A releasable expansion bolt

Abstract

There is provided a releasable expansion bolt, comprising an elongate body having a longitudinal axis; an internal passageway passing through the elongate body parallel to the longitudinal axis, for receipt of an actuation member; an aperture formed in the elongate body; and an expansion member in the aperture and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body, wherein the expansion member is engaged with an engagement surface of the actuation member such that displacement of the actuation member in a first direction displaces the expansion member outwardly to project beyond an outer surface of the elongate body and displacement of the actuation member in a second, opposite direction displaces the expansion member inwardly

Description

A RELEASABLE EXPANSION BOLTTechnical Field

[0001] The present invention relates to expansion bolts, and in particular to expansion bolts that are releasable.Background of the Invention

[0002] Anchor bolts are fastenings used in the construction industry to secure a first object or substrate to a second object or substrate. Anchor bolts include post-installed anchors, which are installed after a substrate has been prepared, or cast-in-place anchors, which are installed before a substrate has been prepared. Often, the prepared substrate is concrete that has been poured and allowed to set, and the anchor bolt is used to secure fittings, such as steel fittings, to the concrete. To install post-installed anchors, a hole is drilled into the substrate that is of great enough diameter and length to accommodate at least a portion of an anchor bolt, which can then be inserted into the hole and subsequently secured.

[0003] Cast-in-place anchors have the disadvantage that the user must predict precisely where the anchor bolt needs to be positioned before the substrate has been prepared. This can be difficult as it does not accommodate changes decided upon or necessitated during construction. It also means that a subsequent phase of construction cannot begin immediately after fitting the anchor. Conversely, placement of a post-installed anchor is made after the substrate has been prepared and so can be done once the required positioning has been decided upon.

[0004] There are several forms of post-installed anchors, and these forms generally fall into two categories: mechanical anchors and adhesive anchors, although other anchors employ properties of both mechanical and adhesive anchors. Mechanical anchors function by applying one or more physical forces to the substrate to secure the anchor in place. Adhesive anchorsrequire the use of an adhesive to bond the substrate to the anchor to secure it in place. Resins are often used as adhesives. Adhesive anchors work by injecting a resin into a pre-drilled hole in the substrate and then inserting a fixing stud or bolt. Once inserted, the stud / bolt bonds with the resin to create a strong anchor point.

[0005] Adhesive anchors that use resin are known to have several disadvantages relative to mechanical anchors. First, resins must be allowed to cure before they can be tightened or loaded, and the time taken to cure is heavily dependent on temperature. Therefore, the adhesive anchor cannot be used right away. Conversely, mechanical anchors can be used as soon as they have been installed and so there is no delay needed before moving onto the next step in a construction project. Second, resins are not resistant to heat to the same degree as an anchor, which is typically made from a metal or a metal alloy, and which itself is a very good conductor of heat. As such, in the event of a fire, the anchor can act to conduct heat to the resin causing it to degrade, disintegrate and / or soften as its temperature increases. As a result, the anchor may fall out of position or loosen such that an object or substrate attached by the anchor to another object or substrate is no longer secured. In building fires, this can contribute towards a degradation of structural integrity of the building where adhesive anchors have been used to secure objects and / or substrates in place, ultimately leading to a total collapse of the building structure. Conversely, mechanical anchors require no resin, and so fire is less likely to impact their functionality and the security of their position, given that the structural integrity of metals and metal alloys used for such anchors is typically higher than the temperature at which a resin used in the construction industry deforms, disintegrates and / or softens. The application of bonded resin anchors requires exacting precision given that they are permanent fixings. However, when used in construction, any application of load prior to curing, whether from a structural load or several tonnes of pressure from concrete mix, can dislodge the anchor. The performance of an adhesive anchor is also heavily dependent on the environment in which it is used. For example, wet and / or dirty environments with poorly cleaned drill holes can severely impact the bonding performance, with the anchor coming loose from the substrate, and reducing the adhesive anchor’s load-bearing capacity. Perhaps most significantly, resinbonded anchors cannot be dismantled and as such are not suitable for temporary structures or any installation where changes will subsequently need to be made.

[0006] Different forms of mechanical anchor rely on different forces or combinations thereof to secure the anchor to a substrate. Mechanical anchors include expansion anchors and clamp anchors / bolts.

[0007] As an example of a clamp anchor, US2014056668A1 discloses a bolt for the detachable connection of two component parts provided with at least one through-hole and a clamping system serving for detachably interconnecting objects provided with through-holes. A bolt housing has through-openings, clip means are supported in the through-openings, and a clamping device is arranged in the housing's interior and provided with an external thread, which meshes with an internal thread of the housing and during clamping, forces the clip means out of the housing such that an outer portion of the clip means protrudes from the through- openings.

[0008] US2018051736A1 discloses another clamp anchor for clamping adjoining parts, which includes a bolt body adapted for insertion in openings of the adjoining parts from one side of the adjoining parts. An actuator is received in the bolt body and actuatable from one end of the bolt body. Mounted in the bolt body and interacting with the actuator is a clamping mechanism which includes tilting elements configured to tilt out of the bolt body in opposition to a restoring force, when the actuator is actuated.

[0009] Conversely, expansion anchors apply frictional forces to the walls of the hole into which they are transferred. Multiple forms of expansion anchor exist. However, current expansion anchors are either not releasable in the sense that, once installed, at least part of the anchor and / or the substrate(s) / object(s) to which they are secured must be destroyed if every component of it is to be removed, or else they involve multiple steps to uninstall the anchor. Both are inconvenient, with the former also not being cost-effective. They also do not provide a hold (firm fixing) until a load is applied to the central bolt.

[0010] For example, CN109184767A discloses a tension-expandable hollow grouting anchor structure belonging to the technical field of fractured rock reinforcement. The structure includes a hollow grouting rod body and a lateral extruding device, which includes a sleeve, multiple expanding rods and multiple tapered blocks. The multiple expanding rods radially pass through expansion holes correspondingly set on the sleeve. The multiple tapered blocks are sleeved on the hollow grouting rod body and, in use, the sleeve is stretched, and the expansion rods are squeezed outwards along the tapered surface of the corresponding tapered blocks in a sliding mode. The structure is said to improve an anti-pulling performance of the anchor, making it clearly unsuitable for removal and reuse.

[0011] Further, CN217055856U discloses an expansion bolt assembly comprising an expansion nail and a conical core, wherein the expansion nail comprises a conical end head, a pipe body and an annular separation blade which are connected in sequence, and wherein the conical end head is composed of a plurality of front fanning strips and a plurality of rear fanning strips. The conical core is said to only play a role in bearing stress and overcoming the elasticity of the conical end head in the process of nailing the expansion nail, and so the conical core is not needed after nailing, and can be reused.

[0012] Further, GB2304850A discloses a bolt having four elongate segments configured to be positioned side-by-side to form a cylindrical body, and having their ends located in a bush and their ends moved apart by a cone or pyramid nut drawn between them by a screw extending through an opening in the bush, with grooves in the segments facilitating the splaying of the segment ends. The nut has lugs which are retained in spaces formed by lateral projections of the segment ends consisting of four or more elements with an outwardly arch-shaped form, to allow the bolt to be deformed to take on a slightly tapered cone shape thanks to the movement of a nut inside these radial elements, causing the entire external surface of the bolt to press on the inside walls of a hole in which it is fitted. To remove this bolt, all the substrate / object in which it is installed must be broken.

[0013] Finally, US2024263659A1 discloses a releasable expansion bolt having an expansion sleeve and, on the inside, an inner cone section, a cone bolt with a cone section which interacts with the inner cone section for expanding the expansion sleeve as a result of an axial relative movement of the expansion sleeve and the cone bolt, and a tensioning device. Multiple steps are required to release a connection arrangement comprising at least two assembly parts to be connected to one another and at least one expansion bolt of the disclosure; namely, the pressure bolt must be unscrewed and then the cone bolt must be pulled out by a tensile force applied to it. This is cumbersome and less practical than a device that can be removed in fewer steps and without additional equipment.

