ROLLING MILL, CONTROL METHOD OF THE ROLLING MILL, ROLLING
APPARATUS AND CONTROL METHOD OF THE ROLLING APPARATUS
BACKGROUND OF THE INVENTION
Field of the Invention [0001]
The present invention relates to a rolling-mill control method and rolling apparatus.
Description of the Related Art [0002]
In a conventional cold rolling mill, in particular, a continuous rolling mill, so-called, Tandem Cold Mill, having plural mills installed in a row, materials (coils) rolled are welded together at an entry side part of the continuous rolling mills and are continuously rolled. Because rolled products differ in the steel type, the strip thicknesses, and the strip width between coils, the rolling operation schedule has to be changed every time a welded point passes through the mill. [0003]
However, if there is a large difference in the strip width, the strip thickness, the strip material, and the like between a coil being currently rolled and a coil subjected to the following rolling operation, the strip rolled in the following rolling operation may break at a welded point. Therefore the mill is once stopped the mill when the welded point passes through, work rolls are opened from a coil with the roll gap being expanded, and operation of the mill restarts after the welded point of the coil passes through.
JP2004-34039A and JPS58-168410 disclose technologies related to this
application. [0004]
Conventionally, when the speed of a rolling stand is controlled, in general, a mass-flow balance of the rolled strip is maintained to prevent the change in the strip thickness and the tension from affecting a subsequent rolling stand. If one of the rolling stands is taken as a reference one, its speed is not adjusted and a speed of the other rolling stand is adjusted in a certain direction. [0005]
For example, when a speed adjustment reference is output to an upstream-side rolling stand without changing the speed with reference to a downstream-side rolling stand while keeping the speed of the downstream-side rolling stand constant, the speed of an entry-side bridle roll is controlled. [00061
Moreover, a control output for the tension adjustment control between rolling stands is made by controlling the speed of a downstream-side rolling stand without changing the speed of an upstream-side rolling stand with reference to the upstream-side rolling stand. In this case, a delivery-side bridle roll is subjected to a control. [0007]
Conventionally, a reference-speed-manipulation-end is determined before starting rolling operation and a strip thickness control and a tension control matching the reference-speed-manipulation-end are selected and performed. JP2008-142728A, JPS58-205611 A, Japan Patent No. 2797872 and Japan Patent No. 3234431 disclose related technologies. [0008]
In the case of the foregoing technology, a stop mark is produced with work
rolls on a portion of the rolled strip on which the rolls stops. Moreover, because the work rolls are closed to the strip after having the welded point pass through and then a rolling operation gets restarted, the rolled strip becomes off-gauge until a strip thickness becomes within the allowable range after the operation is restarted. As a result, the yield of the rolled coil decreases. Furthermore, the operation efficiency also decreases, because the mill is stopped, the work rolls are opened off the strip therebetween, the rolled strip is fed until the welded point (welded point) passes through, the work rolls are closed again, and then the operation is restarted. [0009]
Regarding replacement of the work roll, every time the rolling mill is stopped, a stop mark is produced on the rolled strip. Accordingly the yield of product decreases, while at the same time, the rolling mill cannot be operated until the work rolls are opened off the rolled strip after the mill is stopped, the work roll is replaced, and closing the work rolls to the rolled strip becomes ready. Therefore the operation efficiency of rolling also decreases.
Accordingly, if the work rolls can be opened off the rolled strip and then contact it while the rolling operation is under way, it becomes unnecessary to stop the rolling mills and the yield and the production efficiency improve. Moreover, the operability of the continuous rolling mill can be remarkably improved and changing (replacement) of the work roll and changing the number of stands used for rolling while the mill is in operation become possible. [0010]
However, it is difficult to open and cause the work rolls to contact a rolled strip during a rolling operation, and various studies have been made so far, but only a few technologies can be applied to an actual operation field in practice.
Problems when the work rolls are opened and closed during rolling are that a rolled strip becomes so unstable during opening and closing of the work rolls that the rolled strip breaks, or the work rolls and the rolled strip slip with each other when the work rolls are opened and are made to contact the rolled strip. Therefore the rolled strip and the work rolls are likely to be scratched. [0011]
When stress is applied to the metal band of the rolled strip or the like, the rolled strip is deformed. A temporal deformation that the rolled strip recovers to the original condition after a load is applied and removed is referred to as an elastic deformation, while a permanent deformation that remains in the rolled strip after a load is applied and removed is referred to as a plastic deformation. Stress produced when a state transitions from elastic deformation to plastic deformation is called yield point.
The rolled strip is plastically deformed after rolled because of tension between rolling stands and load applied from the work rolls and the strip thickness at the delivery side of the mill becomes thinner than the strip thickness at the entry side thereof. The difference in the strip thickness between the entry side of the mill and the delivery side thereof is referred to as a reduction. [0012]
As load from the work roll is reduced, the reduction decreases. If the applied load becomes smaller than that for the yield point when a state transitions from plastic deformation to elastic deformation, the reduction becomes zero or extremely small. At this time, the speed of the rolled strip at the entry side of the mill becomes fast, and the speed of the rolled strip at the delivery side of the mill becomes slow, resulting in sharp increase of tension at
the entry side of the mill and at the delivery side thereof.
Moreover, when,the applied load from the work rolls to the strip that is in a elastic deformation state is increased and exceeds that for the yield point at a certain point, the strip transitions to the plastic deformation state. [0013]
At this time, because the reduction sharply increases, the speed of the rolled strip at the entry side of the mill becomes slow, and the speed of the rolled strip at the delivery side thereof becomes fast. As a result, tension sharply decreases at the entry side of the mill and at the delivery side thereof.
At a normal rolling speed, when tension of the rolled strip sharply changes, rolling becomes unstable, a defect in shape so-called an area contraction occurs, and tension at the strip edge increases, resulting in breaking down of the rolled strip. [0014]
Moreover, when the work roll is pulled off from the rolled strip, because the torque of a motor driving the work roll changes, the speed of the work roll changes and the speed of the rolled strip also changes. Then, the rolled strip and the work rolls slip with each other. Conversely, when the work rolls are made to come in contact with the rolled strip, the work rolls and the rolled strip also slip with each other because of a difference in speed between the work rolls and the rolled strip. [0015]
That is, when the work rolls are opened and closed while the mill is in operation (while the rolled strip is running), because there is produced a difference in speed between the work rolls and the rolled strip, slippage and scratches are caused.
Moreover, at the time of opening and closing of the work rolls, because the state of the rolled strip sharply changes from plastic deformation to elastic deformation or vice versa, tension changes so largely that the strip flatness is deteriorated. This causes area contraction and strip's break. [0016]
Accordingly, those skilled in the art seek a method and a rolling mill with which the work rolls are opened off and closed to the rolled strip with a minimum change in strip's tension and without any occurrence of slippage between the rolled strip and the work roll.
Therefore, there is a technological issue to enable opening and closing of the work rolls without making a scratch on any of the rolled strip and the work rolls. [0017]
Moreover, conventional technology also has a following problem. When a downstream-side rolling stand is set as a reference-speed-manipulation-end as shown in a case in which the downstream-side rolling stand is taken as a referential standard, an output for tension control between rolling stands becomes the speed of an upstream-side rolling stand, and an entry-side bridle roll speed is controlled by a successive controlling. Moreover, the entry-side bridle roll speed is also controlled by an entry-side tension control. [0018]
When the reduction of the upstream-side rolling stand is controlled to make the roll gap narrowed, entry-side tension decreases, and tension between the rolling stands also decreases. Accordingly, a tension control between the rolling stands makes the speed of the upstream-side rolling stand slow by an upstream-side-rolling-stand speed output. In a successive control, the
entry-side bridle roll speed is made slower by an entry-side-bridle-roll speed output. Furthermore, in an entry-side tension control, entry-side tension is reduced, so that the entry-side bridle roll speed is made slow by an entry-side-bridle-roll speed output. [0019]
Accordingly, a summation of a control output by the tension control between the rolling stands and a control output by the entry-side tension control is output to the entry-side bridle roll. As a result, a large amount of change in the speed becomes required, thereby making the control response slow. [0020]
According to the conventional technology as explained above, when a successive control is performed by setting the reference-speed-manipulation-end beforehand prior to starting of rolling, the amount of change in speed becomes so large that a control response becomes slow, if a change in tension originating from a roll-gap change of the rolling stand is caused. [0021]
The present invention has been made in view of the foregoing circumstance, and it is an object of the present invention to enable opening and closing of work rolls while suppressing any occurrence of slippage between a rolled strip and the work roll without making those scratched. Moreover, it is another object of the present invention to improve a strip thickness precision and a tension precision by minimizing a tension change and/or a strip thickness change originating from the delay of a speed response.
