JPS6146202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feed-forward type automatic plate thickness control method for a cold tandem rolling mill.

Conventionally, this type of sheet thickness control method detects the deviation in the sheet thickness at the exit side of the upstream stand using a thickness meter or a known gauge meter type, and accordingly adjusts the roll gap at the downstream stand by taking into account the transfer time of the rolled material. At the same time, the thickness of the outlet plate of the next stand on the downstream side is adjusted to match the target plate thickness.

By the way, there are places in the rolled material, such as so-called skid marks, where the hardness is locally high and the deformation resistance is high. If there is a local variation in this deformation resistance, even if the entrance plate thickness and roll gap of the downstream next stand are the same,
As can be seen from the fact that parts with high deformation resistance have a thicker outlet side plate thickness, and parts with a lower deformation resistance have a thinner outlet side plate thickness, it is necessary to change the roll gap depending on the magnitude of the deformation resistance. However, the conventional plate thickness control method described above does not take into account local variations in deformation resistance at all, and therefore cannot accurately control the outlet side plate thickness of the downstream next stand. For this reason, a coil rolled using the conventional sheet thickness control method has the disadvantage that it becomes thicker in areas where local deformation resistance is large, such as skid marks, for example.

In order to eliminate the above-mentioned drawbacks, this invention controls the plate thickness by taking into account local fluctuations in the deformation resistance of the rolled material.
It is an object of the present invention to provide a method for controlling plate thickness of a cold tandem rolling mill that can improve plate thickness accuracy.

The plate thickness control method for a cold tandem rolling mill of the present invention measures the inlet plate thickness of the upstream stand with a thickness gauge, calculates the inlet thickness deviation of the inlet plate thickness with respect to the target inlet plate thickness, and The roll gap when the upstream stand rolls the part of the rolled material for which the side plate thickness deviation has been calculated is set based on the input side plate thickness deviation and the standard deformation resistance so that the outlet side plate thickness of the upstream stand becomes the target outlet plate thickness. and the mill constant of the upstream stand, and calculate the rolling load deviation from the standard rolling load of the actual measured rolling load of the upstream stand when rolling the above-mentioned rolled material part. The exit side plate thickness deviation of the exit side plate thickness of the side stand with respect to the target exit side plate thickness is calculated based on the above-mentioned rolling load deviation, roll gap correction amount, and mill constant of the upstream stand, and then, the deformation of the above-mentioned rolled material portion is calculated. The actual deformation resistance is calculated by calculating the variation in resistance based on the above-mentioned entrance plate thickness deviation, the above-mentioned rolling load deviation, and the above-mentioned exit side plate thickness deviation, and then the downstream next stand rolls the part of the rolled material. The roll gap at the end of the process is corrected and set based on the above actual deformation resistance, the above upstream stand's exit plate thickness deviation, the downstream next stand's mill constant, and the standard reduction amount, and the exit side plate thickness of the downstream next stand is The feature is that the target plate thickness is achieved.

Hereinafter, this invention will be explained in detail with reference to Examples.

First, the first, second, third...
Each target entrance plate thickness of the stand H _1B , H _2B , H _3B ...
..., each outlet target plate thickness h _1B , h _2B , h _3B ... and the standard deformation resistance coefficient of the rolled material having a locally large portion with a large deformation resistance coefficient, for example, the standard deformation resistance coefficient Q ₁ , Q at the time of lock-on. ₂ , _Q3 ... are set in advance.

In the first stand, rolling is carried out by controlling the roll gap as illustrated in Fig. 1, and the actual deformation resistance coefficient of each part of the rolled material is
Q′ ₁ is calculated as follows.

