METHOD OF MANUFACTURING A SPAR CAP FOR A WIND TURBINE BLADE

Abstract

The present invention relates to a method of manufacturing a fibre-reinforced spar cap (41) for a wind turbine. The method comprises the steps of providing a mould (62), and fastening a first guide member (64) and a second guide member (66) to the mould for providing a moulding cavity (68) in between the first and second guide members. A fibre material can be arranged within the moulding cavity, such that a first gap (72) is provided between the fibre material and the first guide member, and a second gap (74) is provided between the fibre material and second guide member. First and second inserts (78, 80) are inserted into the gap prior to resin infusion.

Claims

1. A method of manufacturing a fibre-reinforced spar cap (41) for a wind turbine blade, the method comprising the steps of: providing a mould (62), fastening a first guide member (64) and a second guide member (66) to the mould for providing a moulding cavity (68) in between the first and second guide members, arranging a fibre material (70) within the moulding cavity, such that a first gap (72) is provided between the fibre material and the first guide member, and a second gap (74) is provided between the fibre material and second guide member, placing a vacuum foil (76) over the fibre material and the first and second guide members, such that the vacuum foil (76) extends into the first and second gap (72, 74), inserting a first insert (78) into the first gap (72) on top of the vacuum foil, inserting a second insert (80) into the second gap (74) on top of the vacuum foil, infusing resin into the fibre material to form a resin-infused fibre material, curing the resin-infused fibre material to form the fibre-reinforced spar cap (41), removing the first and second inserts (78, 80) and the vacuum foil (76), and demoulding the fibre-reinforced spar cap from the mould.

2. A method according to claim 1, wherein the first guide member (64) comprises a longitudinally extending guide surface (65), and wherein the second guide member (66) comprises a longitudinally extending guide surface (67) facing the guide surface (65) of the first guide member (64), the guide surface (65) of the first guide member diverging from the guide surface (67) of the second guide member in an upward direction.

3. A method according to claim 1, wherein the spar cap (41) has first and second longitudinally extending lateral surfaces (41a, 41b), wherein the first guide member comprises a longitudinally extending guide surface (65) forming an acute angle (b1) with the first lateral surface (41a) of the spar cap, and wherein the second guide member comprises a longitudinally extending guide surface (67) forming an acute angle (b2) with the second lateral surface (41b) of the spar cap.

4. A method according to claim 1, wherein the step of inserting the first insert (78) into the first gap (72) on top of the vacuum foil comprises squeezing the first insert into the first gap, and wherein the step of inserting the second insert (80) into the second gap (74) on top of the vacuum foil comprises squeezing the second insert into the second gap.

5. A method according to claim 1, wherein the fibre material comprises a plurality of strips (82) of fibre material arranged into adjacent stacks of strips.

6. A method according to claim 1, wherein the guide member comprises an upstand (84, 86) forming the longitudinally extending guide surface (65, 67).

7. A method according to claim 1, wherein the guide member has a substantially L-shaped cross section or a triangular cross section.

8. A method according to claim 1, wherein the first and second guide members extend along substantially the entire length (Ls) of the spar cap (41).

9. A method according to claim 1, wherein the first and second guide members are bolted to the mould.

10. A method according to claim 1, wherein the insert comprises a silicone material.

11. A method according to claim 1, wherein the insert comprises high density polyethylene (HDPE) and a silicone material.

12. A method according to claim 1, wherein the insert is substantially wedge-shaped.

13. A method according to claim 1, wherein the insert has a triangular cross section or a trapezoid cross section.

14. A method according to claim 1, wherein the inserts extend along substantially the entire length (Ls) of the spar cap.

15. A mould assembly (90) for manufacturing a fibre-reinforced spar cap (41) for a wind turbine blade, the mould assembly comprising a mould (62), a first guide member (64) comprising an upstand (84) and a second guide member (66) comprising an upstand (86), the first and second guide members being fastened to the mould for providing a moulding cavity (86) in between the first and second guide members, a first wedge-shape insert (78) for insertion into the moulding cavity, and a second wedge-shape insert (80) for insertion into the moulding cavity.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0035] The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

[0036] FIG. 1 shows a wind turbine,

[0037] FIG. 2 shows a schematic view of a wind turbine blade,

[0038] FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

[0039] FIG. 4 is a schematic perspective drawing illustrating various steps of the method of the present invention,

[0040] FIG. 5 is a schematic perspective drawing illustrating various steps of the method of the present invention, and

[0041] FIG. 6 is a schematic perspective drawing illustrating various steps of the method of the present invention,

[0042] FIG. 7 is a cross sectional view taken along the line A-A in FIG. 4,

[0043] FIG. 8 is a cross sectional view taken along the line A-A in FIGS. 5, and

[0044] FIG. 9 is a cross sectional view taken along the line A-A in FIG. 6.

DETAILED DESCRIPTION OF THE FIGURES

[0045] FIG. 1 illustrates a conventional modern upwind wind turbine according to the so-called Danish concept with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius denoted R.

[0046] FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profiled or an airfoil region 34 farthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

[0047] The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transitional profile gradually changing from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0048] A shoulder 40 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 40 is typically provided at the boundary between the transition region 32 and the airfoil region 34. FIG. 2 also illustrates the longitudinal extent L, length or longitudinal axis of the blade.

[0049] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and/or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and/or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0050] The blade is typically made from a pressure side shell part 36 and a suction side shell part 38 that are glued to each other along bond lines at the leading edge 18 and the trailing edge of the blade 20.

[0051] FIG. 3 shows a schematic view of a cross section of the blade along the line I-I shown in FIG. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 36 and a suction side shell part 38. The pressure side shell part 36 comprises a spar cap 41, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 36. The spar cap 41 comprises a plurality of fibre layers 42 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 45 comprising a plurality of fibre layers 46. The pressure side shell part 36 may also comprise a sandwich core material 43 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 38 may also comprise a sandwich core material 47.

[0052] The spar cap 41 of the pressure side shell part 36 and the spar cap 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 51, such as balsawood or foamed polymer, covered by a number of skin layers 52 made of a number of fibre layers. The blade shells 36, 38 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glue flanges.

[0053] FIGS. 4-9 illustrate various steps of the method of the present invention. As seen in FIGS. 4 and 7, a first guide member 64 and a second guide member 66, each having a substantially L-shaped cross section, are fastened to the moulding surface 90 of a mould 62. This can be advantageously be done by using bolts 88, as shown in the cross sectional view of FIG. 7. The guide members 64, 66 comprise respective upstands 84, 86 forming respective longitudinally extending guide surface 65, 67. A moulding cavity 68 is provided in between the first and second guide members 64, 66. The first guide member 64 comprises a longitudinally extending guide surface 65, and the second guide member 66 comprises a longitudinally extending guide surface 67 facing the guide surface 65 of the first guide member 64. As best seen in FIG. 7, the guide surface 65 of the first guide member diverges from the guide surface 67 of the second guide member in an upward direction, the planes in which the respective guide surfaces 65, 67 lie forming an angle .

[0054] As illustrated in FIGS. 5 and 8, a fibre material 70 is placed within the moulding cavity 68, such that a first gap 72 is provided between the fibre material 70 and the first guide member 64, and a second gap 74 is provided between the fibre material 70 and the second guide member 66. As seen in FIG. 8, the fibre material comprises a plurality of strips 82 of fibre material arranged into adjacent stacks of strips, such as pultruded fibre strips. As best seen in FIG. 8, the fibre material 70 or the final spar cap 41 has first and second longitudinally extending lateral surfaces 41a, 41b, wherein the first guide member 64 comprises a longitudinally extending guide surface 65 forming an acute angle 131 with the first lateral surface 41a of the spar cap, and wherein the second guide member 66 comprises a longitudinally extending guide surface 67 forming an acute angle 2 with the second lateral surface 41b of the spar cap.

[0055] As illustrated in FIG. 9, a vacuum foil 76 is placed over the fibre material 70/41 and the first and second guide members 64, 66, such that the vacuum foil 76 extends into the first and second gap 72, 74. For better visibility, the vacuum foil is omitted in the perspective view in FIG. 6. A first wedge-shaped insert 78 is inserted into the first gap 72 on top of the vacuum foil, and a second wedge-shaped insert 80 is inserted into the second gap 74 on top of the vacuum foil. This can be done by squeezing the first insert 78 into the first gap, and by squeezing the second insert 80 into the second gap. As seen in FIG. 6, the first and second guide members 64, 66 and the first and second inserts 78, 80 extend along substantially the entire length Ls of the spar cap 41.

[0056] Then, resin is infused into the fibre material to form a resin-infused fibre material, the resin is cured to form the fibre-reinforced spar cap 41. Subsequently, the first and second inserts 78, 80 and the vacuum foil 76 can be removed and the fibre-reinforced spar cap 41 can be demoulded from the mould 62.

[0057] The invention is not limited to the embodiments described herein and may be modified or adapted without departing from the scope of the present invention.

LIST OF REFERENCE NUMERALS

[0058] 4 tower [0059] 6 nacelle [0060] 8 hub [0061] 10 blades [0062] 14 blade tip [0063] 16 blade root [0064] 18 leading edge [0065] 20 trailing edge [0066] 30 root region [0067] 32 transition region [0068] 34 airfoil region [0069] 36 pressure side shell part [0070] 38 suction side shell part [0071] 40 shoulder [0072] 41 spar cap [0073] 42 fibre layers [0074] 43 sandwich core material [0075] 45 spar cap [0076] 46 fibre layers [0077] 47 sandwich core material [0078] 50 first shear web [0079] 51 core member [0080] 52 skin layers [0081] 55 second shear web [0082] 56 sandwich core material of second shear web [0083] 57 skin layers of second shear web [0084] 60 filler ropes [0085] 62 mould [0086] 64 first guide member [0087] 65 guide surface [0088] 66 second guide member [0089] 67 guide surface [0090] 68 moulding cavity [0091] 70 fibre material [0092] 72 first gap [0093] 74 second gap [0094] 76 vacuum foil [0095] 78 first insert [0096] 80 second insert [0097] 82 pultruded strip [0098] 84 upstand of first guide member [0099] 86 upstand of second guide member [0100] 88 bolt [0101] 90 moulding surface [0102] L length [0103] Ls length of spar cap [0104] r distance from hub [0105] R rotor radius