EP2527056A1 - Method for milling boards, computer program, data carrier and control device - Google Patents

Abstract

The method involves detecting whether side surfaces (12, 14) of a parallelogram shaped board (4) are offset relative to each other in a rolling direction (6) during discharging the board from a rolling stand (2). Guide elements (16, 18) are asymmetrically adjusted relative to a middle line (M) after centering during a rolling pass when the side surfaces are offset relative to each other. One of the guide elements (18) for one of the side surfaces (14), which enters into the stand as first during the rolling pass, is displaced from the middle line as the other guide element. Independent claims are also included for the following: (1) a computer program comprising instructions for performing a method for rolling boards by a rolling stand (2) a data carrier comprising instructions for performing a method for rolling boards by a rolling stand (3) a control device.

Description

The invention relates to a method for rolling plates by means of at least one roll stand. The invention further relates to a computer program, a data carrier and a control device for a rolling stand.

For the edge-straight guidance of a rectangular plate in a roll stand of a sheet rolling mill side guide elements are provided, which grant the rectilinear, symmetrical course of the plate. The guide elements are used for centering and are then slightly "driven up" again. They do not lie directly on the side surfaces of the plate, but are positioned at a distance from the side surfaces, so that between the guide elements and the side surfaces of the plates columns with a width of a few centimeters, in particular from 3 to 5 cm, are formed. When rolling rectangular plates or sheets, it often happens that the plates do not run straight into the nip of the roll stand of the sheet rolling mill. This situation can arise when e.g. the friction in the different areas of the rolled plate is different. This means that the plate after the roll pass is no longer rectangular, but takes the form of a parallelogram. At the next roll pass, this effect is additionally reinforced, since the plate is only detected on one side of the roll gap and thus transverse forces arise. Due to the transverse forces, however, the plate is rotated with respect to the rolling direction as far as the guide elements permit. Within the scope of these limits, the plate thus runs obliquely into and through the nip.

The phenomenon described leads, especially when rolling thin and wide plates to considerable instabilities and problems that can affect production. With various methods is nowadays trying to lead plates that have lost their perpendicularity, as straight as possible in the nip. One possibility is to push plates whose width is greater than their length in the rolling direction at excessive speed into the nip and thereby move them straight. Another possibility is to drive the guide elements as closely as possible, but that has limitations, because the plates are usually wider at the head and foot and remain stuck in the side guide.

The invention has for its object to ensure a trouble-free rolling of plates and sheets, even if their faces are oriented by the rollers at an angle to the rolling direction.

• ein erster Walzstich durchgeführt wird und beim Auslaufen der jeweiligen Platte aus dem Walzgerüst erfasst wird, ob die Seitenflächen der Platte in Walzrichtung zueinander versetzt sind,
• die Platte vor einem zweiten Walzstich zentriert wird, wobei die Führungselemente in einer Zentrierposition an der Platte anliegen, und
• wenn die Seitenflächen der Platten in Walzrichtung zueinander versetzt sind, bei einem zweiten Walzstich die Führungselemente nach dem Zentrieren asymmetrisch in Bezug auf die Mittellinie eingestellt werden, indem ein erstes Führungselement für die Seitenfläche, die beim zweiten Walzstich als erste in das Walzgerüst einläuft, weiter von der Mittellinie als das zweite Führungselement verstellt wird.

This object is achieved according to the invention by a method for rolling plates with the aid of at least one rolling stand, wherein the rolling stand has a guide element for centering the plates on the drive side and on the operator side and the guide elements are arranged symmetrically with respect to a center line of the rolling stand extending in the rolling direction, in which

• a first pass is made and, when the respective plate exits the rolling stand, it is detected whether the side surfaces of the plate are offset from one another in the rolling direction,
• the plate is centered before a second roll pass, wherein the guide elements rest in a centering position on the plate, and
• when the side surfaces of the plates are offset from each other in the rolling direction, in a second rolling pass the guide elements are adjusted asymmetrically with respect to the center line after centering, by a first guide element for the side surface, which first enters the rolling stand in the second pass, from the center line is adjusted as the second guide element.

