Building renovation works are a larger portion of the market than the construction of new buildings. Such works are mostly made by the so-called"dry"systems using metal constructions to which covered plaster curtain walls are secured by screws.

Such light constructions consist of metal channels forming both flat and curved surfaces having even very complex architectural shapes.

Different types of channels are currently available on the market. They are shaped directly on the building yard and use specific channels having suitable features according to the construction to be built, e. g. guide channels that can be bent are used for a curved wall as well as other types of channels that can be bent are used for the vault, etc.

The state of art proposes only one channel having the capability of being bent and shaped on all space planes, while the other metal channels have a restricted capability of being bent and, generally, only on one space plane.

The capability of such already existing channel to be bent is based upon the inventive concept of the "hinge"joint formed by the material folds inside the

section of the metal channel, especially at the base and the flanges of the U-shaped section. Such folds run transversally to the determined length and are symmetric both to the transversal and the longitudinal axes having the shapes of a succession of open box- like cups connected to one another by folded material, thus allowing the channel to be easily bent by hand.

Such folds, however, prevent greatly the vertical upright sections from sliding and being positioned. In addition, channel must be stiffened with ribbings or templates to be screwed to the construction in order to prevent the joints from rotating and then to cause the channel to keep the desired curved shape.

The solution of the present industrial invention consists of a method of manufacturing channels that can be easily shaped by hand and bent on all space planes without resorting to further steps to provide the material compressing upon production, as it is the case for the"hinge"joint, but by subjecting flat plates to combined compressive and bending stress or to continuous roll forming, thus giving a metal band which has been slotted and recessed previously in particular portions thereof generally a U-shaped section.

The thus produced channels are characterized in that: - the inside section is free from any material fold; - the Y-shaped slots in the base are disposed in alternation with like slots rotated by 180° with respect to the former slots;

- the base is slotted transversally with a determined pitch to form Y-shaped slots, the ends of the"V" portion of the slot reaching the base of the vertical side surface and the other end of the remaining"I" portion of the slot raising the opposite vertical side surface until the recessed connecting material strip; - a small length of the slotted side surface is not sheared so as to connect vertical adjacent surfaces ; - the connecting strips have vertical recesses two of which are disposed at the ends of the strip, a third one at the central point, and a fourth recess is formed horizontally at the centre of the strip and is bounded by the not sheared vertical surfaces. Such recesses are shaped as a half cylinder and directed to the inside of the channel section. Moreover, the central section of the connecting strip is reduced by the removal of a portion of material with a semicircular shape both at the upper and the lower borders; - two small circular holes are formed at the ends of the connecting strip; - one or more holes are formed in the remaining portion of the base.

The shape of slots, recesses, holes and the number thereof as well as their size and location in the surface of the band can be modified with respect to the foregoing provided that the channel keeps the peculiar features of the invention that are accomplished both by the chemical-physical characteristics of the metal material and the

particular recesses formed in the connecting strips at both sides of the channel unchanged. They have a weakening function and receive all outside loads applied by hand or mechanically that cause the plastic deformation of the material allowing the metal sheet to be bent easily in those point of application to provide a curved segmented channel.

In order to better understand the unchanged features of the new inventive concept consisting of the recesses formed in the metal material of the connecting strips, the membrane kinematic mechanism established in such length of material should be highlighted if a couple (strain) is applied from the outside.

Should the channel be bent to provide a U-shaped section on a plane parallel to the side surfaces (for example to form an arch in a vertical wall) a force directed from the bottom to the top should be applied to the central point of the connecting strip which will produce a constraining reaction opposite to the force applied to the ends of the strip. The lower fibres of the material are subjected to compression and the upper fibres to stretching because of the physical plasticity of the metal sheet.

In order to provide a permanent deformation of this length of the channel it is necessary in some way to "store"at the same time both the material stretching of the upper portion and the reduction in length of the lower portion. To this end the three half cylindrical vertical recesses whose depth has about

the same amount as the thickness of the material come into play.

Upon watching such phenomenon at the microscope, the recesses can be likened to a material arching which takes up a longitudinal room equal to the diameter of the cylinder and has an extension equal to half circumference.

The diameter of the recesses start to stretch at the upper portion and to compress at the lower portion giving rise to a so-called accordion effect.

The surface strength of the connecting strip is increased by forming a further horizontal recess crossing the whole connecting strip along its centre line to avoid such central length to tear by the so- called"notch effect"because of the small width of material in such central length of the connecting strip. This measure allows the channel to be also used as rigid guide because it brings a significant rigidity just in the weakened length, thus making up for the lower amount of metal material in such length.

Of course, what is the case for the single connecting strip as above is also the case for the other connecting strips of the channel which are also responsive in the same way when the bending is directed upwards or when a"wavy"shape of the channel is provided.

Should the channel be U-shaped on a plane parallel to the base (for example to provide a curved wall), a force perpendicular to one lateral surface of the channel should be applied to the weakened portion,

i. e. the connecting strip, in a direction from the outside to the inside of the"U"section.

In order for the channel to be bent, it should have a different length of the side surfaces which are parallel to each other and integral with the base surface that in turn should have such requirements as to allow it to be bent. In fact, upon bending two . parallel surfaces with respect to the same centre of rotation, two concentric arches are provided having a different radius of curvature, the distance of the vertical surface which should"extend"from the centre being greater than the distance, which is necessarily shorter, of the other vertical surface to which the strain is applied.

Therefore, the base of the channel is slotted with a determined pitch so as to cause the peripheral edges of the slot to approach on the same plane upon bending. Thus, the base surface does not have any material fold or hinge that reduces the section of the channel. The"Y"shape of the slot brings advantages as further, even if very small, segmentation are provided at the vertical flat surface between two connecting strips.

The Y-shaped base slot, with its"V"portion being directed to the vertical surface that will have to "extend", extends crosswise with its"I"portion along the whole base and continues to the opposite vertical surface and reaches the connecting strip so that the peripheral edges of the vertical surfaces connected by the strip approach on the same plane upon bending,

thus causing the length of the surface to shorten when the channel is subjected to strain. This is the case only provided that the connecting strip does not hamper such approach.

The connecting strip should bend to the inside of the channel section by such an amount as to cause that the reduction in length of a single strip, together with the reductions in length of the other strips, will provide as a whole the bending of the channel.

The presence of the vertical recesses helps the inside bending of the strip because of their half cylindrical shape and the reduced section of the central surface, to which the forces orthogonal to such surface are concentrated, thus inducing irreversible plastic bending deformations. In particular, as the central recess is subjected to a compression with a reduction in its diameter, the other two recesses at the ends of the strip stretch, thus increasing their diameter.

At the same time, all of the recesses on the other vertical surface stretch as such surface is involved in the extension of the stretched fibres. Such further extension helps the reduction in the depth of the folds directed inside the channel section upon bending.

After the above appropriate, necessary functional analysis of the inventive concept, reference is made to the accompanying drawings where the invention is shown by means of illustrative, not limiting embodiments for a better understanding thereof.

Fig. 1 shows a preferably metal band in which transversal Y-shaped slots with a determined pitch are formed in alternation with like slots rotated by 180° with respect to the former slots, where the"V"slot portion starts at about one third from the outside edge of the band, and the"I"slot portion extends along the remaining part of the band until it reaches almost the other outside edge except for a thin strip with almost rectangular shape connecting adjacent surfaces; Fig. 2 shows a"L"band bent along the line connecting the two ends of the"V"slot portions ; Fig. 3 shows a perspective view of an U-shaped channel obtained by bending longitudinally by 90° also the other portion of the band along the line connecting the two ends of the"V"portions of the other slots; Fig. 4 shows the U-shaped channel with the vertical sides having different heights ; Fig. 5 shows the detail of the not sheared length where four recesses have been formed to the inside of the channel section having a half cylindrical shape, two of which being formed at both ends and a third one at the centre of the strip in the vertical direction, the fourth one being formed longitudinally at the centre line of the connecting strip;

Fig. 6 shows a portion of the channel when it is subjected to outside loads to be bent on a plane parallel to the side surfaces; Fig. 7 shows in detail the plastic deformation of the connecting strip subjected to bending; Fig. 8 shows a top plan view of a U-shaped channel which is bent on a plane parallel to the base; Fig. 9 shows the same view as above, with the channel being bent like a"S" ; Fig. 10 shows a perspective view of a detail of the bent channel where the partial bending directed to the inside of the"U"section of the connecting strip on one side of the channel can be seen ; Fig. 11 shows a detail of the above deformed, folded length; Fig. 12 shows the U-shaped channel used as a curved guide with vertical metal channels inserted inside it and able to form a carrying structure for panels or covering plates ; Fig. 13 shows a carrying structure consisting of vertical channels which are inserted into two U-shaped

channels bent like a"S"and secured to the ceiling and the floor to make an undulating wall; Fig. 14 shows an application of the U-shaped channel bent like an arch and embodied in a carrying structure to form a wall with arched door; Fig. 15 shows an application of the U-shaped channel having sides with different heights to make a curved stepped structure to which covered plaster panels are secured by screws ; and Fig. 16 shows the U-shaped channel when it is subjected to a torsional stress.

