JP6330734B2 - Steel plate cutting position setting device and steel plate manufacturing method - Google Patents

Description

  The present invention relates to a steel plate cutting position setting device and a steel plate manufacturing method for setting a cutting position of a crop portion formed at a leading end portion or a trailing end portion in a conveying direction of a steel plate by rough rolling, and in particular, a thick and wide hot It is suitable for rolled steel sheets.

  In general, on the entry side of the finishing mill on the hot rolled steel sheet production line, in order to stabilize the steel sheet transport (also referred to as the threading plate) during the finish rolling, the steel sheet (intermediate material) transport direction tip and the transport in rough rolling. Cut the crop formed at the rear end of the direction. The cropped part is an unsteady deformed part and is discarded. The shape of the cropped part is roughly divided into two types, a tongue shape and a fishtail shape. As for the tongue shape, the width direction center part protrudes in the conveyance direction with respect to the width direction both ends of a steel plate. In the fishtail shape, both end portions in the width direction protrude in the transport direction with respect to the center portion in the width direction of the steel plate. The planar shape of the cropped part may be asymmetric on both sides in the width direction with respect to the center line in the width direction of the steel sheet. In this way, when a steel plate in which the asymmetric crop portion in the width direction is formed at the front end portion or the rear end portion in the steel plate conveyance direction is passed through the finishing mill, an uneven load in the steel plate width direction may occur on the finishing roll. As a result, the steel sheet may meander during finish rolling.

  Moreover, in the front-end | tip part of the conveyance direction of a steel plate, since a heat is radiated from four surfaces, a conveyance direction most front surface, a width direction end surface, an upper surface, and a lower surface, temperature fall is large, and temperature is low compared with a stationary part. This low temperature steel sheet conveyance direction front end portion has a large deformation resistance, which causes a biting failure in the finishing mill. Further, at the rear end portion in the conveyance direction of the steel plate, the temperature is greatly reduced because heat is radiated from the four surfaces of the rear end surface in the conveyance direction, the end surface in the width direction, the upper surface, and the lower surface, and the temperature is lower than that in the steady portion. The rear end portion in the steel plate conveying direction at a low temperature also has a large deformation resistance, and the steel plate is easily drawn during finish rolling. As described above, after the rough rolling is finished, before the finish rolling, the front end portion of the steel sheet in the conveyance direction and the crop portion at the rear end portion in the conveyance direction are cut. The crop part is cut by a crop cutting machine (also referred to as a crop shear). By cutting the front end portion of the steel sheet in the conveyance direction and the cropped portion at the rear end portion in the conveyance direction, effects such as prevention of meandering of the steel sheet, suppression of biting of the steel sheet, and prevention of drawing of the steel sheet can be obtained.

  By the way, in cutting | disconnection of the crop part of the conveyance direction front-end | tip part and conveyance direction rear end part of a steel plate, a cutting load changes greatly with the kind of hot-rolled steel plate manufactured. In recent years, steel plates for line pipe materials, for which demand has been increasing, are also manufactured on a hot-rolled steel plate production line. In the production of the hot-rolled steel sheet for line pipe material, the cutting load of the crop cutting machine in cutting the crop part at the front end part in the steel sheet conveying direction and the rear end part in the conveying direction is larger than that in the conventional general hot-rolled steel sheet production. It is much larger. Line pipe materials are required to have high strength and extremely thick specifications from the viewpoint of high-efficiency transportation of crude oil and natural gas. In addition, since pipelines are sometimes laid in an earthquake zone, line pipe materials are also required to have high toughness. For this reason, when manufacturing the hot-rolled steel sheet for line pipe materials on a hot-rolled steel sheet production line, there are the following points to be noted.

  The first is the thickness of the steel sheet. In the case of a conventional hot-rolled steel sheet having a thickness of about 2 to 4 mm after finish rolling, the thickness of the intermediate material before finish rolling is 30 to 50 mm. On the other hand, in the case of hot-rolled steel sheets for line pipe materials that require high toughness, controlled rolling called TMCP (Thermo-Mechanical Control Process) is performed to refine the crystal structure and ensure the toughness of the steel sheet. In some cases, it is necessary to increase the rolling reduction in finish rolling. The product sheet thickness required for the hot rolled steel sheet for line pipe material is 20 mm or more and 30 mm or less, and in order to obtain the toughness required for the line pipe material, the cumulative rolling reduction in finish rolling is required to be at least 60%. is there. That is, in order to manufacture a hot-rolled steel sheet for a line pipe material having a thickness of 20 mm on a hot-rolled steel sheet production line, a steel sheet having an intermediate thickness of 50 mm or more must be finish-rolled. However, the current hot-rolled steel sheet production line assumes an intermediate material of a general steel sheet with a thickness of 30 to 50 mm, and the upper limit of the cutting load of the crop cutting machine is the same as that of the conventional intermediate material sheet thickness. It has become. Therefore, in order to manufacture a hot-rolled steel sheet for a line pipe material in the current hot-rolled steel sheet production line, a technique for cutting a crop portion of an intermediate material having a thickness of 50 mm or more with an existing crop cutting machine is necessary. .

  The second important point to keep in mind when manufacturing a hot-rolled steel sheet for line pipe material on a hot-rolled steel sheet production line is the sheet width of the steel sheet (intermediate material). The line pipe material may be manufactured as a spiral steel plate. In this case, since it is advantageous in terms of strength to reduce the number of welded portions of the steel pipe as much as possible, a wider hot-rolled steel sheet is required as a pipe material. Generally, the plate width required as a hot-rolled steel plate for line pipe materials is 1200 mm or more and 2100 mm or less, and the crop cutting machine needs to cut the crop portion of the intermediate material having a plate width of 1200 mm or more.

  The third important point to keep in mind when manufacturing a hot-rolled steel sheet for line pipe materials on a hot-rolled steel sheet production line is the temperature of the steel sheet (intermediate material). In order to obtain a hot rolled steel sheet having high toughness, finish rolling must be performed at a temperature in the non-recrystallized region. For this reason, it is necessary to perform finish rolling by setting the sheet thickness center temperature of the steel sheet to 930 ° C. or less from the front end in the transport direction to the rear end in the transport direction. Therefore, the temperature of the crop portion at the cutting position is close to 930 ° C. when cutting the front end portion of the steel plate in the conveyance direction and the rear end portion in the conveyance direction, which is compared with the temperature of a general steel plate (about 1000 ° C.). And it is low. Therefore, the hot-rolled steel sheet for line pipe material (intermediate material) has a higher cutting resistance value than conventional steel sheets, and the cutting load increases.

