BLADES

Technical Field

This application relates generally to wind turbines, and more particularly, relates to a handling system and method used to move recently-manufactured wind turbine blades relative to a NDT (non-destructive testing) scanning system so as to identify any defects in the manufactured blade before installation at a wind turbine.

Background

Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A conventional horizontal-axis wind turbine installation includes a foundation, a tower supported by the foundation, and an energy generating unit positioned atop of the tower. The energy generating unit typically includes one or more nacelles to house several mechanical and electrical components, such as a generator, gearbox, and main bearing, and the wind turbine also includes a rotor operatively coupled to the components in the nacelle through a main shaft extending from the nacelle. Single rotor wind turbines and multi-rotor wind turbines (which may have multiple nacelles) are known, but for the sake of efficiency, the following description refers primarily to single rotor designs. The rotor, in turn, includes a central hub and a plurality of blades extending radially therefrom and configured to interact with the wind to cause rotation of the rotor. The rotor is supported on the main shaft, which is either directly or indirectly operatively coupled with the generator which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator. Wind power has seen significant growth over the last few decades, with many wind turbine installations being located both on land and offshore.

As noted above, blades interact with the wind to generate mechanical rotation of the rotor, which can then be converted into electrical energy. The blades move at varying speeds through the ambient environment surrounding the wind turbine, but often this movement is at high speed. Accordingly, forces and strain applied to the blades during use at the wind turbine can be very high, and as such, it is desired to avoid manufacturing the blades with any defects that may adversely affect how the blade carries these forces and strain.

The blades are typically formed from a shell of fiber composite, aluminum, or similar material with an outer skin defined by a series of layers of coatings (polymeric elastomers, paint, etc.) surrounding and covering an outer surface of the shell. The shell is connected to internal structures such as reinforcing webs during manufacturing, which results in many components and connection points being located within the closed periphery defined by the shell. This arrangement makes it difficult to accurately scan for and detect all the various types of defects that may have become present during blade manufacturing. Blade manufacturers typically utilize several types of so-called NDT, non destructive testing, on a manufactured blade to evaluate whether any defects are present that require correction before installation of the blade at a wind turbine. Conventional NDT detection methods include, but are not limited to: visual scanning (with cameras or manually by operators), acoustic scanning, thermography scanning, and ultrasonic inspections. These NDT detection methods are used to detect various types of potential manufacturing defects such as, for example, web-to-shell adhesive bonds being outside specification, web-to-shell adhesive forming weak "kissing" bonds, trailing edge and leading edge bond deficiencies, delaminations and/or dry spots in laminate construction, incorrect positioning of the blade components, wrinkles caused by non-straight fibers in the laminate, and core damages. Such conventional NDT testing of these and other types of potential defects requires a significant amount of operator labor (including high levels of expertise in reading scans) as well as time investment, each of which increases the cost and time necessary before putting a manufactured blade into operation at the wind turbine. Furthermore, the subjectivity involved in evaluating some of these scan results can lead to false positive indications of flaws or defects where the blade does not actually have such flaws or defects.

Accordingly, wind turbine manufacturers and operators are continuing to seek improved options for conducting NDT scans of manufactured wind turbine blades, preferably those which reduce the time and labor required for detecting any defects that must be corrected before installation of the blade, while also improving accuracy and reliability of such scans.

Summary

To these and other ends, embodiments of the invention are directed to a blade handling system configured to support and move a wind turbine blade past a tomography scanner for detecting manufacturing defects in the blade. The blade handling system includes a root end support trolley and at least one tip end support trolley. The root end support trolley includes a first support element that is mobile, and preferably mounted on wheels. The first support element selectively engages with a root end of the blade. Each tip end support trolley includes a second support element that is mobile, and preferably mounted on wheels, with the at least one tip end support trolley being configured to move in conjunction with the root end support. The second support element selectively engages with a mid-region of the blade between its root end and its tip end. The blade handling system also includes a motorized drive mechanism operated to move the root end support trolley and the tip end support trolley in a linear direction. Selected portions of the second support element directly contact the blade or are adjacent to the blade when the blade is engaged with the tip end support trolley(s). The selected portions are formed from low density materials that do not absorb X-rays such that when the blade is moved past and scanned by the tomography scanner, the selected portions of the second support element are not visible in the X-ray images produced by the scan. The wind turbine blade can thus be accurately imaged and any manufacturing defects properly identified, with less operator labor and time required to scan for such defects precisely.

In one embodiment, the first and second support elements engage with the blade in such a manner to produce a rigid support arrangement for the blade. The rigid support arrangement immobilizes the blade against shaking or other vibrational movements that interfere with accuracy of the X-ray images taken by the tomography scanner as the blade is moved by the root end support trolley and the at least one tip end support trolley through the tomography scanner. Thus, the blade handling system further assures the accurate detection of manufacturing defects in the blade by this arrangement.

In another embodiment, a mobile carrier frame is bolted into engagement with the root end of the blade, the mobile carrier frame typically having wheels. The first support element of the root end support trolley directly engages this mobile carrier frame to support and move the root end of the blade. The first and second support elements may further include one or more moveable grip elements operatively coupled to motorized actuators. The actuators move the grip elements into and out of rigid, direct engagement with at least one of the blade and the mobile carrier frame.

In a further embodiment, the blade handling system includes a track having at least one of grooves and rails that receive the root end support trolley and the at least one tip end support trolley. The track extends in a linear direction and past the tomography scanner. In some embodiments, the track is recessed below a floor surface such that the track is spaced apart from the blade when the blade moves past the tomography scanner.

