Abstract:
An aligning tool in the field of wind turbines is provided. The aligning tool has a first and second section. The second section has an outside diameter tapering down in a direction away from the first section. The aligning tool is connected to a fastener and can easily catch a corresponding hole.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to European Patent Office application No. 12168844.4 EP filed May 22, 2012, the entire content of which is hereby incorporated herein by reference. 
     FIELD OF INVENTION 
     The present invention relates to an aligning tool in the field of wind turbines for aligning a hole with a fastener for insertion of the fastener into the hole. 
     BACKGROUND OF INVENTION 
     Generally, a wind turbine comprises a tower which is installed on a foundation. The foundation comprises a large number of bolts protruding upwards. These bolts have to fit through the same number of through-holes in one or more flanges of the tower. Due to the large number of bolts that need to be aligned with their corresponding through-holes, the installation of the tower on the foundation can be difficult and time-consuming. In the past, the installation required many small turns of the tower with respect to the foundation in order to align the bolts and the through-holes. 
     SUMMARY OF INVENTION 
     It is one objective of the present invention to provide an approach for easy alignment of a hole and a fastener in the field of wind turbines. 
     Accordingly, an aligning tool in the field of wind turbines for aligning a hole with a fastener for insertion of the fastener into the hole is provided. The aligning tool comprises a first section adapted for connecting to the fastener and a second section having an outside diameter tapering down in a direction away from the first section. 
     The second section thus has one end having a smaller outside diameter than the other end. Herein, “diameter” refers to the largest chord of a cross-section of the corresponding element (hole, fastener or aligning tool). The cross-section of the element may be circular, rectangular or square, for example. The smaller outside diameter is smaller than the inside diameter of the hole which the aligning tool aligns with the fastener. The end with the smaller outside diameter will thus easily catch the corresponding hole. For example, one or more of the bolts mentioned in the introductory section may each be fitted with an aligning tool in accordance with the invention in a first step. In a second step, the tower is installed, wherein one or more of the corresponding holes in the flange of the tower are caught by a corresponding aligning tool. When the tower is lowered in a third step, the increasing outside diameter of each aligning tool forces the corresponding holes to become more and more aligned with each corresponding bolt. As one or more of the holes become aligned with their corresponding bolts, the rest of the holes will then follow to fit the rest of the bolts. 
     According to an embodiment, the first section comprises a receptacle to receive the fastener. The receptacle may be formed as a plain sleeve. Preferably, the receptacle is configured so as to receive the fastener in a snug manner. 
     According to a further embodiment, the first section comprises an inner thread adapted to be screwed onto the fastener. Thus, the aligning tool can be connected to the fastener in an easy manner. Typically, the first section will be screwed only onto an end portion of the fastener. The inner thread may be formed on the inside of the receptacle to receive the fastener. 
     According to a further embodiment, the aligning tool comprises a geometry adapted to apply a torque for screwing the first section onto the fastener. This simplifies the mounting of the aligning tool on a corresponding fastener. 
     According to a further embodiment, the geometry is adapted to come into engagement with a wrench or screwdriver. In particular, the geometry may be adapted to fit with a socket wrench, a single-ended wrench, a flat-tip screwdriver or a Phillips screwdriver. 
     According to a further embodiment, the geometry is formed as a hexagon head. Thus, for example a socket wrench with a hexagon-shaped socket may be used for applying a torque to the hexagon head. 
     According to a further embodiment, the hexagon head forms an end of the second section pointing away from the first section. Thus, the hexagon head forms a tip of the aligning tool. 
     Further, a set in the field of wind turbines is provided. The set comprises a first part comprising at least one fastener, a second part comprising at least one hole and an aligning tool in accordance with the present invention, the aligning tool being adapted to align the at least one hole and the at least one fastener for insertion of the at least one fastener into the at least one hole. 
     The “field of wind turbines” presently also covers foundations of wind turbines as well as other objects attached to wind turbines. 
     According to an embodiment, the second section of the aligning tool has a first outside diameter corresponding to the inside diameter of the hole, and a second outside diameter smaller than the first outside diameter, the second section tapering down from the first to the second diameter. Typically, the second outside diameter of the second section is much smaller than the inside diameter of the hole. For example, the second outside diameter of the second section may be half or a third of the diameter of the hole, or smaller. 
     According to a further embodiment, the first part is a foundation of a wind turbine and the second part is a section of a tower of the wind turbine. Thus, the one or more aligning tools are used to connect the foundation to the tower. 
     According to a further embodiment, the first part is a first section of a tower of a wind turbine and the second part is a second section of the tower. Thus, in this embodiment, the one or more aligning tools are used to connect two sections of a tower to each other. 
     According to a further embodiment, the fastener is a bolt, a screw, a stud or a pin. Generally speaking, the fastener may or may not have an outer thread in that portion that the aligning tool is connected to for the alignment process. In the case where the fastener does not have an outside thread, the first section may comprise a sleeve which fits snugly onto the portion of the fastener not having an outer thread. According to another embodiment, the fastener has a first and second portion, the second portion having a smaller diameter than the first portion and, in one embodiment, an outer thread. The first section of the aligning tool is connected to the second portion. 
     According to a further embodiment, the foundation has at least one row of circularly arranged bolts and the first section of the tower has at least one row of circularly arranged holes, wherein at least one aligning tool is screwed onto a bolt. Typically, the first section will have an inside and an outside flange, each flange comprising a row of circularly arranged holes. In this case, the foundation is also provided with two rows of circularly arranged bolts fitting to the first and the second row of holes, respectively. Two or more aligning tools may typically be used. 
     Further, a use of an aligning tool according to the present invention is provided for aligning a hole and a fastener for insertion of the fastener into the hole in the field of wind turbines. 
     Also, a method for assembling a wind turbine is provided, wherein a hole and a fastener are aligned for insertion of the fastener into the hole using an aligning tool in accordance with the invention. 
     For example, a tower of a wind turbine may be connected to a foundation of the wind turbine using the method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects, features and advantages of the present invention will become apparent from the subsequent description and depending claims, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective, partial view of a wind turbine tower being mounted to a foundation according to a first step in one embodiment; 
         FIG. 2  illustrates in a perspective view an aligning tool from  FIG. 1 ; 
         FIGS. 3 and 4  are perspective views of the tower and foundation from  FIG. 1  according to a second and third step. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     In the Figures, like reference numerals designate like or functionally equivalents elements, unless otherwise indicated. 
       FIG. 1  shows in a perspective, partial view a wind turbine  1  being assembled.  FIG. 1  shows a first step. 
     The wind turbine  1  comprises a first part in the form of a foundation  2  and a second part in the form of a tower  3 . 
     The foundation  2  comprises an inner row  4  and an outer row  5  of fasteners in the form of bolts  6 . In fact,  FIG. 1  only shows a threaded shank  7  of each bolt  6  sticking out upwards from a concrete body  11  of the foundation  2 . 
     A number of aligning tools  12  are provided. Each aligning tool  12  is attached to a respective bolt  6 . For example, an aligning tool  12  may be attached to every tenth bolt of the outer row  5 . The foundation  2 , the tower  3  and the aligning tools  12  form together a set  10 . 
     The tower  3  comprises an outer flange  13  at its lower end. Also, the tower  3  comprises an inner flange which is however not shown in  FIG. 1 . 
     The outer flange  13  has a row  14  of holes  15 , each hole  15  corresponding to a bolt  6  in the outer row  5  of the foundation  2 . The holes  15  are formed as through-holes. Likewise, the inner flange (not shown) comprises a row of holes, each hole corresponding to a bolt  6  in the inner row  4  of the foundation  2 . 
       FIG. 2  is a perspective view of one of the aligning tools  12  from  FIG. 1 . 
     The aligning tool  12  comprises a first section  16  adapted for connecting to a threaded shank  7  of a bolt  6 . To this end, the first section  16  has a sleeve-shaped receptacle  17 , comprising an inner thread  21 . The inner thread  21  corresponds to the outer thread of the shank  7  of a bolt  6 . 
     Further, the aligning tool  12  comprises a second section  22  adjoining the first section  16 . The second section  22  tapers down in a direction (indicated with an arrow in  FIG. 2 ) away from the first section  16 . The section  22  has a first end  23  having an outer diameter  24 . The outer diameter  24  is the same as the outer diameter of the first section  16  and is configured to provide a clearance fit with a hole  15  in the flange  13  of the tower  3 . The second section  22  tapers down from the outer diameter  24  to an outer diameter  25 . The outer diameter  25  is much smaller than the outer diameter  24 , and thus much smaller than the diameter of the hole  15 . For example, the outer diameter  25  can be a third of the outer diameter  24 . 
     Preferably, the first and second section  16 ,  22  are formed in one piece and have an smoothly contoured outer rocket-shaped surface  26 . 
     Further, the aligning tool  12  comprises a geometry  27  adapted to apply a torque to the aligning tool  12  for screwing the inner thread  21  onto the shank  7  of a bolt  6 . The geometry  27  is formed as a hexagon head, for example. The hexagon head  27  is adapted to come into engagement with a socket wrench, in particular. The hexagon head  27  may attach to a second end  31  of the second section  22  facing away from the first section  16 . The hexagon head  27  has an outer diameter smaller or equal to the outer diameter  25 . Also, the hexagon head  27  may be formed in one piece with the section  22 . 
     The aligning tool  12  can be made of steel or plastic, in particular fiber-reinforced plastic. 
     Returning to  FIG. 1 , it can be seen that, first, the aligning tools  12  are screwed onto the shank  7  of a respective bolt  6  using a socket wrench (not shown), for example. 
     Thereafter, the tower  3  is lowered towards the foundation  2 . Since the end  31  of each aligning tool  12  (as well as the hexagon head  27 , if provided) has the small outer diameter  25 , the end  31  (or the hexagon head  27 ) easily catches a corresponding hole  15  in the flange  13  of the tower  3 , as shown in  FIG. 3 . Due to the increasing outer diameter of the second section  22 , each hole  15  is centered with respect to a center line  32  of each aligning tool  12  as the tower  3  is lowered more and more towards the foundation  2 . Of course, at the same time, each hole  15  is centered with respect to each bolt  6 . 
     Thus, as shown in  FIG. 4 , all the holes  15  of the flange  13  (and also the holes of the inner flange, which are not shown) come into engagement with the shank  7  of a respective bolt  6 . Once the tower  3  has been fully lowered, the flange  13  lies against the concrete body  11  as seen in  FIG. 4 . Then, the aligning tools  12  are unscrewed, for example using a socket wrench, from the bolts  6 . The aligning tools  12  can be reused hereafter for a further aligning task at another tower installation. Hereafter, nuts (not shown) are screwed onto a shank  7  of each bolt  6  so as to fixedly connect the foundation  2  and the tower  3  to each other. 
     Although the present invention has been described in accordance with preferred embodiments, it is obvious for a person skilled in the art that modifications are possible in all embodiments. 
     For example, the aligning tools  12  may also or instead be attached to bolts  6  of the inner row  4  (see  FIG. 1 ). Further, the aligning tools  12  may be used in connection with other fasteners, for example pins, which do not have an outer thread. In this case, the receptacle  17  of each aligning tool  12  may be formed without the inner thread  21 .