Technical Field

The present invention concerns a capping head for the application of caps on containers or bottles, as well as a capping assembly using at least one such head.

More particularly, the present invention concerns a capping head for the application of caps on containers or bottles, equipped with ejection means which are particularly reliable and suitable to operate in aseptic conditions.

The present invention further concerns a method for cap insertion into and cap ejection from a capping head.

Prior Art

Capping heads are devices allowing tightly sealing a cap or plug on the mouth of containers or bottles, for instance of the kind intended for containing foodstuffs such as beverages. Such heads include, in known manner, an assembly for gripping a cap, which is moved by means of a moving assembly located axially above the gripping assembly. In general terms, the moving assembly includes a plurality of control mechanisms and an associated lubricating system, all enclosed within a casing.

Capping heads are generally employed in capping assemblies also referred to as "capping machines", which usually include a movable support moving a plurality of capping heads, generally mounted on the periphery of the same support, by following a path along which also the containers to be capped are conveyed and synchronously with said containers.

While each capping head and the corresponding container positioned under the head are moving along the common path, the capping head - previously loaded with a cap retained in a receiving seat in the gripping assembly - moves downwards in order to apply the cap onto the container mouth, while possibly rotating the gripping assembly in order to screw the cap, and then moves back to a lifted position.

If the cap application operation is not performed, e.g. because there is no underlying container or because of a misaligned positioning of the cap in the receiving seat in the gripping assembly of the capping head preventing the proper cap application on the mouth of the container, it is necessary that such a cap is removed before the head returns to the position in which it is to take a new cap in order to perform a new capping cycle on a new container. To this end, the prior art capping heads are generally equipped with an ejection rod, which is mounted so as to be axially slidable through the gripping and moving assemblies forming the capping head and the axial position of which is controlled by a respective control drive, e.g. a mechanical cam drive, in which a roller connected to the rod is slidably constrained.

The Applicant has realised that the provision of an ejection rod guided through the capping head may be a source of contamination between the gripping assembly, located in the lower part of the head and kept in aseptic condition, and the above-lying moving assembly, through which assemblies the rod slides.

Actually, in order to comply with the cleanliness and hygienic safety rules required e.g. in the foodstuff field, it is necessary to keep the moving assembly isolated from the gripping assembly, since, as said above, the moving assembly includes the various control mechanisms of the machine and the associated lubricating system.

In order to obviate the above drawback, it is known to use an ejector member, confined within the lower and outer portion only of the capping head, in place of the ejection rod passing through the moving assembly and coming out from the bottom thereof towards the gripping assembly. More particularly, a small cylinder is provided, which is housed within the cap receiving seat defined in the gripping assembly so as to be free to axially slide in such a seat and is connected to a circumferential outer flange surrounding the gripping assembly. When the cap is picked up, it penetrates into the receiving seat and tends to axially lift the small cylinder jointly with the circumferential flange.

If, at the end of the capping path, the cap remains inside the receiving seat in the gripping assembly, whereby the outer flange is in a lifted configuration, the cap interacts with stop walls preventing it from being lifted together with the capping head. Such an interaction causes a lowering of the flange relative to the cap receiving seat and, consequently, a downward push exerted by the small cylinder on the cap present in such a seat, whereby the cap is ejected.

The Applicant has noticed that such a solution, even though it does not entail the risk of contamination between the moving assembly and the gripping assembly since the ejector member is confined in the lower portion of the capping head, has however some drawbacks. Indeed, it compels to provide an abutment located along the capping path, with which the ejector can cooperate.

Moreover, the Applicant has also noticed that such a solution requires making a gripping assembly with a more complex structure, which must be suitable to house the small cylinder and to allow its connection with the outer flange.

Further, the Applicant has noticed that the overall weight and size of the gripping assembly surrounded by the outer flange is increased, so that the resulting structure has a considerably increased moment of inertia, thereby negatively affecting the performance at variable or high speed.

