Method of calculating degree of fullness of caliber in caliber rolling of shaped steel and method of production of shaped steel

Abstract

To provide a method for calculating the degree of filling of a caliber in the caliber rolling of a shape steel by which the degree of filling of the caliber of a steel stock in the caliber rolling of the shape steel is accurately calculated, and to provide a method for manufacturing the shape steel.SOLUTION: The method includes a material cross-sectional area calculating step (step S2) of calculating a material cross-sectional area A in the final caliber pass by dividing a volume of the rough billet S1 after the final caliber pass excluding the crop portion C by a value obtained by subtracting the crop length CL from the measured length L, and a caliber filling degree calculating step (step S2) of calculating a caliber filling degree μ of the steel material S1 in the final caliber pass based on the material cross-sectional area A and a caliber cross-sectional area Kk including a portion to be a roll gap in the final caliber pass. S3 S2.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[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. [Background technology]

[0002] Generally, shaped steel such as H-beams is manufactured by hot rolling steel materials such as blooms, slabs, beam blanks, etc. Hot rolling of shaped steel includes a rough rolling process, an intermediate rolling process, and a finish rolling process. In the rough rolling process, rough rolling called groove rolling is performed in a breakdown rolling mill. In this groove rolling, a pair of upper and lower rolls with grooves called grooves are used to roughly roll the steel material to a predetermined cross-sectional shape. In the intermediate rolling process, the steel material rough rolled to a predetermined cross-sectional shape in the rough rolling process is rolled by 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 by a finish universal rolling mill to produce shaped steel with the product dimensions.

[0003] 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. BACKGROUND ART Conventionally, a method for measuring the length of a hot rolled elongated material is known, for example, as disclosed in Patent Document 1.

[0004] The method for measuring the length of hot long materials described in Patent Document 1 is a method for measuring the length of hot long materials conveyed along a conveying path. The method detects that the hot long materials have been conveyed within the field of view of a single imaging device that captures a specific area of ​​the conveying path and has an imaging field that covers the entire length of the hot long materials. Upon detecting that the hot long materials have been conveyed within the field of view, the method acquires a still image of the hot long materials captured by the imaging device, and calculates the length of the hot long materials from the longitudinal position of the hot long materials 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 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 materials within a specific area.

[0005] 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 degree of groove filling 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 steel section product. For this reason, it is necessary to understand the cross-sectional shape of the steel material after groove rolling. BACKGROUND ART Conventionally, a cross-sectional shape profile measuring method disclosed in Patent Document 2, for example, is known as a method for measuring the cross-sectional shape of a hot-rolled steel material.

[0006] The cross-sectional shape profile measurement method shown in Patent Document 2 involves placing a laser rangefinder on both sides of the object to be measured so that it can travel back and forth, rotating the laser rangefinder on the outbound and inbound journeys to change the direction of the optical axis and scan the object to be measured, 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. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-55833 [Patent Document 2] Japanese Patent Application Publication No. 10-239026 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the conventional hot elongated material length measuring method disclosed in Patent Document 1 and the cross-sectional shape profile measuring method disclosed in Patent Document 2 have the following problems. That is, in the case of the method for measuring the length of a hot elongated material shown in Patent Document 1, although the length of the hot elongated material can be calculated, it is not possible to calculate the degree of groove filling of the steel material during groove rolling.

[0009] Furthermore, in the case of the cross-sectional shape profile measurement method shown in Patent Document 2, it is possible to derive the cross-sectional shape profile of the object to be measured, and therefore it is possible to determine the cross-sectional shape of the rolled material after groove rolling. However, this cross-sectional shape profile measurement 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 in that the measurement accuracy is insufficient for determining the degree of groove filling of the steel material in groove rolling.

[0010] 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. [Means for solving the problem]

[0011] 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.

[0012] In this method for calculating the groove filling degree in groove rolling of structural steel, if tongue cutting is not performed after the rough rolling process, it is preferable that in the material cross-sectional area calculation process, the material cross-sectional area A in the final groove rolling pass is calculated using the following formula (2-1), and in the groove filling degree calculation process, the groove filling degree μ of the steel material in the final groove rolling pass is calculated using the following formula (3).

[0013] A={M-CM} / {(L-CL)·γ} …(2-1) μ = A / Kk …(3)

[0014] Here, in the formula (2-1) and the formula (3), A: material cross-sectional area at the final groove rolling pass M: Mass of the blank after the final groove rolling pass CM: Crop amount expressed as the sum of the mass of the part at the leading end of the rough billet that will become the crop and the mass of the part at the tail end of the rough billet that will become the crop L: Measurement length, which is the length of the blank after the final groove rolling pass CL: Crop length expressed as the sum of the length of the part that will become the crop at the leading end of the rough billet and the length of the part that will become the crop at the tail end of the rough billet γ: specific gravity of rough steel billet μ: Groove filling degree of steel material at the final groove rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap is.

[0015] Furthermore, in the method for calculating the groove fullness in groove rolling of structural steel, if tongue cutting is performed after the rough rolling process, it is preferable that the measurement length calculation process calculates the measurement length L, which is the length of the rough steel billet 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).

[0016] A={M-TM-CM} / {(L-CL)·γ} …(2-2) μ = A / Kk …(3)

[0017] Here, in the formula (2-2) and the formula (3), A: material cross-sectional area at the final groove rolling pass M: Mass of the blank after the final groove rolling pass TM: Tongue cut mass CM: Mass of the cropped portion, which is the sum of the mass of the portion at the leading end of the rough billet that will become the crop and the mass of the portion at the tail end of the rough billet that will become the crop L: Measurement length, which is the length of the blank after the final groove rolling pass CL: Length of the cropped portion, which is the sum of the length of the portion that will become the crop at the leading end of the rough shaped billet and the length of the portion that will become the crop at the tail end of the rough shaped billet γ: specific gravity of rough steel billet μ: Groove filling degree of steel material at the final groove rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap is.

