JPH08206712A - Method for deciding pass schedule at time of changing flying thickness - Google Patents

Abstract

PURPOSE: To provide a method of deciding a pass schedule so as not to change the circumferential speed of roll as much as possible at the time of changing flying thickness in order to reduce the variation of tension between respective stands due to asynchronism in process for changing the set values of a roll gap and circumferential speed in flying thickness change at the joined point in the bar concerned and with the other bar. CONSTITUTION: In a tandem mill in which plural rolling stands are arranged in series, when a flying thickness change is executed in which the thickness is changed into the other product thickness during flying without stopping the rolling mill, the thickness on the respective outlet sides of a 1st stand and succeeding stands up to the (n-1)th stand is decided so as to correspond to the draft of their following stand up to the final n-th stand, respectively (The (n) is an integer of >=3).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a pass schedule in a tandem rolling mill composed of a plurality of stands, in which so-called running thickness change is performed to change the product thickness between runs.

[0002]

2. Description of the Related Art A cold rolling mill uses a cold rolling mill to change the thickness of a product by joining materials of the same or different steel types or sizes at the entrance side of the rolling mill and changing the product thickness between runs without stopping the rolling mill. It is already done in many facilities.

In recent years, a hot strip rolling technique has been applied to hot rolling mills as a means for improving yield and producing small lots. Hereinafter, the present invention will be described here by taking a change of the running plate thickness in the hot finish rolling machine as an example.

When changing the running plate thickness, the roll gap and roll peripheral speed set values of each stand of the tandem rolling mill are usually changed from the set values before the plate thickness change (hereinafter, referred to as A schedule) (hereinafter, Change to the set value of B schedule). At this time, it is important to reduce the off-gauge amount due to the change of the plate thickness, suppress the fluctuation of the tension between the stands as much as possible, and stably change the plate thickness. In order to reduce the amount of off-gauge, it is most effective to shorten the time required to change the roll gap and roll peripheral speed settings. However, shortening the change time of the set value acts in the direction of increasing the fluctuation of the tension between the stands, so there are various measures to improve the method of changing the set value and to improve the accuracy of the set value in order to reduce the fluctuation of the tension. Has been developed. Furthermore, as described in JP-A-56-11515, a method of associating a tension variation between stands with a mass flow change of each stand due to a change in running plate thickness and defining a rolling reduction amount of each stand Is also proposed. In this known example, the change ΔL of the strip loop amount between the stands when the running plate thickness is changed is represented by the equation (1), and the change of the loop amount is the rolling speed V _{R of the} stand and the change amount of the rolling train. It is designed to be uniquely determined as the product of Δr.

ΔL _{i-1, i} = V _Ri−1 · α · Δr _i-1 + V _Ri · (1-α) · Δr _i (1) where α is a coefficient and i is a stand number ( No.), and the rolling reduction r is a value given by the following equation (2).

[0006]

[Equation 1] That is, the rolling speed and the reduction rate change amount are inversely proportional to each other so that the change in the loop amount is small, the reduction rate change amount is increased in the upstream stand with a low rolling rate, and the reduction rate change amount is increased in the downstream stand with a high rolling rate. It is a way to make it smaller. Further, it is also described in this known example that the rolling ratio is changed so that the same amount of turbulence of mass flow is generated in each rolling stand.

[0007]

Table 1 shows the pass schedules before and after the thickness change, which is determined based on the method of the above-mentioned known example, when the running thickness is changed in the hot-finishing rolling mill having a 7-stand structure. .

[0008]

[Table 1] Here, the reduction rate change amount = | (B schedule reduction rate) − (A schedule reduction rate) |, and the downstream stand is made smaller in the reduction rate change amount.

When the F7 stand is used as a reference stand that does not change the roll peripheral speed, the relationship between the plate thickness change point position and the roll gap set value and roll peripheral speed set value of each stand is shown in Tables 2 (a) and (b). Shown in.

[0010]

[Table 2]

[0011]

[Table 3] However, subscript A: A schedule B: B schedule V _Rij : i stand roll peripheral velocity set value when the plate thickness change point reaches the j stand.

As shown in Table 2, the roll gap set value is changed from the A schedule value to the B schedule value at the timing when the plate thickness change point arrives. Further, the roll peripheral speed set value is changed at the timing when the plate thickness change point arrives, at the stand and the upstream stand. When the sheet thickness change point reaches the final F7 stand and the change of the roll gap and the roll peripheral speed is completed, the sheet thickness is changed from the A schedule to the B schedule.

