Slab rolling suitability prediction method, steel sheet manufacturing method, slab rolling suitability prediction device, and steel sheet manufacturing device

Abstract

To provide a method for predicting the propriety of rolling of a slab capable of predicting the propriety of rolling of the slab when the slab is edge-rolled.SOLUTION: In the method for predicting the propriety of rolling of a slab, the propriety of the slab when the slab is edge-rolled is predicted. A slab rolling suitability prediction method includes a reference data acquisition step of acquiring reference data serving as a reference of a degree of twist of the slab before the edging is performed, a position information acquisition step of acquiring position information of the slab at a plurality of points parallel to an upper side or a lower side formed along a width direction of the slab before the edging is performed, a prediction information generation step of generating prediction information predicting a degree of twist of the slab when the edging is performed, based on the reference data and the position information at the plurality of points, and a suitability information generation step of generating suitability information regarding suitability of rolling of the slab, based on the prediction information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for predicting the suitability of rolling a slab when the slab is width-reduced, a method for manufacturing a steel plate, an apparatus for predicting the suitability of rolling a slab, and an apparatus for manufacturing a steel plate. [Background technology]

[0002] For example, a hot rolling line for producing hot-rolled steel sheets includes a heating furnace, a roughing mill, and a finishing mill. The hot rolling line also includes a width reducing section between the heating furnace and the roughing mill, which reduces the width of the slab. That is, the slab is adjusted to a plate width according to the product specifications by the width reducing section, and then rolled to a predetermined thickness.

[0003] If rolling is performed with a twisted slab, defects in quality such as scratches may occur. Therefore, it is common to detect twists in the slab before rolling. For example, in Patent Document 1, the dimensions of two specific slabs are obtained from an image of the side surface of the slab after width reduction, and it is determined whether the width reduction is normal or not based on the absolute value of the difference between these two dimensions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4457888 Summary of the Invention [Problem to be solved by the invention]

[0005] When a slab is subjected to width reduction, the width may increase locally, which is called a width defect. If a width defect occurs in the slab, the slab may not be caught by the edger of the roughing mill, causing the production line to stop.

[0006] As described above, in the method of Patent Document 1, an image of the side surface of the slab after width reduction is used to determine whether the width reduction was normal. Slabs determined to have had an abnormal width reduction are removed from the production line. When removing the slab from the production line, the production line is stopped and then the slab is carried out using a crane. This results in a problem of reduced productivity depending on the time the production line is stopped.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method for predicting the suitability of rolling a slab, which is capable of predicting the suitability of rolling a slab when the slab is reduced in width. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following features.

[0009] [1] A method for predicting whether a slab is suitable for rolling when the slab is width-reduced, comprising: a reference data acquisition step of acquiring reference data serving as a reference for the degree of twist of the slab before the width reduction is performed; a position information acquisition step of acquiring position information of the slab at a plurality of points parallel to the upper or lower edge formed along the width direction of the slab before the width reduction; a prediction information generating step of generating prediction information that predicts the degree of twist of the slab when the width is reduced based on the reference data and the position information of a plurality of points; and a suitability information generating step of generating suitability information regarding the suitability of rolling the slab based on the prediction information. [2] a torsion amount calculation step of calculating a torsion amount of the slab based on the position information of a plurality of points; A shape information acquisition step of acquiring shape information of the slab including the length of the slab in the width direction, The method for predicting the suitability of rolling a slab according to [1], wherein in the prediction information generation step, the prediction information is generated based on the calculated amount of twist of the slab, the shape information of the slab, and the reference data. [3] The method for predicting the suitability of a slab for rolling described in [1] or [2], wherein in the position information acquisition process, the position information of multiple points measured while the slab is pressed from above and below is acquired. [4] A steel plate manufacturing method in which a steel plate is manufactured using the method for predicting the rolling suitability of a slab according to any one of [1] to [3], a width reduction step of performing the width reduction on the slab from which the target slab for the width reduction has been selected in a manner according to the suitability information; a rolling step of rolling the slab that has been subjected to the width reduction. [5] A slab rolling suitability prediction device that predicts whether a slab is rolled properly when the slab is reduced in width, a reference data acquisition unit that acquires reference data that is a reference for the degree of twist of the slab before the width reduction is performed; a position information acquisition unit that acquires position information of the slab at multiple points parallel to the upper or lower edge formed along the width direction of the slab before the width reduction is performed; a prediction information generating unit that generates prediction information that predicts the degree of twist of the slab when the width is reduced based on the reference data and the position information of a plurality of points; and a suitability information generating unit that generates suitability information regarding the suitability of rolling the slab based on the prediction information. [6] A steel plate manufacturing apparatus for manufacturing steel plates, [5] The slab rolling suitability prediction device according to [5], a width reducing section that performs width reduction on the slab from which the target slab for width reduction has been selected in a manner according to the prediction information; a rolling section that rolls the slab that has been subjected to the width reduction. [Effects of the Invention]

