Patent Description:
Wind turbines with wind turbine rotor blades are widely known from the state of the art and are used to convert wind energy into electrical energy. Wind turbines comprise a multitude of components which are connected to each other, for example by means of a flange connection. For example, in the area of a rotor blade root, the rotor blades comprise a rotor blade connection via which the rotor blades are connected to a bearing ring of a so-called pitch bearing or to a component connected to the bearing ring, such as a so-called extender for a wind turbine rotor blade. Further, such connections are also used for connecting rotor blade segments which, arranged and joined together lengthwise, form an entire rotor blade. Such a rotor blade is called a split or segmented rotor blade.

For example, for a connection, a rotor blade or rotor blade segment comprises a number of connecting means integrated into the laminates. The connecting means can, for example, be designed as transverse bolts or bushings, both having inner threads, and be part of a flange insert for the rotor blade connection. For example, rotor blade segments can be connected to each other by means of bolts either directly or via suitable intermediate pieces.

Wind turbine rotor blades are generally made of glass or carbon fiber laminates infused by curable resin, so called fiber reinforced plastics, which themselves are not well suited for the above-mentioned connections. A known approach in the prior art (e.g. <CIT>, <CIT> and <CIT>) is to embed inserts in the form of metal bushings at an end face of the wind turbine rotor blade root area. These bushings extend perpendicular to the end face and longitudinally in the general direction of the rotor blade. The bushings typically comprise a cylindrical part with an at least partially threaded axial bore in an end face perpendicular to the longitudinal axis of the cylindrical part. The other end of the bushing typically comprises a part with a taper.

Typically, quite a lot of space is provided between the connecting means, e.g. inserts. <CIT> suggests elongate spacers adapted to be placed in gaps between inserts of a connection of a wind turbine blade part. These spacers are made of a fiber mat of a predetermined shape and rolled into a coil shape. The spacers are later on impregnated with curable resin, e.g. together with other/further layers in the connection region, e.g. surrounding inserts and the like. Such spacers are usually manually manufactured by persons. These spacers are simple wound coils, and not pre-cured and they may, unlike rigid spacers (e.g. manufactured by pultrusion or other pre-cured fiber reinforced composites), be able to adapt their shape when they are inserted into the gaps between the wrapped inserts. For example, this will ensure good contact between the fibers in the mats wrapped around the inserts and the fibers in the mats of the spacer, thus ensuring the desired high fiber volume fraction in the resin matrix between the inserts. This is because the spacer is deformable and thus may be pressed into and filling the gap between two wrapped inserts entirely. The risk that areas with a low concentration of fibers may occur is thus reduced.

Another prior art technology is disclosed in <CIT>.

One task underlying the present invention is to provide an improved concept for manufacturing a fiber mat of a predetermined, coiled shape, e.g. a spacer meant to be placed in the gap between the inserts of such a connection structure.

The object is solved by the independent claims and the respective sub-claims.

According to the invention a device for rolling a fiber mat for a wind turbine rotor blade is disclosed. The device comprises a working surface. The device comprises a shaft being slidably and rotatably supported. The shaft is slidable in a sliding direction between a start position and an end position along the working surface. The shaft is rotatable in the opposite direction to the sliding direction, wherein with respect to the working surface the shaft rotates as if the shaft were rolling backwards against the sliding direction. The device further comprises a film covering the working surface and being fixedly connected to the shaft with a first end, such that upon rotation of the shaft the film is wound up on the shaft.

The device allows a user to easily roll or wind-up a fiber layer, a fiber mat or generally a fabric layer/mat. In particular a fiber mat can be rolled up to a spacer that is placed in between the above-mentioned (steel) inserts. The spacer can be used instead of pultruded spacers as described above. The device provides several advantages, for example:.

In a general way according to the invention, rolling up the fiber mat with the inventive device works the following way.

After having rolled up the fiber mat, the fiber mat in its rolled-up state can be taken or is released into a corresponding pocket or collector.

In other words, the device is configured and designed such that, after having placed a fiber mat onto the film, wherein the fiber mat is slightly slid under the shaft between the shaft and the film, by sliding the shaft towards the start position and rotating the shaft in the opposite direction the fiber mat is rolled up.

