Method for manufacturing preforms for a wind turbine blade, manufacturing arrangement for manufacturing preforms for a wind turbine blade, and mould for a manufacturing arrangement

The invention refers to a method for manufacturing preforms for a wind turbine blade.

As commonly known, a wind turbine comprises among others sev eral turbine blades attached to a hub. The blades interact with the wind making the hub rotate. To the hub a generator is coupled, which is driven by the rotating hub. The turbine blades of nowadays turbines have enormous dimensions in length and width. Their manufacturing is therefore difficult, as big parts need to be handled. One technology for producing such large blades uses preforms, which are preformed smaller blade parts used for building the respective blade shell. These prefabricated preforms are arranged and aligned accord ing to the requested overall geometry of the blade and are finally connected respectively embedded in fiber mats and resin etc. for manufacturing the final large blade or blade part.

Each preform, which usually has a slightly bended geometry with a length of for example 10 - 12 m and a width of for ex ample 3 - 5 m, is prefabricated in a specific mould. The mould comprises a respective form part, in which the preform building elements like fiber mats and a binding agent and, optionally, core elements, are arranged. These elements are consolidated in the respective mould part by applying a vacu um, which mould part has a defined geometry corresponding to the requested blade geometry. For this consolidation the pre form building elements are covered with for example a foil, so that the vacuum can be applied to the space between the foil and the mould part, in which the building elements are arranged . Afterwards heat is supplied to the building ele ments in order to melt the locally positioned binding agent for locally fixing the fiber mats and the core elements etc. by gluing them in the binder matrix provided by the molten binding agent. After this heating operation the preform needs to be cooled to room temperature, whereafter it is suffi ciently stable to be handled by a crane equipment or any oth er comparable handling or lifting means, usually a vacuum suction lifting equipment.

This way of producing the preforms is quite cumbersome. The moulds used for producing the preforms are very complicated in their set-up, especially as a heating and cooling system needs to be provided in every mould. This makes the mould very expensive, having in mind that a large number of sepa rate moulds is necessary, as usually at least twenty or more preforms are needed for producing a blade or blade part. Fur ther, as the respective mould geometry is designed for a re spective geometry of the preform, an extensive reworking of the mould is necessary, when the preform geometry shall be changed, entailing also the adaption of the heating and cool ing equipment.

Further, as both the heating and cooling treatment is per formed with the preform building elements respectively the hot preform being arranged in the mould, the mould is occu pied. As the heating and the cooling process takes a remarka ble time, the whole mould is blocked during these long- lasting procedures, the productivity is extremely low. This is even enhanced, as the mould cannot be preheated. The tem perature treatment thus needs to start from room temperature, as all building elements need to be separately arranged in the mould before their vacuum consolidation, whereafter the heating may start. Further, it is necessary to cool down the hot preform to room temperature in order to secure its sta bility for handling it with the lifting equipment. Further, the time during which the respective mould is occupied may even be extended, as sometimes a preform is not removed imme diately after cooling it, but instead remains for a certain time in the mould if no storing capacity is given. Finally, after lifting the preform out of the mould, it is necessary to thoroughly clean the mould surface for the next manufacturing process, which cleaning step also takes its time. Still the mould cannot be used, until this cleaning step is finished.

It is therefore an object of the invention to provide an im proved method for producing a preform for a wind turbine blade.

To address the object, the invention proposes a method for manufacturing a preform of a wind turbine blade, with the steps:

Providing a mould and arranging a preform building mate rial in a transferable mould element removably arranged on a mould carrier,

Fixating the preform building material on the mould ele ment,

Removing the mould element with the fixated preform building material from the mould carrier and transferring it into a heating means,

Heating the preform building material for producing the preform,

Removing the mould element with the preform from the heating means and cooling the preform.

According to the invention, a specific new mould type is used for manufacturing preforms. This mould type comprises a mould carrier, to which a mould element, which provides a mould surface corresponding to the geometry of the preform to be built, is removably fixed. The mould element is therefore transferable and can be removed from the carrier. The mould itself respectively the mould element is only used for ar ranging and fixating the building material on it. Right after placing and fixating the building material, the transferable mould element is removed from the mould carrier and is trans ferred to a heating means, for example a heating oven, in which the building material is heated respectively the bind ing agent is molten and/or activated for fixing or adhering respectively gluing the fiber material like fiber mats and/or the core elements etc. in the binder matrix. After this heat treatment the preform is cooled for example to room tempera ture by a cooling treatment, whereafter the final preform can be lifted from the transferable mould element with a respec tive lifting equipment.

During the whole manufacturing process the building material respectively the preform is arranged on the movable mould el ement and is therefore moved with the mould element between the respective manufacturing stations. As this mould element is plate-like with a tray-like element surface, the whole construction set-up of this mould element and the building elements respectively the preform itself is quite thin and therefore very easy to handle. Following the placement and fixation of the building material, for example by vacuum fix ation, the plate- or tray-like mould element can be removed from the mould carrier and transferred to the heating means for further processing.

