Manufacturing method of reinforced pipe

Abstract

A method of manufacturing a reinforced tube (10), comprising the steps of: providing a first metal plate (1) having a thickness t; bending the first metal plate (1) along a bending line to form a helix (30), wherein the pitch of the helix (30) is substantially equal to the width of the plate; and wherein two consecutive turns of the helix (30) are in contact at the seam (20); welding the helically formed tube along the seam (20); and welding at least one first metal reinforcing element (2) to the tube, thereby forming a reinforced tube (10).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a reinforced tube. Background Art

[0002] The offshore floating wind industry is growing. As the size increases, new wind turbine designs are being developed. Therefore, new buoyancy tanks that are lightweight and strong must be provided in an efficient manner in order to produce a floating structure with sufficient buoyancy at the lowest possible cost.

[0003] The present invention relates to a method for manufacturing a cylinder, and more particularly to a method for manufacturing a ring-reinforced cylinder, such a ring-reinforced cylinder can be used as a buoyancy member for an offshore floating wind turbine structure or other large-diameter thin-shell structures. So far, one solution is to reduce the wall thickness to reduce the steel weight and thus the cost of the floating offshore structure.

[0004] Conventional techniques for manufacturing a ring-reinforced structure include bending a metal sheet to form a structure such as a tube, and then welding a ring element on the inside of the tube. For a structure with a relatively large diameter-to-wall thickness ratio (such as a tube), this method is accompanied by problems related to buckling caused by the weight of the sheet itself during sheet bending. The same is true if spiral welding of the tube using conventional techniques is used as the manufacturing method. Welding in the ring-reinforced element after sheet bending is also expensive because it involves additional operations, including additional processing during the manufacture of the reinforced shell. One solution to this is to design a flat buoyancy member instead of a cylinder. A flat structure can be easily reinforced with T-beams by welding the T-beams to the shell plate when the shell plate is in a flat position on the floor. This is a well-known manufacturing method in the shipbuilding industry. Therefore, the production cost per kilogram of steel for a flat reinforced plate is lower than that of a circular reinforced plate. However, a flat buoyancy member will have a higher hydrodynamic excitation force, so a floating foundation carrying the same wind turbine will require more steel.

[0005] Therefore, new production methods have been developed in order to alleviate the problems of the existing methods for manufacturing reinforced thin-walled shells. Summary of the Invention

[0006] The present invention is defined by the appended claims and is defined below:

[0007] In a first aspect, the present invention relates to a method for manufacturing a reinforced tube, which comprises the following steps:

[0008] a) providing a first metal sheet having a thickness t,

[0009] b) bending the first metal sheet along a bending line to form a helix,

[0010] wherein the pitch of the helix is substantially equal to the width of the plate, and

[0011] wherein two consecutive turns of the helix contact at the seam;

[0012] c) welding the helix along the seam to form a tube; and

[0013] d) welding at least a first metal reinforcing element to the tube, thereby forming a reinforced tube.

[0014] Those skilled in the art will understand that the bending is achieved by using any bending machine known in the art. All production steps can be advantageously achieved without removing the plate, the tube or the reinforced tube from the bending machine.

[0015] Those skilled in the art will understand that the term "substantially equal" herein means "equal with a 10% margin". In other words, the pitch of the helix is between 90% and 110% of the width of the plate.

[0016] In one embodiment, the pitch of the helix is between 95% and 105%, 90% and 110%, 100% and 110%, 100% and 105%, 95% and 100%, 100% and 102%, or 100% and 101% of the width of the plate.

[0017] In one embodiment of the method, the reinforced tube has a diameter D, and the ratio D / t can be at least 100, at least 150, at least 200, at least 250, at least 300 or at least 500.

[0018] In one embodiment, the ratio D / t can be between 100 and 1500; preferably between 200 and 800.

[0019] In one embodiment, in step c), the helix is welded along the seam within 400° of the bend line (i.e., the line on the metal plate along which the metal plate is bent); and an angle α is defined between a first radius of the helix along which the metal plate is bent starting from the bend line and a second radius of the helix starting from the welding point.

[0020] In one embodiment, in step c), the helix is welded along the seam within 360°, 270°, 180°, 135°, 90°, 60°, 45°, 30°, 10° or 5° of the bend line.

[0021] In one embodiment, in step d), at least one first metal reinforcing element is 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 helix along which the metal plate is bent starting from the bend line and a second radius of the helix starting from the welding point.

[0022] In one embodiment, in step d), at least one first metal reinforcing element is welded within 360°, 270°, 180°, 135°, 90°, 60°, 45°, 30°, 10°, or 5° of the bending line.

[0023] In one embodiment, at least one first metal reinforcing element of the tube does not bend together with the first metal plate.

[0024] In one embodiment, at least one first metal reinforcing element of the tube bends together with the first metal plate.

[0025] In one embodiment, the thickness t can 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.

[0026] In one embodiment, the thickness t can be between 10 mm and 500 mm, preferably between 15 mm and 200 mm.

[0027] In one embodiment, the diameter D can be between 5 m and 50 m; preferably between 8 m and 30 m.

[0028] 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 reinforcing element.

[0029] In one embodiment, the welding step d) can include welding at least two, at least three, at least four, at least five, or at least ten first metal reinforcing elements to the first metal plate.