SUMMARY OF THE INVENTION
[0022]
In order to achieve at least either one of the foregoing objects, the present invention according to a first aspect provides a rolling mill comprising one or more than one mill, the mill including top and bottom work rolls which press and roll a rolled strip which is running from upper and down sides, a reduction control device which controls a roll gap between the top and bottom work rolls, load detecting means for detecting a load applied by the top and bottom work rolls to the rolled strip, rolled strip speed detecting means for detecting a speed of the rolled strip at an entry side of the mill and at a delivery side of the mill, tension detecting means for detecting tension of the rolled strip at the entry side of the mill and at the delivery side of the mill, electric-motor speed detecting means for detecting a speed of an electric motor that drives the top and bottom work roll of the mill, tension/speed reference computing means for calculating tension of the rolled strip at the entry side of the mill and at the delivery side of the mill or a speed reference to the electric motor, speed control means for controlling a speed of the electric motor based on preset data of a speed measured by the electric-motor speed detecting means and the speed reference, roll-position computing means which calculates a position of the work roll, and computing device of instruction for roll opening/closing during strip-running, which performs controlling of opening/closing the top and bottom work rolls relative to the rolled strip while the rolled strip is running, wherein the computing device of instruction for roll opening/closing during strip-running makes the rolled strip in an elastic deformation state by increasing or decreasing the load, keeps the load constant, and controls an operation of opening off the rolled strip the top and bottom work rolls that is kept closed or closing to the rolled strip the top and bottom work rolls that is kept opened, using the
reduction control device, without stopping the rolled strip from running, while at least one of the tension and the speed of the rolled strip is kept equal between at the entry side of the mill and at the delivery side of the mill. [0023]
Also, the present invention according to a second aspect provides A method of controlling a rolling mill comprising one or more than one mill, the mill including top and bottom work rolls which press and roll a rolled strip which is running from upper and down sides, and a reduction control device which controls a roll gap between the top and bottom work rolls, the method comprising a first step of a control device increasing or decreasing load applied from the top and bottom work rolls to the rolled strip without stopping the rolled strip from running, a second step of the control device keeping the load constant after the rolled strip becomes in an elastic deformation state, and a third step of the control device opening off the rolled strip the top and bottom work rolls that is kept closed or closing to the rolled strip the top and bottom work rolls that is kept opened, using the reduction control device, without stopping the rolled strip from running, while at least one of the tension and the speed of the rolled strip is kept equal between at the entry side of the mill and at the delivery side of the mill. [0024]
Also, the present invention according to a third aspect provides a rolling apparatus comprising an entry-side bridle roll which controls tension applied to a rolled strip at an entry side of a mill, speed control means for the entry-side bridle roll, a delivery-side bridle roll which controls tension applied to a rolled strip at an delivery side at a delivery side of the mill, speed control means for the entry-side bridle roll, a plurality of rolling stands, speed control means for
the plurality of rolling stands, a strip thickness detector which detects a strip thickness of the rolled strip, a tension detector which detects tension of the rolled strip, a plurality of control means for outputting a speed of the entry-side bridle roll, a speed of the delivery-side bridle roll, and a speed of the plurality of rolling stands to respective speed manipulation ends based on preset data of rolling acquired from a strip thickness of the rolled strip detected by the strip thickness detector and tension of the rolled strip detected by the tension detector, a reference-speed-manipulation-end determining means for determining a reference-speed-manipulation-end to which no adjustment amount in a speed control is given so that a speed adjustment amount at each speed manipulation end becomes minimum based on preset data of rolling including a strip thickness and tension, and a rolling condition including a control output including a strip thickness control and a tension control, and speed adjustment reference creating means for determining respective speed adjustment amounts for the entry-side bridle roll, the delivery-side bridle roll, and the plurality of rolling stands in accordance with the reference-speed-manipulation-end determined by reference-speed-manipulation-end determining means, and outputting the respective speed adjustment amount to each speed manipulation end. [0025]
Also, the present invention according to a fourth aspect provides A method of controlling a rolling apparatus, the rolling apparatus comprising an entry-side bridle roll which controls tension applied to a rolled strip at an entry side of a mill, speed control means for the entry-side bridle roll, a delivery-side bridle roll which controls tension applied to a rolled strip at an delivery side at a delivery side of the mill, speed control means for the entry-side bridle roll, speed control means for the delivery-side bridle roll, a plurality of rolling stands.
speed control means for the plurality of rolling stands, a strip thickness detector which detects a strip thickness of the rolled strip, a tension detector which detects tension of the.rolled strip; and a plurality of control means which output a speed of the entry-side bridle roll, a speed of the delivery-side bridle roll, and a speed of the plurality of rolling stands to respective speed manipulation ends based on preset data of rolling acquired from a strip thickness of the rolled strip detected by the strip thickness detector and tension of the rolled strip detected by the tension detector, the method comprising a step of determining a reference-speed-manipulation-end to which no adjustment amount in a speed control is given so that a speed adjustment amount at each speed manipulation end becomes minimum based on preset data of rolling including a strip thickness and tension, and a rolling condition including a control output including a strip thickness control and a tension control, and a step of determining respective speed adjustment amounts for the entry-side bridle roll, the delivery-side bridle roll, and the plurality of rolling stands in accordance with the reference-speed-manipulation-end determined by
reference-speed-manipulation-end determining means, and outputting the respective speed adjustment amount to each speed manipulation end. [00261
According to the present invention, it becomes possible to enable opening and closing of a work roll while suppressing any occurrence of slippage between a rolled strip and the work roll without making those scratched. [0027]
Moreover, it becomes possible to improve a strip thickness precision and a tension precision by minimizing a tension change and/or a strip thickness change originating from the delay of a speed response.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028]
FIG. 1 is a schematic diagram showing a single-stand rolling mill S with a simple example configuration of a system for roll opening/closing during strip-running according to an embodiment of the present invention;
FIG. 2A is a diagram showing a rolling-mill speed which is a speed of work rolls driven by an electric motor of a mill at the time of opening the work rolls from a rolled strip while the mill is in operation (while the rolled strip 1 is running);
FIG. 2B is a diagram showing rolling load to the rolled strip and bending force of the work roll's while the mill is in operation;
FIG. 2C is a diagram showing preset data of tension at the entry side of the mill and at the delivery side thereof while the mill is in operation;
FIG. 2D is a diagram showing preset data of a speed of the rolled strip at the entry side of the mill and at the delivery side thereof while the mill is in operation;
FIG. 3 is a diagram showing an example flow of a open operation of the work rolls from the rolled strip while the mill is in operation;
FIG. 4A is a diagram showing a rolling-mill speed which is a speed of the work rolls by a motor of the rolling mill at the time of closing top and bottom work rolls to the rolled strip while the mill is in operation (while the rolled strip is travelling);
FIG. 4B is a diagram showing rolling load to the rolled strip and bending force of the work rolls while the mill is in operation;
FIG. 4C is a diagram showing preset data of tension at the entry side of the
mill and at the delivery side thereof while the mill is in operation;
FIG. 4D is a diagram showing preset data of a speed of the rolled strip at the entry side of the mill and at the delivery side thereof;
FIG. 5 is a diagram showing an operational flow when the top and bottom work rolls are closed to the rolled strip while the mill is in operation (while the rolled strip is running);
FIG. 6 is a diagram showing a configuration of rolling apparatus and that of a control system thereof according to the embodiment of the present invention;
FIG. 7 is a diagram showing a reference example;
FIG. 8 is a diagram showing a configuration of a reference-speed-manipulation-end determining device installed in the rolling apparatus according to the embodiment of the present invention;
FIG. 9 is a diagram showing a configuration of a speed adjustment reference creating device installed in the rolling apparatus according to the embodiment of the present invention;
FIG. 10 is a diagram showing a time chart of a control operation according to the embodiment of the present invention;
FIG. 11 is a flowchart of a control operation according to the embodiment of the present invention;
FIG. 12 is a diagram showing a first structure of a rolling apparatus as a reference example, and that of a control system thereof;
FIG. 13 is a diagram showing a second structure of a rolling apparatus as a reference example, and that of a control system thereof;
FIG. 14 is a diagram showing a structure of a rolling apparatus with entry-side and delivery-side tension reels according to a modified example of the embodiment of the present invention and that of a control system thereof;
and
FIG. 15 is a diagram showing a structure of a rolling apparatus having an optimum speed setting device according to a modified example of the embodiment of the present invention and that of a control system thereof.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029]
An embodiment of the present invention will now be explained with reference to the accompanying drawings. Note that FIG. 1, etc., shows individual functions as a block diagram, when the whole (or a part of) device is configured by a computer, such function may be realized by a software. That is, a structural element named as a "device" has the same meaning as "means" and "unit". FIG. 1 is a schematic diagram showing a single-stand rolling mill S with a simple example configuration of a system for roll opening/closing during strip-running according to an embodiment of the present invention. [0030]
<>
The rolling mill S according to the embodiment of the present invention opens top and bottom work rolls Rsl, Rs2 off a rolled strip in accordance with a predetermined procedure during the rolling operation at the strip running speed equal to or slower than 60 mpm (meter/minute) when a welded point of the rolled strip 1 passes through the top and bottom work rolls Rsl, Rs2 which bear a rolling work, determines whether or not the rolled strip 1 becomes in an elastic deformation state from a plastic deformation state, and causes the top and bottom work rolls Rsl, Rs2 not to contact the rolled strip 1. Thereafter, during a low-speed operation that the speed of the rolled strip 1 is equal to or slower
than 60 mpm, the rolling mill S causes the top and bottom work rolls Rsl, Rs2 to contact the rolled strip 1 again, determines whether or not the rolled strip 1 becomes in a plastic deformation state from an elastic deformation state, and causes the rolled strip 1 to be in a rolled condition step by step in accordance with a predetermined procedure, thereby opening and closing the top and bottom work rolls Rsl, Rs2 during the rolling operation. [0031]
In this fashion, as it is determined whether the rolled strip 1 is in a plastic deformation state or in an elastic deformation state when the speed of the top and bottom work rolls Rsl, Rs2 and that of the rolled strip 1 are at a low speed equal to or slower than 60 mpm, the top and bottom work rolls Rsl, Rs2 are opened off the rolled strip 1 step by step in accordance with a preset procedure, and then the top and bottom work rolls Rsl, Rs2 are made to contact the rolled strip 1 again, the top and bottom work rolls Rsl, Rs2 can be opened off and closed to the rolled strip 1 without making a scratch on any of the rolled strip 1 and the top and bottom work rolls Rsl, Rs2. [0032]
Moreover, it is possible to prevent the top and bottom work rolls Rsl, Rs2 and the rolled strip 1 from slipping with each other, and to cause the rolled strip 1 to transition to the rolled condition more stably.
More specifically, as the acceleration/deceleration rate of a line, tension of the rolled strip 1, and rolling load are changed step by step so that the rolled strip 1 smoothly transitions to a low-speed state equal to or slower than 60 mpm, the rolled strip 1 can smoothly transition from a plastic deformation state to an elastic deformation state, and also can smoothly transition from an elastic deformation state to a plastic deformation state.
