METHOD AND APPARATUS FOR PRODUCING MESHES, IN PARTICULAR
MADE OF METAL
[01 ] The present invention relates to a method and an apparatus for making meshes, in particular metal meshes.
 Apparatuses for manufacturing meshes, in particular made of metal, which can be used, for example, for reinforcing reinforced concrete structures, for fencing or for other uses are known.
 The metal meshes are constituted by the union, for example by electro-welding, of a plurality of longitudinal elements, metal wires or rods, arranged parallel and appropriately distanced, transverse elements, metal wires or rods, generally arranged perpendicular to the longitudinal elements and appropriately distanced to each other.
 The known types of apparatuses usually include a feeding and advancement unit of the longitudinal elements, as well as a feeding and positioning unit for the transverse elements. The latter, in particular, can be fed in progress by reels and cut to size by cutting means, or fed already cut to a fixing station, in correspondence of which each transverse element is fixed to the plurality of longitudinal elements by means of welding means of known type.
 After fixing a transverse element, the longitudinal elements and, with them, the already welded transverse elements are brought forward by one pitch, so as to be able to free the welding station and to fix a following transverse element.
 The patent EP 1515810 disclose, for example, an apparatus for realizing a metal mesh, comprising a first feeding unit for advancing the longitudinal wires at pitch, a second feeding unit for arranging a transverse wire at a time in a first preparation position, a positioning apparatus for arranging the transverse wire in a second fixing position, and a welding unit for fixing the transverse wires to the longitudinal wires.
 However, the apparatuses of the known type do not fully meet the manufacture requirements. In particular, such apparatuses do not allow to realize in a quick and easy manner, or only with the use of very complex and cumbersome mechanical groups, metal meshes of any type, for example by fixing the transverse wires above or below the fed longitudinal wires.
 In particular in the field of the production of electro -welded meshes, the need to reduce the transport costs of the products is felt. More precisely, the meshes generally have a high bulk and a relatively low weight. To allow transport, the meshes are stacked horizontally on top of each other, thus quickly saturating the available volume, without
however reaching the maximum payload of the used vehicles. This circumstance considerably affects the cost for transferring the products. In order to reduce the encumbrance, it is therefore convenient to stack the meshes alternately, with the transverse wires alternately arranged below or above the longitudinal ones, in the stacked condition. In this way, the transverse wires of two overlapping meshes can be placed side by side, by simply staggering the same mesh panels, thus reducing the overall thickness of the stacked meshes. It should be pointed out that, in plants of the known type, wherein apparatuses producing meshes with transverse wires always on the same side with respect to the longitudinal wires operate, tilting units which operate the alternating tilting of the produced meshes are then used. However, these units are very expensive as well as cumbersome, and therefore affects negatively the production costs.
 Patent AT 215268 discloses a method and an apparatus for making metal meshes. In particular, the method provides for the realization of meshes with transverse wires arranged alternately above and below the feeding plane of the longitudinal wires, so as to allow the stacking of the meshes thus obtained by means of a translation motion. Following this motion, the transverse wires of a mesh are inserted into the space between the transverse wires of an overlapping mesh and, equally, the longitudinal wires are inserted into the empty space of longitudinal wires of overlapping meshes.
 However, in the apparatuses of the known types, times and modes of positioning the transverse wires at the respective position of fixing to the longitudinal wires, and therefore the efficiency of the production cycle are not entirely satisfactory.
Presentation of the invention
[1 1 ] The object of the present invention is to solve said drawbacks by devising a method and an apparatus for producing meshes, in particular made of metal, which allows to perform the operations of feeding the transverse wires in an effective, versatile and precise manner.
 Within the scope of this task, it is a further object of the present invention to provide an apparatus of simple constructional and functional design, provided with safe and reliable use, as well as a relatively economical cost.
 Said objects are achieved, according to the present invention, by the method for producing metal meshes according to claim 1 and by the apparatus according to claim 6.
 The method for making meshes according to the invention provides the steps of advancing a plurality of longitudinal wires by means of an advancement unit on an advancement surface, feeding by means of a feeding unit, in an appropriate phase relation, a transverse wire in correspondence of a fastening or joining position on said advancement surface, joining the longitudinal wires brought forward with respect to the transverse wire fed by means of an operating joining unit in correspondence of said f ixing
or joining position.
