KR100398765B1 - Method of controlling board thickness, calculating passing schedule, and board thickness controller for continuous rolling machine - Google Patents

Abstract

By formulating the influence on the tension when the tuning rate α is changed, a plate thickness control method and a plate thickness control apparatus of a continuous rolling mill capable of facilitating adjustment of the tuning rate α are obtained.

An entrance plate thickness deviation detection step (11) for finding the entry plate thickness deviation immediately before the rolled material enters the rolling mill, an exit plate thickness deviation detection step (12) for determining the exit plate thickness deviation immediately after the rolled material passes the rolling mill, Tension fluctuation between the rolling mill according to the advance rate variation calculation process to calculate the advance rate variation Δfs of the plate speed from the plate thickness deviation ΔH and the plate thickness deviation Δh and the advance rate variation Δfs, the plate thickness deviation ΔH and the plate thickness deviation Δh. It has a tuning rate adjustment process 10 which adjusts the tuning rate regarding suppression.

Description

Plate thickness control method, pass schedule calculation method and plate thickness control device of continuous rolling mill {METHOD OF CONTROLLING BOARD THICKNESS, CALCULATING PASSING SCHEDULE, AND BOARD THICKNESS CONTROLLER FOR CONTINUOUS ROLLING MACHINE}

The present invention relates to a continuous rolling mill that performs sheet rolling in a plurality of continuous rolling mills, and more particularly, to a sheet thickness control method, a pass schedule calculation method, and a sheet thickness control apparatus of a continuous rolling mill in consideration of suppression of tension fluctuations between the rolling mills. will be.

Fig. 6 is a block diagram showing an example of plate thickness control of the most typical gauge metric method among the plate thickness control methods.

The operation of this sheet thickness control method is briefly described below.

In FIG. 6, the pressing position S _A for controlling the pressing position toward the rolling mill 2 from the pressing apparatus 1 is designated.

At this time, T _P is a time constant indicating the speed when the response of the pressure reducing device 1 is approximated, and τ represents an unnecessary time at that time.

The rolling load F _A is determined by the pressing position S _A and the wheat constant M indicated on the rolling mill 2.

Then, the blood rolled material is rolled to a rolling load F _A and the plate thickness h + Δh by a factor of three plastic coefficient Q + ΔQ of the rolling mill (2).

At this time, as a disturbance factor of the rolling phenomenon, there is a grain thickness variation ΔH of the rolled material and a plastic change ΔQ due to temperature.

The gauge thickness method of the gauge meter system is to eliminate the variation Δh of the exit plate thickness h + Δh of the rolled material due to these variations ΔH and ΔQ.

The following operation is explained.

Such gauge meter type plate thickness control device temporarily operates the switch 6 at the timing immediately after the rolling of the rolled material is started, stores the reference pressure position S _AO in the reference pressure position recording device 4, and loads the reference rolling load. The storage device 5 stores the reference rolling load F _AO .

Subsequently, the pressure reduction device S _{A obtained} by calculating the difference ΔS _A between the rolling reduction device S _A and the reference lowering position S _AO , the difference ΔF _A between the rolling load F _A and the reference rolling load F _{AO by} the tight constant M, the tuning factor α and the gain G The pressing position correction amount [Delta] S ^* for controlling the pressing position S _A of (1) so as to eliminate the plate thickness deviation [Delta] h of the rolled material is output.

ΔS ^* is calculated by the following equation.

[1]

Theoretically, it is considered that the maximum effect can be obtained by reducing the exit plate thickness deviation Δh when the tuning ratio α = 1 and the gain G = 1.

However, if the rolling reduction position is operated by bringing the tuning rate α close to 1, the rolling speed of the rolling mill 2 is fluctuated, and the tension between the rolling mills is greatly disturbed, and the safety operation is hindered. The method of adjusting the tuning rate alpha as large as possible is taken.

For example, Japanese Patent Application Laid-Open Publication No. 4-210805 and Japanese Patent Application Laid-Open No. 6-71616 are two methods for controlling sheet rolling. In order to improve the plate thickness accuracy, the transfer timing of the plate thickness data and the calculation method of the pressed position are studied.

In any case, the control limit and the tuning rate are not controlled in consideration of the boardability (the suppression of the tension fluctuation).

In practice, it is necessary to control the plate thickness after considering the influence on tension.

