DE102017200123B4 - Mounting arrangement - Google Patents

Abstract

Fastening arrangement (5) for fastening components to a wall (1) of a tower of a wind power plant, the fastening arrangement (5) having a fastening element (2) and a solder body (4), the fastening element fixed to the by means of the solder body (4) Wall (1) is connected, characterized in that the solder body (4) is designed as a fillet weld, the fastening element (2) and the wall (1) resting against one another at least in some areas.

Description

The invention relates to a fastening arrangement for fastening components to a wall of a tower of a wind power plant and a method for producing a fastening arrangement.

Welded steel structures subject to vibrations are particularly prone to fatigue due to the notch effect of weld seams and welded attachments as well as the process-related residual welding stresses.

Wind turbines provide in reference to a cyclic stress particularly highly loaded constructions. This is mainly due to natural frequencies of the rotor blades and the tower, a wind load as well as the rotor blade passage on the tower itself. This means that such structures up to 10 ⁹ load changes during the entire Should endure service life and must be designed for such a load.

In addition to the gondola including rotor blades and tower foundation, the tower, which is often built as a tubular steel tower, is a regulating factor in the design of the overall wind turbine.

In order to construct stable towers, the operational strength loads and extreme loads are first determined in load simulations, on the basis of which the tower is designed. The concept of the notch effect plays a central role in verifying the fatigue strength. All cross-sectional transitions and shape defects in the tower wall are called notches. In the vicinity of notches, a stress distribution deviates from that of the undisturbed component. This phenomenon is known as the notch effect.

In a notch case class, notches with the same or a similar notch effect are combined to simplify the calculation. According to the European norms (EN 1993; EN 1090), the welding sockets have a notch case of 80. This means that the component designed according to this is operationally stable for a maximum oscillation stress width of 80 N / mm ² . That is, normal stresses in the tower wall can fluctuate for two million cycles with an amplitude of 40 N / mm ² without failure. For a completely notch-free tower wall, e.g. made of steel, a maximum notch class of 160 can usually be assumed.

Wind turbines in steel segment construction usually have three welding details: on the one hand the longitudinal seams with notch class 125, the round seams (transverse seams as butt seams to connect the pipe segments) with notch class 90 and so-called weld bushes with notch class 80. The weld bushes are thus compared to the other weld details a weak point.

The welding sockets allow the installation of tower fittings such as crampons, ladders and cable routing, and the attachment of the tower fittings to the inner wall of the gym. Well over a hundred welding sockets can be used in current wind turbines.

The joining process used by the overwhelming majority to assemble the welding sockets on the inner wall of the tower is gas-shielded metal arc welding (MSG welding). The socket is welded to the inner wall of the tower by means of a fillet weld.

So is from the publication WO 2010/058037 A2 an add-on element for fixing add-on parts to a metallic tower inner wall known, which is provided for welding to the door inner wall.

Advantageous are the inexpensive, quick and simple assembly through the process as well as the versatile consideration of the application in the rules for design. Due to the melting of the base material of the tower inner wall, however, only a comparatively low notch class can be achieved, and correspondingly large material thicknesses must be used to compensate.

The cause of the negative effect of the welding sockets is, on the one hand, an unfavorable influence on the tower wall due to the thermal effects of the welding process. This can lead to hardening, softening, internal irregularities and unfavorable welding residual stresses, all of which lead to reduced fatigue strength. On the other hand, geometric notch effects result from force deflections and deformation hindrances due to such welded-on attachments.

Due to the relatively low notch fall class 80 of the welding bushes, the tower wall has to be made thicker, which on the one hand leads to a higher use of material and on the other hand prevents a higher construction method in terms of utilizing safe wind areas. Last but not least, due to the high notch sharpness and the associated significant reduction of tolerable vibrations, such weld bushings lead to a overall shorter service life of wind turbines.

With a generic wind turbine (120 m hub height, 3 MW output), around 5 to 7 tons of steel mass per tower can be saved for tower installations with notch class 90 or between 15 to 23 tons of steel mass for notch class 112 compared to notch class 80.

It would therefore be desirable to reduce the notch effect of the welding sockets or to increase the notch class.

In the publications DE 20 2012 009 889 U1 and EP 2 078 850 A2 it is proposed to attach components to the tower wall by gluing. The flammability and often inadequate aging resistance of the adhesives to be used are considered disadvantageous.

In the publications DE 20 2014 104 673 U1 , EP 2 574 779 A1 and EP 2 574 780 A1 it is proposed to fasten retaining elements in bores in the tower wall.

In the publication EP 2 187 049 A2 it is suggested to shoot a bolt into the tower wall.

The attachment of add-on elements and sockets by means of magnetic holding force is described in the publication WO 03/067038 A1 described.

The publication DE 20 2016 101 425 U1 describes the joining of add-on elements within a tower by means of a brazing process. With the aid of a flux, a solder is supposed to flow into a defined gap between the socket and the tower wall through capillary action.

The invention is based on the object of providing an arrangement for fastening components to a wall of a tower of a wind power plant, which arrangement avoids the aforementioned disadvantages of the prior art. It is also an object of the invention to provide a method for producing such a fastening arrangement.

The object is achieved by a fastening arrangement according to the main claim and a method according to the secondary claim. Further developments are defined in the dependent claims and the exemplary embodiments and are explained in more detail in the following description.

The fastening arrangement for fastening components to a wall of a tower of a wind turbine has a fastening element and a solder body, the fastening element being firmly connected to the wall by means of the solder body or a soldered seam. The solder body is also designed as a fillet weld.

A fillet weld can be used to create a reliable connection between the fastening element and the wall. The wall of the tower is thermally stressed to a much lesser extent by the solder body during the production of the fastening arrangement than in the case of a welded connection. The solder body forms a material connection between the fastening element and the wall, the material connection guaranteeing that the component can withstand sufficient stress without producing the negative effects of notches in a weld seam.

The fillet weld can be a convex weld, a flat weld or a hollow weld.

It is also provided that the fastening element and the wall are at least partially in contact with one another. The fastening element thus at least partially touches the wall. A defined gap between the fastening element and the wall, as is required in the brazing process, is therefore not necessary. In particular in the case of a cylindrical tower wall of a wind power plant, this can simplify the fastening of the fastening element to the wall.

The solder body can extend at least partially on the outside around an outer wall of the fastening element. The solder body can e.g. be ring-shaped or U-shaped.

It can be provided that the wall has a first surface and the fastening element has a second surface, the said surfaces being essentially perpendicular to one another. The solder body can form a solder bridge between the first surface and the second surface.

In a further development, the solder body is produced by arc joining, in particular arc soldering. In one embodiment, the solder body is flux-free. Fluxes are often used in soft soldering or hard soldering and represent a health hazard. On the other hand, when soldering under a protective gas atmosphere, e.g. Arc brazing, usually no flux required.

In one embodiment, the fastening element is cylindrical or cuboid. The fastening element is designed, for example, as a socket, flag plate or bolt. The fastening element can be fastened to the wall with one end face. In addition, the fastening element can have a through hole that extends from said Front side extends up to a front side opposite said front side. Furthermore, the fastening element can have an internal thread and / or an external thread. The through hole can in particular be designed as a continuous bore with an internal thread. In this way, components can be connected to the fastening element or fastened to the fastening element in a simple manner.

In one embodiment, the solder body is formed by a copper-based solder, a nickel-based solder, a cobalt-based solder or an iron-based solder. The solder and / or the solder body can have a melting temperature of at least 900 ° C and / or at most 1200 ° C. For example, CuSi3 has a melting range of 910 - 1025 ° C, while CuAl8 has a melting range of 1030 - 1040 ° C. Typically the steel used for the inner wall of the wind turbine has a melting temperature of about 1400 ° C or even more. Due to the intended melting temperature of the solder, the solder can be melted without damaging the wall. The solder body and the wall are thus typically made of different materials.

It can be provided that the solder body has a lower modulus of elasticity (E modulus) than the wall and / or the fastening element. This results in reduced deformation restraint, and thus stress peaks can be reduced. The modulus of elasticity of steel, which is typically used for the construction of the wall and / or the fastening element, is typically more than 2 × 10 ⁵ N / mm ² , for example 2.1 × 10 ⁵ N / mm ² . On the other hand, the modulus of elasticity of the solder body can be up to 1.4 × 10 ⁵ N / mm ² , in particular the modulus of elasticity of the solder body can be less than 1.3 × 10 ⁵ N / mm ² . For example, the modulus of elasticity of the solder body is 1.2 × 10 ⁵ N / mm ² .

In one embodiment, the solder body comprises a single layer or multiple layers of a solder or different solders. For the connection of the fastener to the wall, the fastener arrangement can also use a variety of solder bodies, e.g. 2, 3 or even more.

The fastening arrangement can be assigned to a notch class (see definition above) of at least 90, in particular at least 100 and / or at most 130 or 120.

The fastening element can e.g. be connected to an inner tower wall or an outer tower wall. The components that are attached to the wall of the tower of the wind turbine can in particular be crampons, ladders and cable guides. Other components are also conceivable. Typically, a wind turbine comprises a tower with a tower wall. The wind turbine can have the above-mentioned fastening arrangement or a multiplicity of such fastening arrangements.

• - Anordnen eines Befestigungselements an einer Wand eines Turms einer Windkraftanlage;
• - Schmelzen des Lots, wobei zumindest die Wand (1) in einem festen Aggregatszustand bleibt;
• - Bilden eines Lotkörpers mit einer Kehlnaht; und
• - Verbinden des Befestigungselements mit der Wand mittels mit der Kehlnaht des Lotkörpers, wobei das Befestigungselement und die Wand zumindest teilweise aneinander anliegen.

The invention also provides a method of manufacturing a fastening arrangement. The procedure consists of the following steps:

• - arranging a fastening element on a wall of a tower of a wind turbine;
• - melting the solder, whereby at least the wall ( 1 ) remains in a solid state of aggregation;
• - Forming a solder body with a fillet weld; and
• - Connecting the fastening element to the wall by means of the fillet weld of the solder body, the fastening element and the wall at least partially in contact with one another.

When melting the solder, it should therefore be ensured that only the solder melts; the wall and preferably also the fastening element should remain in a solid state of aggregation.

The solder is preferably applied to the fastening element and / or to the wall of the tower during the melting process. Alternatively, the solder can also be arranged on the fastening element and / or on the wall before melting. In a development, the steps of melting the solder and / or producing the soldered connection take place with the supply of a protective gas or in an at least partial vacuum.

Suitable shielding gases depend on the process parameters. For example, pure argon or pure helium or mixed gases rich in argon or helium can be used as protective gases. The partial vacuum can be, for example, a rough vacuum with a pressure of 1 mbar to 300 mbar or a fine vacuum with a pressure of 10 ^-3 mbar to 1 mbar.

Oxidation of the connection partners can be prevented by the vacuum or the protective gas, whereby a stronger soldered connection can be established. At the same time, the material surface can be sufficiently activated by the arc effect. This means that any flux can be dispensed with.

In one embodiment, the solder is melted by means of an electric arc.

For example, the fastening element can be connected to the wall by means of arc soldering. For the purposes of the present invention, arc soldering is a fusion joining process in which the connection between materials is established using an alien filler material. Arc soldering is defined in the DVS bulletin (German Association for Welding Technology eV) 0938, for example. The connection typically comes about through interfacial reactions, including wetting, spreading, capillary behavior and diffusion processes. Arc soldering is usually a joint soldering process, in contrast to the otherwise common gap soldering processes. While with gap soldering a defined gap is mainly filled with solder by means of a capillary filling pressure, with joint soldering a joint can be filled with solder mainly by gravity. The energy transfer for melting the solder takes place by means of an electrical gas discharge (arc) with a protective gas supply. Due to the relatively low melting temperatures of the brazing materials, connections with little damage and low thermal stress on the base materials can be achieved.

For example, the following arc soldering processes can be used for the present invention: metal shielding gas (MSG), tungsten shielding gas (WSG) and plasma soldering. The person skilled in the art can find further details on arc welding and arc soldering from the prior art.

Alternatively, for the step of melting the solder, a welding device, e.g. a metal shielding gas welding machine (MSG welding machine) can be used.

The mentioned method for producing a fastening arrangement is particularly suitable for producing a fastening arrangement described above.

