Abstract:
The system for filling tubes in a tube-filling machine comprises a closed-ring line activated with alternating motion which bears holders destined to receive upturned tubes, with an open end thereof facing upwards in order to receive a nozzle destined to inject into the tube, after raising of the holder-tube group, a batch of a liquid or paste solution. The nozzle is supplied by a volumetric filler, a cylinder of which is connectable, with consent of an associated switching valve, either with a product supply tank or with the nozzle. The holder, the piston of the volumetric filler and the switching valve are activated by corresponding electric actuators by means of a command, management and control unit according to data, processed by the unit, respectively defining a format of the tube, the diameter of the cylinder of the volumetric filler, the viscosity of the product, the batched amount of the product and the number of tubes to be filled per unit of time.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a system and a method for batching a product (liquid and/or pasty solutions) at a same time as filling tubes in an automatic tube-filling machine. 
         [0002]    Tube-filling machines include a conveyor line, activated in alternating motion, which bears equidistanced holders, each holder being destined to receive a head of an empty tube provided with a relative cap, such as to keep the tube vertically-arranged with the posterior part thereof open and facing upwards. 
         [0003]    The line comprises various work stations: 
         [0004]    a tube-loading station; 
         [0005]    a tube-orientating station; 
         [0006]    a tube-filling station (batching the product); 
         [0007]    various stations for closing the posterior end of the tube, conformed according to the nature of the material (for example, aluminum, plastic, laminates, etc.) that the tube is made of; 
         [0008]    a tube-coding station; 
         [0009]    a station for closing the posterior edge of the tube; 
         [0010]    a reject station for discarding tubes considered to be defective; 
         [0011]    a full-tube outlet station. 
         [0012]    At least an injecting nozzle (if the tube-filling machine is single-channel) is comprised in the filling station, which nozzle is downwardly-orientated, and which nozzle is centered with respect to the posterior mouth of the tube positioned in the station; in suitable phase relation with the position, the holder-lift, in which the tube is inserted, is raised by suitable first activating means, such as to insert the nozzle in the tube. 
         [0013]    At this point the nozzle is supplied with the product, in phase relation with the holder-lift, and therefore the tube, up to completion of the filling thereof; completion of the lowering of the holder leads to exit of the nozzle from the tube. 
         [0014]    The nozzle is connected to a volumetric filler, constituted by a cylinder in which a piston sealedly slides, which piston is borne by a stem that projects from a head of the cylinder, and which is movable axially by means of second activating means. 
         [0015]    The remaining head of the cylinder affords two through-holes, which with the aid of a switching valve adjacent to the head are alternatively connected one to a product supply tank (liquid and/or paste solution) and the other with the nozzle. The valve is switched by third activating means. 
         [0016]    In a first phase the batcher aspirates the product from the tank: the length of the piston travel determines the batched amount of the product; when the valve switches, which is performed in phase relation with the inversion of the piston movement, the product is compressed by the piston and is consequently fed to the nozzle and fills the tube. 
         [0017]    The first, second and third activating means are constituted by mechanical cams which are driven by relative actuators, conformed such as to respect the above-described mutual phase relations, obviously over the machine cycle of the filling station. 
         [0018]    In particular, the second activating means cause: the piston travel (thus the batched amount of the product); the speed of the piston in the cylinder during the product aspiration phase; and the speed of the piston on compression of the product directed towards the nozzle. 
         [0019]    As specified, the holder-lift in the filling station is raised towards the nozzle and thereafter lowered during the filling of the tube borne by the holder. 
         [0020]    The length of the holder-lift stroke is a function of the tube size and the batched amount of the product; the law of movement with which the holder-lift is lowered is strictly connected to the speed with which the piston compresses the product. 
         [0021]    The product inserted into the tubes can exhibit a viscosity comprised within a broad spectrum. The viscosity might be comparable to water, or it might be high as in very pasty creams. 
         [0022]    In the case of low viscosity (compatibly with the inertia of the piston and the cam moving it) the aspiration is fast and the compression slow in order to prevent even partial emptying of the conduit connecting the nozzle with the batcher. If the product is highly viscous, the speed of product aspiration has to be such as to prevent cavitation in the product, while the compression speed is as rapid as possible considering the inertia in the masses involved. 
         [0023]    To sum up, in the prior art the variation of the batch of product, comprised in the operating volume of the batcher cylinder, and if the batch is to be optimized, requires the replacement of the cams of the second activating means. In this way, batch-for-batch, on variation of the viscosity it is possible to establish various ranges of viscosity for which predetermined speeds of aspiration and compression can be attributed to the piston. This can be obtained by corresponding cam profiles in the second activating means. 
         [0024]    This is a compromise solution which, among other things, does not resolve the mentioned drawbacks. In fact, if a following product has a viscosity in a different range from the previous one, at least the cams of the first and second activating means have to be changed. 
       SUMMARY OF THE INVENTION 
       [0025]    The advantage of the present invention is that it provides a system which in a tube-filling machine such as in the preamble hereto, using a cylinder/piston batching cylinder, and according to the size of the tube, the viscosity of the product and the productivity of the machine itself, enabling the aspirating/pumping strokes of the piston working inside the cylinder to be regulated, as well as the aspiration and compression speeds of the piston itself, the switching between the product aspiration phase and the product compressing stage, the travel of the holder-lift and the speed of rising and lowering of the holder-lift. 
         [0026]    A further advantage of the invention is that it provides a system which can be activated by means of instructions provided directly by an operator or calculated from previously-stored data relating to the tube, the batch, the product to be processed by the tube-filling machine. 
         [0027]    A further advantage of the invention is to actuate the system using reliable and functional organs, managed by means of algorithms which process data such as to use the technical-functional aspects of the technical expert in the sector and deducible from experience and/or experimental testing, such as the speed of the aspirating/pumping piston according to the product viscosity, such as to optimize the productivity of the tube filling stage, in respect of the tolerances in the batched product. 
         [0028]    A further advantage of the invention is to provide a method, actuable with the present system, which enables the batching of tubes to be optimized while changing the tube format, the format of the batcher, the viscosity of the product, the batched amount of the product and the productivity required, compatibly with the organs used, all of which is obtainable without replacing mechanical parts, such as cams or specially-shaped devices for various formats. 
         [0029]    The above-described advantages are obtained by means of a system for filling tubes in a tube-filling machine and by means of a method actuated according to the aforementioned system. 
         [0030]    The system for filling tubes in a tube-filling machine for filling tubes in a tube-filling machine is of a type comprising a closed-ring line, activated in alternating motion, which line bears equidistanced holders, each conformed such as to receive a head, provided with a cap, of an empty tube arranged vertically with an open posterior end facing upwards, the line comprising at least a station for filling each tube with a batch of product constituted by a liquid or paste solution, which station comprises at least a nozzle for supplying product to the tube located in the station, and first activating means for vertically translating a holder-lift which brings a group comprising the holder and the tube to insert and disinsert the nozzle into and out of the tube, which nozzle is supplied by a volumetric filler of a cylinder-piston type, with the piston being solidly constrained to a stem projecting from a head of the cylinder, the stem being axially moved by second activating means, the cylinder being connectable via a switching valve, adjacent to a remaining head of the cylinder and moved by third activating means, either with a supply tank of the product or with the nozzle, the system comprising a command, management and control unit, destined to receive and process: 
         [0031]    data relating to geometric dimensions of the empty tube; 
         [0032]    data relating to a diameter of the cylinder; 
         [0033]    data relating to a viscosity of the product; 
         [0034]    data relating to an amount of a batch of the product with which the tube, situated in the filling station, will be filled; 
         [0035]    data relating to a number of tubes to be filled in a given unit of time; 
         [0036]    and wherein the first, second and third activating means are constituted by three actuators acting in a suitable phase relation on the holder-lift, the stem and the switching valve, which actuators are activated by signals supplied by the unit in accordance with the data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    The characteristics of the invention are set out in the following description, which makes reference to the figures of the accompanying tables of drawings, in which: 
           [0038]      FIG. 1  schematically illustrates, in plan view, an arrangement of the work stations of a tube-filling machine; 
           [0039]      FIG. 1A  schematically illustrates, with reference to station D of  FIG. 1 , a volumetric filler and electrical-electronic organs and devices associated thereto in order to actuate the proposed system and methods; 
           [0040]      FIGS. 2-5  illustrate the same configuration as in  FIG. 1  in various work stages; 
           [0041]      FIG. 6  is a diagram of the stages which together act to realize the batching of the product inserted in the tube; 
           [0042]      FIG. 7  is a schematic lateral view of an empty tube; 
           [0043]      FIG. 8  is a flow-chart listing the significant stages of the proposed method. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0044]    With reference to the figures of the drawings, L denotes a closed-ringed conveyor line of an automatic tube-filling machine, for example a single-channel machine. The line carries, in a known way to an expert of the sector, equidistanced holders  1  each of which is destined to receive the head  2 A or shoulder of an empty tube  2  provided with a relative cap  3 , such as to keep the tube itself arranged vertically with the open posterior end  2 B facing upwards ( FIGS. 1A-5 ). 
         [0045]      FIG. 1  denotes various work stations arranged along the line L, among which, in order: 
         [0046]    a station C for loading tubes into relative holders  1 ; 
         [0047]    a station O for orientating the tubes; 
         [0048]    a station P for cleaning an internal surface of the tubes; 
         [0049]    a station D for filling the tubes, with a predetermined batch of product  4  (liquid and/or paste solutions); 
         [0050]    various stations R 1 , R 2 , R 3 , R 4 , for closing and sealing the posterior end of each tube, conformed according to the material (e.g. aluminum, plastic, laminates, etc.) with which each tube is constituted; 
         [0051]    a station J for coding the tubes; 
         [0052]    a station W for trimming the posterior edge of each tube; 
         [0053]    a station K for rejecting tubes which are considered to be defective; 
         [0054]    a station E for outletting full tubes  2  from the line. 
         [0055]    The present invention is focused on the volumetric filler  10 , which is functionally associated to the filling station D, and on the electrical and electronic organs and devices cooperating with the volumetric filler  10 . 
         [0056]    It therefore follows that the remaining stations, and the means associated thereto, have not been illustrated and described in detail, as they are generally well-known to the expert in the sector and are not relevant to the object of the invention. 
         [0057]    The batcher  10  comprises a cylinder  5  in which a piston  6  sealedly runs, borne by a stem  7  exiting from a head  5 A of the cylinder  5 . 
         [0058]    The remaining head  5 B of the cylinder affords two through-holes  8 ,  9  which, with the aid of a switching valve  11 , are alternatively connected, one (first position X 1 ) with a tank  12  for supply (gravity or pressure) of the product and the other (second position X 2 ) with a pipe  13  connected to a nozzle  14 . 
         [0059]    The nozzle  14  is connected to the filler station D, faces downwards and is centered with respect to the posterior mouth  2 B of an empty tube positioned in the station. 
         [0060]    The switching valve  11  is activated by an actuator  15  (signal  3 ) preferably an electric actuator, supplied by a control, management and command unit  100 . 
         [0061]    The stem  7 , to which the piston  6  is solidly constrained, is activated by an actuator  16 , preferably and electric actuator  16 , with interposing of an interface mechanism  16 A which transforms the rotation of the drive shaft in a direction or in another, into translation of the stem  7  in a direction or in another; the actuator  16  is managed by the unit  100  (signal  2 ). 
         [0062]    As specified in the preamble, the holder  1  disengages from the line L and is raised in the filler station D; this is done by action of a holder-lift  50  bearing the holder  1 , which holder-lift  50  is moved by an actuator, preferably an electric actuator, managed by the unit  100  (signal  1 ). 
         [0063]    The switching valve  11 , the batcher  10 , and the holder-lift  50  are not activated by means of mechanical cams as in the prior art, but are moved respectively by actuators  15 ,  16 ,  17  according to laws of movement imposed by the unit  100  as specified herein below. 
         [0064]    With reference to  FIG. 7 , D 1  denotes the tube and H 1  the height of the tube starting from the shoulder  2 A thereof; the height H 2  of the product  4  internally of the tube is linked to the batch amount and the diameter D 1 . 
         [0065]    The difference between the heights H 1  and H 2 , denoted by D 1 , identifies the minimum closing distance, i.e. the portion of the posterior end of the tube which will be folded and sealed in the stations R 1 -R 4 . 
         [0066]    D 3  denotes the distance, with the holder-lift  50  in the lowered position, between the nozzle and the extremity of the posterior end  2 B of the tube. 
         [0067]    An interface (or panel)  150  for data entering is functionally connected to the unit  100 . 
         [0068]    The operator, by means of an appropriate keyboard T, transmits the following data to the unit  100 : 
         [0069]    geometric characteristics, denoted by reference Y 1 , relating to the values D 1 , D 2 , D 3 , H 1 , H 2  identifying the size and dimensional characteristics of the tube  2 , or associated to the tube (e.g. parameter D 3 ); 
         [0070]    the diameter of the cylinder  5  of the volumetric filler; reference Y 2 ; 
         [0071]    the viscosity of the product  4 ; reference Y 3 ; 
         [0072]    the value of the batch, i.e. the volume of the product to be inserted in the tube; reference Y 4 ; 
         [0073]    production speed, i.e. the number of batching cycles (i.e. tubes filled in the filler station D) in a given time unit; reference Y 5 . 
         [0074]    The unit  100 , according to the data Y 1 , Y 4  determines the height H 2  of the product internally of the tube and, consequently, the height by which the holder-lift  50  will be raised. 
         [0075]    The travel of the stem  7 , i.e. the piston  5 , is calculated according to the data Y 2 , Y 4 . 
         [0076]    Data Y 3  will give the viscosity and Y 5  the productivity, and these are used to calculate the speed of the piston  5  on aspiration of the product  4  by the tank  12 , and the speed with which the product is compressed on supply to the nozzle  14 . 
         [0077]    Obviously a priority is the value of the tolerances established for the value of the batch (aspiration/pumping of the product  4 ) with respect to the productivity. 
         [0078]      FIG. 6  includes, in a machine cycle (360 degrees in mechanical terms) the graphs relating to the piston movements  6  (reference α 1 ), of the conveyor line L (reference α 2 ) of the holder-lift  50  (reference α 3 ) and the switching valve  11  (reference α 4 ); graphs α 1 -α 4  give the mutual phase relations between the various movements. 
         [0079]    The following phases are in phase relation with the start of the pause of line L: 
         [0080]    the piston  6  completes aspiration of the product (graph α 1 ); 
         [0081]    the holder-lift  50  raises the holder  1 -tube  2  group with the maximum speed that the motor torque (actuator  17 ) allows, positioning the nozzle  14  at the bottom of the tube (see  FIG. 2 ). 
         [0082]    The final of the above phases is preceded by the completion of the phase of aspiration (see graphs α 1 , α 3 ). 
         [0083]    The switching of the valve  11  from the first position X 1  to the second position X 2  is set in phase relation with the definition of the raising of the holder-lift  50  and the end of the product aspiration phase; see graph α 4  and  FIG. 2 . 
         [0084]    Following the switching the valve  11 , the following occur, in synchrony: the product compression phase, by effect of the piston  6 , internally of the cylinder  5 , with a consequent exit of the product  4  from the nozzle  14 , and me descent of the holder-lift  50  which bears the holder  1 -tube  2  group (see  FIG. 3  and graphs α 1 , α 2 ). 
         [0085]    The descent of the holder-lift  50  is done in two steps, one at constant velocity synchronously with the pumping of the product to the nozzle ( FIGS. 3 ,  4 ), the other at the maximum velocity allowed by the actuator  17 , in order to allow the nozzle  14  to completely exit from the tube  2  ( FIG. 5 ) and to enable the holder  1  to deposit in the relative seating afforded in the line L as quickly as possible. 
         [0086]    In phase relation with the moment that divides the two descent phases of the holder-lift  50 , the product stops exiting from the nozzle, in consequence of a signal β 4  supplied by the unit  100 , connected to the fact that the pump action of piston  6  ceases; the switching valve is then brought into the first position X 1 , the line L is moved by a step (corresponding to 120 degrees of the machine) and the piston  6  beings a new aspirating phase. 
         [0087]    An example of an operating cycle, obtained using the present method using the above-described and illustrated system, can be deduced from the flow chart of  FIG. 8 . 
         [0088]    The first phase F 1  includes the analysis of data Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , already described herein above. 
         [0089]    The second phase F 1  includes the definition of the holder-lift  50  according to data Y 1  and Y 4 . 
         [0090]    In the third phase F 3  the value of the descent run of the holder-lift is calculated. 
         [0091]    In the fourth phase F 4  it is calculated whether the holder-lift raising time is greater than or equal to the time in which the valve  11  remains in the first position X 1  (aspiration of the batch into the cylinder  5 ). 
         [0092]    If these criteria are satisfied, the batch aspiration time is set to be equal to the lift time of the holder-lift  50  (fifth phase F 5 ). 
         [0093]    If these criteria are not satisfied, a fifth auxiliary stage F 5 * is set, in which the batch aspiration time is equal to the time in which the valve  11  remains in the first position X 1 . 
         [0094]    In the sixth phase, F 5 , the time available for batching (injection of the product  4  in the tube  2 ) is calculated. 
         [0095]    In the seventh phase F 7 , the pause time of the holder-lift  50  is calculated according to the time required by the valve  11  to switch from the first position X 1  to the second position X 2 . 
         [0096]    In the eighth phase F 8  the cycle time of the holder-lift  50  (rise, pause and descent) is calculated to see whether it is less than or equal to the pause time of the machine (for example 240 machine degrees); if this criterion is not satisfied, the machine cycle velocity is too fast and is considered to be unacceptable. 
         [0097]    If the above criteria are satisfied, the percentage calculation (ninth phase F 9 ) of the time required for aspirating the batch and for pumping the batch is proceeded to, in machine degrees, taking into consideration the data Y 3  relating to the viscosity of the product  4 . 
         [0098]    The times identify corresponding piston  6  velocities; if (tenth phase F 10 ) this falls within the mechanical limits of the piston  6 -stem  7  group and the relative actuator  16 , and the holder-lift  50  and the relative actuator  17 , the cycle is considered to be valid and operative (eleventh phase F 11 ); if the result is the contrary, the cycle is not accepted (eleventh auxiliary phase F 11 *). 
         [0099]    On changing the tube format, and/or the cylinder diameter  5 , and/or the product viscosity, and/or the batch, and/or the productivity, the data Y 1 -Y 5  (displayed on the monitor F included in the interface  150 ) are correspondingly modified and the unit  100 , in agreement with the new data, commands the actuators  15 ,  16 ,  17  accordingly. 
         [0100]    The parameter which varies most frequently is viscosity, such that, taking the tube  2  format, the batch and the cylinder  5 -piston  6 -valve  11  group to be the same, the unit  100  intervenes to change the speeds of the piston runs  6  (and the descent velocity of the holder-lift  50 ). 
         [0101]    Thus the combination of the unit  100  and the actuators  15 ,  16 ,  17  enables “electronic cams” to be realized, with which the valve  11 , the piston  6  and the holder-lift  50  can be commanded, in order to optimize the batching and the time required to carry out the batching, thus obviating the drawbacks in the prior art. 
         [0102]    The provided system does not include the replacement of mechanical cams, as in the prior art, and is also very versatile indeed as it can be adapted to all possible situations, solely by entering data Y 1 -Y 5  in the unit  100 . 
         [0103]    The provided method is such as to optimize the functioning of the batcher meter  10 , in particular in relation to the productivity of the filler station D, and independently of the variations in the data Y 1 -Y 5 . 
         [0104]    The data which identify a tube format, a cylinder  5 -piston  6 -valve  11  group, a product (via the viscosity thereof), a batch value and a productivity are stored in the unit  100  and can be recalled when identical tube-batching situations arise.