Ceiling framework

Abstract

A ceiling framework includes main beams and cross beams, which are connected to one another and transversally to one another by connectors borne by one type of beams among the main beams and the cross beams, and engaged in apertures made in the other type of beams among the main beams and the cross beams, so as to receive tiles. For each beam having the apertures, the apertures are marked with symbols on each face of the beam, the symbols marked on each face being repeated sequentially over the length of the beam, the period of the sequences of symbols on each face being equal to a given tile size. The marking is the same on either face of the beam, starting with the same symbol on each left-hand or right-hand end for each observed face.

Claims

1. A ceiling framework comprising: main beams and cross beams, which are connected to one another and transversally to one another by connectors borne by one type of beams among the main beams and the cross beams, and engaged in apertures made in the other type of beams among the main beams and the cross beams, so as to receive tiles, wherein, for each beam having the apertures, the apertures are marked with symbols on each face of the beam, the symbols marked on each face being repeated sequentially over a length of the beam, a period of a sequence of the symbols on each face spans a size of one tile of the tiles, and each of the apertures in a length of the beam corresponding to the period is marked with a different one of the symbols for each observed face, and wherein the symbols are the same on either face of the beam, starting with a same symbol on each left-hand or right-hand end for each observed face.

2. The ceiling framework as claimed in claim 1, wherein the apertures are made in the main beams.

3. The ceiling framework as claimed in claim 1, wherein a spacing between two identical symbols of two contiguous sequences is equal to the size of the one tile.

4. The ceiling framework as claimed in claim 1, wherein each beam having the apertures has various sequences of symbols, and periods of the various sequences span various tile sizes.

5. The ceiling framework as claimed in claim 1, wherein the symbols are marked by engraving or inkjet printing.

6. The ceiling framework as claimed in claim 1, wherein the symbols are numbers.

7. The ceiling framework as claimed in claim 1, wherein, for each beam having the apertures, the apertures on one face of the beam are marked with a repeating sequence 1, 2, 3, 4, 5, 6/ . . . /1, 2, 3, 4, 5, 6 from left to right, and when the beam is rotated through 180° about a vertical axis passing through its center, the same repeating sequence 1, 2, 3, 4, 5, 6/ . . . /1, 2, 3, 4, 5, 6 is marked from left to right on the other face of the beam.

8. The ceiling framework as claimed in claim 1, wherein, for each beam having the apertures, sequences of symbols are written from left to right on each face of the beam with a same starting symbol on each left-hand end of the beam.

9. The ceiling framework as claimed in claim 1, wherein the main beams are provided with the apertures, some of which are used to connect the cross beams, and wherein, for a given tile size, all connections between the main beams and the cross beams are made in apertures marked with a same symbol corresponding to the given tile size used, avoiding a necessity of counting a number of the apertures between two adjacent cross beams.

10. The ceiling framework as claimed in claim 1, wherein each connector is configured to make a connection according to a stab-in system and comprises two parts that include a primary clip as a first part of the two parts and a secondary clip as a second part of the two parts, which are fastened to one another via a fusible part configured to melt at a temperature of a fire so as to cause the two parts to separate.

11. A method for manufacturing the ceiling framework as claimed in claim 1, comprising: for each beam having the apertures, inserting ends of the other transversal beams bearing the connectors in those apertures of the beam which are marked with a same symbol corresponding to the size of the one tile, without counting a number of the apertures provided between two adjacent transversal beams bearing the connectors.

12. The method as claimed in claim 11, wherein each beam having the apertures is one of the main beams and the beams bearing the connectors are the cross beams.

Description

(1) The invention will now be described in greater detail with reference to the attached figures which depict:

(2) FIG. 1: a portion of the latticework of a metal framework for a suspended ceiling,

(3) FIG. 2: a more detailed view of a portion of a bearing beam and of two cross beams which are intended to be connected thereto and equipped with their connectors according to the invention,

(4) FIG. 3: an exploded view in the region of a connection of two cross beams, each equipped with a two part connector, with a main beam, comprising a view 3A of an end of a cross beam with a part of its connector, a view 3B of the end of the opposite cross beam with a part of its connector, a view 3C with the second part of the connector intended to complete view 3A, a view 3D with the second part of the connector intended to complete view 3B, a view 3E showing the main beam intended to be connected to the two cross beams of 3A and 3B,

(5) FIG. 4: a complete connector with its two parts assembled, viewed on each of its two faces, 4A being a view of its free face, i.e. of the face not butted against the cross beam, and 4B being a view of its opposite face intended to be butted against the cross beam, and

(6) FIG. 5: a schematic view of marked apertures of a beam, according to an illustrative example.

