EP0147263B1 - Method and device for checking and controlling the filling of containers by a given weight of a product - Google Patents

Abstract

A rotary carrousel of a filling installation includes a plurality of filling stations each equipped with a volumetric dispenser (37) whose volume may be varied by varying its dispensing time or the stroke of a piston in a cylinder. At least one of the filling stations includes a balance (36). As a receptacle (39) passes through the filling installation in a filling station equipped with a balance, it is first weighed empty while the corresponding dispenser (37) is filled, and it is then weighed continuously as the material is transferred from the dispenser to the receptacle. The actual weight of material dispensed is determined by comparing the full and empty weights of the receptacle. This weight is compared with a set weight. Any drift which is detected from the set weight can be corrected for subsequent receptacles passing through the filling installation by varying the volume of the material dispensed.

Description

The object of the present invention is a method and an installation for filling containers.

In many industries, food, chemical, petroleum, pharmaceutical, etc., there is a need to package more or less fluid products for their subsequent distribution. To be profitable, the packaging operation must be both rapid and precise. On modern installations, speed is acquired but efforts are still being made to gain precision, the ideal in this area being to fill each container with exactly the quantity of product desired. However, satisfying this second requirement - precision - comes up against several difficulties, essentially linked to the rapid rate required for filling installations and the physical properties of the products to be packaged. The rapid filling rate makes it difficult to check the quantity of product introduced into each container, as for the products to be packaged, even if they are homogeneous, their density and viscosity are likely to vary with temperature, which influences their dosage. However, if we want to carry out precise filling of scrolling containers on a chain filling installation, it is necessary on the one hand to carry out an exact dosage of the product to be packaged and on the other hand to check that the filled containers contain indeed, - individually or statistically, - and contain only the quantity of product desired to be able, if necessary, to modify the dosage for the containers appearing on the carousel upstream of the weighed container.

To carry out the dosing, it is known to use volumetric dosers of the type comprising a timer which controls the opening and closing of the orifice of a reservoir of product to be packaged or of the type comprising a cylinder-piston assembly in which the piston stroke defines the volume to be introduced into the container. These dosers are adjusted to deliver a given volume of product at a given temperature. If the temperature of the product introduced into it varies over the course of a day, over a few days etc., the quantity of product introduced into the containers will vary. To check the quantity of product introduced into the containers and possibly modify the setting of the dosers in order to correct a possible lack or excess of product, it is known to use a balance, only the weight making it possible to define exactly a quantity of product which whatever the temperature.

American patent US-A-2 925 835 describes a method and a device for monitoring and controlling the filling of containers successively engaged in a chain filling installation. In the exemplary embodiment given in this patent, the containers are conveyed on a conveyor belt to a single filling station where they are filled in turn with a quantity of product dosed by a volumetric dispenser comprising a timer. Once filled, the containers continue on their journey on the treadmill to a given point where they are removed mechanically from the treadmill one after the other, placed on a fixed balance next to the treadmill, weighed, then replaced mechanically on the treadmill. The weight of the container is compared with a set value and, if necessary, the setting of the volumetric dispenser is changed. If it allows in theory to solve the problem posed, this device has some disadvantages in practice. On the one hand, the transfer of the container from the conveyor belt to the balance then from the balance to the conveyor belt as well as the weighing of the container which, to be precise, must last a minimum time, does not allow a very rapid filling rate. On the other hand, on this device, it is not intended to tare the containers. However, depending on the material of which they are made, the weight of the containers, even manufactured in series, can vary significantly. This is particularly the case for glass containers. Therefore it is not possible to determine the exact weight of the contents of the weighed containers.

Document US-A-2 961 013 describes an installation for filling receptacles by means of volumetric devices each comprising a piston moving in a cylinder, the movements of the pistons being caused by a movable cam whose position determines the volume distributed to each hit of boost. The position of the cam is controlled as a function of various parameters, but at no time is it intended to check the weight of product dispensed so that this weight can vary depending on the density of the product dispensed.

Document EP-A-52 546 describes a weight metering device in which the product to be dispensed is placed in a hopper and flows out when a filling spout is opened. Such a device is not suitable for filling containers at a high rate with a product of high viscosity.

An object of the present invention is to provide a method and an installation for filling containers which make it possible to achieve a high rate while retaining high precision whatever the viscosity of the product to be dispensed.

• - peser au moins un récipient à l'un des postes de remplissage alors que le récipient est encore vide,
• - peser de façon continue le récipient pesé à vide pendant le remplissage de ce récipient et comparer le poids net de produit introduit à une valeur de consigne,
• - agir sur l'organe de commande en fonction du résultat de cette comparaison pour modifier le volume transféré par le doseur volumétrique à l'ensemble des postes de remplissage.