In Figure 1, H ₁ is the first value actually measured using a thickness gauge.
The entry side plate thickness of the stand, S _1B is the standard roll gap of the first stand, and S ₁ is the corrected roll gap of the first stand. Therefore, FIG. 1 shows that when the target entrance plate thickness of the first stand is H _1B and the roll gap of the first stand is the reference roll gap H _1B ,
The outlet plate thickness is expressed by the abscissa of the intersection point X ₁ between the standard deformation resistance curve Q _1-a having the standard deformation resistance coefficient Q ₁ and the mill stiffness curve M _1-a representing the mill stiffness coefficient M ₁ of the first stand. This shows that the target exit side plate thickness is h _1B , that is, under the standard deformation resistance coefficient Q ₁ and the standard roll gap S _1B , if the entrance side plate thickness is the target input side plate thickness H _1B , the exit side plate thickness is the target output side plate thickness. This indicates that the side plate thickness will be h _1B . On the other hand, even if the entrance side plate thickness deviation of the measured entrance side plate thickness H ₁ from the target entrance side plate thickness H _1B is ΔH ₁ , if the roll gap is the standard roll gap S _1B , then the above deformation The abscissa of the intersection Y of the deformation resistance curve Q _{1-b, which} is obtained by translating the resistance curve Q 1-a, and the mill stiffness curve M _1-a is h _1i , and the exit side plate thickness is calculated with respect to the target exit side plate thickness h _1B . Since the deviation Δh _1i occurs, the abscissa of the intersection Z B between the mill stiffness curve M _1-b obtained by translating the mill stiffness curve M _1-a and the deformation resistance curve Q _{1-b is} the exit target plate thickness h. _1B
Correct the roll gap by ΔS ₁ so that
At this time, the difference in the ordinates between point Z _B and point X, that is, the load deviation ΔP _1i of the predicted rolling load P _1i with respect to the standard rolling load P _1B , is, as is clear from FIG. 2, ΔP _1i = −ΔS ₁ M ₁ = ΔH ₁ Q ₁ ….

Therefore, the roll gap correction amount ΔS ₁ of the first stand is: ΔS ₁ =−Q ₁ /M ₁ ΔH ₁ ... In other words, the roll gap correction amount ΔS ₁ is calculated by the standard deformation resistance coefficient Q ₁ and the first stand's roll gap correction amount ΔS 1 . It is set based on the mill stiffness coefficient M ₁ and the entry side plate thickness deviation ΔH ₁ .

By the way, the deformation resistance coefficient of the part of the rolled material rolled by the first stand is the standard deformation resistance coefficient Q ₁
If so, as shown in Figure 1, the entrance side plate thickness deviation Δ
Even with the gap correction amount ΔS ₁ in addition to H ₁ , the thickness deviation on the exit side of the first stand should become zero as shown by point Z _B. However, the deformation resistance coefficient of an actual rolled material is not always the same for each part, and if the above-mentioned part of the rolled material is, for example, a skid mark part, the deformation resistance coefficient increases and the deformation as shown in Fig. 1 occurs. The resistance curve becomes Q′ ₁ . Therefore, the actual thickness of the rolled material at the exit from the first stand is determined by the actual deformation resistance curve, as shown in Figure 1.
h ₁ is the abscissa of the intersection Z _R between Q′ ₁ and the mill stiffness curve M _1-b . In other words, the exit side plate thickness deviation with respect to the target exit side plate thickness h _1B is Δh ₁ .

This exit plate thickness deviation Δh ₁ is calculated as follows using a known gauge meter formula.

Δh ₁ = ΔS ₁ + ΔP ₁ /M ₁ ... Here, ΔP ₁ is the actual rolling load P 1 measured by, for example, a load cell when the first stand is rolling the part of the rolled material that was actually measured by a _thickness gauge. This is the rolling load deviation from the standard rolling load _P1B .

On the other hand, as is clear from FIG. 1, the actual deformation resistance coefficient Q' ₁ , the actual exit plate thickness h ₁ , the input plate thickness H ₁ , and the actual rolling load P ₁ have the following functional relationship. That is, (H ₁ −h ₁ )Q' ₁ =P ₁ ... Therefore, ΔP ₁ = ∂P ₁ /∂Q ₁ ΔQ ₁ +∂P ₁ /∂H ₁ ΔH ₁ +∂P ₁ /∂h ₁ Δh ₁ ... becomes.

Here, ΔP ₁ : Load deviation of actual rolling load P ₁ with respect to standard rolling load P _1B .

ΔQ ₁ : Variation of actual deformation resistance coefficient Q′ ₁ with respect to standard deformation resistance coefficient Q ₁ .

ΔH ₁ : Inlet thickness deviation of the first stand.

Δh ₁ : Output plate thickness deviation of the first stand.

By substituting the formula into the above formula, the formula regarding ΔQ ₁ is determined as follows.

ΔQ ₁ =AΔP ₁ +BΔS ₁ +CΔH ₁ ... Here, A, B, C are A=1/∂P ₁ /∂Q ₁ (1−∂P ₁ /∂h ₁ /M ₁
)… B=∂P ₁ /∂h ₁ /∂P ₁ /∂Q ₁ … C=∂P ₁ /∂H ₁ /∂P ₁ /∂Q ₁ … In the above formula, each partial differential coefficient in the formula is It is determined by statistical processing using a host computer depending on the type of rolled material.

