JP3290840B2 - How to determine the pass schedule when changing the thickness between runs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A cold rolling mill is used to join materials of the same or different steel types or dimensions at the entrance of a rolling mill and change the product thickness between runs without stopping the rolling mill. Already done in many facilities.

In recent years, the technology for changing the running thickness has been applied to hot rolling mills as means for improving yield and producing small lots. Hereinafter, the present invention will be described with an example of a change in the running sheet thickness in a hot finishing rolling mill.

When changing the strip thickness during running, the set values of the roll gap and the roll peripheral speed of each stand of the tandem rolling mill are usually changed from the set values before the change in the thickness (hereinafter, referred to as A schedule) (hereinafter, referred to as A schedule). (Referred to as B schedule). At this time, the point is to reduce the off-gauge amount due to the change in the plate thickness, minimize the fluctuation of the tension between stands as much as possible, and change the plate thickness stably. In order to reduce the off-gauge amount, it is most effective to shorten the time required for changing the roll gap and the roll peripheral speed setting. However, shortening the change time of the set value acts in the direction in which the fluctuation of the tension between stands increases, so that there are various methods for improving the method of changing the set value and improving the accuracy of the set value to reduce the fluctuation of the tension. Has been developed. Further, as described in JP-A-56-11515, a method of associating a variation in tension between stands with a change in mass flow of each stand due to a change in thickness during running, and defining an amount of change in a rolling reduction of each stand. Has also been proposed. This known example is the rolling speed V _R and the reduction column variation of represents a change △ L of the loop of the strip between each stand (1) by the formula, the change in the amount of loop stand for performing Hashimaban thickness changes It is designed to be uniquely determined as the product of Δr.

[0005] _{△ L i-1, i =} V Ri-1 · α · △ r i-1 + V Ri · (1-α) · △ r i (1) where, α is a coefficient, i stand number ( No.), and the rolling reduction r is a value given by the following equation (2).

[0006]

(Equation 1) In other words, the rolling rate and the rolling reduction are inversely proportional so that the change in the loop amount becomes smaller, the rolling reduction is increased in the upstream stand with a lower rolling speed, and the rolling reduction is increased in the downstream stand with the higher rolling speed. It is a way to make it smaller. Further, this known example also describes that the rolling reduction ratio is such that the same amount of turbulence in the mass flow occurs in each rolling stand.

[0007]

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

[0008]

[Table 1] Here, the reduction ratio change amount = | (B schedule reduction ratio)-(A schedule reduction ratio) |

Tables 2 (a) and 2 (b) show the relationship between the thickness change point position and the roll gap set value and roll peripheral speed set value of each stand when the F7 stand is a reference stand which does not change the roll peripheral speed. Shown in

[0010]

[Table 2]

[0011]

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

As shown in Table 2, the roll gap setting value changes the setting value of the stand from the value of the A schedule to the value of the B schedule at the timing when the thickness change point arrives. The roll peripheral speed set value changes the set value of the stand and the upstream stand at the timing when the thickness change point is reached. At the time when the thickness change point reaches the final F7 stand and the change of the roll gap and the roll peripheral speed is completed, the thickness change from the A schedule to the B schedule has been performed.

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

FIG. 5 shows a simulation result of the change in the running thickness shown in Table 1. In FIG. 5, (a) shows the deviation of the exit side plate thickness 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 speed change amount of each stand. ing. As apparent 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 is a difference in the control response between the roll-down control device for controlling the roll gap and the speed control device of the main engine for controlling the roll peripheral speed. FIG. 6 shows the movement of the control amount when the reference value of the control system in which the crossing angle frequency is represented by the first-order delay of ω _c (rad / s) is changed to a tapered shape. That is, the control amount is a time constant 1 / ω with respect to the reference value.
It changes with a delay of _c (sec). It is important that the actual change of the roll gap and the roll peripheral speed be started at the same timing and completed at the same time in order to prevent the tension fluctuation even in the process of changing the roll gap and the roll peripheral speed set value. However, it is common that the actual control response of the rolling position control device and the speed control device differs by more than twice, so that the reference values of the rolling control device and the speed control device are changed at the same timing and completed at the same time. However, the actual roll gap and the change in the roll peripheral speed do not match. This difference in response appears as a change in volume velocity and causes tension fluctuation.

