Connector for a framework structure

A connector having a main body and a first group of at least four projections which extend outwardly from the body in a common plane. A second group of at least four projections extend outwardly from the body at an angle of between 15.degree. and 75.degree. to the aforesaid plane and preferably at a 45.degree. angle to the said plane. The projections of each group are equi-angularly spaced about an axis normal to the plane and the projections of the second group are angularly staggered by half the angle between adjacent projections of the first group about the axis relative to the projections of the first group. Each projection is of non-circular, and preferably triangular, cross-section and the body and projections are made of non-flexible plastics material. Such connectors are used to connect together elongate members having tubular ends to form a framework structure.

BACKGROUND OF THE PRESENT INVENTION 
This invention relates to connectors of a type suitable for connecting 
together elongate members to form a framework structure which may be used, 
for example, as a display structure or a framework structure. 
SUMMARY OF THE PRESENT INVENTION 
According to one aspect of the invention, there is provided a first group 
of at least four projections extending outwardly from a main body, and are 
equi-angularly spaced about an axis normal to a plane parallel to the 
direction in which each projection of the first group extends from the 
main body, and a second group of at least four projections extending 
outwardly from the main body and being equi-angularly spaced about the 
axis, the projections of the second group each extending at between 
15.degree. and 75.degree., and preferably at 45.degree. or substantially 
45.degree., to the aforesaid plane. 
Preferably each projection is of non-circular cross-section. 
Preferably, there is an equal number of projections in the first and second 
groups and the projections of the second group are angularly staggered by 
half the angle between adjacent projections of the first group about the 
axis relative to the projections of the first group. 
Conveniently, the main body includes a cylindrical or substantially 
cylindrical surface portion from which the first group of projections 
extend and a partial spherical or substantially spherical end portion 
adjoining the cylindrical portion and from which the second group of 
projections extend. 
Advantageously, each projection is of triangular or substantially 
triangular cross-section. In this case, preferably, a flat or a 
substantially flat portion is provided at the junction between each pair 
of adjacent sides of each triangular or substantially triangular 
projection. 
Conveniently, the projections and body of the connector are made of 
non-flexible plastics material. 
According to a second aspect of the invention there is provided a framework 
structure including a plurality of elongate members having a tubular shape 
at least at their ends. The plurality of elongate members are 
interconnected by connectors according to the first aspect of the 
invention. 
Preferably, the elongate members are tubes and are made of deformable 
plastics material.

Referring to FIGS. 1 through 4 of the drawings, the connector shown therein 
includes a body part 10 having a cylindrical surface portion 12 and a 
part-spherical end portion 14 which adjoins the cylindrical surface 
portion 12. The other end portion of the body part will be referred to 
later. A first group of four projections 16 extend outwardly from the 
cylindrical surface portion 12 and are equi-angularly spaced about an axis 
18 of the cylindrical surface portion 12. The projections 16 extend in a 
common plane which is normal to the axis 18. A second group of four 
projections 20 extend outwardly from the part-spherical end portion 14 of 
the body part 10. These projections 20 are also equi-angularly spaced 
about the axis 18 but are angularly staggered by 45.degree. about this 
axis relative to the projections 16. Also the projections 20 extend at an 
angle of between 15.degree. and 75.degree., and preferably at 45.degree., 
to the common plane. 
Each projection 16 or 20 is of non-circular cross-section and ideally is of 
substantially triangular cross-section as shown. Each projection 16 or 20 
has a flat 22 at the junction between each pair of sides. Each flat 22 may 
be slightly convex. 
Each projection has two sides 24 of equal length and a side 26 of shorter 
length. Each side 26 has a concave recess. 
The other end of the connector is provided with an axially inwardly 
extending annular groove 28 (see FIG. 2) which may receive the end of a 
tube serving as a vertical support column. As shown this other end of the 
connector is also provided with an integral, hexagonal nut 30. 
The connector is conveniently formed from non-flexible plastics material, 
such as that sold by I.C.I. under the Trademark `Noryl`. 
A plurality of such connectors can be used to connect together elongate 
members in the form of deformable plastics cylindrical tubes 32 (see FIG. 
4) to form a space frame which may be used, for example, as a display 
stand. In order to locate a tube 32 on a projection 16 or 20, an end of 
the tube 32 is deformed, by hand pressure, is pushed over the projection 
and is then released. The inner wall of the tube is engaged by each of the 
three flats 22 of the projection as an interference fit (see FIG. 3). 
In the above embodiment the projections are described as being of 
non-circular cross-section and while this is highly desirable, it is 
conceivable that they could be of circular cross-section. 
Instead of the tubes 32, solid rods, with cylindrical deformable plastics 
sockets at each end, could be used. 
The connectors and tubes described above could be scaled down for use as a 
toy or an architect's model. 
If desired, the tubes 32 could be heat welded to the projections 16 or 20 
in order to provide a permanent installation or, if the tubes 32 and 
connectors are of the same material, the tubes may be secured to the 
projections of the connectors by adhesive. 
Moreover, the partially spherical end portion may have grooves formed 
therein, each groove joining a diametrically opposite pair of projections 
16 and acting in conjunction with the concave recesses in the sides 26 of 
the associated projections 16 as a location for a cable which can run 
through the tubes. 
What is claimed as novel is as follows: