Method and device for erecting a steel tower

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Office for Industrial Property The Netherlands © 1023402 © C OCTROOI²⁰ © Patent application: 1023402 φυ Int.CI.⁷

F03D11 / 04, E04H12 / 28 (22) Submitted: 13.05.2003

<td>© Registered:</td><td>© Patent holder (s):</td>

<td> 16.11.2004</td><td>Swilion BV in Vijfhuizen.</td>

<td>© Date:</td><td>© Inventor (s):</td>

<td> 16.11.2004</td><td>Pieter Adriaan Oosterling in Nieuw-Vennep</td>

<td></td><td>Fred Ernst Gardner in Zwaag</td>

<td>© Published:</td><td rowspan="2">© Authorized representative:</td>

<td>03.01.2005 IE 2005/01</td>

<td></td><td>Ir. GA Uittenbogaart in 2050 AA Overveen.</td>

© Method and device for building a steel tower and a steel tower.

The invention relates to a method and device for building a steel tower consisting of a conical steel jacket. The steel tower is intended to support the nacelle of a wind turbine. The steel tower is built by adding cladding to a vertical top section at the bottom, the top section being supported and held upright by a support and lifting device. The invention also comprises a steel tower for a wind turbine in which the diameter of the steel jacket near the foundation is greater than four meters.

NL C 1023402

The contents of this patent correspond to the original filed description with claim (s) and any drawings.

Method and device for building a steel tower and a steel tower.

The invention relates to a method according to the preamble of claim 1. Such a method is known. According to the known method, the tower is built up by placing and coupling subsequent parts of the tower. The drawback of this method is that a crane with a large capacity and hoisting height must be available for a long time and that the work takes place at an increasing height, which is a drawback.

In order to avoid this drawback, the method is carried out in accordance with the feature of claim

1. As a result, the tower can be built from below, where the work is easily accessible and the long-term availability of a large crane is not necessary during the construction of the tower.

According to an improvement, the method is carried out in accordance with claim 2. This achieves in a simple manner that the top part is kept upright during the construction of the steel tower.

According to a further improvement, the method is carried out in accordance with claim 3. As a result, the tower can be built up in layers or rings, whereby a new ring is always placed under the top part.

According to a further improvement, the method is carried out in accordance with claim 4. As a result, the tower can be assembled in a continuous process, wherein the additional parts can be supplied as a continuous belt which is placed under the top part in a pitch.

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According to a further improvement, the method is carried out in accordance with claim 5. This makes it possible to supply the sheet material on a roll with a small transport volume, so that costs can be saved on transport.

According to a further improvement, the method is carried out in accordance with claim 6. As a result, the desired spiral coupling seam can be obtained without having to tailor the sides of the sheet material.

According to a further improvement, the method is carried out according to claim 7 or 8. A rapid method of building the steel tower is hereby realized.

The invention also comprises a device according to the preamble of claim 9. Such devices are known and usually comprise hoisting means and aids that enable working at a great height. Such devices are expensive and use requires extensive safety measures, which is a drawback.

In order to avoid these drawbacks, the device is designed in accordance with the feature of claim

9. With such an arrangement it becomes possible to build the steel tower from below and to carry out the work on the ground floor.

According to an improvement, the device is designed in accordance with claim 10. With this it can be ensured that a possible misalignment of the top part is continuously corrected.

According to a further improvement, the device is designed according to claim 11. The top part can hereby be kept upright in a simple and safe manner.

According to a further improvement, the device is designed in accordance with claim 12. The direction and any tilt of the upper part can hereby be measured directly and the aiming means can make corrections immediately.

According to a further improvement, the device is designed in accordance with claim 13. With this it is possible to rotate the top part during the construction and the assembly and the supply of material of the steel jacket can take place in one rotational position.

According to a further improvement, the device is designed in accordance with claim 14. This makes it possible to increase the diameter during construction of the top part, so that conical steel towers can also be built.

According to a further improvement, the device is designed in accordance with claim 15. This makes it possible to make the plates required for the tower suitable for assembly on site.

According to a further improvement, the device is designed in accordance with claim 16. This makes it possible without waste to make the shape of the plates suitable for use in spiral-shaped plating of a conical tower.