[0010] The method for predicting the suitability of slab rolling of the present invention includes a prediction information generation step of generating prediction information that predicts the degree of twist of a slab when it is width-reduced, based on reference data that serves as a reference for the degree of twist of the slab and position information of multiple points on the slab.The method for predicting the suitability of slab rolling also includes a suitability information generation step of generating suitability information regarding the suitability of rolling the slab, based on the generated prediction information.Therefore, it is possible to predict the suitability of rolling a slab before width reduction of the slab.This makes it possible to improve the production efficiency of steel sheets. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing an overview of a steel plate manufacturing apparatus. [Figure 2] FIG. 2 is an explanatory diagram showing a state in which a slab is width-reduced. [Figure 3] FIG. 2 is a functional block diagram of a device for predicting the suitability of rolling a slab. [Figure 4] 1 is a flow chart of a method for manufacturing a steel sheet, including a processing flow of a method for predicting the suitability of rolling a slab. [Figure 5] FIG. 2 is an explanatory diagram showing an aspect in which a slab is imaged by a measuring unit. [Figure 6] FIG. 5 is an explanatory diagram showing an aspect of the position information acquisition step in step S02 of FIG. 4. [Figure 7] FIG. 5 is an explanatory diagram showing an aspect of the prediction information generating step in step S05 of FIG. [Figure 8] FIG. 10 is an explanatory diagram showing an arrangement of a measurement unit according to a modified example. [Figure 9] The positional relationship of the positional information of multiple points on the slab with respect to the reference data is shown. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a steel plate manufacturing apparatus 100 that manufactures steel plates by rolling slabs. In the steel plate manufacturing apparatus 100 of Fig. 1, a slab SB is transported in a transport direction D1 to manufacture steel plates. The steel plate manufacturing apparatus 100 has a heating furnace 10. In the heating furnace 10, the slab SB is heated to a predetermined temperature.

[0013] The steel plate manufacturing apparatus 100 has a width reducing section 20 and a measurement section 30. In the width reducing section 20, the slab SB is reduced in the width direction until it reaches a predetermined width. In addition, the shape of the slab SB before being reduced in width by the width reducing section 20 is measured by the measurement section 30.

[0014] The measuring unit 30 is not particularly limited, but may be, for example, a camera capable of capturing an image of the slab SB, a distance measuring device capable of measuring the shape of the slab SB, etc. In this embodiment, an example in which a camera is used as the measuring unit 30 will be described.

[0015] The steel plate manufacturing apparatus 100 has a rough rolling section 40 and a finish rolling section 50 . The roughing mill 40 and the finishing mill 50 have a pair of work rolls arranged to sandwich the slab SB from above and below. Each of the pair of work rolls is supported by a backup roll. In the steel plate manufacturing apparatus 100, the roughing mill 40 and the finishing mill 50 constitute a rolling section that rolls the slab SB that has been subjected to width reduction.

[0016] In the rough rolling section 40, the width-reduced slab SB is subjected to rough rolling until it reaches a predetermined thickness. In addition, in the finish rolling section 50, the rough-rolled slab SB is subjected to finish rolling until it reaches a predetermined thickness. The finish-rolled slab SB becomes a steel plate.

[0017] The steel plate manufacturing apparatus 100 has a run-out table 60 that cools the finish-rolled steel plate, and a coiler 70 that winds up the cooled steel plate. On the run-out table 60, the steel plate is cooled to a predetermined temperature by being sprayed with cooling water.

[0018] The steel plate manufacturing apparatus 100 has a slab rolling suitability prediction device 80 that predicts whether the slab SB will be rolled properly when the slab SB is width-reduced by the width reduction section 20. The slab rolling suitability prediction device 80 is connected to the width reduction section 20 and the measurement section 30 so as to be able to communicate data with them.

[0019] 2 shows a state in which the slab SB is width-reduced. As shown in FIG. 2, the width-reducing section 20 is provided with a conveying section 15 that conveys the slab SB in the conveying direction D1.

