GB2578862A

GB2578862A - Composite structural coupler

Info

Publication number: GB2578862A
Application number: GB1803757.2A
Authority: GB
Inventors: George Arthur Croll James
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-03-08
Filing date: 2018-03-08
Publication date: 2020-06-03
Anticipated expiration: 2038-03-08
Also published as: GB2578862B; GB201803757D0

Abstract

A tube coupler comprises at least one tube clamping element comprising: a coupler body 10; a clamping strap 20 integrally attached to the body or a hinge pin 50 that is integral to the strap; a tensioning unit 30 integrally attached at an opposing position on the body to the clamping strap and a tensioning component 40 that biases the clamping strap towards the tensioning unit to grip the tube. The body, clamping strap and tensioning unit are made of a composite material comprising a polymer and reinforcing fibres. The body, clamping strap and tensioning unit are movable from a closed configuration in which the body, clamping strap and tensioning unit provide three sections of a substantially circular ring that can grip a circular tube and an open configuration that enables the circular tube to be inserted into the tube clamping element without significant resistance. The tube couplers may comprise two tube clamping elements or one tube clamping element and a second coupling means which may be for a structure other that a tube.

Description

COMPOSITE STRUCTURAL COUPLER

The present invention relates to detachable structural couplers, in particular detachable structural couplers comprising composite materials, in particular for structures wholly or partially comprising tubes such as those used as scaffold couplers.

Structural couplers that are detachable are used for a number of temporary works activities including the common application as connectors in scaffold structures. They form the means of coupling tubes used in for example tube and fit scaffolding so commonly employed for the construction and repair of buildings and other infrastructure.

Most prior art tube and fit scaffold structures use metallic couplers. However, metallic CO couplers are bulky, heavy to transport and awkward to handle during erection and dismantling. They have a high thermal capacity and a high coefficient of thermal CO conduction, which means handling at high or low ambient temperature can be very uncomfortable. Being sensitive to atmospheric corrosion they require regular and expensive maintenance, and frequent replacement. In some chemically hostile C\J environments, such as certain industrial locations and particularly marine locations, they suffer high rates of corrosion rendering them unfit for purpose, sometimes after quite short periods of service. When attempting to remove badly corroded couplers, on which the threaded nuts and bolts may have become fused through corrosion, scaffold personnel are exposed to often unacceptable health and safety hazards. When steel couplers are used in conjunction with aluminium scaffold tubes, galvanic action can accelerate corrosion of coupler and tube especially at the interfaces between them -similar problems occur when aluminium couplers are used with steel tubes. Furthermore, the bearing stresses with metallic couplers tend to he concentrated rather than being distributed around the scaffold tubes they are coupling, which can cause localized damage to tubes. This is especially the case where the tubes are constructed from softer materials such as aluminium or composites. This tube damage can become an even more significant problem as a result of over-zealous tightening of the couplers. This distorts the couplers to an extent that the bearing surfaces, which may be relatively smooth when new, become damaged, thus presenting highly localized sharp edges. The resulting increases in bearing stress concentration can exacerbate damage to tubes.

GB 2514534 discloses a structural clip for coupling scaffolding tubes comprising a securing strap made of polymeric resin, optionally strengthened with reinforcing fibres, wherein the strap passes only partly around the circumference of a tube and is partially reinforced with ribs, and wherein the end of the strap is not reinforced. The straps are thus intentionally deformable, enabling the clips to be conveniently snapped on and off of a tube. However, this structure also significantly lessens the strength of the clip, reducing the force the coupling can transmit.

CO WO 2013/132255 discloses a coupler made from composite materials, forming a tube clamp comprising two pivoted jaws, which form a securing strap that passes substantially CO 15 completely around the tube when closed. The jaws are hinged around a steel hinge pin, and the jaws are secured closed and tensioned in use using a threaded T-bar and (r) cooperating distribution shoulder, which T-bar is tensioned using a suitably configured C\J nut bearing against the seat of the distribution shoulder of one jaw equilibrated by the cross-arm of the T-bolt bearing against the capture mechanism of the opposing jaw.

The coupler of WO 2013/132255 has a number of disadvantageous features. To take advantage of its corrosion resistance, the composite coupler of WO 2013/132255 requires the use of expensive bespoke stainless steel components such as T-bolts and hinge pins, adding greatly to the cost of producing the couplers. The capture mechanism for the cross-arms of the T-bolts is inconvenient, requiring a design that compromises strength for ease of assembly. This means the capture mechanism is prone to accidental damage when couplers are subject to rough handling.

The couplers of WO 2013/132255 feature a clamping strap that allows the bolt force to be 30 evenly applied around the circumference of the tube. However, the mechanism for -3 -distributing the bolt force laterally into the strap relies upon the development of bending action in the distribution shoulder and the cross-arms of the stainless steel T-bolts. This means there are consequentially high levels of stress concentration in both the stainless steel and composite capture mechanism. As a result, to achieve the lateral distribution of bolt forces the stainless steel and composite components are bulky and therefore expensive. To generate the required bending strength and stiffness, the distribution shoulders protrude a considerable distance from the body of the coupler. This presents a hazard for operators, makes them vulnerable to damage, and restricts the orientations over which one coupler can he abutted intimately against another component such as another coupler.

To increase the total load transfer capacity at a connection, it is useful for the couplers to CO he intimately abutted together at any relative orientation one to the other. This is possible over only a limited range of relative orientations with the couplers of WO 2013/132255.

CO 15 Furthermore, it is not possible to deploy the couplers of WO 2013/132255 in situations where, for example, on a working platform of a scaffold a platform unit is required to be (r) placed flush over the top of the coupler. This is because the distribution shoulder and C\J attachment bolt protrude above the highest point of the strap when attached to a tube.

This means the currently available composite couplers cannot be used to replace putlog couplers conventionally used to attach transoms to the ledgers in tube and fit scaffolds.

The composite structural clip of GB 2514534 solves this problem by being more compact than that of WO 20 13/132255, but as with a steel putlog coupler it is fundamentally incapable of transmitting the forces developed when the transom forms part of a structural bracing system. In these situations, an additional load bearing transom must he attached beneath the ledgers using full load transmitting couplers.

There therefore remains a need for full load-transmitting couplers that could be used in place of standard steel putlog couplers to obviate the need for an additional transom. -4 -

In overcoming this problem, there would be practical advantages if the plan width of the coupler body were to be the same as the tube centre-line to centre-line dimension when two tubes are connected together. This would allow the transom adjacent to the standard to be connected directly to the standard reducing the total load to be transferred by the coupler connecting the ledger to the standard. This was not the case in the composite coupler of WO 2013/132255.

The couplers of WO 2013/132255 are asymmetrical in that they have hinges connecting the clamping strap and the capture mechanism connecting the cross-arms of the T-bolt tensioning unit to the body of the coupler being of different forms. Thus, the coupler cannot he used in either a right or left handed configuration, which is inconvenient. In many situations, it would he useful for couplers to he configured so that the tensioning CO units and clamping straps could he interchangeable. Weight of the body part in prior art composite couplers was reduced by means of ribs emanating out from a cruciform core.

CO 15 These rib arrangements provide a coupler body having a relatively low stiffness and strength for the transmission of moments about the axis normal to the 2 tubes being (r) connected (referred to as cruciform moments in the context of scaffold structures).

C\J Furthermore, as the ribs are on the outer surface of the prior art body part, the openings between the ribs of the coupler are prone to accumulation of moisture and detritus, which can hasten any chemical deterioration of the composite material used for its construction.

While the T-bolts of the coupler of WO 2013/132255 are effective in developing the tension in the coupler straps, they have been found in early forms of composite coupler to he less effective for the transmission of moments about axes normal to or parallel to the axes of either of the 2 tubes being coupled, and for shear forces parallel to the tube axes and therefore normal to the thread of the T-bolts. These loads lead to excessive distortions across the strap tensioning unit, loss of geometric integrity and a lowering of the failure load. -5 -

The present invention aims to provide an improved structural coupler that overcomes or at least ameliorates at least one problem associated with prior art couplers.

Accordingly, the present invention provides a tube coupler having two coupling elements with at least one being a tube clamping element comprising: (i) a body; (ii) a clamping strap, integrally attached to the body or pivotally attached to the body at a hinge pin that is integral to the strap; (iii) a tensioning unit, at an opposing position on the body to the clamping strap, integrally attached to the body or pivotally attached to the body at a hinge pin that is integral to the tensioning unit; and (iv) a tensioning component that biases the clamping strap towards the tensioning unit to grip the tube, wherein for a first clamping form the tube clamping element comprises a body, clamping strap and tensioning unit that are movable to form two configurations selected from: a closed configuration in which the body, clamping strap and tensioning unit provide three sections of a CO substantially continuous circular ring that is capable of gripping a circular tube; and an open configuration that enables the circular tube to be inserted into the clamping element CO 15 without significant resistance, and wherein the clamping element for a second clamping form has either or both the clamping strap and the tensioning unit integrally attached to (r) the body, and wherein the second coupling element comprises either a second tube C\J clamping element or a coupling means suitable for attachment to some other structural component. Furthermore, all components of both coupling elements are made of composite materials comprising a polymer and reinforcing fibres, or alternatively all but the tensioning component are made of composite materials comprising a polymer and reinforcing fibres with just the tensioning component made from metal, preferably stainless steel.

Thus, the tube coupler has a minimum number of metallic components and optionally substantially consists of a polymer. In an embodiment, metallic components are confined to the tensioning component.

Some or all components of the tube coupler may be formed by moulding, for example, injection moulding. -6 -

In embodiments of the invention the tube may be a scaffold tube, and so the tube coupler may be configured for use with one or more scaffolding tube.

The tube coupler of the invention advantageously is resistant to corrosion and provides a structural effective connection of a tube. The tube coupler of the invention does not require expensive, bespoke stainless steel components, and allows easy attachment and detachment of tubes from the coupler.

In embodiments of the invention, the polymer is a polymeric resin. The polymer may be strengthened with reinforcing fibres, such as glass fibres. The reinforcing fibres may be randomly orientated to provide high triaxial strength in each of its component parts.

CO

In embodiments of the invention, the tensioning component is a threaded stud and nut. CO 15 The threaded stud and/or nut may be made of a metallic material. Advantageously, the threaded stud and/or nut may be made of a stainless steel. Alternatively, the threaded stud (r) and/or nut may be made of a composite material. Optionally, the composite material may C\J comprise a polymer, such as a polymeric resin. The polymer may be strengthened with reinforcing fibres, such as glass fibres.

In embodiments of the invention, the threaded stud may have a head, forming a bolt, and the head of the bolt or the nut is either bearing on, embedded in or slotted into the tensioning unit with the other end anchored onto the bearing plate of the clamping strap.

In embodiments of the invention, one or more of the body, clamping strap and tensioning unit comprise circumferential reinforcing ribs. The ribs may be external and/or internal.

The circumferential ribs on the clamping strap and/or the tensioning unit may interlock with the ribs on the body to prevent movement along the axis of the clamping strap hinge pin and/or the tensioning unit hinge pin. -7 -

In embodiments of the invention, one or more of the hinge pins are rotatable in hinge bearings formed by the ribs on the body that are open-sided and enable the one or more hinge pins to be removed from the hinge bearings by movement in the direction of the hinge axis, thereby rendering the clamping strap and/or the tensioning unit removable from the body.

In a particular embodiment, the hinge pins are connected to the clamping strap and the tensioning unit by parallel integrally-formed pin tension plates normal to the hinge pin axis and separated by pin tension plate slots, and wherein the parallel pin tension plates are aligned with internal and/or external ribs on the clamping strap and the tensioning unit.

CO

In embodiments of the invention, an end pin tension plate of the clamping strap and the CO 15 tensioning unit is larger relative to the opening to the side of the hinge bearing seats.

Thus, it requires considerable force for the hinge pin to be pushed in the direction of its axis into the hinge bearing and consequently preventing accidental removal of the C\J clamping straps or the tensioning units in use.

In embodiments of the invention, the hinge pins of the clamping strap and the tensioning unit are substantially the same size and shape, and the hinge bearings on the body are substantially the same size and shape, thereby enabling the clamping strap and the tensioning unit to he interchangeable on the body.

In alternative embodiments of the invention, the clamping strap and/or the tensioning unit is integral with the body.

In an embodiment, the tensioning component does not protrude above the point of the clamping strap or tensioning unit furthest from the body. -8 -

In embodiments of the invention, the tube coupler comprises two clamping elements mounted body to body and configured to clamp two tubes together in parallel or at an angle.

Thus, the tube coupler may be configured to couple two tubes such as scaffold tubes.

The tube coupler of the invention may he a fixed parallel scaffold connector. For example, the detachable coupler is a fixed lap joint scaffold connector.

The tube coupler of the invention may he a fixed 90' scaffold connector. For example, the detachable coupler is a fixed right angle scaffold connector.

CO CO 15 (r) C\J

The height of the coupler body may be configured to ensure the perpendicular distance between the two axes of the connected tubes is equal to the width of the coupler body, clamping strap and tensioning unit of the coupler.

In embodiments of the invention, the coupler body may be formed as a single component, in which case the two coupling elements share this single coupler body.

Alternatively, the coupler body may be formed as two separate parts, in which case the two separate parts of the coupler body may be identical in form. The two parts of the coupler body may be rigidly connected one to the other. Suitably the rigidly connected parts of the coupler body may be formed as an integral component. In embodiments of the invention, the integrally connected two parts of the coupler body may be formed by an injection moulding process.

Optionally, the coupler body is comprised entirely of a polymeric based resin material with reinforcing fibres randomly orientated to provide it with high strength. For example, the coupler body is comprised almost entirely of a polymeric based resin material with reinforcing fibres randomly orientated to provide it with high strength. -9 -

In embodiments of the invention, the tube coupler may comprise a clamping element and a second coupling means for fixing the tube coupler to another structure, wherein the second coupling means is selected from a range of forms including: a fixing plate; a laterally-facing G-clamp; and a tube clamp comprising a close-fitting ring and a radially-mounted compression stud, and wherein the clamping element is configured to clamp the tube and the other structure together in parallel or at an angle.

In a particular embodiment, the two clamping elements, or the clamping element and means for fixing, are mounted substantially perpendicularly, thus clamping two tubes, or the tube and another structural component, at 90° with respect to each other.

CO in embodiments of the invention, the tube coupler comprises a clamping element, and a captive threaded stud, bolt or nut. CO 15

The tube coupler may be pigmented to produce colours chosen to suite a particular client or to encode a particular form of use. C\J

In embodiments of the invention, the injection moulds for the two parts of the coupler body may be configured to allow the integrally connected two parts of the coupler body to he attached to tubes having their axes at right angles. in embodiments of the invention, the integrally connected two parts of the coupler body form part of a fixed right angle (or 90°) scaffold connector.

in embodiments of the invention, the injection moulds for the two parts of the coupler body may be configured to allow the integrally connected two parts of the coupler body to be attached to tubes having their axes parallel to each other. In embodiments of the invention, the integrally connected two parts of the coupler body form part of a fixed parallel or lap joint scaffold connector.

-10 -In embodiments of the invention, the two parts of the coupler body may be flexibly connected one to the other through a rotational hinge with axis normal to the axes of the tubes being attached. In embodiments of the invention, the coupler body forms part of a variable angle (or swivel) scaffold connector.

In embodiments of the invention, the two separate parts of the coupler body are each provided with a pair of integral hinge bearings comprised of a polymeric based resin material with reinforcing fibres randomly orientated to provide them with sufficient strength. In embodiments of the invention, the pairs of integral hinge hearings on the two separate parts of the coupler body are aligned so that the axes of the hinge hearings are parallel with the axis of the tube on that separate part of the coupler body.

CO In embodiments of the invention, the pairs of integral hinge bearings on the two separate parts of the coupler body allow the integral hinge pins of the clamping strap and the CO 15 tensioning unit to rotate freely about the axes of the hinge bearings. In embodiments of the invention, the integral hinge bearings of the coupler body allow the forces from the (r) clamping strap and tensioning unit to be transmitted into the coupler body.

In embodiments of the invention, the two parts of the coupler body each comprise a pair of integral hinge bearing seats adapted to cup part of the hinge pin rods of the clamping strap or the tensioning unit. In embodiments of the invention, the hearing seats comprise an arcuate surface. In embodiments of the invention, the hinge bearing seats comprise a concave surface adapted to abut the convex surface of the hinge pin rods of the clamping strap and tensioning unit.

In embodiments of the invention, when the two parts of the coupler body are rigidly connected the integral coupler body is provided with two pairs of integral hinge bearings comprised of a polymeric based resin material with reinforcing fibres randomly orientated to provide them with sufficient strength.

In embodiments of the invention, the two pairs of integral hinge bearings on the coupler body may be positioned so that those on one face are at 90° to those on the other face. In embodiments of the invention, when the two pairs of integral hinge bearings on the coupler body are positioned to be at 90° one to the other the integral coupler body will form part of a fixed 900 scaffold coupler.

In embodiments of the invention, the two pairs of integral hinge bearings on the coupler body may be positioned so that those on one face are aligned with those on the other face. In embodiments of the invention, when the two pairs of integral hinge bearings on the coupler body are positioned to he aligned one to the other the integral coupler body will form part of a fixed parallel scaffold coupler.

CO CO 15 (r) C\J

in embodiments of the invention, the two pairs of integral hinge bearings of the coupler body are identical and allow the interchangeable fitting of the clamping strap and tensioning unit.

In embodiments of the invention, each of the hinge bearings incorporates an opening as part of the capture mechanism. In embodiments of the invention, the hinge bearing openings to the side of the arcuate hinge bearings allow the length-wise fitting of the hinge pins of the clamping straps and tensioning units. In embodiments of the invention, the hinge bearing openings are configured to allow the hinge pins and tension plates of the clamping straps and tensioning units to be lined up with the openings of the hinge bearings and longitudinally pushed into place. in embodiments of the invention, the hinge bearing openings are configured to allow the hinge pins of the clamping straps and tensioning units when aligned to he pushed into place in the direction of the axis of the hinge pins. In embodiments of the invention, the hinge bearing openings and hinge bearing shear plates, and the pin and pin tension plates are sufficiently close in tolerance that a moderate lateral force is required for the clamping straps and tensioning units to be pushed into place.

-12 -In embodiments of the invention, the hinge pins are integrally connected to the clamping straps and tensioning units by means of pin tension plates. In embodiments of the invention, the pin tension plates are shaped to fit closely into the opening to the side of the hinge bearings of the coupler body. In embodiments of the invention, the shaped pin tension plates allow the hinge pins to be pushed into the opening of the hinge bearings of the coupler body when the clamping straps or tensioning unit are orientated in one specific direction.

Advantageously, the close dimensional tolerance between the shaped pin tension plates and the hinge bearing openings mean that a small force will he required to push the hinge pin into the opening of the hinge hearings of the coupler body when the clamping straps or tensioning unit are orientated in one specific direction. Moreover, the small force CO required to push the hinge pin into the hinge bearing is sufficient to prevent the clamping strap and tensioning unit from being accidentally dislodged even when the clamping CO 15 straps and tensioning unit are improbably orientated in the one specific direction required for fitting.

C\J In embodiments of the invention, when the clamping straps and tensioning units are orientated in any direction other than the one required for fitting, the hinge pins are constrained from movement in the direction of the hinge pin axis. In embodiments of the invention, when the clamping straps and tensioning unit are orientated in any direction other than the one required for fitting, the hinge bearing shear plates act as a capture mechanism preventing any movement of the hinge along its axis. In embodiments of the invention, the pin tension plates and the hinge hearing shear plates together provide a capture mechanism. In embodiments of the invention, the capture mechanism allows free rotation of the clamping strap and the tensioning unit about the hinge axis but prevents the hinge pins from being accidentally dislodged from the hinge bearing of the coupler body in the direction of the hinge axis.

-13 -In embodiments of the invention, to provide additional security against the clamping straps and tensioning units from being accidentally dislodged from the coupler body in the direction of the pin axis, one of the end pin tension plates of both the clamping strap and tensioning unit are formed with a deeper section providing a depth greater than the opening of the hinge bearing shear plate of the coupler body. In embodiments of the invention, this over size of the end pin tension plates requires a substantial longitudinal force for it to he pushed into place within the hinge hearing of the coupler body. In embodiments of the invention, once fitted the hinge pin would be securely held in place within the hinge bearing of the coupler body. in embodiments of the invention, the deepened end pin tension plates of the clamping strap and tensioning unit act as a locking mechanism once fitted, preventing any movement of the hinge along its axis.

CO In embodiments of the invention, to provide an alternative form of additional security against clamping straps and tensioning units from being accidentally dislodged from the CO 15 coupler body in the direction of the pin axis, end caps may be fitted to both ends of the hinge pins. In embodiments of the invention, the pin cap at a first end of the clamping (r) strap and tensioning unit may be cast integrally into the hinge pin. In embodiments of the C\J invention, the pin end cap at the opposite, second end may be fitted after the clamping straps and tensioning units have been fitted into the bearing seats of the coupler body.

