JP3344092B2 - Rolling machine tension control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the tension of a 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 a rolled material changes,
Since the thickness of the product is not constant and adversely affects the quality of the product, it is important to control the thickness constant.

FIG. 5 is a block diagram showing an embodiment of a conventional method for controlling the tension of a rolling mill described in Japanese Patent Application Laid-Open No. 4-84613. In FIG. And a first to a fifth stand including a pair of support rolls for supporting the first and second rolls. The first to fifth stands # 1 to # 5 are arranged in tandem with a predetermined distance therebetween, and roll while transferring the strip S in the direction of the arrow in the figure to produce a rolled material having a predetermined thickness. The pressing rolls 41 to 45 are respectively connected to the support rolls of the stands # 1 to # 5, and the pressing positions of the pressing units 41 to 45 are controlled by the pressing position control units 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.
Is controlled by roll speed controllers 91-95.

On the entry sides of the first to fifth stands # 1 to # 5, tension measuring devices SE11 to SE15 for measuring the tension of the strip S are arranged, respectively, and the first to fourth stands # 1 to # 5 are arranged.
4 are connected to tension control devices 81 to 84, and the tension control devices 81 to 84 measure each tension between the first to fourth stands # 1 to # 4. Control commands are given to the rolling-down position control devices 41 to 44 so as to obtain the target tension. The tension measuring device SE15 disposed 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 disposed 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 in order to set the plate thickness of the strip S to the target value. The control amount 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. The roll speed controllers 91, 92 and 93 adjust the rotational speeds of the drive motors 21, 22 and 23 to adjust the roll speeds of the first to third stands # 1 to # 3 successively (simultaneously by the same ratio). .

In such a rolling mill, tension measuring devices SE11 to SE11 are used.
In SE15, the tension of the strip S is measured, and the measured value is given to the tension controllers 81 to 85. The tension control devices 81 to 84 control the pressure reduction devices 41 to 44 by controlling the pressure reduction position control devices 31 to 34 so that the measured tension becomes the target value. Also, 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. The drive motor 24 of the four stand # 4 is controlled.

FIG. 17 is a block diagram showing another embodiment of the conventional method for controlling the tension of a rolling mill described in Japanese Patent Application Laid-Open No. 5-31517, in which the roll speed and the rolling position are simultaneously operated. The thickness of the stand exit side plate is controlled while controlling the stand entrance side tension. FIG. 17 shows the third
The case where the present invention is applied to the stand # 3 is shown. In the figure, the portions corresponding to those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

[0008] 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.
_The thickness _Hm3 measured by _b3 and the thickness gauge 300 is _supplied to the thickness tension controller 220. Further, the plate thickness tension control device 220 receives the speed V ₃ and the pressing position S ₃ from the driving motor 22 connected to the work roll of the second stand # 2 and the pressing 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. In addition, 43
It is Yes the connected pressing position control device 33, the rolling position control device 33 controls the pressing position of the screw down device 43 based on the pressing position command S _{3r ef} given from a thickness of the tension control device 220.

The sheet 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, and outputs a _{rolling- down} position command _S3ref and a speed command _V3ref .

[0010]

(Equation 2)

FIG. 18 is a block diagram showing the configuration of the plate thickness tension control device 220 shown in FIG. Read from read from the thickness gauge thickness H _m3 and tensiometer tension T _b3 is supplied to each of the adders 221, 222. The adders 221 and 222 are also provided with the plate thickness H _m3 and the tension T _b3 for each control cycle in the past of a predetermined period from the memories 223 and 224, respectively. Multiplier result 22
5, 227, 230 and 232 respectively. In addition, tension T _b3
Is provided to the multipliers 226 and 231, and the rolling down position S ₃ is provided to the multipliers 228 and 23.
3, the speed V ₃ is provided to multipliers 229 and 234.

The multipliers 225, 226, 227, 228, and 229 are provided with control gains kb11, ka13, kb12, ka11, and ka12, respectively.
, 228 and 229 are the addition result of the adder 221 and the control gain k
b11, the tension T _b3 and the control gain ka13,
The addition result and the control gain Kb12, the the pressing position S ₃ and control gain Ka11, the the velocity V ₃ and the control gain ka12 multiplied, and outputs the result to the adder 240. Then, the adder 240 adds them and outputs them as the _rolling-down position command S _3ref .

