Technical Field

This invention relates generally to a structural tubing assembly and method of assembling the same. Particularly, but not exclusively, the invention relates to a system and method for mechanically connecting structural tubing in a releasable manner.

Background

Structural tubing, such as steel, aluminium or even rigid plastic tubing, can come in a variety of cross- sectional shapes, typically square, rectangular or round. Its hollow structure provides a high strength- to-weight ratio making it suitable for use in a wide range of structural applications in both industrial and domestic settings, e.g. construction of frames, supports, furniture, and other products and equipment. A structural tubing assembly comprises pieces of structural tubing or tubular members that are provided separately (optionally cut to size) and then joined/connected together, by an end user or a manufacturer, to produce the desired structure.

A common method for connecting pieces of tubing is by welding. Welding is the process of joining two materials together by the application of heat. Although welding is an effective technique for providing mechanically strong and stable joints, it has a number of disadvantages in certain applications. For example, welding is only suitable for connecting certain materials (e.g. steel) and so it cannot be used for all tubing assemblies, particularly those where tubing formed of different, weld-incompatible, materials need to be connected e.g. aluminium and steel, and metal and plastic. It requires specialist equipment and training, so is not suitable for use in self-assembly systems which are meant for the general public or end user to assemble. Welding is also an irreversible process and it can be difficult to disconnect components once they have been welded together, making it unsuitable for connecting assemblies that need to be later disassembled, and even re-assembled (e.g. welded assemblies cannot easily be taken apart for storage and/or transport).

An alternative to welding is to mechanically connect two pieces of tubing via an intermediate connector piece whereby each piece of tubing is independently connected to the intermediate connector, e.g. clamp-based connectors, or strut-based connectors that extend into the ends of the tubing. These tube connectors provide a relatively inexpensive and detachable connection means, but the connection is substantially less rigid than welding and susceptible to angular deflection or “flex”, which is undesirable for most structures. In particular, this effect compounds as the size of the assembled structure increases, and/or as the number of connections in the structure increases.

Aspects and embodiments of the present invention have been devised with the foregoing in mind.

Summary of Invention According to a first aspect of the invention there is provided a structural tubing assembly. The structural tubing assembly may comprise a first tubular member, a second tubular member, and a fastening means for releasably securing the first and second tubular members together in an assembled configuration. The first tubular member may have a male connection portion. The second tubular member may have a female connection portion. The male connection portion may be configured with one or more projections. The female connection portion may be configured to receive the one or more projections of the male connection portion in an assembled configuration. The female connection portion may be configured to receive the one or more projections of the male connection portion to provide a direct connection between the tubular members. The fastening means may be configured to releasably secure the male connection portion to the female connection portion in the assembled configuration. The male and female connection portions may be configured to interlock to provide a direct mechanical connection between the first and second tubular members.

The structural tubing assembly provides a direct mechanical connection between the first and second tubular members which is secured using the fastening means to ensure a tight fit. This has a number of advantages over indirect mechanical connections formed using an intermediate connector piece. The angular deflection or “flex” associated with the connection may be substantially reduced compared to indirect mechanical connections formed using an intermediate connector piece. In addition, the strength of the connection is provided by the material of the tubing itself, rather than that of a separate connecting piece and the joints between the connection piece and each respective tubular members. As such, for a given pair of tubular members, the connection provided by the invention may be substantially stronger (i.e. able to withstand substantially greater stress or load before failure) than indirect connections.

The reduced angular deflection may be the result of the tight and secure connection provided by the fastening means, and/or a reduced number of connection points between the first and second tubular members. For example, the direct connection ensures that there is a single connection point between the connecting portions of the first and second tubular members, whereas in prior art systems in which each tubular member connects individually to a separate intermediate connection piece there are two separate connection points in series. Because each connection point may have a certain degree of angular deflection associated with it (e.g. due to an imperfect fit), the total angular deflection between two tubular member increases with the number of connection points between them. This effect compounds with the number of connected tubular members in the resulting assembled structure. Thus, reducing the number of connection points between the connecting portions of the first and second tubular members reduces the compound angular deflection. Reducing the angular deflection associated with the connection helps to maintain the relative positons of the tubular members in the assembly configuration and thus may improve the structural rigidity of the resulting assembled structure. It may also increase the lifetime of the assembly by reducing wear and tear on the connection portions e.g. that may be subjected to increased moment forces when there is relative movement between them that may cause deformation/damage to the connection portions. As such, the direct connection may reduce the chance of failure and/or accidental/undesired disconnection between the tubular members.

The fastening means may be configured to releasably secure the male connection portion to the female connection portion in the assembled configuration. Releasably securing the connection enables a user to disconnect the tubular members if desired. For example, if a user wishes to transport the structural assembly, or put it in storage, then they can release the fastening means and disconnect the tubular members. This provides an advantage over traditional methods, such as welding, for connecting steel/metallic tubular members.

The female connection portion may comprise one or more openings in a sidewall of the second tubular member. The one or more openings may be configured to receive the one or more projections of the male connection portion. Each opening may correspond to or substantially match a respective projection.

The fastening means may be configured to engage the second tubular member and at least one of the one or more projections of the male connection portion. The fastening means may be configured to apply a retaining force between the tubular members, and/or between the second tubular member and at least one of the one or more projections, upon actuation of the fastening means. The fastening means may be configured to cause the one or more projections of the male connection portion to engage the female portion upon actuation of the fastening means. The fastening means may be configured to cause the one or more projections of the male connection portion to engage the one or more openings in the female portion upon actuation of the fastening means. In this way, the fastening means can “pull” the connection portions together to create a tight and secure connection.

The one or more projections may form part of the first tubular member, i.e. be integral with the first tubular member. The one or more projections of the first tubular member may form part of a sidewall of the first tubular member, i.e. be integral with a sidewall. Because the projections may be formed as part of, rather than being connected to, the first tubular member, the direct connection between the first and second tubular members relies on the strength of the tubular members themselves. For example, when the tubular members are steel tubular members, the connection is strong since steel is strong.

The one or more projections may include at least one primary projection and optionally one or more secondary projections. The primary projection may be configured to couple/engage with a portion of the fastening means and receive a retaining force that causes the projections to engage the female connection portion or corresponding openings of the female connection portion. The one or more secondary projections may be spaced apart from the primary projection (e.g. in a transverse direction of the first tubular member) to provide additional strength and rigidity to the connection. The male connection portion may comprise at least two secondary projections, each secondary projection located on an opposing sidewall of the first tubular member. The fastening means may comprise an end-piece. The end-piece may be configured to engage an end of the second tubular member. The end piece may be configured to fit on or over an open end of the second tubular member, or an opening in an end of the second tubular member. The fastening means may comprise a fastener. The fastener may be a threaded fastener. The fastener may be configured to extend through an opening in the end-piece to at least one of the one or more projections. The fastener may be configured to engage the at least one of the one or more projections.

The at least one of the one or more projections of the male connection portion may comprise a threaded hole/portion for receiving the threaded fastener. The at least one of the one or more projections may be the primary projection of the male connection portion.

The fastening means may comprise an insert. The insert may comprise a threaded hole for receiving the threaded fastener. The threaded hole may be configured to receive and threadly engage the threaded fastener. At least one of the one or more projections of the male connection portion may be configured to support/retain the insert in fixed relation to the at least one of the one or more projections. The at least one of the one or more projections may be the primary projection of the male connection portion. The primary projection may comprise a pair of apertures for receiving/supporting the insert, the pair of apertures located in opposing sidewall portions of the primary projection.

At least one of the one or more projections may be substantially hook-shaped. The hook-shaped projection(s) may be configured to receive and engage a sidewall of the female connection portion when in the assembled configuration.

The male connection portion may be located at or form part of an end, or open end, of the first tubular member. The one or more projections may extend from an end of the first tubular member, or a peripheral edge of a sidewall of the first tubular member, e.g. in a longitudinal direction of the first tubular member. At least one of the one or more projections may comprise a transverse slot. The transverse slot may be configured to receive and engage (e.g. frictionally engage provide an interference fit with) a sidewall adjacent the respective opening of the female connection portion when in the assembled configuration. Each of the one or more openings of the female connection portion may be or comprise a slot. Each slot may be substantially tapered to frictionally engage the respective projection upon actuation of the fastening means.

Frictional engagement between the slots and the projections may help to prevent relative movement between the tubular members. This helps to provide structural rigidity to the assembly in an assembled configuration.

The first and second tubular members may be substantially hollow and formed from one or more sidewalls. The first and second tubular members may have a substantially, square or rectangular crosssection. The second tubular member, or at least the female connection portion of the second tubular member, may have any cross-sectional shape (e.g. square, rectangular, polygon, circular, or semi- circular), The first tubular member, or at least the male connection portion of the first tubular member, may have any cross-section comprising at a pair of substantially flat, parallel sidewalls.

The sidewalls may have a width in the range of between substantially 1 mm and 5 mm, or 1 mm and 10 mm. The sidewalls may have a width in the range of between 1 mm and 3 mm.

The male and/or female connection portions may be formed using laser cutting, dye cutting, or any other suitable method. The male connection portion may be formed by cutting directly into the sidewalls of the tubular member.

Cutting directly into the sidewalls to form the male/female connection portion enables projections and/or slots to be formed integrally with the tubular members. Further, a laser cutter can be programmed to repeatedly cut the same pattern, allowing for mass production of the tubular members which can reduce the time and costs associated with manufacturing.

According to a second aspect of the invention, there is provided a method for assembling a structural tubing assembly. The method may be used to assemble the structural tubing assembly of the first aspect of the invention. The method may comprise connecting a/the male connection portion of a/the first tubular member to a/the female connection portion of a/the second tubular member, and releasably securing the connection between the male connection portion and the female connection portion using the fastening means.

Connecting the male connection portion to the female connection portion may comprise engaging (the) one or more projections of the male connection portion with the female connection portion, or (the) one or more openings of the female portion. Connecting the male connection portion to the female connection portion may comprise inserting (the) one or more projections of the male connection portion into one or more corresponding openings in a sidewall of the female connection portion.

Connecting the male connection portion to the female connection portion may comprise sliding the male connection portion relative to the female connection portion, e.g. in a connection direction. Sliding the male connection portion relative to the female connection portion may comprise sliding in a connection direction to engage a transverse slot of at least one of the one or more projections of the male connection portion with a sidewall of the female connection portion adjacent a respective opening of the female connection portion. The connection direction may be substantially parallel to the sidewall of the female connection portion.

Securing the connection between the male and female connection portions using the fastening means may comprise applying a retaining force between the male connection portion and the female connection portion. The retaining force may cause one or more projections of the male connection portion to maintain engagement with one or more corresponding openings in a sidewall of the female connection portion. Applying the retaining force may displace the male connection portion relative to the female connection portion, e.g. in a connection direction that is substantially parallel to the sidewall of the female connection portion. Applying the retaining force may displace the male connection portion relative to the female connection portion in the connection direction to maintain engagement between a transverse slot of at least one of the one or more projections with the sidewall of the female connection portion, and/or maintain engagement between at least one of the one or more projections and a corresponding opening of the female connection portion (which may be or comprise a slot).

Applying the retaining force may comprise actuating a threaded fastener coupled between an end of the second tubular member and a projection of the male connection portion inserted through a corresponding opening in a sidewall of the female connection portion.

Applying the retaining force may comprise positioning an end-piece of the fastening means on or over an end of the second tubular member. Applying the retaining force may further comprise inserting a threaded fastener of the fastening means through an opening in the end piece into the second tubular member. Applying the retaining force may further comprise engaging the threaded fastener with a projection of the male connection portion inserted through a corresponding opening in a sidewall of the female connection portion.

Engaging the threaded fastener with the projection of the male connection portion may comprise engaging the threaded fastener with a threaded opening in the projection. Alternatively or additionally, engaging the threaded fastener with the projection of the male connection portion may comprise engaging the threaded fastener with a threaded opening of an insert of the fastening means that is secured to the projection.

The method may further comprise securing the insert to the projection before connecting the male connection portion to the female connection portion.

According to a third aspect of the present invention, there is provided a structural tubing assembly, as defined in claim 1. Preferred and/or optional features are set out in the dependent claims. The structural tubing assembly of the third aspect may have any of the features described above with respect to the first aspect.

According to a fourth aspect of the present invention, there is provided a structural tubing assembly, as defined in claim 10. Preferred and/or optional features are set out in the dependent claims. The structural tubing assembly of the fourth aspect may have any of the features described above with respect to the first aspect.

Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable sub-combination. Features described in connection with the assembly of the first aspect may have corresponding features definable with respect to the method of the second aspect, and vice versa, and these embodiments are specifically envisaged.

Brief description of the drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view of a structural tubing assembly in accordance with an embodiment of the invention;

Figure 2 shows a perspective view of a male connection portion in accordance with an embodiment;

Figure 3 shows a side view of the male connection portion of figure 2;

Figure 4 shows a schematic side view of a projection of the male connection portion;

Figure 5 shows a female connection portion in accordance with an embodiment;

Figure 6 shows a plan view of the female connection portion of figure 5;

Figures 7a and 7b show schematically how the male connection portion connects to the female connection portion in accordance with an embodiment;

Figure 8 shows a cross-sectional view of the direct connection between the male and female connection portions of figures 2 and 5;

Figures 9a and 9b show exploded views of a fastening means in accordance with an embodiment;

Figures 10a and 10b illustrate how the fastening means of figures 9a and 9b couples to the male connection portion of figure 2;

Figure 11 shows a schematic cross-sectional diagram of the fastening means fitted to an end of a tubular member;

Figure 12 illustrates how the fastening means of figures 9a and 9b couples to an end of a tubular member;

Figure 13 shows a cross-sectional view of first and second tubular members of a structural tubing assembly secured in an assembled configuration in accordance with an embodiment;

Figure 14 shows a method for assembling a structural tubing assembly in accordance with an embodiment;

Figures 15a and 15b show perspective and side views of a male connection portion according to another embodiment;

Figures 16a and 16b show perspective and side views of a male connection portion according to another embodiment;

Figures 17a and 17b show perspective and side views of a male connection portion according to another embodiment; and

Figures 18a and 18b show perspective and side views of a male connection portion according to another embodiment.

Like reference numerals in different Figures may represent like elements. Detailed description

Figure 1 shows a structural tubing assembly 100 according to an embodiment of the invention. The tubing assembly 100 comprises a first tubular member 101, a second tubular member 102, and a fastening means 130. The tubing assembly 100 is shown in a disassembled state. The tubular members 101, 102 are configured to mechanically connect to each other in a releasable manner without the use of an intermediate connector piece, as is common practice in the prior art. The first tubular member 101 has a male connection portion 110, and the second tubular member 102 has a female connection portion 120 configured to receive one or more projections 112 of the male connection portion 110 when assembled. The fastening means 130 is configured to releasably secure the first tubular member 101 to the second tubular member 102 in the assembled configuration. In this way, the first and second tubular members 101, 102 are directly connected together, using the strength of the tubing itself to create a secure rigid connection, as described in more detail below.

In the illustrated embodiment, the tubing assembly 100 comprises a third tubular member 103 configured to connect to the first tubular member 101. In this example, the tube assembly 100 may form a frame of a table or desk when assembled. However, it will be appreciated that in general the tubing assembly 100 may comprise any number of tubular members that may be configured to connect in a variety of configurations required to provide the desired structure when assembled. For example, in the example shown, the first tubular member 101 comprises a further male connection portion 110 that connects to a female connection portion 120 (not visible) of the third tubular member 103, however, in an alternative configuration (not shown) the third tubular portion 103 may instead have a male connection end 110 that connects to a female connection portion 120 of the first or second tubular member 101, 102.

Each tubular member 101, 102 is substantially hollow and comprises a first end 101a, 102a and a second end 101b, 102b. Each tubular member 101, 102 has a longitudinal axis L defined along the length of the tubular member 101, 102 and a transverse axis T substantially normal to the longitudinal axis L (i.e. in a width direction).

According to an embodiment of the invention, the male and female connection portions 110, 120 are integral with the respective tubular member 101, 102, i.e. they are formed from or are part of the respective tubular member 101, 102. The male connection portion 110 is located and/or formed at the first end 101a of the first tubular member 101 (optionally a further male connection portion may be located and/or formed at the second end 101b, as shown). In the illustrated example, the female connection portion 120 is also located and/or formed adjacent the first end 102a of the second tubular member 102. While this may be preferable for securing the first and second tubular members 101, 102 together with the fastening means 130 in certain assembled configurations (e.g. see figure 13), it is not essential. In other configurations (not shown), the female connection portion 120 may instead be located and/or formed at some distance from the first end 102a of the second tubular member 102. Figures 2 and 3 show perspective and side views of a male connection portion 110 according to an embodiment. As described above, a male connection portion 110 may be located at the first end 101a and/or second end 101b of the first tubular member 101. The male connection portion 110 comprises one or more projections 112 that are configured to fit into corresponding openings 122 of the female connection portion 120 of the second tubular member 101 (see figure 4) and engage the corresponding openings 122 upon actuation of the fastening means 130 to secure or lock the first and second tubular members 101, 102 together, described in more detail below.

The one or more projections 112 include at least a primary projection 113 and optionally one or more secondary projections 114. The primary projection 113 is configured to couple/engage with a portion of the fastening means 130 and receive a retaining force that causes the projections 112 to engage the corresponding slots 122. The secondary projection(s) 114 is(are) spaced apart from the primary projection 113 in the transverse direction T to provide additional strength and rigidity to the connection.

In the example shown, the first tubular member 101 has a substantially rectangular cross-section and is formed from four sidewalls 111 that extend in a longitudinal direction L between the first and second ends 101a, 101b and include first and second pairs of opposing sidewalls I l la, 111b (in this case the first pair I l la form the longer sides of the rectangular cross-section). The one or more projections 112 extend from the sidewalls 111 of the first tubular member 101 in a longitudinal direction L, such that they are continuous with and form part of the sidewalls 111. For example, the projection(s) 112 may be formed by cutting or otherwise removing portions of the sidewalls 111 at the first end 101a (or second end 101b). Suitable techniques for forming the male and female connection portions 110, 120 include laser cutting or other cutting processes suitable for cutting predefined shapes from tubing (e.g. saw, blade, milling or thermal-based cutting), stamping and pressing.

Each projection 112 comprises a transverse slot 118 configured to receive and engage a portion of a sidewall 111 of the female connection portion 120 adjacent the corresponding slot 122. The slots 118 of the projections 112 extend in a common connection direction CD with respect to the longitudinal axis L of the first tubular member 101 that defines the connection angle 0 between the first and second tubular members 101, 102 when assembled. For example, the connection angle 0 may be substantially 90 degrees, or some other angle (e.g. in the range of 60 to 120 degrees) depending on the desired structure. In practice, the angle will most commonly be in the range of 80 to 100 degrees for most structures. As such, each projection 112 is substantially hook-shaped when viewed from the side (see figure 3), and defines a connection direction CD. In the example shown the slots 118 are substantially coplanar, and run substantially parallel with a connection plane CP. The width of each slot 118 is configured to substantially correspond to or match the thickness of the sidewall 111 of the second tubular member 102 to provide a tight fit. The width of slots 118 may optionally taper out at the open end 118a of the respective slot 118 to define a lead-in angle <|>, as illustrated in figure 4. This may help guide the portion of sidewall 111 of the female connection portion 120 into the respective slot 118 during assembly. The lead-in angle <|> may generally be in the range 0-5 degrees, or more preferably in the range of 2 to 3 degrees.

