METHOD OF AND APPARATUS FOR ROLLING STRIP OF FLUCTUATING THICKNESS

Abstract

An apparatus for rolling strip having a periodically fluctuating strip thickness has a roll stand with a set of rollers defining a gap, an adjustment actuator for adjusting the gap of the set of rollers, unwinder for feeding the strip with an initial thickness to an intake side of the roller gap, winder for receiving the strip with a desired final thickness from an output side of the gap, respective upstream and roller assemblies each having an immersion roller provided upstream of the roll stand between the unwinder and the roll stand and downstream of the roll stand between the roll stand and the winder. The strip is guided around the immersion rollers. A controller sets positions of the immersion rollers while operating the rollers of the roll stand at a constant roller speed, for determining the roller gap in dependence on the setting of the rollers.

Claims

1. An apparatus for rolling strip having a periodically fluctuating strip thickness, the apparatus comprising: a roll stand with a set of rollers defining a gap; an adjustment actuator for adjusting the gap of the set of rollers; unwinding means for feeding the strip with an initial thickness to an intake side of the roller gap; winding means for receiving the strip with a desired final thickness from an output side of the gap; respective upstream and roller assemblies each having an immersion roller provided upstream of the roll stand between the unwinding means and the roll stand and downstream of the roll stand between the roll stand and the winding means, the strip being guided around the immersion rollers; control means for setting positions of the immersion rollers while operating the rollers of the roll stand at a constant roller speed, for determining the roller gap in dependence on the setting of the rollers and thereby compensating for changes in the speed of the rolled material on the intake and output sides of the roll stand, and for operating the unwinding means and the winding means in a tension-controlled manner.

2. The apparatus defined in claim 1, further comprising: a respective support roller for the strip upstream of each immersion roller and downstream of each immersion roller over which the strip is guided, and that each support roller having a strip-length or strip-speed detector.

3. The apparatus defined in claim 1, wherein the unwinding means and the winding means are each provided with a respective tension-measuring device by means of which the power supply to drive motors of the winding and unwinding means can be controlled.

4. The apparatus defined in claim 1, wherein the detects the setting of the rollers for a predeterminable roller gap and in accordance with the detected setting controls the positions of the immersion rollers.

5. The apparatus defined in claim 1, wherein the rollers rotates the rollers of the roll stand at a constant speed.

6. A method of operating an apparatus for rolling strip having a periodically fluctuating strip thickness, the apparatus having: a roll stand with a set of rollers defining a gap; an adjustment actuator for adjusting the gap of the set of rollers; unwinding means for feeding the strip with an initial thickness to an intake side of the roller gap; and winding means for receiving the strip with a desired final thickness from an output side of the gap, the method comprising the steps of: determining the final thickness by the roller gap; providing upstream and downstream roller assemblies each with a respective immersion roller that can be adjusted transversely to the direction of travel of the strip and around which the strip is guided both upstream of the roll stand between the unwinding means and the roll stand and downstream of the roll stand between the roll stand and the winding means; controlling with a controller positions of the immersion rollers in dependence on a setting of the rollers of the roll stand, so that changes in the speed of the rolled material on the intake side and on the output side of the roll stand are compensated for by the change in position and the unwinding means and the winding means are operated in a tension-controlled manner.

7. The method defined in claim 6, further comprising the step of: detecting a length and speed of the strip both upstream and downstream of each immersion roller feeding an output corresponding thereto to the controller for the roller system; and the controller, based on the outputs, correcting positions of the immersion rollers.

8. The method defined in claim 6, further comprising the steps, for of adjusting a tension of the winding and unwinding means, of: detecting tensile forces of the winding and unwinding means and feeding outputs correspond thereto the controller; and with the controller operating respective power supplies of the winding and unwinding means such that strip tension is adapted to the respective requirements from the operating parameters.

9. The method defined in claim 6, further comprising the steps of: detecting a setting of the rollers for a predetermined roller gap and feeding signals correspond thereto to the controller; and with the controller, moving the immersion rollers to a target position associated with the roller gap that is stored in the control as a data pattern.

10. The method defined in claim 6, further comprising the step of: operating the rollers of the roll stand at a constant speed.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0021] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0022] FIG. 1 is a schematic side view of the apparatus according to the invention;

[0023] FIG. 2 is a detail view of the invention; and

[0024] FIG. 3 is another detail view of the invention.

SPECIFIC DESCRIPTION OF THE INVENTION

[0025] As seen in FIG. 1 an apparatus according to the invention for rolling strip 1 having a periodically fluctuating strip thickness and moving in a travel direction 2. The apparatus comprises a roll stand 3 whose essential parts are shown—namely, a set of two rollers 4 and 5. Furthermore, an adjustment actuator 6 is shown schematically that serves to adjust the gap of the rollers 4 and 5.