(7) FIG. 1 depicts the latticework of a metal framework 1 made up firstly of parallel main beams 2 attached by hangers 3 to a main structure, not depicted, generally the ceiling of a room or of a storey of a building, made up secondly of secondary beams or cross beams 4 which are parallel to one another and perpendicular to the main beams 2 and connected to the main beams at each point identified by a circle in the figure. In the spaces of the latticework of this metal framework 1 there are tiles 5 the same size and shape as the spaces, and intended to form a false ceiling some distance from a main ceiling which has not been depicted. In one alternative form, which is commonplace because it reduces the number of hangers to be adjusted for correctly balancing the metal framework 1 and therefore at the same time reduces cost, when the loads to be borne are not great, the spacing between the bearing beams 2 is increased and longer cross beams tailored to this longer spacing are used, these cross beams themselves being spaced apart by cross beams 4 of normal length running in the direction of the bearing beams 2. This other set up is the conventional one used for tiles 5 measuring 60 cm×60 cm: the bearing beams are then spaced 120 cm apart and spaced apart with cross beams running perpendicularly and lengthened to 120 cm, said lengthened cross beams themselves being spaced apart by cross beams 4 of the normal length of 60 cm, this time running parallel to the bearing beams 2, to form spaces in the metal framework 1 measuring 60×60. This alternative form has not been depicted in FIG. 1.

(8) FIG. 2 again shows a portion of a main beam 2 viewed from beneath and elements of two cross beams 4 (4a and 4b), the element 4a being already connected to the main beam 2 and the element 4b being offered up to the main beam 2 in the continuation of the adjacent cross beam part 4a, on the opposite side from the element 4a, with a view to connection. The main beams 2 and the secondary beams or cross beams 4 have the overall cross-sectional shape of an inverted T, the false-ceiling tiles 5 being supported by the sole that forms the flanges of the T of the main beams 2 and of the cross beams 4, and the attachment between the main beams 2 and the hangers 3, which have not been depicted in this FIG. 2, is via the stem of the T of the main beams 2, said hangers being hooked into holes, not depicted, pierced in these stems of the T or being attached otherwise using an accessory suited to the shape of the T and not depicted. The main beams 2 are also pierced periodically in their part that forms the stem of the T, with apertures 7 intended for connection with the ends of the cross beams 4. For the purposes of this connection, each end of a cross beam 4 is fitted with a connector 8 secured to said cross beam 4, notably using plunge joints or rivets 9. This FIG. 2 shows the cross beam 4a positioned behind the main beam and of which the connector, which has been passed through an aperture 7,—and which will be given the reference 8a because it is associated with the cross beam 4a—, reemerges on the visible front face of the main beam 2. To encourage support of the cross beams 4 by the main beams 2, the sole of the cross beams is bent over slightly at its end, allowing it thus to overlap the sole of the beam 2 by about 2 or 3 mm in order to press thereon.

(9) Insofar as a metal framework 1 is produced according to the alternative form mentioned earlier with certain cross beams 4 running parallel to the main beams 2 and which connect to other cross beams running perpendicularly, the connection remains identical in principle and in operation: the cross beams running parallel to the bearing beams 2 are equipped with connectors at their ends and they enter apertures identical to the apertures 7 mentioned hereinabove and connect therein, but this time these apertures are pierced in the secondary beams or cross beams perpendicular to them and which will support them. Interconnection with the connector 8 of the other cross beam parallel to the main beams and contiguous with this first cross beam occurs in exactly the same way, whether the aperture 7 is in a main beam 2 or in a cross beam. Since the connection is the same in this alternative form in which the main beams and the cross beams are no longer systematically perpendicular to one another, the remainder of the description will not return again to this alternative form, it being understood that it too forms an integral part of the invention.