Said feeding unit comprises a plurality of loading devices, each being adapted to intercept a respective portion of wire at a pickup position and to transfer it to said fixing position.
Advantageously, the loading devices are movable by a transfer motion being transverse to the taken wire, to conduct the taken transverse wire to said fixing position.
The cyclic succession of said phases of advancement, feeding and joining creates a first mesh.
A prerogative of the invention consists of providing to operate according a positioning motion said feeding unit of the transverse wires, movable between a first operating configuration, on a portion of space with respect to said advancement surface, to a second operating configuration, on the opposite portion of space, so as to be able to feed by means of the same feeding unit a transverse wire from one side for a first mesh and from the opposite side with respect to the longitudinal wires brought forward, for a subsequent mesh.
This positioning motion allows to selectively carry out, preferably in alternating succession, a mesh with the transverse wires fixed on one side and a mesh with the transverse wires fixed on the opposite side, thus avoiding the use of tilting units present in the plants of the known type.
Advantageously, by means of this positioning motion, the feeding unit of the transverse wires crosses the advancement surface on which the longitudinal wires are brought forward.
Advantageously, such crossing occurs in correspondence of a free space determined between a completed mesh and the longitudinal wires of a mesh to be made, inserted specifically on the advancement surface itself or separated, for example by cutting means, from the longitudinal wires of the already realized mesh.
The method can in fact be realized advantageously both in the case where the longitudinal wires are fed already cut to the advancement surface, i.e. as pre-cut bars, and in the case where they are cut on the advancement surface itself, by means of said cutting means. Said cutting means can be arranged, for example, upstream of the joining unit. The passage of the feeding unit of the transverse wires through said advancement surface can advantageously take place in a suitable phase relation to the feeding motion, for unloading the already realized mesh, and / or inserting the longitudinal wires of the new mesh to be made on the advancement surface.
Brief Description of the Drawings
The details of the invention will become more evident from the detailed description of a preferred embodiment of the apparatus suitable to implement the method for making metal meshes, illustrated by way of example in the accompanying drawings, wherein:
 Figures 1 to 13 show a schematic side view of the apparatus according to the invention in successive operating steps of feeding and transferring of the transverse wires of a metal mesh being realized.
Embodiments of the invention
 With reference to Figures 1 to 13, 1 indicates the apparatus according to the invention for realizing, for example, metal meshes 2 (see Figure 1 ), by joining longitudinal wires 3, arranged parallel and suitably spaced apart, with respect to transverse wires 4, also arranged suitably spaced and, preferably, in a perpendicular manner with respect to said longitudinal wires 3.
 The apparatus 1 comprises an advancement unit 10 of the longitudinal wires 3, a feeding unit 20 of the transverse wires 4, as well as a joining unit 30 of the longitudinal wires 3 to the fed transverse wires 4 (see in particular Figure 1 ).
 The advancement unit 10 comprises actuating means, not shown in the figure, suitable for operating the advancement, preferably at pitch, of the longitudinal wires 3 on an advancement surface P along an advancement direction A.
 The advancement unit 10 preferably comprises guide members 1 1 suitable to guide the longitudinal wires 3 in a desired centre-to-centre and alignment condition on the advancement surface P. The centre-to-centre distance between the guide members 1 1 is preferably adjustable, to allow the realization of meshes of any kind.
 Each guide member 1 1 preferably forms a duct inside which a longitudinal wire 3 is inserted following the advancement on the advancement surface P. Each guide member 1 1 is preferably provided with a flared-shaped opening section 12 to facilitate said insertion.
[31 ] The joining unit 30 is arranged downstream of said advancement unit 10, according to said advancement direction A.
 The joining unit 30 is preferably a welding unit comprising a series of welding electrodes 31 , 32 arranged in a transverse manner to the preferably horizontal advancement surface P, on each side of the surface itself. More precisely, the joining unit 30 can comprise a first series of welding electrodes 31 , arranged above the advancement surface P, and a second series of welding electrodes 32, arranged below the same surface.
 Each pair of welding electrodes 31 , 32 is capable of welding a longitudinal wire 3 to at least one transverse wire 4 suitably overlapping thereto.
