JP2009028772A - Method of calculating amount of camber of steel sheet during rolling and method of manufacturing steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of calculating the amount of camber of a steel sheet during rolling and a method of manufacturing the steel sheet by which the camber shape of the steel sheet when rolling the steel sheet is measured accurately and at low cost and the generation of the camber is suppressed without hindering rolling work. <P>SOLUTION: This method is a method of calculating the amount of camber of the steel sheet (6) during rolling the steel sheet (6) with a rolling mill (5) provided with work rolls (1, 2) and the method of calculating the amount of camber of the steel sheet during rolling is provided with: a rolling stage where the steel sheet (6) the position of which is controlled so that the middle in the width direction of the work rolls (1, 2) and the middle in the width direction of the steel sheet (6) are made to coincide on the inlet side of the rolling mill (5) is rolled; a measuring stage where the off-center quantity of the rolled steel sheet (6) is measured in a position at a prescribed distance from the rolling mill (5) on the outlet side of the rolling mill (5) after the rolling stage; and an amount of camber deriving stage where the amount of camber of the rolled steel sheet (6) is derived by using the off-center quantity measured in the measuring stage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method for calculating a camber amount of a steel plate during rolling, capable of measuring the steel plate camber shape when rolling the steel plate accurately and at low cost without interfering with the rolling operation, and suppressing the occurrence of camber. The present invention also relates to a method for manufacturing a steel sheet, comprising a step of measuring a camber amount by the camber amount calculation method.

  In the rolling process of the thick plate factory, rolling is performed using two hot rolling mills, a rough rolling mill and a finish rolling mill. The amount of sheet thickness that can be reduced by one rolling (hereinafter referred to as “pass”) is limited by the load-bearing capacity of the rolling mill and the motor power. Rolled in multiple passes while reciprocating the steel plate. In the rough mill, in order to obtain a required sheet width, width rolling by a horizontal roll and vertical rolling by an edge roll (edger) for adjusting a planar shape are performed. In the finishing mill, finishing rolling is performed using only horizontal rolls that determine the thickness and length of the steel sheet.

  During rolling in the longitudinal direction of this finishing mill, the roll gap initial setting in the rolling mill, the rolling position error resulting from the difference in rigidity between the left and right sides of the mill housing, present at both ends in the width direction of the material to be rolled into the rolling mill Due to various asymmetries such as deviation of deformation resistance based on the difference in sheet thickness (wedge) and temperature difference generated at both ends in the width direction of the material to be rolled. There may be a non-uniform speed difference at both ends. The speed distribution in the width direction on the exit side of the rolling mill causes uneven elongation at both ends in the width direction of the steel strip, and the steel strip running on the exit side of the rolling mill is centered on the rolling mill in a horizontal plane as a whole. As a result, a shape curved in a substantially arc shape (hereinafter referred to as “camber shape”) is generated. FIG. 14 shows an example of the shape of a steel plate having a camber shape (hereinafter sometimes referred to as “rolled material”). The moving direction of the rolled material shown in FIG. 14 is a direction from the left side to the right side of the paper surface, and a camber shape is generated by curving upward on the paper surface on the exit side of the rolling mill.

  FIG. 15 shows the definition of camber shape and camber amount indicating the degree of camber generation. The camber amount is defined as the maximum separation dimension between a line connecting the center in the width direction over the entire length of the curved rolled material (a camber-shaped line) and a line connecting the center in the width direction at both ends of the rolled material. . Usually, at the stage of slab design, based on the analysis results of the actual camber amount depending on rolling conditions such as rolling dimensions, the amount of camber after rolling, i.e., the shortage of width that occurs at the time of product cutting, is predicted, and the shortage of width is calculated. The corresponding weight is given to the slab weight. In particular, in rolling conditions in which the amount of camber tends to be large or a long product that is easily affected by the occurrence of camber, it is necessary to apply a larger slab weight, resulting in a significant decrease in product yield. Moreover, even if the slab weight is increased in advance, if the camber is generated larger than originally predicted, the predetermined product dimensions cannot be cut off from the rolled material.

  Thus, since the occurrence of camber is not desirable from the viewpoint of product yield, the rolling operator visually confirms the occurrence of camber during rolling or between rolling passes, so that the amount of camber is reduced empirically. In addition, the difference between the pressure setting positions of the drive side and the work side, that is, the leveling amount is changed. However, this method has many factors that depend on the skill of the rolling operator, such as the accuracy of the camber amount by visual inspection, the speed of determination, and the leveling correction amount empirically determined based on the visual measurement. It is the present situation that the occurrence of this has not been suppressed.

  Therefore, in order to stably suppress the occurrence of camber, the camber shape and camber amount are measured during rolling or between rolling passes by a measuring device installed in the vicinity of the rolling mill, and the rolling mill is based on the result. Realization of automatic camber control that automatically controls leveling of the image is desired.

  In order to realize this automatic camber control, a measuring device for measuring the camber shape and camber amount of a steel sheet rolled at a high temperature between passes and during rolling is necessary.

  Normally, in a line that is transported without rotation or meandering of the steel plate, a camber is installed on the line through which the steel plate passes by installing a width meter that can measure the off-center amount, which is the amount of deviation from the center line. The shape and camber amount can be measured (see FIG. 16). The camber shape and the camber amount can be obtained by measuring the steel plate length direction position obtained from the off-center amount and the conveyance speed. However, in general, during rolling, when the steel sheet travels on the transport roller, it is accompanied by rotation and meandering. Even if the off-center in the length direction of the steel sheet is measured with one width meter, the rotational movement of the steel sheet is also Since it is measured simultaneously, the camber shape of a steel plate cannot be measured. In the measurement between rolling passes, a method of measuring the off-center amount after exiting the rolling mill is also conceivable, but considering the length of the material to be rolled, a distance corresponding to the length of the steel sheet is conveyed after the end of rolling. It is necessary and very time consuming, which is not preferable from the viewpoint of rolling efficiency. In consideration of leveling correction during the rolling of the steel sheet, leveling correction in the subsequent pass, etc., it is necessary to measure the camber shape and camber amount while rolling.

