PRODUCTION METHOD AND PRODUCTION FACILITY FOR STEEL SHEET PILE WITH FLANGES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-073578, filed in Japan on Apr. 3, 2017, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a production method and a production facility for a steel sheet pile with flanges such as a hat-shaped steel sheet pile, a U-shaped steel sheet pile or the like.

BACKGROUND ART

Conventionally, the production of a steel sheet pile having joints at both ends of a hat shape or the like is performed by a caliber rolling method. Known as a general process of the caliber rolling method is, first, heating a rectangular material to a predetermined temperature in a heating furnace and sequentially rolling the rectangular material by a rough rolling mill, an intermediate rolling mill, and a finish rolling mill including calibers. As the caliber rolling method, a technique of arranging a plurality of calibers at rolls in rough rolling, intermediate rolling, and finish rolling and performing rolling in one to two passes in each of the calibers to produce a hat-shaped steel sheet pile is disclosed, for example, in Patent Document 1.

Besides, a technique of constituting a caliber to balance web and flange elongations in the production of a U-shaped steel sheet pile and performing rolling by reciprocating a material to be rolled a plurality of times in the same caliber is disclosed, for example, in Patent Document 2. Besides, a technique for the purpose of reducing the placing resistance in constructing a steel sheet pile is disclosed and a configuration in which a gradually inclined part is provided at a flange part is proposed, for example, in Patent Document 3.

Further, a production technique for a Z-shaped steel sheet pile including a step of shaping a pre-form having two flange/web transition sections parallel to a rolling plane and a middle section inclined with respect to the rolling plane near a neutral line is disclosed, for example, in Patent Document 4.

As described above, the caliber rolling method and the technique of performing rolling by reciprocating the material to be rolled a plurality of times in the same caliber (so-called one-caliber multiple-pass rolling) are conventionally invented as the production method for a steel sheet pile.

PRIOR ART DOCUMENT

[Patent Document]

Patent Document 1: Japanese Laid-open Patent Publication No. 2006-88176
Patent Document 2: Japanese Laid-open Patent Publication No. S60-44101
Patent Document 3: Japanese Laid-open Patent Publication No.

2004-76580

Patent Document 4: Japanese Laid-open Patent Publication No. H8-224634

DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention

However, in the above conventional caliber rolling method exemplified in the above Patent Document 1, the rolling in one to two passes in one caliber is performed at the rough rolling, the intermediate rolling step to the finish rolling step with the flange set to a linear state at substantially the same angle as that of the product but, in particular, in the case where the flange width is large and the sheet thickness is small, when the reverse rolling is performed, the elongation at each part in the cross section of the material to be rolled cannot be balanced, causing a flange wave in some cases. Note that the “caliber” in the description is a gap formed between upper and lower caliber rolls and indicates a portion through which the material to be rolled is passed and rolled. Hereinafter, as long as the grooves on the rolls forming the caliber are the same if the distance between the upper and lower caliber rolls varies, the caliber will be explained while being called “the same caliber”. Further, the “reverse rolling” in the description means a step of repeatedly performing rolling by reciprocating the material to be rolled in a plurality of passe while gradually narrowing the roll gap in the same caliber constituted of the upper and lower caliber rolls.

Besides, in the technique disclosed in the above Patent Document 2, in the case of performing rolling that takes large elongation, in particular, for a large-sized steel sheet pile having a large flange width and a small flange thickness as compared with the conventional one, like a hat-shaped steel sheet pile, a defective shape such as a flange wave or the like occurs even if balancing the elongations described in the above Patent Document 2, so that the stable rolling and shaping is difficult and a product defective shape possibly occurs. Further, the balancing condition appropriate for suppressing the occurrence of the defective shape such as a flange wave or the like cannot be realized in some cases in the constraint of the rolling mill. In recent years, in fact, a steel sheet pile in a large cross section having a large height and a small sheet thickness is demanded from the viewpoint of economy and construction property, and a further improvement of technique is required in the production of the large-sized steel sheet pile.

Besides, regarding the technique disclosed in the above Patent Document 3, it is stated that a gradually inclined part is provided at a part (at one or more places of a corner part formed by an end flange part and a web part and a middle part of a web part) of a web part (defined as a flange part in the present invention) to reduce the placing resistance and improve the construction property, but the defective shape such as a flange wave or the like in the production process is not mentioned at all. A further improvement of technique regarding realization of the suppression of the defective shape and the realization of stable rolling and shaping and so on in the production of the large-sized steel sheet pile is demanded.

Besides, the technique disclosed in the above Patent Document 4 is considered to be a technique of performing one-caliber one-pass rolling, and there is no description of performing so-called reverse rolling of performing a plurality of passes while gradually narrowing the gap between the upper and lower rolls in the same caliber. This is considered to be because if the reverse rolling is performed in the same caliber in the technique described in Patent Document 4, the elongation becomes nonuniform at each part in the cross section, metal flow occurs to change the filling stage at the joint part and the elongation of a flange/web transition section becomes geometrically larger than the elongation at a middle section, resulting in that twist becomes more likely to occur. In the case of performing one-caliber one-pass rolling, the caliber shape can be made into an optimum shape during one-pass rolling, so that the problem such as a defective shape of the material to be rolled caused by the caliber shape cannot arise. In short, in the above Patent Document 4, the occurrence of the flange wave possibly occurring during the reverse rolling is not mentioned at all and the suppress of the flange wave is not mentioned at all as a matter of course.

Hence, in consideration of the above circumstances, an object of the present invention is to provide a production technique for a steel sheet pile with flanges, capable of suppressing the occurrence of a defective shape such as a flange wave or the like by reverse rolling so as to improve the product dimension accuracy and stability of rolling.

Means for Solving the Problems

To achieve the above object, according to the present invention, there is provided a production method for forming a steel sheet pile with flanges from a material to be rolled by caliber roll rolling, the production method including a step of performing reverse rolling on the material to be rolled by a same caliber, wherein: the step of performing reverse rolling includes a step of forming first flange parts across a neutral line and second and third flange parts arranged on both sides of the first flange parts; the caliber includes first flange facing portions for forming the first flange parts, second flange facing portions for forming the second flange parts, and third flange facing portions for forming the third flange parts; and an inclination angle of the first flange facing portion with respect to a horizontal plane is larger than inclination angles of the second and third flange facing portions.

It is adoptable that the step of performing reverse rolling includes a step of forming a web corresponding part and arm corresponding parts; the caliber includes a web facing portion for forming the web corresponding part and arm facing portions for forming the arm corresponding parts; the caliber includes web-side flange facing portion groups each including at least one of the second flange facing portions and arm-side flange facing portion groups each including at least one of the third flange facing portions; and with respect to a straight line linking a boundary part between the web-side flange facing portion group and the web facing portion and a boundary part between the arm-side flange facing portion group and the arm facing portion, the second flange facing portion is in a protruding shape in a flange outside direction, and the third flange facing portion is in a protruding shape in a flange inside direction.

It is adoptable that rolling in which a flange elongation κf1 at the first flange part is smaller than flange elongations λf2, λf3 at the second flange part and the third flange part is performed in the caliber.

It is adoptable that the step of forming the first flange parts, the second flange parts, and the third flange parts is an intermediate rolling step.

It is adoptable that the caliber has a caliber shape opened at both end parts in a width direction.

It is adoptable that the flange corresponding parts in a bent shape formed in the material to be rolled by the step of forming the first flange parts, the second flange parts, and the third flange parts are rolled and shaped into a desired flat shape by rolling in a caliber at a stage subsequent to the step of forming the first flange parts, the second flange parts, and the third flange parts.

It is adoptable that rolling is performed in the caliber so that the flange elongation κf1 at the first flange part becomes a web elongation λw or less.

It is adoptable that the steel sheet pile is a hat-shaped steel sheet pile.

According to the present invention from another viewpoint, there is provided a production facility for forming a steel sheet pile with flanges from a material to be rolled by caliber roll rolling, the production facility including a rolling mill which performs reverse rolling on the material to be rolled by a same caliber, wherein: the rolling mill which performs reverse rolling includes a caliber which forms first flange parts across a neutral line and second and third flange parts arranged on both sides of the first flange parts; the caliber includes first flange facing portions for forming the first flange parts, second flange facing portions for forming the second flange parts, and third flange facing portions for forming the third flange parts; and an inclination angle of the first flange facing portion with respect to a horizontal plane is larger than inclination angles of the second and third flange facing portions.

It is adoptable that the rolling mill which performs reverse rolling includes a caliber which forms a web corresponding part and arm corresponding parts; the caliber includes a web facing portion for forming the web corresponding part and arm facing portions for forming the arm corresponding parts; the caliber includes web-side flange facing portion groups each including at least one of the second flange facing portions and arm-side flange facing portion groups each including at least one of the third flange facing portions; and with respect to a straight line linking a boundary part between the web-side flange facing portion group and the web facing portion and a boundary part between the arm-side flange facing portion group and the arm facing portion, the second flange facing portion is in a protruding shape in a flange outside direction, and the third flange facing portion is in a protruding shape in a flange inside direction.

It is adoptable that a flange elongation λf1 at the first flange part is smaller than flange elongations λf2, λf3 at the second flange part and the third flange part in the caliber.

It is adoptable that the caliber is a caliber provided in an intermediate rolling mill.

It is adoptable that the caliber has a caliber shape opened at both end parts in a width direction.

It is adoptable to further include a subsequent-stage caliber which rolls and shapes the flange corresponding parts in a bent shape formed in the material to be rolled by rolling in the caliber which forms the first flange parts, the second flange parts, and the third flange parts, into a desired flat shape.

It is adoptable that the flange elongation λf1 at the first flange part is a web elongation λw or less in the caliber.

It is adoptable that the steel sheet pile is a hat-shaped steel sheet pile.

Effect of the Invention

According to the present invention, it becomes possible to suppress the occurrence of a defective shape such as a flange wave or the like by reverse rolling so as to improve the product dimension accuracy and stability of rolling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory view of a rolling line.

FIG. 2 is a schematic cross-sectional view illustrating the caliber shape of a first caliber.

FIG. 3 is a schematic cross-sectional view illustrating the caliber shape of a second caliber.

FIG. 4 is a schematic cross-sectional view illustrating the caliber shape of a third caliber.

FIG. 5 is a schematic cross-sectional view illustrating the caliber shape of a fourth caliber.

FIG. 6 is a schematic cross-sectional view illustrating the caliber shape of a fifth caliber.

FIG. 7 is a schematic explanatory view of a caliber in a configuration obtained by modifying the third caliber, and (a) illustrating a schematic entire view and (b) illustrating an enlarged view near a place facing a flange corresponding part.

FIG. 8 is a schematic explanatory view according to a modification example of the present invention.

FIG. 9 is an explanatory view of an example.

FIG. 10 is a schematic explanatory view according to a modification example of the present invention.

FIG. 11 is a schematic explanatory view according to a modification example of the present invention.

FIG. 12 is a schematic explanatory view according to a modification example of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be explained referring to the drawings. Note that, in the description and the drawings, the same codes are given to components having substantially the same functional configurations to omit duplicated explanation. Note that the explanation will be made assuming that a material to be rolled in a substantially hat-shaped steel sheet pile shape is rolled in a posture that the web is located below the flange (so-called U-posture) in the embodiment, and the scope of application of the present invention extends, as a matter of course, to rolling in other postures (for example, an inverted U-posture). Further, the scope of application of the present invention ranges over steel sheet pile products having various flanges in a hat shape, a U-shape and so on, and a steel sheet pile product produced in the embodiment will be explained as a hat-shaped steel sheet pile product.

Besides, a material to be rolled A described below indicates a steel material to be rolled in the case of producing the hat-shaped steel sheet pile product, steel materials to be passed on a rolling line L are generically called the material to be rolled A, and the material to be rolled A in states that it has been subjected to reduction in rolling mills are described separately using different names (A1 to A5 described below) as needed. The material to be rolled A is in a substantial hat shape, and is composed of a substantially horizontal web corresponding part 3, flange corresponding parts 5, 6 connected to both ends of the web corresponding part 3 at a predetermined angle, arm corresponding parts 8, 9 connected to ends of the flange corresponding parts 5, 6 different from the sides thereof connected with the web corresponding part 3, and joint corresponding parts 10, 11 connected to tips of the arm corresponding parts 8, 9. Note that end portions of the joint corresponding parts 10, 11 are called claw parts 14, 15, respectively. Hereinafter, parts constituting the material to be rolled A will be illustrated and explained with the aforementioned respective codes.

Note that, regarding the material to be rolled A, the rolling direction is called a “longitudinal direction” of the material to be rolled, a direction perpendicular to the longitudinal direction and parallel with a rolling roll axis is called a “width direction” of the material to be rolled, and a direction perpendicular to both the longitudinal direction and the width direction is called a “height direction” of the material to be rolled, for explanation in this description. Further, a “thickness reduction” of the material to be rolled indicates a sheet thickness reduction in the sheet thickness direction of the material to be rolled.

First of all, the outline of the rolling line L being a basic configuration as a producing apparatus 1 for producing the hat-shaped steel sheet pile will be explained. FIG. 1 is an explanatory view of the rolling line L for producing the hat-shaped steel sheet pile, rolling mills provided on the rolling line L and so on. In FIG. 1, a rolling forward direction of the rolling line L is a direction indicated with an arrow, the material to be rolled A flows in the direction, rolling is performed in caliber rolling mills (later-explained rough rolling mill, intermediate rolling mill, and finish rolling mill) on the line to shape a product. Note that a plurality of not-illustrated conveyor rolls are installed on the rolling line L, and the material to be rolled A is conveyed on the rolling line L by the conveyor rolls.

As illustrated in FIG. 1, on the rolling line L, a rough rolling mill (BD) 17, a first intermediate rolling mill (R1) 18, a second intermediate rolling mill (R2) 19, and a finish rolling mill (F) 30 are arranged in order from the rolling upstream side.

On the rolling line L illustrated in FIG. 1, the material to be rolled A such as a slab, bloom or the like heated in a not-illustrated heating furnace (located on the upstream of the rolling line L) is rolled in sequence in the rough rolling mill 17 to the finish rolling mill 30 to form into a hat-shaped steel sheet pile being a final product.

Next, the shape of the caliber provided in any of the rough rolling mill 17, the first intermediate rolling mill 18, the second intermediate rolling mill 19, and the finish rolling mill 30 arranged on the rolling line L will be briefly explained in order from the upstream side referring to the drawings. Note that in FIG. 2 to FIG. 6 referred to in the following explanation, the cross section of the material to be rolled A when the reduction in each caliber is completed is illustrated with one-dotted chain line for reference.

FIG. 2 is a schematic cross-sectional view of the caliber shape of the first caliber 49 (hereinafter, also described simply as a caliber 49). As illustrated in FIG. 2, the caliber 49 is composed of an upper caliber roll 45 and a lower caliber roll 48. The caliber 49 composed of the upper caliber roll 45 and the lower caliber roll 48 is provided, for example, in the rough rolling mill 17, and the caliber rolling in the caliber 49 performs the thickness reduction (namely, rough rolling) on the whole material to be rolled A. More specifically, the caliber rolling of making the slab or the like heated to a predetermined temperature in the heating furnace closer to the substantial hat shape is performed to shape a raw blank A1 illustrated with a one-dotted chain line in FIG. 2. Note that the rough rolling at this time may be performed, for example, by reverse rolling in the same caliber 49.

Besides, FIG. 3 is a schematic cross-sectional view of the caliber shape of a second caliber 59 (hereinafter, also described simply as a caliber 59). As illustrated in FIG. 3, the caliber 59 is composed of an upper caliber roll 55 and a lower caliber roll 58. The caliber 59 composed of the upper caliber roll 55 and the lower caliber roll 58 is provided, for example, in the first intermediate rolling mill 18, and the caliber rolling in the caliber 59 performs the thickness reduction (namely, first intermediate rolling) on the whole material to be rolled A. In the caliber 59, reduction of aligning the claw heights of the claw parts 14, 15 to a desired height is also performed concurrently with the thickness reduction, and more specifically, the caliber rolling of making the raw blank A1 carried out of the caliber 49 much closer to the hat shape is performed. Thus, a first intermediate material A2 illustrated with a one-dotted chain line in FIG. 3 is shaped. Note that the rolling here is performed, for example, by reverse rolling in the same caliber 59.

Besides, FIG. 4 is a schematic cross-sectional view illustrating the caliber shape of a third caliber 69 (hereinafter, also described simply as a caliber 69). As illustrated in FIG. 4, the caliber 69 is composed of an upper caliber roll 65 and a lower caliber roll 68. The caliber 69 composed of the upper caliber roll 65 and the lower caliber roll 68 is provided, for example, in the second intermediate rolling mill 19, and the caliber rolling in the caliber 69 performs the thickness reduction (namely, second intermediate rolling) on the whole material to be rolled A. More specifically, the caliber rolling of making the first intermediate material A2 carried out of the caliber 59 much closer to the hat shape is performed, and thereby a second intermediate material A3 illustrated with a one-dotted chain line in FIG. 4 is shaped. This caliber 69 is in a shape having both end portions in the width direction opened, so that the claw parts 14, 15 of the material to be rolled A are in shapes extended in the width direction by the thickness reduction. Note that the rolling here is performed, for example, by reverse rolling in the same caliber 69.

FIG. 5 is a schematic cross-sectional view illustrating the caliber shape of a fourth caliber 79 (hereinafter, also described simply as a caliber 79). As illustrated in FIG. 5, the caliber 79 is composed of an upper caliber roll 75 and a lower caliber roll 78. The caliber 79 composed of the upper caliber roll 75 and the lower caliber roll 78 is provided, for example, in the second intermediate rolling mill 19, and the caliber 79 intensively performs, for example, shaping of the claw parts 14, 15 of material to be rolled A. More specifically, the reduction to perform the forming while aligning the claw heights of the claw parts 14, 15 in the state extended in the third caliber 69 to a desired height is performed to shape a second intermediate material A4. Note that the rolling here may be reduction of the thickness.

Besides, FIG. 6 is a schematic cross-sectional view illustrating the caliber shape of a fifth caliber 89 (hereinafter, also described simply as a caliber 89). As illustrated in FIG. 6, the caliber 89 is composed of an upper caliber roll 85 and a lower caliber roll 88. The caliber 89 composed of the upper caliber roll 85 and the lower caliber roll 88 is provided, for example, in the finish rolling mill 30, and the caliber 89 mainly performs bending forming (namely, finish rolling) of the claw parts 14, 15 on the material to be rolled A. More specifically, the reduction of making the second intermediate material A4 into a finished material A5 in the substantial hat shape (substantially hat-shaped steel sheet pile product shape). Note that, normally, the finish rolling is not performed in reverse rolling but is performed by rolling in only one pass.

Thus, the material to be rolled A is subjected to caliber rolling in each rolling explained referring to FIG. 2 to FIG. 6, and the finished material A5 is finally shaped.

Note that the configurations of the first caliber to the fifth caliber described in the embodiment are examples and the configurations are not limited to the illustrated forms, but, for example, the arrangement order of the calibers, the caliber shape arranged in each rolling mill, and the increased/decreased arrangement of correction calibers for various calibers may be changed as needed according to conditions such as the facility status, product dimensions and so on. Further, depending on the kind of the raw material, it is also conceivable to separately provide a caliber such as a preform caliber used for rough shaping process from the raw material.

According to the study of the present inventors, at an intermediate rolling step by the caliber 59 and the caliber 69 in the above production process, even when the rolling is performed while balancing the elongation between the web corresponding part 3 and the flange corresponding parts 5, 6, the relative sliding speed between the material to be rolled A (specifically, the flange corresponding parts 5, 6) and the roll differs depending on a part because the upper and lower caliber rolls are different in diameters of upper and lower rolls depending on a part as illustrated in FIG. 3 and FIG. 4. At the flange corresponding parts 5, 6, the elongation of the material to be rolled is suppressed by a peripheral speed difference between the upper and lower rolls at a part where the difference between upper and lower roll diameters is large, whereas the elongation is likely to occur at a position corresponding to a pitch line where the diameters of the upper and lower rolls are equal (hereinafter, described a “neutral line”), so that a compressive stress is likely to occur in the longitudinal direction in the flange near the neutral line at a roll bite outlet and, in the case where the compressive stress exceeds a buckling limit, a defective shape so-called flange wave occurs at the flange corresponding parts 5, 6.

In particular, in the production of a large-sized steel sheet pile such as a hat-shaped steel sheet pile having a high ratio of flange width/flange thickness, the elongation of the flange near the neutral line tends to be large relative to the elongation of the web, and the compressive stress in the longitudinal direction acts on the middle parts of the flange corresponding parts 5, 6 from the inside of the roll bite. Further, the buckling limit stress also lowers, resulting in that the flange wave is remarkably likely to occur.

In the case of performing rolling in one pass by the same caliber, designing a caliber in a shape under consideration of the flange elongation and the web elongation according to the relation with the shape of the preceding caliber can suppress the flange wave. However, it has been found that in the case of performing rolling in two or more passes by the same caliber, each elongation of the web corresponding part, the flange corresponding part and the arm corresponding part is prescribed by the shape of the caliber in the rolling in the second and subsequent passes, so that it is impossible to suppress the occurrence of the flange wave in the middle of the reverse rolling even if the shape of the caliber is designed as in the prior art. For example, the result of study has revealed that in the case where the reverse rolling is performed in the calibers 59, 69, the metal gathers at the middle parts (near the neutral line) of the flange corresponding parts 5, 6 every rolling at the flange corresponding parts 5, 6, and a phenomenon of restoration of the flange thickness is likely to occur. If the restoration of the thickness occurs, the flange elongation increases in the next pass and the flange wave undesirably becomes more likely to occur.

Besides, comparing the caliber 59 and the caliber 69, the caliber 69 being a caliber at a subsequent stage rolls the material to be rolled A (particularly, the flange corresponding parts 5, 6) thinner, and therefore is more likely to remarkably cause a defective shape such as the above-described occurrence of the flange wave. Further, if the defective shape occurs, a step closer to the finish rolling is more likely to be directly linked to the product defective shape. In other words, it is important to solve the problems as described above, in particular, in the caliber 69 being a caliber at a subsequent stage from the viewpoint of the product dimension accuracy and the stability of rolling.

In view of the problems, the present inventors have earnestly studied about the shapes of the calibers 59, 69 explained referring to FIG. 3 and FIG. 4, and have arrived at the invention of the caliber shape satisfying predetermined conditions causing no defective shape called the flange wave. Hereinafter, the detailed shape of a caliber 69′ configured to cause no flange wave by further improving the shape of the caliber 69 will be explained referring to the drawings. Note that though the rolling and shaping relating to, in particular, the flange corresponding part 6 of the caliber 69′ will be illustrated and explained as an example in the following, the caliber of the object in the present invention is a caliber for performing thickness reduction on the whole material to be rolled A and is not limited to the calibers 59, 69.

FIG. 7 is a schematic explanatory view of the caliber 69′ in the configuration obtained by modifying the above third caliber 69, and (a) illustrates a schematic entire view and (b) illustrates an enlarged view near a place facing the flange corresponding part 6 (a portion surrounded by a broken line in FIG. 7(a)). Here, FIG. 7(b) illustrates an appearance after rolling in the caliber 69′ and illustrates the rolled material to be rolled A with a one-dotted chain line. Note that in FIG. 7, the same codes are given to components having the same functional configurations as those of the caliber 69 explained referring to FIG. 4 to omit explanation thereof.

In the modified caliber 69′ illustrated in FIG. 7, a facing portion 100 facing the flange corresponding part 6 of the material to be rolled A is different in shape from that of the above caliber 69 and is concretely composed of a plurality of flange facing portions 100a, 100b, 100c different in inclination in order to the side closer to the web. Regarding the flange facing portions 100a, 100b, 100c, the flange facing portion 100b is prescribed and called as a “first flange facing portion”, and flange facing portions 100a, 100c arranged on both sides thereof are prescribed and called a “second flange facing portion” and a “third flange facing portion” respectively in some cases in this description. Further, a part of the flange corresponding part 6 rolled and shaped by the flange facing portion 100b located at the middle is prescribed and called a “first flange part”, and parts of the flange corresponding part 6 arranged on both sides thereof (parts to be rolled and shaped by the flange facing portions 100a, 100c) are prescribed and called a “second flange part” and a “third flange part” respectively in some cases.

Note that as illustrated in FIG. 7(a), a portion 101 facing the flange corresponding part 5 of the material to be rolled A is similarly composed of flange facing portions 101a, 101b, 101c.

Inclination angles of the flange facing portions 100a, 100b, 100c with respect to the horizontal line are θf2, θf1, θf3, respectively, and θf1 is an angle larger than θf2 and θf3. Besides, θf2 and θf3 may be an equal angle. When intervals tf2, tf1, tf3 (called also as roll gaps) between the upper caliber roll 65 and the lower caliber roll 68 in the flange facing portions 100a, 100b, 100c are constant (the flange facing portions 100a, 100b, 100c of the upper caliber roll 65 and the lower caliber roll 68 are parallel), the angles θf2, θf1, θf3 in each of the upper caliber roll 65 and the lower caliber roll 68 are equal. On the other hand, when the angles formed between the flange facing portions 100a, 100b, 100c and the horizontal line are different between the upper caliber roll 65 and the lower caliber roll 68, it is only necessary to regard average values of the angles formed between the flange facing portions of the upper caliber roll 65 and the lower caliber roll 68 and the horizontal line as the angles θf2, θf1, θf3. Further, the inclination angles θf2, θf1, θf3 are substantially the same even when prescribed as angles formed between a center line S in the roll gap between the upper and lower rolls and the horizontal line.

Further, the flange facing portion 100b is constituted at a position across a neutral line O in the height direction, and the flange facing portion 100a is located on the side closer to the web than the flange facing portion 100b, and the flange facing portion 100c is located on the side closer to the arm (joint). In other words, the flange facing portion 100b is located across the neutral line O and the flange facing portions 100a, 100c are located on both sides thereof.

Here, when the elongation per pass is defined by the thickness ratio before rolling to the thickness after rolling (after one pass), the thickness is represented by the roll gap in the sheet thickness direction in the caliber 69′, and a roll gap reduction amount in the vertical direction in one pass during reverse rolling in the caliber 69′ is Δg, the elongations λf1, λf2, λf3 per pass of the flange facing portions 100b, 100a, 100c are expressed by following Expressions (1) to (3).

λf1=tf1/tf1=(tf1+Δg·cos θf1)/tf1 (1)

λf2=tf2/tf2=(tf2+Δg·cos θf2)/tf2 (2)

λB=tf3/tf3=(tf3+Δg·cos θf3)/tf3 (3)

Note that tf1, tf2, tf3 are roll gaps corresponding to the thickness before rolling of the flange corresponding part 6 corresponding to the flange facing portions 100b, 100a, 100c in the caliber 69′. Further, tf1, tf2, tf3 are roll gaps corresponding to the thicknesses of the flange corresponding part 6 rolled by the flange facing portions 100b, 100a, 100c respectively in the caliber 69′.

Specifically, by making θf1 a larger angle than θf2 and θf3 based on the relation among tf1, tf2, tf3, the following Expressions (4), (5) are satisfied in rolling in the caliber 69′.

λf1<λf2 (4)

λf1<λf3 (5)

Here, the above Expressions (1) to (3) express the elongations per pass of rolling, and the relations similar to Expressions (1) to (3) are established also in the case of totaling the elongations in the reverse rolling performed in a plurality passes. Accordingly, by making θf1 a larger angle than θf2 and θf3 in the caliber 69′, the above Expressions (4), (5) are satisfied not only in the case of the elongations per pass but also in the case of totaling the elongations in a plurality passes during the reverse rolling.

The material to be rolled A rolled and shaped in the caliber 69′ becomes a bent shape having a plurality of inclination angles at the flange corresponding part 5, 6. This shape is made into a desired flat flange shape (flange shape of the hat-shaped steel sheet pile product) by the caliber at a stage subsequent to the caliber 69′ provided in the intermediate rolling mill, for example, the fourth caliber 79, the fifth caliber 89 in the finish rolling mill 30 (finish rolling step) or both of the calibers. In the flange flattening, no reverse rolling is performed. Note that after the bending-back of the flange part, streaky traces in the longitudinal direction are found in the boundary portion of the bent part due to the difference in adherence state of scale with respect to other portions or the like, but the traces do not reduce the strength or the like of the flange part and do not affect the quality as the steel sheet pile.

According to the caliber configuration as illustrated in FIG. 7, making the angle On large decreases the flange elongation near the neutral line O where the compressive stress is likely to occur relative to the caliber 69 having the linear flange facing portion as illustrated in FIG. 4 and decreases the flange elongation near the neutral line O relative to the flange elongation at a position separated from the neutral line O to thereby realize the effect of suppressing the occurrence of the flange wave. On the other hand, making the angles θf2 and θf3 small suppresses the increase in flange height to thereby maintain the elongation of the cross section of the flange corresponding part 6. For example, it is only necessary to make the line length of the center line S corresponding to the flange facing portions (100a, 100b, 100c) of the caliber 69′ identical to the line length of the center line of the flange facing portions of the caliber 69 and design the angles θf2, θf3 in a manner not to change the position in the horizontal direction of the joint with respect to the angle On decided as a flange wave suppression condition, in consideration of the suppression of variation in dimension when shaping into a desired flat flange shape by rolling by the caliber at a subsequent stage. In other words, if the reverse rolling is performed in the modified caliber 69′, the flange elongation decreases as compared with the caliber 69 illustrated in FIG. 4 in the flange facing portion 100b but the flange elongation increases as compared with the caliber 69 at the flange facing portions 100a, 100c, and therefore the same flange cross section elongation as that in the caliber 69 can be maintained as the whole flange. Note that making the line length of the center line S corresponding to the flange facing portions (100a, 100b, 100c) of the caliber 69′ identical to the line length of the center line of the flange facing portions of the caliber 69 does not mean being complete identical but may be being identical within a range of error (for example, less than ±1% with respect to the line length of the center line of the flange facing portion).

Here, to suppress the flange wave at the flange facing portion 100b (hereinafter, referred to also as a steep inclination part 100b) near the neutral line O, it is preferable to set the angle θf1 so that the relation between the elongation λf1 of the flange at the steep inclination part 100b and a elongation λw of the web corresponding part 3 satisfies the following Expression (6).

λf1<λw (6)

Note that it is preferable to set λf1/λw per pass to fall within a range of 0.967≤λf1/λw≤1.000, as a more detailed condition. The basis of the numeral values will be explained in later-described examples.

Since the elongation of the flange is greatly affected by the elongation of the web, the elongation of the flange corresponding part near the neutral line O is expressed by the relation with the elongation of the web also in the technique of the present invention. In the case of the hat-shaped steel sheet pile, the elongation of the arm corresponding parts 8, 9 and the elongation of the web corresponding parts 5, 6 are considered to be substantially equal, and since the U-shaped steel sheet pile has no arm corresponding part, the elongation of the flange corresponding part near the neutral line O can be substantially expressed by the relation with the web elongation. The elongation λw of the web in one pass during reverse rolling is expressed by the following Expression (7).

λw=tw′/tw=(tw+Δg·cos θw)/tw (7)

Here, tw′ is the roll gap corresponding to the thickness of the web corresponding part 3 before rolling in the caliber 69′. Besides, tw is the roll gap corresponding to the thickness of the web corresponding part 3 rolled in the caliber 69′. Besides, θw is the inclination angle of the roll gap corresponding to the web corresponding part 3 with respect to the horizontal line.

Further, in the case of the hat-shaped steel sheet pile having a constant thickness in the flange width direction, the caliber shape is designed so that each thickness of the flange facing portions 100a, 100b, 100c is constant in the final pass except the error accompanying roll abrasion or the like in the caliber 69′ directly before the finish rolling, but the inclination angle θf1 of the flange facing portion 100b is different from the inclination angles θf2, θf3 of the flange facing portions 100a, 100c, and therefore each thickness is not constant in midway passes in the caliber 69′. For this reason, the inclination angle and the width of each flange facing portion may be decided in consideration of the elongation ratios λf1/λw, λf2/λw, λf3/λw in a pass where the flange wave is most likely to occur from the relation between the thickness and elongation of each flange facing portion and the elongation of the web corresponding part.

As explained above, making the inclination angle θf1 of the steep inclination part 100b large makes it possible to decrease the flange elongation near the neutral line O and reduce the compressive stress occurring at this portion.

