Multi-high roll stand

Abstract

A multi-high roll stand has several driven support rolls and several working rolls frictionally driven by the support rolls. The support rolls form a roll gap defining a thickness of rolling stock guided between the working rolls in a rolling direction. The working rolls are moveable in a direction substantially parallel to the rolling direction for adjusting the gap width of the rolling gap.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a multi-high roll stand with a plurality of driven support rolls and with a number of working rolls frictionally driven by the support rolls, wherein the working rolls form a rolling gap which defines the thickness of rolling stock guided between the working rolls in a rolling direction.

[0003] 2. Description of the Related Art

[0004] For rolling a rolling stock, for example, in a rolling mill, a roll stand can be used. The roll stand is often a so-called multi-high roll stand and comprises a plurality of working rolls and a number of support rolls. The support rolls are conventionally driven by a correlated drive wherein each support roll is in frictional contact with a correlated working roll. By means of the thus provided frictional drive action, each working roll is then driven by the correlated support roll. The working rolls act together onto opposed sides of the rolling stock wherein the thickness of the rolling stock, guided between the working rolls through the multi-high roll stand, is determined by the roll gap formed between the working rolls. The thickness of the rolling stock guided through the multi-high roll stand can be adjusted by means of a corresponding variation of the pressing force, which is also referred to as rolling force, of each working roll.

[0005] When processing comparatively high-quality rolling stock such as, for example, steel or stainless steel, it may be important, in particular, for the so-called skin pass rolling step of such a rolling stock, that the respective multi-high roll stand is configured for covering a comparatively wide rolling force range. A control provided for this purpose, by which, inter alia, the thickness of the rolling stock is adjusted, thus covers with its value range also a comparatively large rolling force range. However, for such a system the essential components are conventionally configured such that measuring errors, such as, for example, errors in the rolling force measurement, depend on the maximum value of the respective measured value. In particular in the case of a rolling force measurement, whose value range covers a comparatively wide rolling force range, the absolute measuring error is thus comparatively large.

[0006] On the other hand, in the so-called skin pass rolling of IF (interstitial free) steel, it is necessary to adjust, even for such multi-high roll stands, comparatively small rolling forces. Accordingly, for a multi-high roll stand, which is to be used, on the one hand, for skin pass rolling of IF steel and, on the other hand, for covering a generally comparatively large rolling force range, the measuring error for determining the rolling force can be greater than the actual rolling force required for skin pass rolling of IF steel. The thickness and/or skin pass rolling control for such a multi-high roll stand is thus comparatively imprecise.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide a multi-high roll stand of the aforementioned kind which, on the one hand, can be used for a comparatively high rolling force range and, on the other hand, can be adjusted especially precisely, even for comparatively small rolling forces, with respect to its roll gap and thus with respect to the thickness of the rolling stock. Moreover, a method for operating such a multi-high roll stand is to be provided which makes possible, even for comparatively small rolling forces, a particularly precise thickness control of the rolling stock.

[0008] In accordance with the present invention, this is achieved in regard to the multi-high roll stand in that the working rolls are movable in a direction substantially parallel to the rolling direction for adjusting the gap width of the roll gap.

[0009] The invention in this connection is based on the consideration that the thickness adjustment of the rolling stock can be realized with an especially high precision in that it is carried out via an adjusting parameter having a comparatively large adjusting stroke. The actual adjusting parameter for the thickness adjustment, i.e., the position of the respective working roll perpendicularly to the rolling direction for forming the roll gap, however, has a comparatively minimal stroke adjustment. It is therefore transformed into a parameter with comparatively large adjusting stroke, i.e., the position of the working roll in a direction parallel to the rolling direction. When adjustments are carried out, the working roll rolls on the surface of the spatially stationary support roll so that a defined relation between the position of the working roll perpendicularly to the rolling direction and its position in the rolling direction results. In particular in this area directly below the support roll the geometric conditions are such that a comparatively generous spatial movement of the working roll in the rolling direction results in only a minimal change of its position in the direction perpendicularly to the rolling direction.

[0010] Conventionally, a rolling mill is configured for passing the rolling stock therethrough substantially in a horizontal rolling direction. Advantageously, in an adaptation to this configuration, the working rolls are accordingly movable substantially horizontally for adjusting the gap width of the roll gap.

