JPH08229601A - Method for producing rough billet for H-section steel - Google Patents

Abstract

PURPOSE: To manufacture a rough shaped slab for wide flange shapes having plural cross-sectional dimensions without changing rolls by using the shape of the middle bulged part of a 2nd grooved roll in a 1st stage, amount of edging at a 1st pass, amounts of edging on and after the 2nd pass and shape of the finish forming grooved roll in the 2nd stage expressed by specified inequalities. CONSTITUTION: The shape of the middle bulged part of the 2nd grooved roll in the 1st stage is expressed by the inequality I, the amount of edging at the 1st pass in the 2nd grooved roll is taken as a numerical value of r1 which satisfies the inequality II and the amounts of edging on and after the 2nd pass are taken as the numerical value of r2 which satisfies the inequality III. Further, the shape of finish forming grooved roll in the 2nd stage following this is taken as the inequality IV and the intermediate slab formed with the 2nd grooved roll in the 1st stage is finished and formed into the rough shaped slab with the finish forming grooved roll in the 2nd stage. Where, the unit of the coefficients 1. 2 is degree/mm, θ1 is the apex angle of the middle bulged part of the 1st grooved roll in the 1st stage and its unit is degree, h1 is the approximated height (mm) of the middle bulged part of the 1st grooved roll in the 1st stage, Q2 is the apex angle of the middle bulged part of the 2nd grooved roll in the 1st stage and its unit is degree, h2 is the approximated height (mm) of the middle bulged part of the 2nd grooved roll in the 1st stage, h2 ' is the actual height (mm) of the middle bulged part of the 2nd grooved roll in the 1st stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a rectangular cross-section steel slab as a raw material, and an intermediate steel slab having a dogbone type cross-sectional shape (hereinafter referred to as "intermediate steel slab") produced by width reduction
The present invention relates to a method for efficiently manufacturing a rough-shaped steel slab having a plurality of cross-sectional shapes when a rough-shaped steel slab having an H-shaped cross-sectional shape (hereinafter referred to as "coarse-shaped steel slab") is manufactured by a finish forming die via .

[0002]

2. Description of the Related Art Conventionally, for example, in a rolling process for producing an H-shaped steel 55 shown in FIG. 2, a rough double-hole rolling mill 1 for roughly shaping a rough shaped steel piece 54, and further the rough shaped steel piece 54. To H-section steel 5
The first intermediate rough universal rolling mill 2a, which is in charge of rolling up to 5, the edging rolling mill 2b provided in the vicinity of the first intermediate rough universal rolling mill 2a, the second intermediate rough universal rolling mill 3a, and the second intermediate rolling mill An edging rolling mill 3b provided close to the rough universal rolling mill 3a,
And a finishing universal rolling machine 4.
As a rolling material for H-section steel, a rectangular-section steel piece by continuous casting or a H-section rough-section steel piece by continuous casting is mainly used.

A technique for producing a rough-shaped billet made of a rectangular cross-section billet is disclosed in Japanese Patent Publication No. 58-19361 and Japanese Patent Publication No. 58-.
It is disclosed in Japanese Laid-Open Patent Publication No. 37042 or Japanese Patent Laid-Open No. 2-169103. FIG. 3 is an example of a roll-hole type arrangement of the rough double-hole type rolling mill 1 based on the above-mentioned disclosed technology, and the upper and lower roll pairs 11, 12 are usually guided groove type G
₁ (hereinafter referred to as "G ₁ hole type"), flange generation hole type G
₂ (hereinafter referred to as "G ₂ hole type"), groove elimination hole type G ₃ (hereinafter referred to as "G ₃ hole type"), _three hole types for width-reducing rectangular cross-section steel slab, and finish forming hole Type G ₄ (hereinafter "G
There is a single _4- hole type), and a total of 4-hole type is engraved. The hole bottom widths of G ₁ , G ₂ and G ₃ are s ₁ , s ₂ and s ₃ , respectively, and the approximate heights of the central bulges (hereinafter referred to as “wedges”) of the holes (hereinafter simply “ "Height") is defined as h ₁ , h ₂ and h ₃ , and the apex angles are defined as θ ₁ , θ ₂ and θ ₃ . Generally, each of the G ₁ , G ₂ and G ₃ hole type wedges has a rounded tip for preventing flaws. For example, for the G ₂ hole type h ₂ ′ shown in FIG.
Is the actual height (hereinafter referred to as “actual height”). On the other hand, the above-mentioned approximate height refers to the height of h ₂ , which extends both side surfaces of the wedge, and the intersection O of the both sides and the groove 2 of the hole type.
It is the vertical distance from 2b.

FIG. 4 shows such a pair of upper and lower rolls 11, 12.
Thus, a rectangular cross-section steel piece 5 having a cross-sectional dimension of width a ₀ and thickness b ₀
A process of forming the rough-shaped steel slab 54 using 0 as a raw material is shown. In the figure, the rolled materials 51, 52, 53, 54 show the state in the final pass in each hole type. First, FIG.
The G ₁ hole type is a hole type having a function of forming a V-shaped groove (hereinafter referred to as “induction groove”) 51a in the short side portion of a rectangular cross-section steel slab, and is apex at the center of the hole bottom width. A wedge 21a having an angle θ ₁ and groove portions 21b are formed on both sides of the wedge 21a. The hole bottom width s ₁ of the G ₁ hole type is a rectangular cross-section steel piece 50.
Is designed to be approximately equal to the thickness b ₀ of the. That is, by guiding the rectangular cross-section steel piece 50 by the side wall 31, the guiding groove 51a is accurately formed in the central portion of the short side portion,
If s ₁ is larger than b ₀ , the material will shift to the left or right in the G ₁ hole mold, and will tilt or twist, so s ₁ is approximately equal to b ₀ or prevents scratches due to contact friction with the side wall 31. Therefore, it should be slightly increased. In the G ₁ hole type, the purpose is only to accurately form the guide groove 51a in the central portion of the short side of the rectangular cross section steel piece 50, and the width of the final finished material of the G ₁ hole type (hereinafter referred to as “web height”). ) A ₁ is approximately equal to the width a ₀ of the rectangular cross section billet.

Subsequently, in the G ₂ hole type, when width reduction rolling (hereinafter referred to as "edging rolling") is performed in the height direction of the material to be rolled, the material to be rolled is guided by the wedge 22a along the guide groove 51a. Is accurately guided to the central portion of the G ₂ hole die, and swinging of the rolled material is prevented. Hole bottom width s ₂
And the apex angle θ ₂ of the wedge 22a is set to be larger than s ₁ and the apex angle θ ₁ of the G ₁ hole type, and by the edging rolling until the web height becomes a ₂ , the H-shaped steel flange corresponding portion. (hereinafter referred to as "flange") 42 spread divided by the wedge 22a, expanding its width and thickness, of approximately equal or near the flange width hole bottom width s ₂ value B
Finish to ₂ .

Next, in the edging rolling of the G ₃ hole type, the hole bottom width s ₃ is set to be slightly larger than the hole bottom width s ₂ of the G ₂ hole type, that is, B ₂ ≉s ₃ , so that The rolled material is guided by the side wall 33 to set the web height to a _3, and G ₂
An intermediate steel piece 5 of B ₃ having a flange width of the rolled material formed by the hole die is slightly enlarged to make the flange width substantially equal to the hole bottom width s _3.
Finish to 3. At the same time, the wedge 23 having an apex angle θ ₃ formed larger than the apex angle θ _{2 of} the G ₂ hole type wedge 22a.
By a, the guide groove 52a formed in the G ₂ hole shape is gently inclined to 53a, thereby preventing the occurrence of the folding flaw 54a as shown in FIG. 5 on the outer side of the flange in the subsequent steps. . In the above edging rolling from the G ₁ hole type to the G ₃ hole type, the effect of the width reduction does not extend to the central portion in the width direction of the rolled material as shown in FIG. The thickness of the width center part in the G ₁ hole type (hereinafter referred to as “web thickness”) b ₁ , the web thickness b ₂ in the G ₂ hole type,
The web thickness b ₃ in the G ₃ hole type hardly changes and is almost equal to the thickness b ₀ of the original billet having a rectangular cross section. Then the lead to intermediate steel pieces were turn 90 degrees to G ₄ grooved, web height a ₄ by molding finishing this flange width B _4, to obtain a crude shaped steel strip 54 of the web thickness b _4.

[0007] In the rolling process, the induction of the material to be rolled by G ₂ (to the flange portion of the rolled material is in contact with the side wall 32 of G ₂ grooved) grooved initial path in G ₂ grooved sidewall 32 of Since it is impossible, it is very important to guide the rolled material by the wedge 22a. That is, with respect to the G ₂ hole type wedge 22a, it is important that its shape is such that the rolling material can be prevented from swinging and a flange can be formed. The mechanism for preventing the rolled material from swinging will be described in detail with reference to FIG.

FIG. 6 shows a cross-sectional view of a G ₂ hole type roll shaft at a right angle. Apex angle theta in the previous pass, the rolled material formed a guide groove depth h is conveyed to the left, the roll apex angle theta ₂ which rotates clockwise around the O _R in the relevant path , High h ₂
It shows a situation in which the width of the material to be rolled is reduced by r and a flange portion is generated in a G ₂ hole type having a wedge of.

First, since the material to be rolled guided to the left in the figure has the guide groove, the first contact between the roll and the material to be rolled is made at the point P on the G ₂ hole type wedge 22a. . After that, the material to be rolled is guided by the G ₂ hole type wedge 22a through the guiding groove and centered.
Immediately after that, at the point Q shown in the figure, the outside of the flange portion of the rolled material is pressed down by the G ₂ hole type groove portion 22b, and the roll outlet surface O _R N
It will be finished with the target width and go out. The most important thing in this width reduction process is that the material to be rolled is centered by the G ₂ hole type wedge without swinging. Whether or not the rolled material can be centered depends on the force relationship from the wedge 22a at the point P to the rolled material guiding groove. In order to explain this situation, the straight line O _R P is extended in the roll radial direction and the half line O _R M is taken as shown in FIG. Cut surface of the roll and the material to be rolled by a surface perpendicular to the paper surface including O _R M (hereinafter referred to as “O _R M surface”)
Is projected on the O _R N plane in the projection view of FIG. Point P
Let P ′ be the projection point of. The apex angle of the G ₂ hole type wedge is θ
Is _2, for O _R N and O _R M angle (hereinafter referred to as "bite angle") of the alpha, the projection plane has a theta ₂ is greater than theta ₂ '.

Further, an enlarged view of this portion is shown in FIG. A rolling force F is applied from the wedge to the material to be rolled in the normal direction at the point P ′ of the projected wedge shape, and a frictional force μF is applied in the tangential direction of the wedge. The material to be rolled is displaced from the center of the wedge by s to the left, and s → 0 with respect to the material to be rolled.
If a force acts in the direction of (centering), it is possible to prevent swinging. That is, the lateral force component Fco of the rolling force F
s (θ ₂ '/ ₂₎ and the transverse component force μFsin frictional force μF (θ _2'
If the magnitude relationship of / 2) is Fcos (θ ₂ ′ / 2) ≧ μF sin (θ ₂ ′ / 2) (5), then μ ≦ 1 / tan (θ ₂ ′ / 2) = cot (θ _{If 2} '/ 2) (6), it is possible to prevent swinging. Therefore, as θ ₂ ′ is smaller, that is, as θ ₂ is smaller, rocking can be prevented and the stability of edging rolling is increased.

Therefore, in the conventional rough molding method, the apex angle θ ₂ of the wedge 22a of the G ₂ hole type is made small from the viewpoints of preventing the swing and improving the efficiency of flange generation. In this case, when the finish material of G ₂ hole type is directly guided to G ₄ hole type without erasing the guide groove with G ₃ hole type and finish forming rolling is performed, the guide groove generated by G ₂ hole type as shown in FIG. However, it is an essential condition to eliminate or reduce the guide groove by the G ₃ hole type in order to prevent it from becoming a broken flaw 54a.

Regarding the problem that occurs in this case, the product flange width is nominally 300 mm series (H300 × 300-
H900 × 300) will be described as an example showing the arrangement of each hole type. The actual roll cylinder length L ₀ of the rough double-hole rolling mill shown in FIG. 3 is for senior H-section steel and is usually 2500 to 3000 mm. Within this range, G ₁ , G ₂ , G ₃ , and G ₄ hole cavities are engraved, and each hole die width s ₁ , s ₂ , s ₃ , s ₄ and the side wall of each hole die are formed. Collar thickness 5t (normal t = 10
0 mm) total value L = s ₁ + s ₂ + s ₃ + s ₄ + 5t is the “required roll cylinder length”, and the difference ΔL between this and the actual roll cylinder length L ₀
= L ₀ −L is defined as “roll cylinder length excess / deficiency” (+ is a margin, −
Is insufficient).

Therefore, the web height a ₄ of the rough shaped steel slab finish-formed in the G ₄ hole type is taken as the horizontal axis and the required roll cylinder length L is taken as the left vertical axis (also t = 100 mm), and H300 × Three
FIG. 8 shows a plot of the relationship between the H-shaped steel series of 00 to H900 × 300. Abscissa 59
Point A of 3 mm corresponds to H300 x 300, and the horizontal mark 1167
Point B of mm corresponds to H900 × 300, and each point between both corresponds to an intermediate series between both series. Actual roll length L
_In this example, ₀ is 3000 mm, and the right vertical axis indicates the roll cylinder length excess or deficiency. In this case, the required roll cylinder length is included in the actual roll cylinder length for all series, and each series is engraved with G ₁ , G ₂ , G ₃ , and G ₄ hole dies. 1 for the corresponding rough billet
It is possible to roll with a book roll.

However, in this case, since the roll cylinder length has a margin in the series having a small web height (for example, a margin of about 800 mm in the minimum series H300 × 300), the G for other series is as much as possible in this margin area. ₄ '(referred to as "hole-type or less G _4") hole type' add another engraved, by producing crude form of 2 series on the same roll, reducing the need roll set number, roll changing work It is important to reduce the production cost and improve the rolling efficiency. in this case,
One series is rolled in the order of G ₁ → G ₂ → G ₃ → G ₄ to produce a rough-shaped steel slab, and the other series is manufactured with the same G ₁ ,
G ₂ and G ₃ can be used and rolled in the order of G ₁ → G ₂ → G ₃ → G ₄ ′ to produce a rough steel slab having another cross-sectional dimension.

However, it can be seen that the margin area is not long enough for engraving the G ₄ 'hole mold. That, G ₄ adds the 'hole-type grooved width s _4' and, requires roll body length L is _{L = s 1 + s 2 +} s 3 + s 4 + s 4 '
It is + 6t, and this is plotted on the left vertical axis, and the roll cylinder length excess / deficiency evaluated on the right vertical axis is shown in FIG. Here, the curve (a) is a G ₄ ′ hole type, assuming that a rough billet for the same web height and different flange width series (for example, H300 × 300 and H300 × 200) is manufactured on the same roll. If the hole width s ₄ ′ is equal to that of the G ₄ hole s ₄ (hereinafter referred to as “method I”), the curve (b) shows a series with different web heights (in this case, G ₄ is the maximum series). H900 x
Min Series H300 × 30 the G ₄ 'with respect to a 300
For 0, if G ₄ is assumed to production of the same roll of the G ₄ 'such as for H400 × 300 second smallest) crude shaped steel pieces for relative for H800 × 300 the second largest ( Hereinafter referred to as "method II"). As is apparent from FIG. 9, the hole type can be engraved in the combination of the minimum web height series of Method I (H300 × 300 and H300 ×).
No. 200), and it has been difficult to fully adopt such a method in the past because of the short roll body length.

On the other hand, if the wedge shape of the G ₂ hole type is made proper to prevent the folding flaw 54a and the G ₃ hole type can be omitted, the above-mentioned insufficient roll cylinder length is alleviated.
Therefore, the case where can be omitted G ₃ caliber, the _{G 1, G 2, G 4} , G 4 relationship must roll body length and the actual roll barrel length in the case of engraved each hole type 'in the same roll As shown in FIG. In this case, for method I, the height of the rough billet web can be about 900 mm or less, and in method II, 8 series of rough billet can be manufactured by 4 pairs of double-hole rolling rolls. Becomes

Concerning the manufacturing technology of the rough billet for H-section steel using the rectangular cross-section billet as a raw material, the technique for finishing forming the G ₂ pore type finish material with the G ₄ pore type while omitting the G ₃ pore type. about,
It is disclosed in JP-A-57-124503. The points of the disclosed technology can be summarized into the following five points. (However, the symbols are represented by those shown in FIGS. 3 and 4, and the terms are replaced by those defined in this description). The actual height h ₁ ′ of the G ₁ hole type wedge is set to the material billet thickness b _0.
0.1 to 0.28 times, that is, h ₁ ′ / b ₀ = 0.1
.About.0.28, and the actual height h ₂ ′ of the G ₂ hole type wedge is that of the G ₁ hole type h
'Substantially the same, i.e. h ₂ and' a ≒ h ₁ ', part of the G ₂ grooved wedge surrounding lines, over G ₁ grooved wedge surrounding line length 0.15 times the length of, G ₁ hole ₁ It has the same shape and size as the mold wedge, and the angle formed by the tangent to the surrounding line of the same shape and the groove is 35.
˜55 degrees (vertical angle is 70 to 110 degrees), and further, in the first pass of the G ₂ hole type wedge starting point is the G ₄ hole type, included in the line surrounding the G ₄ hole type. As configured.

Although the disclosed technique is effective in preventing the rolled material from swinging in the G ₂ hole type and preventing the crease 54a, it is caused by the fact that the hole shape is optimized. The feature is that there are many restrictions between hole types. As a result, for example, from the conditions and the conditions, the shape of the G ₂ hole type has to be made almost the same as the shape of the G ₁ hole type (that is, the wedge height and the wedge apex angle are almost the same), and the G ₁ hole type and the G ₁ hole type are the same.
It was difficult to engrave appropriate wedge shapes according to each function of the _two- hole type independently of each other. further,
As can be seen from the conditions, the wedge shape of G ₂ hole type is G
_Since the shape of the _4- hole type is also affected, the wedge shape of the G ₂ -hole type must be fixed.

[0019]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to improve the rolling shaping efficiency by omitting the width reduction pass for erasing the guide groove by the G ₃ hole type and to improve the G ₃ hole type. It is possible to increase the roll cylinder length margin by omitting the mold, and to engrave another finish forming hole mold in the extra cylinder length space, making it possible to form rough shaped steel slabs of different shapes from the same roll. Is to

[0020]

A feature of the present invention is that a wedge shape of a G ₂ hole type and a width reduction amount per pass for preventing the generation of the folding flaw 54a caused by the guide groove and the prevention of the swinging. It is possible to omit the G ₃ hole type by optimizing the shape and the shape of the G ₄ hole type. As a result, unlike the prior art, G ₁ hole type and G ₂
Even if the shape of the grooved rather similar it is possible to swing prevention in G ₂ grooved and yet it is possible to prevent the occurrence of Orekomi flaw 54a in rolling G ₄ caliber later.

That is, according to the present invention, when a rough steel slab for H-section steel is manufactured using a rectangular cross-section steel slab as a raw material, in the first step, the central bulge and the central bulge are formed in the widthwise center of the hole bottom. By forming a groove on both sides of the bulge and using a plurality of edging hole molds in which the hole bottom width is gradually widened, a rectangular cross-section steel slab is width-reduced to form an intermediate steel slab with a dogbone-shaped cross-section. In the second step, in the method of finish forming the intermediate steel slab into a rough steel slab having a predetermined H-shaped cross-section by using a finishing forming dies, the rectangular cross-section slab short by the first step first dies The shape of the central bulge of the second hole die in the first step following the engraving of the guide groove in the side portion is represented by the following equation (1), and the width reduction amount of the first pass in the second hole die is represented by the following equation. The value of r ₁ that satisfies (2) is set, and the width pressure amount after the second pass in the second hole type is expressed by the following equation.
The value of r ₂ that satisfies (3), and then the second
The shape of the process finish forming die is defined by the following formula (4), and the intermediate steel piece formed by the first process second forming die is finish formed into a rough steel piece by the second process finishing forming die. And a method for manufacturing a rough billet for H-section steel. _{θ 2 ≧ 1.2h 2 '... (} 1) r 1 ≦ d 2 -0.9 {(1 / 2d 2 + h 2) tan (θ 2/2) -h 1 tan (θ 1/2)} ... (2) r _{2 ≦ d 2 {1-0.45tan (θ} 2/2)} ... (3) d w -d f ≧ B 2 -b 0 ... (4) here, the unit of the coefficient 1.2 is in degrees / mm , Θ ₁ is the apex angle of the central bulge of the first step first hole die, the unit is degree, h ₁ is the approximate height of the central bulge of the first step first hole die, The unit is mm, θ ₂ is the apex angle of the central bulging portion of the first step second hole type, the unit is degree, and h ₂ is the approximate height of the central bulging portion of the first step second hole type. And the unit is mm, h
₂ 'is the actual height of the central bulging portion of the first step second grooved, unit mm, d ₂ is the groove roll diameter of the first step second grooved, unit mm, d _w is the diameter of the roll of the web to be rolled in the second step finish forming hole type, the unit is
mm and d _f are the diameters of rolls at the tip of the rolled material flange in the second step finish forming hole die, the unit is mm, and B ₂ is the flange of the intermediate steel piece finished by the first step second hole die. Width is a unit of mm, b ₀ is a thickness of the rectangular cross-section material steel billet, and a unit thereof is mm.

[0022]

The function of the present invention will be described in detail below. <Rotation Prevention> First, the concept of rocking prevention will be described. In the geometrical relationship between the G ₂ hole type wedge 22 a and the guide groove 52 a of the material to be rolled shown in FIG. 7, an O- (x, y) coordinate system with O as the origin and x in the right direction and y in the up direction respect, the straight line O-P 'formula to give _{the, y = xcot (θ 2'} / 2) = xcot (θ 2/2) cosα a ... (7), whereas, gives a straight line O'-P ' The formula is y = (x + s) cot (θ / 2) −k (8). Where α is the biting angle and θ is θ ₁ or θ ₂
And θ = θ ₁ when the previous rolling pass is the G ₁ hole type,
When the immediately previous rolling pass is the G ₂ hole type, θ = θ ₂ . k
(> 0) is the vertical distance between O'and O. Straight line [Formula (7)]
A straight line in order to determine the x-coordinate x _P in the formula (8)] of the intersection point P ', when erasing y from equation (8) and equation _{(7), xcot (θ 2} /2) cosα = (x + s) cot _{(θ / 2) -k x P} = {k-scot (θ / 2)} / {cot (θ / 2) -cot (θ 2/2) cosα} = {ktan (θ / 2) -s} / {1-tan (θ / 2 ) / tan (θ 2/2) · cosα} ... a (9). When this is substituted into equation _{(7), y P = {} ktan (θ / 2) -s} / {tan (θ 2/2) / cosα-tan (θ / 2)} ≒ {(h-y P) tan (θ / 2) -s} / {tan (θ 2/2) / cosα-tan (θ / 2)} , and the y-coordinate of the point _{P ', y P = {htan} (θ / 2) -s _{} cosα / tan (θ 2/} 2) ... a (10).

On the other hand, from the geometrical relation of FIG. 6, cos α = {1 / 2d ₂ + h _2- (1 / 2r-h + h ₂ ) -k} / (1 / 2d ₂ + h ₂ ) = {1 / 2d ₂ −1 / 2r + (h−k)} / (1 / 2d ₂ + h ₂ ) ≈ (1 / 2d ₂ −1 / 2r + y _P ) / (1 / 2d ₂ + h ₂ ) ... (11). Here, r is the width reduction amount, h is the rolled material guide groove depth shown in FIG. 6 or 7, and the immediately preceding reduction pass is G ₁
In case of hole type = h ₁ , h in case of immediately preceding rolling pass being G ₂ hole type
= H ₂ . Here, when cosα is obtained by eliminating y _P from formulas (10) and (11), cosα = (1 / 2d ₂ −1 / 2r) / [1 / 2d ₂ + h ₂ − {htan (θ / 2) -s} / tan (θ 2/2)] ... (12) is obtained, and substituting equation (12) to the rocking motion preventing condition given by equation (6), μ ≦ cot ( θ 2 '/ _{2) = cot (θ 2/} 2) cosα = (1 / 2d 2 - 1 / 2r) / [(1 / 2d 2 + h 2) tan (θ 2/2) - {htan (θ / 2) -s} _{] = (1 / 2d 2 -} 1 / 2r) / {(1 / 2d 2 + h 2) tan (θ 2/2) -htan (θ / 2) + s} ... (13) the equation (13) is a theoretical equation However, in reality, the centering action is reduced due to the resistance force exerted on the material from the roll surface in the roll bite, which does not follow the theory.In order to maintain consistency with the actual rolling phenomenon, The correction coefficient λ is defined by the ratio of the left side. _{That, λ = 1/2 (d} 2 -r) / {(1 / 2d 2 + h 2) tan (θ 2/2) -htan (θ / 2) + s} / μ ... (14) The present inventors , To obtain the correction coefficient λ, μ = 0.3,
d ₂ = 416 to 520 mm, s = 5 mm, θ60 to 140
Degree, θ ₂ = 90 to 140 degrees, h = 45 to 117 mm, h ₂
= 45 to 90 mm, r = 0 to 70 mm, a test was conducted to confirm the presence or absence of rocking. The result is shown in FIG.

From this result, if the correction coefficient λ ≧ 1.5, rocking can be prevented and stable edging rolling becomes possible. Substituting equation (14) into this and ignoring the small term s, the equation
(2) and equation (3) are obtained. That is, first, the G ₂ hole type 1
In the pass, the rolled material is a G ₁ hole type finished material (θ =
because it is _{θ 1, h = h 1)} , the width reduction amount r = r ₁ for swing _{prevention, r 1 ≦ d 2 -0.9 {} (1 / 2d 2 + h 2) tan (θ 2/2) _{-h 1 tan (θ 1/2} )} ... a (2). Further, since the shape of the guide groove of the rolled material after the second pass in the G ₂ hole type is θ = θ ₂ and h = h ₂ , the width reduction amount r = r ₂ for rocking prevention is r _{2 ≦ d 2 {1-0.45tan (θ 2} /2)} ... a (3).

<Prevention of Breakage Defects> Next, the breakage defects 54
The conditions for preventing a will be described. In the past, due to the effect of erasing the guide groove in the G ₃ hole type, the condition for preventing the folding flaw required for the G ₄ hole type was relatively loose, but in the process according to the present invention, the material to be rolled is guided. Due to the omission of the groove erasing step, it is a necessary condition not to reduce the apex angle of the guide groove during finish forming and rolling in the G ₄ hole type. That is, when the intermediate steel piece 53 having the flange width B ₂ and the web thickness b ₂ is formed and rolled by the G ₄ hole die (flange width reduction and web thickness reduction), in the first pass, as shown in FIG. It is necessary that no single width reduction be performed. On the contrary, if the flange width is individually reduced as shown in FIG. 12B, the guide groove is closed as shown in FIG. 5, and there is a risk that the folding groove 54a may progress. Therefore, from the geometrical relationship shown in FIG.
The condition under which the single reduction of the flange width is not performed as shown in FIG. 12 (a) is as shown in equation (4). d _w −d _f ≧ B ₂ −b ₂ = B ₂ −b ₀ (4) where d _w and d _f are G ₄ hole type rolling material web pressure roll diameter and flange tip pressure roll diameter. Is.

Next, the inventors, under the condition of the equation (4),
A manufacturing test of the H-section steel 55 was performed in the H-section steel manufacturing process of FIG. 2 to evaluate the presence or absence of the crease flaw on the outer side of the flange of the H-section steel 55. The result is shown in FIG. That is, the condition for rolling and forming without the occurrence of the folding flaw due to the guide groove between the steps from the rough-shaped steel piece 54 to the H-shaped steel 55 is related to the wedge shape of the G ₂ hole type. It was found that θ ₂ ≧ 1.2h ₂ ′ (1).

[0027] In summary, conditions for realizing a process for directly finishing rough shaped steel mold with G ₄ caliber without going through the traditional G ₃ hole-type G ₂ grooved finish intermediate steel piece, following Expression
(1) -Equation (4). _{θ 2 ≧ 1.2h 2 '... (} 1) r 1 ≦ d 2 -0.9 {(1 / 2d 2 + h 2) tan (θ 2/2) -h 1 tan (θ 1/2)} ... (2) r _{2 ≦ d 2 {1-0.45tan (θ} 2/2)} ... (3) d w -d f ≧ B 2 -b 0 ... (4)

[0028]

EXAMPLES An example of carrying out the rolling shaping of a crude billet based on the above-mentioned means of the present invention will be described below. FIG. 1 shows the hole type layout used at this time. Further, Table 1 shows condition data of the dimensions shown in FIG. This roll arrangement is the same as the H600 × 200 rough steel slab and H600 without changing the rolls.
It is a hole type arrangement for producing a rough steel slab for × 300, and is an embodiment of method I described in FIG. next,
Tables 2 and 3 show pass schedules for producing the above-mentioned two types of rough shaped steel slabs by the rough double hole rolling mill having this hole shape. Table 2 shows the pass schedule for producing rough billets for H600x300, and Table 3 shows that for H600x200. The rectangular cross-section steel pieces used have cross-sectional dimensions of 1280 mm × 250 mm and 1200 mm × 250 mm, respectively. After forming the intermediate steel piece with the same G ₁ hole type and G ₂ hole type, the former is finish-formed and rolled with the G ₄₁ hole type and the latter with the G ₄₂ hole type, respectively.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

The above-mentioned embodiment satisfies the conditions of the formulas (1) to (4), whereby the rocking prevention in the G ₂ hole type and the folding flaws in the rolling after the G ₄ hole type are completed. It was confirmed that it can be prevented. The above conditions are those of the prior art Japanese Patent Publication No.
-124503, for example, the condition is out of the range of G ₂ hole type wedge apex angle θ ₂ = 70 to 110 degrees, and it is possible to omit the G ₃ hole type by the comprehensive technology in consideration of the edging rolling condition. It is a thing.

[0033]

Effects of the Invention The present invention improves the rolling shaping efficiency by omitting the path width reduction for the guiding grooves erasure by G ₃ grooved, the omission of G ₃ grooved roll barrel length allowance As a result of making it larger and engraving another finish forming hole die G ₄ in the extra cylinder length space, it is possible to make a plurality of coarse shaped steel pieces having different cross-sectional dimensions from the same roll. Further, as a result, the roll inventory can be reduced, and the roll cost reduction effect is great.

[Brief description of drawings]

FIG. 1 is a hole type layout diagram of a rough double hole type rolling mill 1 according to an embodiment of the present invention.

FIG. 2 is a diagram showing a typical H-section steel manufacturing process.

FIG. 3 is a view showing an example of a roll hole type arrangement of a rough double hole type rolling mill 1 in a conventional method.

FIG. 4 is a diagram showing a manufacturing flow of a rough shaped steel slab 54 by the rough double hole rolling mill 1 in the conventional method.

FIG. 5 is a view showing a fold defect that occurs when the guide groove is not erased by the G ₃ hole type in the conventional method.

FIG. 6 is a view for explaining a rolled material guiding mechanism by a wedge in edging rolling of G ₂ hole type.

7 is a detailed view of the wedge portion shown in FIG.

FIG. 8 is a view showing a relationship between “rough steel billet web height” and “required roll cylinder length and roll cylinder length excess / deficiency” in the conventional method.

[Fig. 9] Fig. 9 shows the relationship between "rough steel billet web height" and "required roll body length and roll body length excess / deficiency" when two G ₄ hole types are engraved in the same roll as in the conventional method. FIG.

FIG. 10 shows “rough-shaped billet web height” and “required roll cylinder length and roll cylinder length excess / deficiency” when two G ₄ hole dies are engraved in the same roll by applying the technique of the present invention. The figure which shows a relationship.