The rolled conditions of the rolled strip 1, such as elastic deformation and plastic deformation, can be detected from a variation in preset data of tension at the entry side of the mill 3 or at the delivery side thereof, or preset data of a speed ratio of the rolled strip 1 between the entry side of the mill 3 and the delivery side thereof. [0033]
Hereinafter, the rolling mill S will be explained in more detail.
<>
The rolling mill S comprises an entry-side speed control roll 2 which is provided at the entry side of the mill 3 that rolls the rolled strip 1, and which feeds the rolled strip 1 to the mill 3 while controlling the speed of the rolled strip I. Moreover, the rolling mill S comprises a tension reel 4 which is provided at the delivery side of the mill 3 and which rolls up the rolled strip 1 as a coil 5.
Note that the entry-side speed control roll 2 can be any mechanism which can control the running speed of the rolled strip 1, such as a mechanism like a pinch roll that holds the rolled strip 1 between rolls, a pay-off reel with a speed control function, or a winding reel with a speed control function. [00341
Provided at the entry side of the mill 3 are a mill entry-side tension detector 9 which detects tension of the rolled strip 1 at the entry side of the mill 3, and a mill entry-side speed detector 6 which detects the running speed of the rolled strip 1 at the entry side of the mill 3.
In addition, provided at the delivery side of the mill 3 are a mill delivery-side tension detector 10 which detects tension of the rolled strip 1 at the delivery side of the mill 3 and a mill delivery-side speed detector 7 which
detects the speed of the rolled strip 1 at the delivery side of the mill 3. [0035]
An example of each of mill entry-side and delivery-side speed detectors 6, 7 is a device which irradiates the rolled strip 1 with laser light in a slightly inclined direction and reads out a change in speed from a difference in wavelength between the incident light and the reflected light.
Examples of the mill entry-side and delivery-side tension detectors 9, 10 are devices which cause respective rolls 9r, lOr to contact the rolled strip 1, and read out tension of the rolled strip 1 from loads applied to the rolls 9r, lOr, respectively, from the rolled strip 1. It should be understood that the mill entry-side and delivery-side speed detectors 6, 7 and the mill entry-side and delivery-side tension detectors 9, 10 are not limited to the above-explained structures. [0036]
The mill 3 is provided with a top work roll position control device 51 and a bottom work roll position control device 52, which work independently from each other. The top work roll position control device 51 and the bottom work roll position control device 52 independently control the height position of the top work roll Rsl and that of the bottom work roll Rs2, respectively.
The top work roll position control device 51 and the bottom work roll position control device 52 are independently controlled by an individual control instruction from a roll-position reference computing device 61. [0037]
There is also provided a load detector 8 which detects load applied to an upper part of the bottom work roll Rs2 or a lower part of the top work roll Rsl, and the rolling load applied to the rolled strip 1 by the top and bottom work rolls
Rsl, Rs2 is measured through the load detector 8. [0038]
A tension/speed reference computing device 62 outputs a speed reference for an electric motor 20 to a speed control device 40 of the entry-side speed controlling roll 2 which feeds the rolled strip 1, and outputs a speed reference for an electric motor 21 of a speed control device 41 of the mill 3. Each of speed control devices 40, 41 detects a rotational speed of each electric motor 20, 21 through a speed detector 30, 3 1 of each of electric motors 20, 21, and controls each of electric motors 20, 21 to rotate at an instructed speed calculated by the tension/speed reference computing device 62. [0039]
A current reference computing device 63 calculates a current reference for a tension reel driving electric motor 22 for acquiring the desired tension from a target tension value of the tension reel 4 which applies tension to the rolled strip 1 at the delivery side,of the mill 3, a diameter of the coil 5 rolling up the rolled rolled strip 1, and a speed reference from the tension/speed reference computing device 62. A current control device 42 into which a current reference calculated by the current reference computing device 63 is input controls the tension reel driving electric motor 22 so that a current of the tension reel driving electric motor 22 becomes equal to a current reference calculated by the current reference computing device 63. [0040]
In a normal rolling condition, tension of the rolled strip 1 at the entry side of the mill 3 is controlled by increasing/decreasing the speed of the rolled strip 1 by the entry-side speed control roll 2, and the rolled strip 1 is rolled to a desired strip thickness by the mill 3, and then rolled up by the tension reel 5.
A computing device of instruction for roll opening/closing during strip-running 60 comprehensively controls the rolling mill S, and comprehensively controls the operation of opening the top and bottom work rolls Rsl, Rs2 off and closing the top and bottom work rolls Rsl, Rs2 to the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running) to be discussed later. [0041]
That is, the computing device of instruction for roll opening/closing during strip-running 60 outputs a roll closing instruction to the roll-position reference computing device 61 which controls the top and bottom work roll position control devices 51, 52. The computing device of instruction for roll opening/closing during strip-running 60 also outputs a speed reference of the rolled strip 1 for the speed control devices 40, 41 to the tension/speed reference computing device 62. The computing device of instruction for roll opening/closing during strip-running 60 further outputs a tension reference of the rolled strip 1 at the delivery side to the current reference computing device 63.
Each of the computing device of instruction for roll opening/closing during strip-running 60, the roll-position reference computing device 61, the tension/speed reference computing device 62, and the current reference computing device 63 are realized by, for example, a PLC (programmable logic controller) storing a control software program. Moreover, the speed control devices 40, 41, the current control device 42, and the top and bottom work roll position control devices 51, 52 are realized by, for example, a control software program, an electronic circuit, and the like in a PLC. [00421

Next, an explanation will be given of an operation of opening the work rolls Rs 1, Rs2 off the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running) with reference to FIGS. 2 and 3.
FIG. 2A is a diagram showing a rolling-mill speed which is a speed of the top and bottom work rolls Rsl, Rs2 by the electric motor 21 of the mill 3 at the time of opening the top and bottom work rolls Rsl, Rs2 from the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running). FIG. 2B is a diagram showing rolling load to the rolled strip 1 and a bending force of the top and bottom work rolls Rsl, Rs2 while the mill is in operation (while the rolled strip 1 is running). FIG. 2C is a diagram showing preset data of tension of the rolled strip 1 at the entry side of the mill 3 and at the delivery side thereof while the mill is in operation (while the rolled strip 1 is running). FIG. 2D is a diagram showing preset data of a speed of the rolled strip 1 at the entry side of the mill 3 and at the delivery side thereof while the mill is in operation (while the rolled strip 1 is running). FIG. 3 is a diagram showing an example flow of a open operation of the top and bottom work rolls Rsl, Rs2 from the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running). [0043]
In order to open the top and bottom work rolls Rsl, Rs2 while the mill is in operation (while the rolled strip 1 is running), first, in a step S101 in FIG. 3, the speed of the top and bottom work rolls Rs 1, Rs2 of the mill is reduced (see (1) in FIG. 2A) by the electric motor 21, and in a step S102 in FIG. 3, it is determined whether or not the mill speed is in a low-speed range (30 to 50 mpm).
When no mill speed is in the low-speed range (30 to 50 mpm) (step S102 in
FIG. 3: NO), the process returns to step S101 and the work rolls Rsl, Rs2 of the mill are decelerated.
On the other hand, when the mill speed comes into the low-speed range (30 to 50 mpm) (step S102 in FIG. 3: YES), in a step S103 in FIG. 3, the deceleration rate of the mill 3 is changed (see (2) in FIG. 2A), and the mill 3 is gradually decelerated and is made to be in an extremely low-speed condition (slower than 30 mpm). [0044]
In the embodiment, in order to prevent any over the operation from happening and keep the incidence of the off-gauging as minimum as possible, the mill 3 is decelerated to the extremely low speed, and if the speed thereof is less than 60 mpm, it is sufficiently slow. Moreover, the way to change the deceleration rate may be a single stage operation, or a multiple stage operation or no-stage operation depending on a speed and a time, and any speed reference which enables stable transition of the speed of the mill 3, the speed of the rolled strip 1 at the delivery side, and tension thereof to the extremely low-speed condition is appropriate.
When the mill speed is low, if it is attempted to maintain the strip thickness of the rolled strip 1 to be constant, load applied to the rolled strip 1 may increase, so that in a step S103b in FIG. 3, the bottom work roll position control device 52 is controlled in such a way that the load becomes constant or the load does not exceeds a predetermined load value in a low-speed condition (see (3) in FIG. 2B). [0045]
In a step S104 in FIG. 3, it is determined whether or not the mill speed (the speed of the mill 3) becomes in the extremely low-speed condition. When the
mill speed (the speed of the mill 3) does not become in the extremely low-speed condition (step S104 in FIG. 3: NO), the process returns to the steps S103a, S103b in FIG. 3.
If the mill speed (the speed of the mill 3) becomes in the extremely low-speed condition (step S104 in FIG. 3: YES), in a step S105 in FIG. 3, the mill speed (the speed of the mill 3) is controlled so as to be constant, and in a step S106a in FIG. 3, a load target value is changed or the bottom work roll position control device is so controlled as to move the bottom work roll Rs2 downwardly, thereby reducing rolling load applied to the rolled strip 1 (see (4) in FIG. 2B). At the same time, in a step S106b in FIG. 3, the bending forces on the top work roll Rsl and the bottom work roll Rs2 are also reduced (see (5a) in FIG. 2B). [0046]
In a step S106c in FIG. 3, a target tension value is controlled in such a way that tension at the entry side of the mill 3 and tension at the delivery side of the mill 3 become equal to each other (see (5b) in FIG. 2C).