[0011] For a particularly reliable automated thickness adjustment of the rolling stock, a control device is correlated advantageously with the multi-high roll stand. It is expediently connected at the output side with a number of adjusting devices, each one being correlated with a working roll, respectively, for adjusting the position of the working roll in the rolling direction. The control device presets in this connection a nominal or preset adjusting value for each adjusting device, respectively, for positioning the respective working roll in the rolling direction wherein the respective adjusting value is selected as a function of a measured actual value of the thickness of the rolling stock.

[0012] For the adjusting devices acting on the working rolls different configurations can be provided, for example, in the form of rotary spindles. Advantageously, the adjusting devices are, however, hydraulic adjusting devices with which an specially high adjusting precision can be obtained.

[0013] For a timely and particularly reactive control, a direct loading of the control device with a measured value characteristic of the thickness of the rolling stock is advantageously provided. For this purpose, the inlet side of the common control device is advantageously connected with a measured value (measurement) transponder for determining the thickness of the rolling stock.

[0014] In order to be able to have available in the way of a selectable rolling program a suitable pre-defined operating parameter for a plurality of different purposes, according to a further expedient embodiment a memory component is correlated with the common control device in which a number of nominal values for the thickness of the rolling stock can be stored. As a function of the actual use of the roll stand, it is possible in a very simple way to switch between different rolling programs in that a new currently desired valid nominal value for the thickness of the rolling stock is selected, respectively, from the nominal values stored in the memory component.

[0015] With respect to the method for operating a multi-high roll stand, the object is solved in that the thickness of the rolling stock is adjusted by a movement of the working rolls in a direction which is substantially parallel to the rolling direction.

[0016] The adjustment of the position of the working rolls in the rolling direction is advantageously performed by means of a comparison of a currently determined value of the thickness of the rolling stock with the nominal value for the thickness of the rolling stock.

[0017] The advantages obtained with the invention reside in particular in that by the movement of the working rolls in the rolling direction for the purpose of adjusting the gap width of the roll gap the thickness of the rolling stock is affected indirectly and by means of a control parameter with a comparatively large adjusting stroke. In particular as a result of the geometric conditions between the support rolls and the working rolls, the displacement strokes of the working rolls, i.e., the positional changes required for obtaining a predetermined change in the gap width of the roll gap, are especially large so that the sensitivity and precision for adjusting the gap width of the roll gap are particularly high. Moreover, the position adjustment of the working rolls in a direction substantially perpendicular to the rolling force is such that a coupling to the rolling force is realized only by the deflection within the working roll itself. Moreover, for such an adjustment of the gap width of the roll gap the stand friction is especially minimal.

BRIEF DESCRIPTION OF THE DRAWING

[0018] One embodiment of the invention will be explained in the following with the aid of the only drawing FIGURE showing a multi-high roll stand.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The FIGURE shows a multi-high roll stand 1 as a four-high stand and comprises an upper working roll and a lower working roll 2, 4 which are supported substantially vertically on a support roll 6, 8, respectively. The working rolls 2, 4 are correlated with roll bending devices, not illustrated in detail, which load the working rolls 2, 4 with vertical roll bending forces for adjusting the rolling profile.

[0020] The support rolls 6, 8 are driven by a drive, not illustrated in detail, receptively, and are rotated about their central axis. Each working roll 2, 4 is in frictional contact with the respectively correlated support roll 6, 8 so that it is entrained by the respective correlated driven support roll 6, 8 by friction.

[0021] Rolling stock 10 is guided between the working rolls 2, 4 in a substantially horizontal rolling direction x, as indicated by the arrow. The working rolls 2, 4 form a roll gap 12 in a direction substantially perpendicular to the rolling direction x which roll gap determines the thickness of the rolling stock 10 leaving the multi-high roll stand 1.

[0022] The multi-high roll stand 1, on the one hand, is configured for loading the rolling stock 10 by means of a rolling force, that is substantially oriented perpendicularly to the rolling direction x, across a comparatively large rolling force area. In this connection, by means of an adjusting device, not illustrated in detail, the rolling force is adjustable at the support rolls 6, 8 and is transmitted by means of the working rolls 2, 4 onto the rolling stock 10. The multi-high roll stand 1 is configured for comparatively minimal rolling forces, as they are required, for example, for skin pass rolling of IF steels, as well as for comparatively high rolling forces and is thus particularly flexible with regard to its use.

