JP2017185507A - Method and device for rolling steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable flaws around an end of a steel plate to become smaller than in the case where a shape of a side surface of the end of the steel plate is not measured.SOLUTION: A shape of a side surface of an end of a steel plate S in a rolling direction, in which the steel plate S is rolled, is measured. Rolling speeds of a pair of pressure rolls 12 for rolling the steel plate S are controlled to be different circumferential velocities, on the basis of the measured shape of the end of the steel plate S.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel plate rolling method and a steel plate rolling apparatus for rolling a thick plate by hot rolling.

  A thick steel plate is manufactured by rolling with a pair of upper and lower rolling rolls. At that time, different peripheral speed rolling is known in which the rolling speed of the upper roll and the rolling speed of the lower roll are made different.

  By performing the different peripheral speed rolling, the warpage of the plate when the thick steel plate is rolled can be reduced. For example, in Patent Document 1, the difference in rotational speed between the upper and lower rolling rolls is time-integrated in the longitudinal direction of the rolled material, and the elongation difference in the longitudinal direction of the upper and lower surfaces of the material to be rolled is detected to prevent sheet warpage. Technology is disclosed.

  Further, the warpage of the steel sheet occurs due to the temperature difference between the upper and lower sides of the steel sheet. For example, Patent Document 2 discloses a difference in which the surface temperature of the upper and lower surfaces of the rolled material is measured to offset the warpage amount. A technique for preventing the tip of a rolled material from warping by giving a peripheral speed ratio to the peripheral speed of the upper and lower work rolls is shown.

  Also, in different speed rolling, for example, as described in Patent Document 3, by rolling the upper rolling material on the entry side and the lower rolling material at the same speed, the upper and lower sides of the rolling material It is known that the amount of wraparound is reduced and the seam ridge is moved to the vicinity of the product edge to achieve a high product yield.

  In addition, as a technique for reducing the seam wrinkles in the vicinity of the product edge, for example, in Patent Document 4, the shape of the end face along the width direction of the material to be rolled is measured, and the slab heating furnace is based on the shape of the end face. The hot-rolling method which prevents the four rounds (seam wrinkle) of a steel plate is shown by controlling the heating amount of the steel slab surface side in and the heating amount of the steel slab back side in a steel slab heating furnace.

JP 2002-96103 A JP 2004-25254 A JP 2000-312904 A Japanese Patent No. 2792445

  As described above, there is a technique for measuring the shape of the end face along the width direction of the steel sheet, and using this shape of the end face to prevent four-sided wrinkles in the longitudinal direction of the steel sheet in the rolling direction, but in the rolling direction of the steel sheet. There has been no technique for measuring the shape of the end surface along the side surface, that is, the side surface shape of the end portion of the steel plate, and reducing the size of the four-sided ridge using the measured side surface shape of the end portion of the steel plate. For this reason, conventionally, it has been difficult to reduce the size of the four corners of the steel plate end.

  The present invention was made in view of the above circumstances, and compared with a case where the shape of the side surface of the end portion of the steel plate is not measured, the steel plate rolling method and rolling capable of reducing the four-sided ridges of the end portion of the steel plate A device is provided.

  In order to achieve the above-mentioned object, the steel sheet rolling method according to the first aspect of the present invention measures the shape of the side surface of the end of the steel sheet in the rolling direction in which the steel sheet is rolled, and measures the measured end of the steel sheet. Based on the shape of the side surface, the rolling speed of the pair of rolling rolls for rolling the steel sheet is controlled to be different peripheral speeds.

  The invention according to claim 2 calculates the difference in elongation in the rolling direction of the end portion of the steel sheet based on the measured shape of the side surface of the end portion of the steel sheet in the steel sheet rolling method according to claim 1, Based on the calculated difference in elongation, control is performed so that the rolling speed of the pair of rolling rolls for rolling the steel sheet becomes a different peripheral speed.

  The invention according to claim 3 is the steel sheet rolling method according to claim 2, wherein the shape of the side surface of the end portion of the steel sheet is determined by using the measured warpage in the thickness direction of the side surface shape of the end portion of the steel plate. Based on the corrected shape of the side surface of the end portion of the steel sheet, the difference in elongation in the rolling direction of the end portion of the steel sheet is calculated.

  The invention according to claim 4 is the steel sheet rolling method according to claim 2 or claim 3, wherein the measured shape of the side surface of the end portion of the steel plate has a convex portion at the center of the plate thickness of the steel plate. In the case of a bulge shape, set the larger one of the difference in elongation in the rolling direction above the plate thickness center and the difference in elongation in the rolling direction below the plate thickness center as the elongation difference, If the measured shape of the side surface of the end portion of the steel sheet is a double bulge shape having a concave portion in the plate thickness central portion, the difference in elongation in the rolling direction of the convex portion above the plate thickness central portion, and The elongation difference in the rolling direction of the convex part below the center part of the plate thickness is set as the larger difference between the elongation differences, and the measured shape of the side surface of the end of the steel sheet is the single bulge shape and the Any shape of double bulge shape If not, the difference between the upper and lower elongations of the steel sheet in the rolling direction is set as an elongation difference, and the rolling of a pair of rolling rolls that rolls the steel sheet based on the set elongation difference. Control so that the speed is different.

