Cylindrical structure

Abstract

To provide a cylindrical structure which reduces the man-hours spent in welding while suppressing lowering of fatigue characteristics.SOLUTION: A cylindrical structure (1) is formed by welding in a circumferential direction and a column shaft direction. The cylindrical structure (1) has: steel plate materials (10) which are connected to each other in the circumferential direction and the column shaft direction of the cylindrical structure (1) by welding; a circumferential direction welding part (W1) for welding the plate materials (10) which are adjacent to each other in the column shaft direction; and a column shaft direction welding part (W2) for welding the plate materials (10) which are adjacent to each other in the circumferential direction. The thickness of the circumferential direction welding part (W1) in the plate thickness direction of the plate material (10) is 0.9 times or more and 1.1 times or less the plate thickness of the plate material (10), and the thickness of the column shaft direction welding part (W2) in the plate thickness direction of the plate material (10) is 0.2 times or more and less than 0.9 times the plate thickness of the plate material (10).SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a cylindrical structure. [Background technology]

[0002] Generally, cylindrical structures are widely used for towers and foundations. As the size of the equipment increases, the strength and rigidity of cylindrical structures must be increased, and the outer diameter and plate thickness must also be increased. As the plate thickness increases, the welding man-hours become enormous, reducing productivity and affecting the manufacturing schedule. Furthermore, there are limits to the capabilities of bending equipment when it comes to increasing thickness and diameter.

[0003] As a countermeasure for increasing the thickness and diameter, for example, a polygonal cylindrical structure in which flat plates are connected is known (see, for example, Patent Document 1). Generally, in a cylindrical structure, welding is performed by full penetration welding. It is known that the welding man-hours can be reduced by alternately providing multiple sections in the height direction (column axis direction) of a cylindrical structure where the weld metal is thinner than the plate thickness, i.e., partial penetration welding sections, in the height direction of a single metal plate (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6160043 [Patent Document 2] Patent No. 7187707 Summary of the Invention [Problem to be solved by the invention]

[0005] In polygonal cylindrical structures, the issue of welding man-hours remains, just as in circular cylindrical structures. When multiple sections of partial penetration welds are provided in the height direction, there are multiple toes where the amount of penetration changes. Stress concentrates at the weld toes, and stress acts in the vertical direction of the column axis, raising concerns about the occurrence of fatigue cracks. When multiple partial penetration welds are provided, stress concentration occurs in multiple areas, which may result in a deterioration of fatigue properties.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to propose a tubular structure that reduces the number of welding steps while suppressing a deterioration in fatigue characteristics. [Means for solving the problem]

[0007] (1) A cylindrical structure according to one embodiment of the present disclosure is a cylindrical structure formed by welding in a circumferential direction and a column axis direction, the cylindrical structure having steel plates connected by welding in the circumferential direction and the column axis direction of the cylindrical structure, a circumferential weld that welds the plate materials adjacent to each other in the column axis direction, and a column axis direction weld that welds the plate materials adjacent to each other in the circumferential direction, wherein the thickness of the circumferential weld along the plate thickness direction of the plate materials is 0.9 to 1.1 times the plate thickness of the plate materials, and the thickness of the column axis direction weld along the plate thickness direction of the plate materials is 0.2 to 0.9 times the plate thickness of the plate materials. (2) In the cylindrical structure according to (1) above, at the intersection of the circumferential weld and the column axis direction weld, an intersection extension weld, in which the plate thickness along the plate thickness direction of the plate material is 0.9 to 1.1 times, may extend in the column axis direction by 2 to 10 times the plate thickness of the plate material. (3) The cylindrical structure according to (1) or (2) above may be configured such that the column axis direction welds of the respective plate materials connected in the column axis direction are not continuous with each other in the column axis direction. (4) The cylindrical structure according to (1) above may be configured such that the column axis direction welds of each of the plate materials connected in the column axis direction are arranged continuously in the column axis direction, and the circumferential direction welds of each of the plate materials connected in the circumferential direction are arranged continuously in the circumferential direction. (5) The tubular structure according to (3) or (4) above may be cylindrical. (6) The cylindrical structure according to (4) above may be polygonal. (7) In the cylindrical structure according to (5) above, the rolling direction of the plate material may be the circumferential direction. (8) In the cylindrical structure according to (6) above, the rolling direction of the plate material may be the column axis direction. (9) The cylindrical structure according to any one of the above (1) to (8) may have a penetration amount changing portion formed at an intersection of the circumferential weld and the column axis direction weld, and a peening portion at a toe where the column axis direction weld and the penetration amount changing portion intersect. (10) In the cylindrical structure according to (9) above, the peening portion may be formed on either the inner surface side or the outer surface side of the cylindrical structure, or on both the inner surface side and the outer surface side of the cylindrical structure. [Effects of the Invention]

