GB2411432A

GB2411432A - Fastener for linear elements comprising expandable boss

Info

Publication number: GB2411432A
Application number: GB0404452A
Authority: GB
Inventors: Gino Di-Mola
Original assignee: ADVANCED BOLTING SOLUTIONS Ltd
Current assignee: ADVANCED BOLTING SOLUTIONS Ltd
Priority date: 2004-02-28
Filing date: 2004-02-28
Publication date: 2005-08-31
Also published as: GB0404452D0

Abstract

A fastener for fixing linear elements, for example, security welded wire mesh fencing panels to hollow structural steel uprights. The fastener comprises a cap (1) having parallel channels (2) and a cylindrical boss (4) which extends through a circular drilled aperture in the structural steelwork outer face. The cap (1) is placed in use over the side upright portions (11) of a pair of fencing panels, and a pin (6) is forced into a stepped bore (5) through the cap (1) and boss (4). The pin (6) forces apart the elements of the segmented end portion of the boss (4) to create a rivet head within the interior of the structural steelwork, holding the fastener in place. The pin (6) can be forced fully into the stepped bore (5) by impact with a hammer or by screwing. Assembly is rapid and is attainable from one side only of the fencing panels and structural steelwork. No bolt heads are required on the far side of the hollow structural steelwork, which provides added security against unauthorised removal of the fastener. The same fastener with one or more channels (2) can be used to secure other wire elements such as electrical cabling.

Description

241 1 432 - 1

TITLE

Fastener for security fencing

DESCRIPTION

Field of the Invention

The invention relates to fasteners for connecting linear elements to hollow structural steelwork. The linear elements may be wires or cables. The invention is particularly but not exclusively suited to the connection of welded wire mesh security fencing panels to hollow structural steel uprights or fence o posts.

Background Art

Cable clamps for securing electrical cables to wooden structural members are well known, and comprise a cap in which is defined a channel for straddling the cable, and mounting portion offset to one side of the cap and having an aperture therethrough into which a nail can be driven to secure the fastener to the timber structural member while the cap straddles the cable and holds it in position.

A similar but larger and more substantial fastener has been proposed for securing welded mesh fencing panels to hollow structural steelwork such as fence posts. The cap has formed therein one or more channels for straddling one or more wire strands of the welded mesh security fencing panel, or for straddling wire strands of two adjacent security fencing panels. An aperture is Q5 formed through a body portion of the cap, and in use a coach bolt or machine bolt is passed through that aperture and through aligned apertures formed on front and back faces of the hollow structural steelwork. The fastener is retained in position by a nut engaging the bolt as it passes to the reverse side of the structural steelwork. One disadvantage of this known fastener for securing fencing panels is that the securing bolt must pass completely through both front and back walls of the hollow structural steelwork, so that preparation of the steelwork requires the drilling of two holes; if those holes - 2 are spaced apart by more than about 5 cm (resulting from the use of structural steelwork with a width of more than 5 cm) then it can be time consuming during installation to align the fixing bolt with the fixing hole formed in the reverse wall of the structural steelwork. A nut must be positioned on the fixing bolt as it passes through that reverse wall, and in many installations this will require a two-person assembly team because one person assembling the fastener from the front of the aligned fencing panels might not be able to reach the screw threaded portion of the fixing bolt as it passes to the rear of the structural steelwork. Finally, the nut must be fastened from the rear and doing so will impart a rotational torque on the fastener cap and body to the front of the fencing panels, so that either one member of the installation team must remain at the front of the fencing panels in order to hold the fastener against rotation as the nut is tightened, or a non-circular hole must be formed in the front face of the structural steelwork, to cooperate with a non-circular protrusion on the fastener to key the fastener to the structural steelwork and prevent rotation during tightening of the bolt.

It is an object of the invention to provide a fastener which avoids the above disadvantages of the prior art, and which can be secured in place from one side only of the structural steelwork. It is also desirable that the fastener should be capable of connection through a single circular hole formed in the front face only of the hollow structural steelwork.

The invention :5 The invention provides a fastener having the features of claim 1.

