JPH1015606A - Method for estimating plate thickness between stands in continuous rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a plate thickness between stands in high precision at the time of controlling the set-up of a continuous rolling mill by obtaining an actual forward slip every time a rolling material passes through each stand, comparing it with the forward slip obtd. by the calculation and learning a calculation model. SOLUTION: The rolling material 20 is passed through from a stand No.1 to stand No.7. First, the necessary time that the front part of the rolling material 20 passes through the interval between both stands, i.e., from the stand No.(i) to the stand No.(i+1), is calculated lated from the difference of the load-on times to both stands. The speed that the front tip part of the rolling material 20 shifts between both stands is obtd. from the above time and a distance between both stands. At the last stand 7, this speed is calculated from a substituted time of the load-on time detected from an HMD 16. The peripheral speed of a roll in the stand No.(i) is obtd. from a pulse integrated value and the diameter of the work roll in the stand No.(i) to obtain the actual forward slip at the time of individually passing through the stand. This actual forward slip and the calculated actual forward slip obtd. from the actual data, and compared and the forward slip calculated model is learnt and corrected to estimate the plate thickness between the stands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a stand-to-stand thickness with high accuracy during mill setup control of a continuous rolling mill.

[0002]

2. Description of the Related Art Mill setup control in a hot continuous rolling mill in which a plurality of stands are juxtaposed involves first determining an outlet plate thickness for each stand, and in accordance with the determined pass schedule plate thickness. The following equation (1) is used to calculate the predicted rolling load P of each stand at the time of rolling the next material. Then, the roll opening is set based on the predicted rolling load P in consideration of the mill elongation for each stand.

[0003]

(Equation 1)

Here, W is the sheet width, k is the deformation resistance of the rolled material, R ₁ is the flat radius of the roll, H is the incoming side sheet thickness, h is the outgoing side sheet thickness, and Q _P is the rolling force function. This rolling force function Q _P is
It is a function such as a coefficient of friction or a draft, and is derived from rolling theory. However, since the deformation resistance k and the friction coefficient included in the rolling force function Q _P cannot be accurately grasped, it is not possible to obtain the predicted rolling load P with high accuracy only by the calculation using the above equation (1). Can not. For this reason, learning correction of equation (1) is performed using the rolling performance data up to the previous material.

[0005] As the actual rolling data used for this learning, the sheet thickness at the entrance and the exit at each stand is required in addition to the rolling load, the roll opening, and the roll peripheral speed. However, in a continuous hot rolling mill, there is usually no means for measuring the thickness of the rolled material except for the exit side of the final stand. In addition, the timing of collecting the rolling performance data used for learning must be a time when the rolling performance data is stable and a time when the mass flow at each stand is established. It must be performed when the tip end of the material has passed through the final stand (hereinafter referred to as “at the time of overall passage”).

Conventionally, the sheet thickness between stands during the entire passage, that is, the sheet thickness on the entrance and exit sides of each stand, is calculated from the actually measured roll peripheral speed of each stand and the sheet thickness on the exit side of the final stand, and separately from an advanced rate calculation model. Using the advanced rate thus calculated, the value is obtained by calculation using the following equation (2) based on the constant law of mass flow.

[0007]

(Equation 2)

[0008] Here, V _R is the roll peripheral speed, f is the advanced rate, the subscript is a stand number. The advance rate f is defined by the following formula (3) using the speed V of the rolled material at the exit side of each stand and the roll peripheral speed V _R, and from the rolling theory,
It can be obtained by the formula.

[0009]

(Equation 3)

Here, φ _n is a neutral angle. However,
Here, the neutral angle φ _n greatly changes depending on the friction coefficient between the rolled material and the work roll and the entrance and exit side tension of each stand. In addition, the friction coefficient is the steel type of the rolled material,
It also changes depending on the rolling temperature and the like, and it is very difficult to grasp accurately. Therefore, it is almost impossible to obtain a high-precision advance rate f from the equation (4).