With reference to the figures, the channel of fig. 3 is made by starting essentially from a preferably metal band 1 from which transversal Y-shaped slots 2 are sheared with a predetermined pitch in alternation with other like slots 3 rotated by 180° with respect to the former slots. A portion 4 of the band with an almost rectangular shape is not sheared between the ends of the slots and the respective side edges of the band, such portion forming a connecting strip between adjacent surfaces 5.

Slotted band 1 is bent like an"U"by a continuous shaping method by rolls that bend the material longitudinally along lines 6 and 7 joining the respective ends 8 and 8'of the V-shaped portions of

slots 2 and 3 of the base so as to form vertical surfaces 5.

Fig. 2 shows band 1 bent only at one side along bending line 6 to form a L-shaped channel that can be made by a method of combined compressive and bending stress.

Circular holes 9 and 10 are formed in the base and the ends of connecting strips 4, respectively. Portions of material with semicircular shape are removed from the central portions of connecting strips 4 both at their upper 11 and lower 12 sides, as shown in fig. 5, thus further reducing the section of the connecting strips.

Each connecting strip 4 has also three vertical recesses 13,14 and 15 and one horizontal recess 16 with half cylindrical shape, the diameter of which is almost the same as the thickness of the material.

Fig. 4 shows an embodiment of the U-shaped channel having different vertical sides. In particular surface 5'has a greater height than surface 5.

When the U-shaped channel is not subjected to external loads causing it to bend, recesses 13,14, 15 and 16 perform the function of stiffening the connecting strip because of the presence of ribbing corrugations of the material surface that increase the whole performance of the channel as far as its rigidity is concerned in order for the latter to be similar to the rigidity of a conventional not sheared U-shaped channel.

Fig. 6 shows two adjacent side surfaces 5 of the U- shaped channel connected by strip 4 and subjected to

strains to bend the channel on a plane parallel to the side surfaces. It should be noted that the upper side 11'of the central portion of the connecting strip is extended because of the stretching of the fibres and the plastic deformation of the vertical half cylindrical recesses 13,14 and 15, the yielding of which causes the upper side 11'to form a half circumference and the lower side 12'to be compressed with the result of an increase in the depth of the central portion of the lower side 12'and the lower end of the vertical recesses.

It should be noted that side edges 17 and 18 of adjacent vertical surfaces 5 form a"V"upon approaching each other until they come into contact as the radius of curvature reaches the lower limit determined both by the initial distance between edges and the height of surfaces 5. Such approach is possible because of the presence of slot 19 formed in the base of the U-shaped channel axially with connecting strip 4.

Of course, the arrangement on a side of the channel is also provided on the other side thereof. The whole relative rotations as well as the plastic deformations of each connecting strip allows the U-shaped channels to be bent.

The channel is bent by hand owing to the thin material of the connecting strip as well as the recesses that make the outside forces to concentrate to such connecting strips, thus causing the material of such strips to deform permanently.

It should be appreciated that the inside section of the channel is completely free from any hindering material fold. Furthermore, the U-shaped channel can also be bent on the same plane but to the opposite direction so that channel lengths with upward and downward bending can also be provided after one another.

Fig. 7 shows in detail the plastic deformations or corrugations of the metal sheet causing the side edges 17 and 18 of vertical surfaces 5 to approach. Such corrugations strengthen the connecting strip so that its performance can be compared with a metal sheet with a double or triple as high thickness with respect to the thickness of the starting channel, thus making up for the lower amount of metal material in such strip.

