Steel plate rolling method, steel plate rolling system, warpage estimation device, and program

Abstract

To provide a steel plate rolling method capable of suppressing warpage of a steel plate.SOLUTION: A steel plate rolling method includes: measuring a side face shape of an end in a rolling direction, of a steel plate rolled by a rolling machine; estimating warpage of the steel plate, on the basis of the measured side face shape of the end; controlling a rolling condition so as to suppress the estimated warpage of the steel plate; and rolling the steel plate by the rolling machine.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a steel plate rolling method, a steel plate rolling system, a warp estimation device, and a program.

Background Art

[0002] Patent Document 1 discloses a technique for predicting the occurrence of the upward warp amount of a material to be rolled from the relationship between the shape ratio and the pickup amount when the material to be rolled is rolled by a rolling roll.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above technique, the prediction accuracy of the warp is not sufficient, and it is difficult to sufficiently suppress the warp.

[0005] The present invention has been made in view of the above problems, and its main object is to provide a steel plate rolling method, a steel plate rolling system, a warp estimation device, and a program capable of suppressing the warp of a steel plate.

Means for Solving the Problems

[0006] To solve the above problems, an aspect 1 of the present invention measures the side shape of an end portion of a steel plate rolled by a pair of upper and lower work rolls of a rolling mill in the rolling direction, and based on the measured side shape of the end portion, estimates the warp that will occur in the steel plate in subsequent rolling, and controls the rolling conditions so as to suppress the estimated warp, and rolls the steel plate by the rolling mill. This makes it possible to suppress the warp of the steel plate.

[0007] Aspect 2 of the present invention is, in the above Aspect 1, the control of the rolling conditions may be the pickup control of the steel plate by the lower work roll of the rolling mill. According to this, it becomes possible to suppress the warping of the steel plate by the pickup control.

[0008] Aspect 3 of the present invention is, in the above Aspect 1 or 2, in the estimation of the warping, based on the side surface shape of the end portion, and the pickup shift and rolling shape ratio when the steel plate is rolled, the warping direction and warping amount of the steel plate may be estimated. According to this, it becomes possible to improve the estimation accuracy of the warping of the steel plate.

[0009] Aspect 4 of the present invention is, in the above Aspect 3, in the estimation of the warping, the temperature difference between the upper and lower surfaces of the steel plate may not be used for the estimation of the warping. According to this, it becomes possible to facilitate the estimation of the warping of the steel plate.

[0010] Aspect 5 of the present invention is, in any one of the above Aspects 1 to 4, in the estimation of the warping, the warping may be estimated based on the shape difference between the upper and lower portions in the side surface shape of the end portion. According to this, it becomes possible to improve the estimation accuracy of the warping of the steel plate.

[0011] Aspect 6 of the present invention is, in any one of the above Aspects 1 to 5, the side surface shape of the end portion may be extracted by a shape measuring device. According to this, it becomes possible to estimate the warping of the steel plate using the side surface shape of the steel plate.

[0012] Aspect 7 of the present invention is, in the above Aspect 6, the warping of the steel plate is the area of the upper region surrounded by the extension line of the upper surface of the steel plate set in the side surface shape, the tip line extending in the plate thickness direction passing through the tip of the end portion, and the contour line above the tip of the end portion, and the extension line of the lower surface of the steel plate, the tip line, and the difference or ratio of the area of the lower region surrounded by the contour line below the tip of the end portion. It may be estimated based on. According to this, it becomes possible to improve the estimation accuracy of the warping of the steel plate.

[0013] Aspect 8 of the present invention is that, in the above Aspect 7, the warp of the steel plate may be estimated based on an index obtained by normalizing the difference between the area of the upper region and the area of the lower region according to the thickness of the steel plate. According to this, it is possible to improve the estimation accuracy of the warp of the steel plate regardless of the thickness of the steel plate.

[0014] Aspect 9 of the present invention is that, in the above Aspect 7 or 8, the warp of the steel plate may be estimated based on an index obtained by dividing the difference between the area of the upper region and the area of the lower region by the square of the thickness of the steel plate. According to this, it is possible to improve the estimation accuracy of the warp of the steel plate regardless of the thickness of the steel plate.

[0015] Aspect 10 of the present invention is a steel plate rolling system including a rolling mill for rolling a steel plate, a measuring unit for measuring a side shape of an end portion of the steel plate rolled by the rolling mill in a rolling direction, an estimating unit for estimating a warp that occurs in the steel plate in a subsequent rolling based on the measured side shape of the end portion, and a control unit for controlling rolling conditions so as to suppress the estimated warp and causing the rolling mill to roll the steel plate. According to this, it is possible to suppress the warp of the steel plate.

[0016] Aspect 11 of the present invention is a warp estimating device including an acquiring unit for acquiring a side shape of an end portion of a steel plate rolled by a rolling mill in a rolling direction, and an estimating unit for estimating a warp that occurs in the steel plate in a subsequent rolling based on a shape difference between an upper portion and a lower portion in the measured side shape of the end portion. According to this, it is possible to improve the estimation accuracy of the warp of the steel plate.

[0017] Aspect 12 of the present invention is a program for causing a computer to execute acquiring a side shape of an end portion of a steel plate rolled by a rolling mill in a rolling direction, estimating a warp that occurs in the steel plate in a subsequent rolling based on the measured side shape of the end portion, and calculating rolling conditions for suppressing the estimated warp. According to this, it is possible to improve the estimation accuracy of the warp of the steel plate.

Advantages of the Invention

[0018] According to the present invention, it is possible to suppress the warpage of the steel sheet.

Brief Description of the Drawings

[0019]

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Figure 17

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification and each figure, elements that are the same as those described above with respect to the already shown figures may be denoted by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0021] One of the production troubles in the rolling process is "warpage". When warpage occurs, the warped steel plate collides with the equipment, causing operation troubles such as equipment failure and line stop. In addition, the addition of a refining process (correction, heat treatment, press, etc.) to flatten the warped steel plate has an adverse effect on cost and delivery accuracy. It is known that the warpage of the steel plate is caused by the upper and lower asymmetry factors in rolling (upper and lower deformation resistance difference, friction difference, roll speed difference, geometric asymmetry, etc.).

[0022] In the embodiments of the present invention described below, the object is to predict and suppress the warpage of the steel plate, particularly to prevent downward warpage in the final rolling pass, and to simply and accurately predict the warpage of the steel plate.

[0023] FIG. 1 is a diagram showing a configuration example of a steel plate rolling system 100. FIGS. 2 to 4 are side view, plan view, and front view showing the main part of the rolling mill 1. The arrow R in the figure indicates the rolling direction of the steel plate W by the rolling mill 1. The steel plate rolling system 100 includes a rolling mill 1, cameras 71 and 72, a warpage estimation device 8, and a control unit 9.

[0024] The rolling mill 1 includes a pair of upper and lower work rolls 2 and 3 for rolling the steel plate W, a conveying roll 4 for conveying the steel plate W, and backup rolls 5 and 6 for supporting the work rolls 2 and 3 respectively. The rolling mill 1 reciprocates the steel plate W by the conveying roll 4 and repeatedly rolls the steel plate W by the work rolls 2 and 3.

[0025] Camera 71 is an embodiment of the shape measurement device, and examples of the imaging means include a color camera or a monochrome camera, etc., but it is not particularly limited. This camera 71 is arranged on the side of the conveying line, images the steel plate W conveyed by the conveying roll 4 from the side to generate an image, and outputs it to the warp estimation device 8. The side refers to the width direction of the steel plate W orthogonal to the rolling direction R, and is a direction parallel to the axial direction of the work rolls 2, 3 and the conveying roll 4. The camera 71 may be provided on both sides of the conveying line.

