System and method for weighing containers

A system for weighing containers includes: a weighing station and a conveying path extending from an upstream infeed section to a downstream outfeed section. The conveying path includes a gripping stretch for gripping the containers and a release stretch for releasing the containers, disposed between the infeed section and the outfeed section; and a conveying device for conveying the containers from the infeed section to the gripping stretch, and the weighed containers from the release stretch to the outfeed section. The conveying device includes first and second groups of housings for receiving the containers and moving them from the infeed section to the gripping stretch. A gripping and transferring device transfers the containers from the gripping stretch to the weighing station and from the weighing station to the release stretch. The first and second groups are movable independently of each other from the infeed section to the gripping stretch.

This application is the National Phase of International Application PCT/IB2018/056634 filed Aug. 30, 2018 which designated the U.S.

This application claims priority to Italian Patent Application No. 102017000099359 filed Sep. 5, 2017, which application is incorporated by reference herein.

TECHNICAL FIELD

This invention addresses the technical field of container weighing.

More specifically, the invention relates to a system and a method for weighing containers. By container is meant a receptacles of any kind for example, a vial, a bottle (used, for example, in the pharmaceutical sector but not only there), or an electronic cigarette cartridge.

BACKGROUND ART

The containers need to be weighed before they are filled so as to be able to precisely determine the amount of product (liquid or powder) inside them when they are full.

Document EP1988018 describes a system for weighing containers which are conveyed continuously by an endless conveyor provided with housings.

The system comprises a product filling station, a weighing scale mounted alongside the conveyor, and two oscillating arms on the outside of the conveyor. The first oscillating arm is adapted to pick up a container from a housing on the conveyor and to place it on the scale. More in detail, while the conveyor moves, the first oscillating arm picks up a single container using a gripper and moves it through a circular arc.

Once the container has been weighed, the second oscillating arm picks the container from the scale and puts it back in the conveyor housing which had been left empty. More in detail, the second oscillating arm moves the weighed container through a circular arc similar and mirror symmetrical to the movement of the first arm.

This movement of the two oscillating arms is necessary because the endless conveyor, in order to reduce the total working time, moves continuously and the two oscillating arms must therefore “chase” it as it moves.

This system (and the related method) does not, however, allow all the containers to be weighed and thus leaves a wide margin of uncertainty as to the actual amount of product filled into each container.

Moreover, the proposed system is structurally complex and cumbersome.

DISCLOSURE OF THE INVENTION

The aim of this invention is to overcome the above mentioned disadvantages.

This aim is achieved by proposing a system and a method for weighing containers according to the accompanying claims.

Advantageously, the system and method according to the invention can overcome the disadvantages of the prior art because they allow all the containers to be weighed.

The system is also structurally simple and has a limited footprint.

With reference to the accompanying drawings, the numerals1,1′ denote a system for weighing containers C according to this invention.

As already stated in the introductory section, the containers C may be of any kind—for example, vials, bottles (used, for example, in the pharmaceutical sector but not only there), or electronic cigarette cartridges (in the preferred embodiment).

Generally speaking, since some containers C such as vials or parts of electronic cigarettes are reduced in size, fragile or unstable in position on account of their shape, the system1,1′ according to the invention may comprise a plurality of holders (also known as “buckets”, shown in the accompanying drawings) to support the containers C before, after and/or during filling. With reference to the drawings, all conveying operations are performed by means of the buckets in which the containers C are placed. Whatever the case, the term “container C” is used herein to denote both the container to be filled and the container and bucket together.

With reference in particular toFIGS. 1-25, the system1for weighing containers C comprises: a weighing station2for weighing the containers C; a conveying path P of the containers C, extending from an infeed section I, upstream of the weighing station2, to an outfeed section U, downstream of the weighing station2.

The conveying path P also comprises a gripping stretch T1for gripping the containers C and a release stretch T2for releasing the containers C, which are interposed between the infeed section I and the outfeed section U (better described below).

The system1also comprises conveying means3, disposed along the conveying path P for conveying the containers C to be weighed from the infeed section I to the gripping stretch T1, and the weighed containers C from the release stretch T2to the outfeed section U.