Note that bending forces of the top work roll Rsl and the bottom work roll Rs2 are forces applied outwardly to both ends of the top work roll Rsl and the bottom work roll Rs2 in order to suppress any deflection of the top work roll Rs1 and the bottom work roll Rs2 (deflection that a center part of the roll deforms outwardly and both end parts deform inwardly because the rolled strip 1 is sandwiched between respective center parts). [00471
In a step S107 in FIG. 3, it is determined whether or not a large change in tension of the rolled strip 1 at the entry side of the mill 3 or at the delivery side thereof is detected (see (6a) in FIG. 2C), whether or not a difference in preset
data of speed between the entry side of the mill 3 and the delivery side thereof becomes in a predetermined range (less than 1 %) (or whether or not the speed ratio between the entry side of the mill 3 and the delivery side thereof becomes 1 or a proximate value to 1) (see (6b) in FIG. 2D), or whether or not rolling load to the rolled strip 1 becomes a lower limit (see (6c) in FIG. 2B). [0048]
In a step S107 in FIG. 3, if no large change in tension of the rolled strip 1 at the entry side of the mill 3 or at the delivery side thereof is detected, a difference in preset data of speed between the entry side of the mill 3 and the delivery side thereof is not in a predetermined range (less than 1 %) (or the speed ratio between the entry side of the mill 3 and delivery side thereof does not become a proximate value to 1), and the rolling load does not become a lower limit (step S107 in FIG. 3: NO), the process returns to the steps S106a, S106b, and S106c in FIG. 3. [0049]
On the other hand, in the step S107 in FIG. 3, if it is determined that a large cahnge in tension at the entry side or at the delivery side is detected, or if the difference in preset data of speed between the entry side of the mill 3 and the delivery side thereof becomes in a predetermined range (less than 1 %) (or when the speed ratio between the entry side of the mill 3 and the delivery side thereof becomes a proximate value to 1), or, if the rolling load becomes a lower limit (step S107 in FIG. 3: YES), it is determined that the rolled strip 1 transitions from plastic deformation to elastic deformation. Next, in a step S108a in FIG. 3, the bottom work roll position control device 52 is so controlled as to control the rolling load to the rolled strip 1 to be constant (see (7a) in FIG. 2B). Thereafter, in a step S108b in FIG. 3, the bending force of the top and bottom
work rolls Rsl, Rs2 are increased up to balanced force (a condition in which the bending force are counterbalanced with respective weights of the top and bottom work rolls Rsl, Rs2) (see (7b) in FIG. 2B) so that the top and bottom work rolls Rsl, Rs2 do not slip with any of intermediate rolls Rcl, Rc2 and backup rolls Rbl, Rb2. [0050]
Next, in a step S109 in FIG. 3, it is determined whether or not preset data of bending force of the top and bottom work rolls Rsl, Rs2 increases to a force equal to or larger than the balanced force and preset data of tension at the entry side of the mill 3 and preset data of tension at the delivery side thereof become equal to each other or the difference therebetween becomes within a predetermined range (see (8) in FIG. 2B).
In the step S109 in FIG. 3, if it is determined that the preset data of bending force of the top and bottom work rolls Rs 1, Rs2 does not increase to a force equal to or larger than the balanced force or the preset data of tension at the entry side of the mill 3 and the preset data of tension at the delivery side thereof is not equal to each other or the difference therebetween is not within a predetermined range (step S109 in FIG. 3: NO), the process returns to the steps S108a, S108b. [0051]
Conversely, if it is determined that the preset data of bending force of the work rolls Rsl, Rs2 increases to a force equal to or larger than the balanced force, and the preset data of tension at the entry side of the mill 3 and the preset data of tension at the delivery side thereof becomes equal to each other or the difference therebetween becomes within a predetermined range (step S109 in FIG. 3: YES), in a step SI 10a in FIG. 3, the bottom work roll position control
device 52 is controlled to move the bottom work roll Rs2 downwardly and to open it off the rolled strip 1 (see (9) in FIG. 2B).
At the same time, in a step S110b in FIG. 3, when rolling road decreases to equal to or less than a certain value, the top work roll position control device 51 is controlled to raise the position of the top work roll Rsl (see (9) in FIG. 2B). [0052]
Subsequently, in a step S111 in FIG. 3, it is determined whether or not the bottom work roll Rs2 reaches a position equal to or larger than a predetermined value X mm from a pass line position where the rolled strip 1 is conveyed. For example, when the strip thickness of the rolled strip 1 is 3 mm, the X mm is set to be 2 mm. X may be any value that the rolled strip 1 does not contact the bottom work roll Rs2.
When it is determined that the bottom work roll Rs2 does not reach a position equal to or larger than the predetermined value X mm from the pass line position where the rolled strip 1 is conveyed (step S111 in FIG. 3: NO), the process returns to the step S110a in FIG. 3. [0053]
Conversely, if it is determined in the step S111 in FIG. 3 that the bottom work roll Rs2 reaches a position equal to or larger than the predetermined value X mm from the pass line position where the rolled strip 1 is conveyed (step S111 in FIG. 3: YES), the operation is terminated (see (10) in FIG. 2B).
Moreover, in a step S112 in FIG. 3, it is determined whether or not the top work roll Rsl reaches a position equal to or larger than a predetermined value X mm from the pass line position where the rolled strip 1 is conveyed. Note that X may be any value at which the rolled strip 1 does not contact the top work roll Rs1.
[0054]
If it is determined that the top work roll Rsl does not reach a position equal to or larger than X mm from the pass line position (step S112 in FIG. 3: NO), the process returns to the step S110b in FIG. 3.
On the other hand, if it is determined that the top work roll Rs1 reaches a position equal to or larger than X mm from the pass line position (step S112 in FIG. 3: YES), the operation is terminated (see (10) in FIG. 2B).
The foregoing procedure is the operation flow of opening the top and bottom work rolls Rsl, Rs2 off the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running). [0055]
«Operation of Closing Upper and Lower Work Rolls Rsl, Rs2 to Rolled Strip 1 while Mill is in Operation»
Next, an explanation will be given of an operation of closing the top and bottom work rolls Rsl, Rs2 to the rolled strip 1 while the rolling mill S is running (while the rolled strip 1 is running) with reference to FIG. 5. [0056]
FIGS. 4A to 4D are diagrams showing an operational chart when the top and bottom work rolls Rsl and Rs2 are closed to the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running) in a low-speed condition that the speed of the rolled strip 1 is equal to or slower than 60 mpm. FIG. 4A is a diagram showing a rolling-mill speed which is a speed of the top and bottom work rolls Rsl, Rs2 by the electric motor 21 of the mill 3 at the time of closing the top and bottom work rolls Rsl, Rs2 to the rolled strip 1 while the mill 3 is running (while the rolled strip 1 is running). FIG. 4B is a diagram showing rolling load to the rolled strip 1 and bending force of the top and bottom work
rolls Rsl, Rs2 while the mill is in operation (while the rolled strip 1 is running). FIG. 4C is a diagram showing preset data of tension at the entry side of the mill 3 and at the delivery side thereof while the mill is in operation (while the rolled strip 1 is running). FIG. 4D is a diagram showing preset data of a speed of the rolled strip 1 at the entry side of the mill 3 and at the delivery side thereof while the mill is in operation (while the rolled strip 1 is running). FIG. 5 is a diagram showing an operational flow when the top and bottom work rolls Rsl, Rs2 are closed to the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running). [0057]
In order to close the top work roll Rsl and the bottom work roll Rs2 to the rolled strip 1 while the mill is in operation (while the rolled strip 1 is running), first, in a step S201 in FIG. 5, operation of the top and bottom work rolls Rsl, Rs2 of the rolling mill (mill 3) by the electric motor 21 is initiated while the rolled strip 1 shown in FIG. 1 is running at a speed equal to or slower than 60 mpm. When the speed of the mill (the rotational speed of the top and bottom work rolls Rsl, Rs2) is faster than the rolled strip 1 at a slow speed equal to or slower than 60 mpm, the mill 3 (the top and bottom work rolls Rsl, Rs2) is decelerated, and a speed reference for the electric motor 21 to the speed control device 41 is adjusted in such a way that the circumferential velocity of the top and bottom work rolls Rs 1, Rs2 of the mill 3 is kept equal to the speed of the rolled strip 1 (see (1) in FIG. 4A). [0058]
In a step S202 in FIG. 5, it is determined whether or not a speed difference between the mill 3 (the top and bottom work rolls Rsl, Rs2) and the rolled strip 1 becomes within a predetermined range.
When it is determined that the speed difference between the mill 3 (the top and bottom work rolls Rsl, Rs2) and the rolled strip 1 is zero or is not within a predetermined range (step S202 in FIG. 5: NO), the process returns to the step S201 in FIG. 5. [0059]
On the other hand, if it is determined that the speed difference between the mill 3 (the top and bottom work rolls Rsl, Rs2) and the rolled strip 1 becomes within a predetermined range (step S202 in FIG. 5: YES), in steps S203a, S203b in FIG. 5, the computing device of instruction for roll opening/closing during strip-running 60 shown in FIG. 1 outputs an roll closing instruction to the roll-position reference computing device 61, and the roll-position reference computing device 61 outputs a closing direction instruction to the top work roll position control device 51 and the bottom work roll position control device 52, thereby closing the rolled strip 1 with the top and bottom work rolls Rsl, Rs2 (see (2) in FIG. 4B). [0060]
In a step S204 in FIG. 5, the load detector 8 (see FIG. 1) detects rolling load to the rolled strip 1, and it is determined whether or not the rolling load becomes equal to or larger than a predetermined value.
When the rolling load does not become equal to or larger than the predetermined value (step S204 in FIG. 5: NO), the process returns to the steps S203a, S203b in FIG. 5.
Conversely, when the rolling load becomes equal to or larger than the predetermined value (step S204 in FIG. 5: YES), in a step S205 in FIG. 5, the roll-position reference computing device 61 (see FIG. 1) outputs a position reference to the bottom work roll position control device 52 so that the rolling
load becomes constant, thereby performing load constant control (see (3) in FIG.
