Abstract:
A cutting machine for forming fracture lines in the cylindrical wall of plastic caps to facilitate the separation of a tamper-evident ring, including at least one cap support which rotates about an axis thereof and a laser beam emitter arranged, with respect to the support, so as to provide a laser beam that strikes the cylindrical wall of the cap, the emitter being activated and deactivated in accordance with the rotary motion of the cap, so as to form in the cylindrical wall of the cap a plurality of cuts alternated with short intact portions, which form a fracture line allowing the separation of the tamper-evident ring from the cup.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a machine for cutting the cylindrical wall of tamper-evident plastic caps in order to form a fracture line which is suitable to facilitate the separation of a tamper-evident ring during the removal of the cap from the container to which it has been applied. 
     Plastic caps are known which are provided with a tamper-evident ring, i.e., with a ring which is fixed below the cup of the cap by means of bridges which break during the initial unscrewing of the cap and allow to determine whether the cap has been tampered with or not. 
     In some types of cap, the tamper-evident ring and the corresponding bridges for coupling to the cup are obtained by molding together with the cap itself. 
     In other types, the ring is molded monolithically with the cup and is rendered separate from said cup at a later stage by means of peripheral cuts, so that the tamper-evident ring remains attached to the cap only with very short intact portions which constitute said bridges. 
     In some conventional machines, the cuts in the cylindrical wall of the cup are performed by means of a cutter with a circular cutting edge, against which the caps are rolled. A plurality of appropriately spaced notches are formed in the cutting edge and form the bridges. 
     These conventional machines suffer the drawback that replacing the cutter, for example due to wear or breakage or due to requirements imposed by the structure of the cap, is a highly complex and time-consuming operation. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to obviate the above-cited drawbacks of conventional machines, by providing a machine for cutting tamper-evident rings which does not wear and can be easily adapted to different cutting methods and to different cap shapes. 
     Within the scope of this aim, an object of the present invention is to achieve the above aim by providing a machine which is simple, relatively easy to manufacture, safe in use, effective in operation, and relatively modest in cost. 
     This aim and this object are both achieved by the present machine for cutting the cylindrical wall of the cup of plastic caps in order to form a fracture line which is suitable to facilitate the separation of a tamper-evident ring, characterized in that it comprises at least one cap support which rotates about an axis, and a laser beam emitter arranged, with respect to said support, so that said beam strikes said cylindrical wall of the cap, said emitter being activated and deactivated in accordance with the rotary motion of the cap, so as to form in the cylindrical wall of the cap a plurality of cuts alternated with short intact portions, which form a fracture line allowing the separation of said tamper-evident ring from said cup. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages of the machine according to the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment, illustrated only by way of non-limitative example in the accompanying drawings, wherein: 
     FIG. 1 is a sectional view of a cutting machine, taken along a vertical plane; 
     FIG. 2 is an enlarged-scale view of the upper part of the machine of FIG. 1; 
     FIG. 3 is a sectional plan view of FIG. 1, taken along the plane III—III; 
     FIGS. 4 and 5 are enlarged-scale views of two details of the cutting device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With particular reference to the above figures, the machine is substantially constituted by a carousel  1  which can revolve on a footing  2  which is provided with a horizontal worktable  3  in which a centering opening for a sleeve  4  having a vertical axis A is formed centrally. 
     A shaft  6  is supported in the sleeve  4  so that it can rotate by means of bearings  5  and rises from the worktable  3 ; below said worktable, said shaft is connected to the output of a gearmotor  7  which is accommodated within the footing  2  and is fixed under the worktable  3 . The gearmotor  7  is suitable to impart an intermittent rotation to the shaft  6 . 
     A drum  8  is fixed on the worktable  3 , concentrically to the sleeve  4  and between said worktable and a flange of the sleeve, and is externally provided with a slot which forms an axial cam  9 . 
     A rotating cap conveyor is fitted on the shaft  6 , above the sleeve  4 , and comprises a flange  10  which is keyed onto the shaft  6  and in which cylindrical seats  11  are provided on a diameter which is greater than the outside diameter of the drum  8 . 
     The cylindrical seats  11  are mutually angularly equidistant, and respective spindles  12  are guided axially therein; said spindles are crossed, in a downward region, by pins  13  which are radial with respect to the axis A. 
