Abstract:
A threaded fastener arranged to engage with a threaded shaft and tighten an object to the shaft by stretching the threaded shaft approximately parallel to its own axis. The threaded fastener is arranged so that when screwed on to the shaft the contacting surface are not parallel, thereby leaving a gap. The threaded fastener further comprises a tilting means of levering the surfaces away from one another and enlarging the gap between the surfaces. The tilting means may comprise an additional threaded shaft being threaded into an additional threaded aperture in the fastener or a ball bearing located in a groove on the surface of the fastened and contacting the surface of the object. The tilting means stretches the threaded shaft without bending the bolt requiring far less torque for stretching than a conventional nut and bolt tightened with a wrench.

Description:
BRIEF DESCRIPTION OF THE INVENTION 
     The present invention relates to an improved fastener, in particular, a threaded type fastener. 
     FIELD OF THE INVENTION 
     Threaded fasteners have almost universal application in all forms of machinery, vehicles and structures. The most commonly used form of threaded fastener is the simple nut and bolt. This type of device has common problems associated with its use, especially in regard to fastening of dynamic parts, for example the fastening of a grinding disc to an angle grinder. In this type of situation the nut and bolt are commonly arranged such that rotation of the device will cause the nut to tighten during use. This, however, results in the situation where difficulty can be encountered in subsequently removing the nut. 
     A number of devices have been previously applied to these situations to attempt to alleviate this type of problem. For example, nuts with low friction bearings have been applied prevent over tightening. These devices, however, have the disadvantages of using expensive or complex parts. 
     The present invention seeks to alleviate some of the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided a fastener characterized in that it includes a nut arranged to engage with a threaded shaft and having a first surface arranged to be screwed down against a contact surface, the first surface of the nut having a first side and a second side, the first side being arranged to come into contact with the contact surface before the second side leaving a gap between the second side and contact surface and the nut also having at least one tilting means adjacent the second side, the tilting means being arranged to engage with the contact surface and vary the size of the gap, and may be used on the backside of the fastened object. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described by way of example with reference to the accompanying drawings in which: 
     FIG. 1 is a side view of a fastener in accordance with the present invention in a nut disengaged position. 
     FIG. 2 is a side view of the fastener of FIG. 1 in a first nut engaged position; 
     FIG. 3 is a side view of the fastener of FIG. 1 in a second nut engaged position, 
     FIG. 4 is an alternate embodiment of the fastener of FIG. 1; 
     FIG. 5 is a top cross-sectional view of the nut of FIG. 4, 
     FIG. 6 a  is a side cross sectional view of the groove of FIG. 5 in a disengaged position, 
     FIG. 6 b  is a side cross sectional view of the groove of FIG. 5 in an engaged position, 
     FIG. 7 is an alternate embodiment of the fastener of FIG. 1; 
     FIG. 8 is an another alternate embodiment of the fastener of FIG. 1; 
     FIG. 9 a  is a side cross sectional view of an alternate tilting means of a fastener in accordance with the present invention in a disengaged position; 
     FIG. 9 b  is a side cross sectional view of the tilting means of FIG. 9 a  in an engaged position, 
     FIG. 10 a  is a side cross sectional view of an another alternate tilting means in accordance with the present invention in a disengaged position; and 
     FIG. 10 b  is a side cross sectional view of the tilting means of FIG. 10 a  in an engaged position; 
    
    
     DESCRIPTION OF THE INVENTION 
     In FIGS. 1 to  3  of the accompanying drawings, there is shown a fastener  10  in accordance with the present invention including a nut  12  a bolt  14  and a washer  16 . The bolt  14  includes a threaded shaft end  22  and a head end  26 . Shown also in FIGS. 1 to  3  are a first plate  18  and a second plate  20  which are to be fastened together. The first and second plates  18  and  20  are each provided with an aperture. The apertures are arranged to be alignable and able to receive the threaded shaft end  22  of the bolt  14 . The plates  18  and  20  represent any two objects, or more than two that may be desired to be fastened together. For example, the first plate  18  may be a grinding disc for an angle grinder and the second plate  20  and bolt  14  may together represent the base of the grinder to which the disc is to be attached, fastened or removed. 