[0014] It is an aim of the present invention to overcome or mitigate some or all of the aforementioned drawbacks of the prior art.Summary of the Invention

[0015] In an embodiment, there is provided a releasable expansion bolt, comprising an elongate body having a longitudinal axis; an internal passageway passing through the elongate body parallel to the longitudinal axis, for receipt of an actuation member; an aperture formed in the elongate body; and an expansion member in the aperture and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body, wherein the expansion member is engaged with an engagement surface of the actuation member such that displacement of the actuation member in a first direction displaces the expansion member outwardly to project beyond an outer surface of the elongate body and displacement of the actuation member in a second, opposite direction displaces the expansion member inwardly. The releasable expansion bolt can be installed regardless of thermal and environmental restrictions, providing the possibility of immediate loading in all conditions, requiring no curing time. The releasable expansion bolt can also be used in conjunction with a bonding resin, if desired, providing an additional failsafe redundancy to the structure for example, if the resin where to fail in the event of a fire, as the expansion bolt provides a firm mechanical fixing to take the load. The expansion bolt does not require the application of a load in order to providea firm fixing. Rather, the expansion members provide a firm fixing within the substrate, giving the advantage of having a bolt secured in placed prior to application of a load. Significantly, the expansion bolt is releasable, meaning it can be removed from a substrate and subsequently reused, making it ideal for use in temporary structures and applications where subsequent modifications are required.

[0016] The releasable expansion bolt is configured to provide an anchor for convenient and rapid post-installation and removal. The advantageous configuration allows for the displacement of an expansion member along a displacement axis inclined to the longitudinal axis of the elongate body. Outwardly displacement along the displacement axis provides a contact point with the wall(s) of a cavity into which the bolt is installed, via which frictional forces are applied to the wall(s) of the cavity. The contact point provides stability to the post-installed bolt. The threaded rod is reversibly received by the actuation member, allowing for simple reversal of the engagement between the threaded rod and the actuation member, and so between the engagement surface of the actuation member and the expansion member. This allows for a reduction in the frictional force(s) applied by the expansion member to the wall(s) of the cavity upon reversal of the engagement between these components, and for the expansion member to be displaced inwardly along the displacement axis, enabling a user to uninstall the bolt without damaging any of its component parts, or otherwise disrupting its functionality, allowing it to be reused in its entirety at a later date, as well as without damaging the substrate within which the cavity was formed.

[0017] Optionally, the outer peripheral face of the elongate body is cylindrical. This shape allows for insertion of the bolt into a prepared circumferential cavity, such as would typically be prepared by a drilling action in the construction industry. A cylindrical elongate body is particularly advantageous for insertion and installation of the bolt in a circumferential cavity because the bolt can be positioned such that, in any rotational orientation around a longitudinal axis, the expansion member is proximate to a wall of the cavity and so the substrate to be engaged by the bolt. Thus, installation may be performed rapidly and conveniently.

[0018] Optionally, the releasable expansion bolt comprises a plurality of apertures formed in the elongate body in each of which one of a plurality of expansion members is located, each engaged with a respective engagement surface of the actuation member. The use of a plurality of expansion members provides improved stability of the bolt in use by providing more than one contact point configured to limit or prevent movement in a radial and / or a rotational direction.

[0019] Further optionally, the plurality of apertures are equiangularly spaced around the elongate body. The plurality of expansion members in the plurality of apertures are therefore displaced from these equiangularly spaced apertures. As such, this positioning of the plurality of apertures provides further improved stability of the bolt in use by providing contact points at regular radial positions between the plurality of expansion members and a surrounding substrate with which they engage. The expansion members are configured to limit or prevent movement of the bolt in a radial and / or a rotational direction after installation (i.e., after the expansion members have been displaced outwardly and come into frictional contact with a substrate), and so this positioning limits or prevents the movement in any direction once installed.

[0020] Further optionally, the plurality of apertures comprises two or more apertures. Still further optionally, the plurality of apertures comprises three apertures. The advantage of a plurality of apertures, and therefore a plurality of expansion members, is discussed immediately above. The use of three apertures, and therefore three expansion members, provides stability of the apparatus in use in all directions against radial and / or rotational movement by providing sufficient contact points to limit or prevent such movement.

[0021] Optionally, the actuation member is constrained from rotating about the longitudinal axis. This ensures that each engagement surface of the actuation member is retained in alignment with its respective aperture and expansion member to allow correct functioning of the bolt.

[0022] Optionally, the actuation member comprises an internally threaded bore formed parallel to the longitudinal axis for receipt of a threaded rod; and further optionally, the internally threaded bore is positioned in the radial centre of the actuation member. The threaded configurations of these features facilitate the reversible engagement of the actuation member by the threaded rod. The positioning of the bore in the radial centre of the actuation member facilitates even radially outward movement of each expansion member ( / .e., movement along an equally sized radially outward distance relative to the longitudinal axis of the threaded rod), such that each expansion member comes into contact with, and exerts frictional pressures on, a surface of a circumferential cavity at the same distance from the longitudinal axis of the threaded rod, or at approximately the same distance therefrom (e.g., within 1 , 2, 3, 4, 5 or more millimetres from the longitudinal axis of the threaded rod) in use. Where only one expansion member is used, no comparative distances are required. This improves engagement of each expansion member with the wall(s) of the cavity of the substrate with which it is engaged.

[0023] Further optionally, clockwise rotation of the threaded rod about the longitudinal axis displaces the actuation member in the first direction. This facilitates ease of actuation, which displaces each expansion member outwardly (in use, towards the wall(s) of a cavity) and allows for installation of the bolt in situ.

[0024] Further optionally, anti-clockwise rotation of the threaded rod about the longitudinal axis displaces the actuation member in the second direction. This facilitates ease of actuation, which displaces each expansion member inwardly (in use, away from the wall(s) of a cavity) and allows for uninstallation of the bolt.

[0025] Optionally, each engagement surface of the actuation member comprises a portion that is inclined to the longitudinal axis. A portion inclined to the longitudinal axis may provide a ramped portion of the surface, which facilities a sliding motion during actuation relative to a respective expansion member, and facilitates a gradual increase in displacement of the expansion member.

[0026] Optionally, each aperture is longitudinally elongated, and each expansion member is sized to have width and length dimensions the same as, or smaller than, the width and length dimensions of its respective aperture. Longitudinally elongate apertures accommodate larger expansion members than, for example, pointed expansion members. As such, expansion members with larger surface areas may be used, which can produce greater frictional force(s) when applied to the wall(s) of a cavity, improving the stability and security of the bolt in use.

[0027] Optionally, each expansion member has a resting surface configured to rest against its respective engagement surface of the actuation member, and a bracing surface configured to engage with a substrate surface in use. A bracing surface is a surface that is braced against the wall(s) of a cavity of a substrate and via which frictional forces are applied to the wall(s) of the cavity. The bracing surface allows for application of frictional forces within the cavity. A resting surface is a surface that is positioned adjacent to the engagement surface of the expansion member’s respective engagement surface. The resting surface provides a point of contact via which the actuation member can actuate the expansion member.

[0028] Further optionally, the bracing surface is non-smooth. A non-smooth bracing surface is configured to generate greater frictional forces relative to the wall(s) of a cavity than a smooth bracing surface when forced outwardly along the displacement axis.

[0029] Still further optionally, the non-smooth bracing surface is grooved, threaded, engraved, embossed or patterned. These are provided as non-limiting examples of non-smooth bracing surfaces that generate greater frictional forces relative to the wall(s) of a cavity than a smooth bracing surface when forced outwardly along the displacement axis.

[0030] Optionally, the outer peripheral face of the elongate body is non-smooth. This facilitates engagement of the bolt with one or more objects positioned proximally relative to one or more substrates secured by the action of the expansion member(s) when forced outwardly along the displacement axis. It may also allow for the elongate body to be engaged with one or more sympathetically non-smooth cavities, substrates and / or objects.

[0031] Further optionally, the non-smooth outer peripheral face is grooved, threaded, engraved, embossed or patterned. These are provided as examples of a non-smooth outer peripheral face of the elongate body that facilitates engagement of the apparatus with one or more objects positioned proximally relative to one or more substrates secured by the action of the expansion member(s) when forced outwardly along the displacement axis. They may also allow for the elongate body to be engaged with one or more sympathetically non-smooth cavities, substrates and / or objects. Where a threaded external surface is used, the bolt can be positioned within a cavity of the substrate at one end, with a load securely fastened at the other end with a nut. The threaded face also provides an increased surface area for greater hold where a resin is used in conjunction.