  In summary, the hot-rolled steel sheet for linepipe material produced in the hot-rolled steel sheet production line has a large thickness, a large sheet width, and a low temperature. A larger cutting load is applied than a typical hot rolled steel sheet. In addition, the specifications of the existing crop cutting machine are designed to match the conventional hot-rolled steel sheet that has been manufactured in the past, and hot rolling for line pipe materials is possible without major modification of the crop cutting machine such as enhancement. In order to manufacture a steel plate, a technique for cutting a steel plate having a plate thickness of 50 mm or more, a plate width of 1200 mm or more and a temperature of 930 ° C. or less is required even in the specifications of the existing crop cutting machine.

  Various techniques have been proposed for cutting the front end of the steel sheet in the finish rolling mill and the crop section at the rear end in the transport direction from the viewpoint of reducing the sheet feedability and yield loss in the finish mill. . For example, in Patent Document 1 below, after predicting the shape of the cropped portion after finish rolling from the shape of the cropped portion at the front end portion in the transport direction and the rear end portion in the transport direction of the steel plate (intermediate material), and evaluating the appearance as a product A method has been proposed in which whether or not the cropped part is cut is determined and the cutting length is automatically adjusted. In this method, rolling can be performed without cutting the front end portion of the steel sheet in the conveyance direction and the crop portion at the rear end portion in the conveyance direction, or the yield can be improved because a minimum cutting length is required even when cutting. Further, for example, in Patent Document 2 below, after measuring the shape of the cropped portion of the steel sheet (intermediate material) before cutting in the conveyance direction front end portion and the conveyance direction rear end portion with a shape meter, the finish rolling machine bites from the measured shape. A method has been proposed in which an optimum cutting length is determined in consideration of defects and quality / yield, and the cropped portion is cut with the cutting length. This method improves the quality and the yield as well as reducing the troubles of the plate passing.

JP-A-62-173115 Japanese Patent Laid-Open No. 7-9245

  In the crop cutting method described in Patent Document 1, since finish rolling may be performed without cutting the crop part, in this case, it is hot without being restricted by the upper limit of the cutting load of the crop cutting machine. A rolled steel sheet can be manufactured. However, the presence or absence of crop cutting depends on the shape of the crop portion at the front end of the steel plate (intermediate material) and the rear end of the transport direction, so finish rolling without cutting all the steel plate (intermediate material) crop portions. It cannot be threaded. Also, when cutting a fishtail-shaped crop part, a steel plate having a large plate thickness, a large plate width, and a low temperature, such as a hot-rolled steel plate for a line pipe material, cannot be cut due to insufficient capacity of the crop cutting machine. Occur.

Further, in the crop cutting method described in Patent Document 2, although the rolling yield and sheet passability are taken into consideration, a steel plate having a large plate thickness, a large plate width, and a low temperature, for example, heat for a line pipe material. In the case of cold-rolled steel sheets, there are situations where cutting is impossible due to insufficient capacity of the clock cutter.
The present invention has been made paying attention to the above-mentioned problems, and is a major equipment modification such as enhancement of a crop cutting machine even if the steel sheet has a large plate thickness, a large plate width, and a low temperature. It aims at providing the steel plate cutting position setting apparatus and steel plate manufacturing method which can cut | disconnect a steel plate stably, without performing.

  In order to solve the above-described problems, according to one aspect of the present invention, a crop portion having a fishtail shape and formed at a leading end portion or a trailing end portion in a conveying direction of a steel plate by rough rolling is subjected to finish rolling. A steel plate cutting position setting device for setting the cutting position of the crop portion with an arithmetic processing device having an arithmetic processing function when cutting with a crop cutting machine before, the shape of the crop portion detected by the crop shape meter Crop section shape reading section that reads the image, a crop section cutting area calculation section that calculates the cutting area of the crop section by the crop cutter from the read shape of the crop section at every specified interval in the steel sheet conveyance direction, and a steel plate thermometer A crop for calculating the cutting load of the crop part from the product value of the shear resistance estimated from the temperature and processing strain rate of the obtained steel sheet and the calculated cutting area of the crop part. Steel sheet cutting position comprising: a cutting force calculation part for cutting and a cutting part cutting position setting part for setting the cutting position of the crop part so that the calculated cutting load of the crop part is not more than the cutting load upper limit value of the crop cutting machine A setting device is provided.

  Moreover, according to another aspect of the present invention, width reduction is performed using a sizing press or a width rolling mill in order to make the shape of the crop portion at the front end portion in the conveyance direction or the rear end portion in the conveyance direction of the steel plate into a fishtail shape. A steel sheet manufacturing method is provided.

  According to the present invention, even a steel plate having a large plate thickness, a large plate width, and a low temperature can be prevented from being cut due to insufficient capacity of the crop cutting machine. In addition, the steel sheet can be stably cut without major equipment modification such as enhancement of a crop cutting machine.

It is a schematic block diagram which shows one Embodiment of the hot rolling equipment with which the steel plate cutting position setting apparatus and steel plate manufacturing method of this invention were applied. It is a block diagram of the arithmetic processing part constructed | assembled with the software in the arithmetic processing apparatus of FIG. It is explanatory drawing of the crop part formed in the conveyance direction front-end | tip part or conveyance direction rear end part of a steel plate. It is explanatory drawing of the temperature distribution to the steel plate conveyance direction in the crop part of a fish tail shape. It is explanatory drawing of the crop part of a fishtail shape. It is a front view of the blade of a crop cutting machine. It is explanatory drawing of the contact-like body of the blade of the crop cutting machine with the largest crop part cutting load. It is explanatory drawing of crop part cutting area calculation. It is explanatory drawing of crop part cutting area calculation. It is a schematic block diagram of a crop cutting machine. It is explanatory drawing of the axial torque of the crop cutting machine of FIG. It is a schematic diagram of the steel plate cutting state by the blade of a crop cutting machine. It is explanatory drawing of the calculated value of a crop part cutting load, and a track record value. It is explanatory drawing of the calculated value of a crop part cutting load, and a track record value. It is a flowchart of the arithmetic processing performed in the crop part cutting position setting part of FIG. It is explanatory drawing of the effect | action of the arithmetic processing of FIG. It is explanatory drawing of the effect of the arithmetic processing of FIG.

