JPH0775813A - Rolling mill tension control method - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a tension control method for a rolling mill capable of controlling tension with high precision while suppressing strip thickness variation. [Structure] Tension detectors SE11 to SE15 are arranged on the entrance sides of the first to fifth stands # 1 to # 5.
15 is connected to the tension control devices 51 to 55. The tension control devices 51 to 55 are connected to the pressure reduction position control devices 31 to 35 of the stand on the downstream side of the tension detectors SE11 to 15 and the respective tension detectors SE12 to SE12.
~ 15 upstream roll speed controller 61-64 and adder 71
~ 73 connected or not. Then, the tension control devices 51 to 55 respectively obtain the rolling position control amount and the roll speed control amount based on the proportional-integral calculation value using the deviation between the detection value of the tension detectors SE11 to 15 and the target value, and the rolling position control device is obtained. 31-35 and roll speed control device 61-64
~ The rolling positions of the fifth stands # 1 to # 5 and the roll speeds of the first to fourth stands # 1 to # 4 are simultaneously controlled.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for controlling the tension of rolled material in a rolling mill having a plurality of stands arranged in tandem.

[0002]

2. Description of the Related Art In a rolling mill having a plurality of stands arranged in tandem, when the tension acting on the rolled material changes,
Since the thickness of the product is not constant and the quality of the product is adversely affected, it is important to control this to be constant.

FIG. 5 is a block diagram showing an embodiment of a conventional tension control method for a rolling mill described in Japanese Patent Laid-Open No. 4-84613. In the figure, # 1 to # 5 are a pair of work rolls and a pair of work rolls. It is a 1st-5th stand provided with a pair of support rolls which support. The first to fifth stands # 1 to # 5 are arranged in tandem with a predetermined distance therebetween, and the strip S is rolled while being transported in the arrow direction in the drawing to manufacture a rolled material having a predetermined thickness. Rolling down devices 41 to 45 are connected to the support rolls of the stands # 1 to # 5, respectively, and the rolling down positions of the rolling down devices 41 to 45 are controlled by the rolling down position control devices 31 to 35. Drive motors 21 to 25 for driving the work rolls of the stands # 1 to # 5 are connected to the work rolls 21 to 25, respectively.
The rotation speed of is controlled by roll speed control devices 91 to 95.

Tension measuring devices SE11 to SE15 for measuring the tension of the strip S are arranged on the entrance sides of the first to fifth stands # 1 to # 5, respectively.
The tension measuring devices SE11 to SE14 arranged on the entrance side of No. 4 are connected to the tension control devices 81 to 84, and the tension control devices 81 to 84 measure the tensions between the first to fourth stands # 1 to # 4. A control command is given to the rolling position control devices 41 to 44 to obtain the target tension. Further, the tension measuring device SE15 arranged on the entrance side of the fifth stand # 5 is connected to the tension control device 85, and the tension control device 85 gives a control command to the roll speed control device 95 of the fourth stand # 4.

A thickness gauge 101 for detecting the thickness of the strip S is arranged on the exit side of the fifth stand # 5, and the thickness gauge 101 is connected to a thickness controller 102. Then, the thickness control device 102 directly controls the roll speed control device 93 so as to set the plate thickness of the strip S to a target value, and also gives a control command to the ratio setter 105 to obtain a control amount of a predetermined ratio, which is used as a roll. It is given to the speed control device 92, and further, a control command is given to the ratio setting device 105 and the ratio setting device 106 to obtain a control amount of a predetermined ratio, which is given to the roll speed control device 91. Further, the roll speed control devices 91, 92, 93 adjust the rotation speeds of the drive motors 21, 22, 23 to adjust the roll speeds of the first to third stands # 1 to # 3 to be successful (at the same ratio). .

In such a rolling mill, the tension measuring device SE11 ...
The tension of the strip S is measured at SE15, and the measured value is given to the tension control devices 81-85. The tension control devices 81-84 control the pressure reduction devices 41-44 by causing the reduction position control devices 31-34 to set the measured tension as a target value. In addition, the tension measuring device SE
Based on the tension of the strip S measured at 15, the tension controller 85 controls the roll speed controller 94 to set the tension of the strip S between the fourth stand # 4 and the fifth stand # 5 to a predetermined value. 4 Drive motor 24 of stand # 4 is controlled.

FIG. 17 is a block diagram showing another embodiment of the conventional tension control method for a rolling mill described in Japanese Patent Laid-Open No. 5-31517, in which the roll speed and the rolling position are simultaneously operated. The stand-out side plate thickness is controlled while the stand-in side tension is controlled. Figure 17 shows the third
It is shown when applied to the stand # 3. Also, in the figure, parts corresponding to those in FIG.