Also, a command to change the set values of the roll gap and the roll peripheral speed due to the control pitch of the controller which gives a set value to the rolling-down control device or the speed control device, and the delay of the transmission system between the controller and the rolling-down control device or the speed control device. It cannot always be synchronized, which also contributes to tension fluctuations. That is, the cause of the tension fluctuation is the asynchronousness of the roll gap and the roll peripheral speed in the process of changing the set value, and it cannot be said that the method of the known example can reduce the fluctuation of the tension.

[0017] The change of the strip thickness during running is not only in the case of rolling coils of different product thicknesses from the same bar, but also by joining bars of different thicknesses, widths or steel types on the entrance side of the finishing rolling mill and continuously rolling. It is also done when you do. At this time, since there are usually two or more bars to be joined (for example, 20 bars), simply changing only the pass schedule between the joined bars to an appropriate value makes it possible to change all the running thicknesses. Cannot be performed stably.

For example, when bars A, B, and C are sequentially joined to change the running distance at each joint, the variation in tension at the time of changing the strip thickness at the joint between bars A and B is reduced. Although the pass schedule for Bar A and Bar B can be determined,
There is no assurance that the pass schedule of the bar C can be determined so that the tension fluctuation at the junction between the and the bar C at the time of the change of the running thickness becomes small. The constraint conditions include the capacity of the rolling mill drive motor, the range in which the speed can be set, the limitation on the rolling mill load, and the like.

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

According to the present invention, the tension between the stands caused by the asynchrony in the process of changing the set value of the roll gap and the set value of the peripheral speed of the roll in the change of the strip thickness in the same bar and at the junction with the different bars. An object of the present invention is to provide a method for determining a pass schedule that does not change the roll peripheral speed as much as possible when changing the inter-running plate thickness in order to reduce fluctuations.

[0021]

According to a first aspect of the present invention, there is provided a tandem rolling mill in which a plurality of rolling stands are arranged in tandem. When changing the sheet thickness, one of the second stands before or after the sheet thickness is changed and the other one of the second stands is equal to the rolling reduction of the last n stands (n is an integer of 3 or more). From one stand (n-
1) Determine the thickness of the outlet side of the stand.

According to a second aspect of the present invention, there is provided a tandem rolling mill in which a plurality of rolling mills are arranged in tandem and a steel sheet or the like is continuously rolled. In the case of changing the running sheet thickness to be changed, any one of the second stand before or after the thickness change is changed so as to be equal to the rolling reduction of the last n stands (n is an integer of 3 or more). Or from the other first stand (n
-1) A first step of determining the exit side plate thickness of the stand, and a second step of predicting and calculating the rolling reduction, rolling load, and rolling power using the stand entrance and exit side plate thicknesses determined in the first step. The step, the rolling reduction of each stand preset from equipment and operation, rolling load, the constraint conditions of the rolling power and the rolling reduction calculated in the second step, the rolling load, the rolling power calculated value Compare, and if these calculated values fall outside the constraints, they fall within the constraints,
A third step of correcting the outlet side plate thickness of the stand, wherein the processes of the second and third steps are sequentially performed on the downstream stand from the first stand, and the rolling reduction differs before and after the plate thickness change. Limit stands to upstream stands.

