JPH11129012A - Tension control method and equipment for metal band in rolling mill exit side - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of slip flaws of a metal band in cutting process while moving, and suppress plate thickness fluctuation of the metal band and stabilize the shape of the metal band. SOLUTION: The first subtraction circuit 26 obtains a current deviation between the order current sent through a goal tension setting circuit 23, an order tension setting circuit 24 and a conversion circuit 25, and a detected current from a current detector 18. The second subtraction circuit 30 obtains a speed deviation between an order curcumferential speed sent through an increment speed setting circuit 28 and an order circumferential speed setting circuit 29, and a detected circumferential speed from a circumferential speed detector 17. A limiting circuit 31 limits the speed deviation based on an upper limit and a lower limit of speed deviation from a limit speed difference setting circuit 33. A current control circuit 34 controls the current of a drive motor 11 of a bridle role by correcting the current deviation by the output of the limiting circuit 31. By the proper setting of upper and lower limit values of the speed deviation, it is possible to prevent the generation of slip flaws of the metal band in cutting process while moving and suppress plate thickness fluctuation of the metal band and stabilize the shape of the metal band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the tension of a metal strip on the exit side of a rolling mill in a continuous rolling facility, and more particularly to a method and an apparatus for controlling the tension during cutting of a metal strip during running.

[0002]

2. Description of the Related Art Conventionally, on the exit side of a rolling mill provided in a continuous rolling facility, for example, a cold rolling mill, a high tension is applied to a metal strip to perform cold rolling. Prevention of plate thickness fluctuation and stabilization of the shape are achieved. Usually, bridle rolls,
A cutting machine and a winding machine are arranged in this order, and the winding machine and the bridle roll share a tension load so that a high tension can be applied to the metal band. The tension control of the metal strip on the exit side of the rolling mill during the steady rolling is performed by controlling the tension applied to the bridle roll so that the tension of the metal strip on the exit side of the rolling mill (hereinafter, referred to as the exit side tension of the rolling mill) becomes a predetermined tension. This is done by controlling the load. That is,
The bridle roll increases the current of the drive motor of the bridle roll when the rolling mill output side tension is lower than a predetermined tension, and decreases the bridging roll when the rolling mill output side tension is higher than the predetermined tension. The rotational torque applied to is corrected.

On the other hand, at the time of cutting while the metal strip is running, the tension on the exit side of the rolling mill, which is shared by the winding machine and the bridle roll, must be borne by the bridle roll alone. The tension of the metal strip decreases during the period until the tip of the cut metal strip is wound around the winder again. For this reason, the bridle roll drive motor attempts to correct the current by increasing the current in order to keep the tension of the metal band at a predetermined tension. However, since the contact pressure between the bridle roll and the metal band is small at the time of cutting during running, slippage may occur on the contact surface and slip defects may occur on the metal band.
Since slip flaws are serious defects in product quality and are unacceptable regardless of their degree, their occurrence must be completely prevented.

As a prior art for solving the above-mentioned problem, Japanese Patent Application Laid-Open No. 7-16629 is disclosed. In the prior art, as shown by a transition line U1 in FIG. 10 (2), from time t11 when the metal band is cut during running, time t12 when the tip of the cut metal band is wound around the reel of the winder again. During this period, the peripheral speed of the bridle roll is controlled to be the same as the peripheral speed of the bridle roll before cutting during running.

[0005]

According to the control method of the prior art, although the occurrence of slip flaws can be prevented, tension cannot be applied to the metal band.
As shown in (1), during the period (time t11 to t12) from the time when the metal band is cut during running to the time when the tip of the cut metal band is wound around the winding machine again (time t11 to t12), the tension is reduced and recovered. It is not possible. As a result, during the above-mentioned period, there is a problem that the thickness of the metal strip greatly fluctuates and the shape of the metal strip deteriorates.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the occurrence of slip flaws in a metal band during cutting while the metal band is running, and to further suppress the variation in the thickness of the metal band and stabilize the shape. It is an object of the present invention to provide a method and an apparatus for controlling the tension of a metal strip on the exit side of a rolling mill.

[0007]

According to the present invention, a plurality of bridle rolls, a running cutter, and a winding machine are arranged in this order on the exit side of a rolling mill to cut and wind a running metal strip. In the method for controlling the tension of the metal strip on the rolling mill exit side in a continuous rolling facility in which the traveling speed of the metal strip on the rolling mill exit side is detected, the traveling distance of the cutting point of the metal strip is detected, and In response, during the traveling period from when the cutting point of the metal band reaches a predetermined position on the upstream side of the traveling cutting machine to when the cut metal band is wound again by the winder, the detected metal is detected. A method for controlling the tension of a metal strip on the exit side of a rolling mill, characterized in that the difference between the running speed of the strip and the peripheral speed of each bridle roll is limited to a small value so as to avoid the occurrence of slip flaws in the metal strip.

According to the present invention, the difference between the running speed of the metal band and the peripheral speed of each bridle roll is limited during a certain period before and after the cutting of the metal band. It is possible to prevent the occurrence of slip flaws in the metal strip due to the speed difference.

Further, according to the present invention, a plurality of bridle rolls, a running cutter, and a winding machine are arranged in this order on the rolling mill output side, and the bridle roll and the winding machine use the metal strip on the rolling mill output side. In the tension control device for the metal strip on the rolling mill exit side in a continuous rolling facility in which the metal strip is wound while applying tension to the metal strip, and a running cut is performed at a predetermined cutting point of the metal strip, each bridle roll is driven. The motor has a variable rotation speed given a control signal,
Traveling speed detecting means for detecting the traveling speed of the metal strip on the exit side of the rolling mill; tension detecting means provided on the exit side of the rolling mill for detecting the tension of the metal strip; and detecting the peripheral speed of each bridle roll. Peripheral speed detecting means, control signal detecting means for detecting a control signal applied to the drive motor of each bridle roll, cutting point detecting means for detecting a cutting point of the metal band, and cutting the traveling distance of the cutting point of the metal band. A travel distance detecting means for detecting the installation position of the point detecting means as a starting point; and a control signal generating means for providing a control signal to the drive motor, wherein outputs of the travel speed detecting means, the cutting point detecting means and the travel distance detecting means are provided. In response to, to detect the traveling distance of the cutting point of the metal band, during the traveling period from the time when the cutting point of the metal band reaches a predetermined position on the upstream side of the traveling cutting machine until it reaches the winding machine, The tension detecting means In response to the output of the peripheral speed detecting means and the control signal detecting means, the rotation speed of the drive motor of each bridle roll is limited to a small value so as to avoid occurrence of slip flaws in the metal band, and the tension of the metal band after cutting is reduced. And a control means for controlling the tension to recover to a predetermined tension at an early stage.

According to the present invention, since the control means for limiting the rotation speed of the drive motor of each bridle roll to a small value based on the output of each detection means is provided, the peripheral speed of the bridle roll is suppressed to reduce the metal band. Can be prevented from occurring. Further, since the tension of the metal band after cutting is controlled by the control means so as to be greater than that at the time of cutting, the tension of the metal band that has dropped at the time of cutting can be recovered at an early stage. Further, since the traveling speed detecting means, the cutting point detecting means and the traveling distance detecting means for the cutting point are provided, it is possible to detect the traveling position of the cutting point of the metal band, and the cutting point of the metal band is located at a predetermined position. , And the time period from when the vehicle reaches the winding machine can be accurately grasped.
Therefore, the period during which the circumferential speed of the bridle roll is suppressed can be shortened.

Further, the control means of the present invention subtracts the target tension of the metal strip shared by the winding machine from the preset target tension of the metal strip on the exit side of the rolling mill, and sets the target tension of the metal strip shared by the bridle roll. Based on the output of the target tension setting circuit for obtaining the target tension and the output of the target tension setting circuit and the tension detecting means,
A command tension setting circuit that corrects the target tension of the metal band shared by the bridle roll and obtains a command tension of the metal band shared by the bridle roll, a conversion circuit that converts the obtained command tension into a command current, and the control signal The detecting means is a current detecting means, based on the output of the conversion circuit and the current detecting means, a first subtraction circuit for calculating a current deviation between the obtained command current and the detected current, and a metal strip on a rolling mill exit side. An incremental speed setting circuit for setting an increment of the peripheral speed of the bridle roll with respect to the traveling speed; a command peripheral speed setting circuit for obtaining a command peripheral speed of the bridle roll based on an output of the incremental speed setting circuit; and a command peripheral speed setting circuit And a second subtraction circuit for obtaining a speed deviation between the obtained command peripheral speed and the detected peripheral speed based on an output of the peripheral speed detecting means, and a limit range of the obtained speed deviation. A limit speed difference setting circuit, a second subtraction circuit, and a limit speed difference setting circuit that are set so that the occurrence of slip flaws in the metal band can be avoided and the tension of the metal band after cutting is set to be larger than that at the time of cutting. A limiter circuit for limiting the obtained speed deviation on the basis of the output of the current control circuit, and the control signal generating means is a current control circuit, wherein the obtained current deviation is obtained based on the outputs of the first subtraction circuit and the limiter circuit. And a current control circuit that controls the current of the drive motor of the bridle roll during the period so that the calculated corrected current deviation becomes zero during the period.

According to the present invention, since the first subtraction circuit is provided, the current deviation between the command current of the bridle roll drive motor and the detected current can be obtained, and the second subtraction circuit is provided. Accordingly, a speed deviation between the command peripheral speed of the bridle roll and the detected peripheral speed can be obtained. Further, since the limit speed difference setting circuit is provided, the limit range of the obtained speed deviation is set so that the slip flaw does not occur on the surface of the metal band, and the tension of the metal band after cutting is lower than that at the time of cutting. It can be set to increase. Further, since the limiter circuit is provided, the obtained speed deviation can be limited. Further, since a current control circuit is provided, it is possible to correct the obtained current deviation to obtain a corrected current deviation, and to control the current of the bridle roll drive motor so that the obtained corrected current deviation becomes zero. it can. Thereby, the control means can suppress the current of the drive motor of the bridle roll, prevent the occurrence of slip flaws in the metal band, and quickly recover the tension of the metal band after cutting to the predetermined tension. it can.