[0008] According to the cylindrical structure of the present disclosure, it is possible to reduce the number of welding steps while suppressing deterioration in fatigue characteristics. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a perspective view illustrating a cylindrical structure of a cylinder according to an embodiment of the present disclosure. [Figure 1B] FIG. 1 is a perspective view illustrating a polygonal cylindrical structure according to an embodiment of the present disclosure. [Figure 2A] FIG. 1B is a side view of the cylindrical structure shown in FIG. 1A. [Figure 2B] FIG. 2B is a cross-sectional view taken along line IIB-IIB of FIG. 2A. [Figure 2C] FIG. 2B is a cross-sectional view taken along line IIC-IIC of FIG. 2A. [Figure 3A] FIG. 2B is a cross-sectional view showing a part of the cross section III-III of FIG. 2A. [Figure 3B] FIG. 3 is a cross-sectional view showing another example of a part of the cross section taken along the line III-III in FIG. 2A. [Figure 4A]FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 4B] FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 5A] FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 5B] FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 6A] FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 6B] FIG. 1 is a cross-sectional view showing a portion of a partial penetration weld of a cylindrical tubular structure according to an embodiment of the present disclosure. [Figure 7A] FIG. 1 is a cross-sectional view illustrating a portion of a partial penetration weld of a polygonal tubular structure according to an embodiment of the present disclosure. [Figure 7B] FIG. 1 is a cross-sectional view illustrating a portion of a partial penetration weld of a polygonal tubular structure according to an embodiment of the present disclosure. [Figure 8A] FIG. 1 is a cross-sectional view illustrating a portion of a partial penetration weld of a polygonal tubular structure according to an embodiment of the present disclosure. [Figure 8B] FIG. 1 is a cross-sectional view illustrating a portion of a partial penetration weld of a polygonal tubular structure according to an embodiment of the present disclosure. [Figure 9] FIG. 2 is a cross-sectional view showing a peening portion having a cylindrical structure according to an embodiment of the present disclosure. [Figure 10] FIG. 2 is a cross-sectional view showing a peening portion having a cylindrical structure according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a cylindrical structure according to an embodiment of the present disclosure will be described with reference to the drawings.

[0011] 1A and 1B, a cylindrical structure 1 according to an embodiment of the present disclosure is a cylindrical structure extending along a central axis O. In the cylindrical structure 1, a direction parallel to the central axis O is referred to as a column axis direction, a direction circumferentially around the central axis O is referred to as a circumferential direction, and a direction perpendicular to the central axis O is referred to as a radial direction. In the radial direction, a direction toward the central axis O is referred to as an inward direction, and a direction away from the central axis O is referred to as an outward direction.

[0012] The cylindrical structure 1 may have a cylindrical shape as shown in Fig. 1A or a polygonal shape as shown in Fig. 1B. In the following, the case where the cylindrical structure 1 has a cylindrical shape will be mainly described first. The case where the cylindrical structure 1 has a polygonal shape will be described later. Fig. 2A is a side view of the cylindrical structure 1 shown in Fig. 1A, Fig. 2B is a cross-sectional view taken along line IIB-IIB in Fig. 2A, and Fig. 2C is a cross-sectional view taken along line IIC-IIC in Fig. 2A.

[0013] The cylindrical structure 1 is a long body installed with the column axis direction parallel to the vertical direction, and has a hollow cylindrical shape. Devices that do not contribute to structural performance may be installed in the hollow part of the cylindrical structure 1. The cylindrical structure 1 is formed by welding in the circumferential direction and the column axis direction. The cylindrical structure 1 has a plate material 10, a circumferential weld W1, and a column axis weld W2.