[0030] In one embodiment, the welding step d) can include welding at least two first metal reinforcing elements to the first metal plate, and at least two first metal reinforcing elements are parallel to each other.

[0031] In one embodiment, at least two first metal reinforcing elements are parallel, and the distance between at least two first metal reinforcing elements is between 1 / 50 and 1 / 4 of the tube diameter D, preferably between 1 / 30 and 1 / 6 of the tube diameter D.

[0032] In one embodiment, at least one first metal reinforcing element is helical, having a diameter equal to the inner diameter of the reinforcing tube, or wherein at least one first metal reinforcing element is helical, having an inner diameter equal to the outer diameter of the reinforcing tube.

[0033] In one embodiment, at least one first metal reinforcing element is circular and has a diameter that is the same as the inner diameter of the reinforcing tube, or at least one first metal reinforcing element is circular and has an inner diameter that is the same as the outer diameter of the reinforcing tube. In one embodiment, at least one first metal reinforcing element forms a circle or a sector of a circle, such as a semi-circle or a quarter of a circle.

[0034] In one embodiment, steps b) and d) can be simultaneous. In other words, the bending step is achieved by a bending machine, and the welding of at least one first metal reinforcing element is achieved without removing the metal sheet or the formed tube from the bending machine. Steps b) and d) can both be achieved in a continuous manner and simultaneously, or can be intermittent by performing a series of partial steps b) and partial steps d).

[0035] In one embodiment, the method may further include the step of welding at least one lower abdominal plate member to the first metal sheet, and at least one first metal reinforcing element is placed and welded on top of at least one lower abdominal plate member.

[0036] In one embodiment, the method may further include the following steps:

[0037] e) Welding at least one second metal reinforcing element to the first metal sheet at an angle to the at least one first metal reinforcing element.

[0038] In one embodiment, at least one second metal reinforcing element is perpendicular to at least one first metal reinforcing element.

[0039] In one embodiment, the welding step e) may include welding at least two, at least three, at least four, at least five or at least ten second metal reinforcing elements to the first metal sheet.

[0040] In one embodiment, the welding step e) may include welding at least one metal reinforcing element to the first metal sheet without removing the tube segment from the tube bending machine after bending the first metal sheet by at least 400 degrees using a bending machine to form a full turn. Thus, the metal sheet is structurally supported by adjacent portions of the finished tube with metal reinforcing elements installed during the bending operation to prevent collapse.

[0041] In one embodiment, the method may include bending the first metal sheet to form at least two turns of a helix.

[0042] In one embodiment, the reinforcing tube can be a cylinder or a conical cylinder having a substantially circular or oval bottom.

[0043] In one embodiment, the reinforcing tube can be a cylinder or a conical cylinder with a substantially circular base, the base having an ovalization factor of less than 10%, 5%, 2%, or 1%. The ovalization factor is herein defined as the ratio of the longest diameter of the base to the smallest diameter of the base.

[0044] In one embodiment, the first metal plate can have a yield strength of at least 200 MPa, at least 250 MPa, at least 300 MPa, or at least 400 MPa.

[0045] In one embodiment, the first metal plate can be made of steel, steel alloy, aluminum, or aluminum alloy.

[0046] In one embodiment, at least one first reinforcing element can be a plate, a T-beam, or a U-beam.

[0047] In one embodiment, at least one first reinforcing element can be made of steel, steel alloy, aluminum, or aluminum alloy.

[0048] In one embodiment, at least one second reinforcing element can be made of steel, steel alloy, aluminum, or aluminum alloy.

[0049] In one embodiment, at least one first reinforcing element and the first metal plate are made of the same material.

[0050] In one embodiment, at least one second reinforcing element and the first metal plate are made of the same material.

[0051] In one embodiment, the ratio of the structural capacity of the reinforcing tube to the structural capacity of the first metal plate can be at least 5, preferably at least 10.

[0052] In one embodiment, at least one first reinforcing element can be oriented in one direction on the first metal plate such that when a cylinder is formed, at least one first reinforcing element forms a ring along the inner perimeter of the cylinder.

[0053] In one embodiment, at least one second reinforcing element is welded in a direction orthogonal to at least one first reinforcing element.

[0054] In one embodiment, the method further includes welding a second metal plate to at least one first metal reinforcing element, wherein the second metal plate is parallel to the first metal plate.

[0055] In one embodiment, the second metal plate can be made of steel, steel alloy, aluminum, or aluminum alloy.

[0056] In a second aspect, the present application describes a reinforcing tube, which includes:

[0057] - A first metal tube having a thickness t and a bottom with a diameter of D,

[0058] - at least one first metal reinforcing element welded to the inner surface of the reinforcing tube,

[0059] where the ratio D / t exceeds 100.

[0060] In an embodiment of the second aspect, the ratio D / t can be between 100 and 1500, preferably between 200 and 800.

[0061] In a third aspect, the present application describes a bending machine for manufacturing a reinforcing tube, the reinforcing tube comprising a metal tube having a bottom with a thickness t and a diameter D, and at least one first metal reinforcing element welded along the circumference of the metal tube on the inner surface,

[0062] where the bending machine comprises an inner roll and two outer rolls, wherein the outer surface of the inner roll or the outer rolls comprises at least one first groove for receiving at least one first metal reinforcing element.

[0063] In an embodiment of the third aspect, the ratio D / t is at least 100.