  As a method of realizing high-accuracy measurement of the camber shape and camber amount of the steel plate during rolling, a method of photographing the whole steel plate with a camera at once, and measuring the off-center amount of the steel plate during rolling at multiple locations A method has been proposed. Patent Document 1 proposes a technique for simultaneously photographing an entire traveling steel sheet using a special optical system lens (anamorphic lens) attached to a camera provided at one point in the traveling direction of the steel strip. Normally, steel strips are extremely long compared to their widths, so if you try to keep the entire steel strip in the field of view with a normal shooting method, the position resolution in the width direction, which is important for measuring the camber shape, is important. descend. For this reason, the technique disclosed in Patent Document 1 uses a special optical system lens having different focal lengths in the width direction and the longitudinal direction of the steel strip to improve the position resolution in the width direction of the steel strip. ing.

  On the other hand, Patent Document 2 and Patent Document 3 propose a technique for measuring the off-center of a steel plate during rolling at three locations. In these methods, three width gauges capable of measuring off-center in the rolling direction of the steel sheet were installed, and at the same time, each time the steel strip traveled a certain distance, the off-center measurement was repeated and obtained. The camber shape is obtained by calculating an approximate curve that maintains the relative positional relationship of all three points (see FIG. 17). According to these methods, since the camber shape is based on the relative positional relationship of the three points, an accurate camber shape can be measured as long as the simultaneity of the measured values at the three points is maintained without photographing the entire steel plate.

Japanese Patent Laid-Open No. 5-118840 JP 59-65710 A JP-A-2-36307

  In order to implement the technique disclosed in Patent Document 1, it is necessary to secure a sufficient field of view of the camera in order to photograph the entire steel plate. However, since there are existing equipment such as side guides and radiation thickness meters in the immediate vicinity of rolling mills, it is practically difficult to measure and measure the camber shape of the entire length of the steel strip with an optical sensor such as a CCD camera. There was a problem that there was.

  On the other hand, according to the methods disclosed in Patent Document 2 and Patent Document 3, it is possible to solve the problem of securing the visual field over the entire steel sheet. However, since these methods use three off-center measuring instruments, there are the following problems.

(Installation space and installation cost problems)
In these methods, it is necessary to install three width meters or steel plate edge measuring instruments at intervals of several meters. Therefore, there are problems such as securing the installation location of the measuring instrument in the rolling line and the cost required for installing as many as three measuring instruments, which are difficult to implement in practice. In these methods, the relative positional relationship between the three width gauges must always be maintained, but the immediate vicinity of the rolling mill is high temperature, and a large amount of water vapor is scattered and intense. Due to the environment in which vibration is applied, the installation base is likely to be distorted. Therefore, it is difficult to stably maintain the relative positional relationship without applying a strong gantry that requires equipment costs.

(Influence on rolling efficiency)
Optical measuring instruments are generally used for off-center measurement of steel sheets by these methods, but since the rolling mill is filled with a large amount of scattered water droplets and mist water droplets generated from a large amount of cooling water, etc. The position where the off-center amount can be actually measured is a position separated by about 10 m or more from the rolling mill. For this reason, after the end of rolling, if the rearmost end in the longitudinal direction of the steel sheet (hereinafter referred to as “the rearmost end”) does not pass under this off-center measuring instrument that is 10 m or more away, The camber shape over the entire length in the longitudinal direction cannot be measured. However, it is not preferable to move the steel plate tail end, which normally goes only a few meters from the mill, to 10 m or more between rolling passes, which leads to an extra rolling time and lowers productivity. If it is a long plate that is 30 m or more between passes, the camber shape can be measured over almost the entire length, so it is considered that the influence on the control is small, but it is long that there are 30 m or more between passes. The quantity of steel plates is limited. In order to actually operate, it is necessary to measure at least the camber shape of a steel plate having a total length of about 15 m. However, it is difficult to measure the camber shape of a steel plate having a total length of about 15 m by these methods.

(Measurement accuracy problem)
A thick steel plate has a width as wide as about 4000 mm at the maximum, and in order to measure off-center with a camera, a high-resolution line sensor is generally applied. However, when the line sensor is used for off-center measurement, only the steel plate edge for one scanning line at a predetermined position in the rolling direction is optically measured. Therefore, in the vicinity of a rolling mill filled with mist-like water droplets or fumes, If the scanning line portion is blocked by mist-like water droplets or fumes, an abnormal measurement result is obtained, and there is a problem that the required measurement accuracy (for example, about 10 mm) of the full length camber amount cannot be achieved.

  Thus, in the techniques disclosed in Patent Documents 1 to 3, the camber shape of the steel plate during rolling cannot be measured accurately and at low cost without interfering with the rolling operation, and applied to camber control. Was limited.

  Therefore, the present invention can measure the shape of the steel plate camber when rolling the steel plate accurately and at low cost without interfering with the rolling operation, and can suppress the occurrence of camber. It is an object to provide a calculation method and a method for manufacturing a steel sheet.

  The present invention has been made using knowledge obtained from the investigation results of camber generation behavior when rolling a steel sheet while centering it with a side guide on the rolling mill entrance side.

