CA2278929A1 - Method and apparatus for correcting the strip travel during strip rolling - Google Patents
Method and apparatus for correcting the strip travel during strip rolling Download PDFInfo
- Publication number
- CA2278929A1 CA2278929A1 CA 2278929 CA2278929A CA2278929A1 CA 2278929 A1 CA2278929 A1 CA 2278929A1 CA 2278929 CA2278929 CA 2278929 CA 2278929 A CA2278929 A CA 2278929A CA 2278929 A1 CA2278929 A1 CA 2278929A1
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- CA
- Canada
- Prior art keywords
- strip
- roll
- roll stand
- tensile stress
- measuring device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 13
- 238000005096 rolling process Methods 0.000 title claims abstract description 13
- 238000005259 measurement Methods 0.000 claims abstract description 13
- 238000009826 distribution Methods 0.000 claims description 20
- 230000001105 regulatory effect Effects 0.000 claims description 13
- 238000010586 diagram Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/68—Camber or steering control for strip, sheets or plates, e.g. preventing meandering
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Metal Rolling (AREA)
Abstract
A method and an apparatus for correcting the strip travel when rolling strips in at least one roll stand, wherein measurement values relevant for the tensile stresses are measured on opposite sides of the exiting strip. Subsequently, the difference of the tensile stress values is computed in a control circuit as an actual value and the strip travel is corrected when the actual value deviates from a desired value by changing the roll adjustment of the at least one roll stand. The tensile stress values are measured at that strip portion which travels over a tension measuring device which, seen in the strip travel direction, is arranged behind the roll stand and transversely of the strip.
Description
METHOD AND APPARATUS FOR CORRECTING THE
STRIP TRAVEL DURIING STRIP ROLLING
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a method and an apparatus for correcting the strip travel when rolling strips in at least one roll stand.
STRIP TRAVEL DURIING STRIP ROLLING
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a method and an apparatus for correcting the strip travel when rolling strips in at least one roll stand.
2. Description of the Related Art In a rolling train composed of two rolls stands, low specific return tensions at the first roll stand produce the problem that the strip does not travel uniformly but breaks out toward the side.
When it becomes apparent that the strip travels toward the side, it is too late to start a strip regulation. The strip tears, or defects due to overlap occur. Consequently, the rolls are damaged which makes it necessary to exchange the rolls, and a certain amount of the strip becomes scrap.
European Patent Application 0 752 285 A2 discloses a met!~od and an apparatus for rolling strips which have over the width thereof a uniform thickness and/or length distribution, wherein it is possible to compensate for strip travel to the side. For this purpose, a control roller is provided which can be pivoted in its position relative to the strip and which is arranged on the entry side or the exit side of a rolling mill. The distribution of the tensile stresses over the width of the strip are measured by means of a measuring device and the control roller is adjusted in dependence on the measured distribution of the tensile stresses until the measured stress distribution corresponds to a desired value.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a method and an apparatus for regulating the strip travel, particularly in roll stands with low return or back tension, wherein additional regulation devices, for example, adjustable control rollers, are unnecessary.
In accordance with the present invention, measurement values relevant for the tensile stresses are measured on opposite sides of the exiting strip. Subsequently, the difference of the tensile stress values is computed in a control circuit as an actual value and the strip travel is corrected when the actual value deviates from a desired value by changing the roll adjustment of the at least one roll stand.
Measurement values relevant for the tensile stresses are, for example, the force which produces tension values in relation to the surface area. In addition, all other types of measurement values can be measured which are in a fixed computational relationship with the tensile stress. This means that an indirect measurement of the tensile stress values takes place.
When it becomes apparent that the strip travels toward the side, it is too late to start a strip regulation. The strip tears, or defects due to overlap occur. Consequently, the rolls are damaged which makes it necessary to exchange the rolls, and a certain amount of the strip becomes scrap.
