JPH06304623A - Method for evaluating edge drop of metallic plate - Google Patents

Abstract

PURPOSE:To provide a method for evaluating edge drop which can be applied to high-accuracy plate crown and shape control. CONSTITUTION:This is a method to calculate and evaluate a quantity of edge drop at the neighborhood of each width end of a rolled stock after it is rolled at the rolling stage of a metal plate. The plate profile at the neighborhood of each width end of the rolled stock is divided into areas of body crown and edge drop, the body crown is approximated by using a polynominal below a fourth degree expression, then, an quantity of edge drop is given by a difference between an extension line in the plate width direction of the approximate function and the plate profile at an arbitrary position in the width direction not exceeding 25mm from the plate end after it is rolled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling or evaluating the plate thickness distribution in the plate width direction of a rolled metal plate in a rolling process, and particularly to a rapid plate thickness reduction existing near the edge of the rolled material plate width, That is, the present invention relates to a method for controlling or evaluating edge drop.

[0002]

2. Description of the Related Art First, a conventional edge drop evaluation method will be described. The plate profile of the rolled material is roughly divided into a body crown region and an edge drop region as shown in FIG. For such a rolled material, in order to reduce the plate crown of the rolled material over the entire sheet width direction, it is possible to reduce not only the body crown but also the edge drop at the edge of the rolled material sheet width. Become essential.

In order to control or manage the edge drop existing in the vicinity of the width end portion of the rolled material plate in the rolling process of the metal plate, it is necessary to rationally define and evaluate the edge drop in consideration of the generation mechanism. There is. As a conventional method relating to this, regardless of hot rolling or cold rolling, for example, as shown in FIG. 16, the edge drop amount is set between two points in the vicinity of the width end of the rolled material, that is, between the positions a and b in the plate width direction. An evaluation method is known which is expressed as a difference in plate thickness or a difference in plate crown. In this case, for example, when the rolled plate profile or rolled crown is expressed as a function in the width direction of the rolled material as shown in FIG. 16, the edge drop amount is evaluated by the equations (1) and (2). Ed = t (a) -t (b) (1) Ed = C (b) -C (a) (2) where Ed is the edge drop amount, t (X) is the plate thickness, and C is
(X) is a plate crown, and X is a position in the plate width direction. As a specific example of the sheet width direction positions a and b for performing the edge drop evaluation by the above-mentioned conventional method, the rolled material sheet width direction position as shown in Table 1 is known.

[0004]

[Table 1]

Next, a conventional edge drop control technique will be described. The control of the plate profile according to the prior art is divided into body crown control and edge drop control.
Body crown control is performed using multiple rolling passes. This is because the body crown of rolled material has heritability between rolling passes, and rolling is performed within the allowable range of plate shape that does not hinder rolling work in the rolling process of metal sheets. This is because the correction amount of the body crown cannot be very large. Therefore, in order to significantly correct the body crown, it is necessary to actively control the body crown from the first half of the rolling pass.

The edge drop control is disclosed in, for example, FIG. 1 as disclosed in Japanese Patent Laid-Open No. 58-221601.
In a rolling mill having a single trapezoidal roll as shown in FIG. 5 as upper and lower work rolls WR, arranged symmetrically with respect to these mill centers, and having a facility capable of moving in the roll axial direction, at least one of the final rolling passes Before the pass, roll it so that the width edge of the rolled material plate hits the roll taper part,
A method in which the plate thickness at the width end of the rolled material is made larger than usual (this is referred to as edge-up Eu in the following description), and then rolling is performed in a rolling mill having a smooth roll crown in the final rolling pass, and edge drop. There is known a method of reducing the rolling load, that is, the reduction ratio in the final rolling pass, in order to reduce the roll flatness caused by the above. Further, the prior art of these edge drop controls is disclosed in Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 8-221601, since the edge drop has a low heritability between rolling passes, it is performed before the final rolling pass or one pass before the rolling process.

[0007]

According to the conventional edge drop evaluation method, for example, as shown in FIG. 16, the edge drop amount is set to the value of the crown of the plate crown between the positions a and b in the plate width direction in the vicinity of the end of the rolled material plate width. Although it is evaluated as a difference, since the edge drop and the thickness change due to the body crown are mixed in this area, not only the edge drop is evaluated, but the body crown near the edge of the strip width of the rolled material is also evaluated. This means that the included amount of change in plate thickness is being evaluated.

