Abstract:
The present invention provides a method for removing a fastener from a component, the fastener comprising an end portion exposed from the component, the end portion having a threaded section, the method comprising the following steps; providing a cap with a threaded opening, screwing the threaded opening of the cap onto the threaded section of the exposed end portion of the fastener, and securing a percussive tool to the cap, such that repeated impacts from the percussive tool are directed onto the exposed end portion of the fastener. The present invention also provides a cap for use in removing a fastener from a component, the cap comprising a threaded opening for screwing onto a threaded section of an exposed end portion of the fastener, and an attachment portion for securing a percussive tool to the cap.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention concerns fastener removal. More particularly, but not exclusively, this invention concerns a method for removing a fastener from a component. The invention also concerns a cap for use in removing a fastener from a component. 
         [0002]    US 2012/0055293 discloses a tool for removing a seized fastener from a component. The tool comprises a rod driver and one or more interchangeable sockets. The sockets connect to one end of the driver and have different openings at their front ends for connecting over different size/shape bolt heads. The driver is designed to secure a pneumatic hammer at its other end. Shock waves are then sent into the bolt shank and thread areas via axial blows from the pneumatic hammer. The tool allows impacts to be centred on the bolt head without damaging the bolt head and without the driver jumping off the bolt. 
         [0003]    However, the tool can only be used on bolts where the bolt head protrudes from the component. In other words, it cannot be used for sunken bolt heads or fasteners that do not have a bolt head, or similar. 
         [0004]    Another method for removing a bolt is also known. This method involves drilling a hole through the centre of the bolt head (which may be sunken) and down into the shank of the bolt. The hole is then tapped to provide it with an internal thread. A mandrel is then screwed into the internally threaded hole, a spacer bush placed over the mandrel and a hydraulic puller tool is used to pull on the mandrel and thereby pull the bolt out from its hole in the component. 
         [0005]    The bolt (still attached to the mandrel) is then placed back in the hole in the component in order to remove the bolt sleeve still in the component hole. A sleeve removal cap is then screwed onto the exposed tail of the bolt. The spacer bush is then placed over the mandrel and the hydraulic puller tool is used to pull the mandrel, and thereby the bolt, sleeve removal cap and the sleeve from the component hole. 
         [0006]    A disadvantage of this method is that, although it can be used for fasteners with sunken bolt heads, it is very time consuming. For example, it can take approximately 5 hours to remove one bolt using this method. In addition, it requires drilling through and tapping inside a bolt, which cause damage to the bolt and introduce health and safety considerations. In addition, there is a risk of damage to the component itself. Furthermore, the pressure required to drill through the bolts can cause damage to the drill bits used. 
         [0007]    The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method for removing a fastener from a component. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides, according to a first aspect, a method for removing a fastener from a component, the fastener comprising an end portion exposed from the component, the end portion having a threaded section, the method comprising the following steps; providing a cap with a threaded opening, screwing the threaded opening of the cap onto the threaded section of the exposed end portion of the fastener, and securing a percussive tool to the cap, such that repeated impacts from the percussive tool are directed onto the exposed end portion of the fastener. 
         [0009]    Providing a cap with a threaded opening allows the cap to be screwed onto an exposed end portion of a fastener. For example, where the fastener is a bolt and the bolt head is sunken, it allows the cap to be screwed onto a tail of the bolt. Having a cap attached to the fastener allows a percussive tool to be secured to the cap and provide repeated impacts to the fastener to allow the fastener to be loosened, if it is seized, for example. The percussive tool may be secured to the cap by an attachment mechanism that attaches the percussive tool to the cap, whilst allowing the percussive tool to have a limited movement with respect to the cap. The percussive tool may be secured to the cap such that it is prevented from detaching from the cap. This means that repeated impacts from the percussive tool do not cause the percussive tool to become detached from the cap and allows repeated impacts from the percussive tool to be directed onto the exposed end portion of the fastener. As the percussive tool is secured to the cap, the repeated impacts are caused to only be directed onto the fastener and not onto the component, for example. 
         [0010]    Preferably, the component is an aircraft component. 
         [0011]    Preferably, the fastener is a bolt and wherein the method also comprises the step of unscrewing a nut from the exposed threaded section of the bolt. 
         [0012]    Preferably, the percussive tool is secured to the cap by securing an impact member, which is secured to, and may be an integral part of, the percussive tool, in a hollow section of the cap, such that the impact member is adjacent to the exposed end portion of the fastener. Having the impact member adjacent to the fastener allows repeated impacts to be directed onto the fastener. Having a hollow section of the cap allows an impact member to be contained within the hollow section. 
         [0013]    More preferably, the impact member is moveable inside the hollow section, to and from the exposed end portion of the fastener. This allows the impact member to be moved to and from the fastener by the percussion tool to provide repeated impacts directed onto the fastener. 
         [0014]    More preferably, the impact member is rotatable inside the hollow section of the cap. This allows the percussive tool to be moved around in relation to the component by an operator during use. 
         [0015]    Preferably, the percussive tool is secured to the cap by pushing the impact member through a resilient opening in the cap into the hollow section of the cap. This allows the impact member to be easily secured and removed from the cap, without the use of a separate clasp, or similar, that would need to be fastened and un-fastened during use. 
         [0016]    Preferably, the percussive tool is secured to the cap by a rod, the rod being secured to the cap and also secured to the percussive tool. This allows the rod to be secured to the percussive tool and the cap in two separate stages. Hence, for example, the rod can be secured to the percussive tool and then push fitted into the resilient opening of the cap. 
         [0017]    More preferably, the impact member is located on the rod and whereby the rod is secured to the cap by securing the impact member in the hollow section of the cap, such that the impact member is adjacent to the exposed end portion of the fastener. 
         [0018]    Preferably, the method comprises the step of placing a protective washer around the exposed end portion of the fastener prior to screwing the threaded opening of the cap onto the exposed end portion of the fastener. The washer provides additional protection to prevent damage to the component. 
         [0019]    Preferably, the method comprises the step of also removing a sleeve from the component by locating a sleeve removal dowel in the sleeve and pulling the sleeve removal dowel and the sleeve out of the component. This allows a sleeve to be removed in a similar way to the prior art. 
         [0020]    According to a second aspect of the invention there is also provided a cap for use in removing a fastener from a component, the cap comprising a threaded opening for screwing onto a threaded section of an exposed end portion of the fastener, and an attachment portion for securing a percussive tool to the cap, such that, in use, repeated impacts from the percussive tool are directed onto the exposed end portion of the fastener. 
         [0021]    Providing a cap with a threaded opening allows the cap to be screwed onto an exposed end portion of a fastener. For example, where the fastener is a bolt and the bolt head is sunken, it allows the cap to be screwed onto a tail of the bolt. Having a cap attached to the fastener allows a percussive tool to be secured to the cap and provide repeated impacts to the fastener to allow the fastener to be loosened, if it is seized, for example. The percussive tool may be secured to the cap by an attachment mechanism that attaches the percussive tool to the cap, whilst allowing the percussive tool to have a limited movement with respect to the cap. The percussive tool may be secured to the cap such that it is prevented from detaching from the cap. This means that repeated impacts from the percussive tool do not cause the percussive tool to become detached from the cap and allows repeated impacts from the percussive tool to be directed onto the exposed end portion of the fastener. As the percussive tool is secured to the cap, the repeated impacts are caused to only be directed onto the fastener and not onto the component, for example. 
         [0022]    Preferably, the attachment portion of the cap comprises a hollow section for securing an impact member therein such that, in use, the impact member is adjacent to the exposed end portion of the fastener. Having the impact member adjacent to the fastener allows repeated impacts to be directed onto the fastener. Having a hollow section of the cap allows an impact member to be contained within the hollow section. 
         [0023]    More preferably, the cap comprises a resilient opening to the hollow section. This allows the impact member to be easily secured and removed from the cap, without the use of a separate clasp, or similar, that would need to be fastened and un-fastened during use. 
         [0024]    The invention also provides a tool assembly comprising a cap as described above, and an impact rod for connecting to the cap and to a percussive tool. 
         [0025]    The invention also provides a method for removing a fastener from a component, as described above, whereby the method comprises using the cap or the tool assembly as described above. 
         [0026]    It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the cap or tool assembly of the invention and vice versa. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0027]    Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: 
           [0028]      FIG. 1  shows a side sectional view of a bolt in a component; 
           [0029]      FIG. 2  shows a perspective view of a cap according to a first embodiment of the invention; 
           [0030]      FIG. 3  shows a view of a first end of the cap of  FIG. 2 ; 
           [0031]      FIG. 4  shows a side sectional view of a rod inserted into the cap of  FIGS. 2 and 3 ; 
           [0032]      FIG. 5  shows a side view of a rivet gun for use with the rod and cap in  FIG. 4 ; 
           [0033]      FIG. 6  shows a perspective view of the bolt of  FIG. 1  in a component, with a protective washer over the bolt tail; 
           [0034]      FIG. 7  shows a view of the arrangement of  FIG. 6  with the cap of  FIG. 2  screwed onto the bolt tail with hidden detail of the inside of the cap  40  also shown; 
           [0035]      FIG. 8  shows a view of the arrangement of  FIG. 7  with the rod of  FIG. 4  inserted into the cap with hidden detail of the inside of the cap  40  also shown; 
           [0036]      FIG. 9  shows a side view of a sleeve removal dowel; and 
           [0037]      FIG. 10  shows a perspective view of the sleeve removal dowel of  FIG. 9  inserted into the component. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]      FIG. 1  shows a side sectional view of a bolt  20  in a Carbon Fibre Reinforced Plastic (CFRP) component  10 . The bolt  20  comprises a sunken tapered bolt head  21 , flush with the front/head side  11  of the component  10 , a cylindrical bolt shank  22  and a bolt tail  23  exposed from the rear/tail side  12  of the component  10 . The bolt tail  23  has a threaded section  24  on it, which a nut (not shown) would have been screwed onto before being removed. 
         [0039]    Surrounding the bolt head  21  and bolt shank  22  is a sleeve  30  in the component  10 . The sleeve  30  comprises a tapered portion  32  to correspond with the tapered shape of the bolt head  21  and a cylindrical straight portion  31  corresponding to the shape of the bolt shank  22 . 
         [0040]      FIG. 2  shows a perspective view of a cap  40  according to a first embodiment of the invention and  FIG. 3  shows a view of a first end  41  of the cap  40  of  FIG. 2 . The cap  40  comprises a first end  41  with a metallic threaded opening  43  and a second end  42  with a resilient opening  44 . The threaded opening  43  corresponds to the threaded section  24  of the bolt tail  23 . The cap is made of metal  46 , covered with a resilient polyurethane material  47 . It is the polyurethane material  47  that provides the opening  44  with its resilient, flexible nature. The cap  40  also comprises a hollow section  45  adjacent to the resilient opening  44 . 
         [0041]      FIG. 4  shows a side sectional view of a cylindrical rod  50  inserted through the resilient opening  44  of the cap  40  of  FIGS. 2 and 3 . The rod  50  comprises a first end  51  with a ball impact member  54 . The ball impact member  54  is located within the hollow section  45  of the cap  40 . Along the length of the rod, towards a second end  52 , is a flared portion  53  where the rod has a portion with a larger diameter than the rest of the rod. This flared portion  53  is for securing to a rivet gun  60 . 
         [0042]      FIG. 5  shows a side view of the rivet gun  60 . The rivet gun  60  comprises an impact driver  62  adjacent to an attachment wire  61 . It is the attachment wire  61  that clips over the flared portion  53  of the rod  50  to secure the rivet gun  60  to the rod  50  so that the impact driver  62  can impact on the second end  52  of the rod. The rivet gun  60  also comprises a user handle  64  and an on-off switch  63 . 
         [0043]      FIG. 6  shows a perspective view of the bolt  20  of  FIG. 1  in the component  10 , with a protective washer  70  over the bolt tail  23 , resting on the rear/tail side  12  of the component. The protective washer  70  is made from ethylene propylene diene monomer (EPDM) and is resilient to prevent damage occurring to the component  10 . It has a thickness of 3.5 mm. It has an internal diameter corresponding to the diameter of the bolt tail  23 . 
         [0044]      FIG. 7  shows a view of the arrangement of  FIG. 6  with the cap  40  of  FIG. 2  screwed onto the threaded section  24  of the bolt tail  23 . The resilient opening  44  of the cap is at the back of the arrangement, facing away from the rear/tail side  12  of the component  10 . 
         [0045]      FIG. 8  shows a view of the arrangement of  FIG. 7  with the ball impact member  54  of the rod  50  of  FIG. 4  inserted into the resilient opening  44  of the cap  40 . At least part of the ball impact member  54  is inserted through the resilient opening  44  and located in the adjacent hollow section  45  of the cap. As can be seen in  FIG. 8 , the rod  50  can rotate with respect to the cap  40 . In addition, the rod  50  can be moved in and out (i.e. towards and away from the rear/tail side  12  of the component  10 ) in relation to the cap  40 . This means that the amount of the ball impact member  54  received in the hollow section  45  can vary. 
         [0046]    When the maximum amount of ball impact member  54  is received in the hollow section  45  of the cap  40  (i.e. when the rod  50  is at its extreme position nearest to the rear/tail side  12  of the component  10 ), the ball impact member  54  impacts against the bolt tail  23  of the bolt  20 . When the minimum amount of ball impact member  54  is received in the hollow section  45  (i.e. when the rod  50  is at its extreme position furthest away from the rear/tail side  12  of the component  10 ), the ball impact member  54  is only partly located in the hollow section  45 , as shown in  FIG. 8 . However, more than half of the ball impact member  54  is located within the hollow section  45 , which means the widest point of the ball impact member  54  is inside the resilient opening  44 , thus preventing the rod  50  from separating from the cap  40 . 
         [0047]      FIG. 9  shows a side view of a sleeve removal dowel  80  for use in removing the sleeve  30  from the component  10 . The dowel  80  comprises a cylindrical shaft  81  and an enlarged end portion  82 . The enlarged end portion has a diameter slightly larger than the rest of the dowel. The diameter of the cylindrical shaft  81  corresponds to the internal diameter of the sleeve  30  and the enlarged end portion has a diameter corresponding to the external diameter of the sleeve  30 . At the opposite end to the enlarged end portion  82 , the shaft  81  has an internally threaded section (not shown). 
         [0048]      FIG. 10  shows a perspective view of the sleeve removal dowel  80  of  FIG. 9  inserted into the component  10 . This figure shows the rear/tail side  12  of the component  10  (where the bolt tail  23  was), with the enlarged portion  82  of the sleeve removal dowel  80  resting on the sleeve  30  and protruding from the rear/tail side  12  of the component  10 . The shaft  81  of the dowel  80  is located through the sleeve  30  and protrudes out of the front/head side  11  of the component  10  (not seen in  FIG. 10 ). 
         [0049]    In use, in order to remove the bolt  20  from the component  10 , the following steps are carried out:
       1) The nut (not shown) is unscrewed from the bolt tail  23  using a nut runner, a torque bar and a ratchet (not shown),   2) Any washers (not shown) under the nut are pulled off the bolt tail  23 ,   3) The protective washer  70  is paced over the bolt tail  23 ,   4) The cap  40  is screwed onto the bolt tail  23  until it is finger tight,   5) The rivet gun  60  is secured to the rod  50  by securing the attachment wire  61  of the rivet gun over the flared portion  53  of the rod,   6) The ball impact member  54  of the rod is pushed through the resilient opening  44  of the cap, into the hollow section  45  of the cap,   7) The rivet gun  60  is turned on gradually and repeated impacts are directed onto the bolt tail  23  until the seizing of the bolt head taper  21  has been released. The power from the rivet gun  60  is reduced as movement of the bolt  20  is felt, in order to reduce the impact on the component  10 ,   8) The ball impact member  54  is pulled out of the resilient opening  44  of the cap,   9) The cap  40  is unscrewed from the bolt tail  23  using an adjustable spanner,   10) The protective washer  70  is removed from the bolt tail  23 , and   11) The bolt  20  is removed from the component  10  by pushing the bolt tail  23  into the rear/tail side  12  of the component  10  until the bolt head  21  protrudes from the front/head side  11  of the component and then the protruding bolt head  21  is pulled out of the front/head side  11  of the component.       
 
         [0061]    In use, in order to then remove the sleeve  30  from the component  10 , the following steps are carried out:
       12) The shaft  81  of the sleeve removal dowel  80  is inserted into the sleeve  30  from the rear/tail side  12  of the component  10  until the enlarged portion  82  abuts the sleeve  30  and is left protruding from the rear/tail side  12  of the component,   13) A mandrel (not shown) is screwed into the internally threaded section of the shaft  81  of the sleeve removal dowel  80  at the front/head side  11  of the component  10 ,   14) A spacer bush (not shown) is placed over the mandrel and onto the front/head side  11  of the component  10 , and   15) A hydraulic puller tool (not shown) is used to pull on the mandrel, and thereby pull on the shaft  81  of the sleeve removal dowel  80 , the enlarged portion  82  of the sleeve removal dowel  80  and push the sleeve  30  out of the front/head side  11  of the component  10 .       
 
         [0066]    Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described. 
         [0067]    Any type of percussive tool could be used, for example a pneumatic hammer could be used, instead of the rivet gun. 
         [0068]    The percussive tool could come with an integral impact member, rather than subsequently being attached to a rod with an impact member. 
         [0069]    The impact member could be any suitable shape, for example a hemisphere, a square or a diamond shape could be used. 
         [0070]    The cap could be made from any suitable resilient material, such as plastic or rubber. Alternatively, the cap could just be made from a metallic material. 
         [0071]    The protective washer could be made from any suitable material, such as plastic or rubber. It may also be any suitable shape or dimension. 
         [0072]    Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.