Bending machine

Abstract

A bending machine (50) for making a reinforced pipe or reinforced pipe sector (10), the reinforced pipe or reinforced pipe sector (10) comprising a metal pipe or reinforced pipe sector having a base with a thickness t and a diameter D, and one or more first metal stiffening elements (2) on an inner surface along the circumference of the metal pipe or reinforced pipe sector (10), the bending machine (50) comprising an inner roller (51) and two outer rollers (52), the outer surface of the inner roller (51) having one or more first grooves (55) for accommodating the one or more first metal stiffening elements (2).

Description

[Technical Field]

[0001] The present invention relates to a bending machine. [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 reinforced cylinders, pipes and pipe sectors 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 application provides a manufacturing method for a reinforced pipe sector, comprising: a) providing a first metal plate having a thickness t; b) providing one or more first metal stiffening elements and disposing said one or more first metal stiffening elements on said first metal plate; c) bending said first metal plate together with said one or more first metal stiffening elements to form a pipe sector; d) welding the one or more first metal stiffening elements to the first metal plate; Here, a method is described in which steps c and d can be performed in any order.

[0007] In one embodiment of the method, the pipe sector has a bend 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. Those skilled in the art will understand that the bend diameter is the diameter of the circle around which the metal plate is bent.

[0008] In one embodiment, the ratio D / t may be comprised between 100 and 1500, preferably between 200 and 800. In one embodiment, the order of steps in the method is a), then b), then d), then c), in other words, one or more first metal stiffening elements are first welded to a first metal plate to form a reinforcing metal plate, which is then bent to form a reinforced pipe sector.

[0009] In one embodiment, the order of steps in the method is a), then b), then c), then d), in other words, a first metal plate is first bent together with one or more first metal stiffening elements to form a pipe sector, and then one or more first metal stiffening elements are welded to the pipe sector to form a reinforced pipe sector.

[0010] In one embodiment, the welding step d) is performed after step c) within 360° with respect to the bend line (i.e. the line on the metal plate along which the metal plate is bent), the angle being defined between the radius of the circle along which the metal plate is bent starting from the bend line and a second radius of the circle along which the metal plate is bent starting from the weld point.

[0011] In one embodiment, the welding step d) occurs after step c) within 270°, 180°, 135°, 90°, 60°, 45°, or 30° of the bend line.

[0012] 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.

[0013] 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.

[0014] In one embodiment, the one or more first metal stiffening elements for the pipe are arranged on a first metal plate in the bending direction, for example, if the one or more first metal stiffening elements are a beam, it is arranged on the metal plate perpendicular to the axis of rotation around which the metal plate and the one or more first metal stiffening elements are bent.

[0015] In one embodiment, the welding step b) 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.

[0016] In one embodiment, the welding step b) 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.

[0017] 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.

[0018] In one embodiment, the method comprises: e) welding one or more second metal stiffening elements onto said first metal plate at an angle to said one or more first metal stiffening elements.

[0019] 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 d) may comprise welding two or more, three or more, four or more, five or more, or ten or more second metal stiffening elements onto the second metal plate.

[0020] In one embodiment, the pipe sector is a full pipe, a half pipe, or a quarter pipe. In one embodiment, the pipe section is a cylinder or tapered cylinder having a generally circular or oval base.

[0021] In one embodiment, the pipe sector is a spiral or tapered spiral with a significantly circular or elliptical base. In one embodiment, the method comprises: f) between steps a) and b) bending at least the end of the first metal plate to approximately the same curvature as the remainder of the pipe sector; The method may further comprise cutting at least an end portion of the one or more first stiffening elements so that the end portion of the one or more first stiffening elements has approximately the same curvature as the end portion of the first metal plate.

[0022] In one embodiment, the method comprises: g) between steps a) and b) bending the ends of the first metal plate to approximately the same curvature as the rest of the pipe sector; The method may further comprise cutting both ends of the one or more first stiffening elements so that the ends of the one or more first stiffening elements have approximately the same curvature as the ends of the first metal plate.

[0023] Here, those skilled in the art will understand that the ends of the metal plate or one or more first stiffening elements are the parts of the metal plate or one or more first stiffening elements that are close to the edges of the plates that come into contact with each other when the cylinder is formed.