Further, according to a third aspect of the present invention, there is provided a tandem rolling mill in which a plurality of rolling mills are arranged in tandem and a steel plate or the like is continuously rolled. When changing the running thickness at multiple positions on the rolled material and continuously performing different product thickness rolling, the allowable range of rolling reduction of each stand is calculated for rolling before and after all the thickness changing points The first step is to perform the following steps, and from an arbitrary j stand set in advance for each change in the plate thickness to the final n stand (n
Is an integer greater than or equal to 3 and greater than j), a reduction rate applicable to rolling before and after all sheet thickness changes is selected from within the allowable reduction rate calculated in the first step, and the first stand 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 a rolling reduction of each stand selected in the second step. From the bar thickness and the first stand to determine the exit side plate thickness of the (n-1) stand based on
And making the rolling reduction of at least the stand downstream from the j stand equal before and after the change of the running thickness.

[0024]

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

First, the method according to claim 1 will be described with reference to a hot finishing rolling mill having a seven-stand configuration. Assuming that the reference stand is the F7 stand, the following equations (3) and (4) are established from the constant volume velocity law in the steady rolling state of the A schedule before the sheet thickness change and the B schedule after the sheet thickness change.

[0026] _{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 exit side plate thickness V _Ri : i-stand roll peripheral speed f _i : i-stand advanced rate Subscript A: A schedule B: B schedule From formulas (3) and (4), F7 which is the reference stand When the ratio of the i-stand roll peripheral speed to the stand roll peripheral speed is obtained, the following expressions (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)
Equation = Equation (6). This means that the roll peripheral speed ratio between adjacent stands, for example, between the i stand and the (i + 1) stand,
As shown in equation (7), it means that the A schedule and the B schedule are equal.

[0028]

(Equation 3) Therefore

[0029]

(Equation 4) The fact that the roll peripheral speed ratio between the adjacent stands is equal before and after the plate thickness change means that the speed change shown in Table 2 (b) is not necessary except for a small change in the advance rate. Here, it is assumed that the stand-out sheet thickness of each stand of the schedule A is known, and the stand-out sheet thickness of each stand of the schedule B which satisfies the relationship of the expression (7) is (5),
Equation (8) is obtained from equation (6).

[0030]

(Equation 5) (8) When _{f iA = f iB f 7A =} f 7B (9) and assuming in equation (8) is expressed by equation (10).

[0031]

(Equation 6) Is the reduction ratio r _i of i stand in B schedule (11)
This is as shown in the equation.

[0032]

(Equation 7) Substituting equation (10) into equation (11) gives A, B as shown in equation (12).
The rolling reduction of the schedule becomes equal.

[0033]

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

That is, when there is no freedom in determining the bar thickness on the entrance side of the finishing mill, each stand of the A and B schedules is set on condition that the rolling reduction from the second stand to the last stand is made equal in the A and B schedules. Determine the exit plate thickness.
For example, when the thickness of the delivery side of each stand of the A schedule is known, the delivery side thickness of the B schedule is determined by Expression (10). As a result, the roll peripheral speed ratio of the second stand to the last stand with respect to the reference stand becomes substantially equal in the A and B schedules, and the interstand tension fluctuation when the running plate thickness is changed can be reduced.

This method will be applied to the rolling schedule shown in Table 1. For example, F2 of B schedule
Table 3 shows that the stand-up reduction rates of the stands F7 to F7 are equal to the schedule A and the stand-out side plate thicknesses of the schedule B are obtained.

[0036]

[Table 4] FIG. 7 shows a simulation result of the change in the running thickness in Table 3. As is apparent from a comparison between the roll peripheral speed change amount in FIG. 7D and the roll peripheral speed change amount in FIG. 5D, in FIG. 7, the roll peripheral speed change is small except for the F1 stand. Also, comparing the tensions of FIG. 7 (b) and FIG. 5 (b), the variation in FIG. 7 is much smaller, and the effect of the method of claim 1 is clear.

Next, the method according to claim 2 will be described.

As shown in Table 3, when the method described in claim 1 was applied to the change of the bar thickness to the product thickness, that is, the change in the running thickness between pass schedules having different total elongations, F1 The rolling reduction of the stand is different between the A schedule and the B schedule. This is the same in the method described in claim 1. That is, the difference between the total growth rates of the schedules A and B is all absorbed by the F1 stand. For this reason, the rolling reduction of the F1 stand may be a value that cannot be rolled in some cases.