In the conventional method of controlling the plate thickness of the continuous rolling mill as described above, the influence on the tension when the tuning rate α is changed is not formulated, and the tuning rate α is adjusted by trial and error after seeing the rolling situation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the method for controlling the thickness of a continuous rolling mill, which can facilitate the adjustment of the tuning rate α by formulating the influence on the tension when the tuning rate α is changed, and It is an object to obtain a sheet thickness control device.

In the plate thickness control method of the continuous rolling mill according to the present invention, the plate thickness control method of the gauge meter method of the continuous mill, the side plate thickness deviation detection step for finding the side plate thickness deviation immediately before the rolling material enters the rolling mill, and the rolled An exit plate thickness deviation detection step for determining the exit plate thickness deviation immediately after passing the rolling mill; an advance rate variation calculation step for calculating the advance rate variation of the plate speed from the deviation of the plate thickness and the exit plate thickness; And a tuning rate adjusting step of adjusting a tuning rate for suppressing tension fluctuations between rolling mills according to the plate thickness deviation and the outgoing plate thickness deviation.

Moreover, the lower limit calculation process of calculating the lower limit of a tuning rate before rolling of a to-be-rolled material by using the optimum value of the tuning rate at the time of prioritizing the tension suppression which can be deduced by approximating the characteristic of a rolling device to an integer, and assuming a plasticity coefficient. In addition, the tuning rate adjustment step uses a lower limit to adjust the tuning rate even before rolling of the rolled material.

The lower limit value calculating step calculates the lower limit value of the tuning rate of the plurality of rolling mills, and the tuning rate adjusting step sets the reference value of the tuning rate for keeping the tension load on the plurality of rolling mills dependent on the given pass schedule. Moreover, the tuning rate of many rolling mills is calculated | required by adding the same coefficient to a reference value.

The tuning rate adjustment step adjusts the tuning rate during rolling by using the plasticity coefficient obtained from the reference rolling load memorized immediately after the rolling start.

Moreover, the pass schedule calculation method which concerns on this invention is a calculation method of the pass schedule of a continuous rolling mill, Comprising: A side plate thickness deviation detection process which calculates the side plate thickness deviation just before a rolled material enters a rolling mill, and after a rolled material passes a rolling mill. The plate thickness deviation detection step for determining the plate thickness deviation of the plate, the advance rate variation calculation step for calculating the variation rate of plate speed from the plate thickness deviation and the plate thickness deviation, and the approximate characteristics of the pressing device N set for the condition of the tuning rate of all the rolling mills according to the optimum value of the tuning ratio, the side plate thickness, and the exit plate thickness, and the actual side plate thickness deviation of one rolling mill. It has a pass schedule calculation process that calculates a pass schedule that simultaneously meets the conditions for achieving the target plate thickness deviation of the rolling mill. It is.

In addition, the plate thickness control apparatus of the continuous rolling mill according to the present invention is a gauge thickness control device of the gauge of the continuous rolling mill, the side plate thickness deviation detection means for finding the side plate thickness deviation immediately before the rolling material enters the rolling mill, Outgoing plate thickness deviation detection means for finding out the outgoing plate thickness deviation immediately after the rolling material passes through the rolling mill, Advance rate variation calculating means for calculating the advance rate variation of the plate speed from the outgoing plate thickness deviation and outgoing plate thickness deviation, And adjusting means for adjusting the tuning rate with respect to the tension variation between the rolling mills in accordance with the deviation of the side plate thickness and the exit plate thickness.

In addition, the lower limit calculation means for calculating the lower limit of the tuning rate before rolling of the rolled material by using the optimum value of the tuning rate when giving priority to the tension suppression derivable by approximating the characteristics of the pressing device to an integer, In addition, the tuning rate adjusting means adjusts the tuning rate even before rolling of the rolled material by using the lower limit value.

The lower limit value calculating means calculates the lower limit value of the tuning rate of the plurality of rolling mills, and the tuning rate adjusting means sets the reference value of the tuning rate for making the tension loads constant for the plurality of rolling mills depending on the pass schedule given. The tuning rate of a plurality of rolling mills is obtained by adding the same coefficient to the reference value.

The tuning rate adjusting means adjusts the tuning rate during rolling by using the plasticity coefficient obtained from the reference rolling load memorized immediately after the rolling start.

1 is a schematic diagram showing a tension model of the rolling period

Fig. 2 is a schematic diagram showing deviations of the entry and exit plate thicknesses of the rolling mill.

3 is a graph showing the relationship between the deviation of the thickness of the plate and the variation of the advance rate;

4 is a configuration diagram showing Embodiment 1 of the present invention.

5 is a block diagram modified from the block diagram of FIG.