[0024] 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.

[0025] In one embodiment, the one or more first stiffening elements may be 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.

[0026] 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.

[0027] 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 sector to the structural capacity of the first metal plate may be 5 or more, preferably 10 or more.

[0028] 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 complete ring around the inner circumference of the cylinder, or a nearly complete ring if a small gap is left for final welding at a later stage.

[0029] 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.

[0030] 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 reinforced pipe.

[0031] In one embodiment, the reinforced pipe has a D / t ratio of greater than 100. In one embodiment of the second aspect, the ratio D / t may be between 100 and 1500, preferably between 200 and 800.

[0032] 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 the circumference of the metal pipe.

[0033] The bending machine comprises one 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.

[0034] 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 grooves have a depth at least equal to a height of the one or more first metal stiffening elements.

[0035] In one embodiment of the third aspect, the one or more 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 sector, such as a welding arm for automatic welding.

[0036] 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.

[0037] 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 at least a side-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, to apply sufficient pressure to the one or more first stiffening elements to prevent the one or more first stiffening elements from buckling.

[0038] In one embodiment, each spacer may comprise two side acting spacer rollers. In one embodiment, each spacer may be freestanding, i.e., each spacer does not need to be attached to another structure.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In a fourth aspect, the present application provides a manufacturing method for a joined reinforced pipe sector, comprising: a) providing a first metal plate having a thickness t; b) bending the first metal plate to form a first pipe sector of up to 340°; c) providing a pre-fabricated reinforcing pipe sector, aligning said pre-fabricated reinforcing pipe and said first pipe sector along their longitudinal axes, and welding said first pipe sector to said pre-fabricated reinforcing pipe sector along their circumference; d) providing one or more pre-fabricated first metal stiffening elements; e) positioning the one or more pre-fabricated first metal stiffening elements along the inner or outer circumference of the first pipe sector and welding the one or more pre-fabricated first metal stiffening elements to the first pipe sector to form a joined, reinforced, joined pipe sector.

[0046] In one embodiment of the method according to the fourth aspect, the one or more pre-fabricated first metal stiffening elements form a complete circle or a nearly complete circle. Here, a person skilled in the art will understand that "a first metal stiffening element that forms a complete circle or an almost complete circle" means that the stiffening element forms a circle or an almost circle in cross section.

[0047] In one embodiment of the method according to the fourth aspect, one or more pre-fabricated first metallic stiffening elements are positioned along an inner circumference of the first pipe sector. In one embodiment of the method according to the fourth aspect, one or more pre-fabricated first metallic stiffening elements are positioned along the circumference of the first pipe sector.

[0048] In one embodiment of the method according to the fourth aspect, the pre-fabricated reinforced pipe sector is a pipe (i.e. a 360° pipe sector), and the method comprises: The method may further comprise the step of: f) further bending the first metal plate to form a first pipe sector of approximately 360°.

[0049] Here, those skilled in the art will understand that the first pipe sector and the prefabricated reinforced pipe sector have approximately the same diameter, and are aligned so that the longitudinal axes of the first pipe sector and the prefabricated reinforced pipe sector are aligned and positioned adjacent to each other, and are welded along the contact points, in other words, along the circumference of the base of the pipe sector.

[0050] In one embodiment, a pre-fabricated reinforced pipe sector is obtained according to the first aspect of the invention. In embodiments of the method according to the fourth aspect, the joined reinforced pipe sector and the first pipe sector have a bending diameter D, and the ratio D / t may be 100 or more, 150 or more, 200 or more, 250 or more, 300 or more, or 500 or more.

[0051] Those skilled in the art will understand that the bend diameter is the diameter of the circle around which the metal plate is bent. In one embodiment, the ratio D / t may be comprised between 100 and 1500, preferably between 200 and 800.