[0013]

FIG. 1 is a system diagram showing a schematic configuration of a tension control device according to an embodiment of the present invention. FIG.
FIG. 1 also shows a schematic configuration of a rolling facility provided with the tension control device 1 of the present embodiment, for example, a continuous cold rolling facility. The continuous cold rolling equipment is configured to sequentially weld a metal strip, for example, a steel strip 7 that is passed in advance, and a steel strip 7 that is subsequently passed, and continuously cool the steel strip 7 while traveling. This is a facility that cuts a rolled and cold-rolled steel strip 7 at a cutting point while winding the strip into a coil shape. The cutting point is a predetermined cutting position of the steel strip 7, and the welding point is usually the cutting point. However, when the thickness is changed in the same material, the thickness change point is the cutting point. The continuous cold rolling equipment of the present embodiment is configured by arranging a cold rolling mill 2, four bridle rolls 3a to 3d, a running cutting machine 5, and a winding machine 6 in this order. ing.

The cold rolling mill 2 is a tandem rolling mill in which four four-high rolling mills are arranged in series, and each four-high rolling mill is provided with a pair of upper and lower work rolls and backup rolls. The cold rolling mill 2 performs cold rolling to a predetermined thickness while applying tension to the steel strip 7. The bridle rolls 3a to 3d are devices that apply tension to the steel strip 7, and are individually rotated and driven by the drive motors 11a to 11d while the steel strip 7 is wound around four bridle rolls 3a to 3d. Each of the bridle rolls 3a to 3d is a right cylindrical roll, and has the same roll outer diameter. Hereafter, bridle rolls 3a to 3d and drive motor 11a
To 11d may be collectively referred to as the bridle roll 3 and the drive motor 11, respectively. The tension is applied to the steel strip 7 by making the peripheral speed of each of the bridle rolls 3a to 3d higher than the running speed of the steel strip 7 on the rolling mill exit side. As a result, the running speed of the steel strip 7 in contact with each bridle roll 3 becomes higher than the running speed of the steel strip 7 on the rolling mill exit side, so that tension is applied to the steel strip 7 on the rolling mill exit side. Granted.

The drive motor 11 is a three-phase induction motor, and the rotation speed of the drive motor 11 is varied by a given control signal, for example, a current control signal. The current control signal is transmitted from a current control circuit 34 which is a control signal generating means as described later. In the present embodiment, as shown in FIG. 2, electric power is supplied from a three-phase AC power supply 14 to a drive motor 11 via an inverter 15. Inverter 15
Is a power converter with a variable voltage and a variable frequency, and speed control and torque control of the drive motor 11 are performed by controlling a current of an inverter which is a control signal. The control signal is detected by current detecting means 18 which is a control signal detecting means. During the control, the speed and torque of the drive motor 3 increase as the current supplied to the inverter increases, and the tension applied to the steel strip 7 increases.
Each of the drive motors 11a to 11d has the same rated capacity, and rotationally drives each of the bridle rolls 3a to 3d to have the same peripheral speed.

The running cutting machine 5 is a cutting machine having a pair of upper and lower rotating blades, and cuts the steel strip 7 in a running state. The winder 6 is a winder called a carousel reel,
It has two take-up reels 6a and 6b. The two take-up reels 6a and 6b are used alternately, and one take-up reel 6a is used.
When the winding of the steel strip 7 as the preceding material in the above is completed, the steel strip 7 as the succeeding following material is wound on the other winding reel 6b. The winding machine 6 controls the rotation speed of the take-up reels 6a and 6b so that the winding speed of the steel strip 7 becomes constant, and
Take up. A snubber roll 8 is provided below the bridle roll 3d. The snubber roll 8 can be freely raised and lowered by the hydraulic cylinder 12, and when the steel strip 7 is cut, it rises and sandwiches the steel strip 7 between the bridle roll 3d and the snubber roll 8. Bridle roll 3
A pinch roll 4 is provided between d and the inter-cutting machine 5. On the upstream side of the cold rolling mill 2, two entrance bridle rolls 13a and 13b are provided.

The steel strip 7 includes an entrance bridle roll 13a,
In a welding machine (not shown) provided on the upstream side of 13b, the rear end of the preceding material and the front end of the following material are welded, and a hole is punched at the cutting point on the exit side of the welding machine. Then, it is cold-rolled by a cold rolling mill, and is wound on one winding reel 6 a of a winding machine 6 via a bridle roll 3 and a running cutting machine 5. During winding, when the cutting point of the steel strip 7 reaches the traveling cutting machine 5, the cutting of the steel strip 7 is performed, and the cut end of the steel strip 7 is connected to the other winding reel 6 b of the winding machine 6. It is wound up. The exit side tension of the rolling mill during the cold rolling is imparted by the bridle roll 3 and the winder 6 in a shared manner. The tension load shared by the bridle roll 3 and the winder 6 is determined by the equipment specifications.

The tension control device 1 is a device for controlling the tension of the steel strip 7 on the exit side of the cold rolling mill. The tension control device 1 is a traveling speed detector 16 which is a traveling speed detecting means, and the tension detector 9 which is a tension detecting means. A peripheral speed detector 17 as a peripheral speed detecting means, a current detector 18 as a current detecting means, a cutting point detector 19 as a cutting point detecting means, and a moving distance detector 20 as a traveling distance detecting means. And a control device 10 as a control means. The traveling speed detector 16 includes, for example, a pulse generator and a pulse counter, and detects the traveling speed of the steel strip 7 on the exit side of the cold rolling mill 2. The pulse generator is attached to an electric motor that drives the work roll of the final stand of the cold rolling mill 2, and the number of generated pulses is counted by a pulse counter. The running speed is
The pulse rate (mm /
Pulse).

