WO2026028522A1 - Method for calculating groove filling degree in groove rolling of shaped steel and method for manufacturing shaped steel - Google Patents

Abstract

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

Description

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

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

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 is 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.
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.

2. Description of the Related Art Conventionally, a method for measuring the length of a hot rolled elongated material is known, for example, as disclosed in Patent Document 1.
The method for measuring the length of hot long materials disclosed in Patent Document 1 is a method for measuring the length of hot long materials transported along a transport path. The method detects that the hot long materials have been transported within the field of view of a single imaging device that captures a specific area of the transport path and has an imaging field that covers the entire length of the hot long materials. When the method detects that the hot long materials have been transported within the field of view, it 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 areas in the image. The length conversion coefficients that differ in two or more longitudinal areas 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.

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.

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.
The cross-sectional shape profile measurement method disclosed 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.

JP 2014-55833 A Japanese Patent Application Publication No. 10-239026

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.
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 has the problem that it can only determine the cross-sectional shape at a specific position in the longitudinal direction of the rolled material, and the measurement accuracy is insufficient for determining the degree of groove filling of the steel material in groove rolling.

The present invention has been made to solve this problem, and its purpose is to provide a method for calculating the caliber filling rate in caliber rolling of sectional steel, and a method for manufacturing sectional steel, which can accurately calculate the caliber filling rate of steel material in caliber rolling of sectional steel.

In order to solve the above problem, one embodiment of the present invention provides a method for calculating the degree of groove fullness in groove rolling of structural steel, which 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 roughly 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. In the groove rolling, multiple groove rolling passes are performed, and in the final groove rolling pass among the multiple groove rolling passes in which the degree of groove fullness is calculated, the steel material is rolled into a web portion and a flange portion. The method includes a measurement length calculation step of calculating a measurement length L, which is the length of the rough steel billet after the final caliber rolling pass; a material cross-sectional area calculation step of calculating a material cross-sectional area A at the final caliber rolling pass by dividing the volume of the rough steel billet after the final caliber 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 caliber fullness calculation step of calculating a caliber fullness μ of the steel material at the final caliber rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation step and the caliber cross-sectional area Kk including the portion that will become the roll gap at the final caliber rolling pass.

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

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

Furthermore, a method for manufacturing structural steel according to another aspect of the present invention includes a groove fullness comparison step for comparing the groove fullness μ of the steel material in 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 step for, for groove rolling of the steel material to be subsequently rough rolled, making a change to reduce the gap between the pair of upper and lower rolls that make up the groove if the groove fullness μ of the steel material in the final groove rolling pass is smaller than the groove fullness reference value, and making a change to increase the roll gap if the groove fullness μ of the steel material in the final groove rolling pass is greater than the groove fullness reference value.

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.
μf=μ+(μ-1)Aw/Af...(4)

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

Furthermore, a manufacturing method for structural 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 the groove fullness in groove rolling of structural steel described above, 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, in accordance with the aforementioned 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 steel slab. and a rolling reduction difference changing process for changing the rolling reduction difference η (= rf - rw) between the flange portion thickness reduction rf and the web portion thickness reduction rw in at least the first pass in an intermediate rolling process for rolling the flange. 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 the 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.

Furthermore, a method for calculating the degree of groove fullness in groove rolling of shaped steel according to another aspect of the present invention is a method for calculating the degree of groove fullness in groove rolling of shaped steel that is manufactured through a rough rolling process in which groove rolling is performed to roughly roll a steel material into a rough steel billet of a predetermined cross-sectional shape using a groove, an intermediate rolling process in which the roughly 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 fill degree calculation groove rolling pass in which the degree of groove fullness is calculated for any intermediate pass among the plurality of groove rolling passes, the steel material has a web portion and a flange portion, 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.

Furthermore, a method for manufacturing structural steel according to another aspect of the present invention includes a groove fullness comparison step for comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel described above with a groove fullness reference value, and a roll gap change step for, for groove rolling of the steel material to be subsequently rough rolled, making a change to reduce the gap between the pair of upper and lower rolls that make up 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.