As shown in FIG. 4, the roll gap and roll peripheral velocity set values are usually changed in the form of a linear function, and the change time is the same as that of each stand based on the principle of constant volume velocity.

FIG. 5 shows a simulation result of changing the running plate thickness shown in Table 1. In Fig. 5, (a) shows the deviation of the plate thickness on the delivery side of each stand, (b) shows the tension between stands, (c) shows the roll gap change amount of each stand, and (d) shows the roll peripheral velocity change amount of each stand. ing. As is clear from Fig. 5 (b), the tension between the stands fluctuates, and the tension fluctuation between the downstream stands is particularly large.

One of the causes for this is the difference in control response between the rolling down control device for controlling the roll gap and the speed control device of the main machine for controlling the roll peripheral speed. FIG. 6 shows the movement of the control amount when the reference value of the control system, which is represented by the first-order lag of the crossing angular frequency ω _c (rad / s), is changed to a tapered shape. That is, the controlled variable is the time constant 1 / ω with respect to the reference value.
It changes with a delay of _c (sec). In order to prevent tension fluctuations in the process of changing the roll gap and roll peripheral speed setting values, it is important that the actual change of roll gap and roll peripheral speed be started at the same timing and completed at the same time. However, the control response of the actual rolling position control device and the speed control device is generally more than doubled, and the change of the reference value of the rolling control device and the speed control device is started at the same timing and completed at the same time. However, the changes in the actual roll gap and roll peripheral speed do not match. This difference in response appears as a change in volume velocity and causes tension fluctuation.

Further, a set value change command for the roll gap and the roll peripheral speed is given according to the control pitch of the controller for giving a set value to the reduction control device or the speed control device and the delay of the transmission system of the controller and the reduction control device or the speed control device. They themselves cannot always be synchronized, which also contributes to tension fluctuations. That is, the cause of the tension fluctuation is the non-synchronization of the roll gap and the roll peripheral speed in the process of changing the set value, and it cannot be said that the tension fluctuation can be reduced by the method of the known example.

The running plate thickness can be changed not only by rolling coils of different product plate thickness from the same bar, but also by continuously joining bars of different thickness, width or steel type at the entry side of the finishing rolling mill. It is also done when you do. At this time, since there are usually two or more bars (for example, 20 bars) to be joined, simply changing the pass schedule between the bars to be joined to an appropriate value can change all the running plate thicknesses. Can not be done stably.

For example, when the bars A, B, and C are sequentially joined and the running distance is changed at each joining point, the tension fluctuation at the time of changing the running plate thickness at the joining point of the bars A and B is reduced. Bars B and B can decide the pass schedule, but Bar B
There is no guarantee that the pass schedule of the bar C can be determined so that the tension variation at the joint between the bar C and the bar C becomes small when the running plate thickness is changed. The constraint conditions are the capacity of the rolling mill drive motor, the speed setting range, the limitation of the rolling mill load, and the like.

Therefore, bar A and bar B, bar B and bar C
The pass schedules for bars A, B, and C must be determined in consideration of both changes in the running plate thickness.

According to the present invention, when changing the running plate thickness in the same bar or at the joining point with different bars, the tension between the stands caused by the non-synchronization in the process of changing the roll gap set value and the roll peripheral speed set value. It is an object of the present invention to provide a method of determining a pass schedule that does not change the roll peripheral speed as much as possible when changing the running plate thickness in order to reduce the fluctuation.

[0021]

According to a first aspect of the present invention, there is provided a tandem rolling mill having a plurality of rolling stands arranged in a tandem, in which the product sheet thickness is changed between running without stopping the rolling mill. When changing the plate thickness, either the second stand before the plate thickness change or after the plate thickness change to the final n-stand (n is an integer of 3 or more) should be equal to the other reduction ratio. From 1 stand (n-
1) Determine the stand-out plate thickness.

