FIELD OF THE INVENTION
The present invention generally relates to space frame structures, utilizing hollow
octagonal nodal connectors and intermediate tubular members. More particularly
the invention relates to an easily attachable and detachable multi-application
space frame node connector device for joining tubular members.
BACKGROUND OF THE INVENTION
Prior art Patent Publications US 3632147, US 6672789, GB 2197417 A, teach
various types of space frame node connector, each having different interlocking
arrangement, several configurations, typical assembly sequences, a plurality type
of material compositions, and operational limitations. The main disadvantages of
these prior art node connector devices are that they involve too many
complicated components which make the assembly/disassembly of space frame
structure too time consuming. Further, the prior art node connectors are not
sufficiently versatile for use in different types of structures.
The closest prior art to the present invention according to the inventors, is the
invention disclosed in Patent No. GB 2197417 A issued to Lawrence Paul.
Nevertheless, the prior art disclose a variety of structural systems having
connectors and auxiliary members which can be assembled to form different
space frame configurations. In prior art, a connector generally is a polyhedron
and spherical in shape. The tubular members are mated to a plurality of
mounting hole, by using plug or mandrel or cap member. The prior art
configurations suffer fresh major constraints due to presence of threaded
mounting holes (openings). This results in stress concentration near the
openings. Such connecting areas are vulnerable to tensile failure constituting
rigid joints between the connectors and auxiliary members of different sizes and
shapes. In contrast, threaded mounting holes get loosened-up when the joints
are subjected to axial load and wind load. Accordingly, the threaded openings
are considered as a major obstacle for efficient assembly. Lack of versatility in
relationship among the auxiliary members and the connectors; appear to result
into lack of dimensional stability when assembled in case of threaded mounting
holes. Therefore, the present inventors noted that use of threadless mounting
holes shall overcome the prior art disadvantages for example lack of dimensional
stability of the structure when assembled with threaded mounting holes.
Threading in the mounting holes of the joint increases shear stress. Threaded
joints are weak in shear. A threaded mounting hole also increases the cost of the
joint that is not economical and is unsafe too.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an easily attachable
and detachable multi-application space frame node connector device for joining
tubular members.
Another object of the invention is to propose an easily attachable and detachable
multi-application space frame node connector device for joining tubular
members, which constitutes an octagonal shaped node connector.
Another object of this new joint configuration is designed to take care of the
forces and moments. The joint between the tubular members of the space frame
structure is a hollow octagonal shaped joint. External forces and reactions forces
are considered to act only at the nodes and result in reduced forces in the
members which are either tensile or compressive forces. Moments (torques) are
explicitly excluded.
A further object of the invention is to propose an easily attachable and
detachable multi-application space frame device for joining tubular members,
which is configured with prefabricated sections for easy and economic handling.
SUMMARY OF THE INVENTION
Accordingly, there is provided an easily attachable and detachable multi-
application space frame device for joining tubular members, comprising a hollow
octagonal node connector, a plurality of tubular members, and a plurality of
mandrels. The Octagonal node connector having sixteen tangent planes of
sixteen quadrilaterals with eight mounting holes with included angles of 0° to
45°, and placed respectively at the alternating centers of the quadrilaterals.
The connector connects a plurality of space frame tubular members coming from
various directions in space to meet at a node, the plurality of space frame
tubular members are connected to the connector so as to lie in respective
relatively orthogonal planes by means of the joint, wherein
a first eight square tangent planes are composed of four diametrically
opposed openings, the axis of which all lies in a first plane being normal
to said axis of said body,
- a second eight trapezoidal tangent planes composed of four diametrically
opposed openings, the axis of which all lies in a first plane being normal
to said axis of said body,
- each of said openings projecting inwardly from the surface of the node
connector device body towards the centre of the body, and
- each of said openings being drilled without thread to mate with the
tubular members along a plurality of corresponding mandrels via fastening
and resilience means.
The connecting technique in accordance with the present invention simplifies the
construction of the connecting members including the process of manufacture of
the space frame node connector device.
In this case which is important for the practical utilization of the invention, each
joint element which satisfies all the requirements of space frame can be
assembled in extremely simple and fast manner. When the space frame is
configured in accordance with the present invention, it provides a significant
advantage especially a considerably simplified production process of the joint
elements and tubular members as well as an easy mounting procedure. When a
joint element is produced with eight connecting members, only one hollow
octagonal joint is needed. Each Octagonal joint with eight openings are needed.
After drilling of eight through openings in each hollow octagonal joint, the
individual joint element is ready for mounting The invention will be best
understood from the following description of specific embodiments when read in
connection with the accompanying drawings.
