Angled Assembly of Profiles for Tongue and Groove Fitting and Key Locking

French Pat. No. 2 226 029 discloses trellis-like metal constructions such as scaffoldings, frames or simply railings or parapets, constituted of profiles which are not assembled by welding, rivets or bolts, but rather by tongue and groove arrangements locked by keys fitted perpendicular to and sunk by force into the groove. The use of presses or calibrated jacks allows locking keys to be sunk in with well-defined force and assures a good safety coefficient for this type of assembly. Moreover, the key is generally provided with a shoulder which facilitates its driving into the groove and simultaneously limits this driving in and thus limits the deformation of the groove to a predetermined value.

Large constructions assembled rapidly and safely at the worksite are thus realized, even with inexperienced personnel.

However, it is to be noted that metal constructions using angled assembly of two profiles by groove, tongue and locking keys are hardly known, other than for trellis-like rectangular metal structures such as ladders, of which the rungs are assembled at right angles to the legs.

In fact, with these groove, tongue and key assemblies, the tightening applied by the key to the tongue assures sufficient jamming in the case wherein the constituent elements are subject to flexing, traction or compression. On the other hand, under the effect of reciprocal stresses, or vibrations, the tongue and the key slide along in the groove, one avoids using a force to support the assembly which has a component parallel to the generatrices of the groove. Because of this, trellis constructions having bars which are oblique to the flanges, which are assembled by a groove, tongue and locking key device, are hardly known.

The object of the present invention is a process and a device allowing oblique assemblies by groove, tongue and key, with a good safety coefficient, both transverse to the groove and also longitudinally along the groove generatrices.

The process of angled assembly of two profiles or structural members, according to the invention, consists of preventing any possibility of sliding of the tongue longitudinally in the groove and making one of the male elements or components introduced into the groove, i.e. either the tongue or the key of greater width than the other or having, a greater length than the other, in the direction of the groove generatrices, and giving one of the sides of the longer element a concave shape along its width, i.e. parallel to the groove generatrices. This side, instead of being essentially flat, is slightly curved inward at each end and the longer male element, instead of having a cylindrical shape of its generatrices parallel to those of the groove, is broadened at its two ends in the areas exceeding the length of the other male element. Thus, if one or the other of the two male elements or components tends to be moved along the groove, it is blocked by the enlarged end of the longer element. One has a sort of double key locking, the one, as in the prior art, locking perpendicular to the groove generatrices, and the other along these generatrices. This process thus leads to the realization of angled assembly devices of two profiles or members by fitting of a tongue into a groove which is integral with one of the profiles or members, the tongue being integral with the other, then locking of the tongue in the groove by a key which is sunk perpendicularly into the groove. To avoid longitudinal sliding of the tongue and key in the groove despite their force locking, one of the male elements of the assembly, the tongue or the key, is longer than the other, in the direction of the generatrices of the groove. One of the sides of the longer male element also is of concave shape along its length.

In the contact zone between the two male elements, tongue and key, the contact surfaces of these two elements are generally flat, and it is only beyond this flat contact zone that the surface of the longer element becomes concave at each end, allowing each of the ends of this longer element to be progressively broadened out, forming a sort of locking nose to block the length of the groove. It is possible to say that the surface of this longer element has a "flat concave" shape.

Thus, along a length essentially equal to the shorter male element, the tongue and the key are locked in the groove along the essentially flat surfaces. If there is a thrust of one of the male elements to slide longitudinally in the groove, then it is blocked by one of the two noses of the longer element.

The concavity of the side surface of the longer element can be such that the extra thickness at its ends is essentially equal to the thickness of the other male element without however being at all greater. Thus it is possible to have a certain pinpoint blocking of both ends of the groove of the concave male element, which further prevents longitudinal sliding.

The invention will be better understood from the following description of particular examples of devices according to the invention. This nonlimiting description is illustrated by the attached drawings.

FIG. 1 shows a perspective view of a trellis girder with oblique bars.

FIG. 2 shows a partial cross section of the girder through a plane perpendicular to its large axis XX', in larger scale.

FIG. 3 shows a partial cross section of the girder through a plane AA of FIG. 1 perpendicular to the plane of the girder and parallel to its large axis, in larger scale.