[0020] The width reducing section 20 has pinch rolls 21 and 22 arranged in the conveying direction D1. The pinch rolls 21 and 22 are arranged so that the slab SB can be sandwiched between a pair of rolls arranged in the vertical direction.

[0021] A pair of dies 23 for pressing down the slab SB in the width direction are provided between the pinch rolls 21 and 22. The pair of dies 23 are arranged opposite to each other in the left-right direction when viewed from the conveying direction D1.

[0022] The measuring unit 30 measures the shape of the slab SB when it is pressed from above and below. In this embodiment, the measuring unit 30 measures the shape of the slab SB when it is pressed from above and below by the pinch rolls 21. This makes it possible to measure the shape of the slab SB when it is leveled horizontally. The measuring unit 30 is installed so as to be able to image the end face of the tail end of the slab SB in the conveying direction D1. The image data captured by the measuring unit 30 is converted, for example, by image processing, into distance data from the measuring unit 30, in other words, shape data of the slab SB.

[0023] Fig. 3 shows functional blocks of a slab rolling suitability prediction device 80. As shown in Fig. 3, the slab rolling suitability prediction device 80 has an input / output unit 81 connected to external devices, a memory unit 82 that stores various data, and a control unit 83 that controls the operation of the slab rolling suitability prediction device 80. The input / output unit 81, the memory unit 82, and the control unit 83 are connected to each other via a bus 84 so that they can communicate data with each other.

[0024] The input / output unit 81 is an interface that is provided to enable data communication with an external device. In this embodiment, the input / output unit 81 is connected to the measurement unit 30.

[0025] The memory unit 82 is a writable non-volatile memory such as an EPROM. The memory unit 82 is not particularly limited, but can be, for example, a storage device such as an HDD or SSD. The memory unit 82 stores measurement data measured by the measurement unit 30, reference data that serves as a standard for the degree of twist of the slab, and the like. The reference data is not particularly limited, but can be, for example, the twist angle, which is the angle between the horizontal direction and a line connecting multiple points on the slab that are parallel to the upper or lower edge formed along the width direction of the slab. Below, an example will be described in which the twist angle is used as the reference data.

[0026] The control unit 83 is a computer including a CPU. The control unit 83 controls the operation of the slab rolling suitability prediction device 80. The control unit 83 has a reference data acquisition unit 83a that acquires reference data that serves as a reference for the degree of twist of the slab, and a position information acquisition unit 83b that acquires position information of multiple points on the slab. The control unit 83 also has a twist amount calculation unit 83c that calculates the amount of twist of the slab SB, and a shape information acquisition unit 83d that acquires shape information of the slab SB.

[0027] The control unit 83 has a prediction information generation unit 83e that generates prediction information that predicts the degree of twist of the slab when it is width-reduced, and a suitability information generation unit 83f that generates suitability information regarding the suitability of rolling the slab.

[0028] The functions of the reference data acquisition unit 83a, the position information acquisition unit 83b, the twist amount calculation unit 83c, the shape information acquisition unit 83d, the prediction information generation unit 83e, and the suitability information generation unit 83f are realized by executing programs stored in the memory unit 82.

[0029] The reference data acquisition unit 83a reads out the reference data stored in the storage unit 82 to acquire the reference data.

[0030] The position information acquisition unit 83b reads out the measurement data measured by the measurement unit 30, i.e., the imaging data, from the memory unit 82 and acquires position information of multiple points parallel to the upper or lower edge formed along the width direction of the slab.

[0031] The prediction information generating unit 83e generates prediction information that predicts the degree of twisting of the slab when the width is reduced, based on the reference data and position information of a plurality of points.

[0032] The suitability information generating unit 83f generates suitability information regarding the suitability of rolling the slab based on the prediction information.

[0033] 4 shows a flow of a steel plate manufacturing method, including a processing flow of a method for predicting the suitability of slab rolling. As shown in FIG. 4, the reference data acquisition unit 83a executes a reference data acquisition step by reading out reference data stored in the storage unit 82 (step S01). The reference data acquisition step of step S01 is executed before the width reduction step, which will be described later, is carried out.

[0034] The position information acquisition unit 83b reads out the measurement data measured by the measurement unit 30 from the memory unit 82 and executes a position information acquisition process (step S02). In the position information acquisition process of step S02, position information of multiple points parallel to the upper edge or lower edge formed along the width direction DX of the slab is acquired. The position information acquisition process of step S02 is executed before the width reduction process described later is performed.