[0052] In the following description, the invention is further explained by means of exemplary embodiments shown in the drawings. [Brief explanation of the drawings]

[0053] [Figure 1a] FIG. 1 is a side view of a first embodiment of a series of first metal stiffening elements welded to a first metal plate. [Figure 1b] FIG. 2 is a perspective view of a first embodiment of a series of first metal stiffening elements welded to a first metal plate. [Figure 2a] FIG. 10 is a side view of a second embodiment of a series of first metal stiffening elements welded to a first metal plate and welded to a second metal plate. [Figure 2b] 10 is a perspective view of a second embodiment of a series of first metal stiffening elements welded to a first metal plate and welded to a second metal plate. FIG. [Figure 3a]10A and 10B are side views of the first metal plate and the first metal stiffening element during bending and subsequent welding at an angle α. [Figure 3b] 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 4a] 1 is a perspective view of a series of first metal stiffening elements welded to a first metal plate and welded to a second metal plate that has been bent into a spiral. [Figure 4b] 1 is a perspective view of an embodiment of a first 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 a series of first metal stiffening elements welded to a first metal plate having a first embodiment of a spacer; FIG. [Figure 9] 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 10] FIG. 10 is a front view of a bending machine equipped with a spacer. [Figure 11] 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 12] Detail 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 comprising a series of vertical and lateral rollers arranged on inner roller support arms. [Figure 14]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 15] 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 16] 1 is a perspective view of a series of first metal stiffening elements welded to a first metal plate, bent into a spiral, and welded to a second metal plate. [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

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Therefore, new production methods are being developed to alleviate the problems of existing methods. The conventional technique for producing reinforced pipe sectors or reinforced pipes involves first bending a metal plate, then forming the pipe, and then welding metal stiffening elements onto the formed cylinder.

[0058] 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.

[0059] 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. An example of such a method is shown, for example, in Figure 5. In detail, the method proposes bending one or more first stiffening elements 2 and a metal plate 1 together to form a pipe sector 10. Another example of such a method is shown in Figure 4b. Details and alternatives are shown in the other figures. In detail, the method proposes bending the metal plate 1 along a bend line to form a helix, the pitch of the helix being approximately equal to the width of the plate, two consecutive turns of the helix being in contact (or being arranged in contact) at a seam 20, welding the helix 30 along the seam 20 to form the pipe, and welding one or more first metal stiffening elements to the pipe to form the reinforced pipe 10.

[0060] Now, those skilled in the art will understand that the stiffening element 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.

[0061] Thanks to the method, the metal plate 1 is able to support the 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 sectors 10, and in particular for making complete reinforced pipe, i.e. pipe of any desired length.

[0062] 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.

[0063] 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 a first step, a series of parallel stiffening elements 2, here T-beams, were 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 circular ring stiffened cylinder pipe sector 10, where the T-beams form a circular cross section.

[0064] In this example, the welding step is accomplished before the bending step. In some examples, it may be advantageous to have the bending step first and then the welding step. The reinforcing flat plate 3 then passes through a bending machine 50 to form a helical stiffened pipe or helix 30, and the T-beam also forms 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. The angle α is defined as the angle between a first radius of the helix along which the metal plate is bent, starting from the starting point of the bend (or bend line), and a second radius of the helix, starting from the weld point. The formed helix is supported by one or more support rollers 70.

[0065] Second Example In the 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 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 circular ring-stiffened cylinder pipe sector 10 or a spiral stiffened pipe or helix 30. The seam 20 of the helix 30 is welded at a 45° angle α to the bend line, for example, using a welding arm.

[0066] 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.

[0067] The reinforced flat plate 3 then passes through a bending machine 50 to form a circular ring reinforced cylinder pipe sector 10, where the T-beam forms a circular cross section. The reinforced pipe sector 10 is supported by support rollers 70.

[0068] Having a series of second stiffening elements in the orthogonal direction also stiffens the reinforced pipe in the orthogonal direction. This is not necessary, but is advantageous for final reinforcement pipes installed to increase the pipe's strength. This also applies to pipe sectors.

