WO2024120595A1

WO2024120595A1 - Adhesive dispensing vehicle and method

Info

Publication number: WO2024120595A1
Application number: PCT/DK2023/050294
Authority: WO
Inventors: Jeremy HAIGHT
Original assignee: Vestas Wind Systems A/S
Priority date: 2022-12-08
Filing date: 2023-12-07
Publication date: 2024-06-13

Abstract

Adhesive dispensing vehicle and method A vehicle for dispensing adhesive on the surface of a wind turbine blade component is described. The vehicle comprises a drive system for moving the vehicle in a direction of travel on the surface of the wind turbine blade component. The vehicle also comprises an adhesive shovel connected to a supply of adhesive. The shovel is configured to dispense a bead of adhesive behind the vehicle when the vehicle moves in the direction of travel. The vehicle includes a sensor for determining a position of an adhesive flow front near a front end of the shovel. A controller of the vehicle is configured to control the speed of the vehicle in the direction of travel in dependence upon the monitored position of the adhesive flow front. An associated method of dispensing adhesive using the vehicle is also described.

Description

Adhesive dispensing vehicle and method

Technical field

The present invention relates generally to the manufacture of wind turbine blades, and more specifically to a vehicle and associated method for dispensing adhesive on a wind turbine blade component such as a wind turbine blade shell.

Background

Wind turbine blades are typically formed from first and second half shells that are bonded together along their leading and trailing edges. One or more shear webs are usually arranged inside the blade and bonded between opposed inner surfaces of the half shells. The shear webs are longitudinally-extending structures and comprise upper and lower mounting flanges. The lower mounting flange is bonded to the inner surface of the first half shell and the upper mounting flange is bonded to the inner surface of the second half shell.

The process of bonding the shear webs to the half shells typically involves depositing a bead of adhesive along the inner surface of the first half shell. The shear web is then lifted into the first half shell and its lower mounting flange is arranged on top of the bead of adhesive. A further bead of adhesive may be applied to the upper mounting flange of the shear web. Adhesive is also applied along the leading and trailing edges of the first half shell. The second half shell is then lifted and positioned on top of the first half shell. The weight of the second half shell bears down on the shear web and compresses the adhesive between the mounting flanges and the inner surfaces of the half shells.

The bead of adhesive is typically deposited on the blade shell surface in a manual process that involves moving a glue shovel along the surface of the blade shell. The glue shovel is mounted on the end of a handle that is pushed by an operator. Adhesive is continuously supplied to the glue shovel through a hose from an adhesive dispensing machine. As the glue shovel is pushed along the surface of the blade shell, a bead of adhesive is extruded behind the shovel. The shovel is shaped to impart a desired profile to the adhesive bead. As the geometry of a shear web typically varies along the length of the blade, it is also known to vary the profile of the adhesive bead at different radial positions along the length of the blade shell. The current manual method involves utilising a number of different glue shovels, one for each of the different adhesive profiles. When the adhesive profile needs to change, the shovels must be exchanged, which involves disconnecting the adhesive supply from the current shovel and connecting it to a new shovel. A team of operators are required to complete the adhesive deposition process, and to clear any mess caused by adhesive overspill, which often arises during shovel changeovers. The used shovels must also be cleaned thoroughly so that they are ready for subsequent use. The manual adhesive deposition process, including the necessary clean up operations, is a labour-intensive process and involves a considerable amount of time and cost.

It can be difficult to ensure a consistent and repeatable process using a manual method. There are a number of variables that can affect the process, for example the bulk density and viscosity of the adhesive may vary between production runs or between factories. Also, the adhesive supply machines in different factories may have vastly different supply rates. The supply rate of any given machine may also vary during the process. With these varying factors, it can be very challenging to deposit a consistent bead of adhesive using the manual method, and often there may be areas of excess adhesive or insufficient adhesive, which must then be corrected before the shear web can be bonded in place.

As the adhesive joints between the blade shells and the shear webs are critical to the structural integrity of the wind turbine blade, a more consistent and repeatable adhesive deposition process is required.

Against this background, the present invention has been developed.

Summary of the invention

The present invention provides a vehicle for dispensing adhesive on the surface of a wind turbine blade component.

