GB2129899A

GB2129899A - Expansible anchor

Info

Publication number: GB2129899A
Application number: GB08326944A
Authority: GB
Inventors: Armin Hoffmann
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 1982-10-20
Filing date: 1983-10-07
Publication date: 1984-05-23
Also published as: DE3238851A1; GB8326944D0; FR2534987A1; CH660404A5; FR2534987B1; GB2129899B

Abstract

An expansible socket for anchorage in a reception material 4 having hollow chambers 4a has a body 2 comprising longitudinal elements 2d which are subdivided by slots 2f into portions 2g which are deformable independently of one another. When an expansion element such as a screw 3 is driven in, the portions 2g located in the hollow chambers 4a grip behind the reception material 4, whilst the portions 2g located in the reception bore 4b are deformed to the cross-section thereof. <IMAGE>

Description

SPECIFICATION Expansible dowel The invention relates to an expansible dowel which is particularly adapted for anchorage in a reception material which has hollow chambers comprises a dowel body and an expansion element, the dowel body having, at least over a part of its length, longitudinal profiles with free edge regions which are radially deformable by the expansion element being driven in.

Specific problems, which are not relevant to anchorage in solid materials, occur when an article is to be fastened by a dowel in a reception material which has hollow chambers. Since the dowel is in engagement with the reception material only in the region of webs of the reception material, i.e. only over part of its length, a conventional expansible dowel is not suitable for such a reception material. In order to achieve the necessary fastening strength or extraction value, the dowel must be in firm, frictional interengagement with the reception material.

However, where the material has hollow chambers this is difficult since the web width and the size of the chambers are different and are not evident from the outside of the material.

It has already been proposed that dowels may be anchored in reception material by introduction of a subsequently hardenable composition.

However, this is both complicated and expensive and requires specific aids, such as dosing tools to enable introduction of the hardenable composition. Moreover, these fastenings are not immediately loadable.

Another known method of fastening is to axially upset the dowel sleeve once inserted into the borehole so as to cause gripping behind the reception material. However, such movement of the dowel sleeve is also very complicated and requires a special setting tool. Moreover, it is not usually possible to remove the dowel sleeve without destruction of the same.

A known dowel has longitudinal profiles extending over part of its length. The longitudinal profiles are forced radially outwards when an expansion element is driven in. However, the longitudinal profiles can be deformed only as a whole. Since these longitudinal profiles adapt themselves to the cross-section of the borehole in the reception material undergripping of the reception material by projection into hollow chambers behind the various webs of material is not possible.

An object of the invention is to provide a dowel, which is economic to produce and simple to set, and which will permit anchorage in reception materials which have hollow chambers with aforesaid manner of interengagement behind the webs of material.

In accordance with the invention, this is achieved in that the free edge regions of the longitudinal profiles are subdivided, by incisions extending from their terminal edges or tips into portions which are deformable independently of one another.

As a result of the subdivision of the longitudinal profiles into individual portions which are deformable independently of one another, these can adapt themselves optimally to the reception material. Thus, the portions disposed in the region of the webs of the reception material are deformed to the cross-section of the reception bore. In contrast, the portions, of the longitudinal profiles disposed in the region of the hollow chambers are not deformed and can grip or engage behind the reception material.

The incisions for formation of the portions which are deformable independently of one another can be designed variously. For simple production and for handling it is advantageous for the incisions to be in the form of slots which extend substantially perpendicularly to the longitudinal axis of the dowel. The width of these slots as well as their spacing from one another can be freely selected. For good adaptation to the reception material it is, however, advantageous for the slots to lie relatively ciose to one another.

Upon axial loading of the dowel, those portions of the longitudinal profiles which are in engagement with the reception material are stressed in flexure. For good strength it is, therefore, advantageous if the slots are V-shaped.

Moreover, a V-shaped design of the slots allows economy of material without the bending strength of the portions being reduced. One of the two flanks of each V-shaped slot can, of course, perpendicularly to the longitudinal axis of the dowel.

In the region of the webs of the reception material, the longitudinal profiles have to be deformed to the cross-section of the reception bore. So that the force necessary to achieve this can be kept within a limit, it is advantageous for the longitudinal profiles to have, at a location remote from their free edge regions, a crosssectional weakening which acts as a bending point. This cross-sectional weakening can be situated radially outwardly or inwardly of the dowel. The resultant weakening of the longitudinal profiles in the axial direction is relatively slight.

The longitudinal profiles of the dowel may have different cross-sections. Thus, for example, U-shaped, or V-shaped cross-sections are possible.

However, for ready deformation, i.e. for slight deformation resistance it is advantageous for the terminal edges or tips of the longitudinal profiles to be directed towards one another. The longitudinal profiles thus have a substantially C-shaped cross-section. In the deformed state the terminal edges or tips of the longitudinal profiles can also overlap.

