JP2003181501A - Method for manufacturing extra thick h shape steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means which can manufacture an extra thick H shape steel by minimizing its defects or by suppressing the defects to the minimum limit. <P>SOLUTION: In the case of manufacturing the extra thick H shape steel by passing a beam blank through a breakdown mill, a combination mill comprising a rough universal mill and an edging mill, and a finish universal mill in this order, the following two stages are implemented, that is, (1) a stage to measure the temperature, the size, and the shape parameter of a finished rolled material rolled by the finish universal mill and (2) the stage to execute return finish rolling by re-adjusting a roll gap of the finish universal mill so as to make the size and the shape parameter of the finished rolled material to satisfy a regulation value when the temperature of the finished rolled material is a transformation point A<SB>1</SB>or more, and, the size and the shape parameter do not satisfy the stipulated value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an H-section steel, and more particularly to a method for producing an extremely thick H-section steel having a very large flange thickness of 40 mm or more.

[0002]

2. Description of the Related Art Generally, H-section steel is made by passing a raw material in the direction of an arrow as shown in FIG. 8 and roughly rolling a beam blank whose cross section is shown in FIG. A combination mill 2 consisting of a mill and an edging mill is used to finish the cross-sectional shape shown in FIG. 9 (b), and this is passed through a finishing universal mill 3 to obtain the shape shown in FIG.
It is manufactured by finishing the final cross-sectional shape consisting of the flange 7 and the web 8 of (c). A hot dimension gauge 4, a thermometer 5, a length gauge 6 and the like are provided on the rear surface of the finishing universal mill 3 so as to measure the dimensions and the like of the product H-section steel.

When manufacturing H-section steel with such an apparatus, the rolling by the finish universal mill 3 is usually performed only in one pass, whereby the final dimension is finished. Such a rolling method is also applied to an H-section steel called an extra-thick H-section steel having a flange thickness of more than 40 mm, but in this case, a forming that causes a flange angle (from (b) to (c in FIG. 9)). ) Step is difficult, the roll angle is reduced in advance in the coarse universal mill 2 to reduce the load on the finishing universal mill 3.

[0004]

However, when an extra-thick H-section steel is manufactured by such a rolling method, first, when the flange is raised in the upright state by the finishing universal mill 3,
There is a problem that the flatness of the outer surface of the flange tends to deteriorate. Secondly, with only one pass in the finishing universal mill, there is a problem that the unevenness of the flange thickness generated in the rough universal mill is likely to remain even after passing through the finishing universal mill. For example, phenomena such as uneven flange thickness where the difference between t ₁ and t ₂ in FIG. 7 becomes large, or defective flange flatness where shrinkage occurs at the root of the web become noticeable. In addition, due to the large thickness of the flange, a deformation called “W-shaped deformation” shown in FIG. 10 or “flange warpage” shown in FIG. 11 occurs. These deformations are also things that cannot be easily corrected in the cold,
In order to respond to the order, the material will have to be remade, which will result in a high production cost and a serious obstacle such as a delay in the delivery date.

The present invention aims to solve the problem in manufacturing such an ultra-thick H-section steel, and manufactures it by eliminating defects in the extra-thick H-section steel as much as possible, or by suppressing defects to the minimum possible extent. It provides the means by which it is possible.

[0006]

The inventors of the present invention, when manufacturing an extremely thick H-section steel, if the temperature of the exit side (rear side) of the finishing universal mill is above a certain temperature, finish rolling again with the finishing universal mill. The present invention has been completed based on the finding that it is possible to rectify a defect in the shape of the product that occurs during the first finish rolling or that remains from the rough rolling stage without difficulty.

Specifically, in manufacturing an extra-thick H-section steel by passing a beam blank through a breakdown mill, a combination mill consisting of a rough universal mill and an edging mill, and a finishing universal mill in this order, (1) the finishing universal mill Measuring the temperature and dimension / shape parameters of the finish rolled material rolled in (2)
When the temperature of the finish rolled material is equal to or higher than the A ₁ transformation point and the dimension / shape parameters do not satisfy the specified values, the rolls of the finish universal mill are configured so that the dimension / shape parameters of the finished rolled material satisfy the specified values. The above problem is solved by performing the step of re-adjusting the gap and performing the re-finishing rolling.