According to a further improvement, the device is designed in accordance with claim 17. The steel wall of the tower can hereby be reinforced, whereby the sheet material of the metal wall can be thinner.

The invention also comprises a steel tower in accordance with the preamble of claim 18. Such steel towers are known and have a limited diameter due to the need to supply the parts of the tower partly by road. Because of the necessary

It is then necessary to thicken the wall thickness of the tower, but the stiffness increases only to a limited extent and the tower remains limp and undesired vibrations can occur due to the low natural frequency of the steel tower.

In order to avoid this drawback, the steel tower is designed in accordance with the feature of claim

18. As a result, a steel tower with a high natural frequency can be built and less vibration will occur, while the possible thinner plating can keep costs down. The foundation can also be made lighter.

According to an improvement, the steel tower is designed in accordance with claim 19. As a result, the sheet material suitable for use in the entire tower can be supplied on one or more rollers, thereby saving transport costs.

According to a further improvement, the steel tower is designed in accordance with claim 20. As a result, the steel tower can be built up in a continuous process, which leads to savings.

According to a further improvement, the steel tower is designed in accordance with claim 21. As a result, the number of different types of plate is limited, so that the assembly equipment can be simplified and the logistics simplified.

According to a further improvement, the steel tower is designed in accordance with claim 22. As a result, a stable steel tower is obtained in a simple manner.

According to a further improvement, the steel tower is designed in accordance with claim 23. As a result, the cross-section of the steel tower retains its circular cross-section even with thin sheet material and thus the steel tower retains its stability even when thin sheet material is used.

The invention is explained below with reference to a few exemplary embodiments with the aid of a drawing.

In the drawing shows

Figure 1 shows a side view of a wind turbine with a conical steel tower,

Figure 2 shows a side view of the construction of the steel tower of figure 1,

Figure 3 shows a schematic top view of the underside of the steel tower during the construction according to a first embodiment,

Figure 4 shows a schematic side view of the underside according to Figure 3,

Figure 5 shows a schematic cross-section and side view of a rolling mill used in the construction according to figure 3, Figure 6 a schematic cross-section of the underside of the steel tower during the construction according to a second embodiment, and

Figure 7 shows a schematic section VII-VII of figure 6.

In figure 1 a wind turbine 3 is shown with a steel tower 2 placed on a foundation 1. At the top of the steel tower 2, a bearing 4 is mounted on which a gondola

5 can rotate about the vertical axis 8 of the steel tower 2. The nacelle 5 is provided with blades 6 which can rotate about an approximately horizontal axis of rotation 7 and thereby drive an axis in a known manner. The steel tower 2 has a height such that the horizontal axis of rotation 7 is at least forty to fifty meters above the ground and an average diameter d, the height of the horizontal axis of rotation above the ground being more than ten times the average diameter d. Due to the stiffness of the samples

W023402 · Tower 2, this is conical in which the wall makes an angle α with the vertical and where α is greater than 2 degrees. The diameter of the steel tower 2 near the foundation 1 is at least four meters. As a result, vibrations in the steel tower 2 are avoided and the steel tower 2 can be designed with a thin wall, with a wall thickness of 6-10 mm being considered for a tower 50 to 100 meters high.

Figure 2 shows how the steel tower 2 can be built. A support and lifting device 12 is placed on the foundation 1. The support and lifting device 12 is used to hold and lift an upper part 11 of the steel tower 2, there being controls (not shown) controlling the support and lifting device 12. Among other things, there is a sensor that can determine whether the center line 8 is sufficiently vertical, the sensor making use of a beam of laser light. A new part of the steel wall is always added to the underside of the upper part 11 by means of welding, while the upper part 11 is lifted continuously or intermittently. The supply of new material for the steel wall, such as steel plate material, is explained below. It will be clear to the person skilled in the art that after the parts have been applied to the steel wall, a preservation must be applied to prevent corrosion.

In the exemplary embodiments discussed here it has always been assumed that the steel tower 2 is assembled by welding sheet material together. In addition to fixing sheet material together by welding, many other fixing methods are known, such as riveting, gluing, seaming and other chipless deformation methods of the sheet material. These methods can be similar

1023409 · used in the construction of the steel tower 2 and will no longer be mentioned separately hereinafter.

