Patent Description:
In the building field and in the naval industry support frames for scaffoldings made in metallic material, for example steel or aluminum, are known. These frames can for example comprise scaffoldings of traditional type, for example used for the manufacture of masonry works, constituted by a plurality of substantially "H"-shaped frames and constrained to each other by means of horizontal beams. Each frame is engaged to a horizontal beam by means of a joint having two shells capable of engaging, by means of pins or bolts, respectively a pillar of the H-shaped frame and a horizontal beam.

Although the scaffoldings described are widely used, the Applicant has observed that the latter have limitations and drawbacks. Such structures are in fact unsuitable for use in corrosive environments such as for example nautical yards or uses in maritime locations. The corrosion of metallic materials in fact causes deterioration from the chemical-physical interaction with the surrounding environment. By effect of the corrosive process, metallic material undergoes a progressive and irreversible decay, of chemical nature, of its technological properties. The damages produced by corrosion are very significant and can cause the replacement of the entire structure or of components thereof or otherwise costs of maintenance aimed at preserving the metal structures used.

For these reasons, the traditional frames, when used in environments corrosive for metals (for example environments close to maritime areas) show a reduced operating reliability, as well as high maintenance costs.

An example of pultruded product, disclosed by <CIT>, is a tubular cylindrical body having a plurality of annular projections transversely spaced by grooves. <CIT> further discloses a pultrusion process for making the product using molds to form the annular projections.

A second example of pultruded product, disclosed by <CIT>, is a U-shaped body having a flat upper surface with transverse grooves spaced from each other. <CIT> further discloses a pultrusion process for making the product using a forming belt to create the grooves on the flat upper surface of the product.

Purpose of the present invention is then to solve at least one of the drawbacks and/or limitations of the previous solutions.

A purpose of the present disclosure is to provide a product made of composite material, for example a tube, free of metallic components.

It is also a purpose of the present invention to avoid or minimize the execution of material removal operations for the manufacture of the pultruded products made of composite material.

Another purpose of the present invention is to provide pultruded products made of composite material through continuous pultrusion processes.

Another purpose of the present disclosure is to offer a support frame comprising pultruded products made of composite material both capable of operating without functional problems and in aggressive environments, for example in maritime areas.

It is another purpose of the present disclosure to make available a support frame comprising pultruded products made of composite material that shows a high reliability grade and that requires a reduced number of maintenance interventions.

These purposes and others, which will be clearer from the following description, are substantially reached by a product made of composite material, a process for the manufacture thereof and a support frame comprising said product according to one or more of the attached claims and/or of the following aspects.

Some embodiments and some aspects of the invention will be described hereinafter with reference to the attached figures, provided for illustrative purposes only and therefore not limiting, wherein:.

It is noted that in the present detailed description corresponding parts shown in the various figures are indicated with the same numerical references. Figures may show the object of the invention through unscaled representations; therefore, parts and components shown in the figures related to the object of the invention may refer exclusively to the schematic representations.

With the terms upstream and downstream used in the description of pultrusion apparatuses it is intended components operating upstream or downstream with respect to other components as well as to steps carried out upstream or downstream with respect to other steps with reference to the feeding direction of the pultruded semifinished product during the process of pultrusion.

In the present description and in the claims the term pultrusion comprises processes wherein the reinforcement materials, as continuous fibers arranged parallel to each other or reinforcing fiber fabrics or in reinforcing fiber mat or braided fibrous materials, are impregnated of resin and moved through a forming head or molding (which may be stationary or movable), downstream thereof operates a pulling system active on the continuous semifinished product exiting the forming head or molding. In other words the term pultrusion is here used for meaning processes which comprise one of the following:.

With <NUM> has been overall indicated a pultruded product made of composite material (in <FIG> and in <FIG> it is shown a longitudinal portion thereof), for example usable for making support frames, such as for example tensile structures, modular support frames or scaffoldings usable in the building and naval field, frames and structures usable in offshore uses for example on oil platforms or similar.

As for example shown in <FIG>, the product comprises an elongated body <NUM> of tubular shape extending along a predetermined prevalent development direction X. In the attached figures it is shown a tubular elongated body of substantially cylindrical shape, however, it is not excluded the manufacture of an elongated body having a prismatic shape with polygonal section, for example square or rectangular.

