FR2703607A1 - Process for manufacturing semi-finished products from metal wire. - Google Patents

Abstract

Device (1) for manufacturing semi-finished products (2) from metal wire (3), in which a ring (17) of metal wire is connected at a plurality of points defining respective sections (20) of the ring ( 17) by means of a plurality of gripping heads (31) arranged in a fan shape around the ring (17), and is folded by means of a plurality of pushing heads (27), interposed among the gripping heads (31) and each adapted so as to advance an intermediate part (22) of a respective section (20) towards an inner junction surface (23) of the ring (17) and of the end parts (24) of the corresponding section (20) itself, in positions located near the respective end parts (24), corresponding to the adjacent push heads (27).

Description

A Process for the production of semi-finished metal wire products La

  The present invention relates to a device for

  manufacture of semi-finished metal wire products.

  In particular, the present invention relates to a device for manufacturing semi-finished metal wire products, intended for the production of small fixing cages for corks for beverage bottles

sparkling -

  The small fixing cages comprise, as is known, a main body adapted so as to surround, in use, a stopper of a bottle, and an annular ring adapted, in use, so as to allow the connection of the main body mentioned at the neck * of the bottle itself The main body mentioned and the ring are normally formed in a fully automatic production line, consisting of a plurality of work stations used to execute the different forming operations The production rate of the line is good course limited by the production rate of the individual stages, including the forming of a semi-finished product intended for the construction of the body of the small

  cage is the most critical overall.

  The object of the present invention is to provide a device for forming semi-finished products intended for the production of small fixing cages and, in particular, bodies of the small cage, which makes it possible to obtain a high production rate. and, at the same time, a

simple and economical manufacturing.

  According to the present invention, there is provided a device for manufacturing semi-finished products of metal wire, characterized in that it comprises folding means adapted so as to bend a metal wire, in order to form a closed ring of shape. substantially circular; a station for forming said semi-finished product, in which said ring is adapted so as to be placed in a position substantially coaxial with respect to a first axis; a plurality of forming groups arranged in the forming station and each provided with a corresponding gripping head, the gripping heads being arranged along respective second axes, substantially radial with respect to said first axis, and being adapted so as to positively coupling with said ring, in order to fix the ring even at a plurality of points delimiting respective sections of the ring; thrust means which can be associated with each of said sections, in order to advance an intermediate portion of each of the sections itself, towards said first axis, along a third axis substantially radial with respect to said first axis, and in order to carry - respective ends of said sections, in positions located near the respective end portions of adjacent sections; and first actuation means, serving to rotate said gripping heads around said respective second axes, in order to twist said said between them

  end parts located next to each other.

  Preferably, in the device of the type described above, said second axes all lie in a forming plane perpendicular to said first axis and extend in fan shape from the first axis itself, in angular positions which are equally spaced between them. The present invention further relates to a method of

  manufacture of semi-finished metal wire products.

  According to the present invention, there is provided a method for manufacturing semi-finished metal wire products, characterized in that it comprises the steps of bending a metal wire, so as to form a closed ring of substantially circular shape ; of connection, in correspondence with a forming station and by means of a plurality of gripping heads, of said ring in a practically coaxial position with respect to a first axis and at a plurality of points delimiting respective sections of the ring itself , said gripping heads being able to move along respective second axes, substantially radial with respect to said first axis; advancement, via the pushing means, of an intermediate part of each said section, towards said first axis, along a respective third axis, practically radial with respect to said first axis, so as to carry respective end portions of each of said sections, in positions located essentially near the respective end portions of adjacent sections; and of kinking between them said end portions located substantially close to one another, by rotating said

  grip heads around said respective second axes.

  Preferably, the aforementioned method comprises the step in which said intermediate parts are forced to abut against a forming surface substantially coaxial with respect to said first axis and adapted so as to be arranged inside said ring, and in which the intermediate parts, even blocked, are maintained against said forming surface, during the kinking step

of said end portions.