In addition, a manufacturing method for structural steel according to another aspect of the present invention is summarized as comprising a groove fullness comparison step of comparing the groove fullness μ of the steel material in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in 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 thickness reduction rate rf of the flange portion and the thickness reduction rate rw of the web portion in at least the first pass in the intermediate rolling step of rolling the roughly rolled rough shaped steel piece, 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 the 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.

The method for calculating the caliber filling rate in caliber rolling of sectional steel and the method for manufacturing sectional steel according to the present invention can accurately calculate the caliber filling rate of the steel material in caliber rolling of sectional steel, and can provide a method for calculating the caliber filling rate in caliber rolling of sectional steel and a method for manufacturing sectional steel.

1 is a schematic diagram of an H-shaped steel rolling facility to which a method for manufacturing an H-shaped steel as shaped steel according to an embodiment of the present invention is applied. 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. 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. 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. FIG. 1 is a diagram showing a schematic configuration of a groove fullness calculation device that calculates a groove fullness in groove rolling. 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. FIG. 10 is a diagram for explaining the cross-sectional area of the groove in the final groove rolling pass. 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. 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. This is a flowchart to explain the process flow for changing the difference in the reduction rate between the flange portion thickness reduction rate and the web portion thickness reduction rate 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.

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.
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.

The rolling equipment 1 for H-section steel shown in FIG. 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, which are arranged in this order from the upstream side to the downstream side.
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 rough rolling mill 3 roughly 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).

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 a groove 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, in the final groove rolling pass among the multiple groove rolling passes, which is used to calculate the groove filling degree, the steel material S1 has a web portion S1W and a flange portion S1F.

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 rough-rolled 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 (front end) and a portion that will become crop C2 is formed at its trailing end (rear end). The length of the rough-rolled billet S2 is measured by a photographing camera 11, which will be described later, and the measured length L is calculated. The portion that will become crop C1 at the leading end of the rough-rolled billet S2 and the portion that will become crop C2 at the trailing end of the rough-rolled billet S2 are combined to form the crop portion C. The length _CL1 of the portion that will become crop C1 at the leading end of the rough-rolled billet S2 and the length _CL2 of the portion that will become crop C2 at the trailing end of the rough-rolled billet S2 are combined to form the crop length CL of the crop portion C.

The technology of the present application can also be applied to products that do not have flanges, as long as the shape can be considered to have a web portion S1W and a flange portion S1F at the rough rolling stage, such as a straight steel sheet pile that has a web portion and joint portions at both ends of the web portion S1W and flange portion S1F at the rough rolling stage. The cross-sectional shape of a 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.

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 with 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 TM.

The intermediate universal rolling mill 4 and the intermediate edging rolling mill 5 are installed downstream of the tongue cut saw 7, and as shown in Figures 4(a) and 4(b), the rough steel billet S2 rough-rolled in the rough rolling process by the roughing mill 3 is rolled into a rolled material S3 having a web portion S3W for finish rolling and a pair of flange portions S3F that have approximately the product dimensions (intermediate rolling process). Note that the approximately product dimensions referred to here mean dimensions that allow the rolled material to be made into the product dimensions in the finish rolling process.
The intermediate rolling process includes an intermediate universal rolling process 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.
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 side surfaces of the horizontal rolls 41, 42 roll down the flange portion S2F in the plate thickness direction.

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

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).
Through this finish rolling process, H-beam steel H is manufactured.
As shown in FIG. 4(c), the finishing universal rolling mill 6 is provided 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.
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 portions 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.

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 and the fullness of the upper end S1Fc of the right flange portion S1F may differ. 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.
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 the finish rolling shown in FIG. 4(c).