From the above, the thickness of the entrance / exit side of each stand obtained from the equation (2) includes a large error in the advance rate f, and the above-mentioned (1) is performed based on the equation (2). The learning correction of the expression (2) also includes a large error. In order to solve this problem, it has been proposed to install a speedometer between all the stands, measure the speed V of the rolled material, and actually measure the advanced rate f using the above equation (3). . As a method of measuring the speed of a rolled material, Japanese Patent Application Laid-Open No. Sho 62-197210 describes a method of installing a laser Doppler type speed meter (hereinafter, referred to as a conventional first method). Also, Japanese Patent Application Laid-Open No. 56-1
No. 14,508 discloses a method of measuring a plate speed from the number of rotations of a looper roll (hereinafter, referred to as a conventional first method).

In addition to the above, the simplest method is to detect the load-on time of each stand, calculate the time required for the leading end of the rolled material to pass between the stands, and determine the distance between the stands by this distance. A method of dividing by time is also widely known (hereinafter, conventionally referred to as a third method).

[0013]

In the first conventional method, since the laser Doppler type speedometer is expensive, there is a problem that the introduction of this method requires a large capital investment, and the second conventional method is difficult. In this case, there is a problem that a non-negligible error is included in a measured value due to a slip between the looper roll and the rolled material.

On the other hand, the conventional third method can be applied only to individual points of time when the leading end of the rolled material passes through each stand (hereinafter, referred to as “individual passage”), and cannot be applied to the whole passage due to the measurement principle. The advance rate f cannot be determined. To acts and out-side tension throughout passage time, since no action egress tension during individual passes, thereby, become neutral angle phi _n that the changes in the overall passage time of the individual when passing, thus naturally In addition, the advanced rate f to be obtained is different.

The present invention has been made in view of the above circumstances, and in performing mill set-up control in a continuous rolling mill, learning correction of a formula for calculating a predicted rolling load is performed. It is an object of the present invention to provide a method for estimating the thickness between stands of a continuous rolling mill, which can estimate the thickness between stands with high accuracy.

[0016]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, according to the present invention, in the method for estimating the thickness between stands in a continuous rolling mill in which a plurality of stands are arranged side by side, each time the leading end of the rolled material passes through each stand other than the last stand, the measured advance at each stand is measured. In the final stand, the measured advance rate is calculated from the exit rolled material speed calculated from the difference between the stand passing time at the final stand and the time at which the leading end of the rolled material has moved a fixed distance and the measured roll peripheral speed at the final stand. And compare the measured advanced rate with the calculated advanced rate to learn the advanced rate calculation model used to calculate the advanced rate, and the leading end of the rolled material passes through the final stand. At the same time, the stand exit side plate thickness and the roll peripheral speed at each stand are actually measured at the same timing, and learning is performed using these measured values and the calculated advance rate calculated taking into account the exit side tension of each stand. Based on the advanced rate calculation model, it is characterized by calculating the plank between each stand.

As described above, the measured advanced rate is also obtained without relying only on the advanced rate obtained by calculation, whereby the advanced rate calculation model used for calculating the advanced rate is learned and corrected. Therefore, the accuracy of estimating the thickness of each stand during the entire passage can be significantly improved as compared with the related art. Accordingly, the accuracy of estimating the plate thickness between stands is improved, so that the accuracy of predicting the rolling load in the next material can be significantly improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a hot continuous rolling mill in which stands 1 to 7 from No. 1 to 7 are juxtaposed, and each of the stands 1 to 7 detects a rolling load. A load cell 10 is provided, and a pulse generator 13 is connected to the mill motor 12 of each of the stands 1 to 7.

On the exit side of the final seventh stand 7, an X-ray thickness gauge 15 and an HMD 16 ("Hot Metal Dete
abbreviated as "ctor", which detects infrared rays to detect the position, etc.). The HMD 16 is arranged at a predetermined distance on the exit side of the seventh stand 7. Therefore, in this hot continuous rolling mill, the leading end of the rolled material 20 is positioned at each of the stands 1 to 7.
, The rise time (that is, the load on time) of each of the stands 1 to 7 can be detected by the load cell signal from each load cell 10.