When this conventional method is used to evaluate the edge drop amount with respect to a rolled material having a large body crown as shown in FIG. 14, for example, the edge drop amount is more than the target edge drop amount on the exit side of the final rolling pass. If it is also large, it is necessary to reduce the edge drop.

As a conventional method of edge drop control, for example, single trapezoidal rolls as shown in FIG. 15 are used as upper and lower work rolls, and these are arranged in point symmetry around the mill center, and at least one pass before the final rolling pass. Then, there is a rolling method in which rolling is performed so that the width end portion of the rolled material sheet is in contact with the roll taper portion to make the edge up, and rolling is performed in a rolling mill having a smooth roll crown in the final rolling pass.
For example, as shown in FIG. 10, in order to secure the target edge drop amount on the exit side of the final rolling pass, the single trapezoidal roll is largely shifted one pass before the final rolling pass, and the vicinity of the width end of the rolled material plate is increased. It is necessary to carry out rolling so as to cover the roll taper portion, and as shown in FIG. 11, on the entry side of the final rolling pass, it is necessary to satisfy at least the target edge drop amount on the exit side of the final rolling pass. In this case, the edge of the rolled material sheet is increased to the thickness reduction due to the body crown in the vicinity of the end portion, and as shown by the dotted line (1) in FIG. 11, the plate profile on the entry side of the final rolling pass is the rolled material sheet width. The edge up will be unnatural near the edge. Then, even if rolled with a smooth roll crown in the final rolling pass, the plate profile on the delivery side of the final rolling pass has an unnatural shape near the width edge of the rolled material as shown by the dotted line (1) in FIG. Become.

As another edge drop control, for example, there is a method of reducing the rolling reduction in the final rolling pass. In this case, as shown in FIG. 14, since the rolled material having a large body crown is subjected to a light reduction, the difference in elongation between the central portion of the rolled material sheet width and the vicinity of the end portion in the rolling method becomes large, resulting in a medium stretched shape.

By the way, since the edge drop amount evaluated by the conventional method also includes the change amount of the body crown, it is treated as a body crown and is set as a target on the exit side of the final rolling pass as shown in FIG. When the rolling pass schedule is corrected so that the body crown amount is obtained and rolling is performed, the plate profile on the delivery side of the final pass has a sheet thickness at the end portion rather than at the center portion of the rolled material sheet width as shown by the dotted line in FIG. Larger, that is, a concave crown.

Further, in order to correct a rolled material having a plate profile as shown in FIG. 13 on the exit side of the final rolling pass to a target plate profile having a small body crown and a small edge drop as shown in FIG. Needs to control both body crown and edge drop.
However, as described above, the conventional edge drop evaluation method cannot quantify the correction amount used for the edge drop control and the body crown control. That is, as described above, in the conventional method, the body crown and the edge drop having different control means are confused in the vicinity of the end of the width of the rolled material plate for evaluation. At this time, for example, the body crown control slightly improves the edge drop, and therefore, when the edge drop is defined by the conventional method, there is a high risk that the edge drop is excessively controlled and the edge is raised.

The present invention solves the above-mentioned problems of the edge drop evaluation method according to the conventional method, and defines the edge drop and the body crown reasonably separately, and is applicable to the plate profile control. The purpose is to provide a method.

[0014]

In order to solve such a problem, the present invention is characterized in that a plate profile of a rolled material is separated into a body crown and an edge drop region, and an edge drop suitable for edge drop control is evaluated. And

That is, the amount of edge drop in the vicinity of the width edge of the rolled material sheet after rolling in the rolling process of the metal sheet is calculated.
By the method of evaluation, the rolled plate profile excluding 25 mm or more and 100 mm or less from the rolled material edge is approximated using a polynomial of 4th order or less, and then any plate width from the rolled material plate edge to the plate edge within 25 mm In the edge drop evaluation method for a metal plate, a difference between a value on an extension line of the polynomial in the plate width direction and an actually measured value of a plate profile after rolling is set as an edge drop amount at a directional position.

