Abstract:
A method for forming metallic reinforcement cages for reinforced concrete includes a step of distribution of the stirrups within specific positioning and retaining means distanced lengthwise, the positioning and retaining means cooperating at least with a portion of the stirrups to clamp them in an erect position on a substantially vertical plane, a step of longitudinal positioning of the longitudinal rods on respective transverse arms, the transverse arms being longitudinally interposed between the means to position and retain the stirrups, a step of reciprocal connection of the longitudinal rods and the stirrups, a step of release of the cage from the positioning and retaining means, and a step of relative displacement in height between the transverse arms and the means to position and retain the stirrups so as to position reciprocally the longitudinal rods and the stirrups at various heights according of the design of the cage to be formed.

Description:
[0001]    This application is a divisional application of U.S. Ser. No. 09/529,031, filed Aug. 9, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention concerns a method to form metallic cages for reinforcement purposes and the relative device.  
           [0003]    The invention is employed to facilitate, accelerate and simplify the positioning of the stirrups and the longitudinal rods in metallic cages, and also the operations to attach the rods to the stirrups.  
           [0004]    The metallic cages as used with the invention are employed as reinforcement in load-bearing structures in reinforced concrete such as beams, pillars, foundations, etc.  
           [0005]    Metallic cages used in load-bearing structures in reinforced concrete comprise a plurality of longitudinal rods, normally round pieces, possibly ribbed and/or shaped, with which a plurality of transverse stirrups, distanced lengthwise, are associated.  
           [0006]    The stirrups can be of any shape whatsoever, for example polygonal, circular, in a mesh, etc., at least partly closed.  
           [0007]    In the state of the art, the metallic cages are assembled manually, for the most part, because, among other reasons, it is difficult to automate the assembly operations; these difficulties derive from the great variety of the structural characteristics of the metallic cages.  
           [0008]    The composition of the metallic cage varies both according to the geometry of the load-bearing structure where they are to be used, and also according to the stress to which the structures are subjected.  
           [0009]    Therefore, it often happens that metallic cages which are equivalent in size and geometry have to reinforced with a variable number of rods, or with reinforcement rods arranged differently inside the stirrup, or with stirrups having a differentiated interaxis.  
           [0010]    This causes considerable operating difficulties for the assembly workers who are obliged to perform continuous measurements before welding, with a high risk of error.  
           [0011]    Another considerable problem is the positioning of the longitudinal rods, which can reach lengths of as much as 12 meters and more, inside the stirrups, or inserting the stirrups outside the rods if the rods are already arranged positioned on trestles or other supporting means.  
           [0012]    A further considerable problem is to maintain the longitudinal rods and the stirrups in position during the welding and tying operations.  
           [0013]    Yet another problem is to ensure the axial alignment of the longitudinal rods.  
           [0014]    All these problems become even more important when the stirrups to be assembled are wide, because of the difficulty of positioning and supporting them in an erect position while the cage is being formed.  
           [0015]    There are solutions known to the art which use partly automated machines, or cage-producing machines, which limit the manual operations required for assembling the cage and make the operations for the workers easier.  
           [0016]    These machines comprise means to retain and position the longitudinal rods cooperating with movable means to transport and position the stirrups in a controlled manner.  
           [0017]    The movable means, as they move parallel to the longitudinal rods, allow the stirrups to be picked up and progressively distributed by the worker along the whole length of the cage.  
           [0018]    Although such machines are extremely efficient, they may be too complex, sophisticated and over-sized for requirements, they need heavy investment, equipping operations, complex systems to move and control them, large spaces for manoeuvring, and equipment which requires constant maintenance and constant attention by the workers.  
           [0019]    Moreover, in the case of very large metallic cages, the machines are unsuitable to support and stably maintain the stirrups to be assembled in an erect position, especially when the latter are very wide.  
           [0020]    Therefore, if on the one hand these machines meet the need of automating the construction of a metallic cage almost completely, on the other hand they have problems of expense, simplicity and practicality, both during construction and during use.  
           [0021]    U.S. Pat. No. 5,350,162 describes a device to form metallic cages comprising a plurality of pairs of retaining elements with a vertical development able to be reciprocally separated according to desired values in both a longitudinal and transverse direction, which serve to position the longitudinally separated stirrups in an erect position.  
           [0022]    The rods to be attached to the comers of said stirrups are inserted longitudinally inside the stirrups.  