In embodiments of the invention, the coupler body for the coupling element is connected to the clamping straps and tensioning unit with an inter-meshing hinge arrangement that prevents the clamping straps and tensioning unit from falling out once placed within the hinge bearing seats. In embodiments of the invention, the minimum width of the opening to the side of the hinge bearing is less than the diameter of the hinge pin. in embodiments of the invention, once in place within the hinge bearing of the coupler body the hinge pins of the clamping straps and tensioning units will be prevented from being dislodged from the coupler body in a direction normal to the axis of the integral hinge pins -14 -In embodiments of the invention, a coupler body having two coupling elements has two pairs of integral hinge bearing seats and hinge bearing shear plates, comprised of a polymeric based material with reinforcing fibres randomly orientated to provide adequate strength, within which the clamping straps and the tensioning units are attached. The coupler body hinge bearing shear plates, allow the tension force from the clamping straps and tensioning units to be transferred into the coupler body.

In embodiments of the invention, the entrained corners where the hinge bearing shear plates are integrally joined to the coupler body are provided with corners having a suitable radius. In embodiments of the invention, the entrained corners where the arcuate ribs are integrally joined to the coupler body are provided with corners having a suitable radius. Accordingly, the radial corners at the abutments of the hinge pin shear plates will CO reduce stress concentrations in use.

CO 15 In embodiments of the invention, the two hinge bearing seats of the coupling element are identical. In embodiments of the invention, the two hinge bearing seats of the coupling (r) element being identical allow interchangeable attachment of either the clamping strap or C\J the tensioning unit.

In embodiments of the invention having two coupling elements, the pairs of coupler body hinge bearing seats allow the attachment of either the clamping strap or tensioning unit, enabling the couplers to be assembled as either left or right hand couplers. In embodiments of the invention, the coupler body hinge hearing seats, allow interchangeable attachment of either the clamping strap or tensioning unit, enabling the couplers to be assembled as couplers having a wide variety of configurations.

In embodiments of the invention, the coupling element has arcuate tube bearing surfaces on the coupler body, clamping strap and tensioning unit adapted to conform to the outer face of the tube to which they are fitted. In embodiments of the invention, the coupling element comprises an arcuate face for engaging a tube in use.

-15 -In embodiments of the invention, the arcuate face of the coupler body for engaging a tube in use comprises a series of arcuate ribs forming a discontinuous bearing surface. In embodiments of the invention, the coupler body of the coupling element has parallel slots between the arcuate ribs. In embodiments of the invention, the arcuate bearing surfaces of the ribs lie on a surface of circular cylindrical foim.

In embodiments of the invention, parallel slots between the arcuate ribs of one part of the coupler body penetrate to the surface of the diaphragm plate separating the two integral coupling elements of the coupler body. In embodiments of the invention, the upper surface of the diaphragm plate forms the lower edge of the arcuate ribs of the coupler body. As such, the parallel slots between the arcuate ribs of the coupler body allow the CO volume of advanced composite material to be kept to the minimum consistent with providing adequate strength and stiffness. CO I5

In embodiments of the invention, a transverse rib runs centrally between the arcuate ribs of the coupler body. In embodiments of the invention, the gate for the moulding process C\J is located at the mid-length of the transverse rib. As such, the transverse rib connecting the arcuate ribs provides a more effective flow channel for dispersing the polymeric based resin material with reinforcing fibres during the injection moulding process.

In embodiments of the invention, the parallel slots between the arcuate ribs of the coupler body when in use are fully enclosed by the outer surface of the attached tube. As such, the fully enclosed parallel slots between the arcuate ribs are unlikely to accumulate detritus in use.

In embodiments of the invention, the tube bearing surfaces for the first and second coupling elements comprise a concave arc of a circular cylinder, allowing uniform pressures to be transferred into the tubes to which the coupler is connected.

CO CO 15 (r) C\J

In embodiments of the invention, the first coupling element has arcuate bearing surfaces to provide the connection to the first tube. In embodiments of the invention, the second coupling element has arcuate bearing surfaces to provide the connection to the second tube. In embodiments of the invention, the arcuate ribs of the first coupling element are separated from the arcuate ribs of the second coupling element by the diaphragm plate.

In embodiments of the invention, the parallel arcuate ribs of the coupler body are within the walls of a thin walled containment box and are aligned with the hinge bearing shear plates. in embodiments of the invention, two of the walls of the containment box comprise the flanges for the arcuate web ribs enhancing the bending strength and stiffness of the body. In embodiments of the invention, the other two walls of the containment box comprise arcuate ribs identical to the other arcuate ribs. in embodiments of the invention, the arcuate ribs have the same thickness as the hinge bearing shear plates. As such, the hinge bearing shear plates and arcuate ribs of the body are aligned to allow continuous transfer of stress when the coupler is subject to external force and moment loading.

In embodiments of the invention, the two coupling elements of the coupler body each have a square thin walled box surrounding the parallel slots lying between arcuate ribs. In embodiments of the invention, the square peripheral box forms an outer shell of the coupler body. As such, the combination of ribs, diaphragm lower plate and the square containing box comprise the required torsional and bending strength and stiffness of the coupler body.

In embodiments of the invention, the coupler body has the two arcuate tube bearing surfaces of the two coupling elements fixed in position so that when tubes are in place they are at right angles one to the other. As such, the two circular cylindrical tube bearing surfaces of the coupler body are integrally connected together at the diaphragm plate, so that the tube axes are fixed at 900 one to the other.

In embodiments of the invention, the coupler body has the two arcuate tube bearing surfaces of the two coupling elements fixed in position so that when tubes are in place they are parallel one to the other. As such, the two circular cylindrical tube bearing surfaces of the coupler body are integrally connected together at the diaphragm plate, so that the tube axes are fixed parallel one to the other.

In embodiments of the invention, the two circular tube hearing surfaces of the coupler body are formed as two identical parts. In embodiments of the invention, the two parts of the coupler body are connected together through a central pin, allowing one part to be freely rotated relative to the other part about a pin having axis normal to the planar diaphragm plate interfaces. In embodiments of the invention, the two parts of the coupler body may he rotated freely about the central pin to provide a variable angle between the CO two coupled tubes. As such the coupler may he a swivel scaffold coupler.

CO 15 In embodiments of the invention, the first coupling form comprises a rotating clamping strap. In embodiments of the invention, the first coupling form comprises a rotating CO tensioning unit.

In embodiments of the invention, the clamping strap and tensioning unit for the first coupling form for use with circular tubes are each attached to the coupler body through integrally cast hinge pins. In embodiments of the invention, the integrally cast hinge pins are connected through pin tension plates to one end of the clamping strap and to one end of the tensioning unit. In embodiments of the invention, the pin tension plates are integrally cast at one end of respectively the clamping strap and tensioning unit.

In embodiments of the invention, the entrained corners where the pin tension plates are integrally joined to the hinge pin of the clamping strap and tensioning unit are provided with corners having a suitable radius. In embodiments of the invention, the entrained corners where the pin tension plates are integrally joined to the clamping strap and tensioning unit are provided with corners having suitable radius. Accordingly, the radial corners at both ends of the pin tension plates will reduce stress concentrations in use.

In embodiments of the invention, the integrally cast hinge pins of the clamping strap and tensioning unit are captured in hinge bearings cast integrally within the coupler body. In embodiments of the invention, the hinge pin capture details embodied within the coupler body are identical for the clamping strap and tensioning unit.

In embodiments of the invention, the clamping strap and tensioning unit have integral hinge pins that allow flexible attachment to the coupler body. As such, the clamping strap and tensioning unit can be removed and replaced at any time. As such, the capture mechanism makes it difficult for the clamping strap and tensioning unit to be accidentally CO dislodged when in use.

CO 15 In embodiments of the invention, the clamping strap and tensioning unit have integrally cast hinge pins comprised of a polymeric based resin material with reinforcing fibres (r) randomly orientated to provide them with sufficient strength.

In embodiments of the invention, the clamping strap for the first coupling form is over its length sufficiently thin to allow the strap load to be applied uniformly to the tube to which it is attached. In embodiments of the invention, the clamping strap is over its length sufficiently thin that when tensioned the dominant stress is uniform across the strap thickness. In embodiments of the invention, the clamping strap has the loads transmitted from the tensioning component with sufficient uniformity that when tensioned the dominant stress is uniform across the strap width. As such the clamping strap when tensioned avoids the development of bending stress.

In embodiments of the invention, the clamping strap is provided at its other end with an integrally cast bearing seat for the tensioning component. In embodiments of the invention, the integrally cast bearing seat allows the tension force to be transferred from -19 -the tensioning component to the clamping strap. In embodiments of the invention, the bearing seat is comprised of a polymeric based material with reinforcing fibres randomly orientated to provide sufficient strength.

In embodiments of the invention, the bearing seat of the clamping strap is integrally cast with internal and external ring and transverse ribs. In embodiments of the invention, the internal and external ribs of the clamping strap are separated by a thin distribution shell. As such the ring ribs, transverse ribs and distribution shell enable the localized force from the tensioning component to he distributed evenly across the width of the clamping strap.

In embodiments of the invention, the tensioning unit for the first coupling form is provided at its other end with an anchor block for the tensioning component. The anchor CO block provides the means for distributing the localized force from the tensioning component into the tensioning unit. The anchor block of the tensioning unit provides the CO 15 means for distributing the localized force from the tensioning component uniformly across the width of the hinge connection to the coupler body. (r) C\J In embodiments of the invention, the anchor block of the tensioning unit is integrally cast with internal and external ring and transverse ribs. In embodiments of the invention, the internal and external ribs of the anchor block are separated by a thin distribution shell. As such the ring ribs, transverse ribs and distribution shell enable the localized force from the tensioning component to be distributed evenly across the width of the tensioning unit.

In embodiments of the invention, the tensioning component allows the transmission of a tension force between the anchor block of the tension unit to the bearing plate of the clamping strap. In embodiments of the invention, the tensioning component comprises a high strength stud and nut or bolt and nut to produce the required tension force between the tensioning unit and the clamping strap.

-20 -In embodiments of the invention, the tensioning component is a composite stud integrally moulded within the anchor block of the tensioning unit. In embodiments of the invention, the tensioning component is a metallic stud or bolt cast within the anchor block of the tensioning unit. In embodiments of the invention, the tensioning component is a metallic bolt having its head cast within the anchor block of the tensioning unit. As such the nut of the stud or bolt bears upon bearing plate of the clamping strap.

