JP3678003B2 - Rolling method of rough steel slab - Google Patents

Description

【００２１】
この表１から、１パス圧下量（２×ΔＷe ）と圧延安定性には関連があり、１パス圧下量（２×ΔＷe ）が大きい程圧延は安定することがわかった。
図２は、表１の条件４におけるフランジ増肉歪みεfw（縦軸）と圧下量（２×ΔＷe ）（横軸）との関係を示した図である。
この図２から、安定して圧延が可能な条件では、フランジ部の厚みが圧下量に比例して効率良く増大可能であることが分かった。
【００２２】
次に、１パス圧下量（２×ΔＷe ）が大きい程圧延は安定し、フランジ部の厚みが圧下量に比例して効率良く増大可能であるとして、何故にこのようになるのかを解析すると共に、１パス圧下量をいかなる値すべきかを検討した。
図３は被圧延材を高さＨs を有する孔型突起部１ｂにより割り込み拡大し、被圧延材端部４１が孔型底部に接触した状態（図３（ａ））と、それ以降さらに圧下を加えた変形状態（図３（ｂ））を示している。以下、図３に基づいて解析結果を説明する。
【００２３】
圧延前の被圧延材端部４１の垂直方向の長さは孔型突起高さと等しくＨs である。そして、１パスの圧下量が２×ΔＷe の場合、片側ΔＷe の圧延による割り込みにより新たなフランジ部４３が創出されるとともに、圧延前フランジ部とこの創出されたフランジ部には、垂直方向にΔＷe の圧下が加わる。これを歪みεfwで表すと
εfw＝ln（Ｈs ／（Ｈs ＋ΔＷe ））
である。
【００２４】
図３（ｂ）に示すように、被圧延材のフランジ部足先と孔型底部では、圧延反力Ｐ1 、Ｐ2 が作用するが、この値は垂直方向の圧下歪みεfwが発生する時の変形抵抗kfと接触面積Ｃ1 、Ｃ2 の積にほぼ比例する。
そして、変形抵抗kfと歪みとの間には一定の関係があり、図４に一例として、1200℃での0.20％Ｃ炭素鋼の圧縮試験における歪みと変形抵抗の関係を示す。この図４から分かるように、圧下歪みが0.15以下の比較的小さい領域では、歪みに対する変形抵抗の変化率が大きく、圧下歪みが約0.15以上ではその変化率が減少する。
【００２５】
つまり、圧延前の被圧延材の前パスでの割り込みにより造形されたフランジ部の長さlfが何らかの原因で左右不均一であった場合、またはロールの左右レベリングが不適正であった場合、当該パスでのフランジ部左右の圧下歪みに違いが生じるが、圧下量が比較的小さい、即ち圧下歪みの比較的小さい場合には、この歪みの差による左右フランジ部の変形抵抗の差が大きくなり、孔型底部に作用するフランジ左右の圧延反カＰ1 ，Ｐ2 に差が生じ、これに起因して圧延不安定となると考えられる。
【００２６】
さらに、左右フランジ部の圧下量が異なると接触領域面積にも差を生じ、圧延不安定をより助長することとなる。また、所望の圧下量をパス毎に小さい圧下量で圧延する場合は、パス回数が増えることにより安定性を害する外乱を受ける機会が多くなる。
【００２７】
すなわち、従来は１パス当たりの圧下量大きくすると圧延不安定になると考えられていたが実はそうではなく、１パス当たりの圧下量を小さくとっていたが故に圧延不安定となっていたのである。
【００２８】
上記要因分析から、上述したように被圧延材の端部４１が孔型底部に接した後、さらに大圧下を加えて大きな歪みを生ずるような圧延をすれば、フランジ部左右長さ不均一等に起因するフランジ部左右の圧下歪みに違いがあっても、圧延は安定することが分かった。なぜなら、圧下歪みを、図４に示すように、被圧延材の変形抵抗の歪みに対する変化率が飽和するような歪み（図４では約0.15）よりも大きくすれば、フランジ部左右の圧下歪みに多少違いがあっても、変形抵抗の差は小さく、孔型底部に作用するフランジ左右の圧延反カＰ1 ，Ｐ2 に差が生じないからである。
【００２９】
すなわち、圧延安定性を確保するためには以下に示す条件を満たすことが望ましい。
ln（（Ｈs ＋ΔＷe ）／Ｈs)≧0.15
【００３０】