This inventive method shows a bundle of advantages. As the mould itself is solely used for arranging the building mate rial on the mould element and for fixing it to the mould ele ment, no heating or cooling treatment is performed in the mould. Therefore, the mould design is very simple, as no heating or cooling equipment needs to be provided at the mould. Further, as the mould carrier, which may be a frame like carrier or the like, is not exposed to any heating or cooling, it will be dimensionally stable and last longer, as it is solely carrying the mould element and the building ma terial.

As only the packing is done in the mould and right after fin ishing this packing the mould element is removed, immediately afterwards a new mould element may be arranged on the mould carrier . This allows to immediately start with the arrange- ment of new building material on the mould element of the same mould, which was occupied short time before. This allows to remarkably increase the throughput and the capacity. As usually a certain number of separate moulds are provided, an ongoing production may be realised, as it is only necessary to provide a respective number of separate mould elements, which can be interchanged with the respective mould carriers.

As only the mould element with the fixated building material needs to be removed from the mould carrier for the further processing, no specific lifting means directly at the mould is necessary, as the plate- or tray-like mould element may simply be removed from the mould carrier for example by a linear pushing or pulling action.

As the heating is performed in a heating means separate from the mould, which heating means is solely used for heating the building material, this heating means respectively the oven can be pre-heated, so that it is constantly held on the re spective process temperature. It is preferred that the heat ing means has a respective capacity, so that several plate- or tray-like mould elements with building material may be simultaneously arranged in the heating means respectively the oven, which further contributes to raising the capacity and the throughput of the manufacturing arrangement. The building material is heated e.g. to a temperature of 80°-100°.

Further, as the building material respectively the preform is arranged on the movable mould element throughout the whole manufacturing process, the handling is improved, as it is not necessary to get in contact with the preform element at any time until it is finally produced. Further, as the mould ele ment together with the vacuum cover, e.g. a foil, provides a perfect protection of the preform, it is possible to store the mould element with the preform in stock after the cooling process . Thus, contamination of the preform with e.g. dust particles, moisture penetration and/or material degradation can be avoided. When the preform is removed from the mould element, the mould surface of the mould element may receive immediately a sur face treatment before it is again placed on the mould carri er. As the system comprises several mould elements, there is always a clean mould element at hand right after a mould ele ment with the fixated building material is removed from a mould carrier, so that the new mould element can be placed on the mould carrier and a new cycle may start.

The inventive method allows for a remarkably higher through put in the production of preform elements, as the steps of arranging and fixating the building material are the only steps performed directly at the mould, while the heating and cooling steps are separated and are solely performed using the removed mould element with the fixated building material.

As mentioned, the mould element is a multi-functional ele ment. It is used as the receiving element, which receives the building material and which defines the shape and/or form, in which the building material is arranged. It is further a fix ation element, as together with the vacuum foil it is used for fixating the building material. Further, it is used as a transport element, as it is removed and transported from the mould carrier through the following manufacturing stations, always securing that the fixated building material or the preform remains in shape. To accomplish these multi functional characteristics, a mould is used comprising a mould carrier with a removable stiff tray-like mould element providing a mould surface on which the building material is arranged . According to this embodiment, the mould element it self is stiff and completely stable in its form. It is pref erably made of a plate which is formed or machined to provide the respective mould surface on which the building material is arranged. The mould element respectively the plate it may be made of has a thickness of for example 2 -5 cm. As the mould element itself is stiff, form stable and heat resistant even at elevated temperatures i.e. well above the temperature applied in the heating means, the stability of the vacuum- fixed building material is ascertained, as the mould element itself provides this stability, although the building materi al is securely fixed by the vacuum.

As mentioned, the building element may comprise at least a fiber material, preferably in the form of fiber mats, be it glass fiber or carbon fiber mats, while also both types of mats may be used in building a preform. Further, the building material comprises a binding agent, usually in the form of a binding powder, granulate or the like but may also be a liq uid or hot melt based binding agent, which binding agent is usually locally applied below, between or above the respec tive fiber material or fiber mats. Further, one or several core elements may optionally be arranged, for example core elements made of wood such as balsawood or a foam, e.g. a synthetic foam, or the like. The stack is locally fixed by the molten binding agent in order to maintain it open for a resin infiltration during the manufacturing process of the turbine blade or blade part.

As also mentioned, the preform building material is fixated on the mould element by at least one vacuum cover covering the preform building material and an applied vacuum. This vacuum cover is preferably a vacuum foil, which is thoroughly placed over the building material and which overlaps with the mould element, whatever kind this mould element is. By apply ing a vacuum between the mould element and the vacuum cover, the space in between, in which the building material is ar ranged, is evacuated and the vacuum cover is sucked towards the mould element, thereby fixating the stacked building ma terial.

Preferably the vacuum established is maintained during any subsequent process steps, and in particular only released at the earliest after the heating process but may also be main tained throughout the cooling process as well and even more only released prior to the preform element is to be released from the mould element and even so only just prior to the preform element is to be used and placed in a blade mould.

The vacuum is preferably established by using appropriate vacuum means such as a pump connected with hoses and valves attached to the vacuum cover allowing to couple and decouple such vacuum means. Thus, the vacuum established may during or prior to any subsequent process steps be checked, e.g. using an appropriate pressure measuring device such as a manometer. If the pressure is above a certain threshold the vacuum can again be brought back to the desired level using vacuum means. The use of e.g. hoses and valves also provides the op tion to blow e.g. air into the vacuum cover as to ease the release of the cover from the mould element and/or preform building material or the preform element after the heating or cooling process step.

