JPH08238505A - Method for setting pass schedule of continuous rolling mill and device therefor - Google Patents

Abstract

PURPOSE: To set a pass schedule by which stable operation is always executed by repeatedly correcting thickness on the outlet side using an estimated sensitivity matrix. CONSTITUTION: The roll gaps at respective stands of a continuous rolling mill are calculated from thicknesses on the outlet sides of the respective stands by use of a rolling model (S1-S3) and the pass schedule is set based on the arithmetic results (S11). In such case, roll gap differences between adjoining stands each other are calculated about calculated roll gaps of the respective stands (S4) and the sensitivity matrix for expressing the relationship between the roll gap difference and the thickness on the outlet side is estimated based on the relationship between the roll gaps and the thicknesses on the outlet sides of respective stands (S5, S6). The thickness on the outlet side is repeatedly corrected by use of the estimated sensitivity matrix (S10) so that the pattern of the calculated roll gap difference is approached to the target pattern which is preliminarily stored in a memory (S7-S9).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pass schedule setting method and apparatus for a continuous rolling mill, and more particularly to a pass schedule setting method and apparatus for a continuous rolling mill capable of accurately reflecting the operator's knowledge of operation. Is.

[0002]

2. Description of the Related Art Generally, when a strip steel is processed by a continuous rolling mill, a reasonable roll gap, rolling speed, etc. are operated so as to satisfy given specifications such as dimensions, shape and strength of each strip steel. It is necessary to determine the set value in advance. Conventionally, these setups have been automatically set by a computer based on a rolling model based on the well-known rolling theory. In order to make such a setup model closer to actual rolling, we estimated and adjusted the parameters required for the model, improved the model formula, and provided a learning coefficient that modeled the operating results of the front material. Several attempts have been made to improve the setting accuracy by applying it to the rolling of the next material. Examples of approaches based on such rolling models include the following. JP-A-1-233003
In the method disclosed in the publication, the rolling power of each stand is predicted based on the rolling model, and when the limit value is exceeded, the load distribution is distributed to other stands. However, there is a characteristic of operation that cannot be expressed by such a rolling model, and the operator tried to systematize the correction to the setting result to further stabilize the operation. That is, in the method disclosed in Japanese Patent Laid-Open No. 4-162905, whether or not the learning coefficient can be updated is determined based on the rolling knowledge of the operator, and the fitting of the model to the operation record is controlled. Further, in the method disclosed in Japanese Examined Patent Publication No. 63-27087, the rolling ratio pattern of the next material is determined so that the rolling ratio is less changed by using the result appropriately corrected by the operator.

[0003]

In the conventional pass schedule setting method for a continuous rolling mill as described above, there are some characteristics of the machine and phenomena that cannot be modeled in order to match the rolling model to the actual operation. There is a certain limit. For this reason, conventionally, it may not be possible to operate using the setting result of the computer as it is, and at that time, the operator corrects the setting result based on the knowledge obtained from operating experience and operates. For example, in Japanese Unexamined Patent Publication No. 4-162905, it is decided according to the situation how much the actual result is reflected in the rolling model, and it is based on the knowledge that under what conditions the accuracy of the model is likely to be off. Limits the amount of change in the learning coefficient. This method cannot capture operating conditions that cannot be reflected in the rolling model. Further, in JP-B-63-27087, when rolling materials having the same setting continuously, the operation result after the intervention can be stabilized because the result of the intervention with respect to the operator's setting is reflected as a rolling reduction pattern, but the condition is On the contrary, when rolling different materials continuously, it was necessary to change the rolling reduction pattern of the previous material, and the operation could not be stabilized sufficiently.
In addition, with certain materials, roll roughening is likely to occur, and stripping, scale flaws, and sheet drawing are likely to occur, so operators cannot deal with phenomena that cannot be modeled such as what kind of rolling setting should be made. Operational knowledge could not be systematized. However, there is a problem in the setting accuracy by simply incorporating the operational knowledge and determining the setting, and it is necessary to ensure the accuracy of the rolling model used conventionally. The present invention has been made in view of the above circumstances, and an object of the present invention is to make use of the operator's knowledge sufficiently to ensure the accuracy of the rolling model and thereby set a pass schedule to always stabilize the rolling model. It is an object of the present invention to provide a pass schedule setting method and apparatus for a continuous rolling mill capable of obtaining the above-mentioned operational state.