Optionally, cables 10 are attached to the top of the upper part 11 and are held under tension by winches 9. By celebrating or tensioning the cables 10, the position of the top of the upper part 11 can be fixed, thereby ensuring that the upper part 11 remains upright. At the top of the upper part 11, the cables can be attached to the wall, for example with lifting eyes 10 or to the mounting flange of bearing 4. If the bearing 4 is mounted, the cables 10 can also be attached to the rotatable part of bearing 4, making it possible to rotate the upper part 11 with tensioned cables 10. When lifting the upper part 11 by the support and lifting device 12 the winches 9 are controlled in such a way that the cables 10 are evenly celebrated and the top of the upper part 11 remains sufficiently fixed.

Figures 3, 4 and 5 schematically show the underside of the upper part 11 of the steel tower 2 during the construction according to a first embodiment. During construction, removable auxiliary equipment is placed on a center support 27 and a rail foundation 18. Rail 17 is arranged and supported on the rail foundation 18 in a circle. A turntable 29 is placed on the center support 27. The axis of rotation of the turntable 29 corresponds to the axis 8 of the steel tower 2 (see figure 1,2). Twelve cylinder supports 26 are mounted on the turntable 29, inter alia with a bolt 28. The cylinder supports 26 are fastened together by means of coupling plates 30 and coupling bolts 25. The end of each cylinder support 26, which is not mounted on the turntable 29, is provided with a wheel 19 which can rotate about a horizontal axis and which can move in a circular path over the rails 17. When the turntable 29 rotates about its vertical axis of rotation by means of a drive (not shown), the twelve cylinder supports 26 rotate synchronously with it. The cylinder supports 26 and the turntable 29 are designed in such a way that they can be easily assembled and disassembled so that they can be easily disassembled after construction of the steel tower 2 and removed from under the steel tower 2 and with a subsequent steel to be assembled tower 2 can be reassembled and used.

The cylinder supports 26 each have an opening in which a hydraulic cylinder 22 is movable in a radial direction and rests with supporting pins 23 on the cylinder support 26. The radial movement of the hydraulic cylinder 22 can take place automatically under the influence of a drive (not shown) if none load on the hydraulic cylinder 22. The hydraulic cylinder 22 is provided with a piston rod 21 with a clamp 35 at the end for clamping sheet material.

The conical wall of the steel tower 2 is formed from a strip of sheet material 20 with a width b. The material is supplied on a stock roll 13 which is placed on a turntable 14. The strip of sheet material 20 is stretched and rolled in a radius Ri in a rolling device 30 provided with four bending rollers 15 which alternate on both sides of the sheet material 20. stand side by side for some distance. The radius Ri in which the sheet material 20 is rolled corresponds to the radius Ri of the underside of the top 11 of the steel tower

2. The sheet material 20 enters into adjacent walls in the outer wall of the steel tower 20, because the steel tower 2 is conical, the edges of the sheet material 20 in the plane of the sheet material 20 must have a radius R2, as shown in figure 5. By correctly dimensioning R2 depending on the radius Ri of the underside of the upper part 11 of the steel tower 2 and the plate width b, it is achieved that the gap between adjacent edges of the plate material 20 is minimal. In order to realize this radius R2, the sheet material 20 is passed through a rolling device 31. In the rolling device 31, the sheet material 20 is guided between two rolling rollers 16, which are placed on either side of the material 20. The distance between the rollers 16 is on the top side ti and on the bottom side ti₂ where t2 is less than ti and where ti is equal to or less than the original thickness of the sheet material 20. As a result, the sheet material 20 is rolled out more at the bottom than at the top and the sides of the sheet material 20 have a radius with the radii R₂ and (R2 + b). In the shown embodiment, single roller rolls 16 are used. This is possible because the width b is limited to about 1.0 meter. With a larger width b of the sheet material 20, the rollers 16 may have to be provided with support rollers.

The turntable 14, the rolling device 30 and the rolling device 31 are mounted on a supporting floor 32 which can be adjusted with an adjustable support 34 at a pitch angle φ with the horizontal top surface of a foundation 33.