  The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, arrangement, etc. of components. Is not specified as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

  Hereinafter, a steel sheet cutting position setting device and a steel sheet manufacturing method according to embodiments of the present invention will be described with reference to the drawings. The steel plate cutting position setting device and the steel plate manufacturing method of this embodiment are used in, for example, a hot rolling facility exemplified in FIG. The hot rolling facility illustrated in FIG. 1 is a hot rolled steel sheet production line, and the steel sheet S is conveyed from the left to the right in the drawing (through plate) in principle, except when it is reciprocally rolled by a rolling mill. Is done. In this hot rolling facility, a steel plate (slab) heated in a heating furnace (not shown) is subjected to width reduction by a width rolling machine (not shown) and rough rolled in a rough rolling process. The width rolling mill rolls the steel sheet in the width direction, that is, in the direction perpendicular to the conveyance direction and in the horizontal direction. Further, in the rough rolling process, a single or a plurality of rough rolling mills 2 are arranged, and the steel plate (slab) is rolled to a steel plate (intermediate material) S having a specified thickness according to a preset rolling schedule. Only the final roughing mill 2 is shown in the figure. The rough rolling machine 2 may perform reciprocating rolling. In addition, when a plurality of rough rolling mills 2 are arranged in the steel sheet conveyance direction, the number of reciprocating rolling operations can be reduced. A sizing press can be used instead of the width rolling mill.

A finishing mill 3 that performs finish rolling of the steel sheet S is disposed on the downstream side of the roughing mill 2 in the direction of conveying the steel sheet. A plurality of finish rolling mills 3 are arranged in the steel plate conveying direction, and each finish rolling mill 3 finish-rolls the steel sheet S to a predetermined thickness according to a preset rolling schedule. A crop cutting machine (crop) for cutting the front end portion of the steel sheet S in the transport direction and the rear end portion in the transport direction of the steel sheet S on the upstream side in the steel plate transport direction of the finish rolling mill 3 and the downstream side in the steel plate transport direction of the rough rolling mill 2. 4) is arranged. Crop cutting machine 4 of this embodiment, as described later, the steel sheet on the blade C _U and the lower blade C _L of the crankshaft disposed above and below the steel plate conveyance line synchronously rotated is attached to the crank shaft S The crop portion is cut. As described above, the front end portion and the rear end portion in the transport direction of the roughly rolled steel sheet S are rapidly cooled and hardened. If the steel sheet S is passed through the finish mill 3 as it is, A biting failure or the occurrence of drawing of the steel sheet S occurs. Then, the crop part of the steel plate conveyance direction front-end | tip part and conveyance direction rear end part is cut | disconnected by the crop cutting machine 4. FIG. The finishing mill 3 is referred to as a first finishing rolling mill, a second finishing rolling mill, ... from the upstream side in the steel sheet conveying direction.

  A measuring roll 5 is disposed on the upstream side in the steel plate conveyance direction with the crop cutting machine 4 interposed therebetween, and a table roll 6 is disposed on the downstream side in the steel plate conveyance direction. A rotation sensor 7 for detecting the rotation state 6 is connected. Further, between the measuring roll 5 and the crop cutting machine 4, a leading end sensor 8 that detects the leading end portion and the trailing end portion in the conveying direction of the steel sheet S is also disposed. The leading edge sensor 8 detects a passing state of the steel sheet S by detecting, for example, gamma rays irradiated from a radiation source, and is turned on when, for example, passing in the front end portion in the carrying direction and turned off when passing through the rear end portion in the carrying direction. A signal is output. The leading edge sensor 8 is disposed at the center in the width direction of the steel sheet S. The output of the leading edge sensor 8 and the output of the rotation sensor 7 are read into an arithmetic processing device 9 having a high arithmetic processing capability such as a process computer, for example, and the steel sheet S passes through the measuring roll 5, for example. The length of the steel plate S at the rear end portion in the steel plate conveyance direction is detected by passing the steel plate S through the front end portion of the steel plate conveyance direction and the table roll 6. Further, the steel plate S is tracked using the output of the rotation sensor 7 from the time when the leading end sensor 8 detects the leading end portion of the steel plate S in the conveying direction. The set position of the crop portion at the rear end is cut by the crop cutting machine 4.

  Between the roughing mill 2 and the measuring roll 5, a crop shape meter 10 that detects the shape of the crop portion at the front end portion in the transport direction and the rear end portion in the transport direction of the steel plate S and a steel plate thermometer that detects the temperature of the steel plate S. 11 is arranged. The crop shape meter 10 includes a lower light source 10a that is provided below the conveying line of the steel plate S and emits light upward, and a plurality of cameras 10b that images the shape of the steel plate S above the light source 10a. The cropped part projected in the above is imaged by the camera (digital camera) 10b, and the shape of the cropped part is detected from the image. Therefore, the crop shape meter 10 can detect not only the shape of the cropped portion but also the edges at both ends in the width direction of the steel sheet S. However, although the crop shape meter 10 can detect the shape of the crop portion, it cannot determine whether the shape of the crop portion is, for example, a tongue shape or a fish tail shape, and the determination will be described later. This is performed by the crop shape detection unit. As the steel plate thermometer 11, a radiation thermometer having a central portion in the steel plate width direction as a visual field, a radiation thermometer for measuring a temperature distribution in the steel plate width direction, or the like is used. And the output of the crop shape meter 10 and the output of the steel plate thermometer 11 are read into the arithmetic processing unit 9, and the cutting position of the crop portion is set according to the arithmetic processing described later.

  The arithmetic processing unit 9 performs a wide range and high speed of overall control for monitoring and managing the entire process of the hot rolling process. These controls are performed according to arithmetic processing executed in the arithmetic processing unit 9 comprising a computer system, that is, software. Therefore, the arithmetic processing device 9 includes a storage device, a display device, an input / output device and the like (not shown) in addition to the arithmetic processing unit constructed by software. The arithmetic processing unit 9 has various arithmetic processing units constructed by software, and has a finish rolling setup calculation unit 12 and a crop part cutting position setting unit 13 as a part thereof, and the crop part cutting position. A crop part shape detection unit 14 is constructed in the setting unit 13. The finish rolling setup calculation unit 12 sets rolling conditions for each finish rolling mill 3 in finish rolling. The crop part cutting position setting unit 13 sets the cutting position of the crop part by the crop cutting machine, as will be described in detail later. The crop portion shape detection unit 14 detects (determines) the shape of the crop portion from the output of the crop shape meter 10, and a specific shape detection method will be described later.