The result of the Finite element analysis for deflection and stresses obtained
according to the parameters of the selected members of the invention are
indicated in Table 2. Table - 2 shows that the stresses and deflections are
maintained at an acceptable limit.
BRIEF DESCRIPTION OF THE ACCOMPAYING DRAWINGS AND TABLES
The accompanied drawings describe the invention in detail and illustrate the
features, aspects, and advantages of the present invention. Reference numerals
are used for locating the component of the device. The invention may be readily
understood and carried into practical effect based on the following description
taken in conjunction with the accompanying drawings, wherein:
Figure 1 shows disposition of an octagonal node connector in a space frame
structure in accordance with one embodiment of the invention. Frame members
of space frame structure are connected into the intermediate openings of the
node connector 1 to provide either 0° or 45° diagonals.
Figure 2 shows an enlarged view of portion marked 'A' of the space frame
structure of Figure 1 which is in pyramid shape. Figure 3 shows detail of the
node connector of Figure 2, with the tubular members in assembled way.
Figure 3 (i) presents an exploded isometric front view of the device.
Figure 3 (ii) shows an exploded perspective view of the device of Figure 3(i).
Figure 3 (iii) shows an exploded isometric bottom view of the device of the
invention.
Figure 3 (iv) shows an exploded top view of the device of the invention.
Figure 3 (v) shows an exploded orthographic bottom view of the device of the
invention.
Figure 4 shows an isometric view of a tubular frame member of the inventive
device, in which cross-section of the tubular member with front, top, side view is
clearly visible.
Figure 5 shows an octagonal node connector, which is having eight mounting
holes, along with mandrel, nut and bolt.
Figure 6 shows a sectional plan view taken along the lines C-C of a front view of
the device specifically including an interior view of a node connector.
Table - 1 shows the technical difference of the present invention with the prior
art devices.
Table - 2 shows the result of the finite element analysis on acceptable limit of
stress and deflecting of the structural members.
Table - 3 shows the detailed components with technical specification of the
inventive device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows location of an octagonal node connector device in the space
frame structure in accordance with a preferred embodiment of the invention.
Here, the node connector and the tubular members are connected in series
consecutively. Front view of the space frame structure is shown in figure 1. The
hollow octagonal node connector device is disposed among the tubular members
of the space frame structure.
Figure 2 shows an enlarged view of portion 'A' of Figure 1. The hollow octagonal
node connector device (1), inclined tubular members (2) and horizontal tubular
members (3) can easily be constructed into any desired configuration. The
inclined tubular members (2) and horizontal tubular members (3) shown in
Figure 2 are connected into a plurality of intermediate openings of the hollow
octagonal node connector device (1) to act as 0° to 45° diagonals. Horizontal
tubular members (3) are mated to the node connector (1) at 0° while the
inclined tubular members (2) are mated at a maximum of 45°*. Node connector
and structural tubular frame member assembly looks like a pyramid shape.
Detail view of the node connector (1) enlarged and showed by different angles
in the Figures 3i, 3ii, 3iii, 3iv, 3v.
Figure 3 shows in detail the hollow octagonal node connector device (1) of
Figure 2. This consists of the inclined tubular members (2) and the horizontal
tubular members (3). The tubular members (2 and 3) protruding towards outside
from the octagonal node connector (1). The tubular members (2 and 3) hold two
plates (2d and 3d) and two springs (2c and 3c) at their both ends.
Figure 3(i) shows an exploded isometric front view of the hollow octagonal node
connector device (1). As shown in Figure 3(i), connector (1) is an octagonal body
having eight openings on its surface extending radially inwardly towards the
centre of the body. The surface of the connector (1) is formed from sixteen flat
surfaces each corresponding to a respective alternate opening in the
connector (1) . Each of these surfaces is normal to the axis of its respective
opening and thus provides an octagonal shape to the connector (1).
Figure 3(ii) shows eight openings and thus sixteen surfaces and these mounting
holes (eight openings) are provided on the alternating surfaces. These holes are
purely drilled and unthreaded. Inclined tubular members (2) and horizontal
tubular members (3) are exploded in their respective direction along with their
components. Furthermore, Figure 3(ii) shows a perspective exploded view of the
detail of Figure 3(i) and illustrates how the tubular frame members (2 and 3) are
connected to the hollow octagonal node connector (1). Inclined tubular member
(2) having components 2a, 2b, 2c, 2d, 2e, 2f and horizontal tubular members (3)
having parts 3a, 3b, 3c, 3d, 3e, 3f. Mounting holes are denoted by '2f' and '3f', in
which '2f' mounting holes corresponds to the Inclined tubular members (2) and
'3f' mounting holes corresponds to the horizontal tubular members. Mandrels are
represented by '2a' and '3a' and Bolts by '2b' and '3b', Springs by '2c' and '3c,
plates by '2d' and '3d', Nuts by '2e' and '3e'. Inclined tubular members (2) are
having smaller size diameter compared to the horizontal tubular members (3). So
the corresponding components for example mandrel '2a', bolt '2b', spring
'2c', plate 'd', nut '2e', mounting holes '2f are having smaller diameter when
compared to the corresponding components 3a, 3b, 3c, 3d, 3e, 3f of the
horizontal tubular members (3). Mandrels ('2a' and '3a') are complementary
(paired or mated or corresponding) part for the opening in the hollow octagonal
node connector (1). Since, in the preferred embodiment, the openings i.e.