For example, in the rolling of H-section steel, as described above, intermediate universal rolling is performed by the intermediate universal rolling mill 4 in the intermediate rolling process. In intermediate universal rolling, as shown in FIG. 4( a), the circumferential surfaces of the horizontal rolls 41 and 42 roll down the entire height of the web portion S2W of the rough steel billet S2 in the thickness direction, and the circumferential surfaces of the vertical rolls 43 and 44 and the side surfaces of the horizontal rolls 41 and 42 roll down the flange portion S2F in the thickness direction. Typically, intermediate universal rolling is performed under conditions such that the thickness reduction rate of the web portion S2W and the thickness reduction rate of the flange portion S2F are approximately equal. However, if the flange fullness (caliber fullness) of the steel material S1 in the rough rolling (final caliber rolling pass) differs from the reference value (it is possible that the flange fullness is greater or smaller than the reference value), the thickness reduction balance in the intermediate universal rolling will not be within the specified range. As a result, the target product cross-sectional dimensions may not be obtained, or the intermediate rolling conditions and finish rolling conditions may become abnormal, making it impossible to perform rolling after the intermediate rolling.
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 degree of groove filling, 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 Figures 1, 5 and 6.
As shown in FIG. 5, the hole-type fullness calculation device 10 includes a photographing camera 11, an image processing device 12, and a monitor 13.
The photographing camera 11 photographs the entire length of the rough-rolled blank S2. As shown in Figures 5 and 6, the photographing camera 11 is installed diagonally above the left side of the rough-rolled blank S2 to be photographed, and photographs the entire length of the rough-rolled blank S2 traveling in the conveying direction after rough rolling.

The image processing device 12 also processes the image captured by the camera 11 to calculate the 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 calculated measured length L minus the crop length CL. 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), which includes the portion that becomes the roll gap at the final caliber rolling pass.

The image processing device 12 is a computer system equipped with an arithmetic processing device. The image processing device 12 performs 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.
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 rough steel billet S2 in the left and right directions.

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 hot long material shown in Patent Document 1 can be adopted. In other words, the measured length L of the rough steel billet S2 is calculated from the longitudinal (left-right) position of the rough steel billet S2 in the image captured by the camera 11 and length conversion coefficients that differ in two or more longitudinal regions in the 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 scale with scales arranged in the longitudinal direction of the rough steel billet S2 within a specific area.

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 steel billet S2 after the final groove rolling pass, excluding the crop portion C, by the value obtained by subtracting the crop length CL from the calculated measured length L. When calculating this material cross-sectional area A, the calculation method for the material cross-sectional area A differs depending on whether tongue cutting is not performed after rough rolling or whether tongue cutting is performed and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated.

(1) When Tongue Cutting Is Not Performed 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 rough steel billet S2 after the final caliber rolling pass L: measured length which is the length of the rough steel billet S2 after the final caliber rolling pass A: material cross-sectional area in the final caliber rolling pass CL: length of the crop portion C, which is the length of the portion that will become the crop C1 at the front end of the rough steel billet S2 _CL1 and the length of the portion that will become the crop C2 at the tail end of the rough steel billet S2 _CL2 γ: specific gravity of the rough steel billet S2 CM: mass of the crop portion C, which is the crop amount which is the sum of the mass CM1 of the portion that will become the crop C1 at the front end of the rough steel billet _S2 and the mass CM2 of the portion that will become the crop _C2 at the tail end of the rough steel billet S2 By modifying formula (1-1), for the material cross-sectional area A in the final caliber rolling pass,
A={M-CM}/{(L-CL)・γ}...(2-1)
It can be expressed as:

(2) When tongue cutting is performed and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated When tongue cutting is performed after rough rolling and the measured length L, which is the length of the rough steel billet S2 after the tongue cutting, is calculated, the formula for the mass of the rough steel billet S2 is as follows.
M-TM=(L-CL)×A×γ+CM…(1-2)
Here, in formula (1-2),
M: mass of the rough slab S2 after the final caliber rolling pass TM: tongue cut mass L: measured length which is the length of the rough slab S2 after the final caliber rolling pass A: material cross-sectional area in the final caliber rolling pass CL: length of the crop portion C, which is the length CL1 of the portion that will become the crop C1 at the front end of the rough slab S2, and the length _CL2 of the portion that will become the crop C2 at the tail end of the rough slab _S2 γ: specific gravity of the rough slab S2 CM: mass of the crop portion C, which is the crop amount which is the sum _CM1 of the portion that will become the crop C1 at the front end of the rough slab S2 and the mass _CM2 of the portion that will become the crop C2 at the tail end of the rough slab S2 By modifying formula (1-2), for the material cross-sectional area A in the final caliber rolling pass,
A={M-TM-CM}/{(L-CL)・γ}...(2-2)
It can be expressed as:

Here, in equations (2-1) and (2-2), M is the mass of the rough steel billet 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 this 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 rough steel billet S2 after the final caliber rolling pass by subtracting the calculated scale loss during heating from the input measured value from the weighing machine.