A tension measuring device SE is provided on the entrance side of the third stand # 3.
13 and a thickness gauge 300 on the exit side of the third stand # 3, respectively, and the tension T measured by the tension measuring device SE13 is measured.
_The plate thickness H _m3 measured by _b3 and the thickness gauge 300 is applied to the plate thickness tension controller 220. Further, the plate thickness tension control device 220 is given a speed V ₃ and a reduction position S ₃ from the drive motor 22 connected to the work roll of the second stand # 2 and the reduction device 43 of the third stand # ₃ , respectively. A speed controller 62 is connected to the drive motor 22, and the speed controller 62 controls the rotation speed of the drive motor 22 based on a speed command V _3ref given from the plate thickness tension controller 220. Also, the rolling down device 43
A reduction position control device 33 is connected to the pressure reduction position control device 33, and the reduction position control device 33 controls the reduction position of the reduction device 43 based on the reduction position command S _{3r ef} given from the plate thickness tension control device 220.

The plate thickness tension control device 220 is a tension measuring device SE13,
Thickness gauge 300, the tension T _b3 given respectively from the drive motor 22 and the screw down device 43, the thickness H _m3, based on the speed V ₃ and the pressing position S _3, optimal regulator control gain determined by the method ka11~ka23 , Kb11 to kb22 are used to output a _rolling position command S _3ref and a speed command V _3ref .

[0010]

[Equation 2]

FIG. 18 is a block diagram showing the structure of the plate thickness tension controller 220 of FIG. The plate thickness H _m3 read from the thickness gauge and the tension T _b3 read from the tension measuring device are given to the adders 221 and 222, respectively. The plate thickness H _m3 and the tension T _{b3 in} the past for a predetermined period from the memories 223 and 224 are also given to the adders 221 and 222, respectively, and the adders 221 and 222 add them and Multiply the result by 22
5, 227, 230 and 232 respectively. Also the tension T _b3
To the multipliers 226 and 231, and the reduction position S ₃ to the multipliers 228 and 23.
3 and the speed V ₃ is applied to the multipliers 229 and 234.

The multipliers 225, 226, 227, 228 and 229 are provided with control gains kb11, ka13, kb12, ka11 and ka12, respectively, and the multipliers 225, 226, 227 and 227 are provided.
, 228 and 229 are the addition result of the adder 221 and the control gain k.
b11 and tension T _b3 and control gain ka13 are added to the adder 222.
And the control gain kb12 are multiplied by the reduction position S ₃ and the control gain ka11 by the speed V ₃ and the control gain ka12, respectively, and the result is output to the adder 240. Then, the adder 240 adds them and outputs it as a _rolling position command S _3ref .

Control gains ka21, ka23, kb22, ka21, ka22 are provided to the multipliers 230, 231, 232, 233, 234, respectively, and the multipliers 230, 231, 232, 232 are provided.
, 233, 234 multiply the respective control gains by the addition result of the adder 221, the tension T _b3 , the addition result of the adder 222, the rolling position S ₃ or the speed V _3, and add the result to the adder 241.
Output to. Then, the adder 241 adds them and outputs them as a speed command V _3ref .

[0014]

[Patent Document 1] Japanese Patent Application Laid-Open No. Hei 4
In the conventional tension control method for a rolling mill described in Japanese Patent Publication No. -84613, for example, the rolling position of the fourth stand is controlled to control the tension between the third and fourth stands. The plate thickness on the delivery side fluctuates, which induces a tension fluctuation between the fourth and fifth stands. On the other hand, the roll speed of the fourth stand is controlled in order to control the tension between the fourth and fifth stands, but this induces the plate thickness variation on the fifth stand outlet side, so the fourth stand outlet side is controlled. There is a problem in that the plate thickness accuracy of the product is reduced together with the plate thickness fluctuation.

FIG. 6 is a graph showing the results of measuring the tension fluctuation width on the entry side of the fourth stand when the rolling position of the fourth stand is changed in a sinusoidal manner in a rolling mill equipped with five stands. The pressure reduction position of the fourth stand was changed in a sinusoidal manner by varying the frequency while keeping the amplitude constant. FIG. 7 is a graph showing the results of measuring the plate thickness fluctuation width on the delivery side of the fourth stand when the rolling position of the fourth stand is changed in a sinusoidal manner as in FIG. 6 and 7, the horizontal axis plots the frequency of the rolling position fluctuation on a logarithmic scale, and the vertical axis plots the gain of the tension fluctuation width or the plate thickness fluctuation width in dB.

