Roller correction method and device for steel sheet pile, and manufacturing method of steel sheet pile

Abstract

To provide a roller straightening technique capable of suppressing width variation at an end part of a steel pile in a longitudinal direction.SOLUTION: A method for straightening a steel pile having a pair of flanges connected to a web on both ends in a width direction through a corner part and a pair of joints at its tips with a roller provided with a plurality of rolls comprises: binding the web and the flange from an inner surface in a concave shape by bringing a roll surface where one roll in inside rolls can be contacted with a part of a web inner surface flat part and a part of a flange inner surface and is not contacted with the corner part by arranging the inside roll and the outside roll alternatively in a material passing direction over a material passing path of the steel pile into contact with a flat part of the web, and binding the steel pile from an outer surface in a convex shape with the outside roll having a roll surface going along to a part of the outer surface of the flange from the flat part of the web including the corner part of the outer surface of the steel pile in the convex shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a roller straightening method and a roller straightening device for straightening a steel sheet pile manufactured by hot rolling, a roller straightening roll, and a method for manufacturing a steel sheet pile, and in particular to a technology for preventing width fluctuation that makes the width of the steel sheet pile uneven during roller straightening.In this specification, the term "x to y" representing a numerical range means not less than x and not more than y, that is, includes the boundary value. [Background technology]

[0002] As an example of a steel sheet pile, the cross-sectional shape of a U-shaped steel sheet pile is shown in Figure 2. A steel sheet pile 1 manufactured by hot rolling is straight immediately after rolling is completed. However, at the end of rolling, the temperature of the web 1A, which has the largest thickness in the cross section, is high, so when it is cooled to room temperature, the thermal contraction of the web 1A is greater than that of the flange 1B and joint 1C. As a result, the steel sheet pile 1 after cooling will have an upward bow. Correction is required to remove the upward bow and straighten the sheet pile.

[0003] As a method for straightening the warpage of sectional steel, roller straightening, in which the steel is passed between rolls arranged in a staggered pattern as shown in Figure 3, to repeatedly bend the steel in the vertical direction, is widely used. To enhance the effectiveness of roller straightening and efficiently remove warpage, it is necessary to optimize the shapes of the upper and lower rolls to match the cross-sectional shape of the steel sheet pile product. For example, Patent Document 1 discloses a technology that enhances the straightening effect by restraining not only the web and flange but also the joint with rolls. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 61-63316 Summary of the Invention [Problem to be solved by the invention]

[0005] During roller straightening, the leading and trailing ends of the sheet pile are essentially free from bending moment at the distance between the upper and lower rolls in the passing direction F, i.e., half the roll pitch P shown in Figure 3 . Therefore, unlike the steady-state portion where bending moment is applied, the sheet pile passes through the roller straightening device 10 with almost no deformation. Due to this difference in deformation, shape defects can occur in the section from the end to approximately half the roll pitch P during the roller straightening process. Specifically, width fluctuations occur in this section, resulting in dimensional defects that exceed the width tolerance of the sheet pile after roller straightening. When a steel sheet pile with such dimensional defects is fitted to another steel sheet pile, the width-varying section can get caught and prevent proper fitting. Therefore, the sheet pile cannot be shipped as is. Therefore, the shape of the width-varying section must be corrected after roller straightening, necessitating an additional press straightening process using a press. In other words, if shape defects occur during the roller straightening process, additional processes require additional costs and time, leading to product shipment delays. Furthermore, if the shape defects cannot be corrected, the sheet pile cannot be shipped as a product and may be scrapped.

[0006] In the above-mentioned conventional technology, attempts were made to prevent the occurrence of shape defects due to width fluctuations by restraining the joint, but this was insufficient in effect, and the rate of occurrence of shape defects remained high.

[0007] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a roller straightening technology for steel sheet piles that can suppress width fluctuations at the longitudinal ends of the steel sheet piles. [Means for solving the problem]

[0008] The inventors have attempted to solve the problems of roller straightening by devising a new roll shape. The present invention provides a roller leveling method for a steel sheet pile, which has been developed to solve the above problems and achieve the above objects. The roller leveling method uses a roller with a plurality of rolls to level a steel sheet pile having a web, a pair of flanges connected to both widthwise ends of the web via corner portions, and a pair of joints at the widthwise tip end. The rollers are arranged such that inner rolls are disposed on a concave inner surface formed by the web and the pair of flanges, and outer rolls are disposed on a convex outer surface formed by the web and the pair of flanges, alternately in a passing direction across the passage of the steel sheet pile. At least one of the inner rolls has a roll surface that can contact a part of a flat portion of the inner surface of the web and a part of the inner surface of the flanges but does not contact the corner portions, and the roll surface contacts the flat portion of the web to restrain the web from the concave inner surface. The outer roll has a roll surface that can follow the convex outer surface of the steel sheet pile from the flat portion of the web including the corner portions to a part of the outer surface of the flanges, thereby restraining the steel sheet pile from the convex outer surface.