 In a known manner, each pair of welding electrodes 31 , 32 is movable relative to the advancement surface P, alternately between a rest configuration, in correspondence of which at least one of the welding electrodes 31 , 32 is separate from the advancement surface P, and an active configuration of welding, in correspondence of which said welding electrodes 31 , 32 are approached to the advancement surface P in such a way as
to clamp the elements to be joined, in the illustrated case, a longitudinal wire 3 to a transverse wire 4 overlapping the first. The series of welding electrodes 31 , 32 is connected to a respective electric power supply assembly, so as to operate, in a suitable phase relation to said welding configuration, the joining of the overlapping elements.
 The feeding unit 20 of the transverse wires 4 comprises a plurality of loading devices 21 , aligned in a transverse direction with respect to the advancement direction A, in a number which is sufficient to adequately support the transverse wires 4, in particular according to their length and to the respective section.
 Each loading device 21 is suitable for intercepting a transverse wire 4, already cut to size or continuously unwound and cut specifically, and for conducting it through a transfer motion which is transverse to the taken wire in a respective fixing position, interposed between the welding electrodes 31 , 32, as described in detail below. The transverse wire 4 preferably comes from feeding and / or unwinding means, arranged laterally to the advancement surface P, for example comprising a drawing and / or straightening device.
 Preferably, the transfer operations of each transverse wire 4 are carried out by means of loading devices 21 simultaneously to the operations for inserting the transverse wire 4 into the apparatus 1 , by means of said feeding and / or unwinding means, so as to optimize the times.
 More precisely, the transverse wire 4 may come from a portion P1 or from an opposite portion P2, with respect to the advancement surface P of the longitudinal wires 3, and thus arrive to the feeding unit 20 at an inlet position, correspondingly, on the portion P1 or on the opposite portion P2.
 The loading devices 21 are preferably aligned transversely to the advancement direction A of the longitudinal wires 3 and, preferably, are carried by the same support structure, not shown for simplicity.
 Advantageously, the same feeding unit 20 is selectively active both on the portion P1 of the advancement surface P and on the opposite portion P2.
[41 ] Preferably, the feeding unit 20 is movable with a positioning motion, preferably alternating, between a first operating configuration, in correspondence of which the loading devices 21 are positioned and operate from the portion P1 of space with respect to the advancement surface P, and a second operating configuration, in correspondence of which the same loading devices 21 are positioned and operate from the opposite portion P2 of space, with respect to the same advancement surface P.
 More specifically, the loading devices 21 are movable with said positioning motion, preferably alternating, between the said first operating configuration and said second operating configuration.
 Preferably, the advancement surface P is arranged horizontally and, in this case, the first
and second operating configuration of the loading devices 21 of the feeding assembly 20 are respectively arranged above and below the advancement surface P itself. Correspondingly, said portion P1 defines, in this case, the half-space above the advancement surface P, while the opposite portion P2 defines the half-space below.
Said supporting structure is preferably actuated for this purpose by respective actuating means, preferably by suitable transmission members, for example articulation members, so as to accomplish this positioning motion through the advancement surface P and thus bring the loading devices 21 from portion P1 to the opposite portion P2 with respect to the advancement surface P and vice versa.
Said positioning motion may be, for example, a motion at least partly circular, or a translational motion or a combination of these motions, in any case suitable to position the loading devices 21 correspondingly on the portion P1 or on the opposite portion P2.
The positioning motion of the feeding unit 20 is actuated in a suitable phase relation to the advancement motion of the longitudinal wires 3 in the advancement direction A, in order to avoid any interference of the same unit 20, in particular, with the elements 3, 4 of the produced or awaiting to be produced mesh 2.
In particular, the motion of the loading devices 21 can be actuated through the advancement surface P in the time interval between the realization of a mesh 2 and of the other.
The loading devices 21 can be positioned upstream or downstream of the joining unit 30. In fact, during this time interval, a free space S is determined on the same advancement surface P (see Figure 7), thanks to the advancement of the mesh 2 just completed and / or to the stopping of the longitudinal wires 3 possibly already inserted into the guide members of the advancement unit 10 for the realization of a subsequent mesh 2. This free space S is therefore suitable for the passage without interference of the feeding unit 20, from the portion P1 to the opposite portion P2 or vice versa, with respect to the advancement surface P. Therefore, in this time interval the longitudinal wires 3 are temporarily stopped upstream of the feeding unit 20, so during said positioning motion the feeding unit 20 does not interfere with them (see, in particular, Figures 6 to 1 1 ).
Each loading device 21 is for example made by means of a mobile gripping member 22, suitable for gripping, in a pick-up position B1 in correspondence of portion P1 and, respectively, in an opposite pick-up position B2 in correspondence of the opposite portion P2, a single transverse wire 4 and releasing it into said fixing position interposed between the welding electrodes 31 , 32, on the corresponding portion of the advancement surface P, then on portion P1 or on the opposite portion P2, depending on the case.
More precisely, when the transverse wire 4 is fed from the pick-up position B1 , the fixing position F1 is located on the portion P1 , to join the transverse wire 4 from a corresponding
side of the longitudinal wires 3, whereas when the transverse wire 4 is fed from the opposite pick-up position B2 the transverse wire 4 is joined to the longitudinal wires 3 on the respective opposite side, in correspondence of the opposite fixing position F2, arranged in the opposite portion P2.
The pick-up position B1 and the opposite position B2 are, for example, the positions wherein each transverse wire 4, respectively, is inserted into the apparatus 1 for producing meshes.
Alternatively, each transverse wire 4 can be inserted in different positions to be then transferred to said pick-up positions B1 , B2. In this case, the feeding unit 20 can advantageously integrate auxiliary storage members, suitable for storing the transverse wires 4 subsequently inserted and feeding them in a suitable phase relation to the loading devices 21 . The presence of said storage members therefore serves to optimize the production cycle, freeing the operations of inserting the transverse wires 4 in the apparatus 1 from the operations of feeding the same wires 4 to the joining unit 30 by the loading devices 21 . The mobile gripping member 22 is preferably made of a gripper member comprising a pair of cooperating jaws, actuated, for example by contrasting elastic means and / or suitable control means, for example with cams or other types, for receiving between them, in said pick-up positions B1 , B2, a respective transverse wire 4 and releasing it, in said fixing positions F1 , F2, for joining a respective longitudinal wire 3 on the corresponding side.
Basically, the mobile gripping member 22 is alternately movable between the respective backward pick-up position B1 , B2, and the respective advanced fastening position F1 , F2, wherein it is suitable to release the transferred transverse wire 4.
Advantageously, each loading device 21 can cooperate with an auxiliary member 23 which forms, for example, a retaining channel for each transverse wire 4 at the respective pick-up position B1 , B2.
The auxiliary member 23 preferably forms at least one retaining seat 24, open on the side facing the joining unit 30, associated, in correspondence of said side, with a removable closure element 25.
The removable closure element 25 can for example form a cap, alternately movable between a closed position, in correspondence of which it intercepts the open side of the retaining seat 24, and an opening position, in correspondence of which it is separated from the same opening, thus allowing the pick-up, by the mobile gripping device 22, of a transverse wire 4 which is housed inside the retaining seat 24 itself.
The removable closure element 25 can for example be movable according to an oscillation or translation motion or to a combination of the two motions.
The operation of the apparatus for automatically feeding elements of elongated shape
according to the invention is apparent from the foregoing disclosure.
 In an initial phase, a plurality of longitudinal wires 3 adapted to produce a specific mesh 2 is arranged on the advancement surface P. In particular, each longitudinal wire 3 is inserted inside a respective guide member 1 1 and is taken over by the advancement unit 10.
[61 ] Means for feeding the transverse wires 4 are suitably loaded with the material, already cut to size or unwinding from a reel and cut by cutting means arranged upstream of the feeding unit 20, to produce said mesh 2.
 The feeding unit 20 is therefore arranged in an operating condition, for example on the portion P1 of the advancement surface P, by operating appropriately the respective operating means of said positioning motion.
 The advancement unit 10 is then actuated so as to advance the longitudinal wires 3 on the advancement surface P, preferably at pitch.
 At the same time, the feeding unit 20 is operated to receive in the pick-up position B1 a first transverse wire 4, directly or indirectly, from said feeding means arranged upstream of the apparatus 1 and to transfer it in correspondence of the fixing position F1 , in correspondence of the joining group 30. In particular, the transverse wire 4 is taken over by the auxiliary members 23, held inside the retaining seats 24 suitably closed by the respective removable closing elements 25 arranged in the closed position (see Figure 2).
 In a suitable phase relation, the removable closing elements 25 are brought into the opening position, to allow the transverse wire 4 to be released to the mobile gripping members 22, arranged in the backward pick-up position (see Figure 3). More precisely, the movable gripping members 22, in correspondence of the pick-up position B1 , grip from the retaining seats 24 and subsequently retain the transverse wire 4, preferably by the contrast of elastic means, which keep the jaws of the same members in a closing position.
 Likewise, the removable closure elements 25 are pushed, preferably by contrast of the elastic means associated with them, in the opening position by the motion of the movable gripping members 22 when picking up the transverse wire 4.
 Subsequently, the transverse wire 4 taken from the mobile gripping members 22, in correspondence of the pick-up position B1 , is transferred to the fixing position F1 , interposed between the electrodes 31 , 32 (see Figure 4). The transverse wire 4 is thus overlapping the longitudinal wires 3 on the portion P1 of the advancement surface P.
 The union assembly 30 is then activated by tightening the transverse wire 4 overlapping the longitudinal wires 3. The movable gripping members 22 are then actuated in a return motion to the pick-up position B1 , by operating the release of the transferred transverse wire 4 (see Figures 5 and 6). The release of the transverse wire 4 to the fixing position F1 preferably occurs by contrasting said elastic means associated with the jaws of the
gripping members 22.
Subsequently, the longitudinal wires 3 are again advanced, by a stroke equal to the pitch of the mesh 2 being produced, in order to carry out a new joining cycle to a subsequent transverse wire 4, fed as described above.
The cycle comprising the steps of advancing the longitudinal wires 3, feeding and transferring each transverse wire 4, as well as mutual joining, is repeated until completion of the mesh 2 to be produced.
Subsequently, the completed mesh 2 is advanced on the advancement surface P, to move it away from the fixing position F1 . At the same time, preferably, the movable gripping members 22 are brought in correspondence of the pick-up position B1 (see Figure 6).
The feeding unit 20 of the transverse wires 4 is then actuated according to the positioning motion, passing through the advancement surface P. By virtue of this positioning motion, the feeding unit 20 of the transverse wires 4 is arranged on the opposite portion P2 with respect to the advancement surface P, for example, passing from a configuration which is above the same, to a configuration which is below. In order to operate this motion without interference with the longitudinal wires 3, possibly already loaded onto the advancement unit 10, it is possible to stop the longitudinal wires 3, while the completed mesh 2 is advanced, so as to determine the free space S on the advancement surface P, which is useful for the passage of the feeding unit 20.
In particular, the movable gripping members 22 with their respective auxiliary members 23 and possibly storage members, if present, carry, possibly holding a transverse wire 4 already inserted into them, are transferred from portion P1 to the opposite portion P2 (see figures 7 to 10).
A new cycle of advancement of the longitudinal wires 3, feeding and transferring of the transverse wires 4 from the opposite portion P2, and joining by the joining unit 30, can then be started with the same procedures as the previous one, for producing a new mesh 2 which will be specular to the one just completed.
In particular, the transverse wires 4 for the construction of the subsequent mesh 2 are supplied by the opposing portion P2 and are loaded by the auxiliary members 23 in correspondence of the opposite pick-up position B2.
The movable gripping members 22 then pick the transverse wires 4 up at the pick-up position B2, to transfer them to the opposite fixing position F2, on the opposite portion P2 with respect to the advancement surface P.
At the opposite fixing position F2, each transverse wire 4 of the new mesh 2 is clamped between the electrodes 31 , 32, released by the movable gripping members 22 and advantageously joined to the longitudinal wires 3 on the opposite side to the fixing one for
the mesh 2 previously disclosed (see Figures 1 1 to 13).
The method for producing meshes, as well as the apparatus capable of implementing it, according to the invention, therefore enables the production of meshes in a quick and effective manner.
In particular, the apparatus according to the invention allows to produce, in an alternate succession, metal meshes with transverse wires arranged alternately on one portion and on the opposite portion of the advancement surface P of the longitudinal wires 3.
This result is achieved, in a very compact manner, by the provision of a feeding unit of transverse wires which is movable with a positioning motion able to place it both on one side and on the opposite one, with respect to di advancement surface P of the longitudinal wires.
In the practical embodiment of the invention, the materials used, as well as shape and dimensions, may be any according to requirements.
Where the technical features mentioned in any of the claims are followed by reference numerals, these reference numerals are included to improve the comprehension of the claims only, and consequently they have no limiting effect on the object of each element identified by way of example by these reference numerals.