The conveying means3comprise at least a first group of housings31and a second group of housings32, adapted to receive the containers C and movable along the conveying path P from the infeed section I to the gripping stretch T1.

The system1further comprises gripping and transferring means4for transferring the containers C to be weighed from the gripping stretch T1(where the containers C are disposed inside the first and second housings31and32) to the weighing station2, and the weighed containers C from the weighing station2to the release stretch T2of the conveying path P.

The gripping stretch T1and the release stretch T2of the conveying path P thus correspond to those points where the containers C are respectively picked up from, and released onto, the conveying means3. With reference to the drawings, the gripping stretch T1and the release stretch T2of the conveying path P are parallel to each other and the conveying means3extend from them (as will become clearer below).

In particular, the first group of housings31and the second group of housings32of the conveying means3are movable independently of each other along the conveying path P, from the infeed section I to the gripping stretch T1.

Advantageously, unlike the prior art, the system1according to the invention guarantees weighing all the containers C moving along the conveying path P and not just some of them. In effect, the fact that the first group of housings31and the second group of housings32are movable independently of each other from the infeed section I to the gripping stretch T1(and preferably vice versa) means that while the containers C disposed at one of the two groups of housings are weighed, other containers C are conveyed by the other group of housings along the conveying path P and can be weighed without affecting the productivity of the machine.

In other words, the system1configured this way allows introducing “pauses” which affect only the containers C being weighed at a particular moment, without affecting the rest of the system1. In effect, it is known that weighing the containers C requires a certain amount of time and stopping the machine would have a negative effect on the overall productivity of the system1.

In the preferred embodiment, when the first group of housings31is at the gripping stretch T1, the gripping and transferring means4(pick up and) transfer simultaneously all the containers C inside the first group of housings31to the weighing station2; similarly, when the second group of housings32is at the gripping stretch T1, the gripping and transferring means4(pick up and) transfer simultaneously all the containers inside the second group of housings32to the weighing station2. Thus, all the containers C in the first group of housings31can be weighed simultaneously in the weighing station2and, similarly, all the containers C in the second group of housings32at the weighing station2can be weighed simultaneously in the weighing station2(as explained in more detail below). Advantageously, the fact that the gripping and transferring means4simultaneously transfer to the weighing station2a plurality of containers C (that is, those in the first group of housings31and in the second group of housings32) means that the containers C can all be conveyed along the conveying path P and all weighed very quickly. In other words, there is a guarantee that all the containers C (and not just a statistical “random sample” of them) are weighed rapidly.

Conveyors of the star wheel type (as illustrated in the accompanying drawings, in particularFIGS. 2 and 12) may be mounted at the infeed section I and at the outfeed section U of the conveying path P; these conveyors feed the containers C continuously to the infeed section I and receive them continuously at the outfeed section U. Alternatively, different devices used for this purpose that is, to feed and receive the containers continuously—may obviously also be provided.

With reference to the above mentioned drawings, each housing of the first group of housings31and of the second group of housings32receives only one container C.

Again with reference to the above mentioned drawings, the number of housings of the first group of housings31coincides with the number of housings of the second group of housings32but, alternatively, the number of housings of the first group of housings31might be different from the number of housings of the second group of housings32.

With reference to the preferred embodiment illustrated in the accompanying drawing, the gripping stretch T1and the release stretch T2extend along a first orientation D1and the gripping and transferring means4transfer the containers C from the gripping stretch T1to the weighing station2and/or from the weighing station2to the release stretch T2by moving the containers along a second orientation D2perpendicular to the first orientation D1.

When they are at the gripping stretch T1, the housings of the first and second groups of housings31and32are disposed along the first orientation D1. With reference to the drawings, the housings (hence the containers C) at the gripping stretch T1are arranged in a row extending along the first orientation D1(seeFIG. 5).

Advantageously, that way, the total productivity times of the system1are kept particularly low compared to prior art systems thanks to the fact that the gripping and transferring means4transfer the containers C from the gripping stretch T1to the weighing station2and from the weighing station2to the release stretch T2along the shortest possible path. Moreover, the overall dimensions needed to move the containers C are also limited.