[0032] Optionally, the bolt further comprises an engagement portion at a proximal end of the elongate body, wherein the engagement portion has an external shape configured to be received by a wrench or a spanner. This allows for further engagement with, or removal of, the bolt using commonly available equipment, thus not requiring the user to have access to specialist equipment.

[0033] Optionally, the releasable expansion bolt further comprises one or more flexible securing features, configured to secure each expansion member in engagement with its respective engagement surface of the actuation member. The one or more securing features ensure that the expansion member(s) remain in engagement with its / their respective engagement surface(s) of the actuation member such that they can be displaced by displacement of the actuation member in both the first and second directions, making the device more easily releasable and reusable, without needing to replace features. The flexibility of the securing features allows them to repeatedly hold the expansion member(s) in place during and after displacement.

[0034] Further optionally, the one or more securing features are one or more open rings. An open configuration confers flexibility on the one or more open rings such that they can expand and retract as required by the position of the expansion member(s).

[0035] Optionally, the threaded rod comprises a head portion configured to receive a driver; further optionally, wherein the driver is a hex key or a hex key shank. It is envisaged that the head portion is a socket head, sized to correspond to the body size e.g. M20. However, other sizes could be used such as M 40- - M12. The headed portion is configured to receive a driver and allows the use of a driver to drive the threaded rod into engagement with the actuation member, facilitating the installation of the bolt through the use of appropriate, readily accessible tools. A hex key is a common type of driver, which allows the user to manually apply engaging forces to the threaded rod, or to use an appropriate electric tool for the purpose, such as an impact driver. This provides versatility, as well as enabling rapid and firm installation of the bolt. Configuring the head to also receive a hex key shank means that an impact driver fitted with a hex key shank can be used, enabling more secure installation, due to the increased torque that can be applied to the head by an impact driver relative to a hex key secured by hand, and also rapid reversal of installation.

[0036] Further optionally, the head portion is configured to be positioned within the dimensions of the elongate body when the threaded rod is received by the internally threaded bore of the actuation member. This protects the head portion within the confines of the elongate body to avoid damage that could make removing the bolt difficult or impossible without destroying or damaging the bolt and / or the one or more substrates and / or one or more objects with which it is engaged.

[0037] Further optionally, the head portion is configured as a hexagon for ease of use especially in smaller size diameters.

[0038] Optionally, one or more of the elongate body, the expansion member(s), the actuation member, the threaded rod and the one or more securing features comprise a metal or a metal alloy. Further optionally, the elongate body, the expansion member(s), the actuation member,the threaded rod and the one or more securing features are manufactured from the same metal or metal alloy. Still further optionally, the metal alloy is hardened steel and may also be coated for increased wear resistance. These materials are resistant to physical strains and impacts, and are resistant to heat damage at higher temperatures than some plastics, as well as some resins / adhesives that are used to secure adhesive anchors. As such, they are a resilient material that is more likely to resist forces applied during construction, and to remain secure during emergencies such as fires once installed.

[0039] Optionally, the elongate body has a major diameter of between approximately 10 mm and 60 mm. The use of an elongate body selected from a range of major diameters allows for the use of the apparatus in cavities of different diameters, as may be required in construction projects in which multiple different substrates and / or objects are to be installed. This range of major diameters is compatible with cavities drilled using readily available and common drill bits in the construction trade.

[0040] Optionally, the releasable expansion bolt is configured to releasably and securely engage one or more substrates and / or one or more objects without additional securing means. This means that additional securing means, such as adhesives, are not required to install and operate the bolt. For example, an adhesive like a resin would make removal and reuse of the bolt more difficult and could slow down construction as more time would need to be allowed for the resin to set.

[0041] In another embodiment, a kit of parts is disclosed, which comprises an elongate body having a longitudinal axis; an internal passageway passing through the elongate body parallel to the longitudinal axis, for receipt of an actuation member; an aperture formed in the elongate body; and an expansion member in the aperture and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body, wherein the expansion member is engaged with an engagement surface of the actuation member such that displacement of the actuation member in a first direction displaces the expansion member outwardly to project beyond an outer surface of the elongate body and displacement of the actuation member in asecond, opposite direction displaces the expansion member inwardly. The kit can be assembled into a complete releasable expansion bolt by the user.Brief description of the drawings

[0042] The invention is described below with reference to the drawings, by way of example only, which are as follows:

[0043] Fig. 1 is a perspective view of a releasable expansion bolt in accordance with an embodiment of the present invention, wherein the longitudinal axis is denoted as a solid line between points A and A’.

[0044] Fig. 2 is a top-down view of the releasable expansion bolt of Fig. 1 .

[0045] Fig. 3 is a perspective of a part of the threaded rod, a part of the elongate body, and the shoulder of the releasable expansion bolt of Fig. 1 .

[0046] Fig. 4 is a top-down view of the actuation member of the releasable expansion bolt of Fig. 1.

[0047] Fig. 5 is a perspective of the actuation member of the releasable expansion bolt of Fig. 1.

[0048] Fig. 6 is a side view of the first portion of the elongate body and one of the plurality of expansion members of the releasable expansion bolt of Fig. 1.

[0049] Fig. 7 is a side view of the releasable expansion bolt of Fig. 1 , wherein the plurality of expansion members are displaced inwardly.

[0050] Fig. 8 is a side view of the releasable expansion bolt of Fig. 1 , wherein the plurality of expansion members are displaced outwardly.Detailed description

[0051] In an embodiment according to Fig. 1 , there is provided a releasable expansion bolt 1 , comprising an elongate body 2 having a longitudinal axis; an internal passageway passing through the elongate body 2 parallel to the longitudinal axis, for receipt of an actuation member16; an aperture 24 formed in the elongate body 2; and an expansion member 26 in the aperture24 and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body 2, wherein the expansion member 26 is engaged with an engagement surface 20 of the actuation member 16 such that displacement of the actuation member 16 in a first direction displaces the expansion member 26 outwardly to project beyond an outer surface of the elongate body 2 and displacement of the actuation member 16 in a second, opposite direction displaces the expansion member 26 inwardly.

[0052] As shown in Fig. 1 , the longitudinal axis runs from the proximal end of the elongate body 2 to the distal end of the elongate body 2, between points A and A.

[0053] As shown in Fig. 1 , in some embodiments, the releasable expansion bolt 1 comprises a plurality of apertures 24 formed in the elongate body 2 in each of which an expansion member 26 is located, each engaged with a respective engagement surface 20 of the actuation member 16. In some embodiments, a plurality of apertures 24 are equiangularly spaced around the elongate body 2, although in other embodiments, the plurality of apertures 24 are non- equiangularly spaced around the elongate body 2. In some embodiments, the plurality of apertures 24 comprises two or more apertures 24, for example, the plurality of apertures 24 may comprise three apertures 24. Alternatively, the plurality of apertures 24 may comprise more than three apertures 24, such as four, five, six, seven, eight, nine, ten or more. Different numbers of apertures 24 may be more suitable in bolts 1 having different outer peripheral shapes of the elongate body 2.

[0054] In some embodiments, the aperture(s) 24 may be longitudinally sized to be any proportion of the length along the longitudinal axis of the elongate body 2 less than 100%; for example, 1 %, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, although these figures are not intended to be limiting and any proportion of the length of the elongate body 2 therebetween is also considered.

[0055] In some embodiments, including the embodiment in Fig. 1 , the outer peripheral face of the elongate body 2 is cylindrical. However, alternative embodiments are envisaged that would allow effective operation of the invention in circumferential cavities or cavities with non- circumferential profiles, including embodiments wherein the outer peripheral face of the elongate body 2 is quadrilateral, pentagonal, hexagonal or any other polygonal shape. In some embodiments, the elongate body 2 is threaded, in embodiments wherein the outer peripheral face of the elongate body 2 is cylindrical, this threaded configuration may allow for the elongate body 2 to be screwed into one or more sympathetically threaded cavities, substrates and / or objects, and / or may facilitate engagement of the bolt 1 with objects positioned proximally relative to one or more substrates secured by the action of the expansion member 26, or plurality of expansion members 26, when outwardly displaced along the displacement axis. Alternative non-smooth configurations are also envisaged in embodiments having any of the outer peripheral face shapes disclosed above, such as a grooved, engraved, embossed or patterned external surface, such as may facilitate engagement with one or more sympathetically non-smooth or receiving cavities, substrates and / or objects. In other embodiments, the first portion of the elongate body 2 may be substantially smooth in that it is manufactured to have a smooth external surface within manufacturing machine tolerances. This may assist with installing the bolt 1 in a cavity during use, as a smooth surface may be less likely to catch or snag on imperfections in the wall(s) of the cavity.

[0056] In some embodiments, including the embodiment in Fig. 1 , the bolt 1 further comprises an engagement portion 4 at a proximal end of the elongate body 2, wherein the engagement portion 4 is longitudinally of a smaller size than the elongate body 2. . The engagement portion 4 and elongate body 2 is cast from single metal piece and machined, Therefore, the engagement portion 4 is integrally formed with the elongate body 2 of the bolt 1 .

[0057] As shown in Fig. 2, in some embodiments, the engagement portion 4 has an external shape configured to be received by a wrench or a spanner, or a similar device. Generally, this external shape is a hexagon wherein each of the six sides are approximately or completely equal in length, to within machine tolerances. However, alternative external shapes areenvisaged, including but not limited to circular, quadrilateral, pentagonal and other polygonal shapes. In embodiments in which the outer peripheral face of the elongate body 2 is threaded and the external shape of the engagement portion 4 is hexagonal, the external shape of the engagement portion 4 allows the user to use a wrench or a spanner, or a similar device to reversibly engage the threading of the outer peripheral face of the elongate body 2 with sympathetic threading of one or more sympathetically threaded or receiving cavities, substrates and / or objects into or through which the invention is to be installed. In some embodiments, this functionality will also be possible with other external shapes of the engagement portion 4, such as circular, quadrilateral, pentagonal and other polygonal shapes.

[0058] In some embodiments, including the embodiments according to Figs. 2 and 3, the engagement portion 4 has an internal shape configured to receive a threaded rod 10. This internal shape forms a cavity through the engagement portion 4, such that the cavity has a radial wall, wherein the cavity is sized to receive the threaded rod 10. In some embodiments, the threaded rod 10 is affixed to, or has, a head or head portion 6, which is configured to receive a driver. In some embodiments the head or head portion 6 is a socket head. In some embodiments, the driver is a hex key (also known as a hex wrench, an Allen key or an Allen wrench), or a impact drill fitted with an engaging shank, such as a hex key shank. In embodiments configured to receive a hex key or a hex key shank, the proximal end of the head portion 6 comprises a hexagonal recess 8 sized and shaped to receive the hex key or hex key shank. In some embodiments, alternative sizes and shapes of recess 8 may be used to accommodate other drivers. In some embodiments, the head portion 6 has a larger diameter than the remainder of the threaded rod 10, which is configured to engage with the actuation member 16.

[0059] According to Fig. 3, in some embodiments, a proximal end of the elongate body 2 that abuts a distal end of the engagement portion 4 comprises or is attached to a shoulder portion 14 positioned within the elongate body 2 and / or the engagement portion 4. The shoulder portion 14 may be circularly ring-shaped such that it extends radially inward from the internal surface of the elongate body 2 and / or the engagement portion 4. Alternative configurations ofthe shoulder portion 14, including elliptical or straight shoulder edges, are also envisaged in other embodiments. The shoulder portion 14 may be positioned immediately at the proximal end of the elongate body 2, or it may be recess 8ed within the proximal end of the elongate body 2. The shoulder portion 14 may alternatively, or additionally, be positioned immediately at the distal end of the engagement portion 4, or it may be alternatively or additionally recessed within the distal end of the engagement portion 4. In use, the shoulder portion 14 is sized to allow passage of the threaded rod 10 but to prevent passage of the head portion 6 of the threaded rod 10 beyond the shoulder portion 14 and into, or further into, the elongate body 2. That is, the smallest dimension of the hole created by the shoulder portion 14 is larger than the diameter of the threaded rod 10 but smaller than the diameter of the head portion 6 of the threaded rod 10.

[0060] In some embodiments, the entirety of the threaded rod 10 is externally threaded, although in other embodiments the threaded rod 10 may be partially threaded. The threaded rod 10, including the head portion 6 in those embodiments in which it is present, is sized to have a shorter longitudinal length than the elongate body 2, (or the elongate body 2 plus the engagement portion 4, where present), so that, in use, it cannot be exposed to potential damage beyond the dimensions of the elongate body 2 (or the elongate body 2 plus the engagement portion 4, where present).

[0061] As shown in Figs. 4 and 5, in some embodiments, a bore hole 18 runs longitudinally through the actuation member 16 and the bore hole 18 is radially sized to accommodate the threaded rod 10. The threading of the threaded rod 10 is configured to sympathetically engage with sympathetic threading within the bore hole 18 of the actuation member 16. In such embodiments, in use, the external threading of the threaded rod 10 reversibly engages the threading of the bore hole 18 of the actuation member 16. The actuation member 16 is externally sized to fit inside the elongate body 2, by which it will be understood that the maximum radial dimensions of the actuation member 16 are smaller than the internal radial dimensions of the elongate body 2. In some embodiments, as the threaded rod 10 is turned by the user to engage the actuation member 16, the head portion 6 of the threaded rod 10abuts the shoulder portion 14, preventing the threaded rod 10 from moving further into the elongate body 2. As a result of this, turning the threaded rod 10 to further engage the receiving bore hole 18 of the actuation member 16 forces the actuation member 16 to move up the threading of the threaded rod 10 towards the proximal end of the bolt 1 ( / .e., where present, towards the engagement portion 4). The engagement between each engagement surface 20 of the actuation member 16 and their respective expansion member 26 constrains the actuation member 16 from rotating about the longitudinal axis. Alternative configurations to constrain the actuation member 16 from rotating about the longitudinal axis are also considered, such as one or more restraining surfaces being included on the external surface(s) of the actuation member 16 and / orthe internal surface of the elongate body 2. For example, in some embodiments, one or more protruding longitudinal ridges present in the internal surface of the elongate body 2 are configured to engage with one or more protruding longitudinal ridges present on the external surface(s) of the actuation member 16 so that rotational movement of the actuation member 16 is constrained. Alternatively, one of the internal surface of the elongate body 2 and the external surface(s) of the actuation member 16 may have one or more longitudinal recesses configured to engage the one or more protruding longitudinal ridges of the other of the internal surface of the elongate body 2 and the external surface(s) of the actuation member 16. The turning or screwing motion described can be achieved by the user via the use of a hex key or via the use of a percussive drill fitted with a hex key shank. The ability to use widely available tools to apply the screwing or turning motion makes embodiments configured to accept these drivers convenient for use as they do not require specialist equipment unlikely to be owned by the typical end user. Accommodation of a hex key shank fitted to a percussive drill allows for rapid and secure engagement of the apparatus in use, as well as rapid disengagement of the apparatus if it needs to be removed and / or reused.

[0062] Although a turning or screwing motion is described immediately above, it will be recognised that alternative means of, and configurations for, reversible engagement of the actuation member 16 are also envisaged. For example, in some embodiments, the bolt 1 comprises a non-threaded rod instead of the threaded rod 10, wherein the non-threaded rod has one or more protruding portions (for example, two, three, four, five or more) that reversiblyengage with one or more sympathetic indented portions (for example, two, three, four, five or more) in the receiving bore hole of the actuation member 16, wherein the receiving bore hole of the actuation member 16 is also non-threaded. In other embodiments, the engagement portion 4 of the non-threaded rod 10 has one or more indented portions (for example, two, three, four, five or more) that reversibly engage with one or more sympathetic protruding portions (for example, two, three, four, five or more) in the non-threaded receiving bore hole of the actuation member 16.

[0063] The actuation member 16 is formed from a cylindrical body having a circular vertical cross-section. The cylindrical body of the actuation member 16 has a central threaded bore hole 18 extending through the body in a direction parallel to the longitudinal axis A-A of the bolt 1 for receipt of the correspondingly threaded central rod 10.

[0064] As best seen in Fig. 5, three elongate recesses are formed in the outer surface, positioned equidistant around a circumference of the cylindrical body. Each recess is inclined with respect to the longitudinal axis of the bolt 1 and extends from a distal end of the actuation member 16 to a proximal end of the actuation member 16.

