WO2013097865A1

WO2013097865A1 - A ring segment for a flange of a wind turbine tower

Info

Publication number: WO2013097865A1
Application number: PCT/DK2012/050500
Authority: WO
Inventors: Michael Jensen; Jan Erik Karlskov JENSEN
Original assignee: Vestas Wind Systems A/S
Priority date: 2011-12-28
Filing date: 2012-12-21
Publication date: 2013-07-04

Abstract

Ring segment (2) for making a flange for attachment of a wind turbine tower section to another tower section. The ring segment (2) comprises a joining surface (3) which is to be joined with a corresponding joining surface of a flange of an adjacent tower section. Furthermore, the segment comprises abutting shoulders (4) at opposite ends of the segment. The abutting shoulder is adapted to adjoin an abutting shoulder of an adjacent segment for joining the segments to form a ring shaped flange. Adjacent segments are joined by use of connectors (1) and optionally by use of an assembly fixture.

Description

A RING SEGMENT FOR A FLANGE OF A WIND TURBINE TOWER

Technicai field

The present invention relates to flanges of a wind turbine tower section and to a method of making such a flange. Background

Modern wind turbines comprise a tower construction which traditionally is formed by tapered round tower sections mounted on top of each other. Each tower section may be made of a steel plate rolled into a tubular shape and assembled by welding of opposite free ends thereby constituting a closed ring. Alternatively, each section may be formed by a number of plates being assembled to form a tower section.

In order to attach one tower section to another tower section, attachment flanges are provided for each of the tower sections. Traditionally, these flanges a e likewise formed by use of a steel plate roiled into shape and assembled by welding of opposite free ends thereby constituting a closed ring. To ensure sufficient strength of the flange, the steel plate has to be very thick. Subsequently, a number of holes are drilled in the fiange in order to be able to attach a flange of one tower section to a flange of another tower section. The flanges and thus the tower sections are attached to each other by aligning the attachment holes of the first flange with attachment holes of the second flange. Attachment bolt are then inserted through the holes and tightened. The assembly of tower sections is thereby a time consuming process.

Summary

It is an object of embodiments of the present invention to provide a fiange assembly and an improved method of making a flange.

In a first aspect, the invention provides a ring segment that forms a circumferential portion of a ring shaped flange for attachment of a wind turbine tower section to another tower section. The ring segment forms a joining surface to be joined with a corresponding joining surface of a fiange of an adjacent tower section, and abutting shoulders at opposite ends of the ring segment. Each abutting shoulder is adapted to adjoin an abutting shoulder of an adjacent ring segment such that a number of ring segments together forms a ciosed ring. The abutting shoulder includes an interconnection feature for joining the ring segments either permanently or preliminarily.

Forming a ring shaped flange of multiple ring segments can facilitate improved handling of the flange and all of the components used to form the flange (i.e., the flange assembly). The flange assembly may also include connectors to secure the segments to each other. Thus, the ring segments may be made at a production facility and transported unassembled to the site of the wind turbine, and subsequently be assembled by use of the connectors at the site.

Transportation of the ring segments and the connectors may be easier and cheaper, than transportation of a finished flange of a larger size. To make a ring shaped flange for attachment to a tower section, the ring segments may be formed as circle segments, so that a ring shaped flange is made, when positioning the segment side by side.

The flange may comprise 2, 3, 4, or up to e.g. 12-16 or even more ring segments, where each segment is connected to one or more adjacent ring segments to form a ring shaped flange. The number of ring segments for the flange assembly may depend on the size of the wind turbine tower to be erected or it may depend on the length of the transportation route for the flange assembly. However, the number of segments may also be chosen as a result of other considerations.

Each ring segment comprises a joining surface which is to be joined with a corresponding joining surface of a segment of a flange of an adjacent tower section. Thus, when the tower is finished and erected, a joining surface of one segment is facing downwards whereas the corresponding joining surface of the segment of the adjacent tower section is facing upwards.

