JPH04200901A - Rolling method of h-shape steel - Google Patents

Abstract

PURPOSE:To make the improvement of the contraction limit of the inside width of web possible without generating buckling and twisting by driving vertical rolls of a universal rolling mill at the time of executing the rolling of H-shape steel accompanied the rolling-down of web height. CONSTITUTION:The vertical rolls V of the universal rolling mill 9 are driven, propulsive force is added to the flange parts (hb) in a region I or the web part (ha) through them and the reaction force Pf in the rolling direction is drastically reduced. Then, the contraction limit of the web height can be extended. Therefore, the increase of the number of rolling pass and the minimization of roll change are possible and production efficiency can be still more improved.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is useful for rolling H-beam steel with a constant web height regardless of the roll wear of rolling rolls, and for rolling H-beam steel with a constant web height regardless of the roll wear of rolling rolls, and The present invention relates to a rolling method that is advantageous when rolling H-beam steel.

(Prior Art) Generally, H-beams are produced by a rough universal rolling mill 2, an edger rolling mill 3, and a finishing universal rolling mill downstream of a breakdown rolling mill 1, as shown in FIGS. 5(a) and 5(b). 6(a),
It is manufactured by hot rolling raw materials 5, 6, or 7 having various cross-sectional shapes as shown in (b) and (c).

The materials shown in FIGS. 6(a), (b), and (c) (numeral 5 is a slab, numeral 6 is a rectangular steel billet, and numeral 7 is a steel billet for section steel) are first processed in a breakdown rolling machine. 1, the rolling mill used for this process usually cuts an open-hole shape 8 or a closed-hole shape 9 as shown in FIGS. 7(a) and (b). A double breakdown rolling mill with upper and lower rolls is used.

Rolling by the breakdown rolling mill 1 is a process of processing a material into a shape suitable for subsequent intermediate rolling by sequentially rolling multiple passes using a plurality of flower shapes.

The raw material that has been roughly shaped through the above rolling is then shown in Figure 8 (
one or more rough universal rolling mills [10] equipped with rolls having the shape as shown in FIG.
(1) Intermediate rolling is performed in a pass or multiple passes, and then rolled into 11 section steel products in one pass in a finishing universal rolling mill 12 equipped with rolls having a shape as shown in FIG. 8(c). be done. Therefore, once the product dimensions are determined, the roll dimensions of the finishing universal rolling mill 12 and the roll dimensions of the previous rolling mills are determined.
) and dimensions (b) to (d) in FIGS. 8(a) to (c) are designed to be approximately equal.

In rolling IJ sections, as mentioned above, the shape change of the material after breakdown rolling is limited, and only certain series (for example +1600 x 300 etc.)
When rolling H-beam steel, horizontal rolls with a specific width suitable for rolling are generally used.

H-shaped steel rolled by such horizontal rolls with a specific width has a constant inner web width, but for example, in one series, several types of shaped steel with different thicknesses are rolled using the same rolling roll. is usually manufactured by rolling with different roll spacing between horizontal rolls and vertical rolls, and in this case, the difference in thickness between the maximum and minimum flange thickness of the section steel product is, for example, on one side. The web height changes by around 10 mm, and on both sides it changes by about 32 mm, which is twice that amount.

Changes in web height within the same series are thus unavoidable in conventional rolling methods, and when using this as a construction material, there are problems as described below.

In other words, when a beam is made by joining multiple H-section steels of several sizes in the same series, if there are variations in the web heights of the section steels, when the outer surfaces of the flanges of one of them are put together, there will be a large ( (twice the flange thickness difference), which causes a problem during construction.

Also, when designing the structure of a building, dimensions are usually determined sequentially from the outside to the inside (however, the inner web width is constant, and the flange thickness and web height (outer dimension) are determined sequentially from the outside to the inside. With changing H-beams, this becomes a serious problem when exact dimensions are required at the construction site.

H-shaped steel manufactured by rolling has the above problems, so H-shaped steel, which is manufactured by welding plates so that the web height remains constant even if the flange thickness changes, is particularly useful for construction purposes. Steel is used, which has the disadvantage of being more expensive to manufacture than rolled H-section steel.

As a technique for solving such problems, the inventors disclosed in Japanese Unexamined Patent Publication No. 2-80102 that a rough-shaped steel billet having a web and flanges that has been subjected to breakdown rolling and rough rolling is horizontally rolled in the finish rolling stage. By setting the roll width of the roll (a roll whose width can be changed) to be smaller than the roll width at the rough rolling stage, the angle of the flange part of the crude steel billet and the web are set as shown in Fig. 9(a) and (b). We proposed a rolling method that performs finish rolling that involves reduction of the height and thickness of the flange, and freely reduces and adjusts the inner width of the web.With this rolling method, even when rolling that changes the flange thickness is performed, the web height remains unchanged. It has become possible to efficiently manufacture H-beam steel with a constant length. However, even in this rolling method, there is a limit to the amount of reduction in web height, as described below, and there has been a desire to develop a rolling method that can achieve greater reduction.

In other words, when reducing the web height by setting the roll width of the horizontal rolls of the finishing universal rolling mill to be smaller than the inner width of the web of the rough-shaped steel billet that has undergone rough rolling, The contact state is as shown in FIG.

Here, the reduction of the web inner width Biyo is carried out by the vertical roll ■, so under normal roll diameter and rolling reduction, the vertical roll ■ comes into contact with the rough shaped steel piece before the horizontal roll H. , then a reduction in the web height is carried out until the sides of the horizontal rolls H touch. In this way, the web inner width Bw. The reduction is mainly carried out in the area slightly on the entry side due to the contact area between the horizontal roll H of the rolling mill and the web part ha of the rough shaped steel piece, but in the area before the rolling of the web part ha begins, the vertical and horizontal 1'' - As shown in Figure 11(a), the gap between the first and second wheels H is larger than the web thickness, so in some cases the first
As shown in FIGS. 1(b) and 1(c), buckling or twisting of the web portion ha occurs. Since the web portion ha of the rough shaped steel piece is rolled down by the horizontal rolls H, even if the web ha is buckled on the entry side of the rolling mill, the shape after rolling will almost match the gap between the rolls. However, there is a problem in that when the buckling is corrected by rolling down the horizontal roll H, the contact pressure locally increases between the web and the horizontal roll surface, causing scratches on the web surface of the product.

Furthermore, if the web is twisted on the entrance side of the rolling mill, it will pass through the rolling mill with the widthwise center of the flange hbO out of the gap between the horizontal rolls H.
), as shown in (b), problems such as web centering bias and web reversal phenomena occur.

Such defects are more noticeable as the web of the rough shaped steel billet before the finishing rolling mill is thinner and wider, and the larger the amount of reduction adjustment is, the more likely it is to occur.

The web thickness of the rough-shaped steel billet before finish rolling is determined from the appropriate reduction amount in universal rolling, and the inner web width before rolling is determined by the rough-shaped steel billet that has the thinnest flange thickness within the same rolling chance. The value is equivalent to the inner width of the web.

Therefore, in order to prevent the above-mentioned quality defects in finish rolling, a limit is set on the amount of reduction per pass depending on the thickness of the web and its inner width, and the required amount of reduction is set to this limit value. If the number of buses exceeded 1, it was necessary to divide the bus into two or more buses.

In Japanese Patent Application Laid-Open No. 2-80102 previously disclosed by the inventors, the limit value of the web inner width reduction amount is set as ΔB engineering 3X (m
m), web thickness before rolling T (mm), web inner width B
It was decided to carry out rolling so as to satisfy the condition of ΔB+,...X-80·T''/Btn.

That is, when the width reduction amount ΔB8 per bus exceeds ΔB8□ calculated from the above equation, the width reduction amount in one bus is restricted by dividing into two or more buses.

However, rolling in two or more passes during finish rolling not only causes a drop in the temperature of the rolled material, resulting in poor shape such as web waves and deterioration of the material, but also reduces production efficiency, so it is usually done in one pass. It has become clear that this is desirable, and that even higher reduction limits may be required in actual operations.

It is also possible to partially reduce the inner width of the web during the rough rolling stage, but when rolling with variable width rolls, increasing the amount of rolling creates a step, so it is not possible to reduce the web thickness by a large amount. Therefore, it was necessary to provide a dedicated bus for reducing the web height, which resulted in an increase in the number of passes, resulting in the same problems as described above.

(Problems to be Solved by the Invention) The purpose of the present invention is to further improve the limit of the amount of web inner width reduction without causing buckling or twisting that is likely to occur in rolling involving web height reduction. This is where we propose a rolling method to obtain the desired results.

(Another means to solve the problem) In a normal universal rolling mill, horizontal rolls are driven,
The vertical rolls are non-driven. The reason for this is that driving the vertical rolls complicates the mechanism, making the frequent roll replacement work complicated during operation, and there are few advantages to driving the vertical rolls. However, in universal rolling involving a reduction in web height, it has been found that driving the vertical rolls of the rolling mill is extremely effective in increasing the amount of web inner width reduction.

This invention is based on the findings described in section 2.

That is, the present invention provides a rough-rolled rough-shaped steel billet having a web portion and a flange portion, and a pair of vertical rolls that sandwich the flange portion of the rough-shaped steel billet on the left and right sides, and a web portion of the rough-shaped steel billet. Using a universal rolling mill equipped with a pair of horizontal rolls that are sandwiched above and below and have a roll width smaller than that at the rough rolling stage, the web height and flange part are adjusted while raising the angle of the flange part and the fuller of the shaped steel piece. This is a method of rolling an IJ section steel in which the web inner width dimension is reduced and adjusted by performing finish rolling to reduce the thickness, and is characterized in that rolling is carried out by driving the vertical rolls.

(Function) The roll width of the horizontal roll of the finishing universal rolling mill is set to be smaller than the web inner width of the rough-shaped steel billet that has undergone rough rolling, and the roll and rough-shaped steel strip are adjusted to reduce the inner width of the web. The contact state and the reaction force from the vertical rolls acting on the web surface are schematically shown in FIG. 1 and FIG. 2. Of these, Figure 1 shows the case where vertical roll V and horizontal roll ■1 are driven.
1. FIG. 2 shows the case where the vertical rolls (2) are not driven and only the horizontal rolls are driven for rolling.

Here, in FIGS. 1 and 2 above, first, the outer surface of the flange portion hb of the rough shaped steel piece entering the rolling mill from the entrance side comes into contact with the vertical roll. At this time, the flange portion hb
Since the inner surface of is not yet in contact with the side surface of the horizontal roll, only the height of the web portion ha is reduced (area ■).
6 Next, the inner surface of the flange portion hb contacts the side surface of the horizontal roll, and in this state, the height of the web portion ha is no longer reduced, but the thickness of the flange portion hb is reduced.

Further, under normal roll diameter and rolling conditions, the horizontal roll surface is not yet in contact with the web ha (area J). Then, the surface of the horizontal roll comes into contact with the web portion ha, and at the same time the thickness of the web ha is reduced, the thickness of the flange portion hb is also reduced (region K). In this way, the height reduction of the nib portion ha proceeds in the region I on the entry side of the rolling mill in both cases.

Here, considering the reaction force from the rolls acting on the web part ha in region I, since the height of the web part ha is being reduced in this part, it is natural that the reaction force in the web height direction from the vertical roll V is Compressive force P8 acts. This reaction force P acts in the height direction of the web in region I, and since the horizontal roll is not yet in contact with the web surface, the web portion ha is free, making it easy for the web to buckle or twist. It is. However, the region I is relatively close to the region K where the web is restrained, and the buckling limit is not so low if only the reaction force P is applied.

However, a reaction force in the rolling direction from the vertical rolls V also acts on the web ha. The reason for this is explained with reference to FIG. 2 in which the vertical rolls are not driven. When only the horizontal rolls are driven, the driving force in the rolling direction applied to the rough shaped steel piece is This is in the region K where the web thickness reduction is performed, and for the flange portion hb, it is in the regions J and K where the thickness reduction is performed and is in contact with the horizontal roll, and in the region ■, the outer surface of the flange portion hb is vertical. Although it is in contact with the roll (2), the vertical roll (2) has no driving force, so no driving force acts on the rough shaped steel piece. In other words, the material in area (3) is dragged forward by the material in front of it. However, in region I, since the web height is being reduced, a resistance force acts against the propulsion in the rolling direction.

In other words, the reaction force Pf in the rolling direction from the vertical roll (2) acts as a reaction to the force pulled from the material in front.

As a result, in region I, as a reaction force from the vertical roll (■) in the web portion ha, a reaction force P, which is the resultant force of the reaction force Pw in the web height direction and the reaction force Pf in the rolling direction, is as shown in Fig. 2. It will act diagonally. This reaction force P is
The magnitude thereof is larger than the reaction force Piy, and it acts to buckle the web in a portion closer to the entrance of the rolling mill than region I.

For this reason, a large compressive force acts on a relatively small area far from the region K where the web is restrained, and therefore, when the vertical rolls are not driven, the amount of reduction in the web height is The limit value was low.

In this invention, the vertical roll (2) of the universal rolling mill is also driven, so that the area I as shown in FIG.
flange part hb or web part h through it
Since a driving force is added to a and the above Pf is significantly reduced, the limit amount for reducing the web height can be expanded.

FIG. 3 shows the rolling situation in normal universal rolling without reducing the web height. In such rolling, since there is no reduction in web height, the above-mentioned region (2) does not exist.

However, in the final universal rolling stage, there is an angle of the flange, so there is a part similar to Region I, but the reaction force from the vertical rolls in this case is very small compared to the case where the web height is reduced. So it's not a problem. Therefore, there is no reaction force in the web height direction acting on the web portion ha, and the above-mentioned problem does not occur, so there is no point in deliberately driving the vertical rolls.

As explained above, in this invention, when rolling an H-section steel that involves web height reduction, it is possible to expand the reduction limit of the web height by driving the vertical rolls of the universal rolling mill. As a result, H-section steel of various sizes can be rolled without increasing the number of rolling passes, and even if the roll width of the rolling rolls changes due to roll wear associated with an increase in the number of rolling passes, the web height can be reduced. By adjusting the amount, an H-section steel with a constant web height can be obtained.

In carrying out the present invention, it is preferable that the circumferential speed of the vertical roll is set within a range that roughly matches the circumferential speed of the horizontal roll.

(Example) H750X 200, which is a typical nominal dimension of H-beam steel
, H600x200, and H450x200, the web thickness is 6 to 1.
We investigated the rolling conditions when width reduction rolling was performed with various changes within the range of 6 mm.

The web thickness before finish rolling is Tw (mm), the web inner width is Bw, the reduction amount of the web inner width is 68w, the increase in web center deviation ΔC, the horizontal axis is the value of 68w・Bw/Tw2, and the vertical axis is FIG. 4 shows a plot of the value of ΔC/Tw on the axis. In Fig. 4, the plotted points of ○ and
The plot points of △ and m are the experimental results obtained when rolling was carried out according to the present invention (both horizontal and vertical rolls of the universal rolling mill were driven, with the same circumferential speed). This is the result. In addition,
The white plot points in the figure indicate that no scratch pattern was generated on the web surface after rolling, and the black plot points indicate that a scratch pattern was generated.

From Figure 4, it can be seen that as the value of the horizontal axis increases, that is, for a certain value of web thickness, the amount of reduction in the inner width of the web increases, and as the inner width of the web increases, the value of the deviation at the center of the web becomes exponential. It can be seen that the probability of occurrence of scratches on the web surface increases as well. However, it can be seen that in rolling according to the method according to the present invention, the deviation amount of the web center and the probability of occurrence of flaws are significantly smaller for the same value of the horizontal axis than in the conventional method.