Making the caliber shape of the caliber 69′ provided in the second intermediate rolling mill 19 in the shape having the plurality of flange facing portions 100a, 100b, 100c different in inclination as explained above referring to FIG. 7 and setting the inclination angles of the flange facing portions 100a, 100b, 100c to preferable conditions as expressed in the above Expressions (1) to (6) make it possible to reduce the compressive stress occurring near the neutral line O of the flange corresponding part 6 in the rolling and shaping in the caliber 69′ and suppress the occurrence of the flange wave. Furthermore, it is also possible to reduce the restoration of the flange thickness occurring due to gathering of the metal near the neutral line of the flange corresponding part 6 in the reverse rolling to further suppress the occurrence of the flange wave.

On the other hand, the elongation of the flange occurring at the flange facing portions 100a and 100c increases relative to the elongation of the flange occurring near the neutral line O (namely, the elongation of the flange at the flange facing portion 100b) and the compressive stress occurring there also increases, but the compressive stress does not become excessive since metal flow to the web corresponding part 3 and the arm corresponding part 9 is likely to occur in addition to separation from the neutral line O. Further, parts, corresponding to the flange facing portions 100a and 100c, in the flange corresponding part 6 are connected to the web corresponding part 3 and the arm corresponding part 9 and unlikely to cause buckling, so that the flange wave is unlikely to occur at the parts.

As described above, making the caliber shape of the caliber 69′ in the shape having the plurality of flange facing portions 100a, 100b, 100c different in inclination angle makes it possible to suppress the flange wave occurring near the neutral line O of the flange corresponding parts 5, 6 of the material to be rolled A as compared with the rolling and shaping in the conventional caliber shape (caliber 69) as illustrated in FIG. 4, thereby realizing the improvement of the product dimension accuracy and the stability of rolling. Depending on the product shape, the elongation of the flange corresponding parts 5, 6 is larger than the elongation of the web corresponding part 3 in the conventional caliber shape (caliber 69) as illustrated in FIG. 4, so that the balance cannot be maintained any longer and the flange wave cannot be suppressed in some cases. In this case, not changing the inclination angle of the whole flange but making the inclination angle θf1 of the steep inclination part 100b larger than the flange inclination angle of the conventional caliber shape as illustrated in FIG. 7 and larger than the flange facing portions 100a and 100c makes it possible to suppress the increase in height of the material to be rolled A during the rolling and shaping and effectively suppress the flange wave.

One example of the embodiment of the present invention has been explained above, but the present invention is not limited to the illustrated embodiment. It should be understood that various changes and modifications are readily apparent to those skilled in the art within the scope of the spirit as set forth in claims, and those should also be covered by the technical scope of the present invention.

For example, the technique of the present invention is applied in the above embodiment, and the explanation has been made using the third caliber 69 as the object to be modified in caliber shape and especially the rolling and shaping of the flange corresponding part 6 of the material to be rolled A has been explained referring to FIG. 7, but the application range of the present invention is not limited to this. More specifically, the technique of the present invention is obviously applicable to both of the flange corresponding parts 5, 6 in the rolling and shaping in the third caliber 69 and also to the rolling and shaping in the second caliber 59. More specifically, the same modification can be applied also to the caliber 59 explained referring to FIG. 3 to suppress, for example, the flange wave occurring in the first intermediate rolling. Further, as a matter of course, the technique of the present invention may be applied to the caliber shapes of both of the second caliber 59 and the third caliber 69. Alternatively, regarding the second caliber 59 and the third caliber 69 for mainly reducing the thickness, the same modification may be applied also to the case where the second caliber 59 is made into a caliber shape having both end portions in the width direction opened and the third caliber 69 is made into a caliber shape for simultaneously performing the shaping of the claw height. Furthermore, the technique of the present invention may be applied to the first caliber for performing the rough rolling.

Further, though the caliber shape of the caliber 69′ is explained as a shape having the plurality of flange facing portions 100a, 100b, 100c different in inclination angle in the above embodiment, the important point of the technique of the present invention is to make the inclination angle θf1 of the flange facing portion 100b near the neutral line O larger than those of the other flange facing portions in the caliber for performing the intermediate rolling so as to reduce the compressive stress acting on the material to be rolled A near the neutral line O. From the viewpoint, in the case of constituting the caliber of the intermediate rolling mill in a shape having the plurality of flange facing portions different in inclination angle in the technique of the present invention, it is not always to provide the three flange facing portions as illustrated in FIG. 7, but any number of flange facing portions different in inclination angle may be provided as long as the inclination angle θf1 of the flange facing portion 100b near the neutral line O is larger than those of the other flange facing portions. In short, for example as illustrated in FIG. 10, the caliber for performing the intermediate rolling may be configured to have four or more flange facing portions different in inclination angle.

Further, the caliber part facing the flange corresponding part 5, 6 of the material to be rolled A (namely, the flange facing portion 100) may be, with respect to a straight line linking the boundary part on the arm side (of the material to be rolled) and the boundary part on the web side (of the material to be rolled), in a protruding shape in a flange inside direction on the side closer to the arm than the flange facing portion near the neutral line O and in a protruding shape in a flange outside direction on the side closer to the web than the flange facing portion near the neutral line O.

Specifically, regarding the shape of the flange facing portion 100 provided with the steep inclination part 100b explained in the above embodiment, the shape of each of the flange facing portions 100a to 100c does not always need to be formed in the linear shape but, for example, part or all of the flange facing portions 100a to 100c may be formed by a curved line as long as the inclination angles of the flange facing portions 100a, 100b, 100c are made under the preferable conditions as expressed in the above Expressions (4) to (6). In this case, the steep inclination part 100b is defined as a range sandwiched between an intersection with the flange facing portion 100a and an intersection with the flange facing portion 100c, and the steep inclination part 100b is configured to cross the neutral line O.

FIG. 8 is a schematic explanatory view according to a modification example of the present invention and is a schematic enlarged view illustrating an example of the vicinity of a place facing the flange corresponding part 6. As illustrated in FIG. 8, in this modification example, the flange facing portions 100a, 100c are formed in a curved shape. The step of performing the reverse rolling, including other embodiments, preferably includes a step of forming the web corresponding part 3 connected to the flange part including at least one second flange part (referred to also as a web-side flange part) and the arm corresponding part 9 connected to the flange part including at least one third flange part (referred to also as an arm-side flange part). In this case, the caliber according to the present invention preferably includes a web facing portion 100d for forming the web corresponding part 3 and an arm facing portion 100e for forming the arm corresponding part 9. Here, the caliber preferably includes a web-side flange facing portion group including at least one flange facing portion 100a (second flange facing portion) and an arm-side flange facing portion group including at least one flange facing portion 100c (third flange facing portion). Here, the boundary between the web-side flange facing portion group and the web facing portion 100d is assumed to be Pa, and the boundary between the arm-side flange facing portion group and the arm facing portion 100e is assumed to be Pc. In the example illustrated in FIG. 8, with respect to a straight line Q linking the boundary part Pc on the arm side (the boundary between the arm facing portion 100e facing the arm corresponding part 9 and the flange facing portion 100c) and the boundary part Pa on the web side (the boundary between the web facing portion 100d facing the web corresponding part 3 and the flange facing portion 100a in the caliber 65), the flange facing portion 100a is in a curved shape to be a protruding shape in a flange outside direction, and the flange facing portion 100c is in a curved shape to be a protruding shape in a flange inside direction. Further, the steep inclination part 100b is illustrated as a linear shape in this modification example, but the steep inclination part 100b may be in a curved shape.

In the case where the flange facing portions 100a, 100c as illustrated in FIG. 8 are in a curved shape, the inclination angles θf2, θf3 of the flange facing portions 100a, 100c only need to be decided by the inclination angles of the tangents (Qa, Qc in FIG. 8) at the middle part in the height direction of the flange facing portions 100a, 100c with respect to the horizontal line. In the case where the steep inclination part 100b is in a curved shape, the inclination angle only needs to be decided based on the tangent where the angle becomes maximum. The straight line Q and the tangents Qa, Qc are explained using the lower caliber roll 68 in FIG. 8, and those only need to be similarly decided also in the upper caliber roll 65. Then, in the case where the angles formed between the flange facing portions 100a, 100b, 100c and the horizontal line are different between the upper caliber roll 65 and the lower caliber roll 68, θf2, θf2, θf3 only need to be set to average values of the angles formed between the flange facing portions of the upper caliber roll 65 and the lower caliber roll 68 and the horizontal line. By setting the inclination angles of the flange facing portions 100a to 100c defined as described above to the preferable conditions as expressed in the above Expressions (1) to (6) similarly to the above embodiment, the same operation and effect can be obtained.

More specifically, in the above embodiment, the caliber shape of the modified caliber 69′ is explained as a shape having the plurality of flange facing portions 100a, 100b, 100c different in inclination angle, but the detailed shapes of the portions 100a, 100b, 100c are not mentioned. The shape of the flange corresponding part 5, 6 only needs to be constituted by a plurality of straight lines or curved lines or combination of them, and the shapes of the portions 100a, 100b, 100c can be arbitrarily designed according to the shape of the flange corresponding part 5, 6. If the curved portion is constituted in the flange corresponding part 5, 6, the inclination angle of the curved portion only needs to be defined by the angle of its tangent.

Further, it is extremely effective to apply the technique of the present invention to a product in which the flange corresponding part has a thickness distribution that the thickness changes in a direction along the surface of the flange corresponding part or to a product in a shape having a plurality of bent portions in which the flange corresponding part increases in inclination angle near the neutral line, which falls within the scope of the present invention. In the case where the flange corresponding part has the thickness distribution in a direction along its surface, it is conceivable to relatively decrease the thickness near the neutral line based on the cross-sectional efficiency of the hat-shaped steel sheet pile product. When applying the technique of the present invention to the above case, the elongation of the flange in the flange facing portion 100b is unlikely to become larger than that in the conventional caliber shape because the inclination angle of the flange facing portion 100b is larger than the those of the flange facing portions 100a, 100c, so that the operation and effect equal to or more than those in the above embodiment can be obtained. Further, the rolling states in the bent shapes illustrated in FIG. 7 and FIG. 8 can be applied also to the steel sheet pile product in which the flange is bent to increase in inclination angle near the neutral line in the product shape, which is very useful.

Further, in the caliber shape of the caliber 69′, the boundary parts between the flange facing portions 100a, 100b, 100c may have R. In this case, each boundary between the flange facing portions 100a, 100b, 100c only needs to be an intermediate point of a corner R.

Furthermore, as a result of detailed study by the present inventors, it has been revealed that the flange wave occurring in the conventional caliber 69 has a peak position of the wave height in the cross section of the flange corresponding part included in a range of 10% of a caliber depth D in the height direction from the neutral line O of the caliber 69 illustrated in FIG. 4.

Therefore, in the case where the steep inclination part 100b near the neutral line O is linear, it is desirable that the steep inclination part 100b decreasing the flange elongation includes the range of 10% of the caliber depth D in the height direction upward and downward from the neutral line O as illustrated in FIG. 11. Further, when a center point position Fc of a line segment in the steep inclination part 100b of the center line S coincides with the neutral line O, the operation and effect explained in the above embodiment can be remarkably obtained. Note that the caliber depth D is defined by the height in the vertical direction of the whole flange facing portions (100a, 100b, 100c) of the lower caliber roll forming the caliber, and the upper end position of the caliber depth D is the upper end in the height direction of the boundary between the flange corresponding part and the arm corresponding part, and the lower end position is the lower end in the height direction of the boundary between the flange corresponding part and the web corresponding part as illustrated in FIG. 11.

Further, also in the case where the flange facing portion 100b near the neutral line O is curved or a combination of a plurality of line segments, it is desirable that the steep inclination part 100b (a range of P1 to P2 in the elongation) includes the range of 10% of the caliber depth D in the height direction upward and downward from the neutral line O as illustrated in FIG. 12. In these cases, when a position Fd where the angle with respect to the horizontal line becomes maximum in the line segment corresponding to the steep inclination part 100b of the center line S coincides with the neutral line O, the above-described effect is further remarkable. However, as illustrated in FIG. 12, even if the position Fd deviates in the height direction from the neutral line O as long as it is within the range of 10% of the caliber depth D, the effect of the present invention can be provided. This is because of the same reason as that in the case where the flange facing portion 100b is linear. In this case, it is only necessary to set the inclination angle at the position of the maximum inclination angle to θf2 and set the flange elongation to λ1. Accordingly, these cases are also regarded as being near the neutral line O and fall within the scope of the present invention.

Note that the case where the second flange facing portion and the third flange facing portion are arranged adjacent to the first flange facing portion is explained in the above embodiment and other embodiments, but they do not always need to be adjacently arranged. In other words, the second flange facing portion and the third flange facing portion are smaller in inclination angle than the first flange facing portion, and can also be set according to the product shape between the first flange facing portion and the web facing portion and between the first flange facing portion and the arm facing portion, respectively.

Further, the above embodiment and other embodiments have been illustrated and explained using the case of rolling the hat-shaped steel sheet pile as an example, but the application range of the present invention is not limited to them. In other words, the present invention is applicable to steel sheet piles with flanges in various shapes where the flange wave possibly occurs in the intermediate rolling. More specifically, the present invention is applicable to a U-shaped steel sheet pile in addition to the hat-shaped steel sheet pile.

EXAMPLES
Example 1

As Example 1 of the present invention, a caliber corresponding to the modified caliber 69′ above explained referring to FIG. 7 was applied to the intermediate rolling caliber (the second caliber and the third caliber in the above embodiment), and the rolling and shaping was performed on the material to be rolled under the conditions 1 to 5 listed in the following Table 1.