Further, the method according to claim 2 is a tandem rolling mill in which a plurality of rolling mills are arranged in tandem and steel sheets and the like are continuously rolled, and different product sheet thicknesses are obtained between runs without stopping the rolling mills. When changing the running plate thickness to be changed, it is necessary to make the rolling ratio equal to the rolling reduction from the second stand before the plate thickness change or after the plate thickness change to the final n stands (n is an integer of 3 or more). From the other first stand (n
-1) A first step of determining the stand-out side strip thickness, and a second step of predicting and calculating a rolling reduction, a rolling load, and a rolling power using the stand-in side and outlet-side strip thicknesses determined in the first step. And the constraint conditions of the rolling reduction, rolling load and rolling power of each stand preset from the viewpoint of equipment and operation, and the rolling reduction calculated in the second step, rolling load and rolling power calculation value. Compare them so that if these calculated values fall outside the constraint conditions, they will fall within the constraint conditions.
It has a third step of correcting the exit side plate thickness of the stand, and the processes of the second and third steps are sequentially carried out from the first stand to the downstream stand, and the rolling reduction is different before and after the plate thickness change. Limit the stand to the upstream stand.

Further, the method according to claim 3 is a tandem rolling mill in which a plurality of rolling mills are arranged in a tandem and steel sheets or the like are continuously rolled, and a bar is joined at the entry side of the tandem rolling mill to join the joining points. In the case of changing the running plate thickness at multiple positions on the rolled material including, and continuously different product thickness rolling, calculate the allowable range of the rolling reduction of each stand for the rolling before and after all the thickness changing points. And the first n stand (n stand (n
Is an integer greater than or equal to 3 and greater than j), the reduction ratio applicable to all rolling before and after the plate thickness change is selected from the reduction ratio allowable range calculated in the first step, and the first stand is used. To (j-1) a second step of selecting the rolling reduction of the stand from the rolling reduction range calculated in the first step for each rolling, and the rolling reduction of each stand selected in the second step. Based on the bar thickness and the first stand, the (n-1) stand side exit plate thickness is determined.
And at least make the rolling reduction of the stand downstream from the j stand equal before and after changing the running plate thickness.

[0024]

The operation of the present invention will be described below for each claim together with its principle.

First, the method according to claim 1 will be described by taking a hot-rolling mill having a seven-stand structure as an example. When the standard stand is the F7 stand, the following equations (3) and (4) are established from the law of constant volume velocity in the steady rolling state of the A schedule before the thickness change and the B schedule after the thickness change.

H _iA · V _RiA · (1 + f _iA ) = h _7A · V _R7A · (1 + f _7A ) (3) h _iB · V _RiB · (1 + f _iB ) = h _7B · V _R7B · (1 + f _7B ) (4 ) here, h _i: i stand delivery side thickness V _Ri: i stand roll peripheral velocity f _i: i stand forward slip subscripts a: a Schedule B: B Schedule (3), a reference stand from (4) F7 When the ratio of the i-stand roll peripheral speed to the roll peripheral speed of the stand is calculated, equations (5) and (6) are obtained.

[0027]

[Equation 2] Here, the roll peripheral speed ratios of the A schedule and the B schedule with respect to the reference stand are made equal. That is, (5)
Formula = (6) Formula This means that the roll peripheral speed ratio between adjacent stands, for example, the i stand and the (i + 1) stand,
This means that the A schedule and the B schedule are equal, as shown in equation (7).

[0028]

(Equation 3) Therefore

[0029]

[Equation 4] The fact that the roll peripheral speed ratio between adjacent stands before and after the plate thickness change is the same means that the speed change shown in Table 2 (b) is not necessary except for a slight change in the advance rate. Here, assuming that the stand-out side plate thicknesses of the A schedule are known, the stand-out side plate thicknesses of the B schedule satisfying the relationship of equation (7) are (5),
From formula (6), formula (8) is obtained.

[0030]

(Equation 5) Assuming that f _iA = f _iB f _7A = f _{7B in} formula (8), formula (8) is expressed by formula (10).

[0031]

(Equation 6) The rolling reduction ratio r _i of the i stand in the B schedule is (11)
As shown in the formula.

[0032]

(Equation 7) By substituting equation (10) into equation (11), as shown in equation (12), A and B
The schedule reduction rates are equal.

[0033]

(Equation 8) Since the reduction rate and the advance rate are almost proportional, there is no problem in the assumption of Eq. (9).

That is, when there is no degree of freedom in determining the bar thickness on the entry side of the finish rolling mill, each stand of the A and B schedules is subject to the same rolling reduction rate from the second stand to the final stand on the A and B schedules. Determine the outlet plate thickness.
For example, if the stand-out side plate thicknesses of the A schedule are known, the B schedule output side plate thickness is determined by the equation (10). As a result, the roll peripheral speed ratio of the second stand to the reference stand of the final stand becomes substantially equal in the A and B schedules, and it is possible to reduce variations in tension between stands when changing the running plate thickness.