In yet another embodiment, the tomography scanner is a gantry scanner in which a scanning element can rotate around a support gantry to perform a CT scan. Such a gantry referred to herein may in particular be ring-shaped or otherwise circular or hoop like such that the tomography scanner can scan the blade from any angular position on the ring-shaped support gantry. The track is positioned to extend through the gantry scanner to enable any cross-section of the blade to be moved inside the gantry scanner for conducting the CT scan at that cross-section of the blade. The track may also be formed from low density materials that do not absorb X-rays from the tomography scanner, in some embodiments.

In another embodiment, the motorized drive mechanism operates to drive the root end support trolley and the tip end support trolley(s) in opposite directions along the linear direction such that the blade is moved in one direction through the tomography scanner to produce at least one longitudinal scan of the blade, and then the blade can be moved in an opposite direction back through the tomography scanner to enable more longitudinal scans and/or detailed re-scans of selected cross-sections of the blade, such as with CT scanning.

A positioning unit may also be mounted on the root end support trolley in further embodiments. The positioning unit is mounted so as to be positioned beyond the root end of the blade in a longitudinal direction of the blade. The positioning unit is detectable by the tomography scanner and thus, may be used to identify a location of the root end of the blade such that a longitudinal scan of the blade can be performed as the blade then follows the positioning unit during movement past the tomography scanner. The detection of the positioning unit can also be used to trigger initiation of a longitudinal scan of the blade when the scanning process is automated.

In a further embodiment, selected portions of the first support element directly contact the blade or are adjacent to the blade when the blade is engaged with the root end support trolley. As such, the selected portions of the first support element are also formed from low density materials that do not absorb X-rays from the tomography scanner. In these and other embodiments, the low density materials do not include any metal materials, but instead, the low density materials are defined by one or more of: plastics, fiber reinforced composites, wood, foam, and adhesives. Preferably, said selected portions of said first support element may exhibit a thickness contacting the blade surface, which thickness extends 1cm or more; or 2cm or more; or 3cm or more; or 4cm or more; or 5cm or more. In embodiments, a low density material being made for example from foam and being configured to be in contact with a blade may have a greater thickness than a support element being made from e.g. composite material. In embodiments a support element may comprise a relatively rigid composite material overlaid with a pliable or conformable material such as foam or an elastic material such as rubber or soft plastics material.

Additional embodiments of the invention are directed to a method for scanning a wind turbine blade for manufacturing defects. The method includes moving the wind turbine blade into engagement with a root end support trolley and at least one tip end support trolley of a blade handling system. The root end support trolley includes a first support element selectively engaging a root end of the blade, and the tip end support trolley(s) includes a second support element selectively engaging a mid-region of the blade between its root end and its tip end, such that the blade is supported in a generally horizontal orientation on the blade handling system. The method also includes actuating a motorized drive mechanism of the blade handling system to move the support trollies along a linear direction past a tomography scanner, thereby moving the blade past the tomography scanner. The method further includes performing X-ray scanning with the tomography scanner as the blade moves past the tomography scanner to produce at least one longitudinal scan of the blade that can be evaluated for potential manufacturing defects. Selected portions of the second support element that directly contact the blade or that are adjacent to the blade are formed from low density materials that do not absorb X-rays such that the selected portions of the second support element are not visible in the longitudinal scan produced by the tomography scanner.

In one embodiment, when the tomography scanner produces more than one longitudinal scans of the blade, the method also includes moving the blade with the blade handling system past the tomography scanner multiple times to allow the tomography scanner to produce the more than one longitudinal scans. The method also includes moving the tomography scanner to a different angle relative to the blade for each of the longitudinal scans, thereby imaging the blade from a different perspective for each of the more than one longitudinal scans.

In one embodiment, the method includes, evaluating the at least one longitudinal scan to identify whether any potential manufacturing defects appear in the blade as well as a radius location where the potential manufacturing defects appear. If no potential manufacturing defects appear in the evaluation, the blade is transferred from the blade handling system for downstream processing without further scans at the tomography scanner. If one or more potential manufacturing defects appear in the evaluation, the motorized drive mechanism of the blade handling system is actuated to move selected cross-sections of the blade back to the tomography scanner. The selected cross-sections are at the radius locations where potential manufacturing defects were identified on the at least one longitudinal scan. Then, CT scanning is performed with the tomography scanner to capture a plurality of images when each of the selected cross-sections is positioned at the tomography scanner, thereby enabling computer construction of a CT image that is used to verify whether the potential manufacturing defects are present at each of the radius locations identified in the evaluation. For example, the tomography scanner may be a gantry scanner in which a scanning element can rotate around a support gantry to perform the CT scanning, in which case the blade handling system moves the blade through the support gantry of the tomography scanner when moving the blade along the linear direction (e.g., to conduct the at least one longitudinal scan).

In another embodiment, the method includes immobilizing the blade against shaking or other vibrational movements that interfere with accuracy of the X-ray scanning during engagement and movement of the blade with the blade handling system.

In a further embodiment, a mobile carrier frame is bolted into engagement with the root end of the blade, and the step of moving the wind turbine blade into engagement with the root end support trolley and the tip end support trolley(s) further includes moving the wind turbine blade with the mobile carrier frame and a blade transport dolly from a manufacturing site to a position adjacent the blade handling system, and transferring the wind turbine blade from the transport dolly to the first and second support elements of the blade handling system. In some embodiments, the root end support trolley and the tip end support trolley(s) are mounted on a track included in the blade handling system, with the track recessed below a floor surface on which the transport dolly sits. In such embodiments, the step of transferring the blade from the transport dolly to the first and second support elements further includes engaging the first support element of the root end support trolley with the mobile carrier frame and lifting the mobile carrier frame with the first support element off of the floor surface to thereby support the root end of the blade, and lowering the blade with the transport dolly into engagement with the second support element of the at least one tip end support trolley to thereby support the tip end of the blade, and further lowering the transport dolly out of engagement with the blade so that the transport dolly can be moved along the floor surface away from the blade handling system. The track includes at least one of grooves and rails extending in the linear direction. In such embodiments, the step of actuating a motorized drive mechanism of the blade handling system to move the root end support trolley and the tip end support trolley(s) further includes driving the root end support trolley and the tip end support trolley(s) to move along the grooves and/or rails of the track to thereby move the blade along the linear direction while keeping the blade spaced apart from the track when the blade moves past the tomography scanner.

