Reinforced pipe manufacturing method

Abstract

A method for manufacturing a reinforced pipe (10), comprising the steps of: providing a first metal plate (1) having a thickness t; bending the first metal plate (1) along a bend line to form a helix (30), the pitch of the helix (30) being approximately equal to the width of the plate, and two consecutive turns of the helix (30) meeting at a seam (20); welding the helix along the seam (20) to form a pipe; and welding one or more first metal stiffening elements (2) to the pipe to form the reinforced pipe (10).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a reinforced pipe. [Background technology]

[0002] The offshore floating wind industry is growing. New wind turbine designs are being developed with increasing sizes. Therefore, there is a need to efficiently provide new lightweight, strong buoyancy tanks to produce floating structures with sufficient buoyancy at the lowest possible cost.

[0003] The present invention relates to a method for making cylinders, and more particularly to a method for making ring-stiffened cylinders that can be used as buoyancy members in offshore floating wind turbine structures or other large diameter thin shell structures. One solution has been to reduce the wall thickness to reduce the weight of the steel, thereby reducing the cost of the floating offshore structure.

[0004] Conventional techniques for fabricating ring-stiffened structures involve bending metal plates to form structures such as pipes and then welding ring elements to the inside of the pipes. For structures with relatively large diameter-to-wall-thickness ratios, such as pipes, this method has been fraught with problems related to buckling during bending due to the plate's own weight. This is true even when spiral welding of pipes using conventional techniques is used as the fabrication method. Furthermore, welding the plates to the ring-stiffening elements after they have been bent is costly because it requires extra handling during the fabrication of the stiffened shell. One solution to this problem has been to design flat-plate buoyancy members instead of circular cylinders. Flat-plate structures can be easily stiffened with T-beams by welding the T-beams to the hull plates when the plates are in a flat position on the floor. This is a well-known manufacturing method in the shipbuilding industry. Therefore, flat-plate stiffened panels are less expensive to produce per kilogram of steel than circular stiffened panels. However, flat panel buoyancy members have higher hydrodynamic excitation forces and therefore more steel is required for the same wind turbine carrying a floating foundation.

[0005] Therefore, to alleviate the problems of existing methods for fabricating stiffened thin-walled shells, new production methods are being developed. Summary of the Invention

[0006] The invention is defined by the appended claims and the following: In a first aspect, the present invention provides a method for manufacturing a reinforced pipe, comprising: a) providing a first metal plate having a thickness t; b) bending the first metal plate along a bend line to form a spiral; the pitch of the spiral is approximately equal to the width of the plate; two successive turns of the spiral meeting at a seam; c) welding the spiral along the seam to form a pipe; and d) welding one or more first metal stiffening elements to the pipe to form a reinforced pipe.

[0007] Those skilled in the art will appreciate that bending may be accomplished using any bending machine known in the art, and all production steps may advantageously be accomplished without the need to remove the plate, pipe, or reinforcing pipe from the bending machine.

[0008] Those skilled in the art will understand that the term "approximately equal" herein means "equal to a margin of 10%." In other words, the pitch of the helix is comprised between 90% and 110% of the width of the plate.

[0009] In one embodiment, the pitch of the helix is between 95% and 105%, between 90% and 110%, between 100% and 110%, between 100% and 105%, between 95% and 100%, between 100% and 102%, or between 100% and 101% of the width of the plate.

[0010] In one embodiment of the method, the reinforcing pipe has a diameter D and the ratio D / t may be 100 or greater, 150 or greater, 200 or greater, 250 or greater, 300 or greater, or 500 or greater. In one embodiment, the ratio D / t may be comprised between 100 and 1500, preferably between 200 and 800.

[0011] In one embodiment, in step c), the spiral is welded along a seam within 400° of the bend line (the line on the metal plate along which the metal plate is bent), and the angle α is defined between a first radius of the spiral (starting from the bend line, along which the metal plate is bent) and a second radius of the spiral starting from the weld point.

[0012] In one embodiment, in step c), the spiral is welded along the seam within 360°, within 270°, within 180°, within 135°, within 90°, within 60°, within 45°, within 30°, within 10°, or within 5° of the bend line.

[0013] In one embodiment, in step d), one or more first metal stiffening elements are welded within 400° of the bend line (i.e., the line on the metal plate along which the metal plate is bent), and an angle β is defined between a first radius of the spiral (starting from the bend line, along which the metal plate is bent) and a second radius of the spiral starting from the weld point.

[0014] In one embodiment, in step d), the one or more first metal stiffening elements are welded within 360°, within 270°, within 180°, within 135°, within 90°, within 60°, within 45°, within 30°, within 10°, or within 5° of the bend line.

[0015] In one embodiment, the one or more first metal stiffening elements for the pipe are not bent together with the first metal plate. In one embodiment, one or more first metal stiffening elements for the pipe are bent together with the first metal plate.

[0016] In one embodiment, the thickness t may be 50 mm or less, 40 mm or less, 30 mm or less, 25 mm or less, 20 mm or less, 15 mm or less, or 10 mm or less. In one embodiment, the thickness t may be comprised between 10 mm and 500 mm, preferably between 15 mm and 200 mm.

[0017] In one embodiment, the diameter D may be comprised between 5 m and 50 m, preferably between 8 m and 30 m. In one embodiment, the width of the metal plate is 10 times, 20 times, 50 times, 100 times, 500 times, 1000 times the width of the first metal stiffening element.

[0018] In one embodiment, the welding step d) may comprise welding two or more, three or more, four or more, five or more, or ten or more first metal stiffening elements onto the first metal plate.

[0019] In one embodiment, the welding step d) may include welding two or more first metal stiffening elements onto the first metal plate, wherein the two or more first metal stiffening elements are parallel to each other.

[0020] In one embodiment, the two or more first metal stiffening elements are parallel and the distance between the two or more first metal stiffening elements is between 1 / 50 and 1 / 4 of the pipe diameter D, preferably between 1 / 30 and 1 / 6 of the pipe diameter D.

[0021] In one embodiment, the one or more first metal stiffening elements are spirals having a diameter equal to the inner diameter of the reinforcing pipe, or the one or more first metal stiffening elements are spirals having an inner diameter equal to the outer diameter of the reinforcing pipe.

[0022] In one embodiment, the one or more first metal stiffening elements are circular with a diameter equal to the inner diameter of the reinforcing pipe, or the one or more first metal stiffening elements are circular with an inner diameter equal to the outer diameter of the reinforcing pipe, In one embodiment, the one or more first metal stiffening elements form a circle or a sector, such as a semicircle or a quarter circle.

[0023] In one embodiment, steps b) and d) may be performed simultaneously. In other words, the bending step is realized by a bending machine, and the welding of the one or more first metal stiffening elements is achieved without removing the metal plate or the formed pipe from the bending machine. Steps b) and d) may both be achieved continuously and simultaneously, or may be intermittent by performing a series of partial steps b) and d).

[0024] In one embodiment, the method may further comprise welding one or more lower web members to the first metal plate, and the one or more first metal stiffening elements may be positioned and welded on top of the one or more lower web members.

[0025] In one embodiment, the method e) welding one or more second metal stiffening elements onto the first metal plate at an angle to the one or more first metal stiffening elements.

[0026] In one embodiment, the one or more second metal stiffening elements are perpendicular to the one or more first metal stiffening elements. In one embodiment, the welding step e) may include welding two or more, three or more, four or more, five or more, or ten or more second metal stiffening elements onto the first metal plate.

[0027] In one embodiment, the welding step e) may include welding one or more metal stiffening elements onto the first metal plate to form a complete turn after the first metal plate has been bent 400° or more using the bending machine without removing the pipe section from the pipe bending machine, so that the metal plate is structurally supported against collapse during the bending operation by the adjacent portion of the finished pipe on which the metal stiffening elements are installed.

[0028] In one embodiment, the method may comprise bending the first metal plate to form two or more turns of the spiral. In one embodiment, the reinforcing pipe may be a cylinder or tapered cylinder with a generally circular or oval base.

[0029] In one embodiment, the reinforcing pipe may be a cylinder or a tapered cylinder with a substantially circular base, the base having an ellipticity coefficient of less than 10%, 5%, 2%, or 1%, where the ellipticity coefficient is defined herein as the ratio of the longest diameter of the base divided by the smallest diameter of the base.

[0030] In one embodiment, the first metal plate may have a yield strength of 200 MPa or greater, 250 MPa or greater, 300 MPa or greater, or 400 MPa or greater. In one embodiment, the first metal plate may be made of steel, a steel alloy, aluminum, or an aluminum alloy.

[0031] In one embodiment, the one or more first stiffening elements may be a plate, a T-beam or a U-beam. In one embodiment, the one or more first stiffening elements may be made of steel, a steel alloy, aluminum or an aluminum alloy.

[0032] In one embodiment, the one or more second stiffening elements may be made of steel, a steel alloy, aluminum or an aluminum alloy. In one embodiment, the one or more first stiffening elements and the first metal plate are made of the same material.

[0033] In one embodiment, the one or more second stiffening elements and the first metal plate are made of the same material. In one embodiment, the ratio of the structural capacity of the reinforcing pipe to the structural capacity of the first metal plate may be 5 or more, preferably 10 or more.

[0034] In one embodiment, the one or more first stiffening elements may be oriented on the first metal plate such that when the cylinder is formed, the one or more first stiffening elements form a ring along the inner circumference of the cylinder.

[0035] In one embodiment, one or more second stiffening elements are welded orthogonally to one or more first stiffening elements. In one embodiment, the method further comprises welding a second metal plate onto the one or more first metal stiffening elements, the second metal plate being parallel to the first metal plate.

[0036] In one embodiment, the second metal plate may be made of steel, a steel alloy, aluminum, or an aluminum alloy. In a second aspect, the present application provides a reinforced pipe, comprising: - a first metal pipe having a base with a thickness t and a diameter D; - one or more first metal stiffening elements welded to the inner surface of the reinforcing pipe; A reinforced pipe is described in which the ratio D / t is greater than 100.

[0037] In one embodiment of the second aspect, the ratio D / t may be between 100 and 1500, preferably between 200 and 800. In a third aspect, the present application describes a bending machine for making a reinforced pipe, the reinforced pipe comprising a metal pipe having a base with a thickness t and a diameter D, and one or more first metal stiffening elements welded to an inner surface along a circumference of the metal pipe; The bending machine comprises an inner roller and two outer rollers, the outer surface of the inner roller or the outer rollers comprising one or more first grooves for accommodating one or more first metal stiffening elements.