[0023] On the other hand, the multi-high roll stands 1—particularly for comparatively small rolling forces—is configured for an especially precise adjustment of the thickness of the rolling stock 10. For this purpose, a control device 20 is correlated with the multi-high roll stand 1 via which the working rolls 2, 4, for the adjustment of the gap width of the roll gap 12, are movable in a direction substantially parallel to the rolling direction. For this purpose, each working roll 2, 4 is moveably supported at its ends in a direction parallel to the rolling direction x. Moreover, each working roll 2, 4 has correlated therewith an adjusting system 22 or 24. The adjusting system 22 correlated with the working roll 2 comprises in this connection a hydraulically actuated adjusting piston 26 which is loadable by means of an adjusting device 28 configured as a pressure transponder with an adjusting pressure. In analogy, the adjusting system 24 correlated with the second working roll 4 comprises an adjusting piston 30 which is loadable by means of an adjusting device 32 in the form of a pressure transponder with adjusting pressure.

[0024] For adjusting the position of each working roll 2, 4 in the rolling direction x, the output side of the control device is connected by data lines 34, 36 to the adjusting device 28, 32. By means of the data lines 34, 36 the common control device presets an adjusting value S in the adjusting devices 28, 32, respectively, and, by means of theses values S, the adjustment of an adjusting pressure is realized via the respective adjusting device 28 or 32; the adjusting pressure, in turn, determines the respective position of the working roll 2 or 4 in the rolling direction X.

[0025] The common control device 20 is configured for readjusting the position adjustment of the working rolls 2, 4 in the rolling direction x as a function of the thickness of the rolling stock 10. For this purpose, the input side of the common control device 20 is connected by means of the data line 40 with a measured value (measurement) transponder 42, configured to determine the thickness of the rolling stock 10. The common control device readjusts by means of the adjusting values S the positions of the working rolls 2, 4 in the rolling direction X until the thickness of the rolling stock 10 measured by the measured value transponder 42 corresponds to a nominal (preset) value Sw. The nominal value Sw, as a function of a predetermined use, can be selected from a plurality of nominal values Sw provided in a data memory system 44 connected to the common control device 20.

[0026] As a result of the continuously maintained contact provided by the rolling force between each working roll 2, 4 and the correlated support roll 6, 8, the respective working roll 2, 4 rolls on the surface of the support roll 6, 8 correlated therewith. As a result of these boundary conditions, the movement of the respective working roll 2, 4 in a direction parallel to the rolling direction x results also in a change of the position of the respective working roll 2, 4 in a direction perpendicularly to the rolling direction x and thus in a change of the gap width of the roll gap 12. As a result of the geometric conditions with regard to the arrangement of the working rolls 2, 4 substantially centrally between the support rolls 6, 8, a comparatively generous spatial movement of the working rolls 2, 4 in a direction parallel to the rolling direction x causes only a minimal change of their position in a direction perpendicular to the rolling direction x. Accordingly, across a comparatively large adjusting stroke in the direction parallel to the rolling direction x, a comparatively minimal and thus high-resolution change of the gap width of the roll gap 12 can be obtained. Accordingly, the control of the adjustment of the roll gap 12 is of relatively high precision even for comparatively minimal rolling forces.

[0027] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. A multi-high roll stand having several driven support rolls and having several working rolls frictionally driven by the support rolls, wherein the support rolls form a roll gap defining a thickness of rolling stock guided between the working rolls in a rolling direction, wherein the working rolls are configured to be moveable in a direction substantially parallel to the rolling direction for adjusting a gap width of the rolling gap.

2. The multi-high roll stand according to claim 1, wherein the working rolls are substantially horizontally movable for adjusting the gap width of the rolling gap.

3. The multi-high roll stand according to claim 1, wherein the working rolls have an adjusting device, respectively, wherein the adjusting devices of the working rolls are configured to adjust a position of the working rolls in the rolling direction, wherein the multi-high roll stand further comprises a common control device connected to the adjusting devices, wherein the common control device provides a set value for each one of the adjusting devices as a function of a measured value of a thickness of the rolling stock and as a function of the preset value for the thickness of the rolling stock.

4. The multi-high roll stand according to claim 3, wherein the adjusting devices acting on the working rolls are hydraulic adjusting devices.

5. The multi-high roll stand according to claim 3, further comprising a measurement transducer connected to an input of the common control device.

6. The multi-high roll stand according to claim 3, wherein the common control device has a memory component configured to store several nominal preset values for the thickness of the rolling stock.

7. A method for operating a multi-high roll stand according to claim 1, comprising the step of adjusting a thickness of the rolling stock by moving the working rolls in a direction substantially parallel to the rolling direction.

8. The method according to claim 7, further comprising the steps of comparing an actual measured value of the thickness of the rolling stock with a nominal value of the thickness of the rolling stock and using a result of the step of comparing in the step of adjusting.