Abstract:
A device for producing a scoring line in the cylindrical wall of a plastic cup, comprising: a mandrel, provided with elements for positioning and retaining a cup applied thereon; a plurality of jaws, an end whereof is articulated to the mandrel so as to oscillate on radial planes; respective circular arc-shaped blades being applied to the opposite end of the jaws and being arranged on a plane which is perpendicular to the axis of the mandrel; actuation elements for the jaws being further provided, as well as elements for actuating the mandrel with respect to the actuation means so as to actuate the arc-shaped blades radially from a position which is external to the cup to a position for engaging the wall of the cup at which the blades form a scoring line in the wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of application number PCT/EP98/06234 of Oct. 1, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a device for producing a scoring line in the cylindrical wall of a plastic cup and to a machine which uses said device. The invention is used in particular in so-called tamper-evident screw caps composed of a cup and of a tamper-evident ring which protrudes from the rim of the cup and in which the scoring line between the wall of the cup and the tamper-evident ring allows to separate the cup from the tamper-evident ring when the cap is unscrewed from the container to which it has been applied.  
           [0003]    Machines using devices for producing a scoring line between the cup and the tamper-evident ring in screw caps for closing containers are already known. These devices essentially consist of a circular cutter against which the cap is made to roll so as to produce a scoring line which causes the tamper-evident ring to break away from the cup when the cap is unscrewed from the container. In order to achieve rolling of the cap, the cap is placed over a mandrel which follows a path which is concentrically external to the circular cutter and presses the wall of the cap against the sharp edge of the cutter. Such devices are disclosed for example in EP-533 633 and in U.S. Pat. Nos. 3,824,941, 3,861,551, 4,343,754 and 4,904,435.  
           [0004]    A device with the features of the preamble of claim  1  is known from the document DE-A-1 482 603.  
           [0005]    Conventional devices entail some substantial drawbacks which can be substantially ascribed to the fact that they are highly sensitive to variations in the external and internal shape of the cup. Moreover, it often happens that the cut is not performed perfectly due to the fact that the cap can slip on the mandrel and thus may not complete its rotation over the cutter.  
         SUMMARY OF THE INVENTION  
         [0006]    The aim of the present invention is to provide a device which allows to obviate the above-mentioned drawbacks of conventional devices.  
           [0007]    This aim is achieved with a device for producing a scoring line in the cylindrical wall of a plastic cup, in accordance with the present invention, which has the features set forth in claim  1 . 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    Further characteristics and advantages of the present invention will become apparent from the following detailed description on the basis of the accompanying drawings, wherein:  
         [0009]    [0009]FIG. 1 is a sectional view of a device according to the invention about to produce a scoring line on a screw cap for closing containers;  
         [0010]    [0010]FIG. 2 is a sectional view, taken along the plane II-II of FIG. 1;  
         [0011]    [0011]FIG. 3 is a view of the device of the invention in the scoring position;  
         [0012]    [0012]FIG. 4 is a sectional view of a second embodiment of the device;  
         [0013]    [0013]FIG. 5 is a sectional view, taken along a vertical plane, of a machine composed of a plurality of devices arranged in a carousel configuration;  
         [0014]    [0014]FIG. 6 is a sectional view, taken along a vertical plane, of another carousel-type machine;  
         [0015]    [0015]FIG. 7 is a view of a further embodiment of the device applied to a machine of the type shown in FIG. 5;  
         [0016]    [0016]FIG. 8 is a view of another embodiment of the device applied to a machine of the type shown in FIG. 5;  
         [0017]    [0017]FIG. 9 is a sectional view, taken along the plane IX-IX of FIG. 8. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    With reference to FIGS. 1, 2 and  3 , the device according to the present invention is generally designated by the reference numeral  1  and is constituted by a cylindrical body  2 , termed receptacle hereinafter for the sake of convenience in description, which comprises a bottom  3  and a cylindrical wall  4 .  
         [0019]    The receptacle  2  is centered and fixed by means of screws  5  to a supporting structure  6  so that its axis A is vertical.  
