EP2358487A2

EP2358487A2 - Method and apparatus for manufacturing spiral-reinforcements for reinforced concrete

Info

Publication number: EP2358487A2
Application number: EP09744193A
Authority: EP
Inventors: Anton Massimo Galluccio
Original assignee: Schnell SpA
Current assignee: Schnell SpA
Priority date: 2008-10-15
Filing date: 2009-10-12
Publication date: 2011-08-24
Anticipated expiration: 2029-10-12
Also published as: IT1391412B1; WO2010044052A2; ES2412382T3; WO2010044052A3; EP2358487B1; WO2010044052A4; ITBO20080637A1; DK2358487T3

Abstract

The method for manufacturing spiral reinforcements provides for feeding a metal wire (2) through a foldingunit (5) provided with a central mandrel (7) and an eccentric folding pin (8), having parallel axis, and for performing successive folds of said metal wire (2) with respect to the longitudinal feed axis (A), to produce a succession of polygonal coils (20) designed to form a spiral-reinforcement (21) constituted by a sequence of perpendicular tracts (22) and of oblique tracts (23) with respect to the longitudinal axis (L) of the spiral. On at least one side of the polygonal coils (20), to form said oblique tracts (23), are made a first fold (23a) on a plane orthogonal to the axis of the mandrel (7) and of the eccentric folding pin (8) and at least a second fold (23b) extended in a third dimension suitably inclined with respect to the aforesaid plane.

Description

Title of Invention: METHOD AND APPARATUS FOR MANUFACTURING SPIRAL-REINFORCEMENTS FOR REINFORCED

CONCRETE

Technical Field

[1] The present invention regards a method and an apparatus for manufacturing spiral- reinforcements for reinforced concrete and other three dimensional developing elements, as well as the spiral-reinforcement thus made. Background Art

[2] It is known that for manufacturing the reinforcement of reinforced concrete pillars and beams, metal cagesconstituted by longitudinal reinforcing rods connected by suitably distanced transverse stirrups are commonly used. Manufacturing such cages is usually rather complex and requires considerable execution times, with sensible waste of workforce and proportionally high costs.

[3] Alternatively to the use of traditional metal cages with stirrups, it has been proposed to use so-called continuous clamping reinforcements, made by spiral- winding a metal rod substantially 'spring' shaped with the required length. It has been noted that such reinforcements have better resistance characteristics, in particular to twisting, with respect to the traditional metal cages.

[4] The spiral-reinforcements can have various configurations. The pitch between a coil and the following one determines the density of the coils and so the characteristics of structural resistance of the reinforcement. Spiral-reinforcements of the known type are illustrated in documents US 3,604,180, EP 0 152 397, EP 0 630 297.

[5] Manufacturing reinforcements wherein the spiral is made without pitch and successively axially put in traction in order to obtain the desired pitch between the coils is particularly known. But when the spiral is made with the provided pitch, it can be compressed and so reduced in compact form, with the coils leaning the ones against the others, such as to be suitable to be stored and transported on the place of use in the minimum dimension configuration. The spiral-reinforcement is blocked in the aforesaid compact configuration by means of suitable fastening or anchorage means. On use, the spiral-reinforcement is released of the fastening or anchorage means, in a way as to allow the spiral to elastically stretch and to assume the desired predetermined dimension.

[6] Nevertheless the spiral-reinforcements are more difficultly feasible, as they require the use of machines more complex than the traditional ones and involve high costs compared with the economic value of the product. The common bidimensional wire bending machines are able to manufacture spiral-reinforcements, but only with moderate length, since they do not provide for members suitable to support the same reinforcement during the formation. The main problem lies in the fact that the spirals made by means of bidimensional wire bending machines are substantially without pitch, namely with the coils leaning the one against the other. This means that, at the moment of the installation, the spiral-reinforcements must be suitably lengthened, with obvious operative complications. In fact the operation requires considerable efforts and manufacturing variable pitch structures further results very difficult.

