GB2091368A

GB2091368A - Drive anchor

Info

Publication number: GB2091368A
Application number: GB8101833A
Authority: GB
Original assignee: Tucker Fasteners Ltd
Current assignee: Tucker Fasteners Ltd
Priority date: 1981-01-21
Filing date: 1981-01-21
Publication date: 1982-07-28
Also published as: FR2498227A1; FR2498227B1; GB2091368B

Abstract

A nylon drive anchor of the kind which has legs 14 spread into frictional engagement with the wall of a bore by driving into it a nail-like expansion member 30, has thick stepped portions 22 at the free ends of its legs 14 to improve its resistance to pull-out, especially under shock loading, when set in lightweight aerated concrete, and a weakened portion 20 which will collapse on driving in the nail 30 to allow the countersunk head to become seated flush with the surface of plasterboard P. <IMAGE>

Description

SPECIFICATION Drive anchor This invention is concerned with drive anchors of the kind having a tubular plastics body and a nail-like expansion member.

Many varieties of drive anchors of the kind referred to are known, some of which are adapted for special purposes. For example, for securing dry linings of plasterboard to masonry or concrete walls, it has been proposed to use an anchor of which the plastics body has a head which is countersunk in shape so that it causes surface paper of the plasterboard around the hole in which the anchor is inserted to be constrained by the head of the body without tearing.It has also been proposed, in an anchor of which the plastics body has a head which it is desired shall be pressed firmly against the surface of the structure in which the anchor is being instailed, or which is to clamp an article that is being secured firmly against such surface, to provide the plastics body with a short portion of reduced wall thickness where it can collapse longitudinally after the legs of the anchor have been expanded into gripping engagement with the wall of the bore in which the anchor has been inserted.

A problem has arisen, however, in that, where it is desired to have a supply of anchors which can be used for a variety of purposes, including those with the aforementioned features, there is a risk, with legs and expansion members of conventional configuration, that the anchor will work loose if the material into which it is inserted is not strong and dense, especially if the anchor is attempting to clamp an article (e.g. a batten) which is subjected to shock (e.g. by hammering an anchor being installed at another part of the batten).

Accordingly, it is an object of the invention to provide an improved drive anchor for use selectively in a variety of applications.

The invention provides, in one of its several aspects, a drive anchor comprising a plastics tubular body with a countersunk head at one end and two legs separated by a diametrical slot extending from the other end, the body having a short length of reduced wall thickness at a locality between the head and the legs, each leg having at its free end a thick portion which provides an external step facing the head and an external surface which tapers from the step towards the free end of the body, each step being half as wide as the slot between the legs.

Preferably, in an anchor in accordance with the invention the said slot extends for about a third of the length of the body, and the body has a head with a circular recess in it of larger diameter than the outside diameter of the body below the head.

An anchor in accordance with the invention preferably also comprises an expansion member in the form of a nail with annular ridges on its shank and a flat head of nearly the same diameter as the recess in the head of the anchor. Alternatively, the expansion member may be a screw-threaded nail having a flat head with a slot or recess for the screwdriver, the head, where the body of the anchor has a recess in its head, being of nearly the same diameter as the recess in the head of the body.

There now follows a detailed description, to be read with reference to the accompanying drawing, of a drive anchor in accordance with the invention and selected to illustrate the invention. It will be realised that this illustrative anchor has been selected for description by way of example and not of limitation of the invention.

In the accompanying drawing: Figure 1 is a view in longitudinal section of the illustrative drive anchor in readiness for setting in a hole into which it is being inserted; and Figure 2 is a view similar to Figure 1 after the anchor has been set.

The illustrative anchor comprises a plastics tubular body 10 with a countersunk head 12 at one end and two legs 14 separated by a parallelsided diametrical slot 1 6 extending from the other end for about one third of the length of the body.

The part of the body 1 0 between the head and the slot has a bore 1 8 of uniform diameter, except where it progressively decreases to merge with the slot 16, but the outer diameter, while uniform over most of its length, is less over a short distance (at a locality about a third of the distance from the head) to provide a short length 20 of reduced wall thickness. The head 12 is flat-topped with a circular recess 28 of larger diameter than the outside of the body 1 0 and deep enough to receive the head of a flat-headed nail.

Each leg 14 of the body 10 of the illustrative anchor has, at its free end, a thick portion 22 which provides an external step 24 facing the head 12 and an external surface 26 which tapers from the step towards the free end of the legs.

Each step 24 is half as wide as the slot 16 where it extends between them.

The illustrative anchor also comprises an expansion member in the form of a nail 30 with annular ridges 32 on its shank and a flat head 34 of nearly the same diameter as the recess in the head 1 2 of the body. The anchor is assembled by inserting the nail 30 into the body 10 until the shank, which may be pointed (as shown) reaches the slot 16.

The illustrative anchor may be used, as shown in Figures 1 and 2, to secure plasterboard P to a brick or concrete wall W by first drilling a hole H of a diameter to admit the body 10 and then squeezing the portions 22 together so that, because the slot 1 6 is as wide as the two steps 24 together, the hole body can be introduced into the hole H up to the head 12. To ensure that the nail 30 does not prematurely advance along the body 10, but retains the relative position shown in Figure 1 until the body of the anchor has been fully inserted in the hole H, the body has two integral restraining ties (not shown) bridging the legs 14 a short distance from the end of the bore 1 8, between which the point of the nail can pass only with extra force.

When the illustrative anchor inserted as shown in Figure 1, the nail 30 is subjected to a blow or blows from a hammer which cause it to force its way past the retaining ties and between the legs 14, forcing them apart into tight engagement with the wall material. With the legs 14 thus anchored, the short length 20 of the body collapses longitudinally allowing the countersunk head 12 of the body to become seated flush with the plasterboard P, which it does without tearing the retaining paper usually provided on its surface.

The head 34 of the nail also lies flush with the plasterboard P because it is fully accommodated in the recess 28.

The ridges 32 on the nail 30 preferably extend as far along its shank as the legs 14 so that material of the legs may be formed into grooves between the ridges the more firmly to secure the nail. The ridges do not need to extend so far along the nail as shown in Figures 1 and 2. The nail head 34 being larger than the external diameter of the body 10 ensures temporary retention of the plasterboard in the event of fire even if the body 10 at or near the head were to melt quickly.

Where the material of the wall W or floor is of lightweight aerated concrete or like material of less compressive strength than ordinary concrete or brick, resistance to pull out of the body from the hole is high even if the article, which may be a batten, being secured to the wall or floor results in the anchor being subjected to sudden shocks as another anchor is securing another part of the batten, by virtue of the pronounced steps 24 which panetrate the wall of the bore.

The body of an anchor in accordance with the invention may be made of any suitable plastics material, preferably a thermoplastic material which can be injection moulded, e.g. nylon.

Claims

1. A drive anchor comprising a plastics tubular body with a countersunk head at one end and two legs separated by a diametrical slot extending from the other end, the body having a short length of reduced wall thickness at a locality between the head and the legs, each leg having at its free end a thick portion which provides an external step facing the head and an external surface which tapers from the step towards the free end of the body, each step being half as wide as the slot between the legs.

2. An anchor according to claim 1 in which said slot extends for about one third of the length of the body.

3. An anchor according to either one of the preceding claims in which the head has a circular recess of larger diameter than the outside diameter of the body.

4. An anchor according to any one of the preceding claims comprising also an expansion member in the form of a nail with annular ridges on its shank and a flat head of nearly the same diameter as the recess in the head of the body of the anchor.

5. An anchor according to any of claims 1 to 3 comprising also an expansion member with a screw-threaded nail having a flat head with a slot or recess for a screwdriver the head having nearly the same diameter as the recess in the head of the plastics body of the anchor.

6. A drive anchor comprising a plastics tubular body substantially as hereinbefore described with reference to the drawing.

7. A method of securing dry linings to walls of lightweight aerated concrete wherein there are used drive anchors according to any one of the preceding claims.