Method of assembling three-dimensional metal wire structures, and machine for carrying out the method.

Description of the Belgian Industrial and Commercial SISMO INTERNATIONAL Patent, Drapstraat, 1,

9288 Laarne-Kalken, Belgium, for STRUCTURE ASSEMBLY PROCESS

THREE DIMENSIONAL METALS, MACHINE

FOR YOUR ACHIEVEMENT AND STRUCTURES

PERFORMED BY THIS PROCESS.

Descriptive Memory

The present invention relates to a method of assembling three-dimensional metal structures by way of example for prefabricated elements such as panels or ceilings to be used in construction. The invention also relates to the machines that perform this process and finally to the structure performed by this same process.

A three-dimensional structure is known. of metal wires comprising a series of flat nets. Each of the flat nets is provided with at least two longitudinal and locking wires. The nets have predetermined mutual distances thanks to a series of transverse wires welded to the nets themselves and to locking wires. Such a structure forms support planes for elongate bodies of corresponding dimensions of light insulating material inserted within the structure itself. The production of these structures requires very little tolerance of

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different components and meticulous alignment between these parts in the welding phases. In order to meet these requirements, numerous manual interventions are required to bring the welding units to the wire crossing areas to weld and to maintain alignment between the parts. Such a process is therefore expensive. In addition, it is difficult to simultaneously align the locking wires of the different sections of the frame at the same time. Serious problems are also found in the construction of these structures, in particular in terms of weld reliability and high resistance to static and dynamic stresses of the structure.

The technical problem in question in the present invention is the realization of a simple and relatively inexpensive assembly process that allows to assemble a very precise three-dimensional wire mesh with high stress resistance. AND_sThis problem can be solved by the process according to the present invention which is characterized by the following steps;

a) making a series of flat nets comprising longitudinal and locking wires welded to longitudinal wires?

b) positioning of the networks according to; given transverse step:

c) alignment of the nets to bring the locking wires of the different nets to the same plane?

d) aligning the longitudinal wires on at least one side of the mesh to define corresponding planes of alignment of the structure?

e) arranging at least one transverse wire in a position in which this wire crosses the longitudinal wires or the locking wires of the nets in different zones of crossing with said longitudinal wires or, respectively, of locking wires?

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f) accessing at least one welding unit to the crossover zone of the nets with the transverse wire so that the electrodes of said welding unit are in front of the crossed wires in the considered crossover zone;

g) mutual contact of the crossed wires and electrodes, and execution of the welding of wires in the crossing zone;

(h) mutual displacement of the mesh and welding unit by an amount equal to the pitch of the transverse wires, keeping the locking wires in the same plane;

(i) repeating steps (f) to (h) for the new transverse wire and the new crossing zone until the longitudinal wires are welded to the longitudinal wires or to the structure mesh.

According to another feature of the present invention, the assembly of the networks forming the three-dimensional structure provides for the following phases:

(a) making straight wires from bends by straightening and at the same time twisting these wires;

b) arranging a group of longitudinal wires in alignment supports allowing parallel positioning of said wires;

c) welding at the respective crossing points the longitudinal wires with a locking wire, such that said wires lie substantially in the same plane as said locking wire;

d) advancing the longitudinal wires relative to the alignment supports by a distance equal to the pitch of said locking wires so as to define another reference section substantially equal to the previous reference section;

E) arranging a second locking wire so that it crosses and is close, i.e. in contact with another reference section of said longitudinal wires and so that this wire is at a precisely defined distance from it. the anterior locking wire;

f) welding the other locking wire to the longitudinal wires in the respective crossing zones;

g) repeating steps d) to f) until all welds of the net are exuded.

The three-dimensional structure made in accordance with the process according to the present invention is characterized by a remarkable stress resistance, thanks to the twisting of the wires and the precision of the welds. This structure is furthermore characterized by an accuracy in the planes of the different locking wires in order to obtain very small spaces between the elongated bodies inserted within the structure itself. In addition, the assembled structure exhibits great dimensional accuracy in order to ensure optimum arrangement of the panels when constructing.