[0026] The roller gap, which can be seen particularly well in FIGS. 2 and 3, is set according to the desired strip thickness to be produced. The strip 1 having an initial thickness is fed to the roller gap from an unwinder 7, and from there the strip 1 having the respective desired final thickness is fed on the output side to a winder 8. Roller assemblies each with at least one respective immersion roller 9, 10 are provided both between the unwinder 7 and the roll stand 3 and between the roll stand 3 and the winder 8. Pairs of guide rollers 13, 14 and 15, 16 flank the immersion rollers 9 and 10 that can be moved as shown by the arrows 11 and 12 toward and away from a plane defined by the rotation axes of the respective guide rollers 13, 14, 15, and 16. An additional guide and deflection roller 17 is provided between of the upstream guide roller 13 and the unwinder 7 and another guide and deflection roller 18 is between the guide roller 16 and the winder 8. The strip 1 passing through is thus guided sequentially around the rollers 17, 13, 9, 14 and 15, 10, 16, and 18, in that order.

[0027] The immersion rollers 9 and 10 can be adjusted up and down as shown in the drawing plane by respective actuators 19 and 20 in the direction of the movement arrows 11 and 12 and are position-controlled in dependence on the setting of the rollers 4, 5 at a constant speed by the rollers 4, 5 of the roll stand 3 determining the roller gap in order to compensate for changes in the speed of the rolled material, i.e., the strip 1, on the intake side and on the output side of the roll stand 3. The unwinder 7 and the winder 8 are operated to control tension in the strip 1.

[0028] The support rollers 13, 14, 15, 16 that flank the immersion rollers 9 and 10 and over which the strip 1 is guided each have respective strip-length and strip-speed detectors 21, 22, 23, 24. Furthermore, the unwinder 7 and the winder 8 are each provided with a tension-measuring devices ZM that control power supplies 25, 26 of drive motors MA of the unwinder and winder 7, 8 in order to maintain the reel tension according to the requirements from the operating parameters.

[0029] Moreover, a controller 27 is provided that detects, processes and/or stores the set point for setting the rollers 4, 5 for a predeterminable roller gap and that controls the positions of the immersion rollers 9, 10 as a function thereof. For this purpose, the controller 27 communicates with the adjustment actuator 6, with the length and speed detectors 21, 22, 23, 24, and with the actuators 19, 20 for the immersion rollers 9, 10, so that the setting of the rollers 4, 5 for the predetermined roller gap is detected by the controller 27 and the immersion rollers 9, 10 are position-controlled as a function thereof.

[0030] The rollers 4, 5 of the roll stand 3 determining the roller gap are operated at a constant speed. In FIG. 1 of the drawing, the regions of constant speed of the strip 1 and variable speed of the strip 1 on the intake side and on the output side are designated by v.sub.E=constant, v.sub.E=variable, v.sub.A=variable, and v.sub.A=constant.

[0031] The entire region from the unwinder 7 to the roll stand 3 is referred to as the intake zone, and the region from the roll stand 3 to the winder 8 as the output zone.

[0032] The changes in the speed of the rolled material (strip 1) on the intake and output sides of the roll stand 3 resulting from the periodically fluctuating strip thicknesses at constant roller speed are compensated for by movement of the two immersion rollers 9 and 10. The immersion rollers 9, 10 are position-controlled. The control occurs directly by positioning the rollers 4, 5 in conjunction with signals for the rolled strip length. The two reels 7 and 8 are operated in a tension-controlled manner.

[0033] The aim is to determine the movement of the immersion rollers 9, 10 directly from the operating parameters of the rolling process. In this way, the direction of movement and the type of movement (constant speed, acceleration, or deceleration) of the immersion rollers 9, 10 is determined by the profile of the rolled material.

[0034] As for controlling movement of the immersion rollers, this is derived directly from the signals for the setting of the rollers as well as from the strip length signals that are detected by the detectors 21, 22, 23, 24.

[0035] The movement of the immersion rollers 8, 10 is periodic. Each period of the immersion rollers 9, 10 at the intake and output is time-correlated exactly to a rolling period.

[0036] As shown in FIGS. 2 and 3, in order to ensure that a movement T of the immersion rollers 9, 10 is correlated with precision, the profile of the rolled material of a rolling period L is subdivided into segments. The individual segments each comprise regions of constant strip thickness (a with s.sub.1 and b with s.sub.2) and of variable strip thickness (Y and Z). By determining the individual cross sections, a cross-sectionally identical and hence mass-equivalent segment is ensured at the roller intake (a.sub.E and b.sub.E as well as y.sub.E and z.sub.E with initial strip thickness s). From this, for a rolling period L, one obtains the mass-equivalent strip length on the intake side L.sub.E.

