DK175863B1 - Method is for production of windmill vanes of fiber-reinforced plastic, vane comprising two half shells, each with application of impregnated fiber matter in each half part - Google Patents

Abstract

The method is for the production of windmill vanes of fiber-reinforced plastic. The vane in each case comprises two half shells, each with application of impregnated fiber matrix in each half part. The method is for the production of windmill vanes of fiber-reinforced plastic. The vane in each case comprises two half shells, each with application of impregnated fiber matrix in each half part. After hardening of the half shells, they are adhered together along their edges. If the half shells are glued together, each is provided with a number of straps, which from an inner end extend past the half shell edge and outwards on the exterior of the form half part.

Description

(19) DENMARK ου DK 175863 B1 <§fe

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Patent and

Trademark Office 4, (51) Int.CI7: B 29 C 33/30 B 29 C 65/78 B 29 D 22/00 F03D 1/06 F 03 D 11/04 (21) Patent Application No: PA 2003 00327 (22 ) Submission day: 2003-03-03 (24) Running day: 2003-03-03 (41) Aim. available: 2004-09-04 (45) Patent Notice bkg. on: 2005-04-18 (73) Patent holder: LM Glasfiber A / S, Rolles Møllevej 1,6640 Lunderskov, Denmark (72) Inventor: Karsten Schibsbye, Holbergsvej 30, 7000 Fredericia, Denmark

Jan Leslie Wagner Christensen, Gelballevej 21, 6640 Lunderskov, Denmark (74) Attorney: Chas. Hude A / S, H.C. Andersens Boulevard 33.1780 Copenhagen V, Denmark (54) Name: Process for manufacturing shell structures, e.g. wind turbine blades made of fiber-reinforced plastic (56) Published publications: DK A 200001281 DK B1 171948 (57) Abstract:

In a method for producing wind turbine blades made of fiber-reinforced plastic and wherein the blade comprises two half shells (4), each half shell is cast by laying and plastic impregnating fiber mats in each mold half (2). After curing the half shells (4), they are bonded along their edges while in their mold half (2). Before the shell halves (2) are bonded together, they are each provided with a plurality of straps (8) extending from an inner end, with the respective half-shell end, past the edge of the half-shell and out on the outside of the mold half (2). By means of clamping means (10) arranged on the outside of the mold half (2), the straps are applied to a "pull" so that the half shell along its edge abuts the inside of the mold half (2).

The tension in the straps (8) is maintained until the glue between the compressed half shells (4) is hardened.

continued DK 175863 B1 * DK 175863 B1

The present invention relates to a method for making shell structures, e.g. wind turbine blades, of fiber-reinforced plastic, e.g. fiberglass-reinforced polyester, and wherein the shell structure comprises two half shells, e.g. wing half shells molded by laying and plastic impregnation of fiber mats in each female mold half, and then, after curing of the plastic, are glued along their edges while being in their mold halves, with one or both half-shell edges applying glue to the edges of the half-shells. then pressed against each other.

In particular, but not exclusively, the method is directed to gluing fiber-reinforced plastic half shells to wind turbine blades, and the outer contour of the wind turbine blade is preferably formed by two blade half shells which, prior to bonding, must be retained in each mold half. As a plastics material, in particular, a curing resin may be used, e.g. polyester, and as fiber reinforcement especially fiberglass, optionally in combination with carbon fibers. However, other plastics and / or fiber materials may also be used. The casting process used may be traditional fiberglass hand laying, with the mats being successively impregnated with plastic. However, a vacuum infusion method is preferably used. In this method, all the intended fiber mats are first placed dry in the mold. Then a so-called vacuum film, which is airtight and which is sealed relative to the edge of the mold, is placed above the fiber laying, e.g. using a sealant, a so-called tacky tape. Next, vacuum is provided between the inside of the mold part and the vacuum foil. Finally, liquid plastic is introduced into the area between the inside of the mold and the vacuum foil so that the fiber coating is completely soaked with plastic.

It is generally known to fix a wing half shell in a mold part prior to bonding the two half shells. The bonding is usually done by pressing two related mold halves with each wing half shell against each other. In order to allow the upper mold part to be placed over the lower part, the wing half shell with clamping tongs is fixed to the upper mold part. This fixation occurs in the edge region where the wing half shell is provided with a "temporary" protruding flange, the purpose of which is to assist in the fixation of the wing shell to and in the mold half. This flange is cut off after gluing the wing. However, this temporary flange has several drawbacks. Thus, there is a large manual task associated with removing this flange after gluing the blade, and the removed material is waste material. Furthermore, the thickness of the flange causes, in particular, the rear edge of the wing to have an increased thickness which exceeds the optimum, so that the aerodynamic conditions deteriorate.

