JPH09271818A - Method for evaluating edge drop of metallic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating the edge drop, which is applicable to highly precise crown and shape control. SOLUTION: This method is for operating and evaluating an edge drop range in the vicinity of the edge of the plate width of a rolled stock after rolling in the rolling process of the metallic plate. A plate profile in the vicinity of the edge of the plate width of the rolled stock, is divided into body crown and edge drop range, the body crown is approximated by using the polynomial of a quartic equation or below. Next, an edge drop quantity is operated from a difference between a prolongation in the plate width direction of the approximate function of the polynomial and the plate profile after rolling, and an edge drop range is operated from a range (area) surrounded by the prolongation in the plate width direction and the plate profile after rolling and the edge drop quantity.

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 managing the plate thickness distribution in the plate width direction of a rolled metal plate in the 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 technique for controlling or managing edge drop.

[0002]

2. Description of the Related Art A plate profile of a 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. As described above, 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, the edge drop is reasonably defined and evaluated in consideration of its generation mechanism. There is a need.

As a conventional method for defining and evaluating the edge drop amount, regardless of hot rolling or cold rolling, for example, as shown in FIG. 9, the edge drop amount is measured between two points in the vicinity of the width end of the rolled material plate. That is, between the positions a and b in the plate width direction,
A method of evaluating as a difference in plate thickness or a difference in plate crown is known. 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. 9, the edge drop amount is
It is evaluated in Eqs. (1) and (2).

C _e = t (a) -t (b) (1) C _e = C (b) -C (a) (2) where C _e is the edge drop amount, t Is the plate thickness, and C is the plate crown.

As the plate width direction positions a and b for evaluating the edge drop amount by the above-mentioned conventional method, for example, the rolled material plate width direction positions shown in Table 1 are known.

[0006]

[Table 1]

As another method for evaluating the amount of edge drop, as disclosed in Japanese Patent Laid-Open No. 6-304623, the profile of the rolled material after rolling is measured in the plate width direction to obtain the rolled material plate width. An area of abrupt thickness reduction existing near the edge, that is, a rolled sheet profile excluding the edge drop area, that is, a body crown is approximated using a polynomial of fourth order or less, and then the edge drop amount C _e is rolled. There is a method of defining and evaluating as the difference between the extension line of the above approximate function in the plate width direction at the distance w _d from the material end and the plate profile after rolling.

Next, a conventional body crown and 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 provided by multiple rolling passes. That is, since the body crown of rolled material has a heritability between rolling passes, and in the rolling process of a metal sheet, rolling must be performed within the allowable range of the sheet shape that does not hinder the rolling work. Since the correction amount of the body crown per pass cannot be so large, it is performed in a plurality of rolling passes. 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.

Regarding the edge drop control, for example, as disclosed in JP-A-58-221601, the upper and lower work rolls have a single trapezoidal shape as shown in FIG.
In a rolling mill in which these work rolls are arranged point-symmetrically around the mill center and have a facility (work roll shift) that can move in the roll axial direction, at least one pass before the final rolling pass Rolling is performed so that the end portion falls on the roll taper portion of the single trapezoidal roll, and the plate thickness of the rolled material plate width end portion is made larger than usual (this is referred to as edge up _Eu in the following description), and then the final There is a method of rolling in a rolling mill having a work roll provided with a smooth roll crown in a rolling pass. Also,
In another example of edge drop control, 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 amount which is a main factor in the mechanism of the edge drop generation. That is, these conventional techniques of conventional edge drop control are performed before the final rolling pass or one pass before the rolling process because the edge drop has a low heritability between rolling passes.

[0011]

As described above, as a method for evaluating the amount of edge drop in the conventional method, as described above, for example, as shown in FIG. A method is known in which the edge drop amount C _e is evaluated as the difference in plate crown or plate thickness between b. However, since edge drop and body thickness change due to body crown coexist in this region, not only the edge drop is evaluated in the above conventional method, but the body crown near the edge of the strip width of the rolled material Since the change amount of the plate thickness including the above is evaluated, there is a problem as a method of evaluating the edge drop amount itself.

