Flange

Abstract

The invention describes a flange for connecting to a complementary flange, and wherein the flange comprises a first flange section and a second flange section, wherein: a) the first flange section comprises: a main bolt circle comprising an annular arrangement of inclined openings; and a first annular connection face adapted to abut against a complementary second annular connection face of the second flange section; and b) the second flange section comprises: annular connection faces on two opposite sides adapted to abut against a complementary annular connection face; a main aperture circle comprising an annular arrangement of openings; and a second main body section having a secondary bolt circle comprising an annular arrangement of openings. The invention also describes corresponding flange sections, a method for manufacturing such a flange, and a tower construction.

Description

Technical Field

[0001] The invention describes a flange for connection to a complementary flange, special elements of the flange and a method of constructing such a flange. Background Art

[0002] Tall towers, such as wind turbine towers, are usually constructed by connecting tower sections together. To this end, each tower section is provided with a flange. A common flange shape is an "L-flange", and complementary L-flanges are connected together by fasteners, such as bolts, arranged in a bolt circle. Tower sections can be manufactured with L-flanges with an inner bolt circle (i.e. the flange extends into the interior of the tower) or an outer bolt circle (i.e. the flange extends outwards from the tower).

[0003] Large wind turbines of the type currently being developed have very long rotor blades and therefore require taller towers. However, the limited load-bearing capacity of the commonly used L-flange connections imposes constraints on the tower structure.

[0004] In order to provide a better flange connection, so-called X-flanges have recently been used. The key feature of these new flanges is the ability to transfer much higher loads than the conventional (L-shaped) flanges described above. The first conception of the X-flange is described, for example, in patent NLC1004960. The X-flange is usually combined with the L-flange to form an "XL-flange", i.e. a flange with an L-shaped aperture circle (usually an inner circle) and an X-shaped aperture area. Therefore, the XL-flange is a special variant of the X-flange.

[0005] The flange is usually machined from a forged ring of, for example, 6-8 mm diameter, and has a rectangular cross section of, for example, 400×400 mm (see, for example, Figure 1 First, machining allowance is removed from the forging to ensure that all surface defects are removed, after which the product is formed on a large turntable. XL flanges require larger forgings than L flanges, and larger forgings mean more steel, and therefore more raw material cost.

[0006] The reason why the XL flange requires a larger forging is that the L-shaped extension ( Figure 1 The right part of the forged ring) increases the width of the forged ring. Since the L-shaped part has a height restriction (due to design rules), a lot of material must be machined away (see Figure 1 ). Due to the size of the weld neck, this wasted portion cannot be reduced as the height of the weld neck is quite large. This is due to the requirements of non-destructive testing (NDT) (inspection) of welds. Sufficient space is required under the weld to place the probe with which the ultrasonic signal is sent.

[0007] Therefore, while the XL flange solves many challenges (such as providing an interface to connect to, reducing equipment costs), it does have the disadvantage of being larger and more expensive due to the larger original components and delicate manufacturing process. Summary of the invention

[0008] It is therefore an object of the present invention to provide an improved flange connection which overcomes the above mentioned problems.

[0009] This object is achieved by a flange, a first flange segment, a second flange segment, a method for assembling a flange and a tower according to the invention.

[0010] The flange according to the invention is suitable for being connected to a complementary flange (two flanges are usually connected to each other) and comprises a first flange section and a second flange section. The two flange sections can be connected to each other, for example, by bolts or screws, welding or an adhesive layer, however, they can also be connected during the connection with the complementary flange.

[0011] a) The first flange segment includes the following features:

[0012] - a main bolt circle comprising an annular arrangement of inclined openings (so as to create an X-shaped flange) suitable for receiving a set of fasteners for connecting said flange to said complementary flange.

[0013] - a first annular connection surface which abuts against a complementary second annular connection surface of the second flange segment. The annular connection surfaces of the two flange segments should be custom-fitted to each other, e.g. have a flat shape or at least a corresponding shape, wherein one connection surface is the negative form of the other connection surface. Obviously, the expression "annular connection surface" refers to the flange facing surface and not the circumferential surface.

[0014] b) The second flange segment includes the following features:

[0015] - It has on one side a second annular connection surface which is adapted to abut against a complementary first annular connection surface of the first flange segment.

[0016] - it has a third annular connection surface on the opposite side, which is suitable for abutting against the complementary annular connection surface of the complementary flange or the complementary annular connection surface of another first flange segment. The three connection surfaces are thus "stacked" on each other. With regard to the connection of two flanges according to the invention to each other, there is a first flange segment at the bottom, whose first connection surface is contacted on top by the second connection surface at the bottom of the second flange segment, whose third connection surface is contacted on top by the third connection surface at the bottom of another second flange segment, whose second connection surface is again contacted on top by the first connection surface at the bottom of another first flange segment.