The device is a stable device, e.g. to be placed at a floor. For example, the device is table-like. For example, the device comprises one or more legs to stand on the floor. Optionally or alternatively, the device is designed to be placed onto a table or other stand device. The device comprises supporting means for supporting and guiding the shaft. The device is mainly made of metal, apart from the film (see below). The device further comprises the working surface being, for example, a flat and even surface. the working surface is a table-like platform.

The film, for example, is a foil. In an embodiment, the film has a smooth surface. At least, the film has a surface which allows the fiber mat and the film to slide off each other, e.g. between the fiber mat and the film is no or only little friction. In an embodiment, the film is made of plastic. The film, for example, is a very thin plastic film, e.g. having a thickness of less than <NUM>,<NUM>.

The film spans an area between the first end and a second end of the film facing away from the shaft. For example, at the first end the film is fixed to the shaft lengthwise, i.e. along a longitudinal axis of the shaft. For example, the film defines a support area for placing the fiber mat onto.

The rotation of the shaft is about the shaft's longitudinal axis (axis of rotational symmetry or central longitudinal axis). The rotation in the opposite direction to the sliding direction means that the shaft counter-rotates with respect to the sliding direction. In other words, if you imaginary look at the shaft from above and the shaft is moved forward in sliding direction towards the end position, then the shaft rotates rearwards. In other words again, with respect to the working surface the shaft rotates as if the shaft were rolling backwards against the displacement movement. In yet other words, the shaft rolls to the one side while it is moved to the other opposing side. At this point, we also refer to the figures, e.g. <FIG>, showing this movement of the shaft.

According to at least one embodiment the device comprises a transfer mechanism, wherein the shaft is coupled to the transfer mechanism such that by sliding the shaft in the sliding direction the shaft is forced to rotate. In other words, a movement of the shaft forces a rotation of the shaft. The transfer mechanism transfers a movement of the shaft into a rotation of the shaft. According to one embodiment, the transfer mechanism is a kinematic system or device. In order to cause the rotation of the shaft, the transfer mechanism is supported at least partially stationary with respect to the working surface.

According to at least one embodiment the transfer mechanism is a gear mechanism, the gear mechanism comprising fixed gear means being stationary with respect to the working surface, wherein a first gear is rotatably fixed on the shaft, the first gear being in meshing engagement with a second gear, wherein the axes of rotation of the first and second gears are fixed with respect to each other, and wherein the second gear is in meshing engagement with the fixed gear means. The first gear and second gear move with the shaft in the sliding direction. Since the second gear is in engagement with the fixed gear means, by sliding the shaft the second gear is rotated. This rational movement is transferred to the first gear, which thus rotates the shaft, since the shaft and the first gear is a fixed unit. In other words, the first gear and the shaft are fixed relative to each other and form a rigid unit.

The fixed gear means are for example one or more gears being fixed with respect to the working surface. Alternatively, the fixed gear means is a toothed rack. In other words, the second gear and the fixed gear means are formed as a rack and pinion.

At this point, we note that the described transfer mechanism and its embodiments may be arranged at one side of the shaft. Optionally, it can be arranged on both sides of the shaft.

According to at least one embodiment the device comprises a sledge unit, the sledge unit being slidable in the sliding direction. The sledge unit is slidably supported on the device and is moved in the sliding direction, e.g. between the start position and the end position. the sledge unit is slidably supported on the device via one or more sledge bars. The sledge bars are, for example, fixed stationary to a support (structure) or frame (structure) of the device.

According to at least one embodiment the shaft is coupled to the sledge unit. In particular, the shaft is supported (rotatably) on the sledge unit.

According to at least one embodiment the first and the second gear are coupled to the sledge unit. Thus, the first and second gears are rotatably supported on the sledge unit. By moving the sledge unit, the first and second gears are moved accordingly.

According to at least one embodiment the sledge unit comprises a handling element in order to move the shaft between the start position and the end position. Thus, an easy way is given for moving the sledge unit and thus the shaft. In particular, the sledge unit is moved manually.

