Patent Publication Number: US-2013230613-A1

Title: Apparatuses and methods for obtaining an object such as a seal, and a seal for containers

Description:
This application is a continuation of U.S. application Ser. No. 12/989,190 having an effective filing date of Jan. 11, 2011. Application Ser. No. 12/989,190 is a continuation of PCT International Application No. PCT/IB2009/005315 filed Apr. 21, 2009. PCT/IB2009/005315 claims priority to IT Application No. MO2008A000116 filed Apr. 22, 2008. The entire contents of these applications are incorporated herein by reference. 
    
    
     The invention relates to apparatuses and methods for obtaining an object provided with an edge zone that extends around a central space, particularly an annular object such as a seal suitable for being associated with caps for closing containers, for example bottles or jars. The invention further relates to a seal associable with caps of containers. 
     Caps are known comprising an end wall having a circular plan shape and a side wall provided with a fixing arrangement that enable the cap to be fixed in a removable manner to a neck of a container, for example a bottle. On the end wall there is provided a seal that usually comprises a relatively thin full central disc and a thicker annular zone that in use is arranged in contact with an edge of the neck of the bottle so as to prevent the substances contained in the bottle from escaping into the external environment and to prevent the substances present in the environment from contaminating the contents of the bottle. The seal may, for example, be formed by compression-moulding depositing inside the cap a dose of plastics in fluid or semifluid state and shaping the dose with a punch directly inside the cap. 
     One drawback of the seals of the type disclosed above is that they require high consumption of plastics, especially for forming the full central disc, that is of no utility during use because the sealing action is exerted exclusively by the annular zone. In order to reduce the quantity of plastics necessary for making a seal, PCT/IB2005/003054 discloses a seal comprising an annular zone suitable for engaging with the edge of the neck of the bottle and an internal region arranged inside the annular zone and connected thereto by a plurality of bridge elements. Between two adjacent bridge elements a through hole is obtained that enables the quantity of plastics consumed to be reduced. 
     The solution disclosed in PCT/IB2005/003054, whilst being an improvement on the seals with a full central disc, uses a not insignificant quantity of plastics in zones that exert no sealing action. In fact, both the internal region and the bridge elements constitute a limit in the attempt to diminish the quantity of plastics necessary for forming the seal. 
     Also the seals according to PCT/IB2005/003054 thus require a relatively great quantity of plastics, which entails high costs and grave environmental repercussions. 
     Apparatuses are further known for obtaining seals from a liquid. Plastics in liquid state, coming from a tank, are applied by a pistol to the internal surface of a cap, such as to shape an annular element. The latter, after possibly being centrifuged, is left to dry and heated such as to harden, so as to form the seal. 
     A drawback of the apparatuses for obtaining seals from a liquid is that they do not enable the shape of the seal to be controlled after the plastics have been applied to the internal surface of the cap. Consequently these apparatuses produce seals having a rather irregular shape. 
     Further, in known apparatuses, it is not possible to dose with precision the quantity of liquid dispensed. 
     Lastly, only a limited range of plastics are suitable for being applied to the cap in liquid state. Further, current legislations in the food field are rather restrictive with regard to the types of plastics that can be used to make seals. This makes it possible to form seals from a liquid with a very small number of plastics, which makes this system inflexible. 
     Italian patent application BO96A000538 discloses an apparatus for forming seals comprising a carousel on which are mounted a plurality of separating elements for separating doses of plastics from an extruder. The separating elements drop the doses inside a heated conduit in which the doses are compacted to form a continuous cylinder of plastics. From the heated conduit, the plastics pass to a plurality of radial conduits that dispense the plastics onto the cap so as to form an annular element. 
     The apparatus disclosed in BO96A000538 has a very complicated structure owing to the presence of the carousel supporting the separating elements, the heated conduit and the radial conduits. Further, high energy consumption is necessary to heat the plastics inside the heated conduit. 
     U.S. Pat. No. 5,686,040 shows a process for making a seal for caps of containers in which thermoplastic elastomeric material is deposited in a melted state under pressure on the periphery of the internal surface of the cap and is then compression-moulded directly on the cap by means of a punch. 
     An object of the invention is to improve the apparatuses and the methods for forming an object provided with an edge zone that extends around a central space, for example an annular object such as a seal for containers. 
     A further object is to improve the seals suitable for being associated with edges of containers, for example bottles or jars. 
     Another object is to reduce the quantity of material necessary for forming objects provided with an edge zone that extends around a central space, so as to reduce the costs thereof and to reduce the environmental impact thereof. 
     Another object is to provide apparatuses and methods that enable seals to be obtained that have a controlled shape. 
     Another object is to provide apparatuses and methods for forming seals from plastics that enable the quantity of plastics used for forming a seal to be dosed with precision. 
     Another object is to provide apparatuses and methods that enables seals with a wide range of plastics to be provided. A further object is to simplify the apparatuses and the methods used for forming seals. 
     In a first aspect of the invention, there is provided an apparatus for forming an object from plastics, said apparatus comprising: 
     a forming arrangement having a recess for forming an edge zone of said object, said recess extending around an internal region of said forming arrangement; 
     a conduit cooperating with a piston device to supply said plastics to said recess; wherein said conduit leads into said internal region, into a position contiguous with said recess. 
     In a second aspect of the invention, there is provided a method for forming an object from plastics, said method comprising the step of shaping said plastics in a recess to obtain an edge zone of said object, said recess extending around an internal region, wherein said plastics are supplied to said internal region in a position contiguous with said recess, so as to reach said recess flowing from said internal region. 
     Owing to the first and second aspect of the invention it is possible to reduce the quantity of plastics necessary to obtain an object having an edge zone. In fact, the plastics are supplied in a position contiguous with the recess in which the edge zone will be formed, which enables the long connecting paths to be avoided that in PCT/IB2005/003054 connected the zone in which the plastics were supplied to the edge zone of the object. 
     In a third aspect of the invention a seal is provided that is associable with a cap of a container, comprising an edge zone suitable for engaging an edge of said container, said edge zone extending around an empty space, wherein it comprises an appendage that is contiguous with said edge zone and projects inside said empty space. 
     Owing to the third aspect of the invention, it is possible to obtain a seal that is associable with a cap of a container that can be formed with a smaller quantity of material than known seals. In fact, the quantity of material is minimised that is necessary for forming parts of the seal that are different from the edge zone that, during use, exerts the seal action. The material that does not work when the seal is engaged with the edge of the container is only the material that forms the appendage, which can be manufactured with a quantity of plastics that is much less than the full central disks or bridge elements of the prior art. 
     In a fourth aspect of the invention, there is provided an apparatus comprising an extruding device for extruding plastics, a separating device for separating a dose of said plastics from said extruding device, a seal-forming arrangement for forming a seal from said dose in a forming chamber, said seal-forming arrangement having a conduit for conveying said dose from said separating device to said forming chamber, wherein said separating device is supported by said seal-forming arrangement. 
     Owing to this aspect of the invention, it is possible to obtain an apparatus for forming seals having a particularly simple structure. By using a separating device supported by the seal-forming arrangement it is in fact possible to avoid the carousels that, in the prior art, are dedicated exclusively to supporting and moving the separating device. 