In the evaluation method disclosed in Japanese Patent Laid-Open No. 6-304623, first, the plate profile of the rolled material after rolling is measured, and then, as shown in FIG. The strip profile after rolling excluding the existing region of the rapid strip thickness reduction, that is, the region determined to be the edge drop is calculated as a body crown using a polynomial of 4th order or less, and then the edge drop amount C _e is rolled. There is a method of defining and evaluating as the difference between the extension line of the above approximate function in the plate width direction at the distance w _d from the material end and the plate profile after rolling. According to this evaluation method, it is possible to rationally separate and evaluate the body crown and the sharp sheet thickness reduction, that is, the edge drop due to the elastic recovery of the roll flatness near the end of the rolled material.

However, as a result of many observations of the rolled plate profile by the inventors, as shown in FIG. 6, for example, the edge drop amount calculated by the evaluation method disclosed in JP-A-6-304623. It was also found that there are rolled materials with different edge drop shapes even if the body crown amount is almost the same. That is, it has been found that if the phenomenon of edge drop is evaluated only by the amount of edge drop, the amount of edge drop cannot be evaluated from that amount.

The present invention solves the above-mentioned problems of the edge drop evaluation method according to the conventional method, and it is possible to evaluate the shape of the edge drop after rationally separating the edge drop and the body crown, and An object is to provide an edge drop evaluation method applicable to plate profile control or edge drop management.

[0015]

In order to achieve the above-mentioned object, the first gist of the present invention is to provide an edge drop which occurs in the vicinity of a width end of a rolled material plate after rolling in a rolling process of a metal plate. A method of calculating and evaluating the range, measuring the plate profile of the rolled material after rolling, and removing the plate profile excluding the region in which the plate thickness that is present in the vicinity of the edge in the plate width direction of this plate profile and sharply decreases Approximation is performed using a polynomial of degree 4 or less, and then the edge drop amount C _e is defined as the difference between the extension line of the above polynomial in the sheet width direction and the sheet profile after rolling at the position of the distance w _d from the end of the rolled material. Further, the area A surrounded by the extension line of the approximate function in the strip width direction and the strip profile after rolling is calculated from the center of the strip to the distance w _d from the edge of the strip, and then the edge is calculated. Drop range The _e, a _{w e = 3 × A / C} e + w metal plate edge drop evaluation method and calculating as _d.

A second aspect of the present invention is a method for calculating and evaluating a range of edge drops generated in the vicinity of a width edge of a rolled material plate after rolling in a rolling process of a metal plate, The plate profile of the rolled material after rolling is measured, and first, the plate profile excluding the region in the vicinity of the edge of the plate width in the plate width direction where the plate thickness suddenly decreases is calculated using a polynomial of 4th order or less. Then, the edge drop amount C _e is calculated as a difference between the extension line of the above polynomial in the strip width direction and the strip profile after rolling at the position of the distance w _d from the end of the strip, and further from the center of the strip. An area A surrounded by an extension line in the plate width direction of the approximate function and the plate profile after rolling is calculated up to a distance w _d from the rolled material end portion, and then an edge drop range w _e is represented by w _e = 3 × A / C + w _d Calculated as further to the plate profile, except for the range of edge drop range w _e previously calculated from the rolled material end, the edge drop range w _e by using the calculation process for calculating the edge drop range Of the metal plate characterized in that the edge drop range is calculated by repeating the calculation process of the edge drop range until the absolute value of the difference between the edge drop range and the previously calculated value becomes smaller than a preset value. This is an edge drop evaluation method.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
In order to find a method for rationally evaluating a rapid reduction in sheet thickness caused by elastic recovery of roll flatness during rolling in the vicinity of the width end of rolled material, that is, the shape of edge drop, the inventors By applying the edge drop amount evaluation method disclosed in Japanese Patent Application Laid-Open No. 6-304623, which was previously submitted by the inventors, to the sheet profile of the rolled material measured later, the sheet profile and the rolled material sheet exist in the vicinity of the width end portion. The relationship between the extended line of the approximate quartic curve of the body crown excluding the region where the plate thickness rapidly decreases, that is, the edge drop region, and the edge drop amount C _e was observed in detail.

As a result, as shown in FIG. 1 (a), the difference between the plate profile and the extension line of the approximate quartic curve of the body crown is roughly as shown in FIG. 1 (b). It has been found that the approximate fourth-order curve of the crown can be approximated by a parabola whose origin is the position where the approximate fourth-order curve starts to separate (hereinafter referred to as an edge drop start point). That is, if the inventors can determine the area A surrounded by the extension line of the approximate quartic curve of the plate profile and the body crown as shown in FIG. 1A, the property of the parabola is used for rolling. distance from wood end to edge drop start point (hereinafter, referred to as edge drop range w _e) and found that a can be obtained by the following expression.

[0019] _{w e = 3 × A / C} e + w d ··· (3) where, w _d means defined position or positions to evaluate the edge drop amount for calculating the edge drop amount, the rolling material Expressed as the distance from the edge. Further, the area A surrounded by the extension line of the approximate quartic curve of the plate profile and the body crown is, for example, from the center of the rolled material to the distance w _d from the end of the rolled material, the approximate function f at intervals of dx. (X) (x is the sheet width direction coordinate with the center of the rolled material as the origin) and the difference between the sheet profile after rolling are multiplied by dx, and the values are added together to obtain the following formula.

A = Σ {f (x) −C (x)} dx (4) Here, the plate profile is the result of measuring the crown distribution in the plate width direction of the rolled material after rolling. Plate crown distribution C (x) corresponding to the plate width direction coordinate x with the center of the material as the origin
Is represented by

Furthermore, the inventors of the present invention disclosed in Japanese Patent Application Laid-Open No. 6-30462.
The method of the present invention is applied to two rolled materials that have substantially the same edge drop amount and body crown amount calculated by the edge drop amount evaluation method disclosed in Japanese Patent Publication No. 3 and have different edge drop shapes. It was verified whether the range can be calculated with practical accuracy. 2 shows the approximate quartic curve of the body crown at that time showed the calculation result of the plate profile and edge drop range W _e. As a result, it was found that the edge drop range can be calculated with practical accuracy by applying the present invention.

Further, from the edge drop range and the edge drop amount obtained from the present invention, since the shape of the edge drop can be parabolic approximated within this range as described above, this parabola and the approximate quartic curve of the body crown are By overlapping, the plate profile itself including the edge drop can be evaluated and calculated.
Further, although the present invention has been described from the viewpoint of the plate crown distribution, it goes without saying that the edge drop range can be similarly evaluated by using the plate thickness distribution.

In order to obtain an effective means for edge drop control, the inventors have applied the present invention to a conventional edge drop control method and evaluated edge drop. Here, the conventional edge drop control method is
For example, the rolling method disclosed in JP-A-58-221601 was applied.

The inventors of the present invention have used a single trapezoidal roll as the upper and lower work rolls as shown in FIG. By arranging rolling mills that are arranged point-symmetrically around the center and equipped with equipment that can move in the roll axial direction, change the work roll shift amount one roll before the final stand to change rolling material with different edge up amounts. It was formed and then rolled in a rolling mill having work rolls with a smooth roll crown in the final rolling pass. The inventors applied the edge drop evaluation method of the present invention to the measurement results of the plate profile on the exit side of the final stand obtained by the rolling, and evaluated the edge drop range, the edge drop amount, and the body crown amount, and Analysis was carried out.

FIG. 3 shows the results of analysis of the relationship between the input side edge drop amount, the output side edge drop amount, and the edge drop range. Here, the entrance and exit edge drop amounts were evaluated at 5 mm from the end of the rolled material. From FIG. 3, it was found that the smaller the edge drop amount of the rolled material on the entrance side of the final stand, the smaller the edge drop range and the edge drop amount on the exit side. That is, when the edge drop observed from the result of the edge drop control of the conventional technique is applied to the present invention and evaluated,
It was found that the effect of edge drop control can be evaluated appropriately.

An example of the edge drop control using the present invention will be concretely described in the following section on the basis of the knowledge obtained from the above-mentioned observation results regarding the edge drop.

[0027]

【Example】

-Example 1- A specific example in which the edge drop control according to the present invention is applied and the edge drop control according to the conventional method is performed will be described below. At this time, for the edge drop control by the conventional method, for example, the rolling method disclosed in Japanese Patent Laid-Open No. 58-221601 was applied. In the present embodiment, the plate crown is used for the numerical expression of the plate profile.