Each ring segment further comprises abutting shoulders at opposite ends of the ring segments. Each abutting shoulder is adapted to adjoin an abutting shoulder of an adjacent ring segment for joining the segments. When positioning the ring segments side by side to form a ring shaped flange, the segments are in other words adjoined shoulder by shoulder. To facilitate adjoining of two abutting shoulders, these shoulders may be formed so that at least a part of one of the abutting shoulders has a form which fits the form of at least a part of the corresponding shoulder of the adjacent segment. To reduce the workload associated with machining of the segments after preparation thereof, the segments may be moulded, such as through a casting procedure, a forging procedure, or the like. It may thereby be possible to make ring segments which are prepared for attachment with adjacent ring segments and for joining with a flange of another tower section substantially without having to machine the segments after removing them from the mould, or with at least only a small amount of machining, e.g. only planning the shoulders and/or the joining surface. As opposed hereto, it is necessary to drill holes in a traditional flange which is made from a steel plate. Consequently, it may be possible to substantially reduce the workload associated with machining of the segments, as the segments may be prepared with holes or other means, such as pockets, to receive assembly bars used to attach a ring segment attachment to another flange. To further reduce the work load, the ring segments according to aspects of the invention can be identical thereby necessitating only one mould and one type of ring segment for each type of flange being on store. In this embodiment, the abutting shoulders of one segment are identical, i.e. opposite free ends of the ring segments could be identical. In fact, the ring segment could have a symmetric shape where one half of the segment corresponds to the other half mirrored in a plane which intersects midway between the free ends, i.e. a plane which is perpendicular to the segment midways between the free ends.

Each ring segment may comprise at least one interconnection feature, such as a notch, in each abutting shoulder. This interconnection featu e or notch may be adapted to cooperate with a corresponding feature. According to one embodiment, a pair of notches in abutting shoulders of an adjacent ring segments form, in combination, a lead to receive a connector. The notches may, in a cross-section, be formed substantially as semicircles in order to form a lead with a cross-section being substantially circular when positioning two adjacent segments shoulder by shoulder. It should however be understood, that the cross-section of the lead may also be oval, e.g . elliptical, or of any other form.

The segments may comprise 1, 2, 3, or more notches in the abutting shoulders, thereby forming 1, 2, 3, or more leads for the connectors which are adapted to secure the segments by attaching a segment to an adjacent segment. The number of notches may depend on the size of the segments and/or the size of the finished flange.

Each connector may comprise a body extending upwardly in a longitudinal direction towards a head, thereby having a form which is comparable with the form of a traditional bolt. The head may form a downwards contraction surface that extends outwardly and downwardly with respect to the body. In one embodiment, the body and head may be formed one piece, whereas the body and head in an alternative embodiment may be formed in two or three pieces, e.g. by forming the body and head as separate pieces, where the head may be formed in one or two pieces, the latter resulting in a body and head being formed in three pieces. One way of forming the head in two pieces may be to form the head by one upper head piece with a pianer downward facing surface and a lower head piece, e.g. in the form of a washer, having a downwards contraction surface extending outwardly and downwardly with respect to the body. In order to fasten the connector and the segments to each other, the body may comprise a threaded part allowing for attachment of a nut. As an alternative, the connector may be formed as a rivet. It should be understood, that a nut may form an upwardly contraction surface extending outwardly and upwardly with respect to the body, i.e. a surface similar to the contraction surface of the head. This may likewise be achieved b a nut in one or two pieces, dependent on whether a washer is used or not.

To promote firm attachment of adjacent ring segments to each other, each segment may include an assembly surface extending from the abutting shoulder at an acute angle a relative to the abutting shoulder. The assembly surface may be formed around the notch as a seat that receives a portion of a connector to facilitate cooperation between the assembly surface and the connector. Thus, the assembly surface may cooperate with the contraction surface of a corresponding connector to press two adjacent segments towards each other upon application of a force in the longitudinal direction of the body, i.e. when applying a force to the body in the longitudinal direction, the contraction surface of the head is pressed towards the assembly surface. To facilitate attachment of two adjacent segments, it may be an advantage if the angle a of the assembly shoulder is identical to the angle of the contraction surface of the head, as the two surfaces can slide along each other to press the adjacent segments towards each other, when applying a force to the body in the longitudinal direction.

The flange may comprise a recess extending from an edge into the joining surface to form a cavity which is accessible from the edge when the joining surface is joined with the corresponding joining surface of a flange of an adjacent tower section, i.e. when joining two flanges of two adjacent tower sections, the two recesses may together form a cavity in the joined flanges.

The recess may extend from an edge of the flange, which edge may face towards the centre of the ring shaped flange, whereby the cavity is accessible form the inner of the flange.

