GB2236373A

GB2236373A - A node for a recticular structure

Info

Publication number: GB2236373A
Application number: GB9017623A
Authority: GB
Inventors: Astigarraga Galfarsoro
Original assignee: Ulma SCL
Current assignee: Ulma SCL
Priority date: 1989-09-11
Filing date: 1990-08-10
Publication date: 1991-04-03
Also published as: NL9001803A; ES2014944A6; DE4021602C2; FR2651821A1; DE4021602A1; GB9017623D0; BE1005032A5; CH681556A5; PT95244A

Abstract

A nodal joint, for coupling to a pole (1) several longitudinal spars (6), is formed as a ring (2), fixed to the pole and shaped as a double cone, defining two facing grooves (3, 3') on which acts a clamp (7, 8) on the end of each spar (6). Each clamp consists of a fixed jaw (7) on the spar (6) and a mobile jaw (8) which is coupled to the fixed jaw and may be locked in a closed position by means of a wedge (11). This joint is especially suited for use in scaffolding structures. <IMAGE>

Description

1 NODE FOR-A RETICULAR 9TRUCTURE The present invention relates to a nodal

joint for a reticular structure between a pole, which may be upright, and a spar, the joint being fully dismantable i.e. the various elements of the structure may be easily disassembled to reduce to a minimum the volume occupied by the structure when not in use, such as during storage or transport thereof.

The joint described is specially suited for use in three dimensional reticular structures such as scaffolding.

Multiple solutions have been suggested for establishing a reticular structure of the type described above and specifically for providing the nodal joints.

Such solutions use tubular poles of 3 to 4 m in height, provided with axial coupling means, the tubes including distributed evenly therealong, at a distance of approximately 50 cm, a plurality of rings which are coupled by welding to the pole and are cup-shaped such that the end of a transverse extension at the end of a spar may be locked within a ring. A simple coupling of this type is insufficient for ensuring suitable stability of the structure, for which reason on each pole and in correspondence with each of the fixed rings, there is provided a displaceable ring, similar to the former ring but with a facing concavity, and is capable of receiving therewithin another end of the transverse extension of the spar which meets at the pole to form a node, but with the special characteristic that this displaceable ring has an edge located along an imaginary helical line, such that when the ring turns, and with the helical edge resting on a fixed abutment integral with the pole, the ring is axially displaced and locked with respect to the fixed ring, the transverse extension of the spar being located therebetween thereby being rigidly coupled to the pole.

2 The problems derived from this solution are essentially centred on two aspects, on the one hand that coupling at a certain node is common for all of the spar tubes, such that if it should for any reason be necessary to disassemble one of them the remainder are necessarily freed as well which may influence very negatively the stability of the structure as a whole, to which must further be added that a plurality of fixed rings, displaceable rings and abutments are distributed along each pole most of which are inactive and therefore involve unnecessary cost.

In an attempt to solve such problems, solutions such as the German 'llayherll system are known, wherein each vertical pole is provided, as a substitute to the bowl- is shaped rings provided in the previous case, with flat rings having a circumferential line of windows, such that the ring receives the ends of the spars which are provided with transverse slits for coupling to the disc-like flat ring, in addition to a vertical through aperture for definitive locking thereof by means of respective bolts.

This solution although allowing the poles and spars to be individually removed with minimum risk to the structure as a whole has as a disadvantage the fact that couplings of the spars to the pole, at the nodal zone, are predef ined by the location of the apertures on the flat ring, such that the spars may only be coupled at angles therebetween of 900 or 450, no other arrangement being possible.

In an attempt to solve this problem, the 11plettac11 system is known wherein rings fitted to the vertical pole are again used, similar to those of ES-A-429836, but with the special characteristic that the ends of the spars adopt a hook-like configuration which may be coupled to the bowl defined by the respective fixed ring and definitively coupled to the ring by means of bolts. This solution which allows any direction for the spars, and likewise allows a widely varying number of spars to converge on one common node, although it conveniently stiffens the spars 3 transversely with respect to the pole, as well as in a vertically and downward direction, does not offer safe coupling in the event of significant impacts or stresses in a vertically upward direction on the spars since disassembly from the ring is comparatively easy especially if the bolt is loose or if the lower end thereof should be accidentally acted-upon.

In accordance with the invention, a nodal joint, for a reticular structure, between a substantially cylindrical pole and an end of at least one spar, comprises a ring encircling the pole and constituted by two cup shaped sectors diverging from a central waist of smallest diameter, at which the ring is f ixed to the pole, to provide two annular grooves between the inner walls of the sectors and the outer wall of the pole; and a clamp on the end of the or each spar, the clamp being formed by a pair of jaws, which are arranged to be received in respective ones of the grooves, one of the jaws being f ixed to the spar and the other being movable towards and away from the one jaw and being provided with locking means for locking the movable jaw in a closed position relatively to the fixed jaw so that the clamp grips the ring with the spar extending transversely from the pole.

The movable jaw may be pivotable relatively to the fixed jaw.

The jaws are preferably curved complementarily to the curvature of the grooves.

The angular extent of the jaws of the clamp, as seen axially along the pole may vary, being of 900 when it is foreseen that only four spars should meet on one node, or narrower in order to allow coupling of a larger number of spars on one node. Thus in general, the jaws may each occupy one nth of the circumferential extent of the grooves, where n is an integer between 2 and 8 whereby a corresponding number of similar spars can be coupled to the pole at the joint.

4 The locking means may comprise a bolt or wedge which is arranged to extend through windows in the two jaws.

When locking means is a wedge, it may have at its narrower end a projection which may be withdrawn through the window in the movable jaw, but not through the window of the fixed jaw so that the wedge is captive by the fixed jaw.

In the accompanying drawings:

Figure 1 is a side elevation, partly in section, of a nodal joint in accordance with the' invention, wherein two facing spars meet at the node; Figure 2 is a plan of the assembly of Figure 1 but with only one spar shown and wherein the fixed ring of the pole is capable of receiving four beams or spars arranged is at right angles to each other; and, Figure 3 is a plan similar to that of Figure 2, but wherein the node receives six spars through tapering of the clamps andlor enlargement of the ring coupled to the pole.

As illustrated a conventional vertical pole 1 which may have a standard length of 3 to 4 m, has, evenly distributed therealong, a plurality of rings 2fixed thereto by welding. Each of the rings is formed by two facing cup-shaped sectors which diverge from a waist such that each ring 2 forms with the pole two annular grooves 3,39.

For rigidly coupling each ring 2 to the pole 1, apertures 4, are provided around the waist of the ring for receiving weld material 5.

As a'coinplement thereto a clamp is established at the' fastening end of each spar 6, the clamp consisting of a fixed jaw 7 and a mobile jaw 8 both of which have a curved edge 9,91 capable of tight coupling within respective ones of the grooves 3,3#. The - mobile jaw 8, is articulately coupled to the f ixed jaw 7 by means of a transverse bolt 10 such that the jaw tends to drop to an open position through the simple effect of gravity. which aids coupling between the parts making up the node. The closed position is achieved with the aid of a wedge 11 which extends through a window 12 in the fixed jaw 7. and likewise through a further window 13 outwardly of the tilting axis 8. The wedge includes an projection 14. at its free end which, whilst allowing full extraction of the wedge with respect to the mobile jaw 8 prevents separation from the fixed jaw 7, thereby preventing accidental loss of the wedge, as would often happen if the wedge 11 were to be totally independent of the clamp.

It can be deduced from the foregoing that the radial orientation 15 of the clamp 7,8, and therefore of the corresponding spar 6 may adopt any position with respect to the pole 1, without this in any way affecting the rigidity of the coupling of the spar to the pole, the spars may be individually dismantled, without any other spars at the same node being affected.

6

Claims

1. A nodal joint, f or a reticular structure, between a substantially cylindrical pole and an end of at least one spar, the joint comprising a ring encircling the pole and constituted by two cup shaped sectors diverging from a central waist of smallest diameter, at which the ring is fixed to the pole, to provide two annular grooves between the inner walls of the sectors and the outer wall of the 10 pole; and a clamp on the end of the or each spar, the clamp being formed by a pair of jaws, which.are arranged to be received in respective ones of the grooves, one of the jaws being fixed to the spar and the other being movable towards and away from the one jaw and being provided with locking is means for locking the movable jaw in a closed position relatively to the fixed jaw so that the clamp grips the ring with the spar extending transversely from the pole.

2. A joint according to claim 1, in which the movable jaw is pivotable relatively to the fixed jaw.

3. A joint according to claim or claim 2, in which the jaws are curved complementarily to the curvature of the grooves.

4. A joint according to any one of the preceding claims, in which the locking means comprises a bolt or wedge which is arranged to extend through windows in the two jaws.

5.- A joint according to claim 4, in which the locking means is a wedge having at its narrower end a projection which may be withdrawn through the window in the movable jaw. but not through the window of the fixed jaw so that the wedge is captive by the fixed jaw.

6. A joint according to any one of the preceding claims, in which the jaws each occupy one nth of the 7 circumferential extent of the grooves, where n is an integer between 2 and 8 whereby a corresponding number of similar spars can be coupled to the pole at the joint.

7. A joint according to any one of the preceding claims, wherein the ring is provided around its waist with a plurality of apertures which are filled with weld material to fix the ring to the pole.

8. A nodal joint for a reticular structure, substantially as described with reference to the accompanying drawings.

Published 1991 atThe Patent Office. State House, 66171 High Holborn. UndonWC I R 47P. Further copies may be obtained from Sales Branch. Unit 6, Nine Mile Point Cwmfelinfach. Cross Keys. Nrt NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.