It is noted that the handling element, the sledge unit and/or the shaft can also be directly driven by a motor unit, e.g. an electronic drive.

According to at least one embodiment a second end of the film, the second end being opposite to the first end, is fixedly connected to an end of the working surface. Thus, the film is fixed to the device at both ends. Thus, a well-defined area is span for laying the fiber mat onto it. For example, the second end is fixed to the device at an end of the working surface, facing away from the shaft in the start position. This contributes to span an even area with the film covering the working surface. The fixation of the film at the second end is stationary, i.e. it is fixed with respect to the working surface. As an example, the film can be fixed via fastening means, e.g. screws, nails or a rivet. Preferably, as another example, the film is adhesively bonded to the device, e.g. via a double-sided adhesive tape.

According to at least one embodiment the device comprises one or more abutment elements in order to limit the movement of the shaft between the start position and the end position. The abutment elements serve as defined stops for the sliding movement of the shaft respectively the above-mentioned sledge unit. A safely and precise movement is guaranteed between the start position and the end position. This also contributes to very easy handling, since a user just needs to move the shaft against the abutment elements in order to be sure that a complete movement and thus a complete rolling of the fiber mat has been performed.

According to at least one embodiment the device comprises a guide element on both sides of the working surface, in order to slidably support the shaft and/or the sledge unit. For example, the device, e.g. a stand or support, comprises one or more guiding rails or bars, e.g. a tab protruding horizontally, on which the shaft is slidably supported. The one or more guiding elements are arranged on one side of the shaft or on both sides, e.g. at axial ends of the shaft. For example, the guiding elements are breakthroughs or slits, through which the shaft is passed through, the breakthroughs or slits extending along the working surface in the sliding direction and defining the sliding movement of the shaft.

Additionally or alternatively the handling element can be slidably supported, e.g. analogously as above.

According to at least one embodiment the device comprises a collector bucket, which is arranged adjacently to the working surface in the area of the end position. The collector bucket being configured to collect a rolled-up fiber mat when the shaft is slid to the end position. The collector bucket is arranged adjacent to or near to the second end of the film. In particular, if the shaft reaches the end position (or close to reaching it), the rolled-up fiber mat is pushed into the collector bucket, e.g. falls into it. For example, an inclined surface joins or follows the surface, which in particular slopes downwards (i.e. along the direction of gravity). Thus, a finished fiber-mat simply can fall into the bucket when the shaft is reaching or has reached the end position.

According to another aspect a method is disclosed for rolling up a fiber mat to a coil with a device according to any of the preceding claims, the method comprising the following steps:.

The method essentially enables the above-mentioned advantages and functions. The above-described features and embodiments according to the first aspect similarly apply to the method.

According to at least one embodiment - in the step of pushing - the front end of the fiber mat is pushed under the shaft and behind the shaft against the film such that the film forms a pocket behind the shaft. In other words, the film forms a loop. In this loop, the fiber mat is rolled and kept during the movement and rotation of the shaft.

According to at least one embodiment - after the step of laying - glue is provided at least partially onto the surface of the fiber mat. This helps to keep the fiber mat in the rolled-up state. In other words, when rolled-up layers of the fiber mat are stuck together. For example, a lower half of or a third of the fiber mat is provided with the glue. Glue is also named adhesive. The glue can be manually or automatically be provided onto the mat, e.g. by spraying.

According to at least one embodiment - prior to the step of pushing - the fiber mat is folded at the front end to form a folded section, and wherein the fiber mat is pushed with the folded section at least partially under the shaft. This contributes to rolling-up the fiber mat, in particular the start of the rolling is improved. In other words, this helps that the rolling-up of the fiber mat in the pocket reliably starts, when the shaft is initially moved out of the start position and rotated.

According to at least one embodiment the fiber mat is folded such that the folded section is facing away from the working surface.

Further advantages, features and functions are given in the following exemplary embodiment of the invention, which are explained in connection with the figures. Identical, similar or similarly acting elements are provided with the same reference signs in the figures.