[0065] Each elongate recess aligns circumferentially with a respective expansion member 26. As previously described, the expansion members 26 are mounted within correspondingly shaped apertures 24 formed in the body portion of the bolt 1. Each elongate recess receives a correspondingly shaped projection portion formed by the inner face of the expansion member 26 such that the projection portion of each expansion member 26 restricts the actuation member 16 from rotating about the longitudinal axis A-A. The inner face of each expansion 26 member is inclined along its length with respect to the longitudinal axis A-A’ to form an interlocking ramp mechanism with the elongate recess, whereby rotation of the threaded central rod 10 results in the actuation member 16, constrained from rotating by the expansion members, to move in a direction parallel to the longitudinal axis A-A’, which in turn causes the expansion members 26 to move in the radial direction. Actuation of the expansion members is described in greater detail below.

[0066] In some embodiments, the actuation member 16 comprises an engagement surface 20. Referring again to Figs. 4 and 5, in some embodiments, the actuation member 16 comprises a plurality of engagement surfaces 20, which may be radially arranged. In embodiments comprising a plurality of engagement surfaces 20, the engagement surfaces 20 are interspersed by a plurality of non-receiving regions 22. Each of these non-receiving regions 22 has an outer surface. In some embodiments, the outer surface is the most radially distant from the bore hole 18 of the actuation member 16. In some embodiments, each outer surface is arcuate in shape such that, taken in combination, the outer surfaces of the plurality of nonreceiving regions 22 describe a circumference of the actuation member 16. In embodiments where it is centrally positions, the bore hole 18 forms the centre of the circumference of the actuation member 16. In embodiments comprising a plurality of engagement surfaces 20, the number of engagement surfaces 20 is two or more (e.g., two, three, four, five, six, seven, eight, nine, ten or more). The number of non-receiving regions 22 is the same as the number of engagement surfaces 20.

[0067] At the proximal end of the actuation member 16, each engagement surface 20 forms a shape cut out of the circumference of the actuation member 16, wherein each shape describes three sides of an oblong or square. No physical fourth side of the oblong or square exists but the person skilled in the art will appreciate that a fourth side of the oblong or square could be envisaged as the line connecting the vertices of the circumferential edges of the adjacent nonreceiving portions 22 separated by the engagement surface 20. In embodiments comprising an actuation member 16 having a bore hole 18. the base of the oblong or square is the side of the oblong or square nearest to the bore hole 18 of the actuation member 16. The same position of the base of the oblong or square, when considered relative to other features of the actuation member 16, is also seen in embodiments lacking a bore hole 18. The base of the oblong or square forms the proximal end of the engagement surface 20. In some embodiments, the proximal end of the engagement surface 20 is a non-straight side of a four-sided shape.

[0068] As shown in Figs. 4 and 5, in some embodiments, at the distal end of the actuation member 16, the circumferential edges of the adjacent non-receiving portions 22 separated bythe engagement surface 20 are connected by a straight line that is parallel to the base of the oblong or rectangle of the engagement surface 20 at the proximal end of the actuation member 16. The line forms the distal end of the engagement surface 20. In some embodiments, the line is the same width as the base of the oblong or square of the same engagement surface 20 at the proximal end of the actuation member 16.

[0069] The line at the distal end of the actuation member 16 (referred to hereinafter in this paragraph as “the line") is connected to the base of the oblong or square of the same engagement surface 20 at the proximal end of the actuation member 16 (referred to hereinafter in this paragraph as “the base of the oblong / square") by the engagement surface 20, which may be planar, or non-planar (e.g., ridged, stepped, undulating, sigmoidal or arcuate). It will be appreciated that, in some embodiments having a non-planar engagement surface 20, the non-planar engagement surface 20 may connect a non-straight line at the distal end and a nonstraight base of a four-sided shape at the end proximal end. In embodiments wherein the line is the same length as the base of the oblong / square or four-sided shape, the engagement surface 20 may have a width of the same dimension. In other embodiments, the engagement surface 20 may have a variable width. In embodiments wherein the line is of a smaller length or width than the base of the oblong / square or four-sided shape, the engagement surface 20 may a width that tapers from the base to the line. In some embodiments, the circumference described by the non-receiving portions 22 at the proximal end of the actuation member 16 has the same dimensions as the circumference described by the non-receiving portions 22 at the distal end of the actuation member 16. In some embodiments, the engagement surface 20 is abutted by a wall at a right angle ( / .e., 90 degrees) on one or both sides, although other angles of either / both walls are considered (e.g., 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees, 150 degrees, 160 degrees or 170 degrees). The top of each wall is the end of the circumference of the adjacent non-receiving portion 22 of the actuation member 16. At the proximal end of the actuation member 16, each wall is formed between the end of the base of the oblong / square or four-sided shape and the end of the circumferential edge of the actuation member 16. At the distal end of the actuation member 16, each wall is formedbetween the end of the line and the end of the circumferential edge of the distal end of the actuation member 16, which is the same vertex. The engagement surface 20 is therefore disposed at a shallower position relative to the circumference described by the non-receiving portions 22 at its distal end than it is at its proximal end, such that a portion, or the entirety, of the engagement surface 20 is inclined to the longitudinal axis.

[0070] In some embodiments, at the distal end of the actuation member 16, each engagement surface 20 forms a shape cut out of the circumference of the actuation member 16, wherein each shape describes three sides of an oblong or square. No physical fourth side of the oblong or square exists but the person skilled in the art will appreciate that a fourth side of the oblong or square could be envisaged as the line connecting the vertices of the circumferential edges of the adjacent non-receiving portions 22 separated by the engagement surface 20. The cut-out is positioned relative to a bore 18 hole in the actuation member 16 in the same way as the cut-out at the proximal end of the actuation member 16, as described above. In some embodiments, the distal end of the engagement surface 20 is a non-straight side of a four-sided shape In these embodiments, the width ofthe base of the oblong or square orfour-sided shape at the distal end of the actuation member 16 may be the same as the width of the base of the oblong / square or four-sided shape of the same engagement surface 20 at the proximal end of the actuation member 16, or smaller than it. The base of the oblong or square or four-sided shape at the distal end of the actuation member 16 is connected to the base of the oblong or square of the same engagement surface 20 at the proximal end ofthe actuation member 16 by the engagement surface 20, which may be planar, or non-planar (e.g., ridged, stepped, undulating, sigmoidal or arcuate). It will be appreciated that, in some embodiments having a non-planar engagement surface 20, the non-planar engagement surface 20 may connect a non-straight base of a four-sided shape at the distal end and a non-straight base of a four-sided shape at the end proximal end. In embodiments wherein the width of the base of the oblong or square or four-sided shape at the distal end of the engagement surface 20 is the same as the width of the base of the oblong or square at the proximal end of the engagement surface 20, the engagement surface 20 may have a width of the same dimension. In other embodiments, the engagement surface 20 may have a variable width. In embodiments wherein the width ofthe base of the oblong / square or four-sided shape at the distal end of the engagement surface 20 is smallerthan the width ofthe base ofthe oblong / square orfour-sided shape at the proximal end of the engagement surface 20, the engagement surface 20 may have a width that tapers from the proximal end to the distal end. In some embodiments, the circumference described by the non-receiving portions 22 at the proximal end of the actuation member 16 has the same dimensions as the circumference described by the non-receiving portions 22 at the distal end of the actuation member 16. In some embodiments, the engagement surface 20 is abutted by a wall at a right angle ( / .e., 90 degrees) on one or both sides, although other angles of either / both walls are considered (e.g., 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees, 150 degrees, 160 degrees or 170 degrees). The top of each wall is the end of the circumference of the adjacent non-receiving portion 22 of the actuation member 16. At the proximal end of the actuation member 16, each wall is formed between the end of the base of the oblong / square or four-sided shape and the end of the circumferential edge of the actuation member 16. At the distal end of the actuation member 16, each wall is formed between the end of the base of the oblong / square or four-sided shape and the end of the circumferential edge of the distal end of the actuation member 16. The engagement surface 20 is therefore disposed at a shallower position relative to the circumference described by the non-receiving portions at its distal end than it is at its proximal end, such that a portion, or the entirety, of the engagement surface 20 is inclined to the longitudinal axis.