Further, by integrating the number of pulses transmitted from the pulse generator 13, the number of rotations of the work roll can be known as a proportional number of the integrated value. It is possible to detect the number of rotations of the roll when the leading end of the rolled material 20 passes between adjacent stands. Similarly, the leading end of the rolled material 20 that has passed through the final seventh stand 7 is H
When passing through the MD 16, the detection time from the HMD 16 can detect the passing time (ie, the time used as a substitute for the load-on time). Therefore, it is also possible to detect the pulse integrated value (that is, the number of rotations of the work roll in the seventh stand 7) until the leading end of the rolled material 20 moves a certain distance after passing through the seventh stand 7.

In the hot continuous rolling mill having such a configuration, the rolled material 20 is passed from the first stand 1 to the seventh stand 7 to execute the method for estimating the inter-stand sheet thickness according to the present invention. Will be described. First, i stand and i
From the difference between the load-on times of the +1 stand, the required time t _i for the leading end of the rolled material 20 to pass between both stands is calculated. Then, the obtained value and the distance L between the two stands are obtained.
_The speed V _{i at} which the leading end of the rolled material 20 moves between the two stands is obtained from _i and the following equation (5). As described above, in the case of the final seventh stand 7, the above H
The calculation is performed at the substitute time of the load-on time detected from the MD 16.

[0022]

(Equation 4)

On the other hand, from the pulse integration value _Ni (roll rotation speed) during the required time t _i and the diameter D _{i of the} work roll in the i stand, the roll circumference of the i stand is calculated by the following equation (6). _{Find the} speed V _Ri .

[0024]

(Equation 5)

Here, n is the number of pulses during one rotation of the roll. As long this way obtained rolled material speed V _i and the roll peripheral speed V _Ri is, by using the equation (3), the measured forward slip f _i during individual passes (including the final 7th stand 7) You can ask.

[0026]

(Equation 6)

On the other hand, by using Orowan's theory of rolling under mixed friction conditions, the relationship between the exit side plate thickness and the reduction ratio and the advanced ratio (FIG. 2), the relationship between the friction coefficient and the reduction ratio and the advanced ratio ( The relationship between the entrance tension and the advance rate (FIG. 4) and the relationship between the exit tension and the advance ratio (FIG. 5) are numerically analyzed off-line. Then, from these analysis results, an advanced rate calculation model based on the above equation (4) is created as represented by the following equation (7), and the advanced rate f is obtained by this.

[0028]

(Equation 7)

Where r is the draft, μ is the coefficient of friction, σ _b
Is the entrance tension and σ _f is the exit tension. The first term (F ₁ ) in the equation (7) is a term relating to the rolling condition and is not affected by the tension. Flat roll radius R ₁ is calculated by the equation of Hitchcock. The rolling reduction r is defined by the equation (8), and the friction coefficient μ is calculated from the equation (9) created based on the result of separately analyzing the rolling performance data off-line.

[0030]

(Equation 8)

In the equations (7) and (8), the entrance side plate thickness H and the exit side plate thickness h are calculated from the roll opening and the rolling load at the time of individual passage by a known gauge meter formula. Θ in the above equation (9) is a rolled material temperature, which is used as a parameter representing the temperature of the roll bite interface.
The rolling reduction r in the equation (9) is used as a parameter representing the relative sliding speed between the work roll and the rolled material at each stand. As representative chemical components,
It is good to use Si content.

The second term (F ₂ ) in equation (7) is a term relating to tension. The actual value at the time of individual passage is used as the entrance tension σ _b . The output side tension σ _f is zero during individual passage. The deformation resistance k is calculated from the equation (10) created based on the results of a separate hot multi-stage compression test.

[0033]

(Equation 9)

Here, ε is strain and ε _v is strain rate. Next, learning is performed on the equation (7). In the above equation (7), the largest error factor is the friction coefficient μ, and all other parameters can be directly or indirectly derived from measured data. Therefore, at the time of learning, the second term may be taken in as it is, and only the first term is expressed by the equation (11) expressed in the form of a ratio, or expressed by the difference (12) ) Is calculated based on the expression to obtain a learning coefficient CF.