[0035] The twist amount calculation unit 83c executes a twist amount calculation step of calculating the twist amount of the slab using the position information of the multiple points of the slab SB acquired in the position information acquisition step of step S02 (step S03).

[0036] The morphological information acquisition unit 83d executes a morphological information acquisition step of acquiring morphological information of the slab SB (step S04). The morphological information acquisition unit 83d acquires the morphological information of the slab SB, including the width direction length of the slab SB, for example, by acquiring the dimensional values ​​of the slab stored in the memory unit 82.

[0037] The prediction information generating unit 83e generates prediction information using the amount of twist of the slab SB, the shape information of the slab SB, and the reference data, and executes the prediction information generating step (step S05).

[0038] The suitability information generating unit 83f generates suitability information regarding the suitability of rolling the slab based on the prediction information generated in the prediction information generating step of step S03 (step S06).

[0039] The control unit 83 determines whether it is appropriate to perform the rolling process on the slab SB based on the suitability information generated in the suitability information generating step of step S06 (step S07).

[0040] When the control unit 83 determines in step S07 that it is appropriate to perform the rolling process on the slab (step S07: YES), the control unit 83 advances the slab to the width reduction section 20, where the width reduction process is performed (step S08). Thus, in the width reduction process of step S08, the slab that is selected as the target for width reduction according to the suitability information is subjected to width reduction.

[0041] Next, the rolling process is carried out by rolling the width-reduced slab in the roughing mill 40 and the finishing mill 50 (step S09). The slab SB is rolled in the rolling process of step S09 to be produced as a steel plate.

[0042] If the slab rolling suitability prediction device 80 determines in step S07 that it is not appropriate to perform the rolling process on the slab (step S07: NO), it executes a removal process to remove the slab from the production line of the steel plate manufacturing equipment 100 (step S10).

[0043] It is preferable that the removed slab be reheated in the heating furnace 10. In this way, by reheating the slab SB in the heating furnace 10, the twist is eliminated by creep deformation, and the amount of twist can be reduced.

[0044] Furthermore, the processing and judgment in steps S01 to S07 should be performed when the width reduction amount in the width reduction step of step S08 is 300 mm or more. This is because problems caused by the amount of twist tend to occur when width reduction is performed with a width reduction amount of 300 mm or more. By doing so, it is possible to effectively improve the yield.

[0045] Fig. 5 shows a manner in which the slab SB is imaged by the measuring unit 30. As shown in Fig. 5, the pinch roll 21 is provided so that the slab SB can be sandwiched between a pair of rolls 21a and 21b arranged in the vertical direction.

[0046] 5 shows a state in which the slab SB is sandwiched between pinch rolls 21 at the leading end in the conveying direction D1. FIG. 5(a) shows a cross section of the slab SB taken along line A1-A1 at the base end in the conveying direction D1. FIG. 5(b) shows a cross section of the slab SB taken along line B1-B1 at the center in the conveying direction D1. The measuring unit 30 is provided so as to be able to capture an image of the slab SB at the base end in the conveying direction D1.

[0047] As shown in Figures 5(a) and (b), in the width direction DX of the slab SB, one end side may be at a different height from the other end side, which is called twisting. Here, for example, if the pressing force of the pinch rolls 21 is set to about 50 tf, the weight of the slab SB is about 15-20 tf. In this case, when the slab SB is sandwiched between the pinch rolls 21, the amount of twist in the portion pressed by the pinch rolls 21 becomes zero. In other words, in the width direction DX of the slab SB, the height positions from one end side to the other end side are the same.

[0048] It is preferable that the measurement unit 30 images the slab SB while the slab SB is sandwiched between the pinch rolls 21. By having the measurement unit 30 image the slab SB in this state, it is possible to image the shape of the slab SB in a state where the variations in height in the width direction DX have been leveled.

[0049] That is, the slab SB may be measured by the measuring unit 30 while being pressed from above and below. Note that the slab SB may be pressed by a pressing means other than the pinch roll 21, as long as the slab SB is pressed from above and below and the variations in height in the width direction can be evened out.

[0050] Figure 6 shows the position information acquisition process of step S02 in Figure 4. Figure 6 shows the width direction DX of the slab SB, the longitudinal direction DY of the slab SB, and the thickness direction DZ of the slab SB. The longitudinal direction DY of the slab SB coincides with the conveying direction D1 of the slab SB.