The elongated body of the product <NUM> has an inner volume, perimetrically bounded by an optionally cylindrical inner surface <NUM>. The elongated body <NUM> has furthermore an outer surface comprising a base surface <NUM> also of optionally cylindrical shape from which emerge projections <NUM>, as it will be better described hereinafter. In the example shown in <FIG>, the elongated body <NUM> has, in cross-section view, a circular shape with closed profile with wall thickness S1 constant along the longitudinal development of the elongated body. It is noted that in this context it is intended for wall thickness, the thickness S1 measured between the inner surface <NUM> of the elongated body <NUM> and the base surface <NUM>, which is constant as above mentioned and comprised between <NUM> and <NUM>, optionally comprised between <NUM> and <NUM>.

As mentioned, the outer surface of the elongated body has also one or more projections <NUM> made in one piece with base surface <NUM>. In particular, the projections <NUM> emerge from the base surface <NUM> transversely to the prevalent development direction X of the elongated body <NUM> and are spaced from each other along the same direction X, i.e. longitudinally to the product <NUM>, from one section (in particular by a smooth section) of the base surface <NUM>.

Each projection <NUM> has an elongated shape transverse to the prevalent development direction X (see <FIG> and <FIG>). Each projection <NUM> may be defined by a respective discrete element of limited extension: for example, by observing the profile of a transverse section of the product of <FIG> (see then <FIG>), each projection elongates along part of the outer profile of this transverse section; in fact in the case of <FIG> are provided multiple projections angularly spaced from each other along the outer profile of the same transverse section of the product. Alternatively, the projections <NUM> may be defined by successive sections of a same continuous element, for example with helical pattern, protruding from the base surface <NUM> (not shown solution). In another variant (see <FIG>) the projections may be different discrete elements projecting from respective portions of the base surface <NUM> spaced from each other and of annular shape, for example of circular shape, which extend radially around the entire base surface <NUM> of the elongated body.

As visible in <FIG> and <FIG>, the product <NUM> may present one or more series <NUM> of projections <NUM> positioned next to each other along a direction parallel to the prevalent development direction X of the elongated body <NUM> and arranged along respective trajectories to each other parallel transverse to the prevalent development direction X. As for example shown in <FIG>, each projection may show, in a longitudinal section plane that cuts the projections <NUM> and is parallel to the prevalent development direction X, a shape defined by:.

As previously mentioned, the projections <NUM> are equidistant to each other, of a pitch X1 measured between two first flanks 3c of two projections <NUM> of the series <NUM> longitudinally adjacent to each other. This pitch is for example comprised between <NUM>,<NUM> and <NUM>, for example between <NUM> and <NUM>. In the attached figures, are also shown projections having a predetermined base width L, measured in between the flanks 3c, 3d of a same projection <NUM>, at the base surface. This base width L of each projection may be comprised between <NUM> and <NUM>, and for example between <NUM> and <NUM>. Still with reference to the shape of each projection in longitudinal section (<FIG>), the top <NUM> is at a predetermined height H from the section 4a of the base surface <NUM> which delimits the projection itself. This height H may be comprised between <NUM> and <NUM>, and for example between <NUM> and <NUM>. However, it is not excluded the manufacture of projections having width, height and pitch different with respect to what is described.

With reference now to the view in a section transverse to the prevalent development direction X of the elongated body <NUM> (for example <FIG>), the projection <NUM> has as already said height H with respect to the base surface <NUM>. The height H may be of dimensions proportional to a maximum overall dimension of the cavity of the elongated body <NUM>, for example the height H may be a function of the diameter D of the elongated body <NUM> (should this defines a cylindrical cavity) delimited by the inner surface <NUM>. The ratio between the height H of each projection <NUM> and the diameter D may be then comprised between <NUM> and <NUM>, optionally between <NUM> and <NUM>. The height of the projection H may also be proportional to the dimensions of the wall thickness S1 of the elongated body <NUM>: for example, the ratio between the wall thickness S1 itself and the height H of each projection <NUM> may be comprised between <NUM> and <NUM>, optionally between <NUM> and <NUM>.

As already mentioned the projections <NUM> may be continuous annular projections or discrete segments: for example in the embodiment shown in <FIG>, the projections <NUM> have a tooth shape extending between a first and a second end 3a, 3b transversely offset from each other on the base surface <NUM>, for example of an angle comprised between <NUM>° and <NUM>°.