Fig. 8 shows a top plan view of the U-shaped channel curved on a plane parallel to the base. As can be seen: -the"closed"slots 2 and the"open"slots 3 have respective opposite edges 2', 2"close each other and edges 3', 3"spaced apart ; - the small material folds 20 directed to the inside of the channel only on one side 21 thereof are formed because of the shortening of side 21 with respect to side 22 in which the vertical recesses 13,14 and 15 are partially stretched and help to increase the difference in length due to the fact that side 21 has a smaller radius of curvature than side 22 and the latter has a greater length of its arc of

circumference because it has a greater distance from the centre of rotation than side 21 ; - circular holes 9 are formed in the base ; - slight folds 23 cause vertical surfaces 5 to deform so that side 22 can take the shape of a curve, thus reducing the length of its linear portions with closer segmentations.

Fig. 9 shows a top plan view of the U-shaped channel curved both upwards and downwards on a plane parallel to the base so as to form a"S". In this case small material folds 20'directed to the inside of the channel are formed in side 22 as well as small vertical folds 23'are formed in side 21.

Fig. 10 shows a perspective view of a portion of the U-shaped channel of fig. 8, and fig. 11 shows in detail the plastic deformations of the material of the connecting strip between vertical surfaces 5, in particular the vertical recesses with half cylindrical shape 13'and 15'are deformed together with the central recess 14'which becomes almost cylindrical.

Also holes 10'and central horizontal recess 16'are deformed because of the outside load to bend the channel.

The U-shaped channel is bent by hand by applying a pressure by the fingers to the side edges of adjacent vertical surfaces 5 and pushing the material to the inside of the channel to be bent. The applied forces are conveyed to a direction perpendicular to the surface of the connecting strip because of the particular recesses and the shape of the latter and

concentrate to the centre of the strip, thus causing irreversible changes of the recesses with permanent deformations of the material.

Further membrane corrugations 13', 14', 15', 16'and 10'are induced to the surface of fold 20 at the connecting strip 4, thus stiffening such length so that the U-shaped channel will have a performance as though it were a continuous curved levelled channel.

The depth of fold 20 which will cause a greater or lower crowning of the material inside the channel depends both on the distance between side edges 17 and 18 of vertical surfaces 5 and the pitch of slots 2 and 3 formed in band 1. In any case, such folds are fully negligible if compared to the width of the channel and the usual radius of curvature of such constructions that have to be covered by plaster panels which by nature have a limit to their curvature.

Fig. 12 shows a vertical upright channel 24 inserted inside the U-shaped guide channel where the small folds inside the channel do not cause any problem.

This is also the case for an undulating wall shown in fig. 13 where the U-shaped channel is used both as floor guide and ceiling guide.

Fig. 14 shows an U-shaped channel used as carrying structure of an arch in a flat wall. Fig. 15 shows a perspective view of a curved stepped structure made by U-shaped channel of the type of fig. 4 having sides with different heights. At last, fig. 16 shows a curved U-shaped channel subjected to torsional stress that produces curvatures not lying on a plane parallel

to the side surfaces and on a plane parallel to the base neither.

In the light of what above described and illustrated, the advantages of the U-shaped channel are as follows: - it can be produced by continuous shaping of a band without additional compressing of the material ; - it can be produced by combined compressive and bending stress of flat plates that are slotted and recessed; - it can be used as rigid supporting structure for covering panels of flat or curved surfaces; - it can be shaped directly on yard as it can be easily shaped by hand; - it can be curved on all space planes.

In comparison with other bendable channels, the channel of the invention has specific features such as: - the absolute lack of material folds inside or outside the channel as the U-shaped channel is bent on a plane parallel to the side surfaces ; - the appearance of small crowning of material directed to the inside of the channel when it is bent on a plane parallel to the base, which are fully negligible if compared with the folds that are present or should be deliberately formed on other bendable channels; - the particular Y-shaped slots formed in the base with a predetermined pitch in alternation with other slots rotated by 180° that make the shaped channel approximately similar to a curved surface as the

vertical surfaces are subjected to a slight significant bending at the contact points with the ends of the V-shaped portion of the slots, thus reducing the linear lengths and segmenting more the whole surface.

Finally, the present invention is fully innovative and has essential differences with respect to the state of art as it uses not only the particular geometrical shapes of the slots, the shape and the positioning of surface recesses but also the chemical-physical features of the material, the whole being directed to provide a channel that can be easily bent by hand on any space plane, thus inducing to the material irreversible plastic deformations that stiffen the whole channel so that it keeps the desired bent shape permanently.

Formal, structural changes of the invention can be made by those skilled in the art without departing from the inventive concept which is defined by the following claims.