5

For wing shells molded from, for example, polyester and fiberglass, a relatively large shrinkage occurs, which means that the cast wing shell is in fact smaller than the mold, and therefore it must be pressed against the inside of the mold and fixed in this position to ensure that the two wing half shells edges are glued directly to each other. If this is not ensured, it is said that the wing has over- or underbite. Unless this bonding is optimal, optimum aerodynamic conditions cannot be achieved, and the production time is considerably extended, as a great deal of effort is required to form the optimal shape of the blade.

15 In order to ensure as good and perfect bonding as possible, the aforementioned core pliers are removed, which are removed after the upper wing half shell and mold half are placed over the lower wing half shell and mold half. This creates a risk of the two wing half shells being displaced relative to each other during gluing.

It is the object of the invention to provide a solution whereby the above problems are solved.

That is, to specify a solution that ensures that a blade shell, regardless of shrinkage, is always fixed to the inside of the mold so that a more precise bonding of the wine-half shells is achieved and to specify a solution by which the size of a temporary protruding flange can be reduced. substantially or avoided so that the subsequent manual work is substantially reduced.

In order to achieve this object, the method according to the invention is characterized in that, before the bonding, the half-shells are each provided with a plurality of straps which extend from an interior with the respective half-shell end extending beyond the edge of the half-shell and to the outside of the mold half, and that by means of clamping means arranged on the outside of the mold half the straps are applied a feature such that a half of the half shell along its edge abuts the inside of the mold half, which feature in the straps is maintained until the glue between the edges of the compressed half shells is hardened.

5 By ensuring that the half shells in their edge region abut the inside of the mold portions, it is possible to place and thus precisely bond the two half shells. Since the exact positioning of the half-shells relative to the fonri halves is maintained until the glue is cured, there is prevented during the bonding between the edges of the half-shells. When the half shells are glued together and the shell structure 10 is removed from the mold, the hanging straps are cut off. This requires considerably less work than the prior art, where a relatively large temporary flange must be cut. This results in a substantial reduction in the finishing work to achieve the intended shape of the shell structure. Furthermore, theoretically, the temporary flange is no longer needed as the fixing straps assume its 1S function. In practice, however, it cannot be ruled out that a small flange is formed on the half shells.

According to the invention, the straps are arranged at predetermined intervals along the edges of the half shells and so that the straps of the two half shells do not coincide when the 20 half shells are glued together.

Since the fixing straps used have such a small thickness, approx. 0.5 to 1 mm, relative to the known temporary flange, which is approx. 2 mm per half shell, and a small width, e.g. ca. 40-50 mm, a significantly more precise bonding is achieved with a minimum thickness of 25 seams. As previously mentioned, this thickness is important for the aerodynamic conditions of the finished blade, but is also of great importance for material consumption during bonding.

A preferred clamping device is the type of clamping device known from a load securing strap which is normally used for securing goods on trucks and the like. This type of clamping device is also referred to as lashing or belt tensioner. Such a 4 DK 175863 B1 clamping device has a shaft with a slot, as well as a handle which can be actuated for turning the shaft. When a strap is to be tightened, its free end is inserted into the slot in the shaft and the handle is then activated. Hereby the strap miles up the shaft, ie. the strap is tightened. Furthermore, it should be noted that the handle is connected to the shaft via a clamping mechanism, so that only one rotation of the shaft occurs when the handle is moved in one direction. Further, the clamping device is provided with a release mechanism which, upon activation, releases the latching mechanism so that the shaft can rotate freely, thereby releasing the strap. Alternatively, other types of clamping devices which operate more automatically may be used. For example, the clamping means may be electrical, hydraulic or pneumatic linear or rotary actuators to which the straps may be fixed and tightened. These devices may furthermore be provided with a gripping tool in which several strap ends can be secured for joint tightening. In this way, the number of clamping devices can be limited.

The straps may be attached to the half shells in any suitable manner. In principle, the straps can thus be attached to the inside of the half shells after casting them, either by mechanical means or by adhesive. However, it is preferred to attach the straps to the shells using the plastic used to impregnate the fiber laying. Hereby the straps may be disposed on the inside of the laying or preferably be placed between layers of the fiber laying so that the straps are laminated in the half shell during casting thereof.

Therefore, it is also preferred for the straps to use a material with which the plastic used makes a good bond, either because of the structure of the material or its chemical composition or a combination thereof.