[0026] Camera 71 images the end ew in the rolling direction R of the steel plate W conveyed by the conveying roll 4. In order to image the end ew of the steel plate W, it is necessary to grasp the position of the end ew of the steel plate W. For example, the temperature of the conveying line is measured by a radiation thermometer (not shown) provided in pair with the camera 71, and the imaging of the camera 71 is turned on at the timing when the measured temperature becomes a predetermined value or more, thereby imaging the end ew of the steel plate W. Alternatively, images may be taken at regular time intervals, the images may be sorted by operation data or image processing, and only the images in which the end ew of the steel plate is within the viewing angle may be used as measurement data.

[0027] It is preferable that the camera 71 images the steel plate W on the way of being conveyed toward the work rolls 2, 3 rather than the steel plate W immediately after being discharged from the work rolls 2, 3. This is because it is difficult to image the steel plate W immediately after being discharged from the work rolls 2, 3 due to the influence of descaling water.

[0028] Also, the camera 71 images both the front and rear ends ew in the rolling direction R of the steel plate W. For example, one camera 71 may image both the front and rear ends ew, or two cameras 71 may be provided to image the front end ew and the rear end ew individually.

[0029] Camera 72 is located obliquely above the conveying line, images the steel plate W conveyed by the conveying roll 4 from obliquely above to generate an image. Not limited to this, the camera 72 may also be arranged on the side of the conveying line in the same manner as the camera 71. Also, the camera 72 may be provided on both sides of the conveying line.

[0030] The image generated by the camera 72 is used to measure the warp of the steel plate W and generate a prediction model, and is not used for estimating the warp of the steel plate W by the warp estimation device 8. For this reason, the camera 72 may not be included in the steel plate rolling system 100.

[0031] Alternatively, the camera 72 may be a stereo camera or combined with projection light to measure the three-dimensional shape of the steel plate W and obtain the warp height. Alternatively, the warp height may be obtained by measuring the upper surface of the steel plate W using a laser rangefinder or microwave. Further, a pendulum may be installed on the outlet side of the rolling mill 1, and the warp height may be obtained from the rotation angle of the pendulum that contacts the steel plate W. The warp height may be quantified as a warp curvature by circular approximation or quadratic approximation. Further, the means for quantifying the warp height may be changed depending on the type of warp.

[0032] The warp estimation device 8 acquires the side shape of the end portion ew of the steel plate W from the image generated by the camera 71, estimates the warp that will occur in the steel plate W during subsequent rolling based on this, and calculates rolling conditions for suppressing the estimated warp. Details of the configuration and operation of the warp estimation device 8 will be described later.

[0033] Based on the calculation result of the warp estimation device 8, the control unit 9 controls the rolling conditions so as to suppress the estimated warp, and causes the rolling mill 1 to roll the steel plate W.

[0034] In the present embodiment, the control of the rolling conditions is the pickup control of the steel plate W by the lower work roll 3 of the rolling mill 1. The warp estimation device 8 calculates a pickup control amount for suppressing the estimated warp, and the control unit 9 drives the hydraulic drive unit 91 according to the calculation result to adjust the height of the lower work roll 3.

[0035] With reference to FIG. 5, the pickup of the steel plate W by the lower work roll 3 will be described. The height difference PU between the top surface of the inlet-side conveying roll 4 and the top surface of the lower work roll 3 is generally called the "pickup amount".

[0036] In addition, among the steel plates W, the height difference PS between the intermediate line m4 of the upper and lower surfaces of the conveyance portion conveyed to the conveyance roll 4 on the inlet side and the intermediate line m3 of the upper and lower surfaces of the cutting portion sandwiched between the upper and lower work rolls 2 and 3 is called "pickup shift".

[0037] When the pickup shift PS is zero, the steel plate W is horizontally incident on the gap between the work rolls 2 and 3. At this time, the incident angle of the steel plate W is set to zero.

[0038] As shown in FIG. 5, when the intermediate line m4 of the conveyance portion is below the intermediate line m3 of the cutting portion, the steel plate W is obliquely incident upward from the lower side on the gap between the work rolls 2 and 3. At this time, the pickup shift PS and the incident angle are set to be positive.

[0039] On the other hand, when the intermediate line m4 of the conveyance portion is above the intermediate line m3 of the cutting portion, the steel plate W is obliquely incident downward from the upper side on the gap between the work rolls 2 and 3. At this time, the pickup shift PS and the incident angle are set to be negative.

[0040] In rolling, if the pickup shift PS is zero, that is, the incident angle is not zero, a elongation difference occurs between the upper surface side and the lower surface side, and warping occurs in the steel plate W. Also, it is known that the warping direction changes according to the rolling shape ratio.

[0041] For example, as shown in FIG. 6, when the steel plate W is obliquely incident upward from the lower side on the gap between the work rolls 2 and 3 and the rolling shape ratio is relatively small, downward warping occurs in the rolled steel plate W. When downward warping occurs in the steel plate W, there is a risk that the steel plate W may collide with equipment such as the conveyance roll 4 on the outlet side.

[0042] The rolling shape ratio m is represented by the following mathematical formula 1. As shown in FIG. 7, L is the contact length at which the steel plate W contacts the work rolls 2 and 3. h m is the average plate thickness of the steel plate W. The average plate thickness h mIt is represented by the following mathematical formula 2. h1 is the plate thickness before rolling, and h2 is the plate thickness after rolling. The contact length L is represented by the following mathematical formula 3. R is the roll radius. ΔH is represented by the following mathematical formula 4.

[0043]

Number

[0044]

Number

[0045]

Number

[0046]

Number

[0047] Also, as shown in FIG. 8, even when the pickup shift is 0, if there is a temperature difference between the upper and lower surfaces of the steel plate W, the steel plate W will warp. For example, when the lower surface side of the steel plate W is relatively hot and the upper surface side is relatively cold, the lower surface side of the steel plate W will expand more than the upper surface side, so the rolled steel plate W will warp upward.

[0048] In this embodiment, pickup control is performed to suppress the warping of the steel plate W. However, the method for suppressing the warping of the steel plate W is not limited to this. For example, the peripheral speed difference between the work rolls 2 and 3 may be controlled, or the temperature difference between the upper and lower surfaces of the steel plate W may be controlled.

[0049] FIG. 9 is a block diagram showing a configuration example of the warping estimation device 8. The warping estimation device 8 is a computer including a CPU, a RAM, a ROM, a non-volatile memory, an input / output interface, and the like. The CPU executes information processing according to a program loaded from the ROM or the non-volatile memory into the RAM.

[0050] The program may be supplied via an information storage medium such as an optical disk or a memory card, or may be supplied via a communication network such as the Internet or a LAN.

[0051] The warp estimation device 8 includes a shape acquisition unit 11, a warp estimation unit 12, and a condition calculation unit 13. These functional units are realized by the CPU executing information processing according to a program. In a storage unit 19 accessible to the warp estimation device 8, a prediction model for predicting the warp of the steel plate W is stored.

[0052] The shape acquisition unit 11 acquires the side shape of the end ew of the steel plate W from the image generated by the camera 71. The side shape of the end ew is the contour shape of the end ew when viewed from the side. The combination of the camera 71 and the shape acquisition unit 11 corresponds to a "measurement unit" that measures the side shape of the end ew of the steel plate W.

[0053] The warp estimation unit 12 estimates the warp that will occur in the steel plate W during subsequent rolling based on the side shape of the end ew acquired by the shape acquisition unit 11. The warp estimation unit 12 estimates the warp of the steel plate W using a pre-created prediction model. The prediction model is, for example, a regression equation.

[0054] The condition calculation unit 13 calculates a pickup shift for suppressing the warp estimated by the warp estimation unit 13 and outputs it to the control unit 9. The control unit 9 controls the pickup of the steel plate W by the lower work roll 3 of the rolling mill 1 so as to realize the pickup shift calculated by the condition calculation unit 13.

