METHOD OF MANUFACTURING A WIND TURBINE ROTOR BLADE PART HAVING AN EMBEDDED PLACEHOLDER

Abstract

A method of manufacturing a wind turbine rotor blade part, the method including: providing a placeholder including a core member and a sleeve, wherein the core member defines a longitudinal direction and has a circumferential surface, a front end and a back end, and the sleeve includes a peel ply layer, wherein the sleeve covers the circumferential surface and the back end of the core member and is affixed to the back end of the core member; arranging the placeholder together with reinforcing fibers and a matrix material in a mold; curing of the matrix material, so that the placeholder is embedded in a fiber-reinforced composite material.

Claims

1. A method of manufacturing a wind turbine rotor blade part, the method comprising: providing a placeholder including a core member and a sleeve, wherein the core member defines a longitudinal direction and includes a circumferential surface, a front end, and a back end, and the sleeve includes a peel ply layer, wherein the sleeve covers the circumferential surface and the back end of the core member and is affixed to the back end of the core member; arranging the placeholder together with reinforcing fibers and a matrix material in a mold; and, curing of the matrix material, so that the placeholder is embedded in a fiber-reinforced composite material.

2. The method of claim 1, wherein said providing the placeholder includes applying a release agent to at least the circumferential surface of the core member.

3. The method of claim 1, wherein said providing the placeholder includes wrapping the peel ply layer about the circumferential surface of the core member.

4. The method of claim 3, wherein said providing the placeholder further includes folding a section of the peel ply layer that extends along the longitudinal direction beyond the back end of the core member against the back end.

5. The method of claim 1, wherein said providing the placeholder includes: providing the sleeve by forming the peel ply layer such that said peel ply layer has a sock-like shape; and, inserting the core member into the sleeve.

6. The method of claim 1, wherein the sleeve is affixed to the back end of the core member via a clamping element exerting a clamping force on the peel ply layer of the sleeve.

7. The method of claim 6, wherein the clamping element is a head of a screw or a washer placed beneath the head of a screw, wherein the screw is screwed into a threaded bore provided at the back end of the core member.

8. The method of claim 6, wherein the clamping element has a circumferential lip contacting the peel ply layer.

9. The method of claim 1 further comprising connecting a pulling tool to a fastening element of the core member.

10. The method of claim 1 further comprising pulling the core member out of the fiber-reinforced composite material along the longitudinal direction towards the front end, such that the sleeve is peeled off the fiber-reinforced composite material and a cavity is formed in the fiber-reinforced composite material.

11. The method of claim 10 further comprising inserting and fastening a joining element in the cavity.

12. The method of claim 11, wherein the joining element is a bushing with a threaded bore.

13. A placeholder for being embedded in a fiber-reinforced composite material of a wind turbine rotor blade part, the placeholder comprising: a core member defining a longitudinal direction and including a circumferential surface, a front end, and a back end; and, a sleeve including a peel ply layer, wherein said sleeve covers said circumferential surface and said back end of said core member and is affixed to said back end of said core member.

14. A wind turbine rotor blade part comprising: a fiber-reinforced composite material; a placeholder having a core member and a sleeve; said core member defining a longitudinal direction and including a circumferential surface, a front end, and a back end; said sleeve including a peel ply layer, wherein said sleeve covers said circumferential surface and said back end of said core member and is affixed to said back end of said core member; and, said placeholder being embedded in said fiber-reinforced composite material.

15. The wind turbine rotor blade part of claim 14, wherein said placeholder is embedded in said fiber-reinforced composite material such that when pulling said core member out of said fiber-reinforced composite material along the longitudinal direction towards said front end, said sleeve is peeled off said fiber-reinforced composite material and a cavity is formed in said fiber-reinforced composite material.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0039] The invention will now be described with reference to the drawings wherein:

[0040] FIG. 1 shows a wind turbine rotor blade part with an embedded placeholder in a schematic, longitudinal section;

[0041] FIG. 2 shows the arrangement of FIG. 1 while pulling out the placeholder;

[0042] FIG. 3 shows a placeholder in two schematic views;

[0043] FIG. 4 shows another placeholder in two schematic views;

[0044] FIG. 5 shows a core member of still another placeholder in a longitudinal section;

[0045] FIG. 6 shows a wind turbine rotor blade in a schematic, perspective view;

[0046] FIG. 7 shows a wind turbine rotor blade with two longitudinal segments each having a wind turbine rotor blade connection part; and,

[0047] FIG. 8 shows a wind turbine rotor blade part arranged at a wind turbine rotor blade root.

DETAILED DESCRIPTION

[0048] FIG. 1 shows in cross section a placeholder including a core member 10 and a sleeve 12. The core member 10 has a longitudinal direction 14, a circumferential surface 16, a front end 18 and a back end 20. The sleeve 12 consists of a peel ply layer 22 having a sock-like shape. The sleeve covers the entire circumferential surface 16 as well as the back end 20 of the core member 10.

[0049] The core member 10 further includes a fastening element, namely an opening 24 having an inner thread 26. The opening 24 is arranged at the front end 18 of the core member 10. At its back end 20, the core member has a threaded bore 52 into which a screw 28 is inserted. The screw 28 has a screw head 30 and serves as a clamping element which is exerting a clamping force on the peel ply layer 22 of the sleeve 12. A section of the peel ply layer 22 covering the back end 18 is arranged between a bottom side of the screw head 30 and the back end 20 of the core member 10.

[0050] The placeholder is embedded in a fiber-reinforced composite material 34 of a wind turbine rotor blade part 36. The wind turbine rotor blade part 36 has a joining surface 38 which is flush with the front end 18 of the core member 10. The sleeve 12 extends beyond the front end 18 of the core member 10, so that there is no direct contact between the core member 10 and the surrounding fiber-reinforced composite material 34. The fiber-reinforced composite material 34 is arranged below, above and to the right of the placeholder. Only the front end 18 of the core member is accessible from the outside. Next to the back end 20 of the core member 10 and embedded the in fiber-reinforced composite material 34, the wind turbine rotor blade part 36 includes a wedge-shaped foam core 40.

[0051] In order to manufacture the wind turbine rotor blade part 36 of FIG. 1, the placeholder is provided and arranged in a mold (not shown) together with reinforcing fibers and a matrix material. The matrix material is then allowed to cure, so that the placeholder is embedded in the fiber-reinforced composite material 34.

[0052] FIG. 2 shows the arrangement of FIG. 1 while pulling out the core member 10 of the surrounding fiber-reinforced composite material 34 in the direction of the arrow 42, towards the front end 18. This may be done by fastening a pulling tool to the opening 24. One can see that the peel ply layer 22 remains affixed to the back end 20. The core member 10 slides out of the sleeve 12, and the sleeve 12 is peeled off the wall 44 of the cavity 46 formed in the fiber-reinforced composite material 34.

[0053] FIG. 3 shows another placeholder, seen to the left of the figure in a longitudinal section and to the right of the figure in a view on the back end 20. The placeholder is similar to the one shown in FIGS. 1 and 2. The sleeve 12 has been formed by wrapping the peel ply layer 22 around the circumferential surface 16 of the core member 10. Sections 48 of the peel ply layer 22 extending beyond the back end 18 of the core member 10 have been folded against the back end 18. They are affixed to the back end via the screw head 30 of the screw 28.

[0054] FIG. 4 shows still another placeholder, seen to the left of the figure in a longitudinal section and to the right of the figure in a view on the back end 20. The placeholder is similar to the one shown in FIGS. 1 and 2. It differs from the placeholder of FIG. 3 only in how the sleeve 12 has been formed. Here, the peel ply layer 22 was provided with a sock-like shape in advance, and the core member 10 was then inserted into the sleeve 12.

[0055] FIG. 5 shows a core member 10 of still another placeholder, in a longitudinal section only. The core member 10 has a longitudinal direction 14, a circumferential surface 16, a front end 18 and a back end 20. The core member 10 further includes an opening 24 having an inner thread 26 and serving as a fastening element for attaching the core member to a mold flange and/or for assembling a pulling tool (not shown). The opening 24 is arranged at the front end 18 of the core member 10. At its back end 20, the core member 10 has a threaded bore 52 into which a screw 28 is inserted. The screw 28 has a screw head 30. A large-diameter washer 50 is placed beneath the screw head 30 and can be pressed against the back end 18 for clamping a section of a sleeve 12 (not shown) to the back end 18.

[0056] At a bottom side of the washer 50, a circumferential groove 54 is formed which can accept an O-ring 55 serving as a lip for clamping the sleeve 12 and for forming a seal between the back end 18 and the washer 50.

[0057] FIG. 6 shows a wind turbine rotor blade 56 having a longitudinal axis 58, an aerodynamic profile 60, a blade tip 62 and a blade root 64. The wind turbine rotor blade 56 is divided in two segments, namely an inner segment 66 including the blade root 64 and an outer segment 68 including the blade tip 62. The two segments 66 and 68 are joined to each other at a segmentation plane 70.

[0058] FIG. 7 shows the wind turbine rotor blade of FIG. 6 in another schematic view. The two segments 66, 68 are drawn in a distance from each other. Each one has a joining surface 72. Each of the segments 66, 68 includes a wind turbine rotor blade connection part 74 facing the segmentation plane 70 and forming the respective joining surface 72. In each of the wind turbine rotor blade connection parts 74, three placeholders 76 are embedded.

[0059] FIG. 8 illustrates a way to employ the method at a wind turbine rotor blade root 64. The view is directed on a joining surface 72 of the wind turbine blade root 64, which is adapted to be connected to a wind turbine rotor hub. The wind turbine blade root 64 is shown in a mold 84 and includes a fiber-reinforce composite material 34 having a plurality of inner layers 80 and a plurality of outer layers 82 of a fiber material. On top of the outer layers 82, foam cores 78 are placed, and between each pair of foam cores, a placeholder including a core member 10 and a sleeve 12 is arranged. Each core member 10 includes an opening 24 for fastening a pulling tool.

[0060] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

LIST OF REFERENCE NUMERALS

[0061] 10 core member [0062] 12 sleeve [0063] 14 longitudinal direction [0064] 16 circumferential surface [0065] 18 front end [0066] 20 back end [0067] 22 peel ply layer [0068] 24 opening [0069] 26 inner thread [0070] 28 screw [0071] 30 screw head [0072] 34 fiber-reinforce composite material [0073] 36 wind turbine rotor blade part [0074] 38 joining surface [0075] 40 foam core [0076] 42 arrow (pulling direction) [0077] 44 wall [0078] 46 cavity [0079] 48 section of the peel ply layer [0080] 50 washer [0081] 52 threaded bore [0082] 54 circumferential groove [0083] 55 O-ring [0084] 56 wind turbine rotor blade [0085] 58 longitudinal axis [0086] 60 aerodynamic profile [0087] 62 blade tip [0088] 64 blade root [0089] 66 inner segment [0090] 68 outer segment [0091] 70 segmentation plane [0092] 72 joining surface [0093] 74 wind turbine rotor blade connection part [0094] 76 placeholder [0095] 78 foam cores [0096] 80 inner layer [0097] 82 outer layer [0098] 84 mold