[0004]

To achieve the above object, a first invention is to calculate a roll gap of each stand of a continuous rolling mill from a delivery model thickness of each stand by using a rolling model, and to perform the calculation. In the pass schedule setting method of the continuous rolling mill, which sets the pass schedule based on the result,
Regarding the roll gap of each stand calculated above, the roll gap difference between the stands that follow each other is calculated, and the relationship between the roll gap difference and the exit side plate thickness is calculated based on the relationship between the roll gap of each stand and the exit side plate thickness. Estimating the sensitivity matrix to be expressed, and repeatedly correcting the outlet plate thickness using the estimated sensitivity matrix so that the calculated roll gap difference pattern approaches the target pattern stored in the memory in advance. And a pass schedule setting method for a continuous rolling mill. A second aspect of the invention is a roll gap calculating means for calculating a roll gap of each stand of a continuous rolling mill from a delivery thickness of each stand using a rolling model, and a pass schedule is set based on the calculation result. In a pass schedule setting device of a continuous rolling mill including a pass schedule setting means, a roll gap difference calculating means for calculating a roll gap difference between adjacent stands with respect to the calculated roll gap of each stand, and each stand. Sensitivity matrix estimating means for estimating the sensitivity matrix representing the relationship between the roll gap difference and the outlet side plate thickness based on the relationship between the roll gap and the outlet side plate thickness, and the calculated roll gap difference pattern is stored in a memory in advance. The output of each stand is calculated by using the estimated sensitivity matrix so as to approach the target pattern. A continuous rolling mill pass schedule setting device, characterized by comprising; and a delivery side thickness correction means for repeatedly modifying the thickness.

[0005]

According to the first and second aspects of the invention, the roll gap of each stand of the continuous rolling mill is calculated from the strip thickness of each stand using a rolling model, and the pass schedule is set based on the calculation result. In doing so, the roll gap difference between the stands that are adjacent to each other is calculated for the calculated roll gap of each stand. A sensitivity coefficient representing the relationship between the roll gap difference and the outlet plate thickness is estimated based on the relationship between the roll gap and the outlet plate thickness of each stand.
The exit side plate thickness is repeatedly corrected using the estimated sensitivity matrix so that the calculated roll gap difference pattern approaches the target pattern stored in the memory in advance. The target pattern is determined based on the experience of the operator and is stored in the memory in advance. Thus, by fully utilizing the operator's knowledge, the model accuracy can be ensured and the pass schedule can be set so that stable operation can always be performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. It should be noted that the following embodiments are examples of embodying the present invention, and are not intended to limit the technical scope of the present invention. here,
FIG. 1 is a diagram showing a schematic flow of a pass schedule setting method for a continuous rolling mill according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing a stand around the rolling mill, and FIG. 3 is an error square of a roll gap difference. It is a figure which shows the transition of the sum. We have:
As a result of hearing the operator's knowledge about operation,
It was empirically determined whether the setting was good or bad by the pattern of the difference between the roll gap of the entrance side stand and the roll gap of the exit side stand. Regarding the evaluation of settings based on this roll gap difference pattern,
It has the following features.

First, the roll gap is a set value that is actually used when operating the material, and is the output of the setting calculation by the computer. For this reason, it is possible to directly correlate the result of the operation at that roll gap. Therefore, it is easy to directly reflect the knowledge of the operator. On the other hand, the conventionally used stand-out plate thickness, reduction rate, load distribution rate, etc. are so-called predicted values that are neither set values for operation nor directly measured quantities, and include model prediction errors. Has been. Therefore, when troubles such as plate drawing, breakage, and scratches due to the rough skin of the roll occur during operation, the cause is guessed from the setting of the roll gap, and the setting accuracy cannot be improved. Secondly, in regard to using the difference of roll gap without using the absolute value, the target final thickness is specified in rolling, so the degree of freedom of pass setting (thickness at each stand exit side) is output. (Each roll gap)
There is one less than the degree of freedom. This means that the absolute value of the roll gap cannot be adjusted to a desired value for each stand output side plate thickness except the output side plate thickness of the final stand. On the other hand, in the relative pattern of each roll gap difference, the degree of freedom is exactly the same as the setting, so it is possible to make adjustments by changing the stand-out plate thickness excluding the stand-out plate thickness.