Each series <NUM> of projections may have a plurality of projections <NUM> arranged next to each other along the prevalent development direction X of the elongated body, wherein the first ends 3a of respective projections <NUM> are aligned along a direction A parallel to the prevalent development direction X of the elongated body <NUM>, and wherein the second ends 3b of respective projections <NUM> of the series <NUM> are aligned along another direction B parallel to the direction A. In other words, each series <NUM> defines a longitudinal strip laterally delimited by sections of the base surface <NUM> free from projections.

The product may comprise a plurality of series <NUM> of projections defining respective longitudinal strips angularly offset from each other. The product may have from <NUM> to <NUM> series <NUM> of projections mutually flanked and angularly equidistant to each other. In particular the strips <NUM> of projections may be angularly offset from each other of an angle comprised between <NUM>° and <NUM>°, optionally comprised between <NUM>° and <NUM>° (<FIG>), spaced by sections of the base surface <NUM> free from projections. It is also to be noted that the series <NUM> of projections are preferably identical to each other and the toothshaped discrete projections <NUM> or the ones continuous of annular shape (<FIG>) show, in longitudinal section view, the same geometric characteristics as previously described, to which reference is made. From the point of view of the materials, the composite product comprises synthetic reinforcing fibers <NUM> such as carbon fibers, glass fibers, aramid fibers, Kevlar, boron fibers or natural fibers such as natural fibers of animal origin, basalt fibers or natural fibers of plant origin. These reinforcing fibers <NUM> may be in part aligned (and arranged full-length) along a direction parallel to the prevalent development direction X of the elongated body. In addition or alternatively the fibers may be arranged according to cylindrical helix or according to bundles of fibers arranged inclined with respect to the prevalent development direction X. The reinforcing fibers are present in the product in a percentage by weight comprised between the <NUM>% and the <NUM> %, optionally between the <NUM>% and the <NUM>%, with respect to the total weight of the product. The resin can for example comprise a thermoplastic or thermosetting polymer matrix, among which polyester, polyurethane, vinylester and epoxy resin, but also thermoplastic matrices such as the polybutylene terephthalate (PBT) and the polyethylene terephthalate (PET).

It is also object of the present invention a pultrusion process for the manufacture of the product made of composite material <NUM> previously described and hereinafter claimed. This pultrusion process is carried out using a pultrusion apparatus <NUM> which, as subsequently detailed, is configured for realizing the transversal projections <NUM>.

As shown in <FIG>, the pultrusion process provides the following steps:.

The step of moving the reinforcing fiber <NUM>, provides to feed a fiber or a set of reinforcing fibers (which may for example form woven or braided filaments, mat of fiber, or stay in shape of fibers arranged next to each other) <NUM>, for example from one or more spools <NUM> or other feeding organs of fibrous material of the apparatus <NUM>. It is to be noted that, according to the invention, the impregnated fibers, for example with thermosetting resin, may be fed parallel to each other and then unidirectionally arranged in the product in production (classical pultrusion). Alternatively or in combination with the arrangement of unidirectional fibers, impregnated fibers, for example with a thermosetting resin (generally epoxy), may be arranged according to one or more windings (pull-winding) and brought towards the forming head where the resin polymerizes. In other words, the fibers may be arranged parallel to each other or for example according to one or more helixes or in both the ways just described (i.e., part of the fibers arranged parallel to each other along the longitudinal development of the product and part of the fibers arranged inclined for example according to one or more helixes).

According to another alternative the fibers may be fed in form of braided layers (pull-braiding). The braided layers of fibers are impregnated of resin (for example of the above-described type) and sent to the forming head. This alternative may be combined either with the classical pultrusion or with the pultrusion of pull-winding type or with both of them.

