Method for calculating groove filling degree in groove rolling of shaped steel and method for manufacturing shaped steel

Abstract

Provided are a method for calculating a groove filling degree in groove rolling of shaped steel, capable of accurately calculating the groove filling degree of steel material in groove rolling of shaped steel, and a method for manufacturing shaped steel. This method for calculating a groove filling degree in groove rolling of shaped steel comprises: a measurement length calculation step (step S1) for calculating a measurement length (L), which is the length of a rough billet (S2) after a final groove rolling pass; a material cross-sectional area calculation step (step S2) for calculating a material cross-sectional area (A) in the final groove rolling pass by dividing the volume of the rough billet (S2) after the final groove rolling pass, excluding a crop portion (C), by the value obtained by subtracting a crop length (CL) from the measurement length (L); and a groove filling degree calculation step (step S3) for calculating a groove filling degree (μ) of the steel material (S1) in the final groove rolling pass on the basis of the material cross-sectional area (A) and a cross-sectional area (Kk) of the groove including a portion that becomes a roll gap in the final groove rolling pass.

Description

Method for calculating groove filling degree in groove rolling of shaped steel and method for manufacturing shaped steel

[0001] The present invention relates to a method for calculating a groove filling degree in groove rolling of a shaped steel and a method for manufacturing a shaped steel.

[0002] Generally, structural steel such as H-beams is manufactured by hot rolling steel materials such as blooms, slabs, and beam blanks. Hot rolling of structural steel includes a rough rolling process, an intermediate rolling process, and a finish rolling process. In the rough rolling process, rough rolling known as groove rolling is performed using a breakdown rolling mill. This groove rolling roughly rolls the steel material to a predetermined cross-sectional shape using a pair of upper and lower rolls formed with grooves called grooves. In the intermediate rolling process, the steel material roughly rolled to a predetermined cross-sectional shape in the rough rolling process is rolled using an intermediate universal rolling mill and an intermediate edging rolling mill to produce a rolled material for finish rolling that has approximately the product dimensions. In the finish rolling process, the rolled material for finish rolling that has approximately the product dimensions rolled in the intermediate rolling process is finish rolled using a finish universal rolling mill to produce structural steel with the product dimensions. Here, the steel material that has been roughly rolled by groove rolling in the rough rolling step is elongated to a length longer than the original length.

[0003] A known example of a method for measuring the length of hot-rolled steel is the hot long bar length measuring method described in Patent Document 1. The method for measuring hot long bars transported along a conveying path includes an imaging field of view that covers the entire length of the hot long bar and detects that the hot long bar has been transported within the field of view of a single imaging device that images a specific area of ​​the conveying path. Upon detecting that the hot long bar has been transported within the field of view, a still image of the hot long bar captured by the imaging device is acquired, and the length of the hot long bar is calculated from the longitudinal position of the hot long bar in the still image and length conversion coefficients that differ in two or more longitudinal zones in the image. The length conversion coefficients that differ in two or more longitudinal zones in the image are derived in advance by image processing of light spot image data obtained by capturing an image of a light spot scale with scales arranged in the longitudinal direction of the hot long bar within a specific area.

[0004] On the other hand, in the groove rolling in the rough rolling process, there are many cases where the material does not completely fill the groove shape. In the groove rolling, if the material does not completely fill the groove shape and the groove filling degree in the groove rolling is different from the expected, the thickness reduction balance does not fall within the predetermined range in the intermediate rolling process, resulting in problems such as not being able to obtain the target cross-sectional dimensions of the shaped steel product. For this reason, it is necessary to understand the cross-sectional shape of the steel material after groove rolling.

[0005] Conventionally, a known method for measuring the cross-sectional shape of a hot-rolled steel material is the cross-sectional shape profile measurement method disclosed in Patent Document 2. The cross-sectional shape profile measurement method disclosed in Patent Document 2 involves disposing a laser rangefinder on both sides of an object to be measured so that it can travel back and forth, scanning the object to be measured by changing the direction of the optical axis by rotating the laser rangefinder on the outward and return paths, and deriving the cross-sectional shape profile of the object to be measured from the position of a base point on the optical axis, the distance from the base point to the scanning point, and the angle between the traveling direction and the optical axis.

[0006] JP2014-55833A JP10-239026A

[0007] However, these conventional hot elongated material length measuring method disclosed in Patent Document 1 and cross-sectional shape profile measuring method disclosed in Patent Document 2 have the following problems. That is, in the case of the hot elongated material length measuring method disclosed in Patent Document 1, although it is possible to calculate the length of the hot elongated material, it is not possible to calculate the caliber filling degree of the steel material in caliber rolling. In addition, in the case of the cross-sectional shape profile measuring method disclosed in Patent Document 2, it is possible to derive the cross-sectional shape profile of the object to be measured, so it is possible to determine the cross-sectional shape of the rolled material after caliber rolling. However, this cross-sectional shape profile measuring method can only determine the cross-sectional shape at a specific position in the longitudinal direction of the rolled material, and there is a problem that the measurement accuracy is insufficient for determining the caliber filling degree of the steel material in caliber rolling.

[0008] Therefore, the present invention has been made to solve this conventional problem, and its purpose is to provide a method for calculating the degree of groove filling in groove rolling of structural steel and a method for manufacturing structural steel, which can accurately calculate the degree of groove filling of steel material in groove rolling of structural steel.

[0009] In order to solve the above problems, a method for calculating a groove filling degree in groove rolling of shaped steel according to one aspect of the present invention is a method for calculating a groove filling degree in groove rolling of shaped steel that is manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material into a rough steel billet of a predetermined cross-sectional shape using a groove, an intermediate rolling process in which the rough rolled rough steel billet is rolled to form a rolled material for finish rolling, and a finish rolling process in which the rolled material for finish rolling is finish rolled, wherein a plurality of groove rolling passes are performed in the groove rolling, and in a final groove rolling pass among the plurality of groove rolling passes in which the groove filling degree is calculated, the steel material is rolled into a web portion, a flange portion, and The gist of the method is to include a measurement length calculation step of calculating a measurement length L, which is the length of the rough steel billet after the final groove rolling pass; a material cross-sectional area calculation step of calculating a material cross-sectional area A at the final groove rolling pass by dividing the volume of the rough steel billet after the final groove rolling pass excluding the crop portion by a value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step; and a groove fullness calculation step of calculating a groove fullness μ of the steel material at the final groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation step and a groove cross-sectional area Kk including a portion that becomes a roll gap at the final groove rolling pass.

[0010] In this method for calculating the groove fullness in groove rolling of structural steel, if tongue cutting is not performed after the rough rolling process, the material cross-sectional area calculation process uses the following formula (2-1) to calculate the material cross-sectional area A in the final groove rolling pass, and the groove fullness calculation process uses the following formula (3). It is preferable to calculate the groove fullness μ of the steel material in the final groove rolling pass. A = {M - CM} / {(L - CL) γ} ... (2-1) μ = A / Kk ... (3) Here, in formulas (2-1) and (3), A: material cross-sectional area in the final caliber rolling pass; M: mass of the rough steel billet after the final caliber rolling pass; CM: crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough steel billet and the mass of the portion that will become the crop at the tail end of the rough steel billet; L: measured length which is the length of the rough steel billet after the final caliber rolling pass; CL: crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough steel billet and the length of the portion that will become the crop at the tail end of the rough steel billet; γ: specific gravity of the rough steel billet μ: caliber filling degree of steel material in the final caliber rolling pass; Kk: caliber cross-sectional area in the final caliber rolling pass including the portion that will become the roll gap.

[0011] Further, in the method for calculating the groove fullness in groove rolling of structural steel, when tongue cutting is performed after the rough rolling process, the measurement length calculation process calculates the measurement length L, which is the length of the rough steel billet after the tongue cutting, and the material cross-sectional area calculation process calculates the material cross-sectional area A in the final groove rolling pass using the following formula (2-2). It is preferable that the groove fullness calculation process calculates the groove fullness μ of the steel material in the final groove rolling pass using the following formula (3). A = {M - TM - CM} / {(L - CL) γ} ... (2-2) μ = A / Kk ... (3) Here, in formulas (2-2) and (3), A: material cross-sectional area at the final caliber rolling pass M: mass of the rough billet after the final caliber rolling pass TM: tongue cut mass CM: mass of the crop portion, which is the crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough billet and the mass of the portion that will become the crop at the tail end of the rough billet L: measured length, which is the length of the rough billet after the final caliber rolling pass CL: length of the crop portion, which is the crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough billet and the length of the portion that will become the crop at the tail end of the rough billet γ: specific gravity of the rough billet μ: caliber filling degree of the steel material at the final caliber rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap.

[0012] In addition, another aspect of the present invention relates to a method for manufacturing structural steel, and is summarized as including a groove fullness comparison process for comparing the groove fullness μ of the steel material at the final groove rolling pass calculated by the above-mentioned method for calculating the groove fullness in groove rolling of structural steel with a groove fullness reference value, and a roll gap change process for groove rolling of the steel material to be subsequently rough rolled, in which if the groove fullness μ of the steel material at the final groove rolling pass is smaller than the groove fullness reference value, the pair of upper and lower roll gaps constituting the groove are changed to be smaller, and if the groove fullness μ of the steel material at the final groove rolling pass is larger than the groove fullness reference value, the roll gap is changed to be larger.

[0013] In addition, a manufacturing method of a shaped steel according to another aspect of the present invention includes a flange fullness calculation step of calculating a flange fullness μf based on the groove fullness μ of the steel material at the final groove rolling pass calculated by the method for calculating a groove fullness in groove rolling of the shaped steel described above, a cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and a cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the following formula (4): and a roll gap changing step of, for groove rolling of a steel material to be subsequently rough rolled, making a change to reduce the roll gap in the web portion of a pair of upper and lower rolls constituting the groove if the flange fullness μf calculated in the flange fullness calculation step is smaller than the flange fullness reference value, and making a change to increase the roll gap if the flange fullness μf calculated in the flange fullness calculation step is larger than the flange fullness reference value.