In embodiments of the invention, the tensioning component comprises a nut integrally moulded into the anchor block of the tension unit. In embodiments of the invention, the tensioning component comprises a metallic nut cast within the anchor block. In embodiments of the invention, the tensioning component comprises a metallic nut slotted into a preformed aperture within the anchor block. As such, the bolt head will bear upon CO the bearing plate of the clamping strap CO 15 In embodiments of the invention, the nut of the stud or bolt of the tensioning component bearing on the bearing plate of the tension strap will comprise an integral washer. In (r) embodiments of the invention, the head of the bolt of the tensioning component bearing C\J on the bearing plate of the tension strap will comprise an integral washer. As such, the force from the tension component will be more evenly distributed over the bearing plate 20 of the tensioning component.

In embodiments of the invention, the tensioning component is of a composite, preferably composite. In embodiments of the invention, the tensioning component is of a fibre reinforced polymeric composite. In embodiments of the invention, the tensioning component is of a glass fibre reinforced polymeric composite. In embodiments of the invention, the tensioning component is of a carbon fibre reinforced polymeric composite. In embodiments of the invention, the fibre reinforced polymeric composite of the tensioning component is of higher strength than the fibre reinforced polymer used for the clamping strap or tensioning unit. In embodiments of the invention, the tensioning component and the tensioning unit are of a carbon fibre reinforced polymeric composite.

In embodiments of the invention, the tensioning component is metallic. In embodiments of the invention, the tensioning component is comprised of mild steel. In embodiments of the invention, the tensioning component is comprised of stainless steel. In embodiments of the invention, the tensioning component is comprised of marine Grade 316 stainless steel.

In embodiments of the invention, there is provided a fibre reinforced polymeric detachable structural coupler for which the coupling element comprises a female thread integrally formed within the anchor block of the tensioning unit. In embodiments of the invention, there is provided a bolt formed from the same reinforced polymeric material as the other components of the detachable structural coupler. In embodiments of the CO invention, the threaded bolt and tensioning unit are formed of a reinforced polymeric material that is stronger than the other components of the detachable structural coupler. In CO 15 embodiments of the invention, there is provided a bolt formed from the same higher- ° strength reinforced polymeric material as the female thread moulded integrally with the CO tensioning unit.

In embodiments of the invention, the clamping strap has shear keys incorporated either side of the bearing block. In embodiments of the invention, the tensioning unit has matching shear keyways incorporated either side of the anchor block. Thus, as the tension component is tightened, the shear keys of the clamping strap will interlock with the keyways of the tensioning unit. As such, the interlocking shear keys may prevent relative tangential distortion between the ends of the clamping strap and the tensioning unit when the coupler transmits subsequent load. Accordingly, relative tangential deformation between the clamping strap and tensioning unit are prevented. Accordingly, damaging shear force and deformation will be avoided in the otherwise vulnerable tensioning component.

-22 -In embodiments of the invention, the clamping strap has shear keyways incorporated either side of the bearing plate. In embodiments of the invention, the tensioning unit has matching shear keys incorporated either side of the anchor block. Thus, as the tension component is tightened, the shear keys of the tensioning unit will interlock with the keyways of the clamping strap. As such, the interlocking shear keys may further prevent relative tangential distortion between the ends of the clamping strap and the tensioning unit when the coupler transmits subsequent load. Accordingly, relative tangential deformation between the clamping strap and tensioning unit are further prevented. Accordingly, damaging shear force and deformation will be further avoided in the otherwise vulnerable tensioning component.

In embodiments of the invention, the tube coupler is a scaffold tube coupler.

CO

In embodiments of the invention, the clamping straps of the first coupling form have a CO 15 wall thickness T1 of between 1 and 5mm, such as between 2 and 4mm, for example 3min C\J In embodiments of the invention, circular clamping straps, tensioning units and coupler body have circular arcuate bearing surfaces of radius RI to provide close tolerance to and allow the development of sufficient bearing pressure on the outer surface of a circular tube having an outer diameter Dl of between 30 and 100mm, in embodiments of the invention between 40 and 60mm, for example 48.3mm; radius R1 chosen to be half Dl.

In embodiments of the invention, clamping straps have a wall width W 1 of between 30 25 and 100mm, in embodiments of the invention between 40 and 80mm, for example 62.3mm.

In embodiments of the invention, the integral hinge pins of the clamping straps and tensioning unit have a diameter D2 of between 4 and 12mm, in embodiments of the 30 invention between 6 and 9mm, for example 8mm; radius R2 chosen to be half D2.

-23 -In embodiments of the invention, the detachable structural coupler comprises one or more polymer. In embodiments of the invention, the coupler comprises a polymer resin. In embodiments of the invention, the coupler comprises a polymeric matrix. In embodiments of the invention, the coupler comprises one or more polymer reinforced with fibres. In embodiments of the invention, the coupler comprises one or more polymer binding fibres together.

In embodiments of the invention, the coupler comprises thermoplastic polyester polymer.

In embodiments of the invention, the coupler comprises thermoplastic polyester resin. In embodiments of the invention, the coupler comprises thermoplastic polyamide polymer. In embodiments of the invention, the coupler comprises thermoplastic polyamide resin. In CO embodiments of the invention, the coupler comprises thermoplastic vinylester polymer.

In embodiments of the invention, the coupler comprises thermoplastic vinylester resin. In CO 15 embodiments of the invention, the coupler comprises thermoplastic polyurethane polymer. In embodiments of the invention, the coupler comprises thermoplastic (r) polyurethane resin.

In embodiments of the invention, the coupler has reinforcing fibres comprising one or more selected from the group: glass fibres; aramid fibres; boron fibres; natural fibres; and carbon fibres. For example, the glass fibres may be e-glass and/or s-glass fibres.

In embodiments of the invention, the detachable structural coupler is comprised of components formed from a fibre reinforced thermoplastic polymeric (frp) composite. In embodiments of the invention, the coupler comprises a single polymeric matrix bonding all the fibres. For example, the coupler may comprise a single polymer bonding all the fibres.

In embodiments of the invention, the coupler comprises between 0 and 80% fibre by 30 volume. In embodiments of the invention, the coupler comprises between 20 and 70%

CO CO 15 (r) C\J

-24 -fibre by volume. For example, the detachable structural coupler may comprise around 50% by volume of fibre.

In embodiments of the invention, the coupler comprises between 0 and 80% glass fibre by volume. In embodiments of the invention, the coupler comprises between 20 and 70% glass fibre by volume. For example, the detachable structural coupler may comprise 50% by volume of glass fibre.

In embodiments of the invention, the detachable structural coupler comprises a single material that is homogeneous and at a macroscopic level isotropic. in embodiments of the invention, all components of the detachable structural coupler are made from the same material. For example, Grilon BO-50, comprising 50% by volume of glass fibre reinforcement within a semi-crystalline polyamide 6 matrix, Grilon TSGL-50/4 comprising 50% by volume of long glass fibre reinforcement within a semi-crystalline polyamide 6 matrix.

In embodiments of the invention, the detachable structural coupler comprises a single material that is heat stabilized. hi embodiments of the invention, the detachable structural coupler comprises a single material that is heat stabilized and has flammability class UL 94 HB under reference number EMS-CHEMIE E53898. In embodiments of the invention, the detachable structural coupler comprises a single material that is self-extinguishing as classified in accordance with UL 94 VO, and is free of halogens and red phosphorous. In embodiments of the invention, all components of the detachable structural coupler are made from the same material. For example, Grivory GV-5HLTm comprising 50% by volume of long reinforcing fibre within a matrix combining semi-crystalline polyamide and co-polyamide.

In embodiments of the invention, the components of the detachable structural coupler may be manufactured using an injection moulding process.

-25 -In embodiments of the invention, the detachable structural coupler is resistant to chemical corrosion. In embodiments of the invention, the detachable structural coupler has low electrical conductivity. In embodiments of the invention, the structural coupler has low thermal conductivity. In embodiments of the invention, the structural coupler has low specific heat.

In embodiments of the invention, the tube coupler is adapted to be compatibly used within a scaffold system comprising metallic tubes. In embodiments of the invention, the tube coupler is adapted to be compatibly used within a scaffold system comprising steel or aluminium tubes. In embodiments of the invention, the tube coupler may have a tube bearing seat equivalent to that of metallic scaffold couplers.

CO In embodiments of the invention, the tube coupler is adapted to be compatible in a scaffold system comprising composite tubes. For example, the tube coupler is particularly CO 15 suited to scaffold systems comprising the composite tubes.

In embodiments of the invention, the tube coupler is lighter than a metallic detachable C\J structural coupler. For example, the tube coupler may be about 10% to 30% the weight of the equivalent steel detachable structural coupler.

The tube coupler may be suitable for use in a tube and fit scaffold system. The tube coupler may be suitable for use in modular scaffold systems.

The tube coupler may have the arcuate bearing surface diameter adapted to suit its use.

The tube coupler may for example have a bearing surface diameter that is compatible with more conventional steel and aluminium scaffold tubes.

The tube coupler may be such that it can be used interchangeably with composite tubes or more conventional steel and aluminium scaffold tubes.

In embodiments of the invention, the tube coupler has a clamping strap with arcuate bearing surface subtending an arc angle greater than 180°. In embodiments of the invention, the arc angle subtended by the clamping strap is between 1900 and 2300. In embodiments of the invention, the arc angle subtended by the clamping strap is between 195° and 210'. For example, the arc angle subtended by the clamping strap is 198.10'.

In embodiments of the invention, the arc angle subtended by the clamping strap allows the coupler in use to have the clamping strap clipped onto the tube to which it is to be attached. In embodiments of the invention, the hearing force when the clamping strap is clipped onto the tube is sufficient to support the weight of the coupler prior to the coupler being fully fastened. In embodiments of the invention, the hearing force when the clamping strap is clipped onto the tube may be sufficient to support the weight of the CO coupler and a significant length of tube prior to the coupler being fully fastened. As such this feature may be helpful during the assembly of scaffold structures. CO 15

In embodiments of the invention, the tube coupler has a tensioning unit that may be rotated within its hinge bearing seat to allow the nut or bolt head of the tensioning C\J component to lightly bear upon bearing plate of the clamping strap. In embodiments of the invention, the tensioning component once located within the recess of the bearing 20 plate of the clamping strap may be torqued to provide the required level of tension force in the tension component. As such, the requisite levels of load may be transmitted from this tube to another similarly connected tube.

In embodiments of the invention, when an assembled tube coupler has two coupling elements and the clamping straps are at the top and bottom of the coupler then at least two vertical faces take the form of flat surfaces. In embodiments of the invention, the flat faces of the assembled coupler enable one coupler when attached to a tube to be intimately abutted against a second coupler attached to the same tube. In embodiments of the invention, the two intimately abutted couplers attached to a first tube may have the second and third tubes to which they are connected subtend any angle one to the other. As -27 -such, two intimately abutted couplers attached to the first tube may be used to increase the total load bearing capacity of the compound connection. Accordingly, the use of two intimately abutted couplers for a scaffold structure may be used to increase the total load bearing capacity at the connection between a longitudinal tube (ledger) and the vertical tube (standard) and between the lateral tube (transom) and standard. Accordingly, for a scaffold structure requiring the transom adjacent to a standard to form an integral part of the overall lateral bracing truss the use of a composite load hearing coupler serves this important purpose. As such the need for an additional underslung transom, so often required when adopting standard scaffold practice, is eliminated.

In embodiments of the invention, when transverse and longitudinal bracing of a scaffold structure is provided through the use of diagonal plan bracing an additional tube coupler CO may be intimately abutted beneath the coupler affixing the ledger to the standard. As such, in addition to transmitting any forces arising from the bracing action, the intimately CO 15 abutted pair of couplers increases the vertical load capacity at this connection.

Accordingly, where the above described tube couplers are also used to connect the (r) transom to the ledger, there will be three intimately abutted tube couplers. As such, the C\J use of the three intimately abutted couplers for a scaffold structure may further increase the total vertical load bearing capacity at the connection between a ledger and standard, a 20 transom and standard and a diagonal plan bracing and standard.

In embodiments of the invention, the tensioning components on the vertical faces do not protrude above the maximum elevation of the coupler when connected to a tube. As such, when the tube coupler is used for attaching transoms of a scaffold structures there is no obstruction to the placing of platform units over the transom coupler. Accordingly, for scaffold structures the tube coupler may usefully replace the commonly adopted putlog coupler for the attachment of transoms used to support the platform units.

In embodiments of the invention, the plan dimensions of the coupler body may be equal to the perpendicular distance between the centre lines of the two connected tubes. As -28 -such, a transom attached to either a ledger or to a standard will have the same elevation affording considerable practical advantages when used in scaffold structures. Accordingly, a full load bearing tube coupler connecting the transom direct to the standard further increases the total vertical load bearing capacity of the connection.

Accordingly, use of a full load bearing tube coupler to connect the transom adjacent to the standard to either the standard or the ledgers eliminates the need for an additional transom.

In embodiments of the invention, the tube coupler has a flexible clamping strap integrally cast with the coupler body. in embodiments of the invention, at one end the clamping strap is integrally cast with the coupler body. in embodiments of the invention, at the other end the clamping strap has a bearing plate according to the invention.

CO

In embodiments of the invention, the tube coupler is adapted to join structural tubes to CO 15 some other non-tubular component. In embodiments of the invention, the detachable tube coupler is adapted to join a scaffold tube to another structural component by adding to the (r) coupling element a means for fixing the tube coupler to another structure (second C\J coupling means). In embodiments of the invention, the second coupling means is of a form enabling a component other than a tube to be fixed in place relative to the tube 20 connected by the first coupling element. The second coupling means may allow attachment to some other structural component.

The other structural component (other than a tube) may for example he a scaffold platform unit or a scaffold toe board consisting of a wooden plank, or some other thin walled metal or composite platform unit.

In embodiments of the invention, the second coupling means may comprise a bearing block with an integrally formed female thread whose axis is normal to the diaphragm plate of the first coupling means.

-29 -In embodiments of the invention, the second coupling means has a coupling form to allow connection with a tie bolt. In embodiments of the invention, the second coupling means may be in the form of an integrally cast stud or nut. As such the integrally cast stud or nut could be metallic, stainless steel, or of the same fibre reinforced polymer as the other components of the tube coupler. Accordingly, the detachable coupler may for example be scaffold tie clamp.

In embodiments of the invention, the second coupling means has a coupling form to allow connection with a steel girder. In embodiments of the invention, the second coupling means may be of a form to allow connection with the web or flange of a steel girder. As such the second coupling means may be a plate normal to and integrally moulded with the diaphragm plate of the half body of the first coupling element.

CO Accordingly, the plate of the second coupling means may be parallel or normal to the axis of the tube attached to the first coupling element. co 15

In embodiments of the invention, the integrally moulded plate of the coupling form for the second coupling means may have another plate in a plane normal to the first plate C\J taking the form of a flange. In embodiments of the invention, threaded holes in this flange plate would allow the second coupling means to be attached to a structural plate lying 20 parallel to the diaphragm plate of the coupler body. As such, the tube coupler may for example be a scaffold toe-board clamp.

In embodiments of the invention, each of the coupling forms of the coupling element and second coupling means incorporate an integrally moulded diaphragm plate. The diaphragm plates for each of the coupling forms may be similar to the diaphragm plate incorporated into the coupler body of the first coupling form. In embodiments of the invention, the diaphragm plates may have a consistent form allowing any two types of coupling elements and/or second coupling means.

-30 -In embodiments of the invention, the moulds for each of the various coupling elements and means are modular and thus may be assembled to allow injection moulding of a wide range of different couplers. As such, where one coupling element permits the structural attachment of a scaffold tube, the use of the wide range of coupler forms for the second coupling means enables the manufacture of a wide range of scaffold coupler types. In embodiments of the invention, the integral connection of the moulds for the two coupling forms allows an injection moulding process to he used to manufacture an extensive range couplers required for the scaffold industry.

in embodiments of the invention, the injection moulds may be configured to allow the integral connection of the two parts of the coupler body. The use of modular injection moulds for each of the coupling forms leads to economies in the manufacturing process.

CO

The tube coupler according to the invention is more resistant to corrosion in normal CO 15 working environments compared to prior art couplers. The tube coupler according to the invention is more resistant to the corrosive effects of air and water than prior art couplers.

(r) The tube coupler according to the invention requires less frequent replacement than prior C\J art metallic tube couplers.

The tube coupler according to the invention is more resistant to the effects of chemical and biological attack than prior art tube couplers. The tube coupler according to the invention is more resistant to the corrosive effects of hostile chemical environments than prior art tube couplers. The tube coupler is consequently advantageous for use in corrosive marine and industrial environments. Accordingly, the tube coupler of this invention requires less frequent replacement than prior metallic scaffold couplers when used in these environments.

The tube coupler according to the invention may be an insulator to electricity and may reduce the risk of accidental electrocution for all those working with and on for example the scaffold structure. The tube coupler may be an insulator to electricity preventing electric current from being transmitted from one metallic tube to another. Accordingly, the risk of accidental electrocution even on metal scaffold structures is greatly reduced.

The tube coupler according to the invention may be an insulator to electricity and reduce the risk of build-up of static electricity. The tube coupler being an insulator to the transmission of static electrical charge from one tube to another will reduce the risk of static discharge. Accordingly, the risk of explosion in combustible environments due to accidental static sparking even on metal scaffold structures is greatly reduced.

The tube coupler according to the invention may have low specific heat capacity and low heat conductivity. Accordingly, the tube coupler may be more comfortable to handle in extremes of hot and cold weather.

CO

The tube coupler according to the invention may have a low modulus of elasticity. CO 15 Accordingly, when such tube couplers impact each other they emit lower frequency sound than equivalent metallic couplers so that handling during erection and demolition may be less noisy and environmentally intrusive than when equivalent metallic couplers C\J are used.

The tube coupler according to the invention may be constructed from high strength and stiffness fibres integrally embedded in a thermoplastic polymeric resin.

The tube coupler according to the invention may be adapted to be used compatibly with more conventional metallic scaffold couplers and ancillary jointing equipment.

The tube coupler according to the invention may be provided with variously coloured pigments. As such, the composite structural coupler may be coloured to represent a particular form of use.

-32 -The tube coupler according to the invention may be translucent, semi-translucent, and may comprise a light source located within and transmit light to the exterior of the tube coupler.

The tube coupler according to the invention may comprise a light source. The tube coupler may comprise a light source located within the cavity incorporated within the coupler body.

The tube coupler according to the invention may comprise a power source. The tube coupler may comprise one or more photoelectric cells, which may optionally be embedded within the body of the composite structural coupler.

CO The tube coupler according to the invention may comprise one or more photoelectric cells coupled to light sources and may be adapted to store solar energy during the daytime to CO 15 power the light source(s) at night time.

(r) The tube coupler according to the invention may be electromagnetic interference neutral.

The present invention will now be described by way of example with reference to the 20 accompanying drawings in which: Figure 1 shows an isometric view of an assembled tube coupler in the 90° configuration with the two coupling elements.

Figure 2 shows a side elevation of the assembled tube coupler of Figure 1 with clamping straps and tensioning units attached to the main body.

Figure 3 shows a plan of the assembled tube coupler of Figure 1 with clamping straps and tensioning units attached to the main body.

-33 -Figure 4 shows a vertical section A-A, as shown in Figure 3, through the assembled tube coupler with clamping straps and tensioning units attached to the coupler body.

Figure 5 shows an isometric view of the tube coupler full body.

Figure 6 shows a side elevation of the tube coupler full body of Figure 5.

Figure 7 shows a plan of the tube coupler full body of Figure 5.

Figure 8 is a horizontal section B-B, as shown in Figure 6, through the tube coupler full body.

CO CO 15

O

Figure 9 is a vertical section C-C, as shown in Figure 7, through the tube coupler full body.

Figure 10 shows an isometric view of the tube coupler clamping strap.

Figure 11 shows a plan of the underside of the tube coupler clamping strap as shown in Figure 10.

Figure 12 shows vertical sections D-D and E-E, as shown in Figure 1 I, through the tube coupler clamping strap.

Figure 13 shows an isometric view of the tube coupler tensioning unit.

Figure 14 shows a front and side elevation of the tube coupler tensioning unit of Figure 13.

Figure 15 shows vertical sections F-F and G-G and a compound horizontal section H-H, as shown in Figure 14, through the tube coupler tensioning unit.

-34 -Figure 16 shows an isometric view of the tube coupler half body.

Figure 17 shows an isometric view of the assembled tube coupler in the parallel configuration with the two coupling elements.

Figure 18 shows a section through an assembled tube coupler with the two coupling elements comprising a clamping strap formed integrally with the coupler body.

Figure 19 shows a side elevation of an assembled tube coupler with the two clamping elements comprising a clamping strap and tensioning unit formed integrally with the coupler body.