[0016]

The present invention will be described in detail below. The inventors
In order to rationally define and evaluate the sharp drop in thickness caused by elastic recovery of roll flatness near the width edge of rolled material, that is, edge drop, the body of rolled material after rolling in the rolling process of metal sheet The relationship between crown and work roll flexural deformation was analyzed. For example, as shown in FIG. 5, the rolling experiment and the work roll deflection deformation at that time were analyzed, and the sheet thickness distribution obtained in the rolling experiment and the work roll deflection amount were compared. However, the work roll deflection amount was expressed as a change amount in the plate thickness direction from the mill center to the roll cylinder length direction as shown in FIGS. 5 (a) and 5 (b).

As a result, for example, as shown in FIG. 5 (c), the rolled material sheet width center and the sheet width direction position a are in good agreement with each other. Then, it was found that the strip thickness distribution obtained in the rolling experiment became sharply smaller. This is shown in FIG.
As shown in (c), the plate crown from the central portion of the rolled material sheet width to the position a in the sheet width direction, that is, the body crown of the rolled material, reflects the work roll flexural deformation during rolling. It was found that there is a thickness reduction that cannot be explained from the work roll deflection deformation near the edges, that is, this is represented as an edge drop.

Therefore, the inventors have invented that the body crown of the rolled material is polynomial-approximated and the approximation function is used to evaluate the edge drop. This method is more advantageous in terms of calculation time than the evaluation by applying the work roll deformation analysis.

Further, the inventors have analyzed the relationship between the above-mentioned work roll deflection and the sheet thickness distribution of many metal sheets after rolling, and as a result, the region where the edge drop exists is the rolled material sheet. It was found that the plate edge was within about 100 mm from the edge, and the region where the difference from the work roll deflection became remarkable was within the plate edge of about 25 mm from the rolled sheet edge. That is, the region where the edge drop of the rolled material exists is much smaller than the body crown region, and even if the body crown of the rolled material is polynomial approximated and extended to the end of the rolled material plate width direction, it is shown in FIG. It was also found that there was almost no error with the work roll flexural deformation during rolling within the width of the rolled material plate.

As a function for approximating the body crown, it has been found from the approximation polynomial and the result of the roll deformation analysis that the work roll deflection can be approximated with practical accuracy by using a polynomial of fourth order or less. It was also found that even if a polynomial of 5th order or higher was used, there was almost no difference compared to the case of using a polynomial of 4th order or lower, and a workroll deflection can be sufficiently expressed by a polynomial of 4th order or lower.

In the present invention, for example, in a rolled material having a sheet thickness distribution as shown in FIG. 1, the rolled plate profile excluding 25 mm or more and 100 mm or less from the body crown region, that is, the edge of the rolled material is 4th or less. The approximation function f (x) of FIG. Then, the reduction amount of the plate thickness (plate crown) which cannot be explained from the extension line of the above polynomial to the end in the plate width direction at any position in the plate width direction from the end of the rolled material to the plate end within 25 mm where the edge drop appears remarkably Will be evaluated as an edge drop.

The edge drop amount according to the present invention is, for example, with respect to a rolled material having a sheet thickness distribution as shown in FIG. When x is set, there is a difference in the rolled material width direction position a between the extension of the function f (x) obtained by polynomial approximation of the rolled material body crown and the strip crown. In this case, the edge drop amount is given by equation (3) and the body crown amount is given by equation (4).
Can be expressed as Ed = f (a) -C (a) (3) Bc = f (a) (4) where Ed is the edge drop amount, Bc is the body crown amount, and f (x) is the plate thickness distribution in the body crown region. C (X) is the plate thickness at X. According to the present invention, as described above, it is possible to rationally separate and evaluate the edge drop and the body crown, which have different control means.

When the edge drop is evaluated according to the present invention, for example, an edge drop for making a rolled material having a plate profile as shown in FIG. 4 on the exit side of the final rolling pass into a target plate profile as shown in FIG. And the correction amount of the body crown can be easily obtained. That is, as shown in FIG. 4, the correction amount of the edge drop in the vicinity of the end portion of the width of the rolled material sheet is the edge drop amount 4d evaluated on the exit side of the final rolling pass and the target edge drop amount 4b on the exit side of the final rolling pass. As a difference, the correction amount of the body crown can be similarly expressed as a difference between 4c and 4a. Therefore, using these correction amounts, the body crown is corrected by correcting the plate crown schedule, and the edge drop is controlled by the final rolling pass or one pass before, and is set as the target on the exit side of the final rolling pass. It can be a plate profile.