[0017] - a first body section having a main aperture circle comprising an annular arrangement of openings designed to allow the passage of a set of fasteners for connecting the flange to a complementary flange or to another first flange segment, to and from the main bolt circle of the first flange segment. Thus, the apertures of the main aperture circle should correspond to the inclined openings of the main bolt circle of the first flange segment, so that when the two flange segments are arranged on each other, bolts can be pushed through both. The apertures of the main aperture circle can be inclined or straight, as long as the bolts fit correctly.

[0018] - A second body section having a secondary bolt circle comprising an annular arrangement of openings to receive a set of fasteners for connecting the flange to an intermediate structure or to the complementary flange. This is an L-shaped section of the flange. This L-shaped section is only part of the second flange section and not part of the first flange section, as this makes the flange much cheaper to manufacture due to the smaller and regular cross-section of the flange section.

[0019] By using two separate flange sections, i.e. "splitting" the flange into two parts, the total material that must be removed from the forging is much less than a conventional XL flange, and the original part forged is smaller, making the forging process easier, as thick forgings are more difficult and more expensive per kg to make than lighter forgings. Splitting the forging into two parts also opens up the way to allow NDT (inspection) from below the first flange section. Because it opens up a view of the weld from below. This potentially allows the size of the weld neck to be reduced, thereby further reducing the size of the forging.

[0020] It should be noted that the flange segment can be present with additional components, in particular rubber, slurry and / or adhesive, between two flange segments, such as additional thin layers. Furthermore, the flange segment can be further segmented, in particular the second flange segment. It can be segmented perpendicular to the aperture of the second bolt cycle (or parallel to the connection surface), for example in the form of a layer stack, or, for example, if the main aperture circle consists of only one annular aperture, segmented so that two or more concentric rings are formed. The further segmentation is described more precisely below.

[0021] The first flange section preferably comprises connection means, in particular welding necks, which are suitable for connecting the flange to the structural element.These connection means are preferably positioned on opposite sides of the first connection face.

[0022] Thus, the present invention allows the construction of flanges, in particular X-shaped flanges, particularly preferably XL-shaped flanges, from two parts. As described above, this greatly reduces the amount of machining, material waste and forging size. According to the present invention, the top and bottom parts (first and second flange segments) will require relatively small forgings. Now, it is also possible to perform less drilling and tapping at a certain angle (depth reduction), which is one of the most expensive production steps. The second flange segments of the corresponding flanges are almost the same, except that their orifices (e.g. slotted holes) can be alternated. However, the same flange segments can be arranged to be slightly twisted for matching. This improves the structural integrity of these rings. The size of the (slotted) orifices of the main orifice circle can be increased and made equal, that is, the width of these holes will increase, removing more material from the middle ring. Slotted holes are easier to machine (or, for example, cut with a water jet, plasma or oxyfuel) than drilling inclined holes. This saves costs. Another embodiment can use an outer ring and an inner ring, wherein the main orifice circle is the distance between these rings.

[0023] Additionally, "thin" forgings offer better material properties due to the way the steel cools and crystallizes. Thinner forgings are also easier to make due to the need for smaller ingots, less heating, smaller possible presses, and shorter cooling times, thus favoring one large thick forging.

[0024] The first flange section according to the invention is designed for the flange according to the invention. The first flange section comprises the following components (see also the corresponding description of the flange):

[0025] - a main bolt circle comprising an annular arrangement of inclined openings for receiving a set of fasteners for connecting said flange to said complementary flange.

[0026] - a first annular connecting surface adapted to abut against a complementary second annular connecting surface of a second flange section of the flange.

[0027] The second flange section according to the invention is designed for the flange according to the invention. The second flange section comprises the following components (see also the corresponding description of the flange):

[0028] - a second annular connecting surface on one side, which is adapted to abut against a complementary first annular connecting surface of a first flange section of the flange.

[0029] - a third annular connection surface on the opposite side, intended to abut against the complementary annular connection surface of the complementary flange or against the first annular connection surface of another first flange segment.

[0030] - a first main body section having a main orifice circle, the main orifice circle comprising an annular arrangement of openings designed to allow a set of fasteners to pass through for connecting the flange to the complementary flange, reaching the main bolt circle of the first flange section and connecting the flange to the complementary flange from the main bolt circle of the first flange section.

[0031] - a second body section having a secondary bolt circle comprising an annular arrangement of openings for receiving a set of fasteners for connecting said flange to an intermediate structure or to said complementary flange.

[0032] The method for assembling a flange according to the invention comprises the following steps (not necessarily in this order):

[0033] - Connecting said first flange section to a cylindrical tower section of the tower, for example by welding, screwing or riveting.

[0034] - Connecting the second flange section to the first flange section, in particular using connecting bolts. The number of bolts required and their size depends on the amount of shear load that needs to be transmitted. Obviously, the two flange sections meet with their connecting surfaces (the first connecting surface contacts the second connecting surface).

[0035] It is further preferred that a (thin) intermediate layer is arranged between the first flange section and the second flange section. Such an intermediate layer can compensate for defects of the annular connecting surface and can improve the contact and bonding between the two connecting surfaces.