  Invention of Claim 5 is the steel plate rolling method of any one of Claims 1-4, The picked-up image of the steel plate side surface image | photographed by the imaging | photography means provided in the entrance side at least of the said pair of rolling rolls Based on the above, the shape of the side surface of the end of the steel sheet is measured.

  The steel plate rolling apparatus according to claim 6 is a pair of rolling rolls for rolling a steel plate, a measuring means for measuring the shape of the side surface of the steel plate in the rolling direction in which the steel plate is rolled, Control means for controlling the rolling speed of a pair of rolling rolls for rolling the steel sheet to be different peripheral speeds based on the shape of the side surface of the end portion.

  The invention according to claim 7 is the steel sheet rolling apparatus according to claim 6, wherein the elongation difference in the rolling direction of the end portion of the steel plate is based on the shape of the side surface of the end portion of the steel plate measured by the measuring means. The control means controls the rolling speed of a pair of rolling rolls for rolling the steel sheet to be different peripheral speeds based on the difference in elongation calculated by the calculating means.

  The invention according to claim 8 is the steel sheet rolling apparatus according to claim 7, wherein the warp in the thickness direction of the shape of the side surface of the end portion of the steel plate measured by the measuring means is used for the end portion of the steel plate. Compensating means for correcting the shape of the side surface, and the calculating means calculates the difference in elongation in the rolling direction at the end portion of the steel sheet based on the shape of the side surface of the end portion of the steel sheet corrected by the correcting means. To do.

  The invention according to claim 9 is the steel plate rolling apparatus according to claim 7 or claim 8, wherein the measured shape of the side surface of the end portion of the steel plate has a convex portion at the center of the plate thickness of the steel plate. In the case of a bulge shape, set the larger one of the difference in elongation in the rolling direction above the plate thickness center and the difference in elongation in the rolling direction below the plate thickness center as the elongation difference, If the measured shape of the side surface of the end portion of the steel sheet is a double bulge shape having a concave portion in the plate thickness central portion, the difference in elongation in the rolling direction of the convex portion above the plate thickness central portion, and The larger one of the elongation differences in the rolling direction of the convex part below the center part of the plate thickness is set as the elongation difference, and the shape of the side surface of the end of the steel sheet measured by the measuring means is the single Bulge shape and double bulge If it is not any shape of the shape, it comprises setting means for setting the difference between the upper elongation and the lower elongation of the steel sheet in the rolling direction as an elongation difference, and the control means is set by the setting means Based on the difference in elongation, the rolling speed of the pair of rolling rolls for rolling the steel sheet is controlled to be different peripheral speeds.

  A tenth aspect of the present invention is the steel sheet rolling apparatus according to any one of the sixth to ninth aspects, further comprising a photographing unit provided on at least the entry side of the pair of rolling rolls, The shape of the side surface of the end portion of the steel sheet is measured based on the captured image of the side surface of the steel sheet photographed by the photographing means.

  According to this invention, compared with the case where the shape of the side surface of the edge part of a steel plate is not measured, the four rounds of the edge part of a steel plate can be made small.

(A) is a side view which shows schematic structure of a steel plate rolling apparatus, (B) is a top view which shows schematic structure of a steel plate rolling apparatus. It is a schematic block diagram of a steel plate rolling apparatus. It is a flowchart of the steel plate rolling process performed with a process computer. It is a flowchart of a vertical elongation difference calculation process. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate. It is a figure for demonstrating the measurement of the shape of the edge part of a steel plate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A is a side view showing a schematic configuration of a steel plate rolling apparatus 10 according to the present embodiment, and FIG. 1B is a plan view of the schematic configuration of the steel plate rolling apparatus 10 according to the present embodiment. A plan view is shown. Moreover, in FIG. 2, the functional block diagram of the steel plate rolling apparatus 10 was shown.

  As shown in FIGS. 1A, 1B, and 2, the steel plate rolling apparatus 10 includes a pair of rolling rolls 12 for rolling the steel plate S, and an end portion of the steel plate S in the rolling direction in which the steel plate S is rolled. It includes a photographing camera 14 that photographs the side surface, a surface thermometer 16 that measures the surface temperature of the steel sheet S, a back surface thermometer 18 that measures the back surface temperature of the steel sheet S, and a process computer 20 that controls the entire equipment.

  As shown in FIGS. 1A, 1B, and 2, the pair of rolling rolls 12 includes an upper rolling roll 12A and a lower rolling roll 12B. The steel sheet S is conveyed in the direction of arrow A in FIG. 1 (A) and rolled by a pair of rolling rolls 12. In addition, when reverse rolling is performed, the steel sheet S is conveyed in the direction of arrow A in FIG. 1A and rolled, and then conveyed in the direction opposite to the direction of arrow A, and again by the pair of rolling rolls 12. Rolled.

  The process computer 20 measures the shape of the side surface of the end portion of the steel sheet S based on the captured image of the side surface of the steel sheet S photographed by the photographing camera 14.

  Moreover, when the process computer 20 rolls the edge part of the steel plate S based on the measured shape of the side surface of the edge part of the steel plate S, the peripheral speed (rolling speed) of the rolling rolls 12A and 12B is different. Control to be

  The process computer 20 gives a peripheral speed difference to the peripheral speeds of the rolling rolls 12 </ b> A and 12 </ b> B when rolling the end of the steel sheet S so that the difference in vertical elongation in the rolling direction of the end of the steel sheet S becomes zero.

  Hereinafter, a method of calculating the different peripheral speed ratio Δω representing the degree of the peripheral speed difference between the peripheral speeds of the rolling rolls 12A and 12B will be described.

First, a pair of rolling rolls 12 _before the upper and lower elongation difference L _rolled end of the steel plate S before rolling by (mm), _after the upper and lower elongation difference L _rolled end of the steel sheet S after rolling (mm), the pre-rolling The length of the upper surface of the end of the steel sheet S is _before LA _rolling , the length of the lower surface is _before LB _rolling , the length of the upper surface of the end of the steel sheet S _{after rolling} is LA _rolled , and the length of the lower surface is LB _rolled Is expressed by the following equation.

_Before L _rolling = _Before LA _{rolling-Before} LB _rolling (1)
_After L _rolling = _After LA _{rolling-After} LB _rolling (2)

_Before and _{after the} up-and-down elongation difference L _rolling and _after the L _rolling , calculation is performed based on the shape of the end portion of the steel sheet S measured based on the photographed image photographed by the photographing camera 14, and details will be described later. Further, from the above equations (1) and (2), the change ΔL in the vertical elongation difference at the end of the steel sheet S before and after rolling is expressed by the following equation.

ΔL = _after L _{rolling-before} L _rolling (3)

Further, the rolling rolls 12A, differential speed ratio of 12B peripheral speed of the [Delta] [omega (%) is, the peripheral speed of the rolling rolls 12A _{S A,} the peripheral speed of the rolling rolls 12B as _{S B,} is expressed by the following equation.

Δω = (S _A −S _B ) / S _B (4)

Further, assuming that the radius of the rolling roll 12B is R and the rotational speed per unit time is n, the peripheral speed S _B (m / s) of the lower rolling roll 12B is expressed by the following equation.

S _B = 2π × R × n (5)

  And when the length of the edge part of the steel plate S which performs different circumferential speed rolling is set to M (mm), time Tim (s) which carries out the different circumferential speed rolling of the edge part of the steel plate S is represented by following Formula.

Tim = M / S _B (6)

  When the vertical elongation difference at the end of the steel sheet S per 1% of the different peripheral speed ratio Δω is β (mm /%), the vertical elongation difference ΔLr at the end of the steel sheet S due to the different peripheral speed ratio Δω is It is represented by Note that β is determined in advance from experimental results and the like.

ΔLr = β × Tim × S _B × Δω
= Β × M × Δω (7)

The surface temperature (top temperature) to T _A of the steel sheet _S, when the back surface temperature (bottom temperature) and T _B, the front and rear temperature difference ΔT of the steel sheet S (° C.) is expressed by the following equation.

_{ΔT = T A -T B ··· (} 8)

  When the difference in vertical elongation at the end of the steel sheet S per 1 ° C. of the front / back temperature difference ΔT is α (mm / ° C.), the vertical elongation difference ΔLt at the end of the steel sheet S due to the front / back temperature difference ΔT is expressed by the following equation. Is done. A method for obtaining α will be described later.

ΔLt = α × ΔT (9)

  The total vertical elongation difference ΔL at the end of the steel sheet S is represented by the sum of the vertical elongation difference ΔLr due to the different peripheral speed ratio Δω and the vertical elongation difference ΔLt due to the front / back temperature difference ΔT, as shown in the following equation.

ΔL = ΔLr + ΔLt (10)

  From the above formulas (1) to (10), the vertical elongation difference α at the end of the steel sheet S per 1 ° C. of the front-back temperature difference ΔT is expressed by the following formula.

α = (ΔL−ΔLr) / ΔT
= (L _{rolled after} -L _{before rolling -β × M × Δω) / (} T A -T B) ··· (11)

When the pair of rolling rolls 12 is a reverse mill that reciprocates and rolls like a thick plate, the average of the _{first pass} α (first pass) and the _{second pass} α (double pass) One α _{round trip average} is ΔL for the first pass ΔL1, ΔLr for the first pass ΔLr1, ΔT for the first pass ΔT1, ΔL for the second pass ΔL2, ΔLr for the second pass ΔLr2, and second pass When ΔT is ΔT2, it is expressed by the following equation.

α _{round trip average} = (α _{1st pass} + α _{2nd pass} ) / 2
= [(ΔL1-ΔLr1) / ΔT1 + (ΔL2-ΔLr2) / ΔT2] / 2
(12)

  Assuming that the temperature difference between the front and back surfaces during the first pass and the second pass is substantially the same (ΔT1≈ΔT2), the following equation is established.

