BACKGROUND

The present invention relates to a fastener. More specifically, the present invention relates to a security fastener that requires a unique tool to rotate (e.g. to loosen or remove) the fastener.

Various fasteners operable with a unique tool are known. For instance, ZA1990/3765 “Protective device” (previously issued to the applicant) describes a bolt or nut with a collar rotatably mounted to and extending about the radial outer surface of the bolt head I nut, defining an annular gap there between, which requires a specially shaped tool to fit therein and turn the bolt I nut. The rotating collar further inhibits rotation of the bolt I nut by a wrench or pliers, or by a tangential blow.

It is also known for fasteners to include a ring rotatably mounted to an axial end of the fastener (similarly to prevent rotation of the fastener by a wrench or plyers, or by a tangential blow). For instance, US2002/0014137 “Screw device and assembly for theftproofing vehicle wheels”, US5,730,567 “Ant-tamper fastener” and US7,351,020 “High security fastener constructions” describe a bolt with: a unique formation at an axial end of the bolt head for cooperating with a corresponding unique formation on a tool; and a ring rotatably secured about the radial outer surface of the bolt head. US7,445,414 “High security fastener constructions” similarly describes a nut with: a unique formation at an axial end of the nut for cooperating with a corresponding unique formation on a tool; and a ring rotatably secured about the radial outer surface of the nut.

US5,256,015 “Torque limiting bolt having retained sheer pins” also describes a bolt with: a two-part hexagonal (in axial cross-section) bolt head, which parts are axially rotatably connected to each other; and locking pins extending between the bolt head parts to inhibit relative rotation of the bolt head parts. Similarly, US5,927,017 “Self-torquing nut” describes a nut comprising: an inner portion defining a female thread formation; an outer ring portion rotatably connected to, and extending about the radial outer surface of the inner portion; and locking pins extending between the inner portion and the outer ring portion to inhibit relative rotation of the two portions. It is an object of the present invention to provide either:

(i) a bolt with a cylindrical bolt head and a circular ring I disc rotatably mounted to an axial end of the bolt head, which bolt head and ring I disc define at least one groove

I flute that extends axially along their radial outer surfaces; or

(ii) a nut with a cylindrical radial outer surface and a circular ring rotatably mounted to an axial end of the nut, which nut and ring define at least one groove I flute that extends axially along their radial outer surfaces, that requires a unique “keyed” tool with projections corresponding to the grooves I flutes to rotate I loosen or remove the bolt or nut.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the invention, there is provided a fastener that includes: a body defining: a threaded portion; a first axial end portion that defines a right circular cylindrical radial outer surface; a member rotatably mounted to the first axial end portion, which member defines a right circular cylindrical radial outer surface that is axially aligned with and extends from the outer surface of the first axial end portion, characterised in that: the first axial end portion defines a first groove extending axially along at least a portion of its radial outer surface; and the member defines a first groove extending axially along its radial outer surface, such that, in use, the member may be rotated relative to the body to align the first groove defined by the first axial end portion and the first groove defined by the member to present a continuous first groove for cooperating with a corresponding formation on a tool used to rotate the fastener.

According to a first embodiment of the invention, the fastener is a bolt and wherein: the first axial end portion is the bolt head; the threaded portion: is right circular cylindrical; defines the thread formation on its radial surface; and extends axially from the first axial end portion; and the radial surface of the first axial end portion extends radially from the radial surface of the threaded portion.

Typically, the member is a ring or disc secured to an axial end of the first axial end portion, distal the threaded portion.

According to a second embodiment of the invention, the fastener is a nut and wherein: the first axial end portion defines an axially extending bore; and the threaded portion extends along the radial inner surface of the first axial end portion.

Typically, the member is a ring secured to an axial end of the first axial end portion.

In respect of the fastener according to either the first or second embodiments of the invention: the first axial end portion may define a second groove: extending axially along at least a portion of its radial outer surface; and spaced circumferentially relative to the first groove defined by the first axial end portion; and the member may define a second groove: extending axially along its radial outer surface; and spaced circumferentially relative to the first groove defined by the member. Typically, at least one of the grooves defined by the member is narrower than the at least one corresponding grooves defined by the first axial end portion.

Generally, the fastener further a right circular cylindrical tubular collar that is, in use, rotatably captured by the first axial end portion, which collar extends along the axial length of the first axial end portion and the member, providing an annular gap between: the collar on the one hand; and the first axial end portion and the member on the other hand.

Preferably, the collar defines a constriction at one axial end, which constriction defines a bore that is undersized relative to a portion of the first axial end portion.

Typically, the first axial end portion defines a radially outwards extending protrusion at or near an axial end of the first axial end portion distal the member.

Generally, the protrusion extends continuously around the circumference of the first axial end portion.

Optionally, a second member identical to the first mentioned member is rotatably mounted to the first axial end portion, concentric and axially adjacent to the first mentioned member.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of examples only, with reference to the accompanying drawing in which:

Figure 1 is a perspective view of a fastener according to a first embodiment of the invention;

Figure 2 is a diametric cross-sectional perspective view of the fastener in Figure 1 ;

Figure 3 is a diametric cross-sectional perspective view of the fastener in Figure 1 with a collar;

Figure 4 is a perspective view of a fastener according to a second embodiment of the invention; Figure 5 is a diametric cross-sectional perspective view of the fastener in Figure 4;

Figure 6 is a diametric cross-sectional perspective view of the fastener in Figure 5 with a collar;

Figure 7 is a perspective view of a fastener according to a third embodiment of the invention;

Figure 8 is a diametric cross-sectional perspective view of the fastener in Figure 7; and

Figure 9 is a perspective view of a fastener according to a fourth embodiment of the invention;

Figure 10 is a diametric cross-sectional perspective view of the fastener in Figure 9; and

Figure 11 is a diametric cross-sectional perspective view of the fastener in Figure 6, with an alternative embodiment of the collar.

DESCRIPTION OF THE INVENTION

With reference to Figures 1 to 3, a fastener 10 according to a first embodiment of the invention is in the form of a bolt.

The bolt 10 includes: a body 12; and a member 14.

The body 12 comprises: a first axial end portion 16; and a threaded portion 18.

Unlike most bolt heads that are octagonal in axial cross-section, the first axial end portion 16 (i.e. bolt head) defines a right circular cylindrical radial surface.

The threaded portion 18, which comprises a right circular cylindrical rod that extends axially from the first axial end portion, defines a thread formation on a portion of its radial surface. The diameter of the threaded portion 18 is less than the diameter of the first axial end portion 16. The first axial end portion 16 defines a radially outwards extending protrusion 20 at or near an axial end of the first axial end portion 16 proximal the threaded portion 18. This protrusion 20 extends continuously around the circumference of the first axial end portion 16.

The first axial end portion 16 also defines a first groove 22a extending axially along at least a portion of its radial surface.

The member 14 is in the form of a ring that is rotatably mounted to an axial end of the first axial end portion 16, distal the threaded portion 18. The member 14 defines a right circular cylindrical radial outer surface that is axially aligned with and extends from the outer surface of the first axial end portion 16. The member 14 also defines a first groove 22b extending axially along its radial outer surface.

The member 14 may be rotated relative to the first axial end portion 16 to align the first groove 22a defined by the first axial end portion 16 and the first groove 22b defined by the member 14 to present a continuous first groove 22.

It will be appreciated that, although the member 14 has been described and shown as a ring, the member 14 could alternatively be a circular disc that covers the entire axial end of the first axial end portion 16.

Figure 1 shows further grooves 24a and 26a that: extend axially along at least a portion of the radial surface of the first axial end portion 16; and are spaced circumferentially relative to the first groove 22a defined by the first axial end portion 16. Similarly, the member 14 defines further grooves 24b and 26b that: extend axially along its radial outer surface; and are spaced circumferentially relative to the first groove 22b defined by the member 14. Optionally (but not shown), at least one of the grooves 22b, 24b and 26c defined by the member 14 could be narrower than the corresponding grooves 22a, 24a and 26a defined by the first axial end portion 16. This enables the fastener 10 to change its “key” by changing only the member 14 while retaining the same body 12.

Turning to Figure 3, the fastener 10 further includes a right circular cylindrical tubular collar 28 that defines a constriction at one axial end (i.e. that provides a constricted opening at one axial end of the collar 28). In use, the body 12 (with head 14) is threaded through the collar 28 until the radially outwards extending protrusion 20 on the first axial end portion 16 limits further movement of the body 12 relative to the collar 28. So, arranged, the collar 28 is rotatably captured by the first axial end portion 16, with the collar 28 extending along the axial length of the first axial end portion 16 and the member 14 and providing an annular gap between: the collar 28 on the one hand; and the first axial end portion 16 and the member 14 on the other hand.

In use:

• The body 12 is threaded through the collar 28 (threaded portion 18 first).

• The male thread formation on the threaded portion 18 is then threaded into a corresponding female thread formation defined by a nut (not shown) or article (not shown) to which the fastener 10 is to be secured, thereby capturing the collar 28 on the fastener 10 body 12.

• With the fastener 10 tightly secured to the nut or article, the collar 28 is freely rotatable about the body 12 (with member 14). Since the collar 28 radially covers the first axial portion 16 and member 14, the collar 28 inhibits turning of the fastener 10 (more specifically, rotation of the threaded portion 18) by pliers or a wrench, or by a tangential blow.

• After tightening, the fastener 10 can only be removed by: o rotating the member 14 relative to the first axial portion 16 until the grooves 22b, 24b and 26ba defined by the member 14 align with the corresponding grooves 22a, 24a and 26a defined by the first axial portion 16; and o Using a unique “keyed” tool (not shown) that:

(i) is sized to fit into the annular gap between the collar 28 and the first axial portion 16 (with member 14);

(ii) defines a socket for receiving the member 14 and first axial portion 16 therein; and

(iii) includes radially inwards extending projections that correspond with the aligned grooves 22, 24 and 26 defined by the member 14 and first axial portion 16, to rotate the fastener 10 relative to the nut or article to which the fastener 10 is secured, and thereby to loosen or remove the fastener 10.

With reference to Figures 4 to 6, a fastener 110 according to a second embodiment of the invention is in the form of a nut. The nut 110 includes: a body 112; and a member 114.

The body 112 comprises: a first axial end portion 116 that defines an axially extending bore; and a threaded portion 18 that extends along the radial inner surface of the first axial end portion 116. The threaded portion 118 defines a female thread formation that extends along its entire axial length.

Unlike most nuts that are octagonal in axial cross-section, the first axial end portion 116 defines a right circular cylindrical radial outer surface.

The first axial end portion 116 defines a radially outwards extending protrusion 120 at or near an axial end of the first axial end portion 116. This protrusion 120 extends continuously around the circumference of the first axial end portion 116.

The first axial end portion 116 also defines a first groove 122a extending axially along at least a portion of its outer radial surface.

The member 114 is in the form of a ring that is rotatably mounted to an axial end of the first axial end portion 116, distal the protrusion 120. The member 114 defines a right circular cylindrical radial outer surface that is axially aligned with and extends from the outer surface of the first axial end portion 116. The member 114 also defines a first groove 122b extending axially along its radial outer surface.

The member 114 may be rotated relative to the first axial end portion 116 to align the first groove 122a defined by the first axial end portion 116 and the first groove 122b defined by the member 114 to present a continuous first groove 122.

Figure 4 shows further grooves 124a and 126a that: extend axially along at least a portion of the radial outer surface of the first axial end portion 116; and are spaced circumferentially relative to the first groove 122a defined by the first axial end portion 116. Similarly, the member 114 defines further grooves 124b and 126b that: extend axially along its radial outer surface; and are spaced circumferentially relative to the first groove 122b defined by the member 114.

Optionally (but not shown), at least one of the grooves 122b, 124b and 126c defined by the member 114 could be narrower than the corresponding grooves 122a, 124a and 126a defined by the first axial end portion 116. This enables the fastener 110 to change its “key’ by changing only the member 114 while retaining the same body 112.

Turning to Figure 6, the fastener 110 further includes a right circular cylindrical tubular collar 128 that defines a constriction at one axial end (i.e. that provides a constricted opening at one axial end of the collar 128). In use, the protrusion 120 defined by the first axial end portion 116 is oversized relative to the constriction defined by the collar 128, thereby preventing the body 112 (with member 114) from passing through the constriction defined by the collar 128. The axial length of the collar 128 is at least as great as the axial length of the first axial portion 116 (with member 114), and the inner diameter is greater than the outer diameter of the first axial portion 116 (with member 114), to provide an annular gap therebetween.

In use:

• The collar 128 is placed over a bolt (not shown) or device (not shown) with male threaded rod.

• The female thread formation on the threaded portion 118 is then threaded onto the bolt or the male threaded rod on the device, thereby capturing the collar 128 on the fastener 110 body 112.

• With the fastener 110 tightly secured to the bolt or device, the collar 128 is freely rotatable about the body 112 (with member 114). Since the collar 128 radially covers the first axial portion 116 and member 114, the collar 128 inhibits turning of the fastener 110 (more specifically, rotation of the threaded portion 118) by pliers or a wrench, or by a tangential blow.

• After tightening, the fastener 110 can only be removed by: o rotating the member 114 relative to the first axial portion 116 until the grooves 122b, 124b and 126ba defined by the member 114 align with the corresponding grooves 122a, 124a and 126a defined by the first axial portion 116; and o Using a unique “keyed” tool (not shown) that:

(i) is sized to fit into the annular gap between the collar 128 and the first axial portion 116 (with member 114);

(ii) defines a socket for receiving the member 114 and first axial portion 116 therein; and

(iii) includes radially inwards extending projections that correspond with the aligned grooves 122, 124 and 126 defined by the member 114 and first axial portion 116, to rotate the fastener 110 relative to the bolt or article to which the fastener 110 is secured, and thereby to loosen or remove the fastener 110.

With reference to Figures 7 and 8, a fastener 210 according to a third embodiment of the invention is generally similar to the fastener 10 according to the first embodiment of the invention. However, the fastener 210 according to the third embodiment of the invention includes second and third members member 230 and 232 identical to the member 14 according to the first embodiment. The second and third members 230 and 232 are similarly rotatably mounted to the first axial end portion 216, concentric and axially adjacent to the first member 214.

With reference to Figures 9 and 10, a fastener 310 according to a fourth embodiment of the invention is generally similar to the fastener 110 according to the second embodiment of the invention. However, the fastener 310 according to the fourth embodiment of the invention similarly includes second and third members member 330 and 332 identical to the member 114 according to the first embodiment. The second and third members 330 and 332 are also rotatably mounted to the first axial end portion 316, concentric and axially adjacent to the first member 314.

Turning to Figure 11 , it will be appreciated that instead of the collar 28 and 128 being tubular, the collar could alternatively be in the form of a cable gland 428. Furthermore, the open axial end of the collar 428 could include a hinged cover 434 to inhibit ingress of dirt into the collar 428.