European Patent Application 0 752 285 A2 discloses a met!~od and an apparatus for rolling strips which have over the width thereof a uniform thickness and/or length distribution, wherein it is possible to compensate for strip travel to the side. For this purpose, a control roller is provided which can be pivoted in its position relative to the strip and which is arranged on the entry side or the exit side of a rolling mill. The distribution of the tensile stresses over the width of the strip are measured by means of a measuring device and the control roller is adjusted in dependence on the measured distribution of the tensile stresses until the measured stress distribution corresponds to a desired value.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a method and an apparatus for regulating the strip travel, particularly in roll stands with low return or back tension, wherein additional regulation devices, for example, adjustable control rollers, are unnecessary.
In accordance with the present invention, measurement values relevant for the tensile stresses are measured on opposite sides of the exiting strip. Subsequently, the difference of the tensile stress values is computed in a control circuit as an actual value and the strip travel is corrected when the actual value deviates from a desired value by changing the roll adjustment of the at least one roll stand.
Measurement values relevant for the tensile stresses are, for example, the force which produces tension values in relation to the surface area. In addition, all other types of measurement values can be measured which are in a fixed computational relationship with the tensile stress. This means that an indirect measurement of the tensile stress values takes place.
The desired value is intended to mean a symmetrical stress distribution in the roll gap which corresponds to a difference of the tensile stresses of zero. If necessary, other desired values can be given.
The present invention starts from the finding that, even before a travel of the strip toward the side becomes visible, the change of the strip travel can be determined by changing forces or stresses which are measured at the exit side of the strip by suitable means. In accordance with the invention, a strip regulation takes place by the direct coupling of the measured tensile stress values and the change of the roll gap of the roll stand. This makes it possible to carry out a strip regulation without additional devices, such as the conventional pivotable control roller.
In accordance with a preferred feature, the tensile stress values are measured at that strip portion which travels over a tension measuring device which, seen in the strip travel direction, is arranged behind the roll stand and transversely of the strip.
The roll gap profile is changed in such a way that the tensile stress distribution in the roll gap once again is symmetrical relative to the center lines of the work rolls. This has the result that the strip travels in the middle of the roll stand and travel toward the side is prevented.
The apparatus according to the present invention for carrying out the method described above has the following features. Means for measuring measurement values relevant for the tensile stress values; a regulating device which computes on the basis of these values the difference of the tensile stress values and which determines, by a comparison with a desired value, adjusting signals for an adjusting system for changing the roll gap of the roll stand.
The regulation takes place through a change of the adjustment, i.e., swivelling of the rolls of the roll stand and not by means of additsonal control rollers.
The means for measuring measurement values relevant with respect to the stress values may be any type of device which can meet this object.
For measuring the stress values, preferably a strip tension measuring device is proposed which, as seen in the strip travel direction, is arranged following the roll stand and transversely of the strip travel. The values are determined at the drive side as well as on the operator side of the strip tension measuring device.
In accordance with an especially preferred embodiment, the measuring devices are load cells or pressure gauges. Using the known or computed surface area conditions of the strip, a conversion into stress values takes place.
In this connection, the drive side is intended to mean that side of the strip which corresponds to the side of the roll stand equipped with the drives. The opposite operator side, on the other hand, is the freely accessible other side of the roll stand.
In accordance with a preferred embodiment, the rolling train is composed of two tandem stands and a strip tension measuring device arranged between the two stands.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
Fig. 1 is a schematic side view of a rolling train composed of two stands;
Fig. 2 is a schematic partial top view of the rolling trains of Fig . 1;
Fig. 3a and Fig. 3b are diagrams showing the difference of the measured tensile stress values (drive side minus operator side) over time; and Figs. 4a, 4b, and 4c are diagrams showing different tensile stress distributions ~in the roll gap of the roll stand arranged in front of the tension measuring device in the strip travel direction.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The rolling train illustrated in Fig. 1 is composed of two roll stands 1 and 1', wherein each roll stand is composed of two work rolls 2a, 2b and 2a' and 2b' and two back-up rolls 3a, 3b and 3a' and 3b'. Arranged between the two roll stands 1, 1' is a strip tension measuring device 4. The strip 5 to be rolled is conveyed over rollers 6a, 6b through the first roll stand 1 in the strip travel direction as indicated by a horizontal arrow, wherein the strip then enters the second roll stand 1' after travelling through the strip tension measuring device 4.