[0014] The plate materials 10 are made of steel and are connected by welding in the circumferential direction and the column axis direction of the cylindrical structure 1. As shown in Fig. 2B, the horizontal cross-sectional shape of the cylindrical structure 1 perpendicular to the column axis direction is circular.

[0015] As shown in Figures 1A and 2A, the welded portion (welded portion) is indicated by the symbol W. The welded portion W has a circumferential welded portion W1 extending along the circumferential direction and a column axial welded portion W2 extending along the column axial direction. The circumferential weld W1 welds adjacent plate materials 10 in the column axis direction. The column axis weld W2 welds adjacent plate materials 10 in the circumferential direction. In this embodiment, ten plate materials 10 of the same shape are connected in the circumferential direction, so that the cross-sectional shape of the tubular structure 1 is cylindrical.

[0016] The cylindrical structure 1 shown in Fig. 1A is formed by connecting a ring body 10A, which is made up of ten plate materials 10 connected in the circumferential direction, in multiple stages (two stages are shown in Fig. 1A) in the column axis direction. The column axis direction welds W2 of each of the plate materials 10 connected in the column axis direction may be configured so as not to be contiguous in the column axis direction, a so-called staggered configuration. The column axis direction welds W2 and the circumferential direction welds W1 intersect in a T-shape. Specifically, the column axis direction weld W2 (W21) in one ring body 10A (first ring body 10A1) connected circumferentially and the column axis direction weld W2 (W22) in another ring body 10A (second ring body 10A2) connected to the ring body 10A (first ring body 10A1) by the circumferential weld W1 are configured to be discontinuous in the column axis direction.

[0017] This configuration can reduce the tensile residual stress at the intersection of the circumferential weld W1 and the column axial weld W2, and can also suppress the occurrence of welding defects.

[0018] FIG. 2B shows a cross section passing through the center of the circumferential weld W1 in the direction of the central axis O. FIG. 3A is a cross section showing a portion of the axial cross section passing through III-III in FIG. 2A, and FIG. 3B is a cross section showing another example of a portion of the axial cross section passing through III-III in FIG. 2A. The thickness tc (mm) of the circumferential weld W1 along the thickness direction of the plate material 10 is 0.9 to 1.1 times the plate thickness t (mm) of the plate material 10. In FIGS. 2B, 3A, and 3B, the thickness tc of the circumferential weld W1 is approximately the same as the plate thickness t of the plate material 10. In the present disclosure, a case where the thickness tc of the circumferential weld W1 is 0.9 to 1.1 times the plate thickness t of the plate material 10 is referred to as full penetration welding. Full penetration welding involves welding across almost the entire thickness of the plate material 10 in the radial direction of the tubular structure 1. The circumferential weld W1 may be welded from the outside of the tubular structure 1, i.e., from the outer surface 11 side of the plate 10. The circumferential weld W1 may be welded from the inside of the tubular structure 1, i.e., from the inner surface 12 side of the plate 10. The thickness tc of the circumferential weld W1 may be measured at three equally spaced locations around the circumferential direction of the circumferential weld W1, and the average value of the measured values may be used. The thickness t of the plate 10 may be measured at three equally spaced locations at any position on the plate 10, and the average value of the measured values may be used.

[0019] In the cylindrical structure 1, the principal stress is in the column axis direction. In the circumferential weld W1, stress acts in the direction perpendicular to the weld line, and high fatigue properties are required, so full penetration welding is used. In the cylindrical structure 1 according to this embodiment, full penetration welding is performed at the circumferential weld W1, which requires high fatigue properties, and therefore fatigue damage can be suppressed. From the viewpoints of reducing stress concentration and improving fatigue strength, the thickness tc of the circumferential weld W1 is preferably at least 0.92 times, and more preferably at least 0.95 times, the thickness t (mm) of the plate material 10. From the viewpoints of welding efficiency and structural weight, the thickness tc of the circumferential weld W1 is preferably at most 1.08 times, and more preferably at most 1.05 times, the thickness t (mm) of the plate material 10.