As is apparent from FIG. 6, when the fluctuation of the pressure reduction position of the fourth stand was changed from around 0 Hz to 2 Hz, and the gain of the tension fluctuation width on the entrance side of the fourth stand was measured, it was found to be substantially the same in all measured ranges. It can be seen that a similar gain is obtained and the tension can be controlled. However, as is clear from FIG. 7, as the frequency of the reduction position increases, the variation range of the plate thickness on the delivery side of the fourth stand increases,
The plate thickness fluctuation width is maximum around 1 Hz.

On the other hand, in the method disclosed in Japanese Patent Laid-Open No. 4-84613, the roll speeds of the first to third stands are controlled to be successful in order to control the plate thickness on the delivery side of the final stand. FIG. 8 is a graph showing the results of measuring the fluctuation range of tension on the entrance side of the fourth stand when the roll speeds of the first to third stands are changed in a successive manner. Fluctuated. FIG. 9 shows FIG.
9 is a graph showing the results of measuring the width variation of the plate thickness on the delivery side of the fourth stand when the roll speeds of the first to third stands are changed in a similar manner to. 8 and 9 are both
The horizontal axis plots the roll speed fluctuation frequency on a logarithmic scale, and the vertical axis plots the tension fluctuation width or the plate thickness fluctuation width gain in dB.

As is clear from FIG. 8, the roll speed fluctuations of the first to third stands were changed from 0 Hz to 2 Hz, and the gain of the tension fluctuation width on the fourth stand entrance side was measured. A gain of about 10 dB higher than that in the case of the fluctuation of the rolling position shown in FIG. 6 is obtained in all ranges, and the fluctuation of the roll speed of the first to third stands strongly changes the tension on the entrance side of the fourth stand. I understand. Further, as is clear from FIG. 9, the roll speed fluctuations are substantially equal to each other in the fourth range from the low frequency region to the high frequency region.
The plate thickness fluctuation range on the stand-out side is generated, and the value of the plate thickness fluctuation range is about 15 to 25 dB higher than that in the case of fluctuation of the rolling position shown in FIG.

When the tension is controlled by controlling the rolling position in this way, the plate thickness varies greatly in the high frequency range. Further, when the plate thickness is controlled by controlling the roll speed, the fluctuation of the tension and the fluctuation of the plate thickness are large.

On the other hand, in the conventional tension control method for a rolling mill disclosed in Japanese Patent Laid-Open No. 5-31517, the strip thickness tension control device has a tension measuring device arranged at the entrance side of the stand and a tension measuring device at the exit side. The tension T _b and the plate thickness H _m are taken in from the arranged thickness gauge, and further the speed V and the reduction position S are obtained from the motor and the reduction device.
Uptake, pressing position command based on these values S _{re f}
Since it is necessary to calculate the speed command V _ref and the speed command V _ref , it takes a long time to calculate both commands, and the control cycle is approximately 0.02 seconds to 0.05 seconds. By the way, the reduction position control device and the speed control device control the operations of the reduction device and the motor in a control cycle of approximately 0.002 seconds to 0.005 seconds based on the given reduction position command S _ref and speed command V _ref . Therefore, there is a problem that the rolling position command S _ref and the speed command V _ref are not given to the rolling position control device and the speed control device at appropriate timing, and hunting occurs as follows.

FIG. 19 is a timing chart showing the control operation of the plate thickness tension control device. In the figure, A is the true actual value of the reduction position, and B is the reduction position recognized by the plate thickness tension control device. , And C respectively show outputs of the rolling position command. The time t ₀ , t ₁ , ... Is the control timing time of the plate thickness tension control device, and its interval is approximately 0.02 seconds.

When the actual value of the reduction position decreases from the reference as at times t _{0 to} t _{2 in} FIG. 19A, it is increased by the operation of the reduction control device to return it to the reference. In the process, the pressing position at time t ₁ is taken in the thickness tension controller, as shown in FIG. 19C, pressure position command to increase the pressing position on the basis of the pressing position at time t ₁ is calculated, it There during is time t ₂ ~ time t ₃ output at time t ₂ is controlled by the pressure position command. Therefore, the rolling position is returning to the reference at time t ₂ , but from time t ₂
At time t ₃ , the rolling position is increased beyond the reference.

Since the actual value of the rolling position is smaller than the reference value at time t ₂ , the plate thickness tension control device calculates a rolling position command for increasing the rolling position and outputs it at time t ₃ .
Therefore, the actual value of the rolling position further increases from time t ₃ to time t ₄ . In this way, since the delay between the reduction position capture in the plate thickness tension control device and the output of the reduction position command based on it is large, overshoot occurs and hunting occurs.