[0036] The tower according to the invention is preferably suitable for wind turbines, but can also be used for other applications, such as monopiles or simple towers. It comprises a plurality of essentially cylindrical tower sections, which are equipped with flanges according to the invention, which are permanently connected by fasteners inserted through inclined openings in the main bolt circle of the flanges. The flanges can be between two adjacent tower sections, but can also be used as a transition piece to connect the base frame with the (bottom) tower section or the upper tower section with the nacelle or another structure on top of the tower.

[0037] In the following, for the sake of simplicity, but without limiting the invention in any way, it may be assumed that the tower section is a wind turbine tower section. However, this is by way of example only and does not limit the general use of any kind of tower built from a plurality of sections. The tower section may also be referred to as a "tower shell". An embodiment of the flange of the present invention is a "part" of the tower section when the tower sections are connected. This should be understood to mean that the tower section and its flange may be considered as a single entity. The tower section and its flange may be formed as a single body. Likewise, the tower section and its flange may be manufactured separately and then joined, for example the flange may be welded to a steel tower shell, or the upright cylindrical portion of the flange may be embedded in the outer end of a concrete tower shell.

[0038] The main bolt circle and the main orifice cycle should be understood as the circle along which the openings are located at the flange connection face. The diameters of the main bolt circle and the main orifice cycle can be assumed to be similar to or equal to the average diameter of the tower section or tower shell. The inclined openings / (slotted) orifices of the main orifice cycle extend from the connection face into the body of the flange. The advantage of the main bolt circle is that the joint effectively "moves" into the tower shell, i.e. the forces applied by the tightened bolts are directed along an inclined path that intersects the average diameter of the tower shell. This means that loads are more effectively transferred from one tower shell to the next. In contrast, the vertical bolts of a conventional L-shaped flange are always at a certain distance from the average diameter of the tower shell, so that the load path is offset, resulting in a larger bending moment. The inclination should preferably be understood as adjacent bolts being arranged in an X-shape in the main bolt circle and the main orifice cycle.

[0039] The opening of the secondary bolt circle (L-shaped portion) can be assumed to be vertical in the conventional sense, i.e. perpendicular to the connecting face of the flange. For example, the secondary bolt circle is provided for connection to an intermediate structure, and the practical difficulties that would be associated with using the primary bolt circle (with its inclined opening) for this purpose can then be overcome.

[0040] The flange of the present invention, through its major and minor bolt circles, effectively provides structural strength comparable to that of a T-shaped flange without sacrificing the main advantage of an L-shaped flange, namely access to the major bolt circle from inside the tower. The L-shaped portion may also be used as an additional connection between the two flanges. The "intermediate structure" may be any device, such as a holding structure used during transportation of the tower section, a lifting interface used during installation of the tower section, etc.

[0041] The terms "flange" and "complementary flange" are understood in a general sense to mean flanges that are substantially identical, eg mirror images of each other, such that they can be connected together.

[0042] The tower section may be assumed to have a substantially cylindrical shape, e.g. a straight cylinder (although it may also have the shape of a prism). Likewise, the tower section may have a frustoconical shape, such that, for example, the diameter of its upper end is smaller than the diameter of its lower end. The tower section may be assumed to have a substantially circular cross-sectional shape. The tower section may be assumed to be "solid", i.e. have solid side walls, e.g. of steel or concrete, but the flange connection of the invention is not limited to tower sections having solid side walls.

[0043] Since the flange of the invention combines two types of bolt circles, namely a bolt circle with alternating inclined fasteners and a bolt circle known from an "L-flange", the flange of the invention can be referred to as an "XL-flange". The "XL-flange" has an advantageously high load-bearing capacity due to the alternating arrangement of the inclined bolts and because the bolts "cross each other" along a ring that is consistent with the tower shell diameter or at least very close to the tower shell diameter. This results in a more efficient load path, so that the type of prying moment that usually occurs in L-flange connections is substantially eliminated. The load-bearing capacity of the flange of the invention is comparable to that of a comparable "T-flange". However, unlike the "T-flange" of the prior art, the assembly of a tower using the "XL-flange" of the invention does not require access from the outside of the tower. This is because all fasteners or studs of the main bolt ring can be inserted from the inside of the tower. This aspect is particularly important for the assembly of towers in offshore locations or at locations where external cranes cannot be deployed to provide personnel access to the platform. A particular advantage of the flange of the present invention is that it provides an XL flange with all its advantages, but without the disadvantages of much of the waste, work and cost in manufacture.

[0044] Particularly advantageous embodiments and features of the invention are given by the dependent claims, as disclosed in the following description. Features of different claim categories may be combined as appropriate to give further embodiments not described herein.

[0045] The flange of the invention basically comprises a first flange section incorporating a primary bolt circle, and a second flange section incorporating a primary aperture circle (holes corresponding to the primary bolt circle, so that the bolts fit through both) and a secondary bolt circle. In the following, it may be assumed that the flange has the general shape of an "L", i.e. the second flange section of the flange is basically a lip or collar extending into the interior space of the tower section.

