阅读说明：本技术 用于压花辊轧带材的方法和装置 (Method and device for embossing rolled strip ) 是由 凯-弗里德里希·卡尔豪森 赫尔诺特·尼切 于 2016-01-26 设计创作，主要内容包括：本发明涉及用于轧钢机架辊轧带材的方法,轧钢机架包括第一工作轧辊(2)和第二工作轧辊(4),第一轧辊(2)和第二轧辊(4)之间限定有轧制线的辊隙。给出辊轧方法,该方法中带材表面结构能够可靠控制并且现有技术中的缺点能够避免,这技术问题通过本发明方法如此解决,即在辊轧方向上在工作轧辊辊隙之前布置控制辊(12),带材(8)通过控制辊(12)以相对于轧制线(6)进入角度(β)引导进入轧钢机架辊隙中并且带材(8’)表面结构通过选择进入角度(β)与控制辊(12)相对于轧制线(6)位置相关地控制。此外本发明涉及用于辊轧带材,尤其实施根据本发明方法的装置,装置具有含第一工作轧辊(2)和第二工作轧辊(4)的轧钢机架,第一工作轧辊(2)和第二工作轧辊(4)之间限定带有轧制线(6)的辊隙。(The invention relates to a method for rolling a strip in a rolling stand comprising a first work roll (2) and a second work roll (4), between which first roll (2) and second roll (4) a roll gap of a pass line is defined. The invention relates to a rolling method, in which the strip surface structure can be reliably controlled and the disadvantages of the prior art can be avoided, which is achieved by the method according to the invention in that a control roll (12) is arranged upstream of the work roll gap in the rolling direction, the strip (8) is guided into the roll stand gap by the control roll (12) at an entry angle (beta) relative to the pass line (6), and the strip (8') surface structure is controlled by selecting the entry angle (beta) in dependence on the position of the control roll (12) relative to the pass line (6). The invention also relates to a device for rolling a strip, in particular for carrying out the method according to the invention, comprising a roll stand having a first work roll (2) and a second work roll (4), the first work roll (2) and the second work roll (4) defining a roll gap with a pass line (6) therebetween.)

1. Method for embossing rolling a strip consisting of aluminium or an aluminium alloy, comprising

-a roll stand with a first work roll (2) and a second work roll (4), wherein a roll gap with a pass line is defined between the first work roll (2) and the second work roll (4), and wherein at least one work roll has an EDT surface structure, an EBT surface structure, an SBT surface structure, a structured chromium layer as a surface structure for embossing rolling or a surface roughened by laser for embossing rolling,

it is characterized in that the preparation method is characterized in that,

-a control roll (12) is arranged in the rolling direction before the roll gap of the working rolls,

-a strip (8) is guided by the control rolls (12) into the roll gap of the roll stand at an entry angle β relative to the roll line (6) and

-the transfer of the surface structure of the work rolls to the strip (8') is controlled by selecting the entry angle β according to the relative position of the control roll (12) and the pass line (6).

-adjusting the entry angle β within a +/-2 α adjustment range, where α is the bite angle of the working rolls (2, 4) in the pass, for which the following holds:

α＝arccos[1-(Δh/D_W)]

where Δ h is the difference between the thickness of the strip before rolling and the thickness of the strip after rolling, in mm (pass reduction), D_WIs the diameter of the work rolls (2, 4) in mm.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

at least one guide roller (14) is used, through which the strip (8) passes before the control roller (12).

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

-positioning the at least one guide roller (14) in such a way that the entry angle β is adjusted by the at least one guide roller (14) when the control roller (12) is not in contact with the strip (8)_BAnd is and

-adjusting the entry angle β by the positioning of the control roll (12), whereby the entry angles β and β_BThe difference of (a) is at least 0.5 °, preferably at least 1.0 °.

4. The method of any one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

a double roll stand is used as a roll stand, in particular a double roll stand with two identical working rolls (2, 4).

5. The method of any one of claims 1 to 4,

it is characterized in that the preparation method is characterized in that,

the surface roughness of at least one surface of the strip (8 ') is adjusted by means of measurements through the positioning of the control rolls (12) during rolling in combination with the surface roughness of the strip (8').

6. The method of any one of claims 1 to 5,

it is characterized in that the preparation method is characterized in that,

the strip (8, 8') changes in the relative thickness (degree of rolling) in the rolling pass by less than 10%, preferably 1 to 6%.