<FIG> shows a schematic view of a wind turbine <NUM>, which comprises a tower <NUM>. The tower <NUM> is fixed to the ground by means of a foundation <NUM>. At one end of the tower <NUM> opposite to the ground a nacelle <NUM> is rotatably mounted. The nacelle <NUM>, for example, comprises a generator which is coupled to a rotor <NUM> via a rotor shaft (not shown). The rotor <NUM> comprises one or more (wind turbine) rotor blades <NUM>, which are arranged on a rotor hub <NUM>.

During operation, the rotor <NUM> is set in rotation by an air flow, for example wind. This rotational movement is transmitted to the generator via the rotor shaft and, if necessary, a gearbox. The generator converts the kinetic energy of the rotor <NUM> into electrical energy.

<FIG> shows an exemplary wind turbine rotor blade <NUM>. The rotor blade <NUM> has the shape of a conventional rotor blade and has a rotor blade root area <NUM> facing the rotor hub <NUM>. The rotor blade root area <NUM> typically has an essentially circular cross-section. The rotor blade root area <NUM> is followed by a transition area <NUM> and a profile area <NUM> of rotor blade <NUM>. The rotor blade <NUM> has a pressure side <NUM> and an opposite suction side <NUM> with respect to a longitudinal extension direction <NUM> (also main extension direction). The rotor blade <NUM> is essentially hollow inside.

In the rotor blade root area <NUM> a rotor blade connection end <NUM> with a flange connection <NUM> is provided, by means of which the rotor blade <NUM> is mechanically connected to a pitch bearing or an extender.

The rotor blade <NUM> exemplarily also comprises a division area <NUM> where a blade root-side rotor blade segment <NUM> and a blade tip-side rotor blade segment <NUM> are connected to each other. For this purpose, both segments <NUM>, <NUM> each comprise a segment connection ends <NUM>, <NUM> (also connection regions). The rotor blade <NUM> is thus a split rotor blade as described above. Embedded into each connection end <NUM>, <NUM> is a multitude of inserts (e.g. sleeves or bushings), which are arranged according to the profile (in circumferential direction) and, for example, comprise internal threads for the reception of screw bolts, also called bearing bolts or connecting bolts. A connection end <NUM>, <NUM> is realized for example as a flange insert, which is inserted as a prefabricated insert into a production mould for the manufacture of the rotor blade <NUM>. However, it is also conceivable that no flange insert is provided and the bushings are embedded and laminated directly into the rotor blade half shells. The inserts are made of steel, for example. Similarly, inserts may also be provided at the rotor blade root end <NUM> for connection to the pitch bearing or the extender as described above.

<FIG> shows a schematic, partial section view of a segment <NUM> of the connection end <NUM> (this similarly applies for connection ends <NUM>, <NUM>). The segment <NUM> has a multitude of inserts <NUM> with boreholes <NUM>, typically being embedded into one or more layers of fiber mats laminated together in synthetic resin (details omitted for sake of clarity). For example, to fill a gap arising from a predetermined distance between the inserts <NUM>, spacers <NUM> are provided between two adjacent inserts <NUM>.

An exemplary spacer <NUM> is shown in <FIG>. Such spacer <NUM> is typically made of a fiber mat <NUM> being rolled-up or wound-up, in particular it is simply rolled up to a coil.

Prior to curing the laminate, such spacers <NUM> are placed between each two inserts <NUM> and are, as can be seen from <FIG>, readily deformable in order not to leave a gap between the inserts <NUM> in which a low concentration of fiber and an excessive concentration of matrix resin would be present, in particular after having provided resin to the laminate and cured the segment <NUM>.

The fiber mat <NUM> for the spacer <NUM> according to <FIG> typically has a trapezoidal cut, such that after rolling the mat <NUM>, the rolled-up spacer <NUM> has a different thickness along the longitudinal length of the spacer <NUM>. However, different shapes can be used for the fiber mats <NUM>, e.g. as shown in <CIT>. The fiber mats <NUM> may be prepregs but are preferably dry mats to be infused in situ in a mould when the segment <NUM> is manufactured either as a prefab or directly during manufacturing of a rotor blade half shell as described above.

In the following, a device <NUM> for rolling a fiber mat <NUM> to a coil, e.g. to be used as a spacer <NUM>, according to an embodiment of the invention is described by the help of <FIG>.