[0046] The inclined opening of the main bolt circle is characterized by an inclination angle θ subtended between its longitudinal axis and the surface normal of the flange connection face. In other words, the longitudinal axis of the main bolt circle opening is inclined relative to the vertical plane. In a preferred embodiment of the invention, this inclination angle θ measured relative to the vertical axis (or the mid-plane axis of the tower shell) is between 5° and 45°, preferably at least 10° and / or preferably at most 30°, particularly preferably between 15° and 25°.

[0047] In a particularly preferred embodiment of the invention, the main bolt circle includes an alternating arrangement of downwardly extending angled openings and upwardly extending angled openings. In a preferred embodiment of the invention, using an "upper" flange for discussion purposes, the downwardly extending angled openings extend through the flange to accommodate the shank of a fastener, which extends into the complementary angled opening of the lower flange, and the upwardly extending angled openings extend partially from the connecting face into the flange to accommodate the threaded end of the fastener, which extends into the flange from the "lower" flange.

[0048] The downwardly extending inclined openings are through holes, which are formed so that a fastener inserted through the flange extends into the inclined opening of the complementary flange. Thus, the downwardly extending inclined openings are "through holes" because they extend all the way through the body of the flange (continuing from the aperture of the main aperture circle).

[0049] The upwardly extending inclined openings are threaded openings formed to receive the threaded end of a fastener which is inserted into the flange via the inclined opening of the complementary flange and the main aperture circle of the second flange section of the present flange. The upwardly extending inclined openings are therefore "blind holes" because they terminate in the body of the flange.

[0050] When viewed from the contact surface, the flange thus shows a ring of openings. Every other opening is an "outlet" opening of an inclined through hole, while the other openings are "inlet" openings of a relatively inclined blind hole. To form a flange connection, the two flanges are arranged face to face so that each "outlet" opening is aligned with its paired "inlet" opening.

[0051] The preferred flange comprises an intermediate layer between the first annular connecting surface of the first flange segment and the second annular connecting surface of the second flange segment. Additionally or alternatively, the preferred flange comprises an intermediate layer on the third annular connecting surface. The intermediate layer preferably comprises a material from the group of rubber, silicone, epoxy resin, slurry and adhesive, in particular a material filled with metal particles. The intermediate layer should be relatively thin. Preferably, the thickness of the intermediate layer is less than 10 mm, preferably less than 5 mm, in particular less than 1 mm. In order to compensate for surface defects, the intermediate layer is preferably thicker than 0.001 mm, in particular thicker than 0.01 mm. The advantage of this intermediate layer between the flange segments and / or between the flanges is an improvement in the connection of the components, in particular with regard to surface defects and optimal load transfer.

[0052] Unlike the second flange segment which has not been welded and therefore has an original surface flatness which is not distorted by heat input and internal stresses, the first flange segment may suffer from welding it to the tower segment. As a result, the second flange segment can achieve a contact surface (second annular connection face) with an excellent flatness tolerance. This is good, since gaps or protrusions have a negative impact on the bolt life. However, the contact surface between the flange segments may suffer from gaps or protrusions on the first annular connection face of the first flange segment. However, these can be compensated with the layer, which is, for example, a slurry type layer, or with an epoxy resin filled with metal particles to bridge any gaps.

[0053] According to a preferred embodiment of the flange, the second flange segment has a substantially rectangular or wedge-shaped cross section with or without rounded edges. Alternatively or additionally, the second flange segment comprises a subsegment, such as a ring, having a substantially rectangular or wedge-shaped cross section with or without rounded edges. This has the advantage that the second flange segment or subsegment can be manufactured very easily without much waste. Another preferred shape of the second flange segment is a stepped or skewed cross section, in particular so that the first flange segment fits into a groove of an originally rectangular or wedge-shaped cross section of the second flange segment.

[0054] According to a preferred embodiment of the flange, the main bolt circle of the first flange section comprises an alternating arrangement of inclined through holes and inclined blind holes. This arrangement has been described above and has the advantage that the bolts can be arranged opposite each other in the X direction.

[0055] According to a preferred embodiment of the flange, the main aperture circle (corresponding to the opening of the main bolt circle) comprises slotted holes arranged longitudinally parallel to the radius of the annular connection face. With regard to the embodiment of the annular second flange section with a rectangular cross section, the slotted holes will be perpendicular to the connection face. The advantage of using slotted holes instead of conventional holes for fitting the bolts (which conventional holes must be inclined because the opening of the main bolt circle is inclined) is that they can receive inclined bolts even if the slotted holes themselves are not inclined.

[0056] Preferably, the hole of the slotted hole is colinear with the surface normal of at least one of said annular connecting faces, ie the hole is not inclined and is therefore very easy to manufacture.

[0057] It should be noted that it is very advantageous when the apertures of the main aperture circle of the second flange segment have no threads or blind holes, but preferably have smooth walls, so that the bolts can easily slide through them.

[0058] According to a preferred embodiment of the flange, the secondary bolt circle is outside the outer shape of the first flange segment. This means that the first flange segment neither covers nor includes the secondary bolt circle. Thus, the first flange segment is part of the vertical line of the L-shape, while the second flange segment forms the horizontal line of the L-shape. The holes in the "L-shaped part" only work if they are outside the outer shape of the first flange segment. Although the holes of the secondary bolt circle can be outside the flange, it is preferred that they face the inside of the flange connection (the inner part of the annular flange).

[0059] According to a preferred embodiment of the flange, an inclined through hole extends through the first flange section (and the aperture of the second flange section) to accommodate the shank of the fastener, which extends into the complementary blind hole of the complementary flange. Typically, the diameter of the fastener shank is slightly smaller than the hole diameter to simplify movement through the hole.

[0060] According to a preferred embodiment of the flange, the blind hole extends partially into the first flange section to accommodate the threaded end of a fastener extending into the flange after passing through the inclined through hole of the complementary flange.

[0061] Preferred embodiments of the flange include an alignment feature that is shaped to engage with an inverse alignment feature of a complementary flange. Such an alignment feature simplifies the correct placement of the two complementary flanges. The alignment feature preferably includes a plurality of guide pins, and the inverse alignment feature includes a plurality of holes designed to mate with the guide pins. The guide pins are very useful for guiding the flange into position, avoiding displacement during installation, and correcting the ovality of the flange.

[0062] According to a preferred embodiment of the flange, the second flange section is mounted to the first flange section by fasteners, preferably connecting bolts extending through openings, preferably perpendicular to the first and second connecting faces. These fasteners should not be misunderstood as bolts connecting two flanges. They are used to assemble a flange by connecting two flange sections and are additionally used to transfer shear loads. These bolts can replace the intermediate layer as described above or work together with the intermediate layer. Preferably, the first flange section includes a plurality of threads and the second flange section includes a plurality of corresponding holes designed to receive and hold the connecting bolts.

[0063] According to a preferred embodiment of the flange, the inner diameter of the first flange segment exceeds the diameter of the second flange segment.Thus, the second flange segment extends further into the center of the annular flange than the first flange segment (resulting in an L-shape).

[0064] Preferably, the outer diameters of the first flange section and the second flange section are the same.Thus, the two flange sections preferably have a flush fit at the outer side of the flange.

[0065] The secondary bolt circle can be based on a complete ring, or on an arcuate segment of a ring. When based on an arcuate segment of a circle, the second flange segment can be further segmented into angled sub-segments, for example each sub-segment is at an angle of 30° to the midpoint of the flange, where four such segments are evenly spaced around the inner periphery of the first body segment. Such an embodiment reduces material costs. Therefore, the second flange segment can be segmented into a plurality of (e.g., 4) quadrants. The quadrants are preferably drawn from thick plates, which has the advantage of saving costs compared to forging.

[0066] The second flange segment may be further segmented into a sub-segment that is a flat ring and is stacked on another sub-segment to form the second flange segment.

[0067] As described above, the second flange segment comprises a third annular connection surface which is adapted to abut against the complementary annular connection surface of the complementary flange or against the first annular connection surface of another first flange segment. This is because a flange connection can be made by means of a flange according to the invention with another flange according to the invention (a total of 2 first flange segments and 2 second flange segments) or with a conventional flange (1 first flange segment, 1 second flange segment and one conventional flange). Alternatively, the flange connection can be achieved by means of only one second flange segment and two first flange segments on each side of the second flange segment. With respect to this preferred embodiment, there are fewer segments in total, however, the main orifice circle must be adapted so that the bolts fit through the main bolt circles of the two first flange segments in order to bolt them together.

[0068] Hence, according to a preferred flange, the second flange segment comprises two or more sub-segments, preferably wherein the sub-segments are arcuate segments of a ring and / or rings stacked on each other and / or concentric rings.

[0069] In a preferred embodiment of the invention, a method of handling a tower section during tower assembly comprises the step of adjusting the two flanges by using a guide pin in one flange which is inserted through an opening in a complementary flange.

[0070] A further advantage of the invention is a lower risk of inconsistencies or additional tests due to better accessibility to functional structures and the possibility to perform NDT (phased array UT) from the surface below the weld neck. This can allow the height of the weld neck to be reduced, saving even more material. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed only for purposes of illustration and not as a definition of the limits of the present invention.

[0072] Figure 1A flange according to the prior art is shown.

[0073] Figure 2 A cross section of a preferred flange according to the invention is shown.

[0074] Figure 3 A perspective view of the flange is shown.

[0075] Figure 4 A cut-away perspective view of a preferred flange according to the invention is shown.

[0076] Figure 5 The connection surface of a preferred flange according to the invention is shown.

[0077] Figure 6 A cross section of another preferred flange according to the invention is shown.