The tension detector 9 comprises, for example, a tension roll and a load meter, and is a detector for obtaining the tension from the load of the tension roll. The tension detector 9 is provided between the cold rolling mill 2 and the bridle roll 3a, and detects the tension of the steel strip 7 on the exit side of the rolling mill. The peripheral speed detector 17 comprises, for example, a pulse generator and a pulse counter, and its configuration and operation are exactly the same as those of the traveling speed detector 16.
The pulse generator of the peripheral speed detector 17 is attached to each of the drive motors 11a to 11d of each of the bridle rolls 3a to 3d, and individually detects the peripheral speed of each of the bridle rolls 3a to 3d. The current detector 18 is an ammeter, and individually detects the current supplied to the drive motors 11a to 11d of the bridle rolls 3a to 3d as described above.

The cut point detector 19 is, for example, a hole detector including a light projector and an optical sensor, and is provided near the exit side of the entrance bridle roll 13a. Cutting point detector 1
9 detects a hole formed at a cutting point of the steel strip 7 and transmits a detection signal. The travel distance detector 20 includes, for example, a pulse generator and a pulse counter, and detects a travel distance of a cutting point of the steel strip 7. The pulse generator of the traveling distance detector 20 is attached to, for example, the drive motor of the entrance bridle roll 13a, and the number of generated pulses is counted by a pulse counter.

The travel distance of the cutting point of the steel strip 7 is obtained by multiplying the accumulated pulse number of the pulse counter by the pulse rate (mm / pulse). Therefore, steel strip 7
If the number of pulses of the pulse counter is reduced to zero at the time when the cutting point passes through the cutting point detector 19, the travel distance of the cutting point of the steel strip 7 is determined based on the integrated pulse number of the pulse counter. Can be obtained as a starting point. The traveling speed of the steel strip 7 on the rolling mill entry side can be obtained by multiplying the number of generated pulses per unit time of the pulse counter of the traveling distance detector 20 by a pulse rate (mm / pulse). Further, the required travel distance until the cutting point of the steel strip 7 reaches the predetermined position from the installation position of the cutting point detector 19 is calculated based on the equipment distance and the increase in the plate length due to cold rolling. The amount of increase in the plate length is determined by the traveling speed of the steel strip 7 on the rolling mill exit side detected by the traveling speed detector 16 and the traveling speed of the steel strip 7 on the rolling mill entrance side detected by the traveling distance detector 20. Is determined based on the ratio of Accordingly, when the travel distance of the cutting point of the steel strip 7 matches the required travel distance obtained above, it is determined that the cutting point of the steel strip 7 has reached the predetermined position. The timing to reach the position can be accurately grasped. The control device 10 is realized by, for example, a computer, and determines whether or not the cutting point has reached a predetermined position. In addition, the control device 10 responds to the output of each of the detectors, as described later, to determine the current of the drive motor 11 of the bridle roll 3, in other words, Controls the exit tension of the rolling mill.

Referring to FIG. 1, cutting point detector 19 detects a cutting point of steel strip 7 and outputs a detection signal to travel distance detector 20.
And sends it to the controller 10. The traveling distance detector 20 makes the count value of the pulse counter zero in response to the output of the cutting point detector 19, and sends a pulse integrated value representing the traveling distance of the cutting point of the steel strip 7 to the control device 10. The traveling speed detector 16 detects the traveling speed of the steel strip 7 on the exit side of the rolling mill and sends a detection signal to the control device 10. The tension detector 9 detects the tension of the steel strip 7 on the exit side of the rolling mill and outputs a detection signal to the control device 1.
Send to 0. The peripheral speed detector 17 detects the peripheral speed of the bridle roll 3 and sends a detection signal to the control device 10. The current detector 18 detects a current of the drive motor 11 of the bridle roll 3 and sends a detection signal to the control device 10. The control device 10 responds to the outputs of the traveling speed detector 16, the cutting point detector 19, and the traveling distance detector 20, detects the position of the cutting point of the steel strip 7 as described above, and It is determined whether or not has reached a predetermined position, and the traveling period from when the cutting point of the steel strip 7 reaches a predetermined position on the upstream side of the inter-cutting machine 5 to when it reaches the winder 6 is determined. Ask. In response to the outputs of the tension detector 9, the peripheral speed detector 17 and the current detector 18, the current of the drive motors 11a to 11d of the bridle rolls 3a to 3d is changed during the obtained period.
In addition to restricting or suppressing the occurrence of slip flaws in the steel strip 7, the tension of the steel strip 7 after cutting is controlled to be greater than that at the time of cutting.

The slip flaw is a surface flaw of the steel strip 7 generated based on a difference ΔV between the peripheral speed of the bridle roll 3 and the running speed of the steel strip 7, and is determined by visual observation. Slip flaws occur when the difference ΔV exceeds ΔV1, as shown in FIG. 3, and the number of flaws increases as the difference ΔV increases. Since the occurrence of slip flaws is not allowed at all as described above, the straight line L1 representing the allowable limit of slip flaws exists at a position where the number of flaws is zero, and the difference ΔV1 becomes the limit value of the difference.