Next, control of the roll gap of the second stand will be explained with reference to FIG. 2, which illustrates the amount of correction of the roll gap of the second stand. In Figure 2, X is the same as in Figure 1,
Y is for explaining the roll gap correction amount of the second stand.

First, in the above equation, the rolling load deviation ΔP ₁ of the first stand, the roll gap correction amount ΔS ₁ of the first stand,
Calculate the variation ΔQ ₁ of the deformation resistance coefficient Q ₁ of the part of the rolled material calculated by substituting the entrance plate thickness deviation ΔH ₁ of the first stand, and calculate the part of the rolled material for which this variation ΔQ ₁ was calculated. The standard deformation resistance coefficient Q′ ₂ in the second stand when the second stand performs rolling is calculated by the following formula.

Q' ₂ =Q ₂ +ΔQ ₁ Q ₂ /Q ₁ ... In the above formula, the coefficient Q ₂ /Q ₁ is for taking into account the change in the deformation resistance coefficient due to rolling. Therefore, the variation ΔQ ₂ of the deformation resistance coefficient with respect to the standard deformation resistance coefficient Q ₂ when rolling the part of the rolled material in the second stand is (ΔQ ₁ Q ₂ /Q ₁ ).

On the other hand, the entrance side plate thickness H ₂ of the above-mentioned rolled material portion in the second stand is equal to the exit side plate thickness h ₁ of the first stand.

In addition, in Fig. 2, H _2B is the target inlet thickness of the second stand (the target outlet thickness of the first stand h _1B
), h _2B is the target outlet plate thickness of the second stand, S _2B is the standard roll gap of the second stand, S ₂ is the corrected roll gap of the second stand, ΔS ₂ is the correction amount of the roll gap of the second stand , Q _2-a , Q _2-b are deformation resistance curves with standard deformation resistance coefficient Q ₂ , M _2-a ,
M _2-b and M _2-c are mill stiffness curves having a mill stiffness coefficient M ₂ of the second stand.

Therefore, the actual deformation resistance curve Q' 2 having the actual deformation resistance coefficient Q' ₂ at the second stand of the above-mentioned part of the rolled material and passing through the point H ₂ indicating the actual entry side plate thickness, and the actual deformation resistance curve Q' ₂ of the second stand With respect to the standard roll gap S 2B of the second stand, as shown in Fig. 2, so that the abscissa of the intersection point W with the mill stiffness curve M _{2-c becomes} the target exit side plate thickness h _2B of the second stand. If ΔS ₂ is corrected to S ₂ , even if the deformation resistance coefficient changes, it will be taken into account and the exit side plate thickness of the second stand will be adjusted to the target exit side plate thickness h.
It can be _2B .

The roll gap correction amount ΔS ₂ is calculated as follows.

In Fig. 2, the standard deformation resistance curve Q _2-b passes through point H ₂ indicating the actual entrance plate thickness H ₂ of the second stand.
and a perpendicular line erected at point _h2B indicating the target outlet plate thickness _h2B , the intersection point is V, and the mill stiffness curve _M2 having the mill stiffness coefficient M2 of the second stand passes through the intersection point _V.
Let the intersection of _−b with the abscissa be S _2i . Then, the difference between the ordinates of the points V and W is defined as ΔP _2q .

Then, as can be seen from Figure 2, ΔP _2q = (H ₂ - h _2B ) Q' ₂ - (H ₂ - h _2B ) Q ₂ = (H ₂ - h _2B ) (Q' ₂ - Q ₂ ) = (H ₂ - h _2B ) ΔQ ₂ ... On the other hand, if the distance between the point S ₂ indicating the corrected roll gap of the second stand and the above point S _2i is ΔS _2q , then the second
As is clear from the figure, ΔP _2q = M ₂ · ΔS _2q ... From the above formula and formula, when ΔP _2q is eliminated, M ₂ ΔS _2q = (H ₂ − h _2B ) ΔQ ₂ ΔS _2q = (H ₂ − h _2B )/M ₂ ΔQ ₂ ... On the other hand, in FIG. 2, the distance ΔS _2B between the point S _2i and the point S _2B is ΔS _2B =Q ₂ /M ₂ ΔH ₂ ....

Also, since −ΔS ₂ =ΔS _2q +ΔS _2B …, by substituting the formula and formula into the equation, −ΔS ₂ =Q ₂ /M ₂ ΔH ₂ +ΔQ ₂ /M ₂ (H ₂ −h _2B
)... On the other hand, as can be seen from Figure 2, H ₂ = H _2B + ΔH ₂ ....