[0014] In addition, a manufacturing method of a shaped steel according to another aspect of the present invention is summarized as including a groove fullness comparison step of comparing the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of the shaped steel described above with a groove fullness reference value, and a reduction rate difference change step of changing the reduction rate difference η (= rf - rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw of at least the first pass in an intermediate rolling step of rolling the rough rolled rough steel billet, so that if the groove fullness μ of the steel material in the final groove rolling pass is smaller than the groove fullness reference value, the reduction rate difference η is changed to be smaller than a standard reduction rate difference condition, and if the groove fullness μ of the steel material in the final groove rolling pass is larger than the groove fullness reference value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition.

[0015] In addition, a manufacturing method of a shaped steel according to another aspect of the present invention includes a flange fullness calculation step of calculating a flange fullness μf based on the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating a groove fullness in groove rolling of the shaped steel, a cross-sectional area Aw of the web portion of the groove in the final groove rolling pass, and a cross-sectional area Af of the flange portion of the groove in the final groove rolling pass, according to the above-mentioned formula (4); a flange fullness comparison step of comparing the flange fullness μf calculated in the flange fullness calculation step with a flange fullness reference value; and a rough-rolled rough shaped steel billet. and a rolling reduction difference changing step of changing the rolling reduction difference η (=rf-rw) between the thickness reduction rate rf of the flange portion and the thickness reduction rate rw of the web portion in at least the first pass in an intermediate rolling step of rolling the flange. When the flange fullness μf calculated in the flange fullness calculation step is smaller than the flange fullness reference value, the rolling reduction difference η is changed to be smaller than the reference rolling reduction difference condition, and when the flange fullness μf calculated in the flange fullness calculation step is larger than the flange fullness reference value, the rolling reduction difference η is changed to be larger than the reference rolling reduction difference condition.

[0016] Further, according to another aspect of the present invention, there is provided a method for calculating a groove fullness in groove rolling of a shaped steel, which is manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material into a rough shaped steel billet having a predetermined cross-sectional shape using a groove, an intermediate rolling process in which the rough rolled rough shaped steel billet is rolled into a rolled material for finish rolling, and a finish rolling process in which the rolled material for finish rolling is finish rolled. In the groove rolling, a plurality of groove rolling passes are performed, and in a fill degree calculation groove rolling pass in which the groove fullness is calculated for any one of the plurality of groove rolling passes, the steel material has a web portion and a flange portion. The gist of the method includes a measurement length calculation step of calculating a measurement length L, which is the length of the steel material after the fullness calculation groove rolling pass; a material cross-sectional area calculation step of calculating a material cross-sectional area A at the fullness calculation groove rolling pass by dividing the volume of the steel material after the fullness calculation groove rolling pass excluding the crop portion by a value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step; and a groove fullness calculation step of calculating a groove fullness μ of the steel material at the fullness calculation groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation step and the groove cross-sectional area Kk including the portion that becomes the roll gap at the fullness calculation groove rolling pass.

[0017] In addition, another aspect of the present invention is a method for manufacturing structural steel, which includes a groove fullness comparison process for comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel described above with a groove fullness reference value, and a roll gap change process for, for groove rolling of the steel material to be next rough rolled, making a change to reduce the gap between a pair of upper and lower rolls that constitute the groove if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is smaller than the groove fullness reference value, and making a change to increase the roll gap if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is greater than the groove fullness reference value.

[0018] In addition, a manufacturing method of a shaped steel according to another aspect of the present invention is summarized as including a groove fullness comparison step of comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in the groove rolling of the shaped steel described above with a groove fullness reference value, and a reduction rate difference change step of changing the reduction rate difference η (= rf - rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw of at least the first pass in an intermediate rolling step of rolling the rough rolled rough steel billet, so that if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is smaller than the groove fullness reference value, the reduction rate difference η is changed to be smaller than a standard reduction rate difference condition, and if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is larger than the groove fullness reference value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition.

[0019] According to the method for calculating the degree of groove fullness in groove rolling of structural steel and the method for manufacturing structural steel of the present invention, it is possible to provide a method for calculating the degree of groove fullness in groove rolling of structural steel and a method for manufacturing structural steel, which can accurately calculate the degree of groove fullness of steel material in groove rolling of structural steel.

[0020] 1 is a schematic configuration diagram of an H-beam rolling facility to which a manufacturing method of an H-beam as shaped steel according to one embodiment of the present invention is applied. FIG. 2 is a diagram showing an example of the relationship between the shape of the groove in the final groove rolling pass for calculating the groove fullness in groove rolling and the cross-sectional shape of the steel material. FIG. 3 is a diagram showing another example of the relationship between the shape of the groove in the final groove rolling pass for calculating the groove fullness in groove rolling and the cross-sectional shape of the steel material. (a) is a cross-sectional view for explaining an intermediate universal rolling process in the intermediate rolling process, (b) is a cross-sectional view for explaining an intermediate edging rolling process in the intermediate rolling process, and (c) is a cross-sectional view for explaining the finish rolling process. FIG. 4 is a diagram showing a schematic configuration of a groove fullness calculation device for calculating the groove fullness in groove rolling. FIG. 5 is a diagram for explaining the vertical position of a photographing camera constituting the groove fullness calculation device relative to a rough steel billet. FIG. 6 is a diagram for explaining the cross-sectional area of ​​the groove in the final groove rolling pass. 1 is a flowchart for explaining the processing flow in a groove fullness calculation device showing a method for calculating the groove fullness in groove rolling. 2 is a flowchart for explaining the processing flow for changing the roll gap for groove rolling of a steel material to be next rough rolled based on the groove fullness of the steel material calculated by the groove fullness calculation device. 3 is a flowchart for explaining the processing flow for changing the rolling reduction difference between the thickness reduction rate of the flange portion and the thickness reduction rate of the web portion in the first pass in an intermediate rolling process for rolling a roughly rolled rough steel billet based on the groove fullness of the steel material calculated by the groove fullness calculation device.

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below are examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not limited to the following embodiments in terms of the materials, shapes, structures, arrangements, etc. of the components. Furthermore, the drawings are schematic. Therefore, it should be noted that the relationships and ratios between thicknesses and planar dimensions differ from the actual ones, and the drawings also include portions where the relationships and ratios of dimensions differ from one another.

[0022] The rolling facility 1 for H-beam steel shown in Figure 1 is configured by sequentially arranging, from upstream to downstream, a heating furnace 2, a roughing mill 3, an intermediate universal rolling mill 4 and an intermediate edging mill 5 as intermediate rolling mills, and a finishing universal rolling mill (finishing mill) 6 as a finishing rolling mill. The heating furnace 2 heats the steel material S1 to a predetermined temperature to be subjected to rough rolling by the roughing mill 3. The roughing mill 3 rough rolls the steel material S1 transported from the heating furnace 2 on table rollers (not shown) to produce a rough steel billet S2 (rough rolling process).

[0023] In the rough rolling process, for example, as shown in Figures 2 and 3, groove rolling is performed to roughly roll the steel material S1 into a rough steel billet S2 having a predetermined cross-sectional shape using grooves 33 formed on the peripheral surfaces of a pair of upper and lower rolls 31 and 32 provided in a rough rolling mill 3. In the groove rolling of the rough rolling process, a plurality of groove rolling passes are performed, and as shown in Figures 2 and 3, for example, in the final groove rolling pass among the plurality of groove rolling passes, which is used to calculate the groove fullness, the steel material S1 has a web portion S1W and a flange portion S1F.

[0024] As shown in Figure 4(a), the rough-rolled billet S2 has a web portion S2W and a flange portion S2F. As shown in Figures 1 and 5, the rough-rolled billet S2 has a predetermined length in the direction from rear to front, which is the conveying direction of the rough-rolled billet S2, and a portion that will become crop C1 is formed at its leading end (front end), and a portion that will become crop C2 is also formed at its trailing end (rear end). The length of the rough-rolled billet S2 is measured by a photographing camera 11, which will be described later, and the measured length L is calculated. The portion that will become crop C1 at the leading end of the rough-rolled billet S2 and the portion that will become crop C2 at the trailing end of the rough-rolled billet S2 are combined to form the crop portion C. The length CL of the portion that will become crop C1 at the leading end of the rough-rolled billet S2 is １ and the length CL of the part that becomes the crop C2 at the tail end of the rough steel billet S2. ２ The combined length is the crop length CL of the cropped portion C.

[0025] The technology of the present application can also be applied to a case where the product does not have a flange portion, as long as the shape can be regarded as having a web portion S1W and a flange portion S1F at the rough rolling stage, such as a straight steel sheet pile having a web portion and joint portions at both ends thereof. The cross-sectional shape of the straight steel sheet pile after rough rolling is the shape shown in Figure 3, and in this specification, both ends in the width direction in Figure 3 are referred to as flange portions S1F.

[0026] Between the roughing mill 3 and the intermediate universal rolling mill 4, a tongue cut saw 7 is installed, which performs tongue cutting, cutting off the tongue portion (not shown), which is the leading and trailing end portion of the rough steel billet S2. Tongue cutting is usually performed using a tongue cut saw 7 having a circular rotary saw blade. Tongue cutting with the tongue cut saw 7 may not be performed depending on the steel type and size of the rough steel billet S2. The tongue portion can be considered to be part of the crop C1 at the leading end of the rough steel billet S2 and the crop C2 at the trailing end of the rough steel billet S2. The mass of the portion cut off by tongue cutting is designated as TM.

