WO2012072085A1

WO2012072085A1 - Plant for surface treatment of a windmill blade

Info

Publication number: WO2012072085A1
Application number: PCT/DK2011/050457
Authority: WO
Inventors: Poul Erik Jespersen
Original assignee: Flex Trim A/S
Priority date: 2010-12-01
Filing date: 2011-12-01
Publication date: 2012-06-07
Also published as: DK177220B1

Abstract

A plant for surface treatment of a windmill blade (8) with its longitudinal axis (9) disposed largely horizontally. The plant includes a processing unit (2) for performing the desired surface treatment and a transport unit (1) for displacing the processing unit along and transversely to the longitudinal axis of the surface (10) in order to perform treatment of the surface. The transport unit includes a vehicle (1) with a support unit (3) supporting the processing unit (2). The processing unit includes at least one processing tool (11 ) for performing the surface treatment. The support unit (3) and/or the processing unit (2) are/is arranged for performing a movement transversely to the longitudinal axis of the surface in a way so that the processing tool (11) can be displaced across the entire surface (10) as the vehicle (1) travels along the surface, while at the same time the support unit and/or the treatment tool are/is displaced transversely to the surface by means of displacing means.

Description

PLANT FOR SURFACE TREATMENT OF A WINDMILL BLADE

Field of the Invention

The present invention concerns a plant for surface treatment of an item with an oblong surface, preferably the surface of a windmill blade, the longitudinal axis of which being disposed largely horizontally, the plant including a processing unit for performing the desired surface treatment and a transport unit for displacing the processing unit in direction along and across the longitudinal axis of the surface in order to perform the treatment of the surface, where the transport unit includes a vehicle with a support unit, where the processing unit is supported by the support unit of the vehicle, where the processing unit includes at least one processing tool, and where the support unit and/or the processing unit are arranged for performing a movement transversely to the longitudinal axis of the surface in a way so that the processing tool can be displaced across the entire surface.

The invention is specifically developed in connection with abrading/polishing the surface on windmill blades. However, a plant according to the invention may also be used in other kinds of surface treatment, for example sand blasting and painting elongated items, e.g. concrete elements or metal pipes. Background of the Invention

For polishing windmill blades, a so-called wing polisher made and marketed by Flex Trim A/S has been proposed. The wing polisher is based on abrading/polishing the windmill blade lying with a flat side oriented largely horizontally and according to a principle known from grinding/polishing of floors. However, increasingly it is desired to place the blades with the flat side standing vertically. Therefore, it is not possible readily to use the wing polisher which is based on the fact that the force of gravity produces contact pressure.

It has therefore also been suggested to use hand polishing. This is however a slow and tedious procedure in the case of large windmill blades. It has also been suggested to use a portal polisher which in principle has the same movement pattern as a car washing machine, as a portal supporting processing units/tools for abrading/polishing is displaced back and forth over a windmill blade in that the portal runs on rails. However, this construction is space consuming and puts demands on the foundation in order that the rails can bear the portal.

However, a long processing time will result as the windmill blade which has been polished is to be released and then taken out of the plant before a new windmill blade can be introduced in the plant where it is to be placed correctly before securing. There is thus a long changeover time between successive treatments, resulting in reduced utilisation of machine capacity.

Plants of the type indicated in the introduction are known from WO2004/108351 and EP 2 090 506. The first of these plants is, however, not suited for treating curving surfaces, and the second of these plants is a technically complicated unit requiring use of specially constructed robots for performing the treatment.

Object of the Invention

It is the purpose of the invention to indicate a plant of the type mentioned in the introduction which is technically simple and which can perform the surface treatment in a simple way, and where it is possible to achieve high utilisation of machine capacity by rapidly changing from treating one surface to a subsequent surface.

Description of the Invention

According to the present invention, this is achieved by an apparatus of the type mentioned in the introduction which is peculiar in that the processing tool includes at least one rotating abrading or polishing cylinder which at its cylinder face is provided with radially oriented flexible abrasive lamellae or abrasive members with abrasive lamellae oriented axially but with their longitudinal direction radially relative to a support member for performing the surface treatment with adaptation to various curvatures/surface structures on the item, as the vehicle travels along the surface while at the same time the support unit and/or the processing tool are/is displaced transversely to the surface by means of displacing means. A rotary abrading or polishing cylinder is known from surface treatment of wood, metal and composite structures, as e.g. windmill blades. The radially oriented flexible abrasive lamellae provide abrasion/polishing of the surface. The abrasive lamellae will usually be provided by slitting sandpaper supported by support brushes that ensure correct contact pressure. Alternatively, it is possible to use other kinds of processing tools, for example abrasive members with abrasive lamellae oriented axially but with their longitudinal direction radially on a support member.