  The camber generation behavior when rolling a steel sheet while centering it with a side guide will be described with reference to FIG. FIG. 18A is a diagram showing the state before rolling starts, and shows a state where camber is generated at the tail end portion (hereinafter referred to as “plate tail end portion”) of the steel plate. FIG. 18 (b) is a diagram showing the behavior of the steel sheet immediately after the start of rolling. A difference in elongation occurs in the width direction of the steel sheet, and the front end of the steel sheet rotates with the center in the width direction directly below the rolling mill as the rotation axis. It is shown that camber has started to occur at the front end of the steel plate (hereinafter referred to as “plate front end”). FIG.18 (c) is the figure which showed the camber generation | occurrence | production behavior during rolling after time passed from the state of FIG.18 (b). On the rolling mill entry side, the steel plate is restrained by the side guides and inserted straight into the center of the rolling mill. On the exit side of the rolling mill, the part that has already been rolled with the progress of rolling, that is, the part that has passed through the rolling mill becomes longer, the area and the plate weight on the exit side of the rolling mill increase, and the friction force with the transport roll increases. An increase occurs. Since this frictional force becomes a resistance force against the steel plate rotation on the delivery side of the rolling mill, which is the occurrence of camber itself, the difference in elongation at both ends in the width direction of the steel plate during rolling is reduced. As a result, the bending generated by rolling is concentrated at the tip of the plate (for example, about 20 m at the tip). Although the shape after rolling is shown in FIG. 18 (d), since the camber amount is forced by the restraint of the side guide at the plate tail end portion, the result is a shape in which only the plate tip portion is bent. Some bending also occurs at the plate tail end, but it is limited to the plate tail end where the restraining force of the side guide weakens, so it is smaller than the bend generated at the plate tip, and the effect on the camber amount of the entire plate is small.

  In the present invention, the camber generated in the previous pass is not inherited, which is a characteristic phenomenon when rolling while centering the steel plate with the side guide on the entrance side of the rolling mill, and the bending occurs only at the front end of the plate and the tail of the plate By utilizing the above phenomenon in which the section is almost straight, a camber amount calculation method and a camber control method for a steel sheet being rolled that can be applied to control with a simple apparatus configuration are provided.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiments.

  1st this invention is a method of calculating the camber amount of a steel plate (6) during rolling of the steel plate (6) by a rolling mill (5) provided with a work roll (1, 2), and comprises a rolling mill (5 ) Rolling the steel plate (6) whose position is controlled so that the center in the width direction of the work rolls (1, 2) and the center in the width direction of the steel plate (6) coincide with each other, After the rolling step, it is measured in a measuring step for measuring the off-center amount of the rolled steel sheet (6) at a position away from the rolling mill (5) on the exit side of the rolling mill (5), and the measuring step. And a camber amount deriving step for deriving the camber amount of the rolled steel sheet (6) using the off-center amount. To do.

  Here, the “off-center amount” means a straight line (center line) passing through the center in the width direction of the work rolls (1, 2) and parallel to the conveying direction of the steel plate (6), and the center in the width direction of the steel plate (6). Distance from the center line. Furthermore, the “position away from the rolling mill (5) by a predetermined distance” is not particularly limited as long as it is a distance that can ensure the measurement accuracy of the off-center amount (for example, about 10 mm). It is preferable that the position is about 10 m or more away from the rolling mill (5).

  In the first aspect of the present invention, it is preferable that only the off-center amount at the front end in the longitudinal direction of the steel plate (6) that has passed through the rolling mill (5) is measured in the measurement step.

  In the first aspect of the present invention, a correlation investigation process for investigating the correlation between the off-center amount at the longitudinal tip of the steel sheet (6) and the camber amount of the rolled steel sheet (6) is a pre-process of the rolling process. It is preferable that the camber amount is derived in the camber amount deriving step using the correlation investigated in the correlation investigation step and the off-center amount measured in the measurement step.

In the first aspect of the present invention, the off-center amount measured in the measuring step is D, the longitudinal length of the steel plate (6) is L, the longitudinal tip of the steel plate (6) being rolled and the work roll (1, 2) When the distance to the part of the steel plate (6) in contact with X is X and the camber amount is C, the camber amount is derived using the following (Equation 1) in the camber amount deriving step. Is preferred.
C = 3D / 4−DX / (2L) (Formula 1)

  Here, the “longitudinal length of the steel plate (6)” refers to the foot of the perpendicular line extending from the center in the width direction of the steel plate (6) at the longitudinal tip of the steel plate (6) to the center line, S1, steel plate (6 ) Is the length between the two points S1 and S2, where S2 is the foot of a perpendicular line that extends from the center in the width direction of the steel plate (6) to the center line.

  2nd this invention specifies the camber amount using the calculation method of the camber amount of the steel plate in rolling concerning 1st this invention, the camber amount specific process, and the camber amount specified by this camber amount specific process And the leveling control step of controlling the leveling of the rolling mill (5) after the next pass.

  Here, “leveling” means a reduction tightening amount on the workpiece side and a reduction tightening amount on the drive side of the rolling mill (5) in which the parallelism of the work rolls (1, 2) is adjusted directly or indirectly. Means the difference. The same applies to the following inventions.

  3rd this invention specifies the camber amount using the calculation method of the camber amount of the steel plate in rolling concerning 1st this invention, the camber amount specific process, and the camber amount specified by this camber amount specific process And a leveling control step for controlling the leveling of the rolling mill (5) during rolling.