[0027] The intermediate universal rolling mill 4 and the intermediate edging rolling mill 5 are installed downstream of the tongue cut saw 7, and as shown in Figures 4(a) and 4(b), the rough steel billet S2 rough-rolled in the rough rolling process by the roughing mill 3 is rolled into a rolled material S3 having a web portion S3W for finish rolling and a pair of flange portions S3F that have approximately the product dimensions (intermediate rolling process). Note that the approximately product dimensions here refer to dimensions that allow the rolled material to be made into the product dimensions in the finish rolling process. The intermediate rolling process includes an intermediate universal rolling process by the intermediate universal rolling mill 4 shown in Figure 4(a) and an intermediate edging rolling process by the intermediate edging rolling mill 5 shown in Figure 4(b).

[0028] As shown in Fig. 4(a), the intermediate universal rolling mill 4 has a pair of upper and lower horizontal rolls 41, 42 that rotate on a horizontal axis, and a pair of left and right vertical rolls 43, 44 that rotate on a vertical axis. In the intermediate universal rolling process using the intermediate universal rolling mill 4, multiple passes of rolling are performed by reverse rolling, and as shown in Fig. 4(a), the circumferential surfaces of the horizontal rolls 41, 42 roll down the entire height direction of the web portion S2W of the rough steel billet S2 in the plate thickness direction, and the circumferential surfaces of the vertical rolls 43, 44 and the side surfaces of the horizontal rolls 41, 42 roll down the flange portion S2F in the plate thickness direction.

[0029] The intermediate edging mill 5 is installed downstream of the intermediate universal rolling mill 4, and as shown in Figure 4(b), is equipped with a pair of upper and lower horizontal rolls 51, 52, each of which has a large diameter roll portion and a small diameter roll portion in the horizontal axis direction. In the intermediate edging rolling process using the intermediate edging mill 5, multiple passes of rolling are performed by reverse rolling, and as shown in Figure 4(b), the large diameter roll portions of the pair of upper and lower horizontal rolls 51, 52 guide the web portion S2W of the rough steel billet S2 that has been intermediate universally rolled, and the small diameter roll portions roll down the end faces of the flange portions S2F in the width direction, turning the rough steel billet S2 into a rolled material S3 for finish rolling that has approximately the dimensions of the product.

[0030] Furthermore, a finishing universal rolling mill (finishing rolling mill) 6 is installed downstream of the intermediate universal rolling mill 4 and the intermediate edging rolling mill 5, and as shown in Fig. 4(c), finish-rolls the rolled material S3 for finish rolling, which has been rolled in the intermediate rolling process to approximately the product dimensions, into H-beam H of the product dimensions (finish rolling process). The H-beam H is manufactured through this finish rolling process. As shown in Fig. 4(c), the finishing universal rolling mill 6 is equipped with a pair of upper and lower horizontal rolls 61, 62 that rotate on horizontal axes, and a pair of left and right vertical rolls 63, 64 that rotate on vertical axes.

[0031] In the finish rolling process using the finishing universal rolling mill 6, a pair of upper and lower horizontal rolls 61, 62 and a pair of left and right vertical rolls 63, 64 roll down the web portion S3W and flange portion S3F of the rolled material S3 to the thickness of the product dimensions, and also correct the angle of the flange portion S3F. This results in an H-beam H of the product dimensions. Here, in the final caliber rolling pass, which calculates the caliber filling degree in caliber rolling in the rough rolling process, there are areas where the steel material S1 does not fill the shape of the caliber 33, as shown in Figure 2, for example. In this example, the inner surface portions S1Fa of the left and right flange portions S1F do not fill the caliber 33.

[0032] Furthermore, in the final groove rolling pass, which calculates the groove filling rate in groove rolling in the rough rolling process, the filling rate of the upper end S1Fc of the left flange portion S1F may differ from the filling rate of the upper end S1Fc of the right flange portion S1F, as shown in another example in FIG. 3. The filling rate of the upper end S1Fc of the left flange portion S1F is smaller than the filling rate of the upper end S1Fc of the right flange portion S1F. Note that rolling using a groove 33 as shown in FIG. 3 is also used for straight steel sheet piles in addition to H-shaped steel. The filling rate of the steel material S1 relative to the groove 33 in the final groove rolling pass affects the subsequent intermediate rolling shown in FIGS. 4(a) and 4(b) and finish rolling shown in FIG. 4(c).

[0033] For example, in the rolling of H-section steel, as described above, intermediate universal rolling is performed by the intermediate universal rolling mill 4 in the intermediate rolling process. In intermediate universal rolling, as shown in FIG. 4( a), the circumferential surfaces of the horizontal rolls 41 and 42 roll down the entire height of the web portion S2W of the rough steel billet S2 in the thickness direction, and the circumferential surfaces of the vertical rolls 43 and 44 and the side surfaces of the horizontal rolls 41 and 42 roll down the flange portion S2F in the thickness direction. Typically, intermediate universal rolling is performed under conditions such that the thickness reduction rate of the web portion S2W and the thickness reduction rate of the flange portion S2F are approximately equal. However, if the flange fullness (caliber fullness) of the steel material S1 in the rough rolling (final caliber rolling pass) differs from the reference value (it is possible that the flange fullness is greater or smaller than the reference value), the thickness reduction balance in the intermediate universal rolling will not be within the specified range. As a result, the target product cross-sectional dimensions may not be obtained, or the intermediate rolling conditions and finish rolling conditions may become abnormal, making it impossible to perform rolling after intermediate rolling. For this reason, it is necessary to grasp the degree to which the steel material S1 has filled the groove in the final groove rolling pass of rough rolling, and to set or correct the rolling conditions for groove rolling of the steel material to be next rough rolled or the rolling conditions in the intermediate rolling process in which the rough rolled rough steel billet is rolled, depending on this groove filling degree.

[0034] In this embodiment, the groove fullness of the steel material S1 at the final groove rolling pass in groove rolling is calculated using a groove fullness calculation device 10 shown in Figures 1, 5, and 6. Here, the groove fullness calculation device 10 is equipped with a photographing camera 11, an image processing device 12, and a monitor 13, as shown in Figure 5. The photographing camera 11 photographs the entire length of the rough shaped steel billet S2 after rough rolling. As shown in Figures 5 and 6, the photographing camera 11 is installed diagonally above the left side of the rough shaped steel billet S2 to be photographed, and photographs the entire length of the rough shaped steel billet S2 traveling in the conveying direction after rough rolling.

[0035] The image processing device 12 also processes the images captured by the camera 11 to calculate a measured length L, which is the length of the rough steel billet S2 after the final caliber rolling pass. The image processing device 12 also calculates the material cross-sectional area A (the cross-sectional area of ​​the steel material S1 in Figures 2 and 3) at the final caliber rolling pass by dividing the volume of the rough steel billet S2 after the final caliber rolling pass, excluding the crop portion C, by the value obtained by subtracting the crop length CL from the calculated measured length L. Furthermore, the image processing device 12 calculates the caliber filling degree μ of the steel material S1 at the final caliber rolling pass based on the calculated material cross-sectional area A and the caliber cross-sectional area Kk (see Figures 2, 3, and 7) including the portion that becomes the roll gap at the final caliber rolling pass.

[0036] The image processing device 12 is a computer system equipped with an arithmetic processing device. The image processing device 12 executes the functions of calculating the measurement length L, calculating the material cross-sectional area A, and calculating the caliber filling degree μ of the steel material S1 at the final caliber rolling pass in accordance with the instructions of the installed program. First, a method for calculating the measurement length L by the image processing device 12 will be described. The image captured by the photographing camera 11 is sent to the image processing device 12, where it is processed to calculate the number of pixels present in the photographed image of the rough steel billet S2 in the left and right directions.

[0037] The image processing device 12 then calculates the measured length L of the rough steel billet S2 by multiplying the calculated number of pixels by a conversion coefficient that converts the length per pixel. The method for measuring the length of hot elongated material described in Patent Document 1 can be used to calculate this measured length L. That is, the measured length L of the rough steel billet S2 is calculated from the longitudinal (left-right) position of the rough steel billet S2 in the image captured by the camera 11 and length conversion coefficients that differ in two or more longitudinal regions in the image. The length conversion coefficients that differ in two or more longitudinal regions in the image are derived in advance by image processing light spot image data obtained by capturing an image of a light spot scale having scales arranged in the longitudinal direction of the rough steel billet S2 within a specific region.

[0038] Next, a method for calculating the material cross-sectional area A in the final groove rolling pass using the image processing device 12 will be described. The image processing device 12 calculates the material cross-sectional area A in the final groove rolling pass by dividing the volume of the rough steel billet S2 after the final groove rolling pass, excluding the crop portion C, by the value obtained by subtracting the crop length CL from the calculated measured length L. When calculating this material cross-sectional area A, the calculation method for the material cross-sectional area A differs depending on whether tongue cutting is not performed after rough rolling or whether tongue cutting is performed and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated.

[0039] (1) When tongue cutting is not performed When tongue cutting is not performed after rough rolling, the formula for the mass of the rough billet S2 is as follows: M = (L - CL) x A x γ + CM (1-1) In formula (1-1), M: mass of the rough billet S2 after the final caliber rolling pass L: measured length, which is the length of the rough billet S2 after the final caliber rolling pass A: material cross-sectional area at the final caliber rolling pass CL: length of the crop portion C, which is the length CL of the portion that becomes the crop C1 at the tip of the rough billet S2 １ and the length CL of the part that becomes the crop C2 at the tail end of the rough steel billet S2. ２ γ: specific gravity of the rough shaped billet S2 CM: mass of the crop C, which is the mass CM of the part of the rough shaped billet S2 that becomes the crop C1 １ and the mass CM of the part that becomes the crop C2 at the tail end of the rough steel billet S2 ２ The crop amount formula (1-1) expressed as the sum of and can be transformed to express the material cross-sectional area A in the final groove rolling pass as A = {M-CM} / {(L-CL) · γ} ... (2-1).