[7] A specific drawback complained in the manufacturing of the cited reinforcements lies in the fact that all the sides of the spiral are inclined, which results unacceptable from a planning point of view. In fact the reinforcement of the beams is aimed at absorbing the shear stresses so the lack of a perfect verticality of the tracts of the stirrup designed to be vertical turns out to be unacceptable.

[8] In the specific field, multiple solutions designed to improve the achievement of the spiral-reinforcements have been proposed. European patent application EP 0 452 246 describes a method applicable to bidimensional wire bending machines for manufacturing tridimensional metal reinforcements. Such method provides for the application of a twisting moment along the axis of the metal wire, so as to cause a permanent plastic deformation of the wire on the branch which supports the side just folded, in a way as to orient it in the space.

[9] European patent application EP 0 630 297 describes a method and a machine that allow to manufacture spiral-reinforcements. The metal wire is advanced in a straightening unit and is folded in a folding unit, wherein the spiral is produced perpendicularly downwards and leaves the production plane of the coils with the aid of the gravity. The produced coils are hosted in a collect device wherein the same coils are hold laterally and at the lower part, the collect device having variable capacity in correspondent way to the dimensions of the already produced coils.

[10] European patent EP 0 864 386 discloses a method and an apparatus for manufacturing spiral-reinforcements from a metal wire. Such apparatus is constituted substantially of a unit for folding the metal wire fixed on a movable frame which is shifted in the feeding direction of the same metal wire. The apparatus further comprises a device for collecting the coils that is moved perpendicularly to the fed metal wire direction and in the meantime rotates such as the angle of the coil produced in that moment be on the metal wire feed line.

[11] But such known apparatuses are structurally rather complex and further generally allow to manufacture reinforcements with leaning spiral, wherein by fact the pitch between the coils does not exist, or more precisely they do not provide for members able to achieve and control the width of the pitch. [12] Tridimensional wire bending machines are also known that, at the difference of the common bidimensional wire bending machines, are theoretically able to produce any type of tridimensional handmade article. Wire bending machines of this type are illustrated for example in the documents US 4,735,075, EP 0 231 092 and EP 0 396 489.

[13] In the tridimensional wire bending machines, the fold head acts as usual orthogonally to the longitudinal axis of the metal wire being worked but can also rotate about the axis of the same metal wire and so manufacture any spatial geometry. In other words, the fold head remains always orthogonal to the axis of the metal wire and rotating thereabout moves from a plane to the other of the infinite planes passing by the axis of the same metal wire. The main drawback of such solution lies in the fact that to manufacture a spiral, the fold head must be rotated incrementally about the axis, always in the same direction and without ever coming back in the initial position. Therefore the portion of achieved structure, which develops orthogonally to the work plane and in axis to the fold head, rotates as well about the axis of the metal wire. This means that such portion of structure cannot have large dimensions, since it is supported by the only rigidity of the metal wire being worked. So the tridimensional wire bending machines are suitable to manufacture also spiral-structures wherein also a pitch is achieved, provided that they have relatively limited longitudinal dimensions; instead they are not able to manufacture the normally required reinforcements, having dimensions of various meters, since during the formation they bend and consequently arrange in an uncontrolled way.

[14] European patent application EP 1469 135 discloses a process for manufacturing a so- called 'broken spiral' reinforcement, or otherwise said 'broken helix', schematically represented for more clearness in fig. 1. The spiral 21 isconstituted by a succession of tracts 22 substantially perpendicular and of tracts 23 substantially oblique with respect to the reinforcement longitudinal axis L, forming coil configuration with polygonal projection on a plane perpendicular to the same longitudinal axis L. In the illustrated case, the oblique tracts 23 appear inclined in directions opposite between them and on facing and parallel surfaces, but the path thereof is oriented in a way as to generate the extent of the spring always in a same direction with respect to the axis L of the same spiral.