In carrying out the above invention, the above (1)
The steps (2) and (2) can be repeated. As a result, it is possible to correct the remaining defects even if the back finishing rolling is performed.

It is preferable to measure the temperature and dimension / shape parameters of the finish rolled material rolled by the finish universal mill on the rear surface of the finish universal mill. Further, it is preferable to employ a means for opening the roll of the finish universal mill and feeding the finished rolled material rolled by the finish universal mill back to the front surface of the finish universal mill. By these means, it is possible to shorten the time until the finish rolling is performed again, and the return finish rolling can be smoothly performed.

In order to carry out the present invention, a step of measuring the temperature and dimension / shape parameters of the finish rolled material rolled by the finish universal mill on the rear surface of the finish universal mill and, after the measurement, rolling by the finish universal mill. Immediately feeding the finished finish rolled material back to the front surface of the finish universal mill, determining whether or not to perform the finish universal mill rolling again based on the measured value, and performing the finish universal mill for the return finish rolling. It is preferable to sequentially perform the step of adjusting and the step of subjecting the finish-rolled material fed back again to finish rolling.

In the above invention, any one or more of the flange width, the web thickness, the web height, the flange flatness, the as-roll length, and the deviation of the web center of the finished rolled material are used as the dimension and shape parameters. Is preferred.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. The outline of the finishing universal mill according to the present invention is as shown in FIG. As shown here, finish universal rolling is first performed by a normal procedure (Fig. 1 (A)), and the dimension and shape parameters of the obtained H-shaped steel S are measured for necessary items and the finish universal mill is performed. When the measured dimension and shape parameters do not satisfy the regulation, the sheet is reverse-finished and rolled (Fig. 1 (C)). Hereinafter, this operation will be described step by step.

The extra-thick H-section steel to which the present invention is applied preferably has a flange thickness of 40 mm or more, preferably 50 mm or more. This is because such a material has a small temperature drop after leaving the finishing universal mill and is suitable for re-finishing rolling. If the flange thickness is small, the temperature drop after leaving the finishing universal mill is large and the finishing cannot be performed smoothly. However, the present invention can be applied to those having a flange thickness of about 40 mm by taking appropriate temperature drop preventing means such as limiting the rolling length to be short. The flange width and web height are not particularly limited.

The extra-thick H-section steel is mainly rolled using a beam blank as a raw material through a breakdown mill, a combination mill combining a rough universal mill and an edging mill, and a finishing universal mill in this order as usual. . The beam blank as a material is not particularly limited, and includes those manufactured by continuous casting, and those molded from a slab having a rectangular cross section by a slab mill or the like. Further, as for the type of break down mill and combination mill, and the operation method, a method for producing an ordinary thick H-section steel may be adopted.

In carrying out the present invention, first, the temperature of the finish rolled material rolled by the finish universal mill is measured. The temperature is measured in a portion of the finished rolled material that can be represented by the flange temperature, for example, in the flange width direction 1.
/ 4 points, and the temperature of the lowest temperature part of the temperature over the entire length is adopted. As a result, it is possible to prevent the rolling work from becoming difficult or the material from being deteriorated due to the low-temperature rolling during the finish rolling again. This temperature measurement can be performed using the hot thermometer 5 provided on the rear surface of the finishing universal mill shown in FIG. 8, but is not limited thereto. For example, a hot thermometer is also provided on the front surface side of the finishing universal mill. After sending back the finished rolled material (which will be explained later),
Therefore, it may be measured.

For the above-mentioned finish rolled material,
-Measurement of shape parameters is performed. With dimension parameters
The flange width of rolled material, web thickness, web height
As the shape parameter,
The flange flatness of H-section steel, deviation of the web center, etc.
Can be mentioned. In addition, "W-shaped deformation" of the flange (Fig.
10) and deformation called "flange warpage" (Fig. 11)
Can be measured. The azuroll length is the above-mentioned specification.
The total length of the rolled material. What is flange flatness?
S in FIG._max, Ie, the intersection of the flange and the web
The amount of shrinkage on the outer surface of the flange at the point
The deviation of the center means (a in FIG.₁-A _Two) / 2, you
That is, it refers to the deviation of the upper and lower flange leg lengths. The above dimensions
・ Measurement of shape parameters is performed by finishing as shown in Fig.8.
Hot dimension gauge 4, length gauge 6 etc. provided on the rear surface of the niversal mill
Can be done using, but is not necessarily limited to
However, various known means can be used.
It