[0040] (2) When tongue cutting is performed and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated When tongue cutting is performed after rough rolling and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated, the formula for the mass of the rough steel billet S2 is as follows: M-TM=(L-CL)×A×γ+CM (1-2) Where, in formula (1-2), M: mass of the rough steel billet S2 after the final caliber rolling pass TM: tongue-cut mass L: measured length, which is the length of the rough steel billet S2 after the final caliber rolling pass A: material cross-sectional area at the final caliber rolling pass CL: length of the crop portion C, which is the length CL of the portion that becomes the crop C1 at the tip of the rough steel billet S2 １ and the length CL of the part that becomes the crop C2 at the tail end of the rough steel billet S2. ２ γ: specific gravity of the rough shaped billet S2 CM: mass of the crop C, which is the mass CM of the part of the rough shaped billet S2 that becomes the crop C1 １ and the mass CM of the part that becomes the crop C2 at the tail end of the rough steel billet S2 ２ The crop amount formula (1-2) expressed as the sum of the above can be transformed to express the material cross-sectional area A in the final groove rolling pass as follows: A = {M-TM-CM} / {(L-CL) · γ} ... (2-2)

[0041] Here, in equations (2-1) and (2-2), M is the mass of the rough slab S2 after the final caliber rolling pass, and is the mass obtained by subtracting the scale loss during heating in the heating furnace 2 from the mass of the material before it is charged into the heating furnace 2. The mass of the material before it is charged into the heating furnace 2 is measured using a weighing machine (not shown), and the actual measurement value is input to the image processing device 12. The scale loss during heating is calculated from the type and dimensions of the material and the heating conditions (heating temperature, material furnace time, etc.). Information on the type and dimensions of the material and the heating conditions is input to the image processing device 12 from a host computer 14 connected to the image processing device 12, and the image processing device 12 calculates the scale loss during heating. The image processing device 12 calculates the mass M of the rough slab S2 after the final caliber rolling pass by subtracting the calculated scale loss during heating from the input actual measurement value measured by the weighing machine.

[0042] In addition, in the formulas (2-1) and (2-2), γ is the specific gravity of the rough steel billet S2, which is 7850 kg / m for carbon steel. ３ Information on the specific gravity γ of the rough shaped billet S2 is input from the host computer 14 to the image processing device 12. In addition, in the formulas (2-1) and (2-2), CM is the mass of the crop portion C, and the mass CM of the portion that becomes the crop C1 at the tip of the rough shaped billet S2 １ and the mass CM of the part that becomes the crop C2 at the tail end of the rough steel billet S2 ２ CL is the length of the cropped portion C, and is the length CL of the portion that becomes the crop C1 at the tip of the rough shaped steel billet S2. １ and the length CL of the part that becomes the crop C2 at the tail end of the rough steel billet S2. ２ The crop length is expressed as the sum of

[0043] The crop portion C is the leading and trailing portions of the rough steel billet S2 that will not ultimately become a product, and the tongue cut also remains on the rough steel billet S2. In formula (2-2), CM is the mass of the crop portion C remaining on the rough steel billet S2 after tongue cut, and CL is the length of the crop portion C remaining on the rough steel billet S2 after tongue cut. Since the standard rolling conditions are the same for each size and type of H-section steel, the crop portion mass CM and crop length CL in formulas (2-1) and (2-2) can be determined for each size and type of H-section steel through prior investigation. Information on the crop portion mass CM and crop length CL in formulas (2-1) and (2-2) is input from the host computer 14 to the image processing device 12. The crop portion C is cut off by sawing (hot sawing or cold sawing) after finish rolling to produce the finished product.

[0044] In addition, in formula (2-2), TM is the tongue cut mass, which is the mass of the tongue portion cut off by the tongue cut saw 7 after rough rolling and before measuring the length of the rough steel billet S2. Since tongue cut conditions are determined for each size and type of H-beam, the tongue cut mass TM is measured in advance for each size and type of H-beam, and this value is used. Information on the tongue cut mass TM in formula (2-2) is input from the host computer 14 to the image processing device 12.

[0045] Next, a method for calculating the caliber filling degree μ of the steel material S1 in the final caliber rolling pass using the image processing device 12 will be described. The image processing device 12 calculates the caliber filling degree μ of the steel material S1 in the final caliber rolling pass using the following formula (3) based on the material cross-sectional area A calculated using formula (2-1) or formula (2-2) and the caliber cross-sectional area Kk (see Figures 2, 3, and 7) including the portion that becomes the roll gap in the final caliber rolling pass. μ = A / Kk ... (3)

[0046] Here, Kk is the cross-sectional area of ​​the groove at the roll gap in the final groove rolling pass. The cross-sectional area Kk of the groove at the roll gap, as explained with reference to Fig. 7, is the cross-sectional area of ​​the groove 33 including the portion that becomes the roll gap S. The cross-sectional area Kk of the groove at the roll gap is expressed as the sum of the cross-sectional area Aw of the web portion in the groove 33 and the cross-sectional area Af (= 1 / 2 Af x 2) of the flange portions on both the left and right sides of the groove 33. In other words, the cross-sectional area Kk of the groove at the roll gap in the final groove rolling pass can be expressed as Kk = Aw + Af.

[0047] The cross-sectional area Aw of the web portion in the groove 33 can be expressed as Aw = Sw x Bw by multiplying the roll gap Sw of the web rolling portion in the groove 33 by the groove width Bw of the web rolling portion in the groove 33. Information on the groove cross-sectional area Kk of the roll gap in the final groove rolling pass is input from the host computer 14 to the image processing device 12. The monitor 13 is a display device that displays the calculation results of the image processing device 12. Specifically, the monitor 13 displays the groove filling degree μ of the steel material S1 in the final groove rolling pass calculated by the image processing device 12.

[0048] Next, a method for calculating the caliber fullness in caliber rolling of a shaped steel according to this embodiment will be described with reference to the flowchart of FIG. 8, which explains the processing flow in the caliber fullness calculation device 10. First, in step S1, the caliber fullness calculation device 10 calculates the measured length L, which is the length of the rough shaped steel billet S2 after the final caliber rolling pass (measurement length calculation process). When calculating this measured length L, the photographing camera 11 of the caliber fullness calculation device 10 first photographs the entire length of the rough shaped steel billet S2 after rough rolling. Next, the image processing device 12 of the caliber fullness calculation device 10 processes the photographed image taken by the photographing camera 11 to calculate the measured length L, which is the length of the rough shaped steel billet S2 after the final caliber rolling pass. The method for calculating this measured length L is as described above.

[0049] Next, in step S2, the image processing device 12 of the caliber fullness calculation device 10 calculates the material cross-sectional area A in the final caliber rolling pass by dividing the volume of the rough slab S2 after the final caliber rolling pass, excluding the crop portion C, by the value obtained by subtracting the crop length CL from the measurement length L calculated in step S1 (measurement length calculation step) (material cross-sectional area calculation step). Here, if tongue cutting is not performed after rough rolling, in the material cross-sectional area calculation step, the image processing device 12 of the caliber fullness calculation device 10 calculates the material cross-sectional area A in the final caliber rolling pass using the above-mentioned formula (2-1).

[0050] On the other hand, when tongue cutting is performed after rough rolling and the measurement length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated, in the material cross-sectional area calculation step, the image processing device 12 of the caliber fullness calculation device 10 calculates the material cross-sectional area A in the final caliber rolling pass using the above-mentioned formula (2-2). Next, in step S3, the image processing device 12 of the caliber fullness calculation device 10 calculates the caliber fullness μ of the steel material S1 in the final caliber rolling pass based on the material cross-sectional area A calculated in step S2 (material cross-sectional area calculation step) and the caliber cross-sectional area Kk including the portion that becomes the roll gap in the final caliber rolling pass (caliber fullness calculation step).

[0051] The image processing device 12 of the caliber fullness calculation device 10 calculates the caliber fullness μ of the steel material S1 at the final caliber rolling pass using the above-mentioned formula (3) based on the material cross-sectional area A calculated by the above-mentioned formula (2-1) or formula (2-2) and the caliber cross-sectional area Kk including the portion that becomes the roll gap at the final caliber rolling pass. Finally, in step S4, the monitor 13 of the caliber fullness calculation device 10 displays the calculation result at step S3 (display process). Specifically, the monitor 13 displays the caliber fullness μ of the steel material S1 at the final caliber rolling pass calculated by the image processing device 12. In this way, the caliber fullness calculation device 10 calculates the caliber fullness μ of the steel material S1 at the final caliber rolling pass.

[0052] Next, a method for correcting the rough rolling conditions from the caliber filling degree in the manufacturing method of shaped steel according to this embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart for explaining the process flow of changing the roll gap for caliber rolling of the steel material to be next rough rolled, based on the caliber filling degree of the steel material calculated by the caliber filling degree calculation device.

[0053] In the case of H-section steel, the cross-sectional area balance between the flange portion S2F and the web portion S2W of the rough-rolled blank S2 can be determined to determine the appropriate conditions for the BD thickness (=finished web thickness in rough rolling) in the rough rolling of the next steel material S1. If the caliber fullness of the steel material, i.e., the flange fullness μf calculated using equation (4) described below, is smaller than the flange fullness reference value, when the next steel material S1 is roughly rolled under the same rough rolling conditions, the flange fullness μf will again be smaller than the flange fullness reference value. On the other hand, if the flange fullness μf is larger than the flange fullness reference value, when the next steel material S1 is roughly rolled under the same rough rolling conditions, the flange fullness μf will again be larger than the flange fullness reference value. If the flange fullness μf is smaller than the flange fullness standard value and the material is subjected to intermediate rolling and finish rolling under standard rolling conditions, there will be insufficient metal in the flange portion at the product stage, which may result in a thin flange thickness or a small flange width.On the other hand, if the flange fullness μf is larger than the flange fullness standard value, the cross-sectional area of ​​the flange portion will be large, resulting in dimensional defects at the product stage.Therefore, the following rolling adjustments are made to the groove rolling of the steel material to be next rough rolled.