In addition, in the formulas (2-1) and (2-2), γ is the specific gravity of the rough steel billet S2, which can be exemplified as 7850 kg/ ^m3 for carbon steel. 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 formulas (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 shaped steel billet S2 that will become crop C1 and the mass _CM2 of the portion at the tail end of the rough shaped steel billet 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 shaped steel billet S2 that will become crop C1 and the length CL2 of the portion at the tail end of the rough shaped steel billet _S2 that will become crop C2.

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

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.

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 in the final groove rolling pass using the following formula (3) based on the material cross-sectional area A calculated using formula (2-1) or formula (2-2) and the groove cross-sectional area Kk (see Figures 2, 3, and 7) including the portion that becomes the roll gap in the final groove rolling pass.
μ=A/Kk…(3)

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

The cross-sectional area Aw of the web portion of the groove 33 can be expressed by multiplying the roll gap Sw of the web rolling portion of the groove 33 by the groove width Bw of the web rolling portion of the groove 33, as Aw = Sw x 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.
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 steel section according to this embodiment will be described with reference to a flowchart illustrating the processing flow in the caliber filling degree calculation device 10 shown in FIG. 8 .
First, in step S1, the caliber fullness calculation device 10 calculates the measured length L, which is the length of the rough 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.

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 piece 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).
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 in the final groove rolling pass using the above-mentioned formula (2-1).

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 in the final groove rolling pass using the above-mentioned formula (2-2).
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 aforementioned equation (3) based on the material cross-sectional area A calculated using the aforementioned 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.
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.
In this way, the groove fullness calculation device 10 calculates the groove fullness μ of the steel material S1 at the final groove rolling pass.

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

In the case of H-shaped steel, the cross-sectional area balance between the flange portion S2F and web portion S2W of the rough steel billet S2 after rough rolling 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 standard value, when the next steel material S1 is rough rolled under similar rough rolling conditions, the flange fullness μf will again be smaller than the flange fullness standard value. On the other hand, if the flange fullness μf is greater than the flange fullness standard value, when the next steel material S1 is rough rolled under similar rough rolling conditions, the flange fullness μf will again be greater than the flange fullness standard 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 not be enough metal in the flange section 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 section will be larger, resulting in dimensional defects at the product stage. Therefore, the following rolling adjustments are made to the groove rolling of the steel material that will then be rough rolled.

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 formula (4) (flange fullness calculation process).
μf=μ+(μ-1)Aw/Af...(4)

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

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 to the roughing rolling control device from the host computer 14.
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 constitute the groove (roll gap change process).

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

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

Then, in step S12, the roughing rolling control device compares the flange fullness μf=0.86 calculated in step S11 with a 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 standard value = 0.90, and since the flange fullness μf = 0.86 is smaller than the flange fullness standard 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 constitute the groove mold.

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

Next, a method for correcting intermediate rolling conditions based on the caliber fullness in the manufacturing method for structural steel according to this embodiment will be described with reference to Figure 10. Figure 10 is a flowchart for explaining 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 caliber fullness of the steel material calculated by the caliber fullness calculation device.

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 standard rolling conditions, there will be insufficient metal in the flange portion at the product stage, which may result in a thin flange thickness or a narrow 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 large, 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.

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

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 to the intermediate universal rolling control device from the host computer 14.
Next, in step S23, if the flange fullness μf calculated in step S22 (flange fullness calculation step) is smaller than the flange fullness reference value, the intermediate universal rolling control device changes the reduction rate difference η to be smaller than the reference reduction rate difference condition (reduction rate difference change step). Here, the reduction rate difference η is the difference (=rf-rw) between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass in the intermediate universal rolling step of the intermediate rolling step that rolls the rough-rolled rough steel billet S2.