This method is applied to the rolling schedule shown in Table 1. As an example, B schedule F2
Table 3 is obtained by making the stand-down ratios of F7 to F7 equal to the schedule A and determining the stand-out side plate thickness of schedule B.

[0036]

[Table 4] FIG. 7 shows the simulation results of changing the running plate thickness in Table 3. As is apparent by comparing the roll peripheral speed change amount of FIG. 7 (d) and the roll peripheral speed change amount of FIG. 5 (d), the roll peripheral speed change is small in FIG. 7 except for the F1 stand. Further, comparing the tensions of FIG. 7 (b) and FIG. 5 (b), the fluctuation is much smaller in FIG. 7, and the effect of the method according to claim 1 is clear.

Next, the method described in claim 2 will be described.

As shown in Table 3, when the method according to claim 1 is applied to change the running plate thickness between pass schedules having different ratios of bar thickness and product thickness, that is, total elongation, F1 is applied. The rolling reduction rate of the stand is different between the A schedule and the B schedule. This also applies to the method described in claim 1. That is, the difference between the total growth rates of the A schedule and the B schedule is absorbed by the F1 stand. Therefore, in some cases, the rolling reduction of the F1 stand may be a value that cannot be rolled.

As the constraint conditions that make rolling impossible, there are constraint conditions from the facility rating and operational constraints. The equipment ratings include the capacity of the main motor, the roll peripheral speed setting range (speed cone), and the maximum rolling load applied to the rolling mill. Further, as a constraint condition in operation, there is a case in which a rolling load per unit width or a rolling reduction itself is limited for the purpose of preventing deterioration of plate flatness and surface quality, and roughening of roll surface.

If the pass schedule is determined, the required rolling power, the rolling load to be generated, and the roll peripheral speed set value can be easily calculated using a known rolling model formula, and whether or not the above constraint conditions are exceeded. Can be determined.

On the other hand, as is apparent from FIG. 5B, the fluctuation in tension between the upstream stands is smaller than that in the downstream stands. This is because the loop amount is proportional to the roll peripheral velocity as shown in Eq. (1), and the equivalent Young's modulus of the rolled material is smaller in the upstream stand.

Based on this fact, when the F1 stand exceeds the constraint condition, the method according to the second aspect changes the exit side plate thickness of the F1 stand so as to be within the constraint condition, and the tension variation can be made by this change. It is absorbed by the upstream stand, which has a low property. FIG. 8 shows a processing procedure for determining the stand outlet side plate thickness of the B schedule by this method. First, the stand-out side plate thickness is determined by the first method or the second method.
(Step 101). Next, the rolling reduction, rolling load and rolling power of the F1 stand are calculated (steps 102 to 103). Next, it is judged whether or not the rolling reduction, rolling load, and rolling power of the F1 stand are within the limit values, and if the limit values are exceeded, the F1 stand exit side plate thickness is changed so as to be within the limit values. (Steps 104, 105). At this time, since the rolling reduction of the F2 stand changes, the rolling reduction, rolling load, and rolling power of the F2 stand are calculated (106, 103), and it is determined whether it is within the limit value like the F1 stand (104). F1 like this
The outlet plate thickness is sequentially corrected from the stand outlet plate thickness toward the downstream stand to absorb the excess of the constraint condition of the F1 stand.

Next, the method described in claim 3 will be described.

When the bars are joined on the entrance side of the finish rolling mill and the running plate thickness is changed at the joining point, the exit plate thickness and bar thickness of each stand are determined in consideration of all of a plurality of continuous pass schedules. FIG. 9 shows an example in which four bars A, B, C and D are joined to change the running plate thickness. In FIG. 9, ∇ indicates a joining point. The bars to be joined generally have different steel types, widths, and thicknesses, and product sheet thicknesses also differ. Although there is an optimal pass schedule for each of A, B, C, and D rolling, the method according to claim 3 determines a pass schedule in which tension fluctuations are reduced in all three running thickness changes.

Various methods for determining the pass schedule of the finish rolling mill have been proposed and implemented. Here, a method based on the idea of making the plate crown of the rolled material appropriate will be described.