The present invention has been made in view of the above circumstances, and an object of the present invention is to control the rolling position and the roll speed at the same time so that the control amounts become the required amounts. It is an object of the present invention to provide a tension control method for a rolling mill capable of controlling the tension with high accuracy while suppressing the strip thickness variation. Further, by obtaining the control amounts of the rolling position and the roll speed based on the preset control gain and the deviation of the tension, the time required for calculating both control amounts is shortened, and the rolling position control and the roll speed control are performed. Another object is to provide a tension control method for a rolling mill that shortens the cycle and suppresses hunting.

[0025]

A tension control method for a rolling mill according to a first aspect of the present invention comprises a method for controlling a tension of a rolled material rolled by rolling rolls of the stand of a rolling mill having a plurality of stands arranged in tandem, In order to eliminate the deviation by using a tension measuring device installed between the stands and using a deviation between the measured value and a target value and a proportional-plus-integral calculation value obtained based on the deviation, reduction of the rolling roll is performed. In a tension control method for a rolling mill that controls a position and a roll speed, based on a stress target value of a load target value for the reduction of the stand and a stress target value of the tension, the degree of influence of the stress target value on the load target value is represented. 1 parameter, and the influence of the stress target value on the advance rate target value based on the advance rate target value and the stress target value for the roll speed of the stand Is determined in advance, the proportional-plus-integral calculation value and the first parameter are used to obtain a control amount of the rolling position of the stand on the downstream side of the tension measuring instrument, and the control amount is calculated using the control amount. While controlling the rolling position of the stand, using the proportional-plus-integral calculated value and the second parameter, the control amount of the roll speed of the stand on the upstream side or the downstream side of the tension measuring device is obtained, and the control amount is calculated by the control amount. The roll speed of the stand is controlled.

A tension control method for a rolling mill according to the second invention is
The tension of the rolled material rolled by the rolling rolls of the stand of the rolling mill having a plurality of stands arranged in tandem, is measured by a tension measuring device installed between the stands, and the measured value and the target value. In order to eliminate the deviation using the deviation and the proportional-plus-integral calculation value obtained based on the deviation, in the tension control method of the rolling mill for controlling the rolling position and the roll speed of the rolling roll, the proportional-integral calculation value and rolling Using the first control gain preset according to the conditions, the control amount of the pressure reduction position of the stand on the downstream side of the tension measuring device is obtained, and the pressure reduction position of the stand is controlled by the control amount, Using the proportional control value and the second control gain preset according to the rolling conditions, obtain the control amount of the roll speed of all stands on the upstream side or the downstream side of the tension measuring device, And controlling the roll speed of the stands in the control amount.

A tension control method for a rolling mill according to the third invention is
In the second invention, the first control gain G ₁ and the second control gain G ₂ are determined by the following equations.

[Equation 3]

[0028]

FIG. 2 shows a fourth embodiment of a rolling mill equipped with five stands.
FIG. 4 is a graph showing the results of measuring the tension fluctuation on the fourth stand entry side when the fluctuation of the rolling position of the stand and the successful fluctuation of the roll speeds of the first to third stands are simultaneously performed stepwise, and FIG. Indicates the plate thickness variation on the delivery side of the fourth stand in that case. 2 and 3, the horizontal axis plots the roll speed fluctuation frequency on a logarithmic scale, and the vertical axis plots the tension fluctuation width or the plate thickness fluctuation width gain in dB.

As is apparent from FIG. 2, the fluctuation of the rolling position of the fourth stand and the fluctuation of the roll speed of the first to third stands are simultaneously changed from a low frequency to 2 Hz, so that the tension fluctuation width on the entrance side of the fourth stand is increased. When the gain of was measured, a gain of approximately 10 dB was obtained in the entire measured range, and it can be seen that sufficient tension control can be performed. Further, as is clear from FIG. 3, the plate thickness fluctuation width on the delivery side of the fourth stand increases slightly as the frequency increases, but the reduction position control and the first to third stands shown in FIGS. The fluctuation range is smaller than that when the roll speed is controlled separately. Therefore, appropriate tension control can be performed while suppressing the influence on the plate thickness variation.

In this way, when the control of the rolling position and the control of the roll speed are simultaneously performed so that both control amounts become the required amounts, the load is determined based on the load target value for the roll reduction and the stress target value of the tension. A first parameter that represents the degree of influence of the stress target value on the target value is determined in advance, and based on the advance ratio target value and the stress target value for the roll speed of the stand, the stress target that affects the advance ratio target value. By presetting the second parameter indicating the degree of influence of the value, the control amount of the rolling position and the control amount of the roll speed can be directly obtained from the deviation between the measured value of the tension and the target value.

