Fastener

Abstract

A fastener (10) comprising a shaft (12) and a head (14). The head (14) comprises a first portion (16) and a second portion (17) and the shaft extends from a first side surface (20) of a first portion (16) of the head (14). Projections (24) are provided on a second side surface of the second portion of the head and recesses (26) are provided the second side surface (21) of the first portion (16). The projections (24) and the recesses (26) are each arcuate in shape and taper downwardly in height from first ends to second ends such that the projections (24) are received in the recesses (26) in a press fit manner. The second portion (17) of the head (14) disengages from the first portion (16) when the fastener (10) is rotated outwardly.

Description

[0001] “Fastener”

[0002] Field of the Invention

[0003]

[0001] The present invention relates to a fastener suitable for securing together sheet material panels.

[0004] Background to the Invention

[0005]

[0002] Sheds are typically constructed of metal sheeting panels fixed to a frame structure. The panels are often fixed to the frame with self drilling screws, such as those commonly referred to as Tek screws. These screws are usually simply drilled through the panels from the outside into the frame members.

[0006]

[0003] As sheds are often used to store equipment of significant value, it is not uncommon for sheds to be targets for theft. While locking the doors of such sheds is relatively easy, a common method for gaining access to a shed is to simply remove the screws securing the panels in place and accessing the shed through the removed panel.

[0007]

[0004] The present invention relates to a fastener suitable for use in securing panels of a shed or other building structure. The fasteners are aimed at being easy to install but difficult to remove to reduce the likelihood of others gaining unauthorised access to the shed through removal of the panels.

[0008] Summary of the Invention

[0009]

[0005] According to one aspect of the present invention there is provided a fastener comprising: a shaft having an external thread; and a head including a first portion and a second portion, the first portion including a first side surface from which the shaft extends and a second side surface, and the second portion of the head including a first side surface adjacent the first portion of the head and a second side surface having a tool engagement portion to be engaged with a tool for rotation of the fastener; projections provided on the second side surface of the first portion of the head or the first side surface of the second portion of the head; and recesses provided on the other of the second side surface of the first portion of the head or the first side surface of the second portion of the head; wherein the projections and the recesses are each arcuate in shape and taper downwardly in height from first ends to second ends thereof and wherein the projections include first and second side walls extending between the first and second ends of the projections and the recesses include first and second side walls extending between the first and second ends of the recesses such that the first and second side walls of the projections engage with the first and second side walls of the recesses respectively in a press fit manner when the projections are received in the recesses so that rotation of the second portion of the head in a first direction rotates the first portion of the head and the shaft and rotation of the second portion in a second direction causes the first and second portions of the head to disengage.

[0010]

[0006] Preferably the projections taper inwardly toward an outer surface thereof and the recesses taper inwardly towards an inner surface thereof.

[0011]

[0007] Preferably the projections each include a first end surface at the first end thereof and the recesses each include a first end surface at the first end therefore such that the first end surface of each of the projections engages with the first end surface of the corresponding recess when the head is rotated in the first direction.

[0012]

[0008] Preferably the projections taper downwardly in height from the height of the first end surface of the projection at the first end of the projection to zero at the second end of the projection the recesses taper downwardly in depth from the depth of the first end surface of the recess at the first end of the recess to zero at the second end of the recess.

[0009] Preferably the projections and recesses are arcuate in shape and are arranged circumferentially around a longitudinal axis of the shaft.

[0013]

[0010] In one embodiment, the projections are provided on the second portion of the head and the recesses on the first portion of the head.

[0014]

[0011] Preferably an adhesive is provided to secure the projections within the recesses such that the adhesive bond between the projections is broken when the fastener is rotated in the second direction.

[0015] Brief Description of the Drawings

[0016]

[0012] The invention will now be described, by way of example, with reference to the following drawings, in which:

[0017]

[0013] Figure 1 is an upper perspective view of a fastener in accordance with the present invention;

[0018]

[0014] Figure 2 is a lower perspective view of the fastener of Figure 1 ;

[0019]

[0015] Figure 3 is a side view of the fastener of Figure 1 ;

[0020]

[0016] Figure 4 is an exploded view of the fastener of Figure 1 ;

[0021]

[0017] Figure 5 is an exploded view of the fastener of Figure 1 showing the underside of the head;

[0022]

[0018] Figure 6 is an upper perspective exploded view of the fastener of Figure 1 showing internal features;

[0023]

[0019] Figure 7 is a first side view of the fastener of Figure 1 showing internal features;

[0024]

[0020] Figure 8 is a second side view of the fastener of Figure 1 showing internal features; and

[0025]

[0021] Figure 9 is a side cross sectional view of the fastener of Figure 1 . Detailed Description of Preferred Embodiments

[0026]

[0022] Referring to the Figures, there is shown a fastener 10 comprising a shaft 12 and a head 14. The shaft 12 includes an external thread 18 such that the shaft 12 may be screwed into a panel, such as a sheet metal panel of the type used on sheds. A distal end of the shaft 12 may be shaped such that the fastener 10 comprises a self-drilling fastener of the type commonly referred to as Tek screws.