           [0023]    This document does not provide in any way to vertically displace the rod support elements with respect to the stationary stirrups, or vice versa, in order to facilitate the positioning and attachment of the rods to the various vertical levels of the stirrups.  
           [0024]    Therefore, with this device, to position the rods at the highest levels inside the stirrup, at least two people need to raise one rod at a time, holding it at the end, and take it to the desired level, and a third person has to carry out the attachment operation; otherwise, the same person has to support the rod with one hand while at the same time he does the tying operation with the other hand.  
           [0025]    It is obvious that this operation not only necessarily requires the intervention of at least two people, but also involves a considerable physical effort and considerable care, with the risk on the one hand of making an unsatisfactory attachment and on the other hand of causing accidents, particularly in the case of very long and heavy rods.  
           [0026]    Another disadvantage comes from the fact that, if on the one hand there is no problem of positioning in the case when the rods are attached only in correspondence with the upper inner comers of the rod, on the other hand, in the case when the rods are positioned at one or more intermediate levels in height, a considerable problem is created concerning the accuracy of the positioning.  
           [0027]    In this case, which is the more frequent one in the production of metallic cages, the workers are obliged to take reference measurements on the sides of the stirrup according to the design specifications of the cage, and then try to respect these reference measurements while they are supporting long, heavy rods at the ends and tying them.  
           [0028]    EP-A-0.376.765 describes the use of identification elements to indicate the position where the stirrups have to be located with respect to the longitudinal rods.  
           [0029]    This document does not describe a method or a device to facilitate the formation of a metallic cage.  
           [0030]    The present applicants have designed, tested and embodied this invention to overcome the shortcomings of the state of the art with a solution which combines efficiency, practicality, versatility, flexibility and economy, and also to obtain further advantages as will be shown hereinafter.  
         BRIEF SUMMARY OF THE INVENTION  
         [0031]    The purpose of the invention is to provide a device to form metallic cages which will accelerate, simplify and rationalise the operations to position the rods and stirrups, whatever their size, and also the operations of welding or tying in the assembly steps.  
           [0032]    The invention also makes possible to vary the interaxis between the stirrups extremely quickly, and to position the longitudinal rods in the correct positions established by the design plans of the cage, without carrying out manual measurements which often cause errors and lead to time being wasted.  
           [0033]    The invention uses a plurality of seatings for means to position and retain the stirrups; the seatings are distributed lengthwise along the length of the cage to be formed.  
           [0034]    Moreover, the invention includes means to support and position the longitudinal rods of the cage to be assembled; these means are arranged at intervals along the length of the cage.  
           [0035]    The seatings for means to position and retain the stirrups are arranged lengthwise with a pre-defined interaxis, either fixed or variable, and cooperate with marker means which identify the position of the stirrups to be inserted according to the design specifications of the cage to be made.  
           [0036]    In a first embodiment, the marker means are manual and the workman applies a marker element from time to time in correspondence with the seating where the stirrup is to be inserted.  
           [0037]    According to a variant, the marker means are commanded by remote control means and consist of visual indicators which light up in correspondence with the seating where the stirrup is to be inserted.  
           [0038]    According to a further variant, when the worker prepares to begin the first cage in a series of identical cages, he inserts the individual stirrups, which causes the light signal to be activated; at the end of the series the light signal is cancelled.  
           [0039]    In another embodiment, the marker means consist of a chain, belt, conveyor, etc., which can move lengthwise to the frame of the device, to which a marker element is attached; the chain, belt, conveyor, etc. is stopped from time to time, to arrange the marker element in the position where the stirrup is to be inserted.  
           [0040]    In a variant of the invention, the interaxis between the housing seatings is a sub multiple of a range of defined interaxes of the stirrups.  
           [0041]    In one embodiment of the invention, the interaxis is 50 mm.  
           [0042]    According to a variant, to form cages with stirrups closer together the interaxis is 25 mm.  
           [0043]    According to a variant, all the available seatings are occupied by means to position and retain the stirrups, of which only some are used during the formation of the cage; those to be used are identified by the marker means.  
           [0044]    In a referential form of this embodiment, the means to position and retain the stirrups are made on profiles arranged between the means to support and position the longitudinal rods.  
           [0045]    According to another variant, the means to position and retain the stirrups can be extracted from the relative housing seating and are positioned from time to time in the appropriate seatings identified by the marker means.  