Still further, the Applicant has noticed that, when the cap is inserted in the receiving seat in the gripping assembly, the cylinder rests by gravity on the cap itself, thereby causing sometimes unwanted ejections of the cap during the capping path.

Thus, the need exists to provide a capping head, which is equipped with a cap ejecting member capable of operating without contaminating the gripping assembly of the capping head and which at the same time is scarcely subjected to wear.

It is an object of the present invention to overcome the problems and the limitations of the prior art, by providing a capping head equipped with a cap ejecting member, which is characterised by a limited moment of inertia in case of rotation, while having at the same time a structure that is simple and compact and that can be produced at limited costs.

It is another object of the present invention to provide a capping head, which is equipped with a cap ejecting member minimising the risk of unwanted ejections.

The above and other objects are achieved by the capping head for the application of caps on containers or bottles as claimed in the appended claims.

Description of the invention

The capping head for the application of caps on containers or bottles according to the invention includes a cap gripping assembly, comprising a hollow body longitudinally extending along a vertical axis and defining therein a receiving and retaining seat for the cap. The receiving and retaining seat is delimited below by an inlet mouth for cap introduction.

The capping head further includes a moving assembly for the gripping assembly, connected to the gripping assembly for controlling the movement thereof.

The capping head according to the invention includes an ejector member housed inside the hollow body of the gripping assembly and comprising a movable element free to axially slide within the hollow body.

In accordance with a preferred feature of the invention, the hollow body has a closed end wall directed towards the moving assembly, such that the gripping assembly is hermetically separated from the moving assembly. This advantageously allows avoiding contaminations between the gripping assembly, kept in aseptic condition, and the moving assembly. Moreover, this makes the gripping assembly completely washable.

In accordance with another preferred feature of the invention, the ejector member comprises at least a first magnetic element suitable to magnetically interact with at least a second magnetic element having the same polarity, placed outside the gripping assembly and at a greater axial height than the first magnetic element, such that a relative axial approach between the second magnetic element and the first magnetic element causes, by magnetic repulsion, a translation of the ejector member towards the inlet mouth of the gripping assembly.

Advantageously, by using the first and second magnetic elements, it is possible to transfer an axial thrust without need to bring such magnetic elements into mutual contact, and hence without the ejector member housed within the sterile gripping assembly being acted upon by contact by an outer element capable of contaminating it.

In accordance with a further preferred feature of the invention, the gripping assembly comprises an upper chamber with variable volume located between the ejector member and the closed end wall of the hollow body. Advantageously, the upper chamber is a partially tightly- sealed chamber arranged to dampen the axial sliding of the ejector member. Indeed, such an upper chamber is arranged to communicate in calibrated manner with the receiving and retaining seat for the cap through a suitable gap between an outer side wall of the movable element of the ejector member and an inner side wall of the hollow body.

Thanks to said dampening function, an impulsive movement of the ejector member is prevented. In the absence of said dampening function, such an impulsive movement would take place when the magnetic repulsion force between the first and the second magnetic element exceeds the magnetic attraction force between the magnetisable element and the first magnetic element. By preventing the impulsive movement, frictions and excessive wear of the ejector member and the hollow body are advantageously reduced.

In accordance with an optional feature of the invention, the upper chamber is arranged to communicate in a calibrated manner with the receiving and retaining seat for the cap by means of suitable channels provided in an outer side wall of the movable element of the ejector member and/or in an inner side wall of the hollow body.

In accordance with another optional feature of the invention, the capping head comprises at least one side chamber with variable volume located between an outer side wall of the movable element of the ejector member and an inner side wall of the hollow body. The side chamber is a partially tightly- sealed chamber arranged to dampen the axial sliding of the ejector member. Actually, the side chamber is arranged to communicate in calibrated manner with the upper chamber through a suitable gap between an outer side wall of the movable element of the ejector member and an inner side wall of the hollow body.

In accordance with a further optional feature of the invention, the upper chamber is arranged to communicate in calibrated manner with the side chamber by means of suitable channels provided in an outer side wall of the movable element of the ejector member and/or in an inner side wall of the hollow body.