In the second and third aspects of the invention, the control amount of the rolling position and the control amount of the roll speed are set using the preset first control gain and second control gain and the deviation of tension. Since both are obtained, both controlled variables can be calculated quickly and highly accurately using the measured values of tension.

FIG. 13 is a graph showing the effect on the material to be rolled when the rolling position of the fourth stand is changed stepwise in a five-stand tandem mill.
Is the tension between the third and fourth stands, (b) is the third stand outlet side plate thickness, (c) is the fourth stand outlet side plate thickness,
(D) has shown the 5th stand delivery side board thickness, respectively.
In Figure 13, the roll gap of the 4th stand is plus 100
It is operated so that it becomes μm.

FIG. 14 is a graph showing the effect on the material to be rolled when the roll speeds of the first to third stands are changed stepwise so as to be successful in the above-mentioned tandem mill. Similarly, (a) is the third
~ The tension between the fourth stands, (b) shows the third stand outlet side plate thickness, (c) shows the fourth stand outlet side plate thickness, and (d) shows the fifth stand outlet side plate thickness. In Figure 14,
The roll speed of the first to third stands is operated to be plus 5%.

As is apparent from FIG. 13, when the pressing position of the fourth stand is operated to be plus 100 μm, the third stand
~ Tension between the 4th stand is corrected by 5tf,
A deviation of plus 20 μm occurs in the stand outlet side plate thickness. Further, a deviation in the minus direction occurs in the output side plate thickness of the third stand and the fifth stand. On the other hand, as is apparent from FIG. 14, when the roll speed of the first to third stands is operated to be plus 5%, the tension between the third to fourth stands is corrected by minus 3 tf, and the fourth stand exit side plate thickness is corrected. Plus 40 μm
Deviation occurs. From these things, for example, by operating the rolling position of the fourth stand in the positive direction and operating the roll speed of the first to third stands in the negative direction, the tension between the third to fourth stands is increased in the positive direction. It is possible to suppress the fluctuation by canceling the fluctuation of the fourth stand outlet side plate thickness and correcting the fluctuation.

FIG. 15 is a graph showing the effect on the material to be rolled when the rolling position of the fourth stand and the successive roll speeds of the first to third stands are changed stepwise at the same time in a 5-stand tandem mill. And
(A) shows the tension between the third and fourth stands, and (b) shows the third tension.
Stand stand-out side plate thickness, (c) shows the fourth stand stand-out side plate thickness, and (d) shows the fifth stand stand-out side plate thickness, respectively. In Figure 15, the roll gap of the 4th stand is plus.
At the same time, the roll speeds of the first to third stands are set to -4% by 100 μm.

As is apparent from FIG. 15, the roll gap of the fourth stand is set to be plus 100 μm, and
-By operating the roll speed of the 3rd stand at minus 4% at the same time, the tension between the 3rd and 4th stands is corrected by + 14tf, but the deviation of the thickness of the 4th stand from the exit side is only 4μm. It has not occurred. Such characteristics were similar at a plurality of reduction position levels and roll speed levels shown in Table 1 below.

[0037]

[Table 1]

Therefore, without using the actual values of the rolling position and the roll speed, the rolling position and the roll speed should be simultaneously changed based on the measured tension deviation so that the rolling deviation and the roll speed become appropriate control amounts in order to eliminate them. Thus, the tension can be controlled while suppressing the plate thickness variation, and both control amounts can be calculated quickly.

The first control gain G ₁ and the second control gain G ₂ are used in the calculation of the control amount of the rolling position and the control amount of the roll speed. These control gains can be obtained by the following formula based on the actual machine test or rolling theory. This makes it possible to calculate the control amounts of the rolling position and roll speed with high accuracy.

[0040]

[Equation 4]

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing an embodiment of the method of the present invention. In the figure, # 1 to # 5 are first to fifth stands equipped with a pair of work rolls and a pair of support rolls supporting the work rolls. The first to fifth stands # 1 to # 5 are arranged in tandem with a predetermined distance therebetween, and the strip S is rolled while being transported in the arrow direction in the drawing to manufacture a rolled material having a predetermined thickness. Rolling down devices 41 to 45 are connected to the supporting rolls of the stands # 1 to # 5, respectively.
Rolling-down position control devices 31 to 35 for controlling this are connected to 45. Further, drive motors 21 to 25 for driving the work rolls of the stands # 1 to # 5 are connected to the work rolls. The drive motors 21 to 25 control roll speed control devices 61 to 25, respectively.
65 are connected respectively. In addition, the roll speed controller 61
Adders 71-73 are connected to 63, respectively.