[0078] Figure 7 A cross section of another preferred flange according to the invention is shown.

[0079] Figure 8 A cross section of another preferred flange according to the invention is shown.

[0080] Fig. 9 A perspective view of a portion of a flange according to the invention is shown.

[0081] Fig.10 A perspective view of a portion of a flange according to the invention is shown.

[0082] Fig.11 A tower comprising stacked tower sections connected by flanges according to the invention is shown.

[0083] Fig.12 Shown according to Fig.11 Section of the tower.

[0084] In the drawings, like reference numerals refer to like objects throughout. Objects in the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0085] Figure 1 The connection between two flanges 1 according to the prior art is shown in cross section. Each flange has a main bolt circle 1P (see for example Figure 4 ), which comprises an annular arrangement of inclined openings 10_thru, 10_part for receiving a set of fasteners 10B for connecting the flange 1 to a complementary flange 1 (see Figure 6 ). The inclined opening 10_thru, 10_part of the main bolt circle 1P is characterized by an inclination angle θ between its longitudinal axis 10A and the surface normal N of the flange connection surface 1F. Figure 1The center of the "exit" opening of the through hole 10_thru and the center of the "entry" opening of the blind hole 10_part are points along the main bolt circle 1P. Figure 4 It is more clearly seen in the perspective diagram given, Figure 4 An alternating arrangement of through hole "exit" openings 10_out and blind hole "inlet" openings 10_in forming a main bolt circle 1P is shown.

[0086] The flange 1 also includes a secondary bolt circle 1S (see Figure 4 ) of the main body section (L-shaped portion), the secondary bolt circle includes an annular arrangement of openings 11_thru for receiving a set of fasteners for connecting the flange 1 to an intermediate structure or a complementary flange 1.

[0087] Regarding the flange described above, there is a large dashed box drawn around the entire flange and a smaller dashed box within the large dashed box. The large dashed box shows the cross section of the ring that must be forged in order to machine the flange out. The smaller dashed box shows the portion that must be machined away in order to just form the L-shaped portion of the flange. The present invention can save material and machining of the smaller dashed box. Since the tower section of a wind turbine and the flange together with it can have an average diameter of about 6-8m and the cross section of the forged original part of the flange can have a size of about 30cm×30cm, the saved material and machining work is an important advantage.

[0088] Figure 2 An embodiment of two flanges 1 according to the invention is shown, which correspond to each other and form a flange connection (without bolts). Figure 1 Similarly, there are X-shaped inclined openings 10_thru, 10_part and an opening 1B_thru in the L-shaped part of the flange 1. Compared to the prior art, the flange is made of two flange segments 1A, 1B, i.e. a first flange segment 1A is arranged on a second flange segment 1B, wherein a first annular connection surface 1C of the first flange segment 1A abuts against a complementary second annular connection surface 1D of the second flange segment 1B. The flanges are in contact via their third annular connection surface 1F.

[0089] With regard to the lower flange 1, an additional intermediate layer 3 is present between the first flange section 1A and the second flange section 1B. Such an intermediate layer 3 can also be arranged between the two flanges, ie between the third connecting surfaces 1F.

[0090] Figure 3 A perspective view of a flange 1 is shown, for example, as part of a tower section 20 (see, for example, Fig.12). The figure indicates the area of ​​the annular connection surface 1F by the outer diameter D_out and the inner diameter D_in, which are also the inner diameter and the outer diameter D_out of the second flange segment 1B. The outer diameter of the first flange segment 1A corresponds to the outer diameter D_out of the second flange segment 1B, while the inner diameter D_1 of the first flange segment 1A is greater than the inner diameter D_in of the second flange segment 1B, so that the L-shaped portion is not covered by the first flange segment 1A.

[0091] Figure 4 A perspective view of a flange 1 forming a circle is shown. The flange 1 has a third connection face IF which will abut against a third connection face of a complementary flange, such as e.g. Figure 2 The main bolt circle 1P corresponds to the main hole circle 1Q, with the difference that the main bolt circle 1P relates to the first flange section 1A, while the main hole circle 1Q relates to the second flange section 1B. To the right of the second flange section 1B, the secondary bolt circle 1S is shown. The alternating holes refer to the outlet 10_out and the inlet 10_in for the bolts to enter and exit the flange.

[0092] Figure 5 FIG. 1 shows a third connection face 1F of a preferred flange 1 according to the present invention. It can be seen as viewed from the third connection face 1F. Figure 4 , except that this figure shows slotted holes 1G in the main orifice circle 1Q instead of inclined holes.

[0093] The through hole 12_thru for the bolt 1E can be seen, as Figure 7 As shown and described in.