As the constraint conditions that make rolling impossible, there are a constraint condition from the equipment rating and a constraint condition from the operation. The equipment rating includes the capacity of the main motor, the roll peripheral speed setting range (speed cone), and the maximum rolling load applied to the rolling mill. As operational constraints, there is a case where a rolling load per unit width or a rolling reduction itself is limited in order to prevent deterioration of plate flatness or surface properties, roughening of rolls, and the like.

If the pass schedule is determined, the required rolling power, the generated rolling load, and the set value of the roll peripheral speed can be easily calculated using a known rolling model formula, and whether or not the above-mentioned constraint condition is exceeded. Is possible.

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 amount of loop is proportional to the peripheral speed of the roll as shown in the equation (1), and the equivalent Young's modulus of the rolled material is smaller at the upstream stand.

According to the second aspect of the present invention, when the F1 stand exceeds the constraint condition based on this fact, the thickness of the F1 stand exit side plate is changed so as to be within the constraint condition, and the change can be used to change the tension. It is absorbed by the upstream stand, which is less likely. FIG. 8 shows a processing procedure for determining the stand-out side plate thickness of the B schedule according to this method. First, the stand thickness of each stand 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 determined whether the rolling reduction, the rolling load, and the rolling power of the F1 stand are within the limit values. If the limit values are exceeded, the thickness of the F1 stand exit side is changed so as to be within the limit values. (Steps 104 and 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 or not it is within the limit value similarly to the F1 stand (104). Thus, F1
The exit side plate thickness is sequentially corrected from the stand exit side plate thickness toward the downstream stand to absorb the excess of the constraint condition of the F1 stand.

Next, the method according to claim 3 will be described.

When the bars are joined on the entry side of the finishing mill and the running strip thickness is changed at the joining point, the delivery side sheet thickness and the 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 thickness. In FIG. 9, ▽ indicates a joining point. Bars to be joined generally differ in steel type, width and thickness, and also in product thickness. Although there is an optimal pass schedule for each of the A, B, C and D rollings, the method according to claim 3 determines a pass schedule in which the tension variation is reduced in all three changes in the running thickness.

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

The i-stand exit side plate crown C ₁ (%) is (1
It is expressed by equation 3).

[0047]

(Equation 9) Here, h _Ci : thickness at the center of the plate width h _Ei : thickness at the end of the plate.

The sheet crown is an important product quality control item, and it is necessary to achieve a target sheet crown. Further, the difference between the entrance-side plate crown and the exit-side plate crown, that is, (C _i −
If C _{i- 1} ) exceeds a certain value, the flatness of the plate such as middle elongation or end elongation is deteriorated. Therefore, it is important to control the plate crown of each stand within a range where the flatness is not deteriorated. The sheet crown in actual rolling is affected by the roll profile, the amount of deflection, and the like, and is usually a function of the rolling load, roll crown, roll bending force, entry side sheet crown, and the like 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) but P: rolling load C _R: roll crown F _B: roll bending force alpha _p: relative plate crown Rolling load influence coefficient α _R : Effect coefficient of roll crown on sheet crown α _B : Effect coefficient of roll bending force on sheet crown α _H : Genetic coefficient of entrance side sheet crown.

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

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

In consideration of the flatness of the plate, the pass schedule is determined on condition that the outgoing plate crown of each stand is made equal to the product target plate crown. Specifically, equations (14) and (15)
The rolling loads P _i and the entry-side sheet thicknesses h _{i−1 at} which the stand-out sheet crowns become the product target sheet crowns are obtained by simultaneous equations. By sequentially performing this process from the final F7 stand to the F2 stand, the exit side plate thickness of the F1 to F6 stands can be determined. Roll bending force F _Bi at this time (14) is an operating end for controlling strip crown, rolling force F _Bi strip crown C _i by setting value of the target strip crown P _i and thickness at entrance side h _{i- 1} comes different. That is, it is possible to obtain the stand-side exit side plate thickness corresponding to the upper limit and the lower limit of the operable roll bending force F _Bi , thereby obtaining the range of reduction ratio that each stand can take. Here, only the roll bending force is used as the operating end for controlling the sheet crown, but in recent years the number of operating working ends has increased, and the range of reduction ratios that can be obtained by combining them is also expanding.