また、本発明のフランジ部造形圧延では、被圧延材端部のみに加工を加えるため、圧延による延伸は５％以下と極めて少なく、フランジ部の厚みは、圧下量２×ΔＷe に対して効率良く増加し、ほぼ以下の関係にある。
ln（Ｔ2 ／ｔ2)＝α×ln((Ｈs ＋ΔＷe)／Ｈs)
α＝0.9 〜0.6
ｔ2 ；圧延前フランジ部厚み
Ｔ2 ；圧延後フランジ部厚み
Ｈs ；突起部高さ
２×ΔＷe ；１パス圧下量
【００３１】
実施の形態２．
次に、図５に示す突起部１ｂの頂角の角度２×Ａと孔型底部の角度Ｂを変更して、これら突起部１ｂの頂角の角度２×Ａと孔型底部の角度Ｂとフランジ部の肉厚増加の関係を角度Ｇ＝Ａ＋Ｂをパラメータとして調査した。
【００３２】
図６は、この調査結果を、フランジ部増肉歪みを縦軸に、角度Ｇ＝Ａ＋Ｂを横軸に取って示したものである。図６から分かるように、角度Ｇが増加するにしたがい、フランジの増肉歪みは徐々に減少し、約４５°を超えるとフランジの増肉歪みの低下は大きくなる。効率的なフランジ部の肉厚増加を実現するためには、突起部１ｂの頂角の1/2 の角度と、孔型底部の角度との和が約４５°であることが望ましいことを見いだした。
【００３３】
実施の形態３．
図７は実施の形態３の説明図であり、実施の形態１に示した側壁を有しない孔型の突起部を隣接する孔型の側壁として利用した孔型を示している。
以下、図７に基づいて、実施の形態３を説明する。
この例は、スラブ３０を素材としてＨ形鋼用粗形鋼片を造形圧延する場合に本発明を適用したものである。
【００３４】
この実施の形態３では、スラブ端面に割り込みをいれフランジ部を造形する第１段階の孔型６２と、この孔型６２で圧延された被圧延材の割り込みを拡大しフランジ部を造形しつつフランジ部の厚みを増大させる第２段階の孔型１（突起部１ｂのみで側壁を有しない実施の形態１で説明した孔型）と、この孔型１の突起部１ｂを片側の側壁としたフランジ部を押し拡げかつエッジングする第３段階の孔型６４と、主としてウェブを減厚しほぼＨ形に成形する第４段階の孔型６５を用いる。
【００３５】
具体的な圧延方法は、第１段階、第３段階、第４段階では、従来例と同様に行い、第２段階では実施の形態１と同様に行う。
【００３６】
本実施の形態では、第２段階の孔型１が側壁を有しておらず、この孔型１の突起部１ｂを第３段階の孔型６４の片側の側壁として利用しているので、孔型として使用されるロール胴長が短くなり、逆に言えば、大物サイズの粗形鋼片の造形が可能となる。
なお、図１１に示した従来法では、実施の形態３の孔型１に相当する孔型６３には側壁を必要としているため、図７に示したようなロール胴長をフルに使用する大物サイズの粗形鋼片の造形は、本発明と同じロール胴長内には孔型を入れ込めないため不可能である。
【００３７】
【実施例】
実施例１
厚み250mm 、幅1100mmの矩形スラブ３０を素材とし、図８に示す本発明の孔型１と、比較例として従来例の孔型６３（図１１参照）により造形圧延を実施した。
圧延条件は、被圧延材のフランジ端部が孔型底に接する迄は同一条件で行い、それ以降の圧下スケジュールは表２に示す条件で行った。その結果も、表２に示す。
【００３８】
【表２】

【００３９】
表２に示したように、比較例の場合には、圧延時にふらつくとともに、フランジ部４箇所の厚みの不均一性も大きかったのに対して、本発明の圧下スケジュールの圧延では、圧延が安定しており、かつフランジ部４箇所の厚みの不均一性も小さかった。
この実施例１から本発明の効果が実証された。
【００４０】
実施例２
厚み250mm 、幅1300mmのスラブを素材とし、図９に示す本発明の孔型（ａ）と本発明とは異なる孔型（ｂ）により、実施例１と同様に被圧延材のフランジ端部が孔型底に接した以降で、表３に示す圧下スケジュールにより造形圧延を実施した。その結果も、表３に示す。
【００４１】
【表３】

【００４２】
双方とも、圧延安定性は良好であったが、比較孔型の圧延では被圧延材端部の幅は増大したが、フランジ部の肉厚の増加は不十分であり、この点で本発明との違いが明確に把握できた。
すなわち、本発明では従来は困難であったスラブ厚みの1/2 以上のフランジ厚みの造形が可能となり、スラブ厚みの1/2 より約20mm厚いフランジ厚みを図９（ａ）の孔型による圧延終了時に確保できた。