As shown in Fig. 2, using two load cells 7, 7' arranged on the drive side A and the operator side B of the strip 5, respectively, the tensile stress values are measured on both sides of the strip 5 and are supplied to a regulating device, not shown. The regulating device supplies adjusting signals to an adjusting system, not shown, which automatically regulates the roll gap in the roll stand 1 and, thus, adjusts the stress distribution in the roll gap to a desired distribution, for example, a symmetrical distribution. Fig. 2 only shows the upper work roll 2a and the center line thereof in the longitudinal direction.
Consequently, the apparatus according to the present invention acting as a strip travel correction system is composed of means for measuring tensile stress values, a regulating device, not shown, and an adjusting system, also not shown, for the roll gap of a roll stand 1 which are operated using a regulating circuit.
It is also possible to influence this regulating circuit manually, for example, by changing the command variable.
Figs. 3a and 3b illustrate by means of two curves the difference values of the tensile stresses on the drive side A and the operator side B in dependence on time. The positive values represent greater tensile stresses on the drive side A as compared to the operator side B.
When the tensile stress increases on the drive side over time, an asymmetrical tensile stress distribution occurs in the roll gap. The difference between the two tensile stresses is positive, as indicated in Fig. 3a.
In order to correct the strip travel, the roll gap must be made smaller on the drive side. This is effected by changing the adjustment of the rolls. In accordance with the invention, this change of the roll gap is effected using an automated regulating system. It is also possible to carry out the regulation manually in dependance on the measured tensile stress values.
Fig. 3b shows the opposite case in which the tensile stress increases on the operator side of the strip. The difference between the measured tensions on the two sides of the strip becomes greater over time. This is apparent from the increasing magnitude of the negative values in Fig. 3b. The regulation of the strip travel takes place by a reduction of the roll gap on the operator side.
This regulated adjustment of the roll gap ensures a steady symmetrical stress distribution in the roll gap. This produces the effect that the strip travels in the middle of the roll stand and prevents the strip from travelling to the side.
In order to further illustrate the invention, Fig. 4 shows the stress distributions in the roll gap W in three cases. In the first case shown in Fig. 4a, an asymmetrical stress distribution exists. The tensile stresses on the operator side A
are greater than the values on the drive side A. The total difference between the stress values on the drive side and the operator side is negative. The strip travel is controlled by reducing the roll gap profile on the operator side, i.e., by pivoting the rolls toward the operator side. This renders the stress distribution uniform relative to the center lines of the rolls. A symmetrical stress distribution is achieved in the roll gap.
Fig. 4b shows a symmetrical stress distribution in the roll gap. Consequently, the difference between the stress values is zero.
The distribution shown in Fig. 4c occurs in the case of a asymmetrical stress distribution with a greater stress at the drive side A. The difference between the tensile stress values is positive. The regulation and influencing of the strip travel is achieved by reducing the roll gap on the drive side A.
The method and apparatus proposed in accordance with the present invention'are to be used primarily in hot-rolling or cold-rolling mills with one or more stands.
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.
The present invention starts from the finding that, even before a travel of the strip toward the side becomes visible, the change of the strip travel can be determined by changing forces or stresses which are measured at the exit side of the strip by suitable means. In accordance with the invention, a strip regulation takes place by the direct coupling of the measured tensile stress values and the change of the roll gap of the roll stand. This makes it possible to carry out a strip regulation without additional devices, such as the conventional pivotable control roller.
In accordance with a preferred feature, the tensile stress values are measured at that strip portion which travels over a tension measuring device which, seen in the strip travel direction, is arranged behind the roll stand and transversely of the strip.
The roll gap profile is changed in such a way that the tensile stress distribution in the roll gap once again is symmetrical relative to the center lines of the work rolls. This has the result that the strip travels in the middle of the roll stand and travel toward the side is prevented.
The apparatus according to the present invention for carrying out the method described above has the following features. Means for measuring measurement values relevant for the tensile stress values; a regulating device which computes on the basis of these values the difference of the tensile stress values and which determines, by a comparison with a desired value, adjusting signals for an adjusting system for changing the roll gap of the roll stand.
The regulation takes place through a change of the adjustment, i.e., swivelling of the rolls of the roll stand and not by means of additsonal control rollers.
The means for measuring measurement values relevant with respect to the stress values may be any type of device which can meet this object.