As mentioned, after the building material is arranged and fixated on the mould element, the mould element itself is re moved from the mould carrier in order to transfer it to the heating treatment. For transferring the mould element to the heating means, the mould element with the fixated preform building material is transferred from the mould carrier to a mould transport means and either stored in the transport means until it is transported with the transport means to the heating means or directly transported with the transport means to the heating means. According to this embodiment, a mould transport means is provided, which is adapted to re ceive at least one mould element with the respective fixated building material. This transport means now may either serve as a kind of buffer, which allows to store the at least one or, if it is adapted to store more than one mould elements, the several mould elements until the time they will be fur ther processed in the heating means. In an alternative the transport means may directly transport the one or the several mould elements to the heating means.

Preferably, more than one mould elements are transferable to a common, preferably rack-like transport means. The transport means thus is adapted to receive a certain number of mould elements with preform building material, for example five to ten. The transport means respectively the rack has respective compartments, for example arranged vertically stacked, with each compartment receiving one mould element. This allows to either store a higher number of mould elements in the rack like transport means for buffering them, or for moving the higher number simultaneously directly to the heating means.

For collecting the several mould elements in the tray-like transport means, the transport means moves from a first mould carrier for receiving a first mould element to one or more further mould elements. For this purpose, the transport means may move or be moved on respective rails or guides arranged in or on the floor, e.g. along a row of separate moulds or mould carriers for collecting the respective mould elements for further processing.

After the transport means has received the one or the several mould elements, they are transferred to the heating means, either directly or after a certain delay. For moving the mould elements into the heating means like the oven, several alternatives are feasible. According to a first alternative the transport means with one or more mould elements moves in to the heating means. Here the transport means itself with the mould elements moves into the oven and remains with them in the oven during the entire heat treatment. In an alterna tive embodiment, one or more mould elements are moved from the transport means into the heating means. Here the transport means moves in a transfer position, in which the or each mould element is transferred from the transport means into the oven for the heat treatment. The transport means in this embodiment can immediately return and start again col lecting mould elements. In this embodiment, the heating means respectively the oven has separate compartments each receiv ing a mould element, as preferably the oven has a dimension which allows to process an enlarged number of mould elements simultaneously . So, it is either dimensioned and comprises a certain number of compartments to receive a respective number of mould elements, or it is dimensioned to receive the whole transport means with the mould elements. In any case the oven may be designed to house several mould elements or mould ele ment transport means placed parallel or in extension of one another.After the heat treatment, the mould elements respec tively the now generated preform needs to be cooled. While the first step regarding the arrangement of the building ma terial and the fixation of the same is the only step per formed on the mould, the following processes are separate from the mould, also the cooling process is separated from the heating process respectively the oven. This means that the hot preforms and mould elements will not stay in the oven during the cooling process, which allows to immediately use the heating means again right after the mould elements are removed from the oven.

The cooling process may also be performed in various ways. It is possible that after the heating the one or more mould ele ments are removed from the heating means and are cooled in ambient air. According to this embodiment the mould elements with the hot preforms are simply moved out of the oven and left to cool down in a cooling area or the like and thus in the ambient air. To avoid that the temperature within the manufacturing facility gets too high due to this cooling, the ambient air cooling should take place in an area outside of the manufacturing building. In an alternative to the ambient air cooling, the mould elements may be moved into a cooling means. Here a specific cooling means, where an active cooling is performed, is provided. Like the heating means, which may be an oven with a respective heating source, the cooling means may also be a housing with a respective cooler like a cooling fan or the like. If the heating means and the cooling means are for example placed close to each other, it is pos sible to establish a kind of energy recycling, as the heat dissipating from the cooling preforms may be transferred to the heating means. As already mentioned, it is possible to either move the transport means, i.e. the rack, with the preferably several mould elements into the heating means, or to move only the separate mould elements into the heating means. If the whole rack is in the oven, preferably only the whole rack with all mould elements is removed from the oven, yet individual ele ments can also be removed from the rack. If the separate mould elements are individually placed in the oven, they may likewise be removed separately from the oven. By removing in dividual mould elements from the oven, this allows to differ ently heat respective mould elements and their preform build ing material, as depending on their respective set-up, e.g. one preform may need a longer heat treatment, while another preform needs a shorter heat treatment. So the introduction of the separate mould elements into, and eventually out again, the oven brings more flexibility regarding the heating process .

Resulting from these various ways of arranging the mould ele ments in the heating means, also various embodiments regard ing the transfer for the next cooling step are feasible. Ac cording to a first alternative the transport means comprising the one or the more mould elements is transferred into the cooling means. Here, as the occupied transport means respec tively rack is in the oven, the whole transport means with the hot mould elements and preforms is moved from the oven into the cooling means like the cooling chamber or the like. Preferably, respective rails or other kind of guides are pro vided allowing a simple transfer of the rack from the oven to the cooler.

In an alternative embodiment the one or more mould elements itself are transferred from the heating means onto a transport means or a further transport means, wherein either the transport means remains or moves into ambient air for cooling, or wherein the transport means moves to the cooling means, with either the one or the more mould elements are transferred into the cooling means or the transport means moves into the cooling means. In this alternative, the sepa rate mould elements arranged in the oven are transferred to and collected on a separate transport means arranged at the exit of the heating means. This transport means, just like the transport means arranged between the moulds and the heat ing means, is adapted to receive a respective number of mould elements with their preforms. Depending on the cooling pro cess two variations are feasible. First, the transport means remains or moves into ambient air for cooling. Here the rack with the preforms either remains close to the heating means or moves to a specific cooling area, where an ambient air cooling is performed. In an alternative, the transport means moves to the cooling means, i.e. the specific ventilation cooler or the like, where either the separate mould elements are removed from the transport means and transferred into the cooling means, where respective separate compartments are ar ranged for receiving them. In an alternative, the whole transport means may move into the cooling means. In any case the cooling means may be designed to house several mould ele ments or mould element transport means placed parallel or in extension of one another.

Finally, it is also possible that the mould elements itself are directly transferred from the heating means into the cooling means. Here, the heating and the cooling means are directly arranged in line and are provided with respective transport devices, so that the mould elements with the pre forms may directly be shifted from the heating to the cooling unit. These transport devices may again be rails or roller guides or the like.

As is obvious, several possibilities for bringing the respec tive hot mould elements with the hot preforms to the cooling means or area(s) are feasible.

After the cooling, the respective fabricated preforms are re moved from the mould element. This is preferably done by a lifting equipment, preferably a vacuum lifting means. With this equipment the respective preforms are either moved to a storage side or directly to the further processing, where the preforms are arranged in a large blade mould for finally pro ducing the blade. If the mould elements with the preforms are arranged on a transport means, they need to be removed from the transport means, for which purpose they may for example be transferred to a kind of conveyor or the like, by which they are transported to the lifting equipment. This may ne cessitate to certainly move the occupied rack out of the cooling unit respectively to move the separate mould elements with the preforms out of the cooling unit in case no ambient air cooling is performed.

The vacuum cover or the like and/or the release film if so used, is eventually removed from the preform element after cooling of the preform e.g. prior to placing the preform into the blade mould.

The invention further refers to a manufacturing arrangement for manufacturing preforms for a wind turbine blade, compris ing

One or more moulds each comprising a mould carrier and one or more assigned mould elements each adapted to fix edly receive preform building material and removably ar- rangeable on the mould carrier,

A heating means adapted to receive at least one of the mould elements, with the preform building material, re moved from the mould carrier.

Preferably, there is a larger number of moulds, for example 5, 10 or 20 moulds. Preferably, the number of mould elements is greater than the number of carriers, so that the moulds may permanently be used, as immediately after removing a mould element with the fixed preform building material a new, cleaned if necessary, mould element may be arranged on the mould carrier and new building material may be arranged on the surface of the mould element. So, for this ongoing cycle process a certain number of separate, interchangeable mould elements are necessary. The mould elements, which are as signed to a common mould carrier, may all be the same, so that this respective mould always produces the same type of preform element. But certainly, in an alternative, the mould elements may also be completely switched between the respec tive mould carriers.

Each mould element may be a stiff tray-like mould element providing a mould surface adapted to receive the preform building material with the mould carrier comprising mould el ement receiving means. In this embodiment, the mould element itself is form stable and for example made from a stiff and rigid plate, which is respectively machined in order to pro vide the respective formed mould surface, onto which the pre form building material is arranged. The mould element may e.g. be 3-D printed i.e. an additive preparation process, casted or form pressed. This stiff mould element is removably placed onto the mould carrier, which may be a simple frame like carrier arrangement, and which is provided with the re spective receiving means. These receiving means may for exam ple be longitudinal rails or bars or the like, on which the stiff mould element is arranged with its longitudinal edges.

The stiff mould element may for example be made of metal like aluminium or made of a sufficiently heat-resistive polymer or wood and may preferably comprise a surface which is not adhe sive to the binding agent. If the surface is adhesive to the binding agent, a release film or similar release agent may be placed on the mould element surface prior to placing the pre form building material. This stiff element may have a thick ness of for example 1 - 5 cm, depending on the material it is made of. The cleaning may be performed with respective auto matic cleaning means, to which the respective mould element is preferably automatically transferred after the preform is removed, and from which the cleaned mould element is recircu lated back to the area with the mould carriers. So it is a circular process starting with the mould section, where the mould elements are placed on the carriers, followed by ar- ranging of the building material, followed for example by the transfer to the transport means, followed by the transfer of the mould elements into the heating means in the above men tioned different ways, followed by the heating step, which is followed by the cooling step, which may also be performed in various ways, whereafter the preforms are removed and further processed, while the emptied mould elements are automatically cleaned and recirculated back to the beginning of the process cycle.

The manufacturing arrangement further comprises at least one mould element transport means adapted to receive one or more mould elements with the fixated preform building elements for transferring the one or more mould elements to the heating means. This transport means, which preferably is adapted to receive several mould elements, is used to transport the one or the more mould elements from the respective mould carriers to the heating oven. It comprises respective receiving or fixation means for the respective mould elements like respec tive rails or bars or the like, on which the edges of the mould elements rest. The transport means may either transport the mould elements directly to the heating means or first to a storing location and afterwards to the heating means.

