System And A Method For Filling Tubes In A Tube-Filling Machine

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.

1 ) A system for filling tubes in a tube-filling machine 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:
 data relating to geometric dimensions of the empty tube;   data relating to a diameter of the cylinder;   data relating to a viscosity of the product;   data relating to an amount of a batch of the product with which the tube, situated in the filling station, will be filled;   data relating to a number of tubes to be filled in a given unit of time;   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.   
   
   
       2 ) The system of  claim 1 , wherein the command signals of the activating actuators respectively of the holder-lift and of the stem of the piston are such as to make a descent of the holder-lift synchronous with the pumping action of the piston. 
   
   
       3 ) The system of  claim 2 , wherein the command signal of the activating actuator of the holder-lift defines two phases for descent of the holder-lift, of which a first phase, synchronous with the pumping action of the piston, and a second phase, actuated with the nozzle when unsupplied, to enable exit of the nozzle from the tube. 
   
   
       4 ) The system of  claim 1 , wherein the command signal of the activating actuator of the holder-lift is such as to impose a raising of the holder-lift with a maximum speed compatible with a potential of the actuator. 
   
   
       5 ) The system of  claim 3 , wherein the command signal of the activating actuator of the holder-lift commands performance of the second phase with a maximum speed compatible with a potential of the actuator. 
   
   
       6 ) The system of  claim 1 , wherein the actuators are activated by a same number of electric motors. 
   
   
       7 ) The system of  claim 1 , wherein the tank supplies the product contained therein to the cylinder by force of gravity or under pressure. 
   
   
       8 ) The system of  claim 3 , wherein the nozzle is provided with an electrically-commanded obturator for activating and deactivating the nozzle, wherein the obturator is brought into a relative deactivated position by means of a signal supplied by the unit at a moment between the two phases. 
   
   
       9 ) A method actuated according to the system of  claim 1 , wherein the processing performed by the command and control unit comprises:
 analysis of data relating to a format of the tube, of data relating to a diameter of the cylinder, of data relating to a batch amount of the product, and of data relating to productivity;   calculation of a travel of the holder-lift according to both the data, relating to the format of the tube, and the data relating to the batch;   evaluation of a descent run of the holder-lift;   verification that a raise time of the holder-lift is greater than or equal to a time in which the switching valve remains in a first position thereof, in which position product is aspirated into the cylinder;   equality between the aspirating time of the batch into the cylinder and the holder-lift raise time;   evaluation of a time necessary for performing the batching;   determination of a pause time of the holder-lift as a function of a time required by the switching valve for passing from the first position for connecting the cylinder with the tank to a second position for connecting the cylinder with the nozzle;   verification that a sum of the lift time, the pause time and the descent time of the holder-lift is less than, or equal to, a pause time of the line;   percentage calculation, in machine degrees, of a time required for aspirating the batch into the cylinder and for pumping the batch towards the nozzle, all of which is evaluated as a function of the data relating to the viscosity of the product;   evaluation of whether the calculation is compatible with the activating organs of the piston and the holder-lift;   acceptance of the cycle on receiving a positive response to the preceding point.   
   
   
       10 ) The system of  claim 9 , wherein if the lift time of the holder-lift is less than the time in which the switching valve stays in the first position thereof, the raise time of the holder-lift is made equal to the time required for aspirating the batch into the cylinder. 
   
   
       11 ) The system of  claim 9 , wherein if a sum of the lift time, pause time and descent time of the holder-lift is greater than a pause time of the line, an operating cycle is considered not valid. 
   
   
       12 ) The system of  claim 9 , wherein the operating cycle is considered not valid if a calculation of times necessary for aspirating the batch and for pumping the batch are not compatible with the activating organs of the piston and of the holder-lift.