In the illustrated embodiment, the male connection portion 110 comprises a primary projection 113 and two secondary projections 114. The primary projection 113 comprises two opposing sidewall portions 113a, 113b connected by an intermediate sidewall portion 113c, in a C-shape. Each opposing sidewall portion 113a, 113b comprises a transverse slot 118, as described above. The opposing sidewall portions 113a, 113b of the primary projection 113 and the secondary projections 114 extend longitudinally from, and form part of, the first pair of opposing sidewalls I l la of the first tubular member 101. The intermediate sidewall portion 113c of the primary projection 113 extends longitudinally from, and forms part of, one of the second pair of opposing sidewalls 111b of the first tubular member 101. The secondary projections 114 are substantially aligned in the transverse direction T (i.e. when viewed from the side as in figure 3). Although a specific embodiment is shown, it will be appreciated that there are a number of alternative configurations of the projections 112 that will achieve the same technical effect. For example, in other embodiments (see figures 15-18, described below), the intermediate sidewall portion 113c of the primary projection 113 may be omitted, or one or both of the opposing sidewall portions 113a, 113b may be omitted depending on how the primary projection 113 is configured to couple to the fastening means 130 (discussed in more detail below). In addition, the secondary projections 114 may be offset in the transverse direction T, or the two secondary projections 114 may be connected by an intermediate sidewall portion (which is formed from the other one of the second pair of opposing sidewalls 111b of the first tubular member 101) in a similar way to the primary projection 113, and/or there may be additional secondary projections 114.

Figure 5 shows a perspective view of a female connection portion 120 of a second tubular member 102 according to an embodiment. The second tubular member 102 also has a substantially rectangular crosssection and is formed from four sidewalls 121 that extend in a longitudinal direction L between the first and second ends 102a, 102b and include first and second pairs of opposing sidewalls 121a, 121b (in this case the first pair 121a form the longer sides of the rectangular cross-section). In the example shown, the cross-section of the first tubular member 101 (defined by sidewalls 111) and the crosssection of the second tubular member 102 (defined by sidewalls 121) are substantially identical, although this is not essential.

The female connection portion 120 comprises one or more openings 122 formed in a sidewall 121 configured to receive the corresponding one or more projections 112 of the male connection portion 110. For example, the opening(s) 122 may be formed by cutting or otherwise removing portions of the sidewall 121. The thickness of the sidewalls 121 of the second tubular member 102 is configured to substantially correspond to or match the width of the transverse slots 118 of the projections 112 of the male connection portion 110. The one or more openings 112 comprises at least a primary opening 123 configured to receive the primary projection 113 and optionally one or more secondary openings 124 configured to receive the one or more secondary projections 114. In the illustrated embodiment, there is a primary opening 123 and two secondary openings 124 formed in one of the first pair of sidewalls 121a to match the arrangement of projections 112 in the male connection portion 110 of figures 2 and 3. However, in general, the number and arrangement of openings 122 in the female connection portion 120 will depend upon, and substantially match, the number and arrangement of projections 112 of the male connection portion 110.

Each opening 122 is or comprises a longitudinal slot that extends in the connection direction CD. For example, with reference to figure 6, the secondary openings 124 are longitudinal slots, and the primary opening 123 comprises two opposing slot portions 123a, 123b and an intermediate opening 123c connecting the two opposing longitudinal slot portions 123a, 123b, to match the primary projection 113 of figures 2 and 3 (the intermediate opening 123c can be omitted where the intermediate sidewall portion 113c is omitted). The width of the slots or slot portions 122 of the female connection portion 120 is configured to substantially correspond to or match the thickness of the sidewalls 111 of the first tubular member 101. In this way, the female connection portion 120 provides a tight and/or interference fit for the male connection portion 110 to minimise relative movement of the first tubular member 110 when assembled.

With reference to figure 6, the width of longitudinal slots 124 and/or slot portions 123a, 123b may be tapered in the connection direction CD to frictionally engage and/or “pinch” the projections 112 when assembled. For example, the taper may reduce the width of the longitudinal slots 124 and/or slot portions 113a, 113b to a value equal to or fractionally less than the thickness of the sidewalls 111 of the first tubular member 101, such that the frictional engagement between the projections 112 and the slots 123a, 123b, 124 increases then the male connection portion 110 is inserted and moved in the connection direction CD. In the embodiment shown, the taper angle q/ is approximately 2 degrees. In other embodiments (not shown), the taper angle q/ may generally be in the range of 0 to 5 degrees, and more preferably, in the range of 2 to 3 degrees. Additionally or alternatively, the longitudinal slots 124 and/or slot portions 123a, 123b may comprise undulations in the width that are configured to grip the projections 112 when assembled.

Figures 7a and 7b show schematically how the first and second tubular members 101, 102 are directly connected together into an assembled configuration. In figure 7a, the projections 112 of the male connection portion 110 are aligned with the openings 122 of the female connection portion 120. The first and second tubular members 101, 102 are then brought together in an insertion direction ID indicated by the arrow so that the projections 112 are received in the openings 122 of the second tubular member 120 and the transverse slots 118 are aligned with the sidewall 121 of the second tubular member 120. Figure 7b shows the projections 112 received in the openings 122 after insertion. After insertion, the first tubular member 101 is then moved relative to the second tubular member 102 in the connection direction CD (indicated by the arrow) such that the slots 118 of the projections 112 receive and slidingly engage a portion of the sidewall 121 of the second tubular member 102. The connection direction CD is substantially parallel to the portion sidewall 121a. This connection movement can continue until the projections 112, or more specifically the (closed) end 118b of the transverse slots 118, abut the sidewall 121 (in some cases, the fastening means 130 may be used/required to move the projections 112 fully into engagement with the sidewall 121, see below). Figure 8 shows how the male connection portion 110 and the female connection portion 120 of figures 2-5 directly connect after the insertion and connection movements. At this point the first and second tubular members 101, 102 are in the assembled configuration and the engagement of the hook-like projections 112 (or more specifically the transverse slots 118) with the sidewall 121 of the female connection portion 120 inhibits disconnection in the reverse insertion direction, e.g. by pulling the male connection portion 110 away from the female connection portion 120. It follows that to disconnect the male and female connection portions 110, 120, the connection steps are reversed, i.e. first one must slide the male connection portion 110 in a reverse connection direction and then remove the male connection portion 110 from the female connection portion 120 in the reverse insertion direction.

With reference to figure 7b, the separation S' between the first pair of opposing sidewalls 121a defines the maximum length / of the projections 112, as measured from the transverse slots 118 to the longitudinally outer edge 112e. The length / of the projections 112 is less than, or equal to, this separation S' in order for the male and female connection portions 110, 120 to connect in the manner described above. In an embodiment, one or more of the projections 112 (primary and/or secondary) may be configured or dimensioned to extend to and contact/abut the other one of first pair of opposing sidewalls 121a when inserted into the openings 122. This may provide a positive feedback to the user of when the male connection portion 110 is fully or correctly inserted into the female connection portion 120, making the connection process easier. Further the abutment of the longitudinally outer edge 112e with the other one of first pair of opposing sidewalls 121a may increase the strength and rigidity of the connection, reducing flex. For example, the longitudinally outer edge 112e of the respective projection 112 can be configured to substantially conform to the other one of the first pair of opposing sidewalls 121a of the second tubular member 102 when in the assembled configuration. This is shown in the embodiment of figures 2, 3 and 8, in which the longitudinally outer edge 113e of the primary projection 113 runs substantially parallel with the slots 118 to match the connection angle 0 and abut the other one of the first pair of opposing sidewalls 121a of the second tubular member 102 when inserted/assembled.

The fastening means 130 is configured to releasably secure or retain the first and second tubular members 101, 102 in the assembled configuration, as explained below. Figures 9a and 9b show exploded views of a fastening means 130 in accordance with an embodiment. The fastening means 130 is configured to engage the second tubular member 102 and the primary projection 113 to apply a retaining force on the primary projection 113 that has at least a component in the connection direction CD. In this way, the fastening means 130 retains the first and second tubular members 101, 102 in the assembled configuration, by pulling them together, and the strength of the tubing material is used to create a strong, tight and rigid connection. In essence, the fastening means 130 secures the connection between the male and female connection portions 110, 120 by preventing the first disconnection step, i.e. the movement of the male connection portion 110 in the reverse connection direction. The fastening means 10 comprises an end-piece 131 and a threaded fastener 132. The end piece 131 is configured to couple to or fit on/in an open end 125 of the second tubular member 102. The threaded fastener 132 is configured to extend through an opening 137 in the end piece 131 into the second tubular member 102 and couple to the primary projection 113 of the male connection portion 110. The threaded fastener 132 can couple to and engage the primary projection 113 either directly or indirectly via an insert 133, such that actuating (rotating/tightening) the threaded fastener 132 exerts a retaining force on the primary projection 113 that pulls it towards the end piece 131. Actuating the fastening means 130 therefore displaces the male connection portion 110 relative to the female connection portion 120 in the connection direction CD to maintain or force engagement of the transverse slots 118 with the sidewall 121. This secures the connection between the male and female connection portions 110, 120 in the assembled configuration.

In the embodiment shown, the threaded fastener 132 comprises a screw with a threaded shaft 132a and a head 132h (sized larger than the opening 137) for actuating/rotating the fastener 132. However, it will be appreciated that any suitable threaded fastener 132 may be used. For example, the threaded fastener 132 may instead comprise threaded bolt (not shown).

The threaded fastener 132 can couple directly to the primary projection 113 via a threaded opening in the projection 113 (not shown) or indirectly via a threaded opening 138 in an insert 133 of the fastening means 130 that is secured to the primary projection 113, as described in more detail below. An example insert 138 of the fastening means 130 is shown in figures 9a and 9b.

With reference to figures 2 and 3, the primary projection 113 comprises one or more openings 116, 117 for receiving a portion of the fastening means 130. In the illustrated embodiments, the insert 133 is a substantially elongate element. The primary projection 113 comprises a pair of apertures 117, one in each opposing sidewall portion 113a, 113b, configured to receive the insert 133. The insert 133 is configured to be inserted into both apertures 117, before the projections 112 are inserted into the openings 122, to support and secure the insert 133 in fixed relation to the primary projection 113. This is illustrated in figures 10a and 10b which show, respectively, the position of the insert 133 before and after insertion into the apertures 117. In figure 10a, the insert 133 is first aligned with the apertures

117. The arrow indicates the direction in which the insert 133 can be inserted between the apertures

117. In figure 10b, the insert 133 is held in place by the apertures 117. The shape of the apertures 117 corresponds to the shape of the insert 133 so that the insert 133 is rigidly secured to the primary projection 113.

Preferably, the apertures 117 are substantially aligned in the transverse T and longitudinal directions such the insert 133 extends substantially perpendicular to the sidewalls I l la of the first tubular member 101. In the example shown, the length of the insert 133 is configured such that its ends lie substantially flush with the exterior surface of the opposing sidewall portion 113a, 113b to avoid interfering with the insertion of the primary projection 113 into the primary opening 123. In other examples (not shown), the insert 133 can protrude from the apertures 117 and the corresponding opening 123 adjusted accordingly.

The threaded opening 138 may extend through the insert 133 to relax the requirements on the length of the threaded shaft 132. In this case the intermediate side wall portion 113c may comprise an opening 116 as shown in figure 2 (which is larger in diameter than the threaded shaft 132) to receive any portion of the threaded shaft that extends through the threaded opening 138.

In the example shown, the insert 133 and the corresponding apertures 117 are substantially rectangular in cross-section to assist in supporting the threaded opening 138 in the correct position and orientation for receiving and engaging the threaded shaft 132. It will be appreciated that the above is only a specific embodiment and that the insert 133 may take different shapes or sizes, and/or may be secured to/supported on the primary projection 113 in variety of different ways and positions. For example, the insert 133 may be secured to the primary projection 113 using adhesive.

In an alternative embodiment (not shown), where the threaded fastener 132 couples directly to the primary projection 113, the opening 116 in the intermediate sidewall portion 113c of the primary projection 133 can be threaded, and the apertures 117 and insert 133 omitted.

Figure 11 shows a schematic cross-sectional diagram of how the end-piece 131 and threaded fastener

132 fit together on the open end 125 of the second tubular member 102 according to an embodiment. The end piece 131 extends at least partially over a peripheral edge 121p of the open end 124 of the second tubular member 102. In this way the end piece abuts the open end 125 of the second tubular member 102. The abutment between the end-piece 131 and the open end 125 of the second tubular member 102 prevents the end-piece 131 from passing through the open end 125 and into the second tubular member 102. This also allows the threaded fastener 132 to apply the retaining force between the primary projection 113 and the end 125 of the second tubular member 102 (via the head 132h and the end piece 131).

In the example shown, the end-piece 131 comprises one or more recesses defining one or more lips 135 or first portions of increased width that extend at least partially over a peripheral edge 12 Ip of the open end 124 of the second tubular member 102. The recess also defines a second portion of reduced width 134 that extends into the open end 125 of the second tubular member 102. The exterior width of second portion 134 may be configured to substantially match the interior width of the open end 125 or the separation S between opposing sidewalls 121 to assist in locating and aligning the end piece 131 and the threaded fastener 132 in the correct position for engaging the threaded opening 138 of the insert

133 (or a threaded opening of the primary projection 133). In other examples, the end-piece 131 may not be recessed.

In other example (not shown), the fastenings means 130 may comprise a plurality of threaded fasteners 132. In this case, the end-piece 131 may comprise a plurality of openings 137 for receiving the threaded fasteners 132 and the insert 133 (or primary projection 113) may comprise a plurality of threaded holes 138 configured to engage with the plurality of threaded fasteners 132.

Figure 12 shows how the fastening means 130 is used to secure the connection between the first tubular member 101 and the second tubular member 102 in the assembled configuration. The male connection portion 110 is first connected to the female connection portion, as shown in figures 7a to 8. The endpiece 131 is then aligned with and coupled/fitted to the open end 125 of the second tubular member 102, as indicated by the arrow. The threaded fastener 132 is inserted through the opening 137 of the end-piece 131 to the threaded opening 138 in the insert 133 and threadly engages the threaded opening 138 by actuating/rotating the threaded fastener 132. Continued actuation of the threaded fastener applies a retaining force between the primary projection 113 of the male connection portion 110 and the end 125 of the second tubular member to secure the connection between the male and female connection portions 110, 120. Figure 13 show a cross-sectional view of the assembly 100 in its assembled configuration.

To disassemble the assembly 100, e.g. after use or for storage or transportation, the fastening means 130 can be readily disengaged by releasing the threaded fastener 132 from the threaded opening 138 in the insert 133 (e.g. rotating it in a counter-clockwise direction). The threaded fastener 132 and endpiece 131 can then be removed from the assembly 100 and the male and female connection portions 110, 120 disconnected as described above.

Figure 14 shows a method 200 for assembling the structural tubing assembly 100 according to an embodiment. In step 201, the insert 133 of the fastening means 130 is aligned with the apertures 117 of primary projection 113, and inserted into the apertures 117 so as to support/retain the insert 133 in fixed relation to the primary projection 113.

In step 202, the first and second tubular members 101, 102 are directly connected. As shown, in figure 7a, the projections 112 of the male connection portion 110 are aligned with the openings 122 of the female connection portion 120. The first and second tubular members 101, 102 are then brought together in an insertion direction ID (indicated by the arrow in figure 7a) so that the projections 112 are received in the openings 122 and the transverse slots 118 are aligned with the sidewall 121 of the second tubular member 120.