In accordance with a further preferred feature of the invention, the gripping assembly further includes an element made of a magnetisable material, arranged to interact with the first magnetic element of the ejector member so as to generate a magnetic attraction force sufficient to keep the ejector member in a suspended configuration. Advantageously, thanks to such a suspended configuration, the ejector member does not discharge its weight on the cap, thereby avoiding the risk of unwanted cap ejections.

Advantageously, the gripping assembly of the capping head according to the present invention can operate at both high and low temperatures and has a long working life.

The capping head according to the present invention enables inserting a cap into the capping head by performing the steps of:

- picking up a cap by means of the gripping assembly;

- introducing the cap into and retaining the cap in the receiving and retaining seat of the gripping assembly;

- making the ejector member axially slide from a first equilibrium position, distal relative to the closed end wall of the hollow body, towards a second equilibrium position, proximal relative to the closed end wall of the hollow body, as a result of the introduction of the cap into the receiving and retaining seat;

- keeping the ejector member of the capping head in the second equilibrium position by magnetic attraction between a first magnetic element of the ejector member and a magnetisable element included in the gripping assembly;

- causing, as a result of the axial sliding of the ejector member, a compression of the upper chamber and a consequent calibrated leakage of an air volume from the upper chamber;

- dampening, as a result of said compression of the air volume and the consequent calibrated leakage of the air volume from the upper chamber, the axial sliding of the ejector member.

The capping head according to the present invention enables ejecting a cap from the capping head by performing the steps of:

- keeping the ejector member in the capping head in a second equilibrium position by magnetic attraction between a first magnetic element of the ejector member and a magnetisable element included in the gripping assembly;

- making a second magnetic element, arranged outside the gripping assembly, approach the first magnetic element;

- making the ejector member axially slide from the second equilibrium position, proximal relative to the closed end wall of the hollow body, towards a first equilibrium position, distal relative to the closed end wall of the hollow body, as a result of the approach and the consequent magnetic repulsion between the first magnetic element and the second magnetic element;

- causing, as a result of the axial sliding of the ejector member, an expansion of the upper chamber and a consequent calibrated leakage of an air volume into the upper chamber;

- dampening, as a result of said expansion of the air volume and the consequent calibrated leakage of the air volume into the upper chamber, the axial sliding of the ejector member;

- ejecting the cap from the capping head.

Advantageously, said air leakages reduce friction and the creation of powders and debris, thereby reducing overheating and making the ejector member and the hollow body self-cleaning.

Lastly, the present invention concerns a capping assembly on which the capping head described above is mounted. The structure of the capping assembly is not disclosed in detail, since it may be made in any manner known in the state of the art.

In general terms, capping assemblies typically have a carousel structure with a plurality of capping heads circumferentially moving along the carousel synchronously with respective supports for the containers, also mounted on a carousel.

At each turn of the carousel, each capping head is axially displaced and it possibly rotates in order to perform the coupling (by insertion or by screwing) of a cap on the mouth of a container.

During each operation cycle, each capping head picks up a respective cap (in known manner) from a cap magazine, it is lowered in order to apply the cap on the container mouth and then it is lifted again to an upper dead-point position where it is again ready to pick up another cap .

Brief Description of the Figures

The above and other features and advantages of the present invention will become more apparent from the following description of preferred embodiments given by non- limiting examples with reference to the accompanying drawings, in which elements denoted by a same or similar numerical reference correspond to components having the same or similar functions and construction, and in which:

- Fig. 1 is a part-sectional side elevation of a first embodiment of a capping head according to the present invention, in a first working condition of elements of a cap ejecting member;

- Fig. 2 is a part-sectional side elevation of a gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 1, in a step of introducing the cap into the receiving seat of the gripping assembly;

- Fig. 3 is a part-sectional side elevation of a gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 1, in a step of retaining the cap in the receiving seat of the gripping assembly;

- Fig. 4 is a part-sectional side elevation of a gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 1, at the beginning of a cap ejection step;