[0027]

[0023] The head 14 of the fastener 10 is connected to an end of the shaft 12. The head 14 comprises a first portion 16 and a second portion 17. The first portion 16 of the head 14 is integrally formed with the shaft 12 such that the shaft 12 extends outwardly from a first side surface 20 of the first portion 16 of the head 14. The first portion 16 of the head 14 is generally circular in shape in the embodiment shown and includes a second side surface 21 opposite the first side surface 20.

[0028]

[0024] The second portion 17 of the head 14 is attachable to the second side surface 21 of the first portion 16. The second portion 17 includes a first side surface 30 and a second side surface 31 . The first side surface 30 of the second portion 17 is connected to the second side surface 21 of the first portion 16. The second side surface 31 of the second portion 17 of the head 14 includes a tool engagement 22 such that the tool engagement 22 may be engaged by a rotating tool. In the embodiment shown, the tool engagement 22 comprises a hex projection 23 to be received in a hex shaped socket engaged with a tool such as a cordless drill.

[0029]

[0025] The first and second portions 16 and 17 are secured together during construction of the fastener 10. The first and second portions 16 and 17 are secured such that rotation of the fastener 10 in a first rotational direction maintains the connection between the first and second portions 16 and 17 such that the shaft 12 may be drilled into the panel. Rotation of the fastener 10 in a second opposite direction however causes the second portion 17 of the head 14 to disengage from the first portion 16.

[0026] The first side surface 30 of the second portion 17 includes a plurality of projections 24. The second side surface 21 of the first portion 16 includes a plurality of recesses 26. The number and shape of the recesses 26 corresponds to the number and shape of the projections 24 such that the projections 24 on the second portion 17 of the head 14 may be received into corresponding recesses 26 on the first portion 16 of the head 14. While the fastener 10 shown includes projections 24 on the second portion 17 and recesses 26 in the first portion 16, it will be appreciated that the projections 24 may be provided on the first portion 16 and the recesses 26 on the second portion 17.

[0030]

[0027] The projections 24 are offset inwardly from a peripheral edge of the first side surface 30 of the second portion 17 of the head 14. The recesses 26 are also offset inwardly from a peripheral edge of the second side surface 21 of the first portion 16 of the head 14

[0031]

[0028] Each of the projections 24 is arcuate in shape and the projections 24 are arranged circumferentially around a longitudinal axis of the shaft 12. The height of each of the projections 24 tapers downwardly from a first end 28 to a second end 29. Each of the recesses 26 is also arcuate in shape and arranged circumferentially around the longitudinal axis of the shaft 12. The depth of each of the recesses 26 also decreases from a first end 38 to a second end 39. The shapes of the recesses 26 are complementary to the shapes of the projections 24 such that the first ends 28 of the projections 24 are received in the first ends 38 of the recesses 26 and the second ends 29 of the projections 24 received in the second ends 39 of the recesses 26.

[0032]

[0029] The projections 24 each include a first end surface 44 at the first end 28 and an outer surface 40 which extends from the first end surface 44 to the first side surface 30 of the second portion 17 of the head 14. The projections 24 therefore taper downwardly in height from the height of the first end surface 44 at the first end 28 to zero at the second end 29. The recesses 26 each include a first end surface 46 at the first end 38 thereof and an inner surface 42 which extends from the first end surface 46 to the second side surface 21 of the first portion 16 of the head 14. The recesses 26 therefore taper downwardly in depth from the depth of the first end surface 46 at the first end 28 to zero at the second end 39.

[0033]

[0030] Each of the projections 24 includes first and second side walls 34 and 35 extending between the first and second ends 28 and 29. The first and second side walls 34 and 35 taper downwardly in height from the first ends 28 to the second ends 29 and are arcuate to define the arcuate shape of the projections 24. Each of the recesses 26 also includes first and second side walls 36 and 37 extending between the first and second ends 38 and 39. The first and second side walls 36 and 37 of the recesses 36 taper downwardly in height from the first ends 38 to the second ends 39 are arcuate to define the arcuate shape of the projections 24.

[0034]

[0031] The projections 24 and the recesses 26 are provided with an engagement mechanism such that the projections 24 engage with the recesses 26 to secure the projections 24 within the recesses 26 during construction of the fastener 10. The engagement mechanism includes a press fit arrangement such that the projections 24 are pressed into the recesses 26 and secured in place by friction. That is, the first and second side walls 34 and 35 of the projections 24 engage with the first and second side walls 36 and 37 respectively of the recesses 26 in a press fit manner. The projections 24 taper inwardly toward the outer surface 40 thereof and the recesses 26 taper inwardly towards the inner surface 42 thereof such that the side walls 34 and 35 of the projections 24 engage with the side walls 36 and 37 of the recesses.

[0035]

[0032] An adhesive may also be provided to further secure the projections 24 within the recesses 26 such that the adhesive bond between the projections 24 and the recesses 26 may be broken during use of the fastener 10.

[0036]

[0033] The fastener 10 may also include a standard flexible washer 32 of a suitable rubber or polymer material to be received around the shaft 12.

[0037]

[0034] In use, the faster 10 is engaged by a rotating tool and drilled into a panel of the structure in the manner of a standard self-drilling screw. The first ends 28 of the projections 24 engage with the first ends 38 of the recesses 26 such that force applied to the second portion 17 of the head 14 is transferred to the first portion 16 to rotate the shaft 12. If the head 14 is engaged by a rotating tool and rotated in an opposite direction, the tapered outer surfaces 40 of the projections 24 will slide along the tapered inner surfaces 42 of the recesses 26 and the force of rotation will be sufficient to break the bond between the projections 24 and the recesses 26 such that the second portion 17 of the head 14 disengages from the first portion 16 of the head 14.

[0038]

[0035] The fastener 10 can therefore be used to secure panels of a structure to the frame in a known manner. However, if someone were to attempt to remove the fasteners 10 in order to gain access to the structure, the second portion 17 of the head 14 engaged by a tool would simply break free and the fastener 10 would remain in place. It is expected that fasteners 10 in accordance with the present invention may only need to be used in limited numbers in some locations on a structure and standard fasteners could be used for the remainder of the structure.

[0039]

[0036] It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention.

Claims

Claims1. A fastener comprising: a shaft having an external thread; and a head including a first portion and a second portion, the first portion including a first side surface from which the shaft extends and a second side surface, and the second portion of the head including a first side surface adjacent the first portion of the head and a second side surface having a tool engagement portion to be engaged with a tool for rotation of the fastener; projections provided on the second side surface of the first portion of the head or the first side surface of the second portion of the head; and recesses provided on the other of the second side surface of the first portion of the head or the first side surface of the second portion of the head; wherein the projections and the recesses are each arcuate in shape and taper downwardly in height from first ends to second ends thereof and wherein the projections include first and second side walls extending between the first and second ends of the projections and the recesses include first and second side walls extending between the first and second ends of the recesses such that the first and second side walls of the projections engage with the first and second side walls of the recesses respectively in a press fit manner when the projections are received in the recesses so that rotation of the second portion of the head in a first direction rotates the first portion of the head and the shaft and rotation of the second portion in a second direction causes the first and second portions of the head to disengage.

2. A fastener in accordance with claim 1 , wherein the projections taper inwardly toward an outer surface thereof and the recesses taper inwardly towards an inner surface thereof.

3. A fastener in accordance with claim 1 , wherein the projections each include a first end surface at the first end thereof and the recesses each include a first end surface at the first end therefore such that the first end surface of each of the projections engages with the first end surface of the corresponding recess when the head is rotated in the first direction.

4. A fastener in accordance with claim 2 or 3, wherein the projections taper downwardly in height from the height of the first end surface of the projection at the first end of the projection to zero at the second end of the projection the recesses taper downwardly in depth from the depth of the first end surface of the recess at the first end of the recess to zero at the second end of the recess.

5. A fastener in accordance with claim any one of the preceding claims, wherein the projections and recesses are arcuate in shape and are arranged circumferentially around a longitudinal axis of the shaft.

6. A fastener in accordance with any one of the preceding claims, wherein the projections are provided on the second portion of the head and the recesses on the first portion of the head.

7. A fastener in accordance with any one of the preceding claims, wherein an adhesive is provided to secure the projections within the recesses such that the adhesive bond between the projections is broken when the fastener is rotated in the second direction.

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