The pitch angle φ is approximately the same size as the pitch angle φ of the sheet metal strips 20 in the steel jacket 2 and has approximately the value φ = arc tangent (b / (2.n.Ri)). Because the pitch angle φ is dependent on the radius Ri and this radius Ri increases as the steel tower 2 becomes ho30, the pitch angle φ will decrease with increasing height of the steel tower 2.

The construction of the steel tower 2 with the device shown in Figures 3, 4 and 5 is as follows. A prefabricated upper part 11 is placed on the clamps 35. The underside of this upper part 11 can have the pitch angle φ where the sheet material 20 connects to the top part 11 with a butt joint 36 and the side of the sheet material

20 is attached to the existing material. If the underside of the top part 11 is flat, the plate material on the side is fitted so that it connects to this flat bottom side of the top part 11. Now the turntable 29 is rotated and the plate material 20 is fed through the rolling devices 30 and 31 so that it right radii is rolled. In a coupling area C, the top of the supplied sheet material 20 is attached to the bottom of the top part 11, for example, by welding or by another fixing method. As soon as the plate material 15 is attached to the upper part 11 and leaves the coupling area C, the clamp 35 coupled at the bottom starts to tension the upper part 11 by tensioning the hydraulic cylinder 22 and will continue to do so until the relevant hydraulic cylinder 22 has a has made almost complete revolution and is approaching the coupling area C again. In synchronism with the rotation of the turntable 29, the clamps 35 are raised by the hydraulic cylinders 22, so that the centerline 8 remains vertical and the coupling area C maintains a more or less constant height. When a clamp 35 approaches and enters the coupling area again after an almost complete rotation, the clamp 35 is detached from the bottom of the upper part 11 and lowered. The hydraulic cylinder 22 is then moved outwardly on the cylinder support 26 in accordance with the angle of inclination α with the vertical. Then, the clamp 35 is raised and attached to the bottom of the sheet material 20, and the operations repeat until supply roll 13 is empty. Then one becomes

1023402 · next stock roll 13 is placed on the turntable 14 and the strip of sheet material 20 is coupled to the top 11 with a butt joint 36 and the cycle is continued.

Stiffening rings 37 are attached to the inside of the wall, preferably at the same time as the covering of the wall of the top part 11 is applied. These stiffening rings 37 ensure that the cross-section of the steel tower always remains circular and that local buckling of the thin sheet material is prevented.

The spacing of these stiffening rings is preferably no more than 1.0 meter and is limited, for example, to 0.5 meter.

A simple way of attaching the sheet material 20 to the top part 11 is welding, wherein the more or less circumferential seam is welded in one position, the coupling area C, whereby the welding can be automated in an easy manner, and for example from the outside welded and where on the inside in the coupling area C backing strips, support rollers or the like can be provided to allow efficient automatic side welding. It is also possible to weld by hand because in the coupling area C the welding seam is easily accessible for several people. Optionally, the top part 11 and the plate material are first coupled in a known manner with coupling plates, whereby welding can take place over a large part of the circumference. Wrinkle shrinkage between the clamps 35 and the top part is detected by the direction of the center axis 8 of the tower changing and this is automatically compensated by length adjustment in the hydraulic cylinders 22.

It will be clear to the skilled person that the top part 11 of the steel tower 2 must be preserved,

1023402 · to minimize corrosion. Preferably, the preservation of the steel tower 2 during construction is also done near the underside of the upper part 11 because the material to be protected is most easily accessible there. The equipment required for this can easily be placed on the outside next to the underside of the top part 11. Equipment required for preserving the inside of the steel tower 2 may optionally be mounted on the turntable 29 in a manner not shown.

An electronic control system is used to keep the center line 8 of the steel tower 2 or the top part 11 vertical with the aid of sensors and to coordinate the movements of the various parts of the installation. Keeping the center line 8 upright with the aid of the hydraulic cylinders 22 and possibly the winches 9 will be fully automated and the various processes can proceed wholly or partly automatically. Preferably there is a direct coupling between the rotation of the turntable

29 and the driving of the sheet material by the rolling device 30 and the rolling device 31, optionally this is combined with the driving of the turntable 14. Also, the adjustment and control of the rolling device 30 can be automated, wherein there are sensors which measure the radius Ri of the plate material 20 can be set and measured. Also, the adjustment and control of the rolling device 31 can be automated, also with sensors having plate thickness t1, t₂ or radius R.₂ measure.