[0054] First, in step S11, the roughing rolling control device (not shown) calculates the flange fullness μf based on the groove fullness μ of the steel material S1 in the final groove rolling pass calculated by the groove fullness calculation device 10, the cross-sectional area Aw of the web portion of the groove in the final groove rolling pass, and the cross-sectional area Af of the flange portion of the groove in the final groove rolling pass, according to the following formula (4) (flange fullness calculation step). μf = μ + (μ - 1) Aw / Af ... (4)

[0055] In the groove in the final groove rolling pass, it can usually be considered that the web portion is 100% filled with the steel material S1, so it is desirable to calculate the flange filling degree μf in the flange portion of the groove and perform step S13 (roll gap changing process) described below. Here, information on the groove filling degree μ of the steel material S1 in the final groove rolling pass calculated by the groove filling degree calculation device 10 is input to the roughing rolling control device from the image processing device 12 of the groove filling degree calculation device 10. In addition, information on the cross-sectional area Aw of the web portion of the groove in the final groove rolling pass and the cross-sectional area Af of the flange portion of the groove in the final groove rolling pass is input to the roughing rolling control device from the host computer 14.

[0056] Next, in step S12, the roughing rolling control device compares the flange fullness μf calculated in step S11 (flange fullness calculation step) with a flange fullness reference value (flange fullness comparison step). The flange fullness reference value is a design value that was determined in advance when rough rolling was performed. Information on this flange fullness reference value is input from the host computer 14 to the roughing rolling control device. Next, in step S13, the roughing rolling control device compares the flange fullness μf with the flange fullness reference value in step S12 (flange fullness comparison step) for groove rolling of the steel material S1 to be next rough rolled. If the flange fullness μf calculated in step S11 (flange fullness calculation step) is smaller than the flange fullness reference value, the roughing rolling control device makes a change to reduce the roll gap in the web portion S1W of the pair of upper and lower rolls 31, 32 that constitute the groove (roll gap change step).

[0057] On the other hand, the roughing rolling control device compares the flange fullness μf with the flange fullness reference value in step S12 (flange fullness comparison step) for the groove rolling of the steel material S1 to be next rough rolled. If the flange fullness μf calculated in step S11 (flange fullness calculation step) is greater than the flange fullness reference value, the roughing rolling control device makes a change to increase the roll gap S (see FIG. 7) in the web portion S1W of the pair of upper and lower rolls 31, 32 that constitute the groove (roll gap change step). Note that if the flange fullness μf calculated in step S11 (flange fullness calculation step) is the same value as the flange fullness reference value, the roll gap S is not changed.

[0058] For example, for a certain steel material S1, if the groove fullness μ of the steel material S1 at the final groove rolling pass calculated by the groove fullness calculation device 10 is 0.93, the groove fullness in the web portion is considered to be 100% full, and therefore the flange fullness μ f in the flange portion is considered to be less than 0.93. Here, for example, in equation (4), when Aw / Af is 1 and the overall groove fullness μ is 0.93, μ f = 0.86. In this case, in step S11, the roughing rolling control device calculates the flange fullness μ f = 0.86.

[0059] Then, in step S12, the roughing rolling control device compares the flange fullness μf = 0.86 calculated in step S11 with the flange fullness reference value. Here, it is assumed that the flange fullness reference value is 0.90 when the web thickness after rough rolling is 50 mm. In this case, in step S13, the roughing rolling control device compares the flange fullness μf = 0.86 calculated in step S11 with the flange fullness reference value = 0.90. As a result, the flange fullness μf = 0.86 is smaller than the flange fullness reference value = 0.90, so a change is made to reduce the roll gap S in the web portion S1W of the pair of upper and lower rolls 31, 32 that constitute the groove.

[0060] Specifically, since the flange fullness μf / flange fullness reference value = 0.86 / 0.90 and the cross-sectional area of ​​the flange portion S1F is 0.86 / 0.90, if the thickness of the web portion S1W is 50 × 0.86 / 0.90 = 47.8 mm, the cross-sectional areas of the flange portion S2F and the web portion S2W of the rough shaped steel billet S2 after rough rolling can be balanced. Therefore, the roll gap S in the web portion S1W of the pair of upper and lower rolls 31, 32 constituting the caliber is reduced from the initial standard web thickness after rough rolling of 50 mm so that the web thickness after rough rolling of the next material (the BD as-received thickness in rough rolling of the next steel material S1 (= the finish web thickness in rough rolling)) is 47.8 mm. This allows the cross-sectional areas of the flange portion S2F and web portion S2W of the rough steel billet S2 after rough rolling to be balanced when performing groove rolling on the steel material to be next rough rolled, and allows intermediate rolling and finish rolling to be performed to produce H-shaped steel with excellent dimensional accuracy.

[0061] Next, a method for correcting intermediate rolling conditions based on the caliber fullness in the manufacturing method of shaped steel according to this embodiment will be described with reference to Fig. 10. Fig. 10 is a flowchart for explaining the flow of a process for changing the difference in the thickness reduction rate between the flange portion and the web portion in the first pass in the intermediate rolling process for rolling a roughly rolled rough shaped steel billet, based on the caliber fullness of the steel material calculated by the caliber fullness calculation device.

[0062] In the intermediate rolling of the rough steel billet S2 for which the caliber fullness μ of the steel material S1 in the final caliber rolling pass has been calculated, the following rolling adjustments can be made. If the flange fullness μf calculated using the same formula (4) as above is smaller than the flange fullness standard value, when the material is intermediate rolled and finish rolled under the standard rolling conditions, there will be insufficient metal in the flange portion at the product stage, which may result in a thin flange thickness or a small flange width. On the other hand, if the flange fullness μf is larger than the flange fullness standard value, the cross-sectional area of ​​the flange portion will be large, resulting in dimensional defects at the product stage. Therefore, the following rolling adjustments are made in the intermediate rolling of the rough steel billet S2.

[0063] First, in step S21, the intermediate universal rolling control device (not shown) calculates the flange fullness μf based on the groove fullness μ of the steel material S1 at the final groove rolling pass calculated by the groove fullness calculation device 10, the cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and the cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, based on the same formula (4) as above (flange fullness calculation process). Here, information on the groove fullness μ of the steel material S1 at the final groove rolling pass calculated by the groove fullness calculation device 10 is input to the intermediate universal rolling control device from the image processing device 12 of the groove fullness calculation device 10. In addition, information on the cross-sectional area Aw of the web portion of the groove at the final groove rolling pass and the cross-sectional area Af of the flange portion of the groove at the final groove rolling pass is input to the intermediate universal rolling control device from the host computer 14.

[0064] Next, in step S22, the intermediate universal rolling control device compares the flange fullness μf calculated in step S21 (flange fullness calculation process) with a flange fullness reference value. The flange fullness reference value is a design value determined in advance when rough rolling is performed. Information on this flange fullness reference value is input from the host computer 14 to the intermediate universal rolling control device. Next, in step S23, if the flange fullness μf calculated in step S22 (flange fullness calculation process) is smaller than the flange fullness reference value, the intermediate universal rolling control device changes the reduction rate difference η to be smaller than the reference reduction rate difference condition (reduction rate difference change process). Here, the reduction rate difference η is the difference (= rf - rw) between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass of the intermediate universal rolling process in the intermediate rolling process for rolling the rough-rolled blank S2.

[0065] Here, the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W are respectively expressed by the following equations: rf = (entry side thickness of flange portion S2F - delivery side thickness of flange portion S2F) / entry side thickness × 100 (%) rw = (entry side thickness of web portion S2W - delivery side thickness of web portion S2W) / entry side thickness × 100 (%) By adjusting this reduction rate difference η to be smaller than the standard reduction rate difference condition, metal flow from the web portion S2W to the flange portion S2F is promoted, and the ratio of the cross-sectional areas of the flange portion S2F and the web portion S2W is improved. As a result, dimensional defects of the H-shaped steel H at the product stage can be suppressed.

[0066] On the other hand, for the first pass of the intermediate universal rolling process, if the flange fullness μf calculated in step S22 (flange fullness calculation process) is greater than the flange fullness reference value, the intermediate universal rolling control device changes the reduction rate difference η to be greater than the reference reduction rate difference condition (reduction rate difference change process). Note that if the flange fullness μf calculated in step S22 (flange fullness calculation process) is the same as the flange fullness reference value, the reduction rate difference η is not changed. This adjustment to increase the reduction rate difference η to be greater than the reference reduction rate difference condition promotes metal flow from the flange portion S2F to the web portion S2W, improving the cross-sectional area ratio of the flange portion S2F to the web portion S2W. As a result, dimensional defects of the H-beam H at the product stage can be suppressed.

[0067] For example, for a certain steel material S1, in step S21, the intermediate universal rolling control device calculates the flange fullness μf to be 0.93 using equation (4). On the other hand, assume that the flange fullness reference value is set to 0.95. In this case, in step S22, the intermediate universal rolling control device compares the flange fullness μf = 0.93 calculated in step S21 with the flange fullness reference value = 0.95. Then, in step S23, the intermediate universal rolling control device changes the reduction rate difference η (= rf - rw) between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass of the intermediate universal rolling process so that the reduction rate difference η is smaller than the standard reduction rate difference condition. In step S22, the flange fullness μf=0.93 calculated in step S21 is compared with the flange fullness reference value=0.95, and it is found that the flange fullness μf=0.93 is smaller than the flange fullness reference value=0.95.

[0068] Specifically, the ratio Bf of the cross-sectional area of ​​the flange portion S1F in the final groove rolling pass to the reference value is 0.98 (=0.93 / 0.95) because the flange fullness μf is 0.93 and the flange fullness reference value is 0.95. According to this ratio Bf, the adjustment amount Δη (%) of the reduction rate difference η between the thickness reduction rate rf of the flange portion S2F in the first pass and the thickness reduction rate rw of the web portion S2W is calculated based on the following formula (5): Δη (%) = -α(1 - Bf) × 100 ... (5) In formula (5), α is a positive proportionality constant.