The present invention has been applied to a finishing rolling mill train of an existing hot continuous rolling mill. FIG. 4 shows an embodiment when the edge drop evaluation method according to the present invention is applied and edge drop control is performed. In the finishing rolling mill train, one trapezoidal roll as shown in FIG. 8 is used as the upper and lower work rolls, and these are arranged point-symmetrically around the mill center and moved in the roll axial direction one stand before the final stand. It is equipped with a rolling mill having possible facilities. further,
As shown in FIG. 4 (a), a plate crown measuring device is installed on the rear surface of the finishing final stand, the plate crown distribution in the plate width direction of the rolled material is measured, and then the plate crown distribution in the plate width direction is measured. As shown in (a) of FIG.
At, the edge drop range, the edge drop amount, and the body crown amount were calculated and evaluated.

The calculation in the calculator 1 uses the coordinate x in the width direction with the center of the width of the rolled material plate as the origin, and for example, the plate crown excluding 80 mm from the end in the width direction of the rolled material (6)
It is approximated by a quartic equation as shown in the equation, and the rolled material edge is
The difference between the extension of the above approximation formula and the plate crown at a point,
In other words, the amount of edge drop is calculated by equation (7). Also, the body crown amount is calculated by the equation (8).

[0030] _{f (x 5) = a ·} x 4 + b · x 3 + c · x 2 + d · x ··· (6) C e = f (x 5) -C (x 5) ··· (7) B _c = f (x ₅ ) ... (8) where C _e is the edge drop amount, f (x) is an approximate function of the body crown, and C (x ₅ ) of the plate crown is the actual plate crown. x ₅ means the position of 5 mm from the end of the rolled material at the coordinate x in the width direction with the center of the width of the rolled material sheet as the origin. As for the edge drop range w _e, it was calculated by the following equation using the equation (3). At this time, w _{d in the} equation (3) is 5
mm: w _e = 3 × A / C _e +5 (9) Here, for example, A may be calculated using the equation (4).

Next, in the computing unit 2 shown in FIG. 4A, the edge drop range, the edge drop amount, and the body crown amount which are predetermined as the target on the exit side of the finishing final stand and the edge drop range evaluated by the computing unit 1 are evaluated. , The edge drop amount, and the body crown amount are compared, and it is determined whether or not these differences are within an allowable range.

When at least one of the edge drop range and the edge drop amount of the rolled material exceeds the allowable range, as shown in FIG. Was calculated to calculate the control amount for changing the work roll shift, and then the work roll shift amount was changed during the running based on the control amount to control the edge up amount of the rolled material. As a result, the rolled material could be controlled to the target plate profile on the exit side of the finishing stand. Also, if the work roll shift is not in time during the running or if the work roll shift cannot be performed during the running,
By learning the difference between the target edge drop range and the edge drop amount on the exit side of the final stand, it can be used for correcting the strip crown schedule in the next rolling chance.

When the body crown amount of the rolled material exceeds the allowable range set in advance as a target, 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. Or, 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.

Since the edge drop range, the edge drop amount, and the body crown amount can be appropriately evaluated by using the present invention, if the evaluation is applied to the edge drop control, the edge drop amount of the rolled material can be efficiently reduced. it can. Furthermore, according to the present invention, since the edge drop and the body crown can be reasonably separated and evaluated, the edge drop range evaluated on the exit side of the final stand,
As a means to correct the strip crown schedule in the next rolling chance, by individually learning the differences between the edge drop amount and the body crown, which are set in advance on the final stand exit side, respectively. Can also be used. Further, the present invention can be used not only for performing the above-mentioned edge drop control, but also as a management standard for the plate profile of the rolled material after rolling.

Example 2 Another example of the present invention will be described below. In FIG. 5, FIG.
The specific calculation process of the arithmetic unit 1 shown in FIG. In this example, first, as in Example 1, 80 mm from the end of the rolled material
The plate crown excluding the above is approximated by a quadratic equation as shown in Eq. (6), and then Eqs. (4) and (7) to (9) are used to calculate the edge drop amount, body crown amount, and edge drop amount. Calculate the range.

Next, the plate crown excluding the edge drop range calculated previously from the rolled material edge is approximated by a quartic equation as shown in equation (6), and then equations (4), (7)-( Calculate the edge drop amount, body crown amount, and edge drop range using equation (9).