Here, the deviation of the web center is J
Considering that the target is ±2 mm, which is stricter than ISG 3192, and the product is 6 mm in size, which is the thinnest in the current rolled H-section steel, the vertical axis ΔC/Tw in FIG. 4 has a value of 0.33 as the limit. Furthermore, if the goal is not to cause scratches on the web surface, the horizontal axis ΔB++-Bw/Tw2 in FIG. 4 is at most 80 in the conventional method. That is, the amount of width reduction per pass is given by the following formula %. On the other hand, according to the present invention, the value of the horizontal axis in "1" has a limit of about 120, and therefore, the limit width reduction amount is given by the following formula %. Therefore, according to this invention, the critical width reduction amount is
It was possible to increase the size by about 1.5 times compared to the conventional method.

In this embodiment, a rolling mill in which horizontal rolls and vertical rolls are driven simultaneously is applied, but in this invention, even if the horizontal rolls are not driven and only the vertical rolls are driven, It is possible to carry out rolling as long as it involves reducing the inner width of the web. Furthermore, in this invention, the horizontal rolls of the rolling mill are rolls that can change the width of conventionally known rolls (for example, JP-A-1-31
7607) is applied, but if the roll width is
Narrower than the inner width of the web part of the rough-shaped steel billet before rolling (and applicable in rolling methods where the gap between the left and right vertical rolls is set smaller than the web height of the rough-shaped billet, and the inner width of the web is reduced) It goes without saying that it can be done.

(Effect of the invention) According to the present invention, normal rolling is performed in the rough universal rolling stage, and the web height is actively reduced by adjusting the roll outer width dimension of the horizontal roll in the finishing universal rolling stage. When adjusting the inner web width by performing
The limit of the amount of reduction adjustment can be greatly expanded, and therefore the number of rolling passes can be increased and roll replacement can be kept to a minimum, making it possible to further improve production efficiency.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the rolling procedure for H-section steel according to the present invention. Figures 2 and 3 are explanatory diagrams of the rolling procedure for H-section steel according to the conventional method. Figure 4 is a defective shape that occurs during the rolling process of H-section steel. Figure 5 is a graph showing the limits of occurrence of surface defects (aL (b) is a diagram schematically showing an example of equipment for a rolling line for H-section steel; Figure 6 is (a), (b), (c)) Figures 7(a) and 8(b) show the cross-section of a material for rolling H-section steel, and Figures 8(a), (b), and (c) show the caliber shape of rolling rolls in breakdown rolling. ) shows the cross section of a rolling roll conventionally used for rolling H-section steel.
Figures (a), (b), Figures 10 and 11 (a)
, (b), (-C-n is an explanatory diagram of the conventional rolling procedure. Figures 12 (a) and (b) are diagrams illustrating the occurrence of shape defects in a rolling method that involves reduction in the height of the web. 1...Slab 2...Rectangular steel piece 3...
・Slab for H-shaped steel 4...Open caliber 5・
... Claus!・Caliber 6...Breakdown rolling mill 7...Rough universal rolling mill 8...Edgeer rolling mill 9...Nyuniharzal rolling mill h...Rough shaped billet ha...Rough shaped steel Piece web part hb...Rough steel billet flange part H...Horizontal roll ■...Vertical roll Fig. 5 (a) (b) ■ ○ ○ Fig. 7 Fig. 8 Fig. 12 (a) 11 .

Claims (1)

[Scope of Claims] 1. A roughly rolled steel billet having a web portion and a flange portion, a pair of vertical rolls that sandwich the flange portion of the rough shaped steel billet on the left and right sides, and a web of the rough shaped steel billet. Using a universal rolling mill equipped with a pair of horizontal rolls that sandwich the sections vertically and have a roll width smaller than that at the rough rolling stage, the web height and thickness of the flange section are reduced while raising the angle of the flange section of the rough-shaped steel billet. A method for rolling an H-section steel in which the web inner width dimension is reduced and adjusted by performing finish rolling.