JP7633496B2 - Manufacturing method of steel sheet pile - Google Patents

Description

The present invention relates to a method for manufacturing steel sheet piles in a steel section factory equipped with a universal mill and an edger mill, in which joints in the steel sheet piles are formed using an edger mill.

For example, in the civil engineering and construction fields, the forming of the joints (claws) of steel sheet piles used to form earth retaining and revetment structures is generally performed simultaneously with the thickness reduction of the steel sheet pile body (e.g., flanges, webs, etc.) using a hole mold. A steel mill capable of producing H-beams and steel sheet piles is mainly composed of a roughing mill (BD mill), an intermediate rolling mill (universal mill, edger mill), and a finishing rolling mill, and when manufacturing steel sheet piles, the rough shaped material discharged from the heating furnace is rolled into steel sheet piles by a rolling mill row consisting of these rolling mills. However, the above-mentioned edger mill (compact 2Hi rolling mill) is a rolling mill used to form the flange width when rolling H-beams, and is not used as a rule in the manufacture of steel sheet piles.

Conventionally, the formation of the joints of steel sheet piles is generally performed when the entire material to be rolled (steel sheet pile) is rolled. In the intermediate rolling mill, a first groove (see FIG. 2(a)) that stretches the entire cross section of the material to be rolled and a second groove (see FIG. 2(b)) that adjusts the joint height of the material to be rolled are arranged in parallel. After rolling the material to be rolled with the first groove, the material to be rolled is shifted and the entire material is rolled with the second groove, including highly accurate dimensional adjustment of the joint. In addition, the first and second grooves are arranged in parallel in the intermediate rolling mill because a large-scale mill capable of applying an extremely large rolling load (rolling torque) is required to roll the entire material to be rolled, and it is extremely difficult to arrange multiple such large-scale mills in series from the viewpoint of concerns about the expansion of the rolling line and rolling equipment and the rise in costs.

However, when the material to be rolled is shifted in the width direction between the first and second grooves described above, rolling elongation has already occurred, making it difficult to shift the steel material uniformly over its entire length, and problems such as left and right misalignment are likely to occur in the next rolling pass. In particular, the cropped portion is prone to deformation imbalance between the left and right, so it is often not accurately fitted into the groove. In addition, pitch loss occurs due to the shift, which causes problems such as a drop in rolling temperature and a decrease in productivity.

For example, Patent Document 1 discloses a method for manufacturing straight steel sheet piles in which reciprocating rolling (hereinafter also referred to as multi-pass rolling) is performed on the same pass line without shifting using a roughing universal rolling mill and an edger rolling mill.

JP 2001-170703 A

However, in the manufacturing method described in the above Patent Document 1, although the manufacturing of straight steel sheet piles is disclosed, the manufacturing of steel sheet piles of other shapes, such as U-shaped steel sheet piles and hat-shaped steel sheet piles, is not described. This is because the rolling load of an edger rolling mill is generally only half the rolling load of an intermediate rolling mill (for example, the rolling load of an intermediate rolling mill is 1000 t or more, and the rolling load of an edger rolling mill is less than 400 t), and therefore there is a problem that the rolling load of the edger rolling mill is insufficient to roll the entire U-shaped steel sheet pile or hat-shaped steel sheet pile in one rolling line including the edger rolling mill.

In view of the above circumstances, the object of the present invention is to provide a method for manufacturing steel sheet piles that can efficiently roll steel sheet piles by effectively utilizing edge rolling machines in one rolling line, without shifting the material to be rolled between the grooves of an intermediate rolling mill using H-beam rolling equipment.

In order to achieve the above object, according to the present invention, there is provided a method for manufacturing a steel sheet pile having a flange portion, a web portion and a joint portion, the method comprising the steps of: in a rolling line including a universal mill and an edge mill arranged in series adjacent to the universal mill along the rolling direction, reducing the entire cross-sectional thickness of the rolled material by the universal mill; reducing and forming a joint corresponding portion of the rolled material by the edge mill; in reducing and forming the joint corresponding portion in the edge mill, a gap is provided between the roll and the rolled material at the web corresponding portion of the rolled material, except for a connection portion with the flange corresponding portion of the rolled material; in the flange corresponding portion of the rolled material, the rolled material is restrained, including a connection portion with the web corresponding portion and a connection portion with the arm corresponding portion of the rolled material; and in the arm corresponding portion of the rolled material, a gap is provided between the roll and the rolled material, except for a connection portion with the flange corresponding portion and a connection portion with the joint corresponding portion .

In addition, in the manufacturing method of the steel sheet pile, the reduction of the entire cross-sectional thickness of the rolled material and the reduction and shaping of the joint corresponding portion of the rolled material are performed by multi-pass rolling in which the universal mill and the edge mill are continuously moved back and forth multiple times, and the reduction and shaping of the joint corresponding portion of the rolled material by the edge mill may be performed only at the end of the multi-pass rolling.

According to the present invention, a method for manufacturing steel sheet piles is provided that can efficiently roll steel sheet piles by effectively utilizing edge rolling machines in one rolling line without shifting the rolled material between the grooves of an intermediate rolling mill using H-beam rolling equipment.

FIG. 1 is a schematic explanatory diagram of a rolling facility. 1A is a schematic diagram of the groove cross-sectional shape of a universal mill that constitutes a second intermediate rolling mill, and FIG. 1B is a schematic diagram of the groove cross-sectional shape of an edge mill. FIG. 2 is a schematic overall cross-sectional view showing a state in which a material to be rolled is restrained in an edger mill. FIG. 4 is a schematic diagram of a web-compatible portion. FIG. FIG. FIG. 13 is an explanatory diagram showing the rolling load performance of a conventional groove of a completely non-constrained type. FIG. 11 is an explanatory diagram regarding the rolling load performance by the groove having the configuration according to the present embodiment. 1 is a graph showing the measurement results of an example.

The following describes an embodiment of the present invention with reference to the drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and duplicated description is omitted. In the following embodiment, an example is described in which a hat-shaped steel sheet pile is manufactured by the steel sheet pile manufacturing method according to the present invention. In this embodiment, a slab or the like is rolled into a rough material, a first intermediate material, and a second intermediate material according to the rolling process of the steel sheet pile, and these are collectively referred to as rolled material A.

(Rolling equipment configuration)
FIG. 1 is a schematic diagram of a rolling facility 1 for carrying out a manufacturing method of a steel sheet pile according to an embodiment of the present invention. As shown in FIG. 1, the rolling facility 1 is configured by arranging a roughing mill (BD mill) 10, a first intermediate rolling mill 20, a second intermediate rolling mill 30, and a finishing rolling mill 40 in order from the upstream along a rolling line L. The second intermediate rolling mill 30 is composed of a universal mill 32 and an edge mill 34 arranged in series and close to each other. In addition, this rolling facility 1 has the same configuration as the facility generally used when rolling H-shaped steel, and it is possible to divert the rolling facility of H-shaped steel in a normal rolling factory to the manufacture of steel sheet piles.

In the rolling equipment 1 shown in FIG. 1, the material to be rolled, such as a slab, discharged from a heating furnace (not shown) is first multi-pass rolled in the roughing mill 10 (rolling the material to be rolled back and forth multiple times in the rolling mill) to form a rough material. The rough material is then rolled into a first intermediate material in the first intermediate rolling mill 20. The first intermediate material is then rolled into a second intermediate material in the second intermediate rolling mill 30. Here, the rolling in the first intermediate rolling mill 20 and the second intermediate rolling mill 30 is also performed by multi-pass rolling. The second intermediate material is then formed into the final product shape in the finishing rolling mill 40, and a steel sheet pile is manufactured.

(Gap configuration of intermediate rolling mill)
The configuration of the second intermediate rolling mill 30 and the rolling of the first intermediate material to the second intermediate material in the second intermediate rolling mill 30 will be described in detail below. Fig. 2 is a schematic diagram of the groove cross-sectional shape (a) of the universal mill 32 constituting the second intermediate rolling mill 30 and the groove cross-sectional shape (b) of the edge mill 34. Here, in Fig. 2 and its description, the material A to be rolled is composed of a web corresponding part 3 corresponding to the web of the hat-shaped steel sheet pile product, flange corresponding parts 4 and 5 connected to both ends of the web corresponding part 3, arm corresponding parts 6 and 7 formed at the respective tips of the flange corresponding parts 4 and 5, and joint corresponding parts 8 and 9 formed at the tips of the arm corresponding parts 6 and 7, and the material A to be rolled is illustrated by a dashed line in the figure.

As shown in FIG. 2(a), the groove provided in the universal mill 32 is composed of an upper grooved roll 60 as a protruding roll and a lower grooved roll 61 as a grooved roll. In this groove, the material A to be rolled is pressed down, and the joint shape is roughly formed. The entire material A to be rolled is pressed down so that the cross-sectional shape becomes an approximately hat-shaped cross-sectional shape that forms the joint portion.

As shown in FIG. 2(b), the groove provided in the edge mill 34 is composed of an upper grooved roll 70 as a protruding roll and a lower grooved roll 71 as a groove roll. In this groove, rolling is performed to determine the shape of the joint corresponding parts 8, 9 (joint shape) and the joint plate thickness, and this largely determines the shape of the final product including the joint shape.

As shown in FIG. 2, the cross-sectional shape of the universal mill 32 and the cross-sectional shape of the edge mill 34 are almost identical except for the shape of the joint portion. In the cross-sectional shape of the universal mill 32, the groove of the portion corresponding to the joint has an open tip (free-spreading shape), and the material to be rolled (first intermediate material) is reduced in its entire cross-sectional thickness in the universal mill 32. In addition, in the cross-sectional shape of the edge mill 34, the groove of the portion corresponding to the joint has a shape in which the tip is constrained, and the joint-corresponding portions 8, 9 of the material to be rolled (first intermediate material) are reduced and formed.

The rolling of the first intermediate material in the second intermediate rolling mill 30 is performed by multi-pass rolling, in which the first intermediate material is rolled by repeatedly going back and forth multiple times so as to pass through both the universal mill 32 and the edge mill 34. In this multi-pass rolling, the edge mill 34 reduces and forms the joint corresponding parts 8, 9 of the material to be rolled (first intermediate material) only in the latter passes or at the end.

(Constraint state of rolled material in edge mill)
As described above, in the manufacturing method of the steel sheet pile according to the present embodiment, in the multi-pass rolling of the rolled material (first intermediate material), only the joint corresponding parts 8, 9 are reduced and formed in the edge mill 34 at the end of the multi-pass rolling. Here, in the edge mill 34, only the joint corresponding parts 8, 9 are reduced and formed, and the main body part (for example, the web corresponding part 3 and the flange corresponding parts 4, 5) of the rolled material A (first intermediate material) is not reduced in principle. Therefore, if the entire cross section of the joint corresponding parts 8, 9 is reduced, a shape defect called so-called bite-out occurs at the tip part. That is, in the reduction and forming of the joint corresponding parts 8, 9 of the rolled material in the edge mill 34, it is necessary to reduce and form the joint corresponding parts 8, 9 while restraining the suitable parts of the joint corresponding parts 8, 9. Therefore, as a result of intensive research, the inventors discovered that the above problem can be solved by adopting a groove design that optimizes the restraint state of the rolled material A when rolling and forming the joint corresponding portions 8, 9 of the rolled material A in the edge mill 34.

Here, the restraint state of the rolled material A in the edge mill 34 in this embodiment will be described with reference to the drawings. Figure 3 is a schematic overall cross-sectional view of the groove showing the restraint state of the rolled material A in the edge mill 34. Also, Figures 4 to 6 are explanatory diagrams showing the restraint state of the rolled material A in the edge mill 34, and are schematic enlarged views of parts A to C shown by dashed lines in Figure 3, Figure 4 is a schematic diagram of the web corresponding part 3, and Figures 5 and 6 are schematic diagrams of the left and right joint corresponding parts 8 and 9, respectively. Note that in Figures 3 to 6, the rolled material A and the groove shape are shown superimposed, with the solid line indicating the groove and the dashed line indicating the rolled material A.

As shown in FIG. 3, the rolled material A in the edge mill 34 is reduced and formed in a state where it is partially unconstrained. Specifically, the web corresponding portion 3 and the left and right joint corresponding portions 8 and 9 are unconstrained except for some parts. Meanwhile, the flange corresponding portions 4 and 5 are in contact with the rolls on both the top and bottom surfaces and are in a constrained state, except for the corner portions described below.

For example, as shown in FIG. 4, in the web corresponding portion 3, reduction and forming are performed with a gap (escape) between the roll and the rolled material A, except for the corner portions (R portions) 80, 81 that are the connection portions with the left and right flange corresponding portions 4, 5. The gap related to this web corresponding portion 3 may be formed mainly between the rolled material A and the upper perforated roll 70, for example, as shown in the figure.

As shown in Figures 4 to 6, the flange corresponding parts 4 and 5 have a roll gap set equal to the thickness of the flange corresponding parts 4 and 5 finished by the front-stage groove. In other words, the flange corresponding parts 4 and 5 are not actively reduced in thickness, but are restrained so that the steel material (rolled material A) does not shift during rolling. However, during operation, the thickness of the steel material may vary, so it is desirable to set the conditions for light reduction, and tests have confirmed that such setting conditions make it possible to restrain the steel material. In other words, the flange corresponding parts 4 and 5 are reduced and formed in a state where the corner parts 80 and 81, the corner parts (R parts) 85 and 86 that are the connection parts with the arm corresponding parts 6 and 7, and the flange corresponding parts 4 and 5 are all restrained.

As shown in Figures 5 and 6, in the arm corresponding parts 6, 7, in addition to the corner parts 85, 86, except for the corner parts (R parts) 90, 91 which are the connection parts with the joint corresponding parts 8, 9, a gap (escape) is provided between the roll and the material A to be rolled, and rolling and forming are performed in this state. The gaps related to these arm corresponding parts 6, 7 may be formed, for example, as shown in the figure, such that one (arm corresponding part 6) is formed mainly between the material A to be rolled and the upper perforated roll 70, and the other (arm corresponding part 7) is formed mainly between the material A to be rolled and the lower perforated roll 71.

In this way, in the edge mill 34, the rolled material A is restrained only at each connection part (corner part) of the web corresponding part 3, the flange corresponding parts 4 and 5, and the arm corresponding parts 6 and 7, and the other parts are left unrestrained with gaps provided, and as a rule, no reduction is performed.

On the other hand, as shown in Figures 5 and 6, in the joint corresponding parts 8 and 9, the tip parts 8a and 9a and the web side end parts 8b and 9b are in a constrained state, and only the joint bottom parts 8c and 9c are unconstrained. In the examples described later, the shape of the joint corresponding parts 8 and 9 when pressed down and formed with the joint bottom parts 8c and 9c in a constrained state is compared with the shape of the joint corresponding parts 8 and 9 when pressed down and formed with the joint bottom parts 8c and 9c in an unconstrained state, to clarify the above findings.

(Action and Effect)
In the edge mill 34, the main body portion of the rolled material A (for example, the web corresponding portion 3) is not reduced, and in principle is not restrained. However, if it is completely unrestrained, a problem occurs in that the rolled material A is displaced from the groove. Therefore, as described in this embodiment, in the reduction and forming of the joint corresponding portions 8, 9 of the rolled material A in the edge mill 34, the flange corresponding portions 4, 5 are lightly reduced, and it was confirmed by verification that the above problem can be solved by reducing and forming the joint corresponding portions 8, 9 of the rolled material A in the edge mill 34 while restraining various connecting portions such as the connecting portions with the web corresponding portion 3 (the above corner portions 80, 81).

Figure 7 is an explanatory diagram of the rolling load performance with a conventional groove of a completely non-constrained type, and Figure 8 is an explanatory diagram of the rolling load performance with a groove having a configuration according to this embodiment (hereinafter referred to as the new groove). Here, in Figures 7 and 8, (a) shows the groove shape and the position of the gap (relief) provided therein, and (b) shows a graph of the rolling load performance in the longitudinal direction. In Figures 7(a) and 8(a), the areas marked with thick lines along the groove shape are the areas where relief is provided.

As shown in Figure 7(b), in the conventional groove, the rolling load increases at the biting end (dashed line in the figure), and the rolling material A is bitten at the biting end with a shift to the left and right, resulting in a large rolling load. In the conventional groove shown in Figure 7(a), in order to reduce the rolling load due to thickness reduction, gaps (relief) are provided in the groove in all parts corresponding to the arm, flange, and web. As a result, the rolling material A is easily bitten at a shift to the left and right, resulting in an increase in the rolling load at the biting end as shown in Figure 7(b).

On the other hand, as shown in Figure 8 (b), in the new hole type, there is no gap (relief) in the flange corresponding portion, so that misalignment of the bite is unlikely to occur. Therefore, there is no increase in the rolling load at the bite end (dashed line in the figure). This is because in the conventional hole type, the arm corresponding portion and the web corresponding portion, which are thicker than the flange corresponding portion, are misaligned and bite into the roll facing the flange corresponding portion, resulting in an increase in the rolling load, whereas in the new hole type, there is no gap (relief) in the flange corresponding portion, so that the arm corresponding portion and the web corresponding portion are unlikely to misalign with the roll facing the flange corresponding portion, and the increase in the rolling load due to misalignment of the bite is suppressed.

When using rolling equipment for H-shaped steel, conventionally, the steel sheet pile, particularly the joint corresponding parts 8 and 9, were manufactured by performing multi-pass rolling in two parallel grooves in the second intermediate rolling mill 30. However, by applying the manufacturing method of the steel sheet pile according to the embodiment of the present invention, the universal mill 32 and the edge mill 34 arranged in series are used to mainly roll the main part of the rolled material (for example, the web corresponding part 3 and the flange corresponding parts 4 and 5) in the universal mill 32, and the joint corresponding parts 8 and 9 are rolled and formed in the edge mill 34. This reduces the load on the rolls in the universal mill 32 and the edge mill 34, and makes it possible to efficiently roll the rolled material and roll and form the joint corresponding parts 8 and 9, such as improving the elongation length. In other words, the load on the edge mill 34 is suppressed, and even an edge mill with a small rolling load can effectively roll and form the joint corresponding parts 8 and 9.

In addition, conventionally, in the second intermediate rolling mill 30, rolling was performed using two grooves arranged in parallel on one caliber, which resulted in significant roll deflection and caused the rolled material A to bend. However, in the steel sheet pile manufacturing method of this embodiment, rolling is performed using one groove each in the universal mill 32 and edge mill 34, which are separate rolling mills, making it possible to keep roll deflection low, suppress the occurrence of bending of the rolled material A, and improve yield.

Furthermore, conventionally, in the second intermediate rolling mill 30, rolling was performed by shifting (moving the rolled material widthwise) the rolled material A between two parallel-arranged grooves. However, in the manufacturing method of the steel sheet pile according to the present embodiment, multi-pass rolling is performed by only moving the rolled material A in the longitudinal direction between the serially-arranged universal mill 32 and edge mill 34. This eliminates the time required to shift the rolled material A, and makes it possible to prevent the occurrence of defective shapes and defective ends (defective parts known as crops) caused by the rolled material A not being accurately fitted into the grooves after shifting.

Although an example of an embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can conceive of various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these naturally fall within the technical scope of the present invention. For example, in the above embodiment, a hat-shaped steel sheet pile was used as an example to explain the manufacturing method of the steel sheet pile according to the present invention, but the scope of application of the present invention is not limited to this, and it can be applied to any steel sheet pile that has a flange portion, a web portion, and a joint portion, and can also be applied to Z-shaped steel sheet piles, which have a completely asymmetric cross section, and U-shaped steel sheet piles, which have a left-right asymmetric cross section, etc.

(Example)
As an example of the present invention, the maximum value (MAX value) and average value (MID value) of the rolling load (rolling reaction force) were measured when the joint bottom and various corners were rolled down and formed in an unconstrained state in an edge mill as described in the above embodiment. Figure 9 is a graph showing the measurement results.

As shown in Figure 9, when the present invention is applied, the rolling load of the edger mill is about 100t for both the rolling load at the time of biting and the rolling load in the steady state. In contrast, for example, the equipment specifications for edger mills in general shaped steel equipment state that the rolling load is a maximum of 400t (i.e., the load capacity of the rolling machine = 400t), but the results of this embodiment are significantly lower than this, and it can be seen that the load on the edger mill is suppressed.

On the other hand, if the present invention is not applied and the full cross-section thickness reduction of the rolled material is performed using an edge mill, it is common technical knowledge that the rolling load will increase significantly, and it is known that a rolling load of approximately 1,000 tons will be generated. In other words, if the full cross-section thickness reduction is performed, it will exceed the maximum rolling load (load capacity) of the edge mill equipment, which is 400 tons, and it is therefore impossible to carry out.

The present invention can be applied to a manufacturing method for steel sheet piles in a steel section factory having a universal mill and an edger mill, in which the joints of the steel sheet piles are formed using an edger mill.

Reference Signs List 1...Rolling equipment 3...Web corresponding part 4, 5...Flange corresponding part 6, 7...Arm corresponding part 8, 9...Joint corresponding part 10...Roughing mill 20...First intermediate rolling mill 30...Second intermediate rolling mill 32...Universal mill 34...Edger mill 40...Finishing rolling mill 60...Upper hole type roll (of universal mill) 61...Lower hole type roll (of universal mill) 70...Upper hole type roll (of edger mill) 71...Lower hole type roll (of edger mill) 80, 81, 85, 86, 90, 91...Corner part L...Rolling line A...Rolled material

Claims (3)

A manufacturing method for a steel sheet pile having a flange portion, a web portion, and a joint portion,
A rolling line including a universal mill and an edge mill disposed adjacent to the universal mill in series along the rolling direction,
The universal mill reduces the thickness of the rolled material in its entire cross section,
The edge mill reduces and forms the joint corresponding portion of the rolled material,
In the pressing and forming of the joint corresponding portion in the edge mill,
In the web-corresponding portion of the rolled material, a gap is provided between the roll and the rolled material except for the connection portion with the flange-corresponding portion of the rolled material,
In the flange corresponding portion of the rolled material, the rolled material is restrained including the connection portion with the web corresponding portion and the connection portion with the arm corresponding portion of the rolled material,
A manufacturing method for a steel sheet pile, in which a gap is provided between the roll and the rolled material in the arm corresponding portion of the rolled material, except for the connection portion with the flange corresponding portion and the connection portion with the joint corresponding portion. The method for manufacturing a steel sheet pile according to claim 1, wherein the rolling and forming of the joint-corresponding portion of the rolled material is performed in a non-constrained state at the bottom of the joint-corresponding portion. The entire cross-sectional thickness reduction of the rolled material and the reduction and shaping of the joint corresponding portion of the rolled material are performed by multi-pass rolling in which the universal mill and the edge mill are continuously reciprocated multiple times;
The method for manufacturing a steel sheet pile according to claim 1 or 2, wherein the reduction and shaping of the joint corresponding portion of the rolled material by the edge mill is performed only at the final time of the multi-pass rolling.

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