6 is a block diagram showing an example of a plate pressure control of a gauge meter method;

<Description of the symbols for the main parts of the drawings>

1: reduction device 4: reference pressure position storage device

5: reference rolling load storage device 6: switch

10: tuning rate α adjusting device (tuning rate adjusting process, tuning rate adjusting means)

11: measuring instrument (side plate thickness deviation detection step, side plate thickness deviation detection means)

12: Measuring mechanism (outside plate thickness deviation detection process, outgoing plate thickness deviation detection process)

13: Load cell ΔH: Gradient plate thickness deviation Δh: Outgoing plate thickness deviation Δfs: Advance rate variation

Embodiment 1

FIG. 1: is a schematic diagram when modeling the tension between the rolling mill i of the code | symbol 8, and the rolling mill i + 1 of the code | symbol 9. As shown in FIG.

The tension σ of the rolling period can be considered to be proportional to the integral of the difference between the exit plate speed V ⁱ _out of the rolling mill ⁱ and the side plate speed V ^{i + 1} _in of the ^{i + 1} .

In other words

[Number 2]

The plate speed V ⁱ _out can be expressed by the following relationship with the roll speed V ⁱ _rol of the rear mill.

[Number 3]

V ⁱ _out = V ⁱ _rol (+ fs ⁱ ) ..... (3)

Here, fs ⁱ is called the advanced rate, and displays the output side speed V ⁱ _out rate of increase of the roll speed V ⁱ _rol.

Roll speed V ⁱ _rol When assuming that a control such that a constant fluctuations Δfs ⁱ increases in fs ⁱ increase in the fluctuation of the output side speed V ⁱ _out t from the equation (3), and moves in the direction in which the tension σ disturbance .

Likewise, in the rolling mill i + 1, the board speed V ^{i + 1} _out can be expressed by the following relationship.

[Number 4]

In addition, when the standing plate | board speed V ^{i + 1} _in of rolling mill i + 1 is represented by the advance rate fs ^{i + 1} , it is determined by the mass flow storage side.

[Number 5]

Here, H ^{i + 1} and h ^{i + 1} are the side plate thickness and the exit plate thickness of the rolling mill i + 1, respectively.

Assuming that control is carried out so that the roll speed V ⁽⁺⁾ _rol is constant (5), the equation also depends on the variation of H ^{i + 1} and h ^{i + 1} , but in general, the variation Δfs ^{i + 1} of fs ^{i + 1} Increasing increases the variation of V ^{i + 1} _m and moves in the direction in which the tension σ is disturbed.

Here, the conditions for reducing the advance rate variation Δfs are obtained.

The advance rate fs is determined by the entry thickness H and the exit thickness h using the simplest approximation.

[Jos 6]

Can be displayed.

If the deviation of the largest part of the side plate thickness deviation is ΔH and this is the remaining horseshoe after passing through the rolling mill (Fig. 2), the absolute value of the change in the advance rate | Δfs |

[Jos 7]

(Process of calculating the rate of change of the rate of change, a means of calculating the rate of change of the rate of change).

Therefore, from (7),

When ΔH · h−Δh · <0, Δh: small → | Δfs |: small → tension variation: small When ΔH · h-Δh · H> 0, Δh: large → | Δfs |: small → tension variation: small.

3 shows an example of the relationship between the outgoing plate thickness deviation Δh and the advance rate variation Δfs.

Use this principle to adjust the magnitude of the tuning rate α.

Fig. 4 is a block diagram showing one embodiment of the principle of tuning rate α adjustment in the present invention.

In Fig. 4, reference numeral 10 denotes an adjusting device (tuning rate adjusting step tuning rate adjusting means) of the tuning rate α newly introduced in the present invention.

Reference numeral 11 denotes a measuring mechanism for directly measuring plate thickness deviation ΔH immediately before the rolled material enters the rolling mill (side plate thickness deviation detecting step, side plate thickness deviation detecting means), and 12 is a plate immediately after the rolled material passes the rolling roll. It is a measuring mechanism (outside plate thickness deviation detection process, outgoing plate thickness deviation detection means) which measures thickness deviation (DELTA) h directly.

In the tuning rate α adjusting device 10, the plate thickness deviations ΔH and Δh obtained by the measuring mechanisms 11 and 12, and from the set side plate thickness H and the exit plate thickness h of the pass schedule are set.