CO

Figures 20 show side elevations for a range of assembled tube couplers comprising an CO 15 upper coupling element and lower, second coupling means suitable for attachment to some structural component other than a tube; such second coupling means could take the (r) form of: a threaded stud (Figure 20a); a captive nut (Figure 20b); a mounting plate C\J (Figures 20c and 20d); and a form of G-clamp (Figures 20e and 20f).

Figure I shows an isometric view of the assembled tube coupler in the 90° configuration with the two coupling elements, comprising clamping straps (20) and tensioning units (30) attached to the coupler body (10). The clamping straps (20) and tensioning units (30) are connected to and tensioned one to the other by means of the tensioning components (40). The clamping straps (20) and tensioning units (30) are each connected to the coupler body (10) through integrally cast hinges (50). The hinges (50) allow flexible rotational movement both between the clamping straps (20) and coupler body (10) and between the tensioning units (30) and the coupler body (10).

-35 -Figure 2 shows a side elevation of the assembled tube coupler of Figure 1 with clamping straps (20) and tensioning units (30) attached to the main body (10) through the hinge (50). By making the hinge bearing opening L5 = 7 2mm to the side of the hinge pins less than the diameter D2 = 2R2 = 8mm of the hinge pin (51) creates a capture mechanism preventing the clamping straps (20) and tensioning units (30) from being removed in a direction normal to the axes of the hinge pins (51). The pair of hinge bearing seats (12) for the hinge pins (5 I) within the coupler body (10) is shown in the upper attachment element of the side elevation to he symmetrically placed with respect to the tube being attached. This allows the clamping straps (20) and tensioning units (30) to he assembled on either side of the coupler body (10). Each of the clamping strap (20), tensioning unit (30) and coupler body ( 10) have inside arcuate bearing surfaces of radius R I = 24. 15mm allowing intimate connection with a tube of radius R I being connected. A similar circular CO arc of radius RI is formed on the underside of the body (10) at right angles to the upper circular arc, providing a perpendicular distance LI between the axes of the two tubes CO 15 being connected together; typically LI = 62.3mm when the tubes connected have a diameter of D1 = 48.3mm. The pin tension plates (52) (see Figures 12 and 13) connecting (r) the hinge pins (51) to the clamping strap (20) and tensioning unit (30) have a shape that C\J matches the bearing surfaces of the hinge bearing shear plates (12) and their side openings within the coupler body (10). When the clamping straps (20) or the tensioning units (30) are suitably aligned with the side openings of the bearing surfaces of the coupler body (10) it is possible to slide in the direction of the hinge pin axis the clamping straps (20) and the tensioning units (30) into the coupler body (10). When fully inserted it is then possible for the hinge pins (51) to he rotated freely over the required arc range within the capture mechanism of the coupler body (10). To prevent the accidental sliding out in the direction of the hinge axis of either the clamping straps (20) or the tensioning units (30) from their capture mechanisms a number of measures can be incorporated into the design. Some of these features are described in relation to subsequent Figures. For practical reasons, it is useful for the tube spacing LI when coupled to be equal to the coupler width Wl; typically W1 = 62.3mm. With the clamping strap having a thickness T1 = 3mm the overall height of the coupler is L2 = 116.6mm. hi the particular embodiment shown, the tensioning component (40) comprises a hexagonal bolt head (44) bearing onto the bearing plate (25) of the clamping strap (20) and a square nut (43) slotted into a preformed aperture within the anchor block (31) of the tensioning unit (30). The eccentricity of the bolt W2 is kept to a minimum consistent with providing the sufficient tensile strength to the anchor block (31) of the tensioning unit (30); typically, W2 = 35.35mm In the illustrated embodiment both the bolt and nut are Grade 316 stainless steel.

Figure 3 shows a plan of the assembled tube coupler of Figure 1 with clamping straps (20) and tensioning units (30) attached to the main body. The eccentricity W2 of the tensioning component (40) relative to the square planform W 1 of the main body is kept to a minimum, allowing the force in the tensioning component (40) to he transmitted from CO the hearing plate (25) into the clamping strap (20) via reinforcing ring ribs (22), transverse ribs (24) and the mid-surface shell (27). CO 15

Figure 4 shows a vertical section A-A, as shown in Figure 3, through the assembled tube coupler with clamping straps (20) and tensioning units (30) attached to the coupler body C\J (10). The perpendicular distance between the two tubes when connected is typically, L3 = 14mm, and with the tube diameter Dl = 48 3mm the perpendicular distance between the 20 axes of the two tubes when attached is Ll = 62.3mm, chosen to equal the width W1 of the coupler. The hinge pins (51) having diameter D2 = 8mm transfer the forces from the clamping strap (20) and the tensioning unit (30) to the coupler body (10) through the hinge bearing shear plates (12). In this embodiment the tensioning component (40) is a stainless steel hexagonal head bolt (44) of diameter D3 = 8mm transferring its tension force into the hearing plate (25) of the clamping strap (20) and into the embedded stainless steel square nut (43) within the anchor block (31) of the tensioning unit (30). To provide sufficient pull-out capacity the nut (43) has a minimum embedment depth of T3 = 7.0mm. Shear keys (28) incorporated into the sides of the clamping straps (20) are designed to mesh into keyways (35) built into the tensioning units (30). Additional shear keys (38) incorporated into the tensioning units (30) are designed to mesh into keyways (29) built into the clamping straps (20). Each of these shear keys provides additional load transfer capacity, particularly when the tensioning units (30) are required to transfer to the clamping straps (20) a shear force parallel to the axis of the tube to which they are attached.

Figure 5 shows an isometric view of the tube coupler full body (10). This can practically he formed from two half coupler bodies (shown in Figure 16) arranged to have their tube hearing surface axes at right angles to each other. The hearing surfaces are made up of a series of arcuate ribs (16) separated by rib slots (19), the purpose of which is to keep component weight to a minimum consistent with required strength. The arcuate ribs (16) extend to form the hinge bearing shear plates (12), and the rib slots (19) are aligned with the pin tension plate slots (18). The pin tension plates (52) (see Figure 10 and 13) are able CO to rotate freely within the pin tension plate slots (18) as part of the coupler body (10) capture mechanism. The diaphragm plate (15) (see Figure 9) lies between the two sets of CO 15 rib slots (19) of the upper and lower tube bearing surfaces. The material between the rib slots (19) and the pin tension plate slots (18), together with the outer pair of arcuate ribs (r) (16), forms a thin walled box section giving the coupler body (10) its requisite torsional C\J and bending strength and stiffness. A transverse rib (11) provides an additional conduit to improve the flow of molten resin during the injection moulding process.

Figure 6 shows a side elevation of the tube coupler full body (10) of Figure 5. The diameter D2' = 8.2mm of the hinge bearing seats (13) is formed to a close tolerance with the diameter D2 = 8mm of the hinge pins (51). To ensure the hinge pins remain captured, the hinge hearing openings (14) of L5 = 7.2mm is less than the diameter D2 = 8mm of the hinge pins (51). This hinge bearing opening (14) is shaped to fit the pin tension plates (52) (see Figures 12 and 14) integrally formed as part of the hinges (50) on the clamping straps (20) and tensioning units (30), permitting the hinge pins (51) to be pushed in along their axes but only when very carefully aligned with the hinge bearing opening (14). The width W5 of the hinge bearing shear plates (12) is chosen to provide a strength consistent with the pin tension plates (52) (see Figures 10 and 13), and in this example W5 = 6.03mm. The pin tension plate slots (18) have a width W6' = 5.23mm to accommodate with sufficient tolerance the pin tension plates (52) having thickness W6 = 4.83mm. The arcuate ribs (16) and hinge bearing shear plates (12) in this example subtend an angle of 81 = 31.15° making the overall height of the coupler full body L6 = 37.32mm, the diaphragm plate (15) has a thickness T2 = 1.8mm at the exposed outer edges but 4 Omm between the rib slots (19) of the two coupling means.

Figure 7 shows a plan of the tube coupler full body (10) of Figure 5, having square plan form width W 1 = 62.3mm. The tube bearing surfaces are made up from a series of arcuate ribs (16) separated by rib slots (19), which respectively align with the hinge bearing shear plates (12) and the pin tension plate slots (18). The two sets of orthogonal arcuate ribs (16) on the upper and lower tube hearing surfaces are separated by a CO diaphragm plate (15) (see Figure 9) of thickness T2 = 4.0mm; this also helps to create the required torsional strength and stiffness of the coupler body (10). A transverse rib (II) CO 15 provides an additional conduit to improve the flow of molten resin during the injection moulding process. The hinge pins have axes separated by a distance W4 = 54.3mm, (r) providing enough distance to create the capture mechanism to the side of the hinge pins C\J (51) and to provide the additional strength to the hinge bearing shear plates (12) on the inside. The width W5 of the hinge bearing shear plates (12) is chosen to provide a strength consistent with the pin tension plates (52) (see Figures 10 and 13), and in this example W5 = 6.03mm. The pin tension plate slots (18) have a width W6' = 5.23mm to accommodate with sufficient tolerance the pin tension plates (52) having thickness W6 = 4.83mm.

Figure 8 is a horizontal section B-B (see Figure 6) through the tube coupler full body (10) showing the alignment of the arcuate ribs (16) with the hinge bearing shear plates (12) and the associated alignment of the rib slots (19) and the pin tension plate slots (18). A transverse rib (11) allows more even distribution of molten resin during the injection moulding process. Section B-B also shows the rectangular thin walled box containing the rib slots (19) of inner width W8 = 23.3mm (see Figure 9). The walls (17) of the -39 -rectangular thin walled box have their outer surfaces aligned with the shape of the pin tension plates (52) (see Figures 12 and 14) when the clamping strap (20) and tensioning unit (30) are rotated to lie in the attached configuration. The width W5 of the hinge bearing shear plates (12) is chosen to provide a strength consistent with the pin tension plates (52) (see Figures 10 and 13), and in this example W5 = 6.03mm.

Figure 9 is a vertical section C-C (see Figure 7) through the coupler full body (10) having overall height L6=37.32mm, showing the arcuate ribs (16) and the transverse rib (11) contained within the walls (17) of the box. The hinge hearing shear plates (12) and the pin tension plate slots (18) provide part of the capture mechanism for the hinge pins (51).

Section C-C shows the rectangular thin walled box containing the rib slots (19) of inner width W8 = 23.3mm (see Figure 8). The walls (17) of the rectangular thin walled box CO have their outer surfaces aligned with the shape of the pin tension plates (52) (see Figures 12 and 14) when the clamping strap (20) and tensioning unit (30) are rotated to lie in the CO 15 attached configuration. Section C-C also shows the location of the diaphragm plate (15) of thickness T2 = 4.0mm separating the two sets of arcuate ribs (16). It also shows the separation between the two connected tubes L3 = 14mm.

Figure 10 shows an isometric view of the tube coupler clamping strap (20). At the hinge (50) end of the strap (20) the pin rod (51) is connected to the thin clamping strap wall (21) by means of pin tension plates (52) with the local stress concentrations reduced by means of the ring ribs (53). The pin tension plates (52) are separated by the hinge bearing shear plate slots (54) that allow the pin rod (51) of the clamping strap (20) to rotate freely about the hinge bearing shear plates (12) of the coupler body (10). The clamping strap wall (21) is at its other end connected to the tensioning component (40) by means of the bearing plate (25) within which the tensioning component opening (26) allows the tensioning component (40) to be rotated into position to have a minimum eccentricity with respect to the strap wall (21). The bearing plate (25) is reinforced to carry the eccentrically positioned tensioning component (40) force through the primary external bearing ring ribs (22) and within the bearing block by the additional internal strap ring -40 -ribs (23) (see Figure 11 and 12). Additional external ring ribs (22) interact with transverse ribs (24) and a thin central shell (27) (see Figure 12) to ensure the force from the tensioning component (40) is laterally distributed across the strap wall. Both sides are provided with shear keys (28) that upon tightening of the tensioning component (40) intermesh with the shear keyways (35) (see Figure 13) within the tensioning unit (30).

These interlocking shear keys (28) and keyways (35) act to prevent relative shear deformation across the gap between the clamping strap (20) and the tensioning unit (30) that would otherwise cause serious overloading of the tensioning component (40).

Figure II shows a plan of the underside of the tube coupler clamping strap (20) as shown in Figure 10. The arcuate internal strap ring ribs (23) assist in ensuring the force from the tensioning component (40), applied to the clamping strap (20) through the hearing plate

CO

(25), is distributed evenly across the width of the strap wall (21). Keyways (29) ensure CO that upon tightening of the tensioning component (40) the shear keys (38) (see Figures 13 CD 15 and 14) within the tensioning unit (30) interlock with the keyways (29) of the clamping CO strap (20). These interlocking shear keys (38) and keyways (29) also act to prevent C\J relative shear deformation across the gap between the clamping strap (20) and the tensioning unit (30) that would otherwise cause serious overloading of the tensioning component (40).

Figure 12 shows vertical sections D-D and E-E, as shown in Figure II, through the tube coupler clamping strap (20). Over most of its length the clamping strap (20) has uniform thickness across its width of TI = 3mm and the vertical distance between the centre-line of the pin rod (51) and the centre-line of the connected tube is L7 = 26. 15mm. The arcuate lower surface of the lower transverse rib subtends an angle of St ' = 29.96) providing the tolerance required for the arcuate upper surface of the hinge bearing shear plates (12) of the coupler body (10). To provide sufficient capacity to the hinge bearing shear plates (12) (see Figures 6 and 9) the centre-lines of the pairs of pin rods (51) are separated by a width of W4 = 54.30mm. The pin rod (51) has radius R2 = 4mm and the pin tension plates (52) a minimum thickness T4 = 7mm To provide adequate shear strength of the bearing plate (25) it outer thickness is T5 = 5 5mm with a taper angle of 82 = 11.86°. The bearing surface of the bearing plate (25) is at a height of L8 = 14.33mm above the centre-line of the connected tube. Shear keys (28) intermeshing with the keyways (35) in the tensioning units (30) (see Figures 13 and 14) provide shear capacity across the connection between the tensioning unit (30) and the clamping strap (20). Shear keyways (29) intermeshing with the keys (38) in the tensioning units (30) (see Figures 13 and 14) provide added shear capacity across the connection between the tensioning unit (30) and the clamping strap (20). Internal ring ribs (23) are aligned with the external ring ribs (22) shown in Figure 10. To prevent any possibility of the clamping straps (20) from being accidentally dislodged in the direction of the hinge axis, one of the end pin tension plates (52) has a minimum thickness T4 = 7.3mm greater than the hinge bearing opening CO (14) of L5 = 7.2mm (see Figure 6). This out of tolerance of the end pin tension plate (52) and the hinge bearing opening (14) requires a significant longitudinal force to be exerted CO 15 along the pin axis when inserting the clamping straps (20), and serves to prevent the clamping strap (20) from being accidentally dislodged from the coupler body (10) when in use.

Figure 13 shows an isometric view of the tube coupler tensioning unit (30). At the hinge pin (50) end the pin rods (51) are connected by means of pin tension plates (52) to the ring ribs (33), which with the transverse ribs (34) and a midsurface shell (37) (see sections G-G and H-H Figure 15) allow more effective lateral distribution of the force from the tensioning component (40). The pin tension plates (52) are separated by the hinge bearing shear plate slots (54) (see Figure 14). An anchor block (31) has bolt hole (32) and within an aperture (36) is embedded for this embodiment the square nut (43) of the tensioning component (40) (see Figures 14 and 15). Keyways (35) on either side allow the shear keys (28) of the clamping strap (20) to intermesh when the tensioning component (40) is tightened. Keys (38) on either side allow the shear keyways (29) of the clamping strap (20) to intermesh when the tensioning component (40) is tightened.

-42 -Figure 14 shows a front and side elevation of the tube coupler tensioning unit (30). In this embodiment the square nut (43) of the tensioning component (40) is embedded into an aperture (36) within the anchor block (31) to prevent any torsional motion when the tension unit (40) is torqued. Maximum thickness T3 = 7.0mm of composite cover to the embedded nut (43) is chosen to prevent pull-out from the anchor block (31). The width W6 = 4.83mm of the pin tension plates (52) fit within the bearing shear plate slots (18) of the coupler body (10). The width W5 = 6.03mm of the hinge hearing shear plates ( I 2) fit within the width W5' = 6.43mm of the pin tension plate slots (54) of the tensioning unit (30). Keyways (35) on either side allow the shear keys (28) of the clamping strap (20) to intermesh when the tensioning component (40) is tightened. Keys (38) on either side allow the shear keyways (29) of the clamping strap (20) to intermesh when the tensioning component (40) is tightened.

CO

Figure 15 shows vertical sections F-F and 0-0 and a compound horizontal section H -H, CO 15 as shown in Figure 14, through the tube coupler tensioning unit. These show the square nut aperture (36) housing the nut (43) of the tensioning component (40) (see Figure 2) embedded within the composite anchor block (31), with a maximum thickness T3 = C\J 7.0mm of composite cover chosen to prevent pull-out of the nut (43) from the anchor block (31). The arcuate lower surface of the lower transverse rib (34) subtends an angle of Si' = 29.96) providing the tolerance required for the arcuate upper surface of the hinge bearing shear plates ( 12) of the coupler body (10). The details of the hinge pin rod (5 I) and pin tension plate (52) are as for the clamping strap (20) in Figure 12. The hinge pin rods (51) are connected by means of pin tension plates (52) to the ring ribs (33), which with the transverse ribs (34) and a midsurface shell (37) allow effective lateral distribution of the force from the tensioning component (40). The pin tension plates (52) are separated by the hinge bearing shear plate slots (54). The bolt hole (32) of diameter D3'=8.4mtn is aligned with distance W2 = 35.35mm from the tube centre and eccentricity of the bolt centre-line corresponds with a distance W13 = 11.2min relative to the outer edge of the coupled tube. To prevent any possibility of the tensioning units (30) from being accidentally dislodged in the direction of the hinge axis, one of the end pin -43 -tension plates (52) has a minimum thickness T4 = 7 3mm greater than the hinge bearing opening (14) of L5 = 7.2mm (see Figure 6). This out of tolerance of the end pin tension plate and the hinge bearing opening requires a significant longitudinal force to be exerted along the pin axis when inserting the tensioning units (30); this serves to prevent the tension unit from being accidentally dislodged when in use. Keys (38) on either side allow the shear keyways (29) of the clamping strap (20) to intermesh when the tensioning component (40) is tightened.

Figure 16 shows an isometric view of the tube coupler half body (10). This is identical with the upper part of the full body shown in Figure 5. This can practically he used together with a similar coupler half body to form the right angle configuration arranged to have their tube bearing surface axes at right angles to each other, shown in Figure 1, or CO the parallel configuration arranged to have their tube bearing surface axes parallel to each other shown in Figure 17. Additionally, this coupler half body (10) may form part for a CO 15 range of assembled tube couplers comprising an upper tube coupling element and a lower, second coupling means suitable for attachment to some structural component other (r) than a tube as shown in Figures 20. The upper coupling element in each case is the C\J coupling element described with respect to Figures 1 to 15 above. The tube bearing surface for the half coupler body (10) is made up of a series of arcuate ribs (16) separated by rib slots (19), the purpose of which is to keep component weight to a minimum consistent with required strength. The arcuate ribs (16) extend to form the hinge bearing shear plates (12), and the rib slots (19) are aligned with the pin tension plate slots (18). The pin tension plates (52) (see Figure 10 and 13) are able to rotate freely within the pin tension plate slots (18) as part of the coupler body (10) capture mechanism. The material between the rib slots (19) and the pin tension plate slots (18), together with the outer pair of arcuate ribs (16), forms a thin walled box section giving the coupler body (10) its requisite torsional and bending strength and stiffness. The material at the underside of the rib slots (19) forms part of the diaphragm plate (15).

-44 -Figure 17 shows an isometric view of the assembled tube coupler in the parallel configuration with the two coupling elements, comprising clamping straps (20) and tensioning units (30) attached to the main body (10). The clamping straps (20) and tensioning units (30) are connected by and tensioned one to the other by means of the tensioning components (40). The clamping straps (20) and tensioning units (30) are each connected to the coupler body (10) through integrally cast hinge pins (50). The hinge pins (50) allow flexible rotational movement between the clamping straps (20) and coupler body (10) and between the tensioning units (30) and the coupler body ( 10). The example configuration shows the hinge pins (50) of the clamping straps (20) on the same side of the assembled coupler; one or other of these hinge pins (50) of the clamping straps (20) could equally be located on opposite side of the coupler body ( 10).

CO Figure I8 shows a section through an assembled tube coupler with the two coupling elements comprising a clamping strap (60) formed integrally with the coupler body and a CO 15 tensioning unit (70). The tensioning component in this embodiment incorporates a stainless steel stud (71) integrally embedded within an anchor block of the tensioning unit (r) (70). Ring ribs (72) allow the force from the stainless steel stud (71) to be distributed C\J across the width of the hinge pin (50). To allow the tensioning unit (70) to be rotated about the hinge pin (50) in order for the nut (73) of the tensioning unit (70) to be slotted into the opening of the bearing block (61), the tensioning unit (70) covers a wider arc of the tube circumference than in the first coupling form described in Figures I to 15; this also allows the tube to be connected to be slotted in from the side by flexing the thin wall of the tensioning strap (60) when the tensioning unit is fully retracted. The arcuate ribs (62) of that part of the coupler body associated with this second coupling form are extended further towards the strap allowing the interspersed slots (63) to be extended.

