The present invention relates to coupling systems for joining two tubular members together. The invention relates to display systems, such as shop fittings and racks. The invention finds particular, though not exclusive, application for joining adjacent T-arms that project from a wall or the horizontal members of display racks, which may have a set orientation.

Background of the invention

As far as the applicant is aware, for T-arms that project from a wall, adjacent T-arms are not joined together. Alignment of adjacent T-arms to provide an aesthetically pleasing appearance relies on tight tolerances, such that the adjacent ends of the arms align or may abut against each other. If the tight tolerances are not provided, due to production faults or to connections at the walls being misaligned, misalignment at the meeting points of adjacent arms results. It is also common for arms that align correctly in an unloaded condition to easily become misaligned by uneven loading of the arms.

Various methods of joining rod or tubular members have been devised in the past. A common system involves the provision of joints on the ends of the tubular members, with a spigot and socket arrangement, where the end of one tubular member is inserted into the end of another tubular member. However, this requires tight tolerances, to be provided; otherwise the tubular members can be misaligned or easily slip out of each other. It also requires adjacent tubular members to be paired as spigots and sockets.

Connecting members have been provided that join two tubular members together, which either rely on a frictional fit between components, plastic deformation of at least one of the connecting components, or rotation of one or more of the tubular members. Connecting methods involving friction fit or deformation of components have been observed to be subject to rapid wear and tear, particularly in commercial retail environments, where shop display structures are frequently dismantled and reassembled. Wear and tear on components quickly leads to a deterioration of the connections and leads to loose and unstable displays. Those that require rotation of a tubular member require joining to take place before mounting and cannot be subsequently joined once positioned.

For display racks, particularly those with a circular or curved horizontal member, a single unbroken horizontal member is provided atop two or more vertical uprights. If the horizontal member were to be made from multiple pieces, the joins would most likely be a frictional spigot and socket arrangement. However, as noted above, such connections have drawbacks. Rotation of tubular members would not be possible due to the locked orientation and the inability to rotate a final member in a closed circular arrangement. It is therefore an object of the present invention to provide an alternative coupling system for tubular members used in display systems, such as shop fittings and racks.

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

Summary of the invention

Accordingly, the present invention provides a coupling system for joining together two tubular members, comprising: a joining insert having a body portion and two engagement portions extending oppositely from the body portion; structure on the joining insert that defines a predetermined rotational alignment relative to at least one of respective components engageable by the engagement portions; and one or more formations on the joining insert engageable with complementary formations on said components whereby the joining insert has an engaged position and a disengaged position and movement between the two positions is effected by rotation of the joining insert relative to said components.

The coupling system may further include one or more socket plugs comprising said components having a passage into which a said engagement portion is receivable, wherein the or each socket plug is shaped to be inserted into an open end of a tubular member.

The or each socket plug may have an insertion opening leading into the aforesaid passage. Advantageously, the or each socket plug has at least one formation in said passage complementary to said at least one formation on the joining insert, to engage the joining insert when inserted within the socket plugs and rotated into the engaged position.

The one or more formations on the joining insert may comprise a plurality of peripherally spaced lugs at or adjacent an end of the engagement portion.

The complementary formations in the passage of the or each socket plug are advantageously opposed lands, preferably including shoulders, behind which the lugs of the joining insert engage, when rotated into the engaged position.

The rotation from the disengaged position to the engaged position, and vice-versa, is preferably a substantially 90° rotation. Advantageously, the 90° rotation can only be actioned in one direction to engage and the opposite direction to disengage. In one embodiment, the aforesaid structure comprises a cavity in each end of the joining insert, preferably extending the length of the engagement portion, although it will be appreciated that the cavity may be provided by a passage that continues through the body portion to the engagement portion at the opposite end. The cavity at a first end of the joining insert may have an insertion opening with a profile, e.g. a figure 8, shaped to define surfaces that set limits to the extent of relative rotation of the joining insert. The passage of the or each socket plug may be closed at the end opposite the insertion opening with a rear wall. In this embodiment, the rear wall includes a central projection, projecting into the passage, to an edge spaced from the aforementioned lands. This central projection may be dimensioned to correspond to the surfaces defined by the aforesaid profile. When this first end of the joining insert is slid into one of the socket plugs, the two protrusions must align to be inserted between the corresponding shoulders and the profile thereon must be in the correct orientation to align with the central projection, otherwise full insertion of the joining insert is prevented. These two features combined mean that the joining insert can only be inserted in a predetermined orientation.