Tension measuring devices SE11 to SE15 for measuring the tension of the strip S are arranged on the entrance sides of the respective stands # 1 to # 5, and the tension measuring devices SE11 to SE15 are tension control devices.
51 to 55 are connected respectively. The tension control devices 51 to 55 are connected to the pressure reducing position control devices 31 to 35 of the stand on the downstream side of the tension measuring devices SE11 to SE15, respectively, and the total roll speed control on the upstream side of each of the tension measuring devices SE12 to SE15 is performed. Device 61
˜64 and adders 71 to 73 or not. That is, the tension control devices 52 to 55 are added to the adder 71,
Tension control devices 53 to 55 are connected to the adder 72, tension control devices 54 and 55 are connected to the adder 73, and a tension control device 55 is connected to the roll speed control device 64.

Next, a method of controlling the tension will be described. The tension measuring devices SE11 to SE15 measure the tension of the strip S and apply it to the tension control devices 51 to 55. A target value of tension is given to the tension control devices 51 to 55 in advance, the deviation between the target value and the measured value is obtained, and the proportional-integral calculation described later is performed using the obtained deviation. Then, the tension control devices 51 to 55 calculate the reduction position control amount in the stand to be controlled based on the calculated value, and give the result to the reduction position control devices 31 to 35. Further, the tension control devices 52 to 55 calculate the roll speed control amount in the stand to be controlled based on the calculation result, and give the result to the adders 71 to 73, and the adders 71 to 73 give the added value. It is given to the roll speed control devices 61 to 63. Further, the tension control device 55 gives the calculated roll speed control amount to the roll speed control device 64.

The rolling-down position control devices 31 to 35 and the roll speed control devices 61 to 64 control the working roll rolling position and the drive motor 21 by the rolling down devices 41 to 45 so as to obtain the given rolling position control amount and roll speed control amount. Control the roll speed of the work roll by ~ 24. The roll speed control device 65 controls the drive motor 25 so that the roll speed of the fifth stand # 5 becomes the target speed.

Next, a method of obtaining the rolling position control amount and the roll speed control amount will be described. A tension control device to which a tension measuring device SE13, which is now arranged on the entrance side of the third stand # 3, is connected
Focus on 53. The tension control device 53 obtains the deviation ΔT ₃ between the measured value from the tension measuring device SE13 and the target value, calculates the proportional-plus-integral by the following equation (1), and then calculates the third stand # by the following equation (2). The rolling position control amount ΔS ₃ of ₃ is calculated.

[0046]

[Equation 5]

[0047]

[Equation 6]

At the same time, the second star is calculated by the following equation (3).
Roll # 2 roll speed control amount ratio ΔV ₂/ V₂To calculate
Together with the same, roll speed control of the first stand # 1
Quantity ratio ΔV₁/ V₁To calculate.

[0049]

[Equation 7]

Next, the results of a comparative test between the method of the present invention and the conventional method will be described. Strip width 60
Using 0 mm low carbon steel, rolling was carried out in a pass schedule as shown in Table 2 by a rolling mill equipped with five stands.

[0051]

[Table 2]

FIG. 4 is a graph showing the results of the method of the present invention. FIG. 4 (a) shows a step-like change of the rolling position of the fourth stand and a successful change of the roll speeds of the first to third stands at the same time. 4B shows the change in tension on the entrance side of the fourth stand, and FIG. 4B shows the change in plate thickness on the exit side of the fourth stand. 10 and 11 are graphs showing the results of the conventional method, and FIG. 10 (a) shows the tension fluctuation on the fourth stand entry side when the rolling position of the fourth stand is changed stepwise. (B) In that case, Fig. 11 (a) shows the variation of the plate thickness on the exit side of the fourth stand, and Fig. 11 (a) shows the variation of the tension on the entrance side of the fourth stand when the roll speeds of the first to third stands are stepwise changed. 11 (b) shows the plate thickness variation on the delivery side of the fourth stand in that case.

As is apparent from FIG. 4, in the method of the present invention, the tension on the fourth stand entry side quickly converges to the target value, and the plate thickness on the fourth stand exit side hardly fluctuates. On the other hand, as is apparent from FIGS. 10 and 11, in the conventional method, the tension on the entry side of the fourth stand quickly converges to the target value when the rolling position and the roll speed are changed. The plate thickness on the side fluctuates significantly.