Here, the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W are respectively expressed by the following equations.
rf = (inlet thickness of flange portion S2F - outlet thickness of flange portion S2F) / inlet thickness x 100 (%)
rw = (inlet thickness of web portion S2W - outlet thickness of web portion S2W) / inlet thickness x 100 (%)
By adjusting the reduction ratio difference η to be smaller than the standard reduction ratio difference condition, metal flow from the web portion S2W to the flange portion S2F is promoted, improving the cross-sectional area ratio between the flange portion S2F and the web portion S2W. As a result, dimensional defects in the H-beam H at the product stage can be suppressed.

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 step) is greater than the flange fullness reference value, the intermediate universal rolling control device changes the reduction rate difference η to be greater than the reference reduction rate difference condition (reduction rate difference change step). Note that if the flange fullness μf calculated in step S22 (flange fullness calculation step) is the same value as the flange fullness reference value, the reduction rate difference η is not changed.
By adjusting the reduction ratio difference η to be larger than the standard reduction ratio difference condition, metal flow from the flange portion S2F to the web portion S2W is promoted, improving the ratio of the cross-sectional areas of the flange portion S2F and the web portion S2W. As a result, dimensional defects in the H-beam H at the product stage can be suppressed.

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.
In this case, in step S22, the intermediate universal rolling control device compares the flange fullness μf=0.93 calculated in step S21 with the flange fullness reference value=0.95.
Then, in step S23, the intermediate universal rolling control device changes the reduction rate difference η (=rf-rw) between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass in the intermediate universal rolling process so that the reduction rate difference η is smaller than the standard reduction rate difference condition. This is because, in step S22, as a result of comparing the flange fullness μf=0.93 calculated in step S21 with the flange fullness reference value=0.95, the flange fullness μf=0.93 is smaller than the flange fullness reference value=0.95.

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

Here, since Bf = 0.98, if α1, then Δη = -2 (%). From this result, the reduction rate difference η between the thickness reduction rate rf of the flange portion S2F and the thickness reduction rate rw of the web portion S2W in the first pass of the intermediate universal rolling process is adjusted to be 2% smaller than the standard reduction rate difference condition, that is, the reduction rate rw of the web portion S2W is adjusted to be 2% larger (strong reduction) relative to the thickness reduction rate rf of the flange portion S2F. The second and third passes of the intermediate universal rolling process may be adjusted so that the web portion S2W is strongly reduced by 1% and 0.5%, respectively.
This adjustment promotes metal flow from the web portion S2W to the flange portion S2F, improving the cross-sectional area ratio between the flange portion S2F and the web portion S2W, thereby reducing dimensional defects in the H-beam H at the final product stage.

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

Furthermore, according to the method for calculating the groove fullness in groove rolling of structural steel according to 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.
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.

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

Furthermore, the manufacturing method for structural steel according to this embodiment includes a flange fullness calculation step (step S11) for calculating the flange fullness μf based on the groove fullness μ of the steel material S1 at the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of structural steel, the cross-sectional area Aw of the web portion of the groove at the final groove rolling pass, and the cross-sectional area Af of the flange portion of the groove at the final groove rolling pass, according to the above-mentioned formula (4). The manufacturing method for structural steel also includes a flange fullness comparison step (step S12) for comparing the flange fullness μf calculated in the flange fullness calculation step (step S11) with a flange fullness reference value. In addition, the manufacturing method for structural steel 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.
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.

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

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

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 raw steel billet S2 has been described, the initial pass in the intermediate rolling process is particularly effective as the rolling pass for changing this reduction ratio difference η, and is not limited to the first pass, as long as it is at least the first pass. For example, the reduction ratio difference η may be changed in the first to third passes in the intermediate rolling process.
Furthermore, the flange fullness μf calculated from the 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 shaped steel is used to correct the rolling conditions for groove rolling of the steel material to be next roughly rolled. However, 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 shaped steel may also be directly used to correct the rolling conditions for groove rolling of the steel material to be next roughly rolled.