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

[0014]

However, Japanese Patent Laid-Open No.
In the conventional method for controlling the tension of a rolling mill described in JP-A-84613, the rolling position of the fourth stand is controlled for controlling the tension between the third and fourth stands, for example. The thickness of the sheet on the delivery side fluctuates, which induces a fluctuation in tension 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. However, this causes a thickness variation on the exit side of the fifth stand. In addition, there is a problem that the thickness accuracy of the product is reduced in accordance with the variation in the thickness.

FIG. 6 is a graph showing the results of measuring the width of tension fluctuation on the entrance side of the fourth stand when the rolling position of the fourth stand is sinusoidally varied in a rolling mill having five stands. The rolling position of the fourth stand was varied sinusoidally by varying the frequency while keeping the amplitude constant. FIG. 7 is a graph showing the result of measuring the thickness variation width on the exit side of the fourth stand when the rolling position of the fourth stand is changed in a sine wave shape 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 thickness fluctuation width in dB.

As is apparent from FIG. 6, the fluctuation of the rolling 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 can be seen that the same gain is obtained and the tension can be controlled. However, as is clear from FIG. 7, the fluctuation of the rolling position is such that as the frequency becomes higher, the width of the plate thickness fluctuation on the exit side of the fourth stand becomes larger,
At around 1 Hz, the thickness variation width becomes maximum.

On the other hand, in the method described in Japanese Patent Application Laid-Open No. 4-84613, the roll speeds of the first to third stands are controlled successively in order to control the sheet thickness on the exit side of the final stand. FIG. 8 is a graph showing the result of measuring the tension fluctuation width on the fourth stand entrance side when the roll speeds of the first to third stands are changed fluctuately. The frequency is variously changed while keeping the amplitude constant. Fluctuated. FIG. 9 shows FIG.
It is a graph which shows the result of having measured the thickness variation width | variety of the 4th stand exit side when changing the roll speed of a 1st-3rd stand similarly to FIG. 8 and 9 together
The horizontal axis plots the frequency of the roll speed 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. 8, the fluctuation of the roll speed of the first to third stands was changed progressively 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. In all ranges, a gain approximately 10 dB higher than the case due to the variation of the rolling position shown in FIG. 6 is obtained, and the variation in the roll speed of the first to third stands strongly varies the tension on the entrance side of the fourth stand. You can see that. Further, as is apparent from FIG. 9, the fluctuation of the roll speed is almost the same from the low frequency range to the high frequency range.
The thickness variation width on the stand exit side was generated, and the value of the thickness variation width was approximately 15 to 25 dB higher than that due to the variation of the rolling position shown in FIG.

When the tension is controlled by controlling the rolling position as described above, the thickness variation is large in a high frequency range. Further, when the sheet thickness is controlled by controlling the roll speed, the fluctuation of the tension and the fluctuation of the sheet thickness are large.

On the other hand, in the conventional tension control method for a rolling mill described in Japanese Patent Application Laid-Open No. 5-31517, a thickness tension control device is provided with a tension measuring device disposed on the entrance side of the stand and a tension measurement device disposed on the exit side. captures the tension T _b and plate thickness H _m from the placed thickness gauge, further velocity V and pressing position S from the motor and screw down device
Uptake, pressing position command based on these values S _{re f}
Since it is necessary to calculate the speed command _Vref and the speed command _Vref , it takes a long time to calculate both commands, and the control cycle is approximately 0.02 to 0.05 seconds. Meanwhile, the rolling-down position control device and the speed control device control the operations of the rolling-down device and the motor in a control cycle of approximately 0.002 to 0.005 seconds based on the given rolling-down position command _Sref and speed command _Vref . For this reason, there is a problem that the rolling position command S _ref and the speed command V _ref are not provided 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 sheet thickness tension control device. In FIG. 19, A indicates the true actual value of the reduction position, and B indicates the reduction position recognized by the thickness tension control device. And C indicate the output of the rolling-down position command. t ₀ , t ₁ ,... are control timing times of the plate thickness tension control device, and the interval is approximately 0.02 seconds.

When the actual value of the rolling position decreases from the reference as shown at times t _{0 to} t _{2 in} FIG. 19A, the actual value is increased to return to the reference by the operation of the rolling control device. 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 time t ₂ the pressing position is getting back to the reference, but the time t ₂ ~
At time t ₃ pressing position is increased beyond a reference.