[0018] 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.

[0019] 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 the 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 that constitute 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.

[0020] μf=μ+(μ-1)Aw / Af …(4)

[0021] In addition, a manufacturing method for structural 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 structural 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.

[0022] 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, 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 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.

[0023] 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.

[0024] 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.

[0025] In addition, a manufacturing method for structural steel according to another aspect of the present invention is summarized as including 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 the groove rolling of structural steel described above with a groove fullness reference value, and a reduction rate difference change process 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 process for 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. [Effects of the Invention]

[0026] 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. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic diagram of an H-beam rolling facility to which a method for manufacturing an H-beam as shaped steel according to an embodiment of the present invention is applied. [Figure 2] FIG. 10 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 filling degree in groove rolling and the cross-sectional shape of the steel material. [Figure 3] FIG. 10 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 filling degree in groove rolling and the cross-sectional shape of the steel material. [Figure 4]This explains the intermediate rolling process and the finish rolling process, where (a) is a cross-sectional view for explaining the intermediate universal rolling process in the intermediate rolling process, (b) is a cross-sectional view for explaining the intermediate edging rolling process in the intermediate rolling process, and (c) is a cross-sectional view for explaining the finish rolling process. [Figure 5] FIG. 1 is a diagram showing a schematic configuration of a groove fullness calculation device that calculates a groove fullness in groove rolling. [Figure 6] 10 is a diagram for explaining the vertical position of a photographing camera constituting the caliber filling degree calculation device relative to a raw steel billet. FIG. [Figure 7] FIG. 10 is a diagram for explaining the cross-sectional area of ​​the groove in the final groove rolling pass. [Figure 8] 1 is a flowchart for explaining a processing flow in a groove fullness calculation device showing a method for calculating a groove fullness in groove rolling. [Figure 9] 10 is a flowchart for explaining the flow of a process 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. [Figure 10] This is a flowchart to explain the process flow for changing the difference in the reduction ratio between the flange portion thickness reduction ratio and the web portion thickness reduction ratio in the first pass in the 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. DETAILED DESCRIPTION OF THE INVENTION

[0028] 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.

[0029] In addition, the drawings are schematic, and therefore it should be noted that the relationship between thickness and planar dimensions, ratios, etc. may differ from the actual relationship, and the drawings may also contain parts where the relationship and ratio of dimensions differ from each other.

[0030] The H-beam rolling equipment 1 shown in Figure 1 is composed of a heating furnace 2, a roughing mill 3, an intermediate universal rolling mill 4 and an intermediate edging rolling mill 5 as intermediate rolling mills, and a finishing universal rolling mill (finishing rolling mill) 6 as a finishing rolling mill, arranged in this order from upstream to downstream. The heating furnace 2 heats the steel material S1 to a predetermined temperature, which is to be subjected to rough rolling by the roughing mill 3. The roughing mill 3 rough rolls the steel material S1 conveyed on table rollers (not shown) from the heating furnace 2 to produce a rough steel billet S2 (rough rolling step).

[0031] In the rough rolling process, for example, as shown in Figures 2 and 3, groove rolling is performed in which the steel material S1 is roughly rolled into a rough steel piece S2 of 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, multiple groove rolling passes are performed, and as shown in Figures 2 and 3, for example, in the final groove rolling pass among the multiple 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.

[0032] As shown in FIG. 4(a), the rough-rolled billet S2 has a web portion S2W and a flange portion S2F. As shown in FIGS. 1 and 5, the billet S2 has a predetermined length in the direction from rear to front, which is the conveying direction of the billet S2, and a portion that will become crop C1 is formed at its leading end (leading end) and a portion that will become crop C2 is formed at its trailing end (rear end). The length of the 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 billet S2 and the portion that will become crop C2 at the trailing end of the billet S2 are combined to form the crop portion C. The length CL1 of the portion that will become crop C1 at the leading end of the billet S2 and the length CL2 of the portion that will become crop C2 at the trailing end of the billet S2 are combined to form the crop length CL of the crop portion C.

[0033] 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.

[0034] 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.

[0035] 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 approximate product dimensions referred to here refer to dimensions that allow the rolled material to be made into the product dimensions in the finish rolling process.

[0036] The intermediate rolling process includes an intermediate universal rolling process using an intermediate universal rolling mill 4 shown in FIG. 4(a) and an intermediate edging rolling process using an intermediate edging rolling mill 5 shown in FIG. 4(b). 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.

[0037] In the intermediate universal rolling process using the intermediate universal rolling mill 4, multiple passes of rolling are performed using reverse rolling, and as shown in Figure 4(a), the circumferential surfaces of the horizontal rolls 41, 42 roll down the entire height 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 sides of the horizontal rolls 41, 42 roll down the flange portion S2F in the plate thickness direction.

[0038] In addition, the intermediate edging rolling mill 5 is installed downstream of the intermediate universal rolling mill 4, and as shown in Figure 4(b), it has a pair of upper and lower horizontal rolls 51, 52, each of which has a large diameter roll section and a small diameter roll section 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 a pair of upper and lower horizontal rolls 51, 52 guide the web portion S2W of the rough steel billet S2 that has been subjected to intermediate universal rolling, and the small diameter roll portions press down the end faces of the flange portions S2F in the width direction, turning the rough steel billet S2 into rolled material S3 for finish rolling that has approximate product dimensions.

[0039] In addition, the 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 Figure 4(c), the rolling material S3 for finishing rolling, which has been rolled in the intermediate rolling process to approximately the product dimensions, is finish-rolled to produce H-shaped steel H of the product dimensions (finishing rolling process). H-beam steel H is manufactured through this finishing rolling process.

[0040] 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 a horizontal axis, and a pair of left and right vertical rolls 63, 64 that rotate on a vertical axis. 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 are used to reduce the web portion S3W and flange portion S3F of the rolled material S3 to the thickness of the product dimensions, and the angle of the flange portion S3F is corrected. As a result, an H-beam H having the product dimensions is obtained.