以上より、実施の形態２で示した孔型の形状がスラブ厚みの増肉に効果的であることが実証された。
【００４３】
【発明の効果】
本発明は以上説明したように構成されているので、以下に示すような効果を奏する。
【００４４】
突起部を有する造形孔型を用いて被圧延材のフランジ部を割り込み圧延し、前記被圧延材の端部が前記造形孔型の孔型底部に接した後、前記被圧延材の端部両側を拘束しないで、さらに圧下を加えて圧延するようにしたので、粗圧延工程においてフランジ厚みをスラブの厚みの1/2 よりもを厚くすることができる。これによって、同一厚みのスラブから大物サイズの形鋼の製造が可能となる。
【００４５】
また、被圧延材の端部が孔型底部に接してからさらに圧下する際の１パス圧下を、被圧延材の変形抵抗の歪みに対する変化率が下記式を満足する圧下量で行うようにしたので、効率及び圧延安定性が良好になった。
ｌ n( Ｈｓ＋ΔＷｅ ) ／Ｈｓ≧ 0.15
但し、Ｈ s ；突起部高さ
２×ΔＷ e ；１パス圧下量
【００４６】
さらに、突起部の頂角の1/2 の角度と、孔型底部の角度との和が４５°以下になるようにしたので、効果的にフランジ部の肉増ができる。
【００４７】
また、造形孔型の突起部を隣接する孔型の側壁として利用するようにしたので、ロール胴長を有効に利用可能とすることにより、大物サイズの粗形鋼片の造形が可能となる。
【図面の簡単な説明】
【図１】 本発明の一実施の形態に用いる孔型の説明図である。
【図２】 表４の条件４におけるフランジ増肉歪みεfw（縦軸）と圧下量（２×ΔＷe ）（横軸）との関係を示した図である。
【図３】 本発明の実施の形態１における理論解析の説明図である。
【図４】 歪み（横軸）と変形抵抗（縦軸）との関係を示す図である。
【図５】 本発明の実施の形態２の説明図である。
【図６】 本発明の実施の形態２におけるフランジ部増肉歪みの変化の説明図である。
【図７】 本発明の実施の形態３の説明図である。
【図８】 本発明の実施例１の説明図である。
【図９】 本発明の実施例２の説明図である。
【図１０】 Ｈ形鋼等の形鋼の熱間圧延工程を摸式的に示した図である。
【図１１】 従来の圧延方法の説明図である。
【図１２】 従来の課題の説明図である。
【符号の説明】
１ 孔型
１ｂ 突起部
４０ 被圧延材
４１ 被圧延材の端部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for rolling a shaped steel slab.
[0002]
[Prior art]
FIG. 10 is a diagram schematically showing a hot rolling process of a section steel such as H-section steel. First, the outline of the hot rolling process of the shape steel will be described based on FIG. A material such as a slab, bloom, or beam blank heated to a predetermined temperature in the heating furnace 51 is rolled into a rough shaped steel slab by a shaping rolling mill 52, and thereafter universal rolling mills 53a, 53b and an edger rolling mill 54a, It is rolled to the product shape size by a rough universal rolling mill group consisting of 54b or a horizontal rolling mill group having a shape steel hole die and a finish rolling mill 55.