mounting holes ('2f' and '3f') are simply drilled, the Mandrels (2a' and 3a') are
then simply mated to the mounting holes ('2f and '3f') in the hollow octagonal
node connector (1) with the help of nut ('2e' and '3e') and bolt ('2b and '3b').
The Mandrels ('2a' and '3a') are designed in such a way that it can received the
bolt, springs and the tubular frame members . The tubular frame members ('2'
and '3') are hollow pipes, which are cylindrical in shape. There is a diametrically
opposite opening for the square surface's mounting holes (3f) in the hollow
octagonal node connector (1). Thus, each such openings and the respective
opposed openings form a diametrically opposed pair of openings whose axis
passes through the centre of the hollow octagonal node connector (1). The
mandrel ('2a' and '3a') are securely locked in position by a fixed nut with a set
screw abutting a node joint.
Referring to Figure 3(ii) Hollow octagonal node connectors (1) consist of sixteen
tangent surfaces. In which, eight tangent planes (P) are formed in the shape of
the square surfaces and remaining eight tangent planes (Q) of the trapezoidal
surfaces. These surfaces connected among the side lines of the eight
quadrilateral tangent planes, and with mounting holes ('2f' and '3f') disposed
respectively at the centers of the tangent planes of the squares (P) and the
trapezoidal (Q) to make each hollow octagonal node connector (1) to have eight
mounting holes ('2f' and '3f') with included angles pointing at different directions
not only to increase the application of a single octagonal connector (1), but also
to comply with the needs of specific application by making variations of different
degrees of mounting angles. Figure 3(ii) shows the tubular frame members
(2 and 3), which are to be welded to the mandrels ('2a' and '3a'). Accordingly,
fillet welding is done in the gap between the periphery (circumference) of the
tubular frame members (2 and 3) and the mandrels ('2a' and '3a'). These
mandrels ('2a' and '3a') are interlocked with the mounting holes ('2f and '3f) via
fastening of the nut ('2e' and '3e') and bolt ('2b' and '3b') in the hollow octagonal
node connector (1). This configuration meets its structural need and to increase
the connection strength among all the tubular frame members (2 and 3). The
bolt ('2b' and '3b') are placed into the mounting holes ('2P and '3f') to finish the
connection among the tubular frame members ( 2 and 3) and the mounting
holes ('2f' and '3f') of the octagonal connector (1).
Figure 3 (iii) displays the hollow shape of the octagonal node connector (1). Nut
(2e and 3e) can also be seen in this view. Nut (3e) is having bigger dimension
rather than nut 2e. These nuts (2e and 3e) are fastened or screwed or tightened
to the mandrels via bolts (2b and 3b).
The openings i.e. mounting holes ('2f' and '3f') showed in Figure 3(iv) are called
axial openings. Spaced around the circumference of the connector (1), around
the center of the octagon, it has eight alternating openings. Four mounting hole
openings (3f) are one alternating faces of the square tangent surfaces (P), and
four mounting hole openings (2f) are on alternating faces of the trapezoidal
tangent surfaces (Q). Larger size mandrels (3a) are fixed on the mounting hole
openings (3f) alternating faces of the square tangent surfaces (P) and smaller
size mandrels (2a) are fixed on the mounting hole openings (2f) are on
alternating faces of the trapezoidal tangent surfaces (Q). Each mounting hole
openings (2f and 3f) has a corresponding paired diametrically opposed opening.
The axes of these opposed pairs of openings, hereafter called the central
openings.
Figure 3(v) shows exploded bottom view of the assembly. Where quantity of
each components are very clearly visible. This view presents each and every
component in detail. Each component is in four quantities.