[0041] Here, in the final groove rolling pass in which the groove filling degree in groove rolling in the rough rolling process is calculated, there are areas where the steel material S1 is not filled with respect to the shape of the groove 33, as shown in Fig. 2, for example. In this example, the inner surface portions S1Fa of the left and right flange portions S1F are not filled in the groove 33.

[0042] Furthermore, in the final groove rolling pass in which the groove fullness is calculated in groove rolling in the rough rolling process, for example, as shown in another example in Figure 3, the fullness of the upper end S1Fc of the left flange portion S1F may differ from the fullness of the upper end S1Fc of the right flange portion S1F. The fullness of the upper end S1Fc of the left flange portion S1F is smaller than the fullness of the upper end S1Fc of the right flange portion S1F. Note that rolling using a groove 33 as shown in Figure 3 is also used for straight steel sheet piles in addition to H-shaped steel.

[0043] The filling rate of the steel material S1 in 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).

[0044] For example, in the rolling of H-beam 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 slab 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 the intermediate rolling.

[0045] Therefore, it is necessary to determine the extent to which the steel material S1 has filled the groove in the final groove rolling pass of rough rolling, and depending on this groove filling degree, set or modify the rolling conditions for groove rolling of the steel material to be next rough rolled and the rolling conditions for the intermediate rolling process in which the rough rolled rough steel billet is rolled. In this embodiment, the groove fullness of the steel material S1 at the final groove rolling pass in groove rolling is calculated by the groove fullness calculation device 10 shown in FIGS.

[0046] Here, the hole-type fullness calculation device 10 includes a photographing camera 11, an image processing device 12, and a monitor 13, as shown in FIG. 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.

[0047] 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.

[0048] 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, the material cross-sectional area A, and the caliber filling degree μ of the steel material S1 in the final caliber rolling pass in accordance with the instructions of the installed program.

[0049] First, we will explain how the measurement length L is calculated by the image processing device 12. 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 raw steel billet S2 in the left and right directions.

[0050] 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. When calculating this measured length L, the method for measuring the length of a hot long material shown in Patent Document 1 can be adopted. 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 photographing camera 11 and length conversion coefficients that differ in two or more longitudinal regions in the captured image. The length conversion coefficients that differ in two or more longitudinal regions in the captured image are derived in advance by image processing light spot image data obtained by capturing an image of a light spot graduated scale having a scale arranged in the longitudinal direction of the rough steel billet S2 within a specific region.

[0051] 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 at the final groove rolling pass by dividing the volume of the rough shaped 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 shaped steel billet S2 after the tongue cutting, is calculated.

[0052] (1) If the tongue has not been cut When tongue cutting is not performed after rough rolling, the formula for the mass of the rough steel billet S2 is as follows: M = (L - CL) × A × γ + CM ... (1-1) Here, in formula (1-1), M: Mass of the blank S2 after the final groove rolling pass L: Measurement length, which is the length of the blank S2 after the final groove rolling pass A: material cross-sectional area at the final groove rolling pass CL: Length of crop C, which is the sum of the length CL1 of the part that will become crop C1 at the leading end of the rough shaped billet S2 and the length CL2 of the part that will become crop C2 at the tail end of the rough shaped billet S2 γ: specific gravity of rough steel billet S2 CM: Mass of the crop C, which is the amount of cropping expressed as the sum of the mass CM1 of the part that will become the crop C1 at the leading end of the rough shaped billet S2 and the mass CM2 of the part that will become the crop C2 at the tail end of the rough shaped billet S2 By modifying the formula (1-1), the cross-sectional area A of the material in the final groove rolling pass is calculated as follows: A={M-CM} / {(L-CL)·γ} …(2-1) It can be expressed as:

[0053] (2) When tongue cutting is performed and the measured length L, which is the length of the raw 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) Here, in formula (1-2), M: Mass of the blank S2 after the final groove rolling pass TM: Tongue cut mass L: Measurement length, which is the length of the blank S2 after the final groove rolling pass A: material cross-sectional area at the final groove rolling pass CL: Length of crop C, which is the sum of the length CL1 of the part that will become crop C1 at the leading end of the rough shaped billet S2 and the length CL2 of the part that will become crop C2 at the tail end of the rough shaped billet S2 γ: specific gravity of rough steel billet S2 CM: Mass of the crop C, which is the amount of cropping expressed as the sum of the mass CM1 of the part that will become the crop C1 at the leading end of the rough shaped billet S2 and the mass CM2 of the part that will become the crop C2 at the tail end of the rough shaped billet S2 By modifying the formula (1-2), the cross-sectional area A of the material in the final groove rolling pass is calculated as follows: A={M-TM-CM} / {(L-CL)·γ} …(2-2) It can be expressed as:

[0054] Here, in equations (2-1) and (2-2), M is the mass of the raw 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 measured value is input into 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 into 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 raw slab S2 after the final caliber rolling pass by subtracting the calculated scale loss during heating from the input measured value obtained by the weighing machine.

[0055] In addition, in 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 steel billet S2 is input from the host computer 14 to the image processing device 12. In addition, in equations (2-1) and (2-2), CM is the mass of the crop portion C, which is the crop amount expressed as the sum of the mass CM1 of the portion at the leading end of the rough slab S2 that will become crop C1 and the mass CM2 of the portion at the tail end of the rough slab S2 that will become crop C2. CL is the length of the crop portion C, which is the crop length expressed as the sum of the length CL1 of the portion at the leading end of the rough slab S2 that will become crop C1 and the length CL2 of the portion at the tail end of the rough slab S2 that will become crop C2.

[0056] The cropped portion C is the leading and trailing ends of the rough steel billet S2 that will not ultimately become a product, and the tongue cut remains on the rough steel billet S2. In formula (2-2), CM is the mass of the cropped portion C remaining on the rough steel billet S2 after tongue cut, and CL is the length of the cropped 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 cropped portion mass CM and cropped 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 cropped portion mass CM and cropped length CL in formulas (2-1) and (2-2) is input from the host computer 14 to the image processing device 12. The cropped portion C is cut off by sawing (hot sawing or cold sawing) after finish rolling to produce the finished product.