[0064] In an embodiment of the third aspect, the depth of the at least one first groove is at least equal to the height of the at least one first metal reinforcing element.

[0065] In an embodiment of the third aspect, the depth of the at least one first groove can be substantially equal to the height of the at least one first metal reinforcing element.

[0066] In an embodiment, the bending machine may further comprise means for welding at least one first metal reinforcing element to the metal tube, such as welding arms.

[0067] In an embodiment, the bending machine may further comprise at least two spacers. A spacer is an object that can be placed on each side of at least one first reinforcing element and between the first metal plate and the inner roll.

[0068] In an embodiment, each spacer may comprise a vertically acting spacer roll. The vertically acting spacer roll transfers the pressure of the inner roll to the first metal plate.

[0069] In an embodiment, each spacer may comprise a laterally acting spacer roll. The laterally acting spacer roll is placed on each side of at least one first reinforcing element, preferably in contact with at least one first reinforcing element, and applies sufficient pressure on at least one first reinforcing element to prevent at least one first reinforcing element from buckling.

[0070] In an embodiment, each spacer may comprise two laterally acting spacer rolls.

[0071] In one embodiment, each spacer can be freestanding. That is, each spacer does not need to be attached to another structure.

[0072] In one embodiment, the bending machine may further include support rollers. The support rollers are rollers that support the formed reinforced tube to further help avoid buckling or bending of the helix, tube, or reinforced tube under its own weight.

[0073] In one embodiment, the height and position of the support rollers can be adjustable. This advantageously allows changing the orientation of the longitudinal axis of the reinforced tube during the production of the reinforced tube / during the operation of the bending machine.

[0074] In one embodiment, the bending machine may include two support rollers.

[0075] In one embodiment, a series of vertical rollers may be spaced along the bending axis on the roller arm member for manufacturing a helical tube in the bending machine. The bending machine may further include lateral rollers to support the first metal reinforcement element during plastic bending of the metal reinforcement element in the bending machine. The series of vertical rollers may be oriented at a feed angle such that the axis of rotation is substantially perpendicular to the first metal plate entering the bending machine for manufacturing the reinforced tube.

[0076] In one embodiment, a series of first metal reinforcement elements may be welded to the first metal plate at an angle orthogonal to the longitudinal axis of the produced helical tube. Then the metal plate with the metal reinforcement element may be fed into the bending machine during the production of the reinforced helical tube. The bending machine may include a helical inner roller that can ensure the contact pressure on the first metal plate and on the first metal reinforcement element, while preventing the first metal reinforcement element from colliding with the rollers in the bending machine during the continuous manufacture of the helical tube.

[0077] In one embodiment, during the operation of the bending machine, the orientation of the inner roller and the outer roller can be adjusted relative to the longitudinal axis of the reinforced tube. This advantageously allows changing the orientation of the longitudinal axis of the reinforced tube during production.

[0078] In one embodiment, the first groove of the inner roller of the bending machine can be a helical groove.

[0079] In one embodiment, the inner roller may include a series of inner rollers and lateral rollers arranged on the inner roller support arm, or the outer roller includes a series of outer rollers and lateral rollers arranged on the outer roller support arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In the following description, the present invention will be further explained by exemplary embodiments shown in the drawings:

[0081] Figure 1aIt is a side view of an embodiment of a reinforced metal plate.

[0082] Figure 1b It is a perspective view of an embodiment of a reinforced metal plate.

[0083] Figure 2a It is a side view of an embodiment of a reinforced metal plate welded to a second metal plate.

[0084] Figure 2b It is a perspective view of an embodiment of a reinforced metal plate welded to a second metal plate.

[0085] Figure 3 It is a side view of a first metal plate and a first metal reinforcement element during bending and subsequent welding of the first metal reinforcement element at an angle β.

[0086] Figure 4 It is a perspective view of an embodiment of a reinforced metal plate bent into a helix and subsequently welded at the seam.

[0087] Figure 5 It is a side view of an embodiment of a reinforced metal plate bent into a helix and subsequently welded at the seam at an angle α.

[0088] Figure 6 It is a perspective view of a first embodiment of a bending machine

[0089] Figure 7 It is a perspective view of a second embodiment of a bending machine

[0090] Figure 8 It is a perspective view of an embodiment of a first metal plate bent into a helix and subsequently welded at the seam.

[0091] Figure 9 It is a perspective view of a first embodiment of a series of first metal reinforcement elements and spacers welded to a first metal plate

[0092] Figure 10 It is a perspective view of a second embodiment of a series of first metal reinforcement elements and spacers welded to a first metal plate

[0093] Figure 11 It is a front view of a bending machine including spacers

[0094] Figure 12 It is a perspective view of a series of first metal reinforcement elements and a first metal plate passing through a bending machine including spacers

[0095] Figure 13 It is a detailed view of a series of first metal reinforcement elements and a first metal plate passing through a bending machine including spacers.

[0096] Figure 14Detailed view of a series of first metal reinforcement elements and a first metal plate passing through a bending machine, the bending machine including a series of vertical and lateral rollers arranged on inner roller support arms.

[0097] Figure 15 Top view of an embodiment in which a series of first metal reinforcement elements are longitudinally welded to a first metal plate, the first metal plate being fed into the bending machine at a feed angle, each inner roller being arranged on an inner roller support arm, the axis of rotation of which is arranged at an angle δ (delta) relative to the longitudinal axis of the helix.