[0009] Regarding the roller straightening method for steel sheet piles according to the present invention, a. The width of the area near the corner of the web that does not contact the one roll is in the range of 10 to 20% of the inner surface width of the web at both ends in the width direction of the web, b. The steel sheet pile is a U-shaped steel sheet pile in which the joint is connected to the end of the flange opposite to the web; This may be a more preferable solution.

[0010] The roller leveling device for steel sheet piles according to the present invention, which has been developed to solve the above problems and achieve the above objects, is a device for leveling a steel sheet pile having a web, a pair of flanges connected to both widthwise ends of the web via corner portions, and a pair of joints at the widthwise tip, with a roller having a plurality of rolls, wherein the rollers are arranged alternately in the passing direction across the passage of the steel sheet pile, with inner rolls arranged on a concave inner surface formed by the web and the pair of flanges and outer rolls arranged on a convex outer surface formed by the web and the pair of flanges, and at least one of the inner rolls has a roll surface that can contact a part of the flat portion of the inner surface of the web and a part of the inner surface of the flange, but does not contact the corner portions, and the outer roll has a roll surface that can follow the convex outer surface of the steel sheet pile from the flat portion of the web, including the corner portions, to a part of the outer surface of the flange.

[0011] In addition, with regard to the roller straightening device for steel sheet piles according to the present invention, a more preferable solution may be that the width of the area where the one roll does not contact the inner surface of the web near the corner portion of the web is in the range of 10 to 20% of the inner surface width of the web at both ends of the width direction of the web.

[0012] The roller straightening roll for steel sheet piles of the present invention, which was developed to solve the above problems and achieve the above objects, is a roll used for roller straightening a steel sheet pile having a web, a pair of flanges connected to both widthwise ends of the web via corner portions, and a pair of joints at the widthwise tip, and is characterized in that the roll has a roll surface that does not come into contact with the corner portions when brought into contact with a portion of the flat portion of the inner surface of the web and a portion of the inner surface of the flange.

[0013] The manufacturing method of a steel sheet pile according to the present invention, which has been developed to solve the above problems and achieve the above objects, is characterized by including a step of straightening a steel sheet pile using any of the above roller straightening methods for a steel sheet pile. [Effects of the Invention]

[0014] The roller leveling method and device for steel sheet piles, the roller leveling roll for steel sheet piles, and the manufacturing method for steel sheet piles according to the present invention can prevent excessive strain from being introduced into both widthwise ends of the steel sheet pile web during roller leveling. This suppresses harmful deformations occurring at the longitudinal ends and at the boundary between the longitudinal ends and the steady portion, thereby reducing width fluctuations of the steel sheet pile during roller leveling. That is, the overall width of the longitudinal ends can be kept within an appropriate standard value range. Furthermore, a sudden change in the overall width at the boundary between the longitudinal ends and the steady portion can be suppressed. Therefore, the steel sheet pile has an excellent appearance and allows smooth joint fitting, contributing to improved productivity, cost reduction, and yield improvement, and is extremely useful in industry. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic front view showing a roll shape for explaining a roller straightening method for a steel sheet pile according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic front view showing the cross-sectional dimensions of a U-shaped steel sheet pile as an example of a steel sheet pile. [Figure 3] FIG. 1 is a schematic side view showing a roller straightening device for a steel sheet pile. [Figure 4] FIG. 1 is a schematic front view illustrating a roll shape used in a conventional roller straightening method. [Figure 5] FIG. 2 is an enlarged partial front view showing an example of detailed dimensions of a roll shape according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are intended to exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to the following. In other words, the technical concept of the present invention can be modified in various ways within the technical scope defined in the claims.