  The invention will be described below with reference to the accompanying drawings, which illustrate an example of non-limiting implementation, in which: FIG. 1 is a bottom view, parts of which have been removed for the sake of clarity, of a preferred embodiment of the device according to the present invention; Figure 2 is a perspective view of a small fixing cage, for bottle caps for sparkling drinks; Figure 3 is a cross-sectional view, on a larger scale, along the line III-III of Figure 1; and Figure 4 is a partial top view, parts of which have been removed for clarity, of the device of Figure 1, illustrated in a

different operating state.

  In the appended figures, the number 1 designates a device for manufacturing semi-finished products 2 (FIG. 3), produced from a metal wire 3 and intended for the manufacture of small fixing cages 4, intended for plugs of bottles (not shown) for

fizzy drinks.

  In particular, the device 1 is part of a manufacturing line (not shown) automatically, of the small cage 4 The small cages 4 (FIG. 2) each include an annular ring 6 adapted so as to be tightened on a neck of a corresponding bottle (not shown), and a main body 7 adapted so as to wind around a closure cap for the bottle (not shown) mentioned The body 7, of which the semi-finished product 2 constitutes the developed plane, comprises a plurality of uprights 8 which are each coupled, by their end, to the ring 6 and converge between them in order to form, in correspondence with their opposite end, a

annular connecting element 9.

  Referring to Figures 1 and 3, the device 1 comprises a chassis 9 a having a substantially vertical central channel 9 b and a tubular rack 10 cylindrical, which extends inside the channel 9 b coaxially with respect to an axis 11 of the channel 9b itself and carries an external radial flange 12, connected to its intermediate part The flange 12 is provided with four radial slots 13, forming between them an angle of 900 and a circular groove 14, which is arranged on a front surface of the flange 12 itself, turned downwards in a coaxial position relative to the axis 11 and intersects the slots 13 even The rack 10 has its upper end part connected to a rectilinear actuator 15, of the type known, adapted so as to move the rack 10 even along the axis 11, in order to move the flange 12 between a loading position 16 in which the wire 3 is brought into contact, in a known manner, with the groove 12 and is then cut by means of a cutting group; known and not illustrated, in order to form a closed circular ring 17 (FIG. 1) and a forming station 18 in which the ring 17 formed is extracted from the groove 12

in order to then be worked on.

  According to what is illustrated in FIG. 1, the device 1 comprises four forming assemblies 19 arranged in the station 18, around the rack 10 and angularly, at an equal distance between them, forming an angle of 90 In particular, in station 18, the assemblies 19 are each arranged in correspondence with respect to a corresponding slot 13 and are adapted so as to block between them the ring 17 at four points, equally spaced and defining respective sections 20 of the ring 17 itself, in order to maintain the ring 17 in a position coaxial with respect to the axis 11 and coplanar with respect to a forming plane P

  perpendicular to the axis 11 itself and to the plane of Figure 12.

  Referring again to FIG. 1, the device 1 further comprises four thrust groups 21, which are also arranged in the station 18 around the rack, in angular positions spaced equally between them The groups 21 are interposed with the forming assemblies 19 and are each adapted so as to advance an intermediate part 22 of a corresponding section 20, towards an external surface 23 of the rack 10, so as to carry the end parts 24 of the corresponding section 20 themselves, each in positions located substantially close to a part

  respective end 24 of an adjacent section 20.

  In particular, the groups 21 each comprise a fixed guide 25 and a carriage 26, which is slidably coupled to the guide 25 itself and supports a pusher head 27 The heads 27 are each configured so as to mate with an intermediate part 22 respective and are movable, in one piece with the respective carriages 26, along a corresponding axis 28 which coincides with the axis of the corresponding group 21, intersects perpendicularly the axis 11 and is located in the plane P. Each of said carriages 26 can move along the respective guide, under the effect of the thrust of a ratchet and rack transmission 29, between a functional advanced position, in which the head 27 itself is adapted so as to clamp the part respective intermediate 22 against the mentioned surface 23 of the rack 10, and a retracted position of rest, in which the head 27 even

  allows the flange 22 to access the forming station 18.