Alternativeiy, the free edge regions of the longitudinal profiles may advantageously extend substantially parallel to one another. When the expansible dowel is produced from plastics material this particular design allows a simpler injection mould and thus lower tool costs. It also simplifies production of the expansible dowel from sheet metal.

The bearing area of the portions gripping behind the reception material can, depending on their dimensions be relatively slight. When this is so, upon axial loading of the dowel the portions can, as a result of excessive pressure per unit of area, dig into the reception material and thus be damaged. For better distribution of the forces, it is therefore, advantageous if the free edge regions of the longitudinal profiles are connected to one another by a web. The web can be the same thickness, thinner or thicker in design than the longitudinal profiles.

So that the web connecting the free ends of the longitudinal profiles does not hinder deformation of the portions present in the region of the reception bore of the material when the expansion element is driven in, it is.advantageous for the web to have a cross-sectional weakening which acts as a predetermined breaking point. After the web has broken through, the corresponding portions of the longitudinal profiles can be freely deformed. In the case of the portions present in the region of the hollow chambers, the web is retained and provide an enlargement of the bearing area.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section of a first embodiment of an expansible dowel in accordance with the invention in the unexpanded state; Fig. 2 is a cross-section through the expansible dowel shown in Fig. 1, along the line Il-Il; Fig. 3 is a longitudinal section illustrating a second embodiment of an expansible dowel in accordance with the invention in the expanded state and in position in reception material which has hollow chambers; Fig. 4 is a cross-section through the expansible dowel shown in Fig. 3, along the line IV--IV; Fig. 5 is a cross-section through the expansible dowel shown in Fig. 3, along the line V--V;; Fig. 6 is a longitudinal section illustrating a third embodiment of an expansibie dowel in accordance with the invention in the unexpanded state, but located in position in a reception material with hollow chambers; Fig. 7 is a cross-section through the expansible dowel shown in Fig. 6, along the line VIl-VIl; Fig. 8 is a view similar to Fig. 6 showing the same expansible dowel in the expanded state; Fig. 9 is a cross-section through the expansible dowel shown in Fig. 8, along the line IX-IX; Fig. 10 is a longitudinal section of a fourth embodiment of an expansible dowel in accordance with the invention in the unexpanded state; and Fig. 11 is a cross-section through the expansible dowel shown in Fig. 10, along the line Xl-XI.

A first embodiment of the expansible dowel of the invention, as shown in Figs. 1 and 2 has a dowel body which is designated as a whole by reference numeral 1. The rearward end of the dowel body 1 is provided with a flange 1 a as well as a bore 1 b for reception of an expansion element. The expansible dowel also has two support beams 1 C which extend parallel to one another. Longitudinal profiles ldofapproximately U-shaped are arranged between the support beams 1 c. The longitudinal profiles 1 d have incisions extending from their radially outer edges or tips 1 e. These incisions are in the form of slots if extending substantially perpendicularly to the longitudinal axis of the dowel. As a result of the slots 1 f, the longitudinal profiles 1 dare subdivided into portions 1g which are deformable independently of one another.For easy deformation, the longitudinal profiles 1 d each have a cross-sectional weakening in a radially inner region to act as a bending point 1 h. To increase the bearing area of the longitudinal profiles 1 on the reception material, the free radially outer edge regions of each longitudinal profile 1 dare connected together by a web 1 i. The web li is. of course, also subdivided by the slots 1 f between the portions 1 g. So that the web 1! does not hinder deformation of the portions 1 g which are disposed within the actual bores in the reception material (i.e. the portions 1 g which are not located in the hollow chambers), the web li has a cross-sectional weakening acting as a predetermined breaking point 1 k.This breaking point 1k tears when sufficient tensile loading is brought to bear thereon. After the webs li have torn through at their respective predetermined breaking points 1 k, the corresponding portions 1g of the longitudinal profiles 1 dare freely deformable.

A second embodiment of the extensible dowel of the invention, as shown in Figs. 3 to 5, corresponds substantially to the embodiment shown in Figs. 1 and 2. It consists of a dowel body which is designated as a whole by reference numeral 2 and has, at its rearward end, a flange 2a as well as a bore 2b for reception of an expansion element. The dowel body 2 includes two support beams 2c extending parallel to one another as well as longitudinal profiles 2d having, in the under armed state, a substantially U-shaped cross-section. The longitudinal profiles 2d are again subdivided, by slots 2f extending from the radially outer edges or tips 2e, into portions 2g which are deformable independently of one another. In contrast to the embodiment shown in Figs. 1 and 2, the slots 2f are however, V-shaped in form. This shape allows economy of material without reducing the bending strength of the portions 2g. Moreover, the sloping flanks of the slots 2ffacilitate insertion of the expansible dowel into a reception bore 4b of a material which is designated as a whole by reference numeral 4 and has hollow chambers 4a. The expansion element is a screw 3.

In use, the expansible dowel may, for example, serve for the fastening of a plate 5. The dowel body 2 is radially widened by the screw 3 being driven in. When this happens the portions 2g which are disposed in the hollow chambers 4a grip behind the reception material 4. In contrast, those portions 2g of the longitudinal profiles 2d which are disposed in the reception bore 4b are deformed and adapt themselves to the crosssection of the reception bore 4b as shown in Fig. 5. Additional anchorage forces are achieved by the deformed portions 2g.

A third embodiment of an expansible dowel in accordance with the invention, as shown in Figs. 6 to 8, consists of a dowel body which is designated as a whole by reference numeral 11 and which has a flange 1 la at its rearward end. In Figs. 6 and 7, this expansible dowel is shown inserted into a reception bore 1 2b of a reception material 1 2 which has hollow chambers 1 2a. The dowel body 11 has longitudinal profiles lid the radially outer edges or tips lie of which are directed towards one another. The longitudinal profiles 11 dare subdivided, by slots 1 1 f extending substantially perpendicularly to the longitudinal axis of the dowel, into portions 1 lg which are deformable independently of one another.

In use, this expansible dowel may, for example, serve for fastening a plate 1 3 to the reception material 12. After the dowel body 11 has been inserted into the reception bore 1 2b, an expansion pin 14 is likewise driven into the reception bore I 2b. The expansion pin 14 has a wedge surface 1 4a which facilitates the deformation of the dowel body 11.

In Figs. 8 and 9, the dowel body 11 is shown to be anchored by the driving-in of the expansion pin 14. Those portions 1 g of the dowel body 11 which are disposed in the hollow chambers 1 2a project and grip behind the reception material 12 so as to hold the dowel firmly in position. In contrast, the portions 1 ig which are disposed in the reception bore 1 2b are deformed, as is ciearly shown in Fig. 9. Additional anchorage forces arise through the deformed portions 1 lg.

A fourth embodiment of an expansible dowel in accordance with the invention, as shown in Figs.

10 and 11, has a dowel body which is designated as a whole by reference numeral 1 5. As in previous embodiments this is provided at its rearward end with a flange 1 spa. As shown in Fig. 1 , the front region of the dowel body 1 5 consists of three longitudinal profiles 1 5d which are curved or curled in a somewhat tubular manner. The radially outer edges or tips 1 5e of the longitudinal profiles 1 5d are again directed towards one another. The longitudinal profiles 1 sod are again subdivided by slots 1 5f into portions 1 5g which are deformable independently of one another. The mode of operation of this expansible dowel is substantially the same as the embodiment illustrated in Figs. 6 to 8. However, the three symmetrically-arranged longitudinal profiles 1 5d result in a better distribution of the anchorage forces. For optimum adaptation of the expansible dowel to the reception material, the slots 1 5f in the individual longitudinal profiles 1 sod can also be arranged so as to be axially offset in relation to one another.

Claims

1. An expansible dowel which is particularly adapted for anchorage in a reception material which has hollow chambers comprises a dowel body and an expansion element, the dowel body having, at least over a part of its length, longitudinal profiles with free edge regions which are radially deformable by the expansion element being driven in, characterised in that the free edge regions of the longitudinal profiles are subdivided, by incisions extending from their terminal edges or tips, into portions which are deformable independently of one another.

2. An expansible dowel as claimed in claim 1, characterised in that the incisions are in the form of slots which extend substantially perpendicularly to the longitudinal axis of the dowel.

3. An expansible dowel as claimed in claim 2, characterised in that the slots are V-shaped.

4. An expansible dowel as claimed in claim 1, 2 or 3, characterised in that at a location remote from their free edge regions, the longitudinal profiles have a cross-sectional weakening which acts as a bending point.

5. An expansible dowel as claimed in any preceding claim, characterised in that the terminal edges or tips of the longitudinal profiles are directed towards one another.

6. An expansible dowel as claimed in any of claims 1 to 4, characterised in that the free edge regions of the longitudinal profiles are in the form of projections which extend substantially parallel to one another.

7. An expansible dowel as claimed in claim 6, characterised in that the free edge regions of the longitudinal profiles are connected together by a web.

8. An expansible dowel as claimed in claim 7, characterised in that the web has a cross-sectional weakening which provides a predetermined breaking point.

9. An expansible dowel, which is particularly adapted for anchorage in a reception material which has hollow chambers, substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, or Figs. 3 to 5, or Figs.

6 to 9, or Figs. 10 and 11 of the accompanying drawings.