α _round - _{trip average} = [(ΔL1−ΔLr1) + (ΔL2−ΔLr2)] / (2 × ΔT1)
... (13)

Here, before L _{rolling before the first pass rolling, before} L _{1 pass rolling} , after L _{rolling after the first pass rolling, after} L _{1 pass rolling} , and before L _{rolling before} the second pass _rolling , L _2. Assuming that after L _{rolling after} the second _{pass rolling before pass rolling and after} L _{2 pass rolling} , the above equation (13) is expressed by the following equation from the above equation (3).

α _{round trip average} = ( _after L _{1 pass rolling−} L _{before 1 pass rolling−} ΔLr1 + L _{after 2 pass rolling−} L2 _{pass before rolling−} ΔLr2) / (2 × ΔT1) (14)

In reverse rolling, the value _after L _{1 pass rolling} is the same as that _before L _{2 pass rolling, and therefore} the above equation (14) is expressed by the following equation.

α _{reciprocal average} = ( _after L _{2 pass rolling−} L _{before 1 pass rolling−} ΔLr1−ΔLr2) / (2 × ΔT1)
(15)

  The front end portion of the first-pass steel plate S is the rear end portion of the second-pass steel plate S, but only the front end portion when the steel plate S enters the pair of rolling rolls 12 is the different peripheral speed. . For this reason, the different peripheral speed ratio Δω when the rear end portion of the second pass is rolled by the pair of rolling rolls 12 is normally zero (ΔLr2 = 0). Therefore, the following equation holds.

α _{reciprocal average} = ( _after L _{2 pass rolling−} L _{before 1 pass rolling−} ΔLr1) / (2 × ΔT1)
= (After L _{2 pass rolling} -L _{Before 1 pass rolling-} β × M × Δω) / (2 × ΔT1) (16)

When the imaging camera 14 that captures the shape of the end portion of the steel sheet S is provided only on the entry side of the pair of rolling rolls 12 as in the present embodiment, when reciprocating rolling is performed according to the above equation (16). It is possible to obtain the _average vertical elongation difference α at the end of the steel sheet S per 1 ° C. of the front-back temperature difference ΔT, that is, the vertical elongation difference α _{round-trip average} .

Using the vertical elongation difference α _{reciprocal average} obtained in this way, when performing the next rolling, the different peripheral speed ratio Δω is obtained so that it becomes zero _after the L _rolling .

  As described above, the following expression is established from the above expressions (3), (7), (9), and (10).

ΔL = _after L _{rolling−before} L _rolling = ΔLr + ΔLt = β × M × Δω + α × ΔT (17)

Here, the α _{reciprocal average} represented by the above equation (16) is used as α in the above equation (17), and the following equation is established when the equation _after Δ _{rolling is set} to zero _after L _rolling .

Δω = (− L _{before rolling−} α _{reciprocal average} × ΔT) / (β × M) (18)

By setting the peripheral speed of the rolling roll 12A and the rolling roll 12B when rolling the end of the steel sheet S so that the different peripheral speed ratio Δω represented by the above equation (18) is established, the steel sheet after rolling _After the up-and-down elongation difference L _rolling of the edge part of S, it becomes zero, and it can suppress four rounds.

In addition, when reverse rolling is performed by a plurality of reciprocating rollings, for example, when reverse rolling is performed by two reciprocating rollings, the α _{reciprocating average} in the first reciprocating rolling is the α _{reciprocating average 1} , and the second reciprocating rolling. The α _{reciprocal average} in rolling may be _calculated by the following equation, with α _{reciprocal average 2} being the α _{reciprocal average 2} and distribution coefficient being r (0 ≦ r ≦ 1).

α _{round trip average} = r × α _{round trip average} 1+ (1−r) × α _{round trip average 2} (19)

Further, when the reverse rolling is performed in a reciprocating rolling over n times (n ≧ 3) is the distribution coefficient _{r 1, r 2, ··· r} n (r 1 + r 2 + ··· + r n = 1 ), The α _{round-trip average} may be obtained by the following equation.

α _{round trip average} = r ₁ × α _{round trip average 1} + r ₂ × α _{round trip average 2} +... + r _n × α _{round trip average n} (20)

  Next, the steel plate rolling process executed by the process computer 20 will be described with reference to the flowchart shown in FIG.

In step S100, the controlled rolling rolls 12A, and 12B so that the peripheral speed _{S A} rolling roll 12A when the differential speed rolling at the end of the steel sheet S, the peripheral speed of the rolling rolls 12B and _{S B.} In addition, after length M which performs different peripheral speed rolling in the edge part of the steel plate S, the peripheral speed of the rolling roll 12A and the peripheral speed of the rolling roll 12B are the same speed normally.

In step S102, it obtains the surface temperature _{T A} of the steel sheet S from the surface thermometer 16.

In step S < _b > 104, the back surface temperature TB of the steel sheet S is acquired from the back surface thermometer 18.

  In step S <b> 106, the photographing camera 14 is instructed to shoot at the timing when the leading end of the steel sheet S passes the photographing camera 14, and a photographed image of the side surface of the leading end of the steel sheet S photographed by the photographing camera 14 is acquired.

In step S108, based on the captured image acquired in step S106, the L1 _pass before rolling before the _{first pass rolling} is calculated. Specifically, the L1 _pass before rolling before the _{first pass rolling} is calculated by the elongation difference calculating process shown in FIG.

  As shown in FIG. 4, in step S200, a process for acquiring a boundary point is executed. Hereinafter, the case where the captured image acquired in step S106 is a captured image 30 as shown in FIG. 5 will be described. 5, the lower right corner of the captured image 30 is the origin O, and in FIG. 5 the left and right direction (the rolling direction of the steel sheet S) is the X direction, and the up and down direction (the thickness direction of the steel sheet S) is the Y direction. . Further, the left direction and the upward direction from the origin O are positive directions, and the right direction and the downward direction are negative directions.

  First, while scanning one pixel at a time in order from the upper left pixel of the captured image 30, it is determined whether or not the luminance difference between the luminance of the target pixel and the luminance of the pixel on the left is equal to or greater than a predetermined threshold value. This is because a hot-rolled steel sheet is, for example, around 1000 ° C. and emits light spontaneously, so that a portion with high luminance is considered to be a steel sheet. Then, while scanning in the X direction, the pixel whose luminance is higher than the threshold of the pixel on the left by the threshold or more is set as the image start point at that height, and then the luminance of the pixel of interest is the pixel on the left A pixel that is lower than the luminance by a threshold or more is set as an image end point at that height. For example, as shown in FIG. 5, when the luminance value graph 32 of the pixel whose Y coordinate is y1 is viewed, the luminance value of the pixel whose coordinates are (x1, y1) rapidly increases. To do. In addition, since the luminance value of the pixel at the coordinates (x2, y1) falls rapidly, this pixel is set as the image end point. By executing such processing from the upper left pixel to the lower right pixel of the image, a boundary point group 34 that is a set of boundary points of the image can be acquired.

  In step S202, for example, as shown in FIG. 6, the boundary point located at the uppermost right is the boundary point 1, and the boundary point closest to the boundary point 1 is the boundary point 2. Similarly, a boundary point closest to the boundary point i and not yet assigned a boundary point number is defined as a boundary point (i + 1). In this way, boundary point numbers are assigned to all boundary points.

  In step S204, the curvature of the image of the edge part of the steel plate S represented by the boundary point group 34 is corrected. For example, as shown in FIG. 7, first, the leftmost boundary point L in the boundary point group 34 is obtained. Then, focusing on boundary point 1 and boundary point L / 2 (intermediate point between boundary point 1 and boundary point L), the boundary point closest to the X coordinate of each of these two boundary points is defined as the lowermost boundary point. Search is performed in the reverse number order from N, and the boundary points are 1 ′ and L / 2 ′, respectively.

  Next, as shown in FIG. 8, a straight line y (== slope m passing through the midpoint A between the boundary points 1 and 1 ′ and the midpoint B between the boundary points L / 2 and L / 2 ′ is n. m × x + n).

  Next, the entire boundary point group 34 is translated by n pixels in the Y direction so that the midpoint A coincides with the origin O. Then, the coordinates of each boundary point included in the boundary point group 34 are corrected so that the inclination m = 0. That is, for all boundary points, a value obtained by subtracting (X coordinate × m) from the Y coordinate is set as a new Y coordinate. Thereby, the straight line y shown in FIG. 9 coincides with the X axis passing through the origin O.

  In step S206, boundary points U, D, Right, and Left for determining the shape of the end of the steel sheet S are specified. Specifically, as shown in FIG. 10, a boundary point C that is an intersection of the X axis passing through the origin O and the boundary point group 34 is obtained. That is, a boundary point where the Y coordinate changes from plus to minus or 0 in the order of the boundary point number is defined as a boundary point C. Then, with the boundary point C as the starting point, the difference between the Y coordinates of the boundary point 1 and the boundary point 1 ′ is H, the coefficient a is a coefficient, and the boundary point where the Y coordinate of the boundary point exceeds a × H for the first time is the boundary point number. Search in reverse order of. A boundary point where the Y coordinate of the boundary point first exceeds a × H is defined as an upper boundary point U. Also, starting from the boundary point C, a boundary point whose Y coordinate is less than −a × H for the first time is searched in the order of the boundary point number. A boundary point whose Y coordinate is less than −a × H for the first time is defined as a lower boundary point D. Note that a is a fixed coefficient and is 0.3 in the example of FIG. 10, but the value of a is not limited to this, and may be set as appropriate based on experimental results and the like.

  The boundary point that is the leftmost point between the boundary point U and the boundary point D is the boundary point Left, and the rightmost boundary point is the boundary point Right. In the example of FIG. 10, boundary point U = boundary point Left, and boundary point D = boundary point Right.

  In the following, as shown in FIG. 11, the X coordinate of the boundary point U is Xu, the X coordinate of the boundary point D is Xd, the X coordinate of the boundary point Left is Xl, and the X coordinate of the boundary point Right is Xr.

