TECHNICAL FIELD

The present invention relates to the field of container processing, with particular reference to the bottling industry.

In particular, the present invention relates to a unit for sterilising closures to be applied on relative containers .

BACKGROUND ART

As it is generally known, the need exists in the food industry to sterilise containers, both internally and externally, prior to filling them with food products, such as e.g. beverages.

Commonly, for sterilisation use is made of chemical agents, like hydrogen peroxide or peracetic acid, which are compatible with virtually any type of material, including paper, cardboard, metals and plastics.

With a view to ensuring that filling operations are performed under aseptic conditions, not only must containers be sterilised, but also their closures, such as caps or stoppers, which are used for sealing containers once the filling operation is finished, need to undergo a similar treatment.

Typically, sterilisation of closures, be they caps or stoppers, is obtained by means of ionising radiation or of chemical agents. Ionising radiation consists of particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, thus ionising them. Direct ionisation induced by single particles or single photons produces free radicals, i.e. atoms or molecules containing unpaired electrons, that tend to be especially chemically reactive due to their electronic structure. On the other hand, interaction between a particle or photon and an atom or molecule also frees one or more electrons, which are, in turn, capable of generating additional ions.

In particular, for sterilisation purposes, electron beam emitters are commonly used in the art. In practice, electron beams are directed on the object to be sterilised in such a manner that electrons can act directly on pathogenic agents, such as viruses, funguses or bacteria, in order to damage the DNA thereof and deactivate the proteins and enzymes necessary to their survival.

Sterilisation by means of ionising sources has the important advantage of reducing operating costs of filling/bottling plants, since consumption of chemical agents, water and sterilising substances is greatly reduced if not eliminated altogether.

Furthermore, the use of sources of ionising radiation as the sterilising agent positively affects environmental issues such as chemical residue disposal.

With particular reference to the sterilization of caps and stoppers, apparatus equipped with a magazine for containing caps and stoppers, connected to a chute for feeding the latter to a sterilisation zone, where they are submitted to ionising radiation of the type described above, are generally known within the bottling industry.

Apparatus of this type have a major drawback in that they do not guarantee complete, reliable sterilisation. In fact, shadow zones tend typically to form where the surfaces of two adjacent closures arranged in single file on the feed chute contact each other. In these shadow zones, ionising radiations fail to fully perform their function. Consequently, pathogenic agents present in those shadow zones are very likely to not be eliminated, the overall sterility of the closures, be they caps or stoppers, being thus greatly compromised.

W02009 / 139013 discloses a sterilising unit associated with a device for feeding container closures, the device comprising guides for conveying the closures to a treatment station and a star wheel with a plurality of projections and recesses suitable for receiving the closures, operatively associated with the guides, and adapted to deliver the closures to the treatment station at evenly spaced time intervals.

The star wheel can move alternatively between a position for blocking the queue of closures approaching the sterilising station and a position enabling the forward movement thereof towards the sterilising station.

For this arrangement to operate correctly, it is however essential that the star wheel rotate to impart to each closure an initial velocity, the closure subsequently being accelerated due to the combined effect of gravity and the inclination of the guides.

Accordingly, the inclination of the guides needs to be at least great enough to offset friction. On the other hand, inclination cannot be as great as to cause the closures to reach a speed such that they are exposed to the sterilising means for too short. These design limitations therefore must always be taken into account.

Furthermore, the star wheel needs to be actuated in such a manner that a sufficient initial velocity is imparted to each and every closure. Besides, for ensuring that adjacent closures are properly evenly spaced, actuation of the star wheels needs to be carefully timed and controlled. A solution such as the one known from W02009 / 139013 has therefore the drawback of certain inherent design constraints, and it is only by precisely controlling how the star wheel is actuated, both in terms of the frequency with which it is alternately rotated and stopped, as well as of the speed imparted by the star wheel on every single closure.

As a consequence of these design constraints, it may become complicated to adapt a sterilising unit of this type to closures of a different size or with different characteristics (e.g. material and, consequently, friction coefficient with respect to the guide surfaces; a different minimum exposure time to the sterilising agent, and so forth) . Furthermore, difficulties could arise if the plant productivity had to be increased, in that the settings determining the star wheel actuation cycles would have to be carefully revised. In other words, a sterilisation unit of this type may not be fully satisfactory in terms of ad ustability and adaptability.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a sterilising unit which makes it possible to overcome the above drawbacks in straightforward and inexpensive fashion.