The vehicle comprises: a drive system for moving the vehicle in a direction of travel on the surface of the wind turbine blade component; an adhesive shovel defining a channel extending from a front end facing the direction of travel to an open rear end facing away from the direction of travel, the channel being connected to a supply of adhesive and being configured to dispense a bead of adhesive behind the vehicle through the open rear end of the channel when the vehicle moves in the direction of travel; a sensor for determining a position of an adhesive flow front near the front end of the channel; and a controller configured to control the speed of the vehicle in the direction of travel.

The sensor is configured to send a signal to the controller indicative of the position of the adhesive flow front. The controller is configured to vary the speed of the vehicle in dependence upon position of the adhesive flow front.

The drive system preferably comprises drive means such as one or more motors connected to a plurality of wheels and/or tracks. In order to control the speed of the vehicle, i.e. to increase or decrease the speed of the vehicle, the controller preferably sends a drive signal to the drive system to vary the speed of the drive means.

The vehicle is preferably an autonomous vehicle. The vehicle preferably includes a plurality of sensors, cameras or other feedback means. The controller controls the movement of the vehicle, including the speed and/or position of the vehicle, and/or other aspects of the adhesive dispensing process, based upon feedback from the one or more sensors, cameras or other feedback means. The controller may be a single controller or a plurality of controllers, for example a main controller and one or more other controllers associated with sub-systems of the vehicle.

The controller is configured to increase the speed of the vehicle when the position of the adhesive flow front exceeds a predefined maximum position and/or decrease the speed of the vehicle when the position of the adhesive flow front decreases below a predefined minimum position.

The position of the adhesive flow front may be a position of the adhesive flow front measured relative to the vehicle and/or measured relative to the surface of the component on which the adhesive is dispensed. For example, the position may be the height of the adhesive flow front above the surface of the component or the height or position of the adhesive flow front within the front end of the channel. The sensor may be any suitable sensor, which may include a camera. Preferably the sensor is a contactless sensor selected from an ultrasonic sensor or an optical sensor such as laser sensor.

The sensor is preferably located ahead of the adhesive flow front and faces rearwards such that it is directed towards the adhesive flow front. The sensor is preferably positioned above the adhesive flow front and is preferably downwardly inclined such that is directed towards the adhesive flow front.

The sensor is preferably a distance sensor. The sensor preferably is configured to measure a distance between the sensor and the adhesive flow front. The sensor may send a signal indicative of the measured distance to the controller.

The controller is preferably configured to decrease the speed of the vehicle when the measured distance exceeds a predefined maximum distance and/or increase the speed of the vehicle when the measured distance decreases below a predefined minimum distance.

The vehicle may further include a plurality of adhesive profiling cards. Each card has an aperture shaped to define an adhesive profile. Each adhesive profiling card is preferably moveable between a deployed position and a retracted position. The bead of adhesive is extruded through the aperture of an adhesive profiling card in a deployed position when the vehicle moves in the direction of travel. The apertures of the respective adhesive profiling cards preferably have different profiles. However, it may also be the case that two or more adhesive profiling cards have the same profile. The vehicle preferably comprises a plurality of actuators for moving the respective adhesive profiling cards between retracted and deployed positions.

The plurality of adhesive profiling cards may be contained within a cartridge. The cartridge may be detachable from the vehicle such that the plurality of adhesive profiling cards can be removed from the vehicle and exchanged as a single unit.

The controller may be configured to deploy different adhesive profiling cards at different predefined locations on the surface of the wind turbine component. The controller may receive positional feedback from one or more sensors or cameras, for example servo encoders or references marks detected by a sensor or camera of the vehicle. The controller may determine when to deploy an adhesive profiling card based upon this positional feedback.

The vehicle may include an evaluation system for verifying the quality of the dispensed adhesive bead. The evaluation system may comprise a camera or other suitable sensor such as a laser scanner mounted on the vehicle, the sensor being configured to monitor the adhesive bead dispensed behind the vehicle such as measuring the profile in plane perpendicular or substantially perpendicular to the plane of the surface of the blade component and perpendicular or substantially perpendicular to the driving direction of the vehicle. Alternatively, the sensor may be a 3D laser scanner capable of generating a full 3D scan of the surface of a portion of the adhesive bead. The evaluation system may further be configured to compare the profile of the dispensed adhesive to a designed bead profile for the adhesive bead, for example a CAD design. If any differences exist between the dispensed adhesive bead and the designed bead profile, then these may be registered as error or flagged for inspection. The sensor determined profile may be available as a function of the vehicle’s position on the blade so that an error includes information about the location of the faulty bead profile.