The reinforcing fibers <NUM> impregnated with a quantity of synthetic resin at the station <NUM> can proceed towards a guiding and positioning station <NUM> (for example comprising a comb or a member equipped with a plurality of through openings for the opportune positioning of the fibers). The reinforcing fibers <NUM> may be moved upstream of the forming head <NUM> by means of rollers <NUM> of the apparatus <NUM> and/or pulled thanks to the action of a guiding member <NUM> positioned downstream of the forming head and still forming part of the pultrusion apparatus. The rollers <NUM> in cooperation with the guiding or pulling member <NUM> of the apparatus <NUM> (or even only the guiding or pulling member <NUM>) are configured for tensioning the fibers and aligning them with respect to the opening of the forming head <NUM>. For this purpose a control system for example comprising at least a control unit for example of digital or analog type, can coordinate the pulling action carried out by the guiding or pulling member <NUM> as well as, eventually, the movement imposed on the rollers <NUM> and optionally the braking imposed on the spools <NUM>. The process object of the present invention provides the manufacture of the projections <NUM> through the use of at least an additional element <NUM> capable of forming continuously the mentioned projections on the outer surface of the product directly during the process of pultrusion: the structure of this additional element <NUM> will be subsequently detailed. The process initially provides for positioning a section upstream of the additional element <NUM>, defined upstream of the forming head <NUM>, in an area radially outside of reinforcing fibers <NUM>, for example in contact with these latter. In particular, the section upstream of the additional element <NUM> is positioned at a respective section parallel to the reinforcing fiber <NUM> itself. The process provides subsequently of moving the additional element <NUM> synchronously with the reinforcing fibers, across the forming head <NUM>. During this step, the additional element <NUM> has at least a surface positioned at a perimeter edge delimiting the through opening of the forming head <NUM>; in other words, also during the step of crossing the forming head <NUM>, the additional element <NUM> can contact the reinforcing fiber impregnated in an area radially outside of the product in production. The continuous product is then formed within the forming head <NUM>, while the fibers and/or the resin are still in contact with the additional element <NUM>. As for example shown in <FIG>, the process may provide the use of two or more additional elements <NUM>, each of them configured for contacting a respective area radially outside of the product in production, for making a respective series <NUM> of projections <NUM>. It is to be noted that the forming of the product occurs continuously: in other words subsequent portions of the product exiting the forming head are kept in continuous movement. This movement is achieved with the guiding member <NUM>, which may comprise, as shown in the attached figures, two or more rollers counter-rotating or alternatively one or more conveyors.

Subsequently to the step of forming, the process provides a step of solidification of the synthetic resin of the continuous product, which can occur both through exposure to natural light or through exposure to an actinic radiation directed towards the product, for example acheved through ultraviolet lamps <NUM> of the apparatus <NUM>, for example operating immediately downstream of the forming head <NUM>. It is to be noted that at least a part of the step of solidification can occur also within the forming head.

Subsequently to an at least partial solidification of the resin, for example before or after the complete solidification of the resin, the process may provide a step of separating the additional element <NUM> from the continuous product according to the modes subsequently described, variable according to the typology of additional element <NUM> used. The process ends with the execution of a step of cutting the continuous semifinished product obtained by pultrusion carrying out a transversal cut or separation to the reinforcing fiber <NUM>, for example in a cutting station <NUM> of the apparatus <NUM>, for defining respective composite products <NUM> of the above-described type, which may be stored and/or conveyed.

Descending into greater detail, the apparatus <NUM> comprises as already mentioned one or more additional elements <NUM>, operating at the periphery of the product in production. Each additional element <NUM> may be defined, in an embodiment for example shown in <FIG> and <FIG>, by a conveyor <NUM> being part of a positioning device <NUM> comprising a motor member <NUM> and a driven member <NUM> (for example a drive roller and a driven roller) around which it is arranged the conveyor <NUM> according to a closed loop operational path. The conveyor <NUM> and then the additional element <NUM> has an outer surface configured for contacting the reinforcing fiber <NUM> and forming the projections <NUM>. As shown in detail in <FIG>, the conveyor <NUM> has a base body <NUM> and a plurality of elements projecting <NUM> from the base body, to each other different and spaced for defining in interposition between two adjacent protruding elements <NUM>, a channel <NUM> configured for housing at least partially reinforcing fiber <NUM> and resin, and then forming a projection <NUM>. The channels <NUM>, at least for a section of the operational path of the conveyor parallel to the reinforcing fibers <NUM>, are transverse to the reinforcing fibers <NUM> themselves and generally transverse to the direction of pultrusion. The protruding elements <NUM> and the channels <NUM> define an outer surface preferably covered seamlessly from a layer in nonstick material, for example silicone-based material, polytetrafluoroethylene (PTFE) or polyvinyl alcohol (PVA). In this embodiment, the step of separating the additional element <NUM> from the product <NUM>, provides exclusively the movement of the conveyor along its own operational path which deviates angularly with respect to the trajectory followed by the pultruded semifinished product, for allowing the extraction of the projections from channels <NUM>.