[Jos 8]

K = ΔH · h-Δh · H ........ (8)

To calculate. When K <0 in (7),

Δh: small → ｜ Δfs ｜: small → tension fluctuation: small

Therefore, when the tuning ratio α is increased to reduce the outgoing plate thickness deviation Δh, the tension variation Δα is decreased, so that the adjustment factor C> 0 is added to the tuning ratio α.

On the other hand, when K> 0,

Δh: large → ｜ Δfs ｜: small → tension fluctuation: small

Therefore, when the tuning ratio α is reduced to increase the outgoing plate thickness deviation Δh, the tension variation Δσ becomes small.

This is contrary to the original purpose of minimizing the outgoing plate thickness variation of the final rolling mill, and α should be as large as possible.

Therefore, the coefficient determined according to the tension variation Δσ from the viewpoint of safety operation by suppressing the tension variation.

f (Δσ)> 0

Α is determined by the method of subtracting from the tuning rate α.

By the above algorithm, it is not necessary to determine the tuning rate α by trial and error after seeing the shape of tension change in rolling as in the prior art, and in some cases, increasing the tuning rate α also includes the viewpoint of safety operation. In this way, an optimum tuning ratio α can be obtained to obtain the maximum effect.

In the present embodiment, the plate thickness deviation ΔH immediately before the rolled material enters the rolling mill and the plate thickness deviation Δh immediately after the rolled material passes through the rolling roll (side plate pressure deviation detection means, side plate pressure deviation detection means). Although it is detected by the measuring mechanisms 11 and 12, plate | board thickness deviation (DELTA) H and plate | board thickness change (DELTA) h are made into the physical load, such as the rolling load from the load cell 13, the reduction position S from the reduction device 1, etc. It may be calculated indirectly.

Embodiment 2

In the following, by using the formula (7), the optimum value of the tuning rate α in the case where priority is given to the suppression of tension fluctuation is theoretically determined.

FIG. 5 is a view in which the block diagram of the gauge metric plate thickness control of FIG. 6 is modified and rewritten.

Formulating the outgoing plate thickness deviation Δh and the reducing position change ΔS _A

[Jos 9]

Δh = (ΔH-ΔS _A ) G _P + ΔS _A ..... (9)

[Jos 10]

ΔS _A = H _P [ΔS _A -G {ΔS _A + αG _P (ΔH-ΔS _A )}] .. (10)

here,

[Jos 11]

[Joe 12]

to be. From equation (10)

[13]

Therefore, substituting equation (13) into equation (9)

[Jos 14]

Δh = A (s; α) ΔH ...... (14)

[Joe 15]

Substituting equation (14) into equation (7)

[Joe 16]

Get

However, the optimum value of α is tuned to make the tension variation Δα the smallest.

[17]

Δfs (α) = 0 ........ (17)

Is the point chill α.

Assuming that this is HP ≒ HC (integer), the relationship between the plate thickness deviation ΔH and the chilled α that does not depend on the plate thickness deviation Δh

[Wed 18]

Get

Here, when H _P indicates the characteristic of the response of the pressing device 1 and approximates it as the constant H _C , for example, the maximum command value output by the plate thickness controller to the maximum deviation ΔH ^MAX of the material to be rolled. If the ratio of the actual maximum output value ΔS ^Max _A to ΔS ^{* Max} is H _C , the chilled α reflecting the characteristics of the rolling mill can be obtained.

Assuming the plasticity coefficient Q before rolling, and using the formula (18) to obtain the chilled α, the value of the tuned α of the tuning factor α can be determined so as to minimize the tension variation Δα, and at the same time, The lower limit chilled α can be grasped before rolling (lower limit calculation step, lower limit calculation means).

This makes it possible to avoid the case where K <0 of the first embodiment and to shorten the tuning time.

Embodiment 3

In addition, if the chill coefficient α ⁱ is obtained for each mill i using the (18) yarn before the rolling, the load balance of the tuning rate α with respect to the tension variation Δα depending on the given pass schedule can be known. .

A form in which the same coefficient C> 0 is applied to the tuning rate α in each rolling mill i on the basis of the chilled α ⁱ .

[Jos 19]

α ⁱ = α ^-i + C ...... (19)

By adjusting the furnace tuning rate α, it is possible to suppress the inclination of the tension variation in each rolling period.

Embodiment 4

In Embodiment 3 described above, when the filter α ⁱ for each rolling mill i is obtained using the formula (18) before rolling, the plasticity factor Q should be assumed, but in general, the plasticity factor Q is a relation with the rolling load F. ,

[Jos 20]

Can be displayed.