In yet another embodiment, a mobile carrier frame is bolted into engagement with the root end of the blade. The step of moving the wind turbine blade into engagement with the root end support trolley then further includes engaging the mobile carrier frame directly with the first support element of the root end support trolley to thereby support the root end of the blade.

In another embodiment, a positioning unit is mounted on the root end support trolley to be positioned beyond the root end of the blade in a longitudinal direction of the blade. The method then also includes detecting the positioning unit with the tomography scanner as the positioning unit moves past the tomography scanner during movement of the root end support trolley and the tip end support trolley(s). The positioning unit is used to identify a location of the root end of the blade when producing the longitudinal scan of the blade. In response to detecting the positioning unit, the X-ray scanning with the tomography scanner may be automatically initiated to cause generation of the longitudinal scan, in some embodiments.

The steps and elements described herein can be reconfigured and combined in different combinations to achieve the desired technical effects in different styles of wind turbines, as may be needed in the art.

Brief Description of the Drawinqs The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

Fig. 1 is a perspective view of a wind turbine including three wind turbine blades, each of which may be scanned for manufacturing defects before installation.

Fig. 2 is a perspective view of a wind turbine blade being moved onto a transport dolly after a manufacturing process, with a mobile carrier frame being bolted to the root end of the blade for further support, which typically occurs before transfer to the blade handling system according to embodiments of the present invention.

Fig. 3 is a perspective view of the wind turbine blade of Fig. 2 engaged with the blade handling system, which is configured to move the wind turbine blade past a tomography scanner as shown.

Fig. 4 is a side view of a first step of a method for scanning a wind turbine blade according to one embodiment of the invention, in which the transport dolly of Fig. 2 moves the wind turbine blade towards the blade handling system.

Fig. 5 is a side view similar to Fig. 4, showing further movement of the transport dolly and the blade relative to a track defined by the blade handling system.

Fig. 6 is a side view similar to Fig. 5, showing a further step of the method of this embodiment, in which the transport dolly has positioned the blade above a root end support trolley and a tip end support trolley, such as by moving the trolleys underneath the blade on the transport dolly.

Fig. 7 is a side view similar to Fig. 6, showing a further step of the method of this embodiment, in which the transport dolly has lowered the blade to transfer same to the blade handling system, with the mobile carrier frame engaged with a first support element at the root end support trolley and a mid-region of the blade engaged with a second support element at the tip end support trolley.

Fig. 8 is a side view similar to Fig. 7, showing a further step of the method of this embodiment, in which the root end support trolley and the tip end support trolley of the blade handling system move the blade in a linear direction through the tomography scanner.

Fig. 9 is a schematic front end cross-sectional view showing the tomography scanner conducting a detailed re-scan by CT scanning the cross-section of the blade located at the tomography scanner, which is done in another step of the method according to this embodiment.

Figs. 10A through 10E schematically illustrate several examples of a web-to-shell adhesive bond, some of which having defects that can be detected, in one example, by the tomography scanner in the method set forth in the embodiments of the invention.

Fig. 11 is a side view of another embodiment of a blade handling system in accordance with this invention, the blade handling system including a root end support trolley located longitudinally in front of the root end of the blade which it supports, and also a tip end support trolley supporting the tip end of the blade.

Detailed Description

With reference to Figs. 1 through 11 , embodiments of a blade handling system configured to support and move a wind turbine blade through a tomography scanner for detecting manufacturing defects in the blade are shown in detail. The blade handling system is used during an associated method for scanning the wind turbine blade for manufacturing defects in accordance with additional embodiments of the invention. The blade handling system advantageously supports the blade with a rigid support arrangement to immobilize the blade against shaking or other vibrational movements that interfere with accuracy of X-ray images generated by scans with the tomography scanner. Furthermore, selected portions of the blade handling system are formed from so-called low density materials that are generally invisible to the tomography scanner during X-ray scans and CT (computer tomography) scans, these selected portions being those which are directly engaged with or adjacent to the blade during the scanning process. It is noted that being "invisible" to the tomography scanner in the context of this invention is defined as an element not showing up at all on X-ray scan images produced by the scanner and/or an element not interfering with imaging of the visible blade features in the X-ray images produced by the scanner. By supporting the blade in this manner and by separating any portions of the blade handling system that would show up on X-ray scans from the blade during the scanning, an accurate and reliable scan of the blade for manufacturing defects therein can be provided when using the blade handling system of this invention, which reduces the number of "false-positive" defect scans as compared to conventional scanning technologies while also reducing the time and labor required to conduct such post-manufacturing scans and analysis. For example, the evaluation of these scans for manufacturing defects requires less expertise when reviewing the X-ray images than known blade scanning and evaluation techniques. The total number of types of manufacturing defects that can be detected is also improved over known combinations of multiple conventional scanning techniques when using the blade handling system and tomography scanner of the embodiments of this invention. Other advantages and technical effects of the embodiments of this invention will be evident from the following description.