[0003]
In the modeling rolling mill 52, for example, when rolling a rough steel slab for H-section steel using a slab 61 as shown in FIG. 11 as a raw material, a plurality of edging rolling box holes 62, 63, 64 for forming a flange portion are used. Then, a desired rough shaped steel slab is rolled by a hole mold 65 that reduces the thickness of the web-corresponding portion and rolls it into an approximately H shape. Such a method for forming a rough steel slab is disclosed in, for example, Japanese Patent Publication No. 58-19361.
[0004]
Based on FIG. 11, the flange part shaping | molding process in a conventional method is described in detail. First, the end face of the slab is constrained by the side wall 62a of the hole mold 62 for edging rolling, the interruption is made by the protrusion 62b, and then the material to be rolled is punched by the hole mold 63 having a large hole width, protrusion height and protrusion angle. While restraining at the side of the mold, the interruption formed by the hole mold 62 is deepened by the protrusion 63b, and the interruption angle is increased to form the flange portion.
[0005]
Next, the portion where the interruption of the material to be rolled is deepened is expanded by the hole mold 64 and the edging is reduced to form the flange portion. At this time, the flange width can be increased by increasing the edging reduction amount, and the rolling stability can be ensured by constraining with the hole-shaped side wall 64a in the latter half of the edging reduction.
Finally, the thickness of the web-corresponding portion is reduced by the hole mold 65, and a desired rough shaped steel slab is rolled by rolling into a substantially H shape.
[0006]
[Problems to be solved by the invention]
If it is possible to form a rough shaped steel slab with a thick flange from a slab of the same thickness, not only will it be possible to produce large-sized steel, but it will also be necessary to increase the thickness reduction of the fragile part in the subsequent process. Therefore, there is a great merit that a wrinkle-free product can be made by increasing the amount of reduction in the subsequent process.
However, in the conventional method for rolling a rough steel slab as described above, it has been extremely difficult to form a rough steel slab having a thick flange portion from a slab having the same thickness. The reason will be described below.
[0007]
First, in the step of the hole mold 62, the slab 61 is interrupted and slit, so that the thickness of the flange portion is ½ of the slab thickness.
Further, in the step of the hole mold 63, the material to be rolled is restrained by the hole side surface 63a, so it is difficult to increase the thickness of the flange portion. Here, the reason why the hole side surface 63a is restrained is that this restraint is considered to be indispensable in order to stably perform the interruption enlargement.
[0008]
Further, when the width reduction amount due to edging is increased in the hole mold 64 process, as shown in FIG. 12, only the flange foot portion in contact with the hole mold side wall 64a is increased in thickness, and the lapping process in the post-rolling process is increased. It is not possible to increase the thickness of the flange portion effectively by causing a harmful effect such as occurrence.
Furthermore, in the step of the hole mold 65, it is well known that a so-called flange shrinkage occurs in which the thickness of the flange portion is reduced because the web is mainly squeezed and the flange portion is stretched by stretching the web. Therefore, it is difficult to increase the thickness of the flange portion.
[0009]
As described above, in the conventional method for rolling a rough steel slab, it has been extremely difficult to form a rough steel slab having a thick flange portion from a slab having the same thickness.
[0010]
As another problem, in the conventional rolling method of rough shaped steel slabs, since all the hole molds require the side walls, a limited roll cylinder is required particularly when modeling large-sized rough shaped steel slabs. It became difficult to arrange all these hole types in the length, and this was a limitation of the modeling size.
[0011]
This invention is made | formed in order to solve this subject, and it aims at providing the rolling method of the rough shaped steel piece which can change flange thickness.
Moreover, it aims at providing the rolling method of a rough shaped steel slab with favorable efficiency and rolling stability.
Furthermore, it aims at providing the rolling method of the rough shaped steel piece which enables the flange part thickness increase effectively.
It is another object of the present invention to provide a method for rolling a rough steel slab that makes it possible to form a large steel slab by making the roll barrel length available effectively.