Using the relational formula, using the coefficient of plasticity Q _O obtained by substituting the reference rolling load F _AO stored in the reference rolling load storage device (not shown) immediately after the start of rolling into the equation (20), When the adjustment of the tuning factor α ^i, it is possible to perform more accurate adjustment of the tuning factor α ⁱ to inhibit pyeonjeung the tension variations of the respective rolling period.

Embodiment 5

Hereinafter, Embodiment 5 of this invention is described.

The load balance of the tuning ratio α with respect to the variation Δσ existing in the pass schedule given by the equation (18) can be seen.

Equation (18) is a function of the entry plate thickness H and the exit plate thickness h. Thus, the path schedule for obtaining a uniform load against the tension variation Δσ can be obtained using these equations.

In other words, replacing (18) with respect to each rolling mill i

[Jos 21]

Becomes In addition, (14), (15)

[Jos 22]

to be.

Thus, the load on the tension fluctuation Δα is made uniform.

[Wed 23]

α ^-1 = α ^-2 = ... = α ^-N (N: total number of rolling mill) ..... (23)

As a result, one combination {tilter h ⁱ } is selected from the following viewpoints among the combination {h ⁱ } of h ⁱ which satisfy | fills Formula (21).

By the formula (21), the tilter α ⁱ is obtained from {tilter h ⁱ },

[Wed 24]

α ⁱ = α ^-1 + c ... (24)

By substituting α ⁱ into the equation (22), the exit plate thickness deviation Δh ⁱ with respect to the plate thickness deviation Δh ^i-1 of each rolling mill when the load is uniformly applied to the plate thickness control of each rolling mill can be obtained. have.

Therefore, {tiller h ⁱ } and C are determined with respect to the actual side plate thickness deviation ΔH ⁱ -Δh ^O of the rolling mill 1 such that the target exit plate thickness deviation Δh N of the rolling mill ^N is realized.

By using the above pass schedule setting method, it is possible to obtain a pass schedule obtained by distributing the load balance with respect to the tension variation Δ _a between the rolling mills.

In the plate thickness control method of the continuous rolling mill according to the present invention, the plate thickness variation step of determining the plate thickness deviation just before the rolled material enters the rolling mill by the gauge thickness method of the continuous mill, and the rolled material is the rolling mill. The exit plate thickness deviation process to find out the deviation of the exit plate thickness immediately after passing through; the advance rate variation calculation process to determine the advance rate variation of the plate speed from the exit plate thickness deviation and the exit plate thickness deviation; And a tuning rate adjusting step of adjusting a tuning rate for suppressing tension fluctuations during the rolling period in accordance with the deviation and deviation of the thickness of the exit plate.

For this reason, the optimum tuning ratio (alpha) for obtaining the maximum effect can be obtained.

Moreover, it becomes possible to formulate the influence on the tension at the time of changing the tuning rate (alpha), and can easily adjust the tuning rate (alpha).

In addition, the lower limit calculation step of calculating the lower limit of the tuning rate before rolling of the rolled material by using the optimum value of the tuning rate when priority is given to the suppression of tension that can be derived by investigating the characteristics of the pressing device as an integer. The tuning rate adjusting process uses a lower limit to adjust the tuning rate even before rolling of the rolled material.

Therefore, the case where K <0 can be avoided and the tuning time can be shortened.

The lower limit value calculating step calculates the lower limit value of the tuning rate of the plurality of rolling mills, the tuning rate adjusting step sets the reference value of the tuning rate for setting the tension load to a plurality of rolling mills depending on the given pass schedule. The same coefficient is added to the reference value to find the tuning rate of a plurality of rolling mills.

For this reason, the inclination of the tension variation in each rolling period can be suppressed.

Further, the tuning rate adjusting step adjusts the tuning rate during rolling by using the plasticity coefficient obtained by the reference rolling load memorized immediately after the rolling start.

For this reason, the tuning rate can be adjusted more accurately.

Moreover, the pass schedule calculation method which concerns on this invention is a calculation method of the pass schedule of a continuous rolling mill, Comprising: A side plate thickness deviation detection process which calculates the side plate thickness deviation immediately before a rolled material enters a rolling mill, and a rolled material immediately after passing a rolling mill. Derivation of the plate thickness deviation to find out the plate thickness deviation, the process of calculating the variation of the plate rate from the plate thickness deviation and the plate thickness deviation, When rolling N rolls for the condition that the tuning rate of all the rolling mills is constant according to the optimum value of the tuning ratio, the side plate thickness and the exit plate thickness when tension suppression is given, and the actual side plate thickness deviation of one rolling mill. Has a pass schedule calculation process that calculates a pass schedule that simultaneously meets the conditions for realizing the target plate thickness deviation It is.

