DE102013101371A1 - Device for sterilizing containers and plastic performs, has shielding unit that is provided to shield acceleration device and/or carrier conduction device sections against magnetic fields - Google Patents

Abstract

The device (1) has a charge carrier generation unit (2) which generates charge carriers. An acceleration device (4) accelerates the carriers in a predetermined direction of acceleration (B). A rod-shaped carrier conduit device (6) is provided with an exit window (8) through which the carrier is escaped from the carrier conduit device. A shielding unit (20) is provided to shield the acceleration device and/or carrier conduction device sections against the magnetic fields. An independent claim is included for a method for sterilizing plastic containers.

Description

The present invention relates to an apparatus and a method for sterilizing containers. Such devices and methods have been known for a long time from the prior art. Recently, it has also begun to perform a sterilization of containers and in particular their inner surfaces by the use of electrons or charge carriers. In this case, charge carriers are usually generated and directed to the surfaces of the containers to be sterilized. The invention will be described below with reference to plastic preforms, which are formed into containers. Accordingly, however, the invention could also be applied to the sterilization of containers and in particular of plastic containers.

Such devices for sterilizing containers by means of electron beams usually have generating means for generating electrons and accelerating means for accelerating the electrons. In other words, such electron beam emitters are usually constructed so that after accelerating the electrons in the vacuum of a tube they are passed without additional magnetic guidance or stabilization within a subsequent to the accelerator tube, such as steel pipe and usually through an exit window in the environment. This exit window is e.g. around a titanium tube limiting the mentioned pipe.

In operation, however, it has been shown that these radiation emitters are very sensitive to their environment. In particular, it has been found that disturbances are generated by motors arranged in the vicinity of the electron emitter, such as, in particular, electric motors. Thus, for example, a change of a focal spot and thus the electron conduction inside the tube has been adjusted by a servo-drive mounted in the vicinity.

Therefore, it was feared that in a movable radiation emitter, as is the case with the Applicant's devices, these influences are even greater, since the radiation emitters are also subject to changing magnetic fields or magnetic fields with changing orientation due to their own movement.

The present invention is therefore based on the object to achieve a more stable operation of such electron beam emitter and thus also such sterilization facilities. These objects are achieved according to the invention by the subject matters of the independent claims.

Advantageous embodiments and further developments are the subject of the dependent claims.

An inventive device for sterilizing containers and in particular of plastic preforms has a charge carrier generating device which generates charge carriers. Furthermore, the device has an acceleration device, which accelerates the charge carriers in a predetermined acceleration direction, and a rod-shaped charge carrier line device which has an exit window, via which the charge carriers can emerge from the charge carrier line device.

According to the invention, the device has a shielding device which shields the acceleration device and / or the charge carrier line device at least in sections from magnetic fields.

The Applicant was able to find out that the fluctuations or the deviations of the electron beams are due in particular to the influence of electromagnetic and in particular magnetic fields. Even an influence of the earth's magnetic field or static magnetic fields, which are generated for example by magnetic components, possibly have an effect on the guidance of the charge carriers, which are in particular electrons. For example, in the context of experiments, a change in a focal spot could be detected by a change in an attachment or a rotation of the radiator by 90 ° about its own longitudinal axis. This led to the assumption that the influence from the outside on the radiation emitter increases even more when the radiation emitter is moving, for example rotating on a circular path, or when a large number of emitters is arranged next to one another. Such changes in the radiation device or the emitter are to be classified as critical, as can be set by a changing or unequal charge carrier or electron guide and a non-uniform electron cloud under the radiator or emitter. In this way, any portions of a plastic container to be sterilized, such as a plastic preform or a plastic bottle, can only be subjected to insufficient radiation and thereby not completely sterilized.

The invention therefore proposes to arrange magnetic field shielding means in the area of sterilization in the vicinity of the plastic preforms or plastic containers and / or if necessary even einhausen the containers or packaging.

Advantageously, the charge carrier conduction means, i. Specifically, the above-mentioned rod-shaped body is arranged immediately after the accelerator. The exit window is in particular a titanium window and preferably has a thickness which is between 3 μm and 30 μm, preferably between 6 μm and 20 μm, particularly preferably between 6 μm and 15 μm.

Furthermore, the device also has a cooling device which cools the said exit window. This is advantageously an externally guided air cooling, which acts on the outlet window and / or its holder with air for the cooling thereof. Alternatively or additionally, other cooling methods of the film, such as a liquid cooling are applicable.

The charge carriers are in particular electrons. However, it would also be conceivable to use, for example protons or alpha particles instead of electrons.

Advantageously, the charge carrier line device is subjected to a vacuum and in particular to a high vacuum, within which the charge carriers move. The above-mentioned exit window delimits this vacuum.

In an advantageous embodiment, the shielding device surrounds the acceleration device and / or the charge carrier line device with respect to the acceleration device at least temporarily and / or at least in sections.

In particular, it has been found that the portion in which the electrons are accelerated is particularly sensitive to magnetic fields. Therefore, it is proposed here to shield a section of the accelerator device from magnetic fields. In a further advantageous embodiment, the shielding device completely surrounds the acceleration device at least temporarily in a circumferential direction with respect to the acceleration device. Thus, it would be possible, for example, for the shielding device to be stationary and to temporarily retract the acceleration device into this shielding device. Conversely, the shielding device can be slipped over the acceleration device and / or the charge carrier line device, so to speak at times.

In a further advantageous embodiment, the shielding device is arranged at least partially stationary relative to the acceleration device and / or the charge carrier line device. For example, the shielding device can be arranged directly on the acceleration device and surround it, for example, in the circumferential direction thereof. The shielding device is advantageously arranged completely stationary relative to the accelerating device and surrounds it completely in the direction of acceleration.

In a further advantageous embodiment of the rod-shaped body via an opening of the container in this container can be inserted. This advantageously serves the means for sterilizing the inner surfaces of the containers and in particular the plastic preforms.

In a further advantageous embodiment, the shielding device has a foil-like body which at least partially and preferably completely surrounds the accelerating device. Thus, a shield against magnetic fields can be achieved in a particularly simple manner.

In a further advantageous embodiment, the shielding device has a μ-metal. For shielding electromagnetic fields or for shielding the electron beams suitable means are especially these said μ