[0051] Point P1 on one end side of the width direction DX and point P2 on the other end side of the width direction DX are located on the end face of the slab SB in the longitudinal direction DY. Points P1 and P2 are parallel to the upper edge UL or lower edge BL of the slab SB. In the example shown in Figure 6, points P1 and P2 are midpoints in the thickness direction DZ, i.e., the center positions of the plate thickness.

[0052] In the position information acquisition process of step S02, position information of multiple points parallel to the upper side UL or the lower side BL of the slab SB, such as points P1 and P2, is acquired. In the example shown in Figure 6, point P1 is located at a higher position than point P2.

[0053] The difference in height between point P1 and point P2 is represented as the amount of twist Δh. In the torsion amount calculation process of step S03, the amount of twist Δh is calculated, for example, from the imaging data. In this case, it is preferable to store reference distance data indicating distances corresponding to coordinate values ​​in the imaging data in advance in storage unit 82.

[0054] The twist amount calculation unit 83c acquires the coordinate values ​​of points P1 and P2 from the imaging data. The twist amount calculation unit 83c refers to the reference distance data to determine the difference between the coordinate values ​​in the thickness direction DZ of the slab SB, and determines the twist amount Δh using the reference distance data.

[0055] Figure 7 shows how prediction information is generated in the prediction information generation process of step S05 in Figure 4. The solid line in Figure 7 represents the end face on the base end side in the conveying direction D1 of slab SB1 before width reduction. The dashed line represents the end face on the base end side in the conveying direction D1 of slab SB2 after width reduction.

[0056] When slab SB1 is width-reduced, a frictional force of several hundred tons acts on slab SB2. Therefore, even if slab SB1 is twisted, the thickness center positions P1b and P2b can be considered to move from the center positions P1a and P2a while maintaining their positions in the width direction DX. In other words, the thickness center positions P1b and P2b after width reduction can be considered to be the same positions in the thickness direction DZ as the thickness center positions P1a and P2a before width reduction.

[0057] Here, the angle between the line connecting the central positions P1a (P1b) and P2a (P2b) and the horizontal direction is defined as the twist angle. The twist amount Δh, which is the difference between the central positions P1a (P1b) and P2a (P2b), is equal to the product of the twist angles tanφ1 and tanφ2 before and after width reduction and the widths w1 and w2 of the slab. In other words, these can be expressed mathematically as the following equation (1).

[0058] (Width after width reduction w2) × (Twist angle after width reduction tanφ2) = (Width before width reduction w1) × (Twist angle before width reduction tanφ1) = (Twist amount Δh) (1)

[0059] When the twist angle tanφ2 after width reduction is summarized in this formula (1), it is expressed by the following formula (2).

[0060] (Twist angle tanφ2 after width reduction) = (slab width w1 before width reduction) / (slab width w2 after width reduction) × (twist angle tanφ1 before width reduction) = (twist amount Δh) / (slab width w2 after width reduction) (2)

[0061] The width w2 of the slab after width reduction can be determined using the value of the operating conditions. The twist amount Δh before width reduction can be measured as described above. That is, the twist angle tanφ2 after width reduction can be calculated using equation (2) if the twist amount Δh and the width w2 of the slab after width reduction can be obtained. The prediction information generator 83e generates, for example, the twist angle tanφ2 after width reduction as prediction information.

[0062] For example, when the helix angle tanφ2 after width reduction generated by the prediction information generating unit 83e is equal to or less than the value of reference data, the suitability information generating unit 83f generates suitability information indicating that the slab is suitable for width reduction. Also, when the helix angle tanφ2 after width reduction exceeds the value of reference data, the suitability information generating unit 83f generates suitability information indicating that the slab is not suitable for width reduction. Note that the value of the helix angle tanφ2 after width reduction used in the reference data can be the minimum angle or average value of the twist angles of slabs previously removed from the hot rolling line.

[0063] Here, the present inventors have found that the cause of the slab SB stopping its progress in the side guides of the roughing rolling section 40 is due to the twisting of the slab SB when it is width-reduced. That is, the present inventors have found that if the slab SB is width-reduced while it is twisted, the required width reduction amount cannot be obtained and the slab is discharged from the width-reducing section 20 in a state wider than the predetermined width.

