FILLED WITH A POURABLE PRODUCT"

TECHNICAL FIELD

The present invention relates to a gripper for gripping and holding containers adapted to be filled with a pourable product, preferably of a foodstuff type.

STATE OF THE ART

Packaging assemblies are known for packaging a pourable product, preferably of a foodstuff type such as, for example, water, spirits, carbonated beverages, milk, fruit juices or the like, into containers.

Typically, the assemblies of the aforementioned type are also configured for treating the containers. In this regard, these assemblies comprise a plurality of treatment units or machines each configured to carry out a specific operation during a packaging process of the pourable product.

For example, in the case where the containers are made of plastic, for example are defined by plastic bottles or small bottles, a typical treatment assembly comprises:

- a blowing unit for forming plastic containers starting from known preforms;

- a filling unit for filling the formed containers with a pre-fixed amount of pourable product;

- a capping unit for applying a cap to each previously filled container; and

- a labelling unit for applying labels to the filled and capped containers.

In the case where the containers are made of glass, the packaging assemblies do not comprise any blowing unit but include, instead of the latter, a rinsing unit for rinsing the glass containers with a rinsing fluid (for example, water) before the filling, capping and labelling operations.

Filling units are known which typically comprise a conveyor, generally of a rotary type and defined by a carousel rotatable about a vertical axis, a tank containing the pourable product, and a plurality of filling devices carried peripherally by the carousel, connected to the tank by means of respective circuits or ducts (and through a collector), and conveyed by the carousel itself along an arc-shaped filling path.

More precisely, the containers to be filled are fed in use to the carousel at an inlet station thereof, then conveyed along the filling path, which defines a filling angle with respect to the axis of the carousel, so as to be filled with the pourable product by the respective filling devices, and then withdrawn from the carousel at an outlet station thereof.

Normally, the known packaging assemblies comprise a plurality of conveyors arranged between the carousel of the filling unit and the other units of the assembly.

Typically, at least some of said conveyors are defined by star wheels, each rotatable about a preferably vertical central axis.

For example, an inlet star wheel is arranged between the rinsing unit or the blowing unit and the filling unit, and an outlet star wheel is arranged between the filling unit and the capping unit.

Other star wheels can be provided between the various units of the packaging assembly, for example between the capping unit and the labelling unit.

Grippers are known which are configured to receive, grip and hold the containers, thereby moving them along the packaging assembly.

These grippers are carried by the aforementioned conveyors.

More precisely, each star wheel comprises a plurality of said grippers fixed to a peripheral portion thereof, so as to be advanced along a circular trajectory about the respective central axis.

In this manner, each gripper cyclically receives one container at a time from one of the aforementioned units, or from an upstream star wheel, grips and holds the container for a given angle about the relative central axis, so as to move it along a conveying path, and lastly releases it to another of the aforementioned units or to a downstream star wheel.

Typically, a gripper of the aforementioned type comprises a support frame mounted on the star wheel and two claws or arms hinged to the frame and in this manner movable rotationally between an open position for receiving/releasing the container and a closing position for holding the container, usually at the neck of the latter, and thus move it along the conveying path.

The gripper may have an "active" configuration, and in this case comprises an actuator, for example a cam-cam follower system, to control the movement of the arms between the open position and the closing position.

Alternatively, the gripper may have a "passive" configuration, and in this case the opening of the arms is actuated directly by the thrust exerted by the neck of the container being received on the arms themselves.

The grippers of the type described above also comprise a fixed support element, commonly known as "tooth" or "dentil", rigidly mounted on the frame and configured to support the container received and held by the arms.

Typically, the tooth projects from the frame in the same extension direction of the arms, namely, in the direction of the gripped container, and is arranged below the arms, with respect to a vertical direction parallel to the central axis of the conveyor, or to the axis of the gripped container.

In greater detail, the tooth defines, at the free end thereof, a lateral abutment surface for supporting the neck of the container gripped by the arms.

In practice, the gripper defines a receiving seat for the container delimited between the free end of the tooth and the free ends of the arms.

Furthermore, the tooth defines an upper resting surface adapted to receive and support, resting thereon, the annular collar which is typically found on the neck of the plastic containers, and is adapted to support the sealing/tamper- evidence ring.

In light the above, the tooth performs the function of stabilising and axially supporting the gripped container, limiting the oscillation thereof during movement and, above all, during reception and delivery.

Although the grippers of the aforementioned type are functionally and structurally valid, the Applicant has noted that they are susceptible to further improvements.

In particular, the Applicant has observed that, since the distance between the free end of each tooth and the free end of the arms is fixed, namely since the dimension of the receiving seat is fixed, the tooth defines a determined fixed (radial) position of the axis of each gripped container with respect to the conveyor on which the gripper is mounted, namely with respect to the central axis of this conveyor.

In the case where it is required to provide for a format change of the containers, it is therefore necessary to substitute all of the grippers. In fact, as mentioned above, the distance between the free end of each tooth and the free end of the arms, namely the size of the receiving seat, is fixed and is therefore specifically adapted to a container of a single format/dimension.

However, a packaging assembly of the aforementioned type comprises a large number of grippers. Therefore, the format change operation is long and expensive.

Furthermore, by changing the format, also the aforementioned (radial) position of the axis of the gripped container will necessarily vary with respect to conveyor on which the gripper is mounted.

This is particularly problematic in the case where the conveyor defines the carousel of one of the aforementioned treatment units.

For example, if the aforementioned grippers are mounted on the carousel of the filling unit, it will be required to provide for a radial displacement of the filling devices, at a format change, to adapt them to the new position of the axis of each container of the new format.

This leads to obvious complications from the point of view of kinematics, flexibility and adaptability of the entire assembly.

OBJECT AND SUMMARY OF THE INVENTION

The aim of the present invention is to manufacture a gripper for gripping and holding containers adapted to be filled with a pourable product, which is of high reliability and limited cost, and allows to overcome at least some of the drawbacks specified above and related to grippers of a known type.

According to the invention, this aim is achieved by a gripper as claimed in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred non-limiting embodiment thereof is described in the following, purely by way of example and with the aid of the attached drawings, wherein:

- Figure 1 is a schematic top view, with parts removed for clarity, of part of an assembly for packaging a pourable product into containers, comprising conveyors each having a plurality of grippers manufactured in accordance with the present invention;

- Figures 2, 3 and 4 are top views, on an enlarged scale and with parts removed for clarity, of a gripper manufactured in accordance with the present invention, during three distinct operative conditions; - Figure 5 illustrates, in a perspective view, on an enlarged scale and with parts removed for clarity, a gripper manufactured in accordance with the present invention;

- Figure 6 is an enlargement of a detail of Figure 5; and

- Figure 7 is a perspective view, on an enlarged scale, with parts removed for clarity and with some parts transparent to show components internal to these parts, of a gripper according to the present invention, during an operative holding condition of a container.

DETAILED DESCRIPTION

With reference to Figure 1, number 1 indicates as a whole a packaging assembly for packaging a pourable product, preferably of the foodstuff type, such as, for example, water, wine, beer, carbonated beverages, fruit juices, milk, oil, or the like, by means of containers 2.

In the described example, and with reference to Figure 7, the containers 2 are defined by plastic bottles, to which the present description will refer without losing generality. Each container 2 has a main body 2a of axis X, an axial neck 2b, and a known annular collar 2c, which is adapted to support a sealing/tamper-evidence ring (not shown).

Alternatively, the containers 2 are defined by plastic small bottles or by glass bottles or small jars. The assembly 1 is of the known type and comprises a number of treatment units or machines (not illustrated). Each of the machines or units is configured to carry out a specific operation during the packaging process of the pourable product.

Preferably, the assembly 1 comprises:

- a blowing unit (not shown), for forming plastic containers 2 starting from known preforms;

- a filling unit, for filling the formed containers 2 with the pourable product;

- a capping unit, for capping each filled container 2; and

- a labelling unit, for applying labels to filled and possibly capped containers 2.

In the case where the containers are made of glass, the assembly 1 does not comprise the blowing unit but includes, instead of the latter, a rinsing unit for rinsing the containers 2 with a rinsing fluid (for example, water), before the filling, capping and labelling operations.

The assembly 1 furthermore comprises a plurality of conveyors 3, which are operatively interposed between the aforementioned treatment units.

In detail, at least one conveyor 3 is arranged between the filling unit and the capping unit, at least one conveyor 3 is arranged between the capping unit and the labelling unit, and at least one conveyor 3 is arranged between the blowing unit and the filling unit.

With reference to Figure 1, each conveyor 3 is defined by a star wheel. The star wheel is rotatable about a preferably vertical central axis (not illustrated). In particular, in the present description, the words "conveyor" and "star wheel" are to be considered interchangeable with one another.

In one embodiment, a plurality of star wheels 3 are interposed between two operatively adjacent treatment units.