Consequently, a suitable fiber-based material and, in particular, a fiber-based material corresponding to one of the fibers used in the fiber lay-up can be used. When using a traditional hand laying, this does not cause any problems. However, by molding the shells by the vacuum infusion method, an airtight space is required between the vacuum foil and the inside of the mold to create and maintain the necessary vacuum during the molding process. In order to prevent air-permeable fiber straps from forming a bond between said airtight compartment and the environment during the molding process, while plastic enters the free end regions of the straps, these end regions must be protected from plastics during the molding process. This can be achieved, for example, by separately wrapping all the free ends of the straps, for example in a plastic bag from which they can be released after casting.

However, according to a preferred embodiment of the invention, straps made of fibrous material are provided between the inner and outer ends with an airtight region 10, which is preferably provided by molding a plastic material, e.g. polyester or polyurethane. This molded airtight area extends throughout the width of the strap and over a limited range of the length of the strap. The airtight region of the strap is arranged to be disposed on the edge of a mold half, whereby, using a sealant such as tacky tape, it is possible to obtain an optimal seal between the edge of the mold half and the vacuum foil. The use of polyurethane for the airtight area is advantageous in that the polyurethane is flexible and partially adhesive.

In addition, according to the invention, the straps as a whole may be made of a flexible air-tight material, such as a plastic material, flake. polyurethane or polyamide.

20

Still, according to the invention, the straps can be applied before the edge shell of the respective half shell has withdrawn from the inside of the mold part due to the shrinkage during the curing of the plastic.

Finally, according to the invention, the half shell in question can be allowed to harden so that its edge region extends away from the inside of the mold part, after which the straps are applied to pull the abutment edge of the half shell against the inside of the mold before bonding the two half shells.

In the following, the invention is explained in more detail with reference to the drawing, in which: FIG. 1 schematically shows a typical mold half for a wind turbine blade with a half shell molded therein, which is provided with fixing straps extending on the outside of the mold half; FIG. 2 shows a section of the embodiment of FIG. 1 shows half of the mold with fixing straps and clamping devices arranged on the outside of the mold; FIG. Figure 3 is a sectional view of two mold halves placed one above the other while bonding the molded mold halves; 4 is a section of a fixing strap with a molded airtight area.

Referring to FIG. 1 and 2, a typical mold half 2 is shown for a wind turbine half shell 4. The mold half 2 is shown with an already molded wing half shell 4, where fixing straps 8 are laminated along the sides 3 of the wing half shell 4. The straps 8 extend past the edges of the half shell and out onto the edges 6 of the mold half 2 and thence down to the respective side 5 of the mold half. The straps are located at a distance which is dependent on the tendency of the particular half-shell 4 to shrink during curing. The straps 8 may be made of a woven fabric, e.g. a fabric based on the same fibers used in one of the fiber mats used in the fiber reinforcement of the half shells. However, the straps may be made of any fabric material having the strength necessary to withstand the tension to which the straps are subjected when tensioned.

In a particularly preferred embodiment of the straps used in casting the half shells by the vacuum infusion method, the straps are provided with a defined area 22 embedded on the strap, see FIG. 4. The region 22 may be molded of any plastic material which, during casting, penetrates the fabric material of the strap 8 and causes the region 22 of the strap to be airtight. Preferably, the region 22 30 is molded of the same plastic material as the half shells 4 or of polyurethane.

a 7 GB 175863 B1 Tensioning devices 10 are provided on the two sides 5 of the mold half. Tensioning means are arranged to apply a strap 8 to the straps 8, so that the half shell in its edge region is held in contact with the inside of the mold half 2. The clamping devices shown, which are not attached to the sides of the mold half in a detailed manner, comprise a base part 15 and a rotatably mounted shaft 14 with a radially through slot 13. The shaft 14 is connected via a non-shown ratchet mechanism. control lever 11. When activating the control lever 11 in one direction, turn the shaft. When turning the control handle in the opposite direction, the shaft is held by the latching mechanism so that there is no turning thereof. The latch mechanism further has a release mechanism (not shown) which, upon actuation, allows free rotation of the shaft 14.

When the straps are to be tensioned, the free end 12 of the strap 8 is passed through the slot 13 in the shaft 14. In the clamping device 10, the operating handle 11 is then operated, whereby the free end portion of the strap is rolled up around the shaft 14 and the strap 8 is thereby tensioned. The straps 8 15 are tightened to such an extent that the edge area of the half shell 4 is securely held against the inside of the mold half in the area at the mold edges 6. If, due to shrinkage, the half shell 4 has withdrawn from the inside of the mold half 2, the straps 8 are tensioned. 4 is brought into contact with the inside of the mold half in the area at the edges of the mold half 6. This ensures that the molded half shell 4, especially its edge, is in the predicted location prior to the bonding of the two half shells 4.