Based on the above measurement results, the finished rolled material was returned.
Whether or not there is a need for finishing rolling, and whether or not it is appropriate
Is done. First, the temperature of the finish rolled material is
Of A ₁If the transformation temperature has not been reached, return finish
Not suitable for rolling. Something like this
When rolling, the rolling load becomes too large.
This is because the material may be deteriorated. This judgment
Is A₁Process considering the relationship between transformation temperature and composition
It can be done by computer. Therefore,
The temperature of the rolled material is A₁Finish when the temperature is above the transformation point
The rolled material is judged to be suitable for back-finish rolling.
Be done.

On the other hand, the dimension and shape parameters of the finish rolled material are compared with the specified values provided for each finished rolled material, and if the specified values are not satisfied, it is determined that the return finish rolling is required. Here, the specified value means, for example, the lower limit value that S _max should satisfy as a final product if the flange flatness is taken, and if it exceeds the lower limit value, the specified value is not satisfied. If the web thickness is taken, the specified value is satisfied if it is within the target upper and lower limit range. This specified value is for each dimension / shape parameter product.
Also, it can be set for each order lot so that the required quality can be satisfied. It should be noted that this specified value does not have to be set for all the items constituting the dimension / shape parameters, but may be set only for those which are considered necessary for the product.

On the basis of the above judgment result, it is necessary to carry out the return finish rolling, and the finish rolled material which is judged to be suitable for that is subjected to the return finish rolling. This return finish rolling is performed to correct the problems of the size and shape that occurred during the previous finish rolling. Therefore, the finish universal mill readjusts the roll gap so that the dimension and shape parameters of the finish rolled material fall within the specified values by the return finish rolling.

If the size and shape parameters satisfy the specified values, the product is used as it is. If the size / shape parameters do not satisfy the specified values but the temperature is equal to or lower than the A ₁ transformation point, they are sent to the next step, for example, sawing, cooling and straightening.

In the present invention, the temperature and the dimension / shape parameter of the finish rolled material rolled by the finish universal mill as described above are measured, and the temperature of the finish rolled material is equal to or higher than the A ₁ transformation point and the dimension / shape. When the parameter does not satisfy the specified value, the return finish rolling is performed. Usually, such back-finish rolling is usually performed only once, but the above steps can be repeated twice or more to improve the dimensional accuracy.

In carrying out the invention described above, it is preferable from the standpoint of workability to take the steps shown in the diagram of FIG. In this process, on the rear surface of the finishing universal mill, the temperature and dimension / shape parameters of the finished rolled material rolled by the finishing universal mill are measured, and after the measurement,
All the finished rolled materials rolled by the finishing universal mill are immediately sent back to the front surface of the finishing universal mill regardless of the above measured values. At that time, the finishing universal mill opens the roll. Then, the finish-rolled material sent back is made to stand by in front of the finish universal mill.

The measured data of the temperature and the dimension / shape parameter of the rolled material are input to the process computer and compared with the specified values to determine whether or not the return finish rolling is performed. Further, when performing the return finish rolling, the adjustment amount of the roll gap of the finish universal mill is determined and output to the control device of the finish universal mill. On the other hand, when the return finish rolling is not performed, an instruction is given to keep the finish universal mill in an open state.

In response to the above instruction, the roll gap of the finishing universal mill is reset, and then the finish rolling universal rolling is performed on the material to be rolled waiting on the front surface thereof. Alternatively, with the roll of the finishing universal mill in an open state, so-called empty pass is performed.

In the present invention, the adjustment of the roll gap at the time of the return finish rolling will be described below by taking the adjustment of the flange thickness as an example. First, when the flange thickness is excessively large in the first finish rolling (or immediately before the return finish rolling), the roll gap S ₂ is determined as follows. _{S 2 = S 1 - △ a-} △ b + c Here, _{S 1:} the last roll gap set value △ a: Thickness reduction (reduction ratio predetermined value) [Delta] b: roll gap variation due to temperature drop c: mill modulus due to the load variation Amount of change

With respect to the other items, the roll gap of the finishing universal mill is changed so that the specified values can be obtained in the next finishing rolling based on the measured values obtained in the immediately preceding finishing rolling. For example, regarding the web height, the width of the variable width horizontal roll and the position of the vertical roll are adjusted, and regarding the deviation of the web center, the positions of the pass line and the web guide in the vertical direction are adjusted. Regarding these position adjustments, so-called learning control can be performed by analyzing past operation results.