[0012]
[Means for Solving the Problems]
In the method of rolling the rough shaped steel slab according to the present invention, in the step of forming the flange portion of the material to be rolled in the hot rolling rough rolling,
The flange part of the material to be rolled is interrupted and rolled using a modeling hole mold having a protrusion having a sum of a half angle of the apex angle and the angle of the bottom of the hole mold of 45 ° or less . After the end portion is in contact with the bottom of the shaping hole mold hole, without rolling both ends of the rolled material, further rolling and rolling, the thickness of the flange portion of the rolled material can be increased. It is characterized by doing.
[0013]
Further, the one-pass reduction when the end portion of the material to be rolled comes into contact with the bottom of the hole mold is further reduced by a reduction amount satisfying the following formula .
l n (Hs + ΔWe) / Hs ≧ 0.15
However, H s ; Projection height
2 × ΔW e ; 1-pass reduction amount
Furthermore, the modeling hole mold is characterized in that a sum of an angle of 1/2 of the apex angle of the protrusion and an angle of the hole mold bottom is 45 ° or less.
[0015]
In addition, the shaping hole mold having the protrusions expands the interruption of the first stage hole mold for shaping the flange part by interrupting the end face of the slab and the material to be rolled rolled by the first stage hole mold. A second stage hole mold for increasing the thickness of the flange part while shaping the flange part, and a third stage hole mold for expanding and edging the flange part of the material to be rolled that has been rolled in the second stage hole mold A second stage hole mold of the roll comprising: a fourth stage hole mold for mainly reducing the thickness of the rolled material rolled in the third stage hole mold and forming a substantially H shape. And
The inclined surface connected to the second-stage hole-shaped protrusion is used as a side wall in the third-stage hole mold .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is an explanatory view of a hole mold used in an embodiment of the present invention. The hole mold 1 shown in FIG. 1 is used in the rolling process by the hole mold 63 shown in FIG. 11 showing a conventional example. As shown in FIG. 1, the hole mold 1 has only protrusions 1b and does not have side walls.
[0017]
Hereinafter, the rolling method of the present invention using the hole mold 1 will be described while describing the process leading to the completion thereof. While the slab end face is restrained by the side wall 62a of the hole mold 62 shown in the conventional example, an interruption is made by the protrusion 62b. And the to-be-rolled material 40 which interrupted is rolled with the hole mold 1 until the edge part 41 contacts a hole bottom as shown in FIG.1 (b). Up to this point, it is the same as the conventional method.
[0018]
In the conventional example, it is considered indispensable to constrain both sides of the end of the material to be rolled in order to perform the subsequent reduction stably, and in fact, the side wall 63a like the hole mold 63 shown in the conventional example. The material to be rolled was restrained and rolled.
However, if the both sides of the end of the material to be rolled are constrained by the perforated side walls in this step, the thickness of the flange cannot be increased.
Therefore, the present inventors have conducted intensive studies to enable stable rolling without restriction by the hole-shaped side wall and to increase the thickness of the flange in this step. As a result, the following new findings have been found.
[0019]
That is, after the end portion 41 of the material to be rolled comes into contact with the bottom of the hole mold, the both sides of the end portion of the material to be rolled are not restrained, and further rolling is performed by applying a large reduction, and the flange portion can be stably rolled. It can effectively increase the thickness. Hereinafter, the background to this finding will be described.
The inventors interrupted and expanded the material to be rolled by the hole-shaped protrusion 1b having the height Hs, and made the same total reduction amount after the end 41 of the material to be rolled contacted the bottom of the hole mold, thereby reducing one pass. The amount (2 × ΔWe) was variously changed, and changes in rolling stability and flange thickness were investigated. The results are shown in Table 1.
[0020]
[Table 1]

[0021]
From Table 1, it was found that the one-pass reduction amount (2 × ΔWe) is related to the rolling stability, and that the larger the one-pass reduction amount (2 × ΔWe), the more stable the rolling.
FIG. 2 is a diagram showing the relationship between the flange thickening distortion εfw (vertical axis) and the reduction amount (2 × ΔWe) (horizontal axis) under Condition 4 in Table 1.
From FIG. 2, it was found that the thickness of the flange portion can be increased efficiently in proportion to the amount of reduction under conditions where rolling can be performed stably.