With regard to <FIG>, the device <NUM> is a stable device to be placed onto a floor (<NUM>) or table. The device <NUM> comprises a rigid support structure <NUM>, which is optionally covered by a fairing <NUM>. The support structure <NUM> can also be seen as a ground structure, base structure or support frame. The support structure <NUM> comprises a stand <NUM> for support on the floor or table. The stand <NUM>, for example, comprises two legs, e.g. U-shaped, as shown in <FIG>.

The device <NUM> comprises a fixed, i.e. stationary, working surface <NUM>, being fixedly coupled with the support structure <NUM> (at least indirectly). The working surface <NUM> is provided by a (flat) plate <NUM>.

At both lateral sides <NUM> of the working surface <NUM> the device <NUM> comprises to vertically (in Z-direction according to the coordinate system of <FIG>) extending side walls <NUM> (only one side wall <NUM> is visible in <FIG>), in particular limiting the working surface <NUM> at the lateral sides <NUM>. The side walls <NUM> are part of the support structure <NUM> or at least indirectly fixed to it.

The device <NUM> comprises a sledge unit <NUM>, which comprises a handling element <NUM>. The handling element <NUM> is formed as a handling shaft and extends over the working surface <NUM>, e.g. in Y-direction according to the shown coordinate system. The sledge unit <NUM> is slidably supported on the device <NUM> at both lateral sides <NUM> of the working surface <NUM>. In the embodiment according to the <FIG>, the sledge unit <NUM> is slidably supported on a sledge bar <NUM> arranged along each side wall <NUM> (only one visible), each sledge bar <NUM> extending horizontally (X-direction according to the shown coordinate system). In the shown embodiment, the sledge bars <NUM> are arranged outside of the side walls <NUM> and the handling element <NUM> extends over the side walls <NUM> and over the working surface <NUM>. Optionally, the handling element <NUM> can be slidably supported on the side walls <NUM>. The sledge bars <NUM> are part of the device <NUM>, i.e. stationary fixed or arragned.

The sledge unit <NUM> can be slid in a sliding direction <NUM> forth and back, in particular between a start position <NUM> and an end position <NUM>. The sledge unit <NUM> can be slid manually via the handling element <NUM>.

The sledge unit <NUM> comprises a shaft <NUM>, which is coupled to the sledge unit <NUM> and extends in parallel to the handling element <NUM>. In particular, each side wall <NUM> comprises a guide element <NUM> in the form of a slot (only one visible), through which the shaft <NUM> passes and extends slightly over the working surface <NUM>. The shaft <NUM> is rotatably supported on the sledge unit <NUM>. The shaft <NUM> and the handling element <NUM> are fixedly coupled to the sledge unit <NUM> with respect to their longitudinal axes <NUM> and <NUM>. The longitudinal axis <NUM> of the shaft <NUM> is its rotation axis. Thus, sliding the sledge unit <NUM> in the sliding direction <NUM> is therefore equivalent to moving the shaft <NUM> between the start position <NUM> and the end position <NUM>. In <FIG>, the sledge unit <NUM> and thus the shaft <NUM> are in the start position <NUM>, e.g. the initial position for rolling up a fiber mat, as will be described below.

In order to provide for a defined sliding movement, the device <NUM> has abutment elements <NUM> (at the start position <NUM>) and <NUM> (at the end position <NUM>) at both lateral sides <NUM>, which limit the sliding of the sledge unit <NUM> and/or the shaft <NUM> respectively. In the shown embodiment, the first abutment elements <NUM> are vertically protruding elements mounted to the side walls <NUM>, which abut against the handling element <NUM>. At the end position <NUM>, the second abutment elements <NUM> are formed by the end of slots <NUM> to abut against the shaft <NUM>.