[0057] In addition, in equation (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 equation (2-2) is input from the host computer 14 to the image processing device 12.

[0058] 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 groove filling degree μ of the steel material S1 at the final groove rolling pass using the following equation (3) based on the material cross-sectional area A calculated using equation (2-1) or equation (2-2) and the groove cross-sectional area Kk (see Figures 2, 3, and 7) including the portion that will become the roll gap at the final groove rolling pass.

[0059] μ = A / Kk …(3)

[0060] 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 is the cross-sectional area of ​​the groove 33 including the portion that becomes the roll gap S, as will be explained with reference to FIG. 7. 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 × 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.

[0061] The cross-sectional area Aw of the web portion in the groove 33 can be expressed 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, as Aw=Sw×Bw. 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.

[0062] 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 at the final groove rolling pass calculated by the image processing device 12. Next, a method for calculating the caliber filling degree in caliber rolling of a shaped steel according to this embodiment will be described with reference to a flowchart shown in FIG. 8 illustrating the flow of processing in the caliber filling degree calculation device 10.

[0063] 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 (measured length calculation step). When calculating this measured length L, first, the photographing camera 11 of the caliber fullness calculation device 10 photographs the entire length of the rough shaped billet S2 after rough rolling. Next, the image processing device 12 of the caliber fullness calculation device 10 processes the photographed image by the photographing camera 11 to calculate the measured length L, which is the length of the rough shaped billet S2 after the final caliber rolling pass. The method of calculating this measured length L is as described above.

[0064] Next, in step S2, the image processing device 12 of the groove fullness calculation device 10 calculates the material cross-sectional area A at 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 measured length L calculated in step S1 (measurement length calculation process) (material cross-sectional area calculation process).

[0065] Here, if tongue cutting is not performed after rough rolling, in the material cross-sectional area calculation process, the image processing device 12 of the groove fullness calculation device 10 calculates the material cross-sectional area A at the final groove rolling pass using the above-mentioned formula (2-1).

[0066] On the other hand, if 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, in the material cross-sectional area calculation process, the image processing device 12 of the groove fullness calculation device 10 calculates the material cross-sectional area A at the final groove rolling pass using the above-mentioned formula (2-2).

[0067] Next, in step S3, the image processing device 12 of the groove fullness calculation device 10 calculates the groove fullness μ of the steel material S1 at the final groove rolling pass based on the material cross-sectional area A calculated in step S2 (material cross-sectional area calculation process) and the groove cross-sectional area Kk including the portion that will become the roll gap at the final groove rolling pass (groove fullness calculation process). The image processing device 12 of the groove fullness calculation device 10 calculates the groove fullness μ of the steel material S1 at the final groove rolling pass using the above-mentioned equation (3) based on the material cross-sectional area A calculated using the above-mentioned equation (2-1) or equation (2-2) and the groove cross-sectional area Kk including the portion that becomes the roll gap at the final groove rolling pass.

[0068] Finally, in step S4, the monitor 13 of the caliber fullness calculation device 10 displays the calculation result in step S3 (display step). 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.

[0069] In this manner, the caliber fullness calculation device 10 calculates the caliber fullness μ of the steel material S1 in the final caliber rolling pass. Next, a method for correcting the rough rolling conditions from the caliber fullness 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 flow of a process for changing the roll gap for caliber rolling of the steel material to be next rough rolled, based on the caliber fullness of the steel material calculated by the caliber fullness calculation device.

[0070] 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 groove 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 section 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 section will be large, resulting in dimensional defects at the product stage. Therefore, the following rolling adjustments are made for the groove rolling of the steel material that will be rough rolled next.

[0071] First, in step S11, the rough 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 following equation (4) (flange fullness calculation process).

[0072] μf=μ+(μ-1)Aw / Af …(4)

[0073] In the groove at the final groove rolling pass, it can usually be considered that the web portion is filled with 100% steel material S1, so it is desirable to calculate the flange filling degree μf at the flange portion of the groove and perform step S13 (roll gap changing process) described below. 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 rough 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 from the host computer 14 to the rough rolling control device.

[0074] 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 is determined in advance when roughing is performed. Information on this flange fullness reference value is input from the host computer 14 to the roughing rolling control device.

[0075] Next, in step S13, the rough rolling control device compares the flange fullness μf with the flange fullness reference value in step S12 (flange fullness comparison process) for the groove rolling of the steel material S1 to be next rough rolled, and if the flange fullness μf calculated in step S11 (flange fullness calculation process) is smaller than the flange fullness reference value, it makes a change to reduce the roll gap in the web portion S1W of the pair of upper and lower rolls 31, 32 that make up the groove (roll gap change process).

[0076] 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 rough rolled next, and if the flange fullness μf calculated in step S11 (flange fullness calculation step) is greater than the flange fullness reference value, it 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 make up 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.

[0077] For example, for a certain steel material S1, if the caliber fullness μ of the steel material S1 at the final caliber rolling pass calculated by the caliber fullness calculation device 10 is 0.93, the caliber fullness in the web portion is considered to be 100% full, and therefore the flange fullness μ 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 caliber fullness μ is 0.93, μf = 0.86. In this case, in step S11, the roughing rolling control device calculates the flange fullness μf = 0.86.

[0078] 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 set to 0.90 when the web thickness after rough rolling is 50 mm. In this case, in step S13, the rough rolling control device compares the flange fullness μf = 0.86 calculated in step S11 with the flange fullness reference value = 0.90, and since the flange fullness μf = 0.86 is smaller than the flange fullness reference value = 0.90, it makes a change to reduce the roll gap S in the web portion S1W of the pair of upper and lower rolls 31, 32 that make up the groove.