The finish rolling setup calculation unit 12 is performed in an existing hot finish rolling process, and is performed to set rolling conditions such as a roll gap and a roll rotation speed of each finishing mill 3. Specifically, based on the rolling specifications such as the thickness of the steel plate (intermediate material), the target plate thickness of the product, the plate width, the steel type, the finish rolling entry temperature, the target steel plate temperature at each finishing mill 3 Next, the roll rotation speed of each finishing rolling mill is calculated from the target steel plate thickness in each finishing rolling mill 3 according to the draft schedule and the specified steel plate transport speed on the final finishing rolling mill 3, and then the temperature drop of the steel sheet is calculated. Predicting and calculating the steel plate temperature in each finishing mill. The deformation resistance km of the steel sheet is a resistance force when the steel sheet is deformed, that is, a force necessary for the deformation, and is affected by processing strain, processing strain rate, and temperature. The processing strain is calculated from the entry side plate thickness and the exit side plate thickness. The processing strain rate is calculated as a value obtained by dividing the processing strain by the time during which the processing strain is applied by the contact between the steel plate as the workpiece and the roll. Knowing the working strain, working strain rate and steel plate temperature, the deformation resistance km of the steel sheet according to the steel type can be estimated, so this deformation resistance km and the inlet side plate thickness h ₀ , the outgoing side plate thickness h _{1 of} each finishing mill 3, roll The rolling load P _P of each finishing mill 3 is calculated from the radius R _R , the sheet width W, and the rolling force function Q _P according to the following formula 1, and the rolling conditions of each finishing mill 3 are determined. Note that L in the formula is the roll contact arc length of the steel sheet S. Also, the rolling force function Q _P, represents the pressure distribution of the steel sheet contact area of the roll, for example, solutions of Sims, Iron and Steel Institute of Japan, as shown in such actual p.36 (2.202) equation theoretical plate rolling It can be estimated by various rolling theory models.

The deformation resistance km of steel in finish rolling is the yield stress under plane strain conditions, and is determined for each steel type (hardness) and depends on the temperature and strain rate. Generally, the higher the strain rate, the lower the temperature. The deformation resistance km of steel is large. In the finish rolling setup calculation, in order to accurately calculate the rolling conditions at the front end of the steel sheet conveyance direction, the steel plate temperature at the front end of the steel sheet conveyance direction is measured by the steel sheet thermometer 11 at the finish rolling entry side, and the steel plate temperature and roll speed are measured. more calculated by strain rate (working strain rate) on each finishing mill 3 of the steel sheet temperature based estimates the deformation resistance km and the rolling load P _P. Furthermore, in order to improve the accuracy of the finish rolling setup calculation, various learning controls such as learning calculation of the deformation resistance km so that the actual rolling load during rolling coincides with the calculated rolling load are also applied. Therefore, the finish rolling setup calculation unit 12 estimates the deformation resistance km with relatively high accuracy. The deformation resistance km has a linear relationship with the shear resistance τ in the crop cutting machine 4 as will be described later.

  In the hot rolled steel sheet production line of this embodiment, in addition to general materials, the above-described hot rolled steel sheet for line pipe material is also produced. Hot-rolled steel sheets for line pipe materials have a larger plate width, larger plate thickness, and lower temperature than general materials, so the cutting load at the front end of the transport direction and the rear end of the transport direction is large, and the existing There is a risk that the upper limit of the cutting load of the crop cutting machine 4 will be exceeded. The crop portions formed at the front end portion and the rear end portion in the transport direction of the steel sheet S are roughly classified into a fishtail shape shown in FIG. 3a and a tongue shape shown in FIG. 3b. In the fishtail shape, both end portions in the width direction of the steel sheet S protrude in the transport direction from the center portion in the width direction. In the tongue shape, the central portion in the width direction of the steel sheet S protrudes in the transport direction from both end portions in the width direction. Since the cutting load of the crop part by the crop cutting machine 4 is considered to be proportional to the cutting area, in this embodiment, the crop part is formed into a fishtail shape, and the crop part is cut at an intermediate position. In order to make the crop portion into a fishtail shape, the width of the steel sheet S is reduced by a width rolling mill or a sizing press prior to rough rolling, and the thickness of both ends in the width direction of the steel sheet S is changed to the thickness of the central portion in the width direction. Larger than that. In addition, the intermediate position of the fishtail-shaped crop part indicates between the fishtail-shaped concave bottom and the convex tip.

  First, the crop part cutting position set by the specification of the hot-rolled steel sheet for line pipe material will be described. FIG. 4 shows, for example, the fishtail shape of the crop portion of the hot-rolled steel sheet for line pipe material at the position of the crop cutting machine 4 and the maximum temperature distribution in the steel plate conveyance direction of the crop section. After heating, the roughly rolled steel sheet S has a lower temperature at the tip of the convex portion of the fishtail-shaped crop part, and is harder accordingly. On the other hand, although the maximum temperature is high at the position corresponding to the concave bottom of the fishtail-shaped crop portion, the amount of heat released from the concave bottom itself of the crop portion is also large and hard. In addition, since the cut area at the bottom of the recess of the fishtail-shaped crop part is large, in the hot-rolled steel sheet for line pipe material, a preset length from the bottom of the recess of the crop part to the top of the convex part For example, an area of 20 mm has a high possibility of exceeding the upper limit of the cutting load of the crop cutting machine 4, and is inappropriate as a crop portion cutting position. The steel plate cutting position regulation amount set by the specifications of the hot-rolled steel sheet for line pipe material is defined as the crop portion shape regulation amount.

  Next, the crop part cutting position set by the specifications of the existing hot rolled steel sheet production line will be described. When the crop part 4 is cut by the crop cutting machine 4, the error between the target cutting position and the actual cutting position depends on the tracking accuracy of the steel sheet S. The tracking accuracy of the steel sheet S is determined by the specifications of the existing hot-rolled steel sheet production line, and the target cutting position is set to the recess bottom of the fishtail-shaped crop portion by the cutting position error due to the tracking accuracy. Unless it is set inside the intermediate position between the tips of the convex portions, it cannot be cut at the intermediate position of the fishtail-shaped cropped portion. Therefore, in this embodiment, the cutting position error length due to tracking accuracy, that is, a preset steel plate conveyance direction from the tip of the convex portion of the fishtail-shaped crop portion of the hot-rolled steel plate for line pipe material to the bottom of the concave portion. A length, for example, a position of 90 mm is set as the convex side cutting position. Further, in addition to the above-mentioned crop portion shape regulation amount (= 20 mm) from the bottom of the concave portion of the fish tail-shaped crop portion of the hot-rolled steel sheet for line pipe material to the tip of the convex portion, the cutting position error length due to tracking accuracy (= 90 mm), that is, a length in the steel sheet conveyance direction set in advance, for example, a position of 110 mm is set as the recess-side cutting position. A portion between the concave side cutting position and the convex side cutting position is mechanically set as a cutting portion of the crop portion. In this embodiment, of the two convex portions in the fishtail-shaped crop portion, the length from the concave bottom to the convex tip is 200 mm or more on the small length side from the concave bottom to the convex tip. Desirably, it is 300 mm or less.