[0094] Figure 6 A cross section of another preferred flange 1 according to the invention is shown, wherein the corresponding flanges 1 shown form a permanent flange connection. The connection is "permanent" in the sense that it can last for the life of the structure. Here, each flange 1 is formed with an alignment feature 15A in the form of a guide pin 15A, which is shaped to engage with an opposite alignment feature 15B in the form of a guide hole 15B of the complementary flange 1. The alignment features 15A, 15B are used to correct any slight ovalization that may exist in the flange when the tower sections are stacked. The figure shows a fastener 10B extending through a through hole 10_thru in the upper flange 1 and into the blind tapered opening 10_part of the lower flange 1. Here, the aperture of the main aperture circle 1Q of the second flange segment 1B is also an inclined hole that cooperates with the through hole 10_thru of the main bolt circle of the first flange segment 1A and the blind tapered opening 10_part.

[0095] The figure also indicates another relatively inclined fastener 10B, which extends through a through hole 10_thru in the lower flange 1 and into a blind tapered opening 10_part of the upper flange 1 .

[0096] Figure 7 Shows something like Figure 7 Another preferred cross-section of the flange 1 according to the present invention is Figure 7 The flange of is different in that in the second flange section 1B there is no inclined hole, but instead there is a flange such as Figure 5 Slotted hole 1G is shown. Slotted hole 1G is easier and cheaper to manufacture than inclined holes.

[0097] In addition, here, each of the two flange sections 1A, 1B of the flange 1 includes a connecting bolt 1E, which passes through the through hole 12_thru and is screwed into the thread in the blind hole 12_part, thereby connecting each second flange section 1B to the corresponding first flange section 1A. These connecting bolts 1E can also be arranged on the right (inner) side of the flange 1 alternatively or additionally.

[0098] Figure 8 A cross section of another preferred flange according to the invention is shown. Here, the slotted holes 1G are all of the same size to accommodate all bolts 10B, or the second flange section 1B comprises two rings and an intermediate space 1H between the inner ring 1Ba and the outer ring 1Bb. Both the inner ring 1Ba and the outer ring 1Bb are bolted to the first flange section 1A by connecting bolts 1E.

[0099] Fig. 9 A perspective view of a portion of a flange 1 according to the invention is shown. It can be assumed that Figure 7 The flange is shown without the upper first flange section 1A. It can be seen that the X-shaped arrangement of the fasteners 10B in the slotted holes 1G and in the outer area of ​​the second flange section 1B and (with Figure 7 Comparison) Through hole 12_thru for connecting bolt 1E also in the inner area of ​​the second flange segment 1B.

[0100] Fig.10 A perspective view of a portion of a flange according to the invention is shown. Fig. 9 There is no upper second flange section 1B, ie only a view of the lower flange 1 .

[0101] Fig.11 A tower 2, such as a wind turbine tower, is shown, comprising tower sections 20 "stacked" on each other and connected by a flange 1 according to the invention. The flange is outlined without additional details. The manner of fastening the flange is described more precisely in the previous figures.

[0102] Fig.12 Shows Fig.11 The enlarged part of the connection (see Fig.11). The tower segment 20 is welded to the flange 1. In this figure, the flange 1 according to the invention (upper flange) is connected to the flange according to the prior art (lower flange). This is possible because only the internal structure of the flange 1 is different, but the holes for connecting the flanges fit each other. The flange 1 is only indicated by symbol. The preferred flange 1 is shown in the aforementioned figures. It must be noted that due to the structure of the lower flange (prior art) is associated with significantly higher costs as explained above.

[0103] Although the present invention has been disclosed in the form of preferred embodiments and variations thereof, it will be appreciated that many additional modifications and variations may be made thereto without departing from the scope of the present invention. For the sake of clarity, it will be appreciated that "a" or "an" used throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements.

Claims

1. A flange (1) for connection to a complementary flange (1), and wherein the flange (1) comprises a first flange section (1A) and a second flange section (1B), wherein: a) The first flange section (1A) comprises: a main bolt circle (1P) comprising an annular arrangement of inclined openings (10_thru, 10_part) suitable for receiving a set of fasteners (10B) for connecting the flange (1) to the complementary flange (1); and - a first annular connection surface (1C) adapted to abut against a complementary second annular connection surface (1D) of said second flange segment (1B); and b) The second flange section (1B) comprises: - a second annular connecting surface (1D) on one side adapted to abut against a complementary first annular connecting surface (1C) of said first flange segment (1A); - a third annular connection surface (1F) on the side opposite to said one side, said third annular connection surface being adapted to abut against the complementary annular connection surface (1F) of said complementary flange (1) or against the first annular connection surface (1C) of another first flange segment (1A); - a first body section having a main orifice circle (1Q) comprising an annular arrangement of openings (10_thru) designed to allow the passage of a set of fasteners (10B) for connecting the flange (1) to the complementary flange (1), reaching the main bolt circle (1P) of the first flange section (1A) and connecting the flange (1) to the complementary flange (1) from the main bolt circle of the first flange section; and - A second body section having a secondary bolt circle (1S) comprising an annular arrangement of openings (1B_thru) for receiving a set of fasteners for connecting the flange (1) to an intermediate structure or to the complementary flange (1).