[0071] Each engagement surface 20 is configured to be positioned in radial alignment with one radially arranged aperture 24. Each radially arranged aperture 24 is a manufactured hole cut into the elongate body 2. Each aperture 24 therefore has a width and a longitudinal length, as well as a depth wherein the depth is the thickness ofthe outer peripheral face ofthe elongate body 2 ( / .e., the distance from the external surface of the outer peripheral face to the internal surface ofthe outer peripheral face). In embodiments in which the elongate body 2 is internally threaded and / or externally threaded, the depth can be defined as the maximum distance from the outer peripheral face to the internal surface of the outer peripheral face. In some embodiments, the actuation member 16, and therefore each engagement surface 20, is smallerin longitudinal length than its respective aperture 24. In other embodiments, the actuation member 16, and therefore each engagement surface, is larger in longitudinal length than each aperture 24. In still other embodiments, the actuation member 16, and therefore each engagement surface 20, is the same longitudinal length as each aperture 24.

[0072] Referring to Fig. 6, each expansion member 26 is configured to be positioned in radial alignment with one engagement surface 20 and one aperture 24. In some embodiments, each expansion member 26 is sized to be smaller in longitudinal length, and in width, than the radially arranged aperture 24 with which it is configured to be positioned in radial alignment. In other embodiments, each expansion member 26 is sized to be the same longitudinal length, and width, as the radially arranged aperture 24 with which it is configured to be positioned in radial alignment. In some embodiments, each expansion member 26 consists of at least a portion of the material excised from the outer peripheral face of the elongate body 2 to generate the radially arranged aperture 24 with which the expansion member 26 is configured to be positioned in radial alignment. In other embodiments, each expansion member 26 does not consist of at least a portion of the material excised from the outer peripheral face of the elongate body 2 to generate the radially arranged aperture 24 with which the expansion member 26 is configured to be positioned in radial alignment. It is also envisaged that, in some embodiments, a larger number of engagement surfaces 20 and apertures 24 are provided than the number of expansion members 26, allowing the user to include more or fewer expansion members 26 as required by a particular task. It is considered that a minimum of three expansion members is required for the shape, size and configuration illustrated in Fig. 1 to stabilise the bolt from movement in all three axes. However, it will be appreciated that more or fewer expansion members may be needed depending on changes to their shape, size and configuration.

[0073] In some embodiments, one or more flexible securing features 28 are configured to be circumferentially positioned around the outer peripheral face of the elongate body 2. In use, the one or more flexible securing features 28 secure the expansion member 26 or plurality of expansion members 26 in position, such that each of the expansion member(s) 26 is / are secured on an outward-facing side (e.g., the bracing surface 30) by the one or more open rings,on the opposite inward-facing side (e.g., the resting surface) by the engagement surface 20 of the actuation member 16, and on the remaining sides by walls of the aperture 24 formed by the depth of the outer peripheral face of the elongate body 2. In some embodiments, including those in Figs. 1 and 6-8, the one or more flexible securing features 28 are one or more open rings. The one or more open rings may comprise any number of open rings (e.g., one, two, three, four, five, six, seven, eight, nine, ten or more). In some embodiments, each of the one or more open rings is shaped as an incomplete ring. In some embodiments, each of the one or more open rings is shaped as a complete ring formed by overlapping rings ( / .e., like an attaching loop on a standard keyring). In some embodiments, one or more of the one or more rings are shaped as an incomplete ring, and one or more of the one or more rings are shaped as a complete ring formed by overlapping rings. The one or more open rings are flexible to allow expansion and contraction of the ring as the expansion members 26 move in the radial direction. In some embodiments the one or more open rings consist of metal or a metal alloy (in some embodiments this requires the metal or a metal alloy to be sufficiently thin to be flexible, and the thinness will be determined by the metal or metal alloy used), but other flexible materials are also envisaged, such as a polymerwith a plastic memory, such as PVC. In some embodiments, the one or more flexible securing features 28 may comprise alternative securing features, in addition to or as an alternative to the one or more open rings. Non-limiting examples of other securing features may be a sheath or a wrap that covers a larger area of the outer peripheral face of the elongate body 2 than the open ring(s) of other embodiments. In some embodiments, securing features 28 may consist of metal or a metal alloy, but other flexible materials are also envisaged such as a polymerwith a plastic memory, such as PVC.

[0074] With reference to Figs. 7 and 8, the adjustable positioning of each expansion member 26 of the releasable expansion bolt 1 will now be described by way of example.

[0075] In some embodiments, including those in Figs. 7-8, each expansion member 26 has a three-dimensional triangularshape ( / .e., a triangle having a depth dimension). As shown in Fig.7, in a first position, one surface (hereinafter referred to as the “resting surface") of the three- dimensional triangular shape of each expansion member 26 is configured to rest against atleast a portion of the engagement surface 20 of the actuation member 16 with which the expansion member 26 is in radial alignment. In this position, the side of the three-dimensional triangle that adjoins the resting surface at the distal end of the expansion member 26 (hereinafter referred to as the “bracing surface" 30) is configured to be parallel to the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned. It will be appreciated that it is not necessary for the bracing surface 30 of the expansion member 26 to be precisely parallel to the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned for the invention to function correctly. Further, it is not necessary for the bracing surface 30 of the expansion member 26 to be precisely level with the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned for the invention to function correctly when the expansion member 26 is displaced inwardly along the displacement axis; rather the bracing surface 30 can be recessed within the longitudinal aperture 24, or it can protrude from the aperture 24. At the proximal end of the expansion member 26, the bracing surface 30 and the resting surface are connected by a third, shorter surface that completes the triangle.

[0076] In some embodiments, each expansion member 26 is shaped as a three-dimensional quadrilateral, wherein the bracing surface 30 and the resting surface are connected at both the distal end and the proximal end by a connecting surface. The connecting surface at the distal end of the expansion member 26 may be shorter than the connecting surface at the proximal end of the expansion member 26. Alternatively, the connecting surface at the distal end of the expansion member 26 may be longer than the connecting surface at the proximal end of the expansion member 26. Alternatively, the connecting surface at the distal end of the expansion member 26 may the same length as the connecting surface at the proximal end of the expansion member 26. In any of these embodiments, wherein the expansion member 26 is a three-dimensional quadrilateral, the three-dimensional quadrilateral may be a three- dimensional parallelogram or a three-dimensional trapezoid, or a cube or cuboid. In embodiments wherein the expansion member 26 is a three-dimensional quadrilateral, theexpansion member 26 may have a maximum depth that is the same depth as the aperture 24 with which it is configured to be positioned in radial alignment; alternatively, the expansion member 26 may have a maximum depth that is smaller or larger than the depth of the aperture 24 with which it is configured to be positioned in radial alignment. It will be appreciated that, in embodiments with a three-dimensional quadrilateral expansion member 26, the “bracing surface 30" of the expansion member 26 is configured to be parallel to the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned. It will be appreciated that it is not necessary for the bracing surface 30 of the expansion member 26 to be precisely parallel to the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned for the invention to function correctly. Further, it is not necessary for the bracing surface 30 of the expansion member 26 to be precisely level with the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned forthe invention to function correctly; ratherthe bracing surface 30 can be recessed within the aperture 24, or it can protrude from the aperture 24. Embodiments wherein the expansion member 26 is a three-dimensional quadrilateral are most advantageously embodiments wherein the walls abutting the engagement surface 20 of the actuation member 16 are quadrilateral in shape, such that, when the expansion member 26 is displaced inwardly, the bracing surface 30 of the expansion member 26 does not protrude from the aperture 24 with which it is radially aligned. However, an expansion member 26 that is a three-dimensional quadrilateral can be aligned with an engagement surface 20 of the actuation member 16 wherein the walls abutting the engagement surface 20 of the actuation member 16 are triangular in shape. Similarly, an expansion member 26 that is a three-dimensional triangle can be aligned with an engagement surface 20 of the actuation member 16 wherein the walls abutting the engagement surface 20 of the actuation member 16 are quadrilateral in shape.