In FIG. 10, w and x are curves showing the range of the rolling reduction that can be taken for each stand. Curve y is the upper limit of the rolling reduction limited by the capacity of the mill drive motor, and curve z is the upper limit of the rolling reduction from the operational point of view, such as the biting property and the rough surface of the roll, and is surrounded by the curves w, x, y, and z. The reduced range is the rolling reduction range that can be actually applied.

The applicable rolling reduction range shown in FIG.
For each of the four bars B, C, and D,
Determine the rolling reduction range applicable to all rolling. From the range of the rolling reduction, the rolling reduction of the F2 to F7 stands to be actually applied is determined. Specifically, a value close to the upper limit is used in terms of productivity. From the determined rolling reduction and the target plate thickness at the outlet of the F7 stand, from the F6 stand to the F2 stand, the outlet plate thickness is obtained by the equation (2).

Next, the bar thickness is determined. However, there are also restrictions on the bar thickness from which even the capacity of various facilities including the rough rolling mill, which is the upstream equipment of the finish rolling mill, and the restrictions on the operation can be selected. The bar thicknesses A, B, C, and D are determined in consideration of the bar thickness constraint within the range of possible F1 stand rolling reductions obtained for each bar.

The above is the basic concept of the present invention.
The above method is applied when the ratio between the minimum value and the maximum value of the target product thickness is large in the combination of the pass schedules to be continuously rolled, for example, in the pass schedule of bars A, B, C, and D in FIG. Can not. For example, when the minimum value of the product thickness target is 1.6 mm and the maximum value is 4.5 mm, the bar thickness is 1.6: 4.
It is unrealistic to select at a ratio of 5.

Therefore, in the method according to the third aspect, based on the fact that the tension fluctuation is small at the upstream stand and the tension fluctuation is large at the downstream stand, the above method is applied to the downstream stand from an arbitrary j stand, and The reduction ratios are made equal, and from the first stand to the (j-1) stand, the reduction ratio distribution and the bar thickness are determined within the respective reduction ratio application ranges. As a result, for the downstream stand, the rolling reduction can be made equal to that of all the pass schedules, and a reduction in the tension fluctuation can be achieved. For the upstream stand, by selecting a pass schedule suitable for the rolling conditions of each bar, the joining can be performed. Thickness difference between the bars to be formed can be reduced.

Here, the stand j is set, for example, to j = 4 or 5 in the case of a 7-stand configuration, and is set to j = 3 or 4 in a 6-stand configuration mill.

Table 4 is an example of a path 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.
6 mm.

J = 5 for the change in the running thickness between bars A and B, and j = 4 stands for between bars B, C and D. Therefore, between the bars A and B, the rolling reduction rates of the F5 to F7 stands are equal, and between the bars B, C and D, F4 to F7
The rolling reduction of the seven stands is equal.

[0060]

[Table 5]

[0061]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail 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 the roll peripheral speeds of the respective stands at predetermined values. Speed control devices for controlling the number of rotations of the electric motors 8 to 14 are pressure reduction control devices for controlling the roll gaps of the rolling mills 1 to 7 to predetermined values.

In such a tandem rolling mill composed of a plurality of rolling mills, it is assumed that a rolled material 29 having a thickness change point (▽) is rolled to a different product thickness before and after the thickness change point. . Here, the part before the thickness change point of the rolled material 29 is the preceding material, and the part after the thickness change point is the succeeding material.

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

Here, it is assumed that the bar thickness of the rolled material 29 and the product target thicknesses of the preceding material and the succeeding material, that is, the target thicknesses on the delivery side of the seventh stand are known. 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 thickness calculating unit 30A, which is a function of the delivery thickness calculating device 30, calculates the delivery thickness from the first stand to the sixth stand by the equation (10). Calculate. The calculated outlet plate thickness is sent to the set value calculator 31. The set position calculating device 31 calculates the roll gap set value and the roll peripheral speed set value for the change in the running strip thickness shown in Table 2 using a known rolling model formula, and sends the calculated values to the setting control device 32. The setting control device 32 tracks the thickness change point on the rolled material 29 and, at the timing when the thickness change point reaches each stand, sends a roll gap setting command according to the set value sent from the set value calculation device 31. 22 to 28, and outputs a roll peripheral speed setting command to the speed control devices 15 to 21. As a result, the running thickness can be changed while the change in the roll peripheral speed of the second stand to the seventh stand is extremely small, and stable operation is achieved.

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

[0069] Of the devices shown in FIG. 2, those denoted by the same reference numerals as those in FIG. 1 have the same functions as those in FIG. 1, and a description thereof will be omitted.

The difference from FIG. 1 is that an outlet thickness correcting unit 30 B is added to the outlet thickness calculator 30. That is,
The calculation result of the outlet plate thickness of the first stand to the sixth stand for the following material in the outlet plate thickness calculator 30A is sent to the outlet plate thickness corrector 30B. Discharge side thickness correction part 30B
Then, the function of the 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 determined whether or not these are within limits from facilities or operation. The exit side plate thickness of the first stand is corrected so as to fall within the limit value, and the same check is sequentially performed from the second stand so as to absorb the first stand exit side plate thickness correction amount in the upstream stand.

The path schedule corrected by the outlet thickness correcting section 30B is sent to the setting calculation device 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.

In this way, even in the case of a change in the running plate thickness in which the thickness change amount is large, the load is not concentrated on the first stand, and at least in the downstream stand, the rolling reduction of the preceding material and the succeeding material can be equalized. In this way, it is possible to 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 the third aspect together with a rolling system.

[0073] Of the devices shown in FIG. 3, those having 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 starting the rolling of all the rolled materials to be joined. For example, as shown in FIG. 9, when four bars A, B, C, and D are joined and continuously rolled, all pass schedules are determined before rolling of the bars A, B, C, and D is started.

In FIG. 3, the allowable rolling reduction range calculating section 30C, which is a function of the outlet plate thickness calculating device 30, is provided, for example, for each stand which satisfies the above-described concept of the outlet plate crown and the facility or operation constraints. Calculate the rolling reduction range. Next, the rolling reduction distribution determination unit 30D first determines the first stand number for equalizing the rolling reduction between the pass schedules before and after the junction, that is, the above-described stand j for each junction. This is given, for example, by a method of indexing from a preset table using the product plate thickness as a parameter. Next, the rolling reduction distribution determining unit 30D determines the rolling reduction of the last stand from the j stands applicable to all the pass schedules, using the calculation result of the allowable rolling reduction range calculating unit 30C.
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 thickness calculating section 30A. The exit side thickness calculating section 30A calculates the exit side thickness of the (n-1) stand from the first stand for all the bars and outputs the calculated value to the set value calculation device 31.

The set value calculating device 31 uses a known rolling model formula to change the roll gap set value and the roll peripheral speed set value with respect to the change in running strip thickness shown in Table 2 to change the running strip thickness at each joint. Is calculated and sent to the setting control device 32 before the start. The setting control device 32 tracks the joining point, that is, the sheet thickness change point, and sends the roll gap setting command according to the set value sent from the set value calculation device 31 at the timing when the sheet thickness change point reaches each stand. 28, and outputs a roll peripheral speed setting command to the speed controllers 15 to 21. As a result, the running thickness can be changed with less fluctuation in the tension between stands at all the joint points, and stable operation can be achieved.