[0020] Fig. 2C is a cross-sectional view taken along line IIC-IIC in Fig. 2A. The cross section IIC-IIC is perpendicular to the central axis O and passes through the column axial weld W2. 2C, the column axis direction weld W2 partially welds the plate material 10 in the radial direction of the tubular structure 1. The thickness ta (mm) of the column axis direction weld W2 along the plate thickness direction of the plate material 10 is 0.2 to less than 0.9 times the plate thickness t of the plate material 10. In the present disclosure, when the thickness ta (mm) of the column axis direction weld W2 is 0.2 to less than 0.9 times the plate thickness t of the plate material 10, it is referred to as partial penetration welding. In the column axial weld W2, stress acts in a direction parallel to the weld line, and the required fatigue properties are lower than those of the circumferential weld W1, so partial penetration welding is used. The thickness ta of the column axis direction weld W2 can be determined by, for example, measuring the column axis direction weld W2 at three equally spaced locations in the column axis direction, and averaging the measurements.

[0021] In the past, partial penetration butt welding was performed from the outer and inner surfaces, leaving the center of the plate unwelded. When this type of partial penetration welding is used, the rigidity of the tubular structure 1 is inferior to that of full penetration welding. In this embodiment, partial penetration welding of the column axial weld W2 is performed from the outside of the cylindrical structure 1, that is, from the outer surface 11 side of the plate material 10. Because the rigidity of the cylindrical structure 1 is strongly affected by the amount of welding on the outer surface, welding in this manner can efficiently ensure the rigidity of the cylindrical structure 1 compared to welding from both the outer and inner surfaces with the same amount of welding.

[0022] 3A and 3B, a portion W4 where the weld penetration changes (penetration change portion) is formed at the intersection 20 between the circumferential weld W1 and the column axis weld W2. The penetration change portion W4 is formed between the circumferential weld W1 and the column axis weld W2. The penetration amount change portions W4 are formed on both ends of the column axis direction welded portion W2 in the column axis direction. However, in this embodiment, the penetration amount change portions W4 are formed on the inside of the column axis direction welded portion W2.

[0023] In the thickness direction of the plate material 10, the sum of the thickness ta of the column axial weld W2 and the thickness of the penetration change portion W4 (total thickness of the penetration change portion) tw (mm) gradually decreases from the circumferential weld W1 toward the column axial weld W2. As shown in FIG. 3A, the penetration change portion W4 smoothly joins the circumferential weld W1 and the column axial weld W2. In the case shown in FIG. 3B, the penetration change portion W4 may smoothly join the cross extension weld W3 (described later) and the column axial weld W2. The thickness tw of the penetration change portion W4 is an intermediate value between the thickness tc of the circumferential weld W1 and the thickness ta of the column axial weld W2.

[0024] Generally, stress concentrates at the toe of the weld where the surface of the plate material 10 intersects with the weld. In this embodiment, as shown in Figures 3A and 3B, the point where the penetration change area W4 intersects with the column axial weld W2 is the toe of the weld P. There is a possibility that stress will concentrate at this toe of the weld P.

[0025] When multiple partial penetration welds are alternately provided in the height direction of a single metal plate as in Patent Document 2, multiple toes of the metal plate where the amount of penetration varies are alternately present, which may result in stress concentration in multiple areas of the single metal plate, potentially deteriorating fatigue properties.

[0026] In the cylindrical structure 1 according to this embodiment, the number of penetration change portions W4 is reduced by partial penetration welding in the column axial direction except for the circumferential weld W1. This reduces the number of weld toes P where the penetration change portions W4 intersect with the column axial weld W2, thereby reducing the number of welding man-hours while suppressing deterioration of fatigue properties.

[0027] From the viewpoint of weld strength, the thickness ta of the column axis direction weld W2 is preferably 0.24 times or more, and more preferably 0.3 times or more, the plate thickness t of the plate material 10. From the viewpoint of reducing the amount of welding, the thickness ta of the column axis direction weld W2 is preferably less than 0.88 times, and more preferably 0.85 times or less, the plate thickness t of the plate material 10.

[0028] The welding method for the circumferential weld W1 and the column axial weld W2 is not particularly limited, but examples thereof include MAG (Metal Active Gas Welding), FCAW (Flux Cored Arc Welding), and SAW (Submerged Arc Welding).