- Fig. 5 is a part-sectional side elevation of a gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 1, at the end of a cap ejection step;

- Fig. 6 is a part-sectional side elevation of a gripping assembly and of elements of a cap ejecting member of a second embodiment of capping head according to the present invention, in a step of introducing the cap into the receiving seat of the gripping assembly;

- Fig. 7 is a part-sectional side elevation of the gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 6, in a step of retaining the cap in the receiving seat of the gripping assembly;

- Fig. 8 is a part-sectional side elevation of the gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 6, at the beginning of a cap ejection step;

- Fig. 9 is a part-sectional side elevation of the gripping assembly and of elements of a cap ejecting member of a capping head as shown in Fig. 6, at the end of a cap ejection step. Description of some Preferred Embodiments of the Invention

Referring to Fig 1, a capping head 30 according to a first embodiment carries at its bottom end a gripping assembly 10 for a cap 50, in which assembly an ejector member 16 according to a first embodiment operates.

Gripping assembly 10 is moved (translated and/or rotated) by means of a moving assembly 31 included in capping head 30 and located above gripping assembly 10. Moving assembly 31 is not shown in detail since it can be made in any manner known in the state of the art.

Gripping assembly 10 includes a hollow body 11 with tubular shape delimited upwards, i.e. towards moving assembly 31, by a closed end wall 17, preferably integrally made with hollow body 11.

Hollow body 11 internally defines a receiving and retaining seat 12 for cap 50. To this end, hollow body 11 has a mouth 13 provided with means suitable to retain cap 50 through a positive and/or non-positive coupling (e.g. resiliency). In the example shown in the Figures, such means (retaining means) comprise a plurality of balls 14 and a resilient ring 15 surrounding them and extending around tubular body 11. Balls 14 project through openings of the internal surface of seat 12 so that they are pressed against the side wall of cap 50 by resilient ring 15.

Ejector member 16 is slidably mounted inside tubular body 11 of gripping assembly 10 and it includes a movable element 18, free to axially slide along axis A of hollow body

11, and a first magnetic element 20 connected, preferably in fixed manner, to movable element 18 of ejector member 16 and located above that element.

A second magnetic element 23 is further provided, which is carried by a rod 26 located inside moving assembly 31 of gripping assembly 10 and vertically sliding along axis A. The second magnetic element 23 has the same axial polarity as the first magnetic element 20 so that, when the second magnetic element 23 is made to approach from above the first magnetic element 20, it causes by magnetic repulsion a downwards translation, i.e. towards mouth 13 of gripping assembly 10, of that element and therefore of movable element 18.

Advantageously, since hollow body 11 is closed at its top by end wall 17 and translation of rod 26 is confined inside moving assembly 31, gripping assembly 10 is hermetically separated from moving assembly 31, thereby separating the lower aseptic part from the upper operating part.

In accordance with a preferred feature of the present invention, an upper chamber 19 with variable volume is formed inside hollow body 11. Said chamber is bounded in axial direction by ejector member 16 and by closed end wall 17 of hollow body 11 and in radial direction by a portion of an inner side wall 21 of hollow body 11. Advantageously, said upper chamber 19 is a partially tightly-sealed chamber, arranged to communicate in calibrated manner with receiving and retaining seat 12 for cap 50 so as to dampen the axial sliding of movable element 18 of ejector member 16, as it will be disclosed below.

More particularly, upper chamber 19 communicates with receiving and retaining seat 12 by means of leakages between an outer side wall 22 of movable element 18 of ejector member 16 and inner side wall 21 of hollow body 11, which walls are separated by a suitable gap 24.

Moreover, upper chamber 19 can communicate with receiving and retaining seat 12 by means of suitable channels (not shown) formed in the outer side wall 22 of movable element 18 of ejector member 16 and/or in inner side wall 21 of hollow body 11. Said channels may have different geometries, e.g. they may be rectilinear or spiral- shaped.

