Anchoring device

Abstract: An anchoring device, illustrated as a wall tie, comprises an elongate tubular body (5), a plunger (6) axially movable in the bore of the body to operate gripping means (9,10) in the form of transverse dog plates (13, 15) which axial movement of the plunger (6) causes to project through openings in the body to engage the surface of a hole drilled in a structure to which the device is to be secured. The wall tie may have gripping means at each end to engage co-axial holes in two leaves of a cavity wall. Alternatively one or each gripping means may be replaced by a waisted, windowed portion of the wall of the body to be secured in the hole by synthetic resin. Means may be provided for connecting a grip-testing device to the wall tie and a modification allows the grip of gripping means (9) to be tested before the gripping means (10) is operated.

Description: This invention relates to an anchoring device for providing a fixing in a wall, floor or other structure and particularly, though not exclusively, to a wall tie for connecting the inner and outer leaves of cavity walls of buildings. Wall ties embedded in the mortar courses are incorporated during the building of brick or block cavity walls. In many older buildings the original wall ties of steel have been weakened by rusting to such an extent that they have broken or are dangerously weak. Replacement is necessary. It is possible by removing bricks to replace old wall ties by new ties similarly embedded in mortar but this is a very laborious and time consuming process. Many proposals for fitting remedial wall ties have been made in which a circular hole is drilled through one leaf, usually the outer leaf, and partway through the other leaf, usually the inner leaf. Various forms of replacement ties to be fitted in such holes have been proposed. Some involve the use of synthetic resin to secure the tie or a nut element in at least one leaf of the wall. A delay is involved while the resin sets before the fixing of the tie can be completed as torque cannot be applied until the resin has set. Other replacement ties are of complex construction and high cost usually involving expansible portions for securing the tie in the inner and outer leaves. In some buildings one leaf of a cavity wall is made of breeze block or similar material which is softer than brick or concrete used for the other leaf. Mechanical gripper means may not grip satisfactorily in softer materials and resin affords a better connection to the wall material. BE-A-787445 discloses a device for securing cladding elements to a wall. It is generally cylindrical and has axial and radial passages through which bonding resin is injected to secure the device within holes in the wall and the cladding. GB-A-1 350 749 discloses a method of securing an anchor insert in a hole in a structure. The insert comprises a metal cylinder, one end of which having a windowed portion formed by strips and slits the outer surface of which is serrated. The insert is placed in a hole, and bonding material injected into it. By driving a plug into the bore of the insert the bonding material is forced through the slits of the windowed portion into the space between the insert and the hole. The bonding material is allowed to harden thereby retaining the insert in the hole which retention is enhanced by the serrations. Driving the plug into the insert also forces the strips of the windowed portion outwards. This limits the amount of bonding material which is situated around the windowed portion or bonding site. DE-A-3 209 018 discloses an anchoring device comprising a pin with a spreader cone, and a sleeve. A capsule of resin is stuck on the front end of the cone, the hardener for the resin formed in a ring around the cone. On driving the device into a hole, the capsule releases the resin, and the sleeve powders the hardener, the two mix, securing the device in the hole. In order for this invention to function, a destructible capsule must be in place on the end of the pin, resulting in a somewhat complicated and expensive device. In US-A-3269251 a self-retaining insert is provided which is adapted to be fixed in a hole in a workpiece without the use of resin or other bonding material. The insert comprises a cylindrical sleeve which is internally screw-threaded to function as a nut and has L-shaped teeth which are caused to be projected radially from the sleeve to be embedded in the walls of the hole to secure the insert in the hole. The teeth are angularly spaced around the sleeve, some within the length of the sleeve and others extending from an inner end of the sleeve. They are joined at one end of the L-shapes to the body of the sleeve and have their opposite, free, ends formed into sharp-edge tips. Initially the L-shapes of the teeth are angled inwardly of the sleeve so that the tops do not protrude beyond the outside diameter of the sleeve. This allows free entry of the sleeve into the hole. A removable shaft slidable in the sleeve is driven along the sleeve to urge the teeth outwards so as to project the tips from the sleeve and embed them in the wall of the hole. Thus retention of the insert in the hole requires the mechanical action of embedding the teeth in the walls of the hole. An object of the present invention is to provide an anchoring device which is simple and inexpensive to make and quick and easy to fit and, in its application to a remedial wall tie, is an improvement in some, at least, of these respects on replacement wall ties so far available. From a first aspect the present invention provides an anchoring device adapted to be fitted in a hole drilled in a structure to which the device is to be secured by synthetic resin, comprising an elongate tubular body having adjacent one end a windowed portion comprising longitudinal strips separated by slots forming windows through the tubular body, the strips being bowed inwards towards a central longitudinal axis of the tubular body such that the windowed portion is bodily waisted, the internal cross-section of the tube is reduced and the windows diminish in width towards medial parts of the lengths of the strips, characterised in that the bore of the tubular body is closed by a disc near to the windowed portion and the windowed portion is between the disc and said adjacent end of the tubular body, the arrangement being such that, in use of the anchoring device, on fitting the device in the