These features of the present invention will be clearly apparent from the following description, by way of non-limiting example, with reference to the accompanying drawings, which figures represent:

Figure 1 is a schematic assembly view of the assembly machines used in the process according to the present invention;

Fig. 2 is a perspective view of an assembly machine according to Fig. 1;

Figure 3 is a schematic partial plan view of the machine according to Figure 2;

Fig. 4 is a side view of the machine of Fig. 3 in the operating position;

Fig. 5 is a front view of the details of the machine of Fig. 2;

Figure 6, in an operating phase;

Figure 7 shows the machine of Figure 2;

Fig. 5 is a side view of Fig. 8; Fig. 8 is a side view of an operation stage;

Figure Q is a schematic sectional view taken by (IX-IX) in Figure 4;

Fig. 10 is a schematic cross-sectional view of the machine of Fig. 2;

Fig. 11 is a schematic view of another detail of the machine of Fig. 2;

Figure 12 is a plan view of a variant of a detail of the machine of fiber 2;

Fig. 13 is a schematic side view of the embodiment of Fig. 12;

Fig. 14 is a phase of operation of the elements of Fig. 12;

Fig. 15 is an operating diagram of the machine of Fig. 2;

Fig. 16 is a schematic drawing of the machine assembly of Fig. 2;

Fig. 17 is a schematic plan view of a second machine according to Fig. 1;

Fig. 18 is a schematic side view of the machine of Fig. 17;

Fig. 19 is a group scheme of the machine of Fig. 17; and

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Figure 20 is a general group scheme of the operations involved in the process according to the present invention.

The assembly process according to the present invention is intended to make, for example, but not exclusively, three-dimensional metal structures (30) (Figure 2) of the type described in European Patent Application No.^s 82,102,021 published 29.9.82. AND_sIn particular, this method is intended to assemble flat steel wire mesh 36 with transverse wire 37, and preferably provides for the use of a machine for mounting the three-dimensional structure (4 °). .

The webs 36 comprise longitudinal wires 34 and locking wires 35 and at a stage prior to assembling the three-dimensional structure are made by means of one. flat welding machine (38) (figure 1).

The mounting machine (4 °) (figure 2) comprises a support structure (41) which supports the nets (36) in a feeder group (42) from which the transverse wires (37) are withdrawn to be welded to the nets (36), a series of welding units (43) and a lead group (45) for the structure (3o) during assembly and a collection assembly (50) (figure 1).

The machine further provides an electronic group (57) (Figure 10) for sequential control of the different assembly and welding phases, a control console (58), a pneumatic unit (59) for the execution of commands or orders. sent by the unit (58) and a hydraulic unit (60) for cooling the welding electrodes of the assembly machines (38) and (40).

The following description refers to the support structure

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The support structure (41) comprises a group of mullions (79) to which a series of crosspieces (80) are fixed at predetermined distances in pairs. The sleepers 80 in turn support a series of horizontal and overlapping support plans 81. THE_s The distances between the planes 81 are equal to each other and regulate the transverse pitch of the flat nets 36 with respect to the already assembled structure 30.

The planes 81 (Figure 3) are of very elongated rectangular shape and are provided with two side sides (82) and (83), respectively left and right, if we refer to Figure 4, and support a corresponding flat network (36). ).

U_m The control element (83), formed by a rectangular section drawing, is fixed on each side (82) and is provided with a control surface (85) which is capable of cooperating with the left ends of the wires. locking means (35) of the nets (36).

The surfaces (85) of the control elements (83) of the different planes (81) are situated in the same plane and define a vertical reference surface of the three dimensional structure (30).