7. The method of any one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

a surface roughness R of at least 0.1 μm to a maximum of 10.0 μm, preferably at least 0.4 μm to a maximum of 4.0 μm, particularly preferably at least 0.5 μm to a maximum of 2.0 μm is obtained on at least one surface of the strip (8') by positioning the control roller (12)_aOr S_aThe range of (1).

8. The method of any one of claims 1 to 7,

it is characterized in that the preparation method is characterized in that,

at least one of the working rolls (2, 4) has an EDT surface structure, an EBT surface structure, a structured chromium layer or a surface roughened by means of a laser.

9. The method of any one of claims 1 to 8,

it is characterized in that the preparation method is characterized in that,

the strip (8) consists of an aluminium alloy of the AA5xxx or AA6xxx type.

10. Device for embossing rolling of a strip consisting of aluminium or an aluminium alloy, for carrying out the method according to any one of claims 1 to 9, comprising

-a roll stand with a first work roll (2) and a second work roll (4), wherein a roll nip with a pass line (6) is defined between the first work roll (2) and the second work roll (4),

and wherein at least one of the working rolls has an EDT surface structure, an EBT surface structure, an SBT surface structure, a structured chromium layer as a surface structure for embossing rolling or a surface roughened by means of a laser for embossing rolling,

it is characterized in that the preparation method is characterized in that,

-control rolls (12) are arranged upstream of the roll gap of the roll stand in the strip running direction,

-means are provided for positioning the control roll (12) relative to the mill pass line (6), and

-the means for positioning the control roller (12) allow an adjustment of the entry angle β in a range between +/-10 ° or +/-5 °, preferably +/-3 °, wherein the position of the control roller is preferably variable in steps of 0.1 °, particularly preferably 0.05 °, of the entry angle β.

11. The apparatus of claim 10, wherein the first and second electrodes are disposed on opposite sides of the substrate,

it is characterized in that the preparation method is characterized in that,

at least one guide roller (14) is arranged upstream of the control roller (12) in the running direction of the strip.

12. The apparatus of claim 11, wherein the first and second electrodes are disposed in a substantially cylindrical configuration,

it is characterized in that the preparation method is characterized in that,

means are provided for positioning the at least one guide roll (14) relative to the mill pass line.

13. The apparatus of any one of claims 10 to 12,

it is characterized in that the preparation method is characterized in that,

the double roll stand is provided as a roll stand, in particular a double roll stand with two identical working rolls (2, 4).

14. The apparatus of any one of claims 10 to 13,

it is characterized in that the preparation method is characterized in that,

at least one measuring device is provided for measuring the surface roughness of at least one surface of the strip (8').

15. The apparatus of claim 14, wherein the first and second electrodes are disposed on opposite sides of the substrate,

it is characterized in that the preparation method is characterized in that,

at least one adjusting device is provided, by means of which the positioning of the control roll (12), optionally of at least one guide roll (14), can be adjusted depending on the measurement of the surface roughness of at least one surface of the strip (8').

Technical Field

The invention relates to a method for embossing a strip and a roll stand having a first work roll and a second work roll, wherein a roll gap with a pass line is defined between the first work roll and the second work roll. The invention further relates to a device for embossing a strip, in particular for carrying out the method according to the invention, comprising a roll stand comprising a first work roll and a second work roll, wherein a roll gap with a pass line is defined between the first work roll and the second work roll.

Background

Rolled strips and sheets can be produced with a specific surface structure in the final rolling pass, in particular in the final cold rolling pass. Use is made here of a roll stand, wherein at least one of the working rolls of the roll stand has a defined surface structure, which is introduced into the surface of the strip or plate by means of a rolling pass.

This surface structure enables the preparation of a strip or plate for specific subsequent processing. In particular in the manufacture of automobiles, but also in other fields of application, such as aircraft construction or rail vehicle construction, there is a need for sheets which have very good forming behavior and achieve a high degree of forming. In automotive construction, a typical field of application is body and chassis components. In visible, painted components, such as externally visible vehicle body panels, it is also necessary for the material to be deformed in such a way that the surface is not damaged by defects, such as sagging or rope loops (Roping), after painting. This is particularly important, for example, for the production of hoods and other body components of motor vehicles from sheet metal.

Only a small pass reduction is carried out in the embossing rolling pass. By means of the embossing pass, the forming behavior of the strip with the specific surface structure introduced by the embossing rolling pass (i.e. the pattern produced by the embossing rolling) is also advantageously influenced. The surface structure of the strip introduced during rolling, for example, reduces the friction between the sheet and the forming tool if the strip or sheet produced from the strip is formed in subsequent processing. In particular, the surface structure is preferably formed such that the sheet material is better able to be wetted with the lubricant during the forming process. The surface can have a recess in the form of an oil pocket, which can receive a lubricating substance. Thereby further reducing the friction force at the time of forming and a higher degree of forming is possible.

However, for this purpose, it is necessary to adjust the surface structure or the rolling pattern of the strip. In the case of rolling, in particular in the case of embossing with a small pass, it is particularly difficult to ensure the transfer of the surface structure of the working rolls of the same shape at all times, in particular on both sides of the strip. The problem is on the one hand that the working rolls of the roll stand wear and thus have a surface structure that changes over time with constant operation. In addition, the surface structure of the work rolls may over time harbor material or other impurities of the sheet material and thereby produce a rolling pattern that varies over time. On the other hand, the strip introduced into the rolling stand is also often subjected to fluctuations, thereby making it difficult to achieve a uniform rolling pattern. For example, the dimensions of the strip introduced here, such as thickness, width or curvature or surface topography or also strength, can vary, which in turn causes the rolling pattern to fluctuate during rolling.

Furthermore, for the same surface structure of the strip on both sides, which surface structure depends on the roller condition and the design of the stand, it is often necessary in practical roll stands to use different work rollers, in particular work rollers with different surface topographies, for the front side and the rear side. It is thus complicated to provide the roll stand with corresponding work rolls.

DE4424613B4 therefore discloses a roll stand which is adjustable with respect to the surface roughness of the strip produced. This adjustment is achieved by means of a bending device on the work roll, which bending device is able to control the bending of the work roll and thus the surface structure by means of the width of the strip. The disadvantage is that the corresponding roll stand with the bending device is complicated and therefore not economical. Furthermore, the control of the surface structure can only be effected over the width of the strip. Adjustment of the surface structure of the front and back side of the strip, for example to take account of different wear levels or wear profiles of the working rolls, is not possible.

In addition, EP0908248a2 describes a device and a method for rolling strip material, in which method the front and back sides of the strip material and the respective working rolls are supplied with lubricant by means of independently adjustable spray devices. The possible differences in the rolling pattern of the front and back of the strip can be avoided by metering the lubricant. The device or the method requires improvement in particular in terms of reliability.

Disclosure of Invention

The invention is therefore based on the technical problem of providing a method and a device for rolling, in which the surface structure of the strip on the front and back sides can be reliably controlled and the disadvantages of the prior art can be avoided.

This object is achieved according to a first technical teaching of the invention by a method for rolling a strip by arranging a control roll in the rolling direction upstream of the roll gap of the working rolls, by which control roll the strip is guided into the roll gap of the rolling stand at an entry angle β relative to the pass line and by controlling the surface structure of the strip by selecting the entry angle β as a function of the relative position of the control roll and the pass line.

The roll stand used in the method according to the invention has a first work roll and a second work roll. In the method, the work rolls are brought into contact with the strip, for example a first work roll is brought into contact with the front side of the strip and a second work roll is brought into contact with the back side of the strip. At least one of the working rolls has a structured surface. By guiding the strip through the nip between the work rolls, the thickness of the strip is reduced and a corresponding structured rolling pattern is introduced on the surface of the strip by the at least one work roll with a structured surface. The cold rolling passes are preferably carried out with the roll stand. Lubricants are typically used in rolling stands during rolling.

Usually two work roll shafts are used in parallel. The axes of rotation are in parallel superposed positions and together with a connecting line arranged perpendicularly to the axes of rotation form the exit plane of the roller gap between the axes of rotation.

The surface normal of the work roll exit plane in the neutral plane of the strip to be rolled is called the rolling line. If the strip is introduced into the roll gap perpendicularly to the outlet plane, its entry angle β with respect to the rolling line is 0 °. The entry angle β is also determined relative to the surface normal of the exit plane. If the strip enters obliquely to the surface normal of the exit plane, the value of the entry angle β is not equal to zero.

According to the invention, the strip is guided by control rolls into the roll gap of the roll stand. The entry angle β is varied by controlling the positioning of the rolls relative to the pass line and thereby controlling the surface structure transfer on the strip. It can be seen that the change of the entry angle by controlling the positioning of the rolls is a very simple and reliable way of controlling the surface structure of the strip in a pass. The pass can be adapted by changing the entry angle β depending on the desired surface structure without changing the rolling stand or without having to adapt other devices, such as guide rollers, upstream of the rolling stand specifically for changing the entry angle β. In particular, the replacement of the working rolls at a certain degree of wear can also be dispensed with, since the influence on the transfer is possible only on one side of the strip under certain conditions. Even if the work rolls are worn, the rolling pattern can be kept uniform by adjusting the entry angle β by means of the control rolls. Simple work rolls without a bending device for changing the roll surface topography can also be used. In particular, it is possible to use work rolls with different surface roughness to produce strip with the same roughness on both sides. It is likewise possible to add positionable control rolls to an existing roll stand, thereby expanding the range of applications of existing roll stands in a simple manner.

The technical effect of controlling the roll positioning or the change of the entry angle β relates in particular to the control of the lubricant entering the roll gap. The entry of lubricant is essentially determined by three routes. They are

Access by surface-active substances which bind the lubricant in an active manner to the work roll surface and/or the strip,

entering by structural conditions of the work rolls and the strip surface, in particular by surface roughness and the oil pockets resulting therefrom and

-hydrodynamic access.

Hydrodynamic access is here the main route of lubricant access. Depending on the angle of contact of the surface of each work roll with the strip surface. By changing the entry angle β, the contact angle of the working rolls and thus the hydrodynamic entry of the lubricant can be changed. In particular, the rolling pattern of the front and back side of the strip can be influenced by changing the entry angle, for example in order to obtain a uniform rolling pattern on both sides and in order to react to different surface structures and different degrees of wear of the surface structures of the two working rolls.

This makes it possible to influence the lubricant entry on the front and back of the strip and thus the roll pattern directly in the roll stand by controlling the positioning of the rolls relative to the pass line.

According to a first embodiment, the entry angle α is preferably adjusted within a +/-2 α adjustment range, where α is the angle of penetration of the working rolls (2, 4) in the pass, for which the following holds:

α＝arccos[1-(Δh/DW)]

where Δ h is the difference between the thickness of the strip before rolling and the thickness of the strip after rolling, in mm (pass reduction), and DW is the diameter of the work roll (2, 4) in mm. By using an adjustment range defined for the angle β, on the one hand, the relevant angle range is covered and, on the other hand, a fine angle adjustment within the range is made possible.

When the entry angle β is greater than the bite angle α, the strip enters in tangential contact with the surface of each work roll before it is formed in the nip. In a preferred embodiment of the method according to the invention, the entry angle β is therefore adjusted to be greater than the bite angle α of the working rolls arccos [1- (. DELTA.h/DW) ], where. DELTA.h is the difference between the thickness of the strip before rolling and the thickness of the strip after rolling, in mm (pass reduction) and Dw is the diameter of the working rolls in mm. In particular, in embossing rolling, a small pass reduction Δ h is usually provided, as a result of which the bite angle α is correspondingly small.

If the work rolls are operated with an entry angle β that is greater than the bite angle α, the rolling pattern changes only on one side of the strip when the entry angle β is changed, since the other side is in contact with the work rolls at a contact angle that is greater than the bite angle. The adjustment of the rolling pattern of the second side of the strip by the change of the entry angle β can thereby be made almost independently of the first side. In this embodiment, therefore, a uniform rolling pattern can be achieved on both sides of the strip, in particular with simplified control. The entry angle β is preferably changed in steps of 0.1 °, particularly preferably in steps of 0.05 °, as a result of which the surface roughness of the front and back side of the strip can be influenced particularly precisely.

The surface topography of the rolled strip is mainly determined by the surface of the work rolls. However, the surface roughness of the two work rolls may be different. The characteristics of the surface topography can be determined by different parameters. A common parameter is the average roughness R according to DIN EN ISO4278 and DIN EN ISO 4288_a. This parameter is defined by the following equation:

z (x) is the topography of the surface, that is to say the one-dimensional profile through the function Z (x, y). L is the length of the integration interval. For determining the surface quality of a surface, the one-dimensional topography Z (x) is actually measured at a plurality of locations on the surface by linear scanning and the corresponding values R are calculated_a。

S_aThe value of (b) is given by a two-dimensional measurement of the surface, i.e. a measurement of the surface profile Z (x, y). S_aThe value is calculated by means of the following equation, where a is the size of the integrated area:

roughness R of work roll surface_aOr S_aFor example, it can be at least 0.1 μm and at most 10.0. mu.m, preferably at least 0.4 μm and at most 4.0. mu.m, particularly preferably at least 0.6 μm and at most 3.0. mu.m. Roughness R of work roll surface_aOr S_aThe difference in (b) can be greater than 0.1 μm, in particular greater than 0.3 μm, in particular in relation to the entry angle β. It is also possible to introduce a structured surface in only one working roll.

The different roughness of the work roll surfaces can be used to set the entry angle β in such a way that the contact angle between the less rough work roll and the strip is greater than the bite angle α and thus the side of the strip has a rolling pattern that is almost independent of the subsequent change in the entry angle β. The rolling pattern of the strip on the side contacting the rougher work roll can be adjusted by the entry angle beta.

In a further embodiment of the method according to the invention, at least one guide roller is used, through which the strip passes before the control roller. The function of the single guide roller or the arrangement of a plurality of guide rollers is to guide the strip and to adjust the strip tension, wherein the strip passes through the plurality of guide rollers and is bent alternately between these guide rollers. In combination with the control roller, the at least one guide roller offers the possibility of pre-adjusting the entry angle β, whereby the entry angle β can be adjusted by the control roller in very small angular steps, and at the same time it is ensured by the at least one guide roller that the control roller has sufficient traction and surface damage of the strip can be avoided.

In a further embodiment of the method according to the invention, the at least one guide roller is positioned in such a way that when the control roller is not in contact with the strip and the entry angle β is adjusted by the positioning of the control roller, the entry angle β is adjusted by the at least one guide roller_BWherein the angles of entry β and β_BThe difference of (a) is at least 0.5 °, preferably 1.0 °. For better understanding, it follows that an approximately horizontal pass line is exemplary, wherein a negative entry angle β represents entry of the strip from an upper position of the pass line and a positive entry angle β represents entry of the strip from a lower position of the pass line, without being bound thereto. First of all, the at least one guide roller is positioned in such a way that the entry angle beta is obtained_BAnd the control roll does not contact the strip. In this example, the control roller is located at the top of the strip path, i.e., it is then positioned such that it contacts the front side of the strip. The entry angle β can now be adjusted by means of the control roll between the guide roll and the roll stand. If the angles of entry beta and beta_BIs at least 0.5 deg., preferably 1.0 deg., then the control roll has sufficient tension on the strip material to avoid slippage between the strip material and the control roll. This avoids undesirable wear and tear on the strip surface caused by the control roller.

In a further embodiment of the method according to the invention, a double-strand rolling mill stand (Duo-Walzger test) is used as a rolling mill stand. The double rolling stand is of simple construction and correspondingly economical. By using control rolls in front of the double rolling stand, the rolling pattern on the strip can be controlled sufficiently well by the control rolls, even at small angles of bite. This makes it possible to dispense with complex, maintenance-intensive and expensive four-and six-fold roll stands.

In particular, a roll stand with two identical work rolls is used. The working rolls can be constructed identically in terms of diameter and length, but do not necessarily have the same structured surface, for example a topography with the same roughness. The work rolls are thereby easily interchangeable, since only one work roll type has to be prepared. The differences in transfer that may occur on the web can be compensated for by the method according to the invention by changing the entry angle β. This also eliminates quality fluctuations during the production of the upper and lower roll surfaces.

In another embodiment of the method according to the invention, the roughness of at least one surface of the strip is adjusted by means of adjustment of the entry angle β by controlling the positioning of the rolls during rolling, in combination with the measurement of the roughness of the surface of the strip. Since the entry angle β can be varied by controlling the positioning of the rolls, there is the possibility that the entry angle β and thus the rolling pattern can also be influenced by controlling the positioning of the rolls in an ongoing rolling operation. The change, in particular the measured value, of the entry angle β during rolling is determined, in particular, by other process parameters. Preferably, surface roughness measurements of the incoming and/or outgoing strip are performed, and further preferably measurements are performed on the front and back side of the strip. When measuring a change or deviation of the surface roughness of the strip from the nominal value, a uniform rolling pattern can thus be subsequently set by a change of the entry angle β.

The roll stand and the control rolls can be arranged in the production line or inside the rolling mill together with the pre-arranged cold and hot rolling stands. The control roll allows flexible adaptation of the embossing rolling pass to the process parameters of the rolling mill or to the parameters of a previously performed pass. In a further embodiment of the method according to the invention, an embossing rolling pass is carried out with a change in the relative thickness of the strip (degree of rolling) of less than 10%, preferably 1 to 6%. The transfer of the surface structure of the roller is improved by the small rolling degree, since the elongation is kept small. While at the same time limiting hardening and thereby advantageously influencing the mechanical properties of the strip. The embossing roll pass is preferably performed by working rolls having a diameter of at least 200mm and a maximum of 1200 mm.

In a further embodiment of the method according to the invention it is possible to control the positioning and the entry of the rollersThe adjustment of the angle β results in a surface roughness R of at least 0.1 μm to a maximum of 10.0 μm, preferably at least 0.4 μm to a maximum of 4.0 μm, particularly preferably at least 0.5 μm to a maximum of 2.0 μm, on at least one surface of the strip_aOr S_aThe range of (1). It has been demonstrated that the above-mentioned surface roughness R_aOr S_aIs advantageous for the forming behaviour of the sheet made from the strip. Preferably, the strip is provided on both sides with structures having the same roughness, i.e. having substantially the same R_aOr S_aThe value of (c).

The roughness value of the strip can be monitored by a measuring device, in particular during rolling. Optical measuring devices are preferably used here, which allow contactless measurement and have sufficient accuracy for the roughness described above.

In a further embodiment of the method according to the invention, at least one working roll has an EDT surface structure or an EBT surface structure. Surface structures produced by "electric spark texturing" (EDT) allow a large number of protrusions on the surface topography. The use of "electron beam texturing" (EBT) enables the creation of a controlled distribution of pits on the surface. The surface structure in the work rolls produced by both methods is very suitable for embossing rolls. Furthermore, it is also possible to use "shot texturing" (SBT) for surface structuring. It is also possible for a structured chromium layer to be used as a surface structure or a surface roughened by means of a laser.

In another embodiment of the method according to the invention, a strip of aluminium or an aluminium alloy is used. Aluminum alloys of the AA5xxx or AA6xxx type are used here in particular. More preferred aluminium alloys are AA6014, AA6016, AA6022, AA6111 or AA6060 and AA5005, AA5005A, AA5754 or AA 5182. The aluminum alloys mentioned are very suitable for applications where high forming requirements are required at the same time as high strength is required. The forming properties of the strip produced from these aluminium alloys can be further improved by the method according to the invention.

The above-described object is achieved according to a second technical teaching of the present invention by a device for rolling a strip, in particular for carrying out the method according to the present invention, in that control rolls are arranged upstream of the roll gap of the rolling stand in the strip running direction and that means are provided for controlling the positioning of the rolls relative to the rolling line.

By means of the device for controlling the positioning of the rolls relative to the pass line, it is possible to vary the entry angle β and thus to control the transfer of the surface structure onto the strip. The variation of the entry angle β by means of the device for controlling the roll positioning is a simple and reliable way of controlling the surface structure of the strip in the embossing rolling pass. The embossing roll pass can be adapted based on the desired surface structure by changing the entry angle β without changing the roll stand, in particular without having to change the work rolls. Despite wear of the working rolls, the rolling pattern can be kept uniform, in particular, by varying the entry angle β by means of the control rolls. Simple working rolls for changing the roll profile without a bending device can also be used.

In one embodiment of the device according to the invention, at least one guide roller is arranged upstream of the control roller in the running direction of the strip. In combination with the control roller, the at least one guide roller offers a plurality of possibilities and variants of the strip path for varying the entry angle β.

In particular, means are provided for positioning the at least one guide roll relative to the pass line. The at least one guide roller can thereby be positioned almost independently of the desired entry angle β, since the entry angle β is decisively adjusted by the device for controlling the roller positioning.

Furthermore, means for positioning the working rolls or for changing the pass line can also be provided, which further increases the variability of the means relating to the strip path and the entry angle β.

In a further embodiment of the device according to the invention, the device for controlling the positioning of the rolls allows an entry angle β of between +/-10 °, +/-5 °, +/-3 °, or preferably +/-2 α. The position of the control roller can preferably be changed in steps of 0.1 °, particularly preferably in steps of 0.05 °, of the entry angle β, as a result of which a very precise influencing of the surface roughness of the front and back side of the strip can be carried out. This is particularly advantageous in combination with a multiple roll stand which provides only a small bite angle. The mentioned entry angles β of +/-10 °, 5 ° or 3 ° achieve a sufficient adjustment range for influencing the surface structure of the strip. When limited to an angular range of +/-5, +/-3 or +/-2 a, a particularly small angular adjustment step amplitude is achieved in a simple manner.