Beginning with reference to Fig. 1 , a horizontal-axis wind turbine 10 of largely conventional design is shown. The 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. The rotor 16 of the wind turbine 10 includes a central hub 18 and a plurality of wind turbine blades 20 that project outwardly from the central hub 18 at locations circumferentially distributed around the hub 18. As shown, the rotor 16 includes three wind turbine blades 20, but the number of blades 20 may vary from one wind turbine to another. The wind turbine blades 20 are configured to interact with air flow to produce lift that causes the rotor 16 to spin generally within a plane defined by the wind turbine blades 20. As the rotor 16 spins, the wind turbine blades 20 pass through the air with a leading edge 22 leading the respective wind turbine blade 20 during rotation and a trailing edge 24 opposite the leading edge 22 along the longitudinal length of each blade 20. The wind turbine blades 20 in use are spaced apart from the ground surface by a significant distance, which normally renders maintenance and repair actions somewhat difficult. As such, it is desired to manufacture and install blades 20 that have minimal or no defects so as to limit the need for such maintenance and repair actions during the lifespan of the blades 20.

Accordingly, following blade manufacturing, which may involve various steps such as lay up of fiber composite materials into moulds to form blade shell halves and then assembly of the blade shell halves with internal components like support webs, it is typical to conduct detailed scans of the manufactured blade to detect whether any manufacturing defects are present. Detection of such defects allows for correction of such defects before the blade goes into installation and service at the wind turbine. Of course, such scanning and testing for defects should be done by non-destructive testing or "NDT" because the blade is to be put into service immediately after this post-manufacturing process. In embodiments of the present invention, this NDT scanning and analysis is conducting by using X-ray scans and CT scans from a tomography scanner. These scans with the tomography scanner can obviate the need for one or more types of conventional NDT scanning processes, including but not limited to: visual scanning, acoustic scanning, thermography scanning, and ultrasonic inspections. Thus, the blade handling system and methods for scanning described below significantly improve the post-manufacturing analysis of wind turbine blades, thereby also improving reliability of blades put into operation at wind turbines following these processes described herein.

Turning to Figs. 2 and 3, a general overview of how a manufactured wind turbine blade 20 is typically moved and the blade handling system 30 of this invention are provided. Following the initial manufacturing, the completed wind turbine blade 20 is usually moved onto a transport dolly 32 (also referred to as a wheeled blade transport dolly 32) for transport to various post-manufacturing processing steps. The transport dolly 32 is of known design and typically includes a main body 34 supported on a plurality of wheels 36, with gripping elements 38 such as moveable pads along a top end of the main body 34 configured to support and retain the blade 20 in position in a generally horizontal orientation (e.g., usually with the straight leading edge 22 facing downwardly) on the transport dolly 32. In the illustrated embodiment where one transport dolly 32 is used, it is located under a mid-region of the blade 20 located between a root end 26 and a tip end 28 of the blade 20. It will be understood that more than one transport dolly 32 and alternative types of transport vehicles may be used in other embodiments consistent with the scope of this invention. A mobile crane unit 40 may be used to transfer the blade 20 from a manufacturing site into the transport dolly 32, as shown in Fig. 2. Typically, a mobile carrier frame 42, which is preferably a wheeled carrier frame 42 as shown, is also bolted into engagement with the root end 26 to help support the blade 20 in combination with the transport dolly 32. The mobile carrier frame 42 can support the root end 26 of the blade 20 at its wheels on a floor surface or can be carried by another dolly or transport element as well understood in this art. The mobile carrier frame 42 is of conventional design and is also referred to in the field as an "H-carrier" or an Ά-frame. " With the blade 20 supported on the transport dolly 32 and on the mobile carrier frame 42, the blade 20 is ready for transport to one or more post-production stations such as inspection stations, a new version of which is now described below.

One embodiment of the blade handling system 30 of the present invention is shown in detail in Fig. 3. In this regard, the blade handling system 30 is configured to transport the wind turbine blade 20 past a tomography scanner 44 that is configured to conduct X-ray scans and CT scans of the blade 20 as detailed in further explanations provided below. For example, the blade handling system 30 moves the blade 20 along a linear direction past the tomography scanner 44 to allow for a longitudinal scan to be produced with X- ray scanning. This longitudinal scan can be evaluated for any potential manufacturing defects, and if such potential defects are revealed on the longitudinal scan, the blade handling system 30 can then move a selected cross-section of the blade 20 where the potential defect is located back to the tomography scanner 44. The tomography scanner 44 can then move around the blade 20 as shown by arrows 46 in Fig. 3 to product a CT scan of that selected cross-section, enabling further detailed analysis of the potential defect to determine whether the defect is actually present. Many different potential manufacturing defects can be reliably and accurately detected and diagnosed for repair using this scanning process, which is enabled by the blade handling system 30 of the present invention.

With continued reference to Fig. 3, the blade handling system 30 of this embodiment includes a root end support trolley 50 and a tip end support trolley 52, each of which is configured to move along a track 54 that is provided so as to be recessed below a floor surface 56, which advantageously spaces the track 54 apart from the blade 20 during support of the blade 20 with the blade handling system 30 to thereby avoid adverse effects on X-ray images taken of the blade 20 when moving along the track 54. The root end support trolley 50 includes a first support element 58 mounted on wheels 60 that engage with the track 54, the first support element 58 configured to engage with the mobile carrier frame 42 at the root end 26 of the blade 20. Similarly, the tip end support trolley 52 includes a second support element 62 mounted on wheels 64 that engage with the track 54. The second support element 62 is configured to engage with the blade 20 along a mid-region of the blade 20 between the tip end 28 and the root end 26. While only one tip end support trolley 52 is shown in this Fig. 3, it will be appreciated that more than one tip end support trolley 52 may be provided at different locations along the longitudinal length of the blade 20 in other embodiments of this invention. To this end, the blade handling system 30 includes the root end support trolley 50 and at least one tip end support trolley 52 for supporting and moving the blade 20.