     Respective bearings  14 ,  15  are supported at the opposite ends of the pivots  13 . The bearings  14  are internal with respect to the spindles  12  and engage in the cam  9 , so that by turning the shaft  6  they force the spindles  12  to perform movements which are determined by the shape of the cam  9 . The bearings  15  instead engage in vertical slots formed in strips  16  which protrude downward from the peripheral region of the flange  10  with which they are rigidly coupled. In this manner, the spindles are prevented from rotating during axial movements. 
     The tops of the spindles  12  have cylindrical cavities in which bearings  17  rotatably support respective stems  18 . The stems  18  protrude upward above the flange  10 , and a circular plate  19  is rigidly coupled to their upper end. 
     The plates  19  are aligned with respective circular seats  20  which are formed in a disk  21  which is fixed on a radial expansion of a collar  22  which is fitted on the shaft  6  and is rigidly rotationally coupled to the flange by means of pins  22   a.    
     Moreover the collar  22  has a shoulder on which a second disk  23  is fixed; said second disk lies flat and parallel with respect to the disk  21 . The disk  23  is provided with peripheral recesses  24  which are open toward the outside and are shaped like circular arcs, so that the disk  23  assumes the appearance of a star. 
     The recesses  24  have a diameter which is complementary to the diameter of the caps C to be cut and are aligned with respective plates  19 , so as to provide seats in which the caps C rest on plates  19  and are retained peripherally by the edge of the recesses  24 . 
     As shown more clearly by FIG. 4, the caps C comprise a cup which has a cylindrical wall P which is internally threaded and protrudes axially, forming the tamper-evident ring G. 
     The caps C are conveyed into the recesses  24  by means of a feeder channel  25  which is composed of a bottom  26  which is co-planar to the disk  21  and of two side walls  27 ,  28 ; the side wall  28  runs circumferentially around the star  23  with a portion  29 , so as to close the recesses  24  along a certain extent in the direction of rotation F of the shaft  6 , at least until the caps C have been locked against the plates  19  by means which are generally designated by the reference numeral  30 . 
     Said means comprise (see FIG. 2) a flange  31  which is fitted on the shaft  6  and is provided with a collar  32  which is rotationally rigidly coupled to the collar  22  by means of axial coupling pins  32   a  and is locked axially by a ring  33 . 
     The flange  31  has a plurality of axial holes which are vertically aligned with the plates  19  and accommodate bushes  34  which internally rotatably support, by means of bearings  35 , hollow shafts  36  whose opposite ends protrude upward and downward out of the bushes  34 . 
     A gear  37  is rigidly coupled to the upper end of the shafts  36 , while the lower end is shaped so as to allow, by means of a ring  38 , the locking of a tang  39  which is coaxial to the shaft  36 . 
     The tang  39 , see FIG. 4 in particular, comprises a substantially cylindrical head  40  which can be inserted with minimal play in the cap C. 
     A hollow  41  is formed frontally in the head  40  and accommodates a complementarily shaped plate  42 . 
     The plate  42  is fixed to a stem  43  which runs axially through the tang  39  and the shaft  36  and is coupled, in an upward region, to actuation elements generally designated by the reference numeral  44 . During the operation of the machine, said elements, by activating the stems  43 , cause the plates  42  to protrude from the recesses  41 , so as to secure the bottom of the caps C onto the plates  19  and lift the caps to a chosen level in order to produce a fracture cut between the tamper-evident ring G and the wall P of the cap by means of a laser-beam device  44   a  which is installed on the worktable  3  with the aid of a bracket  45 . Conveniently, in order to provide greater assurance in cutting, the head  40  of the tang  39  has an annular slot  47  at the level of the emitter  46  of the laser beam. 
     The elements  44  for actuating the stems  43  comprise a cylinder  48  which is supported coaxially to the shaft  6  by posts  49  by means of which it is fixed to the flange  31 . 