[0079] 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 set to 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 groove 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 (BD as-received thickness in rough rolling of the next steel material S1 (=finished web thickness in rough rolling)) is 47.8 mm.

[0080] 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.

[0081] Next, a method for correcting intermediate rolling conditions based on the caliber fullness in the manufacturing method for 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.

[0082] In the intermediate rolling of the rough steel billet S2 after calculating the caliber filling degree μ of the steel material S1 in the final caliber rolling pass, 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 subjected to intermediate rolling and finish rolling under the standard rolling conditions, there will be insufficient metal in the flange portion at the product stage, which may result in a thinner flange thickness or a smaller flange width. On the other hand, if the flange fullness μf is greater than the flange fullness standard value, the cross-sectional area of ​​the flange portion will be larger, resulting in dimensional defects at the product stage. Therefore, the following rolling adjustments are made during the intermediate rolling of the rough steel billet S2.

[0083] 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, using the same formula (4) as described above (flange fullness calculation process).

[0084] 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 from the host computer 14 to the intermediate universal rolling control device.

[0085] Next, in step S22, the intermediate universal rolling control device compares the flange fullness μf calculated in step S21 (flange fullness calculation step) with a flange fullness reference value. 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 intermediate universal rolling control device.

[0086] Next, 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, which rolls the roughly rolled rough steel billet S2, to be smaller than the standard reduction rate difference condition if the flange fullness μf calculated in step S22 (flange fullness calculation process) is smaller than the flange fullness standard value (rolling rate difference change process).

[0087] 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 formulas.

[0088] rf = (inlet thickness of flange S2F - outlet thickness of flange S2F) / inlet thickness x 100 (%) rw = (thickness of entrance side of web S2W - thickness of exit side of web S2W) / thickness of entrance side × 100 (%)

[0089] By adjusting the reduction ratio difference η to be smaller than the standard reduction ratio difference condition, metal flow from the web S2W to the flange S2F is promoted, improving the cross-sectional area ratio between the flange S2F and the web S2W. As a result, dimensional defects in the H-beam H can be reduced at the product stage.

[0090] 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 (rolling rate difference change process). Note that if the flange fullness μf calculated in step S22 (flange fullness calculation process) is the same value as the flange fullness reference value, the rolling rate difference η is not changed.

[0091] By adjusting the reduction ratio difference η to be larger than the standard reduction ratio difference condition, metal flow from the flange S2F to the web S2W is promoted, improving the cross-sectional area ratio between the flange S2F and the web S2W. As a result, dimensional defects in the H-beam H can be reduced at the product stage. 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, it is assumed that the flange fullness reference value is set to 0.95.

[0092] 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 compares the flange fullness μf = 0.93 calculated in step S21 with the flange fullness standard value = 0.95, and since the flange fullness μf = 0.93 is smaller than the flange fullness standard value = 0.95, it 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 in the intermediate universal rolling process so that the reduction rate difference η is smaller than the standard reduction rate difference condition.

[0093] 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).

[0094] Δη(%)=-α(1-Bf)×100 …(5) In equation (5), α is a positive proportionality constant.

[0095] Here, since Bf = 0.98, if α1, then Δη = -2(%). From this result, the rolling reduction 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 rolling reduction difference condition, that is, the rolling reduction rate rw of the web portion S2W is adjusted to be 2% larger (strongly reduced) relative to the thickness reduction rate rf of the flange portion S2F. The second and third passes of the intermediate universal rolling process may also be adjusted so that the web portion S2W is strongly reduced by 1% and 0.5%, respectively.

[0096] This adjustment promotes metal flow from the web S2W to the flange S2F, improving the cross-sectional area ratio between the flange S2F and the web S2W, thereby reducing dimensional defects in the H-beam H at the product stage.

[0097] 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 billet S2 after the final caliber rolling pass, a material cross-sectional area calculation step (step S2) for calculating the material cross-sectional area A at the final caliber rolling pass, and a caliber fullness calculation step (step S3) for calculating the caliber fullness μ of the steel material S1 at 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 at the final caliber rolling pass. In the material cross-sectional area calculation step, the material cross-sectional area A at the final caliber rolling pass is calculated by dividing the volume of the rough shaped 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.

[0098] This makes it possible to accurately calculate the caliber filling degree μ of the steel material S1 in the final caliber rolling pass in caliber rolling of the shaped steel. In addition, according to the method for calculating the groove fullness in groove rolling of structural steel in this embodiment, if tongue cutting is not performed after the rough rolling process, the material cross-sectional area calculation process uses the above-mentioned 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 above-mentioned formula (3) to calculate the groove fullness μ of the steel material S1 in the final groove rolling pass.

[0099] This makes it possible to accurately calculate the groove filling degree μ of the steel material S1 in the final groove rolling pass in groove rolling when tongue cutting is not performed after the rough rolling process.

[0100] In addition, according to the method for calculating the groove fullness in groove rolling of structural steel in 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 steel billet S2 after tongue cutting, the material cross-sectional area calculation process calculates the material cross-sectional area A in the final groove rolling pass using the above-mentioned formula (2-2), and the groove fullness calculation process calculates the groove fullness μ of the steel material S1 in the final groove rolling pass using the above-mentioned formula (3).

[0101] This makes it possible to accurately calculate the groove fullness μ of the steel material S1 in the final groove rolling pass in groove rolling when tongue cutting is performed after the rough rolling process.

[0102] In addition, according to the method for manufacturing structural steel of this embodiment, it includes a flange fullness calculation process (step S11) in which the flange fullness μf is calculated 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, based on the above-mentioned equation (4), and a flange fullness comparison process (step S12) in which the flange fullness μf calculated in the flange fullness calculation process (step S11) is compared with a flange fullness standard value. In addition, the manufacturing method for the steel section also includes a roll gap change process (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 process (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 that constitute the groove is changed to be smaller, and if the flange fullness μf calculated in the flange fullness calculation process (step S11) is larger than the groove fullness reference value, the roll gap is changed to be larger.

