SYSTEM AND METHOD FOR MANUFACTURING PREFORMS FOR A WIND TURBINE ROTOR BLADE

Abstract

The present invention relates to a manufacturing system and to a method for the manufacture of preforms for wind turbine blade parts. The system comprises two or more preform moulds (70), a fibre lay-up station (88) for placing a fibre material into the preform moulds (70), and a heating station (90) for heating the fibre material to form the preforms. At least two of the preform moulds (70) have substantially identical width W and substantially identical height H.

Claims

1. A manufacturing system for the manufacture of preforms (80) for wind turbine blade parts, the system comprising two or more preform moulds (70), each preform mould (70) having a width W, a height H and a length L, a fibre lay-up station (88) for placing a fibre material into the preform moulds (70), and a heating station (90) for heating the fibre material to form the preforms, wherein at least two of the preform moulds (70) have substantially identical width W and substantially identical height H.

2. A manufacturing system according to claim 1, wherein all preform moulds (70) have substantially identical width W and substantially identical height H, and optionally substantially identical length L.

3. A manufacturing system according to claim 1, wherein all preform moulds (70) have substantially identical width W, and wherein in a first subgroup of two or more preform moulds (70) all preform moulds (70) have substantially identical height H1, and in a second subgroup of two or more preform moulds (70) all preform moulds (70) have substantially identical height H2, wherein the height H2 exceeds the height H1.

4. A manufacturing system according to claim 1, wherein each preform mould (70) has a width W of between 1 and 3 meters and a height H of between 0.5 and 2 meters.

5. A manufacturing system according to claim 1, wherein each preform mould (70) has a width W of between 1 and 3 meters and a height H of 1 meter or less.

6. A manufacturing system according to claim 1, wherein each preform mould (70) has a length L of between 15 and 30 meters.

7. A manufacturing system according to claim 1, wherein each preform mould (70) has a bottom surface (82), a moulding surface (72) and an upper edge (74) adjacent to the moulding surface, wherein the preforms are stackable such that the upper edge (74) of an underlying preform mould (70) supports the bottom surface (82) of an overlying preform mould (70).

8. A manufacturing system according to claim 1, wherein the fibre lay-up station (88) is arranged to place a fibre material into two or more preform moulds (70) simultaneously.

9. A manufacturing system according to claim 1, wherein the system comprises four or more preform moulds (70).

10. A manufacturing system according to claim 1, wherein the wind turbine blade part is a blade half, a root laminate or a part thereof.

11. A method of manufacturing a plurality of preforms for wind turbine blade parts, said method comprising providing two or more preform moulds (70), each preform mould (70) having a width W, a height H and a length L, placing a fibre material and a binding agent into each preform mould (70), and heating the fibre material and the binding agent to a temperature of between 40 and 200 C. to form a plurality of preforms, wherein at least two of the preform moulds (70) have substantially identical width W and substantially identical height H.

12. A method according to claim 11, wherein all preform moulds (70) have substantially identical width W and substantially identical height H, and optionally substantially identical length L.

13. A method according to claim 11, wherein all preform moulds (70) have substantially identical width W, and wherein in a first subgroup of two or more preform moulds (70) all preform moulds (70) have substantially identical height H1, and in a second subgroup of two or more preform moulds (70) all preform moulds (70) have substantially identical height H2, wherein the height H2 exceeds the height H1.

14. A method according to claim 11, wherein each preform mould (70) has a bottom surface (82), a moulding surface (72) and an upper edge (74) adjacent to the moulding surface (72), wherein at least two preforms are stacked during the heating step such that the upper edge (74) of an underlying preform mould (70) supports the bottom surface (82) of an overlying preform mould (70).

15. A method according to claim 11, wherein the wind turbine blade part is a blade half, a root laminate or a part thereof.

16. A method of manufacturing a wind turbine blade part, such as a blade half, the method comprising: manufacturing a plurality of preforms (80) according to the method of claim 11, arranging the plurality of preforms (80) in a blade mould (76), optionally together with additional material, infusing resin to the blade mould (76), curing or hardening the resin in order to form the blade part.

17. A method of manufacturing a wind turbine blade part according to claim 16, wherein each of the plurality of preforms (80) is arranged at the root end of the blade mould (76).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0095] The invention is explained in detail below with reference to embodiments shown in the drawings, in which

[0096] FIG. 1 shows a wind turbine,

[0097] FIG. 2 shows a schematic view of a wind turbine blade,

[0098] FIG. 3 shows a schematic view of an airfoil profile through section I-I of FIG. 4,

[0099] FIG. 4 shows a schematic view of the wind turbine blade, seen from above and from the side,

[0100] FIG. 5 is a perspective drawing of a preform mould according to the present invention,

[0101] FIG. 6 is a perspective drawing of a blade mould containing preforms according to the present invention,

[0102] FIG. 7 is a perspective drawing illustrating different parts of the manufacturing system of the present invention,

[0103] FIG. 8 is a perspective view of a preform mould stack according to another embodiment of the present invention, and

[0104] FIG. 9 is a schematic view illustrating different steps of a method of manufacturing a wind turbine blade half according to the present invention.

DETAILED DESCRIPTION

[0105] 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 furthest from the hub 8.

[0106] FIG. 2 shows a schematic view of a first embodiment of a wind turbine blade 10 according to the invention. 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 furthest 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] FIGS. 3 and 4 depict parameters which are used to explain the geometry of the wind turbine blade according to the invention. FIG. 3 shows a schematic view of an airfoil profile 50 of a typical blade of a wind turbine depicted with the various parameters, which are typically used to define the geometrical shape of an airfoil. The airfoil profile 50 has a pressure side 52 and a suction side 54, which during usei.e. during rotation of the rotornormally face towards the windward (or upwind) side and the leeward (or downwind) side, respectively. The airfoil 50 has a chord 60 with a chord length c extending between a leading edge 56 and a trailing edge 58 of the blade. The airfoil 50 has a thickness t, which is defined as the distance between the pressure side 52 and the suction side 54. The thickness t of the airfoil varies along the chord 60. The deviation from a symmetrical profile is given by a camber line 62, which is a median line through the airfoil profile 50. The median line can be found by drawing inscribed circles from the leading edge 56 to the trailing edge 58. The median line follows the centres of these inscribed circles and the deviation or distance from the chord 60 is called the camber f. The asymmetry can also be defined by use of parameters called the upper camber (or suction side camber) and lower camber (or pressure side camber), which are defined as the distances from the chord 60 and the suction side 54 and pressure side 52, respectively.

[0111] Airfoil profiles are often characterised by the following parameters: the chord length c, the maximum camber f, the position d.sub.f of the maximum camber f, the maximum airfoil thickness t, which is the largest diameter of the inscribed circles along the median camber line 62, the position d.sub.t of the maximum thickness t, and a nose radius (not shown). These parameters are typically defined as ratios to the chord length c. Thus, a local relative blade thickness t/c is given as the ratio between the local maximum thickness t and the local chord length c. Further, the position d.sub.p of the maximum pressure side camber may be used as a design parameter, and of course also the position of the maximum suction side camber.

[0112] FIG. 4 shows other geometric parameters of the blade. The blade has a total blade length L. As shown in FIG. 3, the root end is located at position r=0, and the tip end located at r=L. The shoulder 40 of the blade is located at a position r=L.sub.w, and has a shoulder width W, which equals the chord length at the shoulder 40. The diameter of the root is defined as D. The curvature of the trailing edge of the blade in the transition region may be defined by two parameters, viz. a minimum outer curvature radius r.sub.o and a minimum inner curvature radius r.sub.i, which are defined as the minimum curvature radius of the trailing edge, seen from the outside (or behind the trailing edge), and the minimum curvature radius, seen from the inside (or in front of the trailing edge), respectively. Further, the blade is provided with a prebend, which is defined as y, which corresponds to the out of plane deflection from a pitch axis 22 of the blade.

[0113] FIG. 5 is a perspective view of a preform mould 70 according to the present invention. The preform mould 70 comprises a moulding surface 72 for moulding a preform and two adjacent edges 74a, 74b. As illustrated in FIG. 5, the preform mould 70 has a width W, a height H and a length L. For example, the width W may be 2 m, the height H may be 1 meter and the length L may be 20 m. In an example of the manufacturing system of the present invention, at least two of the preform moulds have substantially identical width W, height H and length L.

[0114] As illustrated in FIG. 6, the manufactured preforms 80a, 80b, 80c can be laid up in a blade mould 76 to form part of a wind turbine blade, such as the root laminate. It is particularly preferred that the preforms manufactured according to the present invention are used for a blade section starting from the root end 16 of the blade, such as the root region. As explained above, the preforms 80a, 80b, 80c are arranged in the blade mould, usually together with additional material, after which resin is infused, which is subsequently cured or hardened in order to form the blade part, such as a blade half.

[0115] FIGS. 7a, b and c illustrate different aspects of the preform manufacturing system of the present invention. FIG. 7a shows a stacked arrangement 78 of four preform moulds 70a-d, all preform moulds 70a-d having substantially identical width W, substantially identical height H and substantially identical length L. They are stacked such that the upper edges 74a, 74b of an underlying preform mould support the bottom surface 82 of an overlying preform mould. This is an efficient arrangement for storage and/or transport of the preform moulds.

[0116] A schematic fibre lay-up station 88 for placing a fibre material 84 into the preform moulds is shown in FIG. 7b. It comprises a fibre lay-up device 86 for laying fibres and optionally a binding agent onto the moulding surface 72 of the preform mould 70. Unlike the embodiment shown in FIG. 7b, the fibre lay-up station 88 and the fibre lay-up device 86 may also be arranged to lay up fibres in multiple, such as two or three, preform moulds simultaneously. This is greatly facilitated by the modular/standardised dimensions of the preform moulds of the present invention.

[0117] Finally, the laid-up fibre material and the binding agent are heated at the heating station 90 (FIG. 7c). In the embodiment shown in FIG. 7c, multiple preform moulds 70a-d, in a stacked arrangement, are simultaneously heated in an oven 92 to manufacture a plurality of preforms 80a-d. Again, this is facilitated by the modular/standardised dimensions of the preform moulds of the present invention.

[0118] FIG. 8 shows another embodiment of preform moulds 70a, 70b, 70c according to the present invention. Each preform mould 70a comprises a structure 94a having a moulding surface 72a, the structure 94a being mounted in between two laterally extending frames 96, 98. Thus, the preform moulds 70a, 70b, 70c can be conveniently stacked upon each other.

[0119] FIG. 9 illustrates different steps of a method of manufacturing a wind turbine blade half according to the present invention. First, a plurality of preforms is manufactured according to the above-described method including arranging a fibre material 84 and a binding agent into each preform mould 70; see FIG. 9a. The preform moulds are then stacked such that the upper edge of an underlying preform mould 70c supports the bottom surface of an overlying preform mould 70b; see FIG. 9b. The stacked preform moulds are subsequently heated, for example in oven 92, to form a plurality of preforms; see FIG. 9c. The preforms may be transferred, for example in the form of the stack of preform moulds 70a,b,c, to the blade mould 76, i.e. the mould for the blade half; see FIG. 9d. Next, the preforms 80a,b,c are arranged in the blade mould 76, optionally together with additional material, preferably at the root end of the blade mould 76 as illustrated in FIG. 9e; followed by resin infusion and curing or hardening in order to form the blade half, or a part thereof.

[0120] 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

[0121] 2 wind turbine [0122] 4 tower [0123] 6 nacelle [0124] 8 hub [0125] 10 blade [0126] 14 blade tip [0127] 16 blade root [0128] 18 leading edge [0129] 20 trailing edge [0130] 22 pitch axis [0131] 30 root region [0132] 32 transition region [0133] 34 airfoil region [0134] 40 shoulder/position of maximum chord [0135] 50 airfoil profile [0136] 52 pressure side [0137] 54 suction side [0138] 56 leading edge [0139] 58 trailing edge [0140] 60 chord [0141] 62 camber line/median line [0142] 70 preform mould [0143] 72 moulding surface of preform mould [0144] 74 edges of preform mould [0145] 76 blade mould [0146] 78 stack of preform moulds [0147] 80 preform [0148] 82 bottom surface of preform mould [0149] 84 fibre material [0150] 86 fibre lay-up device [0151] 88 fibre lay-up station [0152] 90 heating station [0153] 92 oven [0154] 94 structure [0155] 96 first laterally extending frame [0156] 98 second laterally extending frame [0157] H height of preform mould [0158] L length of preform mould [0159] W width of preform mould [0160] c chord length [0161] d.sub.t position of maximum thickness [0162] d.sub.f position of maximum camber [0163] d.sub.p position of maximum pressure side camber [0164] f camber [0165] L blade length [0166] r local radius, radial distance from blade root [0167] t thickness [0168] y prebend