[0029] The intersection of the circumferential weld W1 and the column axial weld W2 is an area where welding residual stress is large. Therefore, it is desirable that the circumferential weld W1 and the column axial weld W2 are separated by a certain distance. In this embodiment, as shown in Figure 3B, an intersection extension weld W3 may be provided between the circumferential weld W1 and the column axial weld W2. 3B is an axial cross-sectional view taken along line III-III in FIG. 2A, showing the vicinity of intersection 20 where circumferential weld W1 and column axial weld W2 intersect. Intersection extension weld W3 is present on the inner surface 12 side of cylindrical structure 1 and is not shown in FIG. 2A. At the intersection 20 between the circumferential weld W1 and the column axis direction weld W2, the cross extension weld W3, which has a thickness tb of 0.9 to 1.1 times along the thickness direction of the plate 10, preferably extends in the column axis direction from two to ten times the plate thickness t of the plate 10. As shown in FIG. 3B , the cross extension weld W3 extends in the column axis direction from the end face 10S of the plate 10 from two to ten times the plate thickness t of the plate 10. In FIG. 3B , the cross extension weld W3 extends upward from the upper end face (10S) of the lower plate 10 from two to ten times the plate thickness t of the plate 10. The cross extension weld W3 is a weld between the circumferential weld W1 and the column axis direction weld W2. The penetration amount change portion W4 smoothly joins the intersection extension weld portion W3 and the column axis direction weld portion W2.

[0030] By providing a cross extension weld W3 between the circumferential weld W1 and the column axial weld W2, with a thickness tb of 0.9 to 1.1 times, stress can be reduced. The thickness tb is preferably 0.9 times or more, and more preferably 0.95 times or more. The thickness tb is preferably 1.1 times or less, and more preferably 1.05 times or less. The cross extension weld W3 preferably extends in the column axis direction two times or more, and more preferably three times or more, the thickness t of the plate material 10. The cross extension weld W3 preferably extends in the column axis direction ten times or less, and more preferably eight times or less, the thickness t of the plate material 10. The thickness tb of the cross extension weld W3 can be determined, for example, by measuring three equally spaced locations in the column axis direction of the cross extension weld W3 and averaging the measurements.

[0031] The cylindrical structure 1 may have a polygonal shape as shown in FIG. 1B. In this case, the cylindrical structure 1 is a polygonal cylindrical structure whose horizontal cross-sectional shape is formed by the same number of corners (here, an octagon). The cylindrical structure 1 is formed by connecting steel plates 10 by welding in the circumferential direction and the column axis direction. The horizontal cross-sectional shape of the cylindrical structure 1 perpendicular to the column axis direction is a regular octagon. Note that the cross-sectional shape of the cylindrical structure 1 may be any polygonal cross-section having at least 6 sides and at most 24 sides. Furthermore, the cylindrical structure 1 is not limited to a regular polygon with all sides having the same length, and it is also possible to adopt a polygon with some or all of the side lengths being different.

[0032] In this disclosure, the following cases are treated as regular polygons: The circumferential dimensions of the plate materials 10 are within ±2% of the average value. The angle between adjacent plate materials 10 (in the case of the interior angles of a regular polygon, all interior angles fall within ±2% of (180×(n-2)) / n.

[0033] The cylindrical structure 1 may have a truncated cone shape (tapered shape) in which the cross-sectional shape gradually decreases upward as shown in Fig. 1B. In this case, the cross-sectional shapes at any height in the column axis direction are similar. The plate material 10 has a trapezoidal shape that decreases upward when viewed from the front. The cylindrical structure 1 may have a cross-sectional outer diameter that is substantially uniform in the column axis direction, that is, a cylindrical polygonal shape. In this case, the plate material 10 has a rectangular shape when viewed from the front. The cylindrical structure 1 may be a combination of a cylindrical polygonal shape and a frustum shape. For example, the cylindrical structure 1 may have a lower portion that is a cylindrical polygonal shape and an upper portion that is a frustum shape. The cylindrical tubular structure 1 may also be a frustum shape, or a combination of a cylindrical shape and a frustum shape.

[0034] In the polygonal cylindrical structure 1, from the viewpoint of efficiency of welding work, the circumferential welded portion W1 can be continuous in the circumferential direction, and the column axial welded portion W2 can be continuous in the axial direction. 1B, the column axial welds W2 and the circumferential welds W1 intersect in a cross shape. As shown in Fig. 1B, the column axial welds W2 of the plates 10 connected in the column axial direction are arranged consecutively in the column axial direction in the cylindrical structure 1, and the circumferential welds W1 of the plates 10 connected in the circumferential direction are arranged consecutively in the circumferential direction.

[0035] With this configuration, the circumferential weld W1 and the column axis direction weld W2 can be welded efficiently. The above-mentioned cross extension weld W3 may be provided between the circumferential weld W1 and the column axis direction weld W2.

[0036] In the cylindrical tubular structure 1, the rolling direction (longitudinal direction) of the plate material 10 is preferably the circumferential direction. With this configuration, in the bending process of the plate material 10, it becomes easy to bend a single plate material 10 to a desired cylindrical radius. In the polygonal cylindrical structure 1, the rolling direction of the plate material 10 is preferably the column axis direction. With this configuration, the plate material 10 becomes longer in the column axis direction, and the number of stages in the column axis direction of the cylindrical structure 1 can be reduced. The rolling direction of the plate material 10 is not limited to the circumferential direction in the cylindrical tubular structure 1. Furthermore, the rolling direction of the plate material 10 is not limited to the column axis direction in the polygonal tubular structure 1.

[0037] A method for controlling the weld penetration amount of the column axial weld W2 will be described.

[0038] 4A to 6B, a case where the tubular structure 1 has a cylindrical shape will be described. The welded portion W is welded from the outside of the tubular structure 1. 4A to 6B are cross-sectional views showing a part of partial penetration welding of the cylindrical tubular structure 1. Figures 4A to 6B are the same as the arrow views of Figure 2C, and show a part of the column axial direction weld W2.

[0039] 4A shows the case where the groove in the plate material 10 is an X-groove, and FIG. 4B shows the case where the groove in the plate material 10 is a Y-groove. In FIGS. 4A and 4B, the thickness ta (penetration depth) (mm) of the column axis direction weld W2 is controlled by the depth of the groove in the plate material 10. The column axis direction weld W2 is welded from the outside of the plate material 10 to the bottom of the groove. The length from the outer surface 11 of the plate material 10 to the bottom of the groove along the plate thickness direction of the plate material 10 is the thickness ta of the column axis direction weld W2.

[0040] 5A and 5B show the case where a metal insert 35 or flux 36 is filled inside the cylindrical structure 1. A V-shaped groove is formed in the sheet material 10 so that the groove is convex from the outer surface 11 of the sheet material 10 toward the inner surface 12 of the sheet material 10. The inner side of the V-shaped groove is raised with the metal insert 35 or flux 36, and welding is performed from the outside of the cylindrical structure 1, thereby controlling the thickness ta (mm) of the column axial weld W2. The metal insert 35 is, for example, steel or ceramic. Insert 35 or flux 36 is filled into the inner surface of the V-groove from the outside of the cylindrical structure 1. Welding is performed on the outside of the insert 35 or flux 36 to form a column axial direction weld W2. The column axial direction weld W2 and the insert 35 or flux 36 are joined at a joint surface 41. In the thickness direction of the plate material 10, the length from the outer surface 11 of the plate material 10 to the joint surface 41 is the thickness ta of the column axial direction weld W2. The contact surface 37 between the surface of the V-groove of the plate material 10 and the insert 35 or flux 36 is not welded.

[0041] To improve fatigue properties, inner welding may be performed at inner weld 39. As shown in FIG. 5B, inner welding is performed at inner weld 39 on the inside of the tip of the V-groove. After welding inner weld 39, insert 35 or flux 36 may be filled, and then column axis direction weld W2 may be welded. Alternatively, insert 35 or flux 36 may be filled, then inner weld 39 may be welded, and then column axis direction weld W2 may be welded. Alternatively, insert 35 or flux 36 may be filled, then column axis direction weld W2 may be welded, and then inner weld 39 may be welded. In FIG. 5B, insert 35 or flux 36 is filled, then column axis direction weld W2 may be welded.

[0042] The thickness td (mm) of the inner weld 39 along the thickness direction of the plate material 10 is, for example, 0.05 to 0.2 times the thickness t of the plate material 10. By setting the thickness td of the inner weld 39 to 0.05 to 0.2 times the thickness t of the plate material 10, the fatigue characteristics can be improved. The thickness td of the inner weld 39 is more preferably 0.1 times or more the thickness t of the plate material 10. The thickness td of the inner weld 39 is more preferably 0.15 times or less the thickness t of the plate material 10.