  In the first aspect of the present invention, on the entry side of the rolling mill (5), the steel plate (6) is centered on the center line using a side guide (7, 7,...) Or the like, so that it is directly below the rolling mill (5). Note that the off-center amount is almost zero. In the first aspect of the present invention, the off-center amount is 0 immediately below the rolling mill (5), and the steel plate (6) enters the rolling mill (5) straight on the entry side of the rolling mill (5). If the foremost portion in the longitudinal direction of the steel plate during rolling reaches the off-center measurement position, the average camber curvature between the position immediately below the rolling mill (5) and the off-center measurement position can be measured. That is, according to 1st this invention, it becomes possible to estimate a camber shape by measuring the off-center amount until the tail end of a steel plate (6) passes a rolling mill (5).

In the first aspect of the present invention, on the entry side of the rolling mill (5), if rolling is performed with the steel plate (6) centered on the center line using a side guide (7, 7,...) Or the like, Only bending occurs, and this determines the camber shape of the entire length of the steel sheet. For this reason, the representative value of the camber shape over the full length in the longitudinal direction of the steel plate (6) can be obtained only by measuring the off-center amount of the plate tip, that is, the camber curvature of the plate tip. This means that there is no need to wait for the camber measurement result to be output until the rearmost end of the steel plate (6) passes through the off-center amount measurement position, and the rearmost end of the steel plate (6) As soon as it passes through the rolling mill (5), the rolling operation of the next pass can be performed, which is effective for improving the rolling efficiency. Moreover, since it is only necessary for the front end of the plate to pass through the off-center amount measurement position, the camber amount can be derived even with a steel plate (6) having a short rolling length. However, since it is necessary to be rolling, the length of the steel plate (6) needs to be longer than the distance between the measurement positions of the off-center amount from the rolling mill (5).
If the measurement position of the off-center amount is too close, the influence of the tail end shape in the previous pass and the influence of side guide centering error are likely to occur, and the off-center amount due to bending is small (the same curvature). Since the off-center amount is proportional to the square of the distance from the rolling mill (5) (see FIG. 6), the measurement accuracy is not sufficient. It is preferable to measure at a place separated by about 10 m or more.

  In the first aspect of the present invention, if the correlation between the off-center amount at the front end of the plate and the camber amount of the steel sheet after rolling is examined in advance, the leading edge of the plate passes through the measurement position of the off-center amount, and the measured value is obtained. Once obtained, the amount of camber after rolling can be obtained by calculation.

  Further, in the first aspect of the present invention, considering that the camber is generated only at a fixed length of the plate tip, the maximum camber amount is estimated geometrically and with high accuracy by using the above formula 1. can do.

  According to the second aspect of the present invention, since the camber amount is specified using the first aspect of the present invention, when the front end of the plate passes through the measurement position of the off-center amount, the total camber amount of the steel plate (6) can be estimated. . Therefore, leveling correction control to the next pass can be performed even with a short steel plate (6) in which the plate tail end does not enter the camera view. For this reason, according to 2nd this invention, the manufacturing method of the steel plate which can manufacture the steel plate in which the camber amount was reduced efficiently can be provided.

  According to the third aspect of the present invention, since the camber amount is specified using the first aspect of the present invention, when the front end of the plate passes the measurement position of the off-center amount, the camber amount of the full length of the steel plate (6) can be estimated. . Therefore, application to leveling feedback control during rolling (in the plate) is possible as long as the plate tip passes through the measurement position of the off-center amount. For this reason, according to 3rd this invention, the manufacturing method of a steel plate which can manufacture the steel plate in which the camber amount was reduced efficiently can be provided.

1. FIG. 1 is a flowchart showing an embodiment of a method for calculating a camber amount of a steel plate during rolling according to the present invention (hereinafter also referred to as “calculation method of the present invention”). As shown in FIG. 1, the calculation method of the camber amount of the steel plate under rolling of the present invention includes a rolling step (S11) of rolling the steel plate with a rolling mill, and a measurement for measuring the off-center amount of the steel plate rolled by the rolling mill. A step (S12), and a camber amount deriving step (S13) for deriving the camber amount using the measured off-center amount.

  In order to show the effectiveness of the present invention, a CCD camera was installed on the downstream side of an actual rolling mill, and a correlation between the camber shape and the camber amount measured after cooling the plate after rolling was investigated. Hereinafter, the present invention will be described with reference to the correlation survey.

(Overall system configuration and measurement flow)
FIG. 2 shows an apparatus configuration used for the evaluation test. The straight arrows in FIG. 2 indicate the conveyance direction of the steel plate, and the side guides are indicated by dotted lines in order to make the steel plate easier to see. The illustrated apparatus 10 includes a finish rolling mill 5 provided with work rolls 1, 2, backup rolls 3, 4, and a leveling apparatus 11, a side guide 7 for centering the steel plate 6 to the center line, and a steel plate off-center. Measuring means (CCD camera) 8, 8, 8 for measuring the amount, and camber amount deriving means (personal computer) 9 (hereinafter referred to as “PC 9”) for deriving the camber amount using the measured off-center amount. . As the measuring means, a progressive scan method, the number of pixels: 800 × 600, frame rate: 50 fps, resolution: about 8 mm / pixel CCD cameras 8, 8, 8 were used. Images taken by the CCD cameras 8, 8, and 8 are captured by the PC 9 and the edge position of the steel plate 6 is detected in real time. The PC9 equipped with Pentium 4-2.4 GHz used for this evaluation was capable of 15 measurements per second ("Pentium" is a registered trademark of Intel Corporation in the United States). This is sufficient measurement performance for actual control applications.