Next, the calculation as shown in FIG. 5 is repeated until the absolute value of the difference between the edge drop range calculated last time and the edge drop range calculated this time becomes smaller than a preset value. , Edge drop amount and body crown amount are calculated. At this time, the preset value to be compared with the absolute value of the error between the edge drop range calculated last time and the edge drop range calculated this time is 1 mm, for example, in the present invention.

[0038]

As described above, according to the present invention, the edge drop and the body crown existing in the vicinity of the width end portion of the rolled metal sheet of the rolled metal sheet are rationally separated and the shape of the edge drop is changed. It can be evaluated and calculated, and control can be performed by distinguishing between edge drop and body crown with different control means, and the plate profile of the rolled material can be controlled with high accuracy. In addition, the present invention can be effectively used as a method for controlling the plate profile of a rolled material, since the plate profile of the rolled material, particularly the shape of the edge drop, can be known.

[Brief description of drawings]

1A and 1B are drawings corresponding to a transverse section of a rolled material for explaining an edge drop of the rolled material, where FIG. 1A shows a rolled material surface and its approximate curve, and FIG. 1B shows only an approximate curve.

FIG. 2 is a graph showing a rolled material surface position in a cross section of the rolled material.

FIG. 3 is a graph showing the results of evaluation of a conventional edge drop control technique according to the present invention.

4A is a block diagram showing an outline of an apparatus configuration for carrying out the present invention in one aspect, FIG. 4B is a graph showing data compared by the arithmetic unit 2 shown in FIG. 4A, and FIG. Is a graph showing data calculated by the arithmetic unit 1 shown in (a).

FIG. 5 is a flowchart showing an outline of processing according to the second embodiment of the present invention.

FIG. 6 is a graph showing a surface position of a rolled material in a cross section of the rolled material.

FIG. 7 is a graph showing an approximate curve calculated by a conventional edge drop evaluation method.

FIG. 8 is a front view showing a roll of a rolling mill used for edge drop amount control.

FIG. 9 is a graph showing a surface position of a rolled material in a cross section of the rolled material, showing a conventional edge drop amount evaluation position.

FIG. 10 is a graph showing a surface position of a rolled material in a cross section of the rolled material, showing an edge drop region.

Claims (2)

[Claims] 1. A method for calculating and evaluating the range of edge drops occurring near the widthwise end of a rolled material in a rolling process of a metal sheet, which comprises measuring a plate profile of the rolled material after rolling, The plate profile excluding the region where the plate thickness sharply decreases existing near the end of the plate profile in the plate width direction is approximated by using a polynomial of fourth order or less, and then the edge drop amount C _e is calculated from the end of the rolled material. calculated extension line of the plate width direction of the polynomial at the position of the distance w _d between the difference between the plate profile after rolling, Furthermore, the distance from the rolled material center from the rolled material ends w _d
Calculating the area A surrounded by the plate profile after rolling the extension line of the plate width direction of the approximation function in the up, then the edge drop range w _e, is calculated as _{w e = 3 × A / C} e + w d An edge drop evaluation method for a metal plate, which is characterized in that 2. A method for calculating and evaluating the range of edge drops occurring in the vicinity of the width edge portion of the rolled material after rolling in the rolling process of a metal sheet, which comprises first measuring the plate profile of the rolled material after rolling, and , The plate profile excluding the region in the vicinity of the end portion in the plate width direction where the plate thickness sharply decreases is approximated using a polynomial of fourth order or less, and then the edge drop amount C _e is calculated as It was calculated as the difference between the plate profile after rolling the extension line of the plate width direction of the polynomial at the position of the distance w _d from parts further distance from the rolled material center from the rolled material ends w _d
Calculating the area A surrounded by the plate profile after rolling the extension line of the plate width direction of the approximation function in up and then calculates the edge drop range w _e, as _{w e = 3 × A / C} e + w d and, further to the plate profile, except for the range of edge drop range w _e previously calculated from the rolled material end, calculates the edge drop range w _e by using the calculation process for calculating the edge drop range The edge drop range of the metal plate is calculated by repeating the calculation process of the edge drop range until the absolute value of the difference between the edge drop range and the previously calculated value becomes smaller than a preset value. Evaluation methods.