The invention relates to a clamp coupling for connecting two structural components.

Clamp couplings as such are known, and are used to fix one structural component to another. By clamping the components together in a first direction, friction prevents the components from moving in any other direction with respect to each other, thereby fixing the components together.

In some challenging applications it is necessary to protect the structural components, especially if they are metal components such as steel, from the elements. Different protection techniques exist, one of which is applying a coating. One particular coating technique is powder coating, in which a dry powder is permanently adhered to the component using a curing process involving e.g. heat or UV-radiation. Compared to other coating techniques, powder coating is superior in that powder coated components are generally less susceptible to temperature changes. Additionally, powder coated components can have advantageous structural properties. As such, powder coated components find application in challenging applications, such as construction of steel structures, such as wind turbine masts.

Regardless, some problems arise when using powder coated components in such applications, in particular when the coated components are clamped together to form a structure. It has been found the powder coating reduces the frictional effects of the clamp coupling. The resulting structural rigidity of the clamp coupling has been found insufficient for some applications. Accordingly, a need exists to better couple powder coated components.

The current invention addresses this issue by providing a clamp coupling for connecting two structural components, comprising a first structural component and a second structural component connected to the first structural component, wherein a first surface of the first structural component or a second surface of the second structural component located at an interface between the first structural component and the second structural component is provided with a powder coating layer, wherein a layer of solid particles of a substantially chemically inert material is provided at the interface, wherein the first structural component and the second structural component are clamped together, thereby clamping the layer of solid particles in between them.

It has been found the layer of solid particles at least partially counteracts the detrimental effects of the powder coating with regards to the structural characteristics of the coupling. In particular, including the layer of solid particles may aid in preserving or even increasing the frictional forces between the two clamped components. The invention is based in part on that when a powdered component is clamped, a thin waxy layer may form along the surface of the clamped, powder coated component. The solid particles may bridge the waxy layer by providing a more direct contact between the components. Accordingly, the detrimental effects of the waxy layer, which could detriment the structural properties of the coupling, are reduced or avoided using the solid particles.

The skilled person will thus understand that since the powder coated component itself has particles in its coating layer, the layer of solid particles is an additional powder layer, supplied additional to the powder coating that was already applied to the component(s).

The particles in the layer of solid particles according to the invention may be of another material and/or size than any particles in the coating of the powder-coated component(s).

The layer of solid particles may for instance be sparse, i.e. the layer may have gaps between particles. In an alternative, the layer is a continuous, but possible porous, layer of particles.

The clamp coupling may be effective even when both the first surface and the second surface are provided with a powder coating layer. Accordingly, an effective coupling can be achieved even when both components are protected by a powder coating. As such, the coupling may be useful in demanding applications requiring powder coating components for protecting them from e.g. corrosion.

The skilled person further understands that if both components are powder coated, the layer of solid particles forms an additional layer of solid particles, i.e. a third layer of particles, that is different from the particles in the coating of the powder coated components.

In an embodiment of the clamp coupling, the particles of the layer of solid particles comprise ZnO.

Zinc oxide may be used in particularly challenging applications, for instance in moist or wet environments, or applications involving temperature changes. In particular, such environments include the masts of wind turbines.

In particular, the particles may consist substantially entirely of zinc oxide. In another embodiment of the clamp coupling, the particles of the layer of solid particles comprise glass.

Glass can advantageously be used due to its chemically inert properties in challenging environments. It is possible to combine zinc oxide and glass, and possibly other components as material for the solid particles. However, the particles may also consist substantially entirely of glass.

In yet another embodiment of the clamp coupling, the particles of the layer of solid particles are fixed in a powder coating layer of the first structural component or the second structural component.

By fixing the solid particles in the powder coating layer of one component, the particles may be provided relatively easily at the interface between the components. Moreover, it may be relatively easy to provide an even layer of particles of a desired thickness when only one component is provided with a layer of particles.

In yet another embodiment of the clamp coupler, the particles of the layer of solid particles have a characteristic dimension corresponding to a thickness of the powder coating layer.

The corresponding characteristic dimension may guarantee that the particles are able to break the waxy layer and/or the powder coating layer, in order to allow a mechanical coupling of the two components via the particles, possibly without the waxy layer and/or the coating layer in between.

The characteristic dimension may be the diameter, or the D50 of the particles.

When both components are powder coated, the characteristic dimension may correspond to the thickness of both layers combined.

Corresponding may herein be understood as between 50% smaller to 100% larger, preferably between 30% smaller and 50% larger, more preferably between 20% smaller and 20% larger, most preferably between 10% smaller or larger.

In yet another embodiment of the clamp coupling, the first structural component and the second structural component are clamped together using bolts. Bolts may be used to provide sufficient clamping force to effectively use the particles to increase friction, thereby creating an effective clamp coupling between powder coated components.

