JPH07256322A - Method for cold rolling of metal plate - Google Patents

Abstract

PURPOSE:To control a plate width without the restriction of the shape of a rolling stock, and to improve a yield. CONSTITUTION:By using a rolling mill having upper and lower work rolls flexible in the horizontal direction and at least one or more shape changing means possible to change a rolling shape by making the distribution of a plate thickness in the width direction of a rolling stock change at the time of rolling, the flatness and the plate width of the rolling stock, are simultaneously controlled by rolling with at least one roll out of the upper and the lower work rolls bent in the horizontal direction, and by changing the set value of the shape changing means and horizontal bending amount of the work roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cold rolling a metal sheet, and more particularly to a method for rolling a metal sheet which changes the shape and the width of a metal sheet which is a material to be rolled.

[0002]

2. Description of the Related Art In recent years, the demands of customers for the properties of sheet materials manufactured by rolling various materials (hereinafter referred to as "rolled sheet") have become more and more strict, and the sheet shape and sheet width are highly accurate. Control is desired. Hereinafter, a metal plate will be described as an example of the rolled plate.

In general, when a metal plate is rolled, flatness may occur in the rolled plate due to the difference in elongation strain in the rolling direction (longitudinal direction) in the plate width direction. Generally, the case where the longitudinal extension of the plate end is larger than that of the central part is called "ear wave", and conversely, the case where the extension of the central part is larger than that of the plate end is called "medium expansion".

The elongation strain in the rolling direction, which causes the flatness failure, is determined by the relationship between the amount of compressive strain in the plate thickness direction caused by the reduction of the upper and lower work rolls and the amount of strain generated by the plastic flow in the plate width direction. Currently, as a method of preventing flatness failure during rolling, by changing the amount of reduction of the upper and lower work rolls in the strip width direction and controlling the amount of compressive strain in the strip thickness direction, the strain in the rolling direction in the rolling direction can be reduced. Many methods for optimizing the distribution have been developed and are the mainstream of flatness control methods. For example, there are a method of attaching an initial crown to a work roll, a method of using a roll bender, a method of axially shifting an intermediate roll and a work roll, a method of using a variable crown roll, and a roll cross rolling method.

FIG. 2 is a diagram showing the relationship between the strip thickness distribution in the width direction during rolling and the rolling shape. 2 (a) to 2 (c)
The plate end portion, the work rolls 20 when rolled so as to be thinner than the plate central portion, the bending of the work roll 20, the cross-sectional shape of the material 22 to be rolled, and an explanatory view of each of the material to be rolled showing the result,
In this case, the rolled shape becomes an ear wave 24. Also, FIG. 2 (d)
~ Fig. 2 (f) shows the bending of the work rolls 20 and the material to be rolled 22 when rolled so that the edge of the strip becomes thicker than the center of the strip.
It is an explanatory view of the cross-sectional shape of, and the appearance of the material to be rolled showing the results, in this case, the rolled shape is
Becomes

In order to correct such a flatness defect by the above-mentioned method, if the shape is an ear wave, an actuator such as a bender is operated so that the plate thickness at the plate end portion becomes thick, and if it is medium extension. By operating the actuator so that the plate thickness at the plate end portion becomes thin and changing the strain in the plate thickness direction, the elongation strain in the longitudinal direction is made uniform.

By the way, in the rolling of a metal plate, the flatness and the width-direction plate thickness distribution change, as well as the plate width change. It is known that changes in the width direction plate thickness distribution (plate crown) before and after rolling have a large effect on this width variation due to rolling. A method of adjusting to a target value has been proposed (Japanese Patent Laid-Open No. 62-296904). The principle will be described with reference to FIG.