FIG. 4 shows a view similar to FIG. 3, with a variation of embodiment of the invention wherein the tongue is longer than the key, in the direction of the groove generatrices.

FIG. 5 shows a cross section similar to that of FIG. 2 wherein each flange has two parallel grooves.

FIG. 1 shows a perspective view of a trellis girder of metal, made up of two flanges 1-1' with angles and oblique flat crossbars 2-2'-2"-2'", arranged obliquely in relation to flanges 1-1'. Each of the facing wings of flanges 1-1' has a groove 3-3' forming two facing channels. Crossbars 2-2'-2"-2'" are not fixed to flanges 1-1' by welding or by bolts, but rather by fitting of their ends, which are tongues 4-4', in grooves 3-3', where they are blocked by keys 5-5'-5"-5'"-5""-5""'. Of these, both to facilitate their placement and to limit their insertion into grooves 3-3', and thus to limit the force exerted for locking of the assemblies, each key has a shoulder 6-6'-6"-6'"-6""-6""', most visible in FIG. 2. For reinforcement, grooves 3-3' have an L-shaped cross section, and the fitting tongues 4 have fillets or edge ridges 7 which have extra thickness, which hook into the bottom of L-shaped grooves 3-3'.

FIG. 3 shows that, longitudinally in groove 3, key 5 is longer than tongue 4 at the end of bar 2. The side 8 of key 5, which engages on tongue 4, is concave at its two ends 9a-9b, where key 5 has an extra thickness almost equal to the thickness "a" of the other male element, here, tongue 4. Thus, even in the absence of tongue 4, key 5 cannot be placed in place in groove 3 without being slightly forced into the groove and being subjected to a very slight deformation of its two ends 9a-9b.

The central part 10 of key 5 is of complementary shape to that of groove 3 and tongue 4 with an extra thickness intended to cause deformation when it is opened to a distance e' which is defined by computation, and groove 3 is of the initial thickness e.

The concavity of side 8 of key 5 generally speaking is not continuous but rather is formed by two planes 11a-11b which are inclined in relation to the first central part 10 of side 8. This is what is intended by "flat concave" shape.

To have good longitudinal fitting of tongue 4 against ends 9a-9b of key 5, the angle of inclination alpha of planes 11a-11b in relation to the central part must be less than 7.degree.. Thus, under the effect of a force F parallel to groove 3, tongue 4 tends to slide longitudinally in the groove; the tongue does not abutt sharply against key end 9b, but slides longitudinally thereon, separating the edges of groove 3, thus coming to block said groove.

For better locking of key 5, longitudinal striations are made on the surface 12 which is applied to the inclined surface 4 of the groove, as shown in FIG. 2.

FIG. 4 shows a cross section AA of a variation of the invention wherein tongue 4 is longer than key 5. In this case, it is the side surface 13 of tongue 4 which is concave. Key 5 is blocked only by ends 9a-9b of tongue 4 which are slightly deformed. This solution is not the most desirable. It would be preferable that the flat part of surface 13 of tongue 4 have a length equal to that of surface 8 of key 5 and that maximum contact be retained between tongue and key, on all of their engaging surfaces 8-13.

In the case shown, surface 13 of tongue 4 facing key 5 is concave, but this could as well be the opposite surface 14, or even simply the surface corresponding to fillet 7 which would then include an extra thickness at its two ends. In this case, the tongue is deformed during insertion of the key, in a concavity analogous to that shown in FIG. 4.

In the examples shown, the bars of the trellis girders are flat profiles or members, but they could as well be other types of profiles, e.g. T profiles of which the vertical bar of the T would be sectioned at the ends so that the horizontal bar of the T forms a tongue which can engage in a groove of the corresponding flange of the web girder.

Finally, so that the trellis bars can be arranged along the girder in opposite inclination to the plane of the girders, as near to each other as desired, it is important to provide two parallel grooves 3a-3b as in FIG. 5 in the flanges. Each of the grooves 3a or 3b would be fitted with bars inclined all in one direction. This configuration of flanges 1-1' allows realization of trellis girders of which the axes of bars 2-2' intersect on the axes of flanges 1-1'.