[0069] Here, since Bf = 0.98, if α1, then Δη = -2 (%). Based on this result, the reduction rate difference η between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass of the intermediate universal rolling process is adjusted to be 2% smaller than the standard reduction rate difference condition, i.e., the reduction rate rw of the web portion S2W is adjusted to be 2% larger (strong reduction) relative to the thickness reduction rate rf of the flange portion S2F. The second and third passes of the intermediate universal rolling process may be adjusted to strongly reduce the web portion S2W by 1% and 0.5%, respectively. This adjustment promotes metal flow from the web portion S2W to the flange portion S2F and improves the cross-sectional area ratio of the flange portion S2F to the web portion S2W. As a result, dimensional defects of the H-beam H at the product stage can be suppressed.

[0070] Thus, the method for calculating the caliber fullness in caliber rolling of shaped steel according to this embodiment includes a measurement length calculation step (step S1) for calculating the measurement length L, which is the length of the rough shaped steel billet S2 after the final caliber rolling pass, and a material cross-sectional area calculation step (step S2) for calculating the material cross-sectional area A in the final caliber rolling pass. The method for calculating the caliber fullness in caliber rolling of shaped steel also includes a caliber fullness calculation step (step S3) for calculating the caliber fullness μ of the steel material S1 in the final caliber rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation step (step S2) and the cross-sectional area Kk of the caliber including the portion that becomes the roll gap in the final caliber rolling pass. In the material cross-sectional area calculation step, the material cross-sectional area A in the final caliber rolling pass is calculated by dividing the volume of the rough shaped steel billet S2 after the final caliber rolling pass, excluding the crop portion C, by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step. This makes it possible to accurately calculate the groove filling degree μ of the steel material S1 at the final groove rolling pass in groove rolling of the structural steel.

[0071] Furthermore, according to the method for calculating the caliber fullness in caliber rolling of shaped steel according to this embodiment, when tongue cutting is not performed after the rough rolling process, the material cross-sectional area calculation process calculates the material cross-sectional area A in the final caliber rolling pass using the above-mentioned formula (2-1), and the caliber fullness calculation process calculates the caliber fullness μ of the steel material S1 in the final caliber rolling pass using the above-mentioned formula (3). This makes it possible to accurately calculate the caliber fullness μ of the steel material S1 in the final caliber rolling pass in caliber rolling when tongue cutting is not performed after the rough rolling process.

[0072] Furthermore, according to the method for calculating the caliber fullness in caliber rolling of shaped steel according to this embodiment, when tongue cutting is performed after the rough rolling process, the measurement length calculation process calculates the measurement length L, which is the length of the rough shaped steel billet S2 after tongue cutting. Furthermore, in the material cross-sectional area calculation process, the material cross-sectional area A in the final caliber rolling pass is calculated using the above-mentioned formula (2-2), and in the caliber fullness calculation process, the caliber fullness μ of the steel material S1 in the final caliber rolling pass is calculated using the above-mentioned formula (3). This makes it possible to accurately calculate the caliber fullness μ of the steel material S1 in the final caliber rolling pass in caliber rolling when tongue cutting is performed after the rough rolling process.

[0073] Furthermore, the manufacturing method for structural steel according to this embodiment includes a flange fullness calculation step (step S11) for calculating the flange fullness μf based on the groove fullness μ of the steel material S1 at the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel, the cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and the cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the above-mentioned formula (4). The manufacturing method for structural steel also includes a flange fullness comparison step (step S12) for comparing the flange fullness μf calculated in the flange fullness calculation step (step S11) with a flange fullness reference value. Furthermore, the manufacturing method for shaped steel includes a roll gap change step (step S13) in which, for the groove rolling of the steel material to be next roughly rolled, if the flange fullness μf calculated in the flange fullness calculation step (step S11) is smaller than the groove fullness reference value, the roll gap in the web portion of the pair of upper and lower rolls 31, 32 constituting the groove is changed to be smaller, and if the flange fullness μf calculated in the flange fullness calculation step (step S11) is greater than the groove fullness reference value, the roll gap is changed to be larger. As a result, the flange fullness μf calculated from the groove fullness μ of the steel material S1 in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of shaped steel is used to modify the rolling conditions for the groove rolling of the steel material to be next roughly rolled, and shaped steel with excellent dimensional accuracy can be manufactured.

[0074] Furthermore, the manufacturing method for structural steel according to this embodiment includes a flange fullness calculation step (step S21) for calculating the flange fullness μf based on the groove fullness μ of the steel material at the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel, the cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and the cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the above-mentioned formula (4). The manufacturing method for structural steel also includes a flange fullness comparison step (step S22) for comparing the flange fullness μf calculated in the flange fullness calculation step (step S21) with a flange fullness reference value. The method for manufacturing the section steel also includes a reduction rate difference change step (step S23) in which, if the flange fullness μf calculated in the flange fullness calculation step (step S21) is smaller than a flange fullness reference value, the reduction rate difference η is changed to be smaller than a reference reduction rate difference condition, and, if the flange fullness μf calculated in the flange fullness calculation step (step S21) is larger than the flange fullness reference value, the reduction rate difference η is changed to be larger than the reference reduction rate difference condition. The reduction rate difference η is the difference (= rf - rw) between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass in the intermediate rolling step in which the rough-rolled rough shaped steel billet S2 is rolled. This allows the flange fullness μf calculated from the groove fullness μ of the steel material at the final groove rolling pass, calculated using a method for calculating the groove fullness in groove rolling of structural steel, to be used to modify the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel piece S2 is rolled, thereby producing structural steel with excellent dimensional accuracy.

[0075] Although the embodiments of the present invention have been described above, the present invention is not limited thereto and various modifications and improvements can be made. For example, in the above description, a method for calculating the degree of caliber filling in caliber rolling of H-section steel and a method for manufacturing H-section steel have been described, but the present invention may also be applied to other shaped steels such as steel sheet piles and I-section steels other than H-section steels.

[0076] Furthermore, the above description has been given of the change in the reduction ratio difference η (=rf-rw) between the thickness reduction ratio rf of the flange portion S2F and the thickness reduction ratio rw of the web portion S2W in the first pass in the intermediate rolling process for rolling the rough-rolled rough steel billet S2. However, the rolling pass for changing this reduction ratio difference η is particularly effective in the initial pass in the intermediate rolling process, and is not limited to the first pass, as long as it is at least the first pass. For example, the reduction ratio difference η may be changed in the first to third passes in the intermediate rolling process. Furthermore, the flange fullness μf calculated from the caliber fullness μ of the steel material S1 in the final caliber rolling pass calculated by the method for calculating the caliber fullness in caliber rolling of shaped steel is used to correct the rolling conditions for caliber rolling of the steel material to be next rough rolled. However, the groove filling degree μ of the steel material S1 at the final groove rolling pass calculated by the method for calculating the groove filling degree in groove rolling of structural steel may be directly used to modify the rolling conditions for the groove rolling of the steel material to be next roughly rolled.

[0077] That is, the manufacturing method of shaped steel includes a caliber fullness comparison step of comparing the caliber fullness μ of the steel material S1 in the final caliber rolling pass, calculated by the method for calculating the caliber fullness in caliber rolling of shaped steel, with a caliber fullness reference value. The manufacturing method of shaped steel may also include a roll gap change step of narrowing the gap between the pair of upper and lower rolls that constitute the caliber when the caliber fullness μ of the steel material S1 in the final caliber rolling pass is smaller than the caliber fullness reference value, and widening the roll gap when the caliber fullness μ of the steel material S1 in the final caliber rolling pass is greater than the caliber fullness reference value. This allows the manufacturing method of shaped steel to directly use the caliber fullness μ of the steel material S1 in the final caliber rolling pass, calculated by the method for calculating the caliber fullness in caliber rolling of shaped steel, to modify the rolling conditions for the caliber rolling of the steel material to be next roughly rolled, thereby manufacturing shaped steel with excellent dimensional accuracy.

[0078] Furthermore, the rolling conditions in the intermediate rolling process for rolling the roughly rolled raw steel billet S2 are corrected using the flange fullness μf calculated from the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of shaped steel. However, the rolling conditions in the intermediate rolling process for rolling the roughly rolled raw steel billet S2 may also be corrected by directly using the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of shaped steel.

[0079] That is, the manufacturing method of shaped steel includes a groove fullness comparison step of comparing the groove fullness μ of the steel material S1 in the final groove rolling pass, calculated by the method for calculating the groove fullness in groove rolling of shaped steel, with a groove fullness reference value. The manufacturing method of shaped steel may also include a reduction rate difference change step of changing the reduction rate difference η to be smaller than the reference reduction rate difference condition when the groove fullness μ of the steel material S1 in the final groove rolling pass is smaller than the groove fullness reference value, and changing the reduction rate difference η to be larger than the reference reduction rate difference condition when the groove fullness μ of the steel material S1 in the final groove rolling pass is larger than the groove fullness reference value. The reduction rate difference η is the difference (= rf - rw) between the thickness reduction rate rf of the flange portion and the thickness reduction rate rw of the web portion in at least the first pass in the intermediate rolling step of rolling the rough-rolled rough shaped steel billet S2. This allows the groove filling degree μ of the steel material at the final groove rolling pass, calculated using the method for calculating the groove filling degree in groove rolling of structural steel, to be directly used to modify the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel piece S2 is rolled, thereby producing structural steel with excellent dimensional accuracy.