On the other hand, if the shear resistance τ of the steel sheet can be calculated from the deformation resistance km estimated in the finish rolling setup calculation described above, the shear resistance τ is multiplied by the cutting area A of the crop part by the crop cutting machine 4. The cutting resistance P can be calculated. The cutting area A of the crop part by the crop cutting machine 4 will be described in detail later. However, if the calculated cutting load P of the crop part exceeds the cutting load upper limit value P _MAX of the crop cutting machine 4, it is substantially present. The crop cutting machine 4 cannot cut the crop part, or the equipment is overloaded. Therefore, between the concave side cutting position and the convex side cutting position, the crop cutting load P, which is obtained by multiplying the shear resistance τ by the cutting area A of the cropping part, is equal to or lower than the cutting load upper limit P _{MAX of the} crop cutting machine 4. Readjust the crop section cutting range set to. Specifically, the concave side cutting position where the crop part cutting load P is increased is corrected in the convex part direction of the crop part.

  Next, the fishtail shape and the bottom of the concave portion and the tip of the convex portion of the fishtail-shaped crop portion detected by the crop portion shape detection unit 14 will be described. The two convex portions of the fishtail-shaped crop portion formed at the front end portion in the transport direction and the rear end portion in the transport direction of the steel sheet S are not necessarily equal. Rather, the two convex portions of the fishtail-shaped crop portion are often not equal. In some cases, the cropped portion has a tongue shape. Therefore, as shown in FIG. 5, among the shapes of the steel sheet S detected by the crop shape meter 10, the edges at both ends in the width direction of the steel sheet S are detected from the longitudinal center part of the steel sheet S, that is, the transport direction center part. The point V immediately after the number of edges becomes 3 is defined as the bottom of the recess. Next, the areas A1 and A2 of the convex portions on both sides of the concave bottom V detected by the crop shape meter 10 are calculated, and the distances L1 and L2 between the tips of the convex portions and the concave bottom are calculated. In this calculation process, when the number of edges does not become three and there is no concave bottom, the ratio of the area A1 of the large area to the area A2 of the small area of the two areas is previously determined. If the distance is greater than the set specified value, and the distances L1 and L2 between the protrusion tips of the two protrusions and the bottom of the recess are both equal to or less than the specified value, the cropped portion has a tongue shape (or fish) It is not a tail shape). On the other hand, since it is determined that the crop portion has a fishtail shape in cases other than these, the tip of the convex portion having a small area is set as the convex portion tip. This is because, when setting the cutting position of the crop part to be described later, if the tip of the convex part having a large area is used as the convex part tip, the convex part having a small area may not be cut.

Next, a method for calculating the cutting area of the crop portion by the crop cutting machine 4 will be described. Figure 6 is a front view of a blade C _U and the lower blade C _L on the crop cutter 4 for cutting across the steel plate and lower blades on which are arranged above and below the steel plate conveyance line. As apparent from the drawing, the blade C _U and the lower blade C _L on the crop cutting machine 4, when viewed edge from the front, that is, when viewed from the steel plate conveyance direction, so that warp direction edge dents Is given a rake angle called knife rake. When the radius R constant depressions blade front shape of the Naifureki, such blades of steel cutting load is maximized by the convex upper blade C _U and the lower blade C _L is cropping portion as shown in FIG. 7 When the cutting area A indicated by hatching in the figure at this time is to be cut by contacting the inner corner of the steel plate in the width direction of the steel sheet, the maximum cutting load is obtained by multiplying the cutting area A by the shear resistance τ. P is obtained. As for this cutting area A, for example, the outer maximum cutting width (hereinafter also referred to as cutting width) at the cutting position of the convex portion of the cropped portion is W ₁ , and the inner maximum non-cutting width (hereinafter also referred to as non-cutting width) is W _2. as the center line L _C in the width direction center line and the upper edge C _U and the lower blade C _L of the steel sheet S are the same, the upper blade C _U and the lower blade C _L upper blade from a center line L _C of C _U The calculation method differs depending on whether the distance X _C to the meshing point p of the lower blade C _L is less than or equal to half the cutting width W _1/2 .

Figure 8 is the cutting position of the crop portions, the distance X _C from the center line L _C of the upper blade C _U and the lower blade C _L until engagement point p of the upper blade C _U and the lower blade C _L half value of the cutting width W _1/2 indicates a case where less, 9, the distance X _C from the center line L _C of the upper blade C _U and the lower blade C _L until engagement point p of the upper blade C _U and the lower blade C _L is disconnected The case where the half value W _{1/2 of the} width is exceeded is shown. In either case, the distance Y _C from the center of the recess radius R of the upper blade C _U of Naifureki to the center line of the plate thickness t of the steel sheet S, for ^{_{example, Y C = (R 2 -}} (W 2/2) 2) It is given by ¹ / 2-t / 2. Further, R ² = X _C ² + Y _C ² is established for a line segment connecting the meshing point P of the upper blade C _U and the lower blade C _L and the center of the dent radius R of the knife rake and the distance Y _C and the distance X _C. since ^{_{that, Y C = (R 2 -}} (W 2/2) 2) by substituting _{^{1/2 -t / 2, X C =}} (R 2 - ((R 2 - (W 2/2) 2) ^1/2 -t / 2) ² ) ^1/2 is established.

For clearing the area in FIG. 8, the steel plate widthwise outermost positions of the upper blade C _U in the cutting area coincides with the engagement point p of the upper blade C _U and the lower blade C _L, the upper blade C _U and the lower blade when a line segment and upper blades C _U and angle formed with the center line L _C of the lower blade C _L connecting the center of the C _L of the meshing point p and the upper blade C _U recess radius R of Naifureki of the theta _1, θ ₁ is expressed by the following two equations. Further, the steel plate width direction innermost position of the upper blade C _U in the cutting area is the intersection of the upper blade C _U and the non-cutting width W _2, and the center of the recess radius R of Naifureki of this intersection and the upper blade C _U when the angle formed with the center line L _C of the segment and the upper blade C _U and lower blade C _L was theta ₂ connecting, theta ₂ is appears by the following three equations. As a result, the cut area A in FIG. 8 is geometrically expressed by the following four equations.