  During the displacement of the heads 27 from the retracted position to the advanced position, the ring 17 is held by the assemblies 19 which, as best illustrated in FIG. 3, each comprise a gripping head 31 with clamp, associated with the chassis 9a , and adapted to block the ring 17 in

a corresponding mentioned point.

  In particular, the chassis 9 has, for each assembly 19, a seat 32, the axis 33 of which intersects the axis 11 perpendicularly, lies in the plane P and coincides with the axis of the corresponding assembly 19 Each of the seats 32 defines a guide intended for a corresponding tubular carriage 34, sliding axially within it and, in turn, in rotational contact and in an axially fixed position, with a hollow shaft 35, coaxial with respect to the axis 33 and defining a support for the

corresponding head 31.

  The carriages 34 can move along corresponding axes 33, under the thrust of a device 36 with cam-pusher, adapted so as to move each of the heads 31 between a retracted end-of-travel position, in which the heads 31 same are in partial contact with the corresponding seats 32, so as to allow the flange 12 to access the station 18, and an advanced end-of-travel position, in which the same heads 31 are adapted to

  so as to release the finished semi-finished product 2.

  The device 36 comprises a cam 37 common to all the carriages 34 and respective pushing elements 38, coupled, on one side, to the cam 37 and, on the other, to the corresponding carriage 34 The cam 37 is defined by a annular groove which is arranged in a central body of a toothed wheel 39 which can rotate relative to the chassis 9 a and has an axis of symmetry, which coincides with the axis of the wheel 39 itself, and a variable radius In particular, the wheel 39 is coupled to chassis 9 a so as to be able to rotate about the axis 11, in a position located below the seats 32 and has an external serration meshing with an external serration of a motorized actuating wheel 40 which can rotate around a corresponding axis 41, parallel to the axis 11, in order to rotate the wheel 39 even with respect to the chassis 9 a, counterclockwise as shown

in figure 3.

  Referring to Figure 4, the mentioned groove is defined by four parts of groove 42 contiguous with each other, identical and present in an equal number, while forming an angle of 90 Q The groove

  is therefore periodic according to a period of 900.

  Each part 42 comprises, in the direction opposite to the direction of rotation of the wheel 39, a first curvilinear section 43 with substantially constant radius, a second straight section 44 with decreasing radius, a third section 45 again curvilinear, having a substantially constant radius and of a value less than that of the first section 43, a fourth section 46 substantially rectilinear and with slightly decreasing radius, and a fifth section

  47 inclined, substantially rectilinear and with increasing radius.

  Referring again to FIG. 3, the gripping heads 31 are coupled to corresponding carriages 34, by means of corresponding shafts 35, each of them being able to rotate around the corresponding axis 33, under the thrust d a transmission 48 with toothed wheels Such a transmission comprises a common drive wheel 50 and a plurality of driven toothed wheels, each coupled to the corresponding shaft 35, by means of a splined coupling 51 and maintained in axially fixed positions relative to to the corresponding chassis 9a, by means of a radial dowel 52 An end part of the dowel 52 is fixedly attached to the chassis 9a and an opposite end part, in sliding contact with a grooved circumference arranged in a sleeve 53, coaxial and integral relative to the wheel 49 The wheel 50 is coupled to the chassis 9 a in order to rotate around the axis 11 and comprises an outer front serration, meshing with the den telure of the wheels 49, and a peripheral serration meshing with an external peripheral serration, of a control wheel 54 of a control device, known and not illustrated, adapted so as to actuate the wheel 54 even intermittently. The gripping heads 31 each comprise a fork connected integrally to an end part of the corresponding shaft 35, turned towards the rack 10 and two rocker claws 56, which are articulated relative to the arms 55a of the corresponding fork 55 itself, by means of respective pins 57, perpendicular to said corresponding arms 55a and to the corresponding axis 33, in order to tilt around the axes of the pins 57, under the thrust of a corresponding actuation group 58, between an open position and a closed position, in which they are adapted so as to come into contact with, and to

block, ring 17.