[0055] FIG. 10 is a flowchart showing an example of the procedure of the steel plate rolling method realized in the steel plate rolling system 100. The warp estimation device 8 included in the steel plate rolling system 100 executes the information processing shown in the figure according to a program. FIG. 11 is a diagram showing an example of the image MG1 generated by the camera 71.

[0056] The steel plate rolling method of this embodiment is executed, for example, after the second-to-last pass of the final pass. That is, based on the side surface shape of the end ew of the steel plate W after the second-to-last pass, the warp of the steel plate W after the final pass is estimated, and the pickup shift during the final pass for suppressing the estimated warp is calculated.

[0057] Also, in this embodiment, without using the temperature difference between the upper and lower surfaces of the steel plate W, the warp of the steel plate W is estimated based on the shape difference between the upper and lower parts in the side surface shape of the end ew of the steel plate W. That is, the side surface shape of the end ew of the steel plate W is measured as an index representing the balance of the metal flow on the upper and lower surfaces across the entire plate thickness, and is utilized for predicting the warp.

[0058] When the temperature profile in the plate thickness direction is asymmetric between the upper and lower sides, the tip shape also becomes asymmetric between the upper and lower sides. For example, when the temperature of the upper surface is high, the upper surface side is stretched more during rolling, so the upper surface side becomes longer at the tip. Conversely, when the temperature of the lower surface is high, the lower surface side is stretched more during rolling, so the lower surface side becomes longer at the tip.

[0059] Therefore, by measuring the side surface shape of the end ew of the steel plate W, it is possible to estimate the balance of the metal flow across the entire plate thickness direction.

[0060] As shown in FIG. 10, first, the warp estimation device 8 measures the side surface shape of the end ew of the steel plate W from the image MG1 generated by the camera 71, and calculates a "vertical and horizontal shape difference index" as a representative value of the tip shape (S11 to S16, processing as the shape acquisition unit 11).

[0061] Specifically, the warp estimation device 8 acquires the image MG1 from the camera 71 (S11). The camera 71 images the steel plate W from the side so that only the side surface of the steel plate W can be extracted in the image MG1.

[0062] Next, the warp estimation device 8 extracts the contour of the end ew of the steel plate W from the image MG1 (S12). For the extraction of the contour, a rule-based method such as a differential filter or a method based on machine learning may be used.

[0063] Of the contour of the steel plate W, the upper straight portion is extracted as the upper surface ps, the lower straight portion is extracted as the lower surface ds, and the portion connecting the upper surface ps and the lower surface ds is extracted as the contour of the end portion ew. If the steel plate W is warped, as shown in FIG. 11, the upper surface ps and the lower surface ds are inclined.

[0064] Next, the warp estimation device 8 rotates the image MG1 so that the upper surface ps and the lower surface ds of the steel plate W become horizontal (S13, see FIG. 12). Further, the warp estimation device 8 calculates the plate thickness between the upper surface ps and the lower surface ds of the steel plate W (S14).

[0065] Next, the warp estimation device 8 sets a rectangular frame RC at the end portion ew of the steel plate W in the image MG1 (S15, see FIG. 13).

[0066] As shown in FIG. 13, the rectangular frame RC is a square composed of a tip line ft extending in the plate thickness direction passing through the tip ff of the end portion ew, an upper extension line pt obtained by extending the upper surface ps, a lower extension line dt obtained by extending the lower surface ds, and a rear end line bt extending in the plate thickness direction.

[0067] The region surrounded by the upper extension line pt obtained by extending the upper surface ps, the tip line ft passing through the tip ff of the end portion ew, and the contour line pc above the tip ff of the end portion ew is defined as the "upper region PA".

[0068] The region surrounded by the lower extension line dt obtained by extending the lower surface ds, the tip line ft passing through the tip ff of the end portion ew, and the contour line dc below the tip ff of the end portion ew is defined as the "lower region DA".