Further, when the rolled material exiting the finish universal mill is found to have a bend exceeding the specified value, the roll guide is set so that the bend is corrected, and the return finish rolling is performed. The straightening of the H-section steel is usually performed cold after the rolling is completed, and thus requires a powerful straightening machine and has a limited amount of straightening, but it is extremely small by performing the back finishing rolling according to the present invention. Bending can be corrected with energy.

[0028]

(Example) (Example 1) By applying the equipment of the rolling mill arrangement shown in Fig. 8, the cross section (572x5) of the H500x500 series is applied.
10 × 60 × 60) was rolled. The rolling process of the breakdown mill and the combination mill is basically the same as that of the prior art, and as a result, an intermediate rolled material with a cross-section balance having a thickness ratio of web and flange of the final product (see FIG.
(Shown in (b)) was obtained. The temperature was 910 ° C. at the 1/4 point of the flange.

First intermediate universal rolling was applied to the obtained intermediate rolled material to obtain a finished rolled material. The dimension of the obtained finish rolled material is shown by a thick line in FIG. As can be seen from FIG. 4, in this first finish rolled material, there was a portion where the flange width was out of the lower limit value. The web height was within the specified range for the entire length of the product. However, this web height can be changed by changing the flange thickness during rerolling.

Therefore, it is necessary to adjust the roll gap of the finishing universal mill so that the flange width falls within the specified value and the web height does not deviate from the specified value by changing the flange thickness, and re-rolling is performed. In particular,
It is as shown below.

(Adjustment of Flange Width) As can be seen from FIG. 5, the amount by which the flange width deviates from the lower limit is Δb. Therefore, the flange thickness reduction amount is set so that the flange width is widened by the corresponding amount in the return finish rolling. With reference to FIG. 5, Δb · t ₂ = K · Δt ₂ · B ₁ Here, K is a coefficient indicating the ratio of replacement by the width of the reduction area and is set for each cross-sectional area.

In this example, Δb = 0.40 mm t ₂ = 60.60 mm B ₁ ≈510 mm K = 0.10 is set, and the flange thickness reduction amount for expanding the flange width by 0.4 mm is Δt ₂ = 0.48 mm.

[0033] As seen by reference to (web height adjustment) 6, the web height width setting of variable width roll of the universal mill A _R and the left flange thickness t _2L, a right flange thickness t Determined by the sum of the _2Rs . In the case of this example, it is not necessary to change the web height from the dimension measurement result shown in FIG. However, in order to change the flange thickness and the web height more accurately with the adjustment of the flange width, the web height is adjusted by Δh in FIG.

In this example, the change amount of the roll width caused by the return finish rolling is ΔA _R = Δh + Δt _2L + Δt _2R , Δh is given as a target value, and Δt _2L and Δt _2L
Since t _2R is given as a flange thickness rolling reduction during finishing rolling back, thereby changing the amount of roll width .DELTA.A _R
Can be calculated. Adjust the roll width of the finishing universal mill by this amount.

[0035] In this example, since it is _{Δh = -0.4mm Δt 2L = Δt 2R} = 0.48mm, the _{ΔA R = -0.4 + 0.48 + 0.48} = 0.56mm. Therefore, the roll width before adjustment 458.66m
The m was adjusted to 459.22 mm, and the roll gap was set to t _2R = t _2L = 60.60 mm and H = 580.42 mm, and the return finish rolling was performed.

(Adjustment of Flange Flatness) Generally, a flange
Poor flatness does not occur as a result of uneven flange thickness.
Often. Therefore, first, finish universal
Roll gap adjustment amount, Δt _2R, Δt_2LIs S
_maxDetermines if it is greater, and if so,
Back-finish rolling to correct flange flatness defects
I will not do it. If small, Δt_2R, Δt
_2LTo S_maxAnd then finish rolling. In this example
If the flange flatness is not correct,
No need for finishing rolling.