[0064] As described above, the method for predicting the suitability of slab rolling of the present invention includes a prediction information generating step of generating prediction information predicting the degree of twist of a slab when width reduced, based on reference data serving as a reference for the degree of twist of the slab and position information of multiple points on the slab. The method for predicting the suitability of slab rolling also includes a suitability information generating step of generating suitability information regarding the suitability of slab rolling based on the generated prediction information. Therefore, it is possible to predict the suitability of rolling a slab before width reduction of the slab. That is, a slab before width reduction can be loaded into a heating furnace simply by changing the slab transport direction by the transport device toward the heating furnace. Therefore, since the slab can be transported to the heating furnace without being removed from the production line, the transport time can be significantly reduced compared to transporting a slab to the heating furnace after width reduction. This significantly reduces the downtime of the production line and improves the production efficiency of steel sheets.

[0065] In the above embodiment, points P1 and P2 are defined as midpoints in the thickness direction DZ. However, points P1 and P2 are not limited to this, and can be set at any position as long as they are parallel to the upper or lower side. Furthermore, the number of points is not limited to two, points P1 and P2, and similar processing can be performed on multiple points.

[0066] (Variation 1) In the above-described embodiment, an example has been described in which a camera is used as the measurement unit 30. The measurement unit is not limited to a camera as long as it can measure the shape of the slab SB, and for example, a distance measuring device or the like may also be used. Note that the same components as those in the above-described embodiment are given the same reference numerals and their description will be omitted.

[0067] Fig. 8 shows the arrangement of the measurement units according to a modified example. As shown in Fig. 8, a pair of measurement units 31 are provided in the left and right directions when viewed from the conveying direction D1. The measurement units 31 are also provided facing each other. In other words, the measurement units 31 are provided so as to be able to measure the shapes of one side surface and the other side surface of the slab SB.

[0068] The measurement unit 31 is not particularly limited, but a distance measuring device such as LiDAR (Light Detection and Ranging) can be used. The measurement unit 31 can determine, for example, a point P1 as the midpoint in the thickness direction DZ of one side surface, i.e., the center position of the plate thickness. The measurement unit 31 can also determine, for example, a point P2 as the midpoint in the thickness direction DZ of the other side surface, i.e., the center position of the plate thickness.

[0069] Using the measurement unit 31 configured in this manner, prediction information can be generated, as in the above-described embodiment. Furthermore, suitability information regarding the suitability of rolling a slab can be generated based on the generated prediction information. Therefore, it is possible to predict the suitability of rolling a slab before width reduction is applied to the slab. This makes it possible to improve the production efficiency of steel sheets.

[0070] (Variation 2) In the above embodiment, an example has been described in which suitability information is generated based on the twist angle tanφ2 of the slab after width reduction and the value of the reference data. However, the generation of suitability information is not limited to this manner, and may be performed, for example, based on the positional relationship of points P1 and P2 with respect to the reference data.

[0071] Figure 9 shows the relationship between the positional information of multiple points on the slab and the reference data, i.e., the positional relationship of points P1 and P2 with respect to the reference data. The reference data shown in Figure 9 is a reference line L1 that serves as a reference for the degree of twist of the slab. The reference line L1 is a line that corresponds to the twist angle tanφ3 of the slab SB.

[0072] The suitability information generating unit 83f, for example, aligns the reference line L1 so that it is located on point P1, and generates suitability information according to the position of point P2. For example, if point P2 is located above the reference line L1, the twist angle connecting points P1 and P2 will be gentler than that of the reference line L1. In this case, the amount of twist of the slab SB after width reduction is expected to be below the standard, so the suitability information generating unit 83f generates suitability information indicating that the slab is suitable for width reduction.

[0073] Furthermore, for example, when point P2 is located below the reference line L1, the twist angle is larger than that of the reference line L1. In this case, since the amount of twist after width reduction is expected to exceed the standard, the suitability information generating unit 83f generates suitability information indicating that the slab is not suitable for width reduction.

[0074] By generating suitability information in this manner, it is possible to predict the suitability of rolling a slab before width reduction is applied to the slab, thereby improving the production efficiency of steel sheets. [Example]

[0075] A steel plate was manufactured using the steel plate manufacturing apparatus 100 described in the above embodiment. A CCD camera was used as the measurement unit 30.

