The present invention relates to a truss device comprising a set of elongate tube bodies which extend parallel to each other in a longitudinal direction and which are connected spatially separated from each other by bars, wherein the tube bodies are provided or at least can be provided at opposite outer ends with coupling means for a releasable coupling to a tube body of a further truss device.

Such a truss device is usually referred to as truss and is generally used to construct a temporary, semipermanent or permanent structure thereby, for instance in the context of stage construction and/or set construction. A number of such truss devices is here mutually connected, to each other and optionally via corner elements, by means of manually arrangeable and releasable couplings. The thus formed construction frequently functions as mounting base for technical installations, such as spotlights and loudspeakers, and for erecting optionally temporary support structures and walls.

A known truss is for instance described in European patent application EPl 884 605.

This describes three parallel tube bodies which are mutually connected by means of a system of cylindrical bars. At their outer ends the tube bodies have cups whereby a connection can be brought about to a corresponding cup at an outer end of a further truss via a fitting two-sided wedge part. For manufacturing such trusses use is usually made of aluminium parts, both in respect of the tube bodies and the bars. The parts are usually welded together manually and thus assembled into the final truss device.

A drawback of the known truss is that manufacture thereof requires skill and craftsmanship, particularly in respect of the many welded connections which must be realized manually around the bars and which are time-consuming and vulnerable for this reason, among others.

The present invention has for its object, among others, to provide a truss device of the type described in the preamble which can be produced in significantly simpler manner and which is more suitable for robotization for this reason, among others.

In order to achieve the stated object a truss device of the type described in the preamble has the feature according to the invention that the bars have a polygonal cross-section and are connected to an adjacent tube body along an at least in projection linear connection which coincides with a side of this cross-section at an end surface, and that the connections of a number of bars connected to the tube body lie mutually in line.

By thus making use of essentially straight connections, instead of curved ones as with the bars of the known truss, which moreover lie in one line, the connections between the bars and the tube bodies can be arranged in one or more essentially linear, smooth motions. Not only does this require less skill on the part of a skilled person, this process can also be robotized more readily. In a particular embodiment a motion system (robot) with a freedom of movement over just four axes can particularly suffice for welding of such a truss device. For welding of the round bars of the known truss device driving over six axes is conversely required to enable the bars to be welded all around.

Owing to the solely and at least in projection linear connections according to the invention, more space is also available for manipulation of a welding torch or the like in order to physically realize the connection(s) internally, inside the truss device. All this has the result not only that manufacture of the truss device requires less craftsmanship manually but moreover that, both manually and fully automated, production can take place more rapidly, reliably and partly for this reason at lower manufacturing costs.

A preferred embodiment of the truss device has the feature that the bars are connected to the set of tube bodies at opposite end surfaces along at least in projection linear connections, which each coincide with a side of the cross-section of the bar in question, and that corresponding connections of the bars lie mutually in line. The bars are here connected to a tube body of the set of tube bodies in corresponding manner at both outer ends.

A particular embodiment of the truss device has the feature here according to the invention that the bars are each connected to a tube body of the set of tube bodies along respectively a first at least in projection linear connection and a second at least in projection linear connection, wherein the first connections of the bars lie mutually in line, wherein the second connections of the bars lie mutually in line and wherein the first and second connections are oriented parallel to each other. Because the connections of respectively the first bar and the second bar lie mutually in line here, the relevant connections can be realized one after the other in a relatively smooth run. This applies to both the first connections and to the second connections over which the bars are connected to the tube body. Because they are oriented parallel to each other, a connection can if desired be realized on both sides of the bar in the same run, this saving costly time and operations. The first connections and the second connections are here preferably oriented parallel to the longitudinal direction of the tube body.

Although bars with any random wholly or partially polygonal cross-section can be applied in principle, a further particular embodiment of the truss device has the feature according to the invention that the bars have a rectangular, particularly square, cross-section. A rectangular or square cross-section has the advantage that the peripheral edges thereof can be reached along three orthogonal axes. Use can be made here of solid bars, although a further preferred embodiment of the truss device has the feature according to the invention that the bars comprises hollow tubular profiles. Not only do hollow tubular profiles result in a weight saving and lower material costs while strength is maintained, such bars can also be heat-welded more readily in that heat dissipation will be lower therein.

In a further preferred embodiment the truss device is characterized according to the invention in that the tube bodies and the bars are formed from the same material, particularly from metal such as steel or aluminium, and are connected to each other at least substantially only along linear connections. These linear connections can be arranged by machine in relatively simple manner by adhesion or welding in mechanical, particularly robotic, manner. With a view to an increased bending stability and strength a further preferred embodiment of the truss device has the feature here according to the invention that the tube bodies are connected in crosswise manner by means of the bars.

A further particular embodiment of the truss device is characterized in that the tube bodies are received in a shared end frame at their end surface and that the tube bodies and the end frame are connected to each other along at least one further at least in projection linear connection, which at least one further connection is oriented parallel to a connection along which at least one of the bars is connected to one of the tube bodies, and particularly lies in line therewith. Such end frames have a dual function. During manufacture the tube bodies are thereby held and fixed at the correct mutual distance and position. Once all the parts have been mutually connected, the end frames moreover impart an improved transverse strength, torsional stiffness and stability to the device. Likewise embodying the connection to the end frames parallel or even in line with those of the bars enables this connection to be realized in a collective processing run in relatively simple manner.

In a further preferred embodiment the truss device is furthermore characterized here in that the bars are each connected to a tube body of the set of tube bodies along respectively a first at least in projection linear connection and a second at least in projection linear connection, wherein the first connections and the second connections of the bars each lie in line with a further at least in projection linear connection of the end frame to the tube body, and wherein the first, second and further connections are oriented parallel to each other. The connection of the end frames can thus likewise be realized on both sides in a similar practical manner as applied for the bars themselves.

A further preferred embodiment of the truss device has in this latter respect the feature according to the invention that the tube bodies and the end frames are formed from the same metal, particularly from aluminium, and are welded to each other at least substantially by means of solely and at least in projection linear connections. The construction of end frames, tube bodies and bars can thus be wholly assembled with a motion system along just four axes. This results, particularly in respect of robotization, in a significant simplification and saving relative to the robot system needed previously.

In a particular embodiment the truss device is characterized in that the end frames are formed integrally in monolithic manner, and were particularly obtained by extrusion or casting. Such monolithic parts which are solid to greater or lesser extent have been found in practice to be highly suitable for the relative lateral positioning of the tube bodies and impart a particularly great deal of stability to the whole. A tangible stop, which moreover imparts a correct axial position to the tube bodies, is here preferably provided between each of the tube bodies and the end frame. The invention will now be further elucidated with reference to an exemplary embodiment and an associated drawing. In the drawing:

Figure lis an isometric view of an exemplary embodiment of a truss device according to the invention;

Figure 2 is a cross-section along the line X-X of the truss device of figure 1; and

Figure Sis a front view of the truss device of figure 1.

It is otherwise noted here that the figures are purely schematic and not always drawn to (the same) scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral.

Figure 1 shows an exemplary embodiment of a truss device, also referred to as truss, according to the invention in an isometric view. The device comprises four tube bodies 10 which extend axially parallel to each other and lie at the corner points of a virtual square in cross-section. The tube bodies are provided at their opposite outer ends with coupling means 20 in the form of cups having a conical form internally. Received in the cups is a coupling body, which is not shown but is assumed sufficiently known to a skilled person, which has on either side a complementary conical form externally and whereby a rigid and reliable coupling to a corresponding outer end of a further lattice body can be realized.

The tube bodies 10 and the cups 20 are both formed wholly from aluminium, although other materials are also suitable instead, particularly metals such as steel or plastics, particularly Fiber Reinforced Plastics. Tube bodies 10 are received at their outer end in end frames 30 which impart not only additional stiffness, strength and stability to the final product, but already align and fix the tube bodies 10 precisely relative to each other laterally during production. A tangible stop can optionally be provided here between the tube bodies and the end frames in order to impart a correct positioning in axial direction as well. Figure 3 shows such an end frame 30 further in a front view of the truss device. Use is made for this of a monolithic, solid aluminium body which was for instance obtained by extrusion or was moulded.

For an integral strength and particularly bending stiffness of the truss device the tube bodies are connected to each other in crosswise manner by means of a system of bars 40. According to the invention, use is made here of bars 40 with a polygonal cross-section so that a connection between a bar 40 and an adjacent tube body 10 can be realized on one or more straight peripheral sides thereof. In this case use is for this purpose made for bars 40 of substantially rectangular tubular bodies 40, see figure 2. These are welded at their outer ends to the adjacent tube body over one or more sides of their polygonal cross-section along solely linear connections.

Examples of such connections are shown in the figure for the purpose of illustration by means of broken lines 1,11,111, wherein the transverse connections transversely of the longitudinal direction of the lattice body follow the curve of a tube body 10 but are nevertheless linear in projection. Instead of a welded connection it is otherwise also possible to opt for an adhesion between bars 40 and tube bodies 10, this depending on the raw material of the bars and the tube bodies.

As shown in the figures with the lines I, the connections along which the welded connection of adjacent bars 40 are realized lie mutually in line in axial direction. In this example the welded connection between an end frame 30 and the tube body 10 likewise lies on the same line I. Owing to the linearity of the mutual welds between the different parts of the truss device, and particularly between the bars and the tube bodies, the lattice body can be machine-produced in relatively simple manner. This applies all the more so if the welded connections between successive bars extend parallel in the same direction or, as in this case, even lie mutually in line on one line I. It is thus particularly simpler to largely robotize the production process in that a motion system alongjust four axes suffices for carrying a welding torch along all peripheral edges of the bars 40 in order to realize a reliable linear weld there.

Although the invention has been further elucidated above with reference to only a single exemplary embodiment, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person with ordinary skill in the art.