[0069] Fourth Example In a fourth embodiment, a series of first stiffening elements 2 are placed (without welding) on the metal plate 1. The metal plate 1 and stiffening elements 2 then pass through a bending machine 50 and are welded immediately after the plate 1 and stiffening elements 2 are bent as shown in FIG. 3. In other words, at least the tack welds are advantageously performed close to the point where the plate 1 and stiffening elements 2 are plastically bent, and the final weld can be performed close to the point where the plate 1 and stiffening elements 2 are plastically bent, or further away if vibrations, for example from a roller cold forming operation, adversely affect the weld quality. In other words, the weld is performed at an angle α with respect to the bend line (i.e., the line on the metal plate along which the metal plate is bent), where the angle α 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. By welding the stiffening element 2 to the plate 1 after plastic bending, the combined bending stiffness of the metal plate 1 and the stiffening element 2 during the bending operation is reduced, thus reducing the bending force required during the bending operation and the risk of buckling of the stiffening element. This is also advantageous as it reduces the inherent material strains in the metal plate and the first stiffening element during and after the plastic bending operation.

[0070] Fifth Example In the first step, a single stiffening element 2, here a T-beam, was first welded to a flat plate 1 to form a stiffened flat plate 3. The stiffened flat plate then passes through a bending machine 50 to form a helically stiffened pipe 10, as shown in Figure 5. The stiffened pipe 10 is supported by a series of support rollers 70.

[0071] After forming the pipe to the 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. Alternatively, the plate 1 may be pre-cut before entering the bending machine so that the ends of the spiral reinforced pipe are cylindrical with the ends perpendicular to the longitudinal axis of the pipe.

[0072] Here, the distance between the two first metal stiffening elements 2 may typically be 500 to 2000 mm. Sixth Example In a sixth embodiment, as shown in Fig. 12, 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 with the web members 64 and stiffening elements 2 passes through a bending machine 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 α to the plate 1 with the lower portion of the lower web membrane 64 after plastic bending has occurred 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.

[0073] In this example, part of the welding process is accomplished before the bending process and another part is accomplished after the bending process to reduce stiffness and risk of web and flange buckling during the bending operation, as well as to reduce post-bending plastic (and permanent) strain in the bent material. High plastic strain levels can cause the material to initiate microcracks, thus reducing the fatigue strength of the bent material, and are therefore desirably reduced as much as possible during fabrication.

[0074] Seventh Example In the first step, a first flat metal plate 1 passes through a bending machine to form a 340° circular pipe sector. The formed pipe sector is welded to a previously produced (or prefabricated) reinforced pipe sector. The first metal plate 1 is further bent using a bending machine for a total of approximately 360° and welded to the reinforced pipe sector. One or more metal stiffening elements 2 are independently manufactured to form a complete or nearly complete circle and placed inside the pipe sector. One or more first metal stiffening elements 2 are then welded onto the pipe sector to form a joined reinforced pipe sector. Welding the stiffening elements 2 to the plate 1 after plastic bending reduces the combined bending stiffness of the metal plate 1 and the stiffening elements 2 during the bending operation, thus reducing the bending force required and the risk of buckling of the stiffening elements during the bending operation.

[0075] Eighth Example In the eighth 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, as shown in FIG. 3a (in other words, the welding occurs shortly after or at the point where the plate is plastically bent). 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. 3a), the bend line angle β is about 85°. In submerged arc welding, the optimum weld position is vertically downward, so 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 with a β of 180 degrees.

[0076] 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. Ninth 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.

[0077] Here, the distance between the two first metal stiffening elements 2 may typically be 500 to 2000 mm. Tenth 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. 4b. Then, one or more first metal stiffening elements 2 are 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. The bent metal plate 1 is therefore structurally supported against collapse during the bending operation by the adjacent portions of the finished helical pipe section on which the metal stiffening elements are installed, as shown in Figure 4b.

[0078] Eleventh Example In a first step, a series of parallel stiffening elements 2, here T-beams, are first welded to the flat plate 1 to form the stiffened flat plate 3 as shown in Figures 1a and 1b. In addition to this, a series of parallel second stiffening elements 4, here also T-beams, may be welded to the plate 1 perpendicular to the first stiffening elements 2 to form the stiffened flat plate 3. The stiffened flat plate 3 then passes through a bending machine 50 to form the stiffened cylindrical pipe sector 10.

[0079] In an eleventh example, the stiffening element 2 forms a circular section on the outer surface area of the formed reinforced cylindrical pipe sector 10, as shown in FIG. An advantage of having stiffening elements 2 on the outer surface area of the formed reinforced cylindrical pipe sector 10 is that a second metal plate 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 stiffens the pipe sector 10.