           [0046]    According to a further variant, the means to position and retain the stirrups can slide along guides which are longitudinal to the machine and are positioned from time to time according to the marker means.  
           [0047]    In this last embodiment, only a limited number of means to position and retain the stirrups are needed compared with the range of interaxes which the stirrups have to assume along the cage.  
           [0048]    In one embodiment, the means to position and retain the stirrups consist of a pair of adjacent sections defining a channel to contain the stirrups.  
           [0049]    According to the invention, one of the adjacent sections is stationary and one is movable.  
           [0050]    According to a variant, the sections are both movable.  
           [0051]    During the initial positioning step, the two elements are placed at a distance from each other to allow the stirrups to be inserted easily; the latter are arranged as desired on a substantially vertical plane inside the containing channel.  
           [0052]    When the initial positioning has been concluded, the positioning and retaining means are clamped against the stirrup, locking it into the erect position lying on a plane substantially orthogonal to the longitudinal plane of the cage to be formed.  
           [0053]    According to a variant, the positioning and retaining means consist of a single angle section, the rear part of which is cone-shaped and serves for positioning.  
           [0054]    The means to support and position the longitudinal rods consist of a plurality of transverse arms orthogonal to the axis of the cage and arranged at intervals on a plane substantially parallel to the lower plane on which the cage lies.  
           [0055]    According to a first embodiment, the transverse arms, which are interposed between the means to position and retain the stirrups, are movable at least vertically so as to position the longitudinal rods in cooperation with the stirrup at various heights during the attachment steps.  
           [0056]    According to a variant, the means to vertically move the transverse arms are associated with means to measure and display the movement.  
           [0057]    According to a further variant, there are seatings to guide the longitudinal rods on the transverse arms.  
           [0058]    According to another variant, the transverse arms are lined with wear-resistant material.  
           [0059]    According to another variant, the transverse arms can be associated with extension elements of the rapid replacement type which allow the longitudinal rods to be positioned and supported in a suitable manner even when the cage has a considerable width.  
           [0060]    The extension elements are of different lengths and are used according to the width of the cage to be formed.  
           [0061]    According to a variant, the transverse arms are stationary while the means to position and retain the stirrups are movable vertically to obtain the reciprocal positioning in height of the longitudinal rods and the stirrups during the step of forming the cage.  
           [0062]    According to the invention, the procedure to form the cage is as follows: first the stirrups are inserted, at an interaxis given by the design specifications, into the relative positioning and retaining means, which means are identified by the marker means.  
           [0063]    Then, the transverse arms are slightly raised with respect to the lower plane of the stirrup.  
           [0064]    In the case when the arms are stationary, all the stirrups are slightly lowered with respect to the plane defined by the transverse arms.  
           [0065]    This relative movement in height of the stirrups and rods facilitates the insertion of the longitudinal rods inside the area defined by the stirrups, and avoids the risk of blockages or of the rods being obstructed.  
           [0066]    When all the longitudinal rods have been inserted, the transverse arms are lowered again, or the stirrups are raised, resting all the rods on the side or lower segment of the stirrups.  
           [0067]    The longitudinal rods are then all axially aligned lengthwise, using abutment elements arranged in cooperation with one end of the device, advantageously the forward end.  
           [0068]    Then, all the longitudinal rods are taken substantially to the highest level of attachment required by the design of the cage, thus making it possible to begin the operations of attaching, welding, tying etc. the rods to the stirrup.  
           [0069]    These operations are consequently much simpler, as the longitudinal rods rest on the transverse arms at the desired height with respect to the stirrups.  
           [0070]    When the operation to attach the rods in a high position between inside the stirrup is concluded, the reciprocal position of the stirrups with respect to the rods is varied until all the desired reciprocal positions are obtained, thus allowing the reciprocal attachment to be achieved.  
           [0071]    In order to attach one or more longitudinal rods in correspondence with the segment of the stirrup which cooperates with the means to position and retain the stirrups, the cage formed at that point can be partly extracted at the side, freeing said segment of stirrup and enabling the relative longitudinal rod to be attached in said position.  
           [0072]    According to a variant, the device has in an adjacent position a base with a sliding plane for a trolley to carry the stirrups or to support a welding machine; the sliding plane may include guide means for the trolley.  
           [0073]    According to another variant, on the base there is a longitudinal supporting element to support stirrups which protrude at the side for a large segment of the lateral bulk of the device to form the cage.  