(10) FIG. 3 shows the same elements as FIG. 2 but in greater detail. As before, the references of these elements will be assigned suffixes a (or b) according to whether these elements will be attached to a cross beam 4 with the suffix a (or b). This FIG. 3 is made up of 5 parts:

(11) 3A which shows one end of a cross beam 4a arranged to the right of the figure and on which the first part 10a of a connector 8a is mounted, which first part will be termed hereinafter the primary clip 10a,

(12) 3B which shows one end of a cross beam 4b arranged to the left of the figure, on which the first part 10b, or primary clip 10b, of a connector 8b is mounted. This cross beam 4b is intended to align with the cross beam 4a,

(13) 3C which shows the second part 11a of a connector 8a, which second part will be referred to hereinafter as secondary clip 11a,

(14) 3D which shows the second part 11b, referred to hereinafter as the secondary clip 11b, of a connector 8b,

(15) 3E is a schematic view of a main beam 2 pierced with one of its apertures 7 which is intended to accept the two opposing connectors 8a and 8b in order to secure the two cross beams 4a and 4b to this main beam and connect them together.

(16) The connectors 8a and 8b are identical. Each cross beam is equipped with a same connector 8 at each of its ends, fixed to one of the faces of the stem of the T of the cross beam at one of the ends, fixed to the other face at the other end. Thus, the connector 8a shown is fixed to the visible front face of the cross beam 4a whereas the other connector 8, not depicted, at the other end of the same cross beam 4a will be on the non-visible opposite face. In the same way, the connector 8b is on the non-visible rear face of the cross beam 4b whereas at the other end, not depicted, of the same cross beam 4b, the connector 8, likewise not depicted, is on the front face like the connector 8a.

(17) According to the invention, each connector 8 comprises two parts: a primary clip 10 which is fixed for example by plunge joints or rivets to the end of the cross beam 4 and a secondary clip 11 fixed to the primary clip 10 by a means that melts at a low temperature, notably chosen to be below 300° C., suited to the conditions in which the false ceiling is to be used. The fusible means that melts is, for example, a tin-based braze material.

(18) The primary clip 10 keeps the cross beam 4 resting firmly against the main beam 2 and keeps the interconnection with the connector 8 of the adjacent cross beam in the same alignment firm. It is also designed to withstand bending and be able to remain in alignment with the cross beam despite the loadings experienced, particularly those that may result from its insertion into the aperture 7 of the main beam 2 rather carelessly in an action of the “stabbing” type. For that reason it is made of a material that guarantees this robustness. A steel approximately 0.4 mm thick with a high mechanical strength is very suitable. To prevent it from corroding, it is advantageously covered with a protective coating of the electrogalvanized, bichromate or galvanizing type. As has already been stated, this primary clip 10 is intended to be secured firmly to the end of its cross beam 4, for example by plunge joints or rivets 9, preferably not aligned with one another in order further to increase the robustness of the attachment of the connector to the beam. This primary clip is mounted on its cross beam in such a way as to protrude beyond the end of said cross beam substantially in the proportions illustrated in FIG. 3. It has a rounded front face more or less forming a semicircle to make its insertion in an aperture 7 of the main beam 2 easier, even when it is offered up at an angle of as much as 10 or even 20° with respect to said main beam 2. At the ends of the circular arc, the rounded front portion 12 ends in two notches, one of them, 13, on the top of the primary clip 10 and the other of them, 14, which is wider, at the lower part, the notch 14 being slightly offset from the notch 13 and further from the rounded front portion 12 than the notch 13. The notch 14 is elongate and its length determines the amount of clearance needed to absorb the thermal expansion of the beams in the event of a fire. In a fire, the temperature may gradually reach around 1000° C. and that is therefore the temperature to which the various parts of the metal framework will be subjected. Since the coefficient of expansion of steel is around 12×10.sup.−6, a cross beam 1200 mm long will therefore expand by about 14 mm, which makes 6 mm to be absorbed at each end on each of the connectors at the two ends of the cross beam. A 600 mm cross beam will expand by only 7 mm, making 3.5 mm to be absorbed by each connector. Bearing in mind that not all of the expansion will have to be accommodated by the connectors at the two ends, given the slight softening of the system as a whole, it may be considered that a clearance of 4 or 5 mm, and therefore a notch length of 5 mm or even 4 mm for the notch 14 will be enough for connectors arranged at the two ends of 1200 mm cross beams. A fortiori, this clearance will be enough for connectors fitted to shorter cross beams, notably 600 mm cross beams. Further, given the fact that the steel of the primary clips is far tougher than the metal of the beams, if there were any slightly greater thermal expansion, the beam would be punched slightly by the primary clip before the framework deformed. A longer notch 14 measuring 7, 8 or even 10 mm, which allows greater travel in the event of a fire after the secondary clip has become detached is possible, although this lengthening might weaken the primary clip slightly. In any event, in the case of such an elongation, this potential weakening could be compensated for if necessary by adapting various other factors, including those already mentioned such as the thickness, the nature of the metal, reinforcements such as folds, ribs, etc.

