GB2485248A - Apparatus and method for splicing together two fibre webs. - Google Patents

Abstract

An apparatus 60 for splicing together two fibre webs 50 includes a head 62 having movable 66 and stationary 64 portions. The movable portion 66 includes a pivotal pawl 72 and a blade 114. The pawl 72 includes a punch for forming a flexible tab 146 from the fibre webs 50 having a free end and an attached end. The blade 114 includes a tip 118 and an opening 116 through the blade 114 adjacent the tip 118 and forms a slot through the fibre webs 50. The pawl 72 bends the free end of the flexible tab 146 through the opening 116 in the blade 114 so as to pull the free end 146 through the slot upon removal of the blade 114 from the fibre webs 50 to thereby provide a coupling between the fibre webs.

Description

APPARATUS FOR MAKING A WIND TURBINE BLADE COMPONENT AND

METHOD OF MAKING SAME

Technical Field

[0001] This application relates generally to wind turbines, and more particularly to an apparatus for constructing a wind turbine blade component and to a method of making a wind turbine blade component using such an apparatus.

Background

[0002] The typical modern wind turbine includes a tower that supports a nacelle at an upper end thereof. A rotor having a central hub and one or more blades is coupled to the nacelle and converts the kinetic energy of the wind into mechanical energy, usually in the form of a rotating main shaft. The nacelle includes various components, such as a drive train and a generator, that convert the mechanical energy from the rotor into electrical energy. Wind turbines are known to generate their highest yield (i.e., operating efficiency) under predetermined aerodynamic conditions of their blades, which may have a predetermined profile for optimizing lift on the blades. As the blades are a major aspect and cost of wind turbine construction, much effort has been directed toward the efficient manufacturing of the blades.

[0003] Wind turbine blades include an outer shell disposed about an inner support structure or spar. The spar provides the structural aspects of the blade (e.g., supporting the loads imposed on the blades) while the outer shell provides the aerodynamic aspects of the blade and is configured to generate lift. According to one conventional process, a wind turbine blade is manufactured by disposing structural outer shell material into two mold halves and then injecting a binder, such as an epoxy resin, polyester resin, or other suitable material around the structural outer shell material while a vacuum system (e.g., vacuum bag) presses the structural outer shell material into each of the mold halves. In an alternate process, pre-impregnated composite material may be used which precludes injecting the material with a binder. In any event, after curing the binder about the structural outer shell material (e.g., a fiberglass weave), the two halves of the wind turbine blade outer shell may be coupled to one another around a structural support member or spar.

The two halves of the wind turbine blade are typically coupled by adhesive material along, for example, the leading and trailing edges thereby completing blade construction.

[0004] The spar is typically formed in a separate process and then inserted into the molding apparatus at the appropriate time so as to form the blade.

One current method of forming the spar includes using an automatic fiber placement machine. A fiber placement machine includes an outer housing generally disposed about an inner mandrel. The outer housing includes a movable head which may be moved or wound around the inner mandrel in a circumferential and longitudinal direction (e.g., helical fashion). The movable head is operatively coupled to one or more rolls about which a fiber web is wound. The rolls are configured to feed fiber webs to the head as it moves around and back and forth along the mandrel to form the spar. The fiber webs are sufficiently tensioned so as to tightly wrap the fibers about the mandrel and maintain the shape and compaction needed to form the spar.

Such machines are known in the art and may be referred to in the industry as overwinders.

[0005] The length of fiber spooled about the rolls is not infinite and periodically, the fiber runs out and the rolls need to be replaced. In this regard, during such a switch out, the leading end of the new roll is spliced to the trailing end of the previous roll, which may be hanging relatively loosely about the mandrel. The splicing method is somewhat ad hoc with the leading end of the new roll being tucked under the trailing end of the previous roll and then patted down to loosely keep the leading end in place. No physical coupling between the fiber webs is made. The fiber placement machine is then restarted so as to once again move the head relative to the mandrel.

However, during this initial start up, the fiber placement machine is operated at a reduced speed and reduced tension on the fiber web. The reason for this is to prevent the leading end from being pulled away from the mandrel and becoming separated at the splice. After operating at a reduced level for some time, the fiber web of the new roll essentially becomes self-cinched (e.g., by wrapping about itself one or more times) such that normal operating speeds and tension on the fiber web may be resumed.