FIG. 3 is an explanatory view of a change in width dimension of the metal plate 22 which is a material to be rolled when the width-direction plate thickness distribution (hereinafter referred to as a plate crown) is different. If the plate width of the reference crown-shaped metal plate (solid line) when rolled under normal operating conditions is W and the plate thickness is t, the thickness (t ') at the end in the width direction of the metal plate with the reference crown condition is When rolled thinner than that (t '<t),
For a metal plate with the same plate thickness at the width center (broken line), the width will increase by ΔW. Conversely, if the thickness (t ') at the end of the strip width is increased (t'> t), the strip width of the rolled metal sheet becomes narrower than the strip width under the standard conditions.

Therefore, in the case of correcting the rolled shape, in the above-mentioned method, the flatness is improved, but at the same time, the plate width fluctuation occurs and the plate width accuracy deteriorates.

On the other hand, as described above, the flatness failure during rolling is also affected by the plastic flow in the strip width direction. This widthwise plastic flow is likely to occur at the plate end, and the reason is that the widthwise constraint is small at the plate end. Therefore, as one of means for eliminating the above-mentioned flatness failure, it is considered to positively utilize the plastic flow in the width direction of the plate end portion.

In recent years, in the field of cold rolling, a 6-high rolling mill (usually Universal-Crown) using work rolls of extremely small diameter is used.
Mill, abbreviated as UC mill), there is a phenomenon that the work roll bends in the horizontal direction and affects the rolling shape due to the relationship between the horizontal rolling reaction force, the force acting between the rolls and the offset amount of the work roll. Reported (Proceedings of the Spring Seminar on Plastic Working, 1993, 369-376)
Page). According to this document, it is said that when the center part of the work roll bends forward (outward side), it becomes an ear wave, and when it bends backward (inward side), it becomes middle stretch.

Further, in the field of hot rolling, a rolling mill of the type in which work rolls are bent in the horizontal direction (usually, Minimum-Edgedr
op mill, or ME mill for short) has been developed and put to practical use ("Plasticity and processing", Vol.31-352 (1990), 632-).
638 pages, Proceedings of the 39th Joint Symposium on Plastic Working 593-596
Page). The rolling mill aims to offset the upper work roll having a small diameter, bend it horizontally by a support roll, change the gap distribution between the upper and lower work rolls, and control the plate thickness distribution in the width direction. It is a rolling machine that
It is shown in the above-mentioned documents that the horizontal work roll deflection causes a frictional force in the plate width direction, and the plastic flow during rolling of the material changes in the width direction. As a result, it is suggested that by controlling the elongation deviation in the width direction, it is possible to change the plate thickness distribution in the width direction while maintaining good flatness of the rolled material.

The principle will be described with reference to FIG. FIG. 4 is a plan view showing the bending of the work roll 40 in the horizontal direction,
The arrow in the figure indicates the direction of the roll rotation vector. Figure 4
(a) shows the work roll 40 in a non-deflected state, Fig. 4 (b) shows the work roll 40 bent in the rolling direction, and Fig. 4 (c) shows the work roll 40 bent in the rolling direction. It is a schematic explanatory drawing of each of the opened state. In this method, as shown in FIG. 4 (b) or FIG. 4 (c), the vector in the direction of rotation of the work roll 40 is inwardly or outwardly compared to the normal rolling as in the case of FIG. 4 (a). Since it is outward and the velocity vector in the plate width direction is different, frictional force is generated in the plate width direction and plastic flow of the material occurs.

[0014]

By the way, the conventional shape control method employs a method of changing the roll gap distribution in the width direction, that is, the plate thickness distribution in the width direction of the material to be rolled, in order to control the flatness. ing. However, when this method is used, there is a problem that the strip width after rolling also varies with the variation of the strip thickness distribution in the width direction. Even if the width variation table value is set to an appropriate value, the width variation amount will also be different if the width direction plate thickness distribution of the base material is different, etc. , It is often a value outside the target value.

Further, in the current operation, rolling is performed with an emphasis on the flatness of the rolled plate due to restrictions such as sheet passing property, and changes in the plate width have not been omitted so much.