(19) The maximum height of the primary clip 10 at the end of its rounded portion and just before the notch 13 is of the order of the height of the aperture 7 or slightly less than around 0.1 mm or 0.2 mm. Following on from the notch 13 on the upper part of the primary clip 10 there is a cut 15 separated from the notch 13 by a rounded hump 16, then bounded by a vertical edge 17. It is in the region of this vertical edge 17 that the primary clip 10 adopts its maximum height substantially greater than the height of the aperture 7. The primary clip 10 is pierced at its center with two recesses, 18 near the front 12 and 19 further towards the rear. The region separating these two recesses 18 and 19 is pressed near the recess 19 to create a protrusion 20 on that face of the primary clip 10 that is in contact with the cross beam. On the primary clip 10b shown in FIG. 3B, the face in contact with the cross beam is the visible face, so it is therefore on this face that the protrusion 20 appears. The primary clip 10 is also provided with means such as folds, ribs or bulges, such as the longitudinal bulge 21 depicted, which stiffen it and give it thickness. The front of this primary clip also has two bosses 22, 23 appearing on that face of the primary clip 10 that is not intended to be in contact with the cross beam. Thus, in FIG. 3A, these bosses 22, 23 are on the visible face; by contrast, on the primary clip 10b of FIG. 3B, these bosses are on the face that is not visible and because they are created by pressing, two slight hollows are visible on the visible face, these being the mark of the bosses and bearing the same references 22 and 23.

(20) FIGS. 3C and 3D show secondary clips 11a and 11b each of which constitutes the second component of a connector 8a and 8b respectively. The secondary clips 11a and 11b are identical and are intended to be associated with their respective primary clips 10a and 10b by being fixed to each of the free faces of said primary clips, which is to say to those faces that are not intended to be in contact with their cross beams 4a and 4b respectively. For preference, the secondary clips are made of steel. As already stated, each secondary clip is associated with its primary clip 10 by a brazed joint which melts at a temperature suited to the conditions likely to be encountered, particularly a temperature below 300° C. and in general of around 200-250° C., achieved for example by heating with a resistive element or by laser or induction heating. The secondary clips 11 are mechanically less strong than the primary clips 10, their thickness is smaller than that of the said primary clips 10: a thickness of the order of 0.3 mm is suitable in the case of a steel with a high elastic strength, giving these secondary clips 11 the required elasticity for connection and for the robustness of the connection. To prevent them from corroding, a galvanized or electrogalvanized coating is applied. A secondary clip 11 as shown in FIGS. 3C and 3D is a component that has a three-dimensional shape. For example, the secondary clip 11 is cut by a slot 30 over two-thirds of its height approximately, thus separating a rear part 31 from a front part 32. The front part 32 is bent away from the plane of the rear part 31 by an angle of to 25°; it tapers on its very front 33 and is shaped to come nearer to the main clip and therefore to the plane of its rear part 31 to encourage it to slip through the apertures 7. This front part 32 has a protrusion 34 the evolution of which is gradual and at a gentle slope when a finger is slid along it from the front to the rear of the secondary clip, but on the other hand is abrupt and creates an end stop when the finger is slid in the other direction from the rear forward. According to one embodiment, this protrusion 34 is a flange resulting from an outward bending of the top of this front part 32 and the width of which increases progressively from the front rearwards to end abruptly and form an end stop viewed from the rear/front direction. According to another embodiment, this protrusion 34 is formed from imprinting from the opposite face, thus creating a change in level which rises progressively in a gentle slope where a finger is slid along it from the front to the rear, this slope being interrupted by a slot which forms an abrupt edge and an end stop when the finger is slid in the opposite direction. A protrusion 35 bulging in the opposite direction to that of the protrusion 34 is created in the rear part 31 of the secondary clip by a slot and two folds. As already stated, this secondary clip 11 is secured to the primary clip 10 by the rear of its base 36, the region of its rear part 31 situated below the protrusion 35, so that said base 36 of this secondary clip situated under the slot 30, which is a solid part, fills the bottom notch 14 of the primary clip 10 in the lengthwise direction thereof and even in the heightwise direction extends further down than the edges of said notch 14. Thus, when the secondary clip 11 is fixed to a primary clip 10, the front edge of this base 36 constitutes an end stop at the end of the bottom of the rounded portion 12 at the front of the primary clip 10.