[0080] Twelfth Example In a twelfth embodiment, a first stiffening element 2 is placed on the flat plate 1 without first being welded. The flat plate 1 and the stiffening element 2 then pass through a bending machine 50 and the bent stiffening element 2 may be immediately welded onto the outer surface area of the bent metal plate 1.

[0081] Thirteenth Example In the thirteenth embodiment, a helical pipe sector 10 is prepared as in the twelfth embodiment, after which a second metal plate 5 is bent and then welded to the stiffening elements 2 formed on the outer surface area of the stiffened cylindrical pipe sector 10 to form a double deck (or double hull deck), as shown in Figure 15.

[0082] Fourteenth Example In a first step, a series of parallel stiffening elements 2, here T-beams, are first welded to the flat plate 1 to form the stiffened flat plate 3 as shown in Figures 1a and 1b. In addition, a series of parallel second stiffening elements 4, here also T-beams, may be welded to the plate 1 perpendicular to the first stiffening elements 2 to form the stiffened flat plate 3. The stiffened flat 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 at the bend line angle α, for example using a welding arm.

[0083] In a fourteenth embodiment, the stiffening element 2 forms a helix on the outer surface area of the formed helical stiffening pipe or helix 30 . An advantage of having stiffening elements 2 on the outer surface area of the formed helical stiffening pipe or helix 30 is that a second metal plate 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 stiffens the helical stiffening pipe or helix 30.

[0084] Fifteenth Example 17 , in a fifteenth 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 a complete circle, a nearly complete circle or a helix, 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.

[0085] 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 stiffens the reinforcing pipe 10.

[0086] Sixteenth Example In the sixteenth embodiment, a helical reinforcing pipe or helix 30 is prepared as in the fourteenth or fifteenth embodiment. Thereafter, a second metal plate 5 is bent and then welded to the stiffening element 2 formed on the outer surface area of the helical reinforcing pipe or helix 10 to form a double deck (or double hull deck).

[0087] 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 / 2 of the pipe bend diameter D, preferably between 1 / 30 and 1 / 6 of the pipe bend diameter D.

[0088] 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 / 2 of the pipe sector bending diameter D, preferably between 1 / 30 and 1 / 3 of the pipe sector bending diameter D.

[0089] 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 reinforced pipe 10, it is possible to cut the metal plate prior to the bending operation so that the pipe ends exit the bending machine without having to cut the metal plate after the bending operation to orthogonalize the cylinder ends to the longitudinal axis of the pipe. This is of particular interest when manufacturing helically reinforced pipe 10.

[0090] Bending machine 6 and 7 show two examples of bending machines 50. The bending machine 50 includes a pair of outer rollers 52 and an inner roller 51.

[0091] In the bending machine 50 of the present invention, the inner roller 51 is configured to bend a reinforced bending plate 3 , ie a metal plate 1 welded to one or more first stiffening elements 2 .

[0092] As shown in Figure 6 (and Figure 7), 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 bending 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.

[0093] 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.

[0094] It will be appreciated that when forming a reinforced pipe sector 10 in which stiffening elements 2 are molded onto its outer surface area, such as in Examples 11-16 above, 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 one or more first stiffening elements 2.

[0095] 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 depths of the one or more first grooves 55 and the one or more second grooves 56 are preferably equal to the heights of the one or more first stiffening elements 2 and the one or more second stiffening elements 4, respectively. In this way, the bending 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.

[0096] 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.

[0097] The bending machine 50 may advantageously be mounted so that the central axes of the inner rollers are perpendicular or parallel to the axis of gravity. It will be appreciated that when forming a reinforced pipe sector 10 in which stiffening elements 2 are molded onto its outer surface area, such as in Examples 11-16 above, one or more first grooves 55 and one or more second grooves 56 need to be arranged on the outer surface roller 52 rather than the inner roller 51 so as to accommodate one or more first stiffening elements 2 and one or more second stiffening elements 4.