The flange facing portion of the caliber was configured to be bent to three portions such that the first flange part crossed the neutral line of the calibers indicated in the conditions 1 to 5. Here, the angle and the length of each flange facing portion were adjusted. Further, the flange facing portion of the material to be rolled after the rolling and shaping was flattened in the calibers at the subsequent stages (the fourth caliber and the fifth caliber in the above embodiment).

Further, as comparative examples, the conventional caliber (a caliber corresponding to the caliber 69 before modification) was applied to the intermediate rolling caliber, and the rolling and shaping was performed on the material to be rolled under the conditions 6, 7 listed in the following Table 1.

The rolling and shaping in the caliber under each of the conditions indicated in the conditions 1 to 7 is performed in a plurality of passes, and the flange/web elongation ratios λf1/λw, λf2/λw, λf3/λw listed in Table 1 are elongation ratios per pass of the rolling and shaping in the plurality of passes. Note that in the examples and comparative examples, the flange angle θf of the hat-shaped steel sheet pile product as the final product to be produced was set to 48°. FIG. 9 is an explanatory view of this example, and is a schematic cross-sectional view illustrating an appearance of the final pass of the rolling and shaping in the third caliber according to the example. Note that FIG. 9 illustrates, using a broken line, the shape of the flange facing portion having a flange angle θf=48° similar to the final product. The values of codes θf1, θf2, θf3 listed in Table 1 are values at places illustrated in FIG. 9.

TABLE 1

PRODUCT FLANGE
FLANGE ANGLE(°)

λf2/λw

CONDITION
THICKNESS(mm)
θf1
θf2
θf3
λf1/λw
λf3/λw
RESULT

1
PRESENT
6.5
66
44
44
0.967
1.020
NO FLANGE

INVENTION

WAVE OCCURRED

2
PRESENT
6.5
60
45
45
0.985
1.018
NO FLANGE WAVE

INVENTION

OCCURRED

3
PRESENT
6.5
56
42
42
0.995
1.023
NO FLANGE WAVE

INVENTION

OCCURRED

4
PRESENT
6.5
54
45
45
1.000
1.018
NO FLANGE WAVE

INVENTION

OCCURRED

5
PRESENT
6.5
52
45
45
1.004
1.018
LITTLE FLANGE

INVENTION

WAVE DURING

INTERMEDIATE

ROLLING (NO

FLANGE WAVE ON

PRODUCT)

6
CONPARATIVE
6.5
48
1.013
FLANGE WAVE

EXAMPLE

OCCURRED

7
CONPARATIVE
7.7
48
0.995
FLANGE WAVE

EXAMPLE

OCCURRED

As listed in Table 1, under the conditions 1 to 5, the values of angles θf1, θf2, θf3 were changed as in Table 1 when forming the steep inclination part in the caliber and the intermediate rolling was performed under each of the conditions. Then, the flange corresponding part of the material to be rolled subjected to the rolling and shaping under of each of the conditions was then shaped into a linear shape (flat shape) in the rolling mill at the subsequent stage, and the defective shape such as the presence or absence of the occurrence of the flange wave was confirmed.

Under the conditions 1 to 5, the steep inclination part having θf1>θf2, θf1>θf3 was formed in the caliber, resulting in λf1<λf2, λf1<λf3, and the value of λf1/λw is 0.967 to 1.004. Under the above condition, the flange elongation at the steep inclination part was reduced to suppress the occurrence of the flange wave. Regarding the conditions 1 to 4, the value of λf1/λw is 0.967 to 1.000 so as to satisfy the above Expression (6), thus it was confirmed that there was no occurrence of the flange wave from the intermediate rolling time. Further, regarding the condition 5, the value slightly deviated from the range of the above Expression (6), little flange wave was confirmed in some passes during the intermediate rolling time, but no flange wave was confirmed in the product passed through the rolling at the subsequent stage and the like, and thus sufficient effect was confirmed.

On the other hand, under the condition 6 (comparative example), the rolling and shaping was performed without forming the steep inclination part in the caliber, resulting in flange elongation λf1>web elongation λw, and the rolling and shaping was rolling and shaping not satisfying the Expression (6) explained in the above embodiment, in which the occurrence of the flange wave was confirmed.

Further, under the condition 7 (comparative example), the flange thickness of the product was increased by 1.2 mm and rolling was performed under the condition of the value of λf1/λw of 0.995 to satisfy the Expression (6), but the rolling and shaping was performed without forming the steep inclination part as in the condition 6, and thus the occurrence of the flange wave was confirmed.

In short, in the comparative examples under the conditions 6, 7, the rolling and shaping was performed without forming the steep inclination part in the caliber under the condition that the inclination angle of the flange part was constant at any position, and thus the elongation was different depending on the position (part) of the flange part and the flange wave occurred.

From the above, it is found that bending the flange facing portion of the caliber into three portions suppresses the occurrence of the flange wave to enable the production in a size with small flange thickness.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a production technique of a steel sheet pile having a flange such as a hat-shaped steel sheet pile, a U-shaped steel sheet pile and the like.

EXPLANATION OF CODES

- 1 . . . rolling facility
- 3 . . . web corresponding part
- 5, 6 . . . flange corresponding part
- 8, 9 . . . arm corresponding part
- 10, 11 . . . joint corresponding part
- 14, 15 . . . claw part
- 17 . . . rough rolling mill
- 18 . . . first intermediate rolling mill
- 19 . . . second intermediate rolling mill
- 30 . . . finish rolling mill
- 45 . . . upper caliber roll (of first caliber)
- 48 . . . lower caliber roll (of first caliber)
- 49 . . . first caliber
- 55 . . . upper caliber roll (of second caliber)
- 58 . . . lower caliber roll (of second caliber)
- 59 . . . second caliber
- 65 . . . upper caliber roll (of third caliber)
- 68 . . . lower caliber roll (of third caliber)
- 69 . . . third caliber
- 69′ . . . modified third caliber
- 75 . . . upper caliber roll (of fourth caliber)
- 78 . . . lower caliber roll (of fourth caliber)
- 79 . . . fourth caliber
- 85 . . . upper caliber roll (of fifth caliber)
- 88 . . . lower caliber roll (of fifth caliber)
- 89 . . . fifth caliber
- 100 . . . facing portion
- 100
  a to 100c . . . flange facing portion
- 101
  a to 101c . . . flange facing portion
- A (A1 to A5) . . . material to be rolled
- L . . . rolling line
- O . . . neutral line

PRODUCTION METHOD AND PRODUCTION FACILITY FOR STEEL SHEET PILE WITH FLANGES

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