4B).
[0061]
Subsequently, in a step S206 in FIG. 5, the bending force of the top and bottom work rolls Rsl, Rs2 is reduced from the balanced force (see (4) in FIG. 4B). In a step S207 in FIG. 5, it is determined whether or not reduction of the bending force of the top and bottom work rolls Rsl, Rs2 from the balanced force completes.
If it is determined in the step S207 in FIG. 5 that reduction of the bending force of the top and bottom work rolls Rsl, Rs2 from the balanced force is not completed (step S207 in FIG. 5: NO), the process returns to the step S206 in FIG. 5. [00621
On the other hand, if the reduction of the bending force of the top and bottom work rolls Rsl, Rs2 from the balanced force is completed (step S207 in FIG. 5: YES), in a step S208a in FIG. 5, the roll-position reference control device 61 outputs a closing instruction to the bottom work roll position control device 52 based on an instruction from the computing device of instruction for roll opening/closing during strip-running 60 (see FIG. 1), and the rolled strip 1 is closed with the bottom work roll Rs2 based on an instruction from the bottom work roll position control device 52 to increase load applied to the rolled strip 1 (see (5) in FIG. 4B). At the same time, in a step S208b in FIG. 5, the bending force of the top and bottom work rolls Rsl, Rs2 is increased together with the foregoing load in order to suppress any form change of the rolled strip 1 as minimum as possible (see (6) in FIG. 4B). Moreover, in a step S208c in FIG. 5. the computing device of instruction for roll opening/closing during
strip-running 60 changes a tension reference from the tension/speed reference computing device 62 to the speed control devices 40, 41 at the entry side of the mill 3 and a tension reference to the current reference computing device 63 at the delivery side of the mill 3 to a rolling schedule set value (see (7) in FIG. 4C). [0063]
At a stage when the rolling load to the rolled strip 1 is increased, the rolled strip 1 transitions from an elastic deformation state to a plastic deformation state. This state transition can be detected based on the fact that preset data of tension detected by the mill entry-side tension detector 9 or the mill delivery-side tension detector 10 at the entry side of the mill 3 shown in FIG. 1 or at the delivery side thereof decreases, or there appears a speed difference in preset data of strip speed of the rolled strip 1 between the mill entry-side speed detector 6 at the entry side of the mill 3 and the mill delivery-side speed detector 7 at the delivery side thereof (alternatively, the speed ratio of the rolled strip 1 between the entry side and the delivery side becomes not 1). [0064]
In a step S209 in FIG. 5, it is determined whether or not the rolling load reaches a target load, and whether or not tension change by the computing device of instruction for roll opening/closing during strip-running 60 is completed.
When the rolling load to the rolled strip 1 does not reach the target load or when tension change by the computing device of instruction for roll opening/closing during strip-running 60 does not complete (step S209 in FIG. 5: NO), the process returns to the steps S208a, S208b, and S208c in FIG. 5.
Conversely, if the rolling load reaches the target load and tension change by
the computing device of instruction for roll opening/closing during strip-running 60 completes (step S209 in FIG. 5: YES), in a step S210 in FIG. 5, acceleration of the mill 3 is started from a condition in which the acceleration rate of the mill 3 is decreased (see (8) in FIG. 4A). [0065]
Next, in a step S211 in FIG. 5, it is determined whether or not the speed of the mill 3 (the top and bottom work rolls Rsl, Rs2) becomes equal to or faster than a certain speed.
If the speed of the mills 3 (the top and bottom work rolls Rs 1, Rs2) does not become equal to or faster than the certain speed (step S211 in FIG. 5: NO), the process returns to the step S210 in FIG. 5.
On the other hand, if the speed of the mill 3 becomes equal to or faster than the certain speed (step S211 in FIG. 5: YES), in a step S212 in FIG. 5, the mill is further accelerated with the acceleration rate being returned to a normal acceleration rate (see (9) in FIG. 4A), and the rolling condition is shifted to a normal rolling condition (see (10) in FIG. 4A). [0066]
Regarding the way to change the acceleration rate, the acceleration rate may be changed through a single stage of changing the acceleration rate once, or through multiple stages step by step based on the speed of the mill 3 (the rotational speed of the top and bottom work rolls Rsl, Rs2), a time, and the like, or may be changed successively without any stage.
The foregoing procedure is the operation flow shown in FIG. 5 of closing the top and bottom work rolls Rsl, Rs2 to the rolled strip 1 while the rolling mill S is running (while the rolled strip 1 is running). [0067]
<>
According to the rolling mill S, as the rolled condition of the rolled strip 1 is made to transition step by step during a low-speed operation, it is possible to open/close the top and bottom work rolls Rsl, Rs2. without making a scratch on the top and bottom work rolls Rsl, Rs2 and the rolled strip 1 and without causing any slippage therebetween.
Therefore, it is possible to open/close the top and bottom work rolls Rsl, Rs2 while the rolling is continued. [0082]
Therefore, it becomes possible to allow a welded point of the rolled strip 1 to pass through the work rolls with the top and bottom work rolls Rsl, Rs2 being
opened without changing the top and bottom work rolls Rsl, Rs2 during rolling or without stopping the mill 3. This improves the degree of freedom for changing of the strip thickness and the strip width of the rolled strip I.
Thus, the degree of freedom for changing of the operation mode and changing of the rolling schedule of the rolled strip 1 with a welded point can be improved. [0083]
Moreover, in continuous rolling mills, it becomes possible to change the number of rolling stands (the number of rolling mills 3) while rolling is continued.
Furthermore, because no roll mark is produced on the rolled strip 1, the yield is improved, and because it is possible to continue rolling without stopping the mill 3, the operation efficiency is dramatically improved. [0084]
The present invention can be widely applied to, for example, changing of top and bottom work rolls while a mill is in operation (while the rolled strip 1 is running), changing of the number of stands while the mill is in operation, and changing of operation scheme while the mill is in operation in cold rolling mills. [0089]
Another embodiment of the present invention will be explained. In order to facilitate understanding for this embodiment, an explanation will be given with reference to a reference example.
In rolling apparatus with a Tandem Cold Mill, in order to perform strip thickness control and tension control, it is necessary to appropriately control the speed of each stand. [0090]
FIG. 12 shows an example (reference example) of a conventional rolling apparatus. In FIG. 12, the conventional rolling apparatus is exemplified as a Tandem Cold Mill for a rolling stand 1002. The Tandem Cold Mill comprises a first rolling stand 1001, the second rolling stand 1002, an entry-side bridle roll 1003 which is mill entry-side equipment, and a delivery-side bridle roll 1004 which is mill delivery-side equipment. [0091]
The Tandem Cold Mill also comprises a first-rolling-stand reduction control device 1021 and a second-rolling-stand reduction control device 1022. The first-rolling-stand reduction control device 1021 and the second-rolling-stand reduction control device 1022 control the roll gaps of respective rolling stands to control rolling pressure applied to a rolled strip 1005. The Tandem Cold Mill further comprises a first-rolling-stand speed control device 1023, a second-rolling-stand speed control device 1024, and an entry-side bridle roll speed control device 1025 which control the speed of the rolled strip 1 to adjust tension applied thereto. [0092]
Rolling is performed in order to acquire a predetermined strip thickness of the rolled strip 1005 by adjusting rolling pressure and tension applied to the rolled strip 1005. Hence, a first-rolling-stand delivery-side thickness gauge 1011, and a second-rolling-stand delivery-side thickness gauge 1012 are provided to measure the strip thickness of the rolled strip 1005, and an entry-side tension meter 1013, an inter-stand tension meter 1014, and a delivery-side tension meter 1015 are provided to measure tension at each interval. [0093]
A signal from the first-rolling-stand delivery-side thickness gauge 1011 is input into a strip thickness control device 1031 which controls a strip thickness at the delivery side of the first rolling stand 1001. An output by the strip thickness control device 1031 is input into the first-rolling-stand reduction control device 1021, and the first-rolling-stand reduction control device 1021 controls the rolling pressure of the first rolling stand 1001. [0094]
An output by the inter-stand tension meter 1014 is input into an inter-stand tension controller 1032. The inter-stand tension controller 1032 controls tension between rolling stands through the first-rolling-stand speed control device 1023 which controls the speed of the first rolling stand 1001. [0095]
Likewise, an output by the entry-side tension meter 1013 is input into an entry-side tension controller 1033. The entry-side tension controller 1033 controls tension at the entry side of the first rolling stand 1001 through the entry-side bridle roll speed control device 1025, which controls the speed of the entry-side bridle roll 1003. [0096]
An output by the delivery-side tension meter 1015 is input into a delivery-side tension controller 1034. The delivery-side tension controller 1034 controls tension at the delivery side of the second rolling stand 1002 through a delivery-side bridle roll speed control device 1026, which controls the speed of the delivery-side bridle roll 1004. [0097]
Looking to tension at the entry side of the first rolling stand 1001, in order to make the tension constant, it is necessary that the entry-side speed of the first
rolling stand 1001 is equal to the speed of the entry-side bridle roll 1003. Now, it is assumed that the;inter-stand tension control device 1032 operates so as to change the speed of the first rolling stand 1001. In this case, a control output changes the speed of the first rolling stand 1001, which necessarily brings about a tension change at the entry side. [0098]
Accordingly, it is necessary to have a function of supplying a control output to the entry-side bridle roll 1003 too, and of keeping constant the ratio between the speed of the entry-side bridle roll 1003 and the speed of the first rolling stand 1001 so as to prevent a tension change from occurring. This function is realized by a successive function 1040 shown in FIG. 12. [0099]
As explained above, in the conventional Tandem Cold Mill, when the speed of a rolling stand subjected to a strip thickness control and a tension control is manipulated, the mass-flow balance of the rolled strip 1005 is maintained using the successive function 1040 to prevent a strip thickness and a tension change from affecting another rolling stand. The successive function 1040 does not manipulate the speed with reference to a rolling stand, but adjusts the speed of another rolling stand in one direction. [0100]