In order to obtain an effective means for edge drop control, the inventors evaluated and analyzed many rolling experiments that have been conducted so far, using the edge drop evaluation method according to the present invention. For example, as shown in FIG. 7, the inventors conducted an experiment in which a crown shape control device was operated so that different body crowns on the entrance side of a four-high rolling mill have the same body crown on the exit side of the rolling mill. went.
As a result, as shown in FIG. 7, it was found that the form of edge drop on the delivery side of the rolling mill was such that the larger the plate crown on the entry side, the smaller the amount of edge drop. From the results of this analysis, as shown in FIG. 7, the inventors found that as the plate crown on the rolling mill entrance side is larger, the rolling direction tension near the width edge of the rolled material is smaller than that on the entry side plate crown. It was found that the rolling load becomes smaller toward the tension side, and the rolling load becomes smaller and the roll flatness becomes smaller in the vicinity of the width edge portion of the rolled material plate, that is, the edge drop caused by the roll flatness becomes smaller. This experiment was performed by changing the crown ratio ((outer side plate crown / outer side plate thickness)-(inner side plate crown /
From the viewpoint of the (inlet side plate thickness)), it was found that the edge drop becomes smaller by performing the rolling with the smaller value of the change in the crown ratio, that is, by performing the rolling on the side of the more middle stretched shape.

Further, the inventors conducted an experiment in which the body crown of the rolled material was the same on the entrance side of the four-high rolling mill, and rolling materials having different edge drop amounts were rolled at a reduction ratio of 3, 15 and 30%. I went. As a result, as shown in FIG. 8, the relationship between the edge drop amount on the rolling mill entrance side and the edge drop amount on the exit side for each rolling reduction was obtained. Reduction rate is 15,3
When it is 0%, it does not depend on the size of the edge drop amount on the rolling mill entrance side, and the edge drop amount on the exit side is almost constant. As shown in FIG. 7, when the rolling reduction is 3%. In the region where the amount of edge drop on the rolling mill is small, the amount of edge drop on the outlet side is also small and the amount is almost constant, but as the amount of edge drop on the inlet side increases, the amount of edge drop on the outlet side increases. It has been found that there is a region in which the value increases rapidly.

As a result of detailed analysis of the above experiment, the inventors have found that when the rolling reduction is 15, 30%, regardless of the edge drop amount existing at the end of the rolling material width direction on the rolling mill entrance side,
When the entire rolling material width direction is in full contact with the roll, and when the rolling reduction is 3%, the entire rolling material width direction is in overall contact with the roll in the region where the edge drop amount on the rolling mill entry side is small. However, in an area where the edge drop amount is large,
It was found that there is a non-rolling region that is not in contact with the roll at the widthwise end of the rolled material as shown in FIG. That is, if the roll is in full contact with the entire width direction of the rolled material, the rolling reduction is smaller and the edge drop amount on the delivery side of the rolling mill is smaller as shown in FIG. It has been found that if the end portion is not in contact with the roll, the edge drop existing at the end portion in the width direction of the rolled material on the entrance side of the rolling mill remains on the exit side and the edge drop becomes large.

As a rolling method for obtaining a sufficient edge drop reducing effect in the rolling process of a metal plate based on the knowledge of the above edge drop, first, the rolling process is carried out within the allowable range of the plate shape which does not hinder the rolling work. We focused on rolling the medium stretched shape depending on the material. The edge drop of the rolled material at this time becomes small, but it becomes a medium stretched shape,
The product is considered to be defective.

However, as described above, if the edge drop amount on the rolling mill entrance side is small, the entire roll widthwise contact with the rolls under light pressure, and the edge drop amount on the rolling mill exit side is also small. Even if a defect occurs, if the edge drop of the rolled material is small, it is clear that the shape can be corrected under the light pressure of the next pass, and the edge drop amount after rolling becomes small.

Therefore, as a means for reducing the edge drop in the rolling process of a metal sheet, the inventors first perform rolling on the medium stretched shape side by using a rolled material within the allowable range of the sheet shape that does not hinder the rolling work. Then, the inventors invented a rolling method for performing shape-correcting rolling by light reduction.