Substituting the formula into the above formula and rearranging it, −ΔS ₂ =Q ₂ /M ₂ ΔH ₂ +ΔQ ₂ /M ₂ (H _2B +ΔH ₂ −
_h2B ) = _{Q2 / M2ΔH2} + _ΔQ2 / _M2 ( _H2B − _h2B )+Δ
Q ₂ /M ₂ ΔH ₂ ... =Q ₂ +ΔQ ₂ /M ₂ ΔH ₂ +ΔQ ₂ /M ₂ (H _2B −h
_2B ) =Q' ₂ /M ₂ ΔH ₂ +ΔQ ₂ /M ₂ (H _2B −h _2B )...
becomes.

Also, by substituting ΔH ₂ =Δh ₁ into the equation, −ΔS ₂ =Q′ ₂ /M ₂ Δh ₁ +ΔQ ₂ /M ₂ (H _2B −
h _2B )... becomes.

In the above equation, the first term is the roll gap of the second stand based on the actual deformation resistance coefficient Q' ₂ for the entrance side plate thickness deviation ΔH ₂ of the second stand (the exit side plate thickness deviation Δh ₁ of the first stand). The second term in the above formula is the correction of the roll gap of the second stand by the variation ΔQ ₂ of the deformation resistance number with respect to the standard reduction amount of the second stand {(H _2B − h _2B )}. It is quantity. Therefore, the second term in the above equation indicates the amount of correction of the roll gap of the second stand that must be made when the deformation resistance coefficient changes, even if the thickness deviation on the entrance side of the second stand is zero. be.

In this way, the roll gap correction amount ΔS ₂ of the second stand takes into account the local variation in the deformation resistance coefficient of the rolled material, so the exit plate thickness deviation Δh ₂ of the second stand becomes zero or small.

Furthermore, the plate thickness is controlled in the third and fourth stands in exactly the same manner as in the first and second stands, and the actual deformation resistance coefficient is calculated from the entrance and exit side plate thickness deviations and the actual rolling load deviation of the third stand. Based on this, the roll gap of the fourth stand is corrected.

Of course, in this plate thickness control method, control that takes into account the variation in the deformation resistance coefficient described above is performed for each longitudinal portion of the rolled material.

FIG. 3 shows a block diagram of an apparatus used to carry out the method of the above embodiment.

In Fig. 3, 1 is the rolled material, 2 to 4 are the first to
a third stand; 5-7 are hydraulic cylinders that control the roll gaps and rolling loads of the first to third stands; 11-13 are load cells that detect the rolling loads of the first to third stands; 16; 17 is each X-ray thickness gauge for measuring the entrance side plate thickness of the first stand 2 and the third stand 4; 18 and 19 are the first stand 2;
and pulse generators for detecting the rolling speed of the second stand 3; reference numerals 21 to 23 are amplifiers for outputting to the hydraulic cylinders 5 to 7;

Further, 31 indicates the characteristics of the X-ray thickness meter 16, where 32 is a first-order delay element with a time constant _T1 , and 32 is a time delay element.
33 is a dead time element indicating the transfer time until a part of the rolled material is sent from the X-ray thickness gauge 16 to the first stand 2, and 34 corresponds to the above formula, and calculates the roll gap correction amount ΔS ₁ of the first stand 2. It is an element that

Further, 35 indicates the characteristics of the load cell 11, and 36 is a first-order delay element with a time constant T _{2 and} a time delay element.

Further, 37 is an element for calculating the above formula, 38 is an element for calculating the above formula, and 39 is an element for calculating the above formula, and these elements 37, 38, 3
From the summing point 40 where the output of 9 is input, the deformation resistance coefficient Q ₁ of the rolled material in the first stand 2 is inputted.
Outputs the variation ΔQ ₁ .

Further, 41 is an element indicating the change in the deformation resistance coefficient due to rolling, and 42 corresponds to the first term of the above equation, and is the roll gap based on the entry side plate thickness deviation ΔH ₂ and the actual deformation resistance coefficient Q' ₂ . An element for calculating the correction amount, 43 corresponds to the second term of the above equation, and is an element for calculating the roll gap correction amount based on the variation ΔQ ₂ of the deformation resistance coefficient and the reference reduction amount (H _2B −h _2B ). , 44 corresponds to the above equation, and 45 is a time delay element for calculating the roll gap correction amount ΔS ₂ of the second stand 3. While calculating the transfer time to the second stand 3, a signal giving the roll gap correction amount ΔS ₂ is output to the amplifier 22.