The recess may comprise an insertion section with a first depth from the joining surface into the flange and a suspension section with a second depth from the joining surface into the flange, the second depth being larger than the first depth. It may thereby be achieved that an item being inserted into the recess is retained in the cavity, when inserted through the insertion section to the suspension section. To remove the item from the cavity, the item may be lifted to the level of the insertion section, i.e. to a higher level.

The segments may each comprise one or more of the above described recesses whereby it can be achieved that an item is inserted in more than one of the cavities at the same time. As an alternative, a suspension fitting may be inserted in each of the cavities end an item may be carried by the fittings in common. One example of an item carried by more suspension fittings could be a platform, e.g. for workers carrying out work inside the turbine tower. Other examples could be suspension of ladders, cables, lamps, turbine controllers, or other equipment which is used in a wind turbine.

The flange may have pockets for receiving assembly rods for fixing the flange to a flange of an adjacent tower section. The pockets may be open radially inwards, i.e. the pockets may be formed as indentation in the flange, and may be open radially towards the inner of the ring shaped flange. The ring segments may each comprise one or more pockets allowing for application of a number of assembly rods fixing the flange to a f!ange of an adjacent tower section. As noted herein, interior surfaces of such pockets may be formed entirely through a moulding process and provided for use without machining of the interior surfaces, according to some embodiments.

By forming the pockets as indentations being open towards to inner of the flange, mounting of the assembly rods may be facilitated, as the assembly rods may be inserted into the pockets from the inner of the flange instead of inserting these rods through holes in the flanges. It may further be achieved that the assembly rods are inserted with nuts attached hereto, so that only tensioning hereof remains after insertion of the assembly rods. As the assembly rods may weigh up to 10 kg each, or even more, these pockets may substantially reduce the work load associated the mounting of the assembly rods, since the assembly rods do not have to be inserted through assembly holes in the flange.

The assembly rods may be bolts adapted for tension. Thus, upper and/or lower parts of the assembly rods may be threaded allowing for attachment of a nut thereto. Before fastening a nut to the upper and/or lower part of the assembly rods, a force may be may be applied to the assembly rods in the longitudinal direction, thereby applying tension on the assembly rods.

Thus, the assembly rods may fix the flanges by a contraction force in the longitudinal direction. And each pocket may facilitate receipt of an assembly rod in a direction β transverse to the longitudinal direction. To facilitate insertion of the assembly rods, the direction β may be radial from the centre of the ring shaped flange.

A seat for an assembly rod may be formed at each pocket of a ring segment. The seat may provide an even surface for receiving a tensioned assembly rod, and may include features to prevent removal of the rod from the pocket without a preceding movement of the rod in the longitudinal direction. The seat may thus prevent the assembly rod from falling or sliding out of the pocket when the nut is not fastened to the assembly rod.

In one embodiment, the seat includes protrusions that extend from a surface against which the assembly rods operate when fixing two adjacent flanges. When inserting the assembly rod into the pocket, the nut or head of an assembly rod may be lifted over the protrusions. The protrusions thereby prevent removal of the assembly rod from the pocket without lifting the nut or head of the bolt back over the protrusions, i.e. without a preceding movement of the rod in the longitudinal direction. This feature thereby prevents the assembly rods from sliding sideways out of the pockets. The flange may further comprise grooves in projections between adjacent pockets to form an interrupted circumferential surface that extends along the ring segments, and potentially an entire flange. T e segments may each comprise one or more grooves to form the circumferential surface along the inner surface of the flange.

The grooves may form a contact surface that has a sloping angle intersecting an interface plane defined by the joining surface. In this respect, the groove may form a downwardly sloping surface relative to the joining surface of an upward facing flange and an upwardly sloping surface relative to the joining surface of a downwardly facing flange. It should be understood, that an upwardly facing flange is a flange to be joined with a downwardly facing flange, the upwardly facing flange being joined with a tower section below the flange and the downwardly facing flange being joined with a tower section above the flange.

Grooves on flanges that are mounted to one another may thus together form a contact surface having a sloping angle, where the angles of the two grooves are opposite to each other. A tool or other item may be attached to the trajectories and retention of the tool may be facilitated due to the opposite sloping angles of the contact surfaces. The flange may have an outer circumferential surface with a stepped configuration which defines a transition between two portions of the flange, herein referred to as an internal portion which is intended to extend into a tubular tower section to which the flange is attached, and an external portion which does not extend into the tubular tower section. The flange may be attached to a tubular steel section e.g. by welding the flange and the steel section at the axial transition formed by the step along the outer surface.