Under first Walzstich this is not the very first Walzstich understood in the processing of the plate in the sheet rolling mill, but the chronological first of any two, immediately consecutive rolling passes in the context of the rolling process. Accordingly, "second roll pass" refers to the chronologically later of two immediately consecutive roll passes.

As the sheet exits the nip of a rolling mill, it is predicted how the subsequent run into the next nip will occur and in which direction the disk will rotate if no countermeasures are taken. If the direction of rotation of the plate is known during the second pass, appropriate countermeasures are initiated via the guide elements.

So far, the guide elements after centering, when the plate has reached the next nip, moved symmetrically to distance to the plate, so that on both sides of the plate forms a tolerance gap of 3-5 cm in particular. When a side surface of the plate is more rapidly caught by the nip than the opposite side surface, the plate is rotated in the direction of its "slower" side, i. in the direction of the side surface, which enters as the second in the nip. She beats against the corresponding guide element.

According to the invention is checked after each rolling pass during the rolling process in the sheet rolling mill, whether the side surfaces of the expiring plate are offset in the rolling direction to each other and thus the plate has the shape of a parallelogram with at least one oblique end face. If it is determined that the end faces of the plate after the last pass are no longer transversely to the rolling direction, the next rolling pass the guide elements are set asymmetrically by the guide element, whereas the plate would hit as it rotates when entering the second mill, closer the plate stays, leaving the plate can not perform their rotary motion. The method aims in the first place to prevent further deformation of plates that have already lost their rectangular shape.

Preferably, the second guide element for the side surface, which enters the rolling stand as the second in the second pass, remains in its centering position. This means that the second guide element bears against the side surface of the plate facing it. In other words, the guide element is positioned such that the distance between it and the center line substantially corresponds to the distance between the center line and the side surfaces in a symmetrical arrangement of the plate, so that the guide element against the second when entering the first side surface in the nip Side surface presses and thus prevents pivoting of the plate at the beginning of the rolling pass.

According to a preferred embodiment, a tolerance gap is set between the first guide element and the side surface of the plate facing it whose width is a few centimeters, in particular 6 to 10 cm. The "opening" of the guide element for the side surface, which enters the first in the nip, is made for safety reasons, so that the plate does not get stuck.

According to a preferred variant, a rolling force is measured both on the drive side and on the operator side to check whether the side surfaces of the plate are offset in the rolling direction. If the rolling force on the end faces of the plate on the drive side and the operator side is not the same, this means that the end faces of the plate are viewed in the rolling direction obliquely. This information on the end faces of the plate is determined when the plate comes to an end after the first pass. The guide elements are adjusted asymmetrically in the next roll pass to prevent pivoting of the plate.

The arrangement of the guide elements is important only during the entry of a head side of the plate for the orientation of the plate during the entire rolling pass. If the same rolling force is set on the drive side and on the operator side, the plate is simply moved on independently of the guide elements. So that friction forces are not unnecessarily generated between one of the side surfaces and one of the guide elements, according to a further preferred embodiment, after the second side surface enters the rolling stand, the guide elements are adjusted symmetrically at a slight distance of, in particular, 3 to 5 cm from the side surfaces.

Sheet rolling mills may comprise a plurality of rolling mills, which are arranged one behind the other in the rolling direction. If only one rolling pass is carried out on each roll stand, this means that the plate is always conveyed only in the rolling direction during its processing in the sheet rolling mill, so that the same end face forms the top side of the plate with each rolling pass. In such a sheet rolling mill, after a displacement of the side surfaces of the plate is determined in the rolling direction, preferably the guide elements of the next rolling stand after centering of the plate when entering the plate are also set asymmetrically. Thus, if the plate has already assumed the form of a parallelogram, a further deformation of the plate is counteracted in each further rolling pass in the rolling direction by the asymmetrical adjustment of the guide elements of the individual rolling stands.

The sheet rolling mill may alternatively include at least one reversible rolling stand on which a plurality of rolling passes are performed by the rolling direction is rotated again and again. In this case, both end faces of the plate alternately form the head side. When the plate is rolled by means of at least one reversible roll stand, the guide elements of the reversible roll stand thus according to an advantageous embodiment when changing the rolling direction accordingly adjusted. It is thus always taken into account at the current head side which side surface is the first to enter the nip and accordingly the guide element is opened on this side of the plate and the second guide element remains adjacent to the plate.

The object is further achieved according to the invention by a computer program comprising a machine code, the execution of which by a control device for a rolling stand causes the rolling stand to be operated according to a method according to one of the embodiments described above.

The object is also achieved according to the invention by a data carrier on which such a computer program is stored in machine-readable form.

Furthermore, the object is achieved by a control device for a rolling stand, in which such a computer program is stored, which is executable by the control device.

FIG 1

eine parallelogrammförmige Platte beim Einlaufen in ein Walzgerüst,

FIG 2

die Platte gemäß FIG 1 bei einer asymmetrischen Einstellung von Führungselementen,

FIG 3

ein Signal einer Differenzwalzkraft gemessen in der Situation gemäß FIG 1,

FIG 4

ein Signal der Differenzwalzkraft gemessen in der Situation gemäß FIG 2, und

FIG 5

das Signal der Differenzwalzkraft über mehrere Walzstiche in der Situation gemäß FIG 1.

An embodiment in the invention will be explained in more detail with reference to a drawing. Herein show:

FIG. 1

a parallelogram plate when entering a mill stand,

FIG. 2

the plate according to FIG. 1 in an asymmetrical setting of guide elements,

FIG. 3

a signal of a differential rolling force measured in the situation according to FIG FIG. 1 .

FIG. 4

a differential rolling force signal measured in the situation according to FIG FIG. 2 , and

FIG. 5

the signal of the differential rolling force over several rolling passes in the situation according to FIG. 1 ,

Like reference numerals have the same meaning in the various figures.

In FIG. 1 is symbolically shown a rolling stand 2 of a sheet rolling mill not shown here, with the aid of a plate 4 is rolled. The rolling stand 2 is characterized by a drive side OS and by an operating side DS. The sheet rolling mill comprises a plurality of such rolling stands 2, which are arranged in a rolling direction 6 along a center line M one behind the other. During rolling, the plate 4 is conveyed in the rolling direction 6, wherein usually each next rolling pass is performed on the next rolling mill 2 in the rolling direction 6.

The plate 4 has two end faces 8, 10 and two side surfaces 12, 14. Depending on which end side enters as the first and second in the respective rolling stand 2, the end faces are referred to as the head side and foot side. The head side according to 1 and FIG. 2 is the front side 8 and the foot side is formed by the opposite end face 10.

Ideally, the plate 4 is rectangular. A rectangular plate is thereby driven straight edge in their processing in a rolling gap not shown here in detail of the roll stand 2. For centered guidance of the plate 4, two guide elements 16, 18 are provided, which are arranged parallel to the center line M. The guide elements 16, 18 abut against the plate 4. When the plate 4 reaches the nip, the guide members 16, 18 are adjusted so that between each guide member 16, 18 and the side surface 12, 14, which faces it, a small tolerance gap 20a, 20b formed by a few centimeters. In normal operation of the roll stand 2 in a rectangular plate 4, the width of the tolerance gap is about 3 cm.

However, it may happen that the plate 4 is rotated in operation with respect to the center line M and so into the nip of the roll stand 2 enters. After a roll pass, the plate 4 is then no longer rectangular, but it has the shape of a parallelogram. In the next rolling pass, the head side 8 of the plate 4 is directed obliquely to the nip, so that the plate 4 only with an edge, according to FIG. 1 only enters the mill stand with the drive-side edge of the end face 8. By the rolling forces acting in the region of the drive-side edge of the end face 8, the plate 4 is pivoted in the direction of the operating side DS. This pivoting movement is in FIG. 1 indicated by the arrow 22. During its rotation, the plate 4 can push against the control-side guide element 16.