In another embodiment for example shown in <FIG> and <FIG>, each additional element <NUM> is a strip in fibrous material fed by a feeding station <NUM> of the apparatus <NUM> which during the process is positioned in an area radially outside of the reinforcing fibers <NUM> and configured for moving the additional element <NUM> itself in direction of the forming head <NUM>, for example through the use of one or more conveyors or rollers. As for example shown in the schematic representation of <FIG> (representative of a strip of additional element <NUM>), the fibrous material of the additional element has a first and a second series <NUM>, <NUM> of fibers or wires transversal to each other. The fibers or the filaments are configured for forming the projections <NUM> and the base surface <NUM>. In other words, the additional element <NUM> may be a strip in fabric, wherein warp and weft of the fabric are formed by woven wires (in turn formed by fibers) or directly woven fibers. For allowing the formation of the projections during the process of pultrusion, the fibers of the first series <NUM> (or the wire which constitutes the warp and weft of the fabric) may have transverse section (or thickness) of overall dimensions lower with respect to an overall dimensions of the transverse section (or thickness) of the fibers of the second series <NUM> (or of the wire which forms the weft or respectively the warp of the fabric): this allows to precisely form a fabric substantially shaped as in <FIG> where at regular intervals is present a type of protruding rib formed by wires of higher thickness positioned as already said or in direction of the warp or of the weft. Each projection <NUM> forms then in interposition between adjacent fibers or wires of the second series <NUM>. In this last embodiment, the above mentioned step of separating the additional element <NUM> itself from the continuous product exiting the forming head <NUM>, provides a step of releasing the fibrous material or fabric from the pultruded semifinished product (also in this case it is imposed downstream of the extrusion head a trajectory on the additional element <NUM> different to the one followed by the pultruded semifinished product) thanks to a recalling station, which, in <FIG> has been schematized by one or more rollers <NUM> of the apparatus <NUM> around which the fabric is wound again. In this second example it is then defined a positioning device <NUM> of the additional element <NUM> comprising the station <NUM> and the recalling station <NUM> above described.

In another embodiment, schematically represented in <FIG>, the apparatus <NUM> may comprise one or more feeders <NUM> each configured for feeding an additional element <NUM> in form of a continuous wire, for example in plastic material with high mechanical performances and melting point higher than <NUM> (for example polyamides may be used as non-limiting such as nylon or kevlar). The wire is fed through the forming head <NUM> and arranged such as to form one or more loops inclined with respect to the prevalent development direction of the semifinished product in the step of forming in the head itself. For example it may be provided that the apparatus <NUM> comprises one or more feeders <NUM> rotating around the ideal feed axis of the product in production in such a way as to form on the periphery of this latter a projection <NUM> of helical pattern which is embedded (having the additional element <NUM> in form of wire to cross the forming head) in the resinous matrix. In a variant the additional element <NUM> in form of wire is left in the final product and then remains embedded in it, while in an alternative variant, the wire may be removed (and wound again on a respective spool <NUM>) yet leaving anyway a cavity and a corresponding ridge of helical shape on the surface of the product in production. In this third example the feeder <NUM> and the rewinder <NUM> (the latter if present) define the positioning device <NUM> of the additional element <NUM> (in this case filiform with helical pattern) on the continuous semifinished product.

It is furthermore object of the present disclosure a support frame comprising a plurality of products made of composite material <NUM> according to the attached claims and/or according to the above indicated description. As previously mentioned, the support frame <NUM> may for example be a tensile structure or a scaffolding usable in the building and naval field.

As for example shown in <FIG>, the frame <NUM> has a plurality of pillars <NUM> made as the composite product previously described, each of which is engaged, through a joint <NUM>, at least to a beam <NUM> also made as the product <NUM>.

In conditions of use of the frame <NUM>, the pillars <NUM> are positioned vertically with respect to the ground, while the beams <NUM> are positioned transverse to the pillars, engaged to the latter at a respective terminal end or of an intermediate area. As previously mentioned, the engagement between pillar <NUM> and beam <NUM> is obtained by joints <NUM> for example of the type shown in detail in <FIG>. Areas of intersection between a pillar <NUM> and a beam <NUM> (for example end areas or intermediate areas) are then engageable to a same joint.