[0098] Figure 16 Top view of an embodiment in which a series of first metal reinforcement elements are welded to a first metal plate 1 at an angle orthogonal to the longitudinal axis of the helix, the metal plate being fed into a bending machine including a helical inner roller.

[0099] Figure 17 Perspective view of a flat plate bent into a helix and welded to other elements to form a reinforced tube. Detailed description of the embodiments

[0100] In the design of offshore floating wind farms, reducing the weight of materials is necessary to ensure low-cost energy production. At the same time, the structure needs to maintain its strength in order to withstand environmental mechanical stresses.

[0101] Therefore, new structures with an increasingly large ratio of tube diameter to wall thickness have been developed, especially buoyancy tanks. For example, it is not uncommon to use buoyancy tanks with a diameter greater than 11 m and a wall thickness of only about 20 mm.

[0102] For tubes with a relatively large ratio of tube diameter to wall thickness, traditional production methods are associated with problems related to buckling of the plate due to the gravitational force acting on the plate during bending. Additionally, welding rings after forming the complete tube is a complex, time-consuming, and expensive operation.

[0103] Therefore, in order to mitigate the problems of existing methods, new production methods have been developed.

[0104] Traditional techniques for manufacturing reinforced tube sections or tubes include first bending a metal plate, then forming a tube, and then welding metal reinforcement elements to the formed cylinder.

[0105] Here, the person skilled in the art will understand that the method can be used to form tubes, such as cylinders and conical cylinders. A conical cylinder is equivalent to a frustum. The method is also suitable for forming partial cylinders or partial conical cylinders.

[0106] The person skilled in the art will also understand that any type of welding can be used here, including tack welding before performing the final welding at a later stage.

[0107] Examples of such methods are shown, for example, in Figure 5 and Figure 8 In other figures, details and alternatives are shown. Specifically, the method of the present invention proposes to bend a metal plate 1 along a bending line to form a helix, where the pitch of the helix is substantially equal to the width of the plate, and where two consecutive turns of the helix contact (or are placed in contact) at a seam 20; welding the helix 30 along the seam 20 to form a tube; and welding at least one first metal reinforcing element to the tube to form a reinforced tube 10.

[0108] Here, those skilled in the art will understand that at least one reinforcing element 2 can generally be any reinforcing element conventionally used in the oil and gas industry, in particular beams, such as T-beams and U-beams.

[0109] Due to the method of the present invention, the metal plates 1 will be able to support their own weight during the bending step, and the risk of buckling will be at least reduced or even eliminated.

[0110] In addition, the method allows the process for manufacturing the reinforced tube 10 to be continuous. In particular, it allows the process for manufacturing a complete reinforced tube (i.e., a tube of any desired length) to be continuous.

[0111] Here, at least one reinforcing element 2 can be bent together with the first metal plate 1, or at least one reinforcing element 2 can be placed on the first metal plate 1 after bending the first metal plate 1.

[0112] At least one reinforcing element 2 can also be welded to the first metal plate before (when there is at least one reinforcing element 2) or after the bending step.

[0113] First Example:

[0114] In a first step, a series of parallel reinforcing elements 2 (here T-beams) are first welded to a flat plate 1 to form a reinforced flat plate 3 as shown in Figure 1a and Figure 1b Then the reinforced flat plate 3 is passed through a bending machine 50 to form a helically reinforced tube or helix 30, and where the T-beams also form a helix. As shown in Figure 4 and Figure 5 Using a welding arm 59, for example, the seam 20 of the helix 30 is welded at an angle α of 10° with respect to the bending line (i.e., the line on the metal plate along which the metal plate is bent); where 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 the bending line) and a second radius of the helix starting from the welding point. The formed helix is supported by one or more support rollers 70.

[0115] Second Example

[0116] In a first step, a series of reinforcing elements 2 (here shear webs) are welded to a first flat aluminum plate 1 and then to a second aluminum plate 5 such that a shear web is included between the first plate 1 and the second plate 5 and such that the first aluminum plate 1 and the second aluminum plate 5 are parallel. This results in a double flat deck (or double skin), as Figure 2a and Figure 2b shown. Then, the double flat deck is passed through a bending machine to form a helically reinforced tube or helix 30. For example, a welding arm is used to weld the seam 20 of the helix 30 at an angle α of 45° to the bending line.

[0117] Third Example

[0118] In a first step, a series of parallel first reinforcing elements 2 (here T-beams) are welded to a flat plate 1. A series of parallel second reinforcing elements 4 (also here T-beams) orthogonal to the series of first reinforcing elements 2 are also welded to the flat plate 1, thereby forming a reinforced metal plate 3, with the second reinforcing elements 4 perpendicular to the first reinforcing elements 2.

[0119] Then, the reinforced metal plate 3 is passed through a bending machine 50 to form a helically reinforced tube or helix 30. For example, a welding arm is used to weld the seam 20 of the helix 30 at an angle α of 45° to the bending line.