  In step S208, it is determined whether the following equation is satisfied, where TB is a determination threshold value for determining whether the shape of the end portion of the steel sheet S is a single bulge shape or a double bulge shape. Note that the determination threshold value TB may be set as appropriate based on experimental results and the like.

Xl> Xu + TB and Xl> Xd + TB (21)

  Here, the single bulge shape is a shape having a convex portion at the center of the plate thickness of the steel sheet S as shown in FIG. That is, step S208 determines whether or not the boundary point Left is on the left side of the boundary point U or boundary point D by the determination threshold value TB or more. By this determination, the shape of the end portion of the steel sheet S is a single bulge. It can be determined whether or not the shape.

  If the determination in step S208 is affirmative, that is, if the shape of the end of the steel sheet S is a single bulge shape, the process proceeds to step S210. On the other hand, if the determination in step S208 is negative, that is, if the shape of the end of the steel sheet S is not a single bulge shape, the process proceeds to step S212.

  In step S210, assuming that the shape of the end portion of the steel sheet S is a single bulge shape, the difference in vertical elongation at the end portion of the steel sheet S is set. Specifically, the larger one of the difference in elongation in the rolling direction on the upper side from the sheet thickness central part and the difference in elongation in the rolling direction on the lower side from the sheet thickness central part is set as the difference in vertical elongation. For example, in the case of FIG. 12, the elongation difference (X1-Xu) in the rolling direction on the upper side from the boundary point Left, that is, the elongation difference (X1-Xd) in the rolling direction on the lower side from the boundary point Left. The larger elongation difference (Xl−Xd) is set as the difference in vertical elongation at the end of the steel sheet S. In addition, when the direction of the boundary point U is employ | adopted, it is an upward extension shape, and when the direction of the boundary point D is employ | adopted, it is a downward extension shape.

  In step S212, it is determined whether or not the shape of the end portion of the steel sheet S is a double bulge shape by determining whether or not the following equation is satisfied.

Xu> Xr + TB and Xd> Xr + TB (22)

  Here, a double bulge shape is a shape which has a recessed part in the plate | board thickness center part of the steel plate S, as shown in FIG. That is, step S212 determines whether or not the boundary point U or boundary point D is on the left side of the determination threshold TB or more than the boundary point Right, and by this determination, the shape of the end of the steel sheet S is double bulge. It can be determined whether or not the shape.

  If the determination in step S212 is affirmative, that is, if the shape of the end of the steel sheet S is a double bulge shape, the process proceeds to step S214. On the other hand, if the determination in step S212 is negative, that is, if the shape of the end of the steel sheet S is not a double bulge shape, the process proceeds to step S216.

  In step S214, the difference in vertical elongation at the end of the steel sheet S is set assuming that the end of the steel sheet S has a double bulge shape. Specifically, the larger one of the difference in elongation in the rolling direction of the convex portion above the central portion of the plate thickness and the difference in elongation in the rolling direction of the convex portion lower than the central portion of the thickness is set as the differential elongation. . For example, in the case of FIG. 13, the elongation difference (Xu−Xr) in the upper rolling direction from the boundary point Right, that is, the elongation difference (Xd−Xr) in the lower rolling direction from the boundary point Right. The larger elongation difference (Xu−Xr) is set as the vertical elongation difference at the end of the steel sheet S. In addition, when the direction of the boundary point U is employ | adopted, it is an upward extension shape, and when the direction of the boundary point D is employ | adopted, it is a downward extension shape.

  In step S216, the determination threshold value for determining whether or not the shape of the end portion of the steel sheet S is an upwardly extended shape or a downwardly extended shape is set to TL, and it is determined whether or not the following expression is satisfied. It is determined whether or not the shape of the end portion is an upwardly elongated shape.

Xu> Xd + TL (23)

  Here, as shown in FIG. 11, the upwardly elongated shape is a shape in which the amount of elongation on the upper side of the center portion of the steel sheet S is larger than the amount of elongation on the lower side. That is, step S216 determines whether or not the boundary point U is present on the left side of the boundary point D by the determination threshold TL or more. Based on this determination, whether or not the shape of the end of the steel sheet S is an upwardly elongated shape. It can be determined whether or not.

  If the determination in step S216 is affirmative, that is, if the shape of the end of the steel sheet S is an upwardly elongated shape, the process proceeds to step S218. On the other hand, if the determination in step S216 is negative, that is, if the shape of the end of the steel sheet S is not an upwardly elongated shape, the process proceeds to step S220.

  In step S218, assuming that the shape of the end portion of the steel sheet S is an upwardly extending shape, the difference in the vertical extension of the end portion of the steel sheet S is set. Specifically, the difference between the upper and lower elongations of the steel sheet S in the rolling direction is set as the difference in elongation. For example, in the case of FIG. 11, the difference (Xu−Xd) in the X coordinate between the upper boundary point U and the lower boundary point D is set as the vertical elongation difference of the end portion of the steel sheet S.

  In step S220, it is determined whether or not the shape of the end portion of the steel sheet S is a downwardly elongated shape by determining whether or not the following expression is satisfied.