In step 203, the first tubular member 101 is moved relative to the second tubular member 102 in the connection direction CD (indicated by the arrow in figure 7b) so that the slots 118 of the projections 112 receive a portion of the sidewall 121 of the second tubular member 102. This movement can continue until the end 118b of the transverse slots 118 abuts the sidewall 121.

In step 204, the fastening means 130 is actuated to secure the connection between the first and second tubular members 101, 102. The end-piece 131 is positioned on the open end 125 of the second tubular member 102 and the threaded fastener 132 is inserted though the opening 137. The threaded fastener 132 then engages the threaded hole 138 of the insert 133 to apply a retaining force between the male connection portion 110 and the end 125 of the second tubular member 102 (by rotating the threaded fastener 132, e.g. in a clock-wise direction), so that the positions of the tubular members 110, 120 are secured in the assembled configuration, as shown in figure 13. The actuation of the fastening means

130 prevents the tubular members 101, 102 moving in the opposite direction to the connection direction CD.

In other embodiments, the order of steps 203 and 204 can be swapped, or the steps can be combined. In such embodiments, the actuation of fastening means 130 causes the first tubular member 101 to move relative to the second tubular member 102 in the connection direction CD so that the slots 118 of the projections 112 receive a portion of the sidewall 121 of the second tubular member 102. As the threaded fastener 132 engages the insert 133, the head 132h of the fastener 132-2 abuts the end-piece

131 which in turn abuts the open end 125 of the second tubular member 102, which causes the relative movement between the tubular members 110, 120 in the connection direction CD.

As described above, the male connection portion 110 and female connection portion 120 can be formed by cutting or otherwise removing portions of the sidewalls 111, 122 of the respective tubular member 101, 102 to form the projection(s) 112 and corresponding opening(s) 122. In an embodiment, the male connection portion 110 and female connection portion 120 are formed using a laser cutting process. However, any suitable method known in the art can be used. Other suitable techniques for forming the male and female connection portions 110, 120 include but are not limited to saw, blade, milling or thermal-based cutting processes, die cutting, stamping and pressing.

The tubular members 101, 102 are formed from a substantially rigid material suitable for forming a substantially rigid and load bearing structure when assembled. In an embodiment, the first tubular member 101 and the second tubular member 102 are formed from or comprise a metal material, such as steel, aluminium or titanium. In other examples where high load capacity is not as critical to the assembled structure, the tubular members 101, 102 can be formed from a plastics or other non-metal material.

As described above, although a specific embodiment of the structural tubing assembly 100 has been described, there a number of alternative configurations, particularly of the projections 112 of the male connection portion 110 (with corresponding openings 122 in the female connection portion 120), that will achieve the same technical effect. To illustrate this point, some alternative embodiments of the male connection portion 110 are shown in figures 15-18 (although not shown, it will be appreciated that the corresponding female connection portion 120 would have corresponding openings 122 to match/receive the projections 113, 114 as described above).

In figures 15a and 15b, the male connection portion 110 is essentially the same as that shown in figure 2 but comprises two sets of secondary projections 114. In figures 16a and 16b, the primary projection 113 the same as that shown in figures 2, but the secondary projections 114 is formed from the first pair of opposing sidewalls I l la and one of the second pair of opposing sidewalls 111b. As such, the secondary projection 113 comprises two opposing sidewall portions 114a, 114b connected by an intermediate sidewall portion 114c, in a C-shape, similar to the primary projection 113 (although the C- shape faces the opposite direction)..

In figures 17a and 17b, the primary projection 113 does not include the opposing sidewall portions 113a, 113b shown in figures 2 and 15. In this case it does not define any slots 118 or include any apertures 117 for supporting an insert 133. In this embodiment, the opening 116 of the primary projection 113 is threaded in order to receive and engage the threaded fastener 132 of the fastening means 130. The engagement between the threaded opening 116 and the threaded fastener 132 can therefore remove the need for the insert 133. In addition, this embodiment comprises two sets of secondary projections 114. The additional set of secondary projections 114 may create a stronger connection between the first and second tubular members 101, 102.

In figures 18a and 18b, the location of the primary projection 113 and the secondary projections 114 are swapped in comparison to the embodiment shown in figures 2 and 3. Other embodiments of the male connection portion 110 may comprise and mixture of the features shown in figures 2 and 15 to 18.

Although the first and second tubular member 101, 102 of the illustrated embodiments have a rectangular cross-section, this is not essential. In general, the second tubular member 102 comprising the female connection portion 120 can have any cross-sectional shape (e.g. square, rectangular, polygon, circular, or semi-circular), and the first tubular member 101 comprising the male connection portion 110 (or at least the male connection portion 110) can also have any cross-sectional shape (which need not be the same cross-sectional shape or size as the second tubular member 102) provided it has at least one pair of substantially flat and parallel opposing sidewalls I l la on which the projections 113, 114 can be formed. The other sidewalls of the first tubular member 101 of the male connection portion 110 can be non-parallel and/or curved. For example, the male connection 110 can be formed from a tubular member 101 with a flat-sided oval cross-section.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub- combination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom. For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.