It therefore follows that in the above embodiment, the first end of the joining insert is first inserted into a socket plug, the second end is then inserted into another socket plug, and then the central body portion is rotated into the engaged position, only being allowed to rotate in one direction due to the profiled cavity. The protrusions engage behind the lands and the joining insert locks the two tubular members together. Rotation of the joining insert in the opposite direction into the disengaged position then allows for the disengagement of the two tubular members. It is preferable that both ends of the joining insert are fully inserted within the socket plugs before the central body portion is rotated, preventing the need to rotate a tubular member with respect to the joining insert. Indeed, in many cases, such as T-arms attached to a wall, or horizontal members on a rack, the tubular members are unable to rotate as their orientation is already locked. Each tubular member may include a socket plug on one or both ends. The socket plugs are preferably held within the open sockets of the tubular members by a pin passing through the tubular members and into the socket plugs, preventing rotation of the socket plugs relative to the tubular members.

The tubular members may be straight or curved along their length. Advantageously, the socket plugs have a distal end and a proximal end, where the distal end is inserted into the open socket of the tubular members and the proximal end at least partly projects out of the end of the open socket. The proximal end preferably includes an upward projection or stopper. The open socket may include a cut-out in the upper side of the tubular member that the stopper may slot within, ensuring correct orientation of the socket plug. The stopper can also act to prevent items held on the tubular member from sliding off the end of the tubular member when not joined to another tubular member. The central body portion of the joining insert may also include a projection. The insert projection preferably projects at right angles to the two opposing stoppers on the joining insert. When in the disengaged position, the insert projection preferably projects at 90° to the plug stoppers; when rotated 90° into the engaged position the insert projection preferably aligns with the plug stoppers.

As used herein, except where the context requires otherwise the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude other additives, components, integers or steps.

Brief description of the drawings

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an isometric exploded view of a coupling system, according to an embodiment of the present invention, joining two tubular members together;

Figure 2 is an isometric view of two tubular members being joined together using the coupling system of Figure 1 , with the joining insert in a disengaged position;

Figure 3 is a view similar to Figure 2, with the joining insert in an engaged position; Figure 4 is an isometric view of a display rack having a pair of curved horizontal tubular members joined by the coupling system depicted in Figures 1 to 3;

Figure 5 is an isometric view of a display . rack having a semi-circular rail formed of two horizontal tubular members joined by the coupling system depicted in Figures 1 to 3;

Figure 6 is a front view of two adjacent misaligned T-arms; Figure 7 is a front view of the adjacent T-arms of Figure 6 joined by the coupling system depicted in Figures 1 to 3;

Figure 8 is an isometric view of the joined T-arms shown in Figure 7;

Figure 9 is an isometric view from one end of a joining insert, forming part of the coupling system;

Figure 10 is an isometric view from the other end of the joining insert;

Figure 11 is a first end view of a socket plug;

Figure 12 is an axial cross-sectional view of the socket plug of Figure 1 ; and

Figure 13 is a sectioned isometric view of the socket plug shown in Figures 10 and 12. Detailed description of embodiments of the invention

A coupling system 10 is shown in the drawings for joining together two tubular members 12. As shown in Figures 4 and 5, tubular members 12 may be part of a rack display, raised off the ground by vertical uprights 14. Alternatively, the tubular members 12 may be the crosspieces of T-arms 13 suspended in a cantilever fashion from a wall (Figures 6 to 8). Each T-arm 13 has a projecting tubular arm 16 to complete the T. The tubular members 12 may be straight or curved.

The tubular members 12 have open socket ends 18 into which general cylindrical socket plugs 20 are inserted and held in place with respective pins 22 that project through a hole 23 in the wall 24 of the tubular member 12 into matching aperture 26 in the base 28 of the socket plug 20. (Figures 12 and 13). Typically, the tubular members are installed so that pin hole 23 is on the underside in situ. Pins 22 are ribbed and press fitted in to hold the components in place. The pins 22 also prevent the socket plugs 20 from rotating with respect to the tubular members 12. A socket plug 20 is typically fitted to both ends of each tubular member 12, however it will be appreciated that one end may not be required to join to another tubular member 12 and therefore may not include a socket plug.

The socket plugs 20 have an axially distal end 30 and a proximal end 32. The distal end 30 is inserted into the open socket 18. A small flat peripheral lip 34 at the proximal end 32 abuts the end of the tubular member 12 and so lies just outside the tubular member, as can be seen in Figures 2 and 3. Peripheral rib 34 is dimensioned so that its outer surface is flush with the outer surface of the respective tubular member 12. The proximal end 32 also includes an integral radially upward fin-like stopper 36, which slots into and projects through a cut-out 38 (Figure 1) in the wall of the tubular member 12 diametrically opposite pin hole 23. This assists in ensuring correct orientation of the socket plug 20 relative to the tubular member 12, with the stopper 36 also acting to hold items on the tubular member and prevent them from slipping off an un-joined end, or onto an adjoining tubular member.

The socket plugs 20 each have an insertion opening 42 at their proximal end 32 leading into an axially extending passage 44.