The step may particularly be bevelled relative to the outer surface, i.e. non-perpendicular to the outer surface. The step may e.g. form an angle in the range of 45-135 degrees to the outer surface.

In a second aspect, the invention provides a method of making a flange from an assembly according to the first aspect of the invention, the method comprising the steps of:

- providing an assembly fixture with attachment structures located to communicate with the connectors of an assembled flange, - positioning each ring segment with respect to the assembly fixture such that the connectors are able to communicate with the attachment structures, and

- securing the segments to each other and to the assembly fixture by fastening the connectors to the ring segments and to the assembly fixture.

It should be understood, that the above-mentioned features of the first aspect of the invention may also be applicable in relation to the method according to the second aspect of the invention. Thus, the second aspect may comprise any combination of features and elements of the first aspect of the invention.

To ensure fixing of the flange to the assembly fixture, the attachment structure may comprise holes. These holes may be aligned with notches in the abutting shoulders of the segments, when positioning the segments on a surface of the assembly fixture, so that a connector may extend through these holes and the leads to fix the flange to the assembly fixture.

The method may further comprise a step of aligning the flange with a tower section while it is fixed to the assembly fixture and fixing the flange to the tower section, e.g. by welding. After having fixed the segments to the assembly fixture by use of the connectors, the ring shaped flange may be aligned with a tower section while it is fixed to the assembly fixture. The assembly fixture thereby holds the segments in place relative to each other and holds the flange in place relative to the tower section. The flange may subsequently be fixed to the tower section, e.g. by spot welding. After removal of the assembly fixture, full welding of the flange to the tower section may be carried out.

Brief description of the drawings

Embodiments of the invention will now be further described with reference to the drawings, in which :

Fig. 1 shows abutting shoulders of two ring segments mated to one another, as the ring segments may be mated to one another when incorporated into flanges of mating wind turbine tower sections;

Fig. 2 and 3 illustrate parts of the ring segment embodiment of Fig. 1, Fig. 4 illustrates parts of two ring segments with abutting shoulder; and

Detailed description of the drawings

It should be understood, that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Fig. 1 illustrates ring segments of a pair of ring shaped flanges for attachment of a wind turbine tower section to another tower section. Each ring shaped flange is made of multiple ring segments 2, and potentially connectors 1 that hold the ring segments to one another.

Figs. 2, 3, and 4 illustrate different parts of the ring segments 2 of the flange assembly seen in different views.

Fig. 5 illustrates a belt that may be used to hold assembly rods together for subsequent assembly with a pair of mating flanges, according to one embodiment.

Each segment 2 comprises a welding protrusion for welding the segment to a tower wall of a corresponding tower section and a joining surface 3 (see Fig. 3) to be joined with a corresponding joining surface of a flange of an adjacent tower section. Furthermore, each segment 2 comprises abutting shoulders 4 at opposite ends 5 of the segment. Each abutting shoulder 4 is adapted to adjoin an abutting shoulder of an adjacent segment for joining the segments 2. The ring segments, as illustrated, include interconnection features 1 adapted to secure the segments to each other.

In each of the abutting shoulders 4 as illustrated in Figs. 1-4, the interconnection feature of the segment 2 comprises two notches 6 (see Fig. 2). These notches 6 are adapted to cooperate with corresponding notches in an abutting shoulder of an adjacent segment to form, in combination, a lead 7 (see Fig. 4) for a connector, such as a threaded fastener.

The lead 7 shown in Fig. 4 is configured to receive a connector, such as a threaded fastener, that has a body 8 extending upwardly in a longitudinal direction towards a head 9. The head forms a downwards contraction surface 10 that extends outwardly and downwardly with respect to the body. In the illustrated embodiment, the head is made in two pieces, so that the contraction surface extending outwardly and downwardly is formed in part by a washer 11.

To help a connector urge two adjacent segments 2 in attachment to each other, each segment comprises an assembly surface 12 (see Fig. 2) extending from the abutting shoulder 4 at a pointed angle a relative to the abutting shoulder. The assembly surface 12 is formed in the joining surface 3 around the notch 6 to facilitate cooperation between the assembly surface 12 and the connector 1. Thus, the assembly surface 12 cooperates with the contraction surface 10 of a corresponding connector 1 to press two adjacent segments 2 towards each other upon application of a force in the longitudinal direction of the body 7. I.e. when applying a force to the body 7 in the longitudinal direction, the contraction surface 10 of the head 9 is pressed towards the assembly surface 12.

The ring segment comprises a plurality of recesses 13 (see Figs. 3 and 4) extending from an edge 14 of the flange into the joining surface 3 to form a cavity 15 which is accessible from the edge 14 when the joining surface 3 is joined with the corresponding joining surface 3 of a flange of an adjacent tower section.

The recesses 13 comprise an insertion section 16 with a first depth from the joining surface 3 into the flange and a suspension section 17 with a second depth from the joining surface 3 into the flange, where the second depth is larger than the first depth. An item inserted into the recess 13 is retained in the cavity 15, when inserted through the insertion section 16 to the suspension section 17. According to some embodiments, the item may be trapped within the recess(es) when the joining surface is mated to a joining surface of an adjacent tower section, such as by having a size that will not pass through the portion of the recess having the first depth. In this respect, disassembly of the item from the flange in an assembled tower may be prevented. According to other embodiments, however, items may be sized for removal from a recess in a fully assembled tower.

Fig. 1 illustrates an example of an item 18 inserted in a cavity 15. In this embodiment, the item 18 is a suspension fitting. By inserting suspension fittings 18 in each of the cavities 15, these fittings 18 can carry a platform (not shown) for workers carrying out work inside the turbine tower, or other items that may be suspended within the interior of a wind turbine tower, such as ladders, cables, elevators, lights, and the like.

Furthermore, a plurality of pockets 19 is formed in the flange. The pockets are adapted to receive assembly rods 20 (see Fig. 1) for fixing the flange to a flange of an adjacent tower section. As illustrated in Fig. 2, 3, and 4, the pockets are open radially inwards, i.e. towards the inner of the ring shaped flange.

By forming the pockets 19 as indentations being open towards the inner of the flange, mounting of the assembly rods 19 is facilitated, as the assembly rods 19 can be inserted into the pockets 19 from the inner of the flange instead of inserting them through holes in the flanges. The assembly rods 19 are, in this embodiment, bolts adapted for tension. Thus, the assembly rods 19 fix the flanges by a contraction force in the longitudinal direction. Each pocket 19 facilitates receipt of an assembly rod 20 in a direction β (see Fig. 4) transverse to the longitudinal direction.

The inclusion of pockets 19 that open radially inward can provide for greater flexibility and/or efficiency in the process used to fasten a flange to an adjacent flange. By way of example, according to some embodiments, assembly rods 19 are held to one another by a belt for subsequent assembly to flanges, as shown in Fig, 5. The assembly rods may include threaded fasteners pre-assembled with washers and nuts. According to one approach, a single belt may include a complete set of assembly rods and corresponding hardware (washers, nuts, etc.) for joining a pair of flanges. One or more belts may be provided to assembly personnel in a tower assembly, who then position assembly rods and other hardware of the one or more belts into recesses of the flanges. In this respect, the number of components that are to be handled individually by assembly personnel may be significantly reduced.

In the embodiment of Fig. 5, a central portion of each assembly rod that is to be received within pockets of the flanges is attached to the belt. Other configurations are, however, also possible, including belts that connect to one or both ends of the assembly rods, or even to the threaded nuts that mate with assembly rods or are integral portions of the assembly rods themselves. Each pocket 19 of a flange forms a seat for the assembly rod 20 to prevent removal of the rod 20 from the pocket 19 without a preceding movement of the rod in the longitudinal direction. In the illustrated embodiment, the seat forms protrusions 21 in an upwards surface 22 against which the assembly rods 20 operate when fixing two adjacent flanges.

The flange further comprises grooves 23 in projections 24 between adjacent pockets 19 to form a trajectory which extends circumferentialiy along the flange. The grooves 23 form a contact surface 25 so that the grooves 23 form a downwardly sloping surface relative to the joining surface 3 of an upward facing flange and a upwardly sloping surface relative to the joining surface of a downwardly facing flange.