The device <NUM> further comprises a film <NUM>, which covers the working surface <NUM>. In particular, the film <NUM> lays on the working surface <NUM>, thereby defining a support surface for the fiber mat to be rolled. The film <NUM> comprises a rectangular shape and is made of plastic. The film <NUM> comprises a first end <NUM> and an opposite second end <NUM>. With the first end <NUM>, the film <NUM> is fixedly connected to the shaft <NUM>. For example, the first end <NUM> is adhesively bonded to the shaft <NUM> along the longitudinal axis <NUM>. With the second end <NUM>, the film <NUM> is fixedly connected (directly or indirectly) to an end <NUM> of the working surface <NUM>, e.g. adhesively bonded to the plate <NUM>. For example, a double side adhesive tape is used.

In the region of the end position <NUM>, the device <NUM> comprises a collector bucket <NUM> for receiving manufactured, rolled-up fiber mats, i.e. fiber coils as shown exemplarily in <FIG>. In the shown embodiment according to <FIG>, the collector bucket <NUM> comprises an inclined surface <NUM> adjacently arranged to the end <NUM> of the working surface. The inclined surface <NUM> could be part of a separate plate/wall or part of the plate <NUM> of the working surface <NUM>. The inclined surface <NUM> runs downwardly at a suitable angle, such that finished fiber coils can fall down to be gathered.

As explained in the introductory part of this disclosure, the device <NUM> allows for an easy rolling up of a fiber mat, in particular in a reproducible quality. For this purpose, a fiber mat is be placed onto the film <NUM> and slightly pushed with an end under the shaft <NUM> against the film <NUM> in the region of the first end <NUM>. Then, via the handling element <NUM> the sledge unit <NUM> and thus the shaft <NUM> is slid in the sliding direction <NUM> from the start position <NUM> towards the end position <NUM>. During this sliding movement, the shaft <NUM> is forced to rotate in a direction opposite to the sliding direction <NUM>. The film <NUM> is rolled on the shaft <NUM> thereby forming a small pocket below the shaft, in which the fiber mat is caused to be rolled up to a coil, if the end position is reached. In the end position, the coil is released automatically into the collector bucket <NUM>.

<FIG> shows a side view of the device <NUM> outside of a side wall <NUM>, wherein the sledge unit <NUM> is in the start position <NUM>. <FIG> shows a corresponding schematic sectional view in the start position <NUM>. As can be seen, the sledge unit <NUM> comprises a mounting plate <NUM>, which supports the handling element <NUM> and the shaft <NUM>. The device <NUM> comprises a transfer mechanism <NUM>, wherein the shaft <NUM> is coupled to this transfer mechanism <NUM> such that sliding the shaft <NUM> causes the shaft <NUM> to be rotated. The transfer mechanism <NUM> is a gear mechanism comprising fixed gear means <NUM>, a first gear <NUM> and a second gear <NUM>. The fixed gear means <NUM> is stationary fixed (at least indirectly) to the support structure <NUM> and is thus stationary with respect to the working surface <NUM>. The fixed gear means <NUM> is a toothed rack. The first gear <NUM> is fixed on the shaft <NUM>, rotating together with the shaft <NUM>. The first gear <NUM> is in meshing engagement with the second gear <NUM>. The axes of rotation <NUM> of the first and second gears <NUM>, <NUM> are stationary with respect to each other. The second gear <NUM> is in meshing engagement with the fixed gear means <NUM>, in particular in all positions of the sledge unit <NUM> and thus the shaft <NUM> between the start position <NUM> and the end position <NUM>.

If the sledge unit <NUM> is slid in X-direction towards the end position <NUM>, the second gear <NUM> is rotated due to the engagement with the fixed gear means <NUM>. At the same time the first gear <NUM> is rotated in a first rotation direction <NUM> counterclockwise with respect to a second rotation direction <NUM> of the second gear <NUM>, since the first gear <NUM> is in constant engagement with the second gear <NUM>. Thus, the shaft <NUM> is rotated in a direction opposite to the sliding direction <NUM> towards the end position <NUM>.

The manufacturing method is now described with respect to <FIG>, wherein <FIG> shows a schematic flow chart.

In a first step S1, the shaft <NUM> is provided in the start position <NUM>, as shown in <FIG> and <FIG>. In <FIG>, the film <NUM> is shown laying on the working surface <NUM>.

In a next step S2, a fiber mat <NUM> is placed onto the film <NUM> along the working surface <NUM>.