In order to achieve this goal, there is provided according to the invention a method of filling containers in an installation comprising an element of the rotary carousel type with several filling stations each comprising a volumetric metering device of the type comprising a piston-cylinder assembly in which the stroke of the piston defines the volume of product transferred, this method comprising the steps of successively and individually introducing containers on a filling station while simultaneously filling the volumetric dispenser and then filling each container from the volumetric dispenser by means of '' a control member (such a method is known from document US-A-2 961 013), characterized in that it further comprises the steps of:

• - weigh at least one container at one of the stations filling while the container is still empty,
• - continuously weigh the empty weighed container during filling of this container and compare the net weight of product introduced with a set value,
• - Act on the control unit according to the result of this comparison to modify the volume transferred by the volumetric dispenser to all of the filling stations.

According to the invention there is also provided a container filling installation comprising: a rotary carousel, means for introducing containers one by one onto a plurality of filling stations each comprising a volumetric metering device of the type comprising a piston-cylinder assembly in which the stroke of the piston defines the volume of product transferred, means for filling the volumetric dispenser with product and then emptying the latter into a container, the volume transferred being determined by a control member (such an installation is known from the document US- A-2 961 013), characterized in that at least one filling station includes a scale associated with a calculation and storage device for storing the weight of an empty container introduced on the scale, the weight of the full container given by each balance to calculate the net weight of the product introduced into the container, and means for acting on the control member in order to modify the volume e of product to be introduced into the containers on the carousel upstream of the weighed container.

• - la figure 1 est une vue de dessusschémati- que d'une installation de remplissage comportant un élément de type carrousel rotatif, où ont été représentées les différentes phases du cheminement d'un récipient sur un poste de remplissage équipé d'une balance,
• - la figure 2 est une vue en coupe schématique d'un exemple de réalisation d'un poste de remplissage,
• - la figure 3 est une vue en coupe schématique selon la ligne II-II de l'exemple de réalisation d'un poste de remplissage représenté sur la figure 2, la trèmie d'alimentation et le doseur volumétrique n'étant pas représentés, et
• - la figure 4 est une vue schématique développée d'une came et de deux postes de remplissage, celui de gauche étant représenté sur la rampe montante de la came, celui de droite sur la rampe descendante de la came.

Other characteristics and advantages of the present invention will appear better on reading the following description made in conjunction with the attached drawings, among which:

• FIG. 1 is a diagrammatic view of a filling installation comprising an element of the rotary carousel type, where the various phases of the movement of a container on a filling station equipped with a scale have been represented,
• FIG. 2 is a schematic sectional view of an exemplary embodiment of a filling station,
• FIG. 3 is a schematic sectional view along line II-II of the embodiment of a filling station shown in FIG. 2, the feed hopper and the volumetric metering device not being shown, and
• - Figure 4 is a schematic developed view of a cam and two filling stations, the left one being shown on the rising ramp of the cam, the right one on the descending ramp of the cam.

In Figure 1 are shown the different phases of the path of a container placed on one of the filling stations equipped with a balance of a chain filling installation comprising a rotating carousel 3. The container is conveyed by a conveying means 1 to a distribution star 2 which introduces it at point 6 onto one of the filling stations of the carousel 3 equipped with a scale. Carousel 3 is rotated. Between point 6 and point 7 the empty container is weighed and its weight is stored in memory while the filling of the volumetric metering unit of the filling station, started at point 40, is completed. Between point 7 and point 8 and between point 8 and point 9, the volume of product contained in the volumetric dispenser is transferred with a rapid flow rate (7-8) then with a slower flow rate (8-9) from the dispenser to the container. The container is weighed continuously between its entry into the carousel and its exit from the carousel. Between point 9 and point 10 the balance stabilizes and determines the weight of the full container. A calculation and control unit, a microprocessor for example, calculates from the weight of the full container and the weight of the empty container previously stored the exact weight of the product introduced into the container, compares this weight with a set value and optionally orders the modification of the dosage which will intervene for the containers appearing at a later stage. The advantage of the mobility of the balance (s) installed on the carousel is to allow a weighing time long enough to be precise, without slowing down the filling rate. Once filled, the container leaves the carousel 3 or else at point 10, tangentially to the carousel 3, on a conveying means 25, or else at point 40, in a preferred direction, parallel to the conveying means 1 for example, by the through a distribution star 4.

2 shows a schematic sectional view of an exemplary embodiment of a filling station equipped with a balance. Each filling station is located on the rotary carousel 3 and comprises: an electronic balance 36; means 38 for centering a container 39; a product feed hopper 22 to be packaged 12; a volumetric metering device 37 comprising a piston 28 provided with sealing means 29, a cylinder 13 in which the piston 28 slides, a rod 33 actuating the piston 28; a distributor 14 comprising a body 19 and a cylindrical plug 18 capable of pivoting in the body 19.