Expressed in more concise terms, the invention provides a vehicle for dispensing adhesive on the surface of a wind turbine blade component. The vehicle comprises a drive system for moving the vehicle in a direction of travel on the surface of the wind turbine blade component. The vehicle also comprises an adhesive shovel connected to a supply of adhesive. The shovel is configured to dispense a bead of adhesive behind the vehicle when the vehicle moves in the direction of travel. The vehicle includes a sensor for determining a position of an adhesive flow front near a front end of the shovel. A controller of the vehicle is configured to control the speed of the vehicle in the direction of travel in dependence upon the monitored position of the adhesive flow front.

The present invention also provides a method of dispensing adhesive on the surface of a wind turbine blade component. The method comprises: providing a vehicle having an adhesive shovel defining a channel extending between a front end and an open rear end; moving the vehicle in a direction of travel along the surface of the wind turbine blade component; supplying adhesive to the channel and dispensing a bead of adhesive behind the vehicle through the open rear end of the channel; monitoring a position of an adhesive flow front near the front end of the channel using a sensor; and varying the speed of the vehicle in dependence upon the monitored position of the adhesive flow front.

Varying the speed of the vehicle may comprise increasing the speed of the vehicle when the position of the adhesive flow front exceeds a predefined maximum position and/or decreasing the speed of the vehicle when the position of the adhesive flow front decreases below a predefined minimum position.

The sensor may be configured to measure a distance between the sensor and the adhesive flow front. In this case, varying the speed of the vehicle may comprise decreasing the speed of the vehicle when the measured distance exceeds a predefined maximum distance and/or increasing the speed of the vehicle when the measured distance decreases below a predefined minimum distance.

As discussed above, the vehicle may comprise a plurality of adhesive profiling cards. Each adhesive profiling card may define an aperture having a unique profile. The adhesive profiling cards are preferably moveable between a deployed position and a retracted position. The method may further comprise deploying a first adhesive profiling card; extruding the bead of adhesive through the aperture of the deployed first adhesive profiling card as the vehicle moves in a first region of the wind turbine blade component; retracting the first adhesive profiling card and deploying a second adhesive profiling card at a predefined location on the wind turbine blade component; and extruding the bead of adhesive through the aperture of the deployed second adhesive profiling card in a second region of the wind turbine blade component, such that the bead of adhesive has a different profile in the first and second regions of the wind turbine component.

The method preferably comprises exchanging the adhesive profiling cards whilst the vehicle is moving in the direction of travel such that the bead of adhesive is continuous and of varying profile along its length.

The wind turbine blade component discussed above may be a shell of a wind turbine blade. In this case, the vehicle moves along an inner surface of the blade shell. The vehicle preferably dispenses a bead of adhesive to be used for bonding a shear web to the blade shell. The vehicle may also be used for dispensing adhesive on other suitable components, for example on reinforcing structures for a wind turbine blade such as on the shear web or pultrusions such as a T-pultrusion. It will be appreciated that optional features described above in relation to the vehicle are equally applicable to the method and vice versa. Repetition of such features has been avoided purely for reasons of conciseness.

Brief description of the drawings

Embodiments of the invention will now be described, by way of non-limiting example, with reference to the following figures, in which:

Figure 1 is a front perspective view of a vehicle for dispensing adhesive according to an embodiment of the present invention;

Figure 2 is a front perspective view of the vehicle with a set of wheels omitted to reveal an adhesive shovel;

Figure 3 is a partially transparent perspective view of the adhesive shovel in isolation;

Figure 4 is a schematic rear perspective view of the vehicle in use dispensing a bead of adhesive on to a surface of a wind turbine blade shell; and

Figure 5 is a schematic side view of the adhesive shovel in use showing a sensor measuring a distance to an adhesive flow front near a front end of the adhesive shovel.

Detailed description

Figure 1 shows a vehicle 10 for dispensing adhesive according to an embodiment of the present invention. The vehicle 10 in this example is a twin track skid steer rover. The vehicle 10 comprises a main chassis 12 supporting a drive system. The main chassis 12 in this example is generally U-shaped in cross-section. The drive system comprises a plurality of wheels 14 surrounded by continuous tracks 16. The wheels 14 are mounted to the sides of the U-shaped chassis 12. The drive system further comprises drive motors 18 (one of which is visible in Figure 1) for driving the wheels 14. Each drive motor 18 is connected to a respective set of wheels 14 via a gearbox 20 (one of which is visible in Figure 1). The drive system in this example includes servo encoders (not shown), which may be configured to detect the rotational angle, speed, and/or travel distance of the drive motors 18. The servo encoders send this information to a main controller 22 of the vehicle 10, which is programmed to determine the position of the vehicle 10 along a predefined adhesive deposition path based upon these signals. The main controller 22 also receives signals from various other sensors located on or around the vehicle 10, and these signals are used to control the speed and/or operation of the vehicle 10, as will be discussed in more detail in the following description.