[0076] The slabs used were Al-killed low-carbon steel slabs measuring 7000 to 8000 mm in length, 260 mm in thickness, and 1200 to 1800 mm in width. The widths are the dimensions before width reduction. The slab heating temperature was 1100 to 1200°C. The width reduction of the slabs was 250 to 350 mm. 1000 slabs were produced for each level. The width reduction (ΔW), slab width before width reduction (W1), slab width after width reduction (W2), and width reduction rate (γ) were obtained from the set values. 1000 slabs were width reduced, and the number of slabs removed from the production line was counted. The results are shown in Table 1.

[0077] As a comparative example, steel plates were produced by a conventional method without checking whether the slabs had any twists before width reduction. Width reduction was performed on 1,000 slabs, and the number of slabs removed from the production line was counted. The results are shown in Table 1.

[0078] As shown in Table 1, in the inventive example, 15 of the 1,000 slabs were judged to have twists exceeding the threshold value and were recharged into the heating furnace. After recharging, the width reduction was completed without twisting. In the comparative example, the twists in 15 of the 1,000 slabs increased, resulting in slab removal at the outlet of the width reduction section.

[0079] [Table 1]

[0080] When the work of removing slabs from the hot rolling line is performed, the line is stopped during this work. Therefore, it is desirable to reduce the number of slabs that need to be removed from the hot rolling line. In the example of the present invention, the amount of slab twist during width reduction can be predicted before the width reduction is performed. Therefore, in the example of the present invention, the number of slabs removed from the hot rolling line could be reduced compared to the comparative example. Therefore, the hot rolling line could operate stably. [Explanation of symbols]

[0081] 100 Steel plate manufacturing equipment 10 Furnace 20 Lower part of width pressure 30 Measurement section 31 Measurement section 40 Rough rolling section 50 Finishing Rolling Section 60 Runout Table 83a Reference data acquisition section 83b Location information acquisition unit 83e Prediction information generation unit 83f Suitability information generation unit

Claims

1. A method for predicting whether a slab is suitable for rolling when the slab is width-reduced, comprising: a reference data acquisition step of acquiring reference data serving as a reference for the degree of twist of the slab before the width reduction is performed; a position information acquisition step of acquiring position information of the slab at a plurality of points parallel to the upper or lower edge formed along the width direction of the slab before the width reduction; a prediction information generating step of generating prediction information that predicts the degree of twist of the slab when the width is reduced based on the reference data and the position information of a plurality of points; and a suitability information generating step of generating suitability information regarding the suitability of rolling the slab based on the prediction information.

2. a torsion amount calculation step of calculating a torsion amount of the slab based on the position information of a plurality of points; A shape information acquisition step of acquiring shape information of the slab including the length of the slab in the width direction, 2. The method for predicting the suitability of rolling a slab according to claim 1, wherein in the prediction information generation step, the prediction information is generated based on the calculated amount of twist of the slab, the shape information of the slab, and the reference data.

3. 3. The method for predicting whether a slab is rolled according to claim 1 or 2, wherein in the position information acquisition step, the position information of a plurality of points measured while the slab is pressed from above and below is acquired.

4. A steel plate manufacturing method in which a steel plate is manufactured using the method for predicting the suitability of slab rolling according to claim 1 or 2, a width reduction step of performing the width reduction on the slab from which the target slab for the width reduction has been selected in a manner according to the suitability information; a rolling step of rolling the slab that has been subjected to the width reduction.

5. A steel plate manufacturing method in which a steel plate is manufactured using the method for predicting the suitability of slab rolling according to claim 3, a width reduction step of performing the width reduction on the slab from which the target slab for the width reduction has been selected in a manner according to the suitability information; a rolling step of rolling the slab that has been subjected to the width reduction.

6. A slab rolling suitability prediction device that predicts whether a slab is rolled properly when the slab is reduced in width, a reference data acquisition unit that acquires reference data that is a reference for the degree of twist of the slab before the width reduction is performed; a position information acquisition unit that acquires position information of the slab at multiple points parallel to the upper or lower edge formed along the width direction of the slab before the width reduction is performed; a prediction information generating unit that generates prediction information that predicts the degree of twist of the slab when the width is reduced based on the reference data and the position information of a plurality of points; and a suitability information generating unit that generates suitability information regarding the suitability of rolling the slab based on the prediction information.

7. A steel plate manufacturing apparatus for manufacturing steel plates, The slab rolling suitability prediction device according to claim 6; a width reducing section that performs width reduction on the slab from which the target slab for width reduction has been selected in a manner according to the prediction information; a rolling section that rolls the slab that has been subjected to the width reduction.

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