[0103] This allows the flange filling degree μf calculated from 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 be used to modify the rolling conditions for the groove rolling of the steel material to be next roughly rolled, thereby producing structural steel with excellent dimensional accuracy.

[0104] In addition, according to the method for manufacturing structural steel of this embodiment, it includes a flange fullness calculation process (step S21) in which the flange fullness μf is calculated 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, based on the above-mentioned equation (4), and a flange fullness comparison process (step S22) in which the flange fullness μf calculated in the flange fullness calculation process (step S21) is compared with a flange fullness standard value. In addition, the manufacturing method of the steel section also includes a reduction rate difference change process (step S23) in which, regarding 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 in the intermediate rolling process in which the roughly rolled rough steel block S2 is rolled, if the flange fullness μf calculated in the flange fullness calculation process (step S21) is smaller than the flange fullness standard value, the reduction rate difference η is changed to be smaller than the standard reduction rate difference condition, and if the flange fullness μf calculated in the flange fullness calculation process (step S21) is larger than the flange fullness standard value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition.

[0105] This allows the flange filling degree μf calculated from 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 used to modify the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled, thereby producing structural steel with excellent dimensional accuracy.

[0106] Although the embodiment of the present invention has been described above, the present invention is not limited to this and various modifications and improvements can be made.

[0107] For example, in the above explanation, a method for calculating the degree of groove filling in groove rolling of H-shaped steel and a method for manufacturing H-shaped steel were described, but the present invention may also be applied to other steel shapes such as steel sheet piles and I-shaped steel other than H-shaped steel.

[0108] Furthermore, although 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 blank S2 has been described, the initial passes in the intermediate rolling process are particularly effective as rolling passes for changing this reduction ratio difference η, and are 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.

[0109] In addition, the flange filling degree μf calculated from 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 is used to correct the rolling conditions for the groove rolling of the steel material to be next rough rolled, but 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 also be directly used to correct the rolling conditions for the groove rolling of the steel material to be next rough rolled.

[0110] In other words, the manufacturing method for structural steel may include a groove fullness comparison process in which 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, is compared with a groove fullness reference value, and a roll gap change process in which, for groove rolling of the steel material S1 to be next rough rolled, if the groove fullness μ of the steel material S1 at the final groove rolling pass is smaller than the groove fullness reference value, the pair of upper and lower roll gaps that make up the groove are changed to be smaller, and if the groove fullness μ of the steel material S1 at the final groove rolling pass is larger than the groove fullness reference value, the roll gap is changed to be larger.

[0111] This allows 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 be directly used to modify the rolling conditions for the groove rolling of the steel material to be next roughly rolled, thereby producing structural steel with excellent dimensional accuracy.

[0112] In addition, the flange filling degree μf calculated from the groove filling degree μ of the steel material at the final groove rolling pass calculated by the method for calculating the groove filling degree in groove rolling of structural steel is used to correct the rolling conditions at the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled, but the groove filling degree μ of the steel material at the final groove rolling pass calculated by the method for calculating the groove filling degree in groove rolling of structural steel may also be directly used to correct the rolling conditions at the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled.

[0113] In other words, the manufacturing method for structural steel may include a groove fullness comparison process in which 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 structural steel, is compared with a groove fullness standard value, and a reduction rate difference change process in which, for the reduction rate 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 the intermediate rolling process in which the roughly rolled rough steel billet S2 is rolled, if the groove fullness μ of the steel material S1 in the final groove rolling pass is smaller than the groove fullness standard 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 S1 in the final groove rolling pass is larger than the groove fullness standard value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition.

[0114] 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 shaped steel, to be directly used to modify the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled, thereby producing shaped steel with excellent dimensional accuracy.

[0115] In addition, in groove rolling, the groove rolling pass for calculating the groove fullness μ may not only be the final groove rolling pass, but also any intermediate groove rolling pass for calculating the fullness among multiple groove rolling passes.

[0116] In other words, in a method for calculating the groove fullness in groove rolling of structural steel, multiple groove rolling passes are performed in the groove rolling, and in a fillness calculation groove rolling pass among the multiple groove rolling passes, which calculates the groove fullness, the steel material S1 has a web portion S1W and a flange portion S2F. The method for calculating the groove fullness may include a measurement length calculation process for calculating a measurement length L, which is the length of the steel material S1 after the fullness calculation groove rolling pass; a material cross-sectional area calculation process for calculating the material cross-sectional area A at 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 process; and a groove fullness calculation process for calculating the groove fullness μ of the steel material S1 at 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 cross-sectional area Kk of the groove including the portion that becomes the roll gap in the fullness calculation groove rolling pass.

[0117] This makes it possible to accurately calculate the caliber fullness μ of the steel material S1 in the caliber fullness calculation rolling pass in caliber rolling of the shaped steel.

[0118] Furthermore, the measurement length L may be calculated by photographing the rough shaped 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 shaped steel billet S2 and the detection result of the hot metal detector (HMD).

[0119] When using this method for calculating the degree of groove filling in groove rolling of structural steel, it is preferable to adopt the following manufacturing method of structural steel when modifying the rolling conditions in groove rolling of the steel material to be next roughly rolled.

[0120] In other words, the method for manufacturing structural steel includes a groove fullness comparison process in which the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel is compared with a groove fullness reference value, and a roll gap change process in which, for groove rolling of the steel material S1 to be next rough rolled, if the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass is smaller than the groove fullness reference value, the pair of upper and lower roll gaps that make up the groove are changed to be smaller, and if the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass is larger than the groove fullness reference value, the roll gap is changed to be larger.

[0121] Furthermore, when using the above-mentioned method for calculating the degree of groove filling in groove rolling of shaped steel, it is preferable to adopt the following manufacturing method of shaped steel when modifying the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled.

[0122] In other words, the method for manufacturing structural steel includes a groove fullness comparison process for comparing the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel with a groove fullness standard value, and a reduction rate difference change process for changing the reduction rate 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 the intermediate rolling process for rolling the roughly rolled rough steel billet S2, so that if the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass is smaller than the groove fullness standard 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 S1 in the fill-degree calculation groove rolling pass is larger than the groove fullness standard value, the reduction rate difference η is changed to be larger than the standard reduction rate difference condition. [Example]

[0123] (1) Evaluation of hole filling For H-shaped steel with a cross-sectional designation of H700 x 300 x 12 x 25, tongue cutting was performed after rough rolling was completed, the length of the rough steel billet S2 was measured, and the measured length L was calculated.From this result, the cross-sectional area A of the material was calculated, and the groove filling degree μ of the steel material S1 at the final groove rolling pass was calculated. Then, subsequent rolling of the measured rough steel piece S2 was stopped, the actual cross-sectional shape of the rough steel piece S2 was investigated, the cross-sectional area was measured (the measured cross-sectional area A1 was measured), the measured groove fullness μ1 was calculated, and the calculation accuracy of the groove fullness μ of the steel material S1 in the final groove rolling pass was evaluated.

[0124] The results were as follows: Mass of the rough billet after the final groove rolling pass M (kg): 8450 kg Measurement length L (m): 11.160 m Crop length CL(m):0.6m Crop mass (kg): 90 kg Tongue cut mass TM (kg): 300 kg Specific gravity of rough steel billet 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 thickness 45mm) Pore ​​filling degree μ(-):0.910=91.0% Measured cross-sectional area A1 (m 2 ):0.0969m 2 Actual hole filling rate μ1(-): 0.907 = 90.7% The hole filling rate μ calculated by the method of the present invention was 91.0%, while the actual hole filling rate μ1 was 90.7%, confirming that the calculation accuracy of the hole filling rate μ calculated by the method of the present invention is sufficient.

[0125] (2) Change in rough rolling conditions <1st piece> Reference material For an H-shaped steel having a 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, and from this result the cross-sectional area A was calculated to calculate the groove filling ratio μ of the steel material S1 at the final groove rolling pass. As mentioned above, the calculated groove filling ratio μ of the steel material S1 at the final groove rolling pass was 91.0%. Then, the measured length of the rough steel billet S2 was subjected to intermediate rolling and finish rolling to produce the H-beam steel H product. When the flange width (height of flange part F) of this product was measured over the entire length of the H-beam H, it fluctuated between 297.2 and 297.7 mm, failing the test. The target value for this flange width is 300.0 mm, and the acceptable range is 298.0 to 302.0 mm.

[0126] <2nd item> Example of the present invention Since the groove filling rate μ of the steel material S1 in the final groove rolling pass of the first reference material was 91.0%, which was smaller than the groove 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 that make up the groove in the final groove rolling pass was changed to be smaller from 45 mm to 43.5 mm. Then, the rough rolled rough steel billet S2 was subjected to intermediate rolling and finish rolling under the changed rolling conditions (BD finish thickness), and the H-beam steel H was manufactured as a product. When the flange width of this product was measured over the entire length of the H-beam H, it was found to be between 300.0 and 300.5 mm, which was acceptable.

[0127] <2nd example> Comparative example Based on the actual flange width of the first piece, rough rolling was performed on the next piece without changing the rolling conditions (BD finishing thickness) for rough rolling (BD rolling) of the next piece with the same cross section, depending on the groove filling degree μ of the steel material S1 at the final groove rolling pass for the first reference piece. Then, without changing the rolling conditions (BD finishing thickness), the rough rolled rough steel billet S2 was subjected to intermediate rolling by opening the roll gap of the intermediate edging rolling mill 5 by 1.5 mm in the intermediate edging rolling process, and then to finish rolling to produce the product H-shaped steel H. The flange width at the longitudinal tip of the H-shaped steel H of this product was 297.5 mm, the flange width at the longitudinal steady part 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 end remained unacceptable.

[0128] 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.

[0129] (3) Change 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 cross-sectional area A of the material was calculated from this result to calculate the groove filling ratio μ of the steel material S1 at the final groove rolling pass. Based on this calculated groove filling ratio μ, 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, the flange filling ratio μf was calculated according to the above-mentioned formula (4). The calculated flange filling ratio μf was 78.1%.

[0130] The calculated flange fullness μf=78.1% was compared with the flange fullness reference value=76.1%, and the calculated flange fullness μf=78.1% was 1.9% greater than the flange fullness reference value=76.0%. Therefore, since the flange fullness μf is 1.9% greater than the flange fullness reference value, the following adjustments were made to 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 the intermediate universal rolling process for rolling the roughly rolled rough steel billet S2.

[0131] That is, 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 carried out to produce the final H-section steel H. Measurements of the flange width of this product's H-beam along its entire length revealed that it was between 300.5 and 301.0 mm, passing. The target flange width is 300.0 mm, with an acceptable range of 298.0 to 302.0 mm.

[0132] <Comparative Example> Rough rolling was performed under the same conditions as above, and the calculated flange fullness μf = 78.1% was 1.9% greater than the flange fullness reference value = 76.0%, but intermediate rolling and finish rolling were performed without changing the intermediate rolling conditions, and the product H-shaped steel H was manufactured. When the flange width of this product was measured over the entire length of the H-beam H in the longitudinal direction, it was found to be between 302.5 and 303.0 mm, which meant it failed and required maintenance. In this way, it was confirmed that by using the flange filling degree μf calculated from 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, the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel billet S2 is rolled can be modified, and structural steel with excellent dimensional accuracy can be manufactured. [Explanation of symbols]

[0133] 1. H-beam rolling equipment 2 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 and sew 10. Hole-type filling degree calculation device 11. Camera 12 Image processing device 13 Monitors 14 Upper computer 31 Upper rolling roll 32 Lower rolling roll 33 hole type 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 Section S1F flange S2 Rough shaped steel billet S2W Web Department S2F flange S3 Rolled material S3W Web Department S3F flange HH section steel W Web Department F flange

Claims

1. A method for calculating the degree of groove filling in groove rolling of shaped steel manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material into a rough steel billet having a predetermined cross-sectional shape using a groove; an intermediate rolling process in which the rough rolled rough 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 the steel material has a web portion and a flange portion in a final groove rolling pass among the plurality of groove rolling passes, which is used to calculate the groove filling degree, 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 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 step; A method for calculating the degree of groove fullness in groove rolling of structural steel, characterized in that it includes a groove fullness calculation process for calculating the degree of 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 will be the roll gap in the final groove rolling pass.

