GB2150248A

GB2150248A - Fixing plugs

Info

Publication number: GB2150248A
Application number: GB08429403A
Authority: GB
Inventors: Werner Wolpensinger
Original assignee: A Raymond
Current assignee: A Raymond
Priority date: 1983-12-17
Filing date: 1984-11-21
Publication date: 1985-06-26
Also published as: FR2556793B3; DE3345696C2; AT383188B; FR2556793A1; IT8423671V0; ES283445Y; GB2150248B; ES283445U; JPS60132113A; ATA398084A; NL8403800A; GB8429403D0; DE3345696A1

Abstract

A fixing plug (1) comprises an inclined ramp (3) increasing in thickness towards the insertion end of the plug (1), and an expanding wedge (4) which can be engaged with the ramp (3) and which forms with the stay bolt (1) a circular cross-section in the non- expanded state. To enable the plug to be produced easily and positioned without any trouble, the thin end (5) of the expanding wedge (4) is moulded onto the end of the bolt (1) as a straight extension thereof, by means of an elastic web (6); and before being inserted in the dowel hole (7) in the wall or ceiling it is pivoted into the wedge- shaped bed (3), by bending the web (6). To make the bent over web (6) exert tension on the wedge (4), the web (6), over a length of 1/2 to 2/3 the diameter of the bolt from the moulding on point at the insertion end (2), is somewhat thicker in cross-section than over its remaining length to the end (5) of the wedge. At its rear end, the plug (1) has a head (9), or cable clip, eyelet, hook or flange to receive components such as claddings, pipes, cable leads or the like. The plug (1) is made from hard elastic plastics material. <IMAGE>

Description

SPECIFICATION Fixing plugs The invention relates to fixing plugs of the kind made of hard resilient plastics and comprising a stay bolt, with a holding member to support the load in the rear part of the bolt, and a wedge-shaped bed rising towards the insertion end of the bolt, and further comprising an expanding wedgewhich can be displaced along the wedge-shaped bed and which, together with the stay bolt, forms a circular cross-section in the non-expanded state.

Fixing plugs of the above type are used to anchor components such as claddings, pipes, cable leads or the like to walls, or to suspend intermediate ceilings.

The important requirement is that the plugs should be inserted quickly and simply in the pre-bored holes in the wall or ceiling and then provide a secure hold when the expanding wedge has been driven in.

It is particularly important that the loaded wedge should always be pressed firmly against the wall of the hole, so that the holding force becomes progressively larger as the load increases.

In known plugs of this type the expanding wedge is provided with an elongation guided in the holding member. When the stay bolt has been inserted in the hole in the wall, the elongation projects from the wall, so that this end can be driven in, e.g. with a hammer, until the wedge is seated firmly in the hole with the stay bolt (utility model 79 07).

The length of wedge necessary for the driving-in action has been found to be a disadvantage of those plugs, since the plastic material used for the purpose necessarily increases the manufacturing cost. Furthermore it is almost impossible to dimension the length of the wedge so that when it has been driven in its rear end terminates exactly with the holding member of the stay bolt.

The problem has existed, therefore, of providing a plug of the above kind where the wedge is restricted to the length required to generate the expanding pressure.

According to the invention there is provided a plug of the above kind in which the thin end of the expanding wedge is joined integrally to the insertion end of the stay bolt by a resilient web, and can be pressed against the wedgeshaped bed, overcoming the bending resistance of the web.

Owing to the web connection between the stay bolt and the wedge, the wedge is drawn into the drilled hole without any trouble when the plug is mounted, until the outer wall of the wedge comes into contact with the inner wall of the hole. When the plug is manufactured the wedge is desirably mounted onto the stay bolt as a straight extension thereof, for reasons of deformation.