(21) When joined together, the primary clip 10 and the secondary clip 11 constitute a three-dimensional assembly because of the bent away front part 32 of the secondary clip the thickness of which is relatively great when no stress is applied to this bent away front part 32, but which can be reduced under load. The shapes, dimensions and configuration of the secondary clip 11 are such that once assembled with its primary clip 10, the tapered tip 33 of the front part 32 of the secondary clip is slightly set back by around 1 mm from the very front end of the rounded portion 12 of the primary clip. Also, said tapered tip 33 is positioned between the two bosses 22 and 23 of the primary clip 10 and the top of these two bosses protrudes heightwise beyond the free surface of this point, thus protecting it from any knocks during the connection operation.

(22) FIG. 3E shows a portion of a main beam 2 with an aperture 7. The apertures 7 are in the overall shape of a diamond or, more specifically, a double trapezium, the two trapeziums being superposed, of height equal to the maximum height of the rounded front portion 12 of the primary clip 10 of the connectors. The maximum width of the aperture 17 is such that it allows two connectors 8 positioned head to tail to pass through, their two bent apart but elastic portions 32 being able to flatten to bring them closer into the plane of the portions 31 of the secondary clips.

(23) The two views 4A and 4B of FIG. 4 again show a complete connector 8 comprising its two constituent parts, its primary clip 10 and its secondary clip 11, assembled. View 4A shows the free face of the connector which remains visible when it is assembled at the end of a cross beam. This view 4A again shows the elements of the connector 8 that have already been shown, namely essentially the primary clip 10 and, resting against said primary clip 10, the secondary clip 11, both as already stated being joined together by a fusible means such as brazed material. In the rear part of the primary clip 10 it is possible to make out the two holes which will accept the plunge joints or rivets 9. The rounded portion 12 of the front part of the primary clip 10, its bosses 22 and 23, one of the two recesses 18, 19, in this instance the one referenced 18 which is the one furthest forward, the bulge 21 intended to increase the rigidity, the notch 13, then the cut 15 on the top edge of the primary clip 10, are clearly visible. As far as the secondary clip 11 is concerned, its position relative to the primary clip 10 with its front part 32 bent away from the plane of its rear part and at the same time from the main plane of the primary clip 10 may be seen; it is also possible, thanks to the perspective angle from which this view 4A is viewed, to see how its tapered tip 33 is positioned between the two bosses 22 and 23 of the primary clip 10, how it comes closer to the plane of the primary clip 10 and how by bending it forms the protrusion 34 with an edge at a gentle slope. This same FIG. 4A also shows the base 36 of the secondary clip 11 which plugs the notch 14 of the primary clip 10, which notch is therefore not visible in this view 4A. Thus, the length of the notch 14 is filled by the secondary clip 11, as this has the effect of reducing and even eliminating the clearance allowed for a connector connected into the aperture of a beam.

