the wear Δr or the rate of wear Δ̇r of the running surface (8) is connected to a thickness measuring device (14) for measuring the thickness of the rolled strip (1) and to a device for determining the distance (15) between the upper working roller (3) and the lower working roller (4).
9. Apparatus according to Claim 7, characterized in that the device (11) for determining the wear Δr or the rate of wear Δ̇r of the running surface (8) has a wear model, the wear model being connected at least to one from the group comprising a rolling force measuring instrument for determining the rolling force F, the distance covered by the working roller S_extent and a timer for determining the rolling time.
10. Apparatus according to one of Claims 7 to 9, characterized in that the displacing device is an electromechanical or hydraulic displacing device.

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