Abstract
The present invention relates to a moulding assembly (100) for manufacturing a shell part of a wind turbine blade, and to methods of manufacturing a shell part of a wind turbine blade using the moulding assembly. The moulding assembly (100) comprises a blade mould (96) with a moulding cavity (97), a gripping device (76) for releasably engaging a preform (98) for the shell part, and a lifting device (102). A tensionable member (112) is attached to the blade mould (96), and a tensioning unit coupled to the tensionable member is used for creating and maintaining tension on the tensionable member while arranging an engaged preform within the moulding cavity.
Claims
1-15. (canceled)
16. A molding assembly for manufacturing a shell part of a wind turbine blade, the molding assembly comprising: a blade mold for molding the shell part, the blade mold comprising a molding cavity; a gripping device for releasably engaging a preform for the shell part; a lifting device, wherein the gripping device is connected to the lifting device; a tensionable member with a proximal end and an opposing distal end, the proximal end of the tensionable member being releasably attachable to the blade mold, and the distal end of the tensionable member being coupled to the gripping device, and a tensioning unit engaged to the tensionable member for creating and maintaining tension on the tensionable member.
17. The molding assembly of claim 16, wherein the tensionable member is a cable, a strap, or a rope.
18. The molding assembly of claim 16, wherein the tensioning unit comprises a winding mechanism.
19. The molding assembly of claim 18, wherein the tensioning unit comprises a motor coupled to the winding mechanism.
20. The molding assembly of claim 16, wherein the tensioning unit comprises a ratcheting mechanism to maintain tension on the tensionable member.
21. The molding assembly of claim 16, wherein the proximal end of the tensionable member comprises an attachment device for attachment to an edge of the blade mold.
22. The molding assembly of claim 16, wherein the tensioning unit is mounted on the gripping device, and wherein the distal end of the tensionable member is coupled to the gripping device via the tensioning unit.
23. The molding assembly of claim 16, wherein the lifting device comprises a first hoisting device and a second hoisting device, each of the first and second hoisting devices comprising a respective load engaging member for connecting the first and the second hoisting devices to the gripping device, and wherein the gripping device is connected to the lifting device at the respective load engaging members of the first and second hoisting devices, such that the load engaging members are spaced apart from another
24. The molding assembly of claim 23, wherein the first hoisting device is independently operable from the second hoisting device.
25. The molding assembly of claim 23, wherein at least one of the first hoisting device or the second hoisting device comprises a chain hoist with a load chain, the respective load engaging member being located at the free end of the load chain.
26. The molding assembly of claim 16, wherein the gripping device comprises: a base frame; a plurality of gripping arms slidably mounted on the base frame, each gripping arm having a proximal end and a distal end; a plurality of gripping members for gripping a top surface of the preform, each gripping member being attached to the distal end of at least one of the gripping arms; and a plurality of lock members, each lock member being engaged with at least one of the gripping arms for allowing sliding motion of the gripping arm relative to the base frame in a first direction while preventing sliding motion of the gripping arm relative to the base frame in a second direction.
27. A method of manufacturing a shell part of a wind turbine blade using a molding assembly, the molding assembly having a blade mold having a molding cavity, a gripping device for releasably engaging a preform for the shell part, a lifting device, a tensionable member with a proximal end and an opposing distal end, the proximal end of the tensionable member being releasably attachable to the blade mold, and the distal end of the tensionable member being coupled to the gripping device, and a tensioning unit engaged to the tensionable member for creating and maintaining tension on the tensionable member, the method comprising: engaging a preform for the shell part with the gripping device, arranging the engaged preform within the molding cavity of the blade mold by moving the gripping device and the engaged preform by means of the lifting device; and disengaging the preform from the gripping device, wherein the step of arranging the engaged preform within the molding cavity comprises attaching the proximal end of the tensionable member to the blade mold, and subsequently creating tension on the tensionable member by using the tensioning unit.
28. The method of claim 27, wherein the step of arranging the engaged preform within the molding cavity of the blade mold further includes pulling the gripping device and the engaged preform towards the molding cavity using the tensionable member.
29. The method of claim 27, wherein the preform is manufactured in a preform mold, prior to engaging the preform with the gripping device, wherein the method further comprises a step of transferring the engaged preform to the blade mold using the lifting device and the connected gripping device, prior to arranging the engaged preform within the molding cavity of the blade mold.
30. The method of claim 27, further comprising: infusing resin into the blade mold after disengaging the preform from the gripping device; and curing or hardening the resin in order to form the blade part.
Description
DETAILED DESCRIPTION OF THE INVENTION
[0077] The invention is explained in detail below with reference to embodiments shown in the drawings, in which corresponding components are identified by the same reference numerals, wherein
[0078] FIG. 1 shows a wind turbine,
[0079] FIG. 2 shows a schematic view of a wind turbine blade,
[0080] FIG. 3 shows a schematic view of an airfoil profile through section I-I of FIG. 4,
[0081] FIG. 4 shows a schematic view of the wind turbine blade, seen from above and from the side,
[0082] FIG. 5 is a perspective drawing of a blade mould for producing a wind turbine shell part according to the present invention,
[0083] FIG. 6 is a perspective drawing of a base frame of a gripping device for use in the present invention,
[0084] FIG. 7 is a perspective drawing of a gripping device for use in the present invention,
[0085] FIG. 8 is an enlarged perspective view of a gripping member and a lock member for use in the present invention,
[0086] FIG. 9 is a perspective view of a socket arrangement for mounting on a blade mould,
[0087] FIG. 10 is a schematic view of different steps of a method of transferring a preform for a wind turbine blade,
[0088] FIG. 11 is a schematic side view of a moulding assembly,
[0089] FIG. 12 is a schematic side view of a moulding assembly according to the present invention, seen in a first position,
[0090] FIG. 13 is a schematic side view of a moulding assembly according to the present invention, seen in a second position,
[0091] FIG. 14 is a schematic side view of a moulding assembly according to the present invention, seen in a third position,
[0092] FIG. 15 is a schematic side view of moulding assembly according to another embodiment of the present invention, and
[0093] FIG. 16 is a schematic perspective view of moulding assembly according to another embodiment of the present invention.
DETAILED DESCRIPTION
[0094] 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.
[0095] FIG. 2 shows a schematic view of a first embodiment 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 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.
[0096] 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.
[0097] 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.
[0098] 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.
[0099] FIGS. 3 and 4 depict parameters which are used to explain the geometry of the wind turbine blade. 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.
[0100] 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.
[0101] 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.
[0102] As illustrated in FIG. 5, a manufacturing process for manufacturing a blade part, such as a blade half, may involve laying a number of preforms 98a, 98b, 98c in a blade mould 96. For example, the preforms 98a, 98b, 98c are used for a blade section starting from the root end of the blade, such as the root region. The preforms 98a, 98b, 98c are arranged in the moulding cavity 97, usually together with additional fibre material 94. Then, resin is infused to the moulding cavity 97, which is subsequently cured or hardened in order to form the blade part, such as a blade half.
[0103] FIG. 6 illustrates a base frame 62 for a gripping device suitable for use in the present invention. The base frame 62 may advantageously be suspended from a lifting device such as a crane or a hoist (not shown). The base frame of FIG. 6 comprises a plurality of vertically extending beams 64, a plurality of horizontally extending beams 66 in the longitudinal direction of the base frame 62, and a plurality of horizontally extending beams 68 in the transverse direction of the base frame 62.
[0104] Two horizontally extending sheath members 70 are arranged to receive respective angled support members 72, each support member 72 carrying a pivot connector 74 in the form of a ball member at its distal end. The pivot connector 74 is adapted for being received in a socket member 77 attached to a wind turbine blade mould of the type illustrated in FIG. 9. The socket member 77 may be affixed to a pole member 79 for attachment to a blade mould. Thus, when the preform held by the gripping device is suspended above a blade mould, one or more of the pivot connectors 74 may be received in one or more socket members 77 attached to the blade mould, such that the perform can be pivoted (turned) by simply lowering the same with a crane, without the need for further turning devices.
[0105] FIG. 7 illustrates an embodiment of a gripping device 76 for use in the present invention. The gripping device 76 comprises a base frame 62 of the type illustrated in FIG. 6 and a plurality of gripping arms 78 slidably mounted on the base frame 62. The gripping arms 78 may be mounted to the base frame 62 via one or more horizontally extending transverse support members 80. Alternatively, the gripping arms could be mounted directly on the frame 62, for example on the horizontally extending beams 68 in the transverse direction of the base frame 62.
[0106] Each gripping arm 78 has a proximal end 82 and a distal end 84, as also seen in the enlarged with of FIG. 8. The gripping device 76 further comprises a plurality of gripping members 86, such as needle grippers, for gripping a top surface of the preform, each gripping member being attached to the distal end 84 of at least one of the gripping arms 78, either directly or via a connection member 88. The needle gripper 86 preferably releasably attaches to the preform upon contact with the top surface of the preform.
[0107] Each gripping arm 78 also comprises a lock member 90, each lock member 90 for allowing sliding motion of the gripping arm 78 relative to the base frame 62 in an upward direction while preventing sliding motion of the gripping arm relative to the base frame in a downward direction. The lock member 90 may comprise a ratchet or a brake system. As best seen in FIG. 10, each gripping arm 78 is individually slidable relative to the base frame 62. Each gripping arm 78 may be slidably mounted within a slot 91 of a fixture 92 arranged on the base frame 62.
[0108] FIG. 10 illustrates a method of transferring a preform 73 for a wind turbine blade. The method comprises suspending a gripping device 76 over the preform 73, for example using the lifting device. In the illustrated embodiment the preform is manufactured in a preform mould 71 and is to be transferred to a blade mould for producing a shell half of a wind turbine blade. The gripping device 76 is lowered towards a top surface 75 of the preform 73 until a first gripping member 86a engages the top surface 75 of the preform 73; see FIG. 10b. the gripping device is further lowered until a second gripping member 86c engages the preform top surface 75; FIG. 10c. Meanwhile, the gripping arm 78a carrying the first, already engaged gripping member 86a is moved upwards relative to the base frame as upward movement of the gripping arms relative to the base frame 62 is allowed. The gripping arms of the gripping device 76 are thus pushed upwards relative to the base frame 62 by the engaged preform top surface during the step of lowering the gripping device.
[0109] In FIG. 10d, also the last gripping member (needle gripper) 86 has engaged the top surface 75 of the preform 73, while the other two gripping arms 78a, 78c have moved further upwards relative to the base frame 62. Subsequently, as seen in FIG. 10e, the gripping device is raised with the engaged preform for transporting and arranging the engaged preform 73 within a wind turbine blade mould (not shown). Downward movement of the gripping arms 78a-c relative to the base frame 62 is prevented by the lock members. The upward direction U and the downward direction D are indicated in FIG. 10e. Thus, as seen in FIGS. 10a-e, the positions of the gripping arms 78a-c relative to the base frame 62 is set by the top surface geometry of the preform.
[0110] FIG. 11 is a schematic side view of a moulding assembly. The moulding assembly 100 comprises a blade mould 96 for moulding the shell part, usually a shell half, such as an upwind shell half or a downwind shell half of the blade. The blade mould 96 comprises a moulding cavity 97 in which preforms, fibre layers, or balsa wood can be arranged, typically followed by resin infusion in a VARTM process. The moulding assembly 100 further comprises a gripping device 76, such as a needle gripper, preferably the gripping device illustrated in the preceding figures. The gripping device 76 is operable for releasably engaging a preform 98 for the shell part. The moulding assembly 100 also comprises a lifting device 102, such as a chain hoist, preferably a dual chain hoist, the lifting device comprising a first hoisting device 104a and a second hoisting device 104b, and usually a holder, such as an upper hook which can be suspended from scaffolding, a gantry or a crane (not shown), for example by using strap 89. The lifting device may also comprise a chain hoist housing with a lifting motor that drives a chain sprocket over which the chain moves. Each of the first and second hoisting devices may take the form of a chain hoist, usually comprising a load chain and a lifting chain wheel. Each of the first and second hoisting devices comprises a respective load engaging member 110a, 110b for connecting the first and the second hoisting devices 104a, 104b to the gripping device. The load engaging members are usually arranged at the respective free ends of the load chain and can, for example, take the form of respective lower hook which can engage the gripping device.
[0111] The gripping device 76 is connected to the lifting device 102 at the respective load engaging members 110a, 110b, such as lower hooks, of the first and second hoisting devices 104a, 104b, such that the load engaging members 110a, 110b are spaced apart from another. Thus, by using two hoisting devices 104a, 104b, the gripping device and the engaged preform can be tilted for accurate placement in the root region of the blade mould. FIG. 11c also illustrates angle between a plane of the engaged preform, or a tangent to the curved lower surface of the preform, and the ground surface. It is preferred that the first hoisting device 104a is independently operable from the second hoisting device 104b. Also, as seen in FIGS. 11, the respective load engaging members 110a, 110b of the first and second hoisting devices 104a, 104b are connected at opposing ends of the gripping device 76, for enabling a high degree of tilting.
[0112] FIG. 12 is a schematic side view of a moulding assembly 100 according to the present invention, seen in a first position. The moulding assembly 100 comprises a tensionable member 112, such as strap, with a proximal end 114 and an opposing distal end 116. The proximal end 114 of the strap is releasably attached to the blade mould 96, for example via attachment eye 124. When the gripping device 76 is further away from the blade mould, for example, prior to a preform lowering step, the proximal end 114 of the strap 112 may be free, i.e. detached from the blade mould.
[0113] The distal end 116 of the tensionable member 112 is coupled to the gripping device, in the illustrated embodiment via tensioning unit 118, which is mounted on the gripping device in the illustrated embodiment. The tensioning unit 118 may comprise a winding mechanism 120 engaged to the strap 112 for creating and maintaining tension on the strap. The winding mechanism may be coupled to a motor 122, such as an electric motor, for operating the winding mechanism. In addition, it is preferred that the tensioning unit comprises a ratcheting mechanism to maintain tension on the strap 112.
[0114] The method of manufacturing a shell part of a wind turbine blade using the moulding assembly according to the present invention is illustrated in the sequence of FIGS. 12-14. The engaged preform is arranged within the moulding cavity 97 of the blade mould by moving the gripping device 76 and the engaged preform by means of the lifting device 102, wherein the proximal end of the strap 112 is attached to the blade mould 96 as seen in FIG. 12. Subsequently, tension is created on the strap 112 by using the tensioning unit 118, i.e. the strap 122 is brought from a slack state (dashed line in FIG. 13) to a taut state as seen in FIG. 13. In addition, the gripping device 76 and thus the attached preform 98 can be further pulled towards the moulding cavity 97 using the strap and the tensioning unit 118; see arrow in FIG. 14. Subsequently, the preform can be disengaged from the gripping device 76, thus releasing the preform into the moulding cavity 97.
[0115] The step of arranging the engaged preform within the moulding cavity 97 of the blade mould may also include tilting the gripping device by means of the lifting device 102 comprising the first hoisting device and the second hoisting device. After preform disengagement, resin may be infused into the blade mould followed by curing and/or hardening the resin in order to form the blade part.
[0116] FIG. 15 shows a moulding assembly according to another embodiment of the present invention, wherein the moulding assembly comprises two tensionable members 112a, 112b, each having a proximal end 114a, 114b, and an opposing distal end 116a, 116b. The proximal end 114a of the first tensionable member 112a is releasably attached to the blade mould 96 at a first end of the blade mould, such as a leading edge end or edge of the blade mould. The proximal end 114b of the second tensionable member 112b is releasably attached to the blade mould 96 at an opposing second end of the blade mould, such as a trailing edge end or edge of the blade mould. The respective distal ends 116a, 116b of the tensionable member are each coupled to the gripping device via respective tensioning units 118a, 118b which are engaged to the respective tensionable members 112a, 112b for creating and maintaining tension on the tensionable members. Thus, the step of arranging the engaged preform 98 within the moulding cavity may comprise attaching the proximal end 114a, 114b of each tensionable member to opposing ends or edges, at attachment points 124a, 124b of the blade mould, and subsequently creating tension on both tensionable members by using the tensioning units 118a, 118b. Such embodiments can be used to further minimize undesired movement or rotation of the gripping device and the engaged preform during placement.
[0117] Another embodiment of the moulding assembly 100 of the present invention is illustrated in FIG. 16. The moulding assembly 100 comprises two tensionable members 112a, 112b, each with a proximal end 114 and an opposing distal end 116, wherein the proximal end 114 of the first tensionable member 112a is releasably attached to the blade mould at a root end 126 of the blade mould. The proximal end of the second tensionable member 112b is releasably attached to the blade mould at a tip end 128 of the blade mould. The respective distal ends of the tensionable members 112a, 112b are coupled to the gripping device 76 at opposing ends of the gripping device. Respective tensioning units 118 are engaged to the respective tensionable members 112a, 112b for creating and maintaining tension on the respective tensionable members (not seen for tensioning member 112b).
[0118] 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
[0119] 2 wind turbine [0120] 4 tower [0121] 6 nacelle [0122] 8 hub [0123] 10 blade [0124] 14 blade tip [0125] 16 blade root [0126] 18 leading edge [0127] 20 trailing edge [0128] 22 pitch axis [0129] 30 root region [0130] 32 transition region [0131] 34 airfoil region [0132] 40 shoulder/position of maximum chord [0133] 50 airfoil profile [0134] 52 pressure side [0135] 54 suction side [0136] 56 leading edge [0137] 58 trailing edge [0138] 60 chord [0139] 62 base frame [0140] 64 vertical beams [0141] 66 horizontal beams, longitudinal direction [0142] 68 horizontal beams, transverse direction [0143] 70 sheath member [0144] 71 preform mould [0145] 72 angled support member [0146] 73 preform [0147] 74 pivot connector [0148] 75 top surface of preform [0149] 76 gripping device [0150] 77 socket member [0151] 78 gripping arm [0152] 79 pole member [0153] 80 transverse support members [0154] 82 proximal end of gripping arm [0155] 84 distal end of gripping arm [0156] 86 gripping member [0157] 88 connection member [0158] 89 strap [0159] 90 lock member [0160] 91 slot [0161] 92 fixture [0162] 94 fibre material [0163] 96 blade mould [0164] 97 moulding cavity [0165] 98 preform [0166] 100 moulding assembly [0167] 102 lifting device [0168] 104 hoisting device [0169] 106 wheel [0170] 108 load chain [0171] 110 load engaging member [0172] 112 tensionable member [0173] 114 proximal end of tensionable member [0174] 116 distal end of tensionable member [0175] 118 tensioning unit [0176] 120 winding mechanism [0177] 122 motor [0178] 124 attachment point [0179] 126 root end of blade mould [0180] 128 tip end of blade mould [0181] c chord length [0182] d.sub.t position of maximum thickness [0183] d.sub.f position of maximum camber [0184] d.sub.p position of maximum pressure side camber [0185] f camber [0186] L blade length [0187] La length of rigid arm [0188] r local radius, radial distance from blade root r [0189] t thickness [0190] y prebend