At time t ₂ , since the actual value of the rolling position is smaller than the reference value, the thickness tension controller calculates a rolling position command for increasing the rolling position and outputs it at time t ₃ .
Therefore the actual value of the pressing position for a time t ₄ from the time t ₃ is further increased. As described above, since the delay between the taking in of the rolling-down position in the plate thickness tension control device and the output of the rolling-down position command based thereon is large, overshoot occurs and hunting occurs.

The present invention has been made in view of such circumstances, and an object of the present invention is to perform control of a rolling position and control of a roll speed at the same time so that the control amount becomes a required amount. 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 thickness variation. Further, by calculating the control amounts of the roll-down position and the roll speed based on the deviation of the control gain and the tension set in advance, the time required for calculating both control amounts is reduced, and the control of the roll-down position and the control of the roll speed are reduced. Another object of the present invention is to provide a method for controlling the tension of a rolling mill that shortens the cycle and suppresses hunting.

[0025]

According to a first aspect of the present invention, there is provided a method for controlling the tension of a rolling mill, comprising the steps of: Measured by a tension measuring instrument installed between the stands, and using a proportional-integral calculation value obtained based on the deviation between the measured value and the target value and the deviation, to eliminate the deviation, the rolling reduction of the rolling roll. In a tension control method for a rolling mill that controls a position and a roll speed, a load target value for the reduction of the stand and a stress target value of the tension, based on a target stress value of the tension, indicating a degree of influence of the target stress value on the target load value. The effect 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. Is determined in advance, and the control amount of the rolling-down position of the stand on the downstream side of the tension measuring device is obtained using the proportional-integral calculation value and the first parameter. While controlling the rolling position of the stand, 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 using the proportional integral calculation value and the second parameter, and the control amount is used. The roll speed of the stand is controlled.

According to a second aspect of the present invention, there is provided a method for controlling a tension of a rolling mill.
The tension of the rolled material to be 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 by using the deviation and the proportional integral operation value obtained based on the deviation, in a tension control method for a rolling mill for controlling a rolling position and a roll speed of the rolling roll, the proportional integral operation value and the rolling Using a first control gain preset according to the conditions, a control amount of the roll-down position of the stand on the downstream side of the tension measuring device is obtained, and the roll-down position of the stand is controlled by the control amount, Using the proportional integral calculation value and a second control gain preset according to the rolling conditions, the control amount of the roll speed of all stands on the upstream or downstream side of the tension measuring device is determined, And controlling the roll speed of the stands in the control amount.

According to a third aspect of the present invention, there is provided a tension control method for a rolling mill.
In the second invention, the first control gain G ₁ and the second control gain G ₂ are determined by the following equation.

(Equation 3)

[0028]

FIG. 2 shows a fourth rolling mill having five stands.
FIG. 3 is a graph showing the results of measuring the tension fluctuation on the entrance side of the fourth stand when the fluctuation of the rolling position of the stand and the successive fluctuation of the roll speed of the first to third stands are simultaneously performed, and FIG. Indicates the thickness variation on the exit side of the fourth stand in that case. In both FIGS. 2 and 3, the horizontal axis plots the frequency of the roll speed fluctuation on a logarithmic scale, and the vertical axis plots the gain of the tension fluctuation width or the thickness fluctuation width 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 to change the tension fluctuation width on the entrance side of the fourth stand. When the gain was measured, a gain of approximately 10 dB was obtained in the entire measured range, and it was found that sufficient tension control could be performed. Also, as is clear from FIG. 3, although the thickness variation width on the exit side of the fourth stand slightly increases as the frequency increases, the control of the rolling-down position shown in FIGS. 7 and 9 and the control of the first to third stands are performed. The fluctuation range is smaller than when the roll speed is controlled individually. Therefore, it is possible to perform appropriate tension control while suppressing the influence on the thickness variation.

In the case where 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 controlled based on the load target value for the reduction of the stand and the stress target value of the tension. A first parameter indicating the degree of influence of the stress target value on the target value is determined in advance, and the stress target on the advance rate target value is determined based on the advance rate target value and the stress target value for the roll speed of the stand. By determining the second parameter indicating the degree of influence of the value in advance, the control amount of the rolling position and the control amount of the roll speed can be obtained directly from the deviation between the measured value of the tension and the target value.

In the second and third aspects of the present invention, the control amount of the rolling position and the control amount of the roll speed are determined using the first control gain and the second control gain, which are set in advance, and the deviation of the tension. To obtain the respective values, both control amounts are quickly and accurately calculated using the measured values of the 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 thickness of the third stand, and (c) is the thickness of the fourth stand.
(D) shows the fifth stand outboard thickness.
In FIG. 13, the roll gap of the fourth stand is plus 100.
It is operated to be μm.

FIG. 14 is a graph showing the effect on the material to be rolled when the roll speed of the first to third stands is changed stepwise so as to be a success in the tandem mill. (A) is the third
(B) shows the thickness of the third stand exit side plate, (c) shows the fourth stand exit side plate thickness, and (d) shows the fifth stand exit side plate thickness. In FIG.
The roll speed of the first to third stands is operated so as to be plus 5%.

As apparent from FIG. 13, when the lowering position of the fourth stand is operated to be plus 100 μm, the third
-The tension between the fourth stand is corrected by plus 5tf,
A deviation of plus 20 μm occurs in the thickness of the stand exit side plate. Further, a deviation in the minus direction occurs in the thickness of the delivery side of the third stand and the fifth stand. On the other hand, as is apparent from FIG. 14, when the roll speeds of the first to third stands are adjusted to be + 5%, the tension between the third and fourth stands is corrected by minus 3 tf, and the thickness of the fourth stand exit side plate is increased. Plus 40μm
Deviation occurs. From these facts, for example, by operating the rolling position of the fourth stand in the plus direction and operating the roll speed of the first to third stands in the minus direction, the tension between the third and fourth stands is increased in the plus direction. And the fluctuation of the fourth stand exit side plate thickness can be offset to suppress 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 simultaneously changed in a step-like manner in a five-stand tandem mill. And
(A) is the tension between the third and fourth stands, and (b) is the third tension.
(C) shows the fourth stand exit side plate thickness, and (d) shows the fifth stand exit side plate thickness. In FIG. 15, the roll gap of the fourth stand is positive.
Simultaneously, the roll speeds of the first to third stands are controlled to be −4% so as to be 100 μm.

As apparent from FIG. 15, the roll gap of the fourth stand is set to be plus 100 μm, and
By simultaneously operating the roll speed of the third stand to be minus 4%, the tension between the third and fourth stands is corrected by plus 14 tf, but the plate thickness on the exit side of the fourth stand is only minus 4 μm. Has not occurred. These characteristics were similar at a plurality of rolling 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 rolling speed, etc., based on the measured tension deviation, the rolling position and the rolling speed are simultaneously changed so as to have appropriate control amounts in order to eliminate the deviation. Thereby, the tension can be controlled while suppressing the thickness variation, and both control amounts can be calculated quickly.

In calculating the control amount of the rolling position and the control amount of the roll speed, the first control gain G ₁ and the second control gain G ₂ are used. These control gains can be obtained by the following equations based on actual machine tests or rolling theory. As a result, the control amounts of the rolling position and the roll speed can be calculated 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, wherein # 1 to # 5 denote first to fifth stands including a pair of work rolls and a pair of support rolls for supporting the same. The first to fifth stands # 1 to # 5 are arranged in tandem with a predetermined distance therebetween, and roll while transferring the strip S in the direction of the arrow in the figure to produce a rolled material having a predetermined thickness. The pressing rolls 41 to 45 are connected to the support rolls of the stands # 1 to # 5, respectively.
The rolling position control devices 31 to 35 for controlling this are connected to 45. Driving motors 21 to 25 for driving the work rolls of the stands # 1 to # 5 are connected to the work rolls.
65 are connected respectively. Roll speed control device 61
Adders 71 to 73 are connected to 〜63, respectively.

On the entry sides of the stands # 1 to # 5, tension measuring devices SE11 to SE15 for measuring the tension of the strip S are arranged, respectively. 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 respectively connected to the press-down position control devices 31 to 35 of the stand on the downstream side of the tension measuring devices SE11 to SE15, and the overall roll speed control on the upstream side of each of the tension measuring devices SE12 to SE15. Device 61
To 64 via adders 71 to 73 or without them. That is, the tension control devices 52 to 55 are added to the adder 71,
The tension control devices 53 to 55 are connected to the adder 72, the tension control devices 54 and 55 are connected to the adder 73, and the 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 supply it to the tension controllers 51 to 55. A target value of the tension is given to the tension controllers 51 to 55 in advance, a deviation between the target value and the measured value is obtained, and a proportional integral operation described later is performed using the obtained deviation. Then, the tension controllers 51 to 55 calculate the roll-down position control amounts of the stands to be controlled based on the calculated values, and give the results to the roll-down position controllers 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, give the result to the adders 71 to 73, and the adders 71 to 73 add the added value. This 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 roll-down position control devices 31 to 35 and the roll speed control devices 61 to 64 provide the roll-down position of the work roll by the roll-down devices 41 to 45 and the drive motor 21 so as to achieve the given roll-down position control amount and roll speed control amount. Control the roll speed of the work roll by ~ 24. Note that 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 roll position control amount and the roll speed control amount will be described. Now a tension control device connected to a tension measuring device SE13 placed on the entrance side of the third stand # 3
Focus on 53. The tension control device 53 obtains a deviation ΔT ₃ between the measured value from the tension measuring device SE13 and the target value, performs a proportional-integral operation according to the following expression (1), and then calculates the third stand に よ っ て according to the following expression (2). 3 of pressing position control amount [Delta] S ₃ is calculated.