This object is achieved by a container closure sterilising unit as claimed in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described in the following by way of example and with reference to the accompanying drawings, in which:

Figure 1 shows a schematic perspective exploded view of a sterilising unit in accordance with the teachings of the present invention;

Figure 2 shows a larger-scale schematic plan view of a detail of the sterilising unit of Figure 1 ;

Figure 3 shows a larger-scale perspective view of a detail of the sterilising unit of Figures 1 and 2 ;

Figure 4 shows a side view of an alternative embodiment of a sterilising unit according to the invention; and Figure 5 shows a larger-scale front view of a detail of the embodiment of Figure 4.

BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole a container closure sterilising unit, in particular for caps and stoppers to be applied to relative containers, such as bottles .

Sterilising unit 1 comprises at least one closure treatment station 2 and a device 3 for feeding a plurality of container closures 100 (see Figures 2 and 3) to closure treatment station 2.

As illustrated in greater detail in Figure 2, feeding device 3 comprises guiding means 4 defining: an entrance 5 for closures 100, which entrance 5 communicates with loading means or a closure storage unit (not shown) from which closures 100 to be sterilised are supplied; a conveying path P comprising at least one linear tract PI (i.e. one tract having constant inclination relative to the vertical direction) and along which the at least one treatment station 2 is arranged; and an exit 6 for closures, which exit 6 communicates with a further unit (not shown) arranged downstream from sterilising unit 1.

Advantageously, feeding device 3 comprises (see Figure 2) conveying means 7 operatively active on a single file of closures 100 to advance them towards treatment station 2 evenly spaced from one another along conveying path P. In particular, conveying means 7 are operatively associated with guiding means 4.

Preferably, conveying means 7 comprise a helical coil 8 (see also Figure 3) which is operatively active on a queue of closures 100 to cause said closures to advance along conveying path P and to be fed to the at least one treatment station 2 evenly spaced from one another along conveying path P.

In particular, a longitudinal axis H of helical coil 8 extends parallel to tract PI of conveying path P.

In the embodiment of Figure 3, helical coil 8 is born by a shaft 9 substantially coaxial with coil 8 and driven by motor means 10. More particularly, helical coil 8 is preferably fixed to shaft 9 by a plurality of support elements 11 extending radially from shaft 9 and arranged evenly spaced along the latter. In turn, shaft 9 is rotatably mounted at shaft end mount portions.

By virtue of operative association of conveying means 7 and guiding means 4, rotation of helical coil 8 about its axis results in the forward movement of all closures on which helical coil 8 is operatively active.

In particular, it shall appear that constant speed rotation of helical coil 8 results in the uniform forward movement of the closures 100 upon which helical coil 8 is operatively active at a constant linear speed along tract PI of conveying path P. In other words, upon cooperation with helical coil 8, closures 100 are all advanced at the same speed along tract PI . Although conveying means 7 are preferably driven by a brushless-type electric motor, the use of driving means of a mechanical type, e.g. by means of gears, represents a viable alternative.

With particular reference to Figure 2, guiding means 4 preferably comprise a plurality of guides 12. Guides 12 may, at least for a portion thereof, be inclined relative to the horizontal direction, so as to permit closures 100 to slide by gravity.

Preferably, as in the embodiment shown in Figure 2, guides 12 comprise, in succession relative to an advancing direction of closures 100 along path P, an input section 13, a main section 14 and an output section 15, each section being more inclined relative to the horizontal direction than the previous one (relative to said advancing direction of the closures) . However, as shall become clear in the following, alternative arrangements and inclinations are also made viable by the present invention.

A container closure 100 such as a cap or stopper typically has a substantially cylindrical shape extending along a respective axis B. Accordingly, every container closure shall have a top surface 101 substantially orthogonal to axis B and a lateral (cylindrical) edge surface 102 substantially parallel to axis B.

Guides 12 comprise, in particular (see Figure 2) : one or more first guides 12' extending, at least along tract PI of conveying path P, parallel to shaft 9 and operatively active on the lateral edge surface 102 of closures 100; and one or more second guides 12'' cooperating with the top surface 101 of closures 100.