     Further, the separating device separates a dose of plastics having a mass corresponding to the mass of the seal that it is desired to form. This dose, immediately after being separated from the separating device, is conveyed to the forming chamber through the conduit, along a relatively short path. This enables heating devices to be avoided for heating the doses whilst they are conveyed to the forming chamber and are compacted to form a continuous cylinder. 
     Lastly, the apparatus according to the fourth aspect of the invention enables seals of an annular shape to be obtained that require a reduced consumption of plastics. 
     In a fifth aspect of the invention, an apparatus is provided comprising a dispensing device for dispensing plastics to a supporting surface, a movement arrangement for mutually moving said dispensing device and said supporting surface such that the plastics dispensed by said dispensing device form a precursor of an annular object on said supporting surface, wherein it further comprises a forming arrangement for shaping said precursor on said supporting surface so as to obtain said annular object. 
     In a sixth aspect of the invention, a method is provided comprising the steps of: 
     dispensing plastics to a supporting surface by dispensing device; 
     mutually moving said dispensing device and said supporting surface such that the plastics dispensed by said dispensing device form a precursor of an annular object on said supporting surface, 
     wherein it further comprises the step of shaping said precursor on said supporting surface so as to obtain said annular object. 
     Owing to the fifth and to the sixth aspect of the invention, it is possible to obtain annular objects, for example seals, having a very precise shape. In fact, the forming arrangement enables the precursor of the annular object to be shaped according to the desired geometry. 
     The dispensing device further enables the quantity of plastics to be dosed with precision and many plastics that are different from one another to be processed. 
     In a seventh aspect of the invention a method according to the first claim is provided. 
     In an eighth aspect of the invention an apparatus according to claim fourteen is provided. 
     In a ninth aspect of the invention an apparatus according to claim twenty-five is provided. 
    
    
     
       The invention can be better understood and implemented with reference to the attached drawings, that illustrate some embodiments thereof by way of non-limiting example, in which: 
         FIG. 1  is a schematic plan view of an apparatus for forming objects from plastics, particularly seals for containers; 
         FIG. 2  is a schematic perspective view of a cap having a seal formed by the apparatus in  FIG. 1 ; 
         FIG. 3  is a section view of a forming arrangement included in the apparatus in  FIG. 1 , in a first operating position; 
         FIG. 4  is a section view like that in  FIG. 3 , showing the forming arrangement in a second operating position; 
         FIG. 5  is a section view like that in  FIG. 3 , showing the forming arrangement in a third operating position; 
         FIG. 6  is an enlarged section view showing a detail of the forming arrangement in the first operating position in  FIG. 3 ; 
         FIG. 7  is an enlarged section view showing a detail of the forming arrangement in the second operating position in  FIG. 4 ; 
         FIG. 8  is a view like that in  FIG. 7 , showing a detail of the forming arrangement in the third operating position in  FIG. 5 ; 
         FIG. 9  is a section view showing a forming arrangement according to an alternative embodiment, in an initial operating position; 
         FIG. 10  is a view like that in  FIG. 9 , showing the forming arrangement in a final operating position; 
         FIG. 11  is a section view showing a forming arrangement according to another alternative embodiment, in an initial operating position; 
         FIG. 12  is a view like that in  FIG. 11 , showing the forming arrangement in a final operating position; 
         FIG. 13  is an enlarged view showing an extruding nozzle of the embodiment in  FIGS. 11 and 12 ; 
         FIG. 14  is a plan view of the extruding nozzle in  FIG. 13 ; 
         FIG. 15  is a schematic section showing a screw cap having a seal obtained according to the invention; 
         FIG. 16  is a schematic section showing a twist-off lid having a seal obtained according to the invention; 
         FIG. 17  is a schematic section showing a lid according to an alternative embodiment having a seal obtained according to the invention; 
         FIG. 18  is a schematic view of an apparatus for dispensing precursors of annular objects; 
         FIG. 19  is a schematic view of a forming arrangement for shaping the precursors in  FIG. 18 . 
         FIG. 20  is a top plan view of an extruding device for plastics provided with plurality of extruding outlets. 
         FIG. 21  is a vertically elevated schematic section of the extruding device in  FIG. 20  in which a device is further shown for separating a plurality of doses of plastics from the flow dispensed through the extruding outlets; 
         FIG. 22  is an enlarged view of the dose-separating device in  FIG. 21 ; 
         FIG. 23  is a top plan view of a rotating carousel provided with a plurality of separating devices like that in  FIG. 22 , each of which operates to separate the doses of plastics from the extruder in  FIG. 20 ; 
         FIG. 24  is an enlarged detail in  FIG. 23  in which are traced the trajectories of separating elements of a separating device, each of which separates a dose of plastics from a respective extruding outlet; 
         FIG. 25  is a top plan view of a different embodiment of a rotating carousel operationally associated with a multiple-outlet extruder for plastics; 
         FIGS. 26 and 27  are two top plan views of two different embodiments of a multiple-outlet extruding device having a different number of extruding outlets with respect to the example in  FIG. 20 ; 
         FIGS. 28 and 29  are a top view and, respectively, a side view of a cap on which a seal is formed; 
         FIG. 30  is a vertically elevated view of a support for the cap in  FIGS. 28 and 29  on which forming of the seal occurs; 
         FIG. 31  is a vertically elevated view of a moulding device in which the separating device in  FIG. 22  has already deposited a plurality of doses inside the cap in  FIGS. 28 and 29  carried by the support in  FIG. 30  and in which a punch inserted into the cap is ready to compression-mould the doses to form the seal; 
         FIG. 32  is an enlarged detail of  FIG. 31 ; 
         FIG. 33  is the view in  FIG. 31  with the punch in a different operating configuration; 
         FIG. 34  is an enlarged detail of  FIG. 33 ; 
         FIG. 35  is the view of the cap in  FIG. 28  inside which the doses of plastics have been deposited to form the seal; 
         FIG. 36  is the view of the cap in  FIG. 29  with the ready-formed seal; 
         FIG. 37  is a top plan view of a further embodiment of an extruding device having a different form of extruding outlets from the examples in  FIGS. 20 ,  26  and  27 . 
     
    
    
       FIG. 1  shows an apparatus  1  for moulding objects made of plastics. In particular, the apparatus  1  enables seals to be moulded inside caps for containers, for example for bottles or for jars. 
     The caps processed by the apparatus in  FIG. 1  can be made of plastics, for example by compression-moulding or injection moulding. Alternatively, the apparatus  1  can process caps made of metal, for example crown caps or twist-off lids intended for closing jars. 
     The objects, and in particular the seals, produced by the apparatus  1  can be made from plastics selected from a group comprising: polyethylene copolymers (LLDPE, LDPE, Metocene), styrene block copolymers, in particular having a two-block structure, a three-block structure or ramified structure (for example S-B-S, S-I-S, S-EB-S), polypropylene and EPDM mixtures, polypropylene and EPR mixtures, dynamic vulcanised polypropylene and EPDM products, dynamic vulcanised polypropylene and butyl rubber products, dynamic vulcanised polypropylene and natural rubber products, dynamic vulcanised polypropylene and nitrile rubber products. 
     The apparatus  1  comprises a moulding carousel  2  supporting, in a peripheral region thereof, a plurality of moulding units that will be disclosed in detail below. Each moulding unit enables a seal to be formed inside a corresponding cap. The moulding carousel  2  is rotatable around an axis, for example vertical, in a rotation direction R. 
     A supplying and orientating device  3  enables a plurality of caps inside which the seals have to be moulded to be supplied in sequence to the moulding carousel  2 . The caps that exit the supplying and orientating device  3  are all orientated in the same manner. The supplying and orientating device  3  is connected, by an inlet conveyor  4 , to a supply wheel  5  arranged for transferring in sequence each cap to the corresponding moulding unit of the moulding carousel  2 . The supply wheel  5  can be of the star type. The supply wheel  5  delivers each cap to the corresponding moulding units in a delivery position A arranged along the circular path of the moulding unit. 
     The apparatus  1  comprises an extracting wheel  6 , which may be of the star type, to remove from each moulding unit a cap inside which a seal has been formed. The caps having the seals are subsequently removed from the extracting wheel  6  by means of an outlet conveyor  7 . The extracting wheel  6  removes the caps having the seals in an unloading position B arranged along the path of the moulding units. The unloading position B is arranged downstream of the delivery position A with respect to the rotation direction R. 
     The apparatus  1  further comprises an extruder  8  having an extruding nozzle  9  for dispensing plastics in a pasty state intended for forming the seal. The extruding nozzle  9  is arranged in an extruding position C immediately downstream of the delivery position A. 
       FIG. 2  shows a cap  10  having a seal  11  that can be formed by the apparatus  1 . The cap  10  comprises an end wall  12 , which can be substantially flat, having a circular plan shape. From the end wall  12  a side wall  13  projects, which may be cylindrical in shape. An internal surface of the side wall  13  is provided with a fixing arrangement that is not shown that enables the cap  10  to be fixed in a removable manner to a neck of a container. The fixing arrangement can comprise a thread or one or more ridges. 
     The seal  11  is fixed to the end wall  12 , the seal  11  comprises an edge zone  14  suitable for engaging with an edge of the neck of the container to close the container in a substantially hermetic manner. The edge zone  14  has an annular shape and is in particular shaped like a circular ring. In the seal  11 , the edge zone  14  surrounds an empty space  15 . In other words, there is no material of the seal  11  inside the edge zone  14 . 
     The seal  11  comprises an appendage  45  that projects inside the empty space  15  from the edge zone  14 . In other words, the appendage  45  protrudes inside the edge zone  14 . The appendage  45  can have the shape, if seen in a plan view, of a circle portion. It is nevertheless possible to adopt also different shapes from the circle portion for the appendage  45 . 
     The reasons for which the appendage  45  is present will be explained below with reference to  FIGS. 3 to 8 . 
       FIGS. 3 to 5  show a forming arrangement  16  for forming a seal  11  inside a cap  10 . The forming arrangement  16  of the type shown in  FIGS. 3 to 5  can be included in each moulding unit mounted on the moulding carousel  2  of the apparatus  1 . 
     The forming arrangement  16  comprises a punch member  17  suitable for penetrating inside a cap  10  to shape the plastics such as to shape the seal  11 . As shown in  FIG. 6 , the punch member  17  comprises a central element  18 , having a front surface  19  that can contact the end wall  12  of the cap  10 . A sleeve  20  surrounds the central element  18 . 
     In the illustrated embodiment, the sleeve  20  and the central element  18  are fixed to one another. Nevertheless, the sleeve  20  can also be movable with respect to the central element  18 . In this case, a spring can be provided for acting on the sleeve  20 . 
     The sleeve  20  has an annular end  21  suitable for coming to abut on the end wall  12  of the cap  10 . 
     On the punch member  17  there is obtained a recess  22 , defined between the central element  18  and the annular end  21  of the sleeve  20 . The recess  22  may have the shape of an annular, for example circular, groove corresponding to the shape of the edge zone  14  of the seal  11 . The recess  22  surrounds the front surface  19 , which can thus be considered to be an internal region of the forming arrangement  16 . 
     The central element  18  and the sleeve  20  are fixed to a supporting arrangement  23 , which comprise a supporting element  24  in which a cooling circuit  25  can be obtained, through which a cooling liquid passes coming from a pipe that is not shown. A chamber  26  is obtained in the central element  18  and receives the liquid of the cooling circuit  25  so as to keep the temperature of the regions of the central element  18  and of the sleeve  20  that form the seal  11  low. 
     On the supporting element  24  there is mounted, for example by screws  27 , a separating device comprising a separating member  28  for separating doses of plastics from the extruding nozzle  9 . The separating member  28  has a seat  29  the height of which is such as to receive an end portion of the extruding nozzle  9 . 
     Inside the extruding nozzle  9  there is obtained an extruding conduit having a first portion  30  that extends along an axis D. In the example shown, the axis D is substantially horizontal. A second portion  31  of the extruding conduit is arranged downstream of the first portion  30  and is transverse, for example perpendicular, to the first portion  30 . In the example shown, the second portion  31  is substantially vertical. The second portion  31  leads onto an outlet surface  32  that, in the example shown, is substantially horizontal. 
     The seat  29  is bounded, in a lower region thereof, by a separating surface  33  suitable for interacting with the outlet surface  32  to remove therefrom a dose of plastics. In the example shown, the separating surface  33  is substantially flat and is arranged horizontally. 
     Inside the punch member  17  a conduit  34  is obtained, the conduit  34  being defined by a through hole that passes through the supporting element  24  and the central element  18 . The conduit  34  may have a circular cross section. The conduit  34  has an end leading onto the front surface  19 , i.e. in the central region of the forming arrangement  16 . This end leads into a position that is contiguous with the recess  22 . At a further end of the conduit  34  there is a channel  40 , open on a side, that is obtained in a lower region of the separating member  28 . The channel  40  leads into the separating surface  33 . In the example shown, the conduit  34  is rectilinear and substantially vertical. 
     The forming arrangement  16  comprises a piston  35  that is movable along a direction E parallel to a longitudinal axis along which the punch member  17  extends. The piston  35  can move between a retracted position shown in  FIG. 3  and an extended or forming position shown in  FIG. 5 . In the retracted position, the piston  35  is not present inside the conduit  34 , or in the seat  29 . In the extended position, the piston  35  passes through the conduit  34  until it reaches near the front surface  19 . The piston  35  is moved along the direction E by a driving device comprising a cam member  46  that engages with a wheel  47  associated with the piston  35 . 
     The punch member  17  is fixed to a supporting body  48  of the moulding carousel  2 . 
     Each moulding unit further comprises an extracting element  49 , having a side projection  50 , which can be substantially flat, suitable for engaging with an edge of the side wall  13  of the cap  10 , in order to separate the cap  10  from the punch member  17 , after the seal  11  has been formed. 
     The extractor  49  is fixed to a first end of a rod  37 . At a second end of the rod  37 , opposite the first end, there is mounted a roller  36  that engages with a cam that is not shown. This cam enables the extractor  49  to be moved parallel to the direction E to remove the cap  10  from the punch member  17 . 
     In an alternative embodiment, the extractor  49  can be moved by a movement device that is different from the cam and from the roller  36 , for example comprising an elastic member such as a spring. 
     There is also provided a stem  38 , having an upper end that supports a supporting element  39  on which a cap  10  can be rested. The supporting element  39  supports the cap  10  and pushes the cap with force to the punch member  17  whilst the seal  11  is formed inside the cap  10 . 