[0120] Fourth Example

[0121] In a fourth example, a series of first reinforcing elements 2 are placed on a metal plate 1 (without welding). Then, the metal plate 1 and the reinforcing elements 2 are passed through a bending machine 50 to form a helically reinforced tube or helix 30. For example, a welding arm is used to weld or at least position-weld the seam 20 of the helix 30 at an angle α of 10° to the bending line. As Figure 3 shown, shortly after the plate 1 is bent, a series of first reinforcing elements 2 are welded (in other words, the welding occurs at a location shortly after or at the point of plastic bending of the plate). In other words, at a second angle β to the bending line (i.e., the line on the metal plate along which the metal plate is bent); and the angle β is defined between a first radius of the circle along which the metal plate is bent starting from the bending line and a second radius of the circle along which the metal plate is bent starting from the welding point (of the metal reinforcement 2). Here( Figure 3)At an angle β of approximately 85° of the curved line. For submerged arc welding, the optimal welding position is vertically downward, so the preferred angles α are close to 0 degrees or 360 degrees or 720 degrees, etc., for welding from the inside of the pipe, and close to 180 degrees, 540 degrees, etc., for welding from the outside of the pipe. In this example, the main welding of the seam 20 is carried out from the inside at an α of approximately 10 degrees, and the back welding of the seam 20 (which is a smaller weld to avoid root defects in the finished weld) is carried out from the outside at a β of 180 degrees.

[0122] In this example, the seam is welded first, and then the first reinforcing element 2 is welded, i.e., α < β. α = β or α > β is also possible.

[0123] Fifth Example

[0124] In the first step, a single reinforcing element 2 (here a U-shaped beam) is first welded to the flat plate 1 to form a reinforced metal plate 3. Then the reinforced metal plate is passed through a bending machine 50 to form a helically reinforced pipe. After forming a pipe of appropriate size (here, for example, a pipe with a diameter of 10 m, a thickness of 25 mm, and a length of 40 m), the ends are cut so that the pipe has a cylindrical shape.

[0125] Here, the distance between two first metal reinforcing elements 2 can generally be 500 - 2000 mm.

[0126] Sixth Example

[0127] In the first step, the metal plate 1 is passed through a bending machine 50 to form a helical pipe or helix 30. After the first turn, for example, a welding arm is used to weld the seam 20 of the helix 30 at an angle α of 10° of the curved line. At least one metal reinforcing element 2 is independently manufactured to form a complete circle or substantially a complete circle, and as Figure 8 shown, it is laterally positioned inside the welding machine 50 on the sides of the rollers 51, 52. Then, after the first metal plate 1 is bent by at least 360 degrees using the bending machine, that is, starting from the second turn, at least one first metal reinforcing element 2 is welded onto the first helix 30 to form a reinforced pipe 10. In other words, the formed pipe segment is still at least partially in the bending machine 50. Therefore, as Figure 8 shown, the bent metal plate 1 is structurally supported by adjacent parts of the finished helically reinforced pipe segment with the metal reinforcing element installed during the bending operation to prevent collapse.

[0128] Seventh Example

[0129] In the seventh example, as Figure 13As shown, a series of lower abdominal plate members 64 are welded to the metal plate 1, and a series of first reinforcing elements 2 are placed on top of the web members 64 (without welding). Then, as Figure 3 shown, the metal plate 1 together with the web members 64 and the reinforcing elements 2 is passed through a bending machine 50, and is welded together at the intersection 63 shortly after the plate 1 is bent together with the lower abdominal plate members 64 and the reinforcing elements 2 (in other words, the welding occurs at a position shortly after the point where the plate 1, the lower abdominal plate members 64, and the reinforcing elements 2 are plastically bent). In other words, after plastic bending, at the angle β of the bending line, welding the reinforcing element 2 (which has a reduced web height in this example) to the plate 1 including the lower part of the lower abdominal plate membrane 64 further reduces the combined bending stiffness of the metal plate 1 and the reinforcing element 2 during the bending operation, thereby reducing the total bending force required and the risk of buckling of the reinforcing element during the bending operation, and reducing the post-bending plastic (and permanent) strain in the bent material. A high level of plastic strain may initiate microcracks in the material and thus reduce the fatigue strength of the bent material, so it should be expected to be reduced as much as possible during manufacturing.

[0130] Eighth Example

[0131] Now referring to Figure 17 , in the eighth example, the flat plate 1 is passed through a bending machine 50 to form a spiral tube or helix 30. Additionally, at least one reinforcing element 2 is independently manufactured or bent to form an arc, a complete circle, a substantially complete circle, or a helix (as Figure 17 shown), and is positioned on the outer surface area of the spiral tube or helix 30. Then, after the flat plate 1 is bent at least 360 degrees using the bending machine 50, that is, starting from the second turn, at least one reinforcing element 2 is welded to the outer surface area of the first helix 30, thereby forming the reinforced tube 10.

[0132] The advantage of having the reinforcing element 2 on the outer surface area of the formed reinforced tube 10 is that the second metal plate 5 can be independently bent and more easily welded to the reinforcing element 2 to produce a double flat layer (or double shell layer), which further strengthens the reinforced tube 10.

[0133] Ninth Example

[0134] In the ninth example, a spiral reinforced tube or helix 30 is prepared as in the eighth example. After that, the second metal plate 5 is bent and then welded to the reinforcing element 2 formed on the outer surface area of the spiral reinforced tube or helix 10 to form a double layer (or double shell layer).