[15] The broken spiral structure turns out to be more resistant with respect to the single stirrup traditional clamping because of the continuity present in the same reinforcement, in addition to respect the perfect verticality condition of the descending tracts in order to assure the maximum resistance to the beam shear stress; in fact in the traditional clamping with stirrups, lacking the continuity, it is necessary to manufacture overlaps, also said hooks, which in situation of critical stress always constitute a point of potential danger, for the possible aperture of the hooks with trigger of degenerative phenomena of the structure. Therefore with a broken spiral structure the cited exigencies are satisfied, improving the performance of the final handmade article, and ferrous material is saved because of the elimination of the overlapping hooks present in the stirrups.

[16] The aforementioned broken spiral reinforcement solves many drawbacks complained in the specific field. But the document EP 1 469 135 does not teach how to effectively manufacture such type of structure.

[17] Italian patent application BO2005A000609 describes a method and an apparatus that allow to manufacture, in an at least partially automated manner, broken spiral reinforcements for reinforced concrete, starting from a traditional spiral structure, constituted by a succession of coils with horizontal tracts having variable lengths leaning the ones on the others. The method provides for prearranging in a predetermined work position the leaning spiral structure and for grasping through grasping means at least part of a first coil of the structure. A relative movement of controlled width of the grasping means is then performed for manufacturing the divaricating of a first side of the first coil, through the permanent deformation of such first side of the first coil. The grasped sides of the first coil are released in order to perform the return of the grasping means in an idle position and the pitch feeding of the spiral structure is performed for positioning the successive coils at the plane of action of the grasping means and cyclically performing the divaricating of such coils, until completing the formation of a broken spiral reinforcement.

[18] Nevertheless such method and the relative apparatus require relatively high execution times. The broken spiral is in fact made from a leaning spiral of the traditional type that must be made separately by means of a different apparatus; moreover, during the execution, the expansion of the single leaning coils has to be performed, in order to obtain the desired pitch.

[19] It is further to note that the aforementioned apparatus results scarcely versatile, since it allows to manufacture uniquely broken spiral reinforcements and not spiral reinforcements of the traditional type.

[20] The successive Italian patent application BO2008A000030 discloses a method for manufacturing spiral reinforcements for reinforced concrete that provides for feeding a metal wire through a folding unit according to a predetermined longitudinal feed axis and for performing successive folds of such metal wire with respect to the longitudinal axis, in order to produce a succession of coils designed to form a spiral reinforcement. The produced coils are preferably directed downwards by gravity and collected in a collect device. At least a part of such folds is made inclining the folding unit with respect to the metal wire axis. This typology of machines turns out to be of little efficiency in controlling the pitch and so is not usable for the cited scopes. Disclosure of invention

[21] The task of the present invention is that of solving the cited problems, devising a method that allows to manufacture in a simple and efficient manner spiral reinforcements for reinforced concrete from a suitable metal wire.

[22] A further scope of the present invention is that of providing a method and an apparatus that allow to manufacture spiral reinforcements having suitably large extension.

[23] Another object of the present invention is that of providing an apparatus for manufacturing spiral reinforcements for reinforced concrete having a simple conception, a securely reliable functioning and a versatile use.

[24] The above mentioned scopes are attained, according to the present invention, by the method for manufacturing spiral reinforcements for reinforced concrete according to claim 1. Brief Description of the Drawings

[25] Details of the invention shall be more apparent from a detailed description of a preferred embodiment of the apparatus for manufacturing spiral reinforcements for reinforced concrete, illustrated for indicative purposes in the attached drawings, wherein:

[26] figure 1 shows a schematic perspective view of a so-called broken spiral reinforcement of the known type;

[27] figure 2 shows a front view of the apparatus for manufacturing spiral reinforcements for reinforced concrete according to the invention;

[28] figure 3 shows a magnified perspective view of the operative zone of the apparatus according to the invention;