Xd> Xu + TL (24)

  Here, as shown in FIG. 14, the downwardly elongated shape is a shape in which the amount of elongation on the lower side of the center portion of the steel sheet S is larger than the amount of elongation on the upper side. That is, step S220 determines whether or not the boundary point D is present on the left side of the boundary point U by more than the determination threshold TL. Based on this determination, whether the shape of the end of the steel sheet S is a downward extension shape. It can be determined whether or not.

  If the determination in step S220 is affirmative, that is, if the shape of the end of the steel sheet S is a downwardly elongated shape, the process proceeds to step S222. On the other hand, if the determination in step S220 is a negative determination, that is, if the shape of the end of the steel sheet S is not a downwardly elongated shape, the process proceeds to step S224.

  In step S222, assuming that the shape of the end portion of the steel sheet S is a downward extension shape, the difference in the vertical extension of the end portion of the steel sheet S is set. Specifically, the difference between the upper and lower elongations of the steel sheet S in the rolling direction is set as the difference in elongation. For example, in the case of FIG. 14, the difference (Xd−Xu) in the X coordinate between the lower boundary point D and the upper boundary point U is set as the vertical elongation difference of the end portion of the steel sheet S.

  In step S224, the shape of the end portion of the steel sheet S is set to a shape having no difference in vertical elongation, and the vertical elongation difference is set to zero.

  As described above, the shape of the end of the steel sheet S is determined.

  Returning to FIG. 3, in step S110, the first pass rolling of the steel sheet S is performed.

  In step S112, the second rolling of the steel sheet S is performed.

  In step S114, the photographing camera 14 is instructed to shoot at the timing when the leading end portion of the steel sheet S (the rear end portion of the second pass) passes through the photographing camera 14, and the photographed image of the leading end portion of the steel sheet S photographed by the photographing camera 14 To get.

In step S116, based on the captured image acquired in step S114, the post-L2 _{pass rolling after the second pass rolling} is calculated as in step S108.
At step S118, the obtaining of the surface temperature _{T A} of the steel sheet S from the surface thermometer 16.
In step S120, it acquires the back side temperature _{T B} of the steel sheet S from the back surface thermometer 18.

In step S122, the different peripheral speed ratio Δω is calculated by the above equations (8), (16), and (18). That is, the front-back temperature difference ΔT is calculated by substituting the surface temperature T _A of the steel sheet S acquired in step S102 and the back surface temperature T _B of the steel sheet S acquired in step S104 into the above equation (8). Further, it sets in step S100, the peripheral speed S _A rolling roll 12A when the differential speed rolling at the end of the steel sheet _S, calculates the Δω than the peripheral speed S _B and the (4) of the rolling rolls 12B . Then, calculated ΔT, calculated Δω, _before L _{1 pass rolling} calculated in step S108, _after L _{2 pass rolling} calculated in step S116, M and β are substituted into the above equation (16) to calculate α _{round-trip average} . To do. And the calculated back-and-forth temperature difference ΔT obtained by substituting the calculated α _{round-trip average} , the surface temperature T _A of the steel sheet S acquired in step S118, and the back surface temperature T _B of the steel sheet S acquired in step S120 into the above equation (8). , And _after the L2 _{pass rolling} calculated in step S116 is used as _before L _rolling , M and β are substituted into the above equation (18) to calculate Δω. Note that the difference in elongation calculated in steps S108 and S116 is a positive number in the case of an upwardly extending shape, and a negative number in the case of a downwardly extending shape.

Then, when rolling the front end portion of the next steel sheet S, as the differential speed ratio Δω calculated in step S122, sets the peripheral speed S _B of the peripheral speed S _A and the rolling roll 12B of the rolling rolls 12A To do.
In step S124, different peripheral speed rolling is performed by controlling the rolling rolls 12A and 12B so as to be driven at the peripheral speeds S _A and S _B set in step S122. As a result, it is possible to suppress quadruple wrinkles.

  These series of controls may be repeated in the same manner after the third pass. That is, when performing rolling of the 3rd pass and the 4th pass, Steps S102-S124 are performed again. Moreover, when rolling of the 5th pass and the 6th pass is performed, step S102-S124 are performed again. Thus, steps S102 to S124 are repeatedly executed according to the number of reciprocating rolling operations.

  Thus, in the present embodiment, the shape of the side surface of the end portion of the steel sheet S is photographed by the photographing camera 14, and rolling is performed so that the difference in vertical elongation at the end portion of the steel sheet S becomes 0 based on the photographed image. Control is performed so that the peripheral speeds of the rolls 12A and 12B become different peripheral speeds. Thereby, it is possible to accurately reduce the four rounds of the tip of the steel sheet S.

  In the present embodiment, the case where the photographing camera 14 is provided on the entry side of the pair of rolling rolls 12 has been described, but the photographing camera 14 may be provided also on the exit side of the pair of rolling rolls 12. In this case, since the shape of the end portion of the steel sheet S before and after rolling can be photographed by one rolling, the above control can be performed even when the rolling is performed once instead of the reverse rolling.