The root end support trolley 50 includes additional elements, some of which are shown schematically in Fig. 3. The first support element 58 projects upwardly from the wheels 60 and may define a moveable grip element 68 shown to include a receiving slot 70 (see Fig. 6) in this embodiment. The grip element 68 is configured to be raised and lowered on the root end support trolley 50 to bring the receiving slot 70 into or out of rigid engagement with the mobile carrier frame 42 bolted onto the root end 26 of the blade 20. For this purpose, the root end support trolley 50 includes an actuator motor 72, shown schematically in Fig. 3, which can move the grip element 68 as such. The particular design of the moveable grip element 68 may be modified to be more like those gripping pads shown and described below with respect to the tip end support trolley 52 without departing from the scope of the invention, so long as the first support element 58 can help provide a rigid support arrangement for the blade 20 that immobilizes the blade 20 against shaking or other vibrational movements.

The root end support trolley 50 also includes a drive mechanism 74, which is also shown schematically in Fig. 3 as the motors and such are typically located within the body defined by the first support element 58. The drive mechanism 74 uses motors to drive the wheels 60 on the root end support trolley 50 so as to move the root end support trolley 50 along a linear direction defined by the longitudinal extent of the track 54. The drive mechanism 74 is specifically configured to move the support trollies 50, 52 so that the blade 20 is positioned within about one millimeter of accuracy, which allows for specific radius locations/cross-sections of the blade 20 to be precisely positioned at the tomography scanner 44 as set forth in the methods described herein. Any conventional design for this drive mechanism 74 may be used, but it will be appreciated that it should not create significant vibrational energy that could be transmitted into the blade 20 and adversely affect the tomography scans to be taken thereof. The drive mechanism 74 also actuates movement of the tip end support trolley 52 because the root end support trolley 50 is connected to the tip end support trolley 52 using a link 76 as shown in Fig. 3. The link 76 will be understood to be any element that can both connect the root end support trolley 50 to the tip end support trolley 52 and transmit movement energy in both directions between these elements. In one example, the link 76 shown in these Figures can be omitted because the blade 20 itself acts as a link to transmit movement between the support trollies 50, 52. Accordingly, actuations of the drive mechanism 74 cause the entire blade 20 to be moved when desired at the blade handling system 30.

A positioning unit 78 is also mounted on the root end support trolley 50 in this embodiment. The positioning unit 78 is connected to the first support element 58 in such a manner that it projects forwardly beyond the grip element 68 and therefore is positioned longitudinally in front of where the mobile carrier frame 42 is supported on the root end support trolley 50. The positioning unit 78 is formed from a material (metallics, etc.) that will be detected by X-ray scans conducted at the tomography scanner 44. Consequently, when the blade handling system 30 is moving the blade 20 along the linear direction, the positioning unit 78 will be the first element moving past the tomography scanner 44 and thus will be the first element detected by the tomography scanner 44. Such use of the positioning unit 78 can provide multiple functionalities. For example, the location of the positioning unit 78 can be used as a frame of reference to identify a starting location for the root end 26 of the blade 20 which will then follow to move past the tomography scanner 44 during the taking of a longitudinal scan of the blade 20. In another example, a fully automated scan operation can be initiated using the detection of the positioning unit 78, as the tomography scanner 44 can be triggered to start a longitudinal scan of the blade 20 after detecting the positioning unit 78 in such fully or partially automated embodiments, assuming that the blade handling system 30 is moving the blade 20 such that the root end 26 moves past the tomography scanner 44 before the tip end 28.

The tip end support trolley 52 includes additional elements as shown in Fig. 3. Like the root end support trolley 50 described above, the second support element 62 on the tip end support trolley 52 projects upwardly from the wheels 64 and includes moveable grip elements 82, shown in this embodiment in the form of gripping pads that engage with the surface of the blade 20. The tip end support trolley 52 includes an actuator motor 84, which is shown schematically in Fig. 3 as this element is typically within the interior of the second support element 62. The actuator motor 84 can move the grip elements 82 into and out of rigid engagement with the mid-region of the blade 20. The specific design of the grip elements 82 of the second support element 62 may be modified in further embodiments consistent with the scope of the invention, so long as the second support element 62 continues to help provide a rigid support arrangement for the blade 20 that immobilizes the blade 20 against shaking or other vibrational movements. When multiple tip end support trolleys 52 are provided in some embodiments, each may include these additional elements for engaging with the blade 20 to produce the rigid support arrangement, and it will be understood that additional links 76 will be provided to transmit movement energy to all the tip end support trolleys 52 using the drive mechanism 74 at the root end support trolley 50.

In order to help allow for reliable and accurate scanning with the tomography scanner 44, the blade handling system 30 is formed at least in part from so-called low density materials that will not absorb X-rays and therefore will not adversely affect the various scans of the blade 20 by the tomography scanner 44. To this end, at least selected portions of the second support element 62 are formed from one or more low density materials in the embodiments of the blade handling system 30. In one example, the upper end of the second support element 62, including at least the grip element 82, is formed from low density materials such that the portions of the second support element 62 either directly contacting the blade 20 or adjacent to the blade 20 are "invisible" (not visible and/or not interfering with the blade imaging by distortion, overcasting or the like, as defined above) to X-ray scanning when the blade 20 is moved by the blade handling system 30 past the tomography scanner 44. Exemplary low density materials for the elements of the root end support trolley 50 and the tip end support trolley 52 include one or more of the following: plastics, fiber reinforced composites, wood, foam, and adhesives. Generally, the low density materials do not include any metallic materials. Thus, the blade handling system 30 is configured to enable the scanning and inspection process for manufactured wind turbine blades 20 as described throughout this specification. A low density material which may not absorb X-rays in the present context may be a non-metallic material having a density below about 3000 kg/m ³ or below 2500 kg/m ³ or below 2000 kg/m3. Alternatively or additionally, a low density material which may not absorb X-rays in the present context may be a material having a density lower than the density of fibre-composite material made from fibres embedded in a resin matrix, said fibres including glass fibres or a mixture of glass fibres and other fibres such as for example a blend of glass fibres and carbon fibres. Such a material may in particular be non-metallic. It will be understood that more portions of the at least one tip end support trolley 52 and/or portions of the root end support trolley 50 may also be made from the low density materials in other embodiments of the blade handling system. In this regard, any portion of these support trollies 50, 52 that are close enough in proximity to the blade 20 to affect a substantial number of scans (whether longitudinal scans or CT scans) by the tomography scanner 44 should be formed from low density materials to allow for accurate scans unaffected by the blade handling system, while portions of the support trollies 50, 52 spaced apart from the blade 20 do not necessarily need to be formed from low density materials because the spacing apart of such structures from the blade 20 allows for accurate scanning at multiple angles by the tomography scanner 44. Nevertheless, in still further embodiments, the root end support trolley 50 (but for the positioning unit 78) and the tip end support trolley 52 are completely or substantially completely formed from low density materials, thereby rendering almost all of the blade handling system 30 invisible to X-ray scans.

The first and second support elements 58, 62 on the root end support trolley 50 and the tip end support trolley 52 are also designed such that these engage the blade 20 in a manner to produce the rigid support arrangement noted above. The rigid support arrangement immobilizes the blade 20, which is otherwise very flexible and prone to vibrational and other movements, against such shaking or vibrational movements that would interfere with the accuracy of the X-ray images taken by the tomography scanner 44. To this end, the rigid support arrangement provided by the blade handling system 30 immobilizes the blade 20 against vibrations both when the blade 20 is stationary at the tomography scanner 44 (for CT scans) and when the blade 20 is moved along the linear direction such that the tomography scanner 44 produces a longitudinal scan of the blade 20. The provision of the rigid support arrangement and the use of low density materials advantageously enables the blade handling system 30 to work with methods for scanning the wind turbine blade 20 as set forth herein, thereby increasing the accuracy and reliability of post-production scans for manufacturing defects. Several further details regarding the blade handling system 30 and the tomography scanner 44 are shown in Fig. 3. To this end, the track 54 of the blade handling system 30 is shown to include two rails 90 that extend in a linear direction and generally along the longitudinal length of the blade 20 when the blade 20 is supported on the blade handling system 30. The rails 90 engage with the wheels 60, 64 on the root end support trolley 50 and the tip end support trolley 52 to keep these elements moving along the linear direction. It will be understood that the track 54 may be alternatively formed by grooves that receive the wheels 60, 64 in other embodiments of the invention, or the track 54 may be omitted altogether in other embodiments in which the wheels 60, 64 are mounted so as to allow for movement generally only along the desired linear direction. By providing the track 54 as shown in Fig. 3, the position of the blade handling system 30 and the blade 20 can be consistently and predictably provided relative to the tomography scanner 44, which may be desired for enabling certain types of post-scanning analysis of the X-ray images taken, such post-scanning analysis not being described in further detail herein. Furthermore, although the track 54 is shown being recessed below the floor surface 56 in this embodiment, it will be understood that such recessing may not be necessary in other embodiments, so long as the transport dolly 32 can transfer the blade 20 to the blade handling system 30 in such other embodiments.

The track 54 and the elements thereof may be optionally formed from low density materials that are invisible to X-ray scans, similar to the other elements of the blade handling system 30 described above. In this regard, even though the track 54 is spaced apart from the blade 20 when the blade 20 is moved past the tomography scanner 44, and therefore does not need to be formed from low density materials in all embodiments, the track 54 is provided from one or more of the low density materials to render it invisible to the X-ray scans in all angles of scanning with the tomography scanner 44.

As noted above, the tomography scanner 44 of this embodiment is formed as a gantry scanner which is commercially available in the field from various suppliers. The tomography scanner 44 thus includes a support gantry 92 on which a scanning element 94 can rotate around an entire periphery of the element being scanned, in this case, the wind turbine blade 20. The support gantry 92 is shown to be ring-shaped and circular in this embodiment, but it will be understood that different types of gantry may be used in other embodiments. The scanning element 94 is typically mounted on one side of the support gantry 92 while a film 96 is mounted on the opposite side of the support gantry 92. The scanning element 94 emits X-rays or similar energy through the blade 20 and then the structure revealed by the X-rays is images onto the film 96, as is well understood in the tomography scanning art. When conducting CT scanning of a stationary cross- section of the blade 20, the scanning element 94 moves as shown by arrows 46 around the support gantry 92 and the film 96 also moves to continue being on an opposite side from where the X-rays are emitted by the scanning element 94, the multiple images taken by the CT scanning configured to be combined by a computer into a three-dimensional image. When conducting a longitudinal scan of a moving blade 20, the scanning element 94 and film 96 generally remain stationary on the support gantry 92, but the angle at which the scanning element 94 is positioned by be adjusted between passes of the blade 20 when more than one longitudinal scan is to be generated. It will be appreciated that other arrangements and elements may be used on the tomography scanner 44 in other embodiments of the invention, so long as both types of scan (longitudinal scan and CT detailed re-scans of selected cross-sections) are able to be provided. As noted above, the blade handling system 30 is specifically configured to allow for accurate and reliable tomographic scans to be taken to reveal any manufacturing defects in the wind turbine blade 20.

Now turning with reference to Figs. 4 through 9, a method is shown for moving the wind turbine blade 20 and scanning for manufacturing defects in accordance with an embodiment of the present invention. In Fig. 4, the blade 20 has been loaded onto the transport dolly 32 for movement away from the manufacturing site as described in detail above (see Fig. 2, for example). In this circumstance, the blade 20 is supported by the mobile carrier frame 42 and the transport dolly 32 as initially described above, with the wheels of each of these support frame/dolly elements being in contact with the floor surface 56 as shown. The blade 20 is held in a generally horizontal orientation with the leading edge 22 thereof facing downwardly towards the floor surface 56. The transport dolly 32 then moves as shown by arrow 100 along the floor surface 56 towards a location adjacent the track 54 recessed below the floor surface 56. The transport dolly 32 continues to move until the blade 20 is positioned adjacent or effectively over the track 54 along an entire longitudinal length thereof, as shown in the further view of Fig. 5. It will be understood that in one example, the wheels 36 of the transport dolly 32 and the wheels of the mobile carrier frame 42 are spaced laterally apart enough to straddle over the trough defined by the recessed arrangement of the track 54 below the floor surface 56 during this movement shown in the Figures. In this position, the other elements of the blade handling system 30 are able to move underneath the blade 20 so as to prepare for receipt of the blade 20 from the transport dolly 32. It will be understood that the recessing of the track 54 below the floor surface 56 does not affect movement or operation of the transport dolly 32, such that the following transfer of the blade 20 can be effectuated.

In Fig. 6, the root end support trolley 50 and the tip end support trolley 52 previously described with reference to Fig. 3 have been moved along the track 54 to be positioned underneath the portions of the blade 20 and the mobile carrier frame 42 that are to be directly engaged by the blade handling system 30. In this regard, the receiving slot 70 on the first support element 58 is positioned immediately underneath the mobile carrier frame 42 at the root end 26, while the grip elements 82 on the second support element 62 are positioned underneath and proximate to the surface of the mid-region of the blade 20. From the position, the blade 20 is ready for transfer to the blade handling system 30. To this end, as shown in Fig. 7, the first support element 58 on the root end support trolley 50 is moved upwardly to engage the receiving slot 70 with and lift the mobile carrier frame 42 off of the floor surface 56, and the transport dolly 32 lowers the blade 20 until the mid region of the blade 20 directly engages with the grip elements 82 on the second support element 62. It will be understood that alternatively or in addition to movement downwardly with the transport dolly 32, the moveable grip element 82 may be moved by the corresponding actuator motor 84 as described above to produce the rigid support arrangement desired for the blade 20. Once the transfer to the blade handling system 30 and the support trollies 50, 52 is complete as shown in Fig. 7, the transport dolly 32 may be further lowered and then moved out from underneath the wind turbine blade 20 such that the transport dolly 32 can be used for other functions during the scanning method and operation on the wind turbine blade 20.

The blade handling system 30 is then ready to move the blade 20 for the scanning process to reliably identify any manufacturing defects in the blade 20. In this regard, the drive mechanism 74 is actuated to move the root end support trolley 50 and the tip end support trolley 52 along the linear direction defined by the length of the track 54. This movement is schematically illustrated by arrows 102 in Fig. 8. During this movement, the blade 20 moves through the tomography scanner 44 as shown in Fig. 8 as a result of the track 54 extending through this tomography scanner 44. As initially identified above, the tomography scanner 44 is configured to emit X-ray energy to conduct a longitudinal scan of the cross-section of the blade 20 as the blade handling system 30 moves the blade 20 through the tomography scanner 44. More specifically, the scanning element 94 of the tomography scanner 44 remains stationary on the support gantry 92, as does the film 96 that is used to capture images from the X-ray energy. In embodiments using the positioning unit 78, the tomography scanner 44 first detects the presence of this positioning unit 78 within the support gantry 92 as the root end support trolley 50 begins to move past the tomography scanner 44. This provides a reference point identifying where the root end 26 of the blade 20 begins to pass by the tomography scanner 44, e.g., one end of the longitudinal scan to be completed. The blade handling system 30 continues to move the blade 20 until the tip end 28 has passed through the tomography scanner 44, thereby completing an X-ray scan and image of the blade 20. As a result of some of the components of the blade handling system 30 being formed from low density materials and as a result of the rigid support arrangement immobilizing the blade 20 against vibrations and shaking, an accurate and precise X-ray image is produced in the longitudinal scan, which can then be evaluated for any potential manufacturing defects. This movement and scanning process is then repeated in embodiments of the method in which more than one longitudinal scan is to be provided, with the tomography scanner 44 moving to a different angle on the support gantry 92 between each of the longitudinal scans. The method then includes evaluating the at least one longitudinal scan to identify whether any potential manufacturing defects appear in the blade as well as a radius location where the potential manufacturing defects appear. To this end, the longitudinal scans have a positional scale inherently included, which allows for easy identification of the specific blade cross-section or "radius location" where any defects may be present, and this scale allows for various longitudinal scans to help confirm the radius location of any defects for further investigation. It will be appreciated that the expertise needed to evaluate these images is generally lower than conventional designs, and if no potential manufacturing defects appear, then the blade 20 can be transferred from the blade handling system 30 to downstream processing without further scans being required in the method. If the evaluation reveals that one or more potential manufacturing defects are present, further scanning to better identify manufacturing defects can be completed as follows.

The blade handling system 30 uses the root end support trolley 50 and the tip end support trolley 52 to move the blade 20 back to the tomography scanner 44 until a selected cross- section that appeared to include a potential manufacturing defect is located within the tomography scanner 44, and this is enabled by the scale inherently present within the longitudinal scan(s) of the blade as well as the drive mechanism 74 being configured to position the support trollies 50, 52 and the blade 20 within about 1 millimeter of position accuracy. The blade 20 is then held stationary by the blade handling system 30 as the tomography scanner 44 moves the scanning element 94 about the support gantry 92 to conduct a CT scan of the selected cross-section, as shown by movement arrows 104 in Fig. 9. The detailed re-scan and computer processing of the images taken results in a three-dimensional representation of the blade 20 as well as the floor surface as partially shown in Fig. 9 schematically. Further CT scans of adjacent cross-sections may be taken to provide even more detail as needed. Once a CT scan is performed for each cross- section that may contain manufacturing defects, the detailed re-scans of the blade 20 are evaluated to reliably identify the presence and severity of any manufacturing defects, thereby allowing for such defects to be diagnosed and repaired if necessary before installation of the blade 20 at a wind turbine 10. As will be readily understood from Fig. 9, the significant gap between the blade 20 and any other structures that absorb X-ray energy allows for a precise and accurate scan to be provided in the CT scanning.

One example of a potential manufacturing defect that may be revealed when using the scanning method and blade handling system 30 of this invention is shown in the schematic views of Figs. 10A through 10E. These Figures show several examples of the same web-to-shell bond that may be made between a reinforcing web 110 inside the wind turbine blade 20 and the outer shell (not shown) defining the outer portion of the blade 20. Such a bond is made with adhesive material 112 as shown, and it is desired to apply a precise amount of the adhesive material 112 in the correct location to make this bond (e.g., to keep these elements connected while avoiding any deficiencies such as "kissing" type bonds). A proper application of adhesive material 112 is shown in Fig. 10A, for example. By contrast, the other views show various types of deficiencies that may be deemed manufacturing defects: Fig. 10B shows a partial gap left in the adhesive material 112 along one side of the reinforcing web 110; Fig. 10C shows partial gaps in the adhesive material 112 along both sides of the reinforcing web 110; Fig. 10D shows adhesive material 112 applied to only one side of the reinforcing web 110; and Fig. 10E shows an overapplication of adhesive material 112 that extends beyond the sides of the reinforcing web 110. Such deficiencies in the adhesive application can be accurately detected by the tomographic scans in the embodiments described above, such that corrective action can be taken before installing the blade 20 at the wind turbine 10, if necessary. This is but one example of manufacturing defects that can be accurately detected and is not deemed to be limiting on this disclosure in any manner (it is provided for environment and explanation purposes). The blade handling system 30 and the associated methods of scanning improve the reliability and accuracy of detection of any manufacturing defects that may have occurred during production of the wind turbine blade 20.

It will be understood that the blade handling system 30 and the method of scanning may be modified in other embodiments while remaining consistent with the scope of this disclosure. For example, the root end support trolley 50 may be redesigned in another embodiment (such as the one described further below) to have a connection element formed from low density material and bolted directly onto the root end 26 of the blade 20, rather than interacting with the separate wheeled mobile carrier frame 42 as identified in the embodiment above. In another example, the method may be modified to have the blade handling system 30 move the blade 20 through the tomography scanner 44 for a series of different longitudinal scans, with the scanning element 94 moving to a different location on the support gantry 92 for each longitudinal scan to provide different longitudinal cross-sectional X-ray images of the blade 20, and the series of longitudinal scans can be evaluated together to identify any potential manufacturing defects that necessitate further scanning and/or evaluation. These and further modifications and additions may be made when using the blade handling system 30 and methods of the present disclosure.

One particular alternative embodiment of the blade handling system 130 is shown in a side view in Fig. 11. Many of the same elements from the previously-described embodiment of the blade handling system 30 are repeated and carry the same reference numbers in this Fig. 11 where they are substantially unchanged. For example, the tip end support trolley 52 is again shown with the second support element 62 contacting the blade 20, specifically using the moveable grip elements 82 along a mid-region of the blade 20 closer to the tip end 28 than the root end 26. In this embodiment, the root end support trolley 132 is redesigned and includes a different style of first support element 134. The first support element 134 includes a gripping member 136 that is directly bolted into engagement with the root end 26 of the blade 20 and/or directly engages the mobile carrier frame 42 adjacent the blade 20 rather than near the wheels of the mobile carrier frame 42. It will be understood that in such embodiments, the gripping member 136 is located in engagement with or adjacent to the blade 20 and as such, the gripping member 136 may be provided in the so-called low density materials described above. A remainder of the first support element 134 and the root end support trolley 132 are spaced apart from any portion of the blade 20 and furthermore, do not longitudinally overlap with even the root end 26, which reduces the likelihood that this remainder would adversely affect imaging of the blade 20 with the tomography scanner 44, even when such elements are provided in materials other than the so-called low density materials. Thus, in this embodiment at least selected portions of both the root end support trolley 132 and the tip end support trolley 52 are formed from low density materials to avoid showing up on the various scans taken at the tomography scanner 44. Further modifications of the blade handling system 130 are also possible, so long as the blade handling system 130 continues to provide the rigid support arrangement for the blade 20 while also avoiding adverse effects on X-ray imaging taken with the tomography scanner 44 during longitudinal scans and/or CT scans. It will also be understood that the blade handling system 130 continues to be mounted on a track 54 recessed below a floor surface 56 and that the pass off between the transport dolly 32 and the mobile carrier frame 42 and the first and second support elements 134, 62 is conducted in a similar manner as set forth in detail above.

Accordingly, the blade handling system 30 according to the embodiments of this invention is configured to allow for tomographic X-ray scanning of the blade 20 in a manner that is reliable and accurate, thanks at least in part to the use of low density materials in the components of the blade handling system 30 and the rigid support arrangement provided by the components of the blade handling system 30. Such tomographic scanning is generally quicker and more accurate than several types of conventional NDT scans that are typically used in this post-production process of evaluating the blade's manufacturing quality. Moreover, additional types of defects may be detected using this type of scanning, further improving the reliability of blades 20 before installation at wind turbines 10. As a result of this improved reliability, maintenance and repair actions necessary on wind turbine blades 20 in operation can be significantly reduced, especially at the beginning of a blade's operational life cycle. The blade handling system 30 therefore improves the art of blade scanning for detecting and addressing manufacturing defects that may occur in the normal course of manufacturing a large, complex structure like a wind turbine blade 20.

While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant 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. Thus, the various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.