As a vehicle is used for carrying the processing unit, it is possible to place a number of items on supports located on a firm base where the vehicle can travel along the item. When an item is finished, the vehicle can drive immediately to the next item and immediately begin surface treatment of the new item.

The plant can be used with various types of standard vehicles, such as trucks, tractors or lorries if only the vehicle has a support unit in the form of a lift tower, platform or similar. The surface treatment is effected in a simple way as the processing tool covers the entire surface during the simultaneous travel forward with the vehicle and displacement of the displacing means. Travel and displacement can take place continuously, with complete or partial overlapping of travel and displacement, or in sequences alternating with driving and displacement.

If using a vehicle such as a truck provided with a lifting device, the lifting device of the standard vehicle can be used for moving the processing unit in one direction. The processing unit can in such situation be a structure made up of movable slides/arms provided with processing tools. Besides the movement of the vehicle along an item and the movement of the lifting device in vertical direction, the processing tools can thus also perform a horizontal movement for adapting to various curvatures/surface structures on the item. If a vehicle is without a support unit, the processing unit will be provided with movable slides/arms that enable displacement in vertical as well as horizontal direction. Such a plant can perform a movement along the item in its longitudinal direction simultaneously with displacement vertically and horizontally in order to cover the item. The plant is adapted such that the processing unit provides guiding transversely of the surface while at the same time a guide can be displaced against and away from the surface for ensuring correct contact pressure of the processing unit against the surface or correct distance from the surface if the processing unit does not provide direct pressure on the surface.

Various processing tools can be used for surface treatment. These tools are displaced across the entire surface of the item by adapting the speed of travel along the item to the movement transversely to the item. Alternatively, it is also possible to perform the surface treatment by running the plant back and forth along the item.

Trucks are usually controlled by a joystick. Then it is an electro-hydraulic system where the hydraulic system (valve/pump) is activated by an electric signal. This electric signal can come from another point than from the joystick. This means that it is possible to couple the lifting/lowering function of the truck together with an external control unit used for controlling motors for the processing unit.

According to a further embodiment, the plant according to the invention is peculiar in that the vehicle is a forklift truck, and that the support unit is formed by the lift tower of the forklift truck and forks which can be elevated and lowered in a vertical plane, and that the processing unit is disposed on the forks, including a mounting frame with one or more guides oriented transversely to the travel direction of the forklift truck in a horizontal plane and supporting the processing tools. By using the forklift truck is achieved a particularly simple design as the lifting and lowering ability of the forklift truck with regard to the forks is utilised for moving the processing tools across the items. In the mounting frame there are guides which are oriented transversely to the driving direction of the forklift truck such that the processing tool or tools supported by the mounting frame can be moved in towards the item and follow a curving shape on an item, e.g. a windmill blade.

According to a further embodiment, the plant according to the invention is peculiar in that the vehicle includes a support unit in the form of a support structure which is fixed in height and which supports a processing unit including a mounting frame with guides which in a horizontal and vertical plane are oriented transversely of the vehicle, and which support the processing tool. By using a vehicle having a fixed support structure which is not adjustable in height, it will be necessary to have a processing unit where the mounting frame has guides in horizontal and vertical planes such that the processing tool can be moved across the surface of an item and at the same time follow various curvatures in the surface of the item.

According to a further embodiment, the plant according to the invention is peculiar in that the guides are linear guides that are displaced by means of spindle, toothed rack, toothed belt or similar transmission elements. By linear guides are achieved a technically simple solution and it is possible to use reliable transmission elements. Alternatively, it is possible to use a robot arm or similar where different arms are connected by joints which can be guided along the surface of the item. According to a further embodiment, the plant according to the invention is peculiar in that the processing tool includes sensors that detect the contact pressure on the surface and which are connected with the displacement means, and that a controller is adapted for regulating the contact pressure within desired intervals. In order to ensure correct working pressure on the surface and to ensure that the processing tool follows the contour of curving surfaces, the processing tool will include sensors. These sensors can detect contact pressure against the surface. As the sensors are connected to a control and the displacement means, it is possible to provide a control ensuring that the contact pressure is kept constant or within desired intervals all the time. Hereby it will be possible to establish a constant contact pressure irrespective whether the vehicle travels entirely in parallel with the item to be surface treated.