I stand stand-out side plate crown C ₁ (%) is (1
It is expressed by equation (3).

[0047]

[Equation 9] Here, h _{Ci is the} plate width central part plate thickness h _{Ei is the} plate end part plate thickness.

The plate crown is an important product quality control item, and it is necessary to achieve the target plate crown. Furthermore, the difference between the entrance side plate crown and the exit side plate crown, that is, (C _i −
When C _{i- 1} ) exceeds a certain value, the plate flatness such as medium elongation or edge elongation is deteriorated. Therefore, it is important to control the plate crown of each stand within the range where the plate flatness is not deteriorated. The strip crown in actual rolling is affected by the roll profile and the amount of deflection, and usually becomes a function of the rolling load, roll crown, roll bending force, entry strip crown, etc., as shown in equation (14). C _i = α _pi・ P _i ＋ α _Ri・ C _Ri ＋ α _Bi・ F _Bi ＋ α _Hi・ C _i-1 (14) where P: Rolling load C _R : Roll crown F _B : Roll bending force α _p : For plate crown Rolling load influence coefficient α _R : Influence coefficient of roll crown on plate crown α _B : Influence coefficient of roll bending force on plate crown α _H : Incoming side plate crown genetic coefficient.

Further, the rolling load P _i is a function of the strip width, the deformation resistance of the rolled material, the inlet side plate thickness, the outlet side plate thickness, etc., as shown in equation (15), and can be calculated by a known rolling model formula.

P _i = f (B, K _mi , h _i-1 , h _i , ...) (15) where B is the plate width K m is the deformation resistance.

In consideration of the plate flatness, the pass schedule is determined on condition that the exit side plate crown of each stand is made equal to the product target plate crown. Specifically, Eqs. (14) and (15)
The equations are made simultaneous, and the rolling load P _i and the entrance side plate thickness h _{i-1 at} which the stand outgoing side plate crown becomes the product target plate crown are determined. By sequentially performing this from the final F7 stand to the F2 stand, the exit side plate thicknesses of the F1 to F6 stands can be determined. At this time, the roll bending force F _Bi of the formula (14) is the operation end for controlling the strip crown, and the rolling load P _i and the entry side strip thickness h _{i- at} which the strip crown C _i becomes the target strip crown depending on the set value of F _{Bi. 1} will be different. That is, it is possible to obtain the stand-out side plate thickness corresponding to the upper limit value and the lower limit value of the roll bending force F _Bi , and thus the range of the reduction ratio that each stand can take is obtained. Here, only the roll bending force is used as the operating end for controlling the plate crown, but the number of operating ends has been increasing in recent years, and the range of reduction rate that can be taken by combining them is expanded.

In FIG. 10, w and x are curves showing the range of reduction rates that can be taken for each stand. The curve y is the upper limit value of the rolling reduction ratio limited by the capacity of the mill drive motor, and the curve z is the upper limit curve of the rolling reduction ratio from the operation such as the biting property and the rough surface of the roll, which is surrounded by the curves w, x, y and z. The range is the actual applicable rolling reduction range.

The applicable rolling reduction range shown in FIG.
Obtained for each of the four bars B, C, D,
Determine the reduction range applicable to all rolling. The reduction ratios of the F2 to F7 stands that are actually applied are determined from within this reduction ratio range. Specifically, a value close to the upper limit will be used in terms of productivity. From the determined rolling reduction and the target plate thickness on the outlet side of the F7 stand, the outlet plate thickness is sequentially calculated from the F6 stand to the F2 stand by the equation (2).

Next, the bar thickness is determined, but there is also a restriction on the bar thickness that can be selected even from the capacities of various facilities such as the rough rolling mill, which is the upstream equipment of the finishing rolling mill, and operational constraints. The bar thicknesses A, B, C and D are determined in consideration of the bar thickness constraint conditions within the range of the F1 stand reduction ratio that can be obtained for each bar.

The above is the basic idea of the present invention.
Combination of pass schedules that are continuously rolled, for example, in the pass schedules of bars A, B, C, and D in FIG. 9, when the ratio between the minimum value and the maximum value of the target product thickness is large, the above method is applied. I can't. For example, when the minimum value of the product plate thickness target is 1.6 mm and the maximum value is 4.5 mm, the bar thickness is 1.6: 4.
It is not realistic because it will be selected in the ratio of 5.