FIG. 11 is a diagram showing the basis for determining a correction coefficient in a conditional expression for preventing rocking in the G ₂ hole type.

[12] (a) is a diagram showing a "relationship G ₂ grooved finish the cross-sectional dimensions and G ₄ caliber dimension" to prevent flaws Orekomi in finish forming rolling at G ₄ grooved, (b ) is a diagram showing a "relationship G ₂ grooved finish the cross-sectional dimensions and G ₄ grooved dimension" that can not be prevented flaws Orekomi in finish forming rolling at G ₄ grooved.

FIG. 13 Determines an appropriate wedge shape of a G ₂ hole type for roll forming without causing a crease flaw due to an induction groove during a process from a rough shaped steel piece 54 to an H shaped steel 55. Experimental data.

[Explanation of symbols]

1 rough double-hole rolling mill 2a first intermediate rough universal rolling mill 2b first edging rolling mill 3a second intermediate rough universal rolling mill 3b second edging rolling mill 4 finish universal rolling mill 11, 12 rough double-hole rolling mill Upper and lower roll pairs of machine 21a, 22a, 23a G ₁ hole type, G ₂ hole type, G ₃ hole type wedges 21b, 22b respectively G ₁ hole type, G ₂ hole type wedge both side groove portions 31, 32, 33 respectively Side wall of G ₁ hole type, G ₂ hole type, G ₃ hole type 42 H-shaped steel flange corresponding part generated by G ₂ hole type 50, 51, 52, 53, 54, 55 rectangular section steel pieces, G ₁ hole type finished billet, G ₂ hole type finished billet, G ₃
Hole type finished steel piece (intermediate steel piece), G ₄ Hole type finished steel piece (coarse shaped steel piece), H shaped steel 51a, 52a, 53a, 54a G ₁ respectively
Induction groove of rolled material in hole type, G ₂ hole type, G ₃ hole type and crease flaw in G ₄ hole type

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yamashita No. 1 Tsukiko Yawata-cho, Sakai City, Osaka Prefecture In-house Nippon Steel Co., Ltd. Inside the Sakai Steel Works of Nippon Steel Corporation

Claims (1)

[Claims] 1. A method for producing a rough-shaped steel slab for H-section steel using a rectangular cross-section steel slab as a raw material, in the first step, a central bulge and a central bulge at the center of the hole bottom in the width direction. By using a plurality of edging hole dies that have groove portions formed on both sides and the hole bottom width is gradually widened, a rectangular cross-section steel slab is width-reduced to form an intermediate steel slab with a dog-bone cross-section, and the subsequent second step is performed. Then, in the method of finish-forming the intermediate steel piece into a rough shaped steel piece having a predetermined H-shaped cross-sectional shape by using a finishing forming die, in the first step, the first forming die has a rectangular cross-section steel piece to a short side portion. The first step following the engraving of the guide groove of No. 2 is the following formula (1) for the shape of the central bulge of the second hole mold, and the width reduction amount of the first pass in the second hole mold is the following formula (2). the value of r ₁ satisfying a width amount of pressure in the second pass or later in the second hole-type satisfying the formula (3) below r ₂
And the shape of the second step finish forming die that follows this is expressed by the following formula (4), and the intermediate steel piece formed by the first step second forming die is roughened by the second step finish forming die. A method for producing a rough-shaped steel slab for H-section steel, which comprises finish-forming a shaped steel slab. _{θ 2 ≧ 1.2h 2 '... (} 1) r 1 ≦ d 2 -0.9 {(1 / 2d 2 + h 2) tan (θ 2/2) -h 1 tan (θ 1/2)} ... (2) r _{2 ≦ d 2 {1-0.45tan (θ} 2/2)} ... (3) d w -d f ≧ B 2 -b 0 ... (4) here, the unit of the coefficient 1.2 is in degrees / mm Θ ₁ is the apex angle of the central bulging portion of the first step first hole die, the unit is degree, h ₁ is the approximate height of the central bulging portion of the first step first hole die, The unit is mm, θ ₂ is the apex angle of the central bulging portion of the first step second hole type, the unit is degree, and h ₂ is the approximate height of the central bulging portion of the first step second hole type Where the unit is mm, h ₂ ′ is the actual height of the central bulge of the first step second hole type, the unit is mm, and d ₂ is the groove diameter roll diameter of the first step second hole type And
The unit is mm, d _w is the roll diameter of the rolled material web lowering roll of the second step finish forming hole type, the unit is mm, and d _f is the roll rolling material flange tip lower end of the second step finish forming hole type Roll diameter, unit is mm, B ₂ is flange width of the intermediate steel piece finished by the first step, second hole die, unit is mm, b ₀ is thickness of the rectangular section material steel piece , Unit is mm,
Is.