[0030]

EXAMPLE A specific example of edge drop control to which the edge drop evaluation method according to the present invention is applied will be described below. The present invention has been applied to an existing hot rolling mill finish rolling mill train. FIG. 2 shows an embodiment when the edge drop evaluation method according to the present invention is applied and edge drop control is performed. Here, the finishing final stand is to perform shape straightening rolling. As shown in FIG. 2 (a), the plate thickness distribution of the rolled material is measured by using a plate thickness crown measuring device installed on the rear surface of the finishing final stand, and then, as shown in FIG. Calculate and evaluate the amount of edge drop and the amount of body crown. Then, the calculator 2 compares the target edge drop amount and the body crown amount on the exit side of the final stand to determine whether the edge drop amount and the body crown amount evaluated by the calculator 1 are within the target allowable range. .

As an embodiment of the present invention in the computing unit 1 and the computing unit 2, for example, as shown in FIG. 3, the center of the rolled material strip width is the origin, and the coordinate in the width direction of the rolled material is x (x = at the center portion of the strip width).
0) is approximated from the central part of the rolled material to 80 mm of the rolled material end by a quaternary equation as shown in equation (5),
The difference between the extension of the above approximate expression at the mm point and the plate crown, that is, the expression (6), represents the edge drop amount. ^{f (x) = ax 4 +} bx 3 + cx 2 + dx (5) Ed = f (x 5) -C (x 5) (6) where, Ed edge drop amount, f (x) is the approximate function of the body crown , C is a plate crown, and x ₅ is a point 5 mm from the end of the rolled material. Here, f (x) in equation (5)
In the arithmetic unit 1, each constant term of a = 0.0813,
b = -0.5378, c = 0.8655, d = -0.0
Calculated as 008.

When the edge drop amount of the rolled material exceeds the target permissible range, as shown in FIG.
Calculation to change the setting value of the crown shape control device and the setting value of the final stand within the permissible range of the plate shape that does not hinder the rolling work, and to the side of the medium extension before the finishing last stand And perform rolling according to the above setting calculation during running. From this, it was possible to control the rolled material to the target plate profile on the exit side of the finishing stand.

If the body crown amount of the rolled material is above the target allowable range, the plate crown schedule is recalculated, and rolling is performed by changing the set value of the crown shape control device of each stand during running. Alternatively, by learning the difference from the target body crown on the exit side of the final stand, it can be used to correct the strip crown schedule in the next rolling opportunity.

If the edge drop amount is evaluated using the present invention and applied to the edge drop control at the finishing stand, the edge drop amount of the rolled material can be reduced without disturbing the edge up and the plate shape. .

[0035]

As described above, according to the present invention, the edge drop existing in the vicinity of the width end of the rolled metal sheet can be reasonably evaluated by separating it from the body crown. By controlling the edge drop and the body crown with different control means, the plate profile of the rolled material can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the present invention.

FIG. 4 is a diagram for explaining an advantage of the present invention.

FIG. 5 is a diagram showing a process leading to completion of the present invention.

FIG. 6 is a diagram showing a process leading to completion of the present invention.

FIG. 7 is a diagram showing a process leading to the invention of an edge drop control technique.

FIG. 8 is a diagram showing a process of inventing an edge drop control technique.

FIG. 9 is a diagram showing a process of inventing an edge drop control technique.

FIG. 10 is a diagram used to explain problems of the conventional method.

FIG. 11 is a diagram used to explain problems of the conventional method.

FIG. 12 is a diagram used for explaining problems of the conventional method.

FIG. 13 is a diagram used to explain problems of the conventional method.

FIG. 14 is a diagram showing a form of a plate profile.

FIG. 15 is a diagram showing a conventional technique of edge drop.

FIG. 16 is a diagram showing an embodiment of a conventional method.

FIG. 17 is a diagram showing a body crown and edge drop regions in a plate profile.

Claims (1)

[Claims] 1. A method for calculating and evaluating an edge drop amount in the vicinity of a width end portion of a rolled material sheet after rolling in a rolling process of a metal sheet, which is a sheet after rolling excluding 25 mm to 100 mm from the edge portion of the rolled material. The profile is approximated using a polynomial of 4th order or less, and then the value at the extension line of the polynomial in the plate width direction and the plate profile after rolling at any position in the plate width direction from the plate edge to the plate edge within 25 mm. An edge drop evaluation method for a metal plate, which is characterized in that the difference between the measured value and the measured value is used as the edge drop amount.