In a further embodiment of the device according to the invention, the double rolling stand is a rolling stand, in particular a double rolling stand with two working rolls having the same diameter. The control rolls upstream of the multiple roll stands can also be used to control the rolling pattern on the strip at small entry angles, primarily by means for adjusting the control rolls. This makes it possible to dispense with complex, maintenance-intensive and expensive four-and six-fold roll stands.

In a further embodiment of the device according to the invention, at least one measuring device for measuring the surface roughness of at least one surface of the strip is provided. Optical measuring devices are preferably used here, which allow contactless measurement and have sufficient accuracy for the roughness described above. The measuring device can be arranged in particular downstream of the rolling stand in the direction of travel of the strip, in order to measure the rolling pattern of the embossing pass.

In particular, at least one adjusting device is provided, by means of which the positioning of the rollers is controlled, the positioning of the optionally at least one guide roller being adjustable as a function of the measurement of the surface roughness of at least one surface of the strip. The adjusting device can here analyze the measured surface roughness and change the entry angle β by controlling the positioning of the rollers. The rolling pattern can thus be detected and adjusted during the rolling operation.

Drawings

For further configurations and advantages of the device according to the invention, reference is made to the above-described embodiments and the dependent claims and the figures of the method according to the invention. Wherein:

figures 1a and 1b show schematic views of the geometry at rolling,

figures 2a-2d show schematic views of a method according to the invention or an apparatus according to the invention,

FIG. 3 shows the measured average roughness values S as a function of the angle of entry_aAnd

fig. 4 shows the surface profile of the front and back of a rolled strip according to the invention in relation to the entry angle.

Detailed Description

Fig. 1a shows a schematic view of the geometry in the first rolling pass. A roll gap is formed between the first (upper) work roll 2 and the second (lower) work roll 4, through which roll gap a pass line 6 is given. The pass line 6 extends through the central plane of the strip and is perpendicular to the plane of connection of the axes of rotation of the rolls 2 and 4. The strip 8 travels through the nip and is formed by the work rolls 2 and 4 into a strip 8' having a smaller thickness. Here Δ h is the difference between the thickness of the strip 8 before rolling and the thickness of the strip 8' after rolling, in mm (pass reduction).

The work rolls 2, 4 are in contact with the strip at a bite angle α. As shown in fig. 1a, the bite angle α is the angle between the line connecting the two axes of rotation of the work rolls 2, 4 and the line connecting one of the axes with the point of contact with the strip surface. The angle is formed by

α＝arccos[1-(Δh/DW)]

Is given by_WIs the diameter of the work rolls 2, 4 in mm. In the example shown in fig. 1a, the diameters Dw of the working rolls 2, 4 are identical and therefore have the same nip angle α.

In addition, the strip 8 runs parallel to the pass line 6 on the inside in fig. 1a, whereby the entry angle β is equal to 0 °. The contact angle between the surface of the strip 8 and the surface tangents of the two work rolls 2, 4 is thus equal to the bite angle α.

Fig. 1b shows a schematic view of the geometry of the second rolling, in which there is an entry angle β ≠ 0 ° between the course of the strip 8 and the pass line. This angle is indicated in fig. 1b between the pass line 6 and the centre line 10 of the strip 8. The entry angle β ≠ 0 ° has the effect that the contact angle between the surface of the strip 8 and the tangent of the surface of the work rolls 2, 4 is different for both faces. In fig. 1b the upper work roll 2 has a contact angle of alpha + beta and the lower work roll 4 has a contact angle of alpha-beta.

When using a lubricant, the entry of the lubricant into the roll gap is dependent on the contact angle α + β or α - β between the tangent to the surface of the respective work roll 2, 4 and the surface of the strip 8. By adjusting the entry angle β, the contact angle of the working rolls 2, 4 and thus the hydrodynamic lubricant entry can be changed. In particular, the rolling pattern of the front and back sides of the strip 8' can be influenced by adjusting the entry angle β.

If the entry angle β exceeds the bite angle α, the strip is in tangential contact with the work rolls 4. The entry angle β continues to increase without any substantial effect on the entry of lubricant into the work roll 4.

Fig. 2a shows a first schematic view of a method according to the invention or of a device according to the invention. The roll stand is here shown simplified by the working rolls 2, 4, wherein at least one of the working rolls 2, 4 has a structured surface. Control rolls 12 with means for positioning relative to the pass line 6 are arranged upstream of the working rolls 2, 4 in the strip running direction. Before this, at least one guide roller 14 is arranged in the running direction of the strip.