Therefore, even if the strip width changes, the minimum width portion needs to be equal to or larger than the product width, and the target width is determined to have a surplus width. When the product was taken after slitting, the cut-out portion was increased and the yield was poor.

The present invention has been made in view of the above circumstances, and it is possible to control the strip width without being restricted by the shape of the material to be rolled, thereby improving the yield. The purpose is to provide.

[0018]

In order to achieve the above object, the inventors of the present invention have conducted various studies, and as a result, as will be described below, the amount of bending of the work roll in the horizontal direction and the plate thickness distribution in the width direction are The present invention has been completed by finding that the above problems can be solved by controlling the above.

That is, the cold rolling method for a metal sheet according to the present invention is such that the upper and lower work rolls that are flexible in the horizontal direction and the strip thickness distribution in the width direction of the material to be rolled during rolling are changed to obtain the rolled shape. In a method for cold rolling a metal sheet by a rolling mill having at least one or more shape changing means capable of changing, rolling is performed by bending at least one of the upper and lower work rolls in a horizontal direction. The flatness and strip width of the material to be rolled are controlled simultaneously by changing the set value of the shape changing means and the horizontal deflection amount of the work roll.

The set value of the shape changing means and the change amount of the horizontal deflection amount of the work roll are calculated in accordance with the correction amount of the plate width, and the set value and the horizontal deflection amount are changed to the two obtained change amounts. May be rolled. Further, even if the set value of the shape changing means and the change amount of the horizontal deflection amount of the work roll are obtained according to the correction amount of the shape, and the set value and the horizontal deflection amount are changed to the two obtained change amounts, rolling is performed. Good.

[0021]

The function of the present invention will be described below. First,
The reason why the shape (flatness) of the rolled plate can be changed by bending the work roll horizontally and performing rolling will be described in detail.

FIG. 5 is a view showing the horizontal deflection of the work roll 40, the widthwise force acting on the rolling plate 42, the direction of width variation, and the shape after rolling. 5 (a) to 5 (c) show the work roll 40 in front.
5 (d) to 5 (d) are explanatory views of the bending of the work roll 40 when bent in a direction projecting to the (outward side), the cross-sectional shape of the rolling plate 42, and the appearance of the rolling plate 42 as a result thereof, respectively. f)
FIG. 6A is an explanatory diagram of the bending of the work roll when the work roll 40 is bent in the rearward (entrance side) direction, the cross-sectional shape of the rolling plate 42, and the resulting appearance of the rolling plate 42.

When the roll 42 protrudes to the exit side as shown in FIG. 5 (a), the rolling plate 42 shown in FIG. 5 (b) is subjected to an outward force in the width direction to widen the width. Therefore, the material is collected at the plate end, and as shown in FIG. 5 (c), the plate end has a large elongation, that is, a state in which the ear wave 44 is generated.

On the contrary, when the work roll 42 projects toward the entrance side as shown in FIG. 5D, the rolling plate 42 shown in FIG.
The inward force acts in the width direction and the width shrinks. for that reason,
The material is collected in the central portion of the plate, and as shown in FIG. 5 (f), the material is in a state where the elongation is large in the central portion of the plate, that is, the state where the intermediate elongation 46 occurs.

By the way, although the shape can be changed by bending such a roll in the horizontal direction, since the plastic flow in the width direction changes, the width also changes at the same time. However, it has been confirmed by experiments that the width variation caused by the bending of the roll in the horizontal direction is much smaller than the width variation caused by the change in the plate thickness distribution, and does not hinder the effect of the present invention.

That is, the relationship between the shape and width variation of the rolled plate was compared when only the widthwise plate thickness distribution was changed under the same rolling conditions and when only the roll horizontal direction bending was applied. The results are shown graphically in FIGS. 6 (a) and 6 (b).