[0080] Furthermore, in groove rolling, the groove rolling pass for calculating the groove fullness μ may be not only the final groove rolling pass, but also any intermediate fill-degree calculation groove rolling pass among a plurality of groove rolling passes. That is, in the method for calculating the groove fullness in groove rolling of a shaped steel, a plurality of groove rolling passes are performed in groove rolling, and in the fill-degree calculation groove rolling pass among the plurality of groove rolling passes for calculating the groove fullness, the steel material S1 has a web portion S1W and a flange portion S2F. The method for calculating the groove fullness includes a measurement length calculation step for calculating a measurement length L, which is the length of the steel material S1 after the fill-degree calculation groove rolling pass. Further, the method for calculating the groove fullness includes a material cross-sectional area calculation step of calculating the material cross-sectional area A in the fullness calculation groove rolling pass by dividing the volume of the steel material S1 after the fullness calculation groove rolling pass excluding the crop portion by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step. Further, the method for calculating the groove fullness may include a groove fullness calculation step of calculating the groove fullness μ of the steel material S1 in the fullness calculation groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation step and the groove cross-sectional area Kk including the portion that becomes the roll gap in the fullness calculation groove rolling pass. This makes it possible to accurately calculate the groove fullness μ of the steel material S1 in the fullness calculation groove rolling pass in groove rolling of shaped steel.

[0081] Furthermore, the measurement length L may be calculated by photographing the rough steel billet S2 with a plurality of photographing cameras 11 and calculating the measurement length L from the plurality of photographed images. Alternatively, the measurement length L may be calculated from the conveying speed of the rough steel billet S2 and the detection results of a hot metal detection sensor (HMD). When using this method for calculating the caliber filling degree in caliber rolling of shaped steel, it is preferable to adopt the following method for manufacturing shaped steel when modifying the rolling conditions in caliber rolling of the steel material to be next rough rolled.

[0082] That is, the manufacturing method of shaped steel includes a caliber fullness comparison step of comparing the caliber fullness μ of the steel material S1 in the fillness calculation caliber rolling pass calculated by the method for calculating the caliber fullness in caliber rolling of shaped steel with a caliber fullness reference value. Also, the manufacturing method of shaped steel includes a roll gap change step of, for caliber rolling of the steel material S1 to be next rough rolled, making a change to reduce the gap between the pair of upper and lower rolls that make up the caliber if the caliber fullness μ of the steel material S1 in the fillness calculation caliber rolling pass is smaller than the caliber fullness reference value, and making a change to increase the roll gap if the caliber fullness μ of the steel material S1 in the fillness calculation caliber rolling pass is larger than the caliber fullness reference value.

[0083] Furthermore, when using the above-mentioned method for calculating the caliber fullness in caliber rolling of shaped steel, it is preferable to adopt the following method for manufacturing shaped steel when modifying the rolling conditions in the intermediate rolling process in which the roughly rolled raw shaped steel billet S2 is rolled. That is, the method for manufacturing shaped steel includes a caliber fullness comparison step in which the caliber fullness μ of the steel material S1 in the fullness calculation caliber rolling pass, calculated by the method for calculating the caliber fullness in caliber rolling of shaped steel, is compared with a caliber fullness reference value. Furthermore, the method for manufacturing shaped steel includes a reduction rate difference change step in which, when the caliber fullness μ of the steel material S1 in the fullness calculation caliber rolling pass is smaller than the caliber fullness reference value, the reduction rate difference η is changed to be smaller than the standard reduction rate difference condition, and when the caliber fullness μ of the steel material S1 in the fullness calculation caliber rolling pass is larger than the caliber fullness reference value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition. The reduction ratio difference η is the difference (=rf-rw) between the flange thickness reduction ratio rf and the web thickness reduction ratio rw in at least the first pass in the intermediate rolling process for rolling the rough-rolled blank S2.

[0084] (1) Evaluation of the degree of groove fullness For an H-section steel having a cross-sectional designation of H700 x 300 x 12 x 25, tongue cutting was performed after rough rolling to measure the length of the rough steel billet S2 and calculate the measured length L, and from this result the material cross-sectional area A was calculated to calculate the degree of groove fullness μ of the steel material S1 in the final groove rolling pass. Then, subsequent rolling of the measured rough steel billet S2 was stopped, the actual cross-sectional shape of the rough steel billet S2 was investigated, the cross-sectional area was measured (the measured cross-sectional area A1 was measured), and the measured degree of groove fullness μ1 was calculated, and the calculation accuracy of the degree of groove fullness μ of the steel material S1 in the final groove rolling pass was evaluated.

[0085] The results were as follows: Mass of rough billet after final caliber rolling pass M (kg): 8450 kg Measurement length L (m): 11.160 m Crop length CL (m): 0.6 m Crop mass CM (kg): 90 kg Tongue cut mass TM (kg): 300 kg Specific gravity γ (kg / m ３ ):7850kg / m ３ Material cross-sectional area A (m ２ ): 0.0972m ２ Hole cross-sectional area Kk (m ２ ): 0.1068m ２ (BD open thickness 45 mm) Hole filling degree μ (-): 0.910 = 91.0% Actual cross-sectional area A1 (m ２ ): 0.0969m ２ Measured hole type filling degree μ1(-): 0.907 = 90.7% The hole type filling degree μ calculated by the method of the present invention was 91.0%, while the measured hole type filling degree μ1 = 90.7%, confirming that the calculation accuracy of the hole type filling degree μ calculated by the method of the present invention is sufficiently accurate.

[0086] (2) Changes in rough rolling conditions <First piece> For an H-beam having a reference material cross-sectional designation of H700 x 300 x 12 x 25, the length of the rough steel billet S2 was measured after rough rolling to calculate the measured length L. From this result, the material cross-sectional area A was calculated, and the caliber fullness μ of the steel material S1 at the final caliber rolling pass was calculated. As described above, the calculated caliber fullness μ of the steel material S1 at the final caliber rolling pass was 91.0%. The measured length of the rough steel billet S2 was then subjected to intermediate rolling and finish rolling to produce the finished H-beam H. The flange width (height of the flange portion F) of this finished H-beam H over the entire longitudinal length was measured, resulting in a range of 297.2 to 297.7 mm and failing the test. The target value for this flange width is 300.0 mm, with an acceptable range of 298.0 to 302.0 mm.

[0087] <Second Example> Example of the Invention Since the caliber filling rate μ of the steel material S1 in the final caliber rolling pass of the first reference material was 91.0%, which was smaller than the caliber filling rate reference value (94%), the rolling conditions (BD finish thickness) in the rough rolling (BD rolling) of the next material with the same cross section were changed from 45 mm to 43.5 mm. In other words, the gap between the pair of upper and lower rolls constituting the caliber in the final caliber rolling pass was changed from 45 mm to 43.5 mm. Then, intermediate rolling and finish rolling were performed on the rough rolled rough steel billet S2 with this rolling condition (BD finish thickness) changed, and the product H-shaped steel H was manufactured. The flange width of this product H-shaped steel H was measured over the entire longitudinal length and was found to be between 300.0 and 300.5 mm, which was acceptable.

[0088] <Second Piece> Comparative Example Based on the actual flange width of the first piece, the rolling conditions (BD finish thickness) for the rough rolling (BD rolling) of the next piece with the same cross section were not changed depending on the caliber filling degree μ of the steel material S1 in the final caliber rolling pass for the first reference piece. Then, for the rough rolled rough steel billet S2 without changing the rolling conditions (BD finish thickness), intermediate rolling was performed by opening the roll gap of the intermediate edging mill 5 by 1.5 mm in the intermediate edging rolling process, and finish rolling was also performed to produce the product H-shaped steel H. The flange width at the longitudinal tip of this product H-shaped steel H was 297.5 mm, the flange width at the longitudinal steady portion was 299.0 mm, and the flange width at the longitudinal tail end was 297.6 mm, and the flange widths at the longitudinal tip and tail ends remained unacceptable. In this way, it has been confirmed that the present invention can directly use the groove filling degree μ of the steel material S1 at the final groove rolling pass calculated using the method for calculating the groove filling degree in groove rolling of structural steel to modify the rolling conditions for the groove rolling of the steel material S1 to be next roughly rolled, thereby producing structural steel with excellent dimensional accuracy.

[0089] (3) Changes in intermediate rolling conditions <Example of the present invention> For an H-section steel having a cross-sectional designation of H900 x 300 x 19 x 40, the length of the rough steel billet S2 was measured after rough rolling to calculate the measured length L, and the material cross-sectional area A was calculated from this result to calculate the caliber filling ratio μ of the steel material S1 at the final caliber rolling pass. Based on this calculated caliber filling ratio μ, the cross-sectional area Aw of the web portion of the caliber at the final caliber rolling pass, and the cross-sectional area Af of the flange portion of the caliber at the final caliber rolling pass, the flange filling ratio μf was calculated according to the above-mentioned formula (4). The calculated flange filling ratio μf was 78.1%.

[0090] The calculated flange fullness μf of 78.1% was compared with the flange fullness reference value of 76.1%, and the calculated flange fullness μf of 78.1% was found to be 1.9% greater than the flange fullness reference value of 76.0%. Because the flange fullness μf was 1.9% greater than the flange fullness reference value, the following adjustment was made to the reduction rate difference η (=rf-rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw in the intermediate universal rolling process for rolling the roughly rolled rough steel billet S2.

[0091] Specifically, the following changes were made: the reduction rate difference η for the first pass in the intermediate universal rolling process was increased by 2.0% compared to the standard reduction rate difference condition; the reduction rate difference η for the second pass in the intermediate universal rolling process was increased by 1.0% compared to the standard reduction rate difference condition; and the reduction rate difference η for the third pass in the intermediate universal rolling process was increased by 0.5% compared to the standard reduction rate difference condition. Subsequent intermediate rolling and finish rolling were then performed to produce the H-beam steel H product. The flange width of this H-beam steel H over its entire longitudinal length was measured, and was found to be between 300.5 and 301.0 mm, passing the test. The target flange width was 300.0 mm, with an acceptable range of 298.0 and 302.0 mm.