In fig. 2a, the control roller 12 is positioned in such a way that the control roller 12 does not come into contact with the strip 8. The strip 8 thus runs internally parallel to the pass line 6 and enters at an angle β of 0 °. This shows a situation similar to that of fig. 1a, in which both working rolls 2, 4 have a contact angle with the surface of the strip 8 which is equal to the bite angle α.

In contrast, in fig. 2b, the control roller 12 is positioned by the positioning device in such a way that the control roller 12 comes into contact with the strip 8, deflects the strip 8 and thus sets the entry angle β ≠ 0 ° between the strip 8 and the pass line 6. This situation is similar to the situation in fig. 1 b.

By changing the entry angle β, the contact angle of the working rolls 2, 4 and thus in particular the hydrodynamic lubricant entry of the respective working roll 2, 4 can be changed. By varying the entry angle β with the aid of the device for controlling the positioning of the rolls 12, the rolling pattern of the front and back of the strip 8 'or the surface structure of the rolled strip 8' can be controlled thereby.

Fig. 2c shows a further embodiment of the method according to the invention or of the device according to the invention in a further schematic representation. Here too, means are provided for positioning of at least one guide roll 14 relative to the mill pass line 6.

The at least one guide roller 14 is positioned here such that, provided that the control roller 12 does not come into contact with the strip 8, an entry angle β is provided_B. The entry angle β is adjusted by controlling the positioning of the roller 12, wherein the entry angles β and β_BThe difference between them is at least 0.5 deg., preferably 1.0 deg..

With this positioning of the control roller 12 and the guide roller 14, it is ensured that the control roller 12 has sufficient traction on the strip 8 to avoid slip between the strip 8 and the control roller 12. This avoids undesirable wear and tear on the surface of the strip 8 caused by the control roller 12.

Fig. 2d shows a further embodiment of the method according to the invention or of the device according to the invention in a further schematic representation. Here, a measuring device 16 is provided for measuring the surface roughness of at least one surface of the strip 8'. The roll pattern can be detected by the measuring device 16. The measuring device 16 can send the measured values to the regulating device 18. The adjusting device 18 influences the device for controlling the positioning of the roller 12 on the basis of the measured values of the measuring device 16. The adjusting device 18 can thus be used for adjusting the surface roughness of the strip 8' during rolling. Optionally, the adjusting device 18 can also control the device for positioning of the at least one guide roller 14.

FIG. 3 shows the measured average roughness values S in relation to the entry angle β in an experimental sequence_a. An aluminium alloy strip of alloy type AA6016 having a thickness of 2.4mm was rolled in a rolling stand. The nip angle α of the embossing frame in the test is, for example, 1.3 °.

The strip is rolled at different entry angles beta adjusted by the control rolls. For an angle of entry beta>α is 1.3 °, which exceeds the nip angle α of the lower work roll. Thus average roughness S of the back of the strip_aAnd does not show large variations. More precisely, the back of the strip is in tangential contact with the surface of the lower working roll, thus creating a constant rolling pattern substantially independent of the entry angle β. For the front side, the average roughness S_aA surprisingly strong correlation with the entry angle beta is shown. It was determined that a wide range of different roughness levels of the front side of the strip and the respective mean roughness S could be achieved by varying the entry angle β with the positioning of the control rolls_aCan be purposefully adjusted. Here average roughness S_aThe dependence on the entry angle β over the measurement range is very nearly linear.

Fig. 4 shows the surface profile of the front and back of a rolled strip according to the invention in relation to the entry angle β in the same test sequence as shown in fig. 3. Here too, it can be seen that the profile on the rear side is only slightly changed with the entry angle α due to the fact that the bite angle α is exceeded, while the profile on the front side can be controlled well by adjusting the entry angle β by means of the control roller. For example, the same roughness can be adjusted more reliably on both sides of the strip using control rollers.

The use of control rolls also makes it possible to react to changes or wear of the work rolls. In the test sequence described above, the entry angle β was readjusted to 1.74 ° after increasing the entry angle β from 0.97 ° to 2.20 °. As seen in fig. 3 and 4, the appearance with a slight change or the roughness with a slight change is shown here compared with the previous test with β being 1.74 °. This may be due to material sticking or contamination of the work rolls. In this case, a uniform rolling pattern can be easily restored by readjusting the entry angle β without the need to repair or replace the working rolls.