[0135] Independently of the above examples, when at least two first metal reinforcing elements 2 are placed on the first metal plate 1, the at least two first metal reinforcing elements 2 are advantageously parallel, and the distance between the at least two first metal reinforcing elements 2 is between 1 / 50 and 1 / 4 of the tube bending diameter D, preferably between 1 / 30 and 1 / 6 of the tube bending diameter D.

[0136] In the same spirit, when at least one first metal reinforcing element 2 is helical, the pitch of the helix is between 1 / 50 and 1 / 4 of the tube bending diameter D, preferably between 1 / 30 and 1 / 6 of the tube bending diameter D.

[0137] These segments can then be assembled together and welded to form longer cylindrical or conical cylindrical segments.

[0138] Those skilled in the art will understand that for the first and last parts of the reinforced tube 10, the metal plate can be cut before the bending operation so that the tube ends come out of the bending machine, without the need to cut the metal plate after the bending operation in order to make the cylinder ends orthogonal to the longitudinal axis of the tube.

[0139] Bending machine

[0140] In one example, the bending machine 50 includes a pair of outer rollers 52 and an inner roller 51.

[0141] The bending machine may also include welding arms 59 as Figure 4 and Figure 5 shown. The welding arms can be used to weld the helix 30 along the seam 20.

[0142] As Figure 6 and Figure 7 shown, in this bending machine 50, the inner roller 51 is adapted to bend both the metal plate 1 and the reinforcing element 2 simultaneously before the metal plate 1 and the reinforcing element 2 are welded together, or in the bending machine 50, the inner roller 51 is adapted to bend the reinforced bending plate 3 (i.e., the metal plate 1 welded to at least one first reinforcing element 2).

[0143] The inner roller 51 is not flat, but includes a cylinder (or conical cylinder) with at least one first groove 55 for receiving at least one first reinforcing element 2. The depth of the at least one first groove 55 is preferably equal to the height of the at least one first reinforcing element 2. In this way, the force applied by the inner roller 51 is distributed over the metal plate 1 and the at least one first reinforcing element 2, rather than only over the at least one first reinforcing element 2, thus reducing the risk of buckling of the at least one first reinforcing element 2.

[0144] The at least one first groove 55 is arranged on the circumference around the inner roller 51.

[0145] The inner roller 51 can be a solid piece, or alternatively it can be a cylinder covered by a series of discs.

[0146] It should be understood that when forming the helical reinforcing tube or helix 30 with the reinforcing element 2 formed on its outer surface region, for example in the above examples 8, 9 and 10, at least one first groove 55 must be arranged on the outer roller 52 rather than on the inner roller 51 to accommodate at least one first reinforcing element 2.

[0147] As Figure 7 shown, if the reinforcing plate 3 includes at least one first reinforcing element 2 and at least one second reinforcing element 4 perpendicular to at least one first reinforcing element 2, the inner cylinder 51 includes at least one first groove 55 for accommodating at least one first reinforcing element 2 and at least one second groove 56 for accommodating at least one second reinforcing element 4. The depth of at least one first groove 55 and the depth of at least one second groove 56 are preferably equal to the height of at least one first reinforcing element 2 and the height of at least one second reinforcing element 4 respectively. In this way, the force exerted by the inner roller 51 is distributed over the metal sheet 1, at least one first reinforcing element 2 and at least one second reinforcing element 4, rather than only over at least one first reinforcing element 2 and / or at least one second reinforcing element 4, thereby reducing the risk of buckling of at least one first reinforcing element 2 and / or at least one second reinforcing element 4.

[0148] At least one first groove 55 is arranged on the circumference around the inner cylinder (or tapered inner cylinder). At least one second groove 56 is arranged longitudinally along the outer surface of the inner roller 51.

[0149] The bending machine 50 can advantageously be mounted such that the central axis of the inner roller is orthogonal or parallel to the axis of gravity. In this example, the metal sheet 1 will be wound around the inner roller 51 during the generation of the helix. Therefore, in order to move the helix 30 along the longitudinal axis of the helix 30, it will be necessary to lift the outer roller 51. Therefore, for this embodiment, the production of the helical reinforcing tube needs to be carried out step by step.

[0150] It should be understood that when forming the helical reinforcing tube or helix 30 with the reinforcing element 2 formed on its outer surface region, for example in the above examples 8, 9 and 10, at least one first groove 55 and at least one second groove 56 must be arranged on the outer roller 52 rather than on the inner roller 51 to accommodate at least one first reinforcing element 2 and at least one second reinforcing element 4.

[0151] In a second example of the bending machine 50, the disadvantages of stepwise production of the helical reinforcing tube 30 are avoided. In this example, the bending machine is arranged in the same manner as described above, but the difference is that the groove on the inner roller 51 is a helical groove, so that the metal sheet 1 does not roll up around the inner roller 51 during the continuous production of the helix. Here, the helical grooves are arranged at intervals adapted to the diameter of the roller, the distance between each reinforcing element 2, and the feed angle 76. In this way, the reinforcing element 2 does not collide with the helical groove during the continuous manufacture of the helical tube 30. By arranging the reinforcing element 2 orthogonally to the longitudinal axis of the produced helical tube 30 as shown in Figure 16 and making the distance between each reinforcing element 2 equal to the circumference of the helical tube 30 divided by a positive integer, the reinforced tube 10 can be produced by a helical welding method, and still keep the respective orthogonal reinforcing elements 2 spaced apart inside the tube. That is, in this example, the reinforcing element 2 will not be helical, but a closed circle spaced orthogonally to the longitudinal axis of the helical tube 30.