     The stem  38  is included in an actuator, for example of hydraulic type, arranged for moving the supporting element  39  parallel to the direction E, so as to move the cap  10  towards the punch member  17  or move the cap  10  away from the punch member  17 . 
     During operation, the supporting element  39  is initially at a certain distance from the punch member  17 . In the delivery position A, the supply wheel  5  conveys a cap  10  to the corresponding moulding unit and deposits the cap  10  on the supporting element  39  of the moulding unit. 
     The stem  38  rises, moving parallel to the direction E, i.e. vertically, and moves the cap  10  towards the punch member  17 . In this manner, the punch member  17  penetrates inside the cap  10 , until the end wall  12  comes to abut against the front surface  19 . 
     In this position, as shown in  FIG. 6 , between the punch member  17  and the end wall  12  of the cap  10  an annular forming chamber  42 , is defined in which the edge zone  14  of the seal  11  will be formed. In particular, the annular forming chamber  42  is defined inside the recess  22 , closed by the end wall  12 . The annular forming chamber  42  is in communication with the conduit  34 , which leads into a position adjacent to the recess  22 . In other words, the conduit  34  is directly in communication with the recess  22 , without connecting portions having to be interposed between the conduit  34  and the recess  22 . 
     When the moulding carousel  2  takes the corresponding moulding unit to the extruding position C, the end portion of the extruding nozzle  9  is housed inside the seat  29 . The separating surface  33  comes into contact with the outlet surface  32  of the extruding nozzle  9 . The separating surface  33  scrapes from the outlet surface  32  a dose  41  of plastics, corresponding to the quantity of plastics that exits the extruding nozzle  9  in the period that elapses between the passage of the separating members  28  of two successive moulding units at the extruding position C. The dose  41  is received inside the channel  40  that, as already disclosed previously, is open on one side. This situation is shown in  FIGS. 3 and 6 . 
     Subsequently, owing to the rotation of the moulding carousel  2 , the forming arrangement  16  moves away from the extruder  8 . The seat  29  of the separating member  28  disengages from the extruding nozzle  9 . 
     The cam member  46  drives the piston  35  such that the latter moves to the extended position. The piston  35  thus penetrates the seat  29  and, subsequently, inside the channel  40  and then the conduit  34 . In this manner, the piston  35  pushes the dose  41  contained in the channel  40  inside the conduit  34 , such that the dose  41  moves towards the end wall  12  of the cap  10 . In the position shown in  FIGS. 4 and 7 , the dose  41  is in contact with the end wall  12 . 
     From this moment forth, as the piston  35  penetrates further into the conduit  34 , the dose  41  is compressed and, from the conduit  34 , passes into the adjacent annular forming chamber  42 . The annular forming chamber  42  is thus gradually filled by the plastics pushed by the piston  35 . In this manner the edge zone  14  of the seal  11  is formed. 
     As shown in  FIGS. 5 and 8 , the piston  35  stops inside the conduit  34 , in the extended position, when a thrusting surface  43  of the piston  35 , which bounds the piston  35  transversely to the direction E, is near a transverse surface  51  that bounds the recess  22  transversely to the direction E. 
     In particular, in the extended position the thrusting surface  43  of the piston  35  can be flush with the transverse surface  51  of the recess  22 , even if this is not a necessary condition, as will be disclosed better below. 
     In the extended position, between the piston  35  and the side wall  12  there is defined an internal forming chamber  44  that, if viewed in a plan view, is arranged inside the annular forming chamber  42 . The internal forming chamber  44  is contiguous with the annular forming chamber  42 . When the piston  35  stops in the extended position, inside the internal forming chamber  44  a certain quantity of plastics remain that form the appendage  45  of the seal  11 . 
     In conclusion, the plastics flow from the internal forming chamber  44  to the annular forming chamber  42  moving in a direction that goes from the centre to the periphery, in particular in a centrifugal direction. 
     The internal forming chamber  44  and the piston  35  that bounds the internal forming chamber  44  act as a compensating element for compensating possible weight variations of the dose  41 . If, in fact, the dose  41  has a mass that is slightly greater than a theoretical value, the piston  35  stops in an extended position such as to form an appendage  45  having a greater thickness, for example greater than the thickness of the edge zone  14 . If on the other hand the dose  41  has a lesser mass than the theoretical value, the piston  35  forms an appendage  45  having a reduced thickness, for example less than the thickness of the edge zone  14 . In other words, possible variations of the mass of the dose  41  are translated into variations in the thickness of the appendage  45 . As the appendage  45  does not participate in the sealing action exerted by the edge zone  14  during use, possible variations in the thickness of the appendage  45  do not influence the correct operation of the seal  11 . 
     The punch member  17  and the cap  10  remain in the position shown in  FIGS. 5 and 8  for a sufficient time for the plastics constituting the seal  11  to stabilise. Subsequently, the stem  38  moves the supporting element  39  downwards, whilst the side projection  50  of the extracting element  49  acts on the upper edge of the cap  10  to remove the cap  10  from the punch member  17 . The cap  10  is subsequently moved away from the moulding carousel  2  owing to the extracting wheel  6 . 
     The supporting element  39  is now ready for receiving a new cap, so that a new forming cycle can be initiated. 
     The forming arrangement  16  enables seals with reduced consumption of plastics to be obtained. In fact, the appendage  45  is made with a limited quantity of plastics. The quantity of plastics is thus minimised, which, during use of the seal, is not engaged with the neck of the container and therefore has not utility. 
       FIGS. 9 and 10  show an alternative embodiment in which the parts common to the preceding embodiment will be indicated by the same reference numbers as those used in  FIGS. 3 to 8  and will not be disclosed again in detail. In the embodiment in  FIGS. 9 and 10 , each moulding unit comprises a punch member  117  that is moved by the stem  38  that supports the supporting element  39 . For this purpose, the punch member  117  comprises a supporting element  124  fixed to a cup body  52  that is movable inside a housing element  53 . The housing element  53  is in turn fixed to a plate  54  arranged in a fixed position on the moulding carousel  2 . 
     Inside the cup body  52  an elastic member is arranged, which may comprise a spring  55 , for example a coil spring. The spring  55  has a first end in contact with the plate  54  and a second end in contact with an abutting surface  56  of the cup body  52 . The spring  55  is mounted in such a manner as to push the punch member  117  to the stem  38 . 
     On the plate  54  a bar  57  is further fixed, shown in  FIG. 10 , at a lower end of which a piston  135  is obtained, having a function that is similar to the piston  35  disclosed with reference to  FIGS. 3 to 8 . The bar  57  is integral with the piston  135 . The piston  135  is thus fixed to the moulding carousel  2 . 
     The stem  38 , as already disclosed with reference to  FIGS. 3 to 8 , is on the other hand included in an actuator that moves the stem  38  along a longitudinal axis F thereof. During operation, the stem  38  and the supporting element  39  fixed thereto are initially in a lowered position, shown in  FIG. 9 , in which the supply wheel  5  takes a cap  10  to the supporting element  39 . 
     The cup body  52  is pushed to the punch member  117  by the spring  55  and is in an advanced configuration in which a flanged edge  58  of the cup body  52  abuts against a step  59  obtained inside the housing element  53 . 
     Owing to the rotation of the moulding carousel  2 , the separating member  28  reaches the extruding nozzle  9  and separates the dose  41 , which is received inside the open channel obtained in the separating member  28 . 
     The stem  38  is then gradually lifted by the corresponding actuator and takes the end wall  12  of the cap  10  into contact with the central element  18  and with the sleeve  20 . 
     The stem  38  continues to move upwards along the longitudinal axis F and lifts the cap  10  and the punch member  117  engaged with the cap  10 . The thrust exerted by the stem  38  enables the force of the spring  55  to be overcome so that the cup body  52  moves inside the housing element  53  and the flanged edge  58  approaches the plate  54 . The punch member  117  thus reaches a retracted configuration as shown in  FIG. 10 . 
     Whilst the punch member  117  rises upwards to reach the retracted configuration, the piston  135 , which is fixed to the carousel  2 , penetrates first inside the open channel obtained in the separating member  28  and then inside the conduit  34 . The dose  41  is thus pushed to the cap  10 . The plastics, after coming into contact with the end wall  12  of the cap  10 , move from the centre to the periphery and pass from the conduit  34  to the recess  22 . The plastics gradually fill all the annular forming chamber  42  and give rise to the seal  11 , as previously explained with reference to  FIGS. 6 to 8 . 
     The embodiment shown in  FIGS. 9 and 10  enables a single actuating device to be used, i.e. the actuator in which the stem  38  is included for moving both the supporting element  39  and the punch member  117 , whilst the piston  135  is maintained in a fixed position. In this manner, it is possible to avoid using, in addition to the actuating device that moves the supporting element  39 , a further actuating device for moving the piston  135 . This simplifies the structure of each moulding unit. 
       FIGS. 11 and 12  show another alternative embodiment, which differs from the embodiment shown in  FIGS. 9 and 10  through the configuration of the extruding nozzle. In the embodiment in  FIGS. 11 and 12  an extruding nozzle  109  is in fact provided inside which an extruding conduit is obtained leading onto an outlet surface  132  that, in the example shown, is substantially vertical. 
     The supporting element  124  supports a separating member  128 , shown in detail in  FIGS. 13 and 14 , having an upper portion  60  and a lower portion  61  between which there is defined a seat  129 . In the upper portion  60  a through hole  62  is obtained that can receive the piston  135 . 
     From the lower portion  61  a protruding element  63  projects, for example a protruding element  63  in the shape of a hollow cylinder, suitable for being received inside the supporting element  124 . The lower portion  61  and the protruding element  63  are drilled, so as to permit the passage of the piston  135 . 
     The seat  129  is further bounded by a side wall  64 , which connects the lower portion  61  to the upper portion  60 . In the side wall  64  an open channel  140  is obtained, which in the example shown is substantially vertical, arranged for receiving the dose  41 . The side wall  64  is bounded by a separating surface  133 , suitable for interacting with the outlet surface  132  of the extruding nozzle  109  to remove the dose  41  therefrom. In the example shown, the separating surface  133  is substantially vertical. 
     During operation, the stem  38  is initially in the lowered position in which, as shown in  FIG. 11 , the supply wheel  5  takes a cap  10  to the supporting element  39 . 
     The punch member  117  is pushed by the spring  55  in the advanced configuration. 
     When, during rotation of the moulding carousel  2 , the separating member  128  arrives at the extruding nozzle  109 , the separating surface  133  scrapes a dose  41  of plastics from the outlet surface  132 . As shown in  FIG. 11 , the dose  41  is housed inside the channel  140  and, following rotation of the moulding carousel  2 , is moved away from the extruding nozzle  109 . 
     Subsequently, the actuator starts to move the supporting element  39  upwards, together with the cap  10  supported thereby. The end wall  12  of the cap  10  thus comes into contact with the central element  18  and the sleeve  20 , after which the punch member  117  is moved upwards by the stem  38 , which overcomes the force of the spring  55 . The piston  135 , on the other hand, remains in a fixed position with respect to the moulding carousel  2 . 
     As the punch member  117  is moved upwards, the piston  135  first penetrates the through hole  62 , subsequently the channel  140  and lastly the conduit  34 , thus pushing the dose  41  inside the recess  22  for forming the edge zone  14  of the seal  11 , as shown in  FIG. 12  and as previously disclosed with reference to  FIGS. 6 to 8 . 
       FIGS. 15 to 17  show different types of caps inside which different types of seals can be moulded by using the apparatus  1 . In particular,  FIG. 15  shows a screw cap  110 , which can be obtained by injection or compression-moulding plastics. The screw cap  110  comprises an end wall  112  and a side wall  113  inside which one or more threads  65  are obtained for enabling the screw cap  110  to be removably fixed to the neck of a container. On the end wall  112  there is obtained a seal  111  that may comprise an appendage that is not shown, that is similar to the appendage  45  shown in  FIG. 2 . The seal  111  comprises a lip  66  arranged for engaging with the neck of the container to exert a sealing action. 
     In an embodiment that is not shown, the seal  111  could be provided with two lips. 
       FIG. 16  shows a lid  210 , of the so-called twist-off type, usable for closing containers with a wide mouth such as jars. The lid  210  can be made of a metal material and comprises an end wall  212  to which a side wall  213  is adjacent. An edge of the side wall  213  is folded inside the lid  210 . The lid  210  is provided with a seal  211 , which may comprise an appendage that is not shown that is similar to the appendage  45 . In the example shown, the seal  211  is provided with a lip  266 , but two lips could also be present. The seal  211  is housed inside a throat  67  included in the end wall  212 . 
       FIG. 17  shows a cap  310 , of the so-called twist-off type, having a side wall  313  provided with an edge that, unlike the cap in  FIG. 16 , is not folded inside the cap  310  but is substantially straight. In a throat  367  obtained in an end wall  312  of the cap  310  a seal  311  is housed, having a substantially flat central zone surrounded by a peripheral annular ridge, possibly comprising an appendage that is similar to the appendage  45 . 
     Whilst in  FIGS. 3 to 12  the punch member inside which the piston is arranged is always positioned above the cap  10 , it is also possible for the punch member to be arranged below the cap inside which the seal has to be formed. 
     Further, instead of forming the seals  11  directly inside the caps  10 , it is possible to form the seals  11  on an abutting surface of the apparatus  1  and subsequently associate, for example by gluing, each seal with a corresponding cap. 
     Also, the recess  22  and the internal forming chamber  44 , rather than being obtained on the punch member, can be made in the end wall  12  of the cap  10 . In this case the punch member has a substantially flat forming surface. 
     In an embodiment that is not shown, the conduit  34 , instead of leading onto the front surface  19 , can lead directly into the recess  22 , in which case seals devoid of the appendage  45  will be obtained. 
     The forming arrangement  16 , rather than being mounted on a carousel, can be arranged in a different manner, for example along the path of a closed-loop conveyor belt. 
     The forming arrangement  16  can further be used for forming objects other than the seals, for example objects with an annular shape or objects having a central hole or more in general entirely hollow objects. 
       FIGS. 18 and 19  show an apparatus for forming annular objects according to an alternative embodiment. The annular objects formed by the apparatus in  FIGS. 18 and 19  can be seals, for example having cross sections of the type shown in  FIGS. 15 to 17 , arranged inside caps made of metal or plastics, for example caps of the type shown in  FIGS. 15 to 17 . The materials used for forming the seals in the apparatus in  FIGS. 18 and 19  can be the same materials listed previously with reference to the apparatus  1 . 
     As shown in  FIG. 18 , the apparatus comprises a dispensing unit  93  including an extruding device  68  provided with a screw  69  for extruding plastics in an extruding direction that, in the example shown, is substantially horizontal. The extruded plastics are in a pasty state. 
     The apparatus further comprises a dispensing device including a dispensing nozzle  70  arranged for receiving the plastics coming from the extruding device  68  and for dispensing the plastics inside a cap  410 , which in the example shown is a twist-off lid. 
     The dispensing nozzle  70  can be tilted in such a way as to dispense the plastics in an outlet direction tilted with respect to the vertical direction. 
     The dispensing nozzle  70  is connected to the extruding device  68  by means of a block  71  inside which a passage  72  is obtained for the plastics. The passage  72  may comprise a first substantially horizontal portion followed by a second tilted portion, so as to deviate the plastics from the extrusion direction to the direction of exit from the dispensing nozzle  70 . 
     The dispensing nozzle  70  comprises a plug  73 , having, for example, the shape of a stem, that is slidable inside the dispensing nozzle  70  so as to open or close the dispensing nozzle selectively, to permit or interrupt the dispensing of the plastics. The plug  73  can be moved by a motor  74 , for example fixed to the extruding device  68  by a flange  75 . Alternatively to the motor  74 , it is possible to use other movement systems for driving the plug  73 , for example a piston, a solenoid valve or a rotating motor. 
     The dispensing nozzle  70  is positioned above a supporting element  139  suitable for supporting temporarily the cap  410 . The supporting element  139  may have the shape of a disc fixed to the top of a column  76 . With the supporting element  139  a retaining arrangement is associated for retaining the cap  410  in contact with the supporting element  139  whilst the plastics are deposited inside the cap  410 . The retaining arrangement may comprise a sucking device including, for example, a sucking source that is not shown that is connected, through a sucking conduit  77  obtained inside the column  76 , to a plurality of sucking holes  78  of the supporting element  139 . 
     Alternatively, the retaining arrangement can comprise a gripper device, or a magnet, or also a solenoid valve or something else. 
     The apparatus further comprises a movement arrangement for moving the supporting element  139  with respect to the dispensing nozzle  70  whilst the plastics are dispensed inside the cap  410 . In this manner, the zone of the cap  410  in which the plastics are dispensed changes continuously whilst the dispensing nozzle  70  is open. This enables the plastics to be dispensed inside the cap  410  according to a desired path, such as to shape an extruded product having any preset shape. 
     In particular, the movement arrangement may comprise a rotating member for rotating the supporting element  139  around a rotating axis Z, for example vertical, such as the axis of the column  76 . In this manner, as the dispensing nozzle  70  is arranged in a fixed position during dispensing, the plastics are deposited on the cap  410  according to an annular geometry, in particular a circumference shape. 
     The rotating member may comprise a motor device  79 , fixed to a base  80  of the apparatus, having a driving shaft  81 . On the driving shaft  81  a driving pulley  82  is splined that drives, by a drive belt  83 , a driven pulley  84  that is stiffly connected to the column  76 . The latter is mounted inside a sleeve  85  fixed to the base  80 . Between the sleeve  85  and the column  76  bearings  86  are interposed that enable the column  76  to rotate with respect to the sleeve  85 . 
     During operation, a cap  410  is positioned on the supporting element  139  by means of a supplying device that is not shown. The sucking device is activated to retain the cap  410  firmly in contact with the supporting element  139 . 
     The motor  74  drives the plug  73  such as to open the dispensing nozzle  70 , which is positioned inside the cap  410 . The plastics exiting the extruding device  68  through the passage  72  reach the dispensing nozzle  70 , which deposits the plastics on a supporting surface  87 , which is the internal surface of the cap  410  on which the seal has to be formed. Simultaneously, the movement arrangement rotates the column  76 , together with the supporting element  139 , around the rotating axis Z. The cap  410 , maintained adhering to the supporting element  139  owing to the sucking device, also rotates the supporting element  139  around the rotating axis Z whilst the dispensing nozzle  70  dispenses the plastics. In this manner, the plastics are deposited on the supporting surface  87  so as to form a precursor of the seal, said precursor having an annular, particularly circular conformation. The precursor of the seal can have an approximately circular cross section, even if this condition is not necessary. 
     When the precursor of the seal has been completed, the plug  73  closes the dispensing nozzle  70  and the cap  410  can be moved away from the dispensing nozzle  70  to complete forming of the seal. 
     In an embodiment that is not shown, instead of moving the cap  410  and maintaining the dispensing nozzle  70  stationary, it is possible to move the dispensing nozzle  70  and maintain the cap  410  stationary. The dispensing nozzle  70  can be moved by a suitable movement arrangement, which may comprise a rotating member to rotate the dispensing nozzle  70  around a rotating axis, for example a vertical rotating axis. 
     In another embodiment that is not shown, the movement arrangement can be associated both with the dispensing nozzle  70  and with the cap  410 , so as to move suitably the dispensing nozzle  70  and the cap  410  so that the plastics can form the precursor desired on the supporting surface  87 . 
     In the last two cases disclosed, in which the dispensing nozzle  70  is moved, the dispensing nozzle  70  can be connected to the extruding device  68  by flexible conduits or by a rotating joint. 
     The movement arrangement can enable the dispensing nozzle  70  and the cap  410  to move mutually with a movement that is not necessarily a rotation movement. This enables annular seals to be obtained that have a shape that is not necessarily circular, for example elliptical, square, polygonal or other. 
     In an alternative embodiment, the supporting surface  87 , rather than being the internal surface of the cap  410 , can be the surface of a mechanical component included in the apparatus on which the seal is formed, which will subsequently be removed from the supporting surface  87  and applied to a corresponding cap. 
     The apparatus further comprises a forming arrangement to shape the precursor so as to obtain the desired annular object, for example the seal. The forming arrangement may comprise a compression-forming arrangement that compression-moulds the precursor so as to obtain the seal. 
     The forming arrangement is shown in  FIG. 19  and may comprise a forming carousel  88  comprising a plurality of forming units  89 , only one of which is shown. Each forming unit  89  comprises a supporting member  90  for supporting a cap  410  inside which the plastics are deposited forming the precursor of the seal. The supporting member  90  may have an upper surface shaped so as to engage in a shapingly coupled manner with an external wall of the cap  410  opposite the supporting surface  87 . The supporting member  90  is fixed to a stem  138 , moved by an actuator that is not shown in a forming direction M that, in the example shown, is substantially vertical. 
     Each forming unit  89  further comprises a punch member  217  for shaping the precursor inside the cap  410  such as to shape the seal. The punch member  217  comprises a central element  218  having a front surface  219  suitable for coming to abut on the supporting surface  87  of the cap  410 . 
     Outside the central element  218  there is arranged an intermediate sleeve  91 , included in the punch member  217 , bounded by a forming surface  92  having a shape corresponding to that of the desired seal. In the example shown, the forming surface  92  coincides with a lower surface of the intermediate sleeve  91 . 
     The punch member  217  further comprises an external sleeve  220 , arranged outside the intermediate sleeve  91 , having an annular end  221  suitable for coming to abut on the supporting surface  87  of the cap  410 . In this manner, the external sleeve peripherally bounds a forming chamber inside which the seal can be formed. 
     A spring element  94  can act on the external sleeve  220 , so as to push the external sleeve  220  towards the supporting member  90 . 
     During operation, a transferring device that is not shown conveys the cap  410  from the extruding unit  93  to a forming unit  89 . The cap  410  is delivered to the supporting member  90 , which the corresponding actuator has positioned in a position spaced away from the punch member  217 . 
     The actuator then moves the cap  410  to the punch member  217 , to a point in which the supporting surface  87  of the cap  410  abuts on the external sleeve  220 . The intermediate sleeve  91  is in a retracted position with respect to the external sleeve  220  and to the central element  218 , such that between the external sleeve  220  and the central element  218  an annular recess is defined in which the precursor of the seal can be received. The spring  94  can enable the external sleeve  220  still to retreat slightly, to enable the central element  218  to abut on the cap  218  and to enable the seal to be formed from the corresponding precursor. 
     When the seal has been formed and the shape thereof has been stabilised the actuator moves the supporting member  90  away from the punch member  217  and an extractor  95  detaches the cap  410  from the punch member  217 . The cap  410  can thus be moved away from the supporting member  90 , which is ready to receive a new cap to be processed. 
     As already mentioned previously, the apparatus comprises a transferring device for transporting the cap  410 , having the precursor of the seal inside, from the dispensing unit  93  to a forming unit  89 . The transferring device can convey the cap  410  along a short path, so as to ensure a short transfer time to prevent the precursor of the seal cooling and hardening excessively. 
     Alternatively, along the path of the transferring device a heating device can be positioned to prevent the plastics constituting the precursor of the seal and/or the cap  410  cooling excessively. The heating device may comprise, for example, a tunnel inside which hot air circulates, or a radiofrequency heater, if the cap  410  is made of metal material. 
     Different possible alternatives are possible for the layout of the apparatus. 
     In a first embodiment, the dispensing unit  93  can be configured as an independent machine, connected, by the transferring device, to a further independent machine on which one or more forming units  89  are mounted. 
     In a second embodiment, the dispensing unit  93 , the conveying device and the forming unit  89  (or the forming units  89 ) can be integrated into a single machine. The machine can comprise a first carousel that makes the caps  410  interact with the dispensing nozzle  70 , a possible second transferring carousel and the forming carousel  88  supporting a plurality of forming units  89 . 
     In a third embodiment, dispensing the plastics for forming the precursor and the forming of the seal by the precursor can be integrated into a single device. For example, a main carousel can be provided having a plurality of forming units  89 , each of which comprises the supporting member  90  and the punch member  217 . After a cap  410  has been positioned on a corresponding supporting member  90 , the latter, which is still spaced away from the corresponding punch member  217 , can interact with a dispensing nozzle  70  that deposits inside the cap  410  the plastics for forming the precursor of the seal. The supporting member  90  can rotate around an own axis to enable the plastics to form an annular precursor. Subsequently, during rotation of the main carousel, the forming unit  89  disengages from the dispensing nozzle  70  and the corresponding actuator moves the supporting member  90  to the punch member  217  so that the precursor can be shaped to give rise to the seal. 
     It should be noted that the forming units  89  do not necessarily have to be mounted on a carousel, but can also be moved along a non-circular path, for example by means of a belt device. 
     Further, in all the embodiments downstream of the forming units  89 , accessory devices can be provided, for example vision systems for controlling the quality of the cap and/or of the seal. 
     The apparatus shown in  FIGS. 18 and 19  enables seals to be formed with reduced consumption of plastics. The punch member  217  ensures that the seals have a precise shape, whilst the dispensing nozzle  70  ensures that the quantity of plastics that forms each seal is well dosed. Lastly, the apparatus shown in  FIGS. 18 and 19  enables seals to be formed by using many types of different plastics that the user can select freely according to need. 
     Forming an object made of plastics (in particular of annular shape) is now disclosed (with particular reference to  FIGS. 20 to 37 ), which may comprise, as in this specific case, a seal for a closure for containers of known type (capsule, cap, lid, etc). The closure may be made of plastics and/or of metal and/or of still other known materials. As is known, the seal is generally intended to make a seal on an upper edge of the mouth of the container. 
     The object (seal) is in particular made by compression-moulding plastics. The object can have an annular, open or closed, shape. In this specific case, the object (seal) has a closed circular shape. The object can be made of any plastics, for example a thermoplastic and/or elastomeric material, for example of the type used for forming seals for closures of containers. 
     The object is in particular formed by a forming process that comprises a step of depositing two or more (in the cases illustrated here five, six, or seven) doses of plastics on a resting surface and thus a step of compression-moulding the aforesaid doses inside a forming chamber (of annular shape) in which the material of the various doses is joined so as to form the object (of annular shape). 
     Compression-moulding is optionally achieved by a compression punch with at least a partially annular (open or closed) shape. The moulding chamber in which the doses are compressed is optionally at least partially annular (open or closed). The doses can be wholly or partially deposited on a resting surface that in the moulding step bounds at least a part of the compression-moulding chamber (of open or closed annular shape). The doses are deposited optionally on a peripheral zone of the resting surface that surrounds a central region of the resting surface that, during compression-moulding, is occupied by a punch part that obstructs the flow of the plastics. The doses are optionally placed angularly spaced around the central region of the resting surface. 
     The doses, which in the example illustrated here have a section that has a substantially circular shape, can also have other shapes (for example an oblong shape or a circular-sector shape or a curved shape). It is possible to deposit (for subsequent compression-moulding) doses that are different in shape from one another. 
     The n doses (“n” being a whole number &gt;1) made of plastics to be deposited (and then formed in a compression-moulding chamber) can be separated in a substantially simultaneous manner from n extruding outlets each arranged for dispensing (in a continuous manner) a flow of extruded plastics. The doses can be separated by using a movable separating device provided with n separating elements, each of which separates (by cutting or shearing) a single dose from a respective extruding outlet. The separating device is optionally movable between the separating zone (cutting or shearing) of the doses, where the various extruding outlets are located, and the dose-depositing zone for depositing the doses on the resting surface, on which surface the object will then be formed through compression-moulding of plastics. 
     The separating device can be configured such that the various separating elements (each separating a single dose) are mutually positioned in a similar manner to the arrangement that the doses will have to have in the moulding chamber (of open annular or closed shape). In substance, the separating device could be configured so that the “n” separating elements are arranged with a peripheral distribution around a central region. Such a peripheral distribution could be a circumferential distribution. 
     The separating elements can operate by passing in front of the corresponding extruding outlets so as to cut or shear a dose of plastics and so as to retain the dose of plastics as far as the depositing place. It is possible to provide, in the place of depositing of the dose on the resting surface, detaching arrangement for detaching the dose retained by the separating element that has previously separated (via cutting or shearing element) the dose. It is possible to provide that such detaching arrangement comprises, for example, at least one pushing element, for example of the piston and/or compressed-air type, that pushes the dose (generally downwards). 
     With reference now to  FIGS. 20 to 24 , an extruder made of plastics with multiple outlets has been indicated overall by  501 , the extruding outlets (five in this specific case) have been indicated by  502 , the dispensing flow control devices have been indicated by  503  (for example needle valves, one for each extruding outlet), a supply collector for supplying the plastics at the extruding outlets has been indicated by  504 . In this specific case, the extruding outlets  502  are each configured so as to dispense a continuous extruding flow directed upwards. 
     A device for separating doses of plastics from the flow dispensed by the extruding outlets has been indicated overall by  505 , a single separating element or tool has been indicated by  506  that cuts or shears a dose passing in front of a respective extruding outlet,  507  indicating a single pushing element (of the piston type) that detaches the dose from the respective separating tool,  508  indicating a rotating carousel that rotates, distributed on the periphery thereof, a plurality of separating devices  505 ,  509  indicating the circular trajectories of the separating elements or tools  506  rotated by the carousel. 
     Each separating tool  506  optionally has a concave surface with the concavity facing forwards to an advancing direction of the tools; the advancing direction can be, as in this specific case, a circular trajectory defined by the movement of a rotating carousel for conveying the tools. 
     With reference to  FIG. 25 , another embodiment is illustrated (maintaining for the sake of simplicity the same numbering as for the elements that are similar to those disclosed previously), in which, further to the rotational movement of the carousel  508 , there is provided a further movement of each single separating device  505  with respect to the carousel  508 . This movement can further be, as in the specific case illustrated here, a rotation movement, optionally around a rotation axis that passes through the centre of the circumference on which the separating elements  506  are arranged and which is normal to such a circumference. Such a further relative movement of the separating elements with respect to the carousel can be performed with the object of promoting cutting or shearing of the multiple doses. It is possible to provide also a part of the extruder  501  with the possibility of rotating on itself (for example in a direction opposite the rotation of the separating device  505 ) in particular a part that has the extruding outlets  502 . Such a rotating part could comprise a block that defines the plastics dispensing nozzles terminating with the extruding outlets  502 . The rotation axis would pass through the centre of the circumference on which the extruding outlets  502  are arranged. The rotating block will in this case have a central passage that, on one side, will be connected to the supply of melted plastics, and, on the other side, will be connected to the various extruding outlets  502 . The possibility of moving the extruding outlets can be used to promote the separation (shearing) of the multiple doses. 
     With reference to  FIGS. 26 and 27  there are illustrated (maintaining the same numbering as for the similar elements), two examples of an extruder having, respectively, six or seven extruding outlets  502 . The separating device will have, in these cases, a corresponding number and a similar distribution of the separating tools. 
     With reference to  FIG. 37  there is illustrated (maintaining the same numbering as for the similar elements) an example of an extruder having extruding outlets  502  with different shapes. In this specific case, some extruding outlets  502  have an oblong shape whilst other extruding outlets  502  have a circular shape. The separating device will in this case have a corresponding shape and distribution of the separating tools. 
     The doses separated by the separating device  505  will be deposited, by the pushing elements  507 , inside the capsule illustrated in  FIGS. 28 and 29  to make the seal inside the capsule. 
     The capsule comprises, in this specific case, a closing wall  510  intended for closing the upper mouth of a container and a tubular-shaped side wall  511 . The seal has to be formed on a peripheral zone of the internal surface of the closing wall  510 ; this peripheral zone is also a zone arranged next to the side wall  511 . 
     With reference now to  FIGS. 30 to 36 , the doses of plastics are indicated by  512  that have been deposited by the separating device on the internal surface of the wall  510  of the capsule,  513  being a support that bears the capsule,  514  being overall a compression-moulding device,  515  being a compression punch that forms the seal by compressing the doses  512  on the caps. 
     It is possible to use a moulding apparatus of the rotating carousel type provided on the periphery thereof with a plurality of moulding devices  514 , each of which comprises a support  512  and a punch  515 . The multiple doses  512  can be deposited in a release zone coinciding, for example, with a meeting zone between the carousel  508  that carries the separating devices  505  and the moulding carousel that carries the compression-moulding devices. 
     It is further possible to provide a device of known and non-illustrated type, to supply the capsules to the various moulding devices of the moulding carousel and a device, which is also known, for removing the capsules with the formed seal from the carousel. 
     The compression punch  515  comprises an internal member  516 , an external member  517  of annular shape and an intermediate member  518  which is also of annular shape (coaxial with the external member  517 ) and arranged between the external member  517  and the internal member  516 . The three members  516 ,  517  and  518  of the compression punch  515  and the closing wall  510  are configured for assuming an operating configuration in which they define a moulding chamber  519  (of annular shape) in which the doses  512  are compression-moulded. The intermediate member  518  (that defines above the moulding chamber  519 ) is movable with respect to the other two members  516  and  517  so as to be able to exert the compression action. 
     It is possible to provide a thermal conditioning arrangement (not illustrated) for thermal conditioning (in particular for cooling) of the compression punch. In particular, the member that compresses (represented in the specific case illustrated here by the intermediate member  518 ) could bear internally at least a part of a thermal-conditioning circuit (cooling circuit) connected to a system for supplying a thermal conditioning fluid. 
     In  FIG. 34  there is shown the moulding configuration in which the intermediate member  518  has been lowered to compress the plastics and thus form the seal  520  (with a closed annular shape). The internal member  516  obstructs the flow of compressed melted material to the inside, whilst the external member  517  obstructs the flow to the outside. In  FIG. 36  there is illustrated the capsule with the seal  520 , which in this specific case is of a closed annular shape. 
     As already said, it is possible to use a different number of doses, for example in function of the volume of plastics to be used and/or the shape of the object to be formed. 
     In use, the object (seal) forming process optionally comprises the steps of forming, transferring, depositing and moulding the doses, which can occur, as in the case illustrated here, in a continuous manner. A control unit that is known and not illustrated is configured for controlling various steps of the process. The doses are formed optionally by (substantially simultaneous) separating of the n doses from the n extruding outlets. The doses are separated optionally by cutting or shearing by the n separating elements or tools that pass in front of the n extruding outlets. It should be observed that the n extruding outlets are optionally arranged with the same distribution that the doses will have in the moulding chamber before compressing (in which the doses will be joined or welded together to form the object). 
     The doses are optionally moved by moving the separating tools that retain the corresponding doses (as known, by exploiting the adhesive capacity of the plastics in melted state). The doses are deposited, simultaneously for all the n doses, by means of activation of the detaching arrangement that pushes the n doses  512  onto the resting surface (the wall  510  of the capsule). The doses are deposited synchronised with the movement of the support  513  of the resting surface. In this specific case, both the separating device that carries the doses and the support surface that receives the doses from the separating device, are rotated by two respective conveying carousels that are synchronised together. 
     As said, the doses  512  are deposited on the resting surface (wall  510 ) with a peripheral distribution around a central zone. This central zone will then be occupied by the internal member  516  of the compression punch, which will obstruct the flow of plastics to prevent the material entering this central zone. The intermediate member  518  (of annular shape) will be moved to compress the doses  512  at the position of depositing the doses, i.e. in the peripheral zone around the central zone. This peripheral zone will be the zone where the (annular) moulding chamber  519  will be defined in which the seal will be formed.