Preferably, gripping assembly 10 further includes an element 25 of magnetisable material, e.g. of ferromagnetic material. Such a magnetisable element 25 is for instance ring-shaped, with longitudinal axis coinciding with axis A of hollow body 11, and it is located in the upper part of hollow body 11, preferably in proximal position relative to end wall 17 of hollow body 11. Preferably, ring-shaped magnetisable element 25 has such a diameter as to enable ejector member 16 to slide inside it and to arrive in abutment against end wall 17 of hollow body 11.

Magnetisable element 25 interacts with the first magnetic element 20 of ejector member 16 so as to generate a magnetic attraction force sufficient to keep ejector member 16 in a suspended configuration. Thus, ejector member 16 does not discharge its weight on cap 50, thereby advantageously avoiding the risk of unwanted ejections of cap 50.

Figures 6 to 9 show a second embodiment of capping head 130. In accordance with such a second embodiment, both outer side wall 122 of movable element 118 of ejector member 116 and inner side wall 121 of hollow body 111 have a stepped profile. The stepped profiles of said surfaces 121, 122 are complementary. In this way, a first abutment 127 formed in outer side wall 122 of movable element 118 of ejector member 116 faces a second abutment 128 formed in inner side wall 121 of hollow body 111. Said two stepped profiles give rise to a ring-shaped side chamber 129 with variable volume, bounded in axial direction by the first and second abutments 127, 128 and in radial direction by portions of outer side wall 122 of movable element 118 of ejector member 116 and of inner side wall 121 of hollow body 111.

Advantageously, said side chamber 129 is a partially tightly-sealed chamber arranged to communicate in calibrated manner with upper chamber 19 and with receiving and retaining seat 112 for cap 50 so as to dampen the axial sliding of ejector member 116, as it will be disclosed below.

More particularly, side chamber 129 communicates with upper chamber 19 and with receiving and retaining seat 112 by means of leakages between outer side wall 122 of movable element 118 of ejector member 116 and inner side wall 121 of hollow body 111, which walls are separated by a suitable gap 124.

Moreover, side chamber 129 can communicate with upper chamber 19 and/or with receiving and retaining seat 112 by means of suitable channels (not shown) formed in the outer side wall of movable element 118 of ejector member 116 and/or in inner side wall 121 of hollow body 111. Said channels may have different geometries, e.g. they may be rectilinear or spiral- shaped.

In accordance with further embodiments, further side chambers can be provided, which are formed between the outer side wall of the ejector member and the inner side wall of the hollow body, similarly to side chamber 129.

The operation of capping head 30, 130 according to the present invention will now be described, as far as the operations of inserting cap 50 into gripping assembly 10, 110 and ejecting cap 50 from gripping assembly 10, 110 are concerned.

As to the insertion of cap 50, the operation of the capping head is disclosed hereinbelow.

Initially, capping head 30, 130 is lowered onto cap 50 carried by a suitable magazine (not shown) in order to pick up the cap. During this step, ejector member 16, 116 is located, and is kept by gravity, in a first equilibrium position, distal relative to end wall 17 of hollow body 11, 111 (Figs. 2, 6).

Then, cap 50 is introduced into receiving and retaining seat 12, 112 of gripping assembly 10, 110, by overcoming the action of resilient ring 15, and is kept inside said seat due to the elastic reaction of ring 15 pushing balls 14 against the side wall of cap 50 (Figs. 3, 7).

When cap 50 is introduced into receiving and retaining seat 12, 112, ejector member 16, 116 axially slides and moves back to a second equilibrium position, proximal relative to end wall 17 of hollow body 11, 111. In such a position, the first magnetic element 20 is located in proximity of magnetisable element 25 and advantageously, as previously disclosed, it is kept by such an element in the suspended condition, so that it does not discharge its weight on cap 50.

In accordance with the first embodiment, as a result of the axial sliding of ejector member 16 from the first equilibrium position towards the second, a compression of upper chamber 19 (inside which the pressure increases) occurs, with a consequent calibrated leakage of an air volume from upper chamber 19 to receiving and retaining seat 12. Preferably, upper chamber 19 is reduced to an air bearing when ejector member 16 is in the second equilibrium position.