[0037] One can calculate the average strip thickness s.sub.M on the output side from the individual segments of a rolling period. This average strip thickness is an equivalent for the average speed at the roller output (V.sub.AM) and thus also determines the average speed on the intake side (V.sub.EM). The reel speeds on the intake and output side then each correspond to these average speeds, as if the incoming strip having the thickness s were rolled to the thickness s.sub.M under constant conditions.

[0038] This segment-by-segment manner of viewing the relationships between the average strip thickness and the thickness in a segment enables inferences to be made with respect to the respective speed ratio. The greater the differences in thickness are, the greater the difference in speed in this segment of the roller output is.

[0039] For the roller intake as well, the movements of the roller setting and hence the rolling profile are also crucial for the current speed. Given a constant roller speed and consistent tensions, the intake speed is greater in the case of a low reduction ratio than with a high reduction ratio. Cross-sectionally identical segments in the roller intake can always be correlated with the segments in the output. From the segments of a complete period, it is then possible to determine both an average speed on the intake side and the movement of the immersion rollers 9, 10 on a segment-by-segment basis.

[0040] The type and direction of the immersion roller movements 11, 12 (constant speed up/down, deceleration, dead center, or acceleration) can thus be derived from the rolling parameters. In order to precisely correlate the movement of the immersion rollers 9, 10 to the rolling process, the outgoing rolling profile of a period L is compared on a segment-by-segment basis with a portion of equal volume and length L having the average thickness s.sub.M.

[0041] With the thickness s.sub.2, the segment b is thicker than the average thickness s.sub.M. This means that the speed of the outgoing strip v.sub.A2 is less than the average speed v.sub.AM. To compensate for this, a constant upward movement of the immersion roller is required. The segment Z is divided into two portions (Z.sub.1 and Z.sub.2) by crossing the thickness of the rolled profile with the average thickness. In the region Z.sub.1, the thickness is reduced until it reaches the average thickness. This means that the speed of the outgoing strip is accelerated up to the average speed v.sub.AM. At the point of intersection, the average speed and the speed of the outgoing strip are identical. For the immersion roller, this means that the upward movement of the immersion roller is slowed, and the roller reaches top dead center at the point of intersection. In the region Z.sub.2, the thickness is further reduced until it reaches the thickness s.sub.1. The speed of the outgoing strip is accelerated until it reaches the speed v.sub.A1. The immersion roller is accelerated downward in this region.

[0042] With the thickness s.sub.1, the segment a is thinner than the average thickness s.sub.M. The speed of the outgoing strip v.sub.A1 is therefore greater than the average speed v.sub.AM. The immersion roller compensates for this through a constant downward movement.

[0043] For the segment Y, it holds that the speed of the outgoing strip is reduced until the speed v.sub.A2 is reached. In the region Y.sub.1, the downward movement is slowed until bottom dead center is reached, and, in the region Y.sub.2, the immersion roller is accelerated upward again. The control of the movement of the immersion rollers at the output follows the control of the immersion rollers at the intake.

[0044] In the segment b.sub.E, the speed of the incoming strip v.sub.E2 is greater than the average speed, and in segment a.sub.E, the speed v.sub.E1 is lower.

[0045] Movement of the immersion rollers compensates for this and, at constant speed, is moved up in the segment b.sub.E and down in the segment a.sub.E. The segments Z.sub.E and Y.sub.E are also characterized by slowing, dead center, and acceleration. The points at dead center are each controlled isochronously with the output-side points at dead center.

[0046] In order to monitor and, as appropriate, correct the movements of the immersion rollers, the rollers are provided with pulse generators for detecting strip length and monitoring speed before approaching and after leaving an immersion roller.

[0047] The signals for movement of the immersion roller can thus be coordinated with precision with the roller setting and hence to the rolling profile.

[0048] Corrections can become necessary, for example, if the influence of the roller diameters becomes so great in the case of very fast changes in the roller setting that the material fractions that are additionally blocked or released influence movement of the immersion rollers or if deviations in the thickness of the strip influence the rolling process.

[0049] Since movement of the immersion rollers can be adapted very precisely to the roller setting and hence to the respective change in profile, a constant winding speed and therefore an exact tension control for both reels poses no difficulty.

[0050] It remains to be noted that the processes shown in the illustrated embodiment are only an example. More than four segments for a rolling period are also possible.

[0051] The invention is not limited to the illustrated embodiments, but rather can be varied in many respects within the framework of the disclosure.

[0052] All of the individual and combined features disclosed in the description and/or drawing are regarded as being essential to the invention