Consequently when the wedge is turned over and pressed against the bed, given a web of appropriate dimensions, a certain tension is exerted in the direction of the insertion end of the stay bolt, so that the wedge does not need to be driven in. Once the plug has been pressed in it is held securely at any depth, and if tensile forces arise they may even strengthen the secure hold. Moreover the plug is still cheaper than the known two part construction, owing to the saving in material and the one-part design.

To improve the guidance of the wedge in the bed it is advantageous for the bed to be formed by a bottom surface, corresponding in inclination and width to the wedge surface, and two side walls. The side walls may run parallel or, according to a further feature of the invention, may diverge conically from the bottom surface so that the wedge can be inserted more easily in the bed. The bottom surface of the bed is desirably interrupted by a groove which ends shortly before the outer surface of the stay bolt, so that the two halves of the bolt can be somewhat compressed, should the diameter of the hole turn out to be somewhat smaller, e.g. through the use of a worn drill.As a means of further improving the spreading action, the groove may be at least as wide as the bottom surface of the wedge, so that the wedge is supported only against the side walls and splays out the two halves of the bolt. In this way the splaying action takes effect over the whoie periphery of the bolt and thus over the whole inner wall of the hole.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings. In the drawings: Figure 1 shows a fixing plug according to the invention in use, Figure 2 is an enlarged longitudinal section through the wedge-shaped bed and the wedge in the flat state of the plug as manufactured, Figure 3 is a plan view thereof, Figure 4 shows three cross-sections through the wedge-shaped bed, Figure 5 shows three cross-sections through the wedge, Figure 6 is a longitudinal section through the wedge-shaped bed with the wedge folded over and the web lowered, Figure 7 shows two cross-sections through the wedge-shaped bed and the wedge of Figure 6, Figure 8 is a plan view of Figure 6, Figure 9 is a longitudinal section through a modified form of the plug shown in Figure 6, with a radial expanding action, Figure 10 is a cross-section thereof, Figure 11 is a longitudinal section through a further modification of the plug shown in Figure 6 with the wedge positively guided in the bed, and Figure 12 is a cross-section thereof.

The fixing plug shown in the drawings is made of a hard resilient plastics material and substantially comprises a stay bolt 1, with a wedge-shaped bed 3 rising towards the insertion end 2 of the bolt and an expanding wedge 4 which can be slid along the bed 3. Together with the stay bolt 1, the wedge 4 forms a plug element of circular cross-section in the nonexpanded state.

At its thin end 5 the wedge 4 is joined integrally with the insertion end 2 of the stay bolt 1 by an elastic web 6, in such a way that the wedge 4 can be pressed against the wedge-shaped bed 3 by bending over the web 6. As can be seen from Figures 2 and 3, the wedge 4 is preferably moulded onto the stay bolt 1 as a straight extension thereof.

In the delivery state therefore the web 6 extends in the insertion direction of the bolt 1, and the wedge 4 has to be folded back virtually through 1800 until it lies against the bed 3, in order to make the plug ready for use.

As a means of favourably influencing the flexional elasticity behaviour of the web 6, the web is preferably moulded onto the surface at the bottom part of the insertion end 2 and is dimensioned so that, over a length 1, of the approximately 1/2 to 2/3 of the diameter of the bolt from the moulding on point, it is somewhat thicker in cross-section than over the remainder of its length to the end 5 of the wedge; thus a pre-determined bending point is formed at the transition from the thick to the thin cross section. In this way a higher bending stress is generated when the wedge 4 is folded over, and the wedge 4 is drawn more strongly into the clamping position.

The mode of operation of the connecting web 6 can be seen clearly from Figure 1. The stay bolt, together with the folded over wedge 4, is located in a hole 7 in a supporting wall 8, corresponding to the cross-section of the bolt. The wall 8 preferably has a rough but rigid structure; concrete and building stones are equally appropriate for the wall material as wood or chipboard. At the rear part of the bolt 1 there is a holding member 9; in the present example it is in the form of an end plate and its function is to fix an insulating sheet 10 to the wall 8. Depending on the practical application of the plug the holding member 9 moulded onto the bolt 1 may, for example, equally be a cable clip, eyelet, hook or flange.

On inserting the plug in the hole 7 the wedge 4 is bent slightly backwards and then drawn into the hole 7 by the bent over web 6. The web 6 exerts tension on the wedge 4 as a result of the bending stress, so that the wedge 4 always lies flush against the wall inside the hole and firmly anchors the plug at any depth of insertion. If any tensile forces arise at the holding member 9, the stay bolt yields slightly and simultaneously presses the wedge 4 still more firmly against the wall inside the hole.

In the simplest construction the wedge-shaped bed 3 may merely comprise a bottom surface 11 rising towards the insertion end 2 and having the same angle of inclination a as the wedge suface 12 of the expanding wedge 4. To improve the guidance of the wedge 4, however, it is advantageous for the bed 3 to be bounded by two side walls 13, as shown in Figures 3 and 4 in the present example.

The side walls 13 may run parallel as in the example shown in Figures 11 and 12, or they may diverge conically from the bottom surface 11 as in the example shown in Figures 3 and 4. The side walls 14 of the wedge 4 have the same inclination, and the bottom surface 11 and wedge surface 12 have the same width throughout their length.

Figure 4 shows three different cross-sections through the bed 3, while Figure 5 shows three different cross-sections through the wedge 4. The cross-sections in each case correspond to the section lines indicated in Figure 2. In the bed 3 shown in Figure 4, ther bottom surface 11 is further interrupted by a groove 15, which extends to a position near the outer surface 16 of the stay bolt 1.

In this way the stay bolt 1 can be somewhat compressed, which is an advantage when the hole 7 drilled turns out to be slightly smaller than is required for the diameter of the bolt. Similarly the bolt 1 can be expanded where the hole 7 drilled is too large, if a wedge 1 with a radial or tangential expanding action is used (see further below).

Figures 6 to 8 show a modified form of the plug, where the web 6 is sunk between the side walls 17 of the bolt 1 formed by the groove 15. It is arranged so that the outer arch 18 of the folded web 6 at the most reaches the insertion end 2 of the bolt 1 or stops short of it. This ensures that, even when the end 2 of the plug bolt 1 abuts the end of the hole 7, the bent web will remain fully under tensile stress. If the arch 18 of the web were to project as in Figure 1 and the hole 7 were not drilled deep enough, which is not infrequent in practice, then the arch 18 could abut the bottom of the hole and push back the wedge 4, so that the desired clamping action indicated in Figure 7 would not occur.

Figures 9 and 10 show a different form of the plug, with the groove 15 at least as wide as the wedge surface 12. In this way the wedge 4 is supported not on the bottom surface 11 but on the tapered side walls 13. Consequently the stay bolt 1 is pressed radially apart in all directions so that the clamping action is transmitted evenly to the whole wall of the hole. Particularly with walls of somewmat softer material, this is better than having the clamping force acting only in two directions, as indicated by the upwardly directed arrows Pin Figure 7. The same effect can be obtained in the embodiment shown in Figures 6 to 8, if the side walls 13 of the bed 3 and the side walls 14 of the wedge 4 are tapered together lengthwise towards the insertion end 2. Longitudinal displacement of the wedge produces a keying action in a tangential direction.

In the form ofthe plug shown in Figures 11 and 12 a pointed lug 22 is provided at the front and rear end of the curved outer surface 21 of the wedge 4, as a means of further increasing the static friction of the wedge 4 in the drilled hole 7. The lugs 22 are desirably tapered in the direction in which the wedge 4 is inserted, and rise sharply at the rear.

Their only function is to fix the wedge 4 securely in the hole 7 at every stage of penetration. The lugs 22 only rise far enough above the curved outer surface 21 to bring their tips into the imaginary cylindrical outer peripheral surface 16' of the bolt 1 in the pushed back position of the wedge 4, so that the lugs can be drawn into the hole without any trouble.

If the stay bolt 1 is drawn back slightly, the lugs 22 secure the wedge 4 by friction on the wall of the hole or, with softer material, by penetrating into the wall of the hole, so that the wedge 4 cannot be pulled out of the hole 7. When the plug is used in hard materials such as concrete, the lugs 22 are pressed Flat so that the whole outer surface 21 of the wedge 1 is in contact. The outer surface 21 and that of the stay bolt 1 may be given different structures or D extures to make them suitable to various buiiding materials.

The embodiment in Figures 11 and 12 also shows a modified form of the bed with parallel side walls 12; here the wedge 4 has on its side walls 14 beads 19 extending parallel with the bottom surface 12.

The beads enable the wedge 4 to be guided displaceably in appropriate guiding grooves 20 in the side walls 13. This embodiment enables the wedge 4 to be located in the bed 3 before the plug is inserted in a wall, the beads 19 being pressed into the grooves 20 from above or possibly slid in from behind.

Claims

CLAIMS:

1. A fixing plug made of a hard resilient plastics material and comprising a stay bolt with a holding member to support a load on the rear part of the bolt, and a wedge-shaped bed rising towards the insertion end of the bolt, and further comprising an expanding wedge which can be placed along the wedge-shaped bed and which, together with the stay bolt, forms a circular cross-section in the nonexpanded stated, and wherein the thin end of the expanding wedge is joined integrally to the insertion end of the stay bolt by a flexible resilient web, and can be pressed against the wedge shaped bed by bending the web.

2. A plug according to claim 1, wherein the web is moulded on the insertion end of the stay bolt substantially diametrically opposite the bed and, over a length "1" of substantially 1/2 to 213 the diameter of the bolt from the mouiding on point, is somewhat thicker in cross-section than over its remaining length to the end of the wedge.

3. A plug according to claim 1 or 2, wherein the wedge-shaped bed has a bottom surface corresponding in inclination and width to the co acting surface of the wedge, and two side walls.

4. A plug according to claim 3, wherein the side walls of the bed and the side walls of the wedge diverge from their co-acting surfaces.

5. A plug according to claim 3 or 4, wherein the bottom surface of the bed is interrupted by a groove which ends close to the outer surface of the stay bolt.

6. A plug according to claim 5, wherein the groove is at least as wide as the co-acting surface of the wedge.

7. A plug according to claim 5, wherein the side walls of the bed and the side walls of the wedge are tapered together lengthwise towards the insertion end.

8. A plug according to claims 3 to 5, wherein the wedge has punctiform protrusions or beads extending parallel with its co-acting surface on at least one of its side walls which can be engaged or slid into correspondingly deep guide grooves or recesses in the side walls of the bed.

9. A plug according to any of claims 1 to 8, wherein at least one outwardly projecting pointed lug or the like, tapered in the insertion direction of the wedge, is moulded onto the curved outer surface of the wedge, and in the operative position of the wedge the lug is fully within the imaginary cylindrical outer surface of the bolt.

10. A plug according to claim 5, wherein the web is sunk between the side walls of the bolt formed by the groove in such a way that the outer arch of the folded over web at the most reaches only to the end of the bolt in the clamping position of the wedge.

11. A fixing plug made of a hard elastic plastics material and comprising a stay bolt with a holding member to support a load in the rear part of the bolt.

and a wedge-shaped bed rising towards the insertion end of the bolt, and further comprising an expanding wedge which can be placed along the wedge-shaped bed and which, together with the stay bolt, forms a circular cross-section in the nonexpanded state, and wherein the thin end of the expanding wedge is moulded onto the end of the bolt in a straight extension thereof by means of an elastic web and can be pivoted into position in the wedge-shaped bed by bending the web.

12. A fixing plug constructed and arranged substantially as hereinbefore described and shown in Figures 1-5 or with reference to Figures 68, or 9 and 10, or 11 and 12 of the accompanying drawings.