Alternatively, in variants not illustrated, the gripping and transferring means4can transfer the containers C from the gripping stretch T1to the weighing station2and/or from the weighing station2to the release stretch T2by moving them along an orientation which is not perpendicular to the first orientation (for example along a path that is oblique or in the shape of a circular arc relative to the gripping and release stretches, that is, relative to the first orientation).

Preferably, the gripping and transferring means simultaneously transfer all the containers C present in the weighing station towards the release stretch T2.

In the preferred embodiment, the weighing station2comprises a plurality of scales20(only partly visible and represented schematically in the accompanying drawings), each used to weigh one container C; also, the gripping and transferring means4are adapted to transfer each container C to be weighed (from the gripping stretch T1) to a respective scale20. More specifically, the number of scales20is at least equal to the maximum number of containers C in the first group of housings31or in the second group of housings32, each used to weigh only one container C. This guarantees that all the containers C in the first group of housings31and in the second group of housings32are weighed independently of each other.

With reference to the accompanying drawings, the weighing station2further comprises a supporting surface5, for supporting the containers C during their transfer from the gripping stretch T1to the scales20and from the scales20to the release stretch T2. The supporting surface5comprises a plurality of through openings50(visible for example inFIGS. 8, 9, 23 and 24), each facing a corresponding scale20; the gripping and transferring means4release the containers C to be weighed at the openings50of the supporting surface5in order to engage the openings50(which are of a size suitable for this purpose). Again with reference to the accompanying drawings, the supporting surface5is substantially horizontal in orientation.

More in detail, the supporting surface5is movable vertically (that is to say, it can perform a movement which is perpendicular to the orientation of the supporting surface5itself) between a raised position, above the scales20, and a lowered position, substantially at the scales20. The openings50of the supporting surface5and the scales20are configured in such a way that when the supporting surface5is moved from its raised position to its lowered position, the containers C disengage the openings50and come into contact with the scales20and are weighed, and so that when the supporting surface5is moved from its lowered position to its raised position, the containers C engage the openings50again and disengage the scales20. For example, each scale20has a protruding portion (shown in more detail inFIGS. 8 and 9) which is at a position and of a size such as to be inserted into a corresponding opening50of the supporting surface5(seeFIG. 8, for example) so that once the supporting surface5has moved from the raised position to the lowered position, each containerC comesinto contact with the protruding portion of the respective scale20which weighs it.

Advantageously, the supporting surface5prevents the containers C from reaching the scales20by scraping: the scales are very high precision, delicate instruments which would be easily damaged if subjected to stresses different from those strictly connected with their function.

In the preferred embodiment of the invention, the conveying means3comprise a first conveying unit300(shown in detail inFIGS. 18 and 19) which in turn comprises: a first endless belt33, which carries the first group of housings31, and two first pulleys35, around which the first belt33is looped and which, together with the first belt33, move the first group of housings31.

The first conveying unit300also comprises a second endless belt34which carries the second group of housings32, and two second pulleys36, around which the second belt34is looped and which, together with the second belt34, move the second group of housings32(refer once again in particular toFIGS. 18 and 19).

With reference to the accompanying drawings, the pulleys have a vertical axis and the sections of the belts looped round the pulleys lie on the gripping stretch T1and on the release stretch T2of the conveying path P, along the first orientation D1.

More specifically, the two first pulleys35and the two second pulleys36are movable independently of each other and are mounted respectively in pairs, juxtaposed (more specifically superposed) and coaxial with each other.

The above described feature allows the first and second groups of housings31and32to be moved independently of each other and is structurally simple and limited in cost. Other alternatives are possible, however, as described in more detail below.

In the embodiment illustrated inFIGS. 23-25, the weighing station2is disposed on the outside of the conveying path P of the containers C, alongside the conveying means3; moreover, the container C gripping stretch T1and the container C release stretch T2of the conveying path P coincide. In other words, the conveying means3extend from the infeed section I to the outfeed section U of the conveying path P, preferably in a straight line (as in the case illustrated in the above mentioned figures). In this case, therefore, each container C, after being weighed, may be disposed in the same housing it was disposed in before being weighed.

With reference in particular toFIGS. 23-25, the conveying means3(two belts and four pulleys, as described above) define a closed profile (substantially rectangular in shape).

Advantageously, this embodiment allows other operations to be carried out, if necessary, on one or more sections of the closed profile defined by the conveying means3—for example, the one distal from the weighing station2(opposite the gripping stretch T1and the release stretch). By way of example, these operations may consist in inspecting a sampled group of containers C; these, after being weighed, are not conveyed towards the outfeed section U and, instead, continue travelling along the closed profile defined by the belts33,34to reach inspection stations (not illustrated).

With reference toFIGS. 23-25, the weighing station2is on the outside of the closed profile defined by the belts33,34. This solution allows easier access to the weighing station2when necessary (for example, malfunctioning, cleaning or maintenance).

In an alternative not illustrated, the weighing station2is on the inside of the closed profile defined by the conveying means3(but in any case always on the outside of the conveying path P). This solution is particularly compact.

Now described briefly below is the operation of the system1according to the embodiment described above and illustrated inFIGS. 23-25.

The containers C, transported for example by means of buckets (as specified previously), are fed by the infeed station to the gripping stretch T1of the conveying path P for example by means of the above described star wheel feeders, which release a first group of containers C into the first group of housings31, which may advance towards the gripping stretch T1. In the meantime, a second group of containers C is received by the second group of housings32.

At this point, the first group of housings31is at the gripping stretch T1(which, in this embodiment, as stated above, coincides with the release stretch T2) and remains stationary until the respective containers C are: picked up by the gripping and transferring means4(which, in this case, may comprise a plurality of upturned U-shaped gripper elements42arranged in a row); placed on the supporting surface5; weighed on the scales20(by moving the supporting surface5as described above); picked up again by the gripping and transferring means4and released onto the same group of housings. The latter can then proceed towards the outfeed section U where, for example, one or more star wheel conveyors are mounted.

In the meantime, the second group of housings32has reached the gripping stretch T1/release stretch T2to allow weighing the respective containers C, while the first group of housings31, now empty, moves along the closed profile defined by the belts and is positioned at the infeed section I to receive other containers C.

Alternatively to the above, in a variant not illustrated, the gripper elements mentioned above might not be present and, instead, the containers might be gripped and transferred by the gripping elements supporting surface itself, adapted and structured to disengage the containers from the respective housings and, after weighing, replace them in the same housings. According to this solution, for example, the supporting surface may perform a cyclic stroke in which it moves translationally twice vertically and twice horizontally to define a substantially rectangular, closed path to pick up, weigh and put the containers back in place. Obviously, other means suitable for this purpose might be provided.

With reference toFIGS. 1-17, the conveying means3further comprise a third group of housings40and a fourth group of housings41, adapted to receive the containers C and movable independently of each other along the conveying path P from the release stretch T2to the outfeed section U.

When they are at the release stretch T2, the housings of the third and fourth groups of housings40and41are disposed along the first orientation D1. With reference to the above mentioned drawings, in particularFIG. 10, the housings (of the third group40or of the fourth group41), hence the containers C, are, at the release stretch T2, disposed in a row extending along the first orientation D1(as already stated for the housings disposed along the gripping stretch T1).

As shown inFIGS. 1-17, the weighing station2is positioned along the conveying path P of the containers C (that is, on the inside of the conveying path P), in particular between the gripping stretch T1and the release stretch T2of the conveying path P.

Advantageously, this embodiment offers particularly reduced dimensions (at least along one of the two directions of extension) and facilitates access to the entire system1in case of need (for example, maintenance, cleaning or other operations).

With reference to the above mentioned drawings, each housing of the third group of housings40and of the fourth group of housings41receives only one container C.

Again with reference to the above mentioned drawings, the number of housings of the third group of housings40coincides with the number of housings of the fourth group of housings41but, alternatively, might be different. Whatever the case, the number of housings of the third group of housings40is at least equal to the maximum number of containers C in the first group of housings31or in the second group of housings32, so as to enable all the weighed containers C to be received in the release stretch T2(the same applies to the number of housings of the fourth group of housings41).