[0022]
Next, as the one-pass reduction amount (2 × ΔWe) is larger, the rolling is more stable, and the thickness of the flange portion can be increased efficiently in proportion to the reduction amount. The value of the one-pass reduction amount was examined.
FIG. 3 shows a state in which the material to be rolled is interrupted and enlarged by the hole-shaped protrusion 1b having a height Hs, and the state in which the material 41 is in contact with the hole bottom (FIG. 3 (a)), and further reduction thereafter. The added deformation | transformation state (FIG.3 (b)) is shown. Hereinafter, the analysis results will be described with reference to FIG.
[0023]
The length in the vertical direction of the rolled material end 41 before rolling is equal to the hole-shaped projection height and is Hs. When the reduction amount of one pass is 2 × ΔWe, a new flange portion 43 is created by interruption due to rolling on one side ΔWe, and the pre-rolling flange portion and the created flange portion have ΔWe in the vertical direction. The reduction of is added. When this is expressed by the strain εfw, εfw = ln (Hs / (Hs + ΔWe))
It is.
[0024]
As shown in FIG. 3 (b), the rolling reaction forces P1 and P2 act on the flange foot and the bottom of the hole mold of the material to be rolled. This value is the deformation when the vertical reduction strain εfw occurs. It is almost proportional to the product of the resistance kf and the contact areas C1 and C2.
There is a certain relationship between the deformation resistance kf and the strain. FIG. 4 shows the relationship between the strain and the deformation resistance in a compression test of 0.20% C carbon steel at 1200 ° C. as an example. As can be seen from FIG. 4, the rate of change of deformation resistance with respect to strain is large in a relatively small region where the rolling strain is 0.15 or less, and the rate of change decreases when the rolling strain is about 0.15 or more.
[0025]
In other words, if the length lf of the flange part formed by interruption in the previous pass of the material to be rolled before rolling is uneven for some reason, or if the left and right leveling of the roll is inappropriate, There is a difference in the rolling distortion on the left and right sides of the flange part in the pass, but when the amount of rolling is relatively small, that is, when the rolling distortion is relatively small, the difference in deformation resistance of the left and right flange parts due to the difference in distortion increases. It is considered that there is a difference between the rolling reaction forces P1 and P2 on the left and right sides of the flange that act on the bottom of the hole mold, resulting in unstable rolling.
[0026]
Furthermore, if the amount of rolling of the left and right flange portions is different, a difference is caused in the contact area, which further promotes rolling instability. Moreover, when rolling a desired amount of reduction with a small amount of reduction for each pass, the chances of receiving disturbances that impair stability increase as the number of passes increases.
[0027]
That is, in the past, it was thought that if the rolling reduction per pass was increased, the rolling became unstable, but in fact, this was not the case, and the rolling reduction became unstable because the rolling reduction per pass was made small.
[0028]
From the above factor analysis, after rolling the end 41 of the material to be rolled to the bottom of the hole mold as described above, if rolling is performed such that a large strain is applied to cause a large distortion, the left and right lengths of the flange portion are uneven. It was found that rolling was stable even when there was a difference in the rolling distortion between the left and right flanges due to the above. This is because, as shown in FIG. 4, if the rolling strain is made larger than the strain that saturates the rate of change of the deformation resistance of the material to be rolled (approximately 0.15 in FIG. 4), the rolling strain on the left and right sides of the flange portion is reduced. This is because even if there is a slight difference, the difference in deformation resistance is small, and there is no difference between the rolling reaction forces P1 and P2 on the left and right flanges acting on the bottom of the hole mold.
[0029]
That is, it is desirable to satisfy the following conditions in order to ensure rolling stability.
ln ((Hs + ΔWe) / Hs) ≧ 0.15
[0030]
Further, in the flange part shaping rolling of the present invention, since processing is applied only to the end part of the material to be rolled, the elongation due to rolling is extremely small at 5% or less, and the thickness of the flange part is efficient with respect to the reduction amount 2 × ΔWe. Increased and has the following relationship.
ln (T2 / t2) = α × ln ((Hs + ΔWe) / Hs)
α = 0.9 to 0.6
t2; Flange thickness before rolling T2; Flange thickness after rolling Hs; Projection height 2 × ΔWe; 1-pass reduction amount
Embodiment 2. FIG.