That is, the manufacturing method of shaped steel includes a groove fullness comparison step of comparing the groove fullness μ of the steel material S1 in the final groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of shaped steel with a groove fullness reference value.The manufacturing method of shaped steel may also include a roll gap change step of, for groove rolling of the steel material S1 to be next rough rolled, making a change to reduce the gap between the pair of upper and lower rolls that make up the groove if the groove fullness μ of the steel material S1 in the final groove rolling pass is smaller than the groove fullness reference value, and making a change to increase the roll gap if the groove fullness μ of the steel material S1 in the final groove rolling pass is larger than the groove fullness reference value.
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 groove rolling of the steel material to be next roughly rolled, thereby producing structural steel with excellent dimensional accuracy.

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

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

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.
That is, in the method for calculating the groove fullness in groove rolling of a shaped steel, a plurality of groove rolling passes are performed in the groove rolling, and in a fill-degree calculation groove rolling pass among the plurality of 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 includes a measurement length calculation step of calculating a measurement length L, which is the length of the steel material S1 after the fill-degree calculation groove rolling pass. The method for calculating the groove fullness also includes a material cross-sectional area calculation step of calculating the material cross-sectional area A in the fill-degree calculation groove rolling pass by dividing the volume of the steel material S1 after the fill-degree calculation groove rolling pass, excluding the crop portion, by the value obtained by subtracting the crop length CL from the measurement length L calculated in the measurement length calculation step. In addition, the method for calculating the groove fullness may include a groove fullness calculation process for calculating the groove fullness μ of the steel material S1 in the fullness calculation groove rolling pass based on the material cross-sectional area A calculated in the material cross-sectional area calculation process and the groove cross-sectional area Kk including the portion that becomes the roll gap in the fullness calculation groove rolling pass.
This makes it possible to accurately calculate the groove fullness μ of the steel material S1 in the fullness calculation groove rolling pass in groove rolling of the structural steel.

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 results of a hot metal detector (HMD).
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.

In other words, the method for manufacturing structural steel includes a groove fullness comparison step in which the groove fullness μ of the steel material S1 in the fillness calculation groove rolling pass, calculated using the method for calculating the groove fullness in groove rolling of structural steel, is compared with a groove fullness reference value. The method for manufacturing structural steel also includes a roll gap change step 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 fillness 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 fillness calculation groove rolling pass is larger than the groove fullness reference value, the roll gap is changed to be larger.

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 piece S2 is rolled.
That is, the manufacturing method of shaped steel includes a groove fullness comparison step of comparing the groove fullness μ of the steel material S1 in the fill-degree calculation groove rolling pass calculated by the method for calculating the groove fullness in groove rolling of shaped steel with a groove fullness reference value. The manufacturing method of the shaped steel also includes a reduction rate difference change step of changing the reduction rate difference η to be smaller than the standard reduction rate difference condition when 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, and changing the reduction rate difference η to be larger than the standard reduction rate difference condition when 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 reduction ratio difference η is the difference (=rf-rw) between the flange thickness reduction ratio rf and the web thickness reduction ratio rw in at least the first pass in the intermediate rolling process for rolling the rough-rolled blank S2.

(1) Evaluation of groove filling degree 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 piece 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 actual cross-sectional area A1 was measured), the actual 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.

The results were as follows:
Mass M (kg) of raw steel billet after final groove rolling pass: 8450 kg
Measurement length L (m): 11.160 m
Crop length CL (m): 0.6 m
Crop mass CM (kg): 90 kg
Tongue cut mass TM (kg): 300 kg
Specific gravity γ (kg/m ³ ) of rough shaped steel slab: 7850 kg/m ³
Material cross-sectional area A ( ^m2 ): ^0.0972m2
Hole cross-sectional area Kk (m ² ): 0.1068 ^{m 2} (BD open thickness 45 mm)
Pore filling degree μ(-): 0.910=91.0%
Measured cross-sectional area A1 (m ² ): 0.0969 ^{m 2}
Measured 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.

(2) Changes in rough rolling conditions <First 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 material cross-sectional area A was calculated to calculate the groove filling rate μ of the steel material S1 at the final groove rolling pass. The calculated groove filling rate μ of the steel material S1 at the final groove rolling pass was 91.0%, as described above.
The measured rough steel billet S2 was then subjected to intermediate rolling and finish rolling to produce the finished H-beam steel H.
The flange width (height of the flange portion F) of this product was measured over the entire length of the H-beam H in the longitudinal direction and was found to be between 297.2 and 297.7 mm, failing the test. The target flange width is 300.0 mm, with the acceptable range being 298.0 to 302.0 mm.

<Second example> 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 constituting 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 while changing the rolling conditions (BD finish thickness), and the H-beam steel H was manufactured as a product.
The flange width of the H-beam H of this product was measured over the entire length in the longitudinal direction, and was found to be within the range of 300.0 to 300.5 mm, which was acceptable.

<Second piece> 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 finished 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 longitudinal tail end remained unacceptable.
In this way, it has been confirmed that the present invention can directly use the groove filling degree μ of the steel material S1 at the final groove rolling pass calculated using the method for calculating the groove filling degree in groove rolling of structural steel to modify the rolling conditions for the groove rolling of the steel material S1 to be next roughly rolled, thereby producing structural steel with excellent dimensional accuracy.

(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 material cross-sectional area A was calculated from this result to calculate the caliber filling ratio μ of the steel material S1 at the final caliber rolling pass. Based on this calculated caliber filling ratio μ, the cross-sectional area Aw of the web portion of the caliber at the final caliber rolling pass, and the cross-sectional area Af of the flange portion of the caliber at the final caliber rolling pass, the flange filling ratio μf was calculated according to the above-mentioned formula (4). The calculated flange filling ratio μf was 78.1%.

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 adjustment was 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.

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.
Then, intermediate rolling and finish rolling were carried out to produce the H-section steel H as a product.
The flange width of this product was measured over the entire length of the H-beam H in the longitudinal direction and was found to be between 300.5 and 301.0 mm, which was acceptable. The target flange width is 300.0 mm, and the acceptable range is 298.0 to 302.0 mm.

<Comparative Example>
Rough rolling was performed under the same conditions as described above, and the calculated flange fullness μf = 78.1% was 1.9% greater than the flange fullness reference value = 76.0%, 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 was unacceptable and required maintenance.
In this way, it was confirmed that by using the flange fullness μf calculated from the groove fullness μ of the steel material S1 at the final groove rolling pass calculated using the method for calculating the groove fullness in groove rolling of structural steel, the rolling conditions in the intermediate rolling process in which the roughly rolled rough shaped steel piece S2 is rolled can be modified, and structural steel with excellent dimensional accuracy can be manufactured.

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

Claims (10)

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. 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 at the final groove rolling pass; M: mass of the rough steel billet after the final groove rolling pass; CM: crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough steel billet and the mass of the portion that will become the crop at the tail end of the rough steel billet; L: measured length which is the length of the rough steel billet after the final groove rolling pass; CL: crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough steel billet and the length of the portion that will become the crop at the tail end of the rough steel billet; γ: specific gravity of the rough steel billet; μ: groove filling degree of steel material at the final groove rolling pass; Kk: groove cross-sectional area at the final groove rolling pass including the portion that will become the roll gap. 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 at the final groove rolling pass; M: mass of the rough billet after the final groove rolling pass; TM: tongue cut mass; CM: mass of the crop portion, which is the crop amount expressed as the sum of the mass of the portion that will become the crop at the front end of the rough billet and the mass of the portion that will become the crop at the tail end of the rough billet; L: measured length, which is the length of the rough billet after the final groove rolling pass; CL: length of the crop portion, which is the crop length expressed as the sum of the length of the portion that will become the crop at the front end of the rough billet and the length of the portion that will become the crop at the tail end of the rough billet; γ: specific gravity of the rough billet; μ: degree of groove filling of the steel material at the final groove rolling pass; Kk: groove cross-sectional area at the final groove rolling pass, including the portion that will become the roll gap. 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. 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) 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. 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) 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. 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. 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.