It should be emphasized at this point that features which were only mentioned in relation to the fastening arrangement can also be claimed for the method mentioned and vice versa.

The fastening arrangement and the method for producing the fastening arrangement enable a significant reduction in the notch sharpness of the fastening elements in wind turbines while being simple to implement. As a result, on the one hand, the service life can be increased, but also large masses of tower material can be saved. Furthermore, there are completely new possibilities in terms of design and dimensioning for designing the entire wind turbine. With an increased notch case class, significantly larger hub heights can be generated and towers with reduced wall thicknesses can be realized. In addition, in the context of tower production, there can also be cost advantages through reduced lead times and test times. Maintenance, repair and / or service can also be simplified by the fastening arrangement or the method for producing the same, and / or costs can be saved.

It should also be noted that the reduced energy input during soldering in comparison to welding prevents the burn-off of coatings around the joint. This is especially important with smaller wall thicknesses, when the opposite side of the sheet is already coated. In addition, the smoke exposure from soldering is possibly lower than with a welding process and overall less harmful to health due to the low toxic effect of copper in the human body and the large absorption tolerance.

• 1 einen Teil eines Querschnitts einer Turmwand einer Windkraftanlage,
• 2 eine Wöhler-Kurve aufgeschweißter Buchsen sowie aufgelöteter Buchsen,
• 3 Kehlnähte im Querschliff einer Schweißung (links) und einer Lötung (rechts) einer Befestigungsanordnung und
• 4 eine Aufsicht und einen Querschnitt eines für die Aufnahme der Wöhler-Kurve der 2 untersuchten Probenkörpers .

Further advantages and features of the invention emerge from the following description, in which the invention is explained in more detail with reference to the accompanying figures. In the figures shows

• 1 part of a cross section of a tower wall of a wind turbine,
• 2 a Wöhler curve of welded sockets and soldered sockets,
• 3 Fillet welds in the cross-section of a weld (left) and a soldering (right) of a fastening arrangement and
• 4th a plan view and a cross section of a for recording the Wöhler curve of 2 examined specimen.

In the figures, recurring features are provided with the same reference symbols.

1 Figure 10 shows part of a cross section of a tower wall 1 . The tower wall 1 is part of a wind turbine, not shown, and is built in steel segment construction. For the implementation of the invention, it does not matter how the wind turbine or the tower of the wind turbine are designed in detail. For example, the wind turbine can be a vertical rotor or a horizontal rotor, and a hub height can be between 20 and 200 m, for example. The tower wall 1 is made in particular from a metal, usually steel for the construction of the tower wall 1 is chosen.

In the figure is a mounting arrangement 5 for attaching components to the tower wall 1 shown. The fastening arrangement 5 instructs Fastener 2 on, the one with the tower wall 1 by means of a solder body 4th is firmly connected. Here, the fastening element 2 be attached to an outside or to an inside of the tower wall; in the embodiment shown is the fastening element 2 on the inside of the tower wall 1 (Tower inner wall) attached. The fastener 2 touches the tower wall 1 partially so that the tower wall 1 and the fastener 2 touch each other in areas.

The fastener 2 is designed as a cylindrical socket in the embodiment shown. The socket 2 is with an end face 8th on the wall 1 attached and includes a through hole 3 that extends from said face 8th up to one of the named end faces 8th opposite end face 7th extends. The hole 3 has an internal thread 6th on. Alternatively or additionally, an external thread can also be provided on an outside of the socket 2 be provided. With the help of the internal thread 6th and / or the external thread, components can be attached to the fastening element. These components can be designed differently; For example, ladders, platforms and cable guides are conceivable. Typically, a wind turbine has well over a hundred such mounting arrangements 5 to the components mentioned on the gymnastics wall 1 to fix.

The solder body 4th also has a fillet weld and forms a solder bridge between a surface of the fastening element 2 and a face of the wall 1 with the surfaces oriented perpendicular to each other. The solder body 4th thus forms a material connection between the socket 2 and the tower wall 1 . In the exemplary embodiment shown, the solder body is 4th ring-shaped and circumferential around the cylindrical socket 2 trained around.

The solder body 4th is made in an arc soldering process. By having the solder body 4th is made by arc soldering, a flux can usually be dispensed with. This is the solder body 4th flux free. For a definition of arc soldering, reference is made to the description above.

The solder body 4th can be formed for example by a copper-based solder, a nickel-based solder, a cobalt-based solder or an iron-based solder. The socket 2 and the wall 1 are made of a metal, with steel being selected in the exemplary embodiment shown.

Typically, the solder body comprises 4th a modulus of elasticity that is smaller than a modulus of elasticity of the tower wall 1 and / or a modulus of elasticity of the socket 2 . The lower modulus of elasticity of the solder body 4th allows a certain degree of deformation, for example with temperature fluctuations or with vibrations of the tower wall 1 . In the exemplary embodiment shown, the modulus of elasticity of the solder body is 4th 1.2 × 10 ⁵ N / mm ² . The steel used here is approximately 2.1 × 10 ⁵ N / mm ² .

The melting temperature of steel varies depending on the type of steel, but in most cases it is at least 1400 ° C. As a solder of the solder body 4th has a melting temperature of at least 900 ° C and at most 1200 ° C, the solder can be melted without melting the steel of the tower wall 1 or the socket 2 comes. This allows the fastening arrangement 5 be assigned to a higher notch class than fastening arrangements that create a welded connection between the wall 1 and the fastener 2 exhibit.

In 2 a Wöhler curve is shown. With a Wöhler test, a fatigue strength, more precisely the fatigue strength and fatigue strength of materials or components (component Wöhler test) is determined. For this purpose, the test bodies are loaded cyclically, mostly with a sinusoidal load-time function.

In the 2 the vertical axis shows a longitudinal stress range Δσ in N / mm ² , and the horizontal axis shows the number of load changes N.

The 4th shows a plan view or a cross section of a typical specimen 9 who is responsible for the Wöhler tests of the 2 was used.

Various sockets were used for the Wöhler tests 2 each centered on a metal strip 10 welded or soldered on. The sheet metal strip 10 of the specimen 9 should be the tower wall 1 simulate and has the following dimensions: 500 × 80 × 20 mm. The socket 2 is cylindrical and has a diameter of 30 mm. The socket 2 is by means of a fillet weld 4 ' connected to the sheet metal strip. The fillet weld 4 ' can be designed as a weld seam or solder seam, depending on the experiment. The fillet weld 4 ' has a thickness of 7 mm. The load was cyclical and sinusoidal with a frequency of 10 to 20 Hz until the sheet metal strip broke 10 and / or socket 2 and / or fillet weld 4 ' . Furthermore, a load ratio is R = 0.1 (underload / overload); Tensile swell area).

In the 2 are triangles with the reference numerals 17th provided, the triangles 17th Results of vibration tests with welded-on bushings 2 represent. Next are diamonds with the reference number 18th provided, with the rhombuses 18th the sockets 2 by means of arc soldering on the sheet metal strip 10 are attached.

It can be seen that for the sockets 2 , which by means of arc soldering on the metal strip 10 are attached, compared to sockets 2 , which by means of a welded connection with the sheet metal strip 10 are connected, at the same load level there is approximately a doubling of the tolerable load changes.

3 shows fillet welds 14th , 24 a weld (left) and an arc soldering (right). In the left part of the figure is a fastening element 12th of structural steel 11 via a weld seam 14th connected, while in the right partial figure a fastening element 22nd of structural steel 21st by means of an arc soldering via a soldered seam 24 a solder body is connected. During the structural steel 11 is considerably weakened by the weld in the left part of the figure, it can be seen in the right part of the figure that the soldering has a small influence on the structural steel 21st Has. Consequently, when arranging the 3 left of a notch class 80 be assumed while the arrangement of the 3 on the right has a notch class of about 100 to 110.

• - Anordnen eines Befestigungselements 2 an einer Wand 1 eines Turms einer Windkraftanlage;
• - Schmelzen des Lots mittels eines Lichtbogens oder mittels eines Schweißgeräts, wobei das Lot hierbei auf das Befestigungselement 2 und/oder auf die Turminnenwand 1 aufgebracht wird, wobei die Wand 1 und das Befestigungselement 2 in einem festen Aggregatszustand bleiben;
• - Bilden eines Lotkörpers 4 mit einer Kehlnaht; und
• - Verbinden des Befestigungselements 2 mit der Wand 1 mittels der Kehlnaht des Lotkörpers 4.