           [0074]    According to a further variant, the longitudinal supporting element is movable transversely on the base so as to adapt its position according to the width of the stirrups to be supported.  
           [0075]    According to a further variant, the longitudinal supporting element is attached to the base which can be moved in a transverse direction to the frame of the device to form cages.  
           [0076]    In a first embodiment, the longitudinal supporting element, or the base, is moved manually.  
           [0077]    According to a variant, it is moved by automated means.  
           [0078]    The longitudinal supporting element allows the stirrups to be supported securely and therefore to be positioned more stably in their erect position; this is particularly useful when the stirrups tend to fall onto the working plane due to their width, their weight and their vertical arrangement.  
           [0079]    According to a variant, the longitudinal supporting element has auxiliary positioning and retaining means arranged at the front, in a number mating with the positioning and retaining means on the opposite side of the device according to the invention; in this embodiment the marker means may be included on the longitudinal element also. 
       
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0080]    The attached Figures are given as a non-restrictive example and show some preferential embodiments of the invention as follows:  
         [0081]    [0081]FIG. 1 shows a perspective view of the device to form metallic cages according to the invention in the first step of the cage-forming cycle;  
         [0082]    [0082]FIG. 2 shows the device of FIG. 1, in the embodiment with movable arms and stationary stirrups, in a different step of the cage-forming cycle;  
         [0083]    [0083]FIG. 3 shows the device of FIG. 1 with the finished cage;  
         [0084]    [0084]FIG. 4 shows in part and diagrammatically a front view of the device to form cages according to the invention;  
         [0085]    [0085]FIG. 5 shows in part and diagrammatically a view from above of the device to form cages according to a variant of the invention;  
         [0086]    [0086]FIG. 6 shows a variant of FIG. 2 in the embodiment with stationary arms and movable stirrups;  
         [0087]    [0087]FIG. 7 shows a front view of a further embodiment of the device to form cages according to the invention;  
         [0088]    [0088]FIG. 8 shows a view from above of a detail of the device in FIG. 7.  
         [0089]    [0089]FIG. 9 is a view from above of a preferential embodiment of the device to form cages according to the invention;  
         [0090]    [0090]FIG. 10 is a side view of the device to form cages of FIG. 9;  
         [0091]    [0091]FIG. 11 shows a detail of the device to form cages according to the invention;  
         [0092]    [0092]FIG. 12 shows an extension for transverse arms of the device to form cages according to the invention;  
         [0093]    [0093]FIG. 13 is a front view of the device to form cages shown in FIG. 9;  
         [0094]    [0094]FIGS. 14 a - 14   b  show the means to retain and position the stirrups of the device to form cages shown in FIG. 9;  
         [0095]    [0095]FIG. 15 is a diagram seen from above of a detail of the means to retain and position the stirrups shown in FIGS.  13 - 14 ;  
         [0096]    [0096]FIG. 16 is a view from A of FIG. 15. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0097]    With reference to the attached Figures, the number  10  denotes generally the device according to the invention to form metallic cages  11  for reinforcement comprising a plurality of longitudinal rods  13  associated with stirrups  12  placed transversely across the rods  13  and separated from each other according to pre-defined interaxes.  
         [0098]    The device  10  comprises substantially a supporting frame  14 , the length of which is correlated to the cage  11  which is to be formed; a plurality of seatings  15  for means  20  to position and retain the stirrups  12  are arranged on the frame  14 . The seatings  15  develop substantially along the entire length of the supporting frame  14  and are arranged at an interaxis “i” correlated to the interaxis of the stirrups  12  to be arranged.  
         [0099]    In the case described here, the stirrups  12  are rectangular; however, it is evident that the invention is applied equally well in the case of stirrups  12  which are circular, square, polygonal, meshed or any other desired shape, provided they are of a size which is compatible with the size of the positioning and retaining means  20 .  
         [0100]    In a preferential embodiment, the interaxis “i” has a value equal to a common sub multiple of a desired range of interaxes of the stirrups  12 .  
         [0101]    According to one embodiment of the invention, the interaxis “i” is 50 mm.  
         [0102]    According to a variant, the interaxis “i” is 25 mm.  
         [0103]    Each of the housing seatings  15  is associated with a visual marker element  16  which can be activated individually; the marker elements  16  are suitable to indicate the seatings  15  in correspondence with which the stirrups  12  are to be placed according to the design specifications of the cage  11  to be formed.  
         [0104]    In a first embodiment as shown in FIGS. 4 and 8, the marker elements  16  consist of LEDs  17 .  