[0043] 6A and 6B show a case where a V-shaped groove is formed in the plate material 10 so that the groove is convex from the outer surface 11 of the plate material 10 toward the inner surface 12 of the plate material 10, and a tapered portion 40 is provided in the plate material 10 to control the thickness of the weld. The tapered portion 40 is provided near the groove of the plate material 10 to reduce the plate thickness t of the plate material 10. The tapered portion 40 is provided in the cross section of the plate material 10 so that the plate thickness t of the plate material 10 becomes thinner toward the groove of the plate material 10. The tapered portion 40 may be provided on the outer surface 11 side (outside) of the cylindrical structure 1 as shown in FIG. 6A, or on the inner surface 12 side (inside) of the cylindrical structure 1 as shown in FIG. 6B. In the thickness direction of the plate material 10, the length from the outer surface 11 of the plate material 10 to the bottom of the groove is the thickness ta (mm) of the column axis direction weld W2. Since the thickness of the plate material 10 near the groove is thin, the thickness ta of the column axis direction weld W2 is small. From the viewpoint of the rigidity of the cylindrical structure 1, it is preferable to provide the tapered portion 40 on the inner surface 12 side of the plate material 10.

[0044] 7A to 8B, a method for controlling the weld penetration amount of the column axial direction weld W2 when the tubular structure 1 has a polygonal shape will be described below. The following mainly describes the configuration when the tubular structure 1 has a polygonal shape that is different from when the tubular structure 1 has a cylindrical shape.

[0045] As shown in Figures 7A to 8B, welding is performed from the outside of the tubular structure 1. 7A to 8B are cross-sectional views showing a part of partial penetration welding of polygonal cylindrical structure 1. Figures 7A to 8B are the same as the arrow views of Figure 2C, and show a part of column axis direction weld W2.

[0046] Fig. 7A shows a case where the groove in the plate material 10 is an X-groove, similar to Fig. 4A. Fig. 7B shows a case where the groove in the plate material 10 is a Y-groove, similar to Fig. 5B. Insert 35 or flux 36 is filled inside the cylindrical structure 1, and inner surface welding is performed at inner surface weld 39. 7A and 7B, the thickness ta (penetration depth) (mm) of the column axis direction weld W2 is controlled by the depth of the groove in the plate material 10. The column axis direction weld W2 is welded from the outside of the plate material 10 to the bottom of the groove. In the thickness direction of the plate material 10, the length from the outer surface 11 of the plate material 10 to the bottom of the groove is the thickness ta of the column axis direction weld W2.

[0047] Figure 8A shows a case where, as in the case of Figure 6A, a V-shaped groove is formed in the sheet material 10 so that the groove is convex from the outer surface 11 of the sheet material 10 toward the inner surface 12 of the sheet material 10, and a tapered portion 40 is provided on the outer surface 11 side of the sheet material 10. Figure 8B shows a case where, as in the case of Figure 6B, a V-shaped groove is formed in the sheet material 10 so that the groove is convex from the outer surface 11 of the sheet material 10 toward the inner surface 12 of the sheet material 10, and a tapered portion 40 is provided on the inner surface 12 side of the sheet material 10. In the thickness direction of the plate material 10, the length from the outer surface 11 of the plate material 10 to the bottom of the groove is the thickness ta (mm) of the column axis direction weld W2. Since the thickness of the plate material 10 near the groove is thin, the thickness ta of the column axis direction weld W2 is small. From the viewpoint of the rigidity of the cylindrical structure 1, it is preferable to provide the tapered portion 40 on the inner surface 12 side of the plate material 10. The thickness t of the plate material 10 of the cylindrical structure 1 according to this embodiment, the thickness ta of the column axial weld W2, the thickness tb of the cross extension weld W3, the thickness tc of the circumferential weld W1, and the thickness td of the inner weld 39 can be measured by non-destructive testing using ultrasound, even when filling with a metal insert 35 or flux 36.

[0048] Since stress concentrates at the toe P where the penetration change portion W4 and the column axial weld portion W2 intersect, there is a risk of the fatigue properties deteriorating. In order to improve the fatigue properties, for example, peening treatment is performed on the toe P. As shown in Figures 3A and 3B, it is preferable to provide a peening portion 30 at the toe P where the column axial weld portion W2 and the penetration change portion W4 intersect. The peening portion 30 is formed in the circumferential direction of the cylindrical structure 1, and is preferably formed at the toe P across the width of the column axial weld portion W2.