     The nut  12  includes a threaded aperture  24  having a suitably sized thread to receive the threaded shaft  22  of the bolt  14 . The nut  12  includes a first surface  28  and a second surface  30 . The second surface  30  is remote from the head  26  of the bolt  14  and is arranged to be generally perpendicular to the threaded shaft  22  of the bolt  14  when the threaded shaft  22  is received within the threaded aperture  24  of the nut  12 . 
     The first surface  28  is opposed to the second surface  30  and is arranged at an angle to the second surface  30 . The nut has a first side  32  and second side  34 , remote from the first side  32  whereby the thickness of the nut  12  is greater at the first side  32  than the second side  34  due to the angled first surface  28 . The difference in thickness of side  32  to  36  is precise relevant to the distance of tilt to tension, or loosening. 
     Also provided is a tilting means  35  adjacent the second side  34  of the nut  12 . The tilting means  35  is one example of a tilting means only in the form of a screw  36  arranged to be received within a threaded aperture  38  in the nut  12 . The screw  36  is provided with a lever  40  at a first end  42 , on one side. The first end  42  is arranged adjacent the second surface  30  of the nut  12  when the screw  36  is threaded through the aperture  38 . The lever  40  is arranged such that turning the lever  40  in one direction results in a second end  44  of the screw  36  protruding through the first surface  28  of the nut  12 . Turning the lever  40  in the other direction causes the second end  44  of the screw  36  to be retracted within the nut  12 , so that it does not protrude past the first surface  28 . 
     When the nut  12  is threaded down the bolt  14  it comes up against a contact surface  15 . The contact surface  15  is in the form of a washer  16 , provided to be inserted over the threaded shaft  22  of the bolt  14  between the first plate  18  and the nut  12 . The washer  16  may alternatively be pivotally attached to the nut  12 . 
     In use, the bolt  14  is inserted through the apertures of the plates  18  and  20 . The washer  16  is then placed over the bolt  14  and the nut  12  is screwed onto the threaded shaft  22  of the bolt  14  as can be seen in FIG.  1 . 
     The nut  12  is then screwed down further onto the bolt  14  until it comes into contact with the washer  16 . Due to the angled first surface  28 , the first side  32  of the nut  12  will come into contact with the washer  16  first. At this point there will still be a gap between the washer  16  and the nut  12  adjacent the second side  34 . The nut  12  is then screwed down further until the first surface  28  is now perpendicular to the threaded shaft  22  of the bolt  14  and rests flat against the washer  16  as shown in FIG.  2 . This tilting of the nut is able to occur due to the fact that there will always exist some clearance between the thread of a bolt and of a nut. Also, the first contact of the nut  12  with the contact surface  15  will also cause the threaded shaft  22  to flex sideways. The nut  12  need not tilt fully depending upon shaft  22  clearance and the tension required. 
     The lever  40  of the screw  36  is now turned to extend the second end  44  of the screw below the first surface  28  of the nut  12 . The lever  40  is turned to extend the second end  44  of the screw  16  a sufficient distance such that the nut  12  is tilted back until the second surface  30  is again perpendicular to the threaded shaft  22  of the bolt  14 , as shown in FIG.  3 . Preferably, lugs or stoppers (not shown) are provided on the second surface  30  of the nut  12  to limit travel of the lever  40  between a first position where the second end  44  of the screw  36  is level with or retracted within the first surface  28  and a second position where the second end  44  of the screw  36  is extended sufficiently to level the nut  12  as previously described. A spring to give lever  40  automatic return may be provided. 
     The leveling of the nut  12  increases the tension between the internal thread of the nut  12  and the threaded shaft  22  of the bolt  14 . The pressure thereby created by friction on the threads and contact points under the nut  12  secures the nut  12  in position relative to the bolt  14 . 
     In a device where the first and second plates  18  and  20  are to be secured for rotation, the lever  40  is preferably arranged to be turned opposite to the direction of rotation to the tool spindle of shaft  22 . This prevents any forces, such as a centrifugal force, acting on the lever  40  in a direction that would tend to release the fastener  10 . Preferably also, the screw  36  is of small size to also prevent loosening. To release the nut  12 , the lever free end  40  is turned in the opposite direction to retract the second end  44  of the screw  36  until it is level with or below the first surface  28  of the nut  12 . The tension between the nut  12  and the threaded shaft  22  of the bolt  14  is released and the nut  12  returns to the tilted position as shown in FIG.  2 . The nut  12  then may be easily removed from the bolt  14 . 
     In the case of a dynamic situation such as an angle grinder, the nut  12  may be screwed down with the screw  36  already extended as shown in FIG.  3 . The rotation will then cause the nut  12  to automatically tighten. The nut  12  can then be released as previously described. 
     In FIGS. 4 to  6  is shown an alternate embodiment of a fastener  10  in accordance with the present invention. In this embodiment, the tilting means is formed by at least one ball bearing  19 . The ball bearing  19  is contained within an arcuate groove  17  in the first surface  28  of the nut  12  adjacent the second end  34 . The arcuate groove  17  has a first end  21  and a second end  23 . The depth of the groove  17  is arranged to be shallower at the first end  21  than the second end  23 , as can be seen in FIGS. 6 a  and  6   b . When the ball bearing  19  is located adjacent the first end  21  of the groove  17  it protrudes below the first surface  28  and it is located adjacent the second end  23  of the groove  17  it is contained fully within the groove  17 . 
     When the nut  12  is screwed down, the ball bearing  19  moves to the first end  21  of the groove  17  and protrudes below the first surface  28 , acting in a similar manner to the screw of FIGS. 1 to  3 . When the nut  12  is released, the ball bearing  19  moves towards the second end  23  of the groove  17  and releases the nut  12 . 
     FIG. 7 illustrates an alternate embodiment of the fastener of FIGS. 1 to  3  in accordance with the present invention. As shown in FIG. 7, the first surface  28  of the nut is not angled. The first surface  28  is parallel to the second surface  30  which is perpendicular to the threaded shaft  22  of the bolt  14 . The washer  16  in this case includes an angled surface  15 . Due to the angled surface  48 , the washer  16  has a greater thickness at a first end  46  thereof, than the thickness at second end  34 . In use, the fastener  10  operates in the same way as the fastener  10  of FIGS. 1 to  3 . The first end  46  of the washer  16  must be positioned such that it is opposite the screw  36  of the nut  12 . The washer  16  would preferably be pinned to the nut  12  by pins  47  to ensure this condition. 
     FIG. 8 shows another alternate embodiment of the fastener  10  of FIGS. 1 to  3 . In this embodiment the first surface  28  is parallel to the second surface  30  as in the embodiment of FIG. 7. A lug  50  is provided on the first surface  28  adjacent the first side  32  of the nut  12 . The lug  40  produces the same tilting effect as the angled first surface  28 , FIGS. 1 to  3 . 
     FIGS. 9 a  and  9   b  and  10   a  and  10   b  show further alternate embodiment of the tilting means  35 . In FIGS. 9 a  and  9   b  the second side  34  of nut  12  includes a curved aperture  58  in the first surface  28  on or near the outer edge  34  of the nut  12 . A plurality of ball bearings  60  are contained within the curved aperture  58 . A cover ring  62  is provided to fit over the nut  12  and includes a recess  64  adjacent the outer edge of the nut  12 . The ring  62  may be rotated from a first position in which the recess  64  is in alignment with the curved aperture  58  to a second position in which it is out of alignment with the curved aperture  58 . When in the second position, the ring  62  forces the ball bearings  60  to protrude below the first surface  28 . In the first position, the ball bearings  60  move partially into the recess  64  to release the nut  12 . 
     In FIGS. 10 a  and  10   b  the nut  12  is provided with a groove  66  in the first surface  28 . A ball bearing  68  is provided in the groove  66 . The screw  36  is arranged to come into contact with the ball bearing  68  and force the ball bearing  68  to protrude past the first surface  28 . The screw  36  further includes a tapered second end  44 , 
     In another alternate embodiment, the lever mechanism  40  of the screw  36  may be detachable from the screw  36  or be replaced by a suitable arrangement for receiving a tool. For example, the screw  36  may be provided with a recess in the first end  42  instead of the lever  40 . The recess would be arranged to be suitable for receiving a tool such as an Allen key. 
     In a further embodiment, the first end  42  of the screw  36  may reside in a recess provided in the second surface  30  of the nut  12 . This would provide protection for the screw  36  to prevent it from being damaged or catching on something. The recess may also be provided with cover to further protect the first end  42  of the screw  36 . Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.