In one embodiment, each treatment unit comprises one or more conveyors 3, namely, one or more star wheels, for moving the containers 2 during the specific treatment operation (forming, filling, capping, labelling).

Each conveyor 3 (or star wheel) comprises a plurality of grippers 4, fixed to a peripheral portion 3a thereof, so as to be advanced along a circular trajectory. Each gripper 4 is configured to grip and hold at least one container 2 at a time.

For the sake of brevity, in Figure 1 only one conveyor 3 is shown with the grippers 4 incorporated therein. However, preferably all the conveyors 3 of the assembly 1 are equipped with the grippers 4.

Alternatively, only some of the conveyors 3 are equipped with the grippers 4. Each gripper 4 is configured to cyclically carry out the following steps: receiving a container 2 from a treatment unit or from a gripper 4 of an upstream conveyor 3; holding this container 2 for a given rotation angle in order to advance this container 2 along a treatment/packaging path; releasing the containing 3 to a subsequent treatment unit, or to a gripper 4 of a downstream conveyor 3.

For the sake of brevity, in the following reference will be made to a single gripper 4 gripping a container 2. However, the structural and functional characteristics described and illustrated in relation to this gripper 4 are equally applicable to each of the grippers that are present in each conveyor 3 and in the assembly 1.

With reference to Figures 2 to 7, and in particular to Figures 5 and 7, the gripper 4 comprises a frame 5. The frame is fixable, in particular fixed, to the peripheral portion 3a of the relative star wheel 3.

The gripper 4 comprises a pair of arms 6. The arms 6 are hinged to the frame 5 by means of first hinges 7a. In this manner the arms 6 are movable in rotation between an open position (Figure 4), for receiving/releasing the container 2, and at least one closing position, in particular at least two closing positions (Figures 2 and 3), for gripping and holding the container 2.

In detail, the arms 6 project from the frame 5, in particular from a front edge 5a of the frame 5, starting from the respective first hinges 7a, and up to their respective free ends 6a which are opposite to the hinged ends.

In greater detail, the arms 6 project from the frame 5 radially outward with respect to the central axis of the respective conveyor 3 to which the frame 5 is fixed.

The gripper 4 comprises a pair of support teeth 8, which are mounted on the frame 5 and are configured to support the container 2 held by the arms 6.

According to an important aspect of the present invention, the teeth 8 are hinged to the frame 5. In this manner the teeth 8 are movable in rotation at least between a first position (Figure 2), for supporting a first format Bl of container 2, and a second position (Figure 3), for supporting a second format B2 of container 2.

With particular reference to Figure 5, each tooth 8 defines a lateral abutment 10 for (laterally) supporting the neck 2b of the container 2.

In greater detail, each tooth 8 is configured, through the lateral abutment 10, to support the neck 2b of the container 2 gripped by the arms 6, and push it towards the arms 6 when they are in a closing position, in order to strengthen the grip.

Furthermore, each tooth 8 defines an upper resting surface 11, which is adapted to receive and support, resting thereon, the collar 2c of the container 2.

In light of the above, the teeth 8 perform the function of stabilising and axially supporting the gripped container 2, limiting the oscillation thereof during movement and, above all, during reception and release.

According to an aspect of the present invention, the teeth 8 are hinged to the frame 5, directly and without interposition of the arms 6, by means of second hinges 7b. The second hinges 7b are distinct and spaced apart with respect to the first hinges 7a. In this manner the teeth 8 and the arms 6 are hinged to the frame 5 in parallel to one another, so as to obtain optimisation of the adaptability of the gripper 4 to different formats of container, since the teeth 8 can be subject, in this way, to an angular displacement different from that of the arms 6, as will become clearer in the following.

In this manner, the rotation of the teeth 8 with respect to the second hinges 7b is, in principle, separated from the rotation of the arms 6 with respect to the first hinges 7a. In other words, this configuration allows the arms 6 and the teeth 8 to be subject to different angular displacements. Therefore, an improved adaptability of the teeth 8, and therefore of the gripper 4, to the different types of container 2 is obtained. According to this preferred embodiment, the teeth 8 project from the frame 5, in particular from the front edge 5a, starting from the respective second hinges 7b and up to their respective free end portions 8a.

In particular, the teeth 8 project from the frame 5 radially outward with respect to the central axis of the conveyor 3 to which the frame 5 is fixed. More in particular, the teeth 8 extend along the same extension direction of the arms 6.

Appropriately, the gripper 4 defines a receiving seat 12 (Figure 4) for the container 2. The seat 12 is delimited (in use) between the free end portions 6a of the arms 6 and the free end portions 8a of the teeth 8.

According to the invention, the receiving seat 12 has a size variable by the rotation of the arms 6 and the teeth 8 about the respective first hinges 7a and second hinges 7b.

With reference to Figure 4, the teeth 8 are also movable in rotation to assume a non-operative position (in particular, a fully open position). In this non-operative position, the teeth 8 are spaced apart from the container 2, to allow reception and release of the container 2.

The gripper 4 is controllable in:

- a release condition (Figure 4), for receiving and releasing the container 2, in which the arms 6 are in the open position and the teeth 8 are in the non-operative position;

- a first gripping condition (Figure 2), in which the teeth 8 are in said first position and the arms 6 are in a first closing position, for gripping and holding the first format Bl of container 2; and

- a second gripping condition (Figure 3), in which the teeth 8 are in said second position and the arms 6 are in a second closing position, for gripping and holding the second format B2 of container 2.

Preferably, the container 2 is a bottle. The first format Bl and the second format B2 differ from one another at least in the diameter of the neck 2b. In particular the diameter of the neck of the first format Bl is smaller than the diameter of the neck of the second format B2.

The gripper 4 is configured so that, in the first gripping condition, the gripper 4 grips the neck 2b of the first bottle format Bl.

The gripper 4 is configured so that, in the second gripping condition, the gripper 4 grips the neck 2b of the second bottle format B2. In this way the gripper 4 is configured to better adapt to several bottle formats, since the mobility of the teeth 8 makes the support function exerted by the teeth 8 adapt better to the variation of format.

Furthermore, the displacement of the longitudinal axis X of the gripped bottle 2, which would result from the format variation, is reduced or totally eliminated, so as to reduce or eliminate the operations that would be necessary for adapting the treatment unit to the new format. These operations would be necessary, for example, in the case where the treatment unit is a filling unit or in the case where it is a capping unit, since the position of the axis X is important for the filling step and for the capping step.

In one embodiment, the gripper 4 is controllable in further gripping conditions, for gripping and holding other types of containers 2, namely, containers 2 of other formats. In these further gripping conditions, the arms 6 will be in further closing positions and the teeth 8 will be in further positions distinct from the first and second positions and from the non-operative position.

Preferably:

- the gripper 4 is configured so that, in the gripping conditions, the container 2 is positioned in front of the front edge 5a of the frame 5;

- a first direction Y is defined starting from the first hinges 7a to the front edge 5a and a second direction Z is defined by one of the first hinges 7a to the other of the first hinges 7a;

- the second hinges 7b are positioned between the first hinges 7a and the front edge, with respect to the first direction Y;

- the second hinges 7b are positioned between the first hinges 7a, with respect to the second direction Z;

- the teeth 8 are arranged below the arms 6, with respect to the central axis of the respective conveyor 3.

Preferably, the longitudinal extension of each tooth 8 is smaller than the longitudinal extension of each arm 6.

Conveniently, the gripper 4 comprises a kinematic coupling system 13 between the arms 6 and the teeth 8. The coupling system 13 is configured to couple the rotation of each arm 6 to the rotation of a respective tooth 8. The coupling system 13 allows to contain the mechanical complexity correlated with improving adaptability of the gripper 4 to the format variation, since the rotation of the arms 6 and the rotation of the teeth 8 can be obtained with the same actuator.

Preferably, the gripper 4 according to this preferred embodiment is of the "active" type, namely, the rotation of the arms 6 and of the teeth 8 is generated actively by means of an actuator 19.

The gripper 4 comprises the actuator 19. The assembly comprises an external cam. The actuator 19 is configured to control the rotation of the arms 6 by means of cooperation with the external cam.

The assembly is configured so that the rotation of the star 3 corresponds to the cooperation of the actuator 19 with the external cam, so as to control the rotation of the arms 6 between the open position and one of said first closing position and said second closing position, and therefore the rotation of the teeth 8 between the nonoperative position and one of said first position and second position. Said one of said first closing position and said second closing position and one of said first position and said second position are functions of the specific format of the container 2, by means of which the packaging is intended to be performed. In particular, the actuator 19 includes a cam follower 20 which is kinematically connected with the arms 6 to control the rotation thereof.

More in particular, as shown in Figure 7, the cam follower 20 is coupled to the arms 6 by means of a lever 22, and is adapted to cooperate in contact with a cam 21.

Alternatively, the gripper 4 may be of the "passive" type, namely, the rotation of the arms 6 and the rotation of the teeth 8 are passively controlled by the container 2 being received.

In practice, the container 2 being received in the receiving seat 12 pushes the arms 6 and the teeth 8 until they automatically adapt to the shape of the container 2 itself. In this case, the container 2 acts as an actuator.

More precisely, the system 13 kinematically couples the left arm 6 to the respective left tooth 8, and the right arm 6 to the respective right tooth 8.

An arm 6 and a tooth 8 kinematically coupled to one another, by means of the system 13, define a tooth-arm pair.

Hence, the gripper 4 comprises two tooth-arm pairs, a right pair and a left pair.

The coupling system 13 is configured so that the rotation of the arms 6 between the first closing position and the second closing position controls the rotation of the teeth 8 between the first position and the second position. The coupling system 13 is configured so that the rotation of the arms 6 between the second closing position and the open position controls the rotation of the teeth 8 between the second position and the non-operative position.

The coupling system 13 is configured so that the angular displacement of the teeth 8 about the respective second hinges 7b is different with respect to the corresponding angular displacement of the arms 6 about the respective first hinges 7a. This means that the angular displacement, to which the teeth 8 are subject during the rotation between the first position and the second position, is different with respect to the angular displacement to which the arms 6 are subject during the rotation between the first closing position and the second closing position. This also means that the angular displacement, to which the teeth 8 are subject during the rotation between the second position and the non-operative position, is different with respect to the angular displacement to which the arms 6 are subject during the rotation between the second closing position and the open position.

In this manner, the first position of the teeth 8 and the second position of the teeth 8 can be furthermore adapted to different bottle formats, thus optimising the support effect as a function of the respective bottle format.

The coupling system 13 is of a mechanical contact type. This type reduces the risk of breakdowns, so as to achieve an optimal reliability of the gripper 4.

The kinematic coupling system 13, for each arm 6 and the respective tooth 8 coupled to the arm 6, comprises a respective cam surface 14 and a respective pin 15. The cam surface 14 is integral with one 8 between the arm 6 and the tooth 8, and the pin 15 is integral with the other 6 between the arm 6 and the tooth 8.

The pin 15 cooperates in contact with the cam surface 14, to control the rotation of said one 8 by means of rotation of said other 6.

For each arm 6 and the respective tooth 8 coupled to the arm 6, the pin 15 is integral with the arm 6 and the cam surface 14 is integral with the tooth 8.

The pin 15 and the cam surface 14 are visible in Figures 5 and 6.

The gripper 4 comprises a control device 16. The control device 16 is configured to control the difference between the angular displacement of the teeth 8 and the corresponding angular displacement of the arms 6. In this manner the first position of the teeth 8 and the second position of the teeth 8 can be defined with precision, so as to obtain, through the coupling system 13, improvement in the adaptability of the gripper 4 to several formats. The control device 16 is indicated in Figures 2, 3, 4, 5 and 7.

The control device 16 acts between each tooth 8 and the respective arm 6 which is coupled to the tooth 8. In this manner, control of the positioning of the teeth 8 is carried out automatically and directly by the arms 6 themselves, so as to improve the precision in the positioning of the teeth 8 as a function of the positioning of the arms 6. In this manner an increase of the operating precision of the gripper 4 is obtained.

The coupling system 13 is configured so that the rotation of the arms 6 from the first closing position to the second closing position controls the rotation of the teeth 8 from the first position to the second position. The coupling system 13 is configured so that the rotation of the arms 6 from the second closing position to the open position controls the rotation of the teeth 8 from the second position to the non-operative position.

The gripper is configured so that the control device 16 tends to rotate the teeth 8 from the second position to the first position. Therefore, through the coupling system 13, the control device 16 tends to rotate the arms 6 from the second closing position to the first closing position. The gripper is configured so that the control device 16 tends to rotate the teeth 8 from the non-operative position to the second position. Therefore, through the coupling system 13, the control device 16 tends to rotate the arms 6 from the open position to the second closing position.

In this manner, the control device 16 limits, to the greatest extent possible, the difference of angular displacement between the arms 6 and the teeth 8, which is generated during rotation of the arms 6 from the first closing position to the second closing position, and during the rotation of the arms 6 from the second closing position to the open position. Given that the rotation of the arms 6 from the first closing position to the second closing position, and from the second closing position to the open position, controls the rotation of the teeth 8 from the first position to the second position, and the rotation of the teeth 8 from the second position to the non-operative position, respectively, the teeth 8 could rotate in an uncontrolled manner, so that the aforementioned difference increases in an uncontrolled manner. By means of the control device 16 that acts in order to bring the teeth 8 back from the non-operative position to the second position, and from the second position to the first position, and therefore the arms 6 from the open position to the second closing position, and from the second closing position to the first closing position, the gripper 4 is capable of quickly bringing both the arms 6 and the teeth 8 into the correct positions also as a function of the format. Furthermore, the control device 6 also avoids having to use mechanical stops which could increase wear.

The control device 16 is of a magnetic type. The control device 16 comprises, for each arm 6 and the tooth 8 coupled to the arm 6, a first magnet 17 integral with the arm 6, and a second magnet 18 integral with the tooth 8.

Thanks to this configuration, a sort of "positive feedback" of the gripping is also created: as the difference in angular displacement between teeth 8 and arms 6 increases, the thrust on the arms 6 towards the gripping closing position on the bottle increases.

According to a further aspect of the present invention, each tooth 8 comprises, at the free end 8a thereof, a first abutment surface 10a and a second abutment surface 10b, which both differ from the aforementioned lateral abutment 10 and which are inclined with respect to one another. In particular, each tooth 8 is configured to support the container 2 by means of: the first abutment surface 10a, when the tooth 8 is controlled in the first position (Figure 2); the second abutment surface 10b, when the tooth 8 is controlled in the second position (Figure 3).

In this manner, the support provided to the container 2 from each tooth 8 is improved, since there is an abutment surface 10a or 10b dedicated to each format of the bottle 2. Therefore, the gripping and adaptability of the gripper 4 to different formats of container 2 are furthermore improved.

In one embodiment, each tooth 8 can comprise further abutment surfaces, as many as the formats of container 2 manageable by the gripper 4.

According to a further aspect of the present invention, each arm 6 comprises a working surface 23 and an auxiliary surface 24 (Figures 5, 7).

In particular, the working surface 23 is configured to contact the container 2 and the auxiliary surface 24 is configured to counteract a possible inclination of the container 2 gripped with respect to the frame 5.

More precisely, the working surface 23 of each arm 6 operates every time the container 2 is gripped, namely, when the arms 6 are in the closing position, whereas the auxiliary surface 24 operates to limit the inclination of the container 2, bringing the axis X thereof back to the nominal position (parallel to the central axis of the conveyor 3 on which the gripper 4 is mounted).

This configuration is particularly advantageous, since it allows to limit the oscillations of the container 2 due to the centrifugal forces in play, especially during the passage thereof from a gripper 4 of a conveyor 3 to a gripper 4 of another conveyor 3. This results in a reduction of the splashes and spillages of pourable product from the container 2.

From an examination of the features of the gripper 4 according to the present invention, the advantages that it allows to obtain are evident.

In particular, the presence of teeth 8, movable and hinged to the frame 5 independently of the arms 6, eliminates the need to replace the grippers 4 in the case of a format change, allowing, at the same time, to keep the axis X of the container 2 always gripped in the same radial position with respect to the central axis of the relative conveyor 3, regardless of the type/format of the container 2 itself.

This is particularly advantageous in the case where the conveyor 3 is a conveyor of a treatment unit, for example, the filling or capping unit, since it allows to avoid complicated mechanisms for adapting to different positions of the axis X as the format of the containers 2 to be treated varies. In other words, the movable teeth 8 allow to keep the axis X of the container 2 in the same position with respect to the frame 5, in particular the same radial position, as the format of the container 2 varies, and in particular its neck 2b.

The gripper 4 according to the present invention also allows avoiding complicated components during transfer between the conveyors 3, such as guides and switch rails.

Furthermore, it is possible to avoid acting on the kinematics of the gripper 4 at a format change, since the teeth 8 and the arms 6 are self-adaptive.

Overall, the format change is easier and/or faster, and the components of the gripper 4 can be reduced.

In addition, the control device 16 avoids an uncontrolled displacement of the teeth 8 away from each other and away from the arms 6, thus allowing the angular displacement of the teeth 8 to be different from the angular displacement of the arms 6, while still maintaining a connection between these displacements.

Finally, the advantages mentioned above apply with respect to the magnetic type of the control device 16 and to the presence of different abutment surfaces 10a, 10b on the teeth 8 and of the surfaces 23 and 24 on the arms 6.

It is clear that modifications and variations can be made to the gripper 4 described and illustrated herein without thereby departing from the scope defined by the claims.