         [0020]    The internal cavity of the receptacle  2  constitutes a seat  7  for the sliding of a cylindrical mandrel  8 . At the end of the mandrel  8  that protrudes downward there is provided a shank  9  for the centering of a plastic cap  10  composed of a cup  11  and of a tamper-evident ring  12  which protrudes from the rim of the cup  11 . The cup  11  is internally threaded in order to be screwed onto the mouth of a container, and the tamper-evident ring  12  has internal protrusions which, once the cap has been screwed on, engage under an external collar formed below the mouth of the container.  
         [0021]    The device  1  allows to form a scoring line between the cup  11  and the tamper-evident ring  12  in order to allow separation of the cup  11  from the tamper-evident ring  12 , which is retained by the collar of the container when the cap is unscrewed.  
         [0022]    A recess  12   a  for accommodating a screw  13  is formed in the bottom  3 . The screw  13  is screwed into the mandrel  8  through a hole  14  which formed in the bottom of the recess  12   a  and has a smaller diameter than the head of the screw  13 . The head of the screw  13  locks against the mandrel  8  a bush  15  which is guided in the hole  14 . In this manner, the mandrel can perform axial strokes, with respect to the receptacle  2 , which are limited by the abutment, against the bottom of the recess  12   a , of the head of the screw  13 , which thus acts as a stroke limiter.  
         [0023]    An axial blind hole  16  is formed in the mandrel  8  and is open toward the bottom  3 . The hole  16  accommodates a spring  17  which rests against the bottom  3  through the interposition of a spacing bush  18 .  
         [0024]    A threaded rod  19  is screwed into the bottom  3 , inside the receptacle  2 , protrudes axially through the bush  18  and the spring  17  and is rotationally locked by means of a nut  20 . The rod  19  is suitable to abut against the bottom of the blind hole  16  so as to determine the position of the mandrel inside the seat  7 .  
         [0025]    Three hollows  21  are formed on the outside of the mandrel and are angularly spaced by 120°. An arm  23  is articulated in each hollow by means of a pivot  22  and a jaw  24  is rigidly coupled thereto. The jaw  24  is constituted by a sector which is substantially conical and has an inclined outer surface which converges toward the bottom of the seat  7 .  
         [0026]    By means of springs  25  interposed between the jaws  24  and the mandrel  8 , the sectors are kept in contact against the internal rim  26  of the wall  4  of the receptacle  2 . Conveniently, the internal rim  26  has a chamfer which is complementary to the chamfer of the outer surface of the jaws  24  and is cambered so as to form, together with the jaws, a circumferential contact line.  
         [0027]    Each jaw  24  has, in a downward region, an arc-shaped seat  28  in which a block  29  is provided for retaining a blade  30  which is arranged substantially on a plane which is perpendicular to the axis A of the mandrel  8 . Two screws  31  pass through the block  29  and the blade  30  and clamp the blade in the seat  28 .  
         [0028]    Each blade  30 , see FIG. 2, has a cutting edge  32  which is shaped like a circular arc whose radius is substantially equal to the radius of the cap  10  and has a plurality of notches  33  having a preset mutual distance. As explained more clearly hereinafter, the blades  30  are meant to cut through the cylindrical wall of the cap so as to separate the tamper-evident ring  12  from the cup  11  except for bridges which join the tamper-evident ring  12  to the cup  11  and are formed by not cutting at the notches  33 .  
         [0029]    A radial seat  34  is formed in the blocks  29  for locking the blades  30  in a median region, and a cutter  35  is inserted therein. The sharp edge of the cutter lies on a radial plane which passes through the axis A of the mandrel  8  and is aligned with the sharp edge  32  of the respective arc-shaped blade  30 .  
         [0030]    The cutter  35  is retained in the seat  34  by a screw  36  which is driven from outside through the jaw  24 . The cutters  35  are arranged at such a level that when the arc-shaped blades  30  cut the wall of the cap, the cutters  35  cut transversely through the tamper-evident ring.  
         [0031]    The described device operates as follows.  
         [0032]    In the initial conditions, the mandrel  8  is in a lowered position with respect to the receptacle  2  and the jaws  24  are kept spaced against the internal rim  26  of the receptacle  2  by the springs  25 .  