For example, in the conventional Tandem Cold Mill shown in FIG. 12, when a speed reference is output to the first rolling stand 1001 without changing the speed with reference to the second rolling stand 1002, the speed of the entry-side bridle roll 1003 is manipulated as the successive function. [0101]
Moreover, as shown in FIG. 13, it is possible to control the speed of the
second rolling stand 1002 by the second-rolling-stand speed control device 1024 to which a control output by the inter-stand tension controller 1032 is given without changing the speed of the first rolling stand 1001 with reference to the first rolling stand 1001. In this case, a successive function 1041 is operated for the delivery-side bridle roll 1004. [0102]
Conventionally, a reference-speed-manipulation-end is determined before rolling is started, and a strip thickness control and a tension control matching the reference-speed-manipulation-end are selected and executed. For example, when the first rolling stand 1001 is taken as a reference standard, the control system shown in FIG. 13 is adopted, and when the second rolling stand 1002 is taken as a reference standard, the control system shown in FIG. 12 is adopted. [0103]
As is clear from a case in which the second rolling stand 1002 is taken as a reference standard shown in FIG. 7, when the second rolling stand 1002 is taken as a reference-speed-manipulation-end, an output by the inter-stand tension controller 1032 becomes an reference 1051 for the speed of the first rolling stand 1001, and an reference 1052 for the speed of the entry-side bridle roll 1003 is manipulated using the successive function 1040. Moreover, an entry-side tension controller 1033 manipulates an reference 1050 for the speed of the entry-side bridle roll 1003. [0104]
If reduction on the first rolling stand 1001 is manipulated to make the roll gap closed, tension at the entry side decreases, and tension between rolling stands also decreases. Accordingly, the inter-stand tension controller 1032 decreases the speed of the first rolling stand by the first-rolling-stand speed
reference 1051, and in the successive control 1040, the speed of the entry-side bridle roll 1003 is decreased by the entry-side bridle roll speed reference 1052. Furthermore, because the tension at the entry side decreases, the entry-side tension controller 1033 reduces the speed of the entry-side bridle roll 1003 by the entry-side bridle roll speed reference 1050. [0105]
An embodiment of the present invention will now be explained with reference to the accompanying drawings. The same structural element will be denoted by the same reference numeral, and the duplicated explanation thereof will be omitted. FIG. 6 shows a rolling system according to the embodiment of the present invention. In order to facilitate understanding for the present invention, the embodiment of the present invention will be explained with reference to a Tandem Cold Mill system which is an example having two rolling stands that is the simplest structure. [0106]
The Tandem Cold Mill system of the embodiment comprises the first rolling stand 1001, the second rolling stand 1002, the entry-side bridle roll 1003 which is a mill entry-side equipment, and the delivery-side bridle roll 1004 which is a mill delivery-side equipment. Moreover, the Tandem Cold Mill system of the embodiment also comprises the first-rolling-stand reduction control device 1021, and the second-rolling-stand reduction control device 1022. The first-rolling-stand reduction control device 1021 and the second-rolling-stand reduction control device 1022 control roll gaps of respective rolling stands to adjust rolling pressure applied to the rolled strip 1005. [0107]
The Tandem Cold Mill system of the embodiment further comprises the
first-rolling-stand delivery-side thickness gauge 1011 and the second-rolling-stand delivery-side thickness gauge 1012 which measure the strip thickness of the rolled strip 1005, and the entry-side tension meter 1013, the inter-stand tension meter 1014, and the delivery-side tension meter 1015 which measure tension at each interval. [0108]
The Tandem Cold Mill system of the embodiment further comprises the first-rolling-stand speed control device 1023 which controls the speed of the first rolling stand 1001, the second-rolling-stand speed control device 1024 which controls the speed of the second rolling stand 1002, the entry-side bridle roll speed control device 1025 which controls the speed of the entry-side bridle roll 1003, and the delivery-side bridle roll speed control device 1026 which controls the speed of the delivery-side bridle roll 1004. [0109]
The first-rolling-stand speed control device 1023, the second-rolling-stand speed control device 1024, the entry-side bridle roll speed control device 1025, and the delivery-side bridle roll speed control device 1026 control the speed of the first rolling stand 1001, the speed of the second rolling stand 1002, the speed of the entry-side bridle roll 1003, and the speed of the delivery-side bridle roll 1004, respectively, thereby controlling the speed of the rolled strip 1005 and thus adjusting tension thereof. [0110]
Still further, the rolling system of the embodiment comprises a reference-speed-manipulation-end determining device 1045 which sets a reference-speed-manipulation-end that is a referential standard for speed adjustment based on a control output and preset data of rolling, and a speed-
adjustment reference creating device 1046 which creases speed adjustment amounts to respective reference-speed-manipulation-end that are the first-rolling-stand speed control device 1023, the second-rolling-stand speed control device 1024, the entry-side bridle roll speed control device 1025, and the delivery-side bridle roll speed control device 1026. The speed adjustment reference creating device 1046 outputs the created speed adjustment amount thereto. [0111]
A signal from the first-rolling-stand delivery-side thickness gauge 1011 is input into the strip thickness control device 1031 which controls the strip thickness at the delivery side of the first rolling stand 1001. An output by the strip thickness control device 1031 is input into the first-rolling-stand reduction control device 1021. The first-rolling-stand reduction control device 1021 controls rolling pressure of the first rolling stand 1001. [0112]
A value of tension between the rolling stands measured by the inter-stand tension meter 1014 is input into the speed adjustment reference creating device 1046 through the inter-stand tension controller 1032. A value of tension at the entry side of the first rolling stand 1001 measured by the entry-side tension meter 1013 is input into the speed adjustment reference creating device 1046 through the entry-side tension controller 1033. Furthermore, a value of tension at the delivery side of the second rolling stand 1002 measured by the delivery-side tension meter 1015 is input into the speed adjustment reference creating device 1046 through the delivery-side tension controller 1034. [0113]
In the rolling system of the embodiment, the
reference-speed-manipulation-end determining device 1045 sets a reference-speed-manipulation-end for which no adjustment is made, based on rolling preset data including a strip thickness and tension, and a rolling condition including a control output such as a strip thickness control and a tension control, in such a way that a speed adjustment amount at each control output end (each speed manipulation end) becomes minimum. The reference-speed-manipulation-end determining device 1045 outputs the number of a reference-speed-manipulation-end based on the control output and the rolling preset data to the speed adjustment reference creating device 1046. [0114]
The speed adjustment reference creating device 1046 creates respective speed adjustment amounts for the entry-side bridle roll 1003, the delivery-side bridle roll 1004, and the plurality of rolling stands in accordance with a reference-speed-manipulation-end determined by the reference-speed-manipulation-end determining device 1045. The speed adjustment reference creating device 1046 outputs speed adjustment amounts to respective speed manipulation ends that are the first-rolling-stand speed control device 1023, the second-rolling-stand speed control device 1024, the entry-side bridle roll speed control device 1025, and the delivery-side bridle roll speed control device 1026. [0115]
In order to overcome the problem of the conventional control technique, as shown in FIG. 7, when tension at the entry side and tension between rolling stands decrease with the roll gap of the first rolling stand 1001 being made narrowed, the reference standard is changed to the first rolling stand 1001. As the reference standard is changed to the first rolling stand 1001, an output 1053
by the inter-stand tension controller 1032 is used to control the speed of the second rolling stand 1002, and an output by the inter-stand tension controller 1032 by what corresponds to a successive control and an output by the entry-side tension controller 1033 are added together. This summation becomes an amount of change in the speed of the entry-side bridle roll 1003, thereby preventing any delay of a control response. [0116]
In the rolling apparatus of the embodiment of the present invention shown in FIG. 6, the reference-speed-manipulation-end determining device 1045 selects a reference-speed-manipulation-end in such a way that a speed adjustment amount output to each rolling stand becomes minimum based on preset data of rolling and control outputs, such as a tension control and a strip thickness control. The speed-adjustment-reference creating device 1046 sets a speed reference to each rolling stand (including the entry-side and delivery-side bridle rolls) in accordance with the reference rolling stand, and output such speed reference. [0117]
As controls which manipulate individual rolling stands of the rolling mill, the entry-side tension controller 1033, the inter-stand tension controller 1032, and the delivery-side tension controller 1034 are considered now. The following explanation will be given with reference to a case in which each tension-control output is output with the second rolling stand 1002 being taken as a reference standard. [0118]
FIG. 8 shows a general outline of the reference-speed-manipulation-end determining device. A level for the second rolling stand 1002 to be reasonably
taken as a reference standard is acquired through a fuzzy inference based on tension at the entry side, tension between the rolling stands, and tension at the delivery side. Setting values of respective tensions are subtracted from entry-side tension which is an output by the entry-side tension meter 1013, tension between the rolling stands which is an output by the inter-stand tension meter 1014, and delivery-side tension which is an output by the delivery-side tension meter 1015, respectively, to acquire an entry-side tension deviation, an inter-stand tension deviation, and a delivery-side tension deviation, respectively. Thereafter, based on such results, a certainty factor computing device 1451 acquires a certainty factor to each tension using a membership function shown in FIG. 8. [0119]
The certainty factor becomes as follow:
EM: entry-side tension is smaller than a setting value;
EP: entry-side tension is larger than a setting value;
SM: tension between rolling stands is smaller than a setting value;