In this example, as shown in FIGS. 7A and 7B, work rolls 70, 70, intermediate rolls 72, 72, reinforcing rolls 74, 74.
A 6-high rolling mill including a work roll bender 76 and a horizontal support roll 78 was used to perform rolling in one pass. Here, the working roll diameter is 100 mm, the intermediate roll diameter is 420 mm, the reinforcing roll diameter is 980 mm, and the roll body length is 1200 mm.
The rolled material had a plate thickness of 2.6 mm, a plate width of 1000 mm, and a rolling reduction of 30%.

A roll bender 76 equipped in the rolling mill of FIG. 7 (a) is used as a width direction plate thickness distribution changing means, that is, a shape changing means. Changed. Further, as a means for bending the work roll in the horizontal direction, a pair of horizontal flexible support rolls 78 on the input side and the output side shown in FIG. 7B and its details are used, and the pushing amount of the support roll 78 is changed. The amount of deflection was changed accordingly.

FIGS. 6 (a) and 6 (b) show the relationship between the rolled shape after rolling and the sheet width fluctuation amount, and the relationship between the rolled shape and the sheet crown amount, respectively. Here, the rolled shape is expressed by converting the difference in elongation between the position 10 mm from the plate edge and the center of the plate into a steepness, with the selvages as positive and the middle elongation as negative. The sheet width variation was calculated by taking the difference between the widths before and after rolling, with the width expansion being positive and the width contraction being negative. The plate crown amount is represented by the plate thickness at the center of the width minus the plate thickness at a position of 10 mm from the plate edge.

From the results shown in FIG. 6 (a), when the rolled shape changes from the selvage wave to the middle elongation, the plate width variation amount changes from the width expansion to the edge contraction, but the roll bender changes the plate thickness distribution. It can be seen that the amount of width variation is considerably smaller in the case where horizontal deflection is applied (marked with Δ in the figure) than in the case where it is changed (marked with ○ in the figure).

From the results shown in FIG. 6 (b), when rolling using a roll bender (circle in the figure), when the rolling shape changes from selvage to medium elongation, the amount of plate crown changes from positive to negative. On the other hand, in the case of horizontal deflection (marked with Δ in the figure), the amount of plate crown has hardly changed. However, although it is a small amount, it qualitatively agrees with the condition that the strip thickness distribution is changed.This is because the rolling pressure distribution changes slightly due to the change in the transverse plastic flow, and It is thought to have influenced the bending and flatness of the.

From these results, there is no effect on the shape after rolling between the method of changing the sheet thickness distribution by a shape changing means such as a roll bender and the method of changing the plastic flow by bending the work roll in the horizontal direction. Although it is almost equivalent, it can be seen that the influence on the width variation is extremely small in the method of giving the bending in the horizontal direction as compared with the method of changing the plate thickness distribution.

Next, based on the knowledge obtained here, the basic idea of the present invention will be described. Shape change means for changing shape and plate thickness due to width change (here, the roll bender is taken as an example. Therefore, the control element is the roll bend pressure) and the correlation between the horizontal deflection amount and the coil dimension specifications. In accordance with the above, for each coil, for example, a relational expression as shown in the following expression is obtained.

Ε ₁ = a ₁ + b ₁ P ··· (1) ε ₂ = a ₂ + b ₂ Y ··· (2) W ₁ = c ₁ + d ₁ P ··· (3) W ₂ = C ₂ + d ₂ Y ··· (4) ε ₁ , ε ₂ : Plate shape at a certain roll bender pressure and horizontal bending amount (expansion difference between any position in the width direction and the center position in the width direction) W ₁ , W ₂ : Roll roll bender pressure, plate width at horizontal deflection amount P: Roll bend pressure Y: Horizontal deflection amount of work rolls a ₁ , b ₁ , c ₁ , d ₁ and a ₂ , b ₂ , c ₂ , d ₂ :
Parameters determined for each coil (known amount) Here, the equation (4) takes into consideration the effect on the plate thickness distribution of the equivalent roll crown caused by the horizontal deflection.