In practice, the lateral edge surface 101 of closures 100 rest on the one or more first guides 12' which substantially define, with shaft 9, a rail along which closures 100 may be advanced.

On the other hand, closures 100 are substantially guided between pairs of second guides 12'' arranged on opposite sides of closures 100 (i.e. facing top and bottom sides of closures 100, respectively) or between one or more second guides 12'', on one side, and an opposite supporting wall, as will become apparent in the following.

Where guides 12' are inclined relative to a vertical direction, closures 100 may therefore roll by gravity along the sections of guides 12' where there is no cooperation of closures 100 with helical coil 8.

Sterilising unit 1 further comprises an outer casing 16 adapted to house guiding means 4 and conveying means 7. In the example illustrated, casing 16 comprises a shell portion 17 and a cover portion 18, the shell portion being adapted to materially house guides 12, helical coil 8 and shaft 9, and motor means 10.

With particular reference to Figure 1, outer casing 16 comprises an input channel 19, a central body 20, and an output channel 21, conveying means 7 and a section of the guiding means 4 being housed within central body 20. Central body 20 has at least a first service window 22 positioned in the location of the closure treatment (i.e. sterilisation) station 2 to enable treatment of the closures 100 travelling along path P as defined by the section of guiding means 4 housed within central body 20.

Preferably, central body 20 further comprises a second service window 23 positioned opposite first service window 22, so that closures 100 conveyed along path P by helical coil 8 can be conveniently treated from both sides.

Input channel 19 typically communicates with the loading means or closure storage unit (not illustrated) for storing and feeding the closures to be treated.

In the embodiment illustrated in Figure 1, sterilisation unit 1 comprises one or more sources 24,24' of ionising radiation, for example emitters of electron beams or gamma or beta rays, each arranged at a relative service window 22,23, positioned opposite each other, the conveying path P along which closures are advanced extending between them. In such a case, as illustrated in Figure 1, guiding means and conveying means are interposed between said pair of emitters 24, 24', which irradiate closures 100 through the respective windows 22,23 (only one of which is visible in the drawings) of central body 20 of outer casing 16. Accordingly, closures 100 may advantageously be treated on both their top and bottom sides .

In a preferred embodiment, helical coil 8 is hollow (see the detail of Figure 3) and can advantageously be flown through by a flow of a thermal carrier (e.g. cooling) fluid, like water. To this purpose, a suitable inlet and outlet for the cooling fluid may advantageously be provided at the ends of helical coil 8, e.g. at the shaft end mount portions .

It should be noted that, in use, an electron beam emitter, like other sources of ionising radiations typically employed for sterilisation purposes, releases heat (e.g. thermal powers of about 500 W are common in the field) . Accordingly, ablation of the heat released at the at least one treatment station 2 is desirable, both with a view to preventing any superheating of sterilisation unit 1 as a whole and - even more importantly so - to maintaining the temperature of helical coil 8 within a predetermined range, so that thermal expansion does not alter its geometry. As a matter of fact, thermal deformation of helical coil 8 might result in operational anomalies, what with alterations of the pitch between adjacent convolutions of the coil making cooperation with closures 100 imprecise, not properly functional or even altogether impossible.

Number 1.1 in Figure 4 indicates as a whole an alternative embodiment of a sterilising unit in accordance with the present invention.

Sterilising unit 1.1 is similar to sterilising unit 1 and is described below only insofar as it differs from the latter, and using, wherever possible, the same reference numbers for identical or corresponding parts of sterilising units 1 and 1.1.

More specifically, sterilising unit 1.1 differs from sterilising unit 1 in that it comprises (see also the detail in Figure 5) a plurality of strengthening guide elements 31.1 extending parallel to axis H and substantially tangential to the convolutions of helical coil 8. Preferably, strengthening guide elements 31.1 are equally spaced about axis H. For example, in the embodiment of Figure 4, three strengthening guide elements 31.1 are provided at 120° off one another.

In the embodiment shown, strengthening guide elements 31.1 extend along only part of helical coil 8, however they might run parallel to helical coil 8 along the whole of its length.

