GB2127889A - Clamp - Google Patents

Abstract

The clamp is of a two part type used for clamping a lightning conductor tape in a closed rectangular channel (13) defined between the two parts. One part (11) has an aperture for receiving a fastener e.g. a screw to mount the part on a surface. This part has a pair of sockets (15) each of which co-axially supports a spigot (20) by means of a frangible web (21). The other part (12) has studs (23) which tightly fit in the sockets. Each stud has a recess (26) in which a corresponding spigot (20) is an interference fit. Under impact to engage the studs in the sockets, the spigots engage in the studs and tend to expand them to provide a secure connection. <IMAGE>

Description

SPECIFICATION Clamp This invention relates to a clamp of the type made of plastics material and having two parts which tightly fit together, one of the parts being adapted for mounting on a surface.

Such clamps may be used, for example, for securing conductors or cables. The clamp of this invention is especially useful for clamping a rectangular section tape as used for a lightning conductor. A clamp for this purpose is disclosed in U.K. Patent Specification 1208437. This clamp has a first part provided with a screw aperture for screwing of the part to a wall. This first part also has sockets and the second part has studs which are a press fit in the sockets, so that the two parts can be secured together. In the interengaged position of the parts, a slot is defined between the two parts and this slot receives the tape. This clamp is very simply fitted but it is possible for the two parts to come adrift, especially under relatively low separating forces. The present invention provides an improved clamp.

In accordance with this invention, there is provided a clamp moulded from plastics material and having two engageable parts which define a clamping formation therebetween, the first part being adapted for mounting on a surface, one of the parts having at least a pair of spaced sockets and the other part having studs which closely fit into the sockets, each stud being provided with an axial recess and the part with the sockets also having spigots co-axial with the sockets, each spigot being an interference fit in the corresponding recess.

With this arrangement, the spigots tend to expand the studs to provide a very tight fit of each stud in its socket.

Each spigot may be housed within the corresponding socket, and project from the base of the socket. It is, however, preferred that the sockets are provided on the first part, each socket is open at both opposite ends and the corresponding spigot is supported by a frangible web, whereby during securance of the two parts, the web is broken and the spigot engages the surface on which the first part is mounted.

The broken remains of each frangible web preferably defines a shoulder and the corresponding stud preferably has a projection which snap-engages behind the shoulder.

Each recess and each spigot are preferably tapered, so as to provide the interference fit of each spigot in the corresponding recess.

Reference is now made to the accompanying drawings, wherein:~ Figure 1 is a perspective view of parts of a clamp according to the invention, prior to their securance together; Figure 2 is a sectional view of the clamp parts before securance together; and Figure 3 is a sectional view of the clamp parts after securance together.

The clamp shown comprises two parts, moulded of plastics material, including a first part 11 and a second part 12. The first part is an elongate block having a top face 16 provided with a central, transverse channel 13 in the bottom of which is a bevelled aperture 14 for receiving a screw to mount the part on a surface, such as a wall, with a bottom face 17 of the part in contact with the wall. The second part is also elongate and can be mounted on the first part to close the top of the channel 13, so as to define a slot through which a rectangular section tape will pass, in use, with the tape being clamped between the parts.

The first part 11 has a pair of sockets 15, each provided in an end portion of the part and extending axially parallel to the screw aperture 14. Each socket is open at both opposite faces of the first part. A spigot 20 is located in each socket, so as to project from the socket at the top face 16, the other end of the spigot terminating within the socket and spaced from the bottom face 17 of the part.

Each spigot is supported by an encircling frangible web 21 within the socket, but adjacent the top face 16. Each spigot has a taper providing an increasing diameter from the projecting portion to the portion terminating within the socket.

The face 19 of the second part 12, which face closes the channel 13, is provided with a pair of studs 23 which closely fit into the sockets 15. Each stud has a recess 26, which extends through the opposite face 18 of the part. Each recess 26 is tapered complementary to a corresponding spigot 20, such that the spigot is a tight interference fit in the recess. Each stud has an annular projection 27.

In use, the first part is secured to a surface by means of the screw aperture 14 with the bottom face 17 against the surface. Tape is passed along the channel 13. The second part is then hammered onto the first part to secure the parts together and to clamp the tape in the channel. The studs 23 enter the sockets 15 as the spigots 20 enter the recesses 26.

The frangible webs 21 are broken and the spigots may impart against the surface on which the first part is mounted. The studs are forced over the spigots and are expanded diametrically to provide a tight fitment between the studs and the sockets. In the clamping position, each spigot extends from the bottom face 17 of the first part to the top face 18 of the second part.

The broken web 21 remains to define a shoulder part which the annular projection 27 of the corresponding stud snap-engages. The expansion of the stud also reduces the risk of the stud being pulled out past the shoulder.

Claims (7)

1. A clamp moulded from plastics material and having first and second engageable parts which define a clamping formation therebetween, the first part being adapted for mounting on a surface, one of the parts having at least a pair of spaced sockets and the other part having studs which closely fit into the sockets, each stud being provided with an axial recess and the part with the sockets also having spigots co-axial with the sockets, each spigot being an interference fit in the corresponding recess.

2. A clamp according to Claim 1, wherein one of the parts has an open shallow channel which is closed by the other part to define a clamping formation for receiving a metal light- ning conductor tape.

3. A clamp according to Claim 2, wherein the part having the sockets is provided with the channel, which is located between the sockets.

4. A clamp according to any preceding claim, wherein the first part is provided with the sockets and each socket is open at both opposite ends, the corresponding spigot being supported by a frangible web in the socket.

5. A clamp according to Claim 4, wherein the web is formed, so as to define a shoulder in the socket, after the web has been broken by engagement of the corresponding stud in the socket, the corresponding stud having a projection which snap-engages behind the shoulder.

6. A clamp according to any preceding claim, wherein each recess and each spigot are tapered so as to provide for the interference fit of each spigot in the corresponding recess.

7. A clamp constructed substantially as herein described with reference to the accompanying drawings.