  In FIG. 3, the example of an image of the steel plate during rolling is shown. 3A is an image measured at a position 10 m away from the rolling mill 5, FIG. 3B is an image measured at a position 16 m away from the rolling mill 5, and FIG. 3C is 22 m away from the rolling mill 5. Images measured at different positions are shown. Since the temperature of the steel plate 6 during the rolling is as high as about 700 ° C. to 1000 ° C., the steel plate 6 itself emits heat radiation. Therefore, the steel plate 6 can be observed white on the images of the CCD cameras 8, 8, 8. In order to prevent the brightness from being saturated when the temperature of the steel plate 6 is high, the brightness on the actually obtained image is discriminated and a function for adjusting the camera sensitivity is provided. Image processing was performed on images obtained from each of the three CCD cameras 8, 8, and 8, and the off-center amount was measured.

(Edge detection image processing logic)
FIG. 4 shows the edge detection logic. For the detection of the edge contour line of the steel plate 6 when measuring the off-center amount of the steel plate 6 during rolling, 40 scanning lines per detection were used. In this method, first, the edge position for each scanning line is obtained from the differential intensity. The actual steel plate edge contour is estimated by the least square method obtained by multiplying the obtained plurality of edge positions by the differential strength as the weight. The steel plate edge contour thus obtained is determined so as to fit the edge position of the clear scanning line of the edge having the high differential strength, rather than the unclear scanning line of the edge having the low differential strength. For this reason, even if there is a part that is unclear due to fume or water droplets in the target scan line, it is possible to detect the actual steel sheet edge contour line without being relatively affected, and It is accuracy. Further, it is possible to determine the validity of the measurement result by providing a threshold value for the sum of the differential intensities obtained for each scanning line. FIG. 5 shows an actual measurement example. The noise of the off-center measurement value is about 10 mm, and when the camber is generated, it is observed that the off-center amount changes with the progress of rolling as shown in FIG. It can be confirmed that the off-center amount of can be accurately measured.

(Indicators used for correlation survey)
In order to verify the accuracy of the measured off-center amount, after the steel plate 6 was cooled, the camber amount of the steel plate rolled cold was measured and compared. Hereinafter, PSG (= Plane Shape Gauge) is displayed as a subscript for values measured in the cold. In addition, in order to compare the camber amounts of steel plates of different lengths, assuming that the shape of the entire length of the steel plate where the camber shape occurred is a complete arc shape, camber quantity _{C 30} per 30m from the amount measurements _{C PSG,} in terms of _{PSG.
C30, PSG} = _CPSG × (30000 / L) ² (Formula 2)
In (Formula 2), L is the rolling length [mm].

(Formula 2) uses that the camber amount is proportional to the square of the length when the curvature is the same. Hereinafter, it will be described with reference to FIGS. 6 and 7 that the camber amount is proportional to the square of the length when the curvature is the same.
The radius of curvature of the steel sheet deformed into an arc shape shown in FIG. 6 is R, the off-center amounts at two points A and B on the rolled steel sheet are D ₁ and D ₂ , the contact point between the arc AB and the center line is P, the arc The center of the circle forming AB is O, the foot of the perpendicular drawn from A to the center line is A ′, the foot of the perpendicular drawn from B to the center line is B ′, the midpoint of the straight line AP is M ₁ , the straight line The middle point of BP is M ₂ , ∠AOP = 2θ ₁ , ∠BOP = 2θ ₂ , string PA = L ₁ , and string PB = L ₂ .
Here, from ∠M ₁ OP = ∠A′PA = θ ₁ and ∠OM ₁ P = ∠PA′A = 90 °, the triangle M ₁ OP and the triangle A′PA are similar. Therefore, from OP: PM ₁ = PA: AA ′,
R: Rsinθ ₁ = PA: D ₁ (Formula 3)
It becomes. Here, since OP = OA and OM ₁ is a bisector of ∠POA, PM ₁ = M ₁ A = R sin θ ₁ . From PA = PM ₁ + M ₁ A, since PA = Rsinθ ₁ + Rsinθ ₁ = 2Rsinθ ₁ , substituting this into (Equation 3),
R: Rsinθ ₁ = 2Rsinθ ₁ : From D ₁ , D ₁ R = 2R ² sin ² θ ₁
D ₁ = 2Rsin ² θ ₁
Further, since the triangle M ₂ OP and the triangle B′PB are similar, when calculated in the same manner, D ₂ = 2Rsin ² θ ₂
From the above,
D ₂ / D ₁ = (sin ² θ ₂ / sin ² θ ₁ ) (Formula 4)
It becomes. And
From L ₁ = 2Rsinθ ₁ and L ₂ = 2Rsinθ ₂ ,
^{_{(L 2 / L 1) 2}} = (sin 2 θ 2 / sin 2 θ 1) ( Equation 5)
It becomes. Therefore, from (Expression 4) and (Expression 5),
D ₂ / D ₁ = (L ₂ / L ₁ ) ² (Formula 6)
It becomes. Therefore, the off-center amount is proportional to the square of the distance.

  On the other hand, the contact point between the arc shown in FIG. 7 and the tangent line of the arc is E, the point on the arc that is a distance D away from the tangent line is F, the center of the circle forming the arc EF is G, and ∠EGF ′ The intersection of the segment and the string EF is H, the intersection of the bisector of ∠EGF and the arc EF is I, ∠EGI = θ, GE = GF = GI = R1, and the distance between point H and point I is C , Let J be the perpendicular foot that descends from point F to the tangent. At this time, if the tip of the steel plate having the camber shape is F and the tail end of the steel plate having the camber shape is E, the camber amount of the steel plate is specified by the distance C between the two points H and I. .