[29] figures 4 - 9 show a perspective view of the operative zone of the apparatus, in successive operative phases;

[30] figures 10 and 11 show a front view of the operative zone of the apparatus, in successive operative phases;

[31] figure 12 shows a functional scheme of the aforesaid operative zone of the apparatus;

[32] figures 13 and 14 respectively show a perspective view and a plant view of different forms of coils feasible according to the method object of the present invention;

[33] figure 15 shows a perspective view of a broken spiral reinforcement manufactured according to the method object of the present invention. Best Mode of Carrying Out the Invention

[34] With particular reference to such figures, the apparatus for manufacturing spiral reinforcements for reinforced concrete starting from a metal wire 2, for example a reinforcing rod, is indicated in its entirety with 1.

[35] The apparatus 1 comprises suitable means for feeding the metal wire 2 according to a predetermined longitudinal feed axis A, preferably arranged horizontally. In the case illustrated in fig. 2, such means for feeding the metal wire 2 are usefully provided with the feeding device of a conventional wire bending machine, provided in a known way with suitable straightening members 3. Downstream of the feeding device, according to the feed direction of the metal wire 2, is provided a cutting unit 4 designed to perform the cutting off of the metal wire 2 at the end of the phase of manufacturing of the metal spiral.

[36] Downstream of the cutting unit 4, according to the feed direction of the metal wire 2, is arranged a folding unit 5 of the metal wire 2. The folding unit 5 is suitable to perform successive folds of the metal wire 2 with respect to the longitudinal feed axis A, to produce, one side after the other, a succession of coils 20 designed to form a spiral reinforcement, as better explained in the following.

[37] The folding unit 5 is provided with a fold head that provides for a central pin or mandrel 7 and an eccentric folding pin 8, having substantially vertical and parallel axis (see in particular fig. 3). The folding pin 8 has at its free end a tooth 9 which shapes a shouldering suitable to act on the metal wire 2 during certain folding phases. More precisely, such tooth 9 is suitable to perform a flexure of the metal wire 2 with respect to an abutting zone 10 preferably shaped in correspondence with the cutting unit 4, as explained in the following.

[38] To such end, according to the present invention, the folding pin 8 of the fold head is suitable to be shifted according to its own axis by means of suitable actuating members. Obviously it is possible to provide for the combined axial shifting of the mandrel 7 and of the folding pin 8.

[39] Under the folding unit 5 is arranged a device 12 for collecting the produced coils 20, with a substantially vertical axis. The collect device 12 is preferably of the type illustrated in patent application BO2008A000030 which is recalled here.

[40] Above the device 12 for collecting the produced coils 20, there are suitable to be arranged, in use, one or more substantially bracket-shaped support planes, on which the forming coils 20 are suitable to partially rest, so as to avoid the weight of the same forming coils 20 to weigh on the actuating unit. In the illustrated case there are provided a first and a second support plane 13, 14 horizontal and superimposed. The upper support plane 13 is arranged preferably just under the feed plane of the metal wire 2 according to the mentioned longitudinal feed axis A; the support planes 13, 14 can be vertically and/or horizontally movable, through suitable motor members 16, between an idle rear position and a work position advanced in correspondence with the coils formation zone. The support planes 13, 14 can further be also suitably shaped to favour the working in relationship with the geometry of the product to be made.

[41] The functioning of the apparatus for manufacturing spiral reinforcements for re- inforced concrete according to the method object of the present invention is described in the following.

[42] It is initially providedto set the dimensions of the space for containing the spiral to be manufactured inside the collect device 12, according to the overall dimensions and the geometry of the same spiral.

[43] The feeding of the metal wire 2 by the feed device 3 is then controlled, according to the predetermined longitudinal feed axis A defined by the apparatus (see fig. 4). The metal wire 2 engages the folding unit 5, where successive folds of the metal wire 2 are performed with respect to said longitudinal feed axis A, in order to produce a succession of polygonal coils 20 suitable to form a spiral reinforcement 21.