A further control element (86), also consisting of a rectangular section drawing, is adjustable to the side (83) of each plane (81) and is provided with a surface (87) with which to cooperate. right ends of the figure of the locking wires (35) of the nets (36). The surfaces (87) of the control elements (86) are situated in the same plane and define another vertical reference plane of the three-dimensional structure (3o), parallel to the vertical plane defined by the surfaces (85). AND_sThese two reference planes are such that they bring the longitudinal wires (34) to the same plane on the same side of the different networks (36) and, furthermore, are perpendicular to the planes of the same networks (36). At one end

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In the front, according to Figure 3, the control elements (85) and (86) are provided with guide elements (92) and (93) formed by U-section drawn that protrude out of the planes. (81). AND_sThese elements cooperate with the ends of the locking wires (35) as well as the longitudinal wires (34) of the flat walls (36) and serve to precisely define the vertical reference planes of the structure (30) and to prevent bending of the wires. nets (36) near the exit end of the guide members (92) and (93), adjacent to the welding units (43).

The control elements (87) and the guide elements (93) can be moved relative to the sides (83), for example by means of screws (94). D_andIn this way, the distance between the surface reference planes (87) and the guide elements (92) can be changed either with respect to the surface reference plane (85) or with respect to the guide elements (93). , to precisely define the vertical reference planes of the structures (30) using networks (36) of different widths.

A feed group follows the support structure. This feed group (42) is divided into two units, each of which comprises a hopper (10χ) (Figure 2) in which such transverse wires (37) are arranged. The wires penetrate gravity into an outlet channel (102) (Figure 11) and this operation is facilitated by the action of a cam (103). A device (104) is arranged to drop the wires (37) one by one which, after being guided by the inclined bars (105), stop at the base of the bars (105), striking against the shoulders (106) . The presence of the wire (37) held against the stops (106) is detected by a magnetic beacon (107) which transmits the information in question to the control unit (57) as electrical signals.

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the holder 41 and hoppers 101 (figure 3) provided for two capture arms 111 each formed by a parallelepipod bar with a support shaft at one end and an output shaft 112 of pneumatic working organ (113). AND_sThe maneuvering member (113) is provided for rotating the capture arm from a horizontal position to a vertical position. Each capture arm (111) is, in its horizontal position, substantially aligned and overlapped with the temporarily stationary wire (37). against the stops (106) and in close proximity to the wire itself, a number of magnets (114) are arranged to move the wire (37) away from the stops (106) and to hold it on the arm (111) in alignment with the axis of the same arm.

This position remains unchanged even when arm 111 is in an upright position. Two detectors 115 and 116 also have the function of detecting respectively the horizontal position and the vertical position of the arm 111 and transmitting the information to the control unit 57.

In front of the hopper (10χ) (Figures 2 and 3) are arranged two pneumatic maneuvers (121) provided with pistons (122), movable in a horizontal plane in a direction perpendicular to the reference planes of surfaces (85) and (86). ). In the plungers (122) are attached two corresponding support blocks (123) to which are in turn attached two other pneumatic maneuvers (124). AND_sThese maneuvers (124) are provided with pistons (125) which are horizontally movable in a 45 ° inclined direction with respect to the reference planes of surfaces (85) and (86). The plungers (125) support mullions (126) to which two corresponding series of pneumatically operated collets (127) are attached, which can extend the wires (37) from the arms (111) and hold them parallel to the amounts (126). D_anddetectors (128) allow detection. the presence of one or more wires (37) retained by the tweezers

- 9 (127). The supports (123) may be moved away from the plungers (122) from lateral positions in the vicinity of the hoppers to central positions adjacent to the welding units (43) and the guide elements (92) and (93). The mounts (126) may , in turn, be spaced from plungers (125) from spaced apart positions of hoppers (1θχ) and guide elements (92) and (93) to upright areas (111), and from welding units (43).