[0152] In a third example of the bending machine 50, as shown in Figure 14 , the bending machine is arranged in the same manner as described in the first example of the bending machine 50 above, but the inner roller 51 includes a series of inner rollers 61 and lateral rollers 62 arranged on the inner roller support arm 73. As shown in Figure 15 , a series of first metal reinforcing elements 2 longitudinally welded to the first metal sheet 1 are fed into the bending machine 50 at a feed angle 76. The respective inner rollers 61 are arranged at intervals along the bending line substantially parallel to the longitudinal axis 77 of the helix 30 on the inner roller support arm 73. The respective inner rollers 61 are also arranged on the inner roller support arm 73 with a substantially horizontal axis of rotation arranged at an angle δ (delta) with respect to the longitudinal axis 77 of the helix 30. The rotation angle δ (delta) can be arranged to be self-adjustable (similar to the wheels of a supermarket cart) to allow the metal sheet 1 to be freely fed into the bending machine forming the helix 30 without resisting the forward movement along the axis 77 during the production of the helix 30. As shown in Figure 14 , a lateral spacer including lateral rollers 62 is arranged on the inner roller 61 to support at least one first metal reinforcing element 2 during the plastic bending of the first metal reinforcing element 2. To ensure the stability of the roller, at least 2 lateral rollers 62 are arranged on each side of each inner roller 61.

[0153] It should be understood that when forming a helical reinforcing tube or helix 30 with a reinforcing element 2 formed on its outer surface area, for example, in the above examples 8, 9, and 10, it is the outer roller 52 that includes a series of outer rollers and lateral rollers arranged on the outer roller support arm.

[0154] When manufacturing the spiral tube according to the present invention, if the tube is long, during the proposed manufacturing process, the diameter D of the tube may vary slightly (bit by bit). During the manufacture of the tube, it may also be necessary to transition from a straight section to a tapered section. To control the tube diameter D, if the tube is manufactured in the horizontal direction as shown, the central longitudinal axes of both the inner roll and the outer roll are adjusted relative to the longitudinal axis of the tube. By relatively tilting the rolls 51, 52 about a horizontal axis positioned orthogonally to the longitudinal axis of the tube, the distal ends of the rolls (the ends pointing away from the manufactured cylinder) are raised (and thus become closer to the central axis of the tube 10). As the bending operation continues, the tube diameter D will decrease in a way that makes the tube tapered inward. To increase the tube diameter D, the opposite tilt of the rolls 51, 52 is performed. Since the important feature for controlling the diameter D is the position of the central axis between the said rolls 51, 52 relative to the longitudinal axis of the tube 10, this relative adjustment can be carried out by tilting the inner / outer rolls, or by tilting the tube 10 by adjusting the height of the support rolls 70 of the tube. Adjusting the support rolls of the tube can be carried out by jacking these supports up or down. When the tube is rolled and welded to the rest of the tube, jacking up to tilt the tube will start to decrease the tube diameter D. When the tube is rolled and welded to the rest of the tube, jacking down to tilt the tube will increase the diameter D.

[0155] When adjusting the tube diameter D, it is also necessary to adjust the pitch of each helix by adjusting the feed angle 76 of the metal sheet 1 entering the bending machine 50. Therefore, the diameter D will depend on the pitch of the helix and the feed angle.

[0156] When bending the metal sheet 1 and the strengthening element 2, there is a risk that the strengthening element may buckle. One way to reduce the buckling risk is to increase the width between the two outer rolls 52 in order to increase the effective bending arm, thereby reducing the force required for the rolls 51, 52 to plastically bend the sheet 1 and the strengthening element 2.

[0157] In other words, in order to reduce the force applied to the sheet 1 welded with the strengthening element 2, the space between the outer rolls 52 of the bending machine 50 can be increased.

[0158] Another alternative for reducing the buckling risk is to use at least two spacers 60. As Figure 9 and Figure 10 shown, the spacers are objects that can be placed on each side of at least one first strengthening element 2 and between the first metal sheet 1 and the inner roll 51. Preferably, wherever the inner roll contacts the first metal sheet and at least one first strengthening element, these at least two spacers 60 are along the bending line and even more preferably cover the width of the first metal sheet 1 on each side of the bending line.

[0159] Depending on the number of the first reinforcing elements 2 and their placement on the first metal plate 1, there can be a plurality of spacers with different widths. In other words, the width of the spacer 60 is the distance between two reinforcing elements 2 or between a reinforcing element 2 and the side of the first metal plate 1.

[0160] Preferably, each of at least one first reinforcing element 2 is intended to be included between at least two spacers, such that the spacers will prevent buckling during the bending step c).

[0161] The at least two spacers 60 can be of any suitable shape complementary to the shape of at least one first reinforcing element 2, such that as Figure 9 and Figure 10 shown, the cross-section of the shape of the at least two spacers 60 and the cross-section of the shape of the first reinforcing element 2 can be substantially rectangular, having substantially the same width as the first metal plate 1 and substantially the same height as at least one first reinforcing element 2.

[0162] In the case where at least one first reinforcing element 2 is a T-beam or a U-beam, the at least two spacers 60 can be cuboids.