Preferably, sterilising unit 1.1 further comprises a rotating shielding portion 32.1 kinematically coupled with helical coil 8 and extending coaxially to helical coil 8 at one end thereof.

Helical coil 8 and the convolutions thereof shall be designed and arranged, relative to guides 12 so that strengthening guide elements 31.1 do not hinder proper interaction between the convolutions of helical coil 8 and closures 100.

Strengthening guide elements 31.1 help preventing helical coil 8 from deflecting or undergoing deformations due to thermal expansion, thereby preserving optimal functionality of helical coil 8 itself.

It shall appear that this positive effect resulting from the provision of strengthening guide elements 31.1 can be coupled with that obtainable by having a cooling fluid flowing within a hollow helical coil 8 as described above.

Operation of sterilising unit 1 (1.1) will now be briefly described.

Closures 100 picked up from the loading means or a closure storage unit slide along the section of the guides 12 arranged within input channel 19, forming a single file along path P (see in particular Figure 1) .

Helical coil 8 is rotated by motor means 10 about shaft 9, the convolutions of helical coil 8 and guides 12 cooperating with closures 100 to produce a forward movement of closures 100 along tract PI of conveying path P.

Helical coil 8 thereby imparts a uniform velocity along tract PI to all closures 100 reaching tract PI and conveys them across the at least one service window 22, where closures 100 are conveniently exposed to the action of source 24 of sterilising means (electron beam emitter or the like) . By virtue of the geometry of helical coil 8, closures 100 are maintained evenly spaced from one another as they advance along tract PI of conveying path P. In fact, the convolutions of helical coil 8 contact closures 100 substantially at a single point on their periphery. Therefore, friction and the possible consequent local formation of powder or dust are advantageously greatly reduced. Furthermore, since closures 100 are separated from one another by a respective convolution of helical coil 8 and loosely cooperate with adjacent convolutions of helical coil 8 and with guides 12, a rolling movement of closures 100 (i.e. rotation about their axis B) is induced, as they advance towards output channel 21. As a consequence of said rolling movement, the formation of shadow zones may very advantageously be prevented.

The speed at which closures 100 advance along tract PI of conveying path P is conveniently and uniformly controlled by controlling solely the rotation speed of shaft 9, independent of inclination of guides 12 and of the characteristics of the closure material (e.g. friction coefficient, density and so on) .

A cooling fluid, such as water, may be directed to flow within helical coil 8 for removing any excess heat generating by the sources 24 of ionising means.

The advantages of sterilising unit 1 according to the present invention will be clear from the above description.

In particular, sterilising unit 1 according to the invention prevents the formation of shadow zones between closures 100, whereby a complete and safe sterilisation treatment of the closures is made possible. Furthermore, by controlling solely the speed of rotation of conveying means 7 (helical coil 8) it is possible to have the closures advance along path P evenly spaced by a predetermined pitch and at a uniform given speed. Accordingly, all closures may uniformly be exposed to the source 24 of sterilisation means for the same treatment time and under substantially equivalent treatment conditions. In particular, the duration of the treatment may be conveniently adjusted in use. Furthermore, since the speed at which closures 100 are advanced along tract PI of conveying path P, i.e. along the section of path P materially relevant to the sterilisation process, is controlled univocally by conveying means 7, independently of the inclination of guides 12 relative to the vertical direction, a great number of design alternatives become available, making it possible for the designer to adapt the sterilisation unit to different geometries and space constraints. As a matter of fact, tract PI might even be arranged horizontally or vertically.

Advantageously, the sterilisation unit of the invention makes it possible to adjust the speed at which closures are advanced along path P on the basis of plant productivity requirements, e.g. as a function of the number of bottles capped per hour.

Furthermore, the sterilising unit of the invention can operate with closures of different materials without requiring that parameters such as the speed of rotation of helical coil 8 be adjusted from time to time, since properties such as the friction coefficient between closures 100 and guides 12 has no influence on the time of exposure to the sources 24 of sterilisation means. Besides, replacement of helical coil 8 with a modified coil adapted to cooperate with smaller/larger closures would be enough to make sterilisation unit 1 functionally operable with closures 100 of a different size.

Clearly, changes may be made to sterilising unit 1 as described and illustrated herein without, however, departing from the scope of protection as defined in the accompanying claims.