[0049] The method of treating the peened portion 30 is not limited, and examples thereof include hammer peening, needle peening, and ultrasonic peening.

[0050] The peening portion 30 may be formed on either the inner surface 12 side or the outer surface 11 side of the cylindrical structure 1. The peening portion 30 may be formed on both the inner surface 12 side and the outer surface 11 side of the cylindrical structure 1. For example, when the groove of the plate material 10 is an X-shaped groove as shown in Fig. 4A, the peening portion 30 may be formed on both the inner surface 12 side and the outer surface 11 side of the cylindrical structure 1 as shown in Fig. 9. Alternatively, the peening portion 30 may be formed on either the inner surface 12 side or the outer surface 11 side of the cylindrical structure 1. 5B, when the groove of the plate material 10 is a V-groove, the peening portion 30 may be formed on both the inner surface 12 side and the outer surface 11 side of the cylindrical structure 1, as shown in FIG. 10. Alternatively, the peening portion 30 may be formed on either the inner surface 12 side or the outer surface 11 side of the cylindrical structure 1.

[0051] From the viewpoint of improving fatigue characteristics, it is preferable that the peening portion 30 be formed on both the inner surface 12 side and the outer surface 11 side of the cylindrical structure 1.

[0052] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0053] The above-described cylindrical structure 1 may be used, for example, in a wind power generation facility. Specifically, it may be used as a detachable monopile foundation structure for offshore buoyancy. The cylindrical structure 1 may also be used for other purposes. [Explanation of symbols]

[0054] 1 cylindrical structure 10 Board material 10A Ring body 20 Intersection 30 Peening section 35 Deposit 36 Flux 39 Internal weld 40 Tapered section 41 Joint surface O center axis P toe W welded section W1 Circumferential weld W2 Column axial weld W3 cross extension weld W4 Change in penetration amount

Claims

1. A cylindrical structure formed by welding in the circumferential direction and the column axis direction, The cylindrical structure is Steel plate materials connected by welding to the cylindrical structure in the circumferential direction and the column axis direction; a circumferential weld portion that welds the plate materials adjacent in the column axis direction; a column axial weld portion that welds the plate materials adjacent in the circumferential direction; and The thickness of the circumferential weld along the plate thickness direction of the plate material is 0.9 to 1.1 times the plate thickness of the plate material, A cylindrical structure, wherein the thickness of the column axial direction weld along the plate thickness direction of the plate material is 0.2 times or more and less than 0.9 times the plate thickness of the plate material.

2. 2. The cylindrical structure according to claim 1, wherein at an intersection between the circumferential weld and the column axial weld, an intersection extension weld having a plate thickness in the plate thickness direction of the plate material of 0.9 to 1.1 times extends in the column axial direction by 2 to 10 times the plate thickness of the plate material.

3. The cylindrical structure according to claim 1 , wherein the column axis direction welds of the respective plate materials connected in the column axis direction are arranged discontinuously in the column axis direction.

4. the column axis direction welds of the plate materials connected in the column axis direction are configured to be continuously arranged in the column axis direction, The cylindrical structure according to claim 1 , wherein the circumferential welds of the plate members connected in the circumferential direction are arranged continuously in the circumferential direction.

5. The tubular structure according to claim 3 or 4, wherein the tubular structure is cylindrical.

6. The tubular structure of claim 4 , wherein the tubular structure is polygonal.

7. The cylindrical structure according to claim 5 , wherein the rolling direction of the plate material is the circumferential direction.

8. The cylindrical structure according to claim 6 , wherein the rolling direction of the plate material is the column axis direction.

9. a penetration amount change portion formed at an intersection of the circumferential weld portion and the column axis direction weld portion; a peening portion at a toe where the column axial weld portion and the penetration amount changed portion intersect; The cylindrical structure of claim 1 , having:

10. The cylindrical structure according to claim 9 , wherein the peening portion is formed on one of an inner surface side or an outer surface side of the cylindrical structure, or on both the inner surface side and the outer surface side of the cylindrical structure.

Images