hole, substantial local clearance is left between the windowed portion and the surface of the hole to receive synthetic resin for keying with the windowed portion and in the windows to secure the device in the hole in the structure, and the disc serves to prevent flow of resin along the bore of the tubular body from the windowed portion. From a second aspect the invention provides a method of securing an anchoring device in a hole in a structure, characterised by the steps of introducing synthetic resin into the hole and fitting into the hole an anchoring device in accordance with the foregoing first aspect of the present invention so that the windowed portion of the anchoring device is received within the hole and there is substantial local clearance between the windowed portion and the surface of the hole for the synthetic resin to key to the windowed portion and in the windows to secure the device in the hole, the disc of the device preventing flow of the resin along the bore of the tubular body away from the windowed portions as the portion is received within the hole to be secured and acting as a piston to urge the resin through the windows. The anchoring device may be in the form of a wall tie to be fitted in aligned holes in inner and outer leaves of a cavity wall, and have one of said windowed portions at each end of the tubular body. The anchoring device may be a remedial wall tie. The outer end of the tubular body may be provided with means for releasably connecting a testing device for testing the grip of the anchoring device in the structure on an adaptor for coupling such a testing device to the anchoring device. Testing devices for remedial wall ties are usually provided with an internally screw-threaded socket to engage 6mm screw-threaded ends of wall ties of the rod-type. To enable the grip of wall ties according to the present invention to be tested by standard equipment, an adaptor may be provided having a 6mm screw-threaded shank and a spigot, the diameter of which fits easily into the bore of the tubular body of the wall tie. Interengaging formations may be provided on the spigot and the tubular body engageable on insertion of the head in the bore of the tubular body. For example, the spigot may be inserted axially and then turned to cause the formations to interengage. The adaptor is secured to the wall tie by the interengaging formations and the testing device is connected to the adaptor by the screw-threaded shank. One suitable form of the interengaging formations is a bayonet joint, bayonet slots being provided at the outer end of the tubular body to receive radial pins projecting from the spigot of the adaptor. In another example, projections extending inwardly into the bore of the tubular body are engaged by a spigot the free end of which forms a head the full diameter of which suits the bore of the tubular body. The head has gaps which allow it to pass the projections. Then by turning the adaptor in the bore of the tubular body the head is engaged behind the projections. Anchoring devices in accordance with the first aspect of the present invention, and similar to wall ties in being able to be fixed at opposite ends, may be used to secure together structural components, for example cladding to the face of a building, by drilling aligned holes to receive the anchoring devices in both materials. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a longitudinal section of an anchoring device shown in an operative condition, and Figure 2 is an end elevation of Figure 1 in the direction of the arrow A in Figure 1; In this embodiment of the invention an anchoring device is provided in the form of a remedial wall tie. The wall tie comprises a tubular body 5, a plunger 6, guide tubes 7, a set of gripping means 10 at an outer end of the tubular body 5 and a windowed formation 11 at the opposite, inner, end. The tubular body 5 and the guide tubes 7 are formed from sheet material rolled into a tube leaving in the tubular body 5 an axial slit 12 between the edges of the strip. A drain hole 13 is pierced through the wall of the tubular body 5 opposite the slit 12. Further drain holes 13' are pierced through the wall on opposite sides of the tubular body and evenly angularly spaced from the drain hole 13 and the axial slit 12. Close to the inner side of the drain holes 13, 13' a nylon sealing washer 14 is fitted in the bore of the tubular body 5. A lug 15 on the sealing washer 14 engages the slit 12. The sealing washer 14 has a central aperture complementary to the cross-section of the plunger 6 which is made from flat strip having inclined portions 16 formed in its narrower edges towards the outer end of the tubular body. The plunger 16 extends through and co-operates with dog plates 17, 18 of the gripping means 10 axially spaced apart on the plunger by guide plates 19, 20, 21. The dog plates 17, 18 and guide plates 19, 20, 21 are positioned at a pair of opposed openings 22 in the wall of the tubular body 5 through which the dog plates are caused to be projected transversely from the body, as shown in the drawings, by the inclined portions 16 of the plunger 6 when the plunger is driven axially along the tubular body to an operative position towards the windowed formation 11. The plunger 6 is long enough to remain in engagement with the sealing washer 14 in a pre-operative condition in which it projects from the outer end of the tubular body. As illustrated, the guide tubes 7, for convenience in manufacture, are all of similar length and some do not occupy the full, axial dimensions between other components. To hold the guide tubes 7 and other small components in position during assembly 0-rings may be fitted around the plunger on each side of the component or sub-assembly of components of the gripping means 10 which is to be located. Beyond the inner end of the plunger in the operative condition shown in Figure 1, a nylon disc 23 closes the bore of the tubular body 5. In so far as the wall tie includes the gripping means it is in accordance with the anchoring device claimed in our European Patent No. 0 238 265. The gripping means is operable to secure the wall tie in a hole in an outer leaf of a cavity wall. Securing the wall tie at an inner leaf of the cavity wall is by means of resin and the windowed formation, the latter fitting into a blind hole in the inner leaf. The windowed formation 11 comprises angularly spaced, narrow, longitudinal strips 24 of the tubular body formed and separated from one another by piercing rectangular slots, forming windows 25, through the material of which the tubular body is made. The strips 24 and the windows 25 extend from near the inner end of the tubular body 5 nearly to the disc 23. The strips 24 are bowed radially inwards until their edges at their mid-points meet or nearly meet. The shape of the initially rectangular windows 25 is altered by this operation so that each window 25 is closed or becomes very narrow at the middle and widens from there into generally triangular-shaped ends. The whole inner end of the tube is given a waisted form leaving substantial local clearance between the strips 24 and the surface of the hole in the wall into which the wall tie is fitted. Resin injected into the blind hole in the inner leaf of the wall before the wall tie is put in will, on insertion of the wall tie, flow through the windows 25 enveloping the whole of the inner end of the tubular body 5 in resin. When the resin has set, the windowed formation 11 affords a very good key between the resin and the wall tie. The disc 23 prevents the liquid resin from flowing along the bore of the tubular body 5 and acts as a piston urging the resin through the windows 25. Instead of the resin being injected into the blind hole of the inner leaf of the wall, it may be provided in a frangible capsule an end of which is fitted into the inner end of the wall tie before insertion. The capsule projects axially from the wall tie and is fractured by being compressed between the blind end of the hole and the end of tubular body on insertion of the wall tie. Alternatively the capsule of resin may be fitted during manufacture of the wall tie into the bore of the tubular body 5 between the end of the plunger 6, which may then be shorter than illustrated in Figure 1, and the windowed formation 11, the sealing washer being perforated for the plunger to pass through to fracture the capsule. Although the wall tie illustrated in the drawings is intended for cavity walls, its features may be used in generally similar anchoring devices for securing together structural components, with or without a gap between them, for example, for securing cladding panels to the face of a wall of a building, as by drilling a hole for the anchoring device through the cladding and part way into the wall, inserting and securing the anchoring device and plugging the exposed hole in the cladding.

Claims: An anchoring device adapted to be fitted in a hole drilled in a structure to which the device is to be secured by synthetic resin, comprising an elongate tubular body (5) having adjacent one end a windowed portion (11) comprising longitudinal strips (24) separated by slots forming windows (25) through the tubular body, the strips (24) being bowed inwards towards a central longitudinal axis of the tubular body such that the windowed portion (11) is bodily waisted, the internal cross-section of the tube is reduced and the windows (25) diminish in width towards medial parts of the lengths of the strips, characterised in that: the bore of the tubular body (5) is closed by a disc (23) near to the windowed portion (11) and the windowed portion is between the disc (23) and said adjacent end of the tubular body, the arrangement being such that, in use of the anchoring device, on fitting the device in the hole, local clearance is left between the windowed portion (11) and the surface of the hole to receive synthetic resin for keying with the windowed portion and in the windows (25) to secure the device in the hole, and the disc serves to prevent flow of resin along the bore of the tubular body from the windowed portion. An anchoring device according to claim 1 characterised in that it is in the form of a wall tie to be fitted in aligned holes in inner and outer leaves of a cavity wall and has one said windowed portion (11) at each end of the tubular body (5). An anchoring device according to claim 2 characterised in that the tubular body (5) has an outer end provided with means for releasably connecting a testing device to the tubular body for testing the grip of the anchoring device in the structure, or an adaptor for coupling such a testing device to the anchoring device, the device and adaptor having interengaging formations for releasably coupling the adaptor and anchoring device together. An anchoring device according to any preceding claim, characterised in that a plunger (6) is provided in, and is axially movable along, the tubular body (5) and a frangible resin capsule is located in the tubular body between the windowed portion (11) and the plunger, the plunger being operable to fracture the capsule and release the resin when the anchoring device is inserted in the hole. A method of securing an anchoring device in a hole in a structure, characterised by the steps of introducing synthetic resin into the hole and fitting into the hole an anchoring device as claimed in any one of claims 1 to 3 so that the windowed portion (11) of the anchoring device is received within the hole and there is a substantial local clearance between the windowed portion and the surface of the hole for the synthetic resin to key to the windowed portion and in the windows (25) to secure the device in the hole, the disc (23) of the device preventing flow of the resin along the bore of the tubular body away from the windowed portion as the portion is received within the hole to be secured and acting as a piston to urge the resin through the windows (25). A method of securing an anchoring device according to claim 5, characterised in that the resin is in a frangible capsule inserted in the hole before the anchoring device is fitted in the hole, the capsule being fractured by the tubular body (5) to release the resin for keying with the windowed portion (11) when the anchoring device is inserted in the hole. A method of securing an anchoring device according to claim 5, characterised in that the resin is in a frangible capsule located in the tubular body (5) between the windowed portion (11) and a plunger (6) which is axially movable relative to the tubular body (5) to fracture the capsule and release the resin when the anchoring device is inserted in the hole.

Inventors: CHAMBERS JOHN THOMAS, CHAMBERS, JOHN THOMAS
Applicants: BAKER & FINNEMORE LTD, BAKER & FINNEMORE LIMITED
Application year: 1987
Main classification: E04B2
IPC codes: F16B13, E04G23