[0038] In an embodiment of the third aspect, the ratio D / t is 100 or greater. In one embodiment of the third aspect, the one or more first grooves have a depth at least equal to a height of the one or more first metal stiffening elements.

[0039] In one embodiment of the third aspect, the one or more first grooves may have a depth approximately equal to a height of the one or more first metal stiffening elements. In one embodiment, the bending machine may further comprise means for welding one or more first metal stiffening elements to the metal pipe, such as a welding arm.

[0040] In one embodiment, the bending machine may further include two or more spacers, which are objects that may be positioned on each side of the one or more first stiffening elements and between the first metal plate and the inner roller.

[0041] In one embodiment, each spacer may comprise a vertically acting spacer roller, which transfers the pressure of the inner roller to the first metal plate 1. In one embodiment, each spacer may comprise a laterally acting spacer roller positioned on each side of the one or more first stiffening elements, preferably in contact with the one or more first stiffening elements, and applying sufficient pressure to the one or more first stiffening elements to prevent the one or more first stiffening elements from buckling.

[0042] In one embodiment, each spacer may comprise two laterally acting spacer rollers. In one embodiment, each spacer may be freestanding, i.e., each spacer does not need to be attached to another structure.

[0043] In one embodiment, the bending machine may further comprise support rollers that support the formed reinforced pipe, further helping to prevent buckling or bending of the helix, pipe, or reinforced pipe under its own weight.

[0044] In one embodiment, the support rollers may be adjustable in height and position, which advantageously allows for correcting the orientation of the longitudinal axis of the reinforced pipe during its production / operation of the bending machine.

[0045] In one embodiment, the bending machine may include two support rollers. In one embodiment, a series of vertical rollers may be spaced apart along a bending axis on a roller arm member to create a helical pipe in a bending machine. The bending machine may also include side rollers for supporting a first metal stiffening element during plastic bending of the first metal stiffening element in the bending machine. The series of vertical rollers may be oriented with a rotation axis approximately perpendicular to a feed angle of a first metal plate into the bending machine to create a reinforced pipe.

[0046] In one embodiment, a series of first metal stiffening elements may be welded to a first metal plate at an angle perpendicular to the longitudinal axis of the resulting helical pipe. The metal plate with the metal stiffening elements may then be fed into a bending machine during the production of the reinforced helical pipe. The bending machine may include a helical inner roller that can ensure contact pressure on both the first metal plate and the first metal stiffening elements, while preventing the first metal stiffening elements from colliding with the rollers in the bending machine during the continuous production of the helical pipe.

[0047] In one embodiment, the orientation of the inner and outer rollers may be adjustable relative to the longitudinal axis of the reinforced pipe during operation of the bending machine, which advantageously allows for the orientation of the longitudinal axis of the reinforced pipe to be modified during production.

[0048] In one embodiment, the first groove of the inner roller of the bending machine may be a spiral groove. In one embodiment, the inner roller may comprise a series of inner and side rollers arranged on an inner roller support arm, or the outer roller may comprise a series of outer and side rollers arranged on an outer roller support arm.

[0049] In the following description, the invention is further explained by means of exemplary embodiments shown in the drawings. [Brief explanation of the drawings]

[0050] [Figure 1a] FIG. 10 is a side view of an embodiment of a reinforcing metal plate. [Figure 1b] 1 is a perspective view of an embodiment of a reinforcing metal plate. [Figure 2a] FIG. 10 is a side view of an embodiment of a reinforcing metal plate welded to a second metal plate. [Figure 2b] FIG. 10 is a perspective view of an embodiment of a reinforcing metal plate welded to a second metal plate. [Figure 3] 10A and 10B are side views of the first metal plate and the first metal stiffening element during bending and subsequent welding of the first metal stiffening element at an angle β. [Figure 4] 1 is a perspective view of an embodiment of a reinforcing metal plate being spirally bent and subsequent seam welding. [Figure 5] 10 is a side view of an embodiment of a reinforcing metal plate being bent into a spiral and subsequent seam welding at an angle α. FIG. [Figure 6] 1 is a perspective view of a first embodiment of a bending machine; [Figure 7] FIG. 10 is a perspective view of a second embodiment of a bending machine. [Figure 8] 1 is a perspective view of an embodiment of a first metal plate being spirally bent and subsequent seam welding. [Figure 9] 1 is a perspective view of a series of first metal stiffening elements welded to a first metal plate having a first embodiment of a spacer; FIG. [Figure 10] 10 is a perspective view of a series of first metal stiffening elements welded to a first metal plate having a second embodiment of a spacer. FIG. [Figure 11] FIG. 10 is a front view of a bending machine equipped with a spacer. [Figure 12] 1 is a perspective view of a series of first metal stiffening elements and a first metal plate passing through a bending machine with spacers. [Figure 13] Detail view of a series of first metal stiffening elements and a first metal plate passing through a bending machine with spacers. [Figure 14] Detail view of a series of first metal stiffening elements and a first metal plate passing through a bending machine comprising a series of vertical and lateral rollers arranged on inner roller support arms. [Figure 15] 1 is a top view of an embodiment having a series of first metal stiffening elements longitudinally welded to a first metal plate fed into the bending machine at a feed angle. Each inner roller is positioned on an inner roller support arm having an axis of rotation disposed at an angle δ (delta) relative to the longitudinal axis of the helix. [Figure 16]1 is a top view of an embodiment having a series of first metal stiffening elements welded to a first metal plate 1 at an angle perpendicular to the longitudinal axis of the helix. The metal plate is fed into a bending machine with a helical shaped inner roller. [Figure 17] A perspective view of a flat plate that is bent into a spiral and welded with other elements to form a reinforcing pipe. DETAILED DESCRIPTION OF THE INVENTION

[0051] In the design of offshore floating wind farms, reducing the weight of materials is essential to ensure the low cost of the energy produced, while at the same time the structure must maintain its strength to withstand the mechanical stresses of the environment.

