JP3302930B2 - How to change the setting of the running distance of the rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling mill for rolling steel sheets or the like, which manufactures products having different thicknesses and widths from the same base material, or joins different base materials and continuously rolls them. The present invention relates to a method for changing the running distance setting of a rolling mill when changing the running distance of a rolling mill.

[0002]

2. Description of the Related Art Development of a running distance changing technique has been promoted in various fields for the purpose of continuity of a process and improvement of productivity, and cold rolling mills have already been implemented in many plants. or,
In recent years, a change in running distance has been applied to a hot rolling mill.

[0003] There are the following four cases of changing between runs.

(1) Products having different thicknesses are manufactured from the same base material. (2) Manufacture products having different plate widths from the same base material. (3) Products having different sheet widths and sheet thicknesses are manufactured from the same base material. (4) Different base materials are joined and continuously rolled. This may be different if the dimensions and grade of the base material to be joined are the same, and if the product dimensions are the same before and after the joining point,
May be different.

In order to change the running distance stably and with high accuracy, it is important to appropriately change the set value of the rolling position and the set value of the roll speed of the rolling mill. As a prior art relating to a method of changing the set value of the rolling position and the set value of the roll speed in changing the running distance, for example,
No. 17145. This is a control method in a rolling mill composed of a plurality of stands. Each time a change point during travel reaches each stand, the rolling position of the stand is changed to a set value of a following material, and the stand is changed. And changing the roll speed of all the stands in the upstream stand or the downstream stand so as to maintain the mass flow balance.

FIG. 5 shows two adjacent stands as an example.
The change of the set value of the rolling position and the set value of the roll speed by the conventional method are shown. In FIG. 5, h is the exit side plate thickness, S
Is the rolling position, P is the rolling load, VR is the roll speed, i is the stand number, suffix A is the preceding material before changing the running distance, suffix B
Indicates the following material after the change between runs. In a rolling mill composed of a plurality of stands, when changing the target plate thickness of the preceding material to the target plate thickness of the succeeding material, as shown in FIG. Change to the exit side thickness of the row material.

That is, at the timing when the running change point reaches the i-th stand, the rolling position Si of the i-th stand is changed from the set value SAi of the preceding material to the set value SBi of the succeeding material. The side thickness is changed from the thickness hAi of the preceding material to the thickness hBi of the succeeding material. Further, the rolling load generated at this time changes from PAi to PBi. Similarly, at the timing when the change point between runs reaches the (i + 1) th stand, the (i +
The rolling position Si + 1 of one stand is the set value SAi + 1 of the preceding material.
Is changed to the set value SBi + 1 of the succeeding material, whereby the outlet side plate thickness is changed from the thickness hAi + 1 of the preceding material to the thickness hBi + 1 of the following material. Also, the rolling load generated at this point is
It changes from PAi + 1 to PBi + 1. Further, the roll speed VR
i and VRi + 1 are changed so as to maintain the mass flow balance even during the change between runs. Here, whether or not the plate thickness accuracy can be accurately changed to the plate thickness of the succeeding material depends on the change accuracy of the set value of the rolling-down position.

FIG. 6 shows the relationship between the mill stiffness curve and the plastic curve before and after the change in running distance. In FIG. 6, A is the plastic curve of the preceding material before the change in running distance, B is the plastic curve of the following material after changing the running distance, C is the mill stiffness curve of the preceding material, and D is the following curve after changing the running distance. It is a mill stiffness curve of a material. The horizontal axis in FIG. 6 is the sheet thickness or the rolling position, and the vertical axis is the rolling load. The intersection of the plastic curve and the abscissa is the entry thickness, HA is the entry thickness of the preceding material, H
B is the entry side thickness of the trailing material. The intersection of the mill stiffness curve and the horizontal axis is the rolling position, the value of the horizontal axis at the intersection of the mill stiffness curve and the plasticity curve is the exit side plate thickness, and the value of the vertical axis is the rolling load in the rolling state.

As is apparent from FIG. 6, the set values SA and SB of the rolling-down position are obtained by the following equations.

SA = hA−SmA (1) SB = hB−SmB (2)

Here, SmA and SmB are the amounts of elastic deformation of the mill in the rolling of the preceding material and the following material, that is, the elongation of the mill, and are expressed as functions of the rolling load, the sheet width, and the like. For this reason, conventionally, the rolling loads PA and P
B is predicted, and the elongations SmA and SmB of the mill are obtained. (1)
From the equation (2), the set value SA of the rolling position before and after the change in running distance,
The method of calculating SB was used.

Japanese Patent Application Laid-Open No. 8-332508 discloses a mill constant variable control device for determining a rolling position operation amount in proportion to a variation in rolling load, and correcting a rolling roll reduction position reference based on the rolling position operation amount. In this case, a method of calculating the amount of change in the rolling position in the case of the above is disclosed.

FIG. 7 is a block diagram of a mill constant variable control system. In the drawing, reference numeral 10 denotes a rolled material, which is rolled by a rolling mill including a pair of work rolls 12 and a backup roll 14. Reference numeral 16 denotes a pressure reduction cylinder, which moves a piston up and down by hydraulic pressure to operate a gap between the upper and lower work rolls 12. Reference numeral 18 denotes a rolling position detector which continuously detects a gap between the upper and lower work rolls 12. A load detector 20 continuously detects a rolling load generated in the rolled material 10. Reference numeral 22 denotes a rolling position control device, which is a value obtained by subtracting a rolling position reference operation amount ΔSMMC output from the mill constant variable control device 24 from the rolling position reference SREF, and a rolling position detected by the rolling position detector 18. The operation amount of the screw-down cylinder 16 is calculated according to the difference from the current value, and the gap between the upper and lower work rolls is set to (SREF
-ΔSMMC). Mill constant variable controller 24
Is composed of a load lock-on unit 26 and a gain setting unit 28. The load lock-on unit 26 stores the rolling load P detected by the load detector 20 at a certain timing. The difference between the rolling load P and the load value PL stored in the load lock-on unit 26 is determined by a gain. It is sent to the setting unit 28. The gain setting unit 28 sets the ratio between the mill constant M and the tuning rate α, calculates the product of the rolling load difference ΔP, and outputs the result as the rolling position operation amount ΔSMMC.

If the rolling load P becomes larger than the lock-on load PL for some reason, ΔSMMC becomes an output in the direction of reducing the gap between the upper and lower work rolls of the rolling mill, and the output side plate thickness of the rolled material 10 is reduced. I do.

FIG. 8 is a diagram for explaining the operation of the mill constant variable control. That is, when rolling is performed in the state of the incoming side sheet thickness H1, the rolling load P1, and the outgoing side sheet thickness h1, assuming that the sheet fluctuates in the direction of increasing the incoming side sheet thickness H2, if the rolling position does not change, the rolling load is P2. And the exit side plate thickness is h
It fluctuates in the thick direction to 2. That is, when the mill constant variable control is “off”, the operating point moves on the mill rigidity curve. In the figure, M is the mill constant, which is the slope of the mill stiffness curve near the rolling operation.

Next, when the mill constant variable control is turned on, assuming that the rolling load P1 is equal to the lock-on load PL in FIG. 7, the rolling position operation amount ΔSMMC proportional to the load difference between P2 and P1. However, the rolling position is operated in the closing direction of the roll gap. As a result, the rolling load becomes P3, and the exit side plate thickness changes to h3. As is apparent from FIG.
Is smaller than the exit side plate thickness h2 when the mill constant variable control is not performed, and the difference from the exit side plate thickness h1 before the entrance side plate thickness changes is small. This is the effect of controlling the thickness by the variable mill constant control. If the mill constant variable control is set to “on”, the rolling operating point has moved from (h1, P1) to (h3, P3), and the slope connecting these two points is calculated as the equivalent mill constant Meq. It is called.

The equivalent mill constant is a function of the tuning rate α, and is expressed by the following equation.

Meq = M / (1-α) (3)

The tuning ratio α is desirably a value close to "1.0", and at present, a value of about "0.95" is practically used.

Consider a case in which the mill constant variable control is turned on during the change of the running distance during the changing of the running distance as shown in FIG. Since the mill constant variable control operates the rolling position by changing the rolling load as described above, the rolling position is also operated when the rolling load is changed by changing the running distance.
For example, in FIG. 6, since the rolling load increases from PA to PB, the mill constant variable control further controls the rolling position in a direction to further close the roll gap. Mill constant variable control is off
In the case of, there is no problem by changing the rolling position reference SREF in FIG. 7 from SA to SB, but the mill constant variable control is turned on.
In the case of (1), if the rolling position reference SREF is changed from SA to SB, an error occurs in the rolling position by the rolling position operation amount by the variable mill constant control, and the outlet side thickness is not changed to the target value. For this reason, conventionally, the mill constant variable control has been set to "OFF" during the change of the running distance.

Therefore, in Japanese Patent Application Laid-Open No. 8-332508, in order to effectively utilize the thickness control effect of the mill constant variable control even during the change between running distances, the output side plate thickness is increased even when the mill constant variable control is turned on. To be able to change to accuracy,
Equipped with a mill constant variable control device that calculates the rolling position operation amount in proportion to the variation of the rolling load and corrects the rolling position reference of the rolling roll by this rolling position operation amount. The set value of the rolling position before and after the change of the running distance is determined in consideration of the amount of operation of the rolling position by the device, the rolling position reference change amount is obtained from the obtained setting value of the rolling position, the running distance change point is tracked, The rolling position of the rolling mill is changed at the timing when the running change point is reached.

In the case where the rolling position is changed in the rolled material for the purpose of controlling the thickness of the rolled material in the longitudinal direction or controlling the tension between stands, FIG.
Instead of setting the roll-down position to the roll-down position set value SB of the succeeding material as in the example of 2508, as shown in the following equation, the preceding material and the succeeding material are compared with the actual roll-down position actual value SAact of the preceding material. A method is used in which only the amount of change ΔS in the rolling position of the material is added to obtain a set value SBcmp of the succeeding material rolling position.

SBcmp = SAact + ΔS (4) ΔS = SB−SA (5)

Further, in Japanese Patent Application Laid-Open No. Hei 7-185630, an automatic sheet thickness control is performed using a result of calculation of a sheet thickness target value (draft schedule) of each stand so as to optimize the reduction control operation before and after the sheet thickness change. When controlling the rolling position of the mill by performing the thickness control with a constant target value, and when performing the thickness change control that changes the target thickness of the preceding part and the following part during the running By using different rolling control parameters, for example, at the time of thickness change control, the tuning rate of automatic thickness control is compensated, and the plastic constant of the material is converted assuming that the input side thickness is constant. It is described that the amount of change in the reduction setting is given using the apparent plasticity coefficient obtained.

Japanese Unexamined Patent Application Publication No. 6-15318 discloses that, in order to shorten the off-gauge length after changing the running gauge, in the running-gauge changing setup learning calculation of the cold rolling mill, data tracking of measured values and learning are performed. It describes that learning calculation is performed by selecting the optimal data collection timing for each item.

[0026]

However, the thickness accuracy at the time of changing the running distance in the conventional control method is described in JP-A-8-332508 having a variable mill constant control device.
Except when the mill constant is equivalently set to infinity, it largely depends on the prediction accuracy of the rolling loads PA and PB before and after the change in running distance.

For example, as shown in FIG. 9, the difference ΔPA1, between the predicted rolling load value and the actual rolling load value before and after the change in running distance,
When ΔPB1 is small, or as shown in FIG. 10, the differences ΔPA2 and ΔPB2 between the predicted rolling load value and the actual rolling load value.
When the values are equal to each other, the conventional control method can realize a highly accurate plate thickness accuracy. However, as shown in FIG. 11, the rolling load prediction error ΔPA3 in the preceding material is large, but the rolling load prediction error in the succeeding material is large. If the error ΔPB3 is small, it is not possible to realize a highly accurate plate thickness accuracy.

As shown in FIG. 10, when the rolling load prediction errors are the same, the rolled material to which the same rolling load model (formula (8) described later) and the parameters are applied is set as the leading material and the succeeding material. In the case where the change amount between runs is small and the pattern of the rolling load prediction error is different as shown in FIG. 11, the rolling material to which different rolling load models or parameters are applied is set as a leading material and a succeeding material. Applicable when combined.

Therefore, according to the conventional control method, when joining dissimilar steel types or when making large dimensional changes, not only the accuracy of predicting the rolling load of the preceding and succeeding materials is improved, but also the pattern of occurrence of each error is increased. It is necessary to pay attention to
This was a major constraint in determining the combination of preceding and succeeding materials. Further, when the running distance is changed while performing the mill constant variable control, the rolling position is positively changed in accordance with the rolling load prediction error, and the rolling load prediction error is enlarged. There was a great need to increase the rolling load prediction accuracy, for example, inducing plate shapes that would cause problems.

The present invention has been made to solve the above-mentioned conventional problems, and reduces the load for improving the rolling load prediction accuracy immediately before the change in running distance and improves the rolling load prediction accuracy for the succeeding material. That is the task.

[0031]

SUMMARY OF THE INVENTION According to the present invention, a target product thickness, width, and width can be changed by changing a rolling position between runs.
In the method of changing the running setting of a rolling mill that continuously manufactures different rolling materials such as steel types without stopping the rolling mill, the running change point is tracked, and the running change point reaches the stand. Immediately before, the actual rolling load value of the stand is collected, and the actual rolling load value, the predicted rolling load value after the change in running distance, and the sheet thickness set values before and after the changing of the running distance are used to reduce the rolling during the changing of the running distance. This solves the problem by calculating the position change amount and changing the rolling position corresponding to the rolling position change amount according to a predetermined change pattern from the timing when the running change start point reaches the stand. is there.

The present invention also includes a mill constant variable control device for determining a rolling position operation amount proportional to a variation in the rolling load, and correcting the rolling position rolling position reference based on the rolling position operation amount. By changing the rolling position, the target product sheet thickness, sheet width, different rolling materials such as steel type,
In the method for changing the running distance setting of a rolling mill that is continuously manufactured without stopping the rolling mill, the running change point is tracked, and immediately before the running change point reaches the stand, the rolling load performance of the stand is measured. Using the actual rolling load value, the predicted rolling load value after the change in running distance, and the sheet thickness set values before and after the changing of the running distance, the amount of change in the rolling position at the time of changing the running distance is calculated. From the timing when the change start point reaches the stand, the rolling position corresponding to the rolling position change amount is changed according to a predetermined change pattern,
This has solved the above-mentioned problem.

Immediately before the change point between runs reaches the stand, actual values such as the thickness of the entrance side, the thickness of the exit side, and the temperature of the exit side of the stand are also collected, and the actual values are used to execute the run. The prediction accuracy is further improved by correcting the rolling load prediction value after the change of the interval.

In the present invention, by using the actual rolling load value of the preceding material, the load for improving the rolling load prediction accuracy immediately before the change in running distance is reduced, and the rolling load prediction accuracy of the succeeding material is improved. .

The operation of the present invention will be described below with reference to FIG. In FIG. 1, broken lines A ', B', C ', D'
Are respectively the measured values of the plastic curve A, B, mill stiffness curve C, D of FIG.

In determining the roll position change amount ΔSnew from the preceding material to the succeeding material according to the present invention, the rolling position SAact of the preceding material is calculated by the following equation.

SAact = hAcmp-SmAact (6)

Here, hAcmp is a set thickness value or an actual thickness value, and SmAact is a mill elongation obtained from an actual rolling load.

Also, the set value SBcmp of the rolling-down position in the succeeding material
Is calculated from the above equation (2) or the following equation (7).

SBcmp = hB-SmBcmp (7)

Here, SmBcmp is the mill elongation predicted value (= SmB) obtained by using the rolling load predicted value of the succeeding material or the mill elongation obtained by using the following corrected rolling load predicted value. It is a predicted value.

The rolling load prediction of the succeeding material, which is corrected using the actual rolling load value of the preceding material, is performed, for example, in the following procedure. Note that this correction is an effective method for a combination of a preceding material and a following material for which load prediction is performed using the same rolling load model and parameters.

The rolling load P is, in general, is expected Ri by the following equation.

P = km × W × Ld × Qp (8)

Here, km is the deformation resistance (a function of the incoming side plate thickness, the outgoing side plate thickness, temperature, components, etc.), W is the plate width, and Ld is the contact arc length (roll diameter, function of the incoming side plate thickness, the outgoing side plate thickness). ) And Qp are rolling force functions (functions such as roll diameter, entrance side plate thickness, exit side plate thickness, friction coefficient, etc.).

Equation (8) shows the actual rolling load value PAa of the preceding material.
Enter values other than deformation resistance, such as ct, the actual value of the inlet thickness (or set value), the actual value of the outlet thickness (or set value), etc.
The reverse deformation resistance kmAact is calculated by the following equation.

KmAact = PAact / (WA × LdA × QpA) (9)

The ratio between the inversely calculated deformation resistance kmAact and the deformation resistance prediction value kmAmdf obtained by inputting each actual value to the deformation resistance model and calculating again is calculated by the equation (10), and (11)
The deformation resistance of the following material is corrected by the equation.

RkmA = kmAact / kmAmdf−1 (10) kmBcmp = (1 + gain × rkmA) * kmB (11)

Here, gain is the correction gain, and kmB is the deformation resistance of the succeeding material calculated from the deformation resistance model.

The deformation resistance correction value km for the following material
Using Bcmp, the rolling load prediction value of the succeeding material is calculated by equation (8), and the mill elongation SmBcmp is determined.

The rolling position change amount ΔSnew is determined by the following equation using the preceding material rolling position actual value SAact and the succeeding material rolling position setting value SBcmp.

ΔSnew = SBcmp−SAact (12)

When the mill constant variable control is performed,
In calculating the mill elongations SmAact and SmBcmp, the equivalent mill constant Meq calculated by the above equation (3) is used.

The equivalent plasticity constant Qeq calculated by the following equation (shown by the straight line E in FIG.
Is used, the preceding material rolling load PA used for calculating the equivalent plasticity constant is calculated using the preceding material rolling load actual value according to the present invention.

Qeq = − (PB−PA) / (hB−hA) (13)

It is to be noted that the rolling position change amount ΔS determined by the prior art is compared with the rolling position change amount ΔSnew according to the present invention, and, for example, an intermediate value between the two is selected as the rolling position change amount, or the absolute value of both is determined. It is also possible to select the smaller one as the amount of change in the rolling position, and both are included in the scope of the present invention.

[0058]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In this embodiment, the present invention is applied to a rolling mill provided with a work roll 12 for rolling a rolled material 10 and a backup roll 14, and the rolling load applied to the work roll 12 is reduced as shown in FIG. The apparatus includes a load detector 20 for detecting, a rolling position control device 22, a mill constant variable control device 24, and a rolling position change amount calculating section 30 according to the present invention.

In this embodiment, as shown in FIG.
Rolling load actual value PAact, incoming sheet thickness actual value HAact, outlet sheet thickness actual value hAact, outlet temperature actual value TAact, rolling load predicted value PA, sheet thickness set value hA,
And the predicted rolling load value PB of the succeeding material and the set thickness value hB
Is input to the rolling position change amount calculation unit 30.

The rolling position change amount calculating section 30 takes in the tuning rate α set in the mill constant variable control device 24, corrects the mill constant by the equation (3), and then (6), (7) The roll-down position and the roll-down position set value of the preceding material and the succeeding material are calculated using the formula, and the roll-down position change amount is determined by the formula (12).

From the timing when the running change point reaches the stand, the amount of change in the rolling position is output to the rolling position control device 22 in accordance with a predetermined change pattern (for example, a linear shape), and the rolling position is changed.

In this embodiment, since the rolling position is changed linearly, the control is simplified. The pattern for changing the rolling position is not limited to this.

[0064]

EXAMPLE In accordance with the present invention, when the plate thickness is changed from 1.6 mm to 1.2 mm between runs, the tuning rate α of the mill constant variable control is set to 0.8, as shown in FIG. The rolling load prediction error ΔPA3 = 2 in the preceding material
000 kN, rolling load prediction error ΔPB3 =
FIG. 3 (conventional example) and FIG. 4 (the method of the present invention) show changes in the sheet thickness and the rolling load at 0 kN. In the prior art shown in FIG.
Due to the influence of N, the setting in the closing direction is larger than the rolling position for realizing the set value of the following material thickness, and a thickness variation of −80 μm occurs. However, in the present invention shown in FIG. Since it is not affected by the rolling load error, the target thickness accuracy is achieved.

[0065]

According to the present invention, since the amount of change in the rolling position for realizing a predetermined change in the thickness of the delivery side plate can be set with high accuracy, the running distance can be changed stably and with high accuracy. Thereby, improvement in productivity and yield can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between a mill stiffness curve and a plastic curve for explaining the principle of the present invention.

FIG. 2 is a block diagram showing an example of the overall configuration of a control device for implementing the present invention.

FIG. 3 is a diagram showing an example of a control result according to the related art.

FIG. 4 is a diagram showing an example of a control result according to the present invention;

FIG. 5 is a diagram for explaining a conventional method for changing a running distance.

FIG. 6 is a diagram showing a relationship between a mill stiffness curve and a plasticity curve when a running distance is changed.

FIG. 7 is a block diagram showing the overall configuration of a control device proposed in Japanese Patent Application Laid-Open No. 8-332508.

FIG. 8 is a diagram showing a relationship between a mill stiffness curve and a plastic curve when a rolling position is changed in Japanese Patent Application Laid-Open No. 8-332508.

FIG. 9 is a diagram showing an example of an occurrence pattern of a rolling load prediction error.

FIG. 10 is a diagram showing another example.

FIG. 11 is a diagram showing still another example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Rolled material 12 ... Work roll 14 ... Backup roll 20 ... Load detector 22 ... Roll-down position control device 24 ... Mill constant variable control device 30 ... Roll-down position change amount calculation part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takao Uchiyama 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Hiroshi Shiomi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corp. Chiba Works (56) References JP-A-11-290920 (JP, A) JP-A-59-174207 (JP, A) JP-A-6-190412 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (3)

(57) [Claims] (1) By changing a rolling position between runs, a target material to be rolled having a different product thickness, a width, a steel type, etc., can be obtained.
In the method of changing the running distance setting of a rolling mill that is continuously manufactured without stopping the rolling mill, the running distance changing point is tracked, and immediately before the running distance changing point reaches the stand, the actual rolling load of the stand is obtained. Using the actual rolling load value, the predicted rolling load value after the change in running distance, and the sheet thickness set values before and after the changing of the running distance, the amount of change in the rolling position at the time of changing the running distance is calculated. A method for changing the running distance setting of a rolling mill, wherein a rolling position corresponding to the rolling position change amount is changed in accordance with a predetermined change pattern from a timing at which a change start point reaches the stand. 2. A mill constant variable control device for determining a rolling position operation amount proportional to a variation in rolling load, and correcting a rolling position reference of a rolling roll based on the rolling position operation amount, and changing a rolling position between runs. By doing this, in the method of changing the running distance setting of a rolling mill that continuously manufactures rolled materials having different target product thicknesses, widths, and steel types without stopping the rolling mill, Tracking and immediately before the change point between running reaches the stand, the actual rolling load value of the stand is collected, and the actual rolling load value, the predicted rolling load value after changing the running distance, and Using the plate thickness set value, the amount of change in the rolling position when changing between runs is calculated, and the rolling position corresponding to the amount of change in the rolling position is changed by a predetermined amount from the timing when the start point of changing between runs reaches the stand. According to the pattern An inter-running setting change method of a rolling mill, characterized by further. 3. Immediately before the change point between runs reaches the stand, actual values such as the entrance plate thickness, the exit plate thickness, and the exit temperature of the stand are also collected, and the actual values are used to perform the run. The running distance setting change method for a rolling mill according to claim 1 or 2, wherein the rolling load predicted value after the change of the distance is corrected.