The invention also provides a method for producing the fastening arrangement 5 provided. The procedure consists of the following steps:

• - Arranging a fastener 2 on a wall 1 a tower of a wind turbine;
• - Melting of the solder by means of an electric arc or by means of a welding device, the solder here being applied to the fastening element 2 and / or on the inner wall of the tower 1 is applied, the wall 1 and the fastener 2 remain in a solid state of aggregation;
• - Forming a solder body 4th with a fillet weld; and
• - Connect the fastener 2 with the wall 1 by means of the fillet weld of the solder body 4th .

The solder can be fed in during the process, in particular in the case of the process variants MSG arc melting and WSG arc melting. An arrangement of the solder before the process is often typical for soft and hard soldering processes with a flame. In this respect, processing by means of arc soldering is simpler in terms of process technology compared to conventional soldering processes.

During the melting of the solder and the manufacture of the solder body 4th a protective gas, typically argon or argon-rich mixed gas or, in certain cases, also helium or helium-rich mixed gas, is supplied so that oxidation of the materials used can be prevented or reduced. Alternatively, a vacuum, for example a rough vacuum or a fine vacuum, can also be present to prevent or reduce the oxidation of the connection partners. Further steps can be added to the method, with the features of the fastening arrangement described above 5 correspond.

Features described only in the figures can be combined with features from the above description and claimed individually.

Claims (12)

Fastening arrangement (5) for fastening components to a wall (1) of a tower of a wind power plant, the fastening arrangement (5) having a fastening element (2) and a solder body (4), the fastening element fixed to the by means of the solder body (4) Wall (1) is connected, characterized in that the solder body (4) is designed as a fillet weld, wherein the fastening element (2) and the wall (1) at least partially bear against one another. Fastening arrangement (5) according to Claim 1 , characterized in that the solder body (4) is ring-shaped or U-shaped. Fastening arrangement (5) according to one of the preceding claims, characterized in that the wall (1) has a first surface and the fastening element (2) has a second surface, said surfaces being oriented essentially perpendicular to one another, and the solder body (4) ) forms a solder bridge between the first surface and the second surface. Fastening arrangement (5) according to one of the preceding claims, characterized in that the solder body (4) is produced by arc joining, in particular arc soldering, and / or the solder body (4) is flux-free. Fastening arrangement (5) according to one of the preceding claims, characterized in that the fastening element (2) is fastened with an end face (8) to the wall (1) and comprises a through hole (3) which extends from said end face (8) extends up to one of said end faces (8) opposite end faces (9) and / or has an internal thread (6). Fastening arrangement (5) according to one of the preceding claims, characterized in that the solder body (4) is formed by a copper-based solder, a nickel-based solder, a cobalt-based solder or an iron-based solder. Fastening arrangement (5) according to one of the preceding claims, characterized in that the solder body (4) has a lower modulus of elasticity than the wall (1) and / or the fastening element (2), the modulus of elasticity of the solder body (4) preferably less than 1 , 3 * 10 ⁵ N / mm ² . Fastening arrangement (5) according to one of the preceding claims, characterized in that the solder body (4) has a melting temperature of at least 900 ° C and / or at most 1200 ° C. A method for producing a fastening arrangement (5), comprising the steps: - Arranging a fastening element (2) on a wall (1) of a tower of a wind turbine; - Melting the solder, wherein at least the wall (1) remains in a solid state of aggregation; - Forming a solder body (4) with a fillet weld; and - Connecting the fastening element (2) to the wall (1) by means of the fillet weld of the solder body (4), the fastening element (2) and the wall (1) resting against one another at least in some areas. Procedure according to Claim 9 , the steps of melting the solder and / or forming the solder body (4) taking place with the supply of a protective gas or in an at least partial vacuum. Method according to one of the Claims 9 or 10 , characterized in that the solder is melted by an electric arc. Method according to one of the Claims 9 to 11 , characterized in that the fastening arrangement (5) of the Claims 1 to 8th will be produced.

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