As described above, the traveling speed detector 16, the cutting point detector 19 and the traveling distance detector 20 are provided so that the timing at which the cutting point of the steel strip 7 reaches the predetermined position can be accurately grasped. Therefore, the travel period from when the cutting point of the steel strip 7 reaches a predetermined position on the upstream side of the inter-cutting machine 5 to when it reaches the winding machine 3 can be accurately obtained. . Therefore, the predetermined position can be brought close to the cutting machine 5 while running,
The period during which the current of the drive motor 11 of the bridle roll 3 is suppressed can be shortened. As a result, the current,
In other words, the period in which the tension is not suppressed can be lengthened, and a large tension can be applied to the steel strip 7 immediately before cutting. The configuration and operation of the control device 10 will be described later.

FIG. 4 is a block diagram showing an electrical configuration of the control device shown in FIG. FIG. 4 shows only the configuration of a portion related to the tension control of the steel strip 7 in the configuration of the control device. The control device 10 includes a target tension setting circuit 23,
A command tension setting circuit 24, a conversion circuit 25, a first subtraction circuit 26, an incremental speed setting circuit 28, a command peripheral speed setting circuit 29, a second subtraction circuit 30, a limiter circuit 31,
It is configured to include a limit speed difference setting circuit 33 and a current control circuit 34. Target tension setting circuit 23 is a subtraction circuit for determining the target tension T _B of the steel strip 7 which is bridle roll 3 share. The target tension T _B of the steel strip 7 shared by the bridle roll 3 is obtained by subtracting the target tension T _R of the steel strip 7 shared by the winding machine from the target tension Tt of the steel strip 7 on the rolling mill exit side. The calculation equation is shown in equation (1). _{T B = Tt - T R ...} (1)

The target tension Tt of the steel strip 7 on the delivery side of the rolling mill is a predetermined be the target tension by the rolling conditions, the target tension T _R of the steel strip 7 which winder 6 is shared, the bridle roll 3 and winding This is a target tension determined based on the tension load distribution ratio with the taker 6. In this embodiment, on the basis of the target tension T _B of the steel strip 7, wherein the bridle roll 3 obtained sharing, tension control of the strip 7 takes place. The output of the target tension setting circuit 23 is sent to the command tension setting circuit 24.
The command tension setting circuit 24 is a circuit that obtains a command tension Tc of the steel strip 7 shared by the bridle roll 3. The command tension Tc is given by (2), (3), where T is the rolling mill exit side tension detected by the tension detector 9 and ΔT is the tension deviation.
It is determined by the formula. The output of the command tension setting circuit 24 is sent to the conversion circuit 25. _{ΔT = T B - (T -} T R) ... (2) T C = T B + ΔT ... (3)

The conversion circuit 25 is a circuit for converting the tension into a current, and converts the obtained command tension Tc into a command current Ic. The output of the conversion circuit 25 is sent to a first subtraction circuit 26. The first subtraction circuit 26 is a circuit for obtaining a current deviation ΔI. The current deviation ΔI is obtained by Expression (4), where I is a detection current of the drive motor 11 of the bridle roll 3 detected by the current detector 18. . The output of the first subtraction circuit 26 is sent to the current control circuit 34. ΔI = I _C −I (4)

The incremental speed setting circuit 28 is a circuit for setting an increment ΔF of the peripheral speed of the bridle roll 3 with respect to the running speed of the steel strip 7 on the rolling mill exit side. As described above, the tension is applied to the steel strip 7 by setting the peripheral speed of the bridle roll 3 to be higher than the traveling speed of the steel strip 7 on the exit side of the rolling mill. It is set based on the target tension Tt of the steel strip 7 on the exit side of the rolling mill. The output of the incremental speed setting circuit 28 is sent to the command peripheral speed setting circuit 29.

The command peripheral speed setting circuit 29 is a circuit for obtaining a command peripheral speed Rc of the bridle roll 3. If the target peripheral speed Rc of the steel strip 7 on the exit side of the rolling mill is F, the command peripheral speed Rc is (5 ). The output of the command peripheral speed setting circuit 29 is sent to the second subtraction circuit 30. R _C = F + ΔF (5)

Here, the target value F is used as the traveling speed of the steel strip 7 on the exit side of the rolling mill, and the detection value of the traveling speed detector 16 is not used because the use of the detection value causes a response delay. It is. However, since the traveling speed control is being performed, the target value matches the detected value, and the command peripheral speed Rc is equivalent to a value obtained based on the detected value.

The second subtraction circuit 30 is a circuit for obtaining a speed deviation ΔR. The speed deviation ΔR is obtained by the equation (6), where R is the detected peripheral speed of the bridle roll 3 detected by the peripheral speed detector 17. Can be Second subtraction circuit 30
Is sent to the limiter circuit 31. ΔR = _RC -R (6)

The limit speed difference setting circuit 33 is a circuit for setting a limit range of the obtained speed deviation ΔR. The upper limit value ΔLu of the limit range is set so that the circumferential speed of the bridle roll 3 does not become excessive, in other words, so that no slip flaws occur in the steel strip 7, and the lower limit value ΔLd of the limit range is In order to prevent the peripheral speed of the roll 3 from becoming too low, in other words, the tension of the steel strip 7 after cutting is set to be higher than that at the time of cutting. The output of the limit speed difference setting circuit 33 is sent to the limiter circuit 31.