[0069] In S13 above, the image MG1 is rotated so that the upper surface ps and the lower surface ds of the steel plate W become horizontal. However, the present invention is not limited to this, and the rectangular frame RC may be set to be inclined in accordance with the inclination of the upper surface ps and the lower surface ds without rotating the image MG1.

[0070] Next, the warp estimation device 8 calculates an upper and lower shape difference index (S16). The upper and lower shape difference index is an index based on the difference or ratio between the area of the upper region PA and the area of the lower region DA in the rectangular frame RC set in S15 above.

[0071] The vertical shape difference index is preferably an index obtained by normalizing the difference between the area of the upper region PA and the area of the lower region DA in the rectangular frame RC set in S15 above according to the plate thickness of the steel plate W. Thereby, the same value is calculated for the ends of similar shapes with different plate thicknesses.

[0072] Specifically, as shown in the following formula 5, the vertical shape difference index ΔS is an index obtained by dividing the difference between the area of the upper region PA and the area of the lower region DA by the square of the plate thickness TH of the steel plate W. PA and DA in the formula represent the areas of the upper region PA and the lower region DA.

[0073]

Equation

[0074] Then, the warp estimation device 8 estimates the warp of the steel plate W based on the vertical shape difference index ΔS (processing as the warp estimation unit 12 in S17), and calculates a pickup shift for suppressing the estimated warp of the steel plate W (processing as the condition calculation unit 13 in S18).

[0075] In addition to the vertical shape difference index ΔS representing the side shape of the end ew, the warp estimation device 8 estimates the warp direction and warp amount of the steel plate W based on the pickup shift and the rolling shape ratio when the steel plate W is rolled.

[0076] Specifically, the warp estimation device 8 calculates the warp ρ of the steel plate W based on the vertical shape difference index ΔS, the pickup shift PS, and the rolling shape ratio Γ using the regression formula shown in the following formula 6. a0 to a6 are coefficients. The warp ρ of the steel plate W is defined as the height from the flat upper surface of the steel plate W to the uppermost point of the end ew, for example, as shown in FIG. 14.

[0077]

Equation

[0078] When generating the prediction model, that is, when obtaining the coefficients a0 to a6 of the regression equation, regression analysis is performed using the warpage height ρ of the steel plate W measured from the image generated by the above-described camera 72 (see FIGS. 1 to 4).

[0079] As described above, in the present embodiment, the temperature difference between the upper and lower surfaces of the steel plate W is not used for estimating warpage. That is, the regression equation shown in Equation 6 does not include a term for the temperature difference between the upper and lower surfaces.

[0080] When using the temperature difference between the upper and lower surfaces, there are disturbances such as water flowing on the steel plate such as descaling and steam on the line as disturbances in temperature measurement, so it is difficult to perform stable temperature measurement on both the upper and lower surfaces. In addition, even if the temperature difference between the upper and lower surfaces can be accurately measured, only the surface temperature can be measured by the radiation thermometer, and it is difficult to predict warpage.

[0081] What affects warpage is the balance of metal flow across the entire plate thickness. In predicting warpage, it is necessary to know the temperature distribution across the entire plate thickness. However, when the plate thickness is thick or when the surface is rapidly cooled using descaling, at the time of temperature measurement, the steel plate is in the reheating process, the temperature distribution in the plate thickness direction changes greatly in a short time, and the difference between the surface temperature and the deep temperature is also significant. Therefore, it is generally difficult to accurately estimate the balance of metal flow across the entire plate thickness using the measured surface temperature.

[0082] For this reason, in the present embodiment, the temperature difference between the upper and lower surfaces of the steel plate W is not used for estimating warpage, and by using the vertical shape difference index ΔS representing the side shape of the end portion ew, it is possible to easily and accurately predict the warpage of the steel plate W.

[0083] FIG. 15 is a diagram showing a prediction example of warpage based on the temperature difference between the upper and lower surfaces of the prior art. FIG. 16 is a diagram showing a prediction example of warpage based on the vertical shape difference index of the present embodiment. The horizontal axis represents the predicted value of the warpage height, and the vertical axis represents the actual value of the warpage height.