In order to avoid a collision between the plate 4 and one of the guide elements 16, 18, when the plate has lost its rectangular shape, the shape of the plate 4 is determined after each rolling pass during the departure of the plate 4 from the nip of the respective rolling stand 2. This is done by measuring the rolling force both on the operating side DS and on the drive side OS of the roll stand 2. From the two measured values, a difference measured value D is formed and output, as shown in FIG 3, FIG. 4 and FIG. 5 is shown. The course of the differential rolling force in the situation according to FIG. 1 is in FIG. 3 shown. Since the plate 4 enters the nip only with its drive-side edge, the signal for the differential rolling force D at the time of entry of the slab 4 in the nip provides a first peak 24, since the drive side already high forces on the plate 4 and on the rollers of the roll stand 2, while the operating side no contact between the rollers and the plate 4 has taken place. The range 26 of the signal for the differential rolling force D according to FIG FIG. 3 illustrates the shrinkage of the head 8 in the nip. The peak 28 marks the time from which the operator-side edge of the end face 8 of the plate 4 is in the nip of the roll stand 2.

The time course of the differential rolling force D over several rolling passes I, II and III is in FIG. 5 shown. The first Rolling pass I shows the course of the differential rolling force D in the situation according to FIG. 1 , The course of the differential rolling force D when running in the plate 4 in the roll stand 2 in this case has already been FIG. 3 explained. The second half of the course of the differential rolling force D during the first pass I represents the runout of the slab 4 from the nip. The peak 30 shows a large difference in rolling force between the operating side DS and the drive side OS at the time of the driving side Edge of the foot 10 leaves the nip. The area 32 illustrates the gradual leakage of the foot side 10 of the plate 4 from the rolling stand 2. From the peak 34, the plate 4 is completely outside the nip.

On the basis of the further course of the differential rolling force D during the second and third rolling passes II, III is clearly the tendency to recognize that the areas 26a, 26b and 32a are getting steeper, which suggests that the inclination of the end faces 8, 10 at Entry or exit from the roll gap is getting larger, ie that the plate 4 is further distorted with each further roll pass.

In order to prevent such a deformation of the parallelogram plate 4, the guide elements 16, 18 are positioned asymmetrically with respect to the center line M such that the plate 4 can not perform a pivoting movement 22. This is in FIG. 2 shown. Since the rolling force is measured at each pass, changes in the geometry of the plate 4 that took place during rolling can be detected when the plate 4 leaves the nip. If an oblique position of the end faces 8, 10 of the plate 4 is detected, the next rolling stand on the next rolling stand 2 in the rolling direction 6, the operating-side guide member 16 remains adjacent to the side surface 12. In this arrangement, the plate 4 when entering the nip is no longer in the direction of arrow 22 according to FIG. 1 rotate.

At the same time, the distance between the drive-side guide element 18 and the side surface 14 of the plate 4 facing it is increased. This results in a tolerance gap 20c, the width of which is substantially twice as large as that of the original tolerance columns 20a, 20b in an undisturbed rolling on a rectangular plate 4, which is oriented symmetrically with respect to the center line M.

The course of the differential rolling force D in the arrangement according to FIG. 2 is in FIG. 4 shown. Out FIG. 4 It can be seen that the drive-side edge of the end face 8 moves in front of the user side edge of the end face 8 in the nip, ie that the side surfaces 12, 14 are offset in the rolling direction 6 to each other, by the asymmetric arrangement of the guide elements 16, 18 is guaranteed, that the side surfaces 12, 14 at the inlet of the plate 4 parallel to each other and parallel to the center line M remain. The rectangular shape of the plate 4 can not be restored thereby, however, a further distortion of the plate 4 is avoided during the rolling pass.

After the head side 8 has already fully run into the nip, there is no longer a risk of rotation of the plate 4 in the direction 22. Therefore, after the end face 8 enters the mill stand, i. after the running in of the second side surface 12 into the roll stand, the guide elements 12, 14 are again adjusted symmetrically with respect to the center line M at a distance from the plate 4.

