JPH0661568B2 - Rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] When a metal plate is used as a structural member, there are many cases in which the required strength is different for each part, and in such a case, a plate whose plate thickness partially changes May be required. As shown in FIGS. 4 (a) to 4 (c), the difference thickness plate having a shape in which flat plates having different plate thicknesses are connected to each other is a metal plate product having such a change in plate thickness.
(A), a taper plate (b) in which the plate thickness changes in an inclined shape, and a corrugated plate (c) in which the plate thickness changes in a wavy shape. The present invention relates to a method for rolling a metal plate including the above-mentioned steel plates, the plate thickness of which changes in an arbitrary pattern in the longitudinal direction.

[Conventional technology]

As a rolling method of a metal plate product having a changed plate thickness (hereinafter, referred to as a changed plate material), as described in, for example, Japanese Patent Publication No. 46-37086, only the final pass is the gap between the rolls sequentially from the rolling biting position. A control method for changing the is generally performed.

Further, in Japanese Patent Publication No. 61-50687, the roll gap is finely adjusted only in the final pass in consideration of the difference in the plasticity coefficient of the rolled material between the increased thickness portion and the reduced thickness portion. A method of accurately realizing the plate thickness change pattern of is proposed.

By utilizing these methods, the aforementioned differential thickness plate,
It became possible to automatically roll a plate thickness variable material such as a taper plate, and it became possible to realize a target plate thickness change pattern with much higher accuracy than in the case of manual rolling.

[Problems to be Solved by the Invention]

However, these conventional methods have the following drawbacks.

The conventional rolling does not give a difference in strip thickness over a plurality of passes, but builds a target strip thickness change pattern in the final single pass, so the ability of the rolling mill (maximum rolling load, maximum torque, The maximum bite angle and the maximum change amount of the roll gap per pass) greatly limit the pattern of change in plate thickness that can be realized.

No consideration is given to the effect of changing the roll gap on the flatness of the material to be rolled. That is, normally, when a plate thickness varying material is manufactured by rolling from a material having the same thickness in the longitudinal direction, distortion occurs according to the plate thickness variation. When this distortion is remarkable, a wave at the center of the material to be rolled, called a medium wave, and a wave at the edge of the material to be rolled, called an ear wave, are formed, and as a result, the rolled material to be rolled lacks significantly flatness. Will be things.

Since it is a feedforward control system in principle, it cannot compensate for a prediction error such as the plasticity coefficient of the material to be rolled or a dimensional error caused by an unpredictable disturbance such as temperature deviation.

In order to solve the above problems, the present inventors have tried various methods, but the amount of calculation is considerably larger than that of ordinary plate thickness control, and the development of a rolling control system based on these methods. Since the adjustment load was very high, it was extremely difficult to realize.

INDUSTRIAL APPLICABILITY The present invention solves the above problems, and when rolling a sheet thickness varying material, it is possible to realize a far more diverse sheet thickness varying pattern as compared with the case where a sheet thickness varying pattern is formed in one pass. Distortion can be suppressed, good flatness can be maintained, the target thickness change pattern can be realized with high accuracy by utilizing the automatic thickness control circuit, and it is necessary to determine the thickness deviation to be given in each pass in advance. It provides a rolling method that can significantly reduce the number of calculations on a computer because there is no such problem.

[Means for Solving the Problems] The present invention is to roll a material having a constant thickness in the longitudinal direction to produce a metal plate product in which the thickness distribution in the longitudinal direction is arbitrarily changed, prior to the rolling. A rolling pass schedule for finishing a flat plate having an average thickness of the thickness distribution in the longitudinal direction of the metal plate product (hereinafter referred to as a target thickness change pattern) from the material is created and rolling is started. In, at least, from the flat plate rolling pass to the thickness that first exceeds the maximum value of the target thickness change pattern of the metal plate product to the final flat plate rolling pass, for each pass, the set output thickness of the flat plate rolling pass (target The roll gap based on the output side plate thickness) is set in the automatic plate thickness control circuit, and the roll gap in the pass is set to the set output side thickness of the flat plate rolling pass (target output side plate thickness pattern). And the thickness at each position in the longitudinal direction of the metal plate product (plate thickness deviation pattern) is changed to a plate thickness imparting pass that changes the set roll gap according to a value that is corrected to a range in which flatness can be maintained. In addition, the rolling method is characterized in that the value of the feedback gain by the automatic plate thickness control circuit in this plate thickness imparting pass is set to a larger value as it is closer to the final pass, and rolling is performed.

[Action]

There have been many findings from the past regarding the rolling of a so-called flat plate having the same thickness in the longitudinal direction, and it is easy to prepare a rolling pass schedule for rolling the flat plate by various publicly known means. In the present invention, prior to rolling, a rolling pass schedule for finishing a flat plate having a value between the maximum target thickness and the minimum target thickness in the plate thickness varying material from a material having a predetermined thickness to a flat surface is created. As a result, the outgoing target plate thickness in each rolling pass is determined.