[0077] In use, when each expansion member 26 is in a first position, when fully inwardly displaced (as depicted in the embodiment in Fig. 7), the user engages the actuation member16. In some embodiments, this is done by engaging the head portion 6 of the threaded rod 10with a driver. The driver is turned, usually in a clockwise direction, which causes the threaded rod 10 to engage the internal threading of the receiving bore hole 18 of the actuation member 16. Each expansion member 26 positioned against an engagement surface 20 of the actuation member 16 prevents the actuation member 16 from moving around the longitudinal axis (although additional features for constraining rotation around the longitudinal axis, as disclosed elsewhere in this specification, may also or instead be employed). As the threaded rod 10 engages the internal thread of the receiving bore hole 18 of the actuation member 16, the threaded rod 10 is pulled towards the shoulder portion 14 of the elongate body 2 (where present) until its further distal movement is prevented by the shoulder portion 14. At this stage, further engagement of the threaded rod 10 with the internal thread of the receiving bore hole 18 of the actuation member 16 causes the actuation member 16 to move along the threaded rod 10 in a proximal direction.

[0078] The movement of the actuation member 16 in the proximal direction causes each engagement surface 20 of the actuation member 16 to move proximally relative to the expansion member 26 with which it is radially aligned. In some embodiments, the engagement surface 20 is inclined relative to the longitudinal axis, being shallower at its distal end than it is at its proximal end and, in the first position, the expansion member 26 aligned with the engagement surface 20 is dimensionally sized such that its bracing surface 30 is parallel (or substantially parallel) to the outer peripheral face of the elongate body 2 immediately longitudinally proximal or distal of the aperture 24 with which the engagement surface 20 and the expansion member 26 are configured to be radially aligned. As such, the increasing proximal movement of the actuation member 16 causes an increasingly proximal position on the resting surface of the expansion member 26 to engage with the distal end of the engagement surface 20. It will be understood that any portion(s) of the engagement surface 20 between its distal end and its proximal end may also / alternatively be engaged with the resting surface of the expansion member 26 during this movement.

[0079] With reference to Fig. 8, this increasing engagement of an increasingly proximal position on the resting surface of the expansion member 26 with the distal end of theengagement surface 20 (and / or other points on the engagement surface 20) increasingly displaces the expansion member 26 in a first direction along the displacement axis, and radially away from the longitudinal axis. As each expansion member26 is radially displaced and moved to a second position, the one or more securing features 28 expand. The expansion of the one or more securing features 28 enables each expansion member 26 to be displaced to the second position, whilst still being in position relative to the length and width of the aperture 24 with which it is configured to be radially aligned. The skilled person will appreciate that the one or more securing features 28 also perform this function in any and all transient positions between the first position and the second position along the displacement axis. In the second position, when not engaging with the wall(s) of a cavity, it is not necessary that the bracing surface 30 of each expansion member 26 be substantially parallel to the outer peripheral face of the elongate body 2 immediately distal and / or proximal of the aperture 24 with which the expansion member 26 is configured to be radially aligned. However, substantially parallel positioning of the bracing surface 30 is also envisaged in these circumstances. It is advantageous that the bracing surface 30 be positioned in a substantially parallel position when the bracing surface 30 engages with the wall(s) of a cavity in a substrate during installation of the apparatus ( / .e., in situ), as this increases the surface area of the bracing surface 30 engaging the wall(s) of the cavity, thus applying frictional forces over that larger surface area, providing more secure installation. However, non-parallel positioning of the bracing surface 30 in situ also enables the application of frictional forces to the wall(s) of the cavity and the shape of the bracing surface 30 is such that any non-parallel positioning will still provide a larger surface area across which frictional forces can be applied than a pointed engaging member could . It is also envisaged that a non-parallel bracing surface could be brought into an inclination closer to parallel when pushed into contact against the wall(s) of a cavity as pressure is applied to the bracing surface as it engages the wall(s).

[0080] In some embodiments, to reverse the engagement of the actuation member 16 with the threaded rod 10, when each expansion member 26 is in the second position, the user engages the head portion 6 of the threaded rod 10 with a driver. The driver is turned, usually in an anti-clockwise direction, which causes the threaded rod 10 to increasingly disengage theinternal threading of the receiving bore hole 18 of the actuation member 16 (by which it will be understood here and elsewhere in this application that the internal threading of the receiving bore hole 18 of the actuation member 16 remains in engagement with the threaded rod 10, but the point of engagement moves further towards the distal end of the threaded rod 10). Again, each expansion member 26 positioned in contact with its respective engagement surface 20 of the actuation member 16 prevents the actuation member 16 from rotating around the longitudinal axis of the threaded rod 10 (although alternative or additional features for constraining rotation of the actuation member 16, as discussed above, are also envisaged). As the threaded rod 10 disengages the internal thread of the receiving bore 18 of the actuation member 16, the actuation member 16 is caused to move along the threaded rod 10 in a distal direction. At this stage, in embodiments having a shoulder portion 14, further disengagement of the bore hole 18actuation member 16 releases the force(s) securing the head portion 6 of the threaded rod 10 in a position abutting the shoulder portion 14 until the head 6 of the threaded rod 10 can be moved proximally away from the shoulder portion 14.

[0081] The movement of the actuation member 16 in the distal direction causes the distal end of each engagement surface 20 of the actuation member 16 to move distally relative to the expansion member 26 with which it is radially aligned. The increasing distal movement of the actuation member 16 causes an increasingly distal position on the resting surface of the expansion member 26 to engage with the distal end of the engagement surface 20 ( / .e., the engagement surface 20 moves in a longitudinally opposite direction to when the actuation member 16 moves increasingly proximally). It will be understood that any portion(s) of the engagement surface 20 between its distal end and its proximal end may also be engaged with the resting surface of the expansion member 26 during this movement.

[0082] This increasing engagement of an increasingly distal position on the resting surface of the expansion member 26 with the distal end of the engagement surface 20 increases the force(s) applied to the expansion member 26 in a radial direction away from a longitudinal axis ofthe threaded rod 10. In some embodiments, as the force(s) applied to the expansion member26 decrease, the expansion member 26 is displaced in a second direction to the first position.In other embodiments, an impact to the proximal end of the engagement portion 4 of the elongate body 2 or to a proximal end of the head portion 6 of the threaded rod 10 can be used to release any frictional forces between the engagement surface 20 and the expansion member 26 that may have prevented the expansion member 26 from being displaced in the second direction to the first position. A force applied by any impact action (e.g., knocking with a hand, or hitting with a hammer) not forceful enough to bend, deform or otherwise substantially alter the material comprising the engagement portion 4 of the elongate body 2 or threaded rod 10 may be suitable to release friction between the expansion members 26 and the actuation member 16..

[0083] When each expansion member returns to the first position, the one or more securing features 28 contract accordingly to maintain a retaining force on each expansion member 26. The skilled person will appreciate that the one or more securing features 28 also perform this function in any and all transient positions between the second position and the first position.

[0084] When the apparatus is used to secure one or more substrates and / or one or more objects together, the user may insert the releasable expansion bolt 1 into a cavity before use. The cavity may be a through-hole through one or more substrates and / or one or more objects, but the cavity may extend partially through at least one of the one or more substrates and / or one or more objects. The maximum diameter of the elongate body 2 may be the same as the diameter of the cavity. Alternatively, and advantageously, the maximum diameter of the elongate body 2 may be less that the diameter of the cavity, but the maximum diameter of the notional shape described by the expansion member(s) 26 when outwardly displaced along the displacement axis may have a diameter larger than that of the cavity. In this latter case, the apparatus (when the expansion member(s) 26 is / are displaced inwardly) can be non-forcefully inserted into, and positioned within, the cavity before the expansion member(s) 26 is / are displaced outwardly to apply frictional forces to the substrate against which frictional forces are to be applied by the bracing surface 30 of each expansion member 26. The non-forceful insertion allows for convenient and less time-consuming application.

[0085] When in place in the cavity through or within the one or more substrates and / or one or more objects, the expansion member(s) 26 can be outwardly displaced, as described above. The amount of outward displacement of the each expansion member 26 possible will be limited by the dimensions of the hole at the location with which the bracing surface 30 of each expansion member 26 engages. The material(s) from which the one or more substrates and / or one or more objects with which the bracing surface 30 of each expansion member 26 engages will also determine the amount that the surrounding one or more substrates and / or one or more objects are displaced by the radial force(s) of each expansion member 26. Where the surrounding one or more substrates and / or one or more objects consist of solid, resistant materials such as concrete, cement, steel, or masonry, it will be appreciated that little or no displacement will occur. As the user increases the engagement and actuation of the actuation member 16, greater frictional force(s) are applied radially outward to each expansion member 26. As greater frictional force(s) are applied radially outward to each expansion member 26, greater frictional force(s) are applied by each expansion member 26 to the wall(s) of the cavity with which the bracing surface 30expansion member 26is engaged. It is envisaged that only a part of the bracing surface 30 of an expansion member 26 may at first engage the wall(s) of the cavity. As the actuation member 16 is increasingly engaged and actuated, a greater amount of pressure will be applied to each expansion member 26 radially outwardly relative to the longitudinal axis of the bolt 1 , which may increase the proportion of the surface area of the bracing surface 30 of each expansion member 26 that is applied to the wall(s) of the cavity. The greater the proportion of the surface area of the bracing surface 30 that is applied to the wall(s) of the cavity, the greaterthe maximum frictional force(s) that can be applied to the wall(s) of the cavity at the area at which the bracing surface 30 engages the wall(s).

