of the invention ENTITLED "Device for mechanically joining steel bars" on behalf of Tecnaria Spa.

The present invention relates to a device for mechanically joining steel bars according to the general part of claim 1.

The invention is used in various types of construction, such as, by way of non- exhaustive example, structures of reinforced concrete, masonry and metallic carpentry.

With regard to reinforced concrete structures in particular, as is well known to designers and construction workers, the correct operation of the junction by overlapping of the steel bars is closely linked to the type of concrete that incorporates them and to the thickness of the coating layer of the bars and depends on numerous factors that progressively reduce the effectiveness thereof over time. Among the aforementioned factors, the most important, due to the fact that it is unavoidable, is linked to the concrete carbonation process, which leads to a gradual increase in the porosity of the concrete over time, associated with a loss of protective capacity and adherence to the bars. Naturally, also events such as bumps, fires and earthquakes, which are part of a possible life cycle of a structure, are likely to weaken the covering concrete, compromising the quality of the junction by overlapping.

To avoid these problems, the only technical solution that guarantees the axial junction of steel bars consists in the use of mechanical devices, commonly called sleeves, which block the opposing ends of said bars, thus achieving the restoration of continuity without relying on the concrete and without using welds. A very common type of axial mechanical junction is the threaded joint, where the opposite ends of the two aligned bars are threaded so as to be screwed into a single intermediate connecting sleeve.

Another type of axial mechanical junction, equally common, is the bolted joint, where it is not necessary to process the threading of the bars, which are supported within clamping devices fixed by bolts.

By way of example, the patent document WO2005045151 A2 is cited where a sleeve (ref. 18, 418) is used having a deformable internal section so that, with the closure of the sleeve by means of screws (ref. 432, 5332) it deforms, thus blocking the end parts of the two bars (ref. 12, 14 and 512, 514).

Again by way of example, the patent document EP1504163 Bl (figs. 9,10) is cited where the two bars (ref. 101) are inserted inside a sleeve (ref. 1000) and blocked on knurled tightening saddles (ref. 301) with appropriate bolted screws (ref. 302, 303, 304) passing through threaded holes formed centrally on the sleeve, with direction perpendicular to the axis of the sleeve itself and with a tear-bolted head, so as to level the outer surface of the sleeve and, at the same time, make the escape of said screws impossible.

The most important prior art document however consists of document US 4127354 A; further prior art documents are JP 2001304210 A, US 5127763 A, US 4795365 A, WO 2001/159049 A2 and US 2006/067785 Al.

In particular, the preamble of claim 1 of the present application corresponds to the content of document US 4127354 A.

For the quality of the junction to be guaranteed, the bolted screws are tightened by means of a suitable wrench, which requires a suitable housing space during the execution phases. In the building site practice, the use of bolted joints has the drawback of a considerable encumbrance of the bolted screws, whose dimensions, in some applications, make it difficult to tighten the same screws adapted to block the bar inside the sleeve, with the consequence that the same final quality of the mechanical junction can be partially compromised with respect to the ideal situation in which the operator's maneuvering space is such as to allow the tightening to be carried out with comfort.

The object of the present invention is to provide a device for mechanically joining steel bars which is free of the drawbacks of similar known products.

Specifically, the object of the invention is to provide a device for mechanically joining steel bars which is simple to manufacture, easy to use, has a small size and is easy to visually inspect to check the fixing quality.

This object is achieved with a device for mechanically joining steel bars according to the features of the characterising part of claim 1. Other features of the invention are described in the dependent claims.

The invention will be better defined by the description of some possible embodiments thereof, given only by way of non-limiting example, with the aid of the accompanying drawings, in which:

fig. 1 (dwg. I) shows a perspective view of a junction of steel bars according to the invention;

figs. 2, 3, 4 (dwg. II) show three orthogonal views of the junction in fig. 1;

figs. 5, 6, 7 (dwg. Ill) show three orthogonal sectional views along lines V-V, VI- VI,

VII- VII of the junction in fig. 1;

figs. 8, 9, 10 (dwg. IV) show three orthogonal views of the toothed plate;

fig. 11 shows sectional views of the tooth according to the lines in fig. 10; fig. 12 shows the steps of introducing the toothed plate into the sleeve;

fig. 13 shows a detailed view of the tooth;

figs. 14, 15, 16 (dwg. V) show orthogonal plan views of the sleeve, the views in fig. 15 and 16 being sectional according to lines XV -XV and XVI-XVI in fig. 14;

figs. 17, 18, 19, 20 (dwg. VI) show prospective and sectional views, respectively, of two different embodiments of the sleeve;

figs. 21, 22 (dwg. VII) show perspective exploded and operating views, respectively, of the junction in fig. 1;

fig. 23 (dwg. VIII) shows a perspective view of a junction of steel bars according to the invention which uses a single toothed plate;

fig. 24 shows a side view of the junction in fig. 23;

figs. 25, 26 (dwg. IX) show perspective views of two further embodiments of the invention, with the use of four toothed end plates, or two toothed end plates, respectively, associated with a central toothed plate.

As seen in figs. 1-3, the device according to the invention, indicated as a whole by reference numeral 100, which serves for the mechanical junction of two opposed aligned steel bars 101, consists of a sleeve 1 provided with a through hole 2, arranged in the direction of the longitudinal axis "X" of the sleeve, inside which the two ends 102 of the two bars 101 are inserted, and two plates 3, provided on the major surface of a toothing 4 which are inserted in slots 5, obtained on sleeve 1 with a perpendicular direction with respect to the longitudinal axis "X" and cling, by means of the aforesaid toothing 4, to ends 102 of bars 101, making the desired mechanical joint. Specifically, as visible, in particular in figs. 6 and 7, bar 101 has a diameter "d" smaller than diameter "D" of hole 2 by a value such as to allow plate 3, when it is completely inserted in slot 5, to push portion 102 of the aforementioned bar 101 in tangent contact against hole 2 and, at the same time, to penetrate in the aforementioned portion 102 for a depth not greater than height "h" of teeth 6 of toothing 4, to make a sawtooth fastening portion 7 between plate 3 and end 102 of bar 101.

As seen in figs. 8-10, plate 3 is in the form of a parallelepiped, with the lower end tapered 8 so that teeth 6, also being tapered (see sections in fig. 11), during the introduction of plate 3 in slot 5 gradually come into contact with the bar portion 102 (fig. 12) which, from the initial position resting on the bottom of hole 2 (pos. 1), with the gradual introduction of plate 3 in slot 5, is pushed laterally (pos. 2,3), until it is positioned in a tangent manner laterally on the aforementioned hole 2, held by toothing 4 of plate 3, totally inserted in sleeve 1 (pos. 4).

The invention further provides that, in order not to compromise the mechanical characteristics of the bar, the incision of teeth 6 on portion 102 of bar 101 takes place with a rolling operation, i.e. through heating without removal of material, equipping the aforementioned teeth 6 with crests 9 that are not pointed and thus, are not sharp (fig. 13).

Moreover, at least one of the two side walls of sleeve 1 is provided with openings 10 which allow verifying the correct positioning of end 102 of bars 101 inside sleeve 1; specifically, it is possible to check that the two opposite fronts 11 of the two bars inserted in sleeve 1 are correctly positioned in the center of the sleeve, or at half of the length of said sleeve.

Sleeve 1 may have a rectangular section where wall 12 has a thickness "s" suitable for withstanding the thrust of the bar when it is held resting (figs 17, 18), or a circular section (figs. 19, 20). As shown in fig. 23, a different embodiment of device 100 according to the invention provides for the use of a single toothed plate 3.1 which, introduced into a single slot 5.1, simultaneously hooks both ends 102 of the two bars 101.

Moreover, as shown in fig. 24, hole 2, present in the square section sleeve 1, is made in a non-central position, so that the two side walls of said sleeve have thicknesses "SI" and "S2" suitable for optimising the forces acting on said walls, allowing smaller section sleeves to be obtained.

Finally, as shown in figs. 25 and 26, two further embodiments are possible which respectively provide for the use of a plurality of plates 3 (four in fig. 25) equally positioned on the two ends 102 of the two bars 101, or a "mixed" use of end plates 3, combined with a central plate 3.1.

From what has been described above, it is clear that the predetermined objects of the invention have been achieved because, as can be seen in particular in figs. 1 and 23, device 100 for the axial mechanical junction of two steel bars 101, consists of two or more elements, sleeve 1 and a plate 3.1 or two or more plates 3, all easily implemented and with very limited overall dimensions; moreover, the operation of attachment to the bars is just as simple as, as shown in fig. 22, it is sufficient, after introducing the ends of the two bars into the sleeve, to insert by pressure (arrow "F") the single plate 3.1 and/or the other plates 3 in the corresponding slots 5.1 and/or 5, an operation which is carried out quickly by specific pressing equipment.

Of course the materials, dimensions and shape of the single components may be various, depending on the design requirements of the reinforcement to be made, provided it all falls within the inventive concept defined by the following claims.