         [0033]    The cap  10  to be cut, after being arranged on a lifting device  37 , is lifted by the lifting device and centered on the shank  9 . As the lifting device  37  continues its upward stroke, the thrust applied against the shank  9  causes the lifting of the mandrel  8  in contrast with the elastic reaction applied by the spring  17 .  
         [0034]    Through the lifting of the mandrel  8 , the jaws  24  abut against the rim  26  and are thus forced to move mutually closer toward the mandrel  8  and cause the engagement of the blades  30  against the wall of the cap  10 , thus causing the peripheral cutting of said cap at the level where the tamper-evident ring  12  separates from the cup  11 .  
         [0035]    The penetration of the blades  30  in the wall of the cap  10  is determined by the abutment of the rod  19  against the bottom of the blind hole  16  and is adjusted by screwing or unscrewing the rod  19  so that the tamper-evident ring  12  remains attached to the cup only at the bridges formed by the notches  33  while, by virtue of the cutters  35 , the tamper-evident ring is scored transversely to facilitate its fracture when the cap is removed after being applied to a container.  
         [0036]    The described invention is susceptible of numerous modifications and variations.  
         [0037]    The number of the blades  30  and of the cutters  35  is chosen according to requirements. For example, it is possible to provide four blades  30  associated with respective jaws, each blade covering an angle of 90°. Moreover, the cutters  35  can also be omitted from the device, for example if the tamper-evident ring, after fracture, must remain attached to the container.  
         [0038]    [0038]FIG. 4 is a view of an embodiment of the invention in which the device has been modified to form plastic disks starting from a cup  38  which has a bottom  39  and a cylindrical peripheral wall  40 . The difference with respect to the embodiment of the preceding figures is substantially the fact that in the shank  9  of the mandrel  8  there is provided an annular cutter  41   a  which internally scores the cup along the peripheral region of the bottom  39 , so as to separate a disk which can be used as a liner for caps or for other purposes.  
         [0039]    [0039]FIG. 5 is a view of an embodiment which comprises a plurality of devices  1  for providing a carousel-like machine.  
         [0040]    The machine comprises a vertical shaft  41  which is connected to motor drive means and is rotatably supported in a sleeve  42  which rises from a footing  43 . At the top of the shaft  41  there is provided a disk  44  which supports a plurality of devices  1  which are angularly mutually equidistant and are arranged concentrically around the shaft  41 .  
         [0041]    The disk  44 , by means of a sleeve  45 , is rotationally rigidly coupled to a flange  46  which is keyed on the shaft  41  above the sleeve  42 . A tray  47  is fixed to the sleeve  42  above the flange  46  and is meant to receive the caps arriving from a feeder channel  48 . A star element  47   a  is arranged above the tray  47  and is rigidly coupled thereto. The star element  47   a  is peripherally provided with seats  49  which are aligned with the respective devices  1  and into which the caps arriving from the channel  48  are transferred. The seats  49  are aligned with openings  49   a  of the tray  47  and with respective holes  50  which are formed in the flange  46  and are parallel to the shaft  41 . Respective bars  51  are guided in the holes  50  and constitute the lifting devices for the caps  10 . The bars  51  have, at their lower end, two free rollers  52  and  53  which are diametrically opposite and whose rotation axis is radial with respect to the shaft  41 . The outer roller  52  of the two rollers  52 ,  53  engages a vertical guide  54  which is fixed to the peripheral region of the flange  46 , protrudes downward and prevents the respective bar from rotating in the seat  50  yet allows it to slide axially.  
         [0042]    The internal roller  53  instead engages a slot  55  of an axial cam  56  which is rigidly coupled to the footing and runs around the sleeve  42 .  
         [0043]    With the described machine, the caps  10 , fed in succession from the channel  48  and transferred into the seats  49  of the star element  47   a , which rotates in step with the machine, are transferred onto the receiving tray  47  and positioned in the openings  49  that lie above the tops of the bars  51 , which are at their lower stroke limit in this step.  