[0046]

(Equation 5)

[0047]

(Equation 6)

At the same time, the second star is calculated by the following equation (3).
♯2 roll speed control amount ratio ΔV _Two/ V_TwoCalculate
At the same time, roll speed control of the first stand # 1
Volume ratio ΔV₁/ V₁Is calculated.

[0049]

(Equation 7)

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

[0051]

[Table 2]

FIG. 4 is a graph showing the results obtained by the method of the present invention. FIG. 4 (a) shows a stepwise change of the rolling position of the fourth stand and a smooth change of the roll speed of the first to third stands simultaneously. FIG. 4 (b) shows the thickness variation on the exit side of the fourth stand in the case shown in FIG. 10 and 11 are graphs showing the results obtained by the conventional method. FIG. 10 (a) shows the change in tension on the entrance side of the fourth stand when the rolling position of the fourth stand is changed stepwise. (B) The thickness variation on the exit side of the fourth stand in that case, and FIG. 11 (a) shows the tension variation on the entrance side of the fourth stand when the roll speed of the first to third stands is changed stepwise in a progressive manner. FIG. 11B shows the thickness variation on the exit 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 entrance 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 fourth stand entry side quickly converges to the target value when the rolling position and the roll speed are changed, but in both cases, the fourth stand exits. Side plate thickness fluctuates remarkably.

FIG. 12 is a block diagram showing another embodiment of the present invention, in which the present invention is applied to a fourth stand # 4. The tension measuring device SE is on the entry side of the fourth stand # 4
14 Yes disposed, the tension deviation e ₄ tension meter SE14 was measured is applied to a proportional integral calculation unit 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 adapted to also given tension corrected output quantity c ₄ used to control timing immediately before from the storage unit 203, an adder 202 new tension corrected output quantity c ₄ by adding both The data is output to the storage device 203 and stored therein, and is also supplied to the multipliers 205 and 206.

To the multipliers 205 and 206, a control gain G ₁ for adjusting the rolling position and a control gain G ₂ for adjusting the roll speed are given from the control gain setting device 210 according to the rolling conditions of the material S to be rolled. It has become.

[0056]

(Equation 8)

The multiplier 204 receives the signal from the adder 202.
Output tension correction output c_FourControl gain G₁Multiply by
This is given to the rolling-down position control device 34 to control the lowering
Control the position. In addition, the multiplier 205
Given tension correction output c _FourControl gain G_TwoMultiply by
And the first and second stands # 1, # 2 and # 2
Controls drive motors 21, 22, and 23 connected to 3 stands # 3
To the roll speed controllers 61, 62, and 63
The rotation speeds of the dynamic motors 21, 22, and 23 are controlled.

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 the following Table 3, the plate width, the base material thickness, finishing sheet thickness was determined four different control respectively, for the type of material to be rolled gain G ₁ and the control gain G _2. The result is shown in FIG. 16 as a vector. As shown in FIG. 16, the control gain G ₁ in any case is a positive value, the control gain G ₂ is a negative value. And if the plate width is large (I, K), the value of the control gain G ₁ is increased, pressing position control is mainly, if conversely plate width is narrow (H, J) is the roll speed control and the metallic Become.

[0059]

[Table 3]

Next, the results of a comparative test will be described. Table 4 shows the results of the comparison, and shows the results for the minimum value of the control cycle, the average tension fluctuation width, and the average plate thickness fluctuation width. In the table, Conventional Example 1 corresponds to the above-mentioned JP-A-4-84.
No. 613, and Conventional Example 2
This is the result of implementing the method described in JP-A-5-31517. Each value is represented by a relative value with the minimum value of the control cycle, the average tension variation width, and the average plate thickness variation width of 1.00 in Conventional Example 2.