On the other hand, when the cutting area of FIG. 9, the steel plate widthwise outermost positions of the upper blade C _U in the cutting area is the intersection of the upper blade C _U and the cutting width W _1, the Naifureki of this intersection and the upper blade C _U when the angle between the center line L _C of the segment and the upper blade C _U and the lower blade C _L connecting the center of the recess radius R and θ _1, θ ₁ is manifested by the following equation 5. Further, the steel plate width direction innermost position of the upper blade C _U in the cutting area is the intersection of the upper blade C _U and the non-cutting width W _2, and the center of the recess radius R of Naifureki of this intersection and the upper blade C _U when the angle formed with the center line L _C of the segment and the upper blade C _U and lower blade C _L was theta ₂ connecting, theta ₂ is manifested by the following equation (6). As a result, the cut area A in FIG. 9 is geometrically expressed by the following seven equations.

  If the cutting area A thus obtained is multiplied by the shear resistance τ, the cutting load P of the crop portion can be obtained. However, in a discrete system such as a computer system, for example, since it is difficult to continuously obtain the cutting area A of the cropped part in the steel plate conveyance direction, the cutting area A is set at predetermined intervals in the steel plate conveyance direction. calculate. If the deformation resistance km in the first finishing mill 3 is obtained, the shear resistance τ is given by τ = km / 2 from plastic mechanics. This calculation formula is established under the following conditions. That is, the shear resistance represents the strength of the material against shearing. In the case of the crop cutting machine 4, when an external force is applied to the material with the upper blade and the lower blade, it is the resistance generated inside the material. When (= referred to as shear resistance) exceeds a certain limit, local fracture occurs at the boundary and the material is cut. The shear resistance is further influenced by cutting conditions (processing conditions) such as temperature and cutting speed (processing strain speed) depending on the hardness of the material, that is, the alloy composition. The cutting speed of the crop cutting machine 4 is generally 50 to 100 m / min. For example, if the thickness of the steel sheet S on the finishing rolling entry side is 60 mm, it will be cut in 40 to 70 msec, which is large in a short time. Distortion is added. When considering the shear resistance from the results of material tests conducted offline, such as a tensile test and a compression test, it is difficult to reproduce the same conditions as the crop cutting machine 4, and at the time of cutting the crop part. It is difficult to obtain data corresponding to shear resistance by testing.

On the other hand, the first finish rolling mill 3 is disposed in the immediate vicinity of 7.5 to 11 m downstream of the crop cutting machine 4 in the steel sheet conveyance direction, and the steel sheet S cut by the crop cutting machine 4 is about 10 seconds later. 1 is conveyed to a finishing mill 3. The rolling time (processing time) of the first finish rolling mill 3, that is, the time for the steel sheet S to bite from the roll entry side and reach the roll exit side is 60 msec (30 to 130 msec) on average, and the cutting time of the crop cutting machine 4 It is equivalent to (processing time). That is, the steel plate processing strain rate of the first finish rolling mill 3 and the steel plate processing strain rate of the crop cutting machine 4 are equivalent. Further, a scale removing device (not shown in FIG. 1) is arranged between the crop cutting machine 4 and the first finish rolling mill 3, and for example, high-pressure water of 150 to 600 kg / mm ² is sprayed onto the surface of the steel plate. The In addition to the steel plate temperature drop by this scale remover, there is also a steel plate temperature drop due to radiation and air cooling during conveyance after cutting the crop part, but under conditions where the plate thickness of the steel plate on the finishing rolling entry side is as large as 60 mm, the steel plate temperature drop The amount is as small as about 10 ° C. on the average section of the steel sheet and about several degrees C. at the center of the cross section. That is, it may be considered that the steel plate temperature of the first finish rolling mill 3 and the steel plate temperature of the crop cutting machine 4 are equivalent.

  Also in rolling, when an external force is applied to the material in the same manner as the crop cutting machine 4, resistance is generated inside the material. Plastic deformation (yield) occurs when this becomes large until a certain limit (yield condition) is satisfied. The stress condition (yield condition formula) for plastic deformation (yield) of the material is given by plastic mechanics using the Mises yield condition formula, for example. A constant representing the yield condition during rolling is expressed here as deformation resistance and Called. As described above, since the steel plate processing strain rate and the steel plate temperature that affect the deformation resistance and shear resistance are the same in the first finishing mill 3 and the crop cutting machine 4, the shear resistance τ corresponding to the steel type is the deformation resistance km. Is given as half the value of.

  Therefore, the steel plate shear resistance τ is calculated from the half value of the steel plate deformation resistance km of the first finish rolling mill 3 estimated by the finish rolling setup calculation, and the crop resistance cutting load P is obtained by multiplying the shear resistance τ by the crop section cutting area A. This calculation formula is established in a static situation. Actually, since the rotation speed of the blade of the crop cutting machine 4 reaches a maximum of 100 m / min, an excessive load than expected is applied due to the impact during the cutting of the crop part. FIG. 10 is a schematic diagram showing a schematic configuration of the crop cutting machine 4. The driving forces of the two motors M are transmitted to the drive shaft 53 in synchronization with a speed reducer 52 to which a flywheel 51 is attached, and are distributed to the upper and lower crankshafts 55 by a speed reducer (not shown) provided in the housing 54. The When the shaft torque T is detected by the strain gauge 56 attached to the drive shaft 53, as shown in FIG. 11, it increases in an impulse shape at time t2 after activation of time t1.

Figure 12 is a representation on a state where the blade C _U and the lower blade C _L is in contact with the upper and lower surfaces of the steel sheet S schematically attached to the crankshaft 55. If the shaft torque T at this time is obtained, the actual cutting load value P _S of the crop cutting machine 4 is given by P _S = T / (2rsin θ) using the crank radius r of the crank shaft 55 and the contact angle θ. . FIG. 13 shows the crop portion cutting load actual value P _S thus obtained and the crop portion cutting load calculation value P obtained by multiplying the shear resistance τ by the cutting area A. The white circle and solid line in the figure are the calculated value P, and the alternate long and short dash line is the actual value P _S. Since they must match as shown in FIG. 14, the crop section cutting load (calculated value) P is obtained by the following eight equations using the correction coefficient a and the correction constant b.

  Next, calculation processing for setting the cutting position of the cropped portion of the steel sheet S performed by the calculation processing device 9 will be described with reference to the flowchart of FIG. This calculation process is started simultaneously with the detection of the leading end portion in the conveying direction of the hot-rolled steel sheet S for line pipe material by the measuring roll 5, for example, and is first detected by the crop shape meter 10 and the crop portion shape detector 14 in step S1. Read the shape of the cropped part.

