GB2152174A - Sectional structure - Google Patents

Abstract

A sectional structure comprises a plurality of bars (1) and a plurality of joints (2). These latter mainly consist of a cubic body (3) whose center area is hollow and communicates with each of the six faces by way of respective clearance holes (7). Three of such clearance holes (7) extend through shanks (6) of the body (3) located on three adjacent faces and are arranged to receive the heads of screws (8) whose shanks are screwed into an anchoring element (10) located inside the bars (1). The anchoring elements (10) are fixed inside the bars (1) at a distance not less than the height of the shanks (6) from the ends of the bars (1). <IMAGE>

Description

SPECIFICATION Improvements in or relating to sectional structures The present invention relates to section structure, for instance supporting electrical or electronic apparatus.

The circuits and devices needed for the implementation of electrical or electronic systems are usually located inside cubicles that perform the double function of support and protection. Such cubicles must be mechanically sturdy since, for safety reasons, they are usually required to be able to stand relevant stresses, including bursts or explosions, which might occur in electric energy distribution systems owing to possible short-circuits. In order to provide the necessary mechanical sturdiness, such cubicles are usually provided by a metallic structure which is covered with panels anchored to the structure.

Since such cubicles may be required in a wide range of sizes, the metallic structure is usually obtained by assembling together a plurality of elementary pieces such as bars which are provided by soldering and bending or iron or steel sheets. The bars are generally connected together at a joint which, for reasons of weight and ease of working, is usually made in die-cast aluminimum. Aluminium has a specific gravity sufficiently low to keep down the weight of the joints and consequently of the whole structure and may also be worked easily by die-casting.

In known structures, the connection of the joints to the bars is provided by screws whose heads are inserted into recesses provided in the bars and whose shanks are screwed into threaded holes in the body of the joint. In particular, the bars usually have a polygonal section and each bar is fixed to the joint by two screws located at diametrically opposite points of the polygonal section. Thus a fair distribution of the prestress force deriving from the rightening of the two screws is obtained throughout the entire contact surface between the bars and relative supports provided on the joints.

A structure of this type has the disadvantage that assembly requires a long time since the connection of each bar with the joint involves the tightening of two screws. Further, this structure allows a small number of assembly-disassembly operations; in fact, the threaded holes are provided in an aluminium body whose resistance to the wear is much lower than that of the steel of the screws and, consequently, after some assembly-disassembly operations, the thread deteriorates to a degree such as to render the connection no longer reliable.

According to the invention, there is provided a sectional structure comprising a plurality of bars joined by screws to a plurality of joints, each of which comprises a substantially cubic body, wherein each three faces of the body defining a trihedron angle has a shank of shape complementary to the inner profile of the bars, the cubic body having at its middle a cavity which communicates with each of the six faces via a respective clearance hole, the clearance holes which commicate with the faces of the public body provided with the shanks having a diameter not less than that of the shanks of the screws and, at the end adjacent the cavity, having an enlarged diameter so as to provide a seat for receiving the heads of the screws, the structure further comprising anchorage elements each provided with a threaded hole arranged to receive the shank of a respective one of the screws, each anchorage element being fixed inside a respective one of the bars at a distance from the end of the bar not less than the height of the shanks.

It is thus possible to provide a sectional structure which requires a short time for assembly and which allows a much higher number of assembly-disassembly operations than for known structures.

A preferred embodiment comprises bars linked by way of joints. Each bar is associated with respective face of the joint through a screw whose head is pressed against the joint and whose shank is designed to be screwed to an anchorage element, eg realized in steel, integral with the bar. Thus, the connection requires the screwing of a single screw whose axis is substantially coincident with that of the bar and consequently a single crew allows an even distribution of the prestress force while ensuring a better resistance to wear of the threading.

Such a structure thus requires halve the assembly times in comparison with known structures and allows a large number of assembly-disassembly operations to be performed without incurring in the aforesaid wear.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the structure constituting a preferred embodiment of the invention; Figure 2 illustrates a joint 2 and bars 1 of Figure 1 in more detail; and Figure 3 shows a section of one of the joints 2 of Figure 1 together with a view of another joint.

The structure of Figure 1 comprises a plurality of bars 1 and a plurality of joints 2. The joints mainly comprise a cubic body 3 whose size coincides with the external size of the transverse section of the bars 1. Three faces of the cubic body 3 defining a trihedron angle are coupled, via means illustrated in detail in Figures 2 and 3, to as many bars 1.

One of the remaining three faces is ar ranged to receive the shank of feet 4 designed to be for instance applied to the faces of the cubic body that face downwardly, or the shank of devices 5 arranged to allow the hoisting of the structure and designed to be applied on the faces of the cubic body that face upwardly. Figure 2 shows in detail one of the joints 2 together with and positions of two bars 1. This figure illustrates the faces of the joint destined to be joined to the bars 1 and hence the faces each have a shank 6 whose profile coincides with the inner profile of the bars 1.

The axis of each of these three faces coincides with the axis of a respective hole 7 which is arranged to receive the shank of a screw 8, whose head is allocated in a cavity inside the cubic body as indicated in the following description of Figure 3. The screw 8 has a length such that a large portion thereof comes out from the free face of the shanks and its movement along the axis is reduced on one side by the head and on the other side by an elastic ring 9; the said ring is coupled to the screw when a structure is assembled.

This ring prevents the screw from coming out from its seat before or during an assembly operation.

The structure also has anchorage element, eg comprising a plate 10 whose shape coincides with the inner profile of the bars 1. The plates 10 are inserted inside the bars and fixed thereto, eg by soldering, at a distance from the ends not less than the height of the shanks 6 of the cubic body. Each plate 10 has a threaded hole 11 arranged to receive the shank of the respective screw 8, the center of the hole coinciding with the axis of the respective bar 1.

In an alternative embodiment, the plates 10 are coupled to the bars 1 via at least a pair of shoulders 1 2 illustrated by way of example in the vertical bar of Figure 2. The shoulders 12 may be formed by way of as many drawings effected on at least two opposite angles or corners of the bars and structured so as to provide a flat surface in coincidence with the area of contact with the plate 10.

According to a further embodiment, the flat surfaces of shoulders 1 2 each have a hole 1 3 arranged to receive a respective tooth 14 of the plate 10. The use of shoulders requires a change in the profile of the shanks 6 which require two chamfered angles (not illustrated) so as to receive the shoulders of the bars.

The connection of the joints 2 to the bars 1 provides the coupling of the ends of the bars 1 with the shanks 6 which are structured so as to determine the correct position displacement of the bars and consequently, after the coupling, the axis of the screw 8 coincides with the axis of the holes 11 provided on the anchorage plate. The screw 8 is then screwed sufficiently far into the hole 11 so that any slack between the end of bar 1 and the respective face of cubic body 3 is taken up and so that the contact therebetween is provided with a prestress force deriving from the full tightening of the screw. Such a prestress force is evenly distributed along the whole contact surface between the bar 1 and the cubic body 3 since the tractive force provided by the screw is applied on the axis of the bar 1.

Figure 2 also shows recesses 1 5 in the shanks 6 for receiving the shanks of screws designed to be screwed into threaded holes 1 6 provided in the bars 1. Such screws have for instance the task of performing the tightening of panels, when the structure is provided for the implementation of cubicles.

Figure 3 illustrates the section of one of the joints 1 as well as a view of a second joint. As shown in the section, the center of the cubic body coincides with the center of a cavity 1 7 which communicates, via the holes 7, with each face of the cubic body. In particular, the holes communicating with the faces equipped with the shanks 6 have a diameter suitable for receiving the shanks of the screws 8 and in coincidence with the end facing the cavity 1 7, a diameter which is enlarged so as to create a seat 18 arranged to receive the head of the screw.

The holes communicating with the remaining three faces each have a diameter not less than the diameter of the screw heads and sufficiently large to allow the passage of the shank of a tool to allow screwing of the shank of the feet 4 or of the shank of the devices 5 for hoisting of the structure (see Figure 1).

The faces of the joint 2 not provided with the shank 6 have a further threaded hole 1 9 which is aligned, in the assembled structure, with the holes 1 6 in the bars 1 in order to render possible, for instance, the anchorage of panels on both the bars 1 and the joints 2.

Such an arrangement has advantages with regard to the speed and practicality of the assembly. The joining of a single screw may be performed by means of a tool that is easily handled owing to the fact that during such an operation its shank is perpendicular to the structure with the handgrip opposite thereto.

Furthermore, such a structure sets no limits to the number of assemblydisassembly operations which it is able to stand if the plate 10 is of steel.

Claims (11)

1. A sectional structure comprising a plurality of bars joined by screws to a plurality of joints, each of which comprises a substantially cubic body, wherein each of three faces of the body defining a trihedron angle has a shank of shape complementary to the inner profile of the bars, the cubic body having at its middle a cavity which communicates with each of the six faces via a respective clearance hole, the clearance holes which communicate with the faces of the cubic body provided with the shanks having a diameter not less than that of the shanks of the screws and, at the end adjacent the cavity, having an enlarged diameter so as to provide a seat for receiving the heads of the screws, the structure further comprising anchorage elements each provided with a threaded hole arranged to receive the shank of a respective one of the screws, each anchorage element being fixed inside a respective one of the bars at a distance from the ends of the bar not less than the height of the shanks.

2. A structure as claimed in claim, in which each threaded hole has an axis coinciding with the axis of the respective bar.

3. A structure as claimed in claim 1 or 2, in which at least one of the holes communicating with the faces of the cubic body not equipped with the shanks is threaded.

4. A structure as claimed in any one of the preceding claims, in which the joints are provided with recesses in the shanks at positions aligned with the axes of a plurality of holes provided in the sides of the bars.

5. A structure as claimed in any one of the preceding claims 4, in which the joints are provided with further threaded holes in the faces of the cubic body not having the shanks, each further threaded hole having an axis passing through the intersection of a line extending through the centres of holes provided in horizontal ones of the bars, and of the prolongation of the connection line of holes provided in vertical ones of the bars.

6. A structure as claimed in any one of the preceding claims, in which an elastic ring is located on part of the shank of each of the screws projecting out of the shanks on the body.

7. A structure as claimed in any one of the preceding claims, in which each of the anchorage elements comprises a plate which is fixed to the respective bar by soldering.

8. A structure as claimed in any one of the preceding claims 4, in which each of anchorage elements rests on a pair of shoulders provided inside the respective bar at a distance from the end of the bar not less than the height of the shanks of the cubic body.

9. A structure as claimed in claim 8, in which the shoulders are provided by drawing at at least two opposite angles of the bars, shaped so as to provide a flat surface perpendicular to the axis of the bars.

1 0. A structure as claimed in claim 8 or 9, in each of the shoulders is provided with a hole for receiving a respective tooth of the anchorage element.

11. A sectional structure substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.