(24) FIG. 4B shows the other face of the connector 8, the face intended to press against the cross beam 4. The overall shape of the connector and, in particular, of the primary clip 10 essentially visible on this face, the two holes for attachment to the cross beam by plunge joints or rivets 9, the mark of the bulge 21 as a hollow on this face, the recesses 18 and 19, the notch 14, the protrusion 20 and those parts of the associated secondary clip 11 which are visible through the recess 19 and through the recess 18 or which protrude beyond the primary clip, notably the tip 33 of the tapered part of the front 32 of the secondary clip and the protrusion 35 of the rear part thereof consisting of a slot and two folds, can be seen in this figure.

(25) The invention has been described with a notch 14 at the lower part of the periphery of the primary clip 10 but a configuration in which the notch is in the upper part is also covered by the invention. In this alternative form, the secondary clip is then arranged in such a way as to be able to fill this notch.

(26) When manufacturing a framework for a false ceiling, the system as described hereinabove works as explained below. First of all, the main beams 2 are arranged parallel to one another and anchored to the ceiling by the hangers 3. Next, the ends of the cross beams bearing the connectors 8 are “stabbed” into the evenly spaced apertures 7. To make it easier to insert into the correct point from among the multitude of apertures 7 in the main beams and prevent the need to count off how many apertures 7 there are to be between two adjacent cross beams, the apertures are marked, notably by engraving, inkjet printing or the like, with the size of tile 5 (the common sizes are 600, 625, 675 mm) as the period of the series of marked symbols. As shown for example in FIG. 5, if the tile size contains six apertures, they will be numbered with a sequence 1, 2, 3, 4, 5, 6, this sequence then repeating facing the next apertures along the primary beam 2. The fitter who has connected the secondary beam or cross beam 4 under the number 3 for example, will simply need to connect the other cross beams 4 parallel to one another under the same number, thus avoiding any individual counting of apertures. The sequences are written from left to right on each face of the primary beam 2 with the same starting number on each left-hand end of this primary beam 2. Thus, one side reads 1, 2, 3, 4, 5, 6,/ . . . /1, 2, 3, 4, 5, 6 from left to right, and if the beam is rotated through 180° about a vertical axis passing through its center, the same thing will feature from left to right on the other side. This situation is made necessary by the fact that the beam 2 can be mounted in sequence with a rotation by 180° with respect to this vertical axis without that altering the result of the assembly obtained.

(27) When a connector 8 at the end of a cross beam 4 is thrust into an aperture 7, its entry and penetration are made easier by the fact that the front end of the primary clip 10 which is first to come into contact with a main beam 2 is rounded, thus preventing the connector from dropping too far down in the aperture 7 and also preventing the sole of the cross beam 4 from striking that of the perpendicular main gbeam 2, and finally because the tapered end of the front 32 of the clip is brought closer to the rounded front part of the primary clip 10. It is impossible for the tapered front part 32 of the clip 11 to knock either against the walls of the aperture or against the other connector intended to be inserted into the same aperture 7, because this tapered front part is protected by the two bosses 22 and 23 which flank it, which protrude further beyond the said tapered part and because it is shorter than the primary clip 10. As entry into the aperture 7 continues, the external face of the front of the clip comes into contact with the lateral edge of the aperture 7, then it is the edges of the protrusion 34 which, pressing against the edge of the aperture 7, force the spring-effect elastic front part 32 of the secondary clip to flatten slightly; then, as penetration progresses still further, the notch 13 of the primary clip 10 of the connector at the same time becomes immobilized in the very top part of the aperture 7 and the protrusion 34 protrudes beyond the lateral wall of the aperture 7. Because of the elasticity of the front part of the front part 32 of the clip and the abrupt edges of this side of the protrusion, the connector finds itself immobilized and prevented from moving back. The top of the aperture is then immobilized in the notch 13 and the bottom part of the rounded portion of the front face 12 of the primary clip 10 is very close to the aperture. The connector and the cross beam attached to it are therefore immobilized in the aperture 7. The main beam supports the cross beam and, even with no support at the other end, the cross beam is held in position, cantilever fashion. Just prior to immobilization, the gradually sloping fold of the protrusion 34 rubs against the lateral wall of the aperture 7, forcing the elastic front part 32 of the clip to flatten progressively and, at the moment of immobilization, because the edge of the protrusion 34 is suddenly overshot, the elastic part 32 of the clip relaxes and therefore produces a metallic noise or “click” which is the information that validates correct clipping of the connector into the aperture 7. This “click” is the result of the metallic nature and elastic properties of the clip.