[0084] When the camber height is greater than 0, it means upward camber, and when the camber height is less than 0, it means downward camber. The threshold value CL is the camber height at which it is predicted that when downward camber occurs in the steel plate W, the tip of the steel plate W will contact the conveying roll 4 and waist break will occur.

[0085] In predicting the camber height in this embodiment, a regression equation including the up-and-down shape difference index ΔS shown in the above formula 6 was used. On the other hand, in predicting the camber height in the prior art, a regression equation in which the up-and-down shape difference index ΔS in formula 6 is replaced with the upper and lower surface temperature difference ΔT was used.

[0086] Looking at the prediction example of camber based on the upper and lower surface temperature difference in FIG. 15 (prior art), although a large downward camber such that the actual value of the camber height is lower than the threshold value CL, that is, a large downward camber that may cause waist break, occurs, the predicted value of the camber height is near zero, and there is a point where the degree of downward camber is underestimated.

[0087] On the other hand, looking at the prediction example of camber based on the up-and-down shape difference index in FIG. 16 (embodiment), although the overall prediction accuracy of the camber height is about the same as that of the prior art in FIG. 15, when downward camber occurs in the steel plate W, there is a risk that the steel plate W will collide with equipment such as the conveying roll 4 on the outlet side of the rolling mill 1. The importance of predicting downward camber is extremely high. In this regard, the occurrence of a large downward camber below the threshold value CL can be accurately predicted, and it has great technical significance.

[0088] From the above discussion, it was demonstrated that by using the up-and-down shape difference index ΔS representing the side shape of the end portion ew instead of the upper and lower surface temperature difference of the steel plate W for estimating camber, the occurrence of significant downward camber can be predicted.

[0089] Hereinafter, the calculation of the pickup shift for suppressing camber will be described. FIG. 17 is a diagram showing an example of the relationship between the pickup shift and the camber height, and shows the result of evaluating the camber reduction effect according to the pickup shift. The verification was performed by FEM (Finite Element Method) calculation.

[0090] First, in order to determine the input value of the tip shape, a rolling calculation was performed by applying a predetermined temperature difference between the upper and lower surfaces to a steel plate with a rectangular tip, and the tip shape generated when there is a temperature difference between the upper and lower surfaces was calculated. Next, the calculated tip shape was re-applied as the tip shape of a flat steel plate with the same predetermined temperature difference between the upper and lower surfaces, and then the rolling calculation was performed to evaluate the curvature after rolling.

[0091] Fig. 17 shows the result of comparing the warpage height predicted by the regression equation from the tip shape before rolling with the warpage height calculated by FEM. Similar to the demonstration example in the above-mentioned actual machine test, it can be confirmed that in the FEM calculation, the warpage can be predicted without using the temperature difference between the upper and lower surfaces by using the tip shape.

[0092] Next, a method for deriving the optimum value of the pickup shift for the predicted warpage will be described. This can be realized, for example, by performing calculations with various changes only in the pickup shift using the same regression equation for warpage prediction on a steel plate where the occurrence of downward warpage is foreseen, and obtaining the pickup shift at which the warpage amount becomes zero.

[0093] In this study, under the condition of a temperature difference of 10°C between the upper and lower surfaces where the occurrence of downward warpage is foreseen, calculations were performed with various changes only in the pickup shift, and the relationship between the pickup shift and the warpage height was obtained by linearly regressing the warpage amount, and the pickup shift that makes the warpage amount zero was obtained using that relationship.

[0094] As an example of this method, it was confirmed by FEM calculation with the pickup shift estimated to make the warpage height zero that the warpage height is near 0.

[0095] As described above, according to this embodiment, it was confirmed that the occurrence of downward warpage can be avoided by predicting the downward warpage from the measurement result of the tip shape and appropriately setting the pickup shift for the predicted downward warpage.

[0096] Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible for those skilled in the art.