  In particular, the claws 56 corresponding to the same head 31 are each provided with a spike 58 a, the latter extending in correspondence with the spike 58 a of the other claw 56 to define, in one piece with the another pin 58 has the same and the respective claws 56 and when the claws 56 themselves are disposed in their closed position, an eye 59 adapted so as to be brought into contact with play with a respective part of the ring 17 The claws 56 corresponding to the socket head 31 even have respective surfaces 61, turned and converging towards one another and towards the corresponding shaft 35. The actuating group 58 comprises a control rack 66 coaxial with the corresponding shaft 35 and having, at one end, a frustoconical body 62 which can move along the corresponding axis 33 and adapted so as to cooperate with the surfaces 61, and an annular reaction spring 63, in contact with respective seats arranged on an external surface of the claws 56 themselves, in correspondence with the surfaces 61, in order to exert on the claws 56 an action opposite to that

exerted by the body 62.

  The body 58 further comprises a guide 64 integral with the chassis 9 a and extending in directions parallel to the corresponding axis 33 and a carriage 65 slidably coupled to the guide 64 The control rack 66 comes into contact of axial sliding with the corresponding shaft 35 and has an end opposite to the body 62, projecting beyond the corresponding shaft 35 and coupled to the carriage 65, by means of

  the interposition of a stop cushion 67.

  The carriages 65 and, therefore, the corresponding racks 66, can move along the corresponding guides 64 under the effect of the thrust of an actuation and control device 68, which comprises a cam 69 common to all the carriages 65 and, for each of the carriages themselves, a pushing element 70, one end portion of which is integrally connected to the corresponding carriage 65 and one opposite end portion of which is coupled to the cam 69 In particular, the cam 69 is defined by an annular groove arranged on the body of the mentioned wheel 39, in a concentric and external position relative to the groove defining the cam 37 and has a variable radius The cam 69 is defined by four groove parts 71, identical and contiguous with each other and present in an equal number, while forming an angle of 900 The groove is therefore periodic according to a period of 900 and each of the parts 71 is

  arranged in correspondence with a corresponding part 42.

  Each part 71 comprises, in a direction opposite to the direction of rotation of the wheel 39, a first curvilinear section 72 with constant radius, arranged parallel to the section 43, a second straight section 73 with decreasing radius and slightly divergent with respect to the corresponding section 44 , a third substantially straight section 74, arranged in correspondence with the point of convergence of the sections 44 and 45 and with increasing radius, a fourth curvilinear section 75, arranged in correspondence with the section 45, parallel to the section 45 itself and having a smaller radius to the radius of the first section 72, a fifth section 76 substantially straight and parallel to the section 46, a sixth straight section 77 with decreasing radius, and a last inclined section 78, substantially rectilinear and with increasing and converging radius

  slightly towards the corresponding section 47.

  Referring again to FIG. 3, the device 1 finally comprises a group 79 extractor known per se, arranged in the lower part relative to the station 18 and along the axis 11, in order to grasp the semi-finished product. finished 2 completed and advancing semi-finished product 2 even to a station

  of subsequent forming, not shown.

  The operation of the device 1 will be described below, from a start cycle state, in which the pusher heads 27 are disposed in their retracted rest position, the flange 12 is disposed in the loading station 16 and houses inside the groove 14 a piece of wire, the ends of which are arranged in correspondence with one of the gripping heads 31, the transmission 48 maintains the heads 31 themselves in a fixed angular position, corresponding to a state of perpendicularity between the dowels 57 and the axis 11, and the wheel 39 carrying the cams 37 and 69 is disposed in a determined angular position, in which the elements 38 11 are arranged at the entrance to the corresponding parts 42 of the grooves 37 and block the gripping heads 31 in their retracted position and the elements 70 are arranged at the entrance to the respective parts 71 of the groove 69 and maintain the pairs of claws 56 corresponding in dan s

their closed position.

  From this state, the actuator 15 is activated and moves the flange 12 in the station 18 and simultaneously the wheel 39, which then rotates around the axis 11 of the wheel 40, -in the opposite direction of clockwise, as shown in FIG. 3 During the movement of the flange 12 towards the station 18 and, following the rotation of the wheel 39, the thrust elements 38 and 70 pass through the respective sections 43 and 72, all maintaining practically constant, both the axial position of the heads 31 relative to the corresponding frames 30, as well as the angular position of the claws 56 around the corresponding pins 52, relative to the corresponding forks 55 When the flange 12 reaches the station 18, the claws 56 are rotated by means of the group 58, around the respective dowels 57 and are brought into their open position, under the control of the elements 70 which engage and pass through the sections 73 at the same time and, if simultaneously, the gripping heads 31 are gradually moved into an intermediate functional position, close to the mentioned advanced end-of-travel position, under the action exerted on the carriages 26

  by the elements 38 which cross the sections 44.

  When the heads 31 reach the intermediate functional position mentioned, the claws 56 reach their open position in which they receive a part of the ring 17 between them and in which the respective pins 58 a are placed in positions which allow their protrusion on the plane P

  located inside the ring 17.

  At this time, the gripping heads 31 are held in substantially fixed axial positions by the corresponding elements 38 which, during the rotation of the wheel 39, pass through the respective sections 45 and the claws 56 are carried by the respective elements 70 which, at the same time, cross the respective sections 74, in their closed position, in which they block the ring 17 in a coplanar position with respect to the plane P and coaxial with

in relation to axis 11.

  At the end of the closing phase of the claws 56, the actuating member 15 is activated again and it brings the flange 12 back into the loading station 16, while both the axial position of the heads 31 and the position angular of the claws 56 relative to the corresponding forks 55, remain constant because the elements 38 continue to cross the corresponding sections 45, at constant curvature and the elements 70 engage and pass through the sections 75 also having constant curvature During this state constant of the position of the heads 31 and of the claws 56, the thrust groups 21 are actuated, each of them moving the respective thrust head 27, from its retracted position to its advanced position and, then, the respective intermediate part 22 , in order to bring it into contact with the surface 23 and the respective end parts 24, in positions located near the end parts 24 corresponds ant

to the adjacent heads 27.

  As soon as the pusher heads 27 have reached their advanced position, the gripping heads 31 are progressively advanced towards their advanced end-of-travel position, under the action of the corresponding elements 38 which cross the sections 46 and, simultaneously, they are driven each in rotation about the corresponding axis 33, by the transmission 48 which is actuated by the control device mentioned, not illustrated During the rotation and the displacement of the gripping heads 31, the claws 56 are maintained in their closed position under the action of the corresponding elements 70, which cross the sections 76 and the end portions 24 of the sections 20 mentioned are twisted together, in order to form the uprights 8 of a

corresponding body 7.

  At the end of the twisting step of the end portions 24, the gripping heads 31 are finally advanced along respective axes 33, towards their advanced end-of-travel position, under the action of the elements 38 which continue to pass through the sections 46, while the claws 56 are returned to their open position, under the action of the elements 70 which

  cross sections 77 simultaneously.

  In this way, the semi-finished product 2 is released by the gripping heads 31 and, at this time, the gripping heads 31 are gradually moved back to their rest position, under the action of the elements 38 which, following the rotation of the wheel 39, pass through the sections 47 and the claws 56 are again brought back to their closed position, under the action of the elements 70 which pass through the sections 78 The semi-finished product 2 is brought into contact with the extractor group 79 which extracts it by uncoupling it from the rack 10 and moves it away from the station 18, as soon as the push heads 27 have been brought back to their retracted position, by actuation of the transmission 29 The arrangement of all the organs of the device 1 now corresponds to the state of the aforementioned starting cycle and the cycle

  can again be repeated according to the same steps described.

  From what has been described above, it can be seen that the simplicity of manufacture, associated with the high operating reliability, makes it possible to significantly increase the production rate of the device, which can be associated with any line. production of small cages 4, while significantly increasing the production rate of

the very line.

  It is finally obvious that modifications and variations can be made to the device 1 described, without however departing from the spirit of the present invention. For example, different devices can be provided for the rotation of the grip heads 31 about the axes. 33 correspondents, as well as devices different from those described for command and control

push heads 27.

Claims (14)

  1 Device for manufacturing semi-finished metal wire products, characterized in that it comprises folding means (14) adapted so as to bend a metal wire (3), in order to form a ring (17) closed from substantially circular shape; a station (18) for forming said semi-finished product (2), in which said ring (17) is adapted so as to be placed in a position substantially coaxial with respect to a first axis (11); a plurality of forming groups (19) arranged in the forming station and each provided with a corresponding gripping head (31), the gripping heads (31) being arranged along respective second, substantially radial axes (33) relative to said first axis (11), and being adapted so as to positively couple with said ring (17), in order to fix the ring (17) even at a plurality of points delimiting respective sections (20) of the 'ring (17); pushing means (21) which can be associated with each of said sections (20), in order to advance an intermediate part (22) of each of the sections (20) itself, towards said first axis (11), along a third axis (28) substantially radial with respect to said first axis (11), and in order to carry respective end parts (24) of said sections (20), in positions located near the respective end parts (24) of the sections (20 ) adjacent; and first actuation means (48), used to rotate said gripping heads (31) around said respective second axes (22), in order to twist said said axes together   end parts (24) located next to each other.   2 Device according to claim 1, characterized in that said second axes (33) are all located in a forming plane (P) perpendicular to said first axis (11) and extend in fan shape from the first axis (11) itself , in angular positions which are spaced equally between them.   3 Device according to claim 2, characterized in that said third axes (28) are all located in said forming plane (P), in positions interspersed with respect to said second axes (33) and equally spaced with respect to said second axes (33) same.   4 Device according to any one of   previous claims, characterized in that it   comprises a forming surface (23) coaxial with respect to said first axis (11) and adapted so as to be arranged inside said ring (17); said pushing means (21) comprising, for each said section (20) of the ring (17), a pushing head (27) movable along a said third third axis (28) corresponding, between a first retracted position limit switch, in which the pusher head (27) itself is adapted to be disposed outside of said corresponding ring (17), and an advanced end position, in which the pusher head (21) is adapted so as to force the intermediate part (22) of said corresponding section (20) of the ring (17), to come into   abutment against said forming surface (23).   5 Device according to any one of   previous claims, characterized in that   said gripping heads (21) each comprise clamp means (56), adapted so as to positively couple with said ring (17), and in that each forming among said forming groups (19) further comprises a guide (32) extending along said corresponding second axis (33) and a carriage (34) coupled to the guide (32), so as to slide axially and to support said corresponding gripping head (31); second actuation means (36) being coupled to said carriages (34), so as to each be moved from said gripping heads (31), between a functional advanced position, in which said respective clamp means (56) are adapted so as to come into positive contact with said ring (17), at a said corresponding point, and a retracted position of rest, in which the clamp means (56) themselves are adapted so as to be arranged outside of said ring (17), said first actuating means (48) being adapted so as to rotate said gripping heads (31) only when the gripping heads (31) themselves are arranged near their advanced functional position .  6 Device according to claim 5, characterized by the fact that said second actuating means (36) comprise a first movable cam (37) and, for each said grip head (31), a first coupled push element (38), on one side, to the first cam (37) and, on the other   side, to said corresponding carriage (34).   7 Device according to claim 6, characterized in that said clamp means comprise a pair of claws (56) and said forming groups (19) further comprise each of the third actuating means (61, 62, 63) associated to each of said gripping heads (31), in order to cooperate with the respective claws (56), and control means (68) of said third actuation means (61, 62, 63), in order to move the claws (56 ) of each grip head (31), with respect to each other, between an open position and a closed position, in which they block between them said ring (17).   8 Device according to claim 7, characterized in that said control means (68) comprise a second cam (69) movable and, for each grip head (31), a second pusher element (70) coupled to said second cam and associated with said third means actuation (61, 62, 63).   9 Device according to claim 8, characterized in that said third actuation means (61, 62, 63) comprise a device (61, 62) with an inclined plane, disposed between the respective claws (56), and elastic means (63), adapted so as to exert on the respective claws (56) an action opposite to that exerted by said corresponding inclined plane device (61, 62). Device according to any one of   Claims 6 to 9, characterized in that it comprises   a motorized wheel (39), disposed in a coaxial position relative to said first axis (11) and capable of turning around this first axis (11), relative to said forming groups (19); said first and second cams being defined by a first groove (37) and, respectively, by a second annular groove (69) with variable radius, arranged on a front surface of the wheel (39), in concentric positions one by relative to each other and substantially coaxial with respect to said first axis (11); said first groove (37) and said second groove (69) being defined by a number of first parts (42) and, respectively, of second parts (71), with contiguous grooves and present in a number equal to that of said sets of forming (19), each of said first parts (42) and second parts (71) of groove forming an angle equal to an angle between said second axes (33).   11 Device according to claim 10, characterized in that said first groove parts (42) each comprise, in succession, a first curvilinear section (43) with substantially constant radius, a second straight section (44) with decreasing radius, a third curvilinear section (45) having a substantially constant radius and of a value less than that of said first section (43), a fourth section (46) substantially straight and with slightly decreasing radius, and a fifth section (47) inclined, substantially straight and increasing radius.   12 Device according to claim 11, characterized in that said second groove parts (71) each comprise, in succession, a first curvilinear section (72), with substantially constant radius, a second substantially straight section (73) with decreasing radius , a third substantially straight section (74) with decreasing radius, a fourth curved section (75), having a radius less than that of said first section (72) of said corresponding second part (71), a fifth substantially straight section (76) , with slightly decreasing radius, a sixth straight section (77) with decreasing radius, and a last inclined section (78),   substantially straight and with increasing radius.   13 Device according to claim 12, characterized in that said third section (74) of said second parts (71) is arranged substantially in correspondence with a point of convergence of said second (44) and third (45) sections of said first parts   (42) respective of the first cam (37).   14 Device according to any one of   Claims 5 to 13, characterized in that the said   gripping heads (31) each comprise a support shaft (35) coupled to a corresponding carriage (34), so as to be able to rotate around said second axis (33) and in an axially fixed position, and said first actuation means comprising a transmission (48) in turn comprising a first driving gear (50), common to all the gripping heads (31) and, for each of the gripping heads (31) themselves, a second toothed gear (49) with said first toothed wheel (50) and coupled to a said corresponding hub (35), by means of a corresponding first coupling groove (51). Method for manufacturing semi-finished products (2) from metal wire, characterized in that it comprises the steps of bending a metal wire (3), so as to form a closed ring (17) of substantially circular shape ; of connection, in correspondence with a forming station (18) and by means of a plurality of gripping heads (31), of said ring (17) in a position practically coaxial with respect to a first axis (11) and in a plurality of points delimiting respective sections (20) of the ring (17) itself, said gripping heads (31) being able to move along respective second axes (33), substantially radial with respect to said first axis (11); advancement, via the thrust means (21), of an intermediate part (22) of each said section (20), towards said first axis (11), along a third axis (28) respective, practically radial with respect to said first axis (11), so as to carry respective end portions (24) of each of said sections (20), in positions situated essentially near the respective end portions (24) of the sections (39 ) adjacent; and kinking said end portions (24) located substantially close to one another, by rotating said grip heads (31) around   of said respective second axes (33).   16 Method according to claim 15, characterized in that it comprises the step in which said intermediate parts (22) are forced to abut against a forming surface (23) substantially coaxial with respect to said first axis (11) and adapted so as to be disposed inside said ring (17), and in which the intermediate parts (22) are kept even locked against said forming surface (23), during the step   of kinking said end portions (24).