[0098] In a third embodiment of the bending machine 50, the bending machine is arranged similarly to that described in the above embodiment of the bending machine 50, but the inner rollers 51 comprise a series of inner rollers 61 and side rollers 62 arranged on inner roller support arms 73, as shown in Figure 13. The individual inner rollers 61 are arranged on the inner roller support arms 73 at spaced intervals along a bending line that is generally parallel to the longitudinal axis of the helix 30. The individual inner rollers 61 are further arranged on the inner roller support arms 73.

[0099] As shown in Figure 13, 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.

[0100] When forming a reinforced pipe sector 10, in which the stiffening element 2 is molded onto its outer surface area, such as in Examples 11-16 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.

[0101] 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.

[0102] 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 8 and 9. 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.

[0103] 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.

[0104] 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 8 and 9.

[0105] 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.

[0106] Preferably, the two or more spacers 60 may comprise vertical acting spacer rollers 61 that transmit the pressure of the inner rollers 51 to the first metal plate 1, as shown in Figures 10 and 11. Spacer holding supports 71 may be placed in front of the inner and outer rollers 51, 52 to hold the spacers 60 during the rolling / bending operation.

[0107] Preferably, the two or more spacers 60 may further comprise side acting spacer rollers 62 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.

[0108] 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 9, 10 or 11) or rectangular prisms (Figure 8).

[0109] It will be appreciated that when forming a reinforced pipe sector 10 in which stiffening elements 2 are molded onto its outer surface area, such as in Examples 11-16 above, two or more spacers 60 are preferably arranged on each side of one or more first stiffening elements 2 and between the first metal plate 1 and the outer roller 52.

[0110] 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 the metal plate 1 together with the stiffening element 2, the end of the metal plate 1 is often not bent. Usually, the unbent end of the plate 1 is cut off before being welded together to form a pipe, such as a cylinder.

[0111] 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).

[0112] The metal plate 1 therefore has ski-tip shaped ends which have approximately the same curvature and therefore do not need to be plastically bent to become part of the final circular or approximately circular shape of the manufactured pipe section.

Claims

1. A bending machine (50) for making a reinforced pipe or reinforced pipe sector (10), said reinforced pipe or reinforced pipe sector (10) comprising a metal pipe or metal pipe sector having a base with a thickness t and a diameter D, and one or more first metal stiffening elements (2) on the inner or outer surface along the circumference of said metal pipe or metal pipe sector (10), The bending machine (50) comprises an inner roller (51) and two outer rollers (52), and the outer surface of the inner roller (51) or the outer roller (52) is provided with one or more first grooves (55) for accommodating the one or more first metal stiffening elements (2).

2. 2. The bending machine (50) of claim 1, wherein the ratio D / t is 100 or greater.

3. 3. The bending machine (50) according to claim 1 or 2, wherein the one or more first grooves (55) have a depth at least equal to a height of the one or more first metal stiffening elements (2).

4. The bending machine (50) according to any one of claims 1 to 3, wherein the one or more first grooves (55) have a depth approximately equal to a height of the one or more first metal stiffening elements (2).

5. The bending machine (50) according to any one of the preceding claims, further comprising means for welding said one or more first metal stiffening elements (2) to said metal pipe sector, such as a welding arm.

6. The bending machine (50) of any one of claims 1 to 5, further comprising two or more spacers (60).

7. A bending machine (50) according to any one of the preceding claims, wherein each spacer comprises a vertically acting spacer roller (61).

8. A bending machine (50) according to any one of the preceding claims, wherein each spacer comprises one or more side acting spacer rollers (62).

9. The bending machine (50) of any one of claims 1 to 8, further comprising a support roller (70).

10. The bending machine (50) according to any one of claims 1 to 9, wherein the orientation of the inner and outer rollers (61, 62) is adjustable relative to the longitudinal axis of the reinforced pipe (10) during operation of the bending machine (50).

11. The bending machine (50) according to any one of claims 1 to 10, wherein the first groove (55) is a spiral groove.

12. 12. The bending machine (50) according to claim 1, wherein the inner rollers (51) comprise a series of inner rollers (61) and lateral rollers (62) arranged on inner roller support arms (73), or the outer rollers (52) comprise a series of outer rollers and lateral rollers arranged on outer roller support arms.

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