The vehicle 10 includes a position detection system. In this example, the position detection system includes an array 24 of light dependent resistors (LDR). The LDR array 24 is mounted on an upper surface 26 of the chassis 12 and faces upwards in this example. The LDR array 24 is also connected to the main controller 22 and is also used to control the position of the vehicle 10, as discussed in further detail later.

A lifting eye 28 is shown mounted to an upper surface of the chassis 12 allowing the vehicle 10 to be lifted and positioned in the required location, for example inside a wind turbine blade shell. An umbilical connector 30 is also provided at the upper surface 26 of the chassis 12 allowing optional data connection or external power connection to the vehicle 10. The vehicle 10 is preferably powered by an on-board power source, such as a battery (not shown). A rigid pipe 32 extends upwardly from the upper surface 26 of the chassis 12. In use, an adhesive supply line (not shown) is fed through this pipe 32.

As shown in Figure 2, which shows the vehicle 10 with one set of wheels and track omitted, the vehicle 10 further comprises an adhesive shovel 34. The adhesive shovel 34 is positioned between the sides of the U-shaped chassis 12, beneath the upper surface 26. As will be described in further detail later, the adhesive shovel 34 is supplied with adhesive in use, and dispenses a bead of adhesive 35 (shown in Figure 4) behind the vehicle 10, on the surface of a component (e.g. a wind turbine blade shell or other blade shell component), as the vehicle 10 moves. The adhesive shovel 34 will be described in further detail later, with reference to Figure 3.

Referring still to Figure 2, the vehicle 10 also includes a sensor 36 for monitoring the position of an adhesive flow front 38 (shown in Figure 5) within the adhesive shovel 34. The sensor 36 in this example is an ultrasonic sensor for measuring distance, but other sensors may be used, such as an optical sensor, e.g. a laser. The sensor 36 is mounted beneath the upper surface 26 of the chassis 12 in front of the adhesive shovel 34. The sensor 36 faces rearwards and is downwardly inclined such that it is directed towards a front end 40 of the adhesive shovel 34. The sensor 36 is connected to the main controller 22 and is used to control the speed of the vehicle 10 in dependence on a position of the adhesive flow front 38 as will be discussed in more detail later.

Referring now to Figure 3, this shows the adhesive shovel 34 in isolation. The adhesive shovel 34 comprises a channel 42, which is elongate in this example. The channel 42 extends between a front end 40 and a rear end 41. The front end 40 faces forwards, towards the front of the vehicle 10, i.e. in a direction of travel of the vehicle 10, and the rear end 41 faces backwards. The front end 40 is an open end in this example. The rear end is also an open end, although this is not visible in Figure 3. The channel 42 includes a pair of mutually-opposed sidewalls 44, extending between the front and rear ends 40, 41 of the channel 42. The side walls 44 are connected together by a roof 46. The sidewalls 44 extend beyond the roof 46 in a front end portion 48 of the channel 42. Accordingly, an open window 50 is defined in the front end portion 48 of the channel 42 where the roof 46 is not present. In this example, the sidewalls 44 taper in height towards the front end 40 of the channel 42. Accordingly, the height of the channel 42 decreases towards the front end 40. The channel 42 has an open bottom, and the lower edges of the sidewalls 44 contact the surface of the component on which the vehicle 10 moves when in use. Accordingly, in use, the channel 42 defines an adhesive confinement region 51 (shown in Figure 5) between the sidewalls 44, roof 46 and the surface of the component on which the vehicle 10 travels, e.g. a blade shell surface.

The roof 46 of the channel 42 is provided with a connector 52 configured to be connected to an adhesive supply line (not shown). The adhesive supply line is fed through the pipe 32 shown in Figure 1. The connector 52 in this example includes a magnetic coupler 54 which facilitates the connection process. In use, the end of the adhesive supply line is simply offered up to the magnetic coupler 54 and the two parts become connected together magnetically. In use, the adhesive supply line provides a continuous supply of adhesive, from a remotely-located adhesive supply machine, to the adhesive confinement region 51 of the channel 42.