[0017] Figure 2 shows the cross-sectional shape of a U-shaped steel sheet pile as an example of a steel sheet pile to be leveled. The U-shaped steel sheet pile 1 is composed of a web 1A, which is a substantially horizontal portion, a pair of flanges 1B, which are bent from both ends of the web 1A in the width direction and extend obliquely toward one side of the web 1A, and a pair of joints 1C, which are connected to the tip of each flange 1B on the side opposite to the web 1A. The connection between the web 1A and the flanges 1B is called a corner portion 1D. The joints 1C are connected to the joints 1C of other steel sheet piles 1 by fitting to form a wall or the like.

[0018] As shown in Figure 2, W0 is the total width, that is, the distance between the outer ends of the joint 1C in the width direction. H0 is the total height. W e is the effective width, and H e is the effective height. W1 is the maximum opening width of the inner surface of the flange 1B, W2 is the inner surface width of the web 1A, and W3 is the outer surface width of the web 1A. H1 is the inner surface height. t w is the thickness of the web 1A and is almost constant. The thickness of the flange 1B gradually decreases from the web 1A side toward the joint 1C side.

[0019] Steel sheet piles 1 manufactured by hot rolling may warp after rolling and cooling, so it is necessary to alleviate and remove the warp. In addition, the width of steel sheet piles 1 manufactured by hot rolling is unlikely to be uniform, and there is a risk of variation between products. Therefore, it is necessary to adjust the width to reduce the variation between products.

[0020] The manufacturing process for steel sheet piles is as follows: Steel materials such as blooms and slabs are heated to a predetermined temperature in a heating furnace, and then hot-rolled in multiple rolling mills equipped with rolls with multiple grooves to form the steel sheet pile product shape.

[0021] Therefore, a roller straightening device 10 shown in Fig. 3 is installed in a manufacturing facility for manufacturing the steel sheet pile 1, and the steel sheet pile 1 is introduced into the roller straightening device 10 via a conveying line (not shown) of the manufacturing facility. The roller straightening device 10 reduces and removes the warp of the steel sheet pile 1 by cold straightening, and adjusts the width. Then, the steel sheet pile 1, which has been reduced and removed from the warp and has been adjusted in width for each target product, and has been made into a product of a desired shape, is transported to an inspection process and a shipping process via the conveying line.

[0022] In the roller leveling method for a steel sheet pile according to the present embodiment, a steel sheet pile 1 is leveled using a roll configuration having a shape shown in Fig. 1. For convenience, Fig. 1 shows an example in which the steel sheet pile is leveled in an inverted U-shaped position with an upward convexity, but the present invention is not limited to this, and may be leveled in a U-shaped position with a downward convexity, for example.

[0023] In this embodiment, as shown in Fig. 3, the roller straightening device 10 is composed of multiple rolls 2 and 3. The upper roll 2 is an outer roll having a roll surface shape that conforms to the convex outer surface of the steel sheet pile 1 formed by the web 1A and flange 1B as shown in Fig. 1. The lower roll 3 is an inner roll having a roll surface shape that conforms to the concave inner surface of the steel sheet pile 1 formed by the web 1A and flange 1B as shown in Fig. 1. The upper roll 2 and the lower roll 3 are arranged alternately in the material passing direction F across the material passage C of the steel sheet pile 1, forming a so-called staggered arrangement.

[0024] 1, one of the lower rolls 3 has a roll surface that can come into contact with part of the inner flat portion of the web 1A and part of the inner surface of the flange 1B, but does not come into contact near the corner portion 1D. On the other hand, the upper roll 2 has a roll surface that can fit from the outer flat portion of the web 1A, including the corner portion 1D, to part of the outer surface of the flange 1B.

[0025] In conventional roller leveling methods, as shown in Figures 1 and 4 of Patent Document 1, the roll shape is generally shaped to conform to the front and back surfaces of the steel sheet pile 1 to be leveled. In contrast, the inventors conducted a detailed investigation of the deformation state of a steel sheet pile due to roller leveling using the finite element method (FEM). As a result, they found that with such a conventional roll shape, large strain is introduced at both widthwise ends of the web 1A of the steel sheet pile 1. That is, in the steady portion in the longitudinal direction where bending is applied to the steel sheet pile 1, large strain is introduced at both widthwise ends of the web 1A. On the other hand, in the range from the head and tail ends to half the roll pitch P in the threading direction F, no bending deformation is applied, and therefore the deformation state is significantly different from that in the steady portion. They found that this is the cause of width variation and shape defects after roller leveling.

[0026] Therefore, as shown in Figure 1, the lower roll 3 is shaped so that it does not come into contact with the inner surface of the web 1A of the steel sheet pile 1 at both widthwise ends of the web 1A, i.e., at the corner portions 1D. This reduces the constraint on both widthwise ends of the web 1A by the rolls 2 and 3, and as a result, it becomes possible to reduce the magnitude of strain at both web ends. In other words, it becomes possible to prevent excessive strain from being applied to both widthwise ends of the web 1A. This reduces the difference in deformation between the leading and trailing ends and the steady portion, making it possible to reduce shape defects such as width fluctuations to an acceptable level.

[0027] Here, we will explain the area where the lower roll 3 does not contact the corner portion 1D of the steel sheet pile 1. For the cross-sectional shape of the U-shaped steel sheet pile 1 shown in Figure 2, the inner surface width W2 of the web 1A can be determined by the following definition. That is, one intersection point of a straight line extending the flat part of the inner surface of the web 1A and a straight line extending the outline of the inner surfaces of the pair of flanges 1B, 1B is defined as A, and the other intersection point is defined as B, and the distance from A to B can be defined as the inner surface width W2 of the web.

[0028] The widthwise length of the lower roll 3 that does not contact the inner surface of the steel sheet pile 1 near the corner portion 1D, i.e., the non-contact width, is preferably in the range of 10 to 20% of the inner surface width W2 of the web 1A at each of the widthwise ends of the web 1A. That is, in the case of the steel sheet pile shown in FIG. 2, if the inner surface width W2 of the web is 297 mm, for example, the preferred range is 29.7 to 59.4 mm. If the non-contact width is less than 10% of the inner surface width of the web 1A, the effect of alleviating the above-mentioned strain concentration may be insufficient. On the other hand, if it exceeds 20%, the bending deformation applied by the roll may be concentrated at the center of the web in the width direction, reducing the effect of correcting the upward camber. Therefore, the non-contact width is preferably in the range of 10 to 20% of the inner surface width W2 of the web 1A.

[0029] Furthermore, the roller straightening device 10 of this embodiment is a roller straightening device in which at least one of the lower rolls 3 has the above-described roll shape as an inner roll of the steel sheet pile. It is not necessary to apply rolls of this shape to all of the lower rolls 3. For example, rolls of this shape may be used for the third shaft (#3 in FIG. 3) and the fifth shaft (#5 in FIG. 3), which are subject to strong rolling conditions, and other shafts such as the seventh shaft (#7 in FIG. 3) may have rolls of a shape that conforms to the inner shape of the conventional steel sheet pile 1.

[0030] Furthermore, the steel sheet pile targeted by this embodiment is not limited to the cross-sectional shape shown in FIG. 2. Similar effects can be obtained with any cross-sectional shape of the steel sheet pile manufactured by hot rolling or cold forming. For example, a hat-shaped steel sheet pile is also possible. Furthermore, the roll shape is not limited to the shape shown in FIG. 1. Basically, as long as there is an area where the web 1A near the corner portion does not contact the inner roll, a similar effect of preventing shape defects can be obtained. Furthermore, the number of staggered rolls is not limited to nine, and can be increased or decreased within a reasonable range. For example, the first roll (#1 in FIG. 3) and the ninth roll (#9 in FIG. 3) can be flat rolls that contact the lower surface of the joint portion of the steel sheet pile. Furthermore, the lower roll 3 shown in FIG. 1 may be provided with a sleeve that restrains the widthwise outer edge of the joint 1C. Furthermore, a configuration in which some of the staggered rolls are provided with a sleeve and some are not provided with a sleeve may be used. [Example]

[0031] Examples of the present invention will be described below together with comparative examples. When a steel sheet pile having a cross-sectional shape shown in Fig. 2 was manufactured by hot rolling, a large upward camber occurred, so roller straightening was performed using a roller straightening device similar to that shown in Fig. 3.

[0032] In the compliant example, roller leveling was performed using a roller leveling device with four upper rolls and five lower rolls arranged in a staggered pattern on the third, fifth, and seventh axes, with the upper and lower roll configurations shown in Figures 1 and 5. In this compliant example, the width W4 where the inner surface of the web contacts the lower roll is 232 mm in the example shown in Figure 6, and the non-contact width W5 at both ends of the web in the width direction is 32.5 mm. This non-contact width corresponds to 10.9% of the inner web width W2 of the steel sheet pile, which is 297 mm.