Grooves 23 formed in the flanges can be used for various purposes, including the attachment of a tool to the inner portion of the flange that may be used to install and or fasten the assembly rods. The groove may provide a surface along which the tool may move about the flange during assembly rod installation and/or fastening. The trajectories of the groove may help retain the tool in position due to the opposite sloping angles of the contact surfaces 25. The groove may, additionally or alternatively, be used for other purposes, such as receiving a portion of a belt that holds assembly rods to one another during assembly.

Fig. 1 further illustrates that the flange has an outer circumferential surface with a stepped configuration, forming an axial transition 26 between an internal portion 27 of the flange having a first radial size and an external portion 28 of the flange having a second radial size. The second radial size is larger than the first radial size. The flange is to be attached to a tubular tower section such that the internal portion is inside the tubular section and the external portion is outside the tubular section and thereby forms an outer surface of the wind turbine tower.

Claims

1. A ring segment that forms a circumferential portion of a ring shaped flange for attachment of a wind turbine tower section to another tower section, the ring segment (2) comprising a joining surface (3) to be joined with a corresponding joining surface of a flange of an adjacent tower section, and abutting shoulders (4) at opposite ends (5) of the ring segment, each abutting shoulder being adapted to adjoin an abutting shoulder of an adjacent ring segment and having an interconnection feature (1) for joining the segment to the adjacent ring segment.

2. A ring segment according to claim 1, wherein the ring segment is moulded.

3. A ring segment according to claim 1 or 2, wherein the interconnection feature (1) comprises at least one notch (6) in each abutting shoulder (4), the notch being adapted to cooperate with a corresponding notch in an abutting shoulder of an adjacent ring segment to form in combination a lead (7) for a connector.

4. A ring segment according to any of the preceding claims, wherein each connector ( 1) comprises a body (8) extending upwardly in a longitudinal direction towards a head (9), and where the head forms a downwards contraction surface (10), the contraction surface extending outwardly and downwardly with respect to the body.

5. A ring segment according to claim 4, wherein each interconnection feature (1) includes an assembly surface (12) extending from the abutting shoulder at a pointed angle a relative to the abutting shoulder, the assembly surface cooperating with the contraction surface (10) of a corresponding connector (1) to press two adjacent segments (2) towards each other upon application of a force in the longitudinal direction of the body (8).

6. A ring segment according to any of the preceding claims, including a recess (13) extending from an edge (14) into the joining surface to form a cavity (15) which is accessible from the edge when the joining surface (3) is joined with the corresponding joining surface of a flange of an adjacent tower section.

7. A ring segment according to claim 6, wherein the recess (13) comprises an insertion section (16) with a first depth from the joining surface (3) into the flange and a suspension section (17) with a second depth from the joining surface (3) into the flange, the second depth being larger than the first depth.

8. A ring segment according to any of the preceding claims, further comprising pockets (19) for receiving assembly rods (20) for fixing the flange to a flange of an adjacent tower section, the pockets (19) being open radially inwards to facilitate receipt of an assembly rod (20) in a direction β substantially parallel to the joining surface.

9. A ring segment according to claim 8, wherein each pocket (19) forms a seat for the rod (20), the seat preventing removal of the rod from the pocket without a preceding movement of the rod in the longitudinal direction.

10. A ring segment according to claim 9, wherein the seat forms protrusions (21) in an upwards surface against which the assembly rods (20) operate when fixing two adjacent flanges.

11. An ring segment according to any of claims 8-10, where the flange further comprises grooves (23) in projections (24) between adjacent pockets ( 19) to form a contact surface (25) that iies at an angle with respect to the joining surface and that extends at least intermittently along a circumferential trajectory of the ring segment between opposite ends (5).

12. A ring segment according to any of the preceding claims, connected to one or more adjacent ring segments to form the ring shaped flange.

13. A ring segment according to claim 12, wherein the ring shaped flange is welded to the wind turbine tower section.

14. A method of making a ring shaped flange from ring segments according to any of claims 1-13, the method comprising :

- providing an assembly fixture with attachment structures located to communicate with the connectors (1) of an assembled flange,

- positioning each ring segment (2) with respect to the assembly fixture such that the connectors ( 1) are able to communicate with the attachment structures, and

- securing the segments (2) to each other and to the assembly fixture by fastening the connectors ( 1) and the ring segments to the assembly fixture.

15. A method according to claim 14, further comprising the step of aligning the flange with a tower section while the flange is fixed to the assembly fixture and fixing the flange to the tower section.