GB1574978A

GB1574978A - Expanding wall plug

Info

Publication number: GB1574978A
Application number: GB1597277A
Authority: GB
Original assignee: MAECHTLE F
Current assignee: MAECHTLE F
Priority date: 1976-07-29
Filing date: 1977-04-18
Publication date: 1980-09-17
Also published as: IT1085064B; FR2360007B3; FR2360007A1

Description

(54) EXPANDING WALL PLUG (71) I, FRITZ MACHTLE, a German citizen, of Jahnstr. 4, D-7015 Korntal Munchingen 1, German Federal Republic, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to an expanding wall plug, particularly for use in aerated concrete and similarly elastic structural material.

Expanding wall plugs are known which comprise a screw-threaded shaft encircled by at least two expanding sleeves disposed end-toend on the shaft and having open-ended longitudinal slots in their leading ends, said sleeves being clamped between a clamping member threadedly engaging, or integral with, the rear end of the shaft and a cone member threadedly engaging the leading end of the shaft and having a conical surface projecting partially within the adjacent expanding sleeve, so that relative displacement of the clamping member and cone member towards one another causes expansion of the sleeves.

The term "leading end", as used herein, means that end of the shaft or a sleeve which, in use of the plug, first enters the bore in the wall to which the plug is to be affixed, and the term "rear end" means the end opposite to the leading end.

In known wall plugs of the above kind, the sleeves are usually formed from hardened steel and are slotted over at least two-thirds or even three-quarters of their length. When the wall plug is tightened up, the expanding sleeve which is nearer the leading end of the shaft is pushed onto the cone member and is expanded outwardly. The rear end of this sleeve is conically tapered and thus serves as an expanding tool for the slotted leading end of the rear expanding sleeve.

If only for reasons of series production and stock-keeping it is disadvantageous for the leading and rear expanding sleeves to be different.

Furthermore, the expanding tool function of the conically tapered end of the leading expanding sleeve requires the sleeve to have considerable wall thickness, because otherwise the conically tapered end might well be compressed by the resistance of the rear expanding sleeve to being opened out, and also because if the wall thickness is too thin it is not possible to produce a conically tapered portion of the necessary length. However, from the point of view of material, working, and transport costs, considerable wall thicknesses are undesirable. A further disadvantage of the known construction arises from the fact that the slotted znnes of the expanding sleeves are relatively close to one another so that the compression stresses on the masonry, caused by expansion of the sleeves, are concentrated over a short length.

The invention is based on the problem of further developing an expanding wall plug of the kind first described so that it is particularly suitable for use in aerated concrete or similarly elastic structural material, and so that the pressure forces generated by the expansion of the sleeves in the bore in the masonry are distributed over the greatest possible length, without however loading the non-bearing layers in the vicinity of the inlet into the bore in the wall.

According to the invention there is provided an expanding wall plug comprising a screwthreaded shaft encircled by at least two expanding sleeves disposed end-to-end on the shaft and having open-ended longitudinal slots in their leading ends, said sleeves being clamped between a clamping member threadedly engaging, or integral with, the rear end of the shaft and a first cone member threadedly engaging the leading end of the shaft and having a conical surface projecting partially within the slotted end of the adjacent expanding sleeve, and a further cone member axially displaceable on the shaft between the or each two adjacent sleeves and having a conical surface projecting partially within the adjacent slotted end of the rearward one of the or each two sleeves, so that relative displacement of the clamping member and first cone member towards one another causes the conical surfaces of the cone members to be forced into the slotted ends of the sleeves respectively, thereby expanding said ends of the sleeves.

In the case of expanding wall plugs used in aerated concrete or other elastic masonry material, high holding forces can be attained by use of a wall plug according to the invention, because the expanding sleeves may be formed from non-hardened steel and can therefore be more extensively expanded. The greater expansion is possible above all because a separate expanding cone member is provided for each expanding sleeve so that the wall thickness of the sleeves can be kept smaller than was the case hitherto, since it is not necessary to provide a conically tapered portion at the rear end of the leading sleeve.

Preferably, the non-slotted zone of each sleeve comprises substantially 50% or more of the total length of the sleeve. In this case the considerable holding force of the expanding wall plug is enhanced by the fact that the sleeves have a longer non-slotted zone than heretofore and therefore the locations of compression stresses in the masonry are distributed and not concentrated. The greater distance between the slotted zones of adjacent expanding sleeves, achieved by the inclusion of the further cone member between the sleeves, is also desirable to achieve more intensive expansion, since during the opening out process the slotted zones are pushed closer to one another.

Preferably the expanding sleeves are of the same dimensions and be cone members are of the same external dimensions. This results in even expansion and resultant high holding forces.

A diagram of the distribution of pressure lines shows, in this case, an approximately cylindrical pattern between the two expanded slotted ends of the sleeves, so that localised excess stresses in the masonry are avoided, and by reason of the relatively large non-slotted sleeve length in the vicinity of the entrance to the bore in the wall, a zone is left which is free of stresses.

In the case of large wall thicknesses of com paratively elastic masonry, it is expedient for the holding stresses to be located approximately in the middle of the wall thickness, so that for these cases the expanding sleeve which is adjacent the bore entrance may be of greater length than the leading expanding sleeve. In order nevertheless to achieve equal anchoring forces, it is necessary in this case for the nonslotted zone of the rear expanding sleeve to be longer than the slotted zone.

It is furthermore expedient for there to be a radial clearance of, at most, substantially lmm between the shaft and the sleeves. In this way, the total diameter of the plug can be kept small because, if non-hardened steel is used, a sufficiently large deformation of the sleeves can still be obtained to achieve the anchoring in the elastic masonry. A small overall diameter of the expanding wall plug is desirable to permit the plug to be inserted through a hole in a component which is to be attached to a wall, and into the bore in the wall. The bore in the component can then be kept relatively small and yet still allow the plug to pass through it.

The invention is explained in greater detail hereinafter with reference to the accompanying drawings in which: Figure 1 is a side view of an expanding wall plug according to the invention; and Figure 2 is a section through a wall showing the plug of Figure 1 in use in fixing a component to a wall.

Referring to Figure 1: located end-to-end on a threaded shaft 10 are two expanding sleeves 11, 12 which are preferably identical to each other, each consisting of lengths of metal tube which are formed with openended longitudinal slots 14 extending from one end thereof. There are preferably four slots in each sleeve. The length of the non-slotted zone 15 of each expanding sleeve may amount to 50% or more of the total length of the sleeve. Each sleeve may be formed from non-hardened steel and there is preferably a radial clearance of lmm between the shaft 10 and each of the sleeves.

The expanding wall plug is particularly suitable for use in aerated concrete or similarly elastic structural material. The leading end of the expanding wall plug, i.e. the end which first enters the bore in the wall, has a cone member 16 screwed onto the end of the shaft 10, the cone member being screwed on sufficiently to be at the right depth, in terms of wall thickness, for opening out the expanding sleeve 11. Even in a non-tightened condition, the conical surface of the cone member 16 projects somewhat into the slotted leading end of the expanding sleeve 1 1.

Bearing on the rear end of the leading expanding sleeve 11 is a second cone member 17 which has a larger inner bore than the thread diameter of the shaft 10 so that it can be displaced freely on the screw-threaded shaft. The outside dimensions of the cone members 16 and 17 are preferably the same. The conical surface of the cone member 17 protrudes into the slotted leading end of the rear expanding sleeve 12. A hexagonal nut 19 is screwed onto the screwthreaded shaft 10 and bears against the rear end of the expanding sleeve 12, a washer 18 being interposed between the two components.

Alternatively, the shaft 10 may be integrally formed with a hexagonal or screw head instead of a separate nut 19 being provided.

For mounting a component 22 on a wall 24, as shown in Figure 2, the wall plug is inserted through an aperture 20 in the component 22 and then into a bore 26 in the wall 24 until the washer 18 is resting against the component 22.

When the nut 19 is tightened, the cone member 16 is drawn in the direction of the washer 18 so that both expanding sleeves 11 and 12 are evenly pushed onto the cone members 16 and 17 respectively. Thus an even amount of expansion of the sleeves occurs and the distribution of pressure extends virtually cylindrically between the two opening out areas indicated at 28 and 30.

Although in the described embodiment only two expanding sleeves are provided on the shaft 10, it will be appreciated that if required a greater number of sleeves may be provided, further cone members, similar to the cone member 17, being provided between adjacent sleeves.

WHAT WE CLAIM IS: 1. An expanding wall plug comprising a screw-threaded shaft encircled by at least two expanding sleeves disposed end-to-end on the shaft and having open-ended longitudinal slots in their leading ends, said sleeves being clamped between a clamping member threadedly engaging, or integral with, the rear end of the shaft and a first cone member threadedly engaging the leading end of the shaft and having a conical surface projecting partially within the slotted end of the adjacent expanding sleeve, and a further cone member axially displaceable on the shaft between the or each two adjacent sleeves and having a conical surface projecting partially within the adjacent slotted end of the rearward one of the or each two sleeves, so that relative displacement of the clamping member and first cone member towards one another causes the conical surfaces of the cone members to be forced into the slotted ends of the sleeves respectively, thereby expanding said ends of the sleeves.

2. An expanding wall plug according to claim 1 wherein the non-slotted zone of each sleeve comprises substantially 50% of the total length of the sleeve.

3. An expanding wall plug according to claim 1 wherein the non-slotted zone of each sleeve is longer than the slotted zone thereof.

4. An expanding wall plug according to any of claims 1 to 3 wherein there are provided only two sleeves and the rear sleeve is longer than the leading sleeve.

5. An expanding wall plug according to any of claims 1 to 4 wherein the or each further cone member has the same external dimensions as the first cone member.

6. An expanding wall plug according to any of claims 1 to 5 wherein there is a radial clearance of substantially lmm between the shaft and each expanding sleeve before expansion thereof.

7. An expanding wall plug according to any of claims 1 to 6 wherein each expanding sleeve is formed from non-hardened steel.

8. An expanding wall plug substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. evenly pushed onto the cone members 16 and 17 respectively. Thus an even amount of expansion of the sleeves occurs and the distribution of pressure extends virtually cylindrically between the two opening out areas indicated at 28 and 30. Although in the described embodiment only two expanding sleeves are provided on the shaft 10, it will be appreciated that if required a greater number of sleeves may be provided, further cone members, similar to the cone member 17, being provided between adjacent sleeves. WHAT WE CLAIM IS:

1. An expanding wall plug comprising a screw-threaded shaft encircled by at least two expanding sleeves disposed end-to-end on the shaft and having open-ended longitudinal slots in their leading ends, said sleeves being clamped between a clamping member threadedly engaging, or integral with, the rear end of the shaft and a first cone member threadedly engaging the leading end of the shaft and having a conical surface projecting partially within the slotted end of the adjacent expanding sleeve, and a further cone member axially displaceable on the shaft between the or each two adjacent sleeves and having a conical surface projecting partially within the adjacent slotted end of the rearward one of the or each two sleeves, so that relative displacement of the clamping member and first cone member towards one another causes the conical surfaces of the cone members to be forced into the slotted ends of the sleeves respectively, thereby expanding said ends of the sleeves.