FIG. 12 is a block diagram showing another embodiment of the present invention, which is applied to the fourth stand # 4. On the entry side of the 4th stand # 4, a tension measuring device SE
14 is arranged, and the tension deviation e ₄ measured by the tension measuring device SE14 is given to the proportional-plus-integral computing device PI201. Proportional-integral calculation unit PI201 has directed the tension modifying output quantity c ₄ by performing a proportional integral operation to the tension deviation e _4, give it the adder 202. The adder 202 is also provided with the tension correction output amount c ₄ used for the immediately preceding control timing from the storage device 203, and the adder 202 adds the two to obtain a new tension correction output amount c ₄ . The data is output to the storage device 203 and stored therein, and is also given to the multipliers 205 and 206.

The multipliers 205 and 206 are respectively supplied with a control gain G ₁ for rolling position adjustment and a control gain G ₂ for roll speed adjustment from the control gain setting device 210 according to the rolling conditions of the material S to be rolled. It is like this.

[0056]

[Equation 8]

Then, the multiplier 204 gives the output from the adder 202.
Tension correction output amount c_FourControl gain G₁And multiply
It is given to the reduction position control device 34 to lower the pressure of the reduction device 44.
Control the position. Also, the multiplier 205 is
Given tension correction output amount c _FourControl gain G₂Multiply by
The first stand # 1, second stand # 2 and
Control drive motors 21, 22, 23 connected to 3 stand # 3
The roll speed controller 61, 62, 63 is driven by
Controls the rotation speed of the dynamic motors 21, 22, 23.

As described above, the control gain G ₁ and the control gain G ₂ are determined according to the rolling conditions of the material to be rolled. As shown in Table 3 below, the control gain G ₁ and the control gain G ₂ were obtained for four types of rolled materials having different sheet widths, base sheet thicknesses, and finished sheet thicknesses. The result is shown in FIG. 16 as a vector. As shown in FIG. 16, the control gain G ₁ has a positive value and the control gain G ₂ has a negative value in any case. When the plate width is wide (I, K), the value of the control gain G ₁ is large, and the rolling position control is the main function. Conversely, when the plate width is narrow (H, J), the roll speed control is the main function. Become.

[0059]

[Table 3]

Next, the result of the comparison test will be described. Table 4 shows the comparison results, and shows the results regarding the minimum value of the control cycle, the average tension fluctuation width, and the average plate thickness fluctuation width. In the table, the conventional example 1 is described in the above-mentioned JP-A-4-84.
The method described in Japanese Patent No. 613 and the conventional example 2 are disclosed in
This is the result of carrying out the method described in Japanese Patent Publication No. 5-31517. The respective values are represented by relative values with the minimum value of the control cycle of the second conventional example, the average tension fluctuation width, and the average plate thickness fluctuation width being 1.00.

[0061]

[Table 4]

As is clear from Table 4, since the method of the present invention can rapidly calculate the control amount of the rolling position and the control amount of the roll speed, the control cycle can be shortened to 1/2 or less as compared with the conventional example 2. It was Further, in the method of the present invention, both the average tension fluctuation range and the average plate thickness fluctuation range are suppressed more than in the conventional example 1 and the conventional example 2, and the control for keeping the tension constant while suppressing the plate thickness fluctuation is performed with high accuracy. I understand that.

In this embodiment, the tension control device
Although it is arranged to control the rolling position control device of the downstream stand and the roll speed control devices of all the upstream stands that are adjacent to the tension measuring device, the present invention is not limited to this, and the tension measuring device is not limited to this. Even if the rolling position control devices of the adjacent stands on the downstream side and the roll speed control devices of all the stands on the downstream side are controlled, the effect is the same.

[0064]

As described in detail above, in the tension control method for a rolling mill according to the first aspect of the present invention, since the tension can be controlled with high precision while suppressing the variation of the strip thickness, the strip thickness accuracy of the product is improved. Product quality is improved.

Further, in the tension control method for a rolling mill according to the second and third aspects of the present invention, the control amount of the rolling position and the control amount of the roll speed can be quickly calculated, so that the control cycle can be shortened. The present invention has excellent effects such as improved control accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a method of the present invention.

FIG. 2 shows the results of measuring the tension fluctuation on the entrance side of the fourth stand when the fluctuation of the rolling position of the fourth stand and the successful fluctuations of the roll speeds of the first to third stands are simultaneously performed stepwise. It is a graph.

FIG. 3 shows the results of measuring the plate thickness fluctuation on the delivery side of the fourth stand when the fluctuation of the roll-down position of the fourth stand and the successful fluctuations of the roll speeds of the first to third stands are simultaneously performed stepwise. It is a graph shown.