Next, the process proceeds to step S2, where it is determined whether or not the shape of the read cropped portion is a fishtail shape by the above-described determination method. If the shape of the cropped portion is a fishtail shape, step S3 is performed. If not, return.
In step S3, the deformation resistance km of the steel sheet S in the first finish rolling mill estimated by the finish rolling setup calculation unit 12 is read.

Next, the process proceeds to step S4, and the position of the length in the steel plate conveyance direction (for example, 110 mm) set in advance from the bottom of the concave portion of the fishtail-shaped crop portion to the tip of the convex portion is set as the concave side cutting position.
Next, the process proceeds to step S5, and the position of the length in the steel plate conveyance direction (for example, 90 mm) set in advance from the front end of the convex part of the fishtail-shaped crop part to the bottom of the concave part is set as the convex part-side cutting position.

Next, it transfers to step S6 and the crop part cutting area A between the set recessed part side cutting position and convex part side cutting position is calculated for every steel plate conveyance direction prescribed | regulated space | interval.
Next, the process proceeds to step S7, where the shear resistance τ is calculated from the deformation resistance km read in step S3 and is multiplied by the cutting area A to calculate the crop portion cutting load P. In this case, the cutting load P may be corrected using the correction coefficient a and the correction constant b as shown in equation (8).

Next, the process proceeds to step S8, and the crop part cutting position is readjusted so that the crop part cutting load P calculated in step S7 is equal to or less than the cutting load upper limit value P _{MAX of the} crop cutting machine 4. Specifically, the concave side cutting position where the cutting load P exceeds the cutting load upper limit P _MAX of the crop cutting machine 4 is removed and moved to the convex side of the crop part.
Next, the process proceeds to step S9, and the crop part cutting position is set according to the request for the steel sheet, and then the process returns. Specifically, if the requirement for the steel sheet is to reduce the mechanical load of the crop cutting machine 4, the position where the cutting load is minimized is set as the crop portion cutting position. Further, if it is intended to minimize the yield by cutting the crop part, the position farthest from the fishtail-shaped recess bottom is set as the crop part cutting position.

According to this arithmetic processing, among the read shape of the cropped portion of the hot-rolled steel sheet for line pipe material, the position of the length in the steel sheet conveying direction set in advance from the bottom of the fishtail-shaped recess to the tip of the protrusion Is set as the recess-side cutting position, and among the read crop part shape, the position of the length in the steel plate conveyance direction set in advance from the tip of the fishtail-shaped convex part to the bottom of the concave part can be cut. Is set as the convex part-side cutting position. Next, the crop section cutting area A between the recess-side cutting position and the recess-side cutting position is calculated for each specified interval in the steel sheet conveyance direction, and the steel sheet deformation resistance km estimated by the finish rolling setup calculation section 12 is used to calculate the steel sheet. The shear resistance τ is calculated, and the crop resistance cutting load P is calculated by multiplying the shear resistance τ by the crop section cutting area A. Then, the crop part cutting position is readjusted so that the crop part cutting load P is equal to or less than the cutting load upper limit value P _{MAX of the} crop cutting machine 4, and the crop part cutting position is set according to the request for the steel sheet.

FIG. 16 shows an example in which the cropping section cutting position is readjusted by the arithmetic processing of FIG. The thickness of the steel sheet S on the finishing rolling entry side was 60 mm, the sheet width was 1900 mm, and the dent radius R of the knife rake of the blade of the crop cutting machine 4 was 24000 mm. For example, if fishtail shape crop portion detected by the crop shape meter 10 was as shown in figure 16a, the concave side cut position N ₁ and convex portions determined by the shape of the crop portions of the hot-rolled steel sheet for line pipe material The side cutting position N ₂ appears as shown in the figure. On the other hand, the cutting width W ₁ and a non-cutting width W ₂ of the crop portions, respectively, are those shown in FIG. 16b, the cutting area A of the crop portions obtained from the cutting width W ₁ and a non-cutting width W ₂ Figure 16c It became as shown in. The cutting load P of the crop part calculated by multiplying the crop part cutting area A by the shear resistance τ is as shown in FIG. 16 d, and this crop part cutting load P is set to be equal to or less than the cutting load upper limit value P _MAX of the crop cutting machine 4. for, the concave side cut position n ₁ was moved to the convex portion side of the cropping unit to the adjusted concave side cut position n _n. As a result, the cutting position in the crop unit has a range from adjusted concave side cut position N _n of the convex portion side cutting position N _2.

  In the existing hot-rolled steel sheet production line, for the intermediate material (sheet thickness 60 mm, sheet width 1900 mm, finish rolling entry temperature 840 to 890 ° C.) for producing hot-rolled steel sheets for line pipe materials, the leading edge in the conveying direction The cutting load of the crop cutting machine 4 at the cutting position by the calculation process of FIG. 15 obtained by making the crop part of the head part and the rear end part in the conveying direction into a fishtail shape and multiplying the cropping part cutting area A by the shear resistance τ 17, and the cutting load of the crop cutting machine 4 at the cutting position reflecting only the cutting width of the crop portion is indicated by × in FIG. 17 as a comparative example. The temperature on the horizontal axis is the temperature of the hot steel sheet on the finishing rolling entry side at the front end of the intermediate material in the conveyance direction detected by the steel sheet thermometer 11. As is apparent from the figure, the crop part cutting load at the cutting position reflecting only the cutting width of the crop part exceeds the cutting load upper limit value of the crop cutting machine 4. On the other hand, the crop section cutting load at the cutting position set in the calculation process of FIG. 15 does not exceed the cutting load upper limit value of the crop cutting machine 4.

Thus, in the steel sheet cutting position setting device of this embodiment, the shape is a fishtail shape, and the crop portion formed at the leading end portion or the trailing end portion in the conveying direction of the steel plate S by rough rolling is subjected to finish rolling. In the case of cutting by the crop cutting machine 4, the cutting position of the crop portion is set by the arithmetic processing device 9 having the arithmetic processing function. Therefore, the crop portion shape detected by the crop shape meter 10 is read in the crop portion shape reading step S1, and the crop portion cutting area A by the crop cutting machine 4 is calculated from the read crop portion shape. Crop calculated with the shear resistance τ calculated from the temperature and the processing strain rate at the leading end or the trailing end in the transport direction of the steel plate detected by the steel plate thermometer 11 and calculated at every specified interval in the steel plate transport direction at S6 The cutting load P of the crop part is calculated from the product value with the cutting area A of the part in the crop part cutting load calculation step S7, and the calculated cutting load P of the crop part is equal to or less than the cutting load upper limit P _{MAX of the} crop cutting machine 4 The cutting position of the crop part is set in the crop part cutting position setting steps S8 and S9 so that As a result, the crop part cutting load P does not exceed the cutting load upper limit value P _MAX of the crop cutting machine 4, so even if the steel sheet has a large plate thickness, a large plate width, and a low temperature, the crop cutting machine Therefore, it is possible to prevent the disconnection due to the lack of capability. In addition, the steel sheet can be stably cut without major equipment modification such as enhancement of the crop cutting machine 4.