[0052] Therefore, new structures, particularly buoyancy tanks, have been developed with higher pipe diameter to wall thickness ratios. For example, it is not uncommon to use buoyancy tanks with diameters exceeding 11 m and wall thicknesses of only about 20 mm.

[0053] For pipes with a relatively high pipe diameter to wall thickness ratio, conventional production methods have been fraught with problems related to buckling of the plates during bending due to gravity acting on the plates. Furthermore, welding the rings after forming the complete pipe is a complex, time-consuming and expensive operation.

[0054] Therefore, new production methods are being developed to alleviate the problems of existing methods. The conventional technique for producing reinforced pipe sectors or pipes involves first bending a metal plate, then forming the pipe, and then welding metal stiffening elements onto the formed cylinder.

[0055] Those skilled in the art will now appreciate that this method may be used to form pipes such as cylinders and tapered cylinders. A tapered cylinder is equivalent to a truncated cone. The method may also be adapted to form partial cylinders or partial tapered cylinders.

[0056] Those skilled in the art will also appreciate that any type of welding may be used here, including tack welding before the final welding is performed at a later stage. Examples of such a method are shown for example in Figures 5 and 8. Details and alternatives are shown in the other figures. In detail, the method of the invention proposes bending a metal plate 1 along a bend line to form a spiral, the pitch of the spiral being approximately equal to the width of the plate, two consecutive turns of the spiral being in contact (or being arranged in contact) at a seam 20, welding the spiral 30 along the seam 20 to form a pipe, and welding one or more first metal stiffening elements to the pipe to form a reinforced pipe 10.

[0057] Now, those skilled in the art will understand that the one or more stiffening elements 2 may typically be any stiffening element traditionally used in the oil and gas industry, in particular beams such as T-beams and U-beams.

[0058] Thanks to the method of the invention, the metal plate 1 is able to support its own weight during the bending process and the risk of buckling is at least reduced or even eliminated. Furthermore, the method allows for a continuous process for making reinforced pipe 10, and in particular for making complete reinforced pipe, i.e. pipe of any desired length.

[0059] Here, it is possible both to bend one or more stiffening elements 2 together with the first metal plate 1 or to place one or more stiffening elements 2 on the first metal plate 1 after bending them.

[0060] It is also possible to weld one or more stiffening elements 2 to the first metal plate before (when one or more stiffening elements 2 are present) or after the bending process. First Example In the first step, a series of parallel stiffening elements 2, here T-beams, are first welded to a flat plate 1 to form a stiffened flat plate 3, as shown in Figures 1a and 1b. The stiffened flat plate 3 then passes through a bending machine 50 to form a helical stiffened pipe or helix 30, with the T-beams also forming a helix. The seam 20 of the helix 30 is welded, for example, at an angle α of 10° from the bend line, i.e., the line on the metal plate along which the metal plate is bent, using a welding arm 59, as shown in Figures 4 and 5. Here, angle α is defined as the angle between the first radius of the helix along which the metal plate is bent, starting from the starting point (or bend line), and the second radius of the helix, starting from the weld point. The formed helix is supported by one or more support rollers 70.

[0061] Second Example In a first step, a series of stiffening elements 2, here shear webs, are welded to a first flat aluminum plate 1 and then to a second aluminum plate 5, so that the shear webs are contained between both the first plate 1 and the second aluminum plate 5, and the first aluminum plate 1 and the second aluminum plate 5 are parallel. This creates a double flat deck (or double hull deck) as shown in Figures 2a and 2b. The double flat deck then passes through a bending machine to form a helical stiffening pipe or helix 30. The seam 20 of the helix 30 is welded, for example, using a welding arm, at a 45° angle α of the bend line.

[0062] Third Example In a first step, a series of parallel first stiffening elements 2, here T-beams, were welded to a flat plate 1. Orthogonal to the series of first stiffening elements 2, a series of parallel second stiffening elements 4, here also T-beams, were welded to the flat plate 1 perpendicular to the first stiffening elements 2 to form a stiffened metal plate 3.

[0063] The reinforcing metal plate 3 then passes through a bending machine 50 to form a helical stiffened pipe or helix 30. The seam 20 of the helix 30 is welded, for example using a welding arm, at an angle α of 45° to the bend line.