As a result of the compression of upper chamber 19 and the consequent calibrated leakage of the air volume from upper chamber 19, the axial sliding of ejector member 16 is advantageously dampened.

In accordance with the second embodiment, as a result of the axial sliding of ejector member 116 from the first equilibrium position towards the second, besides the compression of upper chamber 19 (inside which the pressure increases), also an expansion of side chamber 129 (inside which the pressure decreases) occurs; consequently a calibrated leakage of an air volume from upper chamber 19 to side chamber 129 is obtained. Preferably, upper chamber 19 is reduced to an air bearing when ejector member 116 is in the second equilibrium position

As a result of the compression of upper chamber 19 and the expansion of side chamber 129, and of the consequent calibrated leakage of the air volume from upper chamber 19, the axial sliding of ejector member 116 is advantageously dampened.

As to the ejection of cap 50, the operation of the capping head is disclosed hereinbelow.

Initially, capping head 30, 130 retains a cap 50 that was not applied. During this step, ejector member 16, 116 is located, and is kept by magnetic attraction between the first magnetic element 20 and magnetisable element 25, in a second equilibrium position, proximal relative to end wall 17 of hollow body 11, 111 (Figs. 3, 7).

Then, the second magnetic element 23 is made to approach the first magnetic element 20, so as to cause a magnetic repulsion force between the first and the second magnetic elements 20, 23.

As a result of the approach and the consequent magnetic repulsion between the first magnetic element 20 and the second magnetic element 23, ejector member 16, 116 axially slides from the second equilibrium position towards the first equilibrium position, distal relative to end wall 17 of hollow body 11, 111. In accordance with the first embodiment, as a result of the axial sliding of ejector member 16 from the second equilibrium position towards the first, an expansion of upper chamber 19 (inside which the pressure decreases) occurs, with a consequent calibrated leakage of an air volume from receiving and retaining seat 12 to upper chamber 19 (Figs. 4, 5).

As a result of the expansion of upper chamber 19 and the consequent calibrated leakage of the air volume into upper chamber 19, the axial sliding of ejector member 16 is advantageously dampened. Advantageously, cap 50 is ejected (Fig. 5) from gripping assembly 10 in such a manner that, thanks to the dampening function, ejector member 16 is prevented from undergoing an impulsive movement. In the absence of the aforesaid dampening function, such an impulsive movement would take place when the magnetic repulsion force between the first and second magnetic elements 20, 23 exceeds the magnetic attraction force between magnetisable element 25 and the first magnetic element 20. By preventing the impulsive movement, frictions and excessive wear of ejector member 16 and hollow body 11 are advantageously reduced.

In accordance with the second embodiment, as a result of the axial sliding of ejector member 116 from the second equilibrium position towards the first, besides the expansion of upper chamber 19 (inside which the pressure decreases), also a compression of side chamber 129 (inside which the pressure increases) occurs; consequently a calibrated leakage of an air volume from side chamber 129 to upper chamber 19 is obtained (Figs. 8, 9).

As a result of the expansion of upper chamber 19 and the compression of the side chamber and of the consequent calibrated leakage of the air volume towards upper chamber 19, the axial sliding of ejector member 116 is advantageously dampened.

Advantageously, as described above with reference to the first embodiment, cap 50 is ejected (Fig. 9) from gripping assembly 110 in such a manner that, thanks to the dampening function, ejector member 116 is prevented from undergoing an impulsive movement. By preventing such an impulsive movement, frictions and excessive wear of ejector member 116 and hollow body 111 are advantageously reduced.

The features of the capping head for the application of caps on containers or bottles according to the present invention are clearly apparent from the above description, as are clearly apparent the relevant advantages.

Lastly, it is clear that a capping head for the application of caps on containers or bottles as conceived can undergo several changes and modifications, all included in the invention. Moreover, all details can be replaced by technically equivalent elements. In practice, any material as well as any size can be used, depending on the technical requirements.