[0061]

[Table 4]

As is apparent from Table 4, the control method of the present invention can quickly calculate the control amount of the rolling position and the control amount of the roll speed, so that the control cycle can be reduced to 1/2 or less than that of the conventional example 2. Was. Further, in the method of the present invention, both the average tension fluctuation width and the average plate thickness fluctuation width are suppressed as compared with 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 precision. You can see that it is.

In this embodiment, the tension control device
Although the roll-down position control device of the downstream stand adjacent to the tension measuring device and the roll speed control device of all the upstream stands are controlled, the present invention is not limited to this. Even if the roll-down position control device of the adjacent stand on the downstream side and the roll speed control device of all the stands on the downstream side are controlled, the effect is not changed.

[0064]

As described in detail above, in the method for controlling the tension of a rolling mill according to the first invention, the tension can be controlled with high precision while suppressing the fluctuation of the thickness of the rolling mill. Product quality is improved.

In the method for controlling the tension of 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 calculated quickly, so that the control cycle can be shortened. The present invention has excellent effects such as improved control accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the 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 successive fluctuation of the roll speed of the first to third stands are simultaneously performed in steps. It is a graph.

FIG. 3 shows the results of measuring the thickness variation at the exit side of the fourth stand when the variation of the rolling position of the fourth stand and the successive variation of the roll speed of the first to third stands are simultaneously performed in a stepped manner. 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 the results of measuring the width of tension fluctuation on the fourth stand entry side when the rolling position of the fourth stand is changed in a sinusoidal manner in a rolling mill provided with five stands.

FIG. 7 is a graph showing the results of measuring the width of plate thickness variation on the exit side of the fourth stand when the rolling position of the fourth stand is changed 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 fluctuately.

FIG. 9 is a graph showing the results of measuring the thickness variation width on the exit side of the fourth stand when the roll speeds of the first to third stands are varied smoothly.

FIG. 10 is a graph showing a result obtained by a conventional method.

FIG. 11 is a graph showing a result obtained by a 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 in a stepped manner in a five-stand tandem mill.

FIG. 14 shows a first stand of a five-stand tandem mill.
It is a graph which shows the influence which acts on a to-be-rolled material when changing the roll speed of a 3rd stand into a step shape so that it may become succesive.

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 simultaneously changed stepwise in a five-stand tandem mill.

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

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

FIG. 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.

[Description of Signs] 1-5 Stand 11-15 Tension Measuring Device 21-25 Drive Motor 31-35 Depressing Position Control Device 41-45 Depressing Device 51-55 Tension Control Device 61-65 Roll Speed Control Device 71-73 Adder Reference Signs List 201 proportional-plus-integral operation device 202 adder 203 storage device 204 multiplier 205 multiplier 210 control gain setting device S strip

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-188414 (JP, A) JP-A-48-79751 (JP, A) JP-A-59-33005 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (3)

(57) [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 instrument installed between the stands, and the measurement is performed. A method for controlling a rolling position and a rolling speed of the rolling roll so as to eliminate the deviation by using a deviation between a value and a target value and a proportional integral calculation value obtained based on the deviation. A first parameter representing the degree of influence of the target stress value on the target load value based on the target load value for the reduction of the target and the target stress value of the tension; and a target advance rate value for the roll speed of the stand. And a second parameter representing the degree of influence of the stress target value on the advance rate target value based on the stress target value and the proportional integral Using the calculated value and the first parameter, a control amount of the roll-down position of the stand on the downstream side of the tension measuring device is obtained, and the roll-down position of the stand is controlled by the control amount, and the proportional-integral operation value is calculated. A control amount of the roll speed of the stand on the upstream side or the downstream side of the tension measuring device using the second parameter and the second parameter, and controlling the roll speed of the stand by the control amount. Machine tension control method. 2. 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. A method for controlling a rolling position and a rolling speed of a rolling roll, in order to eliminate the deviation by using a deviation between a value and a target value and a proportional integral calculation value obtained based on the deviation. The control amount of the rolling position of the stand on the downstream side of the tension measuring device is obtained by using the integral calculation value and the first control gain set in advance according to the rolling conditions, 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-integral calculation value and a second control gain set in advance according to the rolling conditions. 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)