Next, the apex angle 2 × A of the projection 1b shown in FIG. 5 and the angle B of the hole bottom are changed, and the apex angle 2 × A of the protrusion 1b and the angle B of the hole bottom are changed. The relationship of the increase in the thickness of the flange portion was investigated using the angle G = A + B as a parameter.
[0032]
FIG. 6 shows the results of this investigation with the flange thickness increase distortion on the vertical axis and the angle G = A + B on the horizontal axis. As can be seen from FIG. 6, as the angle G increases, the flange thickness increase distortion gradually decreases, and when the angle exceeds about 45 °, the flange thickness increase distortion decreases. In order to realize an efficient increase in the thickness of the flange portion, it has been found that the sum of the angle of the half of the apex angle of the protrusion 1b and the angle of the bottom of the hole mold is preferably about 45 °. It was.
[0033]
Embodiment 3 FIG.
FIG. 7 is an explanatory diagram of the third embodiment, and shows a hole mold that uses the hole-shaped protrusions having no side wall shown in the first embodiment as adjacent hole mold side walls.
The third embodiment will be described below based on FIG.
In this example, the present invention is applied to a case where a slab 30 is used as a raw material to form and roll a rough steel slab for H-section steel.
[0034]
In the third embodiment, the first stage hole mold 62 for forming the flange portion by interrupting the slab end face, and the flange while forming the flange portion by expanding the interruption of the material to be rolled rolled by the hole mold 62. A second stage hole mold 1 for increasing the thickness of the hole (the hole mold described in the first embodiment having only the protrusion 1b and no side wall), and a flange having the protrusion 1b of the hole mold 1 as one side wall A third stage hole mold 64 for expanding and edging the part and a fourth stage hole mold 65 for mainly reducing the thickness of the web and forming it into an approximately H shape are used.
[0035]
A specific rolling method is performed in the first stage, the third stage, and the fourth stage in the same manner as the conventional example, and in the second stage in the same manner as in the first embodiment.
[0036]
In the present embodiment, the second stage hole mold 1 does not have a side wall, and the projection 1b of the hole mold 1 is used as one side wall of the third stage hole mold 64. The length of the roll body used as a mold is shortened. In other words, a large steel slab can be formed.
In the conventional method shown in FIG. 11, since the hole mold 63 corresponding to the hole mold 1 of the third embodiment requires a side wall, the roll cylinder length as shown in FIG. 7 is fully used. It is impossible to form a rough shaped steel slab because a hole mold cannot be inserted in the same roll body length as in the present invention.
[0037]
【Example】
Example 1
Using a rectangular slab 30 having a thickness of 250 mm and a width of 1100 mm as a raw material, shaping rolling was performed using the hole mold 1 of the present invention shown in FIG. 8 and a conventional hole mold 63 (see FIG. 11) as a comparative example.
The rolling conditions were the same until the flange end of the material to be rolled was in contact with the bottom of the hole mold, and the subsequent rolling schedule was performed under the conditions shown in Table 2. The results are also shown in Table 2.
[0038]
[Table 2]

[0039]
As shown in Table 2, in the case of the comparative example, the rolling was stable during rolling and the thickness unevenness of the four flange portions was large, whereas the rolling of the rolling schedule according to the present invention was stable. In addition, the nonuniformity of the thickness of the four flange portions was small.
From Example 1, the effect of the present invention was demonstrated.
[0040]
Example 2
A slab having a thickness of 250 mm and a width of 1300 mm is used as a raw material, and the flange end of the material to be rolled is formed in the same manner as in Example 1 by the hole mold (a) of the present invention shown in FIG. 9 and the hole mold (b) different from the present invention. After coming into contact with the bottom of the hole mold, shaping rolling was performed according to the rolling schedule shown in Table 3. The results are also shown in Table 3.
[0041]
[Table 3]

[0042]
In both cases, the rolling stability was good, but in the comparative hole type rolling, the width of the end of the material to be rolled increased, but the increase in the thickness of the flange portion was insufficient. The difference was clearly understood.