If the cap has formed therein a single channel only for straddling a single linear element to be fastened, then it is suitable for securing in position electrical cables in single lengths. If the cap has formed therein two parallel channels one on each side of the cylindrical boss, then it is suitable for securing in position two parallel runs of electric cables, or alternatively two adjacent panels of welded wire mesh security fencing. The remainder of this - 3 specification will discuss the embodiment of the invention in which the fastener cap has two such parallel channels, although it is to be understood that this particular description is not intended to limit the scope of the invention to that one embodiment.

Drawings Figures 1 and 2 are perspective views from above and below respectively of a fastener according to the invention, with the pin removed from its stepped bore in the cap for illustrative purposes only; Figure 3 is a horizontal section taken looking down on a fastener according to Figures 1 and 2, the fastener being positioned alongside a hollow rectangular steel fence post.

Figure 4 is a section similar to that of Figure 3 but with the fastener engaging the fence post ready to hold in position two adjacent wire mesh security fence panels, each identified by a single strand only of a wire upright, shown in section; and Figure 5 is a section similar to that of Figure 4 but with the assembly complete.

Referring first to Figures 1 and 2, the fastener of the invention comprises a cap 1 having formed therein two parallel channels 2 each sized to straddle either a wire upright of a welded mesh security fencing panel or a flat covered electrical cable. In addition, two transverse channels 3 are formed in the cap, each communicating with an associated one of the channels 2 for straddling longitudinal spacer elements of a welded wire mesh security fencing panel.

A cylindrical boss 4 extends from the rear face of the cap 1. A stepped bore 5, identified more clearly in Figure 3, passes centrally through the cap 1 and cylindrical boss. As seen in Figure 3, the stepped bore 5 has a larger diameter - 4 as it passes through the cap 1 and a smaller diameter as it passes through the boss 4, with the transition between the two diameter portions of the bore being formed as a taper.

Another component of the fastener of the invention is a pin 6 which is a close fit in the larger diameter portion of the bore 5.

The boss 4 is divided into four quadrants by two diametrical slots 7 formed through the wall of the boss. The division of the boss 4 into quadrants permits those quadrants to splay apart, increasing the effective diameter of the boss 4 when the pin 6 is forced fully into the stepped bore 5.

The fastener of the invention can be used to secure linear elements to hollow structural steelwork as illustrated in Figures 3 to 5. In Figures 3 to 5 the hollow structural steelwork carries the reference number 10 and is typically a hollow rectangular fence post for supporting welded wire mesh security fencing. Only two structural upright wire portions 11 of the security fencing are shown in Figures 3 to 5. A circular fixing hole 12 is drilled through the front face only of the fence post 10, the hole 12 having the same diameter as the external diameter of the boss 4 of the fastener of the invention.

To secure two fence panels in place, a fastener is placed over the end vertical structural uprights 11 of two adjacent fence panels, and the boss 4 of the fastener is inserted into the predrilled hole 12 in the fence post 10. The pin 6 is then tapped into place with a hammer, forcing it into the stepped bore in the direction of the bold arrow A of Figure 4. The pin 6 forces apart the four quadrant sections of the boss 4, so that they splay apart behind the hole 12 in the fence post 10 to form a rivet head preventing the fastener from moving away from the fence post. Assembly is rapid, and can be achieved working from the front only of the fence panels and fence posts. Moreover the fencing is secure, as there are no bolt heads to be removed by a determined intruder. - 5

If it were desired to remove the fastener, then that could be achieved by pushing the pin 6 completely through the fastener to the inside of the fence post 10, using a punch of smaller diameter than the pin 6. The fastener could then be removed by pulling the expanded boss 4 back through the hole 12 in the fence post. If, however, it were desired to manufacture a fastener according to the invention that could not be removed in this way, then all that would be necessary would be to provide the pin 6 with a head which would be received in an annular recess around the entrance of the stepped bore 5 into the cap 1, so that when the pin is forced fully home as in Figure 5, it lies flush 0 with the front face of the cap 1 but cannot be pushed fully through the bore because of the obstruction caused by the head of the pin.

It will be apparent that many variations are possible within the scope of the invention. The pin 6 may be smooth-sided, or may be ribbed, the ribbing making it more difficult for the pin to be pushed completely through the stepped bore for removal of the fastener. Alternatively the pin 6 and the larger diameter portion of the stepped bore 5 may be formed with complementary screw threads, so that the pin 6 is forced into the bore not by impact with a hammer but by turning it to advance it along the screw thread. The turning moment may be achieved by a screwdriver recess formed in the exposed end of the pin 6, this screwdriver recessing being either a conventional slot or cross or a configuration enabling the pin 6 to be turned only using a specially configured security headed screwdriver or similar turning tool. The transverse recesses 3 are optional, and are in fact shown only in phantom in Figures 3 to 5. The cap 1 and boss 4 may be formed in one piece as illustrated, or may be made in two parts, with the cap 1 being formed by extrusion of a continuous length of, for example, aluminium and the boss 4 being formed as a protruding portion of a hollow headed cylinder inserted into a through hole drilled through the cap 1. The formation of such a hollow cylinder is indicated in phantom lines in Figure 5 only. - 6

The pin 6 as illustrated in the drawings is formed with a square end, and the stepped bore 5 is formed with a tapered shoulder connecting the larger and smaller diameter portions of the bore 5. The taper enables the pin to force the segments of the boss 4 to splay apart as the pin is forced down the bore 5.

The same cam action between the pin and the bore can be obtained when the pin 6 is tapered at is leading end and the shoulder between the larger and smaller diameter portions of the bore 5 is a square shoulder. For the most efficient camming apart of the segments of the boss 4, however, both the leading end of the pin 6 and the shoulder between the larger and smaller diameter portions of the bore 5 should be tapered, preferably with cooperating taper angles.

Claims

CLAIMS: 1. A fastener for connecting linear elements to hollow structural

steelwork, comprising: a cap having formed therein one or more channels for straddling the linear element or elements to be fastened; a cylindrical boss extending from the cap for passing through a cylindrical aperture formed in an outer wall of the structural steelwork; a stepped bore formed centrally through the cap and cylindrical boss, with the portion of the stepped bore passing through the cap having a larger internal diameter than at least an end portion passing through the boss; at least two radial slots formed in the wall of the boss distal to the cap to divide the said wall into axial segments; and a pin having substantially the same external diameter as the larger internal diameter of the stepped bore, whereby when the pin enters the end portion of the stepped bore from the larger internal diameter portion it causes the segments to splay outwardly within the hollow interior of the structural steelwork to retain the fastener on the structural steelwork.
2. A fastener according to claim 1, wherein the pin is tapered at its leading end, to cause the axial segments to splay apart by the cam action of the tapered end as the pin enters the end portion of the stepped bore.
3. A fastener according to claim 1 or claim 2, wherein the stepped bore has a tapered shoulder between its larger and smaller diameter portions, to z5 cause the axial segments to splay apart by the cam action of the leading end of the pin on the tapered shoulder as the pin enters the end portion of the stepped bore.
4. A fastener according to any preceding claim, wherein the pin is a smooth sided cylindrical pin which can be forced into the end portion of the stepped bore by impact with a hammer. - 8
5. A fastener according to any of claims 1 to 3, wherein the pin has a ribbed outer surface to increase its resistance to axial movement down the bore as it is forced into the end portion of the bore by impact with a hammer.
6. A fastener according to any of claims 1 to 3, wherein the pin and the larger diameter portion of the stepped bore have cooperating screw threads, so that rotation of the pin causes it to be forced axially into the end portion of the stepped bore
7. A fastener according to claim 6, wherein the pin has a shaped slot or recess at its exposed end for cooperation with a security headed screwdriver or similar turning device.
8. A fastener according to any preceding claim, wherein the pin is provided at its exposed end with an enlarged head, and the stepped bore is provided with an annular cavity for receiving the head of the pin so that the head lies flush with the outer face of the cap when forced fully into the stepped bore, and is prevented by the head of the pin from passing completely through the stepped bore.
9. A fastener according to any preceding claim, wherein the cap has formed therein of mutually parallel pair of the said channels one on each side of the cylindrical boss, for retaining two mutually parallel linear elements such as two parallel electrical cables or the outer wire uprights of two welded wire mesh security fencing panels to be secured in place by the fastener.
10. A fastener as described herein with reference to the drawings.