[44] More precisely, it is usually preferable to manufacture initially a first plane stirrup orthogonal to the longitudinal axis L of the reinforcement, otherwise said 'template stirrup'. To such end, the folding unit 5 first provides to carry out, in a known way, a series of folds of the metal wire 2 alternating feed phases of the same wire 2 with folding phases (fig. 5). Such folds in the plane are made, in a known way, thanks to the fact that the fold pin 8 is rotated about the mandrel 7 and the metal wire 2 interposed therebetween is then wound on the mandrel 7 by the folding pin 8; in folding phase the metal wire abuts in the channel defined by the fixed blade of the cutting unit 4. At the end of every folding phase, the folding pin 8 is brought back by rotation in the initial position, to allow the feed of the metal wire. So the folds manufactured in such way result lying in a plane containing the feed axis A of the wire 2 and orthogonal to the axis of the mandrel 7 and of the folding pin 8.

[45] After completion of such possible first coil, so-called template stirrup, it is provided to manufacture a series of successive polygonal coils 20, constituted by a sequence of tracts 22 substantially perpendicular with respect to the longitudinal axis L of the spiral reinforcement 21 and of tracts 23 substantially oblique with respect to the same longitudinal axis L, forming coil configurations with polygonal projections on a plane perpendicular to the aforesaid longitudinal axis L of the spiral reinforcement 21.

[46] According to the present invention, for the formation of the oblique tracts 23 of the spiral reinforcement 21 it is provided to carry out in ordered succession, that is in successive times, on at least one side of the polygonal coils 20, a first fold 23a on a plane orthogonal to the axis of the mandrel 7 and of the folding pin 8 and lying on a plane α perpendicular to the longitudinal axis L of the spiral reinforcement 21, and at least a second fold 23b extended in a third dimension suitably inclined with respect to the aforesaid plane α perpendicular to the longitudinal axis L of the spiral reinforcement 21 (see in particular fig. 15).

[47] More specifically, the second fold 23b extended in a third dimension is obtained further to a movement of flexure of the metal wire 2 on one of the planes containing the feed axis A of the same metal wire 2.

[48] Practically, the cited fold 23b extended in a third dimension is carried out in suitable phase relationship with a movement of axial shifting of the folding pin 8 of the fold head, such as to perform a flexure of the metal wire 2 on a vertical plane β containing the feed axis A of the metal wire 2 and parallel to the axis of the mandrel 7 and of the folding pin 8, levering on a suitable fixed abutting zone 10 (see also fig. 12). In fact the folding pin 8 has the tooth 9 shaped in such a way as to hook the metal wire 2 and with its own axial shifting movement to act on the same metal wire 2 to perform the aforesaid flexure on the vertical plane β; obviously the same effect can be obtained alternatively through an axial shifting of the mandrel 7, if suitably shaped.

[49] Preferably the cited abutting zone 10 is constituted by the fixed blade of the cutting unit 4, suitably profiled to such scope.

[50] More particularly, when the preceding stirrup is completed, the angular rotation of the folding pin 8is operated, for example of an angle of 90°, to make the first fold 23a on a plane orthogonal to the axis of the mandrel 7 and of the same folding pin 8. When the first fold 23a is made (fig. 10), the return of the folding pin 8 in the initial angular position and the successive movement of axial shifting of the same folding pin 8 upwards (fig. 11) is operated in order to determine the desired inclination of the plane of lying of the preceding coil with respect to the oblique tract to be formed. Obviously according to the width of the axial shifting of the folding pin 8 such inclination and as a consequence the pitch of the spiral will result larger or smaller, as can be schematically seen in fig. 12 where is indicated with S the inclined direction assumed by the metal wire further to the cited flexure on the vertical plane β.