Therefore, in the method according to claim 3, the above method is applied to a downstream stand from any j stand based on the fact that the tension fluctuation is small in the upstream stand and the tension fluctuation is large in the downstream stand. The reduction ratios are made equal, and the reduction ratio distribution and bar thickness are determined within the respective reduction ratio application range from the first stand to the (j-1) stand. As a result, the downstream stand can have the same rolling reduction of all pass schedules, the reduction of tension fluctuation can be achieved, and the upstream stand can be welded by selecting a pass schedule that matches the rolling conditions of each bar. The difference in thickness between the bars can be reduced.

Here, the stand j is set as j = 4 or 5 in the case of the 7-stand structure, and is set as j = 3 or 4 in the mill of the 6-stand structure.

Table 4 is an example of the pass schedule determined by this method. The product plate thicknesses of the bars A, B, C and D are 4.5 mm, 3.0 mm, 2.0 mm and 1.
It is 6 mm.

For changing the running plate thickness between the bars A and B, j = 5, and for the bars B, C and D, j = 4 stands. Therefore, the rolling reduction rates of the F5 to F7 stands are equal between the bars A and B, and F4 to F between the bars B, C, and D.
The rolling reductions of 7 stands are equal.

[0060]

[Table 5]

[0061]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram showing the configuration of an apparatus for carrying out the method according to claim 1 together with a rolling system.

In FIG. 1, 1 to 7 are rolling mills from the first stand to the seventh stand, 8 to 14 are electric motors for driving the rolling mills 1 to 7, and 15 to 21 are roll peripheral speeds of the respective stands to predetermined values. The speed control devices 22 to 28 that control the number of rotations of the electric motors 8 to 14 are reduction control devices that control the roll gaps of the rolling mills 1 to 7 to a predetermined value.

In a tandem rolling mill constituted by such a plurality of rolling mills, it is assumed that a rolled material 29 having a thickness change point (∇) is rolled into different product thicknesses before and after the thickness change point. . Here, the material before the thickness change point of the rolled material 29 is the preceding material, and the material after the thickness change point is the following material.

In this embodiment, before the rolling of the rolled material 29 is started,
The exit side plate thicknesses of the first stand to the sixth stand are determined so that the rolling ratios of the second stand to the seventh stand in the preceding and the following materials are equal, and the roll gap of each rolling mill against the change of the running plate thickness is determined. And set values such as roll peripheral speed.

Here, it is assumed that the bar thickness of the rolled material 29 and the target product thickness of the preceding material and the following material, that is, the delivery-side target thickness of the seventh stand are known. Further, when either the preceding material or the following material is used as the reference pass schedule, it is assumed that the exit side plate thicknesses of the first to sixth stands of the reference pass schedule have already been determined by the conventional pass schedule determination method. . These prerequisites do not particularly impair the essence of the present invention and can be sufficiently achieved by known techniques.

Now, assuming that the reference pass schedule is the pass schedule of the preceding material, the delivery side thickness calculation unit 30A, which is a function of the delivery side thickness calculation device 30, calculates the delivery thicknesses from the first stand to the sixth stand by the formula (10). Calculate The calculated outlet plate thickness is sent to the set value calculation device 31. The set position calculation device 31 uses a well-known rolling model formula to calculate the roll gap set value and roll peripheral speed set value for changing the running plate thickness shown in Table 2 and sends them to the setting control device 32. The setting control device 32 tracks the plate thickness change point on the rolled material 29, and when the plate thickness change point reaches each stand, a roll gap setting command is issued according to the set value sent from the set value calculation device 31. 22 to 28, and also outputs a roll peripheral speed setting command to the speed control devices 15 to 21. As a result, the running plate thickness can be changed with very little change in the roll peripheral speed from the second stand to the seventh stand, and stable operation can be achieved.

FIG. 2 is a block diagram showing the structure of an apparatus for carrying out the method according to claim 2 together with a rolling system.

Among the devices shown in FIG. 2, the devices designated by the same reference numerals as those in FIG. 1 have the same functions as those in FIG. 1, and the description thereof will be omitted.