The limiter circuit 31 is a circuit for limiting the obtained speed deviation .DELTA.R. As shown in FIG. 5, the speed deviation .DELTA.R exceeds the upper limit value .DELTA.Lu of the limit range and the speed deviation .DELTA.R less than the lower limit value .DELTA.Ld of the limit range. Are cut and output as the upper limit value ΔLu and the lower limit value ΔLd.
In the present embodiment, the upper limit value ΔLu of the limit range is set to zero. Therefore, the output of the limiter circuit 31 becomes negative. The output of the limiter circuit 31 is sent to a current control circuit 34 by converting the speed into a current. The current control circuit 34 is a circuit that controls the current of the drive motor 11 of the bridle roll 3. The control in the current control circuit 34 is performed by adding the obtained current deviation ΔI and the output of the limiter circuit 31 to obtain a corrected current deviation ΔIa.
This is performed by controlling the current of the drive motor 11 so that Ia becomes zero.

FIG. 6 is a flowchart for explaining the tension control method of the present invention. In step a1, tension control of the steel strip 7 in the continuous cold rolling facility is started.
In step a2, the first tension control is started. The first tension control is performed such that the drive motor 11 of the bridle roll 3 is driven so that the tension of the steel strip 7 on the exit side of the rolling mill becomes a predetermined target tension.
Is controlled by the command current I as described later.
Control is performed so that the current deviation ΔI, which is the difference between c and the detected current I, becomes zero. In step a3, it is determined whether or not the cutting point of the steel strip 7 has reached a predetermined position. This decision
The control is performed by the control device 10 based on the outputs of the traveling speed detector 16, the cutting point detector 19, and the traveling distance detector 20. The predetermined position is a predetermined position on the upstream side of the running cutter 5, for example, a final stand of the cold rolling mill 2. If the determination is negative, the process returns to step a2 and the first tension control is continued. If the determination is affirmative, the process proceeds to step a4.

In step a4, a second tension control is performed. The second tension control is a control method in which the output signal of the limiter circuit 31 is sent to the current control circuit 34 to correct the current deviation ΔI of the first tension control in the negative direction, thereby suppressing the current of the drive motor 11. The second control is performed before and after the cutting of the steel strip 7. In step a5, it is determined whether or not the leading end of the steel strip 7, which is the following material, has reached the winder 6, and whether or not the cut leading end of the steel strip 7 has been wound on the take-up reel. If this determination is negative, the process returns to step a4,
The second tension control is continued. If this determination is affirmative, the process returns to step a2, and the first tension control is performed again. Such a process is repeated until the continuous rolling of the steel strip 7 in the continuous rolling facility is completed.

As described above, the second tension control is performed immediately before the cutting of the steel strip 7 and during the period from when the steel strip 7 is cut and wound around the reel again. Current can be suppressed. Therefore, an increase in the peripheral speed of the bridle roll 3 can be suppressed. A method of correcting the current deviation ΔI in the second tension control will be described later.

FIG. 7 is a flowchart for explaining a control method of the first tension control shown in FIG. Step b
At 1, the first tension control of the steel strip 7 is started. In step b2, the setting of the target tension T _B of the steel strip 7 to share the bridle roll 3 is performed. Setting of the target tension T _B is
This is performed based on equation (1). In step b3, the output of the rolling mill and the current of the drive motor 11 are detected. The detection of the rolling mill exit side tension T is performed by the tension detector 9, and the detection of the current I is performed by the current detector 18. In step b4, the command tension Tc is set based on the above equations (2) and (3). In step b5, the command tension Tc is converted into a command current Ic. The conversion is performed by the conversion circuit 25. In step b6, the current deviation ΔI is calculated based on the equation (4). In step b7, current control is performed by the current control circuit 34. In the current control, the current deviation ΔI
Is controlled by controlling the current of the drive motor 11 so as to become zero. In step b8, it is determined whether or not the cutting point of the steel strip 7 has reached the running cutting machine 5. If this determination is negative, the process returns to step b3, and the above processing is repeated. If this judgment is affirmative, the steel strip 7 to be controlled is
Is terminated.

FIG. 8 is a flowchart for explaining a method of correcting a current deviation in the second tension control shown in FIG. Starting at step c1, at step c2,
The setting of the incremental speed ΔF, the target traveling speed F, and the limit speed difference is performed. As described above, the incremental speed is set in the incremental speed setting circuit 28 based on the target tension Tt of the steel strip 7 on the rolling mill exit side, and the upper limit value ΔLu and the lower limit value ΔLd of the speed deviation ΔR, which is the limit speed difference, Limit speed difference setting circuit 3
3, the peripheral speed of the bridle roll 3 is set so as not to be excessively large or small. That is, the upper limit value ΔLu of the speed deviation ΔR is set so that no slip flaw occurs in the steel strip 7 after the correction, and the lower limit value ΔLd of the speed deviation ΔR is set such that the tension of the steel strip 7 after the cutting after the correction is lower than that at the time of cutting. It is set to increase. Also, the target traveling speed F
Is set based on the rolling pass schedule of the steel strip 7.