Each joint <NUM> may have a main body <NUM> to which is engaged a half-shell <NUM>, mobile relatively to the main body <NUM> itself between an opening condition and a closing condition. In the opening condition, the half-shell <NUM> is at least in part spaced from the main body <NUM> for allowing the insertion of the pillar <NUM> within a seat <NUM> defined by the body <NUM> and by the half-shell <NUM> (subsequently further described), while in the closing condition, the half-shell <NUM> is blocked to the main body <NUM> for preventing at least a relative movement between pillar and joint in axial direction or parallel to the prevalent development direction of the pillar <NUM>.

In the shown embodiment, the main body <NUM> and the half-shell <NUM> define respective half-parts of the seat (<NUM>) with grooves 27a, 27b alternated to respective protuberances 27c, 27d delimiting the surfaces of each half-part of the seat <NUM>.

In the closing condition between main body <NUM> and half-shell <NUM>, the grooves 27a and the protuberances 27c associated to the first half-part of the seat <NUM> show concavity opposite to the concavity of the grooves 27b and protuberances 27d brought by the half-shell <NUM> and associated to the second half-part of the seat <NUM>. Practically, grooves and protuberances 27a, 27c brought by the main body <NUM> define a first half-part of the seat <NUM>, while grooves and protuberances 27b, 27d brought by half-shell <NUM> define a second half-part of the seat <NUM> facing the first half-part: the two half-parts are facing to each other (in closing condition between main body <NUM> and half-shell <NUM>) for defining the seat <NUM>. The grooves 27a, 27b are then alternated respectively by protuberances 27c and 27d emerging radially and configurated for engaging to projections <NUM> of the portion of pillar <NUM> inserted in the seat <NUM>, for preventing or minimizing a relative axial movement between pillar <NUM> and joint <NUM>. The seat <NUM> can show a substantially cylindrical embodiment (with corrugated surface given the presence of grooves spaced by protuberances) and in any case preferably countershaped to the shape of the outer surface of the pillar <NUM>.

As for example shown in <FIG>, the half-shell <NUM> is engaged to main body <NUM> through a hinge <NUM> and an engaging element <NUM> operating in position spaced from the hinge <NUM>. The engaging element <NUM> is configured for rotationally blocking the half-shell <NUM> to the main body <NUM> when in closing condition. The engagement element, which may for example comprise one or more screws or bolts or other movable pairing members, is on the other hand configured for being released or removed allowing the rotation of the half-shell around the hinge <NUM> and then the passage to the opening condition which allows the insertion or the removal of the pillar from the seat <NUM>. In a not shown alternative embodiment it is possible to provide that, instead of the hinge <NUM>, other removable constraining element <NUM> be provided. In another not shown embodiment it is possible to provide that the hinge and/or the engaging element above described are replaced by rivets or other constraining members that need to be destroyed for allowing the opening of the seat <NUM>.

In another embodiment, the hinge <NUM> may be made by a plastic hinge i.e. by a portion of deformable material, joined by piece to half-shell <NUM> and to main body <NUM>, which may then flex or bend for allowing to open or close the seat <NUM>; for example the hinge may comprise a strip of plastic material (for example elastomeric) which connects the half-shell <NUM> with the main body <NUM>.

The joint <NUM> furthermore has an auxiliary half-shell <NUM>, mobile relatively to the main body <NUM> itself between a respective opening condition and a respective closing condition. In the opening condition, the auxiliary half-shell <NUM> is at least in part spaced from the main body <NUM> to allow insertion of a portion of the crossbar <NUM> within an auxiliary seat <NUM> (analogous to the seat <NUM> and subsequently further described), while in the closing condition, the auxiliary half-shell <NUM> is blocked to the main body <NUM> for closing the auxiliary seat <NUM> and preventing or minimizing a relative axial movement (i.e., directed along the prevalent development direction of the beam) between beam and joint. It is to be noted that the auxiliary seat <NUM> is different and spaced from the seat <NUM>, extending transverse (for example perpendicularly) to the latter for allowing engagement of the crossbar <NUM> transverse to the upright <NUM>. From a structural point of view the auxiliary seat <NUM> may be identical to the seat <NUM> above described. In particular, the main body <NUM> has auxiliary grooves 29a alternated by auxiliary protuberances 29c, while the auxiliary half-shell <NUM> has grooves 29b alternated to respective protuberances 29d.

In the closing condition between main body <NUM> and auxiliary half-shell <NUM>, the auxiliary grooves 29a and the protuberances 29c associated to the main body <NUM> show concavity opposite to the concavity of the grooves 29b and protuberances 29d brought by the auxiliary half-shell <NUM>. Practically, auxiliary grooves and auxiliary protuberances 29a, 29c of the main body <NUM> define a respective first half-part of the auxiliary seat <NUM>, while grooves and protuberances 29b, 29d of the auxiliary half-shell <NUM> define a respective second half-part of the auxiliary seat <NUM> facing the first half-part: the two half-parts facing each other (in closing condition between main body <NUM> and auxiliary half-shell <NUM>) define the auxiliary seat <NUM>. The auxiliary grooves 29a of the main body and the grooves 29b of the auxiliary half-shell <NUM> are then alternated respectively by the auxiliary protuberances 29c of the main body and by the protuberances 29d of the auxiliary half-shell <NUM> emerging radially and configurated for engaging to the projections <NUM> of the portion of crossbar <NUM> inserted in the auxiliary seat <NUM>, for preventing or minimizing a relative axial movement between crossbar <NUM> and joint <NUM>. The auxiliary seat <NUM> may have a substantially cylindrical shape (provided with a corrugated surface, given the presence of grooves spaced by protuberances) and in any case preferably countershaped to the outer surface of the crossbar <NUM>.

In a non-shown variant the main body <NUM> presents (instead of the grooves above described) a first half-part of said seat <NUM> covered by a layer in soft material <NUM>'; analogously in this embodiment the half-shell <NUM> (instead of the grooves) has a second half-part of said seat <NUM> covered by a respective layer of soft material <NUM>'; the soft material of each of said layers has deformability to the compression higher with respect to the one of the material forming the main body of the joint and higher with respect to the one of the material forming said one or more projections present on each pultruded product. In this way, when the joint is in closing condition of the seat <NUM>, the projections can penetrate in the soft material positioned on the surface of the joint and axially anchor the pultruded product (crossbar or upright) to the seat <NUM> and then to the joint. In quite a similar way, according to this embodiment, the main body <NUM> may also present the first half-part of the auxiliary seat <NUM> covered by a layer in soft material <NUM>', and the auxiliary half-shell <NUM> may present the second half-part of the auxiliary seat <NUM> covered by a respective layer of soft material <NUM>'. Also in this case the layer of soft material of each of said layers replaces the grooves and has deformability to compression higher with respect to the one of the material forming the main body and higher with respect to the one of the material forming said one or more projections present on each pultruded product. For example, the soft material may be elastomeric material, silicone material or other. For example, a polyurethane elastomeric material may be used.

The above-described layers of soft material are for example continuous layers with constant thickness. Alternatively a prevalent part of each layer has constant thickness.

According to another aspect, the thickness of each layer is (at least for a prevalent part of the development of the layer on the respective half-shell) equal to or higher than the height H of each projection from the base surface <NUM>. In this way the projection/s may (when the joint is tightened and the seats <NUM> and <NUM> closed) penetrate in the soft material and then obtain an efficient axial blocking. For example, the thickness of each layer of soft material may be comprised between <NUM> and <NUM>. The alternative wherein are provided the layers of soft material allows an efficient blocking also in case of projection or projections having geometric dimensions that are not very precise or machining tolerances that are not too extreme.

As for example shown in <FIG>, the auxiliary half-shell <NUM> is engaged to the main body <NUM> through a respective hinge <NUM> and a respective engaging element <NUM> operating in a position spaced from the hinge <NUM>. The engaging element <NUM> is configured for rotationally blocking the auxiliary half-shell <NUM> to the main body <NUM> in the closing condition. The engagement element, which may for example comprise one or more screws or bolts or other removable coupling organs, is on the other hand configured for being loosened or removed allowing rotation of the auxiliary half-shell <NUM> around the hinge <NUM> and then passage to the opening condition which allows insertion or removal of the crossbar <NUM> from the auxiliary seat <NUM>. In a non-shown alternative it is possible to provide that, instead of the hinge <NUM>, another removable constraining element analogous to the engaging element <NUM> be provided. In another non-shown alternative, it is possible to provide that the hinge and/or the engaging element above described be replaced by rivets or other constraining organs that need to be destroyed for allowing opening of the auxiliary seat <NUM>.

