GB1559516A - Anchoring a hollow fixing plug - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO ANCHORING A HOLLOW FIXING PLUG (71) I, ARTUR FISCHER, a German citizen, of D-7241 Tumlingen, Gde Waldachtal, Weinhalde 34, Germany, 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: This invention relates to the anchoring of a hollow fixing plug in a hole in a wall or panel and especially in a wall made from cavity bricks, by injecting a fixing agent into a sheath surrounding the element to expand the sheath.

The provision of a sheath considerably reduces the quantity of fixing agent which need be used to secure the plug in position.

Thus, in the absence of a sheath, the material would have to fill any cavity surrounding the plug in order to secure the plug in position, whereas with a sheath less material is needed since expansion of the sheath to a size less than that of the cavity will generally secure the plug.

It has been proposed to use rubber sheaths for the plug. However these are not very strong and are liable to damage during transport or assembly. Further, because such a rubber sheath has isotropic expansion characteristics (that is to say the sheath expands substantially equally in all directions) and is extremely resilient, it tends to sag below the plug under its own weight and under the weight of the fixing agent with which it has been filled. As a result there is an uneven distribution of the fixing agent around the plug.

The present invention seeks to limit still further the quantity of fixing agent required and on the other hand to obtain a better distribution of the fixing agent around the plug.

The present invention provides fastening equipment comprising a hollow fixing plug and an expansible sheath for the plug; the sheath being arranged about the plug when the plug is inserted in a hole, being expandable by injection of a fixing agent and being constructed of an anisotropic material so that expansion of it in a direction along the axis of the plug is restricted.

By restricting expansion of the sheath in a direction along the axis of the plug any fixing agent injected into the sheath will cause expansion of the sheath in a radial direction relative to the axis of the plug.

Consequently, less fixing agent will be required to produce a given radial dimension of the sheath. However this in no way reduces the security of an article secured to the wall by the plug since it is the radial extent of the expanded sheath which is the important factor in determining that security.

Preferably, the material from which the sheath is made is a fabric. By making the sheath of a fabric, it is not only more resistant to damage, but also permeable to air, so that the venting necessary for the complete filling of the sheath is guaranteed, and a more rapid hardening of the fixing agent results.

Advantageously, the sheath may be formed from woven material. In this case, to give the material its anisotropic nature a respective one of the warp or weft is woven more tightly than the other.

The present invention further provides anchoring of a hollow fixing plug in a hole, in a panel or wall and especially a cavity wall, by filling, with a fixing agent, an expansible sheath which is pulled over the plug, is closed at its front end and secured at its rear end to the plug, wherein the sheath consists of an an isotropic fabric and can expand only radially relative to the plug.

The present invention also provides a method of anchoring a hollow fixing plug in a hole, the plug being part of equipment according to the invention, wherein the method comprises the steps of inserting the plug and sheath into the hole and injecting a fixing agent into the sheath.

The present invention also provides an anchorage comprising a hollow fixing plug mounted in a hole, a sheath which surrounds the plug, the sheath being filled with a hardened material, the said material haying caused expansion of the sheath radially about the axis of the plug, the sheath being constructed of an anisotropic material so that expansion of it in a direction along the axis has been restricted.

Fastening equipment constructed in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawing, the single figure of which shows a crosssection through the fastening equipment when anchored in a cavity brick wall.

Referring to the accompanying drawing, the fastening equipment comprises a hollow fixing plug 1, the insertion end of which is squashed fiat and is bent in the manner of a barb 2. The barb 2 increases the resistance to withdrawal of the plug 1 when it is anchored in position. The rear end 4 of the plug 1 has a smaller diameter than the main portion so that an internal thread 3 for a fastening screw (not shown) may be better tapped. A bush 6 which substantially closes the mouth of the bore leading to a cavity 5 in the cavity brick, is placed on the reduced diameter section 4 of the plug, the external diameter of the bush 6 being matched to the diameter of the bore so that it can be fixed in the bore.

A flexible sheath 7 is placed round the plug I prior to the insertion of the plug and the bush 6 in the bore. The sheath 7 is attached to the bush 6 by a spring ring 43 which snaps into an annular groove 45 arranged in the outer circumferential surface of the bush 6 in the region of the latter's visible end face 44.

Before a hardenable fixing agent is introduced into the sheath 7, an injection sleeve 41 is inserted into the inner bore 46 of the plug 1, the leading end of the injection sleeve abutting against the end of the inner bore of the plug so as to provide a seal. The fixing agent is now injected through the injection sleeve 41 by an injection device 10. The fixing agent passes through outlet apertures 22 in the plug 1 and into the sheath 7. During the injection process the sheath 7 is filled with fixing agent and expands.

A piece of rubber tubing 9 is stretched over the apertures 22 so as to cover them.

During the injection process this tubing 9 is lifted away from the apertures 22 under the injection pressure, and in this way enables the sheath 7 to be filled. However, after cessation of the injection process, the tubing 9 seals off the apertures 22 so that no fixing agent can flow back into the inner bore 46 of the plug 1.

After sufficient fixing agent has been injected and has hardened, the injection sleeve 41 is then removed, together with a hardened core of fixing agent which is then contained in the sleeve. The inner bore 40 of the plug 1 with its internal thread 3 is now free for receiving a fastening screw which may be used, for example, to clamp an article against the cross-piece 13 of the wall.

The sheath 7 is made of a flexible anisotropic fabric which can expand and/or stretch only in a radial direction relative to the axis of the plug 1. Such a fabric may, for example, be constituted by a woven material in which the weft threads are woven loosely and the warp threads are woven tightly.

Not only is a fabric sheath 7 more resistant to damage than a rubber sheath but it is also, especially if woven, more permeable to air and water. Due to its permeability, the sheath 7 can be more rapidly filled and the fixing agent hardens more quickly.

When the sheath 7 is filled it provides a large and symmetrical counter-abutment area behind the cross-piece 13 of the brick 14, and also, in the example shown in the drawing, behind the apertured cross-piece in the middle of the brick.

Because of the anistropic nature of the sheath 7, expansion of it is prevented in a direction along the axis of the plug. Consequently any fixing agent injected into the sheath 7 will cause expansion of the sheath in a radial direction relative to the axis of the plug. As as result no fixing agent is wasted in extending the longitudinal dimensions of the sheath and all of it is usefully employed in enlarging the sheath radially to form the aforesaid abutment area(s).

In the arrangement shown in the drawing the overall length of the plug I is increased by the use of the barb 2. The sheath has, of course, to extend over the full length of the plug but as shown its extra length in this case has been usefully employed to provide the additional central counter-bearing surface.

Fastening of the sheath 7 (by the spring ring 43) in the region of the visible end of the bush 6 ensures, even where the plug is anchored in structures having thin-walled facing panels, that the sheath is able to expand directly behind that panel. Further, fastening of the sheath 7 in that region also ensures that the sheath is clamped in place not only by the spring ring 43 but also by the clamping action between the bush 6 and the wall of the bore in the facing panel.

Reference is directed to the Complete Specification of our copending British Patent Application No. 42522/76 (Serial No. 1559515) which is also concerned, inter alia, with fastening equipment of the type described and illustrated above.

WHAT I CLAIM IS: - 1. Fastening equipment comprising a hollow fixing plug and an expansible sheath for the plug; the sheath being arranged about the plug when the plug is inserted in a hole, being expandable by injection of a fixing agent and being constructed of an an isotropic material so that expansion of it in a direction along the axis of the plug is restricted.

2. Fastening equipment as claimed in claim 1, in which the material is a fabric.

3. Fastening equipment as claimed in claim I or claim 2, in which the material is woven.

4. Fastening equipment as claimed in claim 3, in which a respective one of the warp or weft is woven more tightly than the other.

5. Fastening equipment as claimed in any one of claims 1 to 4 and substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

6. A method of anchoring a hollow fixing plug in a hole, the plug being part of equipment as claimed in any one of claims I to 5, wherein the method comprises the steps of inserting the plug and sheath into the hole and injecting a fixing agent into the sheath.

7. A method of anchoring a hollow fixing plug in a hole, the method being as claimed in claim 6 and substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

8. An anchorage comprising a hollow fixing plug mounted in a hole, a sheath which surrounds the plug, the sheath being filled with a hardened material, the said material having caused expansion of the sheath radially about the axis of the plug, the sheath being constructed of an anisotropic material so that expansion of it in a direction along the axis has been restricted.

9. An anchorage substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

10. Anchoring of a hollow fixing plug in a hole, in a panel or wall and especially a cavity wall, by filling, with a fixing agent, an expansible sheath which is pulled over the plug, is closed at its front end and secured at its rear end to the plug, wherein the sheath consists of an anisotropic fabric and can expand only radially relative to the plug.

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

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. and the wall of the bore in the facing panel. Reference is directed to the Complete Specification of our copending British Patent Application No. 42522/76 (Serial No. 1559515) which is also concerned, inter alia, with fastening equipment of the type described and illustrated above. WHAT I CLAIM IS: -

1. Fastening equipment comprising a hollow fixing plug and an expansible sheath for the plug; the sheath being arranged about the plug when the plug is inserted in a hole, being expandable by injection of a fixing agent and being constructed of an an isotropic material so that expansion of it in a direction along the axis of the plug is restricted.

2. Fastening equipment as claimed in claim 1, in which the material is a fabric.

3. Fastening equipment as claimed in claim I or claim 2, in which the material is woven.

4. Fastening equipment as claimed in claim 3, in which a respective one of the warp or weft is woven more tightly than the other.

5. Fastening equipment as claimed in any one of claims 1 to 4 and substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

6. A method of anchoring a hollow fixing plug in a hole, the plug being part of equipment as claimed in any one of claims I to 5, wherein the method comprises the steps of inserting the plug and sheath into the hole and injecting a fixing agent into the sheath.

7. A method of anchoring a hollow fixing plug in a hole, the method being as claimed in claim 6 and substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

8. An anchorage comprising a hollow fixing plug mounted in a hole, a sheath which surrounds the plug, the sheath being filled with a hardened material, the said material having caused expansion of the sheath radially about the axis of the plug, the sheath being constructed of an anisotropic material so that expansion of it in a direction along the axis has been restricted.

9. An anchorage substantially as hereinbefore described with reference to and as illustrated by the accompanying drawing.

10. Anchoring of a hollow fixing plug in a hole, in a panel or wall and especially a cavity wall, by filling, with a fixing agent, an expansible sheath which is pulled over the plug, is closed at its front end and secured at its rear end to the plug, wherein the sheath consists of an anisotropic fabric and can expand only radially relative to the plug.