For assembly of the horizontal tubular member or the inclined tubular member to
corresponding mounting holes, the circular member plate ('26' or '3') is welded
inside the tubular member on both sides. Now the spring and bolt are inserted
inside the mandrel and the mandrel is welded to the tubes. Now the mandrel is
placed over the octagonal node connector on the respective mounting holes
surfaces and then the bolt is inserted into the mounting holes. The Mandrel rests
on the flat surface of the Octagonal joint. The bolt is adjusted into the mounting
holes and locked by nut from inside the Octagonal joint. Adjustment is preferably
achieved using a spanner engaging a hexagonal nut associated with the shank of
the bolt. This arrangement for connecting tubular member to node connector is
very specific arrangement.
Figure 4 shows isometric view of the tubular frame members (connecting pipe)
along with the spring and plate. Section A-A renders interior cross section of the
tubular member. Section B-B shows a circular cross section of the tubular frame
members.
Figure 5 shows isometric front view of the octagonal node connector. Mounting
holes are shown on the respective surfaces. Along with this, one more figure of
octagonal node connector is shown, in which mandrel is mounted on the
mounting holes via nut, bolt.
Figure 6 shows a cutting plane taken along the lines C-C. This view shows the
axial opening ('2f' and '3f') and the opposed pairs of central openings. Also, as
shown therein, the axes of these openings pass through the center of the
connector (1), with the annular spacing between the adjacent axes always being
45°-.
The foregoing detailed description of the invention, renders significance that an
infinite variety of and strong space frame structures can be constructed using
only one form of connector, mandrels arrangement and standard lengths of
tubular frame members. The shapes of the squares and the trapezoidal of the
tangent planes of the mounting holes enable the unskilled user to quickly
recognize the place of the desired mounting holes to increase the accuracy and
usefulness of the assembly.
WE CLAIM:
1. An easily attachable and detachable multi-application space frame device
node connector for joining tubular members comprising a hollow
octagonal node connector, a plurality of tubular members, and a plurality
of mandrels. The Octagonal node connector having sixteen tangent planes
of sixteen quadrilaterals with eight mounting holes with included angles of
0° to 45°, and placed respectively at the alternating centers of the
quadrilaterals, the connector connects a plurality of space frame tubular
members coming from various directions in space to meet at the node,
the plurality of space frame tubular members are connected to the
connector so as to lie in respective relatively orthogonal planes by means
of the joint, wherein
- a first eight square tangent planes are composed of four diametrically
opposed openings, the axis of which all lies in a first plane being normal
to said axis of said body,
- a second eight trapezoidal tangent planes composed of four diametrically
opposed openings, the centre of said second openings being substantially
parallel to said first plane,
- each of said openings projecting inwardly from the surface of the device
body towards the centre of the body, and
- each of said openings being drilled without thread to mate with the
tubular members along a plurality of corresponding mandrels via fastening
and resilience means.
2. The device as claimed in claim 1, wherein the inclined and horizontal
tubular frame members comprises a plurality of components for example
at least one each mandrel, bolt, nut, spring and mounting holes, and
wherein diameter of each component of the horizontal member is larger
than that of the inclined member.
3. The device as claimed in claim 1 or 2, wherein the tubular frame members
are hollow pipes with cylindrical shape.
4. The device as claimed in any of the preceding claims wherein the tubular
frame members are welded to the mandrels and wherein the mandrels are
releasable attached to the octagonal node connector by means of bolts,
nuts and springs to the mounting holes.
5. The device as claimed in claim 1, wherein the device exhibits a pyramid
configuration.
6. An easily attachable and detachable multi-application space frame node
connector device for joining tubular members substantially as herein
described and illustrated with reference to the accompanying drawings.

The invention relates to a node connector device in space frame structure. The
points at which tubular members come together are called nodes or nodal points
which are connectors capable of accommodating multiple elements coming
together at different angles. There are many nodal connector systems in use.
The connector may be in various shapes like spherical, ellipsoidal, cylindrical,
octahedron and tetrahedron. This invention employs a hollow octagonal node
connector for space frame structure. Hollow Octagonal node connector consists
of sixteen tangent planes of sixteen quadrilaterals with eight mounting holes with
included angles of 0° to 45° based on height, placed respectively at the
alternating centers of the quadrilaterals. The joint connects a plurality of tubular
members coming from various directions in space to meet at a node. The
plurality of space frame tubular members are connected together so as to lie in
respective relatively orthogonal planes by means of the joint. Each space frame
tubular member and the connector assembly is provided in series. Hollow
octagonal node connector formed into a square tangent surfaces and trapezoidal
surfaces with mounting holes. The mounting holes are through drilled holes.
Mounting holes are totally free from the internal threading. These mounting
holes are drilled for receiving a connecting tubular member with the help of
fasteners. The assembled device exhibits a pyramid shape.