Furthermore, the mould element transport means is adapted to receive the rectangular mould elements by receiving it from the longitudinal element side or from the shorter element side. The mould element may therefore either be inserted from the side vertical to the longitudinal axis or from the front along the longitudinal axis.

The mould element transport means, which is adapted to re ceive several mould elements, preferably comprises vertical movable mould element receiving means for vertically stacking the several mould elements. Here, the transport means respec tively the rack is provided with a kind of paternoster lift or the like, thus any kind of elevating means, which allows for example to take the first mould element in the lowest po- sition, whereafter this first mould element is lifted, until a second mould element may be introduced, both of which ele ments are then lifted etc. This lifting means may for example be circulating chains, belts or the like, to which the re spective receiving elements are arranged. Such arrangement allows the mould elements to easily slide (pushed or pulled) into the receiving means of the mould element transport means with little or no lifting efforts. Accordingly, only a hori zontal movement of the mould elements needs carried out which limited the need for lifting of the mould elements by machine or persons.

The heating means itself may be adapted to receive one, pref erably more mould elements itself. Here, the mould elements with a building material are directly introduced into the ov en. In an alternative, the heating means may also be adapted to receive the transport means comprising the one or more mould elements. In this embodiment the complete rack with the transport elements is moved into the heating means.

If the heating means is adapted to receive the mould elements itself, it may comprise vertically moveable mould element re ceiving means for vertically stacking the several mould ele ments. Again, the mould element receiving means may be an el evator means like a paternoster lift or the like, which al lows to vertically move the mould elements for vertically stacking them. Again, the first mould element is for example received in the lowest position, whereafter it is vertically moved for a first distance, whereafter the second mould ele ment is introduced, both of which mould elements are then again moved vertically, etc. Again, such arrangement provides a horizontal movement only of the mould elements which lim ited the need for lifting of the mould elements by machine or persons.

Further, the arrangement may comprise a cooling means adapted to receive the one or more mould elements with the heated preforms for cooling them. This cooling means allows for an active cooling operation for example by using a cooling fan for removing the heat, wherein the cooling means may be cou pled with the heating means in order to establish an energy recycling . The cooling means, which may be a kind of cooling chamber or cooling box, is adapted to receive one, preferably more mould elements itself, while also the whole transport means comprising the one or more mould elements may be re ceived by the cooling means. Again, just like at the heating means, also here only the mould elements with the heated pre forms may be separately received in the cooling means, or the occupied transport means respectively the rack.

In this circumstance, the transport means received by the cooling means may be the transport means which was previously positioned in the heating means. According to this embodi ment, the transport means respectively the rack is directly transferred from the oven to the cooler, for example automat ically and rail guided. In an alternative, if the oven has received the separate mould elements, the transport means is adapted to receive the one or more mould elements from the heating means.

If the cooling means is adapted to receive the mould elements itself, it may preferably comprise vertically movable mould element receiving means for vertically stacking the several mould elements. Also, the cooling means may be provided with a lifting means like a paternoster lift or any other kind of elevating means, which is adapted to take the separate mould elements . Again, they may be received from the transport means at a lower position, whereafter the first mould element is lifted to a second position, where another mould element is received, etc. Again, such arrangement provides a horizon tal movement only of the mould elements which limited the need for lifting of the mould elements by machine or persons.

As mentioned above, it is possible that certain transfers of a mould element from one position to another position or from one item to another item may be performed. To conveniently accomplish these transfers, transfer means for transferring a mould element from the mould carrier to the transport means and/or from the transport means to the heating means and/or from the heating means to the further transport means or the cooling means or from the further transport means to the cooling means are provided. No matter how the set-up is, the transfer means are provided to ease the transfer from one de vice to a following device of the arrangement. Preferably, these transfer means work automatically, but may also involve partial manual operation like pushing or pulling operation. So, these transfers may be accomplished preferably automati cally by means of respective drive motors or the like, where as in some cases also some manual handling is possible.

The transfer means itself may comprise pushing means arranged at the mould and/or at the transport means, and/or pulling means arranged at the transport means and/or at the heating means, and/or rolling elements arranged at the mould and/or at the transport means bearing the mould elements. These pushing or pulling means may comprise certain pushing or pulling rods or the like, which may automatically couple the mould element to be pushed or pulled e.g. by a motor drive. Also, roller elements may be arranged on respective guide rails or the like, allowing for a simple movement of the heavier mould element with the building material or the pre form, which movement may also at least be initiated by manual pushing or pulling, as the roller elements allow for a very smooth and soft movement. It is to be noted that a mould ele ment, no matter if any kind of transfer means is provided or what kind of transfer means is provided, is preferably locked to the respective device by locking elements. So, the mould element is for example releasably locked to the mould carrier or to the transport means or to the respective mould element receiving means in the heating oven or the cooling unit etc. These locking means may engage automatically, when the mould element is in place, and may also disengage automatically, when it shall be removed. As mentioned, the or each transport means is preferably used for collecting several mould elements from the respective mould carriers or for moving them to the heating means or from the heating to the cooling means etc. Preferably, each transport means is, preferably automatically, movable along respective guiding rails. These preferably floor-based rails ascertain a defined and secure pathway.