In this way, although not shown, the roll gap is controlled in exactly the same way up to the fifth stand, taking into account local fluctuations in the deformation resistance coefficient.

In addition, in Fig. 3, K ₀ to K ₁₀ are gain, S
is the Laplace operator, l ₁ to _{l 3} are the transfer delay times, and 5
1 and 52 are proportional/integral elements for the third stand 4.

Examples of data obtained when the method of this embodiment is executed using the above apparatus are shown in FIGS. 4 and 5.

In Fig. 5, A ₁ and A ₂ are the areas when the control method according to the present invention takes into account local fluctuations in the deformation resistance coefficient, and B is the area when the conventional control method that does not take into account local fluctuations in the deformation resistance coefficient is performed. Area in case C
is the threading area, and D is the tailing area.

From this, it can be seen that when the method of the present invention is implemented, the plate thickness accuracy is not affected by local fluctuations in the deformation resistance coefficient and is greatly improved.

As is clear from the above explanation, the plate thickness control method for a cold tandem rolling mill of the present invention measures the inlet plate thickness of the upstream stand with a thickness gauge, calculates the inlet thickness deviation from the target inlet plate thickness, The roll gap when the upstream stand rolls the part of the rolled material for which the entry side plate thickness deviation has been calculated is set based on the above entry side plate thickness deviation so that the exit side plate thickness of the upstream stand becomes the target exit side plate thickness. While correcting and setting the deformation resistance based on the deformation resistance and the mill constant of the upstream stand, the rolling load deviation from the standard rolling load of the actually measured rolling load when the upstream stand rolls the part of the rolled material is calculated. At the same time, the deviation of the exit side plate thickness of the upstream stand from the target exit side plate thickness is calculated using a so-called gauge meter formula, and then the variation in the deformation resistance of the rolled material portion is calculated as the input side plate thickness deviation,
The actual deformation resistance is calculated based on the above rolling load deviation and the above exit plate thickness deviation, and then the roll gap when the downstream next stand rolls the part of the rolled material is calculated based on the above actual deformation resistance and the above upstream plate thickness deviation. Since it is set based on the exit thickness deviation of the side stand, the mill constant of the downstream next stand, and the standard reduction amount, the fluctuation of deformation resistance is taken into account, and the exit side thickness of the downstream next stand becomes approximately the target thickness. , Therefore, the thickness accuracy of the rolled material can be increased.

[Brief explanation of the drawing]

Figures 1 and 2 are graphs explaining the basic principle of this invention, Figure 3 is a block diagram of an apparatus using an embodiment of this invention, and Figures 4 and 5 show experimental results of the method of the above embodiment. These are each graph shown. 1... Rolled material, 2... First stand, 3... Second stand, 4... Third stand, 5, 6, 7...
...Hydraulic cylinder, 11, 12, 13...Load cell.

Claims (1)

[Claims] 1. A plate thickness control method in tandem rolling using multiple rolling mills, in which the target plate thickness and standard deformation resistance of the rolled material are set at the entrance and exit sides of each stand, and then at least one upstream side The entrance side plate thickness of the stand is measured with a thickness gauge, the entrance side plate thickness deviation from the target input side plate thickness is calculated, and the part of the rolled material for which the input side plate thickness deviation is calculated is rolled by the upstream stand. While correcting and setting the roll gap during the process based on the input side plate thickness deviation, reference deformation resistance, and mill constant of the upstream stand so that the outlet side plate thickness of the upstream stand becomes the target outlet plate thickness,
The actual measured rolling load when the upstream stand rolls a portion of the rolled material with respect to the standard rolling load when the upstream stand rolls a rolled material having a target entrance plate thickness and standard deformation resistance. In addition to calculating the rolling load deviation, the deviation of the exit side plate thickness of the upstream stand from the target exit plate thickness is calculated based on the rolling load deviation, the roll gap correction amount, and the mill constant of the upstream stand. Next, calculate the actual deformation resistance by calculating the variation in deformation resistance of the rolled material portion based on the input side plate thickness deviation, the rolling load deviation, and the exit side plate thickness deviation,
Next, the roll gap when the downstream next stand rolls the part of the rolled material is determined based on the actual deformation resistance, the exit plate thickness deviation of the upstream stand, the mill constant of the downstream stand, and the standard reduction amount. 1. A method for controlling plate thickness of a cold tandem rolling mill, characterized in that the plate thickness is corrected and set based on the following information so that the outlet plate thickness of a downstream next stand becomes a target plate thickness.