For this reason, the pass schedule which disperse | distributed the load balance with respect to the tension fluctuation of each rolling period can be obtained.

In addition, the plate thickness control device of the continuous rolling mill according to the present invention is a gauge thickness control device of the gauge meter type of the continuous rolling mill, the side plate thickness deviation detection means for finding the side plate thickness deviation immediately before the rolling material enters the rolling mill, Outgoing plate thickness deviation detection means for determining the outgoing plate thickness deviation immediately after the rolling material passes through the rolling mill, Advance rate variation calculating means for calculating the advance rate variation of the plate speed from the outgoing plate thickness deviation and outgoing plate thickness deviation, and the advance rate variation And a tuning rate adjusting means for adjusting the tuning rate for suppressing the tension variation in the rolling period in accordance with the plate thickness deviation and the outgoing plate thickness variation.

For this reason, the optimum tuning ratio (alpha) for obtaining the maximum effect can be obtained.

In addition, it is possible to formulate the influence on the tension when the tuning rate α is changed, and the tuning rate α can be easily adjusted.

Moreover, the lower limit calculation means which calculates the lower limit of a tuning rate before rolling of a to-be-rolled paper by using the optimum value of the tuning rate at the time of prioritizing the tension suppression which can be derived by approximating the characteristic of a rolling apparatus to an integer, and assuming a plasticity coefficient. The tuning means adjusts the tuning rate even before rolling of the rolled material by using the lower limit value.

Therefore, the case of K <0 can be avoided and the tuning time can be shortened.

The lower limit value calculating means calculates the lower limit value of the tuning rate of the plurality of rolling mills, the tuning rate adjusting means sets the reference value of the tuning rate to keep the tension loads constant for a plurality of rolling mills depending on the given pass schedule. The tuning rate of a plurality of rolling mills is obtained by adding the same coefficient to the reference value.

For this reason, the bias of tension fluctuations in each rolling period can be suppressed.

The tuning rate adjusting means adjusts the tuning rate during rolling by using the plasticity coefficient obtained from the reference rolling load memorized immediately after the rolling start.

For this reason, the tuning rate can be adjusted correctly.

Claims (3)

A gauge thickness control method of a continuous rolling mill, comprising: a side plate thickness deviation process for finding the side plate thickness deviation immediately before the rolled material enters the rolling mill, and an exit side for the plate thickness deviation immediately after the rolled material passes the rolling mill. A plate thickness deviation detection step, a advance rate variation calculation step of obtaining advance rate variation of the plate speed from the side plate thickness deviation and the exit plate thickness deviation, the advance rate variation, the side plate thickness variation, and the side plate thickness variation And a tuning rate adjusting step of adjusting a tuning rate for suppressing tension fluctuations between the rolling mills. As a method of calculating the pass schedule of a continuous rolling mill, a side plate thickness deviation detection step for finding the side plate thickness deviation immediately before the rolled material enters the rolling mill, and an exit plate thickness deviation for the rolled plate plate thickness deviation immediately after the rolled material passes the rolling mill Tuning when priority is given to the detection step, the advance rate variation calculation step of obtaining the advance rate variation of the plate speed from the side plate thickness deviation and the exit plate thickness deviation, and the tension suppression derivable by approximating the characteristics of the pressing device to an integer. The target plate thickness deviation of the N rolling mills is realized against the conditions when the tuning ratio of all the rolling mills becomes constant according to the optimum value of the rate, the side plate thickness, and the exit plate thickness, and the actual side plate thickness deviation of one rolling mill. Continuous rolling, characterized in that it has a pass schedule calculation step of calculating a pass schedule that satisfies the conditions for Method of calculating pass schedules. A plate thickness control device of a gauge meter of a continuous rolling mill, comprising: a side plate thickness deviation detecting means for finding the side plate thickness deviation immediately before the rolled material enters the rolling mill, and an exit plate for which the rolled material finds the plate thickness deviation immediately after passing the rolling mill. Thickness deviation detecting means, advance rate variation calculating means for obtaining a variation in advance rate of plate speed from the side plate thickness deviation and the exit plate thickness deviation, and the advance rate variation, the side plate thickness variation, and the exit plate thickness variation. And a tuning rate adjusting means for adjusting a tuning rate for suppressing tension fluctuations between rolling mills.