If the strip width is W during rolling, the strip width W
Is expressed as the following equation (5) by the sum of equations (3) and (4). W = c ₁ + c ₂ + d ₁ P + d ₂ Y (5) Similarly, if the shape is ε during rolling, the plate shape ε can be calculated by the following equation (6) according to the sum of equations (1) and (2). ). ε = a ₁ + a ₂ + b ₁ P + b ₂ Y (6) Therefore, by solving the above equations (5) and (6) simultaneously,
It is possible to simultaneously correct the shape and width of the rolled plate to the target value.

FIG. 1 is an explanatory view of the principle of the present invention, and is a graph showing the relationship between the value of the actuator as a means for controlling the shape by changing the distribution of plate thickness and the horizontal deflection amount of the work roll. The horizontal axis represents the value of the shape control actuator (here, the roll bend pressure P as an example), and the vertical axis represents the horizontal deflection amount Y of the work roll. In the graph, R _E is
Roll bend pressure for rolling shape expressed by Eq. (6) −
R _W is a curve showing the relationship between the work roll horizontal deflection amount and R _W is a curve showing the relationship between the roll bend pressure and the work roll horizontal deflection amount with respect to the plate width correction amount represented by the equation (5). It represents a simultaneous solution that satisfies Eqs. (5) and (6). Therefore, regarding the target plate width and shape change amount,
By using the values of the horizontal axis and the vertical axis at the points where R _E and R _W intersect as the change amounts, the shape and the plate width can be corrected at the same time.

Therefore, according to a preferred embodiment of the present invention,
The set value of the shape changing means and the change amount of the horizontal deflection amount of the work roll are obtained according to the correction amount of the strip width, and the set value and the horizontal deflection amount are changed to the obtained two change amounts, and rolling is performed. Alternatively, the set value of the shape changing means and the change amount of the horizontal deflection amount of the work roll are calculated according to the correction amount of the shape, and the set value and the horizontal deflection amount are added to the obtained two change amounts. It may be changed and rolled.

In the present invention, the roll bend pressure is used as an actuator which is a means for controlling the shape by changing the plate thickness distribution. However, the present invention is also applied to the case where a roll shift or a variable crown roll is used, or roll cross rolling. and that effective of course, further, the response is slow, such as rolling Akuchuta such as roll crossing rolling, for example, a Akuchuta to the intersection point between R _W while maintaining the relationship represented by R _E in Figure 1 If changed, it is possible to prevent the flatness defect in the transitional state of the width correction.

[0039]

EXAMPLES The effects of the present invention will be described below based on examples. (Example 1) Regarding the change in strip width when the rolling shape was changed, the results of the method of the present invention and the case where the horizontal bending of the work roll was not controlled (control example) were compared. The experiment is performed using the rolling mill of FIG. 7 under the same conditions as the above experiment, and rolling is performed so that the rolled shape has a predetermined value. In the case of the present example, the strip width variation amount becomes zero. Controlled to.

FIG. 9 is a graph showing the relationship between the steepness and the plate width fluctuation amount at this time. Here, the steepness is 10 mm from the plate edge.
Using the value converted from the difference in elongation between the position and the central part, the sheet width variation was taken as the deviation from the base metal width as a reference value. The steepness was positive for the ear wave shape and negative for the middle extension shape, and the width variation was positive for the width expansion and negative for the width contraction as compared with the reference value.

As can be seen from FIG. 9, when the method of the present invention (indicated by ● in the figure) is used, the elongation is middle and the width variation is ± 0.
The width accuracy is improved within the range of 2 mm or less, but in the comparative example with only the roll bender, the plate width also changes with the change in shape, and within the range of this test condition, the maximum is ± 0.8 mm. It is fluctuating.

Example 2 In this example, Example 1 was repeated in actual operation. Fig. 10 shows the frequency distribution chart of the strip width variation during actual operation on a 5-stand cold tandem rolling line. Figure 10
The result of this example is shown in (a), and the result of the comparative example is shown in FIG. 10 (b). The plate width variation amount is the difference from the target plate width in the width design table.

From this result, it was found that by using the method of the present invention, it is possible to minimize the variation of the plate width regardless of the size and the like, and to manufacture a product having good dimensional accuracy.

[0044]

According to the method of the present invention, the shape and strip width during rolling can be controlled at the same time, and it is possible to manufacture a metal sheet having excellent shape and strip width accuracy by eliminating the influence of the base material size and the like. It is possible and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the method of the present invention.

2 (a) to 2 (f) show the relationship between the plate pressure distribution in the width direction during rolling and the plate shape, and FIGS. 2 (a) to 2 (c) show the case where seismic waves are generated. 2 (d) to 2 (f) are explanatory views showing a case where medium elongation occurs.

FIG. 3 is a diagram showing a relationship between a plate pressure distribution in the width direction and a plate width fluctuation during rolling.

FIG. 4 shows the state of horizontal deflection of the work roll and the state of frictional force acting on the rolling plate. FIG. 4 (a) shows the work roll in a non-deflected state, and FIG. 4 (b) shows the work roll rolled. FIG. 4 (c) is a schematic explanatory view of a state in which the work roll is bent toward the direction entry side, and FIG.

FIG. 5 illustrates that the shape of the rolled plate changes due to horizontal deflection of the work rolls. FIGS. 5 (a) to 5 (c) show the case where an ear wave is generated, and FIGS. ) Is an explanatory view showing a case where medium elongation occurs.

FIG. 6 is a diagram showing the effects of the bending of the roll bender and the horizontal bending of the work roll respectively, and FIG. 6 (a) is calculated by converting from the difference in stretching between the position 10 mm from the end of the rolled plate and the center. Fig. 6 (b) shows the relationship between the steepness and the amount of change in width before and after rolling. Fig. 6 (b) shows the steepness obtained by converting from the difference in stretching between the position 10 mm from the edge of the rolled plate and the center. And the plate crown amount obtained by subtracting the plate thickness at the position of 10 mm from the end part from the plate thickness of the central part.

FIG. 7 (a) is a front view showing the structure of a rolling mill used in an example of the present invention, and FIG. 2 (b) is a side view.

FIG. 8 is a plan view showing a support roll for bending a work roll in a horizontal direction.

FIG. 9 is a graph showing the relationship between the steepness obtained by converting the drawing difference between the central portion and the position 10 mm from the edge of the rolled plate and the width variation before and after rolling.

FIG. 10 is a diagram showing a distribution of deviations from the sheet width fluctuation amount depending on the difference between the sheet width target value and the actual value. FIG. 10 (a) shows an example of the present invention, and FIG. 10 (b) shows a comparative example. It is a graph which shows each result.

[Explanation of symbols]

 40: Work roll 44: Ear wave 42: Rolled plate 46: Medium elongation

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B21B 37/22 8315-4E B21B 37/00 122 Z

Claims (3)

[Claims] 1. An upper and lower work roll which is horizontally flexible,
In the method of cold rolling a metal sheet by a rolling mill having at least one or more shape changing means capable of changing the rolling shape by changing the plate thickness distribution in the width direction of the rolled material during rolling, Rolling is performed by bending at least one of the upper and lower work rolls in the horizontal direction, and changing the set value of the shape changing means and the horizontal deflection amount of the work roll to obtain flatness and plate width of the material to be rolled. A method for cold rolling a metal sheet, which is characterized by controlling simultaneously. 2. The set value of the shape changing unit and the change amount of the horizontal deflection amount of the work roll are calculated in accordance with the correction amount of the plate width, and the set value and the horizontal deflection amount are added to the obtained two change amounts. The method for rolling a metal plate according to claim 1, wherein the rolling is performed after changing the rolling. 3. The set value of the shape changing means and the change amount of the horizontal deflection amount of the work roll are calculated in accordance with the correction amount of the shape, and the set value and the horizontal deflection amount are changed to the obtained two change amounts. The method for rolling a metal plate according to claim 1, wherein the rolling is performed by rolling.