2. The flange according to claim 1 comprises an intermediate layer (3) between the first annular connecting surface (1C) of the first flange segment (1A) and the second annular connecting surface (1D) of the second flange segment (1B) and / or on the third annular connecting surface (1F).

3. A flange according to claim 1 or 2, wherein the second flange segment (1B) is an integral flange segment having a substantially rectangular or wedge-shaped cross-section with or without rounded edges, or comprises a sub-segment (1Ba, 1Bb) having a substantially rectangular or wedge-shaped cross-section with or without rounded edges.

4. The flange according to claim 1 or 2, wherein: The main bolt circle (1P) of the first flange section (1A) comprises an alternating arrangement of inclined through holes (10_thru) and inclined blind holes (10_part).

5. Flange according to claim 1 or 2, wherein the main orifice circle (1Q) comprises slotted holes (1G) arranged longitudinally parallel to the radius of the annular connecting surface (1C, 1D, 1F).

6. The flange according to claim 1 or 2, wherein the secondary bolt circle (1S) is outside the outer shape of the first flange section (1A).

7. The flange according to claim 1 or 2, wherein the second flange segment comprises two or more sub-segments.

8. The flange according to claim 4, in, The inclined through hole (10_thru) extends through the first flange section (1A) to accommodate a shank (10B_s) of a fastener (10B) extending into a complementary blind hole (10_part) of the complementary flange (1) and / or The blind hole (10_part) extends partially into the first flange section (1A) to accommodate the threaded end (10B_t) of a fastener (10B) extending into the flange (1) after passing through the inclined through hole (10_thru) of the complementary flange (1).

9. A flange according to claim 1 or 2, comprising an alignment feature (15A) shaped to engage with an opposing alignment feature (15B) of the complementary flange (1).

10. The flange according to claim 1 or 2, wherein the second flange section (1B) is mounted to the first flange section (1A) by means of a fastener, the fastener being a connecting bolt (1E) extending through an opening (12_thru, 12_part) perpendicular to the first annular connecting surface (1C) and the second annular connecting surface (1D).

11. The flange according to claim 1 or 2, wherein: The inner diameter of the first flange section (1A) exceeds the inner diameter of the second flange section (1B).

12. The flange according to claim 2, wherein: The intermediate layer (3) comprises a material selected from the group consisting of rubber, silicone, epoxy resin, slurry and adhesive.

13. The flange according to claim 12, wherein: The intermediate layer (3) comprises a material filled with metal particles.

14. The flange according to claim 5, wherein: The hole of the slotted hole (1G) is colinear with a surface normal (N) of at least one of the annular connecting surfaces (1C, 1D, 1F).

15. The flange according to claim 7, wherein: The sub-segments are arcuate segments of a ring and / or rings stacked on top of one another and / or concentric rings.

16. The flange according to claim 9, wherein: The alignment feature (15A) includes a plurality of guide pins (15A), and the counter-alignment feature (15B) includes a plurality of holes (15B) designed to mate with the guide pins.

17. The flange according to claim 10, wherein: The first flange section (1A) includes a plurality of threads (12_part), and the second flange section (1B) includes a plurality of corresponding holes (12_thru) designed to receive and retain the connecting bolts (1E).

18. The flange according to claim 11, wherein: The first flange section (1A) and the second flange section (1B) have the same outer diameter.

19. A second flange section (1B) designed for a flange (1) according to any one of claims 1 to 18, comprising: - a second annular connecting surface (1D) on one side adapted to abut against a complementary first annular connecting surface (1C) of the first flange section (1A) of said flange (1); - a third annular connection surface (1F) on the side opposite to said one side, for abutting against the complementary annular connection surface (1F) of said complementary flange (1) or against the first annular connection surface (1C) of another first flange segment (1A); - a first body section having a main orifice circle (1Q) comprising an annular arrangement of openings (10_thru) designed to allow the passage of a set of fasteners (10B) for connecting the flange (1) to the complementary flange (1), to the main bolt circle (1P) of the first flange section (1A) and to connect the flange (1) to the complementary flange (1) from the main bolt circle (1P) of the first flange section (1A); and - A second body section having a secondary bolt circle (1S) comprising an annular arrangement of openings (1B_thru) for receiving a set of fasteners for connecting the flange (1) to an intermediate structure or to the complementary flange (1).

20. A method of assembling a flange (1) according to any one of claims 1 to 18, comprising the following steps: - connecting said first flange section (1A) to a cylindrical tower section (20A) of a tower, - Connecting the second flange section (1B) to the first flange section (1A) using connecting bolts (1E).

21. The method according to claim 20, wherein an intermediate layer is arranged between the first flange section (1A) and the second flange section (1B).

22. A tower (2) suitable for a wind turbine, the tower (2) comprising a plurality of substantially cylindrical tower segments (20) provided with a flange (1) according to any one of claims 1 to 18 and permanently connected by fasteners (10B) inserted through inclined openings (10_thru, 10_part) in a main bolt circle (1P) of the flange (1).

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