[0078]

As described above, according to the pass schedule determining method of the present invention, the stand having the same rolling reduction before and after the change of the plate thickness has a small mass flow change at the time of the plate thickness change. There is almost no need to change the roll peripheral speed, and it is possible to reduce the tension fluctuation caused by the mismatch between the change in the roll gap setting value and the change in the roll peripheral speed setting value. effective.

Further, according to the pass schedule determining method of the present invention, the rolling reduction before and after the thickness change from the second stand to the final stand can be equalized, and the effect of reducing the tension variation is great.

Further, the pass schedule determining method according to the second aspect is effective particularly when the bar thickness is determined as in the case of changing the inter-running plate thickness within the same bar. Correcting the rolling reduction of the upstream stand within the above-mentioned restrictions has the effect of expanding the applicable range of the change in the running thickness.

Further, according to the pass schedule determining method of the third aspect, even when a plurality of bars are successively joined and rolled continuously, a change in the running thickness can be achieved.
The pass schedule for reducing the tension fluctuation can be determined, and the effect of realizing stable operation is great.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is a diagram showing a simulation result of a change in a 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 a 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 for calculating a path schedule 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 diagram of determination of 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 controller 22-28 Rolling-down controller 30 Outboard thickness calculator 31 Set value calculator 32 Setting controller

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kunio Sekiguchi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant (72) Inventor Kaiichi 1 Toshiba-cho, Fuchu-shi, Tokyo Higashi Corporation Shiba Fuchu Plant (58) Field surveyed (Int.Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (3)

(57) [Claims] In a tandem rolling mill in which a plurality of rolling mills are arranged in tandem to continuously roll a steel plate or the like, a running thickness change is performed to change a product thickness different between runs without stopping the rolling mill. In this case, from either one of the first stands before the change of the plate thickness or after the change of the plate thickness, (n is an integer of 3 or more) from the other one of the first stands (n is an integer equal to or more than 3). -1) A method of determining a pass schedule at the time of changing a running strip thickness for determining a delivery side thickness of a stand. 2. In a tandem rolling mill in which a plurality of rolling mills are arranged in tandem to continuously roll a steel plate or the like, a running strip thickness is changed to change a product thickness between runs without stopping the rolling mill. In this case, from either the second stand before the thickness change or after the thickness change, the final n-stands (n is an integer of 3 or more) from the other first stand (n -1) The first step of determining the outlet side plate thickness of the stand, and the rolling reduction, rolling load, and the like using the stand inlet and outlet side plate thicknesses determined in the first step.
The second step of predicting and calculating the rolling power, the rolling reduction rate of each stand, the rolling load, the rolling power, the rolling reduction rate calculated in the second step, the rolling rate, and the rolling conditions set in advance from equipment and operation. A third step of comparing the load and rolling power calculation values, and correcting the exit side plate thickness of the stand so that these calculation values fall within the constraints when the calculated values fall outside the constraints. The second and third steps are sequentially performed on the downstream stand from the first stand, and a pass schedule determining method at the time of changing a running strip thickness is limited to a stand having a different rolling reduction before and after the thickness change. . 3. A tandem rolling mill in which a plurality of rolling mills are arranged in tandem to continuously roll a steel plate or the like, wherein the bars are joined on the entry side of the tandem rolling mill and a plurality of rolling mills including joining points are provided. A first step of calculating the allowable range of the rolling reduction of each stand for the rolling before and after all the thickness change points when the running thickness is changed and continuously different product thickness rolling is performed; From the arbitrary j stand preset for each change to the last n stands (n is 3 or more and is an integer greater than j), the rolling reduction applicable to rolling before and after all sheet thickness changes is determined in the first step. A second step of selecting from the allowable range of the rolling reduction calculated in the above, and selecting a rolling reduction from the first stand to the (j-1) stand from the range of the rolling reduction calculated in the first step for each rolling. And in this second step A third step of determining the bar thickness and the exit side plate thickness of the (n-1) stand from the first stand based on the reduction rate of each selected stand, and running at least the reduction rate of the stand downstream from the j stand. How to determine the pass schedule at the time of running thickness change, which is the same before and after the thickness change.