In another variant (analogous to what was discussed for the hinge <NUM>), the hinge <NUM> may be made by a plastic hinge i.e., by a portion of material deformable that can then flex or bend for allowing to open and close the auxiliary seat <NUM>; for example the hinge may comprise a strip of plastic material (for example elastomeric) which connects the auxiliary half-shell <NUM> with the main body <NUM>.

From a constructive point of view it is possible to make the joint in various ways. For example the half-shell <NUM>, the auxiliary half-shell <NUM> and the main body may be made by molding, for example injection molding and then connected with the hinges <NUM>, <NUM> and the related engagement elements.

Alternatively the half-shell <NUM>, the main body <NUM> and the auxiliary half-shell <NUM> may be made by molding (for example injection molding) making, directly during the step of molding, the mentioned plastic hinges <NUM> and <NUM>. With regard to the alternative wherein the seats <NUM> and <NUM> are covered with soft material, this may be co-molded on the surface of the seats themselves in such a way as to form a joint entirely obtained by molding (for example injection molding) except obviously for the need of one or more engagement elements for the tightening of the seats <NUM> and <NUM>.

As to the materials, the main body, the half-shell <NUM> and the auxiliary half-shell <NUM> may be made in high resistance and stiffness material such as for example nylon reinforced with fibers (for example, glass or carbon fibers). On the contrary, as already mentioned, the layer of soft material (if present) may be made using material with deformability (in particular to compression) considerably higher with respect to the one of the material used for the main body <NUM> and the half-shells <NUM>, <NUM>: for example a polyurethane elastomeric material may be used for each layer of soft material.

The construction of the support frame <NUM> shown in <FIG> follows arrangement and engagement of a plurality of uprights <NUM> to respective crossbars <NUM>. This step provides the coupling of at least an upright <NUM> to at least a joint <NUM> through insertion of the upright within the seat <NUM> and of block of the half-shell <NUM> to the main body <NUM> of the joint by means of screws, pins or rivets. As previously described, the insertion of the desired portion of upright within the seat <NUM> occurs after the movement of the half-shell <NUM> from the closing position to the opening position. With the subsequent closure movement of the half-shell <NUM>, the upright <NUM> may be blocked to the main body of the joint <NUM>.

The process provides furthermore engagement of a crossbar <NUM> to the same joint <NUM> through insertion of the desired portion of the crossbar <NUM> within the auxiliary seat <NUM>. By blocking the auxiliary half-shell <NUM> to the main body of the joint <NUM>, blocking of the crossbar with respect to the auxiliary seat <NUM> of the joint <NUM> is obtained. Practically, the insertion of the desired portion of the crossbar <NUM> within the auxiliary seat <NUM> occurs in a way similar to the insertion of the desired portion of upright <NUM> in the seat <NUM> of the same joint.

Claim 1:
A pultrusion process for making a composite product comprising a tubular elongated body (<NUM>) extending along a prevalent development direction (X) and bounded by an outer surface comprising:
- a base surface (<NUM>) and
- one or more projections (<NUM>) emerging from the base surface (<NUM>) and arranged transversely to the prevalent development direction (X) of the elongated body (<NUM>), said projections or successive sections of the same projection being spaced apart from each other in a direction parallel to the prevalent development direction (X),
said process comprising:
- impregnating a reinforcing fiber (<NUM>) with synthetic resin in a liquid state, optionally with thermosetting resin,
- moving the impregnated reinforcing fiber (<NUM>) towards a forming head (<NUM>), wherein said forming head (<NUM>) has at least one through opening suitable for shaping the product,
- arranging across the forming head (<NUM>) two or more operating sections of respective additional elements (<NUM>) configured for forming respective projections (<NUM>),
- continuously forming, within the opening of the forming head (<NUM>), consecutive portions of a continuous composite semifinished product of tubular shape,
- transversely cutting a discrete segment of the continuous semifinished product for defining said composite product,
wherein respective upstream sections of each additional element, defined upstream of the corresponding operating section, are positioned at respective areas radially outer the continuous semifinished product.