JP2712855B2 - Rolling method for H-section steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling an H-section steel. More specifically, the present invention relates to a method for rolling an H-beam, which is capable of providing a product having excellent rolling efficiency and high dimensional accuracy.

[0002]

2. Description of the Related Art Generally, a hot rolling of an H-section steel is performed by a breakdown rolling mill, a coarse universal rolling mill, an edger rolling mill and a finishing universal rolling mill as shown in FIG. It is performed in the step having. First, a slab having a sectional shape is shown in FIG. 9A, a rectangular slab having a sectional shape is shown in FIG. 9B, or a slab having a sectional shape is shown in FIG. 9C.
Rolling material, such as a billet for section steel, is divided into upper and lower rolls engraved with an open die as shown in Fig. 10 (a) or upper and lower rolls engraved with a closed die as shown in Fig. 10 (b). It is roughly formed into a predetermined shape by a rolling mill. In the breakdown rolling mill, a plurality of dies are used, and a rolling material is processed into a shape suitable for rolling in the subsequent steps by rolling in a plurality of passes in order.

[0003] The roughly formed rolling material is obtained by using one or more coarse universal rolling mills having rolls whose cross-sectional shape is shown in FIG. 11 (a) and an edger rolling mill having rolls having the cross-sectional shape shown in FIG. 11 (b). After one or more passes of intermediate rolling are performed by the mill, the finished H-shaped steel is rolled in one pass by a finishing universal rolling mill having a roll whose cross-sectional shape is shown in FIG. 11 (c).

[0004] In the rolling process of such an H-section steel,
When the product dimensions are determined, the roll dimensions of the finishing universal rolling mill and the roll dimensions of each rolling mill before the finishing universal rolling mill are determined. That is, the dimensions of the distance a in FIG. 10 (a), the distance b in FIG. 11 (a), the distance c in FIG. 11 (b), and the distance d in FIG. 11 (c) are almost equal. Designed to be. Therefore, when the dimensions of the product, especially the inner width of the web, which is the distance d in FIG. 11 (c), is changed,
Normally, rolling is performed by replacing the horizontal rolls of each rolling mill in addition to the grooved rolls of the breakdown rolling mill.

[0005] Rolling of an H-section steel having a large size (hereinafter referred to as "large size") is generally carried out by a roll in which a plurality of vertically symmetric hole types (open hole types) shown in FIG. This is performed as shown in FIG. In the case of a large H-section steel, the rolling load increases, so that a small dimension (hereinafter referred to as “small dimension”) H
This is because it is not possible to use a roll (see FIG. 13) formed by engraving a plurality of vertically asymmetric hole dies (closed dies) shown in FIG. 10 (b) used for rolling section steel.

When a plurality of closed dies shown in FIG. 13 are formed by a roll engraved, a plurality of the dies are arranged alternately up and down so that the material to be rolled can be rolled without rotating. Is extremely high. However, the difference between the maximum diameter and the minimum diameter of the roll becomes remarkably large due to the vertically asymmetric hole type. In general, the maximum diameter of the roll is regulated by the window width of the rolling stand, so that the absolute value of the minimum diameter of the roll becomes small and there is a risk of causing breakage of the roll. Vertically asymmetrical cavities cannot be applied to rolling. On the other hand, in the case of rolling with a vertically symmetrical grooved roll, in each pass of each grooved form, an overfill occurs on the outer surface of the flange. Becomes For this purpose, it is necessary to perform a break-in edging pass for flattening the outer surface of the flange for each pass of each mold. This requires a 90 ° rotation of the rolled material, which in turn increases the number of passes and significantly increases idle time between passes.

[0007]

As described above, the conventional H
The method of rolling section steel has the following problems.

When an H-section steel is manufactured in a hot rolling line as shown in FIG. 8, particularly when a large-size H-section steel is manufactured from a slab having the shape shown in FIG. The rough rolling process by the rolling mill becomes a bottleneck, preventing improvement in production efficiency.

FIG. 14 (a) to FIG. 14 (a) and FIG. 14 (b) show the shape of the material to be rolled by the groove rolling method in the current breakdown rolling mill.
As is evident from Fig. 14 (b), when forming the flange part with a hole mold, the reduction ratio of the web> the reduction ratio of the flange,
The metal flows from the flange to the web, causing a reduction in flange width. Therefore, after the final pass of breakdown rolling, the flange portion of the crude steel slab (beam blank) is not filled with the die, and the degree of filling is different at each end of the flange. It is a factor that worsens. For this reason, in the current groove rolling, the flange width is reduced. Therefore, a large-sized H-section steel is manufactured using a material having a large slab width and a large slab thickness. There is a limit to the improvement in the degree of filling of the slab, and the increase in the cross-sectional area of the slab leads to a decrease in the efficiency of the heating furnace and a decrease in the unit consumption of fuel.

Here, an object of the present invention is to form and manufacture a large-sized H-section steel from a slab.
The present invention provides a method for rolling an H-section steel having a satisfactory filling degree of a material to be rolled with respect to a die while reducing the number of break-in edging passes and the total number of passes in a breakdown rolling mill and improving the rolling efficiency. An object of the present invention is to stably produce a product having dimensional accuracy.

[0011]

In order to achieve the above-mentioned object, the present inventor has proposed to suppress overfill occurring at the roll collar portion on the outer surface of the flange for each pass of the groove rolling of the breakdown rolling mill, In addition to omitting the break-in edging pass, it is possible to maximize the degree of filling of the groove of the flange portion for each pass of the groove rolling of the breakdown rolling mill as much as possible. Various investigations were conducted by using a model rolling mill experiment using a simulation and a simulation using the finite element method, and the following findings were obtained.

(I) As can be understood from FIG. 1 showing the result of the simulation calculation by the finite element method, the shape of the hole-shaped fillet portion (the joint portion between the flange and the web portion) is an arc shape. When the filling degree of the material to the hole of the flange is examined by changing the size, it is clear that the larger the arc of the fillet is, the more the filling of the hole at the tip of the flange is improved, and the material to the roll collar is The amount of overhang (overfill) is also reduced. Also, as the arc becomes larger, the rolling load decreases.

(Ii) As shown in FIG. 2 showing the result of the simulation calculation by the finite element method, the apparent exclusion area of the cross section of the material by the hole-shaped roll is kept constant, that is, the remaining material of the fillet portion of the material after rolling. The straight portion of the fillet shape (in this case, the straight portion and the curved portion in which the straight portion intersects with the inner surface of the flange and the web surface is a circular arc) with the same wall thickness is the web surface. When the degree of filling of the material with respect to the hole of the flange portion is examined by variously changing the angle θ to be formed, when gradually increasing θ to make the surplus amount of the fillet portion closer to the inner surface side of the flange, the flange portion has The degree of filling is improved. In addition, as the arc of the curved portion increases, the rolling load decreases.

The present inventor has made the following
As a result of further studies, the present invention has been completed. here,
The gist of the present invention is to provide a method of rolling an H-section steel through breakdown rolling, rough universal rolling, edger rolling and finish universal rolling, wherein the breakdown rolling reduces the flange portion and the web portion of the material to be rolled. In the joint portion, a surplus portion for improving the filling degree of the groove is formed, and a web portion of only the surplus portion is made by a horizontal roll by the first pass or a plurality of passes of the subsequent rough universal rolling. Rolling, and then pass
And rolling the web and flange .

Further, in the present invention, in the first pass or the plurality of passes of the rough universal rolling, the outer peripheral surface of the flange is held in the height direction of the web by the vertical roll while holding the excess portion by the horizontal roll. By reducing the inner width of the web by rolling down, it is possible to roll a crude steel slab having a different inner width from a breakdown rolled material having the same dimensions. The surplus portion of the present invention refers to the joint (fillet portion) between the flange and the web in the breakdown rolling, and at least one pass rolling of the coarse universal rolling, which is performed after the breakdown rolling is completed. In the above, a flange or a web having a large thickness is drawn down from an outer peripheral end (corner portion) of a horizontal roll of the mill.

[0016]

Hereinafter, the present invention will be described in detail together with the functions and effects. The H-beam rolling line according to the present invention will be described using a hot rolling process shown in FIG. Also, as the material to be rolled,
An example in which a large-sized H-section steel is manufactured using a continuous cast slab as shown in FIG.

The continuous cast slab is heated by a heating furnace prior to rolling.
It is heated to around 1250 ° C and then transported to a breakdown rolling mill. In the breakdown rolling mill, the material to be rolled is first subjected to reduction in the width direction of the slab by a double roll in which a plurality of vertically symmetrical cavities as shown in FIG. 12 are engraved, and FIG. It is shaped into a dog bone shape as shown in). At this time, the hole shape was Kal-III in FIG.
Are generally used. The rolled material shaped into the dog bone shape was then Kal-
I, Kal-II, Kal-IV, and Kal-V are mainly used to reduce the thickness of the web in a hole type as shown in the figure, to a beam blank (coarse billet) having a predetermined flange width, flange thickness, and web thickness. It is roughly rolled. However, in the case of rolling a large-sized H-section steel, engraving a large number of holes as in the hole roll of FIG. 12 has a problem in roll width. Other than the above, it is common to provide one or two hole types.

In order to carry out the present invention, in a hole type roll of a breakdown rolling mill having flange forming holes on both sides of a web pressing portion, an excess portion is provided near a joint portion between the flange portion of the material to be rolled and the web. The hole-shaped shape is designed and processed so as to form. The size of the surplus portion may be such that the flange of the material to be rolled completely fills the groove portion of the horizontal roll during rough universal rolling, as described later. Generally, it is about 5 to 10% of the entire cross section of the beam blank after the completion of the breakdown rolling. For example, the beam blank has an arc shape as shown in FIG. 1 or a shape composed of a straight line and a curve as shown in FIG. First, a roll hole die for rolling the fillet portion of the material to be rolled is processed. In the case of the arc-shaped fillet shown in Fig. 1, the inner width of the flange of the product
(Flange width-web thickness) It is preferable to use an arc having a radius having a maximum value of 1/2, and in the case of a fillet portion having the shape shown in FIG. 2, the angle θ formed between the straight portion and the web surface. Is preferably set to 40 to 60 °.

As described above, in the fillet portion of the material to be rolled,
The point of the present invention is to form a large excess thickness portion compared to the beam blank shape after the conventional breakdown rolling and to perform rough universal rolling. For this reason, the width of the web pressing portion of the forming die (the distance a in FIG. 10 (a) is the width of the horizontal roll of each mill after rough universal rolling (FIG. 11).
(A) distance b, Fig. 11 (b) distance c, Fig. 11 (c) distance d)
, And considerably smaller than the inner web width of the product.

According to the present invention, the beam blank at the stage of forming by the grooved roll of the breakdown rolling mill has a larger fillet portion than that of the beam blank in the conventional rolling method. In the rough universal rolling that is performed subsequently after the breakdown rolling, the web is partially rolled only in the excess thickness portion by a horizontal roll by the first one pass or a plurality of passes of two to three passes, so that the thickness is flat to the web central portion. There is no problem because it is made uniform.

In general, in the case of the universal rolling, the web may be wavy if the reduction of the web is too large as compared with the reduction of the flange. However, in the present invention, the joint between the web and the flange is first partially removed. Because of the reduction, the elongation of each of the web and the flange is equalized, and no web waving occurs. In this manner, by the breakdown rolling, a surplus portion is formed in the fillet portion of the material to be rolled, and by performing the subsequent rolling, the overfill generated in the roll collar portion of the material to be rolled is suppressed,
The degree of filling of the flange of the material to be rolled into the groove can be improved.

Further, according to the method for rolling an H-section steel according to the present invention, a breakdown-rolled material having the same dimensions can be formed from:
High dimensional accuracy H-section steels having different web inner widths can be stably manufactured. FIG. 3 (a) is a schematic explanatory view showing a situation where rough universal rolling of an H-section steel is performed according to the present invention, and FIG. 3 (b) shows a cross-sectional shape of a material to be rolled at the end of the rough rolling. FIG. 3 (a), the width H ₁ of the horizontal rolls of the rolling mill, as described above, is usually that equal the web in the width of the finished product, even web inner width H ₀ of the rough shape steel piece to this generally with respect to approximately equal to H _1, when practicing the present invention is capable of the H ₀ is increased about 50~100mm than H _1.

In other words, when the present invention is carried out, in the breakdown rolling, in order to form a surplus portion in the fillet portion of the material to be rolled, a horizontal roll is used in one or more passes of the subsequent rough universal rolling. while holding the excess thickness portions, by reduction of the flange outer surface to the web height direction perpendicular roll, as shown in FIG. 3 (b), H ₀ -
Only H _1, it is possible to reduce the web inner width, and the web center bias of the crude shaped steel strip shape after rolling: the (A-B) / 2 and not to little occur can perform stable rolling.

On the other hand, FIG. 4 (a) is a schematic cross-sectional view showing a general method of rolling a rough shaped steel slab which does not cause a fillet portion of a material to be rolled in breakdown rolling. FIG. 4B is a schematic explanatory view showing an example of the cross-sectional shape of the rough rolled material at the end of the rough rolling. Fig. 4 (a)
As shown in, when the outer surface of the flange is rolled down in the height direction of the web by a vertical roll in one or more passes of a coarse universal rolling mill, the flange portion of the material to be rolled is easily deformed upward or downward with respect to the web. As a result, as shown in FIG. 4 (b), a large shaped steel slab having a large web center deviation (A−B) / 2 as shown in FIG.

Thus, according to the present invention, it becomes possible to manufacture H-section steels having different inner web widths from the same breakdown rolled material, and the web height of the product:
Breakdown rolls having different rolls at 50 mm pitch can be shared, and the number of rolls held can be significantly reduced. Further, the present invention will be described in more detail with reference to examples, but this is merely an example of the present invention, and the present invention is not limited thereto.

[0026]

EXAMPLE In order to confirm the effect of the method for rolling an H-section steel according to the present invention, the production of JIS size H-section steel H600 × 300 (nominal dimensions) was performed using a rolling line having a group of rolling mills shown in FIG. Carried out. The rolled material was a continuous cast slab having a thickness of 250 mm, which was heated to 1250 ° C. in a heating furnace and subjected to rolling.

FIG. 5 is a diagram showing a breakdown roll hole shape and an edger roll hole shape according to the method for rolling an H-section steel according to the present invention. In addition, a diagram of a breakdown roll sculpture for performing the above is shown. Among the dies for carrying out the present invention shown in FIG. 5, Kal-I to Kal-IV are dies for shaping a slab into a dogbone shape, and are used for performing a conventional rolling method. It had the same shape as the mold. Further, among the hole types for carrying out the present invention, Kal-I to Kal-V are roll hole types of a breakdown rolling mill,
VI is a roll hole shape of an edger rolling mill. As can be seen by comparing the hole shape Kal-V and the conventional hole shape for carrying out the present invention, the hole shape for carrying out the present invention in which the fillet portion of the material to be rolled is rolled, the fillet portion includes:
It is designed in a shape that easily forms a surplus portion consisting of a straight line and a circular arc.

The rolling pass schedule adopted in this embodiment is shown in Table 1, and the cross-sectional shape of the material to be rolled on the roll exit side in a representative pass of the same pass schedule is shown in FIGS.
This is shown in (b). In addition, the left side of Table 1 shows, for comparison, the cross-sectional shape on the roll exit side of the material to be rolled in the representative pass of the conventional H-beam rolling method.

[0029]

[Table 1]

As can be seen from Table 1, in the case of the method of the present invention, the number of turns of the material in the breakdown rolling can be reduced from 10 to 6 times as compared with the conventional method, and the Kal-V in the method of the present invention can be further reduced. In the case of the groove rolling, the rolling load is reduced if the web rolling reduction is the same as compared with the conventional groove rolling, and conversely, the web rolling amount per pass can be increased, and as a result, As a result, the number of passes of the breakdown rolling was significantly reduced from 21 passes to 13 passes.

As shown in FIG. 6 (b), in the case of the present invention, in the final pass (13 passes) of the breakdown rolling, the grooved die is almost completely filled with the rolled material. The cross-sectional shape of the material to be rolled after breakdown rolling could be made uniform as compared with the conventional rolling of an H-section steel shown in FIG.
Further, in the case of the present invention, it is possible to make the continuous casting slab width of the material considerably smaller than that of the conventional one, thereby improving the material filling rate in the heating furnace and reducing the heating unit consumption. I was able to plan.

In the pass schedule of the present invention, since the excess amount of the fillet portion of the rough steel slab after the breakdown rolling is large, the coarse universal rolling: three passes and the edger rolling: one pass reduce the thickness of this portion. Rolling mainly with
Finally, a beam blank having a uniform shape was obtained. Thereafter, this beam blank was subjected to 10 pass reversal rolling with UR-E, and was able to be finished to a shape close to a product.
Therefore, the total number of passes in UR-E was 13, which could be the same as the number of passes in the conventional coarse universal and edger rolling.

FIG. 7 shows H600 × H600 in each of the case where the method of the present invention is applied and the case where the conventional rolling method is applied.
4 shows the web center deviation distribution of the H-section steel confirmed by actual rolling of 300 size. As is clear from FIG. 7, it can be seen that the present invention suppresses the occurrence of web center deviation.

[0034]

As described in detail above, according to the present invention, by providing a new method for rolling an H-section steel using a breakdown rolling mill and a coarse universal rolling mill, the number of turns of a material in breakdown rolling can be reduced. By reducing the number of passes, it is possible to improve the rolling efficiency, and also to improve the dimensional accuracy of the product, reduce the number of breakdown rolls, reduce the energy consumption of heating rolls, and achieve many other effects. Was completed. The significance of the present invention having such effects is remarkable.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a deformation state of various fillet portions of a material to be rolled due to a groove shape.

FIG. 2 is a schematic explanatory view showing deformation states of various fillet portions of a material to be rolled due to a groove shape.

FIGS. 3A and 3B are schematic illustrations of a deformation process of a material to be rolled in the method of rolling an H-section steel according to the present invention, wherein FIG. 3A shows a state at the start of rolling, and FIG. Show.

FIG. 4 is a schematic explanatory view of a deformation process of a material to be rolled in a conventional method of rolling an H-section steel, and FIG.
FIG. 4B shows the state at the end of rolling.

FIG. 5 is a schematic cross-sectional view showing a hole shape of each of a breakdown roll and an edger roll according to the present invention method and the conventional method in an example.

FIG. 6 is a schematic cross-sectional view showing the shape of a material to be rolled in each step of breakdown rolling, rough universal rolling, and edger rolling in Examples. FIG. 6 (a) shows a conventional method, and FIG. ) Indicates the method of the present invention.

FIG. 7 is a schematic explanatory view showing the web center deviation distribution of a product after rolling in the examples according to the method of the present invention and the conventional method.

FIG. 8 is a schematic explanatory view showing a general configuration example of a hot rolling line for H-section steel.

9 is a schematic cross-sectional view showing the cross-sectional shape of various rolled materials. FIG. 9 (a) shows a slab, FIG. 9 (b) shows a rectangular slab, and FIG. 9 (c) shows steel for H-section steel. Each piece is shown.

10 is a roll cross-sectional view showing a cross-sectional shape of a roll hole type, in which FIG. 10 (a) shows an open type and FIG. 10 (b) shows a closed type.

11 is a schematic sectional view showing the process of hot rolling of an H-section steel, where FIG. 11 (a) shows rough universal rolling, FIG. 11 (b) shows edger rolling, and FIG. 11 (c) shows finishing 3 shows universal rolling.

FIG. 12 is a schematic sectional view of a breakdown roll having a plurality of aperture types.

FIG. 13 is a schematic sectional view of a breakdown roll having a plurality of closed holes.

FIG. 14 shows a conventional breakdown rolling process.
FIG. 3 is a schematic sectional view showing a change in a sectional shape of a material to be rolled;
14 (a) shows the state after the dogbone shaping, FIG. 14 (b) shows the state after one pass of the groove rolling, and FIG. 14 (c) shows the state after the final pass of the groove rolling.

Claims (2)

(57) [Claims] 1. A method for rolling an H-section steel through breakdown rolling, rough universal rolling, edger rolling, and finishing universal rolling, wherein the breakdown rolling includes a joining portion between a flange portion and a web portion of a material to be rolled , Forming extra space to improve the filling of the mold ,
In the first pass or multiple passes of the subsequent rough universal rolling, the web is partially rolled only in the excess portion with a horizontal roll, and the web and the roll are passed in subsequent passes.
A method for rolling an H-section steel, comprising rolling a flange and a flange . 2. In a first pass or a plurality of passes of the rough universal rolling, while holding a surplus portion by a horizontal roll, a flange roll is pressed down in a web height direction by a vertical roll to reduce a web inner width. The method for rolling an H-section steel according to claim 1, wherein the reduction is performed.