         [0044]    As the machine revolves, each lifting device  51 , actuated by the cam  56 , lifts the respective cap until it abuts against the shank  9 . Then, as the lifting of the lifting device continues, the blades  30  close onto the cap  10  and the peripheral scoring is formed as described above with reference to FIG. 1.  
         [0045]    When scoring is complete, the lifting device  51  is lowered, allowing the mandrel  8  to follow its movement by means of the spring  17 . Simultaneously with the descent of the mandrel  8 , the spring  25  disengages the blades  30  from the cap, which once it has been released onto the tray  47  can be removed laterally from the seats by means of conveyor elements.  
         [0046]    [0046]FIG. 6 also shows an application of the device for forming a carousel machine which differs from the preceding one in that instead of lifting the cap  10  the devices  1  are lowered.  
         [0047]    The machine of FIG. 6 comprises a vertical shaft  57  which is connected to motorization means and is rotatably supported in a footing which is not shown.  
         [0048]    A sleeve  58  is keyed onto the shaft  57  and is provided with a flange  59  in which a plurality of bushes  60  is provided which are angularly equidistant around the shaft  57 . The receptacles  2  of respective devices  1  can slide in the bushes  60 . The tray  61  for receiving the caps is fixed to the lower end of the sleeve  58  together with the corresponding star  61   a,  which is provided with seats  61  into which the caps  10  are transferred by a feeder channel which is similar to the one designated by the reference numeral  48  in the embodiment of the machine shown in FIG. 5.  
         [0049]    A sort of drum  62  is fixed to the upper end of the sleeve  58  and is provided with axial guides  63  which are aligned with the bushes  60 . Respective sliding blocks  64  can slide in the guides  63  and are connected to the receptacles  2  of the respective devices  1  by means of rods  65 . Conveniently, flexible couplings  66  are provided between the rods  65  and the sliding blocks  64  to allow small mutual movements.  
         [0050]    Respective free rollers  67  protrude inward from the sliding blocks  64  and engage the slot  68  of an axial cam  69  which is centered and fixed on the collar  70  of a sleeve  71  in which the upper portion of the shaft  57  is rotatably supported. The sleeve  71  and therefore the cam  69  are caused to be stationary with respect to the shaft  57  by means of a bracket-like connection  72  to the frame of the machine.  
         [0051]    It is evident from FIG. 6 that as the shaft  57  revolves, the cam  69  actuates the sequential descent of the devices  1 , so that the shanks of the mandrels  8  engage the respective caps  10  to be scored.  
         [0052]    When the shank  9  of one device has made contact against the bottom of the respective cap, the cam  69  actuates the further descent of the device which causes the movement of the mandrel  8  with respect to the receptacle  2 , consequently closing the jaws  24  and perimetrically scoring the cap.  
         [0053]    As the machine continues its rotation, the cam  69  actuates the lifting of the device  10 , so that the spring  17  can push out the mandrel  8  again, allowing the jaws  24  to open and allowing the blades to disengage from the cap, which can thus be left on the tray  61  for removal.  
         [0054]    [0054]FIG. 7 illustrates a further embodiment of a machine of the type shown in FIG. 5 but provided with devices  1  such as the one of FIG. 4 for forming plastic disks. The machine of FIG. 7 can of course be used also to score caps for closing containers.  
         [0055]    With respect to the preceding devices, the differences of the embodiment of FIG. 7 aim to reduce friction and consist of the fact that the mandrel  8  is guided in the receptacle  2  by means of a sleeve-shaped ball bearing  73  and in that in order to actuate the jaws  24  bearings  74  are provided which are supported in extensions  75  of the wall  4  and in contact with the conical outer surface of the jaws  24 .  
         [0056]    Advantageously, instead of the threaded rod  19  there is provided an adaptable shim  76  which allows to adjust the level at which the blades  30  act. Finally, the reference numeral  77  designates a duct which leads onto the supporting surface of the cup  38  and is connected to a source of suction in order to retain the disks on the top of the bars  51 .  
         [0057]    Another embodiment of the machine of FIG. 5 is shown in FIGS. 8 and 9 and allows, for each device, to determine the angular position of the cap  10  with respect to a cutter  35  (see FIG. 9).  