For measuring the stress values, preferably a strip tension measuring device is proposed which, as seen in the strip travel direction, is arranged following the roll stand and transversely of the strip travel. The values are determined at the drive side as well as on the operator side of the strip tension measuring device.
In accordance with an especially preferred embodiment, the measuring devices are load cells or pressure gauges. Using the known or computed surface area conditions of the strip, a conversion into stress values takes place.
In this connection, the drive side is intended to mean that side of the strip which corresponds to the side of the roll stand equipped with the drives. The opposite operator side, on the other hand, is the freely accessible other side of the roll stand.
In accordance with a preferred embodiment, the rolling train is composed of two tandem stands and a strip tension measuring device arranged between the two stands.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
Fig. 1 is a schematic side view of a rolling train composed of two stands;
Fig. 2 is a schematic partial top view of the rolling trains of Fig . 1;
Fig. 3a and Fig. 3b are diagrams showing the difference of the measured tensile stress values (drive side minus operator side) over time; and Figs. 4a, 4b, and 4c are diagrams showing different tensile stress distributions ~in the roll gap of the roll stand arranged in front of the tension measuring device in the strip travel direction.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The rolling train illustrated in Fig. 1 is composed of two roll stands 1 and 1', wherein each roll stand is composed of two work rolls 2a, 2b and 2a' and 2b' and two back-up rolls 3a, 3b and 3a' and 3b'. Arranged between the two roll stands 1, 1' is a strip tension measuring device 4. The strip 5 to be rolled is conveyed over rollers 6a, 6b through the first roll stand 1 in the strip travel direction as indicated by a horizontal arrow, wherein the strip then enters the second roll stand 1' after travelling through the strip tension measuring device 4.
As shown in Fig. 2, using two load cells 7, 7' arranged on the drive side A and the operator side B of the strip 5, respectively, the tensile stress values are measured on both sides of the strip 5 and are supplied to a regulating device, not shown. The regulating device supplies adjusting signals to an adjusting system, not shown, which automatically regulates the roll gap in the roll stand 1 and, thus, adjusts the stress distribution in the roll gap to a desired distribution, for example, a symmetrical distribution. Fig. 2 only shows the upper work roll 2a and the center line thereof in the longitudinal direction.
Consequently, the apparatus according to the present invention acting as a strip travel correction system is composed of means for measuring tensile stress values, a regulating device, not shown, and an adjusting system, also not shown, for the roll gap of a roll stand 1 which are operated using a regulating circuit.
It is also possible to influence this regulating circuit manually, for example, by changing the command variable.
Figs. 3a and 3b illustrate by means of two curves the difference values of the tensile stresses on the drive side A and the operator side B in dependence on time. The positive values represent greater tensile stresses on the drive side A as compared to the operator side B.
When the tensile stress increases on the drive side over time, an asymmetrical tensile stress distribution occurs in the roll gap. The difference between the two tensile stresses is positive, as indicated in Fig. 3a.
In order to correct the strip travel, the roll gap must be made smaller on the drive side. This is effected by changing the adjustment of the rolls. In accordance with the invention, this change of the roll gap is effected using an automated regulating system. It is also possible to carry out the regulation manually in dependance on the measured tensile stress values.
Fig. 3b shows the opposite case in which the tensile stress increases on the operator side of the strip. The difference between the measured tensions on the two sides of the strip becomes greater over time. This is apparent from the increasing magnitude of the negative values in Fig. 3b. The regulation of the strip travel takes place by a reduction of the roll gap on the operator side.
This regulated adjustment of the roll gap ensures a steady symmetrical stress distribution in the roll gap. This produces the effect that the strip travels in the middle of the roll stand and prevents the strip from travelling to the side.
In order to further illustrate the invention, Fig. 4 shows the stress distributions in the roll gap W in three cases. In the first case shown in Fig. 4a, an asymmetrical stress distribution exists. The tensile stresses on the operator side A
are greater than the values on the drive side A. The total difference between the stress values on the drive side and the operator side is negative. The strip travel is controlled by reducing the roll gap profile on the operator side, i.e., by pivoting the rolls toward the operator side. This renders the stress distribution uniform relative to the center lines of the rolls. A symmetrical stress distribution is achieved in the roll gap.
Fig. 4b shows a symmetrical stress distribution in the roll gap. Consequently, the difference between the stress values is zero.
The distribution shown in Fig. 4c occurs in the case of a asymmetrical stress distribution with a greater stress at the drive side A. The difference between the tensile stress values is positive. The regulation and influencing of the strip travel is achieved by reducing the roll gap on the drive side A.
The method and apparatus proposed in accordance with the present invention'are to be used primarily in hot-rolling or cold-rolling mills with one or more stands.
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 (9)
1. A method of correcting strip travel when rolling strips in at least one roll stand, the method comprising measuring measurement values relevant with respect to tensile stress on opposite sides of the strip exiting from the at least one roll stand, computing a difference of the tensile stress values as an actual value in a regulating circuit, and, when the actual value deviates from a desired value, correcting the strip travel by changing a roll adjustment of the at least one roll stand.
2. The method according to claim 1, comprising measuring the measurement values at a strip portion which travels over a tension measuring device arranged, as seen in a strip travel direction, behind the at least one roll stand and transversely of the strip.
3. The method according to claim 1, wherein the at least one roll stand has a drive side and an operator side, comprising producing a change of a roll gap of the at least one roll stand by pivoting the rolls of the stand in a direction toward one of the drive side and the operator side.
4. The method according to claim 3, comprising changing a roll gap profile such that a tensile stress distribution in the roll gap is symmetrical relative to a center line of the roll stand.
5. The method according to claim 1, comprising manually influencing the regulating circuit.
6. An apparatus for correcting a strip travel when rolling strips in at least one roll stand, comprising means for measuring at opposite sides of the strip exiting the at least one roll stand measurement values relevant for tensile stress of the strip, a regulating device for computing a difference of tensile stress values on opposite sides of the strip as an actual value, and an adjusting system for changing a roll gap of the at least one roll stand, wherein the regulating device is configured to determine adjusting signals for the adjusting system by comparing the actual value with a desired value.
7. The apparatus according to claim 6, wherein the means for measuring the measurement values are comprised of a tension measuring device with load cells in the tension measuring device.
8. The apparatus according to claim 6, wherein the means for measuring the measurement values are comprised of a tension measuring device with load cells on a drive side and an operator side of the tension measuring device.
9. The apparatus according to claim 6, wherein the means for measuring the measurement values are comprised of a tension measuring device mounted between two successively arranged roll stands.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833322 | 1998-07-24 | ||
| DE19833322.6 | 1998-07-24 | ||
| DE19843039.6 | 1998-09-19 | ||
| DE19843039A DE19843039A1 (en) | 1998-07-24 | 1998-09-19 | Method and device for correcting the strip run during strip rolling |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2278929A1 true CA2278929A1 (en) | 2000-01-24 |
Family
ID=26047665
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2278929 Abandoned CA2278929A1 (en) | 1998-07-24 | 1999-07-23 | Method and apparatus for correcting the strip travel during strip rolling |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0974406A2 (en) |
| JP (1) | JP2000051916A (en) |
| CA (1) | CA2278929A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103203373B (en) * | 2012-01-12 | 2015-07-22 | 宝山钢铁股份有限公司 | Strip deviation correction control method for cold rolling pickling unit |
| CN102652959A (en) * | 2012-05-04 | 2012-09-05 | 中国重型机械研究院有限公司 | Double four-roll temper mill |
| EP3599038A1 (en) * | 2018-07-25 | 2020-01-29 | Primetals Technologies Austria GmbH | Method and device for determining the lateral contour of a running metal strip |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19524729A1 (en) | 1995-07-07 | 1997-01-16 | Sundwiger Eisen Maschinen | Method and device for rolling strips with a non-uniform thickness and / or length distribution across their width |
-
1999
- 1999-07-17 EP EP19990113959 patent/EP0974406A2/en not_active Withdrawn
- 1999-07-23 JP JP11209612A patent/JP2000051916A/en not_active Withdrawn
- 1999-07-23 CA CA 2278929 patent/CA2278929A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0974406A2 (en) | 2000-01-26 |
| JP2000051916A (en) | 2000-02-22 |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |