JPH0661567B2 - 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. 3 (a) to 3 (c), a metal plate product with such a change in plate thickness has a difference thickness plate formed by connecting flat plates having different plate thicknesses.
(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.

No consideration has been given to the method of providing the plate thickness difference over a plurality of passes. Therefore, the target strip thickness change pattern is built in the final 1 pass, but in this case, depending on the ability of the rolling mill (maximum rolling load, maximum torque, maximum biting angle, maximum change amount of roll gap per pass), The plate thickness change pattern that can be realized is greatly limited.

No consideration is given to the effect of changing the roll gap on the flatness of the material to be rolled. Normally, when a plate thickness varying material is manufactured by rolling from a material having the same thickness in the longitudinal direction,
Strain is generated 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.

Regarding the plate thickness control, it is an open loop control system in principle, and it is not possible to compensate for a dimensional error caused by an unpredictable disturbance such as a plastic coefficient of the material to be rolled or a temperature deviation.

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. The present invention provides a rolling method capable of suppressing the occurrence of strain and maintaining good flatness, and utilizing an automatic plate thickness control circuit to realize a target plate thickness change pattern with high accuracy.

[Means for Solving the Problems]

In the present invention, in the production of a metal plate product in which a material having a constant thickness is rolled in the longitudinal direction and the thickness distribution in the longitudinal direction is arbitrarily changed, prior to the rolling, the longitudinal direction of the metal plate product is obtained from the material. The thickness distribution in the direction (hereinafter referred to as the target thickness change pattern) is used to create a rolling pass schedule for finishing into a flat plate having an average thickness, and rolling is started. In the middle of this flat plate rolling pass schedule, at least the metal plate product From the flat plate rolling pass that first exceeds the maximum value of the target thickness change pattern to the final flat plate rolling pass, the roll gap based on the set output side thickness (target output side plate thickness) of the flat plate rolling pass is set for each pass. The roll gap in the pass is set, and the set exit side thickness (target exit side plate thickness pattern) of the flat plate rolling pass and the thickness at each position in the longitudinal direction of the metal plate product are set. Deviation (plate thickness deviation pattern) is changed to a range in which the flatness can be maintained and changed to a plate thickness imparting pass in which the set roll gap is changed, and the final pass adopts AGC. It is a rolling method.

[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 is prepared in which a flat plate having a value between the maximum target thickness and the minimum thickness in the plate thickness varying material is finished flat from a material having a predetermined thickness. As a result, the output-side average target plate thickness in each rolling pass is determined.

In general, in order to prevent deterioration of flatness due to rolling, it is necessary to make the strain generated inside the rolled material within the buckling limit due to the change in the crown ratio before and after rolling. That is, the crown rate change must be kept within a certain range. Here, the crown rate Rc is an amount defined by the following formula.

Rc = (Hc-He) / Ha However, Hc: Thickness in the central part in the strip width direction He: 〃 Edge 〃 Ha: 〃 Average 〃 Outward crown ratio of each pass is mainly due to roll deflection caused by rolling load. It is determined. Therefore, in order to keep the crown rate change within a certain range, it is necessary to determine the amount of reduction so that the rolling load of each pass becomes an appropriate value. FIG. 2 shows this condition by the relationship between the plate thickness and the rolling load. If the delivery side plate thickness and rolling load of each pass are within the region A in FIG. 2, buckling due to the change in crown rate is suppressed, and flatness is maintained.

It goes without saying that the rolling schedule of the flat plate passes through the region A as shown by the polygonal line M in FIG. 2, but the maximum thickness part and the minimum thickness part of the plate thickness varying material are also the plate thickness and load of each pass. It is necessary to determine the amount of reduction of each part so that the relationship of (3) is within the area A as shown by the broken lines T and B in the figure. Therefore, as described below, there may be a case where there are a plurality of passes that give a difference in plate thickness.

Depending on the flat plate rolling pass schedule and the plate thickness change pattern of the target product, in the flat plate pass schedule, from 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, to the final pass Is specified as the path that gives 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).

Therefore, (1) the difference between the maximum thickness and the minimum thickness of the target thickness change pattern of the product is large, and (2) the maximum value of the rate of change of the thickness change pattern in the longitudinal direction of the product (thickness difference per unit length (3) The larger is the maximum value, and (3) The smaller the reduction amount per pass in the rolling pass schedule is, the more the number of passes for providing the plate thickness difference needs to be set. 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 the sheet thickness difference giving path, the sheet thickness deviation pattern between the target sheet thickness change pattern of the product at each position in the longitudinal direction and the delivery side average target delivery side sheet thickness pattern of the pass is calculated at the same time as the rolling material is advanced. When the plate thickness deviation pattern does not fit in the area A, the pattern is changed to the plate thickness deviation pattern of the area A internal reduction amount. The rolling load and the reduction amount of (1) are multiplied by a correction coefficient of 1 or less for fitting in the flatness maintaining relation area, and the plate thickness deviation setting pattern in the pass is output from the computer and input to the setting control circuit or the AGC circuit. When the reversible rolling mill applies a sheet thickness deviation to a plurality of passes, the output has a pattern in which the front and rear are inverted for each pass.

As an advantage of giving the plate thickness difference in the plurality of passes, since the plate thickness change pattern which is close to the target plate thickness change pattern to some extent is already given from the initial pass, the occurrence of strain at each position in the longitudinal direction in the pass is minimized. Therefore, it is possible to maintain good flatness over each pass of the plate thickness difference imparting pass. Furthermore, if the absolute value AGC is applied at least in the final pass, the variation of the mill housing elongation and roll deflection due to the gap change is automatically compensated, and the target thickness change pattern can be realized with high accuracy.

〔Example〕

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

FIG. 1 shows an example of a rolling system configuration 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 flat plate rolling pass schedule, the number of passes of the plate thickness difference giving pass and the plate thickness deviation in the plate thickness difference giving pass are determined.

(2-1) First, it is assumed that the plate thickness difference of the target product is given only in the final pass, and the rolling load at each position in the longitudinal direction in the final pass is calculated. If the exit side plate thickness and rolling load at each position are all within the area A in FIG. 2, the calculation is terminated and the process (3) is performed. If there is a point outside the area A, the process proceeds to (2-2). Here, the region A is registered in the computer 1 as the rolling load upper and lower limits for each delivery side plate thickness.

(2-2) The previous pass of the final pass is also a plate thickness difference imparting pass, and the target plate thickness deviation pattern ΔHi in pass i is determined with the pass number of the pass being i. However, ΔHN is the path i
Is a deviation in plate thickness from the target thickness at each position in the longitudinal direction of the product centered on the target delivery side plate thickness of the flat plate rolling pass schedule.

ΔHi is given by the following equation.

ΔHi = ΔHN × g (N−i) Here, g (N−i) is a plate thickness deviation giving rate, which is given for each pass as shown in FIG. Based on ΔHi, the rolling load at each position in the rolling longitudinal direction in each pass is calculated.
If the rolling load and the plate thickness at each position of each pass are within the area A of FIG. 2, the calculation is ended and the process (3) is performed. If there is a point outside the area A, the process proceeds to (2-3).

(2-3) A pass immediately before pass i is also a plate thickness difference imparting pass,
The same process as (2-2) is performed until the rolling load and plate thickness at each position of each pass fall within the area A of FIG. 2 (2-
The process 3) is repeated to increase the number of passes for providing the plate thickness difference.

By the above processing, the number of passes of the plate thickness difference application and the plate thickness deviation in each pass are determined. As shown in FIG. 2, the rolling pass schedule for the maximum thickness portion and the rolling pass schedule for the minimum thickness portion determined by the above-described method are, as shown in FIG. 2, the maximum thickness portion (the polygonal line T) and the minimum thickness portion (the polygonal line B). The outgoing side plate thickness difference ΔHi becomes larger as the passes are overlapped. A rolling pass schedule of an arbitrary intermediate thickness between the maximum thickness and the minimum thickness passes through a region between the polygonal lines T and B in the figure.

(3) In the plate thickness difference imparting pass i, first, the roll gap of the flat plate rolling pass schedule is set. During rolling of pass i, the gap change amount calculated by the following formula ΔSi (x)
The roll gap Si is changed by an amount (the tightening direction is +).

ΔSi (x) = − (HN (x × c) −N) × ΔHi / ΔHN × K 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 average finished thickness of the final pass K: Influence coefficient where the longitudinal position x is the work roll 3 The output value of the pulse generator 4 connected to is integrated with the pulse width and the advanced rate correction coefficient to be converted into the rolling length. K is an amount defined by the roll gap change amount / plate thickness change amount, which is determined by the rigidity of the mill housing and the roll. However, using the AGC controller 2, the absolute value AG
When C is applied, this rigidity is substantially infinite, so K = 1 may be set.

When the absolute value AGC is applied to at least the final path, the output ΔS of the computer 1 is set in the AGC controller 2.
With respect to i (x), the outputs of the load cell 5 and the roll gap measuring machine 6 are provided by the AGC feedback circuit 9. On the other hand, when the absolute value AGC is not used, the computer output does not go through the AGC feedback circuit 9 and directly becomes a hydraulic cylinder position change command through the bypass circuit 10.

The fifth example of rolling according to the above processes (1) to (3)
Shown in the figure. Table 1 shows the rolling conditions and the actual rolling values. Table 2 shows the rolling pass schedule of this example.

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. 5, 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 3 shows a comparison with the conventional method.

In both cases, the target is a sinusoidal plate thickness change pattern having the amplitude and pitch shown in the left column of Table 3. In the rolling method a, when the plate thickness difference is given only in the final pass and one pass (no absolute value AGC), b is the absolute value AGC in a.
In the case of applying the above, c is an example of rolling according to the present method, and similarly to the example shown in FIG. 5, the plate thickness difference is continuously given in three passes including the final pass, and the absolute value AGC is further given in the final pass. This is the case when applied. As the actual values in Table 3, as in the case of Table 1, the representative values of the sine curve fitted to the actual measurement point sequence by the least square method are used.

In case A, it can be seen that the dimensional accuracy (maximum thickness, minimum thickness, pitch) increases in the order of a, b, and c. Further, regarding the rolled finish shape, in case of c, it is almost completely flat, in case of a and b, middle wave is generated in the maximum thickness portion, and ear wave is generated in the minimum thickness portion. Especially, in the case of b, the wave is cold. It could not be removed by correction.

In Case B, it was impossible to give a predetermined plate thickness difference only in the final one pass. Even in this case, c could be realized with high precision in both 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. The generation of distortion at the position can be suppressed, good flatness can be maintained, and the target thickness change pattern can be realized with high accuracy by utilizing the automatic thickness control circuit.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a rolling system for carrying out the present invention, FIG. 2 is an explanatory diagram of a flatness maintenance allowable range, FIG. 3 is a diagram showing an example of a metal sheet product having a changed sheet thickness, and FIG. FIG. 5 is a diagram showing an example of a plate thickness deviation imparting rate, and FIG. 5 is a diagram showing a plate thickness profile measured value in an actual rolling example according to the present method. 1 ... Calculator, 2 ... AGC controller, 3 ... Work roll, 4 ... Pulse generator, 5 ... Load cell, 6 ... Roll gap measuring machine, 7 ... Hydraulic cylinder, 8 ... Backup roll, 9 ... … AGC feedback circuit, 10… Bypass circuit.

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. Create a rolling pass schedule to finish the flat plate to be the average thickness of the thickness distribution in the longitudinal direction and start rolling, and in the middle 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 first exceeds the final flat plate rolling pass, for each pass, set the roll gap based on the set exit thickness of the flat plate rolling pass, and set the roll gap in the pass to the flat plate rolling pass. The set roll gap is changed according to a value obtained by correcting the deviation between the set output thickness and the thickness at each position in the longitudinal direction of the metal plate product within a range in which the flatness can be maintained. The final pass rolling method characterized by employing the AGC with rolling by changing the plate thickness imparting path to.