[0163] The at least two spacers 60 can be freestanding. That is, they are not necessarily attached to a support structure or the like.

[0164] Preferably, as Figure 11 and Figure 12 shown, the at least two spacers 60 can include vertically acting spacer rollers 61, which transfer the pressure of the inner roller 51 to the first metal plate 1.

[0165] Preferably, the at least two spacers 60 can further include laterally acting spacer rollers 62 to prevent buckling of at least one first reinforcing element 2.

[0166] Each roller 61, 62 can be freely rolling or can have a motor driving them.

[0167] It should be understood that the individual drive rollers used in known techniques for spiral welding of pipes and any other features known to those skilled in the art of spiral welding of pipes can be used in conjunction with the present invention.

[0168] In the case where at least one first reinforcing element 2 is a T-beam, the at least two spacers 60 should be designed to avoid buckling of all parts of the T-beam (i.e., both the shear web and the flange), as in the examples using (one or more) rollers ( Figure 10 , Figure 11 or Figure 12 ) or cuboids ( Figure 9 ) as described above.

[0169] It should be understood that when forming a helically reinforced tube or helix 30 with a reinforcing element 2 formed on its outer surface region, for example, in Examples 8, 9, and 10 above, at least two spacers 60 are preferably placed on each side of at least one first reinforcing element 2 and between the first metal sheet 1 and the outer roller 52.

[0170] The bending machine 50 is not always able to apply a bending moment to the ends of the article to be bent, so it is not possible to permanently and plastically bend those ends. Due to this difficulty, the ends of the metal sheet 1 are usually not bent when the sheet 1 is bent. Usually, the non-bent end portions of the sheet 1 are cut off before being welded together to form a tube such as a cylinder.

[0171] To further improve the method, one or both end portions of the sheet can be bent in a first step before placing the reinforcing element 2 on the metal sheet 1. Additionally, at least one reinforcing element 2 can be shaped or cut at one or both end portions such that at least one reinforcing element 2 can be easily placed on the sheet 1 (with one or both bent end portions).

[0172] Thus, the metal sheet 1 has end portions shaped like skateboard tips, which do not need to be plastically bent to become part of the final circular or substantially circular shape of the produced tube cross-section, because the sheet 1 and the reinforcing element 2 and their respective end cross-sections will have substantially the same curvature after passing through the bending machine, thus forming a substantially circular cross-section.

Claims

1. A method for manufacturing a reinforced tube (10), which comprises the following steps: a) providing a first metal plate (1) having a thickness t; b) bending the first metal plate (1) along a bending line to form a helix (30), wherein the pitch of the helix (30) is substantially equal to the width of the plate; and wherein two consecutive turns of the helix (30) contact at a seam (20); c) welding the helix along the seam (20) to form a tube; and d) welding at least one first metal reinforcing element (2) to the tube, thereby forming a reinforced tube (10).

2. The method according to claim 1, wherein the reinforced tube (10) has a diameter D, and the ratio D / t is included between 100 and 1500, preferably included between 200 and 800.

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

4. The method according to claim 1, 2 or 3, wherein in step d), the at least one first metal reinforcing element (2) is welded within 400° of the bending line.

5. The method according to any one of the preceding claims, wherein the at least one first metal reinforcing element (2) is helical with an outer diameter the same as the inner diameter of the reinforced tube (10), or wherein the at least one first metal reinforcing element (2) is helical with an inner diameter the same as the outer diameter of the reinforced tube (10).

6. The method according to any one of claims 1 to 4, wherein the at least one first metal reinforcing element (2) is circular with an outer diameter the same as the inner diameter of the reinforced tube (10), or wherein the at least one first metal reinforcing element (2) is circular with an inner diameter the same as the outer diameter of the reinforced tube (10).

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

8. The method according to claim 7, wherein the at least two first metal reinforcing elements (2) are parallel to each other.

9. The method according to claim 8, wherein the distance between the at least two first metal reinforcing elements (2) is between 1 / 50 and 1 / 4 of the tube diameter, preferably between 1 / 30 and 1 / 6 of the tube bending diameter D.

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

11. The method according to any one of the preceding claims, which further comprises the following steps: e) welding at least one second metal reinforcing element (4) to the first metal plate (1) at an angle to the at least one first metal reinforcing element (2).

12. The method according to claim 10, wherein the at least one second metal reinforcing element (4) is perpendicular to the at least one first metal reinforcing element (2).

13. The method according to any one of the preceding claims, wherein the at least one first metal reinforcing element (1) is a T-shaped beam or a U-shaped beam.

14. The method according to any one of the preceding claims, comprising bending the first metal plate (1) to form at least two turns of the helix (30).

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

16. The method according to any one of the preceding claims, further comprising the step of welding at least one lower abdominal plate member (64) to the first metal plate (1), and wherein the at least one first metal reinforcing element (2) is placed on top of the at least one lower abdominal plate member (64) and welded together after the at least one lower abdominal plate member (64) and the at least one first metal reinforcing element (2) have been bent together with the first metal plate (1).

17. The method according to any one of claims 1 to 4 or 6 to 15, further comprising the steps of: - providing at least one prefabricated first metal reinforcing element (2) which forms a complete circle or substantially a complete circle, and - positioning at least one first metal reinforcing element (2) inside or outside the helix formed by the bent metal plate after bending at least one complete turn of the helix but before bending the complete first metal plate.

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