In a next step S3, a front end <NUM> of the fiber mat <NUM>, the front end <NUM> facing the shaft <NUM>, is pushed slightly under the shaft <NUM> against the film <NUM>. Optionally, the film <NUM> is pushed slightly behind the shaft <NUM> against the film <NUM> such that the film <NUM> forms a pocket <NUM> (or loop).

In a next step S4, the sledge unit <NUM> and thus the shaft <NUM> are slid in the sliding direction <NUM> towards the end position <NUM> by manually using the handling element <NUM>. Thereby, the fiber mat <NUM> is rolled up.

<FIG> show the sledge unit <NUM> in an intermediate position between the start position <NUM> and the end position <NUM>. Due to the rotation of the shaft <NUM>, the film <NUM> is rolled up onto the shaft <NUM>, however, the combination of movements, sliding in sliding direction <NUM> and rotation in the first rotation direction <NUM>, the fiber mat <NUM> is rolled up in the pocket <NUM>. In <FIG>, the fiber mat <NUM> is already partially coiled and forms a coil <NUM>.

<FIG> show the sledge unit <NUM> and thus the shaft <NUM> in the end position <NUM>, wherein the fiber mat <NUM> is fully rolled up to form coil <NUM> and is in a final step <NUM> automatically released into the collector bucket <NUM>. As can be seen, optionally an opening <NUM> (see also <FIG>) is provided in the collector bucket <NUM>, in order that the finished coil <NUM> can fall down from the device <NUM>, e.g. into a separate box to gather several coils.

In an optional step, after the step S2 of laying the fiber mat <NUM> onto the film <NUM>, glue <NUM> is provided at least partially onto the surface of the fiber mat <NUM> (see <FIG>).

Optionally, prior to the step S3 of pushing the fiber mat <NUM> under the shaft <NUM>, the fiber mat <NUM> is folded at the front end <NUM> to form a folded section comprised of at least two layers of the fiber mat <NUM>. Then, the fiber mat <NUM> is pushed with the folded section at least partially under the shaft <NUM>. In one optional embodiment in this regard, the fiber mat <NUM> folded such that the folded section is facing away from the working surface <NUM>. In other words, the front end <NUM> is not in direct contact with the working surface <NUM>.

The described embodiment provides the mentioned effects and advantages.

We note that the overall design and structure of the device <NUM> can be different. For example, the support structure <NUM> and/or the stand <NUM>, can be formed and constructed differently. Essentially, the device <NUM> must be designed to support the shaft <NUM> to be slidable and rotatable as described above, to provide a working surface <NUM> and to comprise the film <NUM> being connected to the shaft <NUM> with one end <NUM>.

Although providing advantages, the second end <NUM> of the film <NUM> not necessarily needs to be fixed to the device <NUM> in any way, laying on the working surface <NUM> is sufficient.

The film <NUM> can be made of any suitable material, e.g. plastic, which allows that a fiber mat <NUM> can be placed onto it and which has a sufficiently low friction with the fiber mat <NUM>, in order that it can be rolled up in the pocket <NUM> as described above. For example, the film <NUM> is a vacuum foil. Also, the film <NUM> can have different shapes.

Claim 1:
Device (<NUM>) for rolling a fiber mat (<NUM>) to a coil (<NUM>) for a wind turbine rotor blade (<NUM>), the device (<NUM>) comprising
- a working surface (<NUM>),
- a shaft (<NUM>) being slidably and rotatably supported,
wherein
- the shaft (<NUM>) is slidable in a sliding direction (<NUM>) between a start position (<NUM>) and an end position (<NUM>) along the working surface (<NUM>), and
- the shaft (<NUM>) is rotatable in the opposite direction to the sliding direction (<NUM>), wherein with respect to the working surface (<NUM>) the shaft (<NUM>) rotates as if the shaft (<NUM>) were rolling backwards against the sliding direction (<NUM>), and
- a film (<NUM>) covering the working surface (<NUM>) and being fixedly connected to the shaft (<NUM>) with a first end (<NUM>), such that upon rotation of the shaft (<NUM>) the film (<NUM>) is wound up on the shaft (<NUM>).