With reference to the embodiment described above, the first conveying unit300is positioned upstream of the weighing station2. Downstream of the weighing station2, the conveying means3also comprise: a second conveying unit400in turn comprising a third endless belt43, carrying the third group of housings40; and two third pulleys (not illustrated), around which the third belt43is looped and which, together with the third belt43, move the third group of housings40. The second conveying unit400also comprises a fourth endless belt44which carries the fourth group of housings41, and two fourth pulleys (not illustrated), around which the fourth belt44is looped and which, together with the fourth belt44, move the fourth group of housings41.

More in detail, the two third pulleys and the two fourth pulleys (which, in the accompanying drawings, have a vertical axis) are movable independently of each other and are mounted respectively in pairs, juxtaposed (more specifically, superposed) and coaxial.

The above described feature allows moving the third and the fourth group of housings41in the same way as described above with regard to the first and the second group of housings32.

It is noted that the second conveying unit400is not fully illustrated because it is the same as the first conveying unit300which is, instead, illustratedFIGS. 18 and 19, commented above.

Now described briefly below is the operation of the system1according to the embodiment described above and illustrated inFIGS. 1-17.

Similarly to what is described above for the embodiment illustrated inFIGS. 23-25, the containers C, transported for example by means of buckets are fed by the infeed section I to the gripping stretch T1of the conveying path P for example by means of a star wheel feeder which releases a first group of containers C into the first group of housings31(seeFIG. 2 or 3, for example) which may advance towards the gripping stretch T1.

Next, the first group of housings31is moved to the gripping stretch T1, where the respective containers C are: all picked up simultaneously by the gripping and transferring means4seeFIGS. 4-6, for example) (which, in this case, comprise two rows of upturned U-shaped gripper elements42); placed on the scales20and all weighed simultaneously (by moving the supporting surface5, as described above). In the meantime, the second group of housings32has been moved to the gripping stretch T1together with corresponding containers C.

While the containers C in the second group of housings32are all picked up simultaneously by the gripper elements42which form a row, the containers C on the scales20are all picked up simultaneously by the other row of gripper elements42and released onto the release stretch T2, where they are received by the third group of housings40which carries the containers C towards the outfeed section U.

At the same time, the fourth group of housings41moves to the release stretch T2to receive the containers C which have just been weighed.

Each group of housings (first31, second32, third40and fourth41) may include any number of housings, depending on requirements.

Obviously, there may be more groups of housings in addition to those mentioned above.

Each housing31,32,40,41may comprise, for example, a suction cup capable of holding the container while it is being conveyed. Alternatively, or in combination with what has just been said, the correct position of the containers C in the respective housings may be guaranteed by other means such as, for example, grippers/fingers or specially shaped walls/panels.

With reference to the accompanying drawings, each housing is shaped to match the part of the container C it has to receive; in this specific case, it defines a rounded housing.

Alternatively to the system1for moving the containers C with two belts, as described above, a variant not illustrated might comprise a conveyor (or more than one conveyor) with independent carriers (that is, housings) driven by a linear motor.

For example, the gripping and transferring means4may be of the pick and place type and may comprise a robot linked to the gripper elements42(which, in the accompanying drawings are in the shape of an upturned U. Refer in particular toFIGS. 14-17.

Alternatively to what is stated above, the gripping and transferring means4may comprise a linkage mechanism (not illustrated) with two degrees of freedom, which carries gripper elements42(for example in the shape of an upturned U, as inFIGS. 1-4, described in more detail below) and which allows gripping and moving the containers C as described above.

With reference in particular toFIGS. 1-17 and 20-22and as mentioned above, the gripping and transferring means4comprise two parallel rows of gripper elements42that are connected and suitably spaced apart: that way, with a single movement, it is possible to move the containers C, already weighed on the scales20, onto the release stretch T2, and the containers C, on gripping stretch T1, still to be weighed, onto the scales20(in place of those picked up). Advantageously, the total times of the system1are thus optimized. More in detail, the number of gripper elements42is at least equal to the maximum number of containers C in the first group of housings31or in the second group of housings32, each used to pick up and transfer only one container C. That way, all the containers C can be transferred simultaneously from the housings31,32on the gripping stretch T1to the weighing station2(and then to the transfer stretch T2). The gripping and transferring means4illustrated in the drawings move with a reciprocating, to-and-fro movement along two opposing orientations: one (substantially vertical) to pick up and release the containers C (in two opposite directions) and the other (substantially horizontal) to transport the containers C picked up and, after releasing the latter, to move back to the gripping position (hence in two opposite directions).