In this example, a plurality of adhesive profiling cards 56a, 56b, 56c are provided at a rear end portion 58 of the channel 42. The adhesive profiling cards 56 each include an aperture 60 having a profile that defines a cross-sectional profile of an adhesive bead 35 (shown in Figure 4) dispensed by the vehicle 10 in use. The adhesive profiling cards 56 are each movable between deployed and retracted positions. In this example, a first adhesive profiling card 56a is shown in a deployed position, whilst the remaining adhesive profiling cards 56b, 56c are retracted. When deployed, i.e. in the deployed position, the adhesive profiling cards 56 act as a bulkhead within the rear end portion 58 of the channel 42, and adhesive is extruded through the aperture 60 of the deployed adhesive profiling card 56a when the vehicle 10 moves forward.

The extruded bead of adhesive 35 (shown for example in Fig. 4) adopts the cross- sectional profile of the aperture 60. In this example, the aperture 60 of the deployed first adhesive profiling card is “house-shaped”. The resulting adhesive bead 35 extruded through this aperture 60 will therefore have a house-shaped profile. The adhesive profiling cards 56 may have different profiles, i.e. different shapes and/or sizes. This makes it possible to vary the profile of the adhesive bead 35 that is dispensed by retracting certain cards 56 and deploying other cards 56. Accordingly, it is possible to dispense a continuous bead of adhesive 35 having a profile that varies along its length.

In some cases, two or more adhesive profiling cards 56 may have the same profile. This provides a level of redundancy and may be useful in case an adhesive profiling card 56 becomes stuck or clogged, in which case a back-up card defining the same profile may be deployed.

In this example, the adhesive profiling cards 56 are movable up and down between retracted and deployed positions. The profiling cards 56 are lifted into their retracted positions and lowered into their deployed positions. In other examples, the adhesive profiling cards 56 could be moved sideways or in another way. A plurality of actuators 62 are used to drive the movement of the adhesive profiling cards 56. In this example, a plurality of linear actuators are connected above the adhesive profiling cards 56. The actuators 62 are each connected to the main controller 22, which sends a signal to the actuators 62 to move the relevant adhesive profiling cards 56 into their deployed or retracted positions, as required, during operation of the vehicle 10.

In this example, the plurality of adhesive profiling cards 56 are contained within a cartridge 64 that is readily detachable from the vehicle 10. This allows the profiling cards 56 to be removed and exchanged with another set of cards as a single unit. This may be done, for example, between production runs, or between each deposition process. The profiling cards 56 may be stamped from sheet material or 3D printed. Accordingly, they can be mass-produced inexpensively and may be considered to be disposable or consumable items. This substantially eliminates the clean-up process, and therefore saves significant time and cost in comparison to the manual adhesive deposition method described by way of background.

Operation of the vehicle 10 in use will now be described, by way of non-limiting example only, with reference to the remaining figures.

Referring to Figure 4, this schematically shows the vehicle 10 dispensing a continuous bead of adhesive on an inner surface 65 of a wind turbine blade shell 66. This figure is not to scale and the vehicle 10 is enlarged relative to the blade shell 66 for illustrative purposes. The wind turbine blade shell 66 extends longitudinally between a root end and a tip end, although only a small section of the shell is represented in Figure 4. The blade shell 66 extends in a chordwise direction C between a leading edge flange 68 and a trailing edge flange 70. The shell 66 has concave curvature between the leading and trailing edge flanges 68, 70.

A laser projection system 72 is located above the blade shell 66. The laser projection system 72 projects a laser line 74 on the inner surface 65 of the blade shell 66 in a position where a shear web (not shown) will be bonded. This line 74 also represents the position where the adhesive bead 35 needs to be deposited, as the adhesive bead 35 in this example will be used to bond the shear web to the blade shell 66.

The vehicle 10 is initially lifted into the blade shell 66 and positioned on the inner surface 65 of the blade shell 66. The vehicle 10 is placed on the laser line 74 such that the laser line 74 projects onto the LDR array 24 on the top of the vehicle 10. An adhesive supply line 76 is fed through the rigid pipe 32 and connected to the adhesive shovel 34 via the connector 52 shown in Figure 3. The vehicle 10 is then set to move in a direction of travel represented by the arrow 78 in Figure 4.

As the vehicle 10 moves in the direction of travel 78, it dispenses a bead of adhesive 35 behind it. The LDR array 24 monitors the chordwise position of the vehicle 10 relative to the overhead laser 72 and sends a signal indicative of this position to the controller 22. If the vehicle 10 begins to deviate from the laser line 74, then the controller 22 will adjust the speed of one or both drive motors 18 to steer the vehicle 10 back on course. The system is capable of making very fine adjustments such that any deviations from the required course will be very minimal.

Referring now to Figure 5, this schematically shows the adhesive shovel 34 in use when adhesive 80 is supplied to the channel 42 and the adhesive shovel 34 is moving in the direction of travel indicated by the arrow 78. The adhesive 80 is supplied to the channel 42 at a positive pressure. The adhesive 80 fills the adhesive confinement region 51 defined between the sidewalls 44 and roof 46 of the channel 42 and the surface 65 of the blade shell 66. Hydraulic pressure builds within the channel 42 and the forward velocity of the vehicle 10 causes the bead of adhesive 35 to be extruded through the aperture 60 in the adhesive profiling card 56 in the rear end portion 58 of the channel 42.

Due to the positive hydraulic pressure of the adhesive entering the channel 42, there will also be some overflow of adhesive 80 near the front end 40 of the channel 42. This overflow of adhesive 80 near the front end 40 of the channel 42 forms an adhesive flow front 38, which is also referred to herein as “heaving”. Ideally the adhesive flow front 38 (heaving) is contained within the front end portion 48 of the channel 42, between the tapering side walls. As such, the adhesive flow front will normally be visible through the window in the front end portion 48 of the channel 42. In some circumstances, the adhesive flow front 38 may extend slightly beyond the front end 40 of the channel 42.

The amount of heaving that occurs depends on a number of factors. These include the bulk density and viscosity of the adhesive 80, the rate at which adhesive 80 is supplied to the shovel 34, and the speed at which the shovel 34 is moved in the direction of travel 78.

It has been discovered as part of the present invention that there is a correlation between this heaving and the quality and consistency of the adhesive bead 35 that is dispensed by the adhesive shovel 34. If heaving is too great, then the adhesive flow front 38 will bulge excessively at the front end 40 of the channel 42 and may overspill the sidewalls 44 of the channel 42, resulting in excess adhesive 80 being deposited on the blade shell 66 that will need to be removed. Conversely, too little heaving may result in too little adhesive 80 being extruded and the dispensed adhesive bead 35 may not have the required profile, which again may need to be corrected. It has been recognised that, if the adhesive heaving can be controlled within defined limits, then high quality and consistent adhesive beads 35 may be created. In order to control the adhesive heaving, the sensor 36 (in this example the ultrasonic sensor described previously) is configured to determine a position of the adhesive flow front 38 near the front end 40 of the channel 42 as the vehicle 10 moves in the direction of travel 78. The sensor 36 sends a signal to the controller 22 indicative of the position of the adhesive flow front 38. In response, the controller 22 varies the speed of the vehicle 10 in dependence on the monitored position of the adhesive flow front 38 to maintain the position of the adhesive flow front 38 within predefined limits 81.

In this example, and as shown in Figure 5, the sensor 36 is configured to measure a distance dff between the sensor 36 and the adhesive flow front 38 near the front end 40 of the channel 42. The sensor 36 communicates a signal indicative of this distance dff to the main controller 22. If the monitored distance dff becomes too small, then this is indicative of excessive heaving, i.e. the flow front 38 is bulging too much in the front end portion 48 of the channel 42, which may be liable to cause an overflow of adhesive 80 at the front of the shovel 34. Conversely, if the monitored distance dff is too great, then this indicates insufficient heaving, i.e. the flow front 38 has receded too far within the channel 42, which may result in insufficient adhesive 80 being dispensed behind the vehicle 10.

In order to ensure the required amount of heaving, upper and lower limits for the monitored distance dff may be predefined in the main controller 22. These limits correspond to an optimal range for the adhesive heave.

If the monitored distance d_ff decreases below a predefined minimum distance, this indicates that the adhesive heaving is too great, i.e. that the flow front 38 is bulging too much at the front of the channel 42. In response to this, the main controller 22 increases the speed of the vehicle 10, e.g. by sending a control signal to the drive motors 18. Increasing the speed of the vehicle 10 causes adhesive 80 to be extruded from the rear of the channel 42 at a faster rate and consequently causes the flow front 38 or heaving to diminish.

Conversely, if the monitored distance dff increases above a predefined maximum distance, then this indicates that the adhesive heaving is too little, i.e. the flow front 38 has decremented too much at the front of the channel 42. In response to this, the main controller 22 decreases the speed of the vehicle 10, e.g. by sending a control signal to the drive motors 18. Decreasing the speed of the vehicle 10 causes adhesive 80 to be extruded from the rear of the channel 42 at a slower rate and allows the channel 42 to refill with adhesive 80 and the adhesive heaving near the front of the channel to increase again towards its optimal size.

The sensor 36, main controller 22 and drive system together form a feedback control system that controls the speed of the vehicle 10 to maintain an optimal level of adhesive heaving. Adhesive heaving, i.e. the position of the adhesive flow front 38, is used as the control variable to control the speed of the vehicle 10.

The sensor 36 in this example is orientated such that it faces towards the window 50 in the front end portion 48 of the channel 42. However, in other embodiments the sensor 36 may be orientated differently provided that it can see the adhesive flow front 38 and determine its position relative to the vehicle 10 and/or its position relative to the surface 65. Whilst the sensor 36 in this example measures the distance dff between the sensor 36 and the adhesive flow front 38, a different measurement may be taken in other examples, provided that it is indicative of the position of the flow front 38, and hence indicative of the extent of adhesive heaving. For example, the sensor 36 may be arranged to measure a distance between the flow front 38 and another fixed reference point on the vehicle 10 or surface 65 of the component.

Controlling the speed of the vehicle 10 based upon adhesive heaving is particularly advantageous because it eliminates the need to control other variables such as the adhesive supply rate, bulk density and viscosity of the adhesive. The vehicle 10 may be supplied with any suitable type of adhesive or other paste at any suitable rate, and the speed of the vehicle 10 automatically adjusts to ensure a consistent bead of adhesive 35 is dispensed. This allows the vehicle 10 to be plugged into any adhesive supply machine and the vehicle 10 speed will automatically adjust itself to ensure a consistent bead of adhesive 35 is dispensed.

Figure 5 shows a first adhesive profiling card 56a in a deployed position. Accordingly, as the vehicle 10 moves in the direction of travel 78, the adhesive bead 35 is extruded onto the surface 65 of the component, in this example a wind turbine blade shell 66, through the aperture 60 in the first adhesive profiling card 56a. The main controller 22 is programmed to deploy different adhesive profiling cards 56 at different predetermined locations on the surface 65 of the component 66. In the case of a wind turbine blade shell 66, where the adhesive bead 35 is used for bonding a shear web, the required adhesive profile may change at one or more radial locations along the blade shell 66. These locations may be programmed within the main controller 22. The main controller 22 may receive signals from the servo encoders of the drive system from which the main controller 22 can determine the radial location of the vehicle 10 at any point.

When the vehicle 10 reaches a predetermined radial location at which the adhesive profile needs to change, the main controller 22 may send a signal to the actuator 62 connected to the first adhesive profiling card 56a instructing the actuator 62 to retract the first adhesive profiling card 56a. The main controller 22 may also send a signal to another actuator connected to the second adhesive profiling card 56b instructing that actuator to deploy the second adhesive profiling card 56b.

This process may occur whilst the vehicle 10 moves continuously in the direction of travel 76 such that there is no interruption to the adhesive deposition process when varying the adhesive profile. This is a significant advantage over the manual adhesive deposition process described by way of background, where changes in the adhesive profile required suspending the adhesive deposition process to change adhesive shovels, and the associated requirement to disconnect the adhesive supply from one shovel and connect it to another shovel. The adhesive deposition process using the vehicle 10 is therefore significantly faster than prior art techniques and does not require a team of operators.

The vehicle 10 may also be equipped with an evaluation system for verifying the quality of the dispensed adhesive bead 35 and detecting any errors. In this example, the evaluation system comprises a camera 82 mounted to the rear of the chassis 12, as shown schematically in Figure 5. The camera may be a 3D laser line CMOS camera. The evaluation system measures the profile of the dispensed adhesive bead 35 and compares it to the CAD geometry of a designed profile for the adhesive bead 35. Any deviations between the geometry of the dispensed adhesive and the CAD design may be registered by the main controller 22. The vehicle 10 may report errors to an operator so that the relevant part of the adhesive bead 35 can be inspected and corrected if required.

Many modifications may be made to the specific examples described above without departing from the scope of the present invention as defined in the following claims. For example, whilst the above examples describe adhesive being deposited onto a wind turbine blade shell 66, the vehicle 10 may be used to deposit adhesive onto other wind turbine blade components, for example reinforcing structures of the blade, e.g. spars, spar caps, shear webs etc.

Claims

1. A vehicle for dispensing adhesive on the surface of a wind turbine blade component, the vehicle comprising: a drive system for moving the vehicle in a direction of travel on the surface of the wind turbine blade component; an adhesive shovel defining a channel extending from a front end facing the direction of travel to an open rear end facing away from the direction of travel, the channel being connected to a supply of adhesive and being configured to dispense a bead of adhesive behind the vehicle through the open rear end of the channel when the vehicle moves in the direction of travel; a sensor for determining a position of an adhesive flow front near the front end of the channel; and a controller configured to control the speed of the vehicle in the direction of travel, wherein the sensor is configured to send a signal to the controller indicative of the position of the adhesive flow front and the controller is configured to vary the speed of the vehicle in dependence on the position of the adhesive flow front.

2. The vehicle of Claim 1 , wherein the controller is configured to increase the speed of the vehicle when the position of the adhesive flow front exceeds a predefined maximum position and/or decrease the speed of the vehicle when the position of the adhesive flow front decreases below a predefined minimum position.

3. The vehicle of Claim 1 or Claim 2, wherein the sensor is configured to measure a distance between the sensor and the adhesive flow front and send a signal indicative of the measured distance to the controller.

4. The vehicle of Claim 3, wherein the controller is configured to decrease the speed of the vehicle when the measured distance exceeds a predefined maximum distance and/or increase the speed of the vehicle when the measured distance decreases below a predefined minimum distance.

5. The vehicle of any preceding claim, wherein the sensor is located ahead of the adhesive flow front facing rearwards such that it is directed towards the adhesive flow front.

6. The vehicle of any preceding claim, wherein the sensor is a contactless sensor selected from an ultrasonic sensor or an optical sensor such as laser sensor.

7. The vehicle of any preceding claim, further comprising a plurality of adhesive profiling cards each having an aperture shaped to define an adhesive profile, each adhesive profiling card being moveable between a deployed position and a retracted position, wherein the bead of adhesive is extruded through the aperture of an adhesive profiling card in a deployed position when the vehicle moves in the direction of travel.

8. The vehicle of Claim 7, wherein the apertures of the respective adhesive profiling cards have different profiles.

9. The vehicle of Claim 7 or Claim 8, further comprising a plurality of actuators for moving the respective adhesive profiling cards between retracted and deployed positions.

10. The vehicle of any of Claims 7 to 9, wherein the plurality of adhesive profiling cards are contained within a cartridge that is detachable from the vehicle such that the plurality of adhesive profiling cards can be removed from the vehicle and exchanged as a single unit.

11. The vehicle of any of Claims 7 to 10, wherein the controller is configured to deploy different adhesive profiling cards at different predefined locations on the surface of the wind turbine component.

12. The vehicle of any preceding claim, further comprising an evaluation system for verifying the quality of the dispensed adhesive bead, wherein the evaluation system comprises a camera mounted on the vehicle, the camera being configured to monitor the adhesive bead dispensed behind the vehicle.

13. A method of dispensing adhesive on the surface of a wind turbine blade component, the method comprising: providing a vehicle having an adhesive shovel defining a channel extending between a front end and an open rear end; moving the vehicle in a direction of travel along the surface of the wind turbine blade component; supplying adhesive to the channel and dispensing a bead of adhesive behind the vehicle through the open rear end of the channel; monitoring a position of an adhesive flow front near the front end of the channel using a sensor; and varying the speed of the vehicle in dependence upon the monitored position of the adhesive flow front.

14. The method of Claim 13, wherein varying the speed of the vehicle comprises increasing the speed of the vehicle when the position of the adhesive flow front exceeds a predefined maximum position and/or decreasing the speed of the vehicle when the position of the adhesive flow front decreases below a predefined minimum position.

15. The method of Claim 13 or 14, wherein the sensor is configured to measure a distance between the sensor and the adhesive flow front and varying the speed of the vehicle comprises decreasing the speed of the vehicle when the measured distance exceeds a predefined maximum distance and/or increasing the speed of the vehicle when the measured distance decreases below a predefined minimum distance.