The invention also relates to a plate-metal structure comprising a first metal plate and a second metal plate, both of which are provided with a powder coat layer, the first and second metal plate being arranged substantially coplanar with each other, wherein the first metal plate and the second metal plate are fixed to each other by clamping to each of the first metal plate and the second metal plate a connecting component, the connecting component thereby forming a clamp coupling according to any of the preceding claims with each of the first metal plate and the second metal plate.

Using the connecting component, two plate-like components may be attached to each other, thereby allowing the creating of relatively large plate-like structures from relatively small components. Accordingly, the components may be manufactured offsite, and may be transported easily to construction site. As an example, plates may be prepared offsite and be assembled on-site to produce a stacked annular structure, such as a wind turbine mast.

In order to further strengthen the connection between the two metal plates, two connecting components may be provided on opposing sides of the first metal plate and the second metal plate, and the two connecting components may be clamped towards each other thereby clamping the first metal plate and the second metal plate in place.

The invention also relates to a method of fixing at least two structural components together, wherein at least one of the at least two components is powder coated at at least the interface of the at least two structural components, wherein a layer of solid particles of a substantially chemically inert material is provided between the at least two structural components at the interface, and the at least two structural components are clamped together.

The method may result in a reliable coupling between the at least two structural components. The method may result in the clamp coupling as described above, with any of the above-presented features or characteristics, in any suitable combination or by themselves.

In particular, the layer of particles may be provided on a powder coated one of the structural components before clamping the components together.

Accordingly, the clamp coupling may be made relatively easily, for instance off-site. layer of particles may be applied to the powder coated structural component by softening at least a part of the powder coat layer and introducing the solid particles to the softened coating.

Using the powder coating to use apply the particles results in a relatively elegant method, as no adhesives are needed to apply the particles.

In particular a solvent may be used to soften the coating. A solvent may be able to locally soften the powder coating, thereby affecting only those parts upon which the particles are later applied. Accordingly, other parts of the powder coating may remain intact.

The invention will be further elucidated with reference to the attached drawings, wherein:

Figure 1 shows schematically a cross section of a plate metal structure;

Figure 2A shows schematically a top view of an annular plate metal structure; and Figure 2B shows schematically a side view of multiple stacked plate metal structures forming a mast of a wind turbine.

Throughout the figures, like elements are referred to using like reference numerals. Like elements across different embodiments are referred to using reference numerals increased by 100 (one hundred).

Figure 1 shows a first metal plate 1 and a second metal plate 2. The metal plates 1, 2 are arranged coplanar, and are both powder coated. The metal plates 1, 2 are attached by a clamp coupling, comprising two connection components 3, 4 on opposing sides of the metal plates 1, 2. The metal plates are also powder coated. Each connection component 3, 4 is provided with a layer of solid particles 5, 6 on a side facing the metal plates 1, 2. The solid particles 5, 6 are applied in the powder coating layer of the connection components 3, 4 by softening the coating using a solvent before applying the solid particles. As explained above, the layer of solid particles thus applied, is an extra layer, i.e. additional to the particles of the powder coating. The particles of the layer of solid particles may be applied in the coatings, which themselves include particles. Nevertheless, the layer of solid particles may remain readily distinguishable by those skilled in the art, for instance due to different materials used or different particle size. The solid particles comprise ZnO. Alternatively glass or a mixture of the two, or another chemically inert solid could be used. The connection components 3, 4 are clamped together using bolts 7 tightened by nuts 8. Accordingly, the metal plates 1, 2 are clamped between the two connection components 3, 4 and held in place due to frictional forces at the interface of each connection component 3, 4 with each metal plate 1,

2. The layer of solid particles 5, 6 is provided at the interface between the connection components

3, 4 and the metal plates 1, 2. Due to the clamp coupling, the metal plates 1, 2 are fixed together. Figure 2A shows a part of an annular structure 109 as atop view. The annular structure 109 consists of a repeating pattern of metal plates 101, 102, which are angled. The metal plates 101, 102 are connected together using connection components 103, 104 as detailed in figure 1. Due to the metal plates 101, 102 being angled, a repeating pattern of the metal plates 101, 102 results in an annular structure 109. The size and amount of metal plates 101, 102 can be chosen as desired.

Figure 2B shows a side view of a part of a mast 110 of a wind turbine. The mast is formed by multiple annulare structures 109 which are stacked. Each annular structure 109 is attached to the one below and/or above using clamp couplings as described above. Connection components 103 of the clamp couplings are visible in figure 2B. The amount of annular structures 109 to form the mast can be chosen as desired.

Although the invention has been described-above with reference to particular examples and embodiments, the scope of the invention is not limited thereto. In fact, the invention is defined also by the attached claims.