SP: tension between rolling stands is larger than a setting value;
DM: delivery-side tension is smaller than a setting value; and
DP: delivery-side tension is larger than a setting value. [0120]
Based on each certainty factor acquired by the certainty factor computing device 1451, in an inferring device 1452, an inference executing device 1454 draw an inference in accordance with inference rules set in an inference rule base 1453 beforehand. The inference rules are set as follow so that a speed adjustment amount to each speed control device becomes minimum:
IF (EM AND SP) THEN second rolling stand is to be taken as a reference
standard (i)
IF (EM AND SM AND DP) THEN first rolling stand is to be taken as a reference standard (i+1)
IF (EP AND SM) THEN second rolling stand is to be taken as a reference standard (i+2) [0121]
Note that AND takes a minimum value in accordance with a predefined rule in the fuzzy inference. Inference is executed by the number of rules set beforehand using those inference rules, and the level (i) for the first rolling stand to be reasonably taken as a reference standard, the level (i) for the second rolling stand to be reasonably taken as a reference standard which are the conclusion parts of individual inference rules, and the maximum values thereof are acquired, thereby acquiring the level how much the first rolling stand is taken as a reference standard and the level how much the second rolling stand is taken as a reference standard. [0122]
A determination device 1455 compares a level for the first rolling stand 1001 to be reasonably taken as a standard with the level for the second rolling stand 1002 to be reasonably taken as a reference standard, and sets a reference-speed-manipulation-end number. Needless to say, if the level for the first rolling stand to be reasonably taken as a reference standard is larger than the level for the second rolling stand to be reasonably taken as a reference standard, the reference-speed-manipulation-end number becomes 1 (first rolling stand 1001). [0123]
FIG. 9 shows a general outline of the speed-adjustment-reference creating
device 1046. An output by the inter-stand tension controller 1032 is output to either the first rolling stand 1001 or the second rolling stand 1002 in accordance with the reference-speed-manipulation-end number acquired by the reference-speed-manipulation-end determining device 1045. Together with this operation, a gain GISTD, and a gain G2STD are set in accordance with whether the output by the inter-stand tension controller 1032 is output to the first rolling stand 1001 or the second rolling stand 1002. [0124]
If the reference-speed-manipulation-end number = 1, the first rolling stand 1001 is taken as a reference standard and a control output by the inter-stand tension controller 1032 is output to control the speed of the second rolling stand 1002. Because the output by the inter-stand tension controller 1032 is calculated with reference to the second rolling stand 1002, it is necessary to invert a code, and GISTD = 0, and G2STD = -1 in this case. Likewise, when the first rolling stand 1001 is taken as a reference standard, GISTD = 1, and G2STD = 0 in this case. [0125]
When the gains GISTD and G2STD are set, through a control block shown in FIG. 9, a speed adjustment amount is output to each speed control device with control outputs of an entry-side tension control, an inter-stand tension control, and a delivery-side tension control being as an entry-side bridle roll speed adjustment reference, a first-rolling-stand speed adjustment reference, a second-rolling-stand speed adjustment reference, and a delivery-side bridle roll speed adjustment reference, respectively. [0126]
The inferring device 1452 determines which of the first rolling stand 1001
and the second rolling stand 1002 is taken as a reference standard based on which is larger between the level for the first rolling stand to be reasonably taken as a reference standard and the level for the second rolling stand to be reasonably taken as a reference standard. In addition, which of the first rolling stand 1001 or the second rolling stand 1002 is taken as a reference standard can be determined based on whether or not a weighted gain > 1.0 from (the level for the first rolling stand 1001 to be reasonably taken as a reference standard) > weighted gain x (the level for the second rolling stand to be reasonably taken as a reference standard) with the second-rolling-stand standard given priority. [0127]
FIG. 10 is a diagram showing a control operation according to the embodiment of the present invention relative to a temporal change in the condition of the rolling apparatus. FIG. 10 shows an entry-side tension reference, an inter-stand tension reference, a delivery-side tension reference, and a reference-speed-manipulation-end number in each condition and a speed reference in a condition A of the rolling apparatus in a case in which the condition of the rolling apparatus changes from the condition A to a condition B. [0128]
In the condition A of the rolling apparatus, tension at the entry side is large, tension between the rolling stands is also large, and there is no deviation in tension at the delivery side. In the condition A, an entry-side tension control increases the speed of the entry-side bridle roll. A manipulation is made in such a way that an inter-stand tension control increases the speed of the first rolling stand 1001 with reference to the second rolling stand 1002 or decreases the speed of the second rolling stand 1002 with reference to the first rolling stand 1001.
[0129]
Accordingly, when the second rolling stand 1002 is taken as a reference standard, acceleration (by what corresponds to successive control to the first rolling stand) is performed by acceleration + inter-stand tension control as entry-side bridle roll speed = entry-side tension control, so that a manipulation amount of the entry-side bridle roll 1003 becomes large. In contrast, when the first rolling stand 1001 is taken as a reference standard, only acceleration by entry-side bridle roll speed = entry-side tension control is performed, so that the manipulation amount of the entry-side bridle roll 1003 becomes small. [0130]
In the condition B of the rolling apparatus, tension at the entry side is small, but tension between the rolling stands is large, and there is no deviation in tension at the delivery side. In the condition B, an entry-side tension control decreases the speed of the entry-side bridle roll. A manipulation is made in such a way that an inter-stand tension control increases the speed of the first rolling stand 1001 with reference to the second rolling stand or decreases the speed of the second rolling stand with reference to the first rolling stand. [0131]
If the first rolling stand 1001 is taken as a reference standard, it becomes necessary to decelerate the entry-side bridle roll 1003 and to decelerate the second rolling stand 1002. If the second rolling stand 1002 is taken as a reference standard, to be considered and at least partially cancelled out with each other are deceleration of the entry-side bridle roll 1003 by an entry-side tension control overlaps acceleration (by what corresponds to successive control for the speed change of the first rolling stand 1001) of the entry-side bridle roll 1003 by an inter-stand tension control. As a result, the amount of change in
speed of the entry-side bridle roll 1003 becomes small. [0132]
FIG. 11 shows a control operation for the rolling apparatus according to the embodiment of the present invention. First, it is checked whether or not the rolling apparatus are in rolling (step S1001). When the rolling apparatus is not in rolling, it is checked again whether or not the rolling apparatus is in rolling after a waiting time has elapsed (step S1002, and step S1001). When the rolling apparatus is in rolling operation, preset data of tension at the entry side, preset data of tension between the rolling stands, and preset data of tension at the delivery side are acquired from the entry-side tension meter 1013, the inter-stand tension meter 1014, and the deliver-side tension meter 1015, respectively (step S1003). A reference-speed-manipulation-end is determined based on those pieces of preset data of tension, a control output like a deviation in each tension, and preset data of rolling (step S1004). [0133]
Respective control outputs by the entry-side tension controller 1033, the inter-stand tension controller 1032, and the delivery-side tension controller 1034 are calculated (step S1005). Based on respective control outputs by the entry-side tension controller 1033, the inter-stand tension controller 1032, and the delivery-side tension controller 1034, and in consideration of ones by what corresponds to successive control in accordance with the reference-speed-mani'pulation-end together with those control outputs, respective speed references to the entry-side bridle roll 1003, the first rolling stand 1001, the second rolling stand 1002, and the delivery-side bridle roll 1004 are created (step S1006). Respective speed references are output to the entry-side bridle roll 1003, the first rolling stand 1001, the second rolling stand
1002, and the delivery-side bridle roll 1004 (step S1007). [0134]
Through the foregoing operation, based on rolling conditions, such as tension at the entry side, tension between the rolling stands, and tension at the delivery side, during rolling, a reference-speed-manipulation-end having a speed not changed is set, and control outputs in accordance with the reference-speed-manipulation-end are output to respective speed control devices of the entry-side bridle roll 1003, the first rolling stand 1001, the second rolling stand 1002, and the delivery-side bridle roll 1004. [0135]
The embodiment of the present invention can be applied to not only a two-rolling-stand Tandem Cold Mill, but also a Tandem Cold Mill with an any structure. Moreover, the embodiment of the present invention can be applied to, as shown in FIG. 14, a rolling mill that the entry-side bridle roll and the speed control device are an entry-side tension reel 1055 and a speed/torque control device 1057, or the delivery-side bridle roll and the speed control device thereof are a delivery-side tension reel 1056 and a speed/torque control device 1058. [0136]
According to the embodiment of the present invention, a reference-speed-manipulation-end is determined through the fuzzy inference based on rules set beforehand in such a way that a speed adjustment amount to each speed control device becomes minimum. However, a speed adjustment amount to each rolling stand may be calculated based on inference from a speed
- adjustment-amount output from each control device with a
reference-speed-manipulation-end being changed, and a
reference-speed-manipulation-end may be determined in accordance with evaluation criteria set beforehand so that a speed adjustment amount becomes an appropriate amount. FIG. 15 shows a configuration of a control system in this case. [0137]
Regarding how to acquire the evaluation criteria set beforehand, an absolute value of a speed adjustment amount to each rolling stand may be acquired, the maximum value thereof may be acquired, and a reference-speed-manipulation-end having minimum such maximum value may be selected, or a root-mean-square average of a speed adjustment amount to each rolling stand may be acquired, and a reference-speed-manipulation-end that such acquired value becomes minimum may be selected.