FIG. 4 is a graph showing the results of the method of the present invention.

FIG. 5 is a block diagram showing an embodiment of a conventional tension control method for a rolling mill.

FIG. 6 is a graph showing a result of measuring a tension fluctuation width on the entrance side of the fourth stand when the rolling position of the fourth stand is changed in a sine wave shape in a rolling mill provided with five stands.

FIG. 7 is a graph showing a result of measuring a plate thickness variation width on the delivery side of the fourth stand when the rolling position of the fourth stand is varied in a sine wave shape.

FIG. 8 is a graph showing the results of measuring the tension fluctuation width on the entrance side of the fourth stand when the roll speeds of the first to third stands are changed with succession.

FIG. 9 is a graph showing the results of measuring the width variation of the plate thickness on the delivery side of the fourth stand when the roll speeds of the first to third stands are changed with succession.

FIG. 10 is a graph showing the results of the conventional method.

FIG. 11 is a graph showing the results of the conventional method.

FIG. 12 is a block diagram showing another embodiment of the present invention.

FIG. 13 is a graph showing the effect on the material to be rolled when the rolling position of the fourth stand is changed to a step in a 5-stand tandem mill.

FIG. 14 is a tandem mill with five stands, where the first to
It is a graph which shows the influence which it has on a rolling material, when the roll speed of a 3rd stand is changed in steps so that it may become successive.

FIG. 15 is a graph showing the effect on the material to be rolled when the rolling position of the fourth stand and the successive roll speeds of the first to third stands are changed stepwise at the same time in a 5-stand tandem mill.

FIG. 16 is a vector diagram showing the results of obtaining control gain G ₁ and control gain G ₂ for four types of rolled materials having different plate widths, base material plate thicknesses, and finished plate thicknesses.

FIG. 17 is a block diagram showing another embodiment of the conventional tension control method for a rolling mill.

18 is a block diagram showing a configuration of the plate thickness tension control device of FIG.

FIG. 19 is a timing chart showing a control operation of the plate thickness tension control device.

[Explanation of Codes] 1-5 Stand 11-15 Tension measuring device 21-25 Drive motor 31-35 Rolling down position control device 41-45 Rolling down device 51-55 Tension control device 61-65 Roll speed control device 71-73 Adder 201 Proportional Integral Computation Device 202 Adder 203 Storage Device 204 Multiplier 205 Multiplier 210 Control Gain Setting Device S Strip

Claims (3)

[Claims] 1. The tension of a rolled material rolled by a rolling roll of the stand of a rolling mill having a plurality of stands arranged in tandem is measured by a tension measuring device installed between the stands, and the measurement is performed. In order to eliminate the deviation by using the deviation between the value and the target value and the proportional-plus-integral calculation value obtained based on the deviation, in the tension control method of the rolling mill for controlling the rolling position and the roll speed of the rolling roll, the stand Based on the load target value for the reduction of the load and the stress target value of the tension, a first parameter indicating the degree of influence of the stress target value on the load target value is determined in advance, and an advanced rate target value for the roll speed of the stand. And a second parameter indicating the degree of influence of the stress target value on the advanced ratio target value is determined in advance based on the stress target value, and the proportional integral Using the calculated value and the first parameter, the control amount of the rolling position of the stand on the downstream side of the tension measuring device is determined, and the rolling position of the stand is controlled by the control amount, and the proportional-plus-integral calculated value is obtained. And the second parameter, the control amount of the roll speed of the stand on the upstream side or the downstream side of the tension measuring device is obtained, and the roll speed of the stand is controlled by the control amount. Machine tension control method. 2. The tension of a rolled material rolled by rolling rolls of the stand of a rolling mill having a plurality of stands arranged in tandem is measured by a tension measuring device installed between the stands, and the measurement is performed. In order to eliminate the deviation by using the deviation between the value and the target value and the proportional-plus-integral calculation value obtained based on the deviation, in the tension control method of the rolling mill that controls the rolling position and the roll speed of the rolling roll, the proportional Using the integral calculation value and the first control gain preset according to the rolling conditions, the control amount of the rolling position of the stand on the downstream side of the tension measuring device is obtained, and the rolling position of the stand is determined by the control amount. And controlling the roll speed of the stand on the upstream side or the downstream side of the tension measuring device by using the proportional-plus-integral calculated value and the second control gain preset according to the rolling condition. Determine the amount, tension control method of a rolling mill, characterized by controlling the roll speed of the stands at the control amount. 3. The tension control method for a rolling mill according to claim 2, wherein the first control gain G ₁ and the second control gain G ₂ are determined by the following equation. [Equation 1]