DESCRIPTION OF SYMBOLS 10 Rolling apparatus 12A, 12B Roll roll 14 Photographing camera 16 Surface thermometer 18 Back surface thermometer 20 Process computer

Claims (10)

Measure the shape of the side surface of the end of the steel plate in the rolling direction in which the steel plate is rolled,
A steel plate rolling method for controlling a rolling speed of a pair of rolling rolls for rolling the steel plate to be a different peripheral speed based on the measured shape of the side surface of the end of the steel plate. In the steel plate rolling method according to claim 1,
Based on the measured shape of the side surface of the end of the steel sheet, the elongation difference in the rolling direction of the end of the steel sheet is calculated,
A steel plate rolling method for controlling the rolling speed of a pair of rolling rolls for rolling the steel sheet to be different peripheral speeds based on the calculated elongation difference. In the steel plate rolling method according to claim 2,
Using the warpage in the thickness direction of the shape of the side surface of the end portion of the steel sheet, correcting the shape of the side surface of the end portion of the steel plate, based on the corrected shape of the side surface of the end portion of the steel plate, A steel plate rolling method for calculating an elongation difference in the rolling direction at an end of the steel plate. In the steel sheet rolling method according to claim 2 or claim 3,
When the shape of the side surface of the end portion of the steel plate measured is a single bulge shape having a convex portion at the plate thickness central portion of the steel plate, the difference in elongation in the rolling direction above the plate thickness central portion, and The elongation difference in the rolling direction on the lower side from the center of the plate thickness, and the larger one is set as the elongation difference,
If the measured shape of the side surface of the end portion of the steel sheet is a double bulge shape having a concave portion in the plate thickness central portion, the difference in elongation in the rolling direction of the convex portion above the plate thickness central portion, and The elongation difference in the rolling direction of the convex part below the center part of the plate thickness, and the larger one is set as the elongation difference,
When the measured shape of the side surface of the end portion of the steel sheet is neither the single bulge shape nor the double bulge shape, the difference between the upper elongation and the lower elongation of the steel plate in the rolling direction. Is set as the differential elongation,
A steel plate rolling method for controlling a rolling speed of a pair of rolling rolls for rolling the steel sheet to be different peripheral speeds based on the set elongation difference. In the steel plate rolling method according to any one of claims 1 to 4,
A steel plate rolling method for measuring the shape of the side surface of the end portion of the steel sheet based on a photographed image of the side surface of the steel sheet photographed by photographing means provided at least on the entry side of the pair of rolling rolls. A pair of rolling rolls for rolling steel sheets;
Measuring means for measuring the shape of the side surface of the end of the steel plate in the rolling direction in which the steel plate is rolled;
Based on the shape of the side surface of the end of the steel sheet, control means for controlling the rolling speed of a pair of rolling rolls for rolling the steel sheet to be different peripheral speeds;
Steel plate rolling equipment including In the steel plate rolling apparatus according to claim 6,
Based on the shape of the side surface of the end portion of the steel sheet measured by the measuring means, comprising calculating means for calculating the elongation difference in the rolling direction of the end portion of the steel sheet,
The said control means is controlled so that the rolling speed of a pair of rolling roll which rolls the said steel plate becomes a different peripheral speed based on the said elongation difference calculated by the said calculation means. In the steel plate rolling apparatus according to claim 7,
Using a warp in the thickness direction of the shape of the side surface of the end portion of the steel sheet measured by the measuring means, comprising correction means for correcting the shape of the side surface of the end portion of the steel plate,
The said calculation means calculates the elongation difference in the said rolling direction of the edge part of the said steel plate based on the shape of the side surface of the edge part of the said steel plate correct | amended by the said correction means. In the steel plate rolling apparatus according to claim 7 or claim 8,
When the shape of the side surface of the end portion of the steel plate measured is a single bulge shape having a convex portion at the plate thickness central portion of the steel plate, the difference in elongation in the rolling direction above the plate thickness central portion, and The elongation difference in the rolling direction on the lower side from the center of the plate thickness, and the larger one is set as the elongation difference,
If the measured shape of the side surface of the end portion of the steel sheet is a double bulge shape having a concave portion in the plate thickness central portion, the difference in elongation in the rolling direction of the convex portion above the plate thickness central portion, and The elongation difference in the rolling direction of the convex part below the center part of the plate thickness, and the larger one is set as the elongation difference,
When the shape of the side surface of the end portion of the steel plate measured by the measuring means is neither the single bulge shape nor the double bulge shape, the upper elongation and lower side of the steel plate in the rolling direction It has setting means to set the difference from the elongation as the elongation difference,
The said control means is a steel plate rolling apparatus controlled based on the said elongation difference set by the said setting means so that the rolling speed of a pair of rolling roll which rolls the said steel plate may become a different peripheral speed. In the steel plate rolling apparatus according to any one of claims 6 to 9,
The photographing means provided at least on the entry side of the pair of rolling rolls,
The said measurement means measures the shape of the side surface of the edge part of the said steel plate based on the picked-up image of the steel plate side surface image | photographed by the said imaging means.

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