The body 19 has a horizontal bore of axis 27; a vertical duct 24 located in its upper part and opening on the one hand into the feed hopper 12 and on the other hand into the bore of axis 27; a vertical duct 26 located in its upper part and opening on the one hand into the volumetric metering device 37 and on the other hand into the bore of axis 27; a vertical bore of the same axis as the conduit 26, surmounting the latter and receiving the cylinder 13 of the volumetric metering device 37; a vertical duct 30 located in its lower part and opening on the one hand into the bore of axis 27 and on the other hand above the container 39.

The cylindrical plug 18 occupies the vertical bore of axis 27 of the body 19 in which it can pivot. It comprises a recess 15 which, in a determined position of the plug 18 relative to the body 19, connects the conduits 24 and 26 of the body 19; a cylindrical conduit 17, without communication with the recess 15, which, in another determined position of the plug 18 relative to the body 19, connects the conduits 26 and 30 of the body 19; a control lever 20 for pivoting the plug 18 inside the body 19. Electrical, pneumatic or equivalent means, not shown in the figure, act on the control lever 20 on the instructions communicated to them by the member of calculation and order.

When a filling station is located between points 10 and 7 of the path shown in FIG. 1, the plug 18 is positioned so that the recess 15 faces the conduits 24 and 26 of the body 19 and the hopper of supply 12 and the volumetric dispenser 37 are in communication (case of FIG. 2). When a filling station is located between point 7 and point 9 of the path shown in FIG. 1, plug 18 is positioned so that the conduit 17 faces the conduits 26 and 30 of the body 19 and the volumetric metering device 37 and the container 39 are in communication.

FIG. 4 represents a schematic developed view of a cam controlling the operation of two filling stations. It must be understood that in reality such a cam is not located in a plane but is wound on a cylinder with the same center as the carousel and that it controls a number of filling stations, variable depending on the case, but well above 2.

The cam 34 shown in FIG. 2 comprises a rising ramp with two successive inclinations: ramp 340 between points 40 and 6, adjustable ramp 341, between points 6 and 7; a downward ramp with two inclinations: ramp 342 between points 7 and 8, ramp 343 between points 8 and 9; a horizontal part 344 between points 9 and 40. A cam follower 35, parallel to cam 34, is arranged above the descending ramp of cam 34, between points 7 and 9. (The numbering of these points corresponds to that of figure 1). The rising ramp corresponds to the filling of the volumetric metering device 37, which in this embodiment is a metering cylinder. The downward ramp with two inclinations corresponds to the transfer of the product at two flow speeds, from the volumetric dispenser 37 into the container 39.

The cam 34 and the cam follower 35 are fixed relative to the rotary carousel 3 on which the filling stations are installed. The cam 34 guides only the roller 32 secured to the rod 33 of the piston 28 between point 40 and point 7. Between point 7 and point 9, that is to say on the descending ramp of the cam 34, the cam 34 cooperates with the cam follower 35 to guide the roller 32.

The cam 34 has a rising ramp portion 341 whose inclination, which is variable, is adjusted by the stroke of an endless screw 16 driven by a geared motor 25. If the calculation and control member finds a difference between the weight of product introduced into the container and the set value, it controls the modification of the inclination of the ramp part 341 up or down depending on the direction of the drift. The resulting change in the volume admitted into the volumetric dispenser occurs naturally for containers that appear at a later stage.

The advantage of such a device, thanks to which the verification of the quantity of product introduced into the containers is statistical since only a fraction of the number of filling stations in the carousel is equipped with a scale, lies in the detection and in correction of any dosage drift, whatever the cause.

Claims (2)

1. A method for the filling of receptacles placed in an installation which includes a rotary carrousel type member (3) having a plurality of filling stations each comprising a volumetric dispenser (37) of the type comprising a piston-cylinder assembly in which the stroke of the piston determines the volume of material transferred, this method comprising the steps of successively and individually introducing receptacles on a filling station while simultaneously filling the volumetric dispenser, then filling each receptacle from the volumetric dispenser by means of a control lever characterized in that it further comprises the steps of:

- weighing at least one receptacle at one of the filling stations while the receptacle is still empty,

- continuously weighing during filling said receptacle weighed while empty and comparing the net weight of inserted material with a set value,

- acting on the control lever according to a function of the result of this comparison to modify the volume of material transferred by the volumetric dispenser at all filling stations.

2. Apparatus for the filling of receptacles comprising: a rotary carrousel, means to introduce receptacles one by one on a plurality filling stations each comprising a volumetric dispenser (37) of the type having a piston-cylinder assembly in which the stroke of the piston determines the volume of material transferred, means for filling the volumetric dispenser with material and emptying it into a receptacle, the volume transferred bein determined by a control member (34) characterized in that at least one filling station includes a balance (36) associated with a calculating and a storage unit for storing the weight of an empty receptacle introduced on the balance, the weight of the full receptacle given by each balance, for calculating the net weight of product inserted in the receptacle, and means (16, 25) for acting on the control member to modify the volume of material to be inserted in the receptacles arriving on the carrousel, upstream the weighed receptacle.

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