This invention also relates to a system1(illustrated inFIGS. 26 and 27) for weighing containers C, different from the system described above, but linked to the same inventive concept (as explained in more detail below). With regard to the containers C, what is stated above obviously applies.

The system1′ for weighing containers C comprises: a weighing station2′ for weighing containers C, a conveying path P′ of the containers C, extending from an infeed section I′, upstream of the weighing station2′, to an outfeed section U′, downstream of the weighing station2′.

The conveying path P′ also comprises a gripping stretch T1′ for gripping the containers C and a release stretch T2′ for releasing the containers C, which are interposed between the infeed section I′ and the outfeed section U′.

The system1′ also comprises conveying means3′, disposed along the conveying path P′ for conveying the containers C to be weighed from the infeed section I′ to the gripping stretch T1′, and the weighed containers C from the release stretch T2′ to the outfeed section U′.

The conveying means3′ comprise at least a first group of housings31′ and a second group of housings32′, adapted to receive the containers C and movable along the conveying path P′ from the infeed section I′ to the gripping section T1′.

The system1′ further comprises gripping and transferring means4′ for transferring the containers C to be weighed from the gripping stretch T1′ (where the containers C are disposed inside the first and second housings31′ and32′) to the weighing station2′, and the weighed containers C from the weighing station2′ to the release stretch T2′ of the conveying path P′.

The gripping stretch T1′ and the release stretch T2′ of the conveying path P′ thus correspond to those points where the containers C are respectively picked up from, and released onto, the conveying means3′. With reference to the drawings, the gripping stretch T1′ and the release stretch T2′ of the conveying path P′ are parallel to each other and the conveying means3′ extend from them.

More specifically, the first group of housings31′ and the second group of housings32′ of the conveying means3′ are connected to each other and arranged in a row; moved along the conveying path P′ at a first speed from the infeed section I′ towards the gripping stretch T1′, and at a second speed, lower than the first speed (and preferably zero), when they are at the gripping stretch T1′, to allow the gripping and transferring means4′ to grip the containers C.

Advantageously, unlike the prior art, the system1′ according to the invention (as already stated for the system1) guarantees weighing all the containers C moving along the conveying path P′ and not just some of them. In effect, the fact that the first group of housings31′ and the second group of housings32′ are linked to each other and arranged in a row and movable at a first speed from the infeed section I′ to the gripping stretch T1′, and at a second speed, lower than the first speed, when they are at the gripping stretch T1′, means that while the containers C disposed at one of the two groups of housings are picked up by the gripping and transferring means4′ and weighed, other containers C are conveyed by the other group of housings along the conveying path P′ at a higher speed without affecting the productivity of the machine.

In other words, the system1′ configured this way allows introducing “pauses” which affect only the containers C which are on the gripping stretch T1′ to be picked up at that moment and then weighed, without affecting the rest of the system1′. In effect, it would not otherwise be possible to weigh all the containers C without stopping the machine, which would negatively affect the overall productivity of the system1′.

In the preferred embodiment, when the first group of housings31′ is at the gripping stretch T1′, the gripping and transferring means4′ (pick up and) transfer simultaneously all the containers inside the first group of housings31′ to the weighing station2′; similarly, when the second group of housings32′ is at the gripping stretch T1′, the gripping and transferring means4′ (pick up and) transfer simultaneously all the containers inside the second group of housings32to the weighing station2.

Advantageously, the fact that the gripping and transferring means4′ simultaneously transfer to the weighing station2′ a plurality of containers C (that is, those in the first group of housings31′ and in the second group of housings32′) means that the containers C can all be conveyed along the conveying path P and all weighed very quickly. In other words, there is a guarantee that all the containers C (and not just a statistical “random sample” of them) are weighed rapidly.

Conveyors of the star wheel type (as illustrated in the accompanying drawings) may be mounted at the infeed section I′ and at the outfeed section U′ of the conveying path P′. Alternatively, different devices used for this purpose may obviously also be provided. These conveyors move continuously to feed the containers C towards and away from the housings at a constant speed.

As shown in the drawings which illustrate this embodiment, and as described above for the preceding embodiment, each housing of the first group of housings31′ and of the second group of housings32′ receives only one container C.

Again with reference to the drawings which illustrate this embodiment, the number of housings of the first group of housings31′ coincides with the number of housings of the second group of housings32′ but, alternatively, the number of housings of the first group of housings31′ might be different from the number of housings of the second group of housings32′.

Again with reference toFIGS. 26 and 27, the conveying means3′ further comprise a belt403′ carrying the first group of housings31′ and the second group of housings32′, two translatory pulleys (303′,304′), around which the belt403′ is looped and movement means, to allow the two translatory pulleys303′,304′ to be moved along an orientation of translation Y′ parallel to their centre-to-centre line (in two opposite directions).

In practice, the belt403′ moves around the two translatory pulleys303′,304′ to receive the containers C fed continuously by the infeed section I′, for example in the first group of housings31′ until they reach the gripping stretch T1′. Here, the containers C inside the first group of housings31′ must be picked up by the gripping and transferring means4′ and are thus fed at the second speed, preferably at a standstill (that is, their speed is zero). To do this, the belt403′ is no longer moved (driven) directly by the two translatory pulleys303′,304but, in order to simultaneously allow other containers C to be fed continuously to the conveying means3′ (for example, in the second group of housings32′) the two translatory pulleys303′,304′ are moved (translated) (for example, by means of a cam not illustrated) along an orientation parallel to the respective centre-to-centre line, in a first direction of translation. This creates a buffer of containers C on the belt403′ without having to interrupt the flow of containers C from the infeed section I′.

Once the containers C which were in the first group of housings31′ have been picked up by the gripping and transferring means4′ to be weighed, the belt403′ resumes its movement under the action of the two translatory pulleys303′,304′ which, at the same, time return to the starting position by moving translationally along an orientation parallel to the respective centre-to-centre line in a second direction of translation (opposite to the first direction of rotation) until the containers C in the second group of housings32′ reach the gripping stretch T1′.

In other words, the path of the containers C between the infeed section I′ and the gripping stretch T1′ is a variable path defined by the translation of the two translatory pulleys303′,304′ to and fro along an orientation of translation Y′ parallel to the respective centre-to-centre line.

The embodiment illustrated inFIGS. 26 and 27provides a system very similar to the one just described for transferring the weighed containers from the release stretch T2′ to the outfeed section U′.

More specifically, there is another pair of translatory pulleys305′,306′ which can move translationally in the same way as described above in connection with the pair of translatory pulleys303′,304. There is also another belt404′ looped around the other translatory pulleys305′,306′, a third group of housings40′ and a fourth group of housings41′ carried by the belt404′.

In the embodiment illustrated inFIGS. 26 and 27, the weighing station2′ is disposed along the conveying path P′ of the containers C in the same way as described above in connection with the embodiment illustrated inFIGS. 1-17. For details regarding the weighing station2′, the presence of the supporting surface5′ (and the related drive system) and the gripping and transferring of the containers, the reader is therefore referred to the above description.

In a variant not illustrated, alternative to the this solution, the weighing station2′ might be disposed on the outside of the container conveying path P′. With regard to the operation of the weighing station2′, the number of scales and the gripping and transferring means4′, the reader is referred to what is stated above in connection with the solution illustrated inFIGS. 23-25.

The invention also relates to a machine (not illustrated) for filling and weighing containers C and which comprises: a first system1,1′ for weighing containers C (according to any one of the embodiments described above), for weighing empty containers (C) to be filled; and a filling station (not illustrated), that receives the empty containers (C), weighed in the first weighing system1,1′ and filled with a filling product (for example, liquid or powder); and a second system1,1′ for weighing containers C (according to any one of the embodiments described above), for weighing the containers C filled in the filling station.

The machine also comprises a control unit which is connected to the first weighing system1,1′ and to the second weighing system1,1′ and which, for each container C, calculates the weight of the product placed therein (by calculating the difference between the weight of the full container C and the weight of the empty container C) and hence, the amount of product filled into the containers C.

Furthermore, for each container C, the control unit compares the calculated product weight with a reference value which, for example, is stored in an internal memory of the control unit itself. If the calculated value is different from the reference value (plus or minus a given tolerance, if necessary), the container C is rejected at a specific point of the machine.