The adjustment of the guide elements 12, 14 is carried out in particular by a control device not shown in detail here, which outputs a control signal to the guide elements 16, 18 as a function of the measurement signal of the rolling forces on the operating side DS and the drive side OS or as a function of the differential rolling force D. ,

The asymmetrical adjustment of the guide elements 12, 14 during running in of the plate 4 is carried out on each additional roll stand 2 in the rolling direction 6.

It is also conceivable that the rolling mill 2 is operated reversibly, so that several roll passes are made on this one roll stand 2. In this case, the rolling direction is changed in the opposite direction of the arrow 6 after a first rolling pass. The end face 10, which has hitherto formed the foot side of the plate 4, thus becomes the head side of the plate 4. In the second rolling pass on the roll stand 2, it is therefore to be considered that now the operating side face 12 lies in the rolling direction in front of the working side face 14, so that a rotation of the plate in the direction of the drive-side guide element 18 is to be expected. In this case, the drive-side guide member 18 is applied to the side surface 14 before the run-in of the plate 4 in the rolling stand 2, and the operation-side guide member 16 is further removed from the center line M.

By means of the arrangement of the guide elements 16, 18 according to FIG. 2 a further distortion of the plate 4 is prevented, whereby on the one hand the material losses in the manufacture of the plate 4 are kept smaller and on the other hand a trouble-free operation of the rolling stands 2 is ensured.

Claims (10)

Method for rolling plates (4) by means of at least one rolling stand (2), wherein the rolling stand (2) has a guide element (16, 18) on the drive side and on the operator side for centering the plates (4) and the guide elements (16, 18) are arranged symmetrically with respect to a in the rolling direction (6) ersteckende center line (M) of the roll stand, in which a first pass is made and when the respective plate (4) leaves the rolling stand (2) it is detected whether the side surfaces (14, 16) of the plate (4) are offset from one another in the rolling direction (6), - The plate (4) is centered before a second rolling pass, wherein the guide elements (16, 18) in a centering position against the plate (4) abut, and if the side faces of the plate are offset in the rolling direction, in a second pass the guiding elements (16, 18) are adjusted asymmetrically with respect to the center line (M) after centering, by a first guide element (18) for the side face (14 ) which enters the mill stand (2) first in the second pass, is moved further from the center line (M) than the second guide member (16). Method according to claim 1,
wherein the second guide element (16) for the side surface (12), which enters the second rolling pass as the second in the roll stand (2), remains in its centering position. Method claim 2,
wherein a tolerance gap (20c) is set between the first guide element (18) and the side surface (14) of the plate (4) facing it, the width of which is a few centimeters, in particular 6 to 10 cm. Method according to one of the preceding claims,
wherein to test whether the side surfaces (12, 14) of the plate (4) in the rolling direction (6) are offset from each other, a rolling force is measured on both the drive side and the operator side. Method according to one of the preceding claims,
wherein the guide elements (16, 18) after the arrival of the second side surface (12) in the roll stand (2) are set symmetrically again. Method according to one of the preceding claims,
wherein in the rolling direction (6) a plurality of rolling stands (2) are arranged one behind the other and when an offset of the side surfaces (12, 14) of the plate (4) in the rolling direction (6) is determined, the guide elements (16, 18) of the next rolling stand ( 2) when entering the plate (4) are also set asymmetrically. Method according to one of the preceding claims,
wherein the plate (4) is rolled by means of at least one reversible roll stand (2) and the guide elements (16, 18) of the reversible roll stand (2) are adjusted accordingly when changing the rolling direction (6). A computer program comprising a machine code whose execution by a rolling mill control means (2) causes the rolling stand (2) to be operated according to a method according to any one of the preceding claims. Data carrier on which a computer program according to claim 8 is stored in machine-readable form. Control device for a rolling mill, in which a computer program according to claim 8 is stored, which is executable by the control device.

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