(28) When the second cross beam 4 to be aligned with the first already installed is offered up to the other face of the main beam 2 and begins to enter the aperture 7, the two faces of the connectors 8 which have no clips slide against one another. The forward movement of this second cross beam and its immobilization in the aperture 7 occur as explained in respect of the first cross beam. In addition, the two cross beams interconnect with one another. The two elastic portions of the clips 11 collaborating with the lateral edges of the aperture 7 keep the two connectors pressed against one another. The end stops formed by the protrusions 20 bear against the front wall of the recess 18 of the opposite connector. The high strength of the steel of the primary clips 10 of the connectors, the elastic pressure applied by the secondary clips, and the bulges 21 having a size that causes them to press against the lateral walls of the aperture 7, all contribute to keeping the connectors firmly connected to one another via their protrusions 20 and their recesses 18.

(29) If need be, in order to remove the connector when it is on its own in the aperture 7, the elastic part 32 of the secondary clip 11 needs to be pressed by hand in order thus to disengage the lateral part of the aperture 7 from the stop that the protrusion 34 constitutes.

(30) In order to remove the connector when it has already been interconnected with its parallel counterpart facing it in the aperture 7, the elastic part 32 must be pressed by hand and the cross beam thus held twisted upward about the axis formed by the main beam so that the protrusion 20 can escape contact with the hole 18, this beginning at the start of the rotational movement through the fact that the upper boss 22 protrudes beyond the hole 18, allowing it to ride more easily up the protrusion 20 of the connector opposite. This dismantling can be done effortlessly and with no damage to the connectors or to the beams.

(31) The metal framework thus created is capable of withstanding significant tensile loadings in excess of kilos, and various vibrations, thus preventing it from being damaged in the event of such vibrations and making it suitable for use in earthquake areas. This superior performance is a result of the interconnection between two aligned cross beams at their respective connectors fitted into one and the same aperture that allows the tensile loading to be spread across all the connections with the main beams along each line of cross beams, and also results from the firmness of these connections which is due to the robustness of the metal of the primary clips, to the spring effect of the secondary clips which effect presses together the two connected primary clips in order to keep them firmly connected, and to the absence or near-absence of clearance under normal circumstances.

(32) In the event of a fire, the secondary clips 11 secured to their primary clips 10 detach when 200-250° C. is reached. The result of this is that the base 36 of the secondary clips uncovers the notch 14 and that the end stop 35 which is blocking the front of the primary clip of the opposite connector ceases this blocking action. Under the longitudinal thrust resulting from thermal expansion caused by the fire, the connectors penetrate a little further into the apertures 7, the humps 16 of the primary clips 10 of the connectors no longer form an obstacle to this progression insofar as the notches 14 compensate for the height of said humps 16. The apertures 7 are therefore located in the region of the cut 15 on the top of the primary clip 10 and in the region of the notch 14 on the bottom of the same primary clip 10. Both the cut 15 and the notch 14 have a certain length of the order 4 or 5 mm which allows the connectors to penetrate further into the apertures which means that expansion can continue without risk to the integrity and intactness of the framework which therefore remains correctly aligned thus preventing the tiles 5 from falling out and thus protecting the structure and the ceiling above.

(33) The fact that the connector is produced in two parts means that each part can be better specialized by choosing its composition, its treatment and its shape without being limited by restrictions imposed by the other part.

(34) Thanks to the combination of the primary clip that allows a relatively large amount of clearance with the secondary clip that reduces this clearance for operation in normal service, it is possible for thermal expansions caused by fire to be absorbed without impairing the stability, precision and solidity which are needed for an esthetically attractive solution.

(35) An interconnection clearance of as little as 0.2 or even 0.1 mm is thus possible. It is also advantageous to preserve this small clearance in order to absorb any manufacturing variations on the beams and prevent these variations from adding up and causing the grid spacing of the ceiling to deviate.