The diaphragm plate (64) would be similar to that of the diaphragm plate (15) for the half coupler body shown in Figure 16. In the illustration shown the lower coupling means is also of this second coupling form, but this could equally be of any other coupling form. The hinge pin (50) arrangements can be adopted from those described above for the first coupling form. This second coupling form requires just one rotating part, and in say a -45 -scaffold context requires the tubes to be simply clicked into place, allowing the tube to be held in position prior to tightening the tensioning component (71).

Figure 19 shows a side elevation of an assembled tube coupler with the two coupling elements comprising a clamping strap (80) and tensioning unit with a lower bearing block (85) formed integrally with the coupler body. The tensioning component (81) in this embodiment consists just of a standard stainless steel bolt with an Allen key head (82) to keep the required eccentricity with respect to the clamping strap wall to the lowest level possible. For convenience, the square stainless steel nut (83) could be embedded within the lower bearing block (85) of the tensioning unit to prevent rotation when the bolt is tensioned from the Allen key head (82). Otherwise the upper hearing block (84) could be of essentially the same form as that of the lower bearing block (85), with the difference CO that the lower hearing block (85) would be integrated into a series of ribs (86) separated by slots (87). A similar set of ribs (86) and slots (87) would provide the strength and CO 15 stiffness required between the coupled tubes. In this case the tube to be attached would need to be inserted into the coupler along its axial direction. In the configuration shown (r) the lower coupling element is the same as the upper coupling element. Again, the C\J modular nature of the coupling element means that the lower coupling element may differ from the upper coupling element. The embodiment of the coupling element shown in Figure 19 avoids the need for any rotating parts, but against this is the inconvenience in say a scaffold context of requiring the tubes to be slotted into the coupler end on -not always easy. It is likely that this embodiment element would be suitable for applications where loads to he transmitted are of a moderate level.

Figures 20 shows side elevations for a range of assembled tube couplers comprising an upper coupling element and a lower, second coupling means suitable for attachment to some structural component other than a tube. The upper coupling element in each case is the coupling element described with respect to Figures 1 to 15, having a tube coupler half body as shown kin Figure 16. However, the upper coupling element could be any coupling elements according to the invention. The base plate (100) dimensions would be determined by the loads to be transmitted and if needed a form of rib reinforced base plate could be adopted. Whatever the form, the modular nature of the injection moulds allows a wide range of couplers to be assembled. In the first illustrative example Figure 20(a) shows a second coupling means comprising a single stainless steel stud (102) embedded into an anchor block (101) as part of the composite base plate (100). As a variant the composite stud (102) could be replace with a bolt having its head embedded within the base plate ( 100) of the coupler half body (10). Alternatively, the stud (102) could be integrally formed with the composite material of the base plate ( 100). In some situations it is more convenient to have the stainless steel nut (103) integrally formed or inserted within an anchor block (101) as part of the base plate (100) as illustrated in Figure 20(b). As a third illustrative example Figure 20(c) shows a second coupling means comprising a composite plate (104) integrally formed with the composite base plate (!00).

CO The plate (104) could have holes (105) formed to allow attachment to a variety of structural components. As a result of the modular nature, the plate (104) could be CO 15 arranged to lie normal to the axis of the tube to be connected to the upper coupling means, as illustrated in Figure 20(c), or to be parallel with axis of the tube to be attached (r) to the upper coupling means, as shown in Figure 20(d). As a fifth illustrative example C\J Figure 20(e) shows a second coupling means comprising a composite web plate (106) integrally faulted with the composite base plate (100) and a flange plate (107). As a result of their modular nature the mould for the web plate (106) could be attached to the mould for the half coupler body (10) so that the web plate (106) lies parallel to the axis of the tube to be connected to the upper coupling element, as illustrated in Figure 20(e), or to lie normal to the axis of the tube to be attached to the upper coupling element, as shown in Figure 20(f). The flange plate (107) could have holes ( 105) formed to allow attachment to a variety of structural components, such as the flange of a hot rolled steel section, or to hold in place the toe boards on a scaffold platform; for these purposes the holes could be threaded to allow the bolt (108) to be tightened against the attached component.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combinations, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to CO any novel one, or any novel combination, of the steps of any method or process so disclosed.

CO O

Claims

Claims 1. A tube coupler having two coupling elements with at least one being a tube clamping element comprising: (i) a body; (ii) a damping strap, integrally attached to the body or pivotally attached to the body at a hinge pin that is integral to the strap; (iii) a tensioning unit, at an opposing position on the body to the clamping strap, integrally attached to the body or pivotally attached to the body at a hinge pin that is integral to the tensioning unit; and (iv) a tensioning component that biases the clamping strap towards the tensioning unit to grip the tube, wherein for a first clamping form the tube clamping dement comprises a body, clamping strap and tensioning unit that are movable to form two configurations selected from: a closed configuration in which the body, clamping strap and tensioning unit provideCOthree sections of a substantially continuous circular ring that is capable of gripping a circular CO tube; and an open configuration that enables the circular tube to be inserted into the clamping element without significant resistance, and wherein the clamping element for a second clamping form has either or both the C\I clamping strap and the tensioning unit integrally attached to the body, and wherein the second coupling element comprises either a second tube clamping element or a coupling means suitable for attachment to some other structural component, and wherein all components of both coupling elements are made of a composite material comprising a polymer and reinforcing fibres, or alternatively the tensioning components is made from stainless steel.
2. The tube coupler according to claim 1, wherein the polymer is a polymeric resin.
3. The tube coupler according to claim 1 or claim 2, wherein in the polymer is strengthened with reinforcing fibres, such as glass fibres.
4. The tube coupler according to any one preceding claim, wherein the tensioning component is a threaded stud and nut or a threaded bolt and nut.
5. The tube coupler according to claim 4, wherein the nut and/or the threaded stud or bolt is made of a composite material.
6. The tube coupler according to claim 4, wherein the nut and/or the threaded stud or bolt are made of a metallic material.
7. The tube coupler according to claim 4 and 6, wherein the nut and/or the threaded stud or bolt are made of stainless steel.
8. The tube coupler according to any one of claims 4 to 7, wherein the head of the bolt and/or the nut is either bearing on, embedded in or slotted in to the tensioning unit with the nut and/or the head of the bolt bearing on the bearing plate of the clamping strap.
9. The tube coupler according to claim 4 or claim 5, wherein the stud and/or the nut isCOintegrally formed with the tensioning unit and the nut of the stud or the head of the bolt bear on the bearing plate of the clamping strap.COO
10. The tube coupler according to any one previous claim, wherein one or more of the C\I body, clamping strap and tensioning unit comprise circumferential reinforcing ribs.
11. The tube coupler according to claim 10, wherein the ribs are external and/or internal.
12. The tube coupler according to claim 10 or claim 11, wherein the ribs on the clamping strap and/or the tensioning unit interlock with the ribs on the body to prevent movement along the axis of the clamping strap hinge pin and/or the tensioning unit hinge pin.
13. The tube coupler according to any one of claims 10 to 12, wherein one or more of the hinge pins are rotatable in hinge bearings formed by the ribs on the body that are open-sided and enable the one or more hinge pins to be removed from the hinge bearings by movement in the direction of the hinge axis, thereby rendering the clamping strap and/or the tensioning unit removable from the body.
14. A tube coupler according to claim 13, wherein the hinge pins are connected to the clamping strap and the tensioning unit by means of parallel integrally formed pin tension plates normal to the hinge pin and separated by pin tension plate slots, and wherein the parallel pin tension plates are aligned with internal and/or external ribs on the clamping strap and the tensioning unit.
15. A tube coupler according to claim 14, wherein the oversize of one end pin tension plate of the clamping strap and tensioning unit relative to the opening to the side of the hinge hearing seats require considerable force for the hinge pin to he pushed in the direction of its axis into the hinge bearing.
16. The tube coupler according to any one of claims 13 to 15, wherein the hinge pins are substantially the same size and the hinge hearings are substantially the same size, thereby enabling the clamping strap and the tensioning unit to be interchangeable on the body.CO
17. The tube coupler according to any one of claims 1 to 15, wherein the clamping strap CO and/or the tensioning unit is integral with the body.
Ocr) 18. A tube coupler according to any one preceding claim, wherein the tensioning C\J component does not protrude above the highest point of the clamping strap or tensioning unit furthest from the body.
19. A tube coupler according to any one preceding claim, wherein at least two faces of the assembled tube coupler have a planar form and do not protrude beyond the width of the square planform of the coupler body.
20. The tube coupler according to any one preceding claim, comprising two clamping elements mounted body to body and configured to clamp two tubes together in parallel or at an angle.
21. A tube coupler according to claims 19 and 20, wherein the height of the coupler body ensures the perpendicular distance between the two axes of the connected tubes is equal to the width of the coupler body, clamping strap and tensioning unit of the coupler.
22. The tube coupler according to any one of claims 1 to 18, comprising a clamping element and a second coupling means for fixing the tube coupler to another structure, wherein the second coupling means is selected from a group consisting of: an integrally embedded stud; a loosely or integrally embedded bolt; an integrally or loosely embedded nut; a fixing plate; a laterally-facing G-clamp; and a tube clamp comprising a close-fitting ring and a radially-mounted compression stud, and wherein the clamping element is configured to clamp the tube and the other structure together in parallel or at an angle.
23. The tube coupler according to any one of claims 20 to 22, wherein the two clamping elements, or the clamping element and means for fixing, are mounted substantially perpendicularly. thus clamping two tubes, or the tube and other structure, parallel or at 90° with respect to each other.COelement, and a captive threaded stud or nut.
24. The tube coupler according to any one of claims 1 to 18, comprising a clampingCO
O 25. A tube coupler according to any one preceding claim, which is pigmented to produce cr) colours chosen to suite a particular client or to encode a particular form of use.
26. A tube coupler according to any preceding claim, further comprising a light source within, and which is translucent to allow light from the light source to be transmitted.
27. A tube coupler according to any one preceding claim, which has modular moulds for the body component that allow efficient injection moulding of a wide range of composite couplers for connecting a tube to another tube or to some other structural component.
28. An injection mould configured to make the tube coupler of any preceding
29. A tube coupler herein described with reference to the accompanying drawings.