Finally, the invention refers to a mould for a manufacturing arrangement as previously described. This mould is character ised by a mould carrier and at least one interchangeable mould element, which mould element is a stiff tray-like mould element providing a mould surface adapted to receive the pre form building material, wherein the mould carrier comprises mould element receiving means.

As the building material is vacuum-fixated on the mould ele ment, the mould carrier also comprises a respective vacuum fixation means for fixing the building material to the mould element using a vacuum cover, e.g. a foil, a vacuum mat or the like, preferably a foil since it is lightweight and easy to handle.

Finally, the mould comprises a transfer means for moving the mould element from the mould carrier, which transfer means preferably comprises a, preferably automatic, pushing means and/or rolling elements arranged at the mould carrier.

Other objects and features of the present invention will be come apparent from the following detailed description consid ered in conjunction with the accompanying drawings. The draw ings, however, are only principle sketches designed solely for the purpose of illustration and do not limit the inven tion. The drawings show:

Fig. 1 is a principle illustration of an inventive mould of a first embodiment, Fig. 2 is a principle illustration of an inventive mould with a transport means for receiving mould ele ments,

Fig. 3 is a principle illustration of a manufacturing ar rangement,

Fig. 4 is a principle illustration of a second alternative for transferring the mould elements into the heat ing means and into the cooling means,

Fig. 5 is a principle illustration of a third alternative for transferring the mould elements into the heat ing means and into the cooling means,

Fig. 6 is a principle illustration of a fourth alternative for transferring the mould elements into the heat ing means and into the cooling means, and

Fig. 7 is a principle illustration of a manufacturing ar rangement of a second embodiment.

Fig. 1 shows a principle illustration of a mould 1 for manu facturing a preform for a wind turbine blade. The mould 1 comprises a mould carrier 2, to which a removable or inter changeable mould element 3 is attached. The mould carrier 2 comprises respective receiving elements 4, for example longi tudinal rails or beams or the like, on which the mould ele ment 3 rests. It may be fixed thereto by respective locking elements, which are released when the mould element 3 shall be removed.

The mould element 3 comprises a tray-like recess 5 with a mould surface 6, on which building material 7 for building the preform is arranged. The building material 7 comprises fiber material like fiber mats made of glass or carbon fi bers, and a binding agent usually in powder or granular form. A liquid or hot melt binder may however also be used. The building material 7 is arranged in the respective order re spectively the needed amounts, wherein the building material

7 obviously follows the tray-like form of the mould surface

6.

After arranging all the building material on the surface 6, a vacuum cover 8 is arranged which overlays the building mate rial 7 and extends also onto the surface 6 of the mould ele ment 3, as fig. 1 shows. The mould carrier is equipped with a vacuum fixation means 9 comprising a vacuum pump and respec tive hoses or the like with valves allowing to couple and de couple the means 9 to the mould element 3, allowing to gener ate a vacuum between the mould element 3 and the vacuum cover

8 in order to evacuate the space between them, where the building material 7 is arranged. This evacuation or vacuum fixation fixes the building material 7 very tightly to the mould element 3.

The mould element 3 itself is a rigid plate-like element, which is made from a respective stiff plate for example made of a metal such as steel, aluminium or the like or a plastics that is heat resistant and form stable during the heating process that will follow. This e.g. steel or aluminium plate is shaped accordingly in order to prepare the tray-like or convex mould surface 6.

As mentioned, the mould element 3 is removable from the mould carrier 2. After vacuum fixation of the building material 7, it is possible to remove the mould element 3 with the fixed building material 7 and the vacuum cover 8 after decoupling it from the vacuum fixation means 9, while the vacuum is maintained between the mould element 3 and the vacuum cover 8, so that also the fixation of the building material is maintained . The mould element 3 can now be moved to a heating means for further processing. Solely, the mould carrier 3 re mains in place and may be equipped with another new and clean mould element 3, on which immediately after removal of the previous mould element 3 a new building material 7 may be ar ranged etc.

The first embodiment according to fig. 1, as mentioned, com prises a stiff and form stable, plate-like mould element 3, which is removably arranged on top of the mould carrier 2, e.g. simply by lowering it on the carrier 2 with a lifting means or by pushing it on the mould carrier 2 with a transport means or by hand. As the mould element 3 itself is stiff, the handling is easy, no form or shape change occurs during the handling and further processing.