Here, from ∠HGE = ∠JEF = θ and ∠GHE = ∠EJF = 90 °, the triangle HGE and the triangle JEF are similar. Therefore, if a calculation similar to the calculation for the triangle M ₁ OP and the triangle A′PA is performed,
D = 2Rsin ² θ (Equation 7)
It becomes. Also,
From C = HI = GI−GH = R−Rcos θ,
^{R 2 cos 2 θ = R 2} - 2RC + C 2 ( Equation 8)
It becomes. From (Expression 7) and (Expression 8),
R ² (cos ² θ + sin ² θ) = R ² −2RC + C ² + DR / 2
So,
^{C 2 - 2RC + DR / 2} = 0 ( Equation 9)
It becomes. Applying the solution formula to (Equation 9),
C = R ± R (1- D / 2R) 1/2
It becomes. Therefore,
From C≈R ± (R−D / 4), C≈D / 4, 2R−D / 4
It becomes. Here, from FIG. 7, C <D <R. Therefore,
C ≒ D / 4 (Formula 10)
It becomes.

Thus, by assuming that the camber shape of the steel plate is an arc shape, it can be approximated as C≈D / 4. Therefore, when the off-center amounts measured at 10 m, 16 m, and 22 m away from the rolling mill 5 are D ₁₀ , D ₁₆ , and D ₂₂ , respectively, from the above (Formula 2) and (Formula 10) The camber amount ( _{C30, D10} , _{C30, D16} , and _{C30, D22} ) in terms of 30 m can be expressed as follows.
C _{30, D10} = 0.25 × D ₁₀ × (30000/10000) ² (Formula 11)
_{C 30, D16 = 0.25 × D} 16 × (30000/16000) 2 ( Equation 12)
_{C 30, D22 = 0.25 × D} 22 × (30000/22000) 2 ( Equation 13)

  Using the above (Formula 11) to (Formula 13), an attempt was made to compare the camber amount obtained from the measured off-center amount of the steel sheet during rolling with the cold camber amount (test number N = 70). The rolling dimension of the steel plate used as the object was longitudinal length; 30 to 50 m, plate width; 1800 to 3000 mm, plate thickness; 6 to 20 mm.

FIG. 8 and FIG. 9 show the correlation between the off-center amount at the front end of the plate during the final pass rolling and the 30 m equivalent camber amount in the cold state. FIG. 8 shows the correlation between the off-center amount (D ₁₀ , D ₁₆ , and D ₂₂ ) at the front end of the plate and the 30 m equivalent camber amount (C _{30, PSG} ) in the cold, and FIG. The correlation between the camber amount ( _{C30, D10} , _{C30, D16} and _{C30, D22} ) obtained from the measurement result of the off-center amount of the part and the cold 30m equivalent camber amount ( _{C30, PSG} ) Show. As shown in FIG. 8, there is a correlation between the cold 30 m equivalent camber amount and the off-center amount of the plate tip measured during rolling, and by using this correlation, the off-center amount of the plate tip can be reduced. If measured, the amount of camber after rolling can be calculated. Further, as apparent from FIG. 8 or FIG. 9, the correlation between the off-center amount and the camber amount becomes stronger as the measurement position of the off-center amount at the front end of the plate is farther from the finishing mill (2σ becomes smaller). The reason for this is considered to be that the off-center amount increases as the distance from the finishing mill increases, and the sensitivity to bending caused by the camber improves. Here, “2σ” is the result of calculating the deviation between the camber amount derived based on the correlation coefficient and the cold 30 m equivalent camber amount for each steel plate, ie, the standard for the estimation error. This is a result of calculation for twice the deviation σ, and it can be determined that the smaller the value, the smaller the difference between them, that is, the estimation error, and the higher the camber amount can be estimated.

At a distance of 22 m from the finishing mill, 2σ = 14.3 mm from the off-center amount, 30 m equivalent MAX camber amount (when the total length of the steel plate is L [mm] and the maximum camber amount is C, the curvature is the total length of the steel plate. It is possible to estimate the 30 m-converted MAX camber amount C ₃₀ that can be calculated by C ₃₀ = C × (30000 / L) ² (see also (Equation 2)). As described above, by measuring the off-center amount at the front end of the plate, it is possible to estimate the camber amount over the entire plate length. Further, focusing on the slope of the approximate line shown in the graph of FIG. 8, the closer to the rolling mill, the greater the slope of the approximate curve, and the closer to the finishing mill, the more presumed from the off-center amount of the plate tip. It can be seen that the 30 m equivalent camber amount increases. This indicates that the bending of the plate tip is large, and the bending of the steel plate becomes gentler as the distance from the tip of the steel plate increases.

(Calculate the total length camber amount from the off-center amount at the tip of the plate)
The calculation formula of the total length camber amount when the bending of the front end portion of the steel plate is assumed to be concentrated at 22 m from the front end of the steel plate was newly created. The calculation method will be described with reference to FIG. In the figure, D is the off-center amount at the tip of the plate at the 22 m position, D3 is the off-center amount at the rearmost end of the steel plate, X is the length on the center line corresponding to the range of the steel plate where the bending occurs, L Indicates the longitudinal length of the steel sheet projected onto the center line. Further, in FIG. 10, the tip position of the steel plate is K, the steel plate position where the bending has started to occur is M, the tail end position of the steel plate is N, the perpendicular foot that is lowered from the tip position K of the steel plate to the center line is S, 2 The middle point between points M and S is T, the intersection of a straight line passing through T perpendicular to the center line (hereinafter referred to as “straight line T”) and the curve KM is U, the intersection of the straight line T and the straight line KM is V, and the straight line The intersection of T and the straight line KN is W, the intersection of the straight line passing through K parallel to the center line and the straight line T is Y, the straight line passing through K parallel to the center line and the straight line passing through N and perpendicular to the center line Is Q. Further, assuming that the curve KM in FIG. 10 is an arc, the center of the circle forming the arc KM is G, and the intersection of the straight line connecting the two points G and V and the arc KM is two points centered on Z and G. Let the radius of a circle passing through K and M be R and ∠KGM = 2θ.