In step c 3, the peripheral speed R of the bridle roll 3 is detected by the peripheral speed detector 17.
In step c4, the command peripheral speed Rc is set based on the equation (5). In step c5, the speed deviation ΔR is calculated based on the equation (6). In step c6, the speed deviation ΔR is limited. The limitation of the speed deviation ΔR is performed by cutting the speed deviation ΔR outside the upper and lower limit values. That is, the speed deviation ΔR is equal to the upper limit value Δ
When Lu exceeds Lu, ΔR = ΔLu, and the speed deviation Δ
When R is less than the lower limit ΔLd, ΔR = ΔLd, and
When the speed deviation ΔR is within the range of the upper and lower limits, ΔR
= ΔR. In step c7, the speed is converted into a current, and a correction value of the current deviation is obtained from the limited speed deviation. In step c8, the corrected current deviation ΔIa is obtained by adding the obtained correction value to the current deviation ΔI. In step c9, the correction of the current deviation ΔI is completed.

FIG. 9 is a graph showing changes in the tension of the steel strip on the exit side of the rolling mill and the circumferential speed of the bridle roll during the tension control. FIG. 9 shows the transition before and after the cutting of the steel strip 7 among the above transitions. At time t1, the first tension control is performed, and the steel strip 7 is given a high tension based on the rolling conditions. The output side tension of the rolling mill and the peripheral speed of the bridle roll 3 around time t1 are kept constant. At time t2, the cutting point of the steel strip 7 reaches the final stand of the cold rolling mill 2 at a predetermined position. Further, the second tension control is started, and the reduction of the tension on the exit side of the rolling mill is started. The reduction of the tension on the exit side of the rolling mill
In order to prepare for cutting, the bridging roll 3 alone is used to carry the tension load. At time t3, the reduction of the tension is completed, and the tension is reduced to almost half. At time t4, the steel strip 7 is cut while running. By cutting while running,
The exit side tension of the rolling mill temporarily decreases greatly, and gradually increases with time. On the other hand, the peripheral speed of the bridle roll 3 is kept almost constant after slightly increasing as shown by a transition line R1 in FIG. At time t5, the cut end of the steel strip 7 is wound on a winding reel of the winding machine 6,
The first tension control is started again. Due to the winding on the take-up reel, the tension on the exit side of the rolling mill sharply increases, the peripheral speed of the bridle roll 3 decreases, and returns to the level before the increase. The tension on the exit side of the rolling mill after the winding of the take-up reel is kept almost constant at the level immediately before cutting. At time t6, the increase of the rolling mill exit side tension starts, and at time t7, the tension returns to the original high level.

As described above, from when the cutting point of the steel strip 7 reaches the predetermined position on the upstream side of the running cutter 5 until the cut steel strip 7 is wound up again by the winder 6. Period (time t
During the period from 2 to t5), the second tension control in which the current of the drive motor 11 is suppressed is performed, so that the increase in the peripheral speed of the bridle roll 3 after cutting during running can be controlled so as not to be excessive. . Therefore, it is possible to prevent the occurrence of slip flaws in the steel strip 7 after cutting.
In addition, the second tension control controls the circumferential speed of the bridle roll 3 so that the increase amount is not excessively small.
The tension of the steel strip 7 after cutting is greater than at the time of cutting. Therefore, the thickness variation of the steel strip 7 after cutting can be suppressed, and the shape of the steel strip 7 after cutting can be stabilized.

[0042]

As described above, according to the first aspect of the present invention, the speed difference between the running speed of the metal strip after cutting and the peripheral speed of the bridle roll can be reduced, so that the slip of the metal strip can be reduced. The generation of flaws can be prevented. Therefore, the production yield of the metal strip can be improved.

According to the second aspect of the present invention, the tension of the metal band after cutting can be increased more than that at the time of cutting, so that the tension of the metal band that has decreased during cutting can be recovered at an early stage. . Therefore, the thickness variation of the metal strip after cutting can be suppressed, and the shape of the metal strip can be stabilized. Further, since the period from when the cutting point of the metal band reaches the predetermined position to when the metal band reaches the winding machine can be accurately grasped, the period during which the current of the drive motor of the bridle roll is suppressed is shortened. can do. Therefore, the period during which the current is not suppressed can be lengthened, and a large tension can be applied to the metal strip until immediately before cutting.

According to the third aspect of the present invention, since the control means is provided with the limit speed difference setting circuit, the limiter circuit and the current control circuit, the current of the drive motor of the bridle roll can be suppressed. it can. Further, the occurrence of slip flaws in the metal band can be prevented, and the tension of the metal band after cutting can be increased as compared with the time of cutting.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a schematic configuration of a tension control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a power supply of the drive motor shown in FIG.

FIG. 3 is a graph showing a relationship between a difference ΔV between a peripheral speed of a bridle roll and a traveling speed of a steel strip, and the number of slip flaws.

FIG. 4 is a block diagram showing an electrical configuration of the control device shown in FIG.

FIG. 5 shows the output of the limiter circuit shown in FIG. 4 and the speed deviation ΔR.
6 is a graph showing a relationship with the graph.

FIG. 6 is a flowchart illustrating a tension control method according to the present invention.

FIG. 7 is a flowchart for explaining a control method of the first tension control shown in FIG. 6;

8 is a flowchart for explaining a method of correcting a current deviation in the second tension control shown in FIG.