Fig. 2 shows the inventive mould 1 according to fig. 1. The mould element 3 with the vacuum-fixed building material is already partially moved from the mould carrier 2. The receiv ing means 4 are equipped with respective transfer means 14 here in form of the respective roller elements 15, on which the mould element 3 rolls and can easily be pushed or pulled in order to transfer it to a transport means 16, here in form of a rack 17. This transport means 16 is movable and guided on respective rails 18, so that it can e.g. automatically move along several moulds 1, which are arranged side by side, one of which is only shown in fig. 3. The transport means 16 is adapted to receive several of the mould elements 3 with the vacuum-fixed building material 7. As fig. 3 shows, al ready one mould carrier 2 from a not-shown mould 1 is already received in the rack 17. The rack 17 comprises respective re ceiving means 19, here in form of longitudinal bars or carri ers, which are e.g. provided with rollers or the like in or der to easily move the mould element on them. The receiving means 19 are, as shown by the arrow PI, vertically movable, so that respective receiving means may be moved in place to receive a new mould element 3, whereafter the receiving means 19 with the mould element 3 is vertically moved and another receiving means 19 is moved in place in order to receive an other mould element 3. The mould elements 3 are, as shown by the arrow P2, simply pushed into the rack 17 by respective pushing means, which may be arranged at the carrier 2, while these pushing action may also be performed manually, as the mould element 3 rolls on the roller elements 15. It may also be pulled into the rack 17 by using respective pulling means arranged at the rack 17. These pushing or pulling means may for example be pushing or pulling rods or the like.

The vertical movement of the receiving means 19 may be per formed by respective electric motors or for example driving circulating chains or belts, to which the receiving means 19 are coupled, or respective spindle drives or the like. Also, the respective pushing or pulling means may be motor driven.

Fig. 3 shows a first embodiment of an inventive manufacturing arrangement 20 for producing preforms for turbine blades. It shows in this example three moulds 1, which are arranged side by side. The mould la is equipped with a new mould element 3a, which is, see the arrow P3, pushed or anyhow else placed on the mould carrier 2a. The second mould lb is equipped with the mould element 3b arranged on the mould carrier 2b. The building material 7b is already arranged on the mould element 3b, but for example not yet vacuum-fixed.

Finally, the mould element 3c of the third mould lc is ready for the further processing and is therefore, as shown by the arrow P4, moved into the transport means 16 respectively the rack 17. The mould element 3c comprises the building material 7 covered by the vacuum cover 8c, it is therefore vacuum- fixed. As shown, it is already partially moved into the rack 17, in which already two other mould elements 3d, 3e are ar ranged.

The rack 17 moves on the respective rails 18 in the direction of the arrow P5 and therefore along the respective moulds 1. At each mould 1 the respective mould element 3 comprising the fixed building material is received on respective receiving means 19 of the rack 17, until the rack 17 is fully loaded. The rack 17 then moves to a heating means 21, i.e. a heating oven, which can be pre-heated respectively remains always at a certain temperature level necessary for melting the usually only locally applied binding agent in order to embed all the fiber material and core material etc. in a respective fluid binding matrix. Several mould elements are moved into the heating means 21, as shown by the arrow P6. In this illustra tion already several mould elements 3f, 3g are already in this heating means 21, which is shown partially opened just for illustration purpose. They are heated for a certain time necessary to build the preform. Regarding the way the mould elements are inserted in the heating means several possibili ties are feasible, which are explained later.

Further shown is a cooling means 22, like a housing or unit comprising a cooling fan or the like, which is adapted to ac tively cool the heated preforms, which are, as shown by the arrow P7, transferred from the heating means 21 to the cool ing means 22. This transfer will also be described later. The mould element capacity of the cooling means 22 preferably corresponds to the mould element capacity of the heating means 21, so that all heated mould elements 3 can be trans ferred to the cooling means 22 and be cooled simultaneously.

In this cooling means 22 the hot preforms are cooled down to an ambient temperature, whereafter they are removed from the cooling means 22, as shown by the arrow P8 to be further pro cessed.

As this principle layout clearly shows, the moulds 1 are only used for preparing the building material 7 and for shaping the form of the building material 7 according to the request ed preform shape and for fixing the building material 7 to the respective mould element 3. Right after the respective mould element 3 is removed from the mould carrier, a new mould element 3 may be put in place on the mould carrier, which new mould element 3 is completely surface cleaned to ensure that the building material 7 may be properly arranged. The heating process is completely separated from the mould area. As only the heating is performed in the heating means, this heating means can be held on a constant temperature, which allows a very short heating operation.

The same holds for the cooling means 22, which allows for a separated cooling step, and which cooling means 22 can also be maintained on a certain cooling temperature or allows to actively run a certain cooling ramp in order to enhance the cooling.

Thus, an almost constant manufacturing may be realised, as it is constantly possible to provide respective loaded mould el ements 3 ready for the heating and cooling processing. The time, for which a mould 1 is occupied, is very short and cor responds almost only to the time needed for arranging a new mould element 3 in place, loading the building material 7 and fixing it, and for removing the loaded mould element 3. As both the heating means 21 and the cooling means 22 are adapted to receive several mould elements, also the heating and cooling process is significantly faster, as a certain number of mould elements may simultaneously be processed.

Fig. 4 shows a first alternative regarding the transfer of the mould elements 3 into the heating means 21 and the cool ing means 22. In this embodiment the mould elements 3 are ar ranged in the transport means 16, i.e. the rack 17, and are received on respective receiving means 19, which are, as shown by the double arrow P9, vertically movable, as previ ously mentioned.