Moreover, the finishing rolling setup calculation part 12 which sets the rolling conditions of each finishing rolling mill in finishing rolling is provided, and the shear resistance (tau) is the process calculated from the roll speed of the 1st finishing rolling mill 3 in the uppermost stream side of finishing rolling. It calculates from the deformation resistance km of the steel plate in the 1st finishing rolling mill 3 estimated with the finishing rolling setup calculation part 12 with the detected temperature of the front-end | tip part of the conveyance direction of a steel plate using a distortion speed. Thereby, since the shear resistance τ at the time of cutting the crop part can be calculated with high accuracy, it is possible to reliably prevent the crop part cutting load P from exceeding the cutting load upper limit value P _MAX of the crop cutting machine 4.

Also, of the shape of the crop portion that was read, the concave side cut position setting step the position of the preset steel conveying direction length towards the recess bottom projection end as the concave side cut position N ₁ of fishtail shape Of the shape of the cropped portion that is set and read in S4, the position of the length in the steel plate conveyance direction set in advance from the tip of the fishtail-shaped convex portion to the bottom of the concave portion can be cut on the convex portion side. Crop section cutting position readjustment step that is set as the position N ₂ in the convex section cutting position setting step S5 and that the calculated cutting load P of the crop section is less than or equal to the cutting load upper limit value P _{MAX of the} crop cutting machine 4 in S8, readjusting the set concave side cut position N ₁ and the convex portion side cutting position N _2. Accordingly, it is possible to reliably prevent the crop portion cutting load P from exceeding the cutting load upper limit value P _MAX of the crop cutting machine 4 while avoiding equipment-related cutting position shifts and ensuring cutting at the crop portion. it can.

Further, crop unit breaking load calculation step S7, the cutting load P crop portion that was calculated previously determined so as to match the cutting load actual value P _S of the cropping section of the crop cutter fourth correction coefficient a and the correction constant b The cutting load P of the cropped part calculated using is corrected. This makes it possible to crop unit cutting load P is reliably prevented from exceeding the breaking load limit P _MAX crop cutter 4.

  In the above-described embodiment, the finish rolling setup calculation is performed using the temperature at the front end portion of the steel sheet S in the transport direction, and the deformation resistance km is calculated, but the finish is also performed using the temperature at the tail end portion in the transport direction of the steel sheet S. If the calculation model used for the rolling setup calculation is used, the deformation resistance km at the tail end of the steel sheet conveyance direction can be estimated. And it is also possible to use the deformation resistance km of the tail end part of the steel sheet conveyance direction estimated in this way for calculation of the crop part cutting load P by the crop cutting machine 4.

  It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention-specific matters described in the appropriate claims from the above description.

DESCRIPTION OF SYMBOLS 2 Rough rolling mill 3 Finish rolling mill 4 Crop cutting machine 5 Measuring roll 6 Table roll 7 Rotation sensor 8 Leading edge sensor 9 Arithmetic processing device 10 Crop shape meter 11 Steel plate thermometer 12 Finish rolling setup calculation part 13 Crop part cutting position Setting part 14 Crop part shape detection part S Steel plate

Claims (6)

Computation with an arithmetic processing function when the shape is a fishtail shape and the crop part formed at the leading end or the trailing end in the transport direction of the steel sheet by rough rolling is cut with a crop cutting machine before finish rolling. A steel plate cutting position setting device for setting the cutting position of the crop part in the processing device,
A crop part shape reading unit for reading the shape of the crop part detected by the crop shape meter;
A crop section cutting area calculation unit that calculates the cutting area of the crop part by the crop cutting machine from the shape of the read crop part for each specified interval in the steel sheet conveyance direction;
Crop part cutting load calculation for calculating the cutting load of the crop part from the product value of the shear resistance estimated from the temperature and processing strain rate of the steel sheet detected by the steel sheet thermometer and the calculated cutting area of the crop part And
A steel plate cutting comprising: a crop part cutting position setting unit that sets a cutting position of the crop part so that the calculated cutting load of the crop part is equal to or less than a cutting load upper limit value of the crop cutting machine. Position setting device. A finish rolling setup calculation unit that sets rolling conditions for each finishing mill in the finish rolling,
The shear resistance, the detected steel sheet temperature and estimated in the above using a machining strain rate finish rolling up calculator which is calculated from the roll speed of the first finishing mill of the most upstream side of the front Symbol finish rolling It calculates from the deformation resistance of the steel plate in the said said 1st finishing rolling mill, The steel plate cutting position setting apparatus of Claim 1 characterized by the above-mentioned. Of the read shape of the cropped portion, a recess-side cutting position setting unit that sets the position of the length in the steel plate conveying direction set in advance from the fishtail-shaped recess bottom to the tip of the protruding portion as the recess-side cutting position. When,
Of the read shape of the crop part, the position of the length in the steel plate conveyance direction set in advance from the tip of the fishtail-shaped convex part to the bottom of the concave part is defined as a convex part-side cutting position at which the crop part can be cut. A convex side cutting position setting part to be set,
The crop section cutting position setting section is
A crop part cutting position readjustment unit for readjusting the set recess side cutting position and the convex part side cutting position so that the calculated cutting load of the crop part is equal to or less than a cutting load upper limit value of the crop cutting machine; The steel plate cutting position setting device according to claim 1, wherein the steel plate cutting position setting device is provided. The crop part cutting load calculation unit is:
The calculated crop cutting load using at least one of a correction coefficient and a correction constant obtained in advance so that the calculated cutting load of the crop section matches the cutting load of the crop section in the crop cutting machine. It correct | amends, The steel plate cutting position setting apparatus as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   A crop cutting machine that cuts a crop portion at a leading end portion or a trailing end portion in a transport direction of a steel sheet according to the cutting position of the crop portion set by the steel sheet cutting position setting device according to any one of claims 1 to 4. The steel plate manufacturing method characterized by cut | disconnecting by.   In the steel plate cutting position setting device according to any one of claims 1 to 4, a sizing press or a sizing press to make the shape of the crop portion at the front end portion or the rear end portion in the transport direction of the steel plate into a fishtail shape. A method of manufacturing a steel sheet, comprising performing a width reduction of the steel sheet using a width rolling mill.

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