[0033] In the compliance example, straightening was performed on 10 products. As a result, for all products, the overall width after straightening was within the dimensional tolerance range for the entire length. In addition, the overall width difference, which is the difference between the overall width at the longitudinal end and the overall width 1 m from the longitudinal end, was within -2 to +2 mm, and was within the allowable range of -4 to +4 mm.

[0034] As a comparative example, 10 steel sheet pile products with the same cross-sectional shape were flattened using a lower roll having a roll surface with a shape shown in Fig. 4, that is, a shape that runs from the inner flat portion of the web, including the corner portion, to the inner surface of the flange. As a result, 80% (8 piles) of the flattened products had dimensional defects, with the overall width difference exceeding the allowable range of -4 to +4 mm, and press flattening was required. Thus, the effect of the present invention is clear. [Industrial Applicability]

[0035] INDUSTRIAL APPLICABILITY The present invention can be used for roller leveling of steel sheet piles to suppress warpage and width fluctuation, contribute to improving productivity, reducing costs, and improving yield, and is extremely useful industrially. [Explanation of symbols]

[0036] 1 (U type) steel sheet pile 1A Web 1B flange 1C fitting 1D corner part 2 Upper roll 3 Lower roll 10. Roller straightening device (for steel sheet piles) F Threading direction C. Logging route (pass line) P Roll pitch

Claims

1. A method for straightening a steel sheet pile having a web, a pair of flanges connected to both ends of the web in a width direction via corner portions, and a pair of joints at a tip end in the width direction, by using a roller having a plurality of rolls, The rollers are arranged such that inner rolls arranged on a concave inner surface formed by the web and the pair of flanges and outer rolls arranged on a convex outer surface formed by the web and the pair of flanges are alternately arranged in a passing direction across the passing path of the steel sheet pile, one roll of the at least one inner roll arranged in the material-passing direction has a continuous roll surface that can come into contact with a part of a flat portion of the inner surface of the web and a part of the inner surface of the flange, of the concave inner surface of the steel sheet pile, as viewed from the material-passing direction, but does not come into contact with the corner portion, and the roll surface is brought into contact with the flat portion of the web to restrain the web from the concave inner surface, The steel sheet pile is restrained from the convex outer surface by the outer roll having a roll surface that can continuously follow the convex outer surface of the steel sheet pile from the flat portion of the web including the corner portion to a part of the outer surface of the flange, A roller straightening method for a steel sheet pile for straightening the steel sheet pile.

2. The width of the region near the corner portion of the web that does not contact the one roll is in the range of 10 to 20% of the inner surface width of the web at both ends in the width direction of the web. The roller straightening method for a steel sheet pile according to claim 1.

3. 3. The roller straightening method for a steel sheet pile according to claim 1, wherein the steel sheet pile is a U-shaped steel sheet pile in which the joint is connected to an end of the flange opposite to the web.

4. A device for straightening a steel sheet pile having a web, a pair of flanges connected to both ends of the web in the width direction via corner portions, and a pair of joints at the tip in the width direction, by using a roller having a plurality of rolls, the rollers are arranged such that inner rolls arranged on a concave inner surface formed by the web and the pair of flanges and outer rolls arranged on a convex outer surface formed by the web and the pair of flanges are alternately arranged in a passing direction across the passing path of the steel sheet pile, one roll of the at least one inner roll arranged in the material-passing direction has a continuous roll surface that can come into contact with a part of a flat portion of the inner surface of the web and a part of the inner surface of the flange, among the concave inner surfaces of the steel sheet pile, when viewed from the material-passing direction, but does not come into contact with the corner portion; The roller straightening device for a steel sheet pile, wherein the outer roll has a roll surface that can continuously follow the convex outer surface of the steel sheet pile from the flat portion of the web including the corner portion to a part of the outer surface of the flange.

5. 5. The roller straightening device for a steel sheet pile according to claim 4, wherein the width of an area where the one roll does not contact the inner surface of the web near the corner portion of the web is in the range of 10 to 20% of the inner surface width of the web at both ends in the width direction of the web.

6. A method for manufacturing a steel sheet pile, comprising a step of straightening the steel sheet pile by the method according to claim 1 or 2.

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