What is claimed is:
1. A rolling mill comprising
one or more than one mill, the mill including top and bottom work rolls which press and roll a rolled strip which is running from upper and down sides,
a reduction control device which controls a roll gap between the top and bottom work rolls,
load detecting means for detecting a load applied by the top and bottom work rolls to the rolled strip;
rolled strip speed detecting means for detecting a speed of the rolled strip at an entry side of the mill and at a delivery side of the mill;
tension detecting means for detecting tension of the rolled strip at the entry side of the mill and at the delivery side of the mill;
electric-motor speed detecting means for detecting a speed of an electric motor that drives the top and bottom work roll of the mill;
tension/speed reference computing means for calculating tension of the rolled strip at the entry side of the mill and at the delivery side of the mill or a speed reference to the electric motor;
speed control means for controling a speed of the electric motor based on preset data of a speed measured by the electric-motor speed detecting means and the speed reference;
roll-position computing means which calculates a position of the work roll; and
computing device of instruction for roll opening/closing during strip-running, which performs controlling of opening/closing the top and bottom work rolls relative to the rolled strip while the rolled strip is running,
wherein the computing device of instruction for roll opening/closing during strip-running makes the rolled strip in an elastic deformation state by increasing or decreasing the load, keeps the load constant, and controls an operation of opening off the rolled strip the top and bottom work rolls that is kept closed or closing to the rolled strip the top and bottom work rolls that is kept opened, using the reduction control device, without stopping the rolled strip from running, while at least one of the tension and the speed of the rolled strip is kept equal between at the entry side of the mill and at the delivery side of the mill.
2. The rolling mill according to claim 1, wherein the computing device of
instruction for roll opening/closing during strip-running adjusts bending forces
of the top and bottom work rolls when increasing/decreasing the load and when
the top and bottom work rolls is opened or closed.
3. The rolling mill according to claim 1, wherein the computing device of instruction for roll opening/closing during strip-running performs controlling the operation so as to open/close the top and bottom work rolls with the rolled strip running at a speed slower than 30 meter/minute.
4. The rolling mill according to claim 1, wherein the computing device of instruction for roll opening/closing during strip-running includes speed ratio/rolling determination means for acquiring a speed ratio between the entry side of the mill and the delivery side of the mill from speeds of the rolled strip at the entry side of the mill and at the delivery side detected by the rolled strip speed detecting means, and determining whether the rolled strip is in a plastic deformation state or in an elastic deformation state.
5. The rolling mill according to claim 1, wherein the computing device of instruction for roll opening/closing during strip-running includes tension/rolling determination means for detecting a transition of the rolled strip from a plastic deformation state to an elastic deformation state or from an elastic deformation state to a plastic deformation state based on changes in the tension of the rolled strip at the entry side of the mill and at the delivery side of the mill detected by the tension detecting means.
6. A method of controlling a rolling mill comprising one or more than one mill, the mill including top and bottom work rolls which press and roll a rolled strip which is running from upper and down sides, and a reduction control device which controls a roll gap between the top and bottom work rolls,
the method comprising,
a first step of a control device increasing or decreasing load applied from the top and bottom work rolls to the rolled strip without stopping the rolled strip from running,
a second step of the control device keeping the load constant after the rolled strip becomes in an elastic deformation state, and
a third step of the control device opening off the rolled strip the top and bottom work rolls that is kept closed or closing to the rolled strip the top and bottom work rolls that is kept opened, using the reduction control device, without stopping the rolled strip from running, while at least one of the tension and the speed of the rolled strip is kept equal between at the entry side of the mill and at the delivery side of the mill.
7. The rolling-mill control device according to claim 6, further comprising a fourth step of adjusting a bending force of the top and bottom work rolls when the load is being increased/decreased and when the top and bottom work rolls are being opened/closed.
8. The rolling-mill control device according to claim 6, wherein in the first step, the load is being increased or decreased without stopping the rolled strip from running while a speed of the rolled strip is slower than 30 meter/minute.
9. The rolling-mill control method according to claim 6, further comprising a fifth step of detecting, speeds of the rolled strip at the entry side of the mill and at the delivery side of the mill, of calculating a speed ratio of the rolled strip between the entry side of the mill and the delivery side of the mill, and of determining whether the rolled strip is in a plastic deformation state or in an elastic deformation state.
10. The rolling-mill control method according to claim 6, further comprising a
sixth step of detecting tensions of the rolled strip at the entry side of the mill
and at the delivery side of the mill, and of detecting changes in the tension of
the rolled strip at the entry side of the mill and at the delivery side of the mill,
thereby detecting a transition of a state of the rolled strip from a plastic
deformation state to an elastic deformation state or from an elastic deformation
state to a plastic deformation state
11. A rolling aparatus comprising:
an entry-side bridle roll which controls tension applied to a rolled strip at
an entry side of a mill,
speed control means for the entry-side bridle roll,
a delivery-side bridle roll which controls tension applied to a rolled strip at an delivery side at a delivery side of the mill,
speed control means for the entry-side bridle roll,
a plurality of rolling stands;
speed control means for the plurality of rolling stands;
a strip thickness detector which detects a strip thickness of the rolled strip;
a tension detector which detects tension of the rolled strip;
a plurality of control means for outputting a speed of the entry-side bridle roll, a speed of the delivery-side bridle roll, and a speed of the plurality of rolling stands to respective speed manipulation ends based on preset data of rolling acquired from a strip thickness of the rolled strip detected by the strip thickness detector and tension of the rolled strip detected by the tension detector;
a reference-speed-manipulation-end determining means for determining a reference-speed-manipulation-end to which no adjustment amount in a speed control is given so that a speed adjustment amount at each speed manipulation end becomes minimum based on preset data of rolling including a strip thickness and tension, and a rowing condition including a control output including a strip thickness control and a tension control; and
speed adjustment reference creating means for determining respective speed adjustment amounts for the entry-side bridle roll, the delivery-side bridle roll, and the plurality of rolling stands in accordance with the reference-speed-manipulation-end determined by the reference-speed-manipulation-end determining means, and outputting the
respective speed adjustment amount to each speed manipulation end.
1 2. The rolling apparatus according to claim 11, wherein the speed adjustment reference creating means performs successive control for adding a speed manipulation amount to the each speed manipulation end whose speed is adjusted with reference to the reference-speed-manipulation-end side, the speed manipulation amount determined based on a control output amount to the each speed manipulation end in accordance with a speed distribution for the speed manipulation ends.
13. The rolling apparatus according to claim 11, wherein the reference-speed-manipulation-end determining means determines the reference-speed-manipulation-end using a control rule including a fuzzy inference in which a speed adjustment amount at each speed manipulation end is determined in advance to be minimum based on the rolling condition.
14. The rolling apparatus according to claim 11, wherein the reference-speed-manipulation-end determining means acquires an evaluation value using an evaluation function predetermined based on a speed adjustment amount at each speed manipulation end, and determines the reference-speed-manipulation-end so that the evaluation value becomes an optimized value.
15. The rolling apparatus according to claim 11, wherein the entry-side bridle roll and the speed control means for the entry-side bridle roll are an entry-side tension reel and a speed or torque control means for the entry-side tension reel,
respectively.
16. The rolling apparatus according to claim 11, wherein the delivery-side bridle roll and the speed control means for the delivery-side bridle roll are a delivery-side tension reel and a speed or torque control means for the delivery-side tension reel, respectively.
17. A method of controlling a rolling apparatus, the rolling apparatus comprising:
an entry-side bridle roll which controls tension applied to a rolled strip at an entry side of a mill,
speed control means for the entry-side bridle roll,
a delivery-side bridle roll which controls tension applied to a rolled strip at an delivery side at a delivery side of the mill,
speed control means for the entry-side bridle roll,
speed control means for the delivery-side bridle roll;
a plurality of rolling stands;
speed control means for the plurality of rolling stands;
a strip thickness detector which detects a strip thickness of the rolled strip;
a tension detector which detects tension of the rolled strip; and
a plurality of control means which output a speed of the entry-side bridle roll, a speed of the delivery-side bridle roll, and a speed of the plurality of rolling stands to respective speed manipulation ends based on preset data of rolling acquired from a strip thickness of the rolled strip detected by the strip thickness detector and tension of the rolled strip detected by the tension detector,
the method comprising,
a step of determining a reference-speed-manipulation-end to which no adjustment amount in a speed control is given so that a speed adjustment amount at each speed manipulation end becomes minimum based on preset data of rolling including a strip thickness and tension, and a rolling condition including a control output including a strip thickness control and a tension control; and
a step of determining respective speed adjustment amounts for the entry-side bridle roll, the delivery-side bridle roll, and the plurality of rolling stands in accordance with the reference-speed-manipulation-end determined by reference-speed-manipulation-end determining means, and outputting the respective speed adjustment amount to each speed manipulation end.
18. The rolling apparatus control method according to claim 17, wherein the step of determining respective speed adjustment amounts includes a successive control step of adding a speed manipulation amount to the each speed manipulation end whose speed is adjusted with reference to the reference-speed-manipulation-end side, the speed manipulation amount determined based on a control output amount to the each speed manipulation end in accordance with a speed distribution for the speed manipulation ends.
19. The rolling apparatus control method according to claim 17, wherein the reference-speed-manipulation-end is determined using a control rule including a fuzzy inference a control rule including a fuzzy inference in which a speed adjustment amount at each speed manipulation end is determined in advance to be minimum based on the rolling condition, in the step of determining a reference-speed-mani'pulation-end.
20. The rolling apparatus control method according to claim 17, wherein an evaluation value is acquired using an evaluation function predetermined based on a speed adjustment amount at each speed manipulation end, and the reference-speed-manipulation-end is determined so that the evaluation value becomes an optimized value, in the step of determining a reference-speed-manipulation-end.
21. The rolling apparatus control method according to claim 17, wherein the entry-side bridle roll and the speed control means for the entry-side bridle roll are an entry^-side tension reel and a speed or torque control means for the entry-side tension reel, respectively.
22. The rolling apparatus control method according to claim 17, wherein the
delivery-side bridle roll and the speed control means for the delivery-side bridle
roll are a delivery-side tension reel and a speed or torque control means for the
delivery-side tension reel, respectively.
23. A rolling mill, substantially as herein described with reference to accompanying drawings and example.
24. A method of controlling a rolling mill, substantially as herein described with reference to accompanying drawings and example.
25. A rolling apparatus, substantially as herein described with reference to accompanying drawings and example.
26. A method of controlling a rolling apparatus, substantially as herein described with
reference to accompanying drawings and example.