[0064] Fourth Example In a fourth embodiment, a series of first stiffening elements 2 are placed (without welding) on a metal plate 1. The metal plate 1 and stiffening elements 2 then pass through a bending machine 50 to form a helical stiffened pipe or helix 30. The seam 20 of the helix 30 is welded, or at least tack-welded, at an angle α of 10° from the bend line, for example, using a welding arm. The series of first stiffening elements 2 are welded immediately after the plate 1 is bent (in other words, the welding occurs shortly after or at the point where the plate is plastically bent), as shown in FIG. 3. In other words, a second angle β is formed from the bend line, i.e., the line on the metal plate along which the metal plate is bent, and the angle β is defined between the radius of the circle along which the metal plate is bent starting from the bend line and the second radius of the circle along which the metal plate is bent starting from the weld point (of the metal stiffener 2). Here (FIG. 3), the bend line angle β is approximately 85°. In submerged arc welding, the optimum welding position is vertically downward, therefore the preferred angle α is close to 0, 360, or 720 degrees, etc., for welding from the inside of the pipe, and 180, 540 degrees, etc., for welding from the outside of the pipe. In this example, the main weld of seam 20 is made from the inside with an α of about 10 degrees, and the back weld of seam 20, which is a smaller weld to avoid root defects in the finished weld, is made from the outside at an β of 180 degrees.

[0065] In this embodiment, the seam is welded first and then the first stiffening element 2 is welded, i.e. α<β. It is also possible that α=β or α>β. Fifth Example In the first step, a single stiffening element 2, here a U-beam, is first welded to a flat plate 1 to form a stiffening metal plate 3. The stiffening metal plate then passes through a bending machine 50 to form a spiral stiffening pipe. After forming a pipe of appropriate dimensions, here a pipe 10 m in diameter, 25 mm thick, and 40 m long, for example, the ends are cut so that the pipe has a cylindrical shape.

[0066] Here, the distance between the two first metal stiffening elements 2 may typically be 500 to 2000 mm. Sixth Example In the first step, the metal plate 1 passes through the bending machine 50 to form a helical pipe or helix 30. After the first turn, the seam 20 of the helix 30 is welded at a 10° angle α of the bend line, for example, using a welding arm. One or more metal stiffening elements 2 are independently fabricated to form a complete or nearly complete circle and are positioned laterally relative to the sides of the rollers 51, 52 inside the welding machine 50, as shown in FIG. 8. One or more first metal stiffening elements 2 are then welded onto the first helix 30 after the first metal plate 1 has been bent 360 degrees or more using the bending machine, i.e., from the second turn, thus forming the reinforced pipe 10. In other words, the formed pipe section is still, at least partially, in the bending machine 50. Thus, the bent metal plate 1 is structurally supported against collapse during the bending operation by the adjacent portions of the completed helical pipe section on which the metal stiffening elements are installed, as shown in FIG. 8.

[0067] Seventh Example In a seventh embodiment, as shown in FIG. 13, a series of lower web members 64 are welded to the metal plate 1, and a series of first stiffening elements 2 are placed on top of the web members 64 (without welding). Next, as shown in FIG. 3, the metal plate 1 with the web members 64 and stiffening elements 2 passes through the bending machine 50 and is welded to each other at the intersections 63 immediately after the plate 1 with the lower web members 64 and stiffening elements 2 is bent (in other words, the welding occurs shortly after the plate 1 with the lower web members 64 and stiffening elements 2 is plastically bent). In other words, welding the stiffening elements 2, which in this example have a reduced web height, at the bend line angle β to the plate 1 with the lower portion of the lower web membrane 64 after plastic bending further reduces the combined bending stiffness of the metal plate 1 and the stiffening elements 2 during the bending operation, thus reducing the total required bending force and the risk of buckling of the stiffening elements during the bending operation, as well as reducing the post-bending plastic (and permanent) strain in the bent material. High plastic strain levels can cause the material to initiate microcracks and thus reduce the fatigue strength of the bent material, and are therefore desirably reduced as much as possible during fabrication.

[0068] Eighth Example 17, in an eighth embodiment, a flat plate 1 passes through a bending machine 50 to form a helical pipe or helix 30. Furthermore, one or more stiffening elements 2 are independently manufactured or bent to form an arc, a complete circle, a nearly complete circle or a helix (as shown in FIG. 17) and placed on the outer surface area of the helical pipe or helix 30. One or more stiffening elements 2 are then welded onto the outer surface area of the first helix 30 after the flat plate 1 has been bent 360 degrees or more using the bending machine 50, i.e. from the second turn, thus forming the reinforced pipe 10.

[0069] An advantage of having stiffening elements 2 on the outer surface area of the formed reinforcing pipe 10 is that a second metal plate 5 can be bent independently and more easily welded onto the stiffening elements 2 to create a double flat deck (or double hull deck) which further strengthens the reinforcing pipe 10.

[0070] Ninth Example In the ninth embodiment, a helical reinforcing pipe or helix 30 is prepared as in the eighth embodiment. Afterwards, a second metal plate 5 is bent and then welded to the stiffening elements 2 formed on the outer surface area of the helical reinforcing pipe or helix 10 to form a double deck (or double hull deck).

[0071] Regardless of the embodiment, when two or more first metal stiffening elements 2 are arranged on the first metal plate 1, the two or more first metal stiffening elements 2 are advantageously parallel, and the distance between the two or more first metal stiffening elements 2 is between 1 / 50 and 1 / 4 of the pipe bend diameter D, preferably between 1 / 30 and 1 / 6 of the pipe bend diameter D.