Next, according to the flat plate rolling pass schedule and the target plate thickness change pattern, in the flat plate pass schedule, after any intermediate pass of the rolling pass up to the thickness exceeding the maximum thickness of the target plate thickness change pattern of the product, the final pass Up to are specified as the paths that give the plate thickness difference. For example, one to a plurality of passes in reverse order from the final pass of the flat plate rolling pass schedule are designated as passes for giving a sheet thickness difference (hereinafter referred to as sheet thickness difference giving paths).

Generally, (1) the difference between the maximum thickness and the minimum thickness of the target thickness change pattern is large, (2) the maximum value of the rate of change of the thickness change pattern in the longitudinal direction (the maximum value of the thickness difference per unit length). However, (3) The smaller the amount of reduction per pass in the rolling pass schedule, the more passes this plate thickness difference imparting need to take. By this operation, it is possible to realize a much wider variety of plate thickness change patterns as compared with the case where a plate thickness change pattern is created in one pass.

In each rolling pass of the plate thickness difference giving pass, as the input input to the automatic plate thickness control circuit, the target plate thickness change pattern set value of the product at the longitudinal position centered on the target delivery side plate thickness of the pass of the plate rolling pass schedule The plate thickness deviation between and is output from the computer according to the progress of the material to be rolled. When the strip thickness deviation is output over a plurality of passes by the reversible rolling mill, the applied input has a pattern in which the front and rear are inverted for each pass.

In the rolling of all of the passes in the plate thickness difference imparting pass, the feedback gain of the automatic plate thickness control circuit such as the Visler method is set small in the upstream pass and large in the downstream pass close to the final pass. By this operation, in the upstream pass, the fluctuation of the roll gap is absorbed by the elongation of the mill housing and the fluctuation of the roll deflection, so that the plate thickness deviation is limited to a fraction of the fluctuation of the roll gap, and the distortion at each position in the longitudinal direction is generated. It can be suppressed. Then, since a plate thickness change pattern that is already close to the target plate thickness change pattern to some extent from the upstream pass is gradually given to the flat plate rolling pass schedule, the occurrence of distortion at each position in the longitudinal direction in the downstream pass is also minimized. . Further, since the feedback gain is maximized in the final pass, the fluctuations of the elongation and roll deflection of the mill housing are automatically compensated by the strong feedback action, so that the rolling is performed according to the plate thickness deviation, and the target plate thickness change pattern can be accurately produced. Can be realized. Therefore, good flatness can be maintained over each rolling pass.

〔Example〕

 Hereinafter, specific examples of the present invention will be described.

FIG. 1 shows an example of a control system for carrying out the present invention.

Hereinafter, a specific calculation processing procedure will be described with reference to FIG.

(1) The computer 1 creates a flat plate rolling pass schedule for finishing a flat plate having an intermediate thickness of a target thickness change pattern flat, and sets the final pass number to N.

(2) Next, according to this rolling schedule, the number of passes of the plate thickness difference imparting pass and the AG of the plate thickness difference imparting pass i of the Bisler system
The value of the feedback gain Ci of the C controller 2 is determined. In the present invention, the number of passes for providing the plate thickness difference is a table value based on the difference between the maximum thickness and the minimum thickness of the target plate thickness change pattern and the wave pitch.

The feedback gain Ci is a function depending on the number of passes i as shown in FIG. In the figure, Ci <1 in any of the passes, but in a normal operation, a plate thickness within the tolerance can be sufficiently achieved by setting approximately Ci> 0.8.

It should be noted that the number of passes for providing the plate thickness difference and the feedback gain C
As a parameter for determining i, it is also possible to adopt an amount other than the above, for example, an absolute value of the minimum thickness, a deformation resistance of the rolled material, or the like.

(3) In the plate thickness difference providing path i, first, the schedule roll gap of the plate is set.

Further, the feedback gain Ci of the rolling pass, the schedule rolling load i of the flat plate, and the mill rigidity Mi are given to the AGC controller 2 as initial conditions.

During rolling of pass i, the gap change amount command value ΔSi (x) calculated by the following equation is output to AGC controller 2 (the gap tightening direction is +).

ΔSi (x) = − (HN (x × c) −N) (1) where HN (x): target thickness change pattern x: longitudinal position c: length correction coefficient (c = i / N) N: The average thickness in the longitudinal direction of the metal plate product in which the thickness distribution in the longitudinal direction is arbitrarily changed. In other words, the finished average thickness of the final pass i: The outgoing plate thickness of the pass i in the flat plate rolling schedule. x is a product obtained by integrating the output values of the pulse generator 4 connected to the work roll 3 and multiplying it by the pulse width and the advanced rate correction coefficient to convert it into a rolling length.

(4) The AGC controller 2 calculates the mill spring (total of elongation of the housing, deflection of the roll, etc.) Fa / Mi from the rolling load measured by the load cell 5, and calculates the difference between this value and the planned mill spring i / Mi. The gain Ci is multiplied and fed back to the gap change command value.

In this case, the variation ΔHi (x) of the strip thickness of the rolled material is given by the following equation.

ΔHi (x) = ΔSi (x)-(1-Ci) × (Fa-i) / Mi (2) That is, the change in plate thickness of the rolled material is corrected by the second term on the right side.

In this way, the correction amount is gradually reduced in the N number of passes of the plate thickness difference providing pass, and is minimized in the final pass to provide the plate thickness deviation according to the target plate thickness change pattern of the product to the rolled material. it can.

Note that in actual operation, the gain Ci is usually set to a value smaller than 1 in order to stabilize the control system in the AGC control. In this case, if the value of Ci is set as large as possible without disturbing the stability of the system, preferably Ci> 0.8, a plate thickness within the tolerance can be sufficiently realized.

As described above, depending on the method of selecting Ci in each automatic plate thickness control up to the absolute value AGC of the final pass, the plate thickness deviation Δ given around the target delivery side plate thickness of the flat plate rolling pass schedule by the pass i
It can be seen that Hi can be controlled. Moreover, Calculator 1
It is only necessary to calculate ΔSi (x) according to the equation (2), and there is no need to perform a complicated calculation in consideration of mill spring fluctuation due to gap change.

Third example of rolling according to the above processes (1) to (4)
Shown in the figure. Table 1 shows the rolling conditions and the actual rolling values.

The target was a sinusoidal plate thickness variation pattern with an amplitude of 3 mm and a pitch of 5650 mm. In the example of FIG. 3, the plate thickness difference is continuously applied in three passes including the final pass, and the absolute value A is further applied in the final pass.
GC was applied. The black circle in the figure is 100 mm from the edge of the rolled material.
The values obtained by actually measuring the inner plate thickness with a micrometer, and the curves are sine curves fitted to these measurement points using the method of least squares. The actual values in Table 1 show the error between the representative value (maximum thickness, minimum thickness, pitch, and phase) of this sine curve and the target value.

Table 2 shows a comparison with the conventional method.

In each case, the target is the sinusoidal plate thickness change pattern of the amplitude and pitch shown in the left column of Table 2. Rolling method a is a case where a plate thickness difference is given only in the final pass (no absolute value AGC), and b is an example of rolling by this method.
Regarding b, as in the example shown in FIG. 4, the plate thickness difference was continuously applied in three passes including the final pass, and the absolute value AGC was applied in the final pass. As the actual values in Table 2, as in the case of Table 1, a representative value of a sine curve fitted to a series of actually measured points by the method of least squares is used.

In case A, it can be seen that the dimensional accuracy (maximum thickness, minimum thickness, pitch) of the case b is much higher than that of the conventional example a. Further, the rolled finish shape was almost completely flat in the case of b, and in the case of a, the medium wave was generated in the maximum thickness portion and the ear wave was generated in the minimum thickness portion.

In Case B, it was impossible to give a predetermined plate thickness difference only in the final one pass. Even in this case, b was able to be realized with high dimensional accuracy and flatness.

〔The invention's effect〕

As described above, according to the present invention, when rolling the sheet thickness varying material, a far more diverse sheet thickness varying pattern can be realized as compared with the case where the sheet thickness varying pattern is formed in one pass. It is possible to suppress the occurrence of distortion at the position, maintain good flatness, and realize a target thickness change pattern with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an automatic plate thickness control system for carrying out the present invention, FIG. 2 is a diagram showing an example of a feedback gain Ci used in the embodiment of the present invention, and FIG. FIG. 4 is a diagram showing an actual measurement value of a sheet thickness profile obtained by the actual rolling result by the method, and FIG. 1 ... Computer, 2 ... AGC controller, 3 ... Work roll, 4 ... Pulse generator, 5 ... Load cell, 6 ... Cylinder position detector, 7 ... Servo valve,
8 ... Hydraulic cylinder, 9 ... Backup roll, Ci
... Feedback gain of AGC circuit, G: servo amplifier gain, x: longitudinal position of rolled material, Sa, Fa:
Measured roll gap, load, Si, i, i: path i
Target average roll gap, exit side plate thickness, load, Mi: mill rigidity of pass i, HN (x): target plate thickness change pattern,
N: HN (x) average value in the longitudinal direction, ΔSi (x): Roll gap change command value of path i.

Claims (1)

[Claims] 1. When manufacturing a metal plate product in which a material having a constant thickness is rolled in the longitudinal direction to arbitrarily change the thickness distribution in the longitudinal direction, the metal plate product is preliminarily cut from the material prior to the rolling. Start rolling by creating a rolling pass schedule for finishing into a flat plate having an average thickness of the thickness distribution in the longitudinal direction, and in the course of this flat plate rolling pass schedule, at least the maximum value of the thickness distribution in the longitudinal direction of the metal plate product. From the flat plate rolling pass to the thickness that exceeds the first to the final flat plate rolling pass, the roll gap based on the set output thickness of the flat plate rolling pass is set in the automatic plate thickness control circuit for each pass, and the rolls in the pass are set. The gap is set by the value obtained by correcting the deviation between the set-out side thickness of the flat plate rolling pass and the thickness at each position in the longitudinal direction of the metal plate product to a range in which flatness can be maintained. Rolling is performed by changing to a plate thickness giving pass that changes the roll gap, and the value of the feedback gain by the automatic plate thickness control circuit in this thickness giving pass is set to a larger value for the pass closer to the final pass, and rolling is performed. And rolling method.