2. After the rough rolling process, if tongue cutting is not performed, 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) to calculate the groove fullness μ of the steel material in the final groove rolling pass. 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 the formula (2-1) and the formula (3), A: Material cross-sectional area in the final groove rolling pass M: Mass of the blank after the final groove rolling pass CM: Crop amount expressed as the sum of the mass of the part at the leading end of the rough billet that will become the crop and the mass of the part at the tail end of the rough billet that will become the crop L: Measurement length, which is the length of the rough steel billet after the final groove rolling pass CL: Crop length expressed as the sum of the length of the portion that will become the crop at the leading end of the rough shaped billet and the length of the portion that will become the crop at the tail end of the rough shaped billet γ: Specific gravity of rough steel billet μ: groove filling degree of steel material at the final groove rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap is.

3. When tongue cutting is performed after the rough rolling process, in the measurement length calculation process, the measurement length L, which is the length of the rough steel billet after the tongue cutting, is calculated, and in the material cross-sectional area calculation process, the material cross-sectional area A in the final groove rolling pass is calculated using the following formula (2-2). In the groove fullness calculation process, the groove fullness μ of the steel material in the final groove rolling pass is calculated using the following formula (3). A method for calculating the groove fullness in groove rolling of shaped steel, as described in claim 1. A={M-TM-CM} / {(L-CL)・γ}...(2-2) μ=A / Kk…(3) Here, in the formula (2-2) and the formula (3), A: Material cross-sectional area in the final groove rolling pass M: Mass of the blank after the final groove rolling pass TM: Tongue cut mass CM: Mass of the cropped portion, which is the amount of cropping expressed as the sum of the mass of the portion of the rough billet that will become the crop at the leading end and the mass of the portion of the rough billet that will become the crop at the tail end L: Measurement length, which is the length of the rough steel billet after the final groove rolling pass CL: Length of the cropped portion, which is the sum of the length of the portion that will become the crop at the leading end of the rough shaped billet and the length of the portion that will become the crop at the tail end of the rough shaped billet γ: Specific gravity of rough steel billet μ: groove filling degree of steel material at the final groove rolling pass Kk: Cross-sectional area of ​​the groove in the final groove rolling pass, including the portion that becomes the roll gap is.

4. A groove fullness comparison step of comparing 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 shaped steel according to any one of claims 1 to 3 with a groove fullness reference value; Next, regarding the groove rolling of the steel material to be roughly rolled, if the groove filling degree μ of the steel material in the final groove rolling pass is smaller than the groove filling degree reference value, the pair of upper and lower roll gaps that constitute the groove are changed to be smaller, and if the groove filling degree μ of the steel material in the final groove rolling pass is larger than the groove filling degree reference value, the roll gap is changed to be larger.

5. 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 shaped steel according to any one of claims 1 to 3, 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, calculate the flange fullness μ f based on the following 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; Next, in the groove rolling of the steel material to be roughly rolled, if the flange fullness μf calculated in the flange fullness calculation process is smaller than the flange fullness reference value, the roll gap in the web portion of the pair of upper and lower rolls that make up the groove is made smaller, and if the flange fullness μf calculated in the flange fullness calculation process is larger than the flange fullness reference value, the roll gap is made larger. A method for manufacturing structural steel, characterized in that it includes a roll gap change process. μf=μ+(μ-1)Aw / Af...(4)

6. A groove fullness comparison step of comparing 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 shaped steel according to any one of claims 1 to 3 with a groove fullness reference value; and a reduction rate difference change process 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 in at least the first pass in an intermediate rolling process for rolling the rough-rolled rough steel billet, in which 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. 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 shaped steel according to any one of claims 1 to 3, 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, calculate the flange fullness μ f based on the following 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 rolling reduction difference change process for changing the rolling reduction difference η (=rf-rw) between the flange portion thickness reduction rate rf and the web portion thickness reduction rate rw in at least the first pass in an intermediate rolling process for rolling the rough-rolled rough steel billet, such that if the flange fullness μf calculated in the flange fullness calculation process is smaller than the flange fullness reference value, the rolling reduction difference η is changed to be smaller than a reference rolling reduction difference condition, and if the flange fullness μf calculated in the flange fullness calculation process 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. μf=μ+(μ-1)Aw / Af...(4)

8. A method for calculating the degree of groove filling in groove rolling of shaped steel manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material into a rough steel billet having a predetermined cross-sectional shape using a groove; an intermediate rolling process in which the rough rolled rough 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 the steel material has a web portion and a flange portion in a fill degree calculation groove rolling pass that calculates an arbitrary groove fill degree among the plurality of groove rolling passes, 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; The volume of the steel material after the fullness calculation groove rolling pass excluding the crop portion is divided by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step, thereby calculating the material cross-sectional area A in the fullness calculation groove rolling pass; A method for calculating the groove fullness in groove rolling of structural steel, characterized in that it includes 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 groove fullness comparison step of comparing the groove fullness μ of the steel material in the groove fullness calculation groove rolling pass calculated by the groove fullness calculation method in groove rolling of shaped steel according to claim 8 with a groove fullness reference value; Next, regarding the groove rolling of the steel material to be rough rolled, 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 pair of upper and lower roll gaps that make up the groove are changed to be smaller, 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 roll gap is changed to be larger.

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

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