In this embodiment, the complete transport means 16 with all the mould elements 3 moves into the heating means 21 and stays there during the heating process. When the heating pro cess is finished, the transport means 16 moves out of the heating means 21 and directly into the cooling means 22 to be finally cooled. After the cooling step is finished, the whole transport means 16 with the cool mould elements 3 comprising the cooled preforms is moved out of the cooling means 22, whereafter the mould elements 3 may be removed from the transport means 16 and the finished preforms may be removed from the mould elements 3 for further processing. In an al ternative the transport means 16 may be moved to a storage area for storing the finished preforms.

The mould elements 3 will be, after the preforms are removed, automatically surface cleaned and will be automatically re circulated again for being arranged on an unloaded mould car rier 2 again.

In the embodiment of fig. 5, again a transport means 16 re spectively a rack 17 is shown, which comprises several mould elements 3 arranged on a respective vertically movable re ceiving means 19, as shown again by the arrow P9.

The heating means 21 is equipped with separate receiving means 23 which are vertically movable, as shown by the double arrow PI0. The separate mould elements 3 of the transport means 16 are, as shown by the arrow PI1, horizontally moved from the transport means 16 to the heating means 21 respec tively from a receiving means 19 to a receiving means 23. For example, only the lowest mould element 3 is moved to the low est position in the heating means 21. In the next step, the next mould element 3 of the transport means 16 is lowered, while the previous mould element received in the heating means 21 is raised, so that a new transfer may start until all mould elements are unloaded. As soon as the transport means 16 is unloaded, it returns to again receive new mould elements 3.

After the heating process is finished, the separate mould el ements 3 are transferred to the cooling means 22. The set-up of the cooling means 22 is comparable to the set-up of the heating means 21. Also, the cooling means 22 comprises re ceiving means 24, which are, see the double arrow P12, verti- cally movable. Again, by using respective transfer means, as shown by the arrow P13, separate and single mould elements 3 are moved from the heating means 11 respectively a receiving means 23 to the cooling means 22 respectively a receiving means 24. Also, here the respective vertical movement is per formed.

After the cooling is finished, the mould elements 3 with the cooled preforms are transferred to another transport means 25, again a rack, with a respective receiving means 26 for receiving the respective mould elements 3, as shown by the arrow P14. The receiving means 26 are, as shown by the arrow P15, also vertically movable. With this transport means 25 the mould elements 3 with the finished preforms may be trans ported to a storage area or to a further processing device etc.

It is to be noted that the transport means 25 is only option al. It is certainly possible to transfer the separate cooled mould elements 3 for example to a respective conveyor belt or the like and to transport them into a storage area or to a lifting device for vacuum-lifting the finished preforms from the mould element for further processing the preforms. The emptied mould element 3 will then be surface cleaned if so needed and recirculated.

Fig. 6 shows an embodiment with a first transport means 16, which set-up is identically to the transport means 16 of fig. 5. Also, the heating means 21 and the cooling means 22 corre spond in their set-up and function to the heating and cooling means 21, 22 of fig. 6. In this embodiment, the heating means 21 and the cooling means 22 are distanced, thus a direct transfer of the mould elements is not possible. For the transfer a further transport means 27 is provided, comprising respective receiving means 28, e.g. beams or rails, on which the separate mould elements 3 are received from the heating unit 21, as shown by the arrow PI6. Again, the receiving means 28 can be vertically moved, as shown by the arrow P17. After the transport means 27, again a rack, is completely loaded, it moves to the cooling means 22, where the separate mould elements 3 are unloaded as shown by the double arrow PI8 onto respective receiving means 24 of the cooling unit 22. After the cooling step is finished, the mould elements 3 may again be transferred to the transport means 25 or may be directly transferred to a conveyor belt etc.

In both embodiments according to figs. 5 and 6 the mould ele ments 3 are transferred separately into and out of the heat ing unit. The order, in which they are transferred into and out of the heating unit 21 may be the same. This means that each mould element 3 receives the same temperature treatment respectively remains for the same process time in the heating means 21. In case a mould element 3 respectively the building elements needs a shorter or longer heat treatment, the re spective mould element may remain shorter or longer in the heating unit 21 than other mould elements 3, so that the transfer order may vary depending on the needed treatment time. This is possible due to the separate mould element transfer .

Finally, fig. 7 shows another layout of a manufacturing ar rangement 20. It again comprises in this example four moulds 1, with each mould having a removable mould element 3. For arranging the building material 7 on the respective mould el ement 3, the building material 7 is arranged close to the re spective mould 1 and is for example unwound from respective fiber mat rolls etc., while the binding agent is applied from respective hoppers or the like.

In this embodiment, a transport means 18 in form of a fork lift is provided between the two rows of moulds 1. This transport means 16 respectively fork lift is adapted to take a loaded mould element 3 and to transport it to the heating means 21, as shown by the arrow PI9. From the heating means 21 the mould element 3 is then transferred to the cooling means 22, from where it is then further processed as de scribed .

The empty mould element 3 is then returned by another transport means 25 like a fork lift after cleaning the sur face of the mould element 3 for replacing it on a mould car rier 2.

This figure also shows the various rails 18, on which the transport means 25 moves, wherein this rails 18 may also be used by respective transport cars 29 used for distributing the building material.

Although the present invention has been described in detail with reference to the preferred embodiment, the present in vention is not limited by the disclosed examples from which the skilled person is able to derive other variations without departing from the scope of the invention.