[0097] In the above embodiment, an example of predicting warpage using the vertical shape difference index ΔS without using the upper and lower surface temperature difference ΔT has been described. However, this does not exclude the application of the upper and lower surface temperature difference ΔT, and the upper and lower surface temperature difference ΔT may be used together with the vertical shape difference index ΔS for predicting warpage. The upper and lower surface temperature difference ΔT is calculated by a radiation thermometer (not shown) or the like.

Explanation of Reference Numerals

[0098] 1 Rolling mill, 2, 3 Work rolls, 4 Conveyor roll, 5, 6 Backup rolls, 71, 72 Cameras, 8 Warpage estimation device, 9 Control unit, 91 Drive unit, 11 Shape acquisition unit, 12 Warpage estimation unit, 13 Condition calculation unit, 19 Storage unit, W Steel plate, ew End

Claims

1. Measuring the side shape of the end portion of a steel sheet rolled by a pair of upper and lower work rolls of a rolling mill in the rolling direction, estimating the warp that will occur in the steel sheet during subsequent rolling based on the measured side shape of the end portion, controlling the rolling conditions so as to suppress the estimated warp, and rolling the steel sheet with the rolling mill, A steel sheet rolling method.

2. The control of the rolling conditions is the pickup control of the steel sheet by the lower work roll of the rolling mill, The steel sheet rolling method according to Claim 1.

3. In the estimation of the warp, the warp direction and warp amount of the steel sheet are estimated based on the side shape of the end portion, as well as the pickup shift and rolling shape ratio when the steel sheet is rolled, The steel sheet rolling method according to Claim 1.

4. In the estimation of the warp, the temperature difference between the upper and lower surfaces of the steel sheet is not used for the estimation of the warp, The steel sheet rolling method according to Claim 3.

5. In the estimation of the warp, the warp is estimated based on the shape difference between the upper and lower portions in the side shape of the end portion, The steel sheet rolling method according to Claim 1.

6. The side shape of the end portion is extracted by a shape measuring device, The steel sheet rolling method according to Claim 1.

7. The warp of the steel sheet is estimated based on the difference or ratio between the area of the upper region surrounded by the extension line of the upper surface of the steel sheet set in the side shape, the tip line extending in the plate thickness direction passing through the tip of the end portion, and the contour line above the tip of the end portion, and the area of the lower region surrounded by the extension line of the lower surface of the steel sheet, the tip line, and the contour line below the tip of the end portion, The steel sheet rolling method according to Claim 6.

8. The warp of the steel sheet is estimated based on an index obtained by normalizing the difference between the area of the upper region and the area of the lower region according to the plate thickness of the steel sheet, The steel sheet rolling method according to Claim 7.

9. The warp of the steel sheet is estimated based on an index obtained by dividing the difference between the area of the upper region and the area of the lower region by the square of the plate thickness of the steel sheet, The steel sheet rolling method according to Claim 7.

10. A rolling mill for rolling a steel sheet, A measuring unit for measuring the side shape of the end portion of the steel sheet rolled by the rolling mill in the rolling direction, An estimating unit for estimating the warp that will occur in the steel sheet during subsequent rolling based on the measured side shape of the end portion, A control unit for controlling the rolling conditions so as to suppress the estimated warp and rolling the steel sheet with the rolling mill, A steel sheet rolling system comprising the above.

11. An acquisition unit that acquires the side surface shape of an end portion of a steel sheet rolled by a rolling mill in the rolling direction; An estimation unit that estimates the warpage that occurs in the steel sheet during subsequent rolling based on the shape difference between the upper and lower portions of the measured side surface shape of the end portion; A warpage estimation device comprising the above.

12. Acquiring the side surface shape of an end portion of a steel sheet rolled by a rolling mill in the rolling direction; Estimating the warpage that occurs in the steel sheet during subsequent rolling based on the measured side surface shape of the end portion; and Calculating rolling conditions for suppressing the estimated warpage; A program for causing a computer to execute the above.

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