The coupling system 10 further includes a joining insert 46. The joining insert is of integral, generally tubular longitudinal form with a circular cross-section. The joining insert 46 has a central cylindrical body portion 48, with engagement portions, in this case plug portions 50, 52, projecting axially oppositely from the body portion 48. The plug portions 50, 52 are engageable with tubular members 12 by being inserted into the insertion openings 42 of respective socket plugs and positioned within the passages 44. The joining insert 46 has an engaged position, shown in Figure 3, and a disengaged position, shown in Figure 2: movement between the two positions is effected by rotation of the joining insert 46 relative to the two tubular members 12. The inner end of each of the plug portions 50, 52 includes two diametrically opposite arcuate lugs 54. Each socket plug 20 also includes formations 56 on the side wall of the passage 44, complementary to the lugs 54. As shown in Figure 13, formations 56 comprise two opposing shoulders that project inwardly from the side wall of the passage 44, dimensioned and positioned so that the lugs 54 can engage behind the lands 56 in the engaged position, preventing removal, but can also pass the lands when the insert is in the disengaged position. The joining insert ^' 46 is inserted into the passage 44 with the lugs 54 aligned to pass between the lands 56. Rotation of the joining insert 46 by 90° from the disengaged position to the engaged position locks the protrusions behind the shoulders 56. To disengage the joining insert 46, the joining insert 46 must be rotated 90° in the opposite direction so that the lugs 54 misalign with the lands 56, allowing them to slide out between them.

The central cylindrical body portion 48 also includes an external radial projection 58 of rectangular cross-section. When the joining insert 46 is in the disengaged position, as shown in Figures 1 and 2, the projection 58 projects at right angles to the stoppers 36, i.e. is circumferentially displaced by 90° from the stoppers. Rotation of the joining insert by 90° into the engaged position, as shown in Figure 3, aligns the projection 58 between the stoppers 36: the projection 58 is dimensioned to register with the stoppers so that the three components form a contiguous structure 59. The projection 58 is used to effect the rotation as it can be engaged by fingers or by a thumb, with an index finger engaged with a stopper 36 such that the thumb can be pulled towards the index finger, squeezing the projection 58 towards the stoppers 36.

The joining insert 46 has a central bore or passage that provides respective co-axial cavities 60, 62 at the ends of the respective plug portions 50, 52. The cavity 60 in plug portion 50 is generally circular, whilst the other cavity 62 in plug portion 52 has a figure 8 profile in cross-section, as shown best in Figure 10. The figure 8 is created by a cylinder 64 having two opposed rectangular ribs 66. As shown in Figures 11, 12 and 13, each socket plug 20 includes diametrical wall 68 from which a central projection 70 extends into the passage 44. The central projection 70 is rectangular, having a height greater than its width such that it extends diametrically aligned and co-planar with the orientation of the respective stopper, as shown in Figures 11 and 13, being a generally vertical orientation in situ. As can be seen from Figure 12, the central projection 70 does not extend axially as far as the lands 56, providing a region 72 where the lugs 54 sit when engaged. The central projection 70 has a width that corresponds to the distance between parallel side faces 74 of the ribs 66 in cavity 62. This means that the joining inserts 46 can only be inserted in an orientation with the projection 58 extending sideways so that the lugs 54 line up between the lands 56 and the side faces 74 will align with the central protrusion 70 when fully inserted. Due to the figure 8 shaped cavity 62, the joining insert 46 can thereafter only be rotated in one direction, in the illustration being anti-clockwise to move into the engaged position, in which the projection 70 aligns with the other side faces 75 of the ribs 66. To disengage, the joining insert 46 must be rotated 90° in the opposite, clockwise direction, to allow the joining insert to be removed, and the two connected tubular members 12 separated. Side faces 74, 75 comprise surfaces that set limits to the extent of relative rotation of the joining insert.

It will be appreciated that the figure 8 cavity 62 provides structure on the joining insert 46 that defines a predetermined rotational alignment relative to one or both of the tubular members 12. It will further be appreciated that lugs 54 constitute formations on the joining insert engageable with lands 56 on the socket plugs 20 whereby the joining insert has an engaged position and a disengaged position and movement between the two positions is effected by rotation of the joining insert relative to the socket plugs 20 and tubular members 12.

An advantage of the present invention over prior art coupling systems is that a joining insert is rotated relative to both tubular members 12, rather than having to rotate one or both of the tubular members, which would be impossible for tubular members with locked orientations, such as in the application of the present invention. Due to the locked orientation of the tubular members, both ends of the joining insert 46 must be fully inserted before it can be rotated into the engaged position. As shown by Figures 6 to 8, the coupling system of the present invention provides a solution in instances where two adjacent tubular members misalign, causing an aesthetically unpleasing result in a retail environment. The coupling system according to the present invention can be easily utilised to join the two tubular members together, creating a seamless display assembly.

As shown in Figures 4 and 5, for display racks there is no longer a need to provide the horizontal member as a single tubular member, which can be quite limiting and take up large amounts of storage and transport space. Indeed the invention allows much greater flexibility, as a multitude of tubular members 12 can be coupled together to create a variety of different display rack configurations.