The difference from FIG. 1 is that a delivery side plate thickness correction unit 30B is added to the delivery side plate thickness calculation device 30. That is,
The output side plate thickness calculation unit 30A calculates the output side plate thicknesses of the first stand to the sixth stand for the trailing material and sends the result to the output side plate thickness correction unit 30B. Delivery side plate thickness correction unit 30B
Then, the function of block 30B shown in FIG. 8 is performed.
As described above, the rolling reduction, rolling load, and rolling power of the first stand are calculated, and it is judged whether or not these are within the limit values due to equipment or operation. If the limit values are exceeded, The outlet side plate thickness of the first stand is corrected so as to be within the limit value, and the same check is sequentially performed from the second stand so that the upstream stand absorbs the corrected amount of the outlet side plate thickness of the first stand.

The pass schedule corrected by the outlet side plate thickness correction unit 30B is sent to the setting arithmetic unit 31. The operations of the setting calculation device 31 and the setting control device 32 are the same as those described with reference to FIG.

As a result, the load is not concentrated on the first stand even when the plate thickness is changed while the plate thickness change amount is large, and it is possible to make the rolling ratio of the preceding material and the following material equal at least in the downstream stand. Therefore, it is possible to stably change the running plate thickness with little fluctuation in tension between stands.

FIG. 3 is a block diagram showing the configuration of an apparatus for carrying out the method according to claim 3 together with a rolling system.

Among the devices shown in FIG. 3, the devices designated by the same reference numerals as those in FIG. 1 have the same functions as those in FIG.
The description is omitted.

In this embodiment, the pass schedule is determined before the rolling of all the rolled materials to be joined is started. For example, when four bars A, B, C and D are joined and continuously rolled as shown in FIG. 9, all pass schedules are determined before the rolling of the bars A, B, C and D is started.

In FIG. 3, the allowable reduction ratio range calculation unit 30C, which is a function of the output side plate thickness calculation device 30, has, for example, each stand that satisfies the above-described concept of constant output side plate crown and facility or operation constraint conditions. Calculate the rolling reduction range. Next, the reduction rate distribution determination unit 30D first determines, for each junction point, the first stand number that equalizes the reduction rates between the pass schedules before and after the junction point, that is, the aforementioned stand j. This is given by a method such as indexing from a table preset with the product plate thickness as a parameter. Next, the reduction rate distribution determination unit 30D uses the calculation result of the allowable reduction rate range calculation unit 30C to determine the reduction rate of the final stand from the j stands applicable to all pass schedules.
Further, the bar thickness and the rolling reduction from the first stand to the (j-1) stand are determined using the allowable rolling reduction range for each bar.

The determined rolling reduction of each stand is sent to the outlet side plate thickness calculating section 30A. The outlet side plate thickness calculation unit 30A calculates the outlet side plate thickness of the (n-1) stand from all the bars and outputs it to the set value calculator 31.

The set value calculation device 31 uses a known rolling model formula, and the roll gap set value and the roll peripheral speed set value corresponding to the change of the running plate thickness shown in Table 2 are changed by the running plate thickness of each joining portion. Is calculated and sent to the setting control device 32. The setting control device 32 tracks the joining point, that is, the plate thickness change point, and issues a roll gap setting command according to the set value sent from the set value calculation device 31 at the timing when the plate thickness change point reaches each stand. 28, and outputs the roll peripheral speed setting command to the speed control devices 15 to 21. As a result, it is possible to change the running plate thickness with little fluctuation in tension between stands at all joint points, and to achieve stable operation.

[0078]

As described above, according to the pass schedule determination method of the present invention, in a stand in which the rolling reductions before and after the plate thickness change are equal, the mass flow change at the time of plate thickness change is small, and therefore, at the time of running plate thickness change. There is almost no need to change the roll peripheral speed, tension fluctuations due to unmatched roll gap setting value changes and roll peripheral speed setting value changes can be reduced, and stable running plate thickness can be changed, improving productivity. effective.

Further, according to the pass schedule determining method of the first aspect, the rolling reductions before and after the plate thickness change can be made equal from the second stand to the final stand, and the effect of reducing the tension fluctuation is great.

Further, according to the pass schedule determination method of the second aspect, it is effective especially when the bar thickness is determined such as changing the running plate thickness in the same bar, and it is effective in equipment and operation. Correcting the rolling reduction of the upstream stand within the above constraints has the effect of expanding the range of application of changing the running plate thickness.

Furthermore, according to the pass schedule determination method of the third aspect, even when the running strip thickness is changed when a plurality of bars are joined one after another and continuously rolled,
A pass schedule that reduces tension fluctuations can be determined, and the effect of achieving stable operation is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an apparatus for carrying out the method according to claim 1 of the present invention.