The process of the invention will be elucidated below with reference to the preparation of a wind turbine blade comprising two half shells made of glass-fiber reinforced polyester by the vacuum infusion method.

Each half shell is made by laying fiberglass mats on the inner half of the mold. In connection with this, straps 8 of the embodiment of FIG. 4. The straps are positioned so that their inner ends are located between two layers of mats in the lay-up and the straps extend over the edge of the mold half 6. Further, the straps are positioned so that the area 22 is on said edge 6. Above above 8 DK 175863 In the B1 laying, a vacuum film is applied which is sealed with respect to the edge 6 of the mold half 4 and the area 22 of the straps by means of tacky tape. Next, vacuum is created between the vacuum cloth and the inner half of the mold, and then liquid polyester is introduced into the region between the vacuum film and the inner half of the mold to completely soak the fiber laying. Thereafter, the polyester is allowed to cure and the straps 8 are tensioned by means of the clamping means 10 immediately before the plastic is fully cured and the molded half shell 4 still abuts the mold in the edge area of the half shell. When the two half shells are finished, the vacuum foil is removed and the half shells are placed one above the other, as shown in FIG. 3. Before joining the mold halves 16, 18 with the half shells 4 herein, glue is applied to the edge half of the lower half shell. Then the mold halves 16,18 are joined together and clamped together.

As shown in FIG. 3, the fixing straps 8 in the two half shells are arranged so that they do not lie on top of each other when comparing the two half shells 4. The distance between the straps in the two mold halves 16 and 18 depends, among other things, on the geometry of the cast wing and is adapted as required. . The clamping devices used to clamp the straps are not shown in FIG. 3, but illustrated by arrows 20 pointing in the tensioning direction. When the glue is cured, the blade is removed from the mold and the protruding 20 straps cut away. Finally, a finishing work is done on the joint area between the two half shells.

Claims (9)

1. A process for manufacturing shell structures, e.g. wind turbine blades, 5 fiber-reinforced plastics, e.g. fiberglass-reinforced polyester, the shell structure comprising two half shells (4) molded by laying and impregnating fiber mats in each mold half, and then, after curing, bonded along their edges while in their mold halves (2) one or both half-shells (4) are applied to glue before the edges of the half-shells (4) are then pressed against each other, characterized in that, before the bonding, the half-shells (4) are each provided with a number of straps (8) which the end connected to said half shell extends beyond the edge of the half shell and outwards on the outside of the mold half (2; 16, 18), and that by means of clamping means (10) arranged on the outside of the mold half (2; 16, 18) 5) the straps (8) are applied so that the shell halves along their edge abut the inside of the mold half, which feature in the straps (8) is maintained until the glue between the compressed half shells (4) nter is hardened. Method according to claim 1, characterized in that the straps (8) are arranged at predetermined intervals along the edges of the half shells, so that the straps of the two half shells 20 do not coincide when the half shells are glued together. Method according to claim 1 or 2, characterized in that the straps (8) are fastened, especially by gluing, to the inside of the half-shells after casting them. Method according to claim 1 or 2, characterized in that the straps (8) are placed adjacent to the fiber laying, especially between layers thereof, and are laminated in the half shells during casting thereof. Method according to one or more of the preceding claims, characterized in that the straps (8) are made of a fiber-based material, in particular a woven material and preferably a fiber web of the same type as a mat included in the fiber laying. 10 DK 175863 B1 Method according to claim 5, characterized in that the strap (8) between its inner and outer ends (12) is provided with an airtight region (22) which is preferably provided by molding a plastic material, e.g. polyester or polyurethane. 5 Method according to one or more of claims 1 to 4, characterized in that the straps are made entirely of a flexible airtight material, in particular a plastic material, e.g. polyurethane or polyamide. Method according to one or more of the preceding claims, characterized in that the straps are applied before the edge of the half shell in question has withdrawn from the inner half of the mold half due to the shrinkage during the curing of the half shell. Method according to one or more of claims 1 to 7, characterized in that the half shell in question is allowed to cure, so that its edge area extends away from the inside of the mold half concerned, after which the straps are applied to pull the edge shell areas into contact with the mold. inside, before gluing the two half shells. 20