[0072] In the same vein, when the one or more first metal stiffening elements 2 are helical, the pitch of said helix is between 1 / 50 and 1 / 4 of the pipe bend diameter D, preferably between 1 / 30 and 1 / 6 of the pipe bend diameter D.

[0073] These sections can then be later attached and welded together to form longer cylindrical or tapered cylindrical sections. Those skilled in the art will appreciate that for the first and last sections of the reinforced pipe 10, it is possible to cut the metal plate before the bending operation so that the pipe ends exit the bending machine without having to cut the metal plate after the bending operation to make the cylinder ends perpendicular to the longitudinal axis of the pipe.

[0074] Bending machine In one example, the bending machine 50 includes a pair of outer rollers 52 and an inner roller 51 .

[0075] The bending machine may further include a welding arm 59, as shown in Figures 4 and 5. The welding arm may be used to weld the spiral 30 along the seam 20. As shown in Figures 6 and 7, in this bending machine 50 the inner rollers 51 are configured to bend the metal plate 1 and the stiffening elements 2 simultaneously and before the metal plate 1 and the stiffening elements 2 are welded together, or in the bending machine 50 the inner rollers 51 are configured to bend the reinforced bending plate 3, i.e. the metal plate 1 welded to one or more first stiffening elements 2.

[0076] Instead of being flat, the inner roller 51 is a cylinder (or a tapered cylinder) that includes one or more first grooves 55 for accommodating the one or more first stiffening elements 2. The depth of the one or more first grooves 55 is preferably equal to the height of the one or more first stiffening elements 2. In this way, the force applied by the inner roller 51 is distributed over both the metal plate 1 and the one or more first stiffening elements 2, rather than just the one or more first stiffening elements 2, thereby reducing the risk of buckling in the one or more first stiffening elements 2.

[0077] One or more first grooves 55 are arranged circumferentially around the inner roller 51 . The inner roller 51 may be a solid piece, or alternatively may be a cylinder covered by a series of discs.

[0078] It will be appreciated that when forming a spiral stiffening pipe or helix 30 in which stiffening elements 2 are molded onto its outer surface area, such as in Examples 8, 9, and 10 above, the one or more first grooves 55 need to be arranged on the outer roller 52 rather than the inner roller 51 so as to accommodate the one or more first stiffening elements 2.

[0079] 7 , when the reinforcing plate 3 comprises one or more first stiffening elements 2 and one or more second stiffening elements 4 perpendicular to the one or more first stiffening elements 2, the inner cylinder 51 comprises one or more first grooves 55 for accommodating the one or more first stiffening elements 2 and one or more second grooves 56 for accommodating the one or more second stiffening elements 4. The depth of the one or more first grooves 55 and the one or more second grooves 56 is preferably equal to the height of the one or more first stiffening elements 2 and the one or more second stiffening elements 4, respectively. In this way, the force applied by the inner roller 51 is distributed not only to the one or more first stiffening elements 2 and / or the one or more second stiffening elements 4 but also to both the metal plate 1, the one or more first stiffening elements 2, and the one or more second stiffening elements 4, thereby reducing the risk of buckling in the one or more first stiffening elements 2 and / or the one or more second stiffening elements 4.

[0080] One or more first grooves 55 are circumferentially disposed around the inner cylinder (or tapered inner cylinder). One or more second grooves 56 are longitudinally disposed along the outer surface of the inner roller 51.

[0081] The bending machine 50 may advantageously be mounted so that the central axis of the inner roller is perpendicular or parallel to the axis of gravity. In this embodiment, the metal plate 1 wraps around the inner roller 51 during the creation of the helix. Therefore, the outer roller 51 must be lifted in order to move the helix 30 along its longitudinal axis. Therefore, in this embodiment, the creation of the helically reinforced pipe must be carried out in stages.

[0082] It will be appreciated that when forming a helical stiffening pipe or helix 30 in which stiffening elements 2 are molded on its outer surface area, such as in Examples 8, 9, and 10 above, the one or more first grooves 55 and one or more second grooves 56 need to be arranged on the outer roller 52 rather than the inner roller 51 so as to accommodate the one or more first stiffening elements 2 and one or more second stiffening elements 4.

[0083] A second embodiment of the bending machine 50 avoids the drawbacks of producing the spiral reinforced pipe 30 in stages. In this embodiment, the bending machine is configured similarly to the above, with the difference that the groove on the inner roller 51 is a spiral groove, so that the metal plate 1 does not wrap around the inner roller 51 during the continuous production of the spiral. Here, the spiral groove is arranged by a pitch determined by the diameter of the roller, the distance between each stiffening element 2, and the feed angle 76. In this way, the stiffening elements 2 do not collide with the spiral groove during the continuous production of the spiral pipe 30. As shown in FIG. 16 , by arranging the stiffening elements 2 perpendicular to the longitudinal axis of the produced spiral pipe 30 and setting the distance between each stiffening element 2 equal to the circumference of the spiral pipe 30 divided by a positive integer, it is possible to produce a reinforced pipe 10 by the spiral welding method and further have individual stiffening elements 2 spaced perpendicularly inside the pipe. That is, in this embodiment, the stiffening elements 2 are not helical in shape, but are closed circles spaced apart perpendicular to the longitudinal axis of the helical pipe 30 .