         [0058]    This requirement arises in the case of caps  10  in which the tamper-evident ring  12  is provided with internal flaps  78  which are separated by gaps  79  and must remain attached to the cup  11  after fracture along the scoring lines, formed by the blades  30  and by the cutters  35 , when the cap  10  is unscrewed from the container. This is done to avoid having to remove, with a subsequent operation, the tamper-evident ring which has remained attached to the neck of the container or for materials recycling reasons, since the material of the cap is different from the material of the container.  
         [0059]    In the embodiment of FIGS. 8 and 9, the shank  9  has a peripheral groove  80  in which circular sectors  81  engage; said sectors are centered in a seat  82  of a disk  83  which is fixed to the lower end of the mandrel  8  by means of screws  84 .  
         [0060]    The sectors  81  are crossed by fixing screws  84   a  which are screwed into the disk  83 .  
         [0061]    The shank  9  has an external set of teeth  85  whose angular distance is equal to the distance of the gaps  79  between the flaps  78  of the cap  10 . Moreover, in the shank  9  there is provided a blind hole  86  having a threaded portion in which a ring  87  is screwed. The ring  87  has a flange  88  whereby it is locked against a shoulder of the hole  86  and an axial seat  89  in which a pivot  90  provided with a collar  91  is guided. A spring  92  acts on the pivot  90  and, by abutting against the bottom of the hole  86 , keeps the collar  91  in contact against an internal abutment of the bush  87 .  
         [0062]    When the collar  91  rests on the internal abutment of the ring  87 , the end of the pivot  90  protrudes axially out of the shank  9 .  
         [0063]    The angular arrangement of the teeth  85  and their shape is such as to allow them to enter the gaps  79  when the cap is fitted over the shank  9 .  
         [0064]    In order to ensure that the tamper-evident ring  12  remains attached to the cup  11  also after the cap has been removed from the container, some portions  93 ,  94  of two adjacent blades  30  are removed so that the wall of the cap that lies in front of them remains intact. The tamper-evident ring  12  is opened by forming a single transverse scoring line with a single cutter  35  arranged at one end of the portion  93 . In this manner, when the cap is unscrewed from the container, the tamper-evident ring can break starting from the position of the cutter  35 .  
         [0065]    In order to position each cap  10  on the respective shank  9  in the intended angular position with respect to the cutter  35 , at the top of the corresponding bar  51  there is provided a coaxial pivot  95  which supports, by means of bearings  96 , a bush  97  provided with an external set of teeth  98 . At the top of the bush  97  a seat  99  is provided for accommodating a tray  100  which constitutes a supporting base for a cap  10 .  
         [0066]    Through the actuation of the bar  51  by the cam  56 , the bush  97  is raised from a lowered position for receiving a cap on the tray  100  to a position for engaging the shank  9 .  
         [0067]    In order to allow the teeth  85  of the shank  9  to enter the gaps  79  between the flaps  78 , the set of teeth  98 , during the upward stroke of the bush  97 , is made to mesh with an actuation element which is capable of making the bush  97  rotate. The actuation element is constituted, for example, by a ring  101  with internal teeth which is fixed to the outside of the devices  1 . The profiles of the teeth  98  are shaped so as to avoid violent impacts when meshing with the teeth  85  occurs. In a further embodiment, the actuation element is constituted by a gear which is rotatably supported on the central shaft  41  and meshes constantly with the set of teeth  85  of the bush  97 . The wheel is controlled by an actuation cam whose profile is such as to make the bush  97  rotate gradually.  
         [0068]    By means of the machine of FIGS. 8 and 9, in a first step of the lifting action a relative rotation occurs between the cap  10  and the bush  97  until the teeth  85  engage the gaps  79 , while in a second step of the lifting action, as a consequence of the relative movement between the jaws  24  and the receptacle  2 , the tamper-evident ring is scored peripherally and transversely.  
         [0069]    By means of the descent stroke, the pivot  90 , by means of the thrust applied by the spring  92 , causes the separation of the cap from the shank  9  and its deposition on the tray  100 .