Limit switches (131) and (132) of the switchgear (121) detect the side and center positions of the blocks (123) and limit switches (133) of the switchgear (124) respectively. the mullions (126) near the arms (111) and the welding units (43). In addition, magnetic detectors (134) detect the presence of wires (27) in the risers (126) when they are held by tweezers (127). Information from detectors (134) is also transmitted to control units (57). The hoppers (10χ) are arranged to accept, each tuna, with the appropriate separation elements, two series of transverse wires (37), with a length slightly less than the maximum width of the hopper itself. The inclined bars (105), the capture arms (111), the mullions (126), the tweezers (127) and the different detectors are capable of simultaneously treating two wires (37) aligned with each other and close together. I_sallows you to assemble two three-dimensional structures at a time slightly lower than the half of a minimum height structure.

THE_s welding units (43) (figure 3) are divided into two groups mounted respectively on two plates (145) and (146). These plates are mounted in vertical uprights (147) arranged to the left and right of the guide elements (92) and (93) such that each pair of elements (92) and (93) is associated with a pair of control units. welding (43).

Ç_Theof the unit (43) comprises a hollow parallelepiped shaped body (151) on which a transformer (152), a pneumatic switchgear (153), a movable electrode (154) and a contrast electrode (155) are mounted .

movable electrode (154) is attached to a piston (157) of the switchgear (153) which, in turn, is guided by sleeves isolating it from the body (151). The contrast electrode (155) has an L-shaped body and is electrically connected to the body (151). The transformer 152 is partially inserted into the parallelepiped body 151 and is provided with a primary whose terminals may be connected to the network. 0 The transformer secondary is provided with two terminals (159) and (160) connected to the electrodes (154) and (155). Terminal 159 is directly connected to electrode 155, while the connection between electrode 154 and terminal 16θ is secured by a series of thin, U-shaped copper foils allowing displacements of the piston (157) relative to the transformer (152). The active part of each movable electrode (154) (figure 5) indicated by (163) is cylindrically shaped and is placed higher than the piston (157) and connected thereto by a block (164). The active portion of each electrode 155, indicated by 165, is in the form of a parallelipiped and extends upwardly over electrode 155. The blocks (164) of the electrodes (154) and (155) are internally traversed by cooling pipes, provided with small inlet and outlet ports (166) and (167) connected to the hydraulic unit (60).

In the rest position, the parts (163) and (165) of the units (43) are arranged below the planes of the nets (36) and each plate (145) and (146) can be moved vertically with respect to the mullions (147). ).

a maneuvering member (170) moves the welding units (43) upwards to bring the parts (163) and (165) into alignment with the planes of the networks (36). Alem ί * | ί fc · ·

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In addition, two limit switches (168) and (169) can respectively detect the upper and lower positions of the units (43). N_The variant according to figures 12 and 13), the welding units (43) are mounted on two fixed plates (180). Ç_TheThe contrast electrode, designated 171, is provided with a lever arm 173 and swings around a sleeve 172 parallel to the piston 157.

THE_s active parts of the moving electrodes 154 are brought into alignment with the planes of the various networks 36, while the active parts of the electrodes 171 are disposed beneath these planes. The arms (173) oscillate in a single vertical connecting rod (174) which, in turn, is connected to a pneumatic maneuvering member (175).

The switchgear 175 is designed to oscillate the electrodes 171 around the flanges 172 to bring the active parts 164 into alignment with the network planes 36. The detectors 168 and (169), in this case, detect the respective upper and lower positions of the electrodes (171).

The group 45, called the advancement group (FIGS. 3 and 7), comprises a pneumatic maneuvering member 182 provided with two pistons 183 which can be moved parallel to the guide members 92 and 93. A vertical bar (104) is mounted on the pistons to which horizontal L-shaped arms (185) are fixed and arranged in the space between the planes of the networks (36). The arms (185) have a longitudinal portion (186) disposed in the mid plane between the vertical reference planes defined by the guide elements (92) and (93).

In each part (186) oscillates by means of an axis of rotation (187) a toothed lever (190) provided inferiorly by an anterior tooth (191) and a posterior tooth (192). In the rest position, the lever 190 is held in the horizontal position by gravity and the action against

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holding element (188) from part (186). Each tooth (191) and (192) in its front part comprises a corresponding substantially vertical meeting edge (193) and, at its rear, an inclined edge (194). The meeting edges 193 of teeth 191 and 192 are aligned with each other in two vertical planes which are slightly longer (less than 1 mm for 0.6 - 0.7 mm metal wires) at half of the locking wire pitch (35) and the nets (36). 0 biasing member (182) is designed to move the bar (184), and thus the levers (190), of a path equal to half the pitch of the locking wires (35). A pair of limit switches (197) and (196) accurately check limit limits and transmit the information to the control unit (57). The control edges (193) are designed to cooperate with the locking wires (35) in order to move the nets (36) at the same time, but keeping the same plane of the locking wires of the different nets (36), either before mounting the frame (30) or during the movement of the nets (36) during welding operations.

In particular, in the rest position, the control edges 193 of the teeth 191 and or 192 are disposed close to the wires and behind the locking wires 35 of the nets 36. P_OAccordingly, upon a forward displacement of the plungers (183), the edges (193) of the teeth (191) or teeth (192) of the levers (190) drag the nets (36) to the front of the and this at a distance equal to half the pitch of the locking wires (35).

During the return path, the locking wires with the inclined edges 194 cause the toothed levers 190 to be raised, which can then take the edges 193 back behind the locking wires 35 with a view to a new advance of the networks (36). During the two forward and reverse cycles

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of the levers 190, the teeth 191 and 192 act only once, but in both cycles on the same locking wire 35. A step of the transverse wires 37 is thus substantially equal to half of the step of the locking wires 35 in the already assembled structure 30.

Referring to Figure 1, it will be appreciated that the collection assembly 50 comprises a transposition plane 20χ provided with a base 202 for grasping the already assembled structure and at least one zone 203 which can receive a console for a second frame when the assembly machine (4o) simultaneously assembles two frames of reduced height.

The unicLade 57, called the control unit, comprises a microprocessor 210 provided with a series of input-output interface units. The input-output interfaces receive data from detectors detecting the presence of wires and detectors detecting the limit switches of switching devices; the output interface units are connected to relays or possibly to static switches controlling the opening or closing of valves (212) to (219) inserted between the compressed air circuit (225) of the pneumatic unit (59) and, respectively maneuvering organs (104), (113), (122), (124), (127), (182), (169) or (175), as well as of all welding (43).

A microprocessor (210) is provided for activating a power unit (226) that connects &amp; mains the transformer primary (152) of the units (43). The microprocessor 210 is provided with a program that controls the operation of the different electric valves, depending on the state of the different detectors. AND_sIt is further coupled to a number of regulators to allow for a variation in welding times.

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The assembly process is outlined in Figure 20 and is designed to perform, in stages (211) and (212), the collection of wires (37) in the hoppers (101) and the positioning of the nets (36) (figure 3) in the planes. support (81). The longitudinal wires (34) are thus inserted into the various guide elements (92) and (93) until the locking wires (35) of the first series are located opposite the control edges (193) of the teeth (191). ) ·

The machine (40) is designed to work with two wires (37), or four wires if two structures already positioned in the arms (111) are mounted, and this in the vertical position. The blocks (123) are in the positions respective side panels and mullions are spaced from the arms (111). In this situation, the control unit (57) is ready to begin assembly of the frame (30). By pressing the start button, ρδβ operates the operating devices (182) which move the respective levers (190) towards the front of the machine, thereby simultaneously advancing the unmounted nets (36).

Accordingly, while the locking wires (35) of the first series are correctly positioned in the same plane, the longitudinal wires (34) are carried to the respective welding zones.

After the forward movement of the nets (36) detected by the detectors (198), the control unit (57) operates the maneuvers (124) to bring the mullions (126) close to the arms (111) . The unit (57) controls the closing of the tweezers (127) over the wires (37) and the replacement of the wires in the mullions (126). Once this condition has been verified, the unit 57 provides for the opposite activation of the switching elements 124, pushing away the mullions 126, and thus the wires, of the arms 111. Unit (57) operates the maneuvers (121) to move the

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support (123) for the welding zone.

The control unit (57), having verified, thanks to the detectors (131), the new position of the elements, again activates the switching elements (124) (figure 15) to bring the wires (37) in close proximity. Bearing in mind that the plungers (125) move at an angle of 45 ° to the electrode and wire axes (34), the wires (37) and mullions (126) can move freely without hindering these parts. New wire position (37) is detected by detectors (133)

In this state, the unit (57) elevates the plates (145) and (146) as well as all welding units (43) or vertical connecting rods (174) (figure 13) only with the electrodes ( 171) until the active parts (163) and (165) are brought (figure 5) to the electrodes for alignment with the longitudinal wires (34) and with the cross-sections of the transverse wires (37) and the longitudinal wires (34).

The unit (57) further provides for the operation of the maneuvering devices (113) to raise the arms (111) to the horizontal position to allow elevation of another pair of wires (37) (or four wires, if not two structures) out of the hoppers (101).

During the next phase, unit (57) provides for the control of all maneuvers (153) of all welding units (43). Accordingly, the movable electrodes 154 lead the crossed wires 34 and 37 into contact with the respective counter electrodes. Unit 57 thus provides for the supply of transformer primers 152 and the welding of wires 37 and 34 in the respective crossing zones. When the electrodes still maintain the wires 34 and 37, the unit 57 starts the maneuvers 182 for a return stroke towards the rear of the machine.

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corner. The levers (190) are thus withdrawn to the rear and slightly overlap, with their hind legs (192), the locking wires (35) of the second series. Having verified the new position of the levers (190) by means of the detectors (197), the unit (57) controls the opening of the electrons and the tweezers and in the opposite direction maneuvers (180) or (175) to bring the electrodes out the path and the locking wires (35). The unit (57) further takes the arms (111) to the upright position. The unit (57) finally moves the mullions (126) and blocks (123) away from the welding zone, bringing the machine to its initial position.

Figure 3 shows, at dash-and-point, the position of the blocks 123 near the welding zone, with the clamps 127 being shown open and spaced from the welding zone. The forward positions of the toothed levers 190 and nets 36 are shown in the same manner. Figure 4 shows the arrangement of the maneuvers (121) and (124) for the welding phase, the wires (35) being aligned by the toothed levers (190). Figure 8 shows the positions occupied by the unit (43) during the welding phase and, at point-and-dash, the phase of retaking a wire (35) by a tooth (192).

Fig. 15 shows the schematic diagram as a function of time of welding current flow, displacement of moving electrodes 154 relative to counter electrodes 157 or 171, and displacement of units 43 or electrodes (171). These also depicted the displacements of the tweezers (127) of the maneuvering organs (122) and (123) and the wire (37) in the arms (105), as well as those of the arms (111).

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The following description refers to the flat assembly machine.

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The longitudinal wires (34), prior to being welded to the locking wires (35), are unrolled from the large capacity benders (240) (Figure 1) and are pre-straightened by means of a wire straightening machine (241). This machine of known type is not detailed here. Generally, the machine is provided with a series of rectifying rollers and counter rolls (242) that straighten the wires.

In the course of straightening, the wires are stiffened by denserolation and deformation due to twisting during this phase.

Mesh assembly machine 38 comprises an elongated workbench 245 having an inlet zone and an outlet zone 244. The bench (245) (figure 17) is provided with a series of sleepers (246) which can hold the longitudinal wires (34). In turn, the longitudinal wires 34 are further summarily held at predetermined mutual distances by appropriate guides 247 which can move along the sleepers. In the middle area of ​​the bench 245, furthermore, carefully calibrated alignment brackets 246 are provided, and of such length that the longitudinal wires 34 will be arranged substantially parallel to each other in a reference zone next to the zone. of the supports themselves. The wires (34) are situated substantially in the same plane; The mutual distance between the wires themselves is therefore very precise and has very small tolerances with respect to the design data. Beside the exit zone of the supports (248) there is provided a device (250) for feeding the locking wires (35) and a welding unit (251). The device (250) is designed so that each locking wire (35) can be arranged to cross the longitudinal wires (34) parallel to each other so that each wire is as close as possible.

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wires (34) or in contact with them in their reference section. Device 250 (FIG. 18) comprises in particular a hopper (252) provided with an outlet rail (253) controlled by a switching member (254), a number of inclined bars (256), and a series of small thrust fins (258).

The welding unit (251) comprises a fixed electrode (260) disposed slightly below the wires (34) and transversely with respect to the wires in its reference zone, and a movable electrode group (261). The active portion of these electrodes 261 is substantially parallel to the active portion of electrode 260, and the electrodes 261 are designed to move vertically with respect to the electrode 260 under the action of corresponding maneuvers (2 '). ). The electrodes 261 are designed to cooperate in their downward movement with a locking wire 35 and to push it against the longitudinal wires 34 which in turn are retained by the fixed electrode 260 at the respective crossing zones for the successive welding of wires (34) and (35). The machine 38 further comprises a lead member 270 capable of advancing the longitudinal wires relative to the electrodes 260 and 261 of a value perfectly equal to the pitch of the locking wires. This device comprises transverse teeth (272) displaced by a chain (273) ® that can be applied to the locking wires (35) after welding. 0 each of the teeth (272) is carefully controlled by an extension encoder (275) which accurately collects the angular displacements of an axis (276) on which a sprocket cooperating with the chain (271) is attached. In turn, this chain is displaced by a servo mechanism comprising a motor (277) controlled by the extension encoder according to a program synchronizing with the movement of the electrodes (261) and with the welding of the wires. Downstream of the device (250) there is provided a cutting device (278) driven by

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a pneumatic control unit (279) and comprising shears which can cut the locking wire (35) exactly next to the welding zones with the longitudinal wires (34) located outside the net. The nets themselves therefore have very precise dimensions, which allows precise succession of the frame assembly operations (30) on the machine (40).

The machine 38 allows to assemble several redgs at the same time. This operation is performed using a single transverse wire for multiple networks. These are then separated during the actual cutting phase following their welding. The different stages of advancing the networks, welding and cutting are controlled from a control unit (281) comprising a microprocessor (282) (figure 19) and a control console (283). In the microprocessor 282, the different working phases, the advance phase and the welding times can be programmed and tuned. Figure 20 summarizes the different stages of assembly of the frame (30).

In phase (290) welding and twisting of wires (34), (35) and (37) are performed, which will be cut respectively in phases (291), (292) and (293).

During steps 294 and 295, the wires 34 are respectively placed in the supports 246 of the machine 38 and the wires 35 in the appropriate die 252. The wires 34 and 35 are welded at phase 296 and then cut at phase 297. Then, when the teeth return to the welding zone during phase 298 /, the nets can be caught at stage 299 and placed in the planes 81 of the assembly machine 40, The transverse wires (37) will in turn be caught in the hoppers (101) during phase (211).

From here takes place the frame assembly phase (30) which provides for step-a20 A

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transverse wires in step (300) while maneuvering member (104) and arms (111) place the wire (37) in the middle position in phase (303).

Then follows the elevation of the electrodes in phase 305, the welding in phase 306 and the return of the levers 190 in phase 307. The order for descending the electrodes is then given at step 309 and at step 310 the body 50 is collected from the assembled structure.