That is, it becomes possible to form a flange having a thickness of 1/2 or more of the slab thickness, which has been difficult in the present invention, and a flange thickness of about 20 mm thicker than 1/2 of the slab thickness is rolled by the hole mold shown in FIG. It was secured at the end.
From the above, it was demonstrated that the hole shape shown in the second embodiment is effective for increasing the thickness of the slab.
[0043]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0044]
After interrupting and rolling the flange portion of the material to be rolled using the shaping hole mold having the protrusion, and the end of the material to be rolled is in contact with the bottom of the hole shape of the shaping hole mold, both sides of the edge of the material to be rolled Since the rolling is further performed without restraining, the flange thickness can be made thicker than 1/2 the slab thickness in the rough rolling process. As a result, it is possible to manufacture a large-sized section steel from a slab having the same thickness.
[0045]
In addition, the one-pass reduction when the end of the material to be rolled comes into contact with the bottom of the hole mold is performed at a reduction amount in which the rate of change with respect to the strain of the deformation resistance of the material to be rolled satisfies the following formula . Therefore, efficiency and rolling stability were improved.
l n (Hs + ΔWe) / Hs ≧ 0.15
However, H s ; Projection height
2 × ΔW e ; 1-pass reduction amount
Furthermore, since the sum of the half angle of the apex angle of the protrusion and the angle of the hole bottom is 45 ° or less, the thickness of the flange can be effectively increased.
[0047]
Further, since the modeling hole mold protrusion is used as the side wall of the adjacent hole mold, it is possible to model a large steel slab by making the roll cylinder length available effectively.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a hole mold used in an embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between flange thickening strain εfw (vertical axis) and reduction amount (2 × ΔWe) (horizontal axis) under condition 4 in Table 4.
FIG. 3 is an explanatory diagram of theoretical analysis according to Embodiment 1 of the present invention.
FIG. 4 is a diagram showing the relationship between strain (horizontal axis) and deformation resistance (vertical axis).
FIG. 5 is an explanatory diagram of Embodiment 2 of the present invention.
FIG. 6 is an explanatory diagram of a change in flange thickness increase distortion in the second embodiment of the present invention.
FIG. 7 is an explanatory diagram of Embodiment 3 of the present invention.
FIG. 8 is an explanatory diagram of Example 1 of the present invention.
FIG. 9 is an explanatory diagram of Embodiment 2 of the present invention.
FIG. 10 is a diagram schematically showing a hot rolling process of a shape steel such as an H-section steel.
FIG. 11 is an explanatory diagram of a conventional rolling method.
FIG. 12 is an explanatory diagram of a conventional problem.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hole type | mold 1b Protrusion part 40 Rolled material 41 End part of a rolled material

Claims (3)

In the process of shaping the flange portion of the material to be rolled in the hot rolling rough rolling,
The flange portion of the material to be rolled is interrupted and rolled using a modeling die having a protrusion whose sum of a half angle of the apex angle and the angle of the bottom of the die is 45 ° or less . After the end is in contact with the hole bottom of the modeling hole mold, rolling is performed with further reduction without restraining both sides of the end of the rolled material, and the flange portion of the rolled material can be increased in thickness. A method of rolling a rough shaped steel slab characterized by comprising: The rough shaped steel according to claim 1, wherein the one-pass reduction when further rolling is performed after the end portion of the material to be rolled comes into contact with the bottom of the hole mold is performed with a reduction amount satisfying the following formula. How to roll a piece.
ln (Hs + ΔWe) /Hs≧0.15
However, Hs: Projection height
2 × ΔWe; 1 pass reduction The shaping hole mold having the protrusions is a flange part that expands the interruption of the first stage hole mold that forms the flange part by interrupting the end face of the slab, and the material to be rolled that is rolled in the first stage hole mold. A second stage hole mold that increases the thickness of the flange part while shaping the mold, and a third stage hole mold that expands and edges the flange part of the material rolled by the second stage hole mold, and The second stage hole mold of the roll comprising the fourth stage hole mold for reducing the thickness of the web mainly rolled by the third stage hole mold and forming it into a substantially H shape,
The method of rolling a rough steel slab according to claim 1 or 2, wherein an inclined surface connected to the second stage hole mold protrusion is used as a side wall in the third stage hole mold.

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