The invention also relates to a method for weighing containers C, comprising the following steps:conveying a plurality of containers C along a conveying path P, from an infeed section I towards a gripping stretch T1of the path;gripping the containers C at the gripping stretch T1of the path and transferring them to a weighing station2;weighing the containers C;after weighing the containers C, gripping the containers C and transferring them to a release stretch T2of the conveying path (P);conveying the containers C towards an outfeed section U.

In particular, during the conveying of the containers C from the infeed section I to the gripping stretch T1, at least a first group and a second group of containers C are conveyed independently of each other.

In the preferred embodiment, the containers C of the first group of containers are all transferred simultaneously from the gripping stretch T1to the weighing station2; similarly, the containers C of the second group of containers are all transferred simultaneously from the gripping stretch T1to the weighing station2. Preferably, the containers C of the first group of containers are weighed simultaneously (each on a respective scale, as already stated) and the containers C of the second group of containers are weighed simultaneously (each on a respective scale, as already stated).

For example, the method can be implemented using the system1described above.

Advantageously, the method according to the invention guarantees weighing all the containers C moving along the conveying path P, unlike the prior art methods. In effect, the fact that a first group of containers C and a second group of containers C are moved independently of each other from the infeed section I to the gripping stretch T1means that while the first group of containers C is weighed, the other group of containers C is conveyed towards the weighing station2. In other words, the method allows introducing “pauses” which affect only the containers C being weighed at a particular moment, without affecting the others. In effect, it is known that weighing the containers C requires a certain amount of time and stopping altogether would have a negative effect on the overall productivity.

Preferably, the gripping stretch T1and the release stretch T2of the conveying path P are oriented along a first orientation and the containers C are transferred from the gripping stretch T1to the weighing station2and from the weighing station2to the release stretch T2along a second orientation, perpendicular to the first orientation.

Advantageously, that way, as stated above in connection with the system1, the total productivity times of the system1are kept particularly low compared to prior art systems thanks to the fact that the containers C are transferred from the gripping stretch T1to the weighing station2and from the weighing station2to the release stretch T2along a path oriented perpendicularly to the first orientation.

Alternatively, in variants not illustrated, transfer may occur along paths oriented differently, that is to say, not perpendicularly to the first direction.

In one embodiment, during the conveying of the containers C from the release stretch T2to the outfeed section U, at least a third group and a fourth group of containers C are conveyed independently of each other.

Advantageously, this feature also allows optimizing the operations for weighing the containers C.

Another weighing method of the invention, alternative to the one described above, comprises:conveying a plurality of containers C along a conveying path P′, from an infeed section I′ towards a gripping stretch T1′ of the path;gripping the containers C at the gripping stretch T1′ of the path and transferring them to a weighing station2′;weighing the containers C;after weighing the containers C, gripping the containers C and transferring them to a release stretch T2of the conveying path P′;conveying the containers C towards an outfeed section U′.

More specifically, the containers C are conveyed at a first speed from the infeed section I′ to the gripping stretch T1′ and are carried at a second speed, lower than the first speed, when they are at the gripping stretch T1′. Preferably, the second speed is zero.

In the preferred embodiment, the containers C of the first group of containers are all transferred simultaneously from the gripping stretch T1′ to the weighing station2′ and the containers C of the second group of containers are all transferred simultaneously from the gripping stretch T1′ to the weighing station2′. Preferably, the containers C of the first group of containers are weighed simultaneously (each on a respective scale, as already stated) and the containers C of the second group of containers are weighed simultaneously (each on a respective scale, as already stated).

This method, too, like the one described above, allows creating “pauses” in order to facilitate weighing of the containers.

The invention also relates to a method for filling and weighing containers C and which comprises, in succession:a first step of weighing the empty containers C to be filled;a step of filling the weighed containers C;a second step of weighing the containers C after they've been filled.
Following the above steps, the method also comprises the steps of:calculating the weight of the product filled into each container C and hence, the amount of product;comparing the weight of the product filled into each container C with a reference value; andif the weight of the product filled into a container C does not coincide with the reference value (plus or minus a given tolerance), rejecting the container C.