[0035]

(Equation 10)

Here, f _a is the measured advance rate. This learning coefficient CF is calculated by the following exponential smoothing method (13)
It is corrected sequentially according to the formula.

[0037]

[Equation 11]

Here, α is a smoothing coefficient, CF _j is a learning coefficient calculated this time, and CF ₀ is a smoothing learning coefficient up to the previous material. It should be noted that this correction is preferably performed for each group of steel type, plate thickness, and the like, since the learning accuracy can be further improved, which is preferable. Next, at the time of the entire passage, the exit side plate thickness h _M7 at the final 7th stand 7 is _measured by the X-ray plate thickness meter 1.
Measured according to 5. At the same time,
The roll peripheral speed _VRMi at each stand is actually measured by the above-described method using the number of accumulated pulses.

Further, the calculated advance rate f _M is calculated from the equation (7) using the actual rolling data at the time of the entire passing. However, at the time of the whole passage, the method of obtaining at the time of the individual passage is the exit side tension σ
_The difference is that _f must be taken into account. The calculated advance rate f _M is corrected by the following equation (14) using the smoothing learning coefficient CF obtained by the equation (13).

[0040]

(Equation 12)

Here, F _M1 and F _M2 correspond to the first and second terms of the equation (7) calculated using the actual rolling data at the time of the entire passage. Finally, the thickness between the individual stands during the entire passage corresponds to the above-mentioned equation (2).
It is calculated by the following equation (15).

[0042]

(Equation 13)

As described above, in the stand-to-stand sheet thickness estimating method according to the present invention, not only the advanced rate obtained by calculation but also the actually measured advanced rate is obtained, and the advanced rate used for calculating the advanced rate is thereby obtained. Since the calculation model is learned and corrected, the accuracy of estimating the thickness of each stand during the entire passage can be significantly improved as compared with the related art.

FIG. 6 shows the accuracy of the rolling load prediction model used for mill set-up control in the case where the thickness between the stands during the entire passage according to the present invention is used, and the conventional advanced ratio obtained by calculation. It is shown in comparison with the case where the thickness between the stands at the time of the entire passage calculated from the above is used. As is clear from FIG. 6, according to the method of the present invention, the prediction accuracy of the rolling load can be remarkably improved by improving the estimation accuracy of the thickness between the stands.

[0045]

As is clear from the above description, according to the method of the present invention, the accuracy of estimating the thickness between stands in the preceding material is improved, thereby significantly improving the prediction accuracy of the rolling load in the next material. Can be.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a hot continuous rolling mill used for carrying out a method for estimating a thickness between stands according to the present invention.

FIG. 2 is a graph showing the results of numerical analysis of the relationship between the exit side plate thickness and the reduction ratio and the advance ratio.

FIG. 3 is a graph showing a result of numerical analysis of a relationship between a friction coefficient and a reduction ratio and an advanced ratio.

FIG. 4 is a graph showing the result of numerical analysis of the relationship between the entrance tension and the advance rate.

FIG. 5 is a graph showing the result of numerical analysis of the relationship between the output side tension and the advance rate.

FIG. 6 is a graph comparing the present invention with the conventional one regarding the rolling load prediction accuracy.

[Explanation of symbols]

 1-7 stand 10 load cell 12 mill motor 13 pulse generator 16 HMD

Claims (1)

[Claims] 1. A method for estimating a sheet thickness between stands in a continuous rolling mill in which a plurality of stands are juxtaposed, wherein each time a leading end portion of a rolled material passes through each stand other than the last stand, an actually measured advance rate at each stand In the final stand, the measured advance rate is calculated from the exit rolled material speed calculated from the difference between the stand passing time at the final stand and the time at which the leading end of the rolled material has moved a fixed distance, and the measured roll peripheral speed at the final stand. The advanced rate calculation model used to calculate the advanced rate is calculated by comparing the measured advanced rate with the calculated advanced rate. Measure the stand-out side plate thickness and the roll peripheral speed at each stand at the same timing, and use these measured values and the calculated advance rate calculated taking into account the stand-out side tension of each stand. of Based on the advance rate calculation model, interstand thickness estimation method of the continuous rolling mill and calculates the plank between each stand.