[51] The folding pin 8 is then rotated angularly, to make the second fold 23b which will result always orthogonal to the axis of the mandrel 7 and of the folding pin 8 and consequently inclined with respect to the lying plane of the preceding coil (fig. 6).

[52] At this point the metal wire is fed along the axis A, in order to obtain the desired length of the tract determined by the fold 23b (fig. 7). When such tract is completed, the fold pin 8 is axially shifted downwards, to allow the manufacture, through successive folds, of a further tract 22 substantially perpendicular with respect to the longitudinal axis L of the spiral reinforcement 21 (see successively figures 8 and 9).

[53] In fact suitably shaping the tooth 9, for example with a shape of fork (see fig. 12), it is possible to obtain as well the downwards flexure of the metal wire 2 on the vertical plane β. Obviously in this case the folding pin 8 and/or the mandrel 7 must be axially shifted downwards. This allows to obtain a fold extended in the third dimension opposite to the preceding one.

[54] It is to note that, if the side designed to the fold extended in the third dimension has a relatively high inclination, such tridimensional fold can be constituted by two or more successive folds, also with different widths, obtained moving suitably the folding pin 8, possibly in combination with suitable feeds of the metal wire 2.

[55] In definitive, as schematically illustrated in fig. 15, is manufactured a broken spiral reinforcement 21 constituted by a succession of tracts 22 lying on a plane α substantially perpendicular to the longitudinal axis L of the same spiral reinforcement 21, forming coil configurations with polygonal projections perpendicular to the longitudinal axis, and of tracts 23 suitably inclined with respect to the aforesaid plane α perpendicular to the longitudinal axis L.

[56] It is to note that the sum of the first fold 23a made on a plane orthogonal to the axis of the mandrel 7 and of the same folding pin 8 and of one or more extended folds 23b, carried out in successive times, offers the advantage of not inducing rotation movements of the structure during the formation about the axis of the metal wire and of controlling the pitch with the desired precision.

[57] It is to note that such folds can be manufactured physically in the same tract of metal wire 2, even if in successive times, or in different times and positions, indifferently first the one then the other. But it is preferable to make the first fold 23a in plane and the second fold 23b in the third direction without making feeds of the metal wire 2 between the one and the other, so the two cited folds 23a, 23b will result at a distance in function of the overall dimensions and of the geometry of the members constituting the folding unit 5.

[58] In suitable phase relationship with the formation of the coils 20, the advancing of the support planes 13, 14 in the work position is controlled. In particular, the upper support plane 13 is suitable to support the coil 20 in formation, while the lower support plane 14, suitably distanced, supports the already formed coils 20. In particular, if the distance between the support planes 13, 14 is adjusted in a way as to match the pitch of the coil 20 in formation, the lower support plane 14 is suitable to support the previously formed branch of the coil 20, supporting the already formed coils 20 in suspension in the zone below the aforesaid plane. It is further possible to provide that the coils 20 which accumulate on the lower support plane 14 result progressively pressed against the upper support plane 13. The displacement of the support planes 13, 14 in the idle rear position determines the extension and the positioning of the coils 20 inside the collection device 12.

[59] This allows to move the collection device 12 in the position of extraction of the completed spiral while the formation of the coils of the successive spiral begins. Once the extraction of the spiral is executed, the collection device 12 is moved back in the work position below the coils formation zone. In other words, the extraction of the completed spiral occurs in so-called masked time during the initial phases of the formation of the successive spiral, substantially without interruption of the productive cycle.

[60] The method and the apparatus according to the invention attain the scope of manufacturing in a simple and efficient way spiral reinforcements for reinforced concrete from a metal wire. In particular it is possible to manufacture easily and in limited times continuous and broken spiral reinforcements, constituted by a succession of tracts substantially orthogonal and of tracts substantially oblique with respect to the reinforcement longitudinal axis.

[61] It is to note that the described apparatus allows to manufacture broken spiral reinforcements of any conformation, suitably varying the operative parameters. The apparatus further allows, if required, to manufacture spiral reinforcements of the traditional type and/or stirrups. More precisely, it is possible to provide for the apparatus to be provided with suitable actuating means suitable to orientate the work plane of the folding members in a substantially vertical way, so as to allow the manufacturing of traditional type plane stirrups.

[62] For example, in figures 13 and 14 are illustrated in comparison various forms of spirals that can be obtained with the method according to the invention. Particularly, the spiral 20 has on the upper side the cited fold 23b, suitable to define the oblique tract 23, and a corresponding fold 23b on the lower side to bring the successive tract 22 back on a plane orthogonal to the spiral axis. To the same aim, the coil 20a has instead at the end of the upper oblique tract 23 a contrary fold 23c, obtained by succession of two contrary shifts of the folding pin 8. The coil 20b has oblique tracts 23 as well on the upper side as on the lower side, obtained through analogous folds of the coil 20a, so as to manufacture a substantially double pitch.

[63] A characteristic of the invention lies in the fact that it allows the manufacture of spiral reinforcements having also relatively large extension. Such result is first due to the innovative idea of carrying out separately a fold in direction inclined with respect to the preceding folding plane. In fact this allows to have the control on the pitch to be made and very reduced movements of the forming spiral and consequently easier to control during the phase of collection and support of the forming product.

[64] At the end of the formation of the spiral, the reinforcement 21 can be pressed also automatically, with the coils 20 leaning the ones on the others, in a way as to be able to be stored and transported on the place of use in the minimum dimension configuration. The spiral reinforcement 21 is blocked in the aforesaid compact configuration through suitable binding or anchorage means preferably before being extracted from the collection device 12.

[65] It is also to note that the apparatus according to the invention has a high security level. In fact the apparatus does not require manual interventions so the productive process results completely automated and therefore considerably reduces the risks to which the operators in charge of the surveillance of the system are potentially exposed.

[66] A further advantage consists ofthe high constructive and functional simplicity of the apparatus according to the invention.

[67] In practice, the embodiment of the invention, the materials used, as well as the shape and dimensions, may vary depending on the requirements.

[68] Should the technical characteristics mentioned in each claim be followed byreference signs, such reference signs were included strictly with the aim of enhancing the understanding the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.

Claims

[Claim 1] 1) Method for manufacturing spiral reinforcements for reinforced concrete and the like, comprising the phases of:

(a), feeding a metal wire (2), according to a predetermined longitudinal feed axis (A), through a folding unit (5) provided with a central mandrel (7) and an eccentric folding pin (8), having substantially parallel axis;

(b). performing by means of said folding unit (5) successive folds of said metal wire (2) with respect to said longitudinal feed axis (A), to produce a succession of polygonal coils (20) designed to form a spiral reinforcement (21) constituted by a sequence of tracts (22) substantially lying on a plane (α) perpendicular to the longitudinal axis (L) of the same spiral reinforcement (21) and of tracts (23) substantially oblique with respect to said longitudinal axis (L) of the spiral reinforcement (21), forming coil configurations with polygonal projection on the plane perpendicular to said longitudinal axis (L) of the spiral reinforcement (21); characterized in that it provides for carrying out in ordered succession on at least one side of said polygonal coils (20), in order to form said oblique tracts (23) of the spiral reinforcement (21), (bl). a first fold (23a) on a plane orthogonal to the axis of said mandrel (7) and of said eccentric folding pin (8) and lying on said plane (α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21), and

(b2). at least a second fold (23b) extended in a third dimension suitably inclined with respect to said plane (α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21).

[Claim 2] Method according to claim 1 characterized in that it provides for carrying out said second fold (23b) extended in a third dimension further to a movement of flexure of said metal wire (2) on a plane (β) containing said feed axis (A) of the same metal wire (2) and parallel to the axis of said central mandrel (7) and of said eccentric folding pin (8).

[Claim 3] Method according to claim 2 characterized in that it provides for carrying out said second fold (23b) extended in a third dimension in suitable phase relationship with a movement of axial shift of said mandrel (7) and/or of said fold pin (8) of the folding unit (5), shaped in such a way as to act on said metal wire (2) to perform said flexure.

[Claim 4] Method according to claim 3 characterized in that it provides for performing said flexure of the metal wire (2) levering on an abutting zone (10) shaped by the fixed blade of a cutting unit (4) of the machine.

[Claim 5] Method according to claim 1 characterized in that it provides for manufacturing said first fold (23a) lying on said plane(α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21) and said second fold (23b) extended in a third dimension without performing an intermediate feed of said metal wire (2).

[Claim 6] Apparatus for manufacturing spiral reinforcements for reinforced concrete and the like, comprising a succession of polygonal coils (20) constituted by a sequence of tracts (22) substantially lying on a plane (α) perpendicular to the longitudinal axis (L) of the same spiral reinforcement (21) and of tracts (23) substantially oblique with respect to said longitudinal axis (L) of the spiral reinforcement (21), forming coil configurations with polygonal projections on a plane perpendicular to said longitudinal axis (L) of the spiral reinforcement (21), characterized in that it comprises a folding unit (5) provided with a central mandrel (7) and an eccentric folding pin (8), having substantially parallel axis, perpendicular to the longitudinal feed axis (A) of a metal wire (2) designed to form said spiral reinforcement (21), and suitable to carry out in ordered succession on at least a side of said polygonal coils (20), to form said oblique tracts (23) of the spiral reinforcement (21), a first fold (23a) on a plane orthogonal to the axis of said mandrel (7) and of said folding eccentric pin (8) and lying on said plane (α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21), and at least a second fold (23b) extended in a third dimension suitably inclined with respect to said plane (α).

[Claim 7] Apparatus according to claim 6, characterized in that said central mandrel (7) and/or said eccentric folding pin (8) are suitable to be operated with a movement of axial shift in order to determine a movement of flexure of said metal wire (2) on a longitudinal plane (β) containing said feed axis (A) of the metal wire (2) and parallel to the axis of said central mandrel (7) and of said eccentric folding pin (8), to carry out said second fold (23b) extended in a third dimension.

[Claim 8] Apparatus according to claim 7 characterized in that said folding pin (8) shapes a tooth (9) which forms a shouldering suitable to engage said metal wire (2) to determine said flexure movement.

[Claim 9] Apparatus according to claim 7 characterized in that said central mandrel (7) and/or said eccentric folding pin (8) are suitable to determine said flexure of the metal wire (2) levering on a fixed abutting zone (10).

[Claim 10] Apparatus according to claim 9 characterized in that said abutting zone (10) is constituted by the fixed blade of a cutting unit (4) of the machine.

[Claim 11] Apparatus according to claim 8 characterized in that said tooth (9) is shaped such as to allow producing said flexure of the metal wire (2) according to opposite directions with respect to said feed axis (A) on said longitudinal plane (β).

[Claim 12] Spiral reinforcement for reinforced concrete and the like, comprising a succession of polygonal coils (20) constituted by a sequence of tracts (22) substantially lying on a plane (α) perpendicular to the longitudinal axis (L) of the same spiral reinforcement (21) and of tracts (23) substantially oblique with respect to said longitudinal axis (L) of the spiral reinforcement (21), producing the pitch of the spiral and forming coil configurations with polygonal projection on a plane perpendicular to said longitudinal axis (L) of the spiral reinforcement (21); characterized in that said substantially oblique tracts (23) have a first fold (23a) on a plane orthogonal to the axis of said mandrel (7) and of said eccentric folding pin (8) and lying on said plane (α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21) and at least a second fold (23b) extended in a third dimension suitably inclined with respect to said plane (α) perpendicular to the longitudinal axis (L) of the spiral reinforcement (21).