[0086] In some embodiments, the bracing surface 30 of the expansion member 26 is nonsmooth. For example, the non-smooth bracing surface 30 may be grooved, threaded or striated. In embodiments wherein the bracing surface 30 of the expansion member 26 is nonsmooth, the non-smooth variations in the bracing surface 30 generate additional frictional force(s) against the wall(s) of the cavity, in use. The greaterthe frictional force(s) applied to the wall(s) of the cavity, the more securely held the bolt 1 will be, and so the more securely heldtogether the one or more substrates and / or one or more objects will be. This confers structural integrity on the construction.

[0087] It will be appreciated that the bracing surface 30 is suitable for applying pressure and frictional force(s) to the wall(s) of the cavity through / in the one or more substrates and / or one or more objects.

[0088] In some embodiments, one or more of the elongate body 2, the threaded rod 10, the actuation member 16, the expansion member(s) 26, the shoulder portion 14, and the one or more securing features 28 comprise a metal or a metal alloy. Each of these features may comprise the same metal or metal alloy. In some embodiments, the metal alloy is hardened steel. In some embodiments, one or more of the elongate body 2, the threaded rod 10, the actuation member 16, the expansion member(s) 26, the shoulder portion 14, and the one or more securing features 28 may consist of a material selected from steel, carbon steel, zinc- plated steel, copper, zinc, aluminium, brass and bronze. In some embodiments, the expansion members are comprised of a ceramic material.

[0089] Multiple sizes of the bolt 1 are envisaged to accommodate different sized cavities. For example, the first portion of the elongate body 2 may have a maximum diameter selected from 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 7.5 mm, 8 mm, 10 mm, 12 mm, 12.5 mm, 14 mm, 16 mm, 18 mm, 20 mm, 24 mm, 27 mm, 30 mm, 33 mm, 36 mm, 50 mm and 55 mm, or greater. The maximum size of the recess 8 in the head 6 portion of the threaded rod 10 will be smaller than the maximum diameter of the elongate body 2 and it will be sized to fit a hex key with a maximum size selected from, for example, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 5.5 mm, 6 mm, 8 mm, 10 mm, 14 mm, 17 mm and 19 mm.

[0090] The tensile strength of the bolt is such that the operational forces applied to the bolt is limited only by that which can be withstood by the surrounding substrate. This enables the apparatus to remain operational and engaging the engaged substrate(s) / object(s) up until the application of forces that are destructive to the surrounding substrate(s) / object(s) without destroying the apparatus, thus providing longevity and resilience.

[0091] Other aspects, features and advantages will be apparent upon examination of the attached drawings and appended claims.

Claims

CLAIMS1 . A releasable expansion bolt (1) comprising: an elongate body (2) having a longitudinal axis; an internal passageway passing through the elongate body parallel to the longitudinal axis, for receipt of an actuation member (16); an aperture formed (24) in the elongate body; and an expansion member (26) in the aperture and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body, wherein the expansion member is engaged with an engagement surface (20) of the actuation member such that displacement of the actuation member in a first direction displaces the expansion member outwardly to project beyond an outer surface of the elongate body and displacement of the actuation member in a second, opposite direction displaces the expansion member inwardly.

2. The releasable expansion bolt of claim 1 , wherein the outer peripheral face of the elongate body is cylindrical.

3. The releasable expansion bolt of any preceding claim, comprising a plurality of apertures formed in the elongate body in each of which one of a plurality of expansion members is located, each engaged with a respective engagement surface of the actuation member.

4. The releasable expansion bolt of claim 3, wherein the plurality of apertures are equiangularly spaced around the elongate body.

5. The releasable expansion bolt of any of claims 3 and 4, wherein the plurality of apertures comprises two or more apertures; optionally wherein the plurality of apertures comprises three apertures.

6. The releasable expansion bolt of any preceding claim, wherein the actuation member is constrained from rotating about the longitudinal axis.

7. The releasable expansion bolt of any preceding claim, wherein the actuation member comprises an internally threaded bore (18) formed parallel to the longitudinal axis for receipt of a threaded rod (10); optionally wherein the internally threaded bore is positioned in the radial centre of the actuation member.

8. The releasable expansion bolt of claim 7, wherein clockwise rotation of the threaded rod about the longitudinal axis displaces the actuation member in the first direction.

9. The releasable expansion bolt of any of claims 7 and 8, wherein anti-clockwise rotation of the threaded rod about the longitudinal axis displaces the actuation member in the second direction.

10. The releasable expansion bolt of any of claims 1 to 9, wherein each engagement surface of the actuation member comprises a portion that is inclined to the longitudinal axis.

11. The releasable expansion bolt of any of the preceding claims, wherein each aperture is longitudinally elongated, and each expansion member is sized to have width and length dimensions the same as, or smaller than, the width and length dimensions of its respective aperture.

12. The releasable expansion bolt of any of the preceding claims, wherein each expansion member has a resting surface configured to rest against its respective engagement surface of the actuation member, and a bracing surface (30) configured to engage with a substrate surface in use.

13. The releasable expansion bolt of claim 12, wherein the bracing surface is non-smooth.

14. The releasable expansion bolt of claim 13, wherein the non-smooth bracing surface is grooved, threaded, engraved, embossed or patterned.

15. The releasable expansion bolt of any of claims 2 to 14, wherein the outer peripheral face of the elongate body is non-smooth.

16. The releasable expansion bolt of any of claims 2 to 15, wherein the non-smooth outer peripheral face is grooved, threaded, engraved, embossed or patterned.

17. The releasable expansion bolt of any of the preceding claims, further comprising an engagement portion (4) at a proximal end of the elongate body, wherein the engagement portion has an external shape configured to be received by a wrench or a spanner.

18. The releasable expansion bolt of any of the preceding claims, further comprising one or more flexible securing features (28), configured to secure each expansion member in engagement with its respective engagement surface of the actuation member.

19. The releasable expansion bolt of claim 18, wherein the one or more flexible securing features are one or more open rings.

20. The releasable expansion bolt of any of claims 7 to 21 , wherein the threaded rod comprises a head portion (6) configured to receive a driver; optionally wherein the driver is a hex key or a hex key shank.

21. The releasable expansion bolt of claim 20, wherein the head portion is configured to be positioned within the dimensions of the elongate body when the threaded rod is received by the internally threaded bore of the actuation member.

22. The releasable expansion bolt of any of the preceding claims, wherein one or more of the elongate body, the expansion member(s), the actuation member, the threaded rod, and the one or more securing features comprise a metal or a metal alloy; optionally, wherein one or more of the elongate body, the expansion member(s), the actuation member, the threaded rod, and the one or more securing features comprise the same metal or a metal alloy; further optionally, wherein the metal alloy is stainless steel.

23. The releasable expansion bolt of any of the preceding claims, wherein the elongate body has a major diameter of between approximately 20 mm and 55 mm.

24. The releasable expansion bolt of any of the preceding claims, wherein the bolt is configured to releasably and securely engage one or more substrates and / or one or more objects without additional securing means.

25. A kit of parts comprising: an elongate body having a longitudinal axis; an internal passageway passing through the elongate body parallel to the longitudinal axis, for receipt of an actuation member; an aperture formed in the elongate body; and an expansion member in the aperture and constrained to move along a displacement axis inclined to the longitudinal axis of the elongate body, wherein the expansion member is engaged with an engagement surface of the actuation member such that displacement of the actuation member in a first direction displaces the expansion member outwardly to project beyond an outer surface of the elongate body and displacement of the actuation member in a second, opposite direction displaces the expansion member inwardly.

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