The present invention relates to fastening member. The fastening member may comprise, be provided at, or integral with, a fastener, such as nuts, bolts, washers, screws, nails and the like. Alternatively, the fastening member may be provided at a structural component, such as a beam, pillar, bracket or the like. In particular, but not exclusively, the invention relates to threaded fasteners having self locking means.

Various types of self locking fasteners, such as nuts and bolts, exist to prevent unintended unfastening. In particular, many such fasteners are designed to prevent loosening due to vibrations. However, conventional self locking fasteners have a number of drawbacks or limitations. For instance, many such fasteners do not allow intended unfastening, such as when an article is being disassembled for maintenance or when the fastener itself is worn or corroded and requires to be replaced.

It is desirable to provide a self locking fastener which resists unintended loosening but which substantially allows intended loosening.

Many conventional self locking fasteners are complex and costly to produce. Also, the self locking means can often only be provided on certain types of fasteners. Furthermore, the self locking means may only resist loosening due to certain types of forces (for instance, the self locking means may only resist torsional forces present) and the self locking means may be incompatible with other forms of self locking means.

It is desirable to provide a self locking fastener which is relatively simple in structure and/or operation. It is desirable to provide self locking means which can be provided on a wide range or all types of mechanical fasteners. It is desirable to provide a self locking fastener which can resist any type of forces which can cause loosening. It is desirable to provide self locking means which is compatible with other forms of self locking means.

According to the present invention there is provided a fastening member which is fastenable to an article, the fastening member comprising: a body member; and a pivotable gripping member which extends from the body member to the article, wherein the gripping member is arranged such that separation of the fastening member from the article causes pivoting of at least a portion of the gripping member towards the article thereby causing the gripping member to grip the article to resist further separation of the fastening member from the article.

The term "separation" is intended to cover infinitesimal movement of the gripping member away from the article. Alternatively, the fastening member may be arranged to allow significant separation before the gripping member pivots towards the article to grip the article.

The fastening member may have a fastening axis which is defined as the direction of movement of the fastening member towards and away from the article. The gripping member may be arranged at an oblique orientation to the fastening axis. The gripping member may be arranged such that separation of the fastening member from the article causes pivoting of the gripping member from the oblique orientation towards a plane which is normal to the fastening axis.

The fastening member may include biasing means for biasing the gripping member into contact with the article. The fastening member may be configured such that the gripping member is bias towards the article during one or both of separation or unfastening of the fastening member from the article. Alternatively or in addition, the fastening member may have a rotational plane which is defined as a plane of rotation of the fastening member relative to the article. The gripping member may be arranged at an oblique orientation to a line within the rotational plane extending from the gripping member to the article. The gripping member may be arranged such that rotation of the fastening member relative to the article causes pivoting of the gripping member towards the line extending from the gripping member to the article.

Alternatively or in addition, the gripping member may include an end feature which is adapted to move towards the article during pivoting of the gripping member.

The gripping member may be flexible and pivoting of the gripping member is due to flexing of the gripping member.

Alternatively, the fastening member may include a hinge member and the gripping member is pivotable about the hinge member.

The body member and gripping member may be integral. Alternatively, the body member may be provided by a separate component.

The fastening member may include control means for selectively preventing or inhibiting the gripping member from gripping the article during separation of the fastening member from the article. The control means may be adapted to prevent or inhibit pivoting of the gripping member towards the article during separation of the fastening member from the article.

The fastening member may be a female fastening member having an aperture for receiving the article. At least a portion of the body member may be adapted to be circumferentially spaced from the aperture and the gripping member may extend towards the aperture. The aperture may be threaded for receiving a correspondingly threaded article.

The gripping member may define an aperture for receiving the article. The gripping member may be adapted to extend into the spacing defined by two adjacent threads of the article. Alternatively, the aperture may be threaded.

The fastening member may comprise a female fastener such as a nut or a washer or the like. Alternatively, the fastening member may be provided at a structural member having an aperture for receiving the article.

The fastening member may be a male fastening member having a protrusion adapted to fit within an aperture of the article. The fastening member may include means for forming the aperture of the article during fastening of the fastening member to the article. The gripping member may extend outwards from the protrusion towards the article.

The protrusion may be threaded for screwing the fastening member to a correspondingly threaded aperture of the article.

The gripping member may be adapted to extend into the spacing defined by two adjacent threads of the article.

The fastening member may comprise a male fastener such as a bolt or a screw or a nail or the like. Alternatively, the fastening member may be provided at a structural member having a protrusion which is receivable in an aperture of the article.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side view of a nut according to a first embodiment of the invention and a conventional bolt;

Figure 2 is a detailed side view of a portion of the nut of Figure 1 in a (a) non- pivoted and (b) pivoted state; and

Figure 3 is a side view of a bolt according to a second embodiment of the invention and a conventional nut.

Figure 1 shows a first embodiment of the invention. In this embodiment, the fastening member is a female fastener in the form of a nut 10 which can be fastened to a conventional bolt 100.

The nut 10 comprises a body member 12 which has a threaded aperture 16 and a flange 14 at one end of the nut 10 (intended to be end facing the bolt 100 in this embodiment). Extending from the flange 14 towards the aperture 16 is a pivotable gripping member 18. The gripping member 18 is therefore a cantilever and is formed (in terms of geometry and material properties) to be substantially flexible so that the gripping member 18 will bend (pivot) about the flange 14.

In an alternative embodiment, the nut 10 could include a hinge at the flange 14 and the gripping member 18 could freely pivot about the hinge.

The nut 10 can be considered to have a fastening axis 102 which is defined as the direction of movement of the nut 10 towards and away from the bolt 100. The gripping member 18 is arranged at an oblique orientation to the fastening axis

102 and to a plane 104 normal to the axis 102. The flange 14 and gripping member 18 could be provided at the other end of the nut 10 with respect to the end for inserting the bolt 100. In this case, the gripping member 18 would then extend from the flange 14 at an oblique orientation away from the body 12. The aperture 16 is sized to correspond to the outer diameter 106 of the bolt 100 in the same manner as for a conventional nut. Similarly, the extending gripping member 18 defines a correspondingly sized aperture prior to pivoting of the gripping member 18. In this embodiment, the gripping member 18 is continuous and is therefore a washer. However, in other embodiments the gripping member 18 need not be continuous. For instance, the gripping member 18 could comprise a plurality of spaced apart fingers which extend from the flange 14. Alternatively, the gripping member 18 could be substantially continuous (prior to pivoting) but formed from closely packed or abutting fingers.

The bolt 100 can be threaded to the nut 10 in a conventional manner. Any contact between the gripping member 18 and the bolt 100 caused by movement of the bolt 100 towards the nut 10 will tend to bend the gripping member 18 towards the body 12 of the nut 10 and away from the plane 104 normal to the fastening axis 102. This effectively increases the diameter of aperture defined by the gripping member 18.

However, the gripping member 18 resists any separating force which attempts to move the bolt 100 away from the nut 10. This force could arise from vibrations, which tend to be complex and multidirectional but a resultant separating force must usually be present to cause unintended unfastening. The separating force causes the gripping member 18 to bend away from the body 12 of the nut 10 and towards the plane 104 normal to the fastening axis 102. Since the gripping member 18 is restrained from expansion by the flange 14, the gripping member 18 is compressed as it must retain the same distance in the plane 104 from the flange 14 to the bolt 100. This compression results in a reaction force between the gripping member 18 and the bolt 100 such that the bolt 100 is gripped to resist further separation of the bolt 100 from the nut 10. It should be noted that, for this embodiment, only a resultant separating force causes gripping of the bolt 100. Therefore, the nut 10 can be freely unfastened from the bolt 100.

In some cases, this uninhibited unfastening can be undesirable, such as when a permanently locked or tamperproof fastener is required. In an alternative embodiment, the nut 10 can include biasing means for biasing the gripping member 18 into contact with the article. The gripping member 18 can be configured so that it is in tension when the nut 10 is fastened to the bolt 100. The gripping member 18 will therefore be bias towards the bolt 100 and will grip the bolt 100 more firmly during both attempted separation and unfastening of the nut 10 from the bolt 100.

In another alternative embodiment, the gripping member 18 can be arranged at an oblique orientation to a line within the plane 104 which extends radially inwards from the gripping member 18 to the bolt 100. The gripping member can be arranged such that rotation of the nut 10 relative to the bolt 100 causes pivoting of the gripping member towards the line extending from the gripping member to the article. The diameter of the aperture of the gripping member 18 will then decrease during unfastening of the nut 10 causing gripping of the bolt

100.

In the above embodiments, it is not essential that the gripping member 18 is arranged at an oblique orientation. For instance, the gripping member could be planar and parallel to the plane 104 but include an end feature which is adapted to move towards the bolt 100 during pivoting of the gripping member 18. If the gripping member 18 is suitable configured, such as a corner 20 (possible tapered) offset from the centreline 22 of the gripping member 18, a small amount of rotation of the gripping member 18 will cause the corner to rotate towards the bolt 100 to increase gripping. This is shown in Figure 2. Control means (not shown) could be provided for selectively preventing the gripping member 18 from gripping the article during separation, such as by preventing pivoting of the gripping member 18 during separation. One means of doing this is providing a releasable connection between the gripping member 18 and the flange 14 (for instance, the gripping member 18 could be threaded to the flange 14). When released, any bending of the gripping member 18 will cause expansion of the gripping member 18 rather than compression or the gripping member 18 will be free to move in the separating direction along with the bolt 100.

In the embodiment of Figure 1 , the body 12, flange 14 and gripping member 18 are integral. However, the flange 14 and gripping member 18 could be provided as a separate component, such as a modified washer. As long as there is a component like the flange 14 which provides a cantilever support for the gripping member 18 to pivot about, pivoting of the gripping member 18 will cause gripping of the bolt 100. Indeed, the fastening member does not need to be provided as part of a standard fastener. For instance, the fastening member could be provided at a structural member such as a bracket for supporting an article and having an aperture for receiving the article. The fastening member could be provided to inhibit separation of the bracket and article.

Figure 2 shows a second embodiment of the invention. In this embodiment, the fastening member is a male fastener in the form of a bolt 30 which can be fastened to a conventional nut 110.

The bolt 30 has a conventional head 32 and threaded shaft 34. The bolt also has a non-threaded portion 36 of the shaft and a pivotable gripping member 38. The gripping member 38 extends outwards at an oblique angle from the non-threaded portion 36 for a distance corresponding to the outer diameter of the threads of the shaft 34. The non-threaded portion 36 may have a reduced outer diameter to increase the length of the gripping member 38 to promote bending of the gripping member 38.

The gripping member 38 can either extend into the spacing defined by two adjacent threads of the nut 1 10 or it can have a threaded end. As before, the gripping member 38 is a cantilever and is formed to be substantially flexible. In an alternative embodiment, the bolt 30 could include a hinge.

The bolt 30 can be threaded to the nut 110 in a conventional manner. However, the gripping member 38 resists any separating force which attempts to move the bolt 30 away from the nut 110. The separating force causes the gripping member 38 to bend outwards and be compressed which results in a reaction force between the gripping member 38 and the nut 110 such that the nut 110 is gripped to resist further separation.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention. For instance, the fastening member may include means for forming an aperture during fastening. The fastening member may be a self-tapping screw or a nail and the article is a planar surface such as a wall.