[0006] Heretofore, the process described above for producing the spar has been sufficient for most wind turbine applications. However, in order to make wind turbines even more cost efficient and competitive in the marketplace, wind turbine design criteria have become more stringent and demanding. By way of example, wind turbine blades are being designed to withstand ever-increasing loads without necessarily having a corresponding increase in size or weight (e.g., increase the strength to weight ratio). Additionally, current designs are calling for increased life spans. In this regard, for example, some current designs call for a thirty year life span of wind turbine blades and other major components of the wind turbine. To meet these new demands, engineers and designers have examined the manufacturing process in tremendous detail to locate the source of potential weaknesses in the wind turbine blade. Based on this detailed analysis, designs have found that the splicing process used in spar construction may result in a highly localized discontinuity in the spar material. The discontinuity may take the form of a void, wrinkle, kink, misalignment, material contamination or other malformation in the material that forms the spar. It is believed that these localized discontinuities act as locations of weakness with, for example, a local reduction in strength or stiffness, which may ultimately result in failure of the wind turbine blade.

[0007] Accordingly, engineers and designers have begun to look at the splicing process and develop improved apparatus and processes for making wind turbine blades that avoid the shortcomings and other drawbacks described above. More particularly, there is a need for an improved apparatus and associated method that allows fiber webs from separate rolls to be sliced together in a manner that avoids the discontinuities that result from the current splicing technique.

Summary

[0008] To address these and other drawbacks of conventional approaches, an apparatus for splicing together a first fiber web to a second fiber web in an overlap region of the fiber webs includes an operating head having a movable head portion and a stationary head portion. The movable head portion includes a pawl configured to be pivotally coupled to the movable head portion and a blade. The pawl includes a punch configured to form a flexible tab from the fiber webs in the overlap region. The flexible tab has a free end and an attached end that remains connected to the fiber webs. The blade includes a sharpened tip and a first opening through the blade adjacent the sharpened tip. The blade is configured to form a slot through the fiber webs in the overlap region adjacent, but spaced from the attached end of the flexible tab. The pawl is configured to pivot about a pivot axis so as to bend the free end of the flexible tab through the first opening in the blade so as to pull the free end of the tab through the slot upon removal of the blade from the fiber webs, thereby providing a coupling between the fiber webs in the overlap region.

[0009] In one embodiment, the pawl has an L-shaped configuration including a first leg and a second leg. The first leg includes an inner surface having a first surface portion and a second surface portion angled with respect to the first surface portion to define a nose adjacent a terminating end of the first leg. The second leg includes an inner surface having a first surface portion and a second surface portion separated from each other by a step.

The punch is adjacent the terminating end of the first leg and includes an arcuate surface. The stationary head portion may include a stop plate disposed between a portion of the pawl, such as the first leg thereof, and the blade. The stationary head portion facilitates the pivotal movement of the pawl. The blade may include a second opening therethrough and spaced from the first opening. The second opening may be configured to receive a portion of the pawltherethrough. The blade may further include a biasing member, such as a leaf spring, adjacent the second opening for contacting the portion of the pawl extending through the second opening and imposing a biasing force thereon.

[0010] In one embodiment in accordance with the invention, the splicing apparatus discussed above may be incorporated in a fiber placement machine. In this regard, the fiber placement machine may include a placement head and a mandrel, the splicing apparatus being incorporated into the placement head of the fiber placement machine. In another embodiment according to the invention, a wind turbine component may be formed using the fiber placement machine having the splicing apparatus incorporated therein. By way of example, the wind turbine component made from such a fiber placement machine includes a root, a spar, or a joint for coupling the root and spar. In still another embodiment, a wind turbine includes a tower, a nacelle coupled to the tower, and a rotor coupled to the nacelle and including a hub and at least one blade extending therefrom, wherein the at least one blade includes a blade component made from the fiber placement machine having the splicing apparatus according to aspects of the invention.

[0011] A method of splicing together a first fiber web and a second fiber web in an overlap region of the fiber webs includes forming a coupling between the fiber webs from a material that is the same as the material used to form the first and second fiber webs. Accordingly, the splice contains only a single material and material contamination issues raised by the presence of two or more materials may be avoided. This may be achieved, for example, by forming the coupling from the first and second fiber webs. More particularly, the method further includes forming a flexible tab from the fiber webs in the overlap region, the flexible tab having a free end and an attached end that remains connected to the fiber webs; forming a slot through the fiber webs in the overlap region adjacent, but spaced from the attached end of the flexible tab; and inserting the free end of the tab through the slot to provide the coupling between the first and second fiber webs. As noted above, this results in a physical coupling between the fiber webs in a way that no new material is introduced in the process as a result of the splice.

[0012] In one embodiment, forming the flexible tab includes penetrating the fiber webs with a punch to form the flexible tab, and forming the slot includes penetrating the fiber webs with a blade to form the slot. The method may further include bending the flexible tab in a direction toward the slot; inserting the free end of the tab through an opening in the blade that extends through the slot; and moving the blade back through the slot so as to pull the free end of the flexible tab through the slot. The method may be repeated to form several couplings in the overlap region of the fiber webs.

[0013] In yet another embodiment, a method of forming a wind turbine component includes winding a fiber web about a mandrel to form the wind turbine component and splicing together the first and second fiber webs according to the method discussed above on the occasion that the supply of the fiber web (e.g., roll) runs out. In still another embodiment, a wind turbine includes a tower, a nacelle coupled to the tower, and a rotor coupled to the nacelle and including a hub and at least one blade extending therefrom, wherein the at least one blade includes a blade component made according to methods discussed above.

Brief Description of the Drawings

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with a general description of the invention given above and the detailed description of the embodiments given below, serve to explain the embodiments of the invention.

[0015] Fig. 1 is a diagrammatic perspective view of a wind turbine having a blade component made with an apparatus in accordance with one embodiment of the invention; [0016] Fig. 2 is a perspective view of a wind turbine blade shown in Fig. 1; [0017] Fig. 3 is a cross-sectional view of the wind turbine blade shown in Fig. 2 taken along line 3-3; [0018] Fig. 4 is a schematic perspective view of a fiber placement machine according to an embodiment of the invention; [0019] Fig. 5 is a schematic side view illustrating an overlap region of fiber webs according to an aspect of the invention; [0020] Fig. 6 is a schematic top view of fiber webs being coupled together along an overlap region of the fiber webs according to an aspect of the invention; [0021] Fig. 7 is a schematic cross-sectional view of an apparatus for coupling fiber webs; [0022] Fig. 8 is another schematic cross-sectional view of the apparatus shown in Fig. 7; and [0023] Fig. 9 is another schematic cross-sectional view of the apparatus shown in Fig. 7 illustrating the formation of the coupling between the fiber webs in accordance with an aspect of the invention.

Detailed Description

[0024] With reference to Fig. 1 and in accordance with an embodiment of the invention, a wind turbine 10 includes a tower 12, a nacelle 14 disposed at the apex of the tower 12, and a rotor 16 operatively coupled to a generator (not shown) housed inside the nacelle 14. In addition to the generator, the nacelle 14 houses miscellaneous components required for converting wind energy into electrical energy and various components needed to operate, control, and optimize the performance of the wind turbine 10. The tower 12 supports the load presented by the nacelle 14, the rotor 16, and other components of the wind turbine 10 that are housed inside the nacelle 14, and also operates to elevate the nacelle 14 and rotor 16 to a height above ground level or sea level, as may be the case, at which faster moving air currents of lower turbulence are typically found.

[0025] The rotor 16 of the wind turbine 10, which is represented as a horizontal-axis wind turbine, serves as the prime mover for the electromechanical system. Wind exceeding a minimum level will activate the rotor 16 and cause rotation in a direction substantially perpendicular to the wind direction. The rotor 16 of wind turbine 10 includes a central hub 18 and at least one blade 20 that projects outwardly from the central hub 18. In the representative embodiment, the rotor 16 includes three blades 20 at locations circumferentially distributed thereabout, but the number may vary. The blades are configured to interact with the passing air flow to produce lift that causes the central hub 18 to spin about a longitudinal axis 22. The rotor 16 is mounted on an end of a main rotary shaft (not shown) that extends into the nacelle 14 and is rotatably supported therein by a main bearing assembly (not shown) coupled to the framework of the nacelle 14. The main rotary shaft is coupled to a drive train (not shown) having as an input the relatively low angular velocity main rotary shaft, and having as an output a higher angular velocity secondary rotary shaft (not shown) that is operatively coupled to the generator. The main shaft or rotor may also be directly coupled to the generator in direct-drive systems.

[0026] The wind turbine 10 may be included among a collection of similar wind turbines belonging to a wind farm or wind park that serves as a power generating plant connected by transmission lines with a power grid, such as a three-phase alternating current (AC) power grid. The power grid generally consists of a network of power stations, transmission circuits, and substations coupled by a network of transmission lines that transmit the power to loads in the form of end users and other customers of electrical utilities. Under normal circumstances, the electrical power is supplied from the generator to the power grid as known to a person having ordinary skill in the art.

[0027] With reference to Figs. 1-3, a wind turbine blade 20 is an elongate structure having, in an exemplary embodiment, an outer shell 24 disposed about an inner support element or spar 26. The outer shell 24 may be optimally shaped to give the blade 20 the desired aerodynamic properties to generate lift, while the spar 26 provides the structural aspects (e.g., strength, stiffness, etc.) to blade 20. The elongate blade 20 includes a first root end 28 which is coupled to the central hub 18 when mounted to rotor 16, and a tip end 30 longitudinally opposite to root end 28. As discussed above, the outer shell 24 includes a first, upper shell half 32 on the suction side of the blade 20, and a second, lower shell half 34 on the pressure side of the blade 20, the upper and lower shell halves 32, 34 being coupled together along a leading edge 36 and a trailing edge 38 located opposite one another across a chord of the blade 20.

[0028] In an exemplary embodiment, and as shown schematically in Fig. 4, the spar 26 may be formed in a fiber placement machine 40 having an inner mandrel 42 that defines a longitudinal axis 44 and a multi-axis machine placement head 46 that moves relative to the mandrel 42. As used herein, a fiber placement machine is any machine that deposits fibrous reinforcement material, such as onto a work surface or the like. In one embodiment, for example, the placement head 46 may move circumferentially about the mandrel 42 and in a direction generally parallel to the longitudinal axis 44 of the mandrel 42 while the mandrel 42 remains stationary. In an alternative embodiment, the placement head 46 may remain stationary and the mandrel 42 rotatable about the longitudinal axis 44 and movable in a direction generally parallel to the longitudinal axis 44. One or more rolls 48 may be associated with the placement head 46 for feeding fiber webs 50 to the placement head 46 to be deposited onto the mandrel 42 or on previously laid fiber webs to thereby form the spar 26 or other blade component. In one embodiment, the rolls 48 may be carried by the placement head 46.

Alternatively, the rolls 48 may be located separate from the placement head 46, but operatively coupled thereto.

[00291 The fiber webs 50 may be spooled or wrapped around the rolls 48 so that rotation of the rolls 48 allows the fiber webs 50 to be unwrapped therefrom and deposited onto the mandrel 42. The fiber webs 50 may be from a fibrous material suitable for forming the spar 26 or other component of the wind turbine blade 20. For example, the fiber webs 50 may be glass fibers, carbon fibers, or combinations thereof including, for example, glass and aramid or carbon and aramid. The fiber webs 50 may also be pre-impregnated or semi-impregnated with a suitable resin. A dry fiber web may also be used and resin introduced in some other manner. Those of ordinary skill in the art may recognize other materials used for fiber webs 50 and suitable for forming the structural components of the wind turbine blade 20.

[0030] As discussed above, periodically, the fiber webs 50 on the rolls 48 run out and the rolls 48 need replacing. As schematically illustrated in Figs. 5 and 6, this replacement of the rolls 48 results in a splicing process between the trailing end 52 of the fiber web 50 of the previous roll 48 and the leading end 54 of a fiber web 50a on a new roll 48a. This splicing process may take place in an overlap region 56 between the trailing end 52 of the previous roll 48 and the leading end 54 of the new roll 48a. In accordance with an aspect of the present invention, the splicing process provides a physical coupling between the two fiber webs 50, 50a that is capable of withstanding the tensions and speeds associated with fiber web placement on the mandrel 42 observed during normal operation of the fiber placement machine 40. This physical coupling may be performed prior to the new fiber web 50a being applied about the mandrel 42. This splicing process described herein is distinctly different from the self-cinching process currently used to splice the two fiber webs 50, 50a together, and provides certain benefits that address the drawbacks in the current apparatus and methods.

[0031] In this regard, Fig. 7 schematically illustrates a coupling apparatus, generally shown at 60, for physically coupling the two fiber webs 50, 50a in accordance with an aspect of the invention. The coupling apparatus 60 includes an operating head 62 having a stationary head portion 64 and a movable head portion 66. The operating head 62 is configured to be located on a first side 68 (e.g., the upper side) of the overlap region 56 of the fiber webs 50, 50a and the movable head portion 66 is configured to be moved in a direction generally toward and away from the first side 68 of the fiber webs 50, 50a, illustrated by arrow 70 in Fig. 7. For example, this direction may be in a generally vertical direction, although the invention is not so limited.

[0032] As illustrated in Figs. 7-9, the movable head portion 66 includes an L-shaped pawl 72 and a blade 74. The pawl 72 has an L-shaped body 76 defining a first leg 78 and a second leg 80. In an exemplary embodiment, and for purposes described below, the pawl 72 may be pivotally coupled to the movable head portion 66 at pivot point 82 so as to define a pivot axis 84 about which the pawl 72 may rotate. The terminating end 86 of the first leg 78 includes a punch 88 for penetrating through the fiber webs 50, 50a when the pawl 72 is sufficiently moved in the direction of the first side 68 (e.g., downwardly). For example, at least a portion of the edges of the pawl 72 at the terminating end 86 may be sharpened so as to penetrate the fiber webs 50, 50a. The punch 88 includes an arcuately-shaped contacting surface 90 for contacting the fiber webs 50, 50a. An inner side surface 92 of the pawl 72 includes a first surface portion 94 and a second surface portion 96 adjacent terminating end 86 angled relative to the first surface portion 94 to define a nose 98. The second leg 80, which projects away from the first leg 78 at about ninety degrees and toward blade 74, includes an outer surface 100 and an inner surface 102. The inner surface 102 includes a first surface portion 104 and a second surface portion 106 separated by a step 108. The outer and inner surfaces 100, 102 may meet at end face 110 at a terminating end 112 of the second leg 80.

[0033] The blade 74 has a generally elongated body 114 having a thickness that is significantly less than the width and length of the blade 74.

The blade 74 has a terminating end 116 that includes a sharpened tip 118 sufficient to penetrate the fiber webs 50, bOa. A first window or opening 120 is formed through the blade 74 adjacent the sharpened tip 118. The first opening 120 defines an upper edge 122, a lower edge 124, and a pair of generally parallel side edges 126 (one shown). A second window or opening 128 is also formed through the blade 74 at a location spaced from the first opening 120 and further from the sharpened tip 118. The second opening 128 defines an upper edge 130, a lower edge 132, and a pair of generally parallel side edges 134 (one shown). The blade 74 may further include a leaf spring 136 adjacent second opening 128 so as to overlie at least a portion of second opening 128. As illustrated in the drawings, the second opening 128 is configured to receive the terminating end 112 of the second leg 80 therethrough so as to slightly flex the leaf spring 136 (Fig. 7). The purpose of the first and second openings 120, 128, as well as the leaf spring 136 will be described in more detail below.

[0034] As shown in Figs. 7-9, the stationary head portion 64 of operating head 62 includes a stop plate or bar 138. The stop plate 138 may be disposed between the first leg 78 of the pawl 72 and the blade 74 with an upper end 140 of the stop plate 138 suitably spaced from the inner surface 102 of the second leg 80, and a lower end 142 of the stop plate 138 configured to be positioned adjacent the first side 68 of the fiber webs 50, bOa during use. The length of the stop plate 138 may be suitably chosen to achieve the purposes described below.

[0035] Operation of the coupling apparatus 60 will now be described. In this regard, the operating head 62 may be positioned adjacent the first side 68 of the fiber webs 50, 50a along the overlap region 56 in a ready position, as illustrated in Fig. 7, for example. The movable head portion 66 may be operatively coupled to an actuator, shown schematically at 144, for moving the movable head portion 66 toward and away from the first side 68 of the fiber webs 50, 50a. The actuator 144 may be activated to move the movable head portion 66 downward toward the first side 68 of fiber webs 50, 50a. The downward movement of the pawl 72 and blade 74 is sufficient to allow the punch 88 on the terminating end 86 of the first leg 78 and the sharpened tip 118 of the blade 74 to penetrate through the fiber webs 50, 50a. During the penetration of these parts through the fiber webs 50, 50a, the leaf spring 136 applies sufficient force on the terminating end 112 of the second leg 80 of pawl 72 to resist rotation of the pawl 72 and maintain the pawl 72 in an aligned position, as shown in Fig. 7.

[0036] As illustrated in Fig. 6, penetration of the punch 88 through the fiber webs 50, 50a forms a generally flexible tab 146 formed by the two layers of fiber webs 50, 50a. The flexible tab 146 includes a free end 148 and an attached end 150 that remains connected to the fiber webs 50, 50a and operates as a bend line. The penetration of the blade 74 through the fiber webs 50, 50a forms a generally straight slot 152. The slot 152 is generally aligned with the attached end 150 (e.g., bend line) of the flexible tab 146, but spaced therefrom by an amount less than the length of the flexible tab 146.

[0037] After the punch 88 and the blade 74 penetrate through the fiber webs 50, 50a, continued downward movement of the movable head portion 66 causes the second leg 80 of pawl 72 to contact the stop plate 138. More particularly, as the pawl 72 moves toward the fiber webs 50, 50a, the upper end 140 of the stop plate 138 contacts the first surface portion 104 of inner surface 102. As illustrated in Fig. 8, this stops the purely downward motion of the pawl 72 and initiates the rotational movement of the pawl 72 about pivot axis 84. In this regard, after this contact, additional downward movement of the pawl 72 causes the pawl 72 to rotate about pivot axis 84 (e.g., in a counterclockwise direction) such that the second portion 96 of inner surface 92 contacts the flexible tab 146 and bends the flexible tab 146 backwards, the flexible tab 146 pivoting along the bend line at attached end 150. The flexible tab 146 now overlies a second surface 154 of the fiber webs 50, SOa.

[0038] As the flexible tab 146 is pivoted by the pawl 72 so as to overlie the second surface 154 of the fiber webs 50, 50a, the free end 148 of the tab 146 is received through the first opening 120 in the blade 74. As illustrated in Fig. 8, at least a portion of the nose 98 of the first leg 78 may also extend through the first opening 120. The pawl 72 may continue to rotate about pivot axis 84 until the lower end 142 of stop plate 138 contacts the inner surface 92 of the first leg 78. At this point, the flexible tab 146 may be engaged against the upper edge 122 of the first opening 120. Additionally, the upper end 140 of the stop plate 138 may be engaged with the step 108 between the first and second surface portions 104, 106 of the inner side 102 of second leg 80. The leaf spring 136 continues to act on the second leg 80 of the pawl 72, but is insufficient to overcome the forces causing rotation of the pawl 72 about pivot axis 84.

[0039] After the pawl 72 has sufficiently rotated so as to insert the flexible tab 146 through the first opening 120 of the blade 74, the movable head portion 66 may be moved upwardly and away from the fiber webs 50, 50a. As the pawl 72 moves upward, the force resulting from contact between the stop plate 138 and the pawl 72 diminish and the force imposed by the leaf spring 136 causes the pawl 72 to rotate about pivot axis 84 back in the opposite direction (e.g., clockwise direction) toward its initial aligned position.

Additionally, as the pawl 72 rotates about pivot axis 84, the lower edge 124 of the first opening 120 contacts the flexible tab 146 and effectively pulls the tab 146 up through the slot 152 previously formed by the blade 74 such that the free end 148 of the flexible tab 146 overlies the first surlace 68 of the fiber webs 50, 50a. This bending of the flexible tabs 146 backwards and up through the slot 152 provides an effective coupling between the fiber webs 50, 50a.

[0040] When the movable head portion 66 has been moved sufficiently away from the fiber webs 50, 50a, the operating head 62 may be moved to another location to provide additional couplings between the fiber webs 50, 50a. Any number of couplings may be made between the fiber webs 50, 50a in the overlap region 56. Although four such couplings are shown in Fig. 6, this is merely exemplary. For example, more or less couplings, such as six such couplings, may be made in the overlap region 56. The particular arrangement of the couplings may also be varied to meet the needs or desires of a specific application. In this regard, the couplings may also include various orientations relative to the length direction of the fiber web. For example, Fig. 6 shows the couplings oriented at approximately ninety degrees relative to the length direction of the fiber web. This is merely exemplary and the couplings may be oriented at other angles, such as at +1-thirty degrees, relative to the length direction of the fiber web. Furthermore, the arrangement may include couplings having the same orientation or couplings having different orientations. It will be appreciated that other orientations and configurations are possible depending on the particular application.

[0041] The coupling between the fiber webs 50, 50a as described above provides a number of benefits relative to the current methodologies for splicing fiber webs in a fiber placement machine. In this regard, the coupling creates a physical connection between the trailing end 52 of the fiber web 50 of the previous roIl 48 and the leading end 54 of the fiber web 50a of the new roll 48a. Because of the physical connection, the fiber web may be sufficiently tensioned (e.g., prior to restarting the fiber placement machine) without the fiber webs coming apart at the splice. This, in turn, allows the fiber placement machine to resume operation at or nearly at full tension (e.g., the tension at normal operating parameters). Moreover, the fiber placement machine may be ramped up to normal speeds much quicker. Because the tension in the fiber web may be put up to substantially normal levels prior to resuming operation (e.g., no longer relying on self-cinching of the fiber web to reestablish normal tension levels), it is believed that the wrinkles, kinks, voids, or other discontinuities that may form locations of weakness or potential failure initiation sites may be eliminated or at the least substantially reduced in magnitude. It is further believed that the avoidance or reduction of these discontinuities will increase the acceptable loading of the wind turbine blades having components made in accordance with aspects of the invention.

Moreover, it is believed that the avoidance or reduction of these discontinuities will increase the life span of wind turbine blades having components made in accordance with aspects of the invention.

[0042] In addition to the above, the splicing the fiber webs together in the manner described above may provide further benefits. In this regard, the coupling between the fiber webs is achieved using only a single material, i.e., the material of the fiber webs is the material used to form the coupling. This is in stark contrast to any number of couplings, such as metal staples or the like, to facilitate the splicing of the fiber webs. It is believed that using multiple materials in the formation of the spar or other wind turbine components may contaminate the component and provide a location of weakness or potential failure initiation site. Aspects of the present invention overcome these issues by forming the coupling from the same material of the fiber webs used to form the component. Additionally, there may be an aversion to using metal in the construction of wind turbine blades due to lightning strikes, for example.

[0043] After the formation of the spar 26 or other blade component as described above, the spar 26 may be incorporated into the wind turbine blade according to techniques generally known in the art. In this regard, in an exemplary method, the outer shell 24 of wind turbine blade 20 may be formed by molding an upper shell half 32 in a first mold half and molding a lower shell half 34 in a second mold half. After the upper and lower shell halves 32, 34 are at least partially cured, the spar 26 may be positioned in one of the mold halves and the other mold half moved so as to overlie the mold half having the spar 26. The mold halves are brought together so that the edges of the shell halves 32, 34, such as the leading and trailing edges 36, 38, may be coupled together and thereby complete the construction of the wind turbine blade 20.

[0044] While the invention was primarily described in regard to forming the spar of a wind turbine blade, aspects of the invention are not so limited. In this regard, aspects of the present invention may provide benefits to a broad range of components formed using a fiber placement machine. This would include not only the spar of a wind turbine blade, but other wind turbine blade components as well. For example, some wind turbine blades call for a separate root and spar, the root being the structural support element adjacent the root portion of the blade. Each of the root and spar may be formed using a fiber placement machine which incorporates aspects of the present invention. Additionally, a fiber placement machine incorporating aspects of the present invention may also be used to form the joint between a separately formed root and spar. Thus, aspects of the invention are broader than just to the application of forming a spar. Other wind turbine blade components may also gain the benefits of embodiments of the present invention.

[0045] The coupling apparatus 60 in accordance with that disclosed herein may be incorporated in the fiber placement machine 40 in different ways. For example, in one embodiment, the coupling apparatus 60 may be incorporated into the placement head 46. Alternatively, the coupling apparatus 60 may be coupled to the fiber placement machine 40 at a location spaced from the placement head 46. Moreover, various devices and apparatus may accompany the coupling apparatus 60 to facilitate its use within the fiber placement machine 40. In this regard, for example, an alignment device may be provided to ensure proper alignment of the fiber webs. Those of ordinary skill in the art may recognize other apparatus and devices that will facilitate incorporation of the coupling apparatus 60 within the fiber placement machine 40.

[00461 While the invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art.

For example, benefits of the present invention may apply to other fiber placement processes wherein a fiber web is disposed relative to a tool to form a wind turbine component. The tool may include a mandrel, as discussed herein, or include other tools such as a mold or the like wherein fiber webs are rolled or otherwise placed therein for forming a wind turbine component. The invention in its broader aspects is therefore not limited to the specific details, representative methods, and illustrative examples shown and described.

Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.

What is claimed is:

Claims (23)

1. An apparatus for splicing together a first fiber web to a second fiber web in an overlap region of the fiber webs, comprising: an operating head having a movable head portion and a stationary head portion and configured to be positioned adjacent the overlap region of the fiber webs, wherein the movable head portion includes a pawl configured to be pivotally coupled to the movable head portion and a blade, the pawl including a punch configured to form a flexible tab from the fiber webs in the overlap region, the flexible tab having a free end and an attached end that remains connected to the fiber webs, the blade including a sharpened tip and a first opening adjacent thereto and configured to form a slot through the fiber webs in the overlap region adjacent, but spaced from the attached end of the flexible tab, wherein the pawl is configured to pivot to bend the free end of the flexible tab through the first opening in the blade so as to pull the free end of the tab through the slot upon removal of the blade from the fiber webs to thereby provide a coupling between the fiber webs in the overlap region.

2. The apparatus according to claim 1, wherein the pawl has an L-shaped configuration including a first leg and a second leg, the first leg including an inner surface having a first surface portion and a second surface portion angled with respect to the first surface portion to define a nose adjacent a terminating end of the first leg, the second leg including an inner surface having a first surface portion and a second surface portion separated from each other by a step.

3. The apparatus according to claim 2, wherein the punch is adjacent the terminating end of the first leg and includes an arcuate surface.

4. The apparatus according to any of the preceding claims, wherein at least a portion of the stationary head portion may be disposed between a portion of the pawl and the blade.

5. The apparatus according to any of the preceding claims, wherein the blade further includes a second opening spaced from the first opening, the second opening configured to receive at least a portion of the pawl therethrough.

6. The apparatus according to claim 5, wherein the blade further comprises a leaf spring configured to overlie the second opening in the blade.

7. A fiber placement machine incorporating the splicing apparatus according to any of claims 1-6.

8. The fiber placement machine according to claim 7, wherein the fiber placement machine includes a placement head and a mandrel, the splicing apparatus being incorporated into the placement head of the fiber placement machine.

9. A wind turbine blade component formed using the fiber placement machine according to claim 7 or 8.

10. The wind turbine blade component according to claim 9, wherein the blade component includes a root, a spar, or a joint for coupling a root to a spar.

11. A wind turbine, comprising: a tower; a nacelle coupled to the tower; and a rotor coupled to the nacelle and including a hub and at least one blade extending therefrom, wherein the at least one blade includes a blade component made according to claim 9 or 10.

12. A method of splicing together a first fiber web and a second fiber web in an overlap region of the fiber webs, comprising: forming a physical coupling between the fiber webs from a material that is the same as the material used to form the first and second fiber webs such that the splice only includes materials that form the fiber webs.

13. The method according to claim 12, wherein the coupling is formed from the first and second fiber webs.

14. The method according to claim 12 or 13 further comprising: forming a flexible tab from the fiber webs in the overlap region, the flexible tab having a free end and an attached end that remains connected to the fiber webs; forming a slot through the fiber webs in the overlap region adjacent, but spaced from the attached end of the flexible tab; and inserting the free end of the tab through the slot to provide a coupling between the first and second fiber webs.

15. The method according to claim 14, wherein forming the flexible tab comprises penetrating the fiber webs with a punch to form the flexible tab.

16. The method according to claim 14 or 15, wherein forming the slot comprises penetrating the fiber webs with a blade to form the slot.

17. The method according to claim 14, wherein inserting the free end of the tab through the slot comprises: bending the tabs in a direction toward the slot; inserting the free end of the tabs through an opening in a blade that extends through the slot; and moving the blade back through the slot so as to pull the free end of the tab through the slot.

18. The method according to any of claims 12-17 further comprising forming several couplings in the overlap region of the fiber webs.

19. The method according to any of claims 12-18, wherein the first and second fiber webs are formed by one or more fibers and are pre-impregnated or semi-impregnated with a resin such that the splice only includes the one or more fibers of the fiber webs and the resin.

20. A method of forming a wind turbine component, comprising: placing a fiber web relative to a tool to form the wind turbine component; and splicing together the first and second fiber webs according to the method of claims 12-19.

21. The method according to claim 20, wherein placing a fiber web includes winding a fiber web.

22. The method according to claim 20 or 21, wherein the tool includes a mandrel.

23. A wind turbine, comprising: a tower; a nacelle coupled to the tower; and a rotor coupled to the nacelle and including a hub and at least one blade extending therefrom, wherein the at least one blade includes a blade component made according to the method of claims 20-22.