     Seats  50  are formed in the cylinder  48  and are coaxial to the hollow shafts  36 ; sliders  51  are guided therein and are connected to the stems  43  by elastic couplings, shown more clearly in FIG.  5 . Each coupling is provided with a notch  52  which has a T-shaped cross-section, is formed diametrically at the lower end of the respective slider, and is engaged by the head  53  of a mushroom-shaped portion formed at the top of the stem  43 . The stem  53  is not as high as the notch  52  is deep, so that the stem  43  can perform axial movements with respect to the slider  51 . 
     The head  53  is actuated into abutment against the undercuts of the notch  52  by a spring  54  which is arranged on the stem  43  and acts between the slider  51  and a shoulder  55  of said stem. 
     A roller  56  is fixed in the sliders  51  so as to cantilever out toward the shaft  6  and engages a cam  57  formed in the outer wall of a stationary drum  58  which is internally concentric to the cylinder  48 . The cam  57  actuates the axial movements of the sliders  51  and, in order to prevent the rotation thereof in the respective seat  50 , on the supporting pivot of each roller  56  there is a ring  59  which slides in a slot  60  formed in the internal wall of the seat  48 . 
     The drum  58  is centered and fixed on a flange  61  of a sleeve  62  in which bearings  63  rotatably support the top of the shaft  6 . The flange  61  is fixed below a bracket  64  which rises above the drum  58 . 
     The bracket  64  is fixed to the top of an upright  65  which rises from the worktable  3  of the footing. A vertical plate  66  is rigidly coupled to the bracket  64  in a diametrically opposite position with respect to the upright  65 , and a motor  67  having a vertical axis is coupled to said plate by means of a flange. The shaft of the motor  67  protrudes downward, and a pinion  68  is keyed thereon; said pinion lies at the level of the gears  37  and at a radial distance from the shaft  6  which allows it to make tangential contact and mesh with the gears  37 . 
     The operation of the above-described apparatus is as follows. The caps C, by means of driving means which are not shown (for example with the aid of an air jet or by gravity), are conveyed along the channel  25 , where they form a stack of caps. In the stopped position of the carousel  1 , the front cap, designated by C 1  in FIG. 3, engages in a recess  24  of the star  23  and rests on the plate  19 . 
     As soon as the intermittent rotation of the carousel  1  in the direction F is activated, and before the cap C 1  leaves the portion  29  of the side wall  28 , the rod  43  is actuated so as to lower, consequently locking the cap C 1  against the plate  19  by means of the plate  42 . Since the cap C 1  is now centered with respect to the head  40 , the subsequent lifting of the plates  19 ,  42 , actuated by the cams  9  and  57 , causes the cap C 1  to fit onto the head  40  of the tang  39  up to the level at which the region connecting the tamper-evident ring G and the cup lies at the annular slot  47  of the head  40 . 
     When a cap C 1  arrives in front of the laser emitter  46 , the carousel  1  stops and the gear  37  of the corresponding tang  39 , on which the cap is centered, meshes with the pinion  68  of the motor  67 . 
     The rotation of the tang  39 , actuated by the motor  67 , causes the rotation of the cap C in front of the emitter  46 , so that the emitted laser beam can strike the cap C 1  circumferentially between the tamper-evident ring G and the cup, forming a fracture line which is composed of circular cuts interrupted by bridges. 
     As the rotation of the carousel continues, the cams  9  and  57  actuate the descent of the spindle  12  and of the stem  43 . In particular, the descent of the stem  43  causes the separation of the cap C 1  from the head  40  and its release between the portions  69  and  70 , which are tangent to the star  23 , of a pair of side walls  71  and  72  which, together with a bottom  73 , form an exit channel  74  for the caps. It should be noted that the portion  69  fits between the disks  21  and  23  in order to extract the caps which, when the plates  19  have descended into the respective seats  24 , are released and can move freely. 
     The rotation and cutting cycle is repeated for each cap in the above described manner. 
     A prerogative of the above-described machine is that the emitted laser beam can be controlled according to various requirements, extending or shortening the cutting arcs and therefore the bridges that remain in order to join the tamper-evident ring to the cup. 
     Another advantage consists in that the machine can be easily adapted to  30  the various types of cap by replacing the tangs  39  after unscrewing the plate  42  from the stems  43  and the ring  38 . 
     The disclosures in Italian Patent Application No. BO99A000040 from which this application claims priority are incorporated herein by reference.