FIG. 2 is a block diagram showing the configuration of an apparatus for carrying out the method according to claim 2 of the present invention.

FIG. 3 is a block diagram showing a configuration example of an apparatus for performing the method according to claim 3 of the present invention.

FIG. 4 is an explanatory diagram for explaining a method of changing a roll gap and a roll peripheral speed setting value.

FIG. 5 is a diagram showing a simulation result of changing the running plate thickness by a conventional method.

FIG. 6 is an explanatory diagram for explaining a response to a ramp-shaped reference value change of the first-order lag control system.

FIG. 7 is a diagram showing a simulation result when the method according to claim 1 is applied.

FIG. 8 is a flowchart showing a processing procedure of path schedule calculation in the method according to claim 2;

FIG. 9 is an explanatory diagram of a case where a plurality of bars are joined and continuously rolled.

FIG. 10 is an explanatory view of determining a rolling reduction range in the method according to claim 3.

[Explanation of symbols]

 1-7 Rolling mill 8-14 Electric motor 15-21 Speed control device 22-28 Rolling down control device 30 Delivery side plate thickness calculation device 31 Set value calculation device 32 Setting control device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location B21B 37/26 B21B 37/00 BBP 8315-4E 114 (72) Inventor Sadayuki Sankichi Chiba Chiba 1 Kawasaki-cho, Chuo-ku, Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Kunio Sekiguchi Fuchu-shi, Tokyo 1st Toshiba-cho, Fuchu factory, Toshiba (72) Inventor Kaiichi Tokyo Fuchu Toshiba Town No. 1 Inside the Fuchu factory of Toshiba Corporation

Claims (3)

[Claims] 1. A tandem rolling mill in which a plurality of rolling mills are arranged in tandem and steel sheets and the like are continuously rolled, and a running strip thickness is changed to change a product strip thickness between runs without stopping the rolling mill. In this case, one of the second stands (n is an integer of 3 or more) from the second stand either before or after the thickness change (n is an integer of 3 or more) is equal to the reduction ratio of the other first stand (n -1) A method of determining a pass schedule when changing the running plate thickness, which determines the stand-out plate thickness. 2. A tandem rolling mill in which a plurality of rolling mills are arranged in a tandem to continuously roll steel sheets and the like, and a running strip thickness is changed to change a different product strip thickness between runs without stopping the rolling mill. In this case, one of the second stands (n is an integer of 3 or more) from the second stand either before or after the thickness change (n is an integer of 3 or more) is equal to the reduction ratio of the other first stand (n -1) A first step of determining the stand-out side plate thickness, and a rolling reduction, a rolling load, using the stand-in side and side-side plate thicknesses determined in the first step.
The second step of predicting and calculating the rolling power, the rolling reduction of each stand, the rolling load, the constraint conditions of the rolling power, and the rolling reduction calculated in the second step, which are preset from the viewpoint of equipment and operation. Comprising a third step of comparing the load and the rolling power calculation value, and correcting the exit side plate thickness of the stand so that these calculation values fall within the constraint conditions when these calculated values deviate from the constraint conditions. A method for determining a pass schedule at the time of changing the running plate thickness in which the processes of the second and third steps are sequentially performed from the first stand to the downstream stand, and the stands having different rolling reductions before and after the plate thickness change are limited to the upstream stand . 3. A tandem rolling mill for arranging a plurality of rolling mills in tandem and continuously rolling steel sheets and the like, wherein a bar is joined on the inlet side of the tandem rolling mill and a plurality of rolled material positions including joining points are provided. When changing the running thickness and continuously rolling different product thicknesses, the first step of calculating the allowable range of the rolling reduction of each stand for rolling before and after all the thickness change points, and The reduction ratio applicable to all the rollings before and after the change of the plate thickness from the arbitrary j-stand to the final n-stand (n is 3 or more and an integer larger than j) preset for each change is the first step. The second step of selecting from the allowable range of the reduction rate calculated in step 1, and selecting the reduction rate of the (j-1) stand from the first stand within the range of the reduction rate calculated in the first step for each rolling. And in this second step It has a third step of determining the bar thickness and the (n-1) stand outlet plate thickness from the first stand based on the selected reduction ratio of each stand, and runs the reduction ratio of at least the downstream stand from the j stand. How to determine the pass schedule when changing the running plate thickness so that it is equal before and after changing the plate thickness.