FIG. 9 is a graph showing changes in the tension of the steel strip on the exit side of the rolling mill and the circumferential speed of the bridle roll during the tension control.

FIG. 10 is a graph showing changes in the tension of the steel strip on the exit side of the rolling mill and the circumferential speed of the bridle roll during tension control in the prior art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tension control device 2 cold rolling mill 3 bridle roll 5 running cutting machine 6 winding machine 7 steel strip 9 tension detector 10 control device 11 drive motor 16 running speed detector 17 peripheral speed detector 18 current detector 19 cutting Point detector 20 Travel distance detector 23 Target tension setting circuit 24 Command tension setting circuit 25 Conversion circuit 26 First subtraction circuit 28 Incremental speed setting circuit 29 Command peripheral speed setting circuit 30 Second subtraction circuit 31 Limiter circuit 33 Limit speed difference setting Circuit 34 Current control circuit

Claims (3)

[Claims] A plurality of bridle rolls, a running cutter, and a winding machine are arranged in this order on a rolling mill exit side, and rolling is performed in a continuous rolling facility in which a running metal strip is cut and wound. In the method for controlling the tension of the metal strip on the machine exit side, the traveling speed of the metal strip on the exit side of the rolling mill is detected, the traveling distance of the cutting point of the metal band is detected, and in response to the traveling distance, the cutting point of the metal band is detected. During the traveling period from when the pre-cut position reaches the predetermined position on the upstream side of the running cutter to when the cut metal band is wound up again by the winding machine, the traveling speed of the detected metal band and each bridle roll are detected. A method for controlling the tension of the metal strip on the exit side of the rolling mill, wherein the difference from the peripheral speed of the metal strip is limited so as to avoid the occurrence of slip flaws in the metal strip. 2. A plurality of bridle rolls, a running cutter, and a winding machine are arranged in this order on a rolling mill outlet side, and tension is applied to the metal strip on the rolling mill outlet side by the bridle rolls and the winder. In the tension control device of the metal strip on the rolling mill exit side in the continuous rolling equipment in which continuous rolling is performed at a predetermined cutting point of the metal strip, the drive motor of each bridle roll is Running speed detecting means for detecting the running speed of the metal strip on the exit side of the rolling mill, the rotation speed of which is variable by the application of the control signal; and detecting the tension of the metal strip on the outlet side of the rolling mill. Tension detecting means, a peripheral speed detecting means for detecting a peripheral speed of each bridle roll, a control signal detecting means for detecting a control signal applied to a drive motor of each bridle roll, and a cutting means for detecting a cutting point of the metal strip. Break point detection means, travel distance detection means for detecting the travel distance of the cutting point of the metal strip starting from the installation position of the cut point detection means, and control signal generation means for providing a control signal to the drive motor, In response to the outputs of the traveling speed detecting means, the cutting point detecting means and the traveling distance detecting means, the traveling distance of the cutting point of the metal band is detected, and the cutting point of the metal band is set at a predetermined position on the upstream side of the cutting machine during traveling. In response to the output of the tension detecting means, the peripheral speed detecting means and the control signal detecting means during the traveling period from when the winding belt reaches the winding machine, the rotation speed of the drive motor of each bridle roll is adjusted to the speed of the metal belt. Control means for controlling the tension of the metal strip after cutting to a predetermined tension as soon as possible, while limiting the metal strip to a small size so as to avoid the occurrence of slip flaws. No Zhang The control device. 3. The target tension of a metal band shared by a bridle roll by subtracting a target tension of a metal band shared by a winder from a preset target tension of a metal band on a rolling mill exit side. And a target tension setting circuit for correcting the target tension of the metal band shared by the bridle roll based on the outputs of the target tension setting circuit and the tension detecting means, and obtaining a command tension of the metal band shared by the bridle roll. A setting circuit, a conversion circuit that converts the obtained command tension into a command current, and the control signal detection unit is a current detection unit, and the obtained command current is based on an output of the conversion circuit and the current detection unit. A first subtraction circuit for calculating a current deviation from the detected current; an incremental speed setting circuit for setting an increment of a peripheral speed of the bridle roll with respect to a traveling speed of the metal strip on the rolling mill exit side; A command peripheral speed setting circuit for obtaining a command peripheral speed of the bridle roll based on an output of the minute speed setting circuit; and a command peripheral speed and a detection circuit which are obtained based on outputs of the command peripheral speed setting circuit and the peripheral speed detecting means. A second subtraction circuit for obtaining a speed deviation from the speed; and a limiting range for the obtained speed deviation, wherein the occurrence of slip flaws in the metal band is avoided, and the tension of the metal band after cutting is larger than that at the time of cutting. A limit speed difference setting circuit that sets the speed difference to be set, a limiter circuit that limits the obtained speed deviation based on the outputs of the second subtraction circuit and the limit speed difference setting circuit, And the first
Based on the outputs of the subtraction circuit and the limiter circuit, the calculated current deviation is corrected to obtain a corrected current deviation, and during the period, the current of the bridle roll drive motor is adjusted so that the obtained corrected current deviation becomes zero. The tension control device for a metal strip on the exit side of a rolling mill according to claim 2, further comprising a current control circuit for controlling the tension.