         [0105]    According to the variant shown in FIGS. 5, 14 a ,  15  and  16 , the marker elements  16  consist of pins  18  which can be inserted into mating holes  19  located in correspondence with each of the housing seatings  15 .  
         [0106]    According to a variant which is not shown here, the marker elements consist of a pin associated with a device arranged parallel and near the frame  14 , for example of the chain type, which displaces the pin lengthwise to the device and stops it automatically in the positions where the worker has to insert the stirrup  12 .  
         [0107]    In the specific case as shown in FIGS.  1 ÷ 8 , the positioning and retaining means  20  cooperate with a comer portion of the stirrup  12 ; the stirrups  12  can be supported at the lower part by supporting means  34 , shown in FIGS. 7 and 8 and in this case consisting of tubular elements, solid with the supporting frame  14  and defining the base plane of the cage  11  to be formed.  
         [0108]    In the embodiment shown in FIGS.  1 ÷ 4  the positioning and retaining means  20  are permanently constrained to the relative housing seatings  15 .  
         [0109]    In this embodiment, each positioning and retaining means  20  consists of a pair of sections, one stationary  21  and one movable  22 , between which the stirrup  12  is arranged and clamped.  
         [0110]    In this case, the stationary section  21  consists of an angle piece closed at the rear.  
         [0111]    The movable sections  22  consist of plates associated with supports connected to moving means, which are not shown in detail here.  
         [0112]    The moving means are advantageously shared by all the movable sections  22  and are activated by commands  23  on the control console  24 .  
         [0113]    Moving the movable sections  22  from a first, wider position (show by a line of dashes) to a second, closed position (shown by a continuous line), pushes and clamps the stirrups  12  against the stationary section  21 .  
         [0114]    With the movable sections  22  in the second position, the stirrups  12  are clamped in a substantially erect position orthogonal to the longitudinal plane on which the cage  11  to be formed lies.  
         [0115]    According to the variant shown in FIG. 5, the positioning and retaining means  20  can be removed from their relative housing seating  15 , to allow them to be used in the appropriate number from time to time as necessary to clamp the stirrups  12  of the cage  11  to be formed.  
         [0116]    In this embodiment, each positioning and retaining element  20  consists of a section  25  defining an insertion cavity  26  for the stirrup  12 , the section  25  can be coupled and fitted into the relative housing seating  15 .  
         [0117]    The rear wall  26   a  of the insertion cavity  26  has a cuneiform development against which the stirrup  12  is pushed and clamped in contact in a position substantially orthogonal to the longitudinal plane on which the cage  1  lies.  
         [0118]    According to a variant which is not shown here, there is a thruster element which pushes every stirrup  12  inside the section  25  and causes it to be clamped.  
         [0119]    According to another variant, the stirrup  12  is clamped by the cuneiform base  26   b  of the insertion cavity  26 .  
         [0120]    According to yet another variant, both the base  26   b  and the rear wall  26   a  of the insertion cavity  26  are cuneiform in development.  
         [0121]    By using removable positioning and retaining means  20 , when the construction plans of the cage  11  so ordain, it is possible to use stirrups  12  of different diameter, using sections  25  of different width or with a more or less tapered cuneiform segment.  
         [0122]    In the case of FIG. 5, for example, the central section  25  is wider than the lateral sections  25 .  
         [0123]    In the embodiment shown in FIGS. 7 and 8, the positioning and retaining means  20  consist of sections  25  substantially identical to those of FIG. 5.  
         [0124]    The sections  25 , in this case solidly associated with the supporting frame  14 , are arranged with the interaxis “i” close together, to allow the formation of cages  11  with stirrups  12  likewise particularly close together.  
         [0125]    In the preferential form of embodiment shown in FIGS.  9 - 16 , the positioning and retaining means  20  consist of wedge-shaped hollows  47  made respectively on a plurality of L-shaped lateral profiles  46   a  and on a mating plurality of lower flat profiles  46   b.    
         [0126]    The wedge-shaped hollows  47  have a limited interaxis “i”, advantageously of 25 mm, so that it is possible to make cages  10  with substantially any design specifications.  
         [0127]    The stirrups  12  come into contact with the wedge-shaped hollows  47  and are clamped therein.  
         [0128]    The L-shaped lateral profiles  46   a  (FIG. 14 a ) extend substantially for the entire length of the device  10  so as to define two parallel and facing rows of wedge-shaped hollows  47  and are suitable to receive the stirrups  12  from above, cooperating with the respective vertical segments of the stirrups  12  and clamping the stirrups  12  in position so that they do not oscillate on the vertical plane.  
         [0129]    The lower flat profiles  46   b  (FIG. 14 b ) extend on a plane below that of the L-shaped lateral profiles  46   a  for the whole length of the device  10  and are suitable to cooperate with the lower horizontal segment of the stirrups  12 , defining the supporting plane (FIGS. 15 and 16) on which the stirrups  12  rest.  
         [0130]    This embodiment makes it extremely quick and easy to insert and position the stirrups  12  along the device  10 , and also guarantees that the stirrups  12  are stably clamped in an erect position, which makes the subsequent welding of the longitudinal rods  13  considerably easier and more precise.  
         [0131]    The device  10  according to the invention, moreover, comprises a plurality of transverse arms  27  to support the longitudinal rods  13  arranged in a line and at intervals along the supporting frame  14 .  
         [0132]    The transverse arms  27  are positioned at desired intervals, provided that they guarantee an efficient support for the longitudinal rods  13 , and are arranged between the housing seatings  15 .  
         [0133]    In the embodiment shown in FIGS. 9 and 10, the transverse arms  27  are arranged at an intermediate position between the L-shaped lateral profiles  46   a  and the lower flat profiles  46   b , each of the L-shaped lateral profiles  46   a  and the lower flat profiles  46   b  extending for a length equal to the net gap between two of the transverse arms  27 .  
         [0134]    The transverse arms  27 , in the embodiment shown in FIGS.  1 ÷ 3  and  7 ÷ 13 , can be moved from a lowered position, wherein they lie substantially on the base plane of the cage  11 , to a position wherein they are completely raised and which defines the maximum height of the cage  11  itself.  
         [0135]    This maximum height corresponds to a value which allows the worker  35  to carry out the operations of attachment, welding or tying in a comfortable and operationally functional manner.  
         [0136]    The transverse arms  27  moreover are arranged in an intermediate position between the supporting means  34  for the stirrups  12 , in such a way as to not interfere therewith.  
         [0137]    In the specific case of FIGS.  1 ÷ 3 , the transverse arms  27  are associated at the lower part with a connection beam  28  and include stiffening rods  29  which prevent them from bending when they have a considerable weight to support.  
         [0138]    In the embodiment shown in FIGS.  11 - 13  the transverse arms  27 , which in this case too are attached to a connection beam  28 , are able to be associated with extension elements  50  which allow the longitudinal rods  13  to be suitably supported and positioned whenever the cage  11  is of considerable width.  
         [0139]    The extension elements  50  (FIG. 12) are of the type which can be replaced quickly; they are of variable length, and therefore are interchangeable according to the width of the cage  11  to be formed.  
         [0140]    To be more exact, in correspondence with one end, the extension elements  50  have a groove  48  opening upwards into which horizontal attachment pins  49 , solid with the transverse arms  27 , are suitable to be inserted.  
         [0141]    When the extension elements  50  are in a position of association with the attachment pins  49 , they are aligned at their upper part with the transverse arms  27  and are supported below by the said transverse arms  27  (FIG. 11).  
         [0142]    The extension elements  50  are removed simply by rotating them upwards and releasing them from the relative attachment pin  49 .  
         [0143]    According to a variant which is not shown here, at their upper part the transverse arms  27 , and/or the extension elements  50 , have guide elements suitable to assist the insertion and positioning of the longitudinal rods  13 .  
         [0144]    According to another variant the transverse arms  27  and/or the extension elements  50  are lined on the upper part with a wear-resistant material, in order to limit the deterioration caused by the sliding of the longitudinal rods  13 .  
         [0145]    In a preferential embodiment, the lining is of the type which can be replaced.  
         [0146]    The transverse arms  27  are displaced upwards by means of the controls  23  on the control console  24 , and the entity of the displacement is displayed on a graduated rod  30  which, in the case shown in FIGS.  1 ÷ 3 , is associated with the first of the transverse arms  27  and cooperates with a reference indicator  31  which is solid with the supporting frame  14  (FIGS.  1 ÷ 3 ).  
         [0147]    In the variant shown in FIG. 11 the graduated rod  30  is frontally associated with the supporting frame  14  and cooperates with an indicator  31  attached to the connection beam  28  of the transverse arms  27  and aligned with the upper profile  27   a  thereof.  
         [0148]    When the transverse arms  27  are in the lowered position, the upper profile  27   a , and therefore the indicator  31 , are aligned with the “zero” of the graduated rod  30 .  
         [0149]    In the embodiment shown in FIG. 7, each transverse arm  27  is solidly associated with a relative trolley  36 , which is able to slide by means of wheels  36   a  on a guide rod  37  with a vertical development which is solid with the supporting frame  14 .  
         [0150]    The trolley  36  is constrained to a chain  38  cooperating with a guide pulley  39   a , solid with the supporting frame  14 , and with a traction pulley  39   b  solid with an actuator  40  with vertical movement.  
         [0151]    According to the position of the actuator  40 , the chain  38  slides along the guide pulley  39   a  and causes the trolley  36  to move on the guide rod  37  and therefore positions the transverse arms  27  in the desired position.  
         [0152]    In this case, the device  10  is associated with a raised side base  32  on which the worker  35  may stand in order to perform the operations to form the cage  11  in a more comfortable position.  
         [0153]    There may also be, on the side base  32 , a movable trolley, possibly mounted on the appropriate guide means, for the initial transport of the stirrups  12  or of technical equipment; this allows the stirrups  12  to be distributed more quickly and easily, and more in general, it facilitates the operations to assemble the cage  11 .  
         [0154]    There is a longitudinal supporting element  41  for wide stirrups  12  on the base  32 .  
         [0155]    The longitudinal supporting element  41  comprises a base structure  42  whose function is to support the stirrups  12  in correspondence with the side opposite that where the stirrups are clamped by the positioning and retaining means  20 .  
         [0156]    In this case, the base structure  42  is associated in such a way as to slide transversely to the base  32  on a guide  43 , so that the longitudinal supporting element  41  can be moved from a first remote position on the base  32  to a position closer to the positioning and retaining means  20 ; the longitudinal supporting element  41  can thus be arranged in the desired position according to the transverse size of the stirrups  12  to support.  
         [0157]    In the embodiment shown here, the longitudinal supporting element  41  is moved manually by the worker  35 .  
         [0158]    According to a variant, it can be moved in an automated manner.  
         [0159]    In this case, moreover, auxiliary retaining means  44  are mounted on the base structure  42 , by means of L bars  45 , and consist of sections  25  substantially identical to those of the positioning and retaining means  20 .  
         [0160]    The auxiliary retaining means  44 , into which the stirrups  12  are inserted during the positioning step, allow the stirrups  12  to be maintained more stably in an erect position, and at the same time guarantee a secure support.  
         [0161]    In the embodiment shown in FIGS. 9, 10 and  13 , the system to move the transverse arms  27  is substantially the same as that shown in FIG. 7, but in this case there are only two trolleys  36  associated with the connection beam  28 , sliding on respective guide rods  37  on the ends of the device  10 .  
         [0162]    In this embodiment, the device to form cages  10  comprises two side bases  32 , one stationary  32   a , arranged between the guide rods  37 , and one movable  32   b , on the opposite side, on which the longitudinal support element  41  is associated.  
         [0163]    The movable side base  32   b  is able to slide on guides  51  arranged transverse to the supporting frame  14  in order to adapt its position according to the width of the cage  11  to be formed.  
         [0164]    In this case, the movable side base  32   b , which rests on the ground on rollers  53 , is moved manually by means of a hand wheel  52 .  
         [0165]    According to a variant which is not shown here, the system to move the movable side base  32   b  is of the driven type.  
         [0166]    The longitudinal support element  41  comprises in this embodiment a base structure  42  on which a plurality of aligned L-shaped lateral profiles  46   a  and lower flat profiles  46   b  are mounted, mating with the corresponding profiles  46   a  and  46   b  associated with the supporting frame  14  of the device  10 .  
         [0167]    When the movable side base  32   b  is displaced transversely according to the width of the stirrups  12 , all the elements to support the stirrups  12  are also displaced, making these operations to adapt the size and the subsequent operations to insert and pre-arrange the stirrups extremely rapid.  
         [0168]    There are marker elements  16  also on the movable side base  32   b , which makes it easier to position the stirrups  12 .  
         [0169]    There is also a rail  55  on the movable side base  32   b ; there is a trolley  54  assembled to slide thereon, which is suitable to support the welding device which can thus be taken to the most convenient position to carry out welding operations.  
         [0170]    This configuration of the device  10  is extremely advantageous because it allows the operator  35  to perform the various steps of forming the cage  11  standing on the side bases  32   a  and  32   b  arranged on both sides thereof.  
         [0171]    The inclusion of a longitudinal support element  41 , stationary with respect to the movable side base  32   b , gives the operator  35  greater ease of operation even when the cages  11  are of considerable width.  
         [0172]    According to the variant shown in FIG. 6, the device  10  comprises vertically fixed transverse arms  27 ; in this embodiment the stirrups  12  are moved vertically from the start position as shown in FIG. 1 to a maximum low position wherein their upper side is arranged substantially to support the longitudinal rods  13  which rest on the transverse arms  27 .  
         [0173]    The procedure to form the cage  11  is as follows: first the stirrups  12  are introduced into the positioning and retaining means  20  indicated by the marker means  16 , and the stirrups  12  are clamped in an erect position substantially orthogonal to the longitudinal plane on which the cage  11  lies by closing the positioning and retaining means  20  of the type as per FIG. 4, or by thrusting the stirrups  12  into the cuneiform seating if the positioning and retaining means  20  are of the type as shown in FIGS. 5, 7,  8  and  14   a - 16 .  
         [0174]    Subsequently, the longitudinal rods  13  are introduced inside the area defined by the stirrups  12 ; at this stage the transverse arms  27  are slightly raised with respect to their lowered position, or the stirrups  12  are slightly lowered, to allow the longitudinal rods  13  to be inserted better, with no risk of their knocking against the stirrups  12 .  
         [0175]    Then the transverse arms  27  are lowered again, or the stirrups  12  raised, and the leading ends of the longitudinal rods  13  resting on the stirrups  12  are aligned by means of an abutment element  33 , in this case consisting of an oscillating rod associated with the forward end of the supporting frame  14  (FIG. 1).  
         [0176]    The transverse arms  27 , in the embodiment shown in FIGS. 2 and 3, are then raised until they take the longitudinal rods  13  to abut internally on the upper side of the stirrups  12  in correspondence with which the longitudinal rods  13  are attached, by welding or tying, in the number and position required (FIGS. 2, 4 and  7 ).  
         [0177]    This operation of attachment is facilitated since both the stirrups  12  and the longitudinal rods  13  are maintained in position, respectively by the positioning and retaining means  20  and the transverse arms  27 , so that the worker  35  has his hands free to perform the operations.  
         [0178]    Afterwards, as shown by the line of dashes in FIG. 4, the transverse arms  27  are progressively lowered and are arranged at the intermediate levels wherein the longitudinal rods  13  will possibly be attached.  
         [0179]    The entity of this downward movement is displayed on the graduated rod  30 , thus allowing the longitudinal rods  13  to be positioned accurately and easily, without the worker  35  having to take measurements.  
         [0180]    The machine can be made to stop automatically in the positions wherein the longitudinal rods  13  have to be attached; this can be managed by the control unit of the machine after the worker  35 , at the beginning of the work, has set the design parameters of the cage  11 .  
         [0181]    When the intermediate longitudinal rods  13  have been attached, the transverse arms  27  are lowered until the remaining longitudinal rods  13  are brought to rest on the lower side of the stirrups  12  and they too can be attached.  
         [0182]    In the embodiment shown in FIG. 6, which is conceptually identical, the stirrups  12  are first completely lowered and then progressively raised and stopped, according to a visual verification of the graduated rod  30  or an automatic verification managed by the machine, in correspondence with the intermediate positions wherein the longitudinal rods  13  are to be attached.  
         [0183]    In the case shown in FIGS.  1 ÷ 6 , the operation of attaching the longitudinal rod/rods  13  in correspondence with the comer of the stirrups  12  which cooperates with the positioning and retaining means  20  is performed by extracting from the side the already partly assembled cage  11  until the said corner is free (FIGS. 3 and 5).  
         [0184]    For this purpose the transverse arms  27  are sufficiently long, with respect to the transverse size of the cage  11 , to enable the cage  11  to be supported even when it is extracted at the side.  
         [0185]    In the embodiment shown in FIGS. 14 a ÷ 16 , when the longitudinal rods  13  are attached in correspondence with the corners of the stirrups  12  it is not necessary to extract the cage  11  laterally, since the profiles  46   a  and  46   b  are arranged in a position where they do not interfere with the said comers (FIG. 16).