In FIG. 10, when UV = α, VY = β, and YW = γ, it can be expressed as UW = α + β−γ. 7 and 10, VZ = HI≈D / 4 and ∠UVZ = θ. Actually, since X = 22 m and D3 = 10 cm, it can be approximated to UV≈VZ / cos θ, and further, can be approximated to cos θ≈1, and can be expressed as α = UV≈VZ≈D / 4.
Further, KY = ST = TM = X / 2, ∠KYV = ∠MTV = 90 °, and ∠KVY = ∠MVT, the triangle KVY≡triangle MTV. Therefore, from VY = VT, it can be expressed as β = VY = D / 2.
Furthermore, since the straight line YW and the straight line QN are parallel, the triangle KYW and the triangle KQN are similar. Therefore, from KY: KQ = YW: QN, X / 2: L = γ: (D−D3) and can be expressed as γ = X (D−D3) / 2L.
From the above, UW = α + β−γ = D / 4 + D / 2 + X (D−D3) / 2L.
UW = 3D / 4 + X (D−D3) / 2L (Formula 14)
It can be expressed as.

  FIG. 11 shows the result of trial calculation of the 30 m equivalent camber amount with X = 22000 mm and D3 = 0 in the above (Formula 14). In this way, the 30 m equivalent camber amount calculated using the off-center amount at the front end of the plate corresponds 1: 1 with the cold 30 m equivalent MAX camber amount, and the assumption used in this calculation formula Is valid. The difference from the cold 30 m equivalent camber amount is 2σ = 12.3 mm, and the camber amount of the full length can be estimated with very good accuracy.

  From the above, it can be seen that the bending caused by the camber is actually concentrated on the tip portion of the steel plate (region of 22 m from the tip in the longitudinal direction of the steel plate). The reason for this is that as the length of the steel plate on the exit side of the rolling mill increases, the weight on the exit side increases, and the frictional force increases with the increase in the contact area with the table roller. This is because a large force is required to rotate the whole. In the results of FIG. 9, the accuracy of estimating the 30 m equivalent camber amount from the off-center amount of the plate tip is 2σ = 14.3 mm, which is inferior to FIG. 11, because the bending caused by the camber concentrates on the plate tip. It is thought that this is due to the fact that it does not take into account the effects of bending at the tail end.

2. Steel plate manufacturing method The camber amount calculation method according to the present invention can estimate the total camber amount when the plate tip passes through the off-center measurement position. Leveling correction control is possible, and application to leveling feedback control during rolling (within the plate) is possible as long as the plate tip passes the off-center measurement position. For this reason, the steel plate by which the camber was controlled efficiently can be manufactured.

  FIG. 12 is a flowchart schematically showing an embodiment of the method for manufacturing a steel sheet of the present invention. FIG. 13 is a view showing an example of a manufacturing apparatus to which the method for manufacturing a steel sheet of the present invention can be applied, and shows an enlarged part of the manufacturing apparatus. The straight arrow in FIG. 13 is the conveying direction of the steel plate. Hereinafter, the manufacturing method of the steel plate of this invention is demonstrated, referring FIG.12 and FIG.13.

  As shown in FIG. 12, the steel sheet manufacturing method of the present invention (hereinafter also referred to as “the manufacturing method of the present invention”) specifies the camber amount using the calculation method of the present invention. A step (S21), and a leveling control step (S22) for controlling the leveling of the rolling mill using the camber amount specified in the step S21.

  On the other hand, as shown in FIG. 13, the manufacturing apparatus 100 includes a rolling mill 5, a control unit 20, a side guide 7, and a CCD camera 8. The rolling mill 5 includes work rolls 1 and 2 and backup rolls 3 and 4 disposed above and below to roll the steel plate 6, and a leveling device 11 for adjusting the parallelism of the backup rolls 3 and 4. It has. The operation of the leveling device 11 is controlled by the control means 20, and when the parallelism of the backup rolls 3 and 4 is adjusted by correcting the leveling by the leveling device 11, the backup rolls 3 and 4 are disconnected to indirectly In addition, the parallelism of the work rolls 1 and 2 is also corrected.

  In the manufacturing method of the present invention, the steel plate 6 rolled by the rolling mill 5 is photographed by the CCD camera 8 in step S21. Image data photographed by the CCD camera 8 (for example, image data at the front end of the plate) is sent to the image processing device 30, and an off-center amount is measured by image processing to calculate a camber amount. The camber amount is sent to the control means 20. The control means 20 is provided with a CPU 21 that performs operation control of the leveling device 11 and a storage device for the CPU 21. The CPU 21 is configured by combining a microprocessor unit and various peripheral circuits necessary for its operation. As a storage device for the CPU 21, for example, a ROM 22 for storing programs and various data necessary for operation control of the leveling device 11, and the CPU 21. The RAM 23 and the like functioning as a work area are combined. In addition to the configuration, the control means 20 in the manufacturing apparatus 100 functions by combining the CPU 21 with software stored in the ROM 22.