When the finish universal mill was readjusted and the back-finish rolling was performed as shown above, as shown in FIG.
As shown by the thin line on the
The width of the left and right flanges and the height of the web could be kept within the specified values over the entire length of the commercialized part.

(Example 2) In producing an H-section steel of the same size as that of Example 1 but having a different flange thickness,
The conventional method of one-pass finishing and the method of performing the back-finishing rolling according to the present invention once or more were applied to a plurality of strips. As a result, the variation in flange thickness was 1.0
What was ~ 1.4mm was settled in about 0.3mm,
In addition, S _max , which is an index of the flange flatness, was 0.8 to 1.2 mm, which was 1.2 to 1.8 mm in the related art, which was about 70%.

[0039]

According to the method of the present invention, an extremely thick H-section steel having good dimensional accuracy can be manufactured in a hot state, and the raw material unit can be reduced.
We were able to reduce the number of man-hours for correction and strictly adhere to product delivery times.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing a plan view of a process outline of a return finish rolling according to the present invention.

FIG. 2 is a cross-sectional view of an extra-thick H-section steel and is an explanatory view showing reference numerals of various dimensions.

FIG. 3 is a flow chart of steps when carrying out the present invention.

FIG. 4 is a graph showing changes in flange width and web height when the present invention is implemented.

FIG. 5 is an explanatory diagram of roll gap setting when the present invention is applied to flange width adjustment.

FIG. 6 is an explanatory diagram of roll gap setting when the present invention is applied to adjustment of a flange height.

FIG. 7 is an explanatory diagram of roll gap setting when the present invention is applied to adjustment of flange flatness.

FIG. 8 is a layout view of a rolling equipment row for producing an extremely thick H-section steel.

FIG. 9 is a raw material, an intermediate product, and a product cross-sectional view obtained in the rolling stage of extra-thick H-section steel.

FIG. 10 is a cross-sectional view of an H-shaped steel in which W-shaped deformation appears.

FIG. 11 is a cross-sectional view of an H-section steel in which a warp appears.

[Explanation of symbols]

1: Breakdown mill 2: Coarse universal mill 3: Finishing universal mill 4: Hot dimension meter 5: Thermometer 6: Length meter 7: Flange 8: Web

Claims (6)

[Claims] 1. A beam blank for a breakdown mill,
In manufacturing an extra thick H-section steel through a combination mill consisting of a rough universal mill and an edging mill and a finishing universal mill in this order, (1) the temperature, dimension and shape parameters of the finish rolling material rolled by the finishing universal mill are set. And (2) when the temperature of the finish rolled material is equal to or higher than the A ₁ transformation point and the dimension / shape parameters do not satisfy the specified values, the dimension / shape parameters of the finished rolled material satisfy the specified values. A method of manufacturing an extra-thick H-section steel, comprising the steps of: re-adjusting the roll gap of the finishing universal mill and performing back finishing rolling. 2. The method for producing an extremely thick H-section steel according to claim 1, wherein rolling is repeated to repeat the steps (1) and (2). 3. The extra-thickness H according to claim 1 or 2, characterized in that the temperature and dimension / shape parameters of the finish rolled material rolled by the finish universal mill are measured on the rear surface of the finish universal mill. Shaped steel manufacturing method. 4. The method according to claim 1, further comprising the step of opening the roll of the finish universal mill and feeding the finish rolled material rolled by the finish universal mill back to the front surface of the finish universal mill. The method for producing an extremely thick H-section steel according to. 5. The step of measuring the temperature and dimension / shape parameters of the finish rolled material rolled by the finish universal mill on the rear surface of the finish universal mill, and after the measurement, the finish rolled material rolled by the finish universal mill is measured. Immediately back-feeding to the front surface of the finishing universal mill, determining the necessity of re-finishing rolling based on the measured values, adjusting the roll gap of the finishing universal mill for re-finishing rolling, and The method for producing an extra-thick H-section steel according to any one of claims 1 to 4, wherein the step of subjecting the sent finish-rolled material to re-finish rolling is sequentially performed. 6. The dimension / shape parameter is any one of flange width, web thickness, web height, flange flatness, as-roll length, and web center deviation of the finish rolled material.
Alternatively, the number is 2 or more, and the method for producing an extremely thick H-section steel according to any one of claims 1 to 5.