The pass schedule setting method for the continuous rolling mill according to the present embodiment is based on the above-mentioned examination results. As shown in FIG. 1, the roll gap of each stand of the continuous rolling mill is set to Calculation is performed using the rolling model from the delivery side plate thickness (S1 to S3), and the pass schedule is set based on the calculation result (S11). Calculate the roll gap difference (S4),
The sensitivity matrix representing the relationship between the roll gap difference and the outlet side plate thickness is estimated based on the relationship between the roll gap and the outlet side plate thickness of each stand (S5, S6), and the calculated roll gap difference pattern is stored in advance in memory. The exit side plate thickness is repeatedly corrected using the estimated sensitivity matrix so as to approach the target pattern stored in S7 (S7 to S9) (S1).
0). FIG. 2 shows a schematic configuration of an apparatus to which the above method can be applied. The roll gap calculating means 2 in the figure is the step S1 in the above method.
~ S3, pass schedule setting means 3 step S1
1, the roll gap difference calculating means 4 performs step S4,
The sensitivity matrix estimating means 5 executes steps S5 and S6, and the exit side plate thickness correcting means 7 executes steps S7 to S10. Each of these means is prepared as a program of each execution format built in the computer connected to the continuous rolling mill, but a part or all of them is supported by hardware separate from the above computer. You can also

The basic operation of this apparatus will be described below. The knowledge that the operator empirically thinks that it is a more preferable rolling that is less likely to cause problems is the strength of the material,
First, it is expressed by a table of roll gap differences corresponding to material conditions such as target plate thickness and plate width. Then, this is stored in the memory 6 as a target pattern. Then, using the rolling model 1, the roll gap calculating means 2 calculates the roll gap, and the roll gap difference calculating means 4 calculates the roll gap difference. Next, the roll gap difference (result of system setting calculation) is made to approach the target pattern of the roll gap difference stored in the memory 6. Specifically, the sensitivity matrix estimating unit 5 estimates a sensitivity matrix indicating how much the roll gap difference changes when the exit side plate thickness of each stand excluding the final stand is changed from the rolling model 1, and the roll gap difference is calculated. By multiplying the error between the target pattern and the setting calculation result by the inverse matrix of the sensitivity matrix, the correction amount of the output side plate thickness of each stand except the final stand is obtained by the output side plate thickness correcting means 7, and the setting calculation is rolled again. This is performed by the gap calculation means 2.

Here, a series of calculation contents in the computer will be described in more detail. Now, the roll gap difference vector, which is the operator knowledge corresponding to the next material, is d
Let s ^ be the roll gap difference vector calculated from the rolling model 1 as ds. The roll gap difference, which is the calculation result, was calculated by giving the stand outlet side plate thickness. In this case, assuming that the other setting conditions do not change, each stand output side plate thickness vector h ₀ , the sensitivity matrix J (= ∂ds / ∂h), and the plate thickness change amount Δh
Taylor expansion is performed as follows, and is approximated up to the first-order term. Here, the sensitivity matrix J is a regular matrix due to the characteristics of hot rolling. ds = ds (h ₀ ) + JΔh The policy of making this roll gap difference vector ds as close as possible to ds ^ is the plate thickness variation Δ of the next evaluation function E.
Formulate as a minimization on h. However, T represents transposition (the same applies hereinafter). E = (ds ^ -ds) ^T * (ds ^ -ds) Necessary condition ∂E / ∂Δh = 0 and the sensitivity matrix J are regular. Δh = J ⁻¹ (ds ^ −ds (h ₀ )) = J ⁻¹ Δds where Δds is an error vector between the roll gap difference of the operator and the roll gap difference of the pass schedule calculation result.

Based on the above calculation, the thickness of each stand outlet side is Δ
By changing only h and repeating the setting calculation several times,
The roll gap difference target pattern,
Then, the stand outlet plate thickness is updated as shown in the following formula. h^{n + 1}= Hⁿ+ J^-1Δdsⁿ Where hⁱIs the i-th stand outlet side thickness vector
Yes, Δds^jIs the error difference of the jth roll gap difference
It's Tor. Next, a method of estimating the sensitivity matrix J will be described.
I do. For convenience of explanation, the number of stands of the continuous rolling mill is now 7
Suppose there is. Output side thickness vector (Eyes on the output side of the final stand)
H = [h₁ h₂ …
h ₆]^T, The element of the roll gap difference vector is ds =
[Ds₁ ds₂ ... ds ₆]^Tfar. h_iIs i
The thickness of the outlet side of the tando, ds_i= S_{i + 1}-S_iAnd
It Also s_iIs the roll gap of the i stand. This
Then, the sensitivity matrix J is as follows.

[0012]

[Equation 1] Here, as shown in FIG. 2, among the respective variables, h _{1 to} h ₆ are 1 to 6 stand outlet plate thicknesses, h ₇ is a target plate thickness, and s _{1 to} s ₇
Is 1 to 7 stand roll gap, P _{1 to} P ₇ is 1 to 7
Stand load, M ₁ ~M ₇ is 1 to 7 stand mill modulus. Next, if the roll gap difference is divided into roll gaps, the following equation holds.

[Equation 2] Here, in order to calculate the contents of the matrix, a well-known gauge meter formula used when calculating the roll gap in the pass schedule is used. Then, the following formula is established at each stand.

H _i = s _i + (P _i / M _i ) (i = 1, 2, ..., 7) where M _i is a mill constant, that is, a coefficient when the rolling mill is considered as a spring, P _i is a load. This load P _i
Is greatly affected by changes in the incoming plate thickness to the stand (exit plate thickness of the preceding stand) and the outgoing plate thickness from the stand, but the effects from other plate thicknesses and other factors can be ignored. It is about the size. Partial differentiation of the gauge meter type roll gap with the plate thickness is as follows.

(Equation 3) Here, considering the relationship between the load of the rolling mill and the plate thickness, a _i
> 0 and b _i > 0. At this time, since the determinant of the sensitivity matrix J is as follows, it can be seen that the sensitivity matrix J is a regular matrix.

[0014]

[Equation 4] That is, numerical instability does not pose a problem in the execution of the above method. However, it is necessary to obtain the value of the mill constant M _i in advance. Also, the influence coefficient ∂P _i / ∂h
The values of _i-1 , ∂P _i / ∂h _i can be obtained using the load prediction model of the setup calculation. For example, the load prediction data generally uses a function of the following form. P _i = F (h _i-1 , h _i , σ _i-1 , σ _i , σ _i , R _i , w _i , θ _i , ...) where i is the stand number, P _i is the load of the i stand,
F () is a load prediction model, h _i-1 is the entrance plate thickness to the i stand (i-1 stand exit plate thickness), h _i is the i stand exit plate thickness, and σ _i-1 is the i stand Entry side tension (i-
1 stand-out tension), σ _i is the stand-out tension of the i stand, R _i is the roll diameter of the i stand, w _i is the plate width of the i stand, and θ _i is the material temperature of the i stand.

For the load prediction model, the above influence coefficient is calculated as follows.

(Equation 5) Here, Δh _i is the minute change in the plate thickness on the delivery side of the i stand, and Δh _i
i-1 is a minute change in the outgoing plate thickness of the i-1 stand. Since the second term on the right side of the above two equations is calculated at the time of model calculation, the plate thickness may be slightly changed to calculate the load of the first term on the right side.

Each calculation is performed as described above, and based on the results, the path schedule setting means 3 can set the final path schedule. Hereinafter, in order to understand the present invention, each data is embodied and further explained. 1 and 2, the specifications input in steps S1 and S2 for each calculation by the roll gap calculating means 2 are the specifications of the material to be processed and the operating conditions.
It is assumed that the plate thickness on the delivery side of each stand at the start of calculation is determined according to the operating conditions of step S1. In step S3, the roll gap calculation means 2 executes the setup calculation part based on the rolling theory, and in step S3A
Then, the temperature and the load are predicted, and the roll gaps are calculated in step S3B. Roll gap difference calculation means 4
From the roll gap calculated in step S3 by
The roll gap difference between the front stand and the rear stand is calculated in step S4.

Next, the sensitivity coefficient estimating means 5 obtains an influence coefficient from the plate thickness and load related to the setting used in the roll gap calculation in step S5, and obtains a sensitivity matrix from the influence coefficient and the mill constant in step S6. . Step S7
Gives knowledge about the roll gap difference,
Data extracted from the operator in the following form,
That is, the target pattern of the roll gap difference is stored in the memory 6. IF strength is 20K and target thickness ≤ 1.49mm THEN roll gap difference (6,3,1.45,1.25,0.2, -0.5)

The exit side plate thickness correcting means 7 extracts the roll gap difference corresponding to the operating conditions of the above steps S1 and S2 in step S7, and the above step S4 in step S8.
The error from the calculated roll gap difference calculated in step 1 is calculated as the sum of squares of the errors in the roll gap difference pattern. In step S9, it is determined whether the error is less than or equal to a predetermined value ε (eg, ε = 0.5), and if it is less than or equal to the predetermined value ε, the calculation result is output, and the path schedule setting means 3 performs step S9.
Set to 11 for actual operation. However, if the error is larger than the predetermined value ε, the output side plate thickness correction amount for bringing the roll gap difference in step S4 closer to the target pattern of the roll gap difference in step S7 is set in step S10.
Then, the product is calculated by the inverse matrix of the sensitivity matrix and the roll gap difference error, and the roll gap setting is obtained by adding the correction amount to the output side plate thickness to change the model thickness and re-running the model calculation.

According to the present embodiment, it is possible to approximate the roll gap difference that the operator has as an image of stable operation by repeating the calculation two to three times, and to reduce the load on the operator and stable operation. I found that I can contribute. An example of the result is shown in FIG. This figure 3
Then, the number of calculations and the roll gap difference, which is the calculation result, and the target roll gap difference set from operator knowledge,
It is shown that the sum of multiplications (evaluation function) decreases. In the figure, the first time is the calculation result based on the rolling model, and the deviation from the target roll gap difference is large. However, it can be understood that the target roll gap difference can be quickly met by adding the correction according to the present embodiment. Also,
According to this embodiment, the result obtained from the rolling model 1 is adapted to the operator knowledge.
Sufficient conventional model accuracy can be secured.

As a result, by fully utilizing the knowledge of the operator, the model accuracy can be ensured, and the pass schedule can be set so that stable operation can always be performed. In the above embodiment, the target pattern of the roll gap difference based on the experience of the operator is used in order to fully utilize the knowledge of the operator. However, in actual use, when a good rolling result is obtained in the past. There is no problem even if the measured pattern of the roll gap difference is used.
In the above embodiment, after the roll gap difference calculation means 4 calculates the roll gap difference (S4), the sensitivity matrix estimation means 5 executes the influence coefficient estimation (S5) and the sensitivity matrix calculation and the inverse matrix calculation (S6). However, in actual use, there is no problem even if step S4 and steps S5 and S6 are executed in reverse or simultaneously.

[0021]

Since the pass schedule setting method for continuous rolling mill and the apparatus therefor according to the present invention are configured as described above, the model accuracy can be secured by fully utilizing the knowledge of the operator. It is possible to set a pass schedule that enables stable operation at all times.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic flow of a pass schedule setting method for a continuous rolling mill according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a stand around a rolling mill and a pass schedule setting device.

FIG. 3 is a diagram showing a transition of a sum of squared errors of a roll gap difference.

[Explanation of symbols]

 S1 to S3 ... Roll gap calculation step S4 ... Roll gap difference calculation step S5, S6 ... Sensitivity matrix estimation step S7 to S10 ... Delivery side plate thickness correction step S11 ... Roll gap setting step

Front page continued (72) Inventor Akira Kitamura 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Kobe Steel Co., Ltd. (72) Inventor Kazunori Haraguchi 1 Kanazawa-machi, Kakogawa-shi, Hyogo Stock Company Kado Steel Works Kakogawa Steel Works

Claims (2)

[Claims] 1. A pass schedule setting method for a continuous rolling mill, in which a roll gap of each stand of the continuous rolling mill is calculated from an outlet plate thickness of each stand using a rolling model and a pass schedule is set based on the calculation result. In the above, the roll gap difference between adjacent stands is calculated for the calculated roll gap of each stand, and the roll gap difference and the exit side plate thickness are calculated based on the relationship between the roll gap of each stand and the exit side plate thickness. The sensitivity matrix representing the relationship is estimated, and the output side plate thickness is repeatedly corrected using the estimated sensitivity matrix so that the pattern of the calculated roll gap difference approaches the target pattern stored in the memory in advance. A method for setting a pass schedule for a continuous rolling mill, characterized by: 2. A roll gap calculating means for calculating a roll gap of each stand of a continuous rolling mill from a strip thickness of each stand by using a rolling model, and a pass schedule setting for setting a pass schedule based on the calculation result. And a roll gap difference calculating means for calculating a roll gap difference between adjacent stands with respect to the calculated roll gap of each stand, and a roll gap of each stand. Sensitivity matrix estimating means for estimating a sensitivity matrix representing the relationship between the roll gap difference and the exit side plate thickness based on the relationship between the roll gap difference and the exit side plate thickness, and the target of the calculated roll gap difference pattern previously stored in a memory. Using the estimated sensitivity matrix above, the exit side plate thickness of each stand is approximated to the pattern. A pass schedule setting device for a continuous rolling mill, comprising: an exit side plate thickness correcting means for repeatedly correcting.