  Through the processing by the image processing apparatus, the off-center amount and the camber amount of the steel plate 6 are specified (step S21). In this way, when the camber amount of the steel plate 6 is specified, information regarding the camber amount reaches the CPU 21 as an input signal via the input port 24. The CPU 21 outputs an operation command specified based on the program stored in the ROM 22 to the leveling device 11 via the output port 25, and the operation of the leveling device 11 is controlled based on the operation command (step S22). ).

  In the manufacturing method of the present invention, when the step (S22) in which the leveling of the rolling mill 5 after the next pass is controlled using the camber amount specified in step S21 (first form) is provided, the steel plate being rolled After the operation command specified based on the camber amount of 6 is output to the leveling device 11, the rolling after the next pass may be performed using the rolling mill 5 including the leveling device 11 controlled by the operation command. . On the other hand, in the manufacturing method of the present invention, when the step S22 of the form (second form) for controlling the leveling of the rolling mill 5 during rolling is provided using the camber amount specified in the step S21, Based on the camber amount derived using the off-center amount of the front end of the steel plate 6 during rolling, after specifying the operation command, the specified operation command is fed back to the leveling device 11 to control the operation, Rolling may be performed. Regardless of whether the form of step S22 is the first form or the second form, the production method of the present invention includes the step S21 of specifying the camber amount by the calculation method of the present invention. According to this manufacturing method, the steel plate 6 with a reduced camber amount can be manufactured efficiently.

It is a flowchart which shows the example of the form of the calculation method of this invention. It is a figure which shows the apparatus structural example which can apply the calculation method of this invention. It is a figure which shows the example of an image of a camber observation camera. It is a figure which shows an edge detection logic. It is a figure which shows the example of a measurement of the off-center amount in the camber generation | occurrence | production during rolling. It is explanatory drawing of length conversion of the camber amount. It is explanatory drawing of the calculation method of the camber amount from the off-center amount of a board front-end | tip part. It is a figure which shows a comparison with the amount of off-centers of a board front-end | tip part, and 30m conversion camber amount in cold. It is a figure which shows the comparison with the camber amount computed from the off-center amount of the board front-end | tip part, and the 30m conversion camber amount in cold. It is explanatory drawing of the calculation method of the full length camber amount from the off-center amount of a board front-end | tip part. It is a figure which shows the calculation result of the camber amount from the off-center amount of a board front-end | tip part. It is a flowchart which shows roughly the example of the manufacturing method of the steel plate of this invention. It is a figure which shows the example of a form of the manufacturing apparatus which can apply the manufacturing method of the steel plate of this invention. It is a figure which shows generation | occurrence | production of a camber. It is a figure which shows the definition of a camber shape and the camber amount. It is a figure which shows the measurement of the camber shape and camber amount by the off-center measurement in one place. It is a figure which shows the measurement of the camber shape and camber amount by the off-center measurement in three places. It is a figure which shows the generation | occurrence | production process of a rolling camber.

Explanation of symbols

S11 ... Rolling step S12 ... Measuring step S13 ... Camber amount deriving step S21 ... Camber amount specifying step S22 ... Leveling control step 1, 2 ... Work roll 3, 4 ... Backup roll 5 ... Rolling mill 6 ... Steel plate 7 ... Side guide 8 ... Measuring means 9 ... PC
DESCRIPTION OF SYMBOLS 10 ... Apparatus 11 ... Leveling apparatus 20 ... Control means 21 ... CPU
22 ... ROM
23 ... RAM
24 ... Input port 25 ... Output port 30 ... Image processing device 100 ... Manufacturing device

Claims (6)

During the rolling of the steel sheet by a rolling mill equipped with a work roll, a method for calculating the amount of camber of the steel sheet,
On the entry side of the rolling mill, the rolling process of rolling the steel sheet, the position of which is controlled so that the width direction center of the work roll and the width direction center of the steel sheet coincide with each other, and
Measuring the off-center amount of the rolled steel sheet at a position a predetermined distance away from the rolling mill on the exit side of the rolling mill; and
Deriving a camber amount of the rolled steel sheet using the off-center amount measured in the measurement step, a camber amount deriving step;
A method for calculating a camber amount of a steel sheet during rolling. 2. The method of calculating the camber amount of a steel plate during rolling according to claim 1, wherein only the off-center amount at the longitudinal tip of the steel plate that has passed through the rolling mill is measured in the measuring step. A correlation investigation step for investigating the correlation between the off-center amount at the longitudinal tip of the steel plate and the camber amount of the rolled steel plate is provided as a pre-process of the rolling step,
The camber amount is derived in the camber amount derivation step using the correlation investigated in the correlation investigation step and the off-center amount measured in the measurement step. Or the calculation method of the camber amount of the steel plate during rolling of 2. The off-center amount measured in the measuring step is D, the longitudinal length of the steel plate is L, the distance between the longitudinal tip of the steel plate being rolled and the portion of the steel plate that is in contact with the work roll. 3. The rolling according to claim 1, wherein when the camber amount is C and the camber amount is C, the camber amount is derived using the following (Equation 1) in the camber amount deriving step. A method for calculating the amount of camber on a steel plate.
C = 3D / 4−DX / (2L) (Formula 1) Using the calculation method of the camber amount of the steel plate during rolling according to any one of claims 1 to 4, a camber amount specifying step of specifying the camber amount;
Using the camber amount specified in the camber amount specifying step, the leveling control step of controlling the leveling of the rolling mill after the next pass, and
A method for producing a steel sheet, comprising: Using the calculation method of the camber amount of the steel plate during rolling according to any one of claims 1 to 4, a camber amount specifying step of specifying the camber amount;
Using the camber amount specified in the camber amount specifying step, the leveling control step of controlling the leveling of the rolling mill during rolling,
A method for producing a steel sheet, comprising: