Powered hinge

Abstract

A powered hinge for turning a first structure, such as a mold for manufacturing a wind turbine blade shell, relative to a second structure, such as a second mold for manufacturing an opposing wind turbine blade shell. The powered hinge has a base part 14 and a rotational part 12. Three linear actuators 30, 50, 70 are provided for causing rotation of the rotational part relative to the base part. Each one of the linear actuators are secured to the hinge base part by their own individual pins. Two of the linear actuators 30, 50 are each cantilevered so as to be supported on only one side. The pins attaching the third actuator 70 to the base are not aligned with the pins of the other two actuators 30, 50.

Description

FIELD OF THE INVENTION The present invention relates to powered hinge for use in manufacturing a wind blade, for example a wind turbine blade for a wind turbine generator (WTG). The powered hinge is for turning a first structure for manufacturing a wind blade part relative to a second structure for manufacturing a wind blade part. BACKGROUND OF THE INVENTION There are challenges in manufacturing large composite parts. These will be explained in the context of wind turbine blades, as an example, which can be many tens of metres long. Conventionally, wind turbine blades comprise an outer shell composed of two shell-halves that are joined together, one shell-half defining one surface of the blade, and the other shell-half defining a surface on the opposite side of the blade (in some contexts, each shell-half may alternatively be referred to as a “shell”, and this terminology will generally be used in the rest of this document). The two shell-halves may also be referred as the upper shell and lower shell (depending on the orientation in which the blade is fabricated), or the leeward shell and windward shell, or the pressure side (PS) shell and the suction side (SS) shell, based on the aerodynamic shape of the blade. The shell defines a relatively thin surface or skin of the blade. The interior of the blade is generally hollow, except for one or more longitudinal internal structural components that provide the blade with stiffness. To manufacture a blade, a shell mold is provided for each of the upper shell and lower shell. Each mold defines the shape of the exterior aerodynamic surface of the respective shell portion. Dry fiber materials are laid up in each mold; each mold is bagged; and liquid resin is infused into the fiber. The resin is cured to form each solid shell. Longitudinal internal structural components of one or more spar structures and / or web assembly or web assemblies are bonded into the lower shell. Adhesive is applied to the leading edge (LE) and trailing edge (TE) of the lower shell, as well as to the tops of the internal structural components. The upper shell mold containing the upper shell is then lifted and rotated into position above the lower shell mold containing the lower shell. The upper shell mold is lowered into position on the lower shell mold. Clamps around the edges of the molds align the mold flanges (and the shells within the molds) and apply a clamping force. The adhesive is cured to an appropriate level such that the two shells are bonded together to form the blade. The clamps are released, the upper mold is removed, and the blade is lifted from the lower mold, so that the blade can be taken to a finishing area. In a conventional apparatus, the upper shell mold and lower shell mold are initially alongside each other and are connected by a number of hydraulically powered hinges that lift and rotate the upper shell mold through 180 degrees until it located on top of the lower shell mold. There are a number of problems with the conventional powered hinge design, including how to make the hinge compact and to utilize the space within the hinge, and how to provide the freedom for the positioning of the powering mechanism (such as linear actuators) to optimize mechanical efficiency of the hinge. The present invention aims to alleviate, at least partially, some or any of the above problems. SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a powered hinge for turning a first structure for manufacturing a wind blade part relative to a second structure for manufacturing a wind blade part, wherein the powered hinge comprises: a base part; a rotational part, rotatably joined to the base part to be rotatable relative to the base part about a rotation axis; and a first linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a first pin defining a first axis, and wherein the second end is rotatably attached to the base part by a second pin defining a second axis, a second linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a third pin defining a third axis, and wherein the second end is rotatably attached to the base part by a fourth pin defining a fourth axis; and a third linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a fifth pin defining a fifth axis, and wherein the second end is rotatably attached to the base part by a sixth pin defining a sixth axis, wherein: (i) each one of the second pin and fourth pin is attached to a single respective one of said linear actuators; (ii) the second pin and fourth pin are each cantilevered so as to be supported by the hinge base part on only one side of the second end of the respective first linear actuator or second linear actuator; and (iii) wherein the sixth axis does not coincide with either the second axis or the fourth axis. Another aspect of the invention provides a wind blade manufacturing apparatus comprising: a first structure for manufacturing a first wind blade part; a second structure for manufacturing a second wind blade part; and a plurality of powered hinges, each according to any one of the preceding claims, wherein the rotational parts of the powered hinges are attached to the first structure, and the base parts of the powered hinges are attached to the second structure, such that the first structure can be turned from a first position alongside the second structure to a second position on top of the second structure Further optional features of the invention are defined in the dependent claims. DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of non-limiting example, with reference to the accompanying drawings. The invention may further comprise, in any combination, any features of the embodiments which will now be described. Figure 1 illustrates a wind blade manufacturing apparatus; Figure 2 is a side view of a powered hinge; Figures 3 to 5 are further views of the powered hinge of Fig. 2 from different viewpoints; Figures 6 to 8 are a sequence of views of a powered hinge moving from the state for a mold in an open state to a closed state; and Figures 9 and 10 show a further example of a powered hinge. In the drawings, like parts are indicated with like reference numerals, and, for conciseness, description thereof will not be repeated. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a first structure 2 for manufacturing a wind blade part positioned on top of a second structure 4 for manufacturing a wind blade part. In this example, the first structure 2 comprises an upper shell mold 6, and the second structure 4 comprises a lower shell mold 8. A plurality of powered hinges 10 (also referred to herein as ‘hinges’ for conciseness) are spaced apart along the length of the structure 2, 4. Each hinge comprises a rotational part 12 that is rotatably joined to a base part 14. The rotational part 12 is attached to the first structure 2 by a first interface part 16, and the base part 14 is attached to the second structure 4 by a second interface part 18. By operating the hinges 10, as discussed more fully below, the first structure 2 can be moved from a first position in which it is alongside the second structure 4, to a second position (as illustrated in Fig. 1) in which the first structure 2 has been lifted and rotated 180 degrees to be on top of the second structure 4. In the first position, the two shell molds 6 and 8 are open and upward facing, such that respective shells can be fabricated in each mold, and internal structural components bonded in place. The first structure 2 with mold 6 is then turned by operating the hinges 10 to unite the two molded shells to form a blade. Referring to Figs. 2 to 5, a hinge 10 comprises a base part 14 comprising two parallel upright side pieces 20, in the form of side walls of a frame. A rotational part 12 is rotatably joined to the base part by bearings 24 and is rotatable relative to the base part about a rotation axis 26. In this example, the rotational part 12 comprises two portions, one attached to one side piece 20, and the other portion attached to the second side piece. Each portion comprises two parallel plates 22 with a bearing 24 and side piece 20 sandwiched between the two plates 22. A first linear actuator 30 (comprising a hydraulic cylinder and piston rod in the illustrated example, and which may be referred to simply as an actuator for conciseness) has a first end 32 attached by a first pin 34 to the rotational part 22, and a second end 36 attached by a second pin 38 to the base part 14. The attachments are rotatable, with the pins 34, 38 defining respective first axis 40 and second axis 42 about which the rotation can occur. In this example, the second pin 38 is supported at one end by the base part 14 and is cantilevered outward to where its other end is connected to the actuator 30. In this way, the first actuator is provided on the outer side of one of the side pieces 20 of the base part 14. The second pin 38 is attached to only one linear actuator 30 and is cantilevered such that it is supported by the hinge base part 14 on only one side of the second end 36 of the linear actuator 30. A second linear actuator 50 is provided on the opposite side of the hinge. The second linear actuator 50 and its attachment arrangement is substantially identical to the first linear actuator 30 (but in mirror image). The second linear actuator 50 has a first end 52 attached by a first pin 54 to the rotational part 22, and a second end 56 attached by a second pin 58 to the base part 14. The attachments are rotatable, with the pins 54, 58 defining respective third axis 60 and fourth axis 62 about which the rotation can occur. In this example, the first axis 40 is aligned with the third axis 60; the second axis 42 is aligned with the fourth axis 62; and the actuators 30, 50 operate in unison. In this example, the first pins 34, 54 comprise a common through-pin. However, this is optional, and each first pin 34, 54 can be separate and attached to only one linear actuator as described for the second pins 38, 58. A third linear actuator 70 is provided between the side pieces 20 of the base part 14. The third linear actuator 70 has a first end 72 attached by a first pin 74 to the rotational part 12, and a second end 76 attached by a second pin 78 to the base part 14. The attachments are rotatable, with the pins 74, 78 defining respective fifth axis 80 and sixth axis 82 about which the rotation can occur. In this example, the fifth and sixth pins 74, 78 are conventional clevis pins supported at both ends (on both sides of the relevant end of the third actuator) by the side pieces 20 of the base part 14 or by the plates 22 of the rotational part 12. Operation of the powered hinge will now be explained with reference to Figs. 6 to 8. Fig. 6 shows a starting position, in which a first structure for manufacturing a wind blade part would be alongside a second structure for manufacturing a wind blade part, with the first structure on the right and attached to the rotational part 12, and the second structure on the left attached to the base part 14. All actuators 30, 50, 70 commence by extending, which raises and rotates the rotational part 12 about the axis 26 and leads to a state such as shown in Fig. 7. As the rotation continues, the first and second actuators 30, 50 reach a maximum extension when their line crosses the axis 26, and then they start contracting. In Fig. 7 the rotational part 12 has been rotated 90 degrees from Fig. 6; the first and second actuators 30, 50 are now contracting, and the third actuator 70 is still extending. Similarly, as the line of the third actuator 70 crosses the axis 26 it also starts contracting, such that all actuators 30, 50, 70 are now contracting. Finally, the hinge reaches a second position (see Fig. 8), in which the rotational part 12 has been rotated 180 degrees from Fig. 6, in which an attached first structure has been lifted and rotated 180 degrees to be on top of the second structure (this is the situation as illustrated in Fig. 1 - the hinges 10 are in the state illustrated in Fig. 8). The above sequence of operation can be reversed, by powering the actuators appropriately, to return the hinge from the state of Fig. 8 (mold closed) to the state of Fig. 6 (mold open). As described above, the geometry of the apparatus requires 180 degree rotation to be achieved; this means that the load is transferred between the actuators, and there are inherently points at which actuators have to reverse their motion (extension to contraction). The powered hinges 10 of Fig. 1 are operated in a synchronous manner, in which the linear actuators are controlled by a programmable logic controller (PLC) to achieve synchronicity. In the case of hydraulic powered hinges, the hydraulic linear actuators are powered by variable speed pumps which in turn are controlled by the PLC. The hydraulic cylinder behaviour at the switch points, where their motion is reversed, as well as pressure control inside the hydraulic cylinders themselves, are controlled by the PLC. In this example of a powered hinge, the first and second actuators 30, 50 effectively replace a single larger actuator previously located within the hinge frame. Mounting the smaller first and second actuators 30, 50 outside the side portions 20, and articulating the first and second actuators to the base part on separate cantilevered pins, rather than on a single common pin passing through the hinge, frees up space within the hinge body. This increases the design freedom to optimize the hinge mechanism. For example, as shown in Fig. 8, the third actuator 70 can overlap the rotational axis (second axis 42 and fourth axis 62) of the second and fourth pins 38, 58 of the first and second actuators 30, 50 without clashing with the second and fourth pins (in some versions, the third actuator can completely cross or pass-through the line of the second axis and / or fourth axis). In one preferred version, the first axis 40, third axis 60 and fifth axis 80 are all arranged to be at the same distance from the rotation axis 26 of the hinge. However, in general, the freedom of locating the actuator pins allows for optimization of the geometry for maximum mechanical efficiency which is governed by the position of the actuator pins in relation to the main hinge rotational axis 26. The pins, such as 38, 58, comprise hardened steel can be attached to the base part 14 using means such as sleeves, lock-nuts, spacers, circlips and so forth. Further details of an example of the attachment of a linear actuator to the rotational part and base part of a hinge are illustrated in Figs. 9 and 10. A bearing is provided where each end of each actuator is rotatably attached to its respective pin. The bearings can be conventional rotational bearings, but in a preferred example of the invention, at least one of the bearings is a spherical bearing (such as a spherical plain bearing). The spherical bearing permits rotation in the plane normal to the respective pin, but also permit twisting and rotation not in that plane, for example by a few degrees, such as 8 degrees. The spherical bearing allows for misalignment of the pin axis relative to the actuator, for example due to pin deflection at maximum actuator load force. A spherical bearing is particularly preferred for the pins that are cantilevered and support an end of an actuator on only one side thereof, such as for the outer actuators 30, 50. An example of a powered hinge embodying the invention can provide a turning torque in excess of 500 kNm, such as 700 kNm. VARIANTS It is emphasised that the described and illustrated powered hinge is merely one specific example; the invention can be practiced in numerous different ways within the scope as defined by the claims. The following is merely a non-exhaustive list of alternatives or variants of the specifically described example. The illustrated base part 14 comprises side pieces 20 sandwiched between plates of the rotational part, but equally it can be done the other way around with the rotational part can comprise one or more items that are sandwiched between plates of a base part, or both items can be single walled or both double walled and so on. The side pieces 20 are shown in the form of plates that are upright and parallel, but could equally be non-planar and / or non-parallel. Each actuator is illustrated as a hydraulic actuator (with cylinder and rod; in principle the cylinder and rod can be swapped over without changing the mechanical function); however, each actuator can also be any suitable form of linear actuator, such as hydraulic, screw, telescopic, electrical, and so forth. In the illustrated example, the second and fourth pins (38, 58) are cantilevered and fixed to only one actuator each, and the fifth and sixth pins (74, 78) are supported at both ends with a (third) actuator attached to the middle of the pin. The first and third pins are provided as a single common through-pin with the first actuator attached on one end of that pin, and the second actuator attached at the other end of that pin. However, the first and third pins (36, 56) can be cantilevered and fixed to only one actuator each. The third actuator can also be provided on one or more cantilevered pin(s) or common (shared) pin(s). As well as the sixth axis 82 not coinciding with the second axis 42 or the fourth axis 62, the illustrated example shows the sixth axis 82 arranged at a different distance from the rotation axis 26 than the second axis 42 or fourth axis 62, but this is not essential and the if desired, the sixth axis 82 can be arranged at the same distance from the rotation axis 26 as the second axis 42 and / or fourth axis 62. Furthermore, the second axis 42 and fourth axis 62 do not have to be coincident. Figures 9 and 10 illustrate a further example of a powered hinge in which all of the first through sixth axes 40, 42, 60, 62, 80, 82 are unique and are not coincident with any other axis. If they are not coincident, this can enable the first and second actuators 30, 50 to reverse motion (from extension to contraction) at different times, and to smooth the hinge motion when the third actuator 70 is reversing motion. In further examples, different combinations of some of the axes can be coincident. In a preferred example, the third actuator 70 is larger and more powerful than the first and second actuators 30, 50, and applies more of the turning torque (or takes more of the load) when the hinge rotation angle is near zero degrees or 180 degrees (figs. 3 and 7). The first and second actuators 30, 50 assist the third actuator 70, particularly when the third actuator 70 is at or in the vicinity of reversing motion. The example has been described as the first and second structures 2, 4 for manufacturing a wind blade part comprising mold parts 6, 8. In an alternative example, the first and second structures can be post-mold structures for supporting wind blade parts after they have been removed from a mold, for example for post-molding finishing of the parts. Although the above description has specifically mentioned manufacturing a wind turbine blade, the invention can also be applied in other embodiments to assembling blade structures such as for wind assisted propulsion of sea transportation vessels. One or more of these blades can typically be vertically mounted on top of the vessel, and is rotatable about the vertical axis. The vessel can be, for example, a cargo container, oil / gas tanker, or grain tanker. The aerodynamic blade or blades utilises wind assistance to augment the conventional propulsion of the vessel, thereby reducing fuel costs and emissions. In this context, a blade may also be called a wing or a sail, but the term ‘blade’ is used herein to encompass these alternative terms. Thus every aspect of the present description and claims can be read as disclosing such methods, apparatus and blades by replacing the term “wind turbine” by “shipping vessel”. The term ‘wind blade’ is used herein as a generic term to encompass a ‘wind turbine blade’ and a shipping wing or sail.

Claims

1. A powered hinge for turning a first structure for manufacturing a wind blade part relative to a second structure for manufacturing a wind blade part, wherein the powered hinge comprises:a base part;a rotational part, rotatably joined to the base part to be rotatable relative to the base part about a rotation axis; anda first linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a first pin defining a first axis, and wherein the second end is rotatably attached to the base part by a second pin defining a second axis,a second linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a third pin defining a third axis, and wherein the second end is rotatably attached to the base part by a fourth pin defining a fourth axis; anda third linear actuator having a first end and a second end, wherein the first end is rotatably attached to the rotational part by a fifth pin defining a fifth axis, and wherein the second end is rotatably attached to the base part by a sixth pin defining a sixth axis,wherein:(i) each one of the second pin and fourth pin is attached to a single respective one of said linear actuators;(ii) the second pin and fourth pin are each cantilevered so as to be supported by the hinge base part on only one side of the second end of the respective first linear actuator or second linear actuator; and(iii) wherein the sixth axis does not coincide with either the second axis or the fourth axis.

2. A powered hinge according to claim 1, wherein the second axis is aligned with the fourth axis.

3. A powered hinge according to claim 1 or 2, wherein:(i) each one of the first pin and third pin is attached to a single respective one of said linear actuators;(ii) the first pin and third pin are each cantilevered so as to be supported by the hinge rotational part on only one side of the first end of the respective first linear actuator or second linear actuator; and(iii) wherein the fifth axis does not coincide with either the first axis or the second axis.

4. A powered hinge according to claim 3, wherein the first axis is aligned with the third axis.

5. A powered hinge according to any preceding claim, wherein the base part comprises two upright side pieces, and wherein the first and second linear actuators are each provided on the outer side of a respective side piece, and wherein the third linear actuator is provided in between the two side pieces.

6. A powered hinge according to any preceding claim, wherein the third linear actuator is more powerful than each of the first linear actuator and second linear actuator.

7. A powered hinge according to any preceding claim, wherein, in at least one position of the hinge, the third linear actuator overlaps at least one of the second axis and fourth axis.

8. A powered hinge according to any preceding claim, wherein the first axis, third axis, and fifth axis are all arranged at the same distance from the rotation axis.

9. A powered hinge according to any preceding claim, wherein the sixth axis is arranged at a different distance from the rotation axis than the second axis or fourth axis.

10. A powered hinge according to any preceding claim, wherein at least one of said pins is joined to at least one of said linear actuators by a spherical bearing.

11. A powered hinge according to any preceding claim, wherein the first, second, third and fourth pins are each joined to their respective linear actuator by a respective spherical bearing.

12. A powered hinge according to any preceding claim, wherein the or each linear actuator is one of: a hydraulic actuator, and an electric actuator.

13. A wind blade manufacturing apparatus comprising:a first structure for manufacturing a first wind blade part;a second structure for manufacturing a second wind blade part; anda plurality of powered hinges, each according to any one of the preceding claims,wherein the rotational parts of the powered hinges are attached to the first structure, and the base parts of the powered hinges are attached to the second structure, such that the first structure can be turned from a first position alongside the second structure to a second position on top of the second structure.

14. A wind blade manufacturing apparatus according to claim 13, wherein:the first structure comprises a first mold part, and each rotational part is attached to the first structure by a respective first interface part; andthe second structure comprises a second mold part, and each base part is attached to the second structure by a respective second interface part.

15. A wind blade manufacturing apparatus according to claim 13 or 14, wherein the powered hinges are arranged, spaced-apart, along the length of the first and second structures.

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