[0084] In the third embodiment of the bending machine 50, the bending machine is arranged similarly to that described in the first embodiment of the bending machine 50 above, but the inner roller 51 comprises a series of inner rollers 61 and side rollers 62 arranged on an inner roller support arm 73, as shown in FIG. 14. As shown in FIG. 15, a series of first metal stiffening elements 2 longitudinally welded to a first metal plate 1 are fed into the bending machine 50 at a feed angle 76. The individual inner rollers 61 are arranged on the inner roller support arm 73 spaced apart along a bending line that is generally parallel to the longitudinal axis 77 of the helix 30. The individual inner rollers 61 are further arranged on the inner roller support arm 73 with a generally horizontal axis of rotation that is arranged at an angle δ (delta) relative to the longitudinal axis 77 of the helix 30. The rotation angle δ (delta) can be configured to be self-adjusting (similar to the wheels of a supermarket cart) so as to allow the metal plate 1 to be fed freely into the bending machine that forms the spiral 30 without resisting forward motion along the axis 77 during the creation of said spiral 30.

[0085] As shown in Figure 14, lateral spacers comprising lateral rollers 62 are arranged on the inner rollers 61 to support one or more first metal stiffening elements 2 during the plastic bending of said first metal stiffening elements 2. To ensure the stability of the rollers, two or more lateral rollers 62 are arranged on each side of each of the inner rollers 61.

[0086] When forming a helical stiffening pipe or helix 30 in which the stiffening element 2 is molded on its outer surface area, such as in Examples 8, 9 and 10 above, it is understood that it is the outer roller 52 that comprises a series of outer rollers and lateral rollers arranged on the outer roller support arms.

[0087] When manufacturing a helical pipe according to the present invention, the pipe diameter D may vary slightly during the proposed process if the pipe is long. It may also be desirable to transition from a straight section to a conical section during the manufacturing of the pipe. To control the pipe diameter D, if the pipe is manufactured horizontally as shown in the figure, the central longitudinal axes of both the inner and outer rollers are adjusted relative to the longitudinal axis of the pipe. By tilting the rollers 51, 52 relative to each other about a horizontal axis disposed perpendicular to the longitudinal axis of the pipe, the distal ends of the rollers (thus facing away from the cylinder being manufactured) are raised (thereby moving closer to the central axis of the pipe 10), and the pipe diameter D is reduced by coning the pipe inward as the bending operation continues. To increase the pipe diameter D, the rollers 51, 52 are tilted in the opposite direction. Because the key feature for controlling diameter D is the position of the central axis between the rollers 51, 52 relative to the longitudinal axis of the pipe 10, this relative adjustment can be performed by tilting the inner / outer rollers or by tilting the pipe 10 by adjusting the height of the pipe support rollers 70. Adjustment of the pipe support rollers can be performed by jacking up or down these supports. Jacking up to tilt the pipe begins to reduce the diameter D of the pipe as it is rolled and welded to the rest of the pipe. Jacking down to tilt the pipe increases the diameter D as it is rolled and welded to the rest of the pipe.

[0088] When adjusting the pipe diameter D, the pitch of each spiral must also be adjusted by adjusting the feed angle 76 of the metal plate 1 entering the bending machine 50. Thus, the diameter D depends on the pitch and feed angle of the spiral.

[0089] When bending a metal plate 1 having stiffening elements 2, there is a risk that the stiffening elements may buckle. One approach to reduce the risk of buckling is to increase the width between the two outer rollers 52 to increase the effective bending arm and therefore reduce the required force of the rollers 51, 52 required to plastically bend the plate 1 having stiffening elements 2.

[0090] In other words, in order to reduce the force applied to the plate 1 with the welded stiffening elements 2, the space between the outer rollers 52 of the bending machine 50 may be increased. Another alternative to reduce the risk of buckling is to use two or more spacers 60. Spacers are objects that can be placed on each side of one or more first stiffening elements 2 and between the first metal plate 1 and the inner roller 51, as shown in Figures 9 and 10. Preferably, these two or more spacers 60 cover the width of the first metal plate 1 along the bend line, and even more preferably, cover each side of the bend line wherever the inner roller contacts the first metal plate and one or more first stiffening elements.

[0091] There may be multiple spacers of different widths depending on the number of first stiffening elements 2 and their arrangement on the first metal plate 1. In other words, the width of the spacer 60 is the distance between two stiffening elements 2 or between a stiffening element 2 and a side of the first metal plate 1.

[0092] Preferably, each of the one or more first stiffening elements 2 is comprised between two or more spacers, whereby the spacers are intended to prevent buckling during the bending step c). The two or more spacers 60 may be of any suitable shape that complements the shape of the one or more first stiffening elements 2, for example, the cross section of the shape of the two or more spacers 60 and the shape of the first stiffening element 2 may be approximately rectangular with approximately the same width as the first metal plate 1 and approximately the same height as the one or more first stiffening elements 2, as shown in Figures 9 and 10.

[0093] When the one or more first stiffening elements 2 are T-beams or U-beams, the two or more spacers 60 may be rectangular parallelepipeds. Two or more spacers 60 may be freestanding, i.e., the spacers 60 do not need to be attached to a support structure or the like.

[0094] Preferably, the two or more spacers 60 may comprise vertically acting spacer rollers 61 that transmit the pressure of the inner rollers 51 to the first metal plate 1, as shown in Figures 11 and 12 .