[0092] <Comparative Example> Rough rolling was performed under the same conditions as described above, and the calculated flange fullness μf = 78.1% was 1.9% greater than the flange fullness reference value = 76.0%. However, intermediate rolling and finish rolling were performed without changing the intermediate rolling conditions to produce the finished H-shaped steel H. When the flange width of this finished H-shaped steel H was measured over the entire longitudinal length, it varied between 302.5 and 303.0 mm, resulting in failure and requiring finishing treatment. In this way, it was confirmed that shaped steel with excellent dimensional accuracy can be produced by modifying the rolling conditions in the intermediate rolling process in which the rough-rolled raw steel billet S2 is rolled using the flange fullness μf calculated from the caliber fullness μ of the steel material S1 in the final caliber rolling pass, which was calculated using the method for calculating the caliber fullness in caliber rolling of shaped steel.

[0093] REFERENCE SIGNS LIST 1 H-beam rolling equipment 2 Heating furnace 3 Roughing mill 4 Intermediate universal rolling mill 5 Intermediate edging rolling mill 6 Finishing universal rolling mill (finishing rolling mill) 7 Tongue cut saw 10 Groove filling degree calculation device 11 Photography camera 12 Image processing device 13 Monitor 14 Host computer 31 Upper rolling roll 32 Lower rolling roll 33 Groove 41 Horizontal roll 42 Horizontal roll 43 Vertical roll 44 Vertical roll 51 Horizontal roll 52 Horizontal roll 61 Horizontal roll 62 Horizontal roll 63 Vertical roll 64 Vertical roll S1 Steel material S1W Web portion S1F Flange portion S2 Rough billet S2W Web portion S2F Flange portion S3 Rolled material S3W Web portion S3F Flange section H H-shaped steel W Web section F Flange section

Claims

1. A method for calculating the degree of groove fullness in groove rolling of shaped steel that is manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material using a groove to form a rough steel billet of a predetermined cross-sectional shape, an intermediate rolling process in which the rough rolled rough steel billet is rolled to form a rolled material for finish rolling, and a finish rolling process in which the rolled material for finish rolling is finish rolled, wherein in the groove rolling, a plurality of groove rolling passes are performed, and in the final groove rolling pass among the plurality of groove rolling passes, where the degree of groove fullness is calculated, the steel material has a web portion and a flange portion, and a measurement length calculation process in which a measurement length L, which is the length of the rough steel billet after the final groove rolling pass, is calculated; A method for calculating a groove fullness in groove rolling of a structural steel, comprising: a material cross-sectional area calculation process for calculating a material cross-sectional area A in the final groove rolling pass by dividing the volume of the raw steel billet after the final groove rolling pass, excluding the crop portion, by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation process; and a groove fullness calculation process for calculating a groove fullness μ of the steel material in the final groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation process and the groove cross-sectional area Kk including the portion that becomes the roll gap in the final groove rolling pass.

2. If tongue cutting is not performed after the rough rolling process, the material cross-sectional area calculation process calculates the material cross-sectional area A in the final groove rolling pass using the following formula (2-1), and the groove fullness calculation process calculates the groove fullness μ of the steel material in the final groove rolling pass using the following formula (3). A method for calculating the groove fullness in groove rolling of structural steel as described in claim 1. A = {M - CM} / {(L - CL) γ} ... (2-1) μ = A / Kk ... (3) Here, in formulas (2-1) and (3), A: material cross-sectional area in the final caliber rolling pass; M: mass of the rough steel billet after the final caliber rolling pass; CM: crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough steel billet and the mass of the portion that will become the crop at the tail end of the rough steel billet; L: measured length which is the length of the rough steel billet after the final caliber rolling pass; CL: crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough steel billet and the length of the portion that will become the crop at the tail end of the rough steel billet; γ: specific gravity of the rough steel billet μ: caliber filling degree of steel material in the final caliber rolling pass; Kk: caliber cross-sectional area in the final caliber rolling pass including the portion that will become the roll gap.

3. When tongue cutting is performed after the rough rolling process, the measurement length calculation process calculates the measurement length L, which is the length of the rough steel piece after the tongue cutting, the material cross-sectional area calculation process calculates the material cross-sectional area A in the final groove rolling pass using the following formula (2-2), and the groove fullness calculation process calculates the groove fullness μ of the steel material in the final groove rolling pass using the following formula (3). A method for calculating the groove fullness in groove rolling of structural steel as described in claim 1. A = {M - TM - CM} / {(L - CL) γ} ... (2-2) μ = A / Kk ... (3) Here, in formulas (2-2) and (3), A: material cross-sectional area at the final caliber rolling pass M: mass of the rough billet after the final caliber rolling pass TM: tongue cut mass CM: mass of the crop portion, which is the crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough billet and the mass of the portion that will become the crop at the tail end of the rough billet L: measured length, which is the length of the rough billet after the final caliber rolling pass CL: length of the crop portion, which is the crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough billet and the length of the portion that will become the crop at the tail end of the rough billet γ: specific gravity of the rough billet μ: caliber filling degree of the steel material at the final caliber rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap.

4. A method for manufacturing structural steel, comprising: a groove fullness comparison step for comparing the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel as set forth in any one of claims 1 to 3 with a groove fullness reference value; and a roll gap change step for, for groove rolling of the steel material to be subsequently rough rolled, making a change to reduce the gap between a pair of upper and lower rolls constituting the groove if the groove fullness μ of the steel material in the final groove rolling pass is smaller than the groove fullness reference value, and making a change to increase the roll gap if the groove fullness μ of the steel material in the final groove rolling pass is larger than the groove fullness reference value.

5. A flange fullness calculation step of calculating a flange fullness μf based on the groove fullness μ of the steel material at the final groove rolling pass calculated by the method for calculating a groove fullness in groove rolling of structural steel as set forth in any one of claims 1 to 3, a cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and a cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the following formula (4); and a flange fullness comparison step of comparing the flange fullness μf calculated in the flange fullness calculation step with a flange fullness reference value. Next, in regard to the groove rolling of the steel material to be roughly rolled, if the flange fullness μf calculated in the flange fullness calculation step is smaller than the flange fullness reference value, a change is made to reduce the roll gap in the web portion of the pair of upper and lower rolls constituting the groove, and if the flange fullness μf calculated in the flange fullness calculation step is larger than the flange fullness reference value, a change is made to increase the roll gap. μf = μ + (μ - 1) Aw / Af ... (4) 6. A method for manufacturing shaped steel, comprising: a groove fullness comparison step of comparing the groove fullness μ of the steel material in the final groove rolling pass calculated by the method for calculating groove fullness in groove rolling of shaped steel as set forth in any one of claims 1 to 3 with a groove fullness reference value; and a reduction rate difference change step of changing the reduction rate difference η (= rf - rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw of at least the first pass in an intermediate rolling step of rolling the rough rolled rough steel billet, so that if the groove fullness μ of the steel material in the final groove rolling pass is smaller than the groove fullness reference value, the reduction rate difference η is changed to be smaller than the standard reduction rate difference condition, and if the groove fullness μ of the steel material in the final groove rolling pass is larger than the groove fullness reference value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition.

7. A flange fullness calculation step of calculating a flange fullness μf based on the groove fullness μ of the steel material at the final groove rolling pass calculated by the method for calculating a groove fullness in groove rolling of structural steel as set forth in any one of claims 1 to 3, a cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and a cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the following formula (4); and a flange fullness comparison step of comparing the flange fullness μf calculated in the flange fullness calculation step with a flange fullness reference value. and a reduction rate difference changing step of changing the reduction rate difference η (=rf-rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw in at least a first pass in an intermediate rolling step of rolling the rough-rolled blank, so that the reduction rate difference η is smaller than a standard reduction rate difference condition if the flange fullness μf calculated in the flange fullness calculation step is smaller than the flange fullness standard value, and so that the reduction rate difference η is larger than the flange fullness standard value if the flange fullness μf calculated in the flange fullness calculation step is larger than the flange fullness standard value. μf=μ+(μ-1)Aw / Af (4) 8. A method for calculating a groove fullness in groove rolling of shaped steel that is manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material using a groove to form a rough steel billet of a predetermined cross-sectional shape, an intermediate rolling process in which the rough rolled rough steel billet is rolled to form a rolled material for finish rolling, and a finish rolling process in which the rolled material for finish rolling is finish rolled, wherein in the groove rolling, a plurality of groove rolling passes are performed, and in a fillness calculation groove rolling pass that calculates the groove fullness of any intermediate one of the plurality of groove rolling passes, the steel material has a web portion and a flange portion, and a measurement length calculation process that calculates a measurement length L, which is the length of the steel material after the fillness calculation groove rolling pass; A method for calculating the groove fullness in groove rolling of structural steel, comprising: a material cross-sectional area calculation process for calculating the material cross-sectional area A in the fullness calculation groove rolling pass by dividing the volume of the steel material after the fullness calculation groove rolling pass excluding the crop portion by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation process; and a groove fullness calculation process for calculating the groove fullness μ of the steel material in the fullness calculation groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation process and the groove cross-sectional area Kk including the portion that becomes the roll gap in the fullness calculation groove rolling pass.

9. A method for manufacturing structural steel, comprising: a groove fullness comparison process for comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel as described in claim 8 with a groove fullness reference value; and a roll gap change process for, for groove rolling of the steel material to be subsequently rough rolled, making a change to reduce the gap between a pair of upper and lower rolls constituting the groove if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is smaller than the groove fullness reference value, and making a change to increase the roll gap if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is greater than the groove fullness reference value.

10. A method for manufacturing a shaped steel, comprising: a groove fullness comparison step for comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating groove fullness in groove rolling of shaped steel as set forth in claim 8 with a groove fullness reference value; and a reduction rate difference change step for changing the reduction rate difference η (= rf - rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw of at least the first pass in an intermediate rolling step for rolling the roughly rolled rough shaped steel billet, if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is smaller than the groove fullness reference value, to make the reduction rate difference η smaller than a reference reduction rate difference condition, and if the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass is larger than the groove fullness reference value, to make the reduction rate difference η larger than the reference reduction rate difference condition.

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