According to a further embodiment, the plant according to the invention is peculiar in that the displacing means include a motor provided with torque/power control which is separate for each processing unit or each processing tool. A motor provided with torque/power control will be a simple way of establishing displacement of the processing tools. It is preferred that each processing tool has its own motor. Alternatively, a processing unit containing several processing tools will also be provided with a motor simultaneously driving all processing tools in a processing unit.

It is preferred that the motor of the processing tools will follow the processing tools. However, alternatively it will be possible to provide the motor on the movable part and provide control and frequency converter and other parts on the part which is not moving, thereby just connecting them to the motor by a cable.

According to a further embodiment, the plant according to the invention is peculiar in that at the surface, preferably at each end, of the abrading or polishing cylinder there is provided spacing controlling discs safeguarding that the abrasive lamellae are not pressed too hard against the surface which is treated. By using the spacing controlling discs, there is achieved a particularly simple way of ensuring that the abrasive lamellae are never pressed too hard against the treated surface. The spacing controlling discs may thus be used in combination with the above mentioned control of the contact pressure. By dimensioning the dimension of the spacing controlling discs relative to the dimension of the radially oriented abrasive lamellae, it is ensured that a maximum contact pressure for the abrasive lamellae is never exceeded. Too hard pressure against the surface to be treated will thus never occur. The spacing controlling discs are made of a soft material which does not damage the surface, e.g. rubber or plastic.

According to a further embodiment, the plant according to the invention is peculiar in that the processing tool includes two abrading or polishing cylinders arranged for mutual counterrotation. Particularly when abrading windmill blades it is important that abrading or polishing cylinders that work beyond a leading edge and trailing edge in a way such that abrading is done away from the windmill blade. A processing tool with two abrading or polishing cylinders will thus be adapted so that the abrading or polishing cylinder which is moved beyond a leading or trailing edge is rotated in direction away from the windmill blade. It is possible to mount two abrading or polishing cylinders in separate guides. Alternatively, they can be placed in a common guide where the guide supports an arm which is pivotably suspended at its centre, and which at each end supports the abrading or polishing cylinders in a way. According to a further embodiment, the plant according to the invention is peculiar in that the processing unit includes a mounting frame which is U-shaped and includes at least two processing tools for performing the surface treatment of two oppositely directed surfaces at each side of an oblong item, preferably a windmill blade, and that the support unit and/or the processing unit are/is adapted for performing simultaneous movement of the processing tools at each side at mutually opposed positions. By a U- shaped frame it will be possible that processing tools are provided at each side of a narrow item, for example a windmill blade. In one run along the item it will hereby be possible to perform surface treatment of two opposing surfaces. By such a design is also achieved the advantage that there is no need for a special support in order to keep the item in a stable position. By the simultaneous surface treatment at both sides, a pressure arising in the lateral direction will be neutralised.

The motors and control of the plant are to be adapted to ensure the following functions:

Processing tool rotation at variable speed. There may be a separate motor per tool. A frequency converter/control can be individual or common to both tools.

The linear movement for the tool contact pressure against the item for each guide. In case of two tools/guides it is to be ensured that the two linear guides have constant speed. When using a separate motor per tool, the frequency converter/control can alternatively move the slides individually for each head.

The contact pressure against the item for each tool. This is effected by a separate motor per tool with frequency converter/control which is to regulate the contact pressure via torque/power control for each head individually. The motor/frequency converter/control can be the same as the one used for the above linear movement. If the item is oriented with a vertical surface to be treated, the movement of the processing tool up and down for displacement across the entire surface can occur in three ways:

Only by means of the lifting-lowering function of a truck

- Only by a lifting-lowering mechanism incorporated in the processing unit

A combination of the above two

The plant can be used on surfaces that are oriented largely vertically or largely horizontally or on surfaces that are curving.

As examples of applications in addition to windmill blades, surface treatment of trains and aircraft can be mentioned.

The vehicle can run along a train and have the processing units facing to the side of the vehicle and have processing units at ends of the guides.

The vehicle can drive under an aircraft and have the processing units facing upwards instead of laterally of the vehicle. Subsequently, the vehicle can drive at the side of the aircraft and have the processing units facing to the side of the vehicle. The plant is only to be adapted such that the guides are pivotable such that they provide a guiding transversely to the surface while simultaneously guides can be displaced against and away from the surface.

Description of the Drawing

The invention will now be explained more closely in the following with reference to the accompanying schematic drawing, where:

Fig. 1 shows a schematic view of a plant according to the invention, as seen from the side;

Fig. 2 shows an elementary sketch of a detail of the plant;

Fig. 3 shows a schematic view of a plant shown in Fig. 1 , as see from the front; Figs. 4-6show various embodiments of guides for the plant indicated in Fig. 1, and Fig. 7 shows a schematic view of a machining tool for the plant shown in Fig. 1. Detailed Description of the Invention

Fig. 1 shows a schematic view of a plant according to the invention in the form of a truck 1 supporting a processing unit 2. The truck 1 is provided with a support unit in the form of a lift tower 3 which can lift and lower forks 4 upon which the processing unit 2 is located. The truck is provided with wheels 5 running on a base 6 according to a driving direction 7. The truck may thus drive with a movement along an item in the form of a windmill wing 8, see Fig. 8, which is disposed with its longitudinal axis 9 largely horizontal corresponding to the surface 6. When the truck 1 runs in the driving direction 7 simultaneously with the lift tower displacing the processing unit up and down it will be possible for the processing tool (as will be explained in detail below) to perform a movement transversely to a surface 10 on the windmill wing 8 such that by the combined driving movement and elevating and lowering a surface treatment of the entire surface 10 is effected.

In Fig. 2 there is shown a partial view of the windmill wing 8 with the surface 10 treated by processing tools 11. Each of the two tools 11 are mounted in a linear guide 12 such that it can perform a reciprocating movement 13 oriented transversely to the driving direction 7 of the truck 1. The reciprocating movement will thus establish a contact pressure F,F' against the surface 10. The contact pressure may vary, depending on the position of the tools above the surface of the windmill wing which displays a curvature at the bottom as indicated at the bottom of Fig. 2. The contact pressures F,F' can be adjusted individually such as explained below. The guides 12 are provided in a mounting frame 14 which forms a part of the processing unit.

Fig. 3 shows a front view of the plant in Fig. 1. The truck 1 has the processing unit 2 suspended in the forks of the lift tower 3 such that the processing unit 2 can be moved in an up- and down-going movement in vertical plane as indicated by the double arrow 15. The guides 12 support each their tool 11. The tool 11 is provided by a grinding or polishing cylinder 16 (see Fig. 7) which at each of its ends is provided with spacing controlling discs 17. The spacing controlling discs 17 may simultaneously be used as sensors that detect the contact pressure F against the surface 10. These sensors can also be provided as separate sensors. The sensors will be connected with displacing means explained in the following, and a control which is adapted such that it is possible to regulate the contact pressure F within a desired interval.

Use of the spacing controlling discs 17 will furthermore prevent the abrading or polishing cylinder 16 from being pressed more closely to the surface 10 than allowable. Hereby, excessive abrasion/polishing on the surface is avoided. If the discs 17 are used for controlling the motors of the displacing means it will be the reactive force on the discs 17 which will be used for regulating the contact pressure F. Hereby, a particularly sure control is achieved. If alternatively the contact pressure directly on the tool was used for the control, there could be a risk of variation in the contact pressure.

Figs. 4, 5 and 6 show various embodiments of the linear guides. Fig. 4 shows a spindle 18. Fig. 5 shows a toothed rack 19. Fig. 6 shows a toothed belt 20. The guides 17 are connected with a motor 21 establishing the reciprocating movement 13 of the guide 12.

Each guide supports a processing tool 11 which is driven by a separate motor 22. A control is incorporated in the motors 21, adapted to regulate the contact pressure on the basis of the response transmitted from sensors detecting the contact pressure against the surface 10.

The motors 22 can be controlled individually for desired rotation of the processing tool 11.

The motors 21 are provided with torque/power control which is separate for each processing tool 11.

Fig. 7 shows a picture of the abrading or polishing cylinder 16 viewed from the side and from the end, respectively. It appears that the abrading or polishing cylinder has a cylinder surface 23 in which radially oriented flexible abrasive lamellae 24 are provided. The flexibility appears particularly clearly from the end view that shows how the rotating abrading or polishing cylinder rotates in direction of the arrow 25 such that the lamellae are bent backwards relative to the direction of rotation when they strike the surface 10. The abrading or polishing cylinder 16 have the spacing controlling discs 17 disposed at each end of the cylinder in order to ensure that the abrasive lamellae 24 are not pressed too hard against the surface 10. Moreover, the abrading or polishing cylinder 16 has a pulley 26 for connecting with the motor 22 and O-rings 27 at each end of the cylinder which ensures that the lamellae 24 are easily exchanged by axial displacement in axially running mounting grooves (not shown) in the cylinder surface 23. When the processing unit is provided with two abrading or polishing cylinders as indicated in Fig. 11 , these will be arranged for mutual counterrotation. When windmill wings 8 are abraded, it is important that the abrading or polishing cylinders rotate away from the upper and lower edges of the windmill wing. The upper will thus rotate with an upward direction of rotation as indicated by the arrow 28, and the lower with a direction of rotation downward at its contact with the surface 10 as indicated by the arrow 28.

As alternative to the shown embodiment, the truck in its lift tower can be provided with a U-shaped mounting frame that extends above an upper edge of the windmill wing. Hereby a laterally inversed processing unit can be provided at the opposite side of the windmill wing relative to the one at which the truck is driving. The U-shaped mounting frame may thus perform surface treatment on two oppositely directed surfaces 10 of the windmill wing. Hereby may be achieved a more rapid surface treatment with a simultaneous treatment of both flat sides of the windmill wing.

Claims

1. A plant for surface treatment of an item with an oblong surface, preferably the surface of a windmill blade, the longitudinal axis of which being disposed largely horizontally, the plant including a processing unit for performing the desired surface treatment and a transport unit for displacing the processing unit in direction along and across the longitudinal axis of the surface in order to perform the treatment of the surface, where the transport unit includes a vehicle with a support unit, where the processing unit is supported by the support unit of the vehicle, where the processing unit includes at least one processing tool, and where the support unit and/or the processing unit are arranged for performing a movement transversely to the longitudinal axis of the surface in a way so that the processing tool can be displaced across the entire surface, characterised in that the processing tool includes at least one rotating abrading or polishing cylinder which at its cylinder face is provided with radially oriented flexible abrasive lamellae or abrasive members with abrasive lamellae oriented axially but with their longitudinal direction radially relative to a support member for performing the surface treatment with adaptation to various curvatures/surface structures on the item, as the vehicle travels along the surface while at the same time the support unit and/or the processing tool are/is displaced transversely to the surface by means of displacing means.

2. Plant according to claim 1, characterised in that the vehicle is a forklift truck, and that the support unit is formed by the lift tower of the forklift truck and forks which can be elevated and lowered in a vertical plane, and that the processing unit is disposed on the forks, including a mounting frame with one or more guides oriented transversely to the forklift truck in a horizontal plane and supporting the processing tools.

3. Plant according to claim 1, characterised in that the vehicle includes a support unit in the form of a support structure which is fixed in height and which supports a processing unit including a mounting frame with guides which in a horizontal and vertical plane are oriented transversely of the vehicle, and which support processing tools.

4. Plant according to claim 2 or 3, characterised in that the guides are linear guides that are displaced by means of spindle, toothed rack, toothed belt or similar transmission elements.

5. Plant according to any preceding claim, characterised in that the processing tool includes sensors that detect the contact pressure on the surface and which are connected with the displacement means, and that a controller is adapted for regulating the contact pressure within desired intervals.

6. Plant according to any preceding claim, characterised in that the displacing means include a motor provided with torque/power control which is separate for each processing unit or each processing tool.

7. Plant according to any preceding claim, characterised in that at the surface, preferably at each end, of the abrading or polishing cylinder there is provided spacing controlling discs safeguarding that the abrasive lamellae are not pressed too hard against the surface which is treated.

8. Plant according to any preceding claim, characterised in that the processing tool includes two abrading or polishing cylinders arranged for mutual counterrotation.

9. Plant according to any preceding claim, characterised in that the processing unit includes a mounting frame which is U-shaped and includes at least two processing tools for performing the surface treatment of two oppositely directed surfaces at each side of an oblong item, preferably a windmill blade, and that the support unit and/or the processing unit are/is adapted for performing simultaneous movement of the processing tools at each side at mutually opposed positions.