[0095] Preferably, the two or more spacers 60 may further comprise spacer rollers 62 acting in a lateral direction to prevent the one or more first stiffening elements 2 from buckling. Each roller 61, 62 may rotate freely or may have a motor driving it.

[0096] It is understood that separate drive rollers, such as those used in known techniques for helical welding of pipe, may be used with the present invention, as well as any other features known to those skilled in the art of helical welding of pipe.

[0097] If the one or more first stiffening elements 2 are T-beams, the two or more spacers 60 are designed to avoid buckling of all parts of the T-beam, i.e., both the shear web and the flanges, as in the above examples using rollers (Figures 10, 11 or 12) or rectangular prisms (Figure 9).

[0098] It will be appreciated that when forming a spiral stiffening pipe or helix 30 in which the stiffening element 2 is molded on its outer surface area, such as in Examples 8, 9 and 10 above, two or more spacers 60 are preferably arranged on each side of the one or more first stiffening elements 2 and between the first metal plate 1 and the outer roller 52.

[0099] The bending machine 50 is not always able to apply a bending moment to the end of the article being bent, and therefore is unable to permanently and plastically bend that very end. For this reason, when bending a metal plate 1, the end of the metal plate 1 is often left unbent. Typically, the unbent end of the plate 1 is cut off before the plate is welded together to form a pipe, such as a cylinder.

[0100] To further improve this method, one or both ends of the metal plate 1 may be bent in a first step before placing the stiffening elements 2 on the plate. Furthermore, one or more stiffening elements 2 may be shaped or cut at one or both ends so that the one or more stiffening elements 2 can be easily placed on the plate 1 (with one or both ends bent).

[0101] Thus, since the plate 1 and stiffening element 2 and their respective end sections have approximately the same curvature after passing through the bending machine and therefore form approximately circular sections, the metal plate 1 has ski-tip shaped ends that do not need to be plastically bent to become part of the final circular or approximately circular shape of the produced pipe section.

Claims

1. A method for manufacturing a reinforced pipe (10), comprising: a) providing a first metal plate (1) having a thickness t; b) bending the first metal plate (1) along a bend line to form a spiral (30); The pitch of the spiral (30) is approximately equal to the width of the plate; two successive turns of said spiral (30) meeting at a seam (20); c) welding said spiral along said seam (20) to form a pipe; d) welding one or more first metal stiffening elements (2) to said pipe to form a reinforced pipe (10).

2. 2. The method according to claim 1, wherein the reinforcing pipe has a diameter D and the ratio D / t is comprised between 100 and 1500, preferably between 200 and 800.

3. 3. The method of claim 1 or 2, wherein in step c) the spiral (30) is welded along the seam (20) within 400° of the bend line.

4. The method according to any one of claims 1 to 3, wherein in step d) the one or more first metal stiffening elements (2) are welded within 400° of the bend line.

5. 5. The method according to claim 1, wherein the one or more first metal stiffening elements (2) are spiral-shaped with an outer diameter identical to the inner diameter of the reinforcing pipe (10), or the one or more first metal stiffening elements (2) are spiral-shaped with an inner diameter identical to the outer diameter of the reinforcing pipe (10).

6. 5. The method according to claim 1, wherein the one or more first metal stiffening elements (2) are circular with an outer diameter identical to the inner diameter of the reinforcing pipe (10), or the one or more first metal stiffening elements (2) are circular with an inner diameter identical to the outer diameter of the reinforcing pipe (10).

7. The method according to any one of the preceding claims, wherein step d) comprises welding two or more first metal stiffening elements (2) to the first metal plate (1).

8. 8. The method according to claim 7, wherein the two or more first metal stiffening elements (2) are parallel to each other.

9. 9. The method according to claim 8, wherein the distance between the two or more first metal stiffening elements (2) is between 1 / 50 and 1 / 4 of the pipe diameter, preferably between 1 / 30 and 1 / 6 of the pipe bend diameter D.

10. The method according to any one of claims 1 to 9, wherein t is 30 mm or less.

11. The method according to any one of claims 1 to 10, further comprising the step of: e) welding one or more second metal stiffening elements (4) onto said first metal plate (1) at an angle to said one or more first metal stiffening elements (2).

12. 11. The method of claim 10, wherein the one or more second metal stiffening elements (4) are perpendicular to the one or more first metal stiffening elements (2).

13. The method according to any one of claims 1 to 12, wherein said one or more first metal stiffening elements (1) are T-beams or U-beams.

14. A method according to any one of the preceding claims, comprising bending the first metal plate (1) to form two or more turns of the spiral (30).

15. The method according to any one of claims 1 to 14, wherein steps b and d are carried out simultaneously.

16. 16. The method according to any one of claims 1 to 15, further comprising the step of welding one or more lower web members (64) to the first metal plate (1), wherein the one or more first metal stiffening elements (2) are placed on top of the one or more lower web members (64), and the one or more lower web members (64) and the one or more first metal stiffening elements (2) are welded together after being bent together with the first metal plate (1).

17. providing one or more pre-fabricated first metal stiffening elements (2) that form a complete or nearly complete circle; The method according to any one of claims 1 to 4 and 6 to 15, further comprising the step of positioning the one or more first metal stiffening elements (2) inside or outside the spiral formed by the bent metal plate after one or more complete turns of the spiral have been bent but before the entire first metal plate has been bent.

Images