To attach the sheet material 20 to the top part 1, an automated process can be selected or manual control is used. Preferably, the clamp 35 is manually placed around the underside of the sheet material, while repositioning the hydraulic cylinder 22 on the cylinder support 26 can be done manually or automatically.

After the steel tower 2 has reached the required height, the outer wall of the steel tower 2 is attached all around on the outside to the permanent foundation, which is, for example, attached to the rail foundation 18. After the steel tower 2 is attached to the foundation, the clamps can 35 can be released and the hydraulic cylinders 22 can be lowered. The turntable 29, the cylinder supports 26 and the cylinders 22 can then be disassembled and taken out from under the steel tower 2. If necessary, excess sheet material is removed and a door is optionally made in the steel wall. The winches 9 can also be disassembled and the gondola 5 can be placed on the steel tower 2.

Figures 6 and 7 schematically show the underside of the upper part 11 of the steel tower 2 during the construction according to a second embodiment. Below the axis 8 of the steel tower 2 is a foundation 51 on which a central support 50 is placed. A foundation ring 49 is arranged around the foundation 51 on which a support 48 of a horizontal beam 38 can rest. The other end of the horizontal bar 38 rests on the center support 50. A foot 39 can move horizontally over the horizontal beam 38, possibly under the influence of a drive system. An adjustable support 45 is mounted on the foot 39, along which a slide 44 can be moved in vertical direction by a drive (not shown), this drive can be hydraulic or mechanical. Each slide 44 is provided with a coupling piece 43 which can be coupled to a mounting plate 42 which is attached to the inside of the wall of the steel tower 2.

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The steel tower 2 is built from conical steel rings. In figure 6 the top part 11 is shown with a bottom ring 47 which is attached to the top part 11 with a welded coupling seam 52. Each conical steel ring is made of sheet material which, for example, is made suitable for assembly by rolling as described above. Each conical ring has at least one butt joint 40 and is provided with stiffening rings 37 for keeping the ring circular and / or preventing local kinking of the slightly curved plate. On the inside, six mounting plates 42 are arranged all around, the mounting plates 42 may optionally form part of a stiffening ring 37.

There are two groups of vertical supports 45. The first group of vertical supports 45 is coupled to the mounting plates of the lower ring 47 with the coupling pieces 43 and supports the upper part 11. To keep the center line 8 of the upper part 11 vertical, the slides 44 controlled by a control not shown. In connection with the stability of the support of the upper part 11, there are preferably twelve or more vertical supports 45, so that each group comprises at least six vertical supports 45. The bottom ring 47 has been moved upwardly by the vertical supports 45 with the top 11 while the cables

10 were celebrated by the winches 9. The bottom ring 47 is raised so that there is room underneath to assemble another ring 41 to be coupled.

After the next ring 41 to be coupled has been assembled, it is coupled to the second group of vertical supports

45 after they have been moved to a larger diameter by the feet 39. Subsequently, the next ring 41 to be coupled is lifted by the vertical supports 45 until the coupling seam 46 to be welded is narrow enough to weld, and subsequently this coupling seam 46 is welded mechanically or by hand. After this coupling seam 46 is ready, the coupling pieces 43 can be detached from the lower ring 47 and the respective uncoupled slides 44 can be lowered and the slides coupled to the ring 41 can be raised, with the entire upper part 11 moving upwards. .

The steel tower 2 is built up in this way from conical steel rings until the tower 2 has reached the required height. Then the bottom ring is attached to a foundation and the vertical supports 45, the horizontal bars 38 and the other mounting means are removed.

The sheet material 20 used in this construction method can be the same as in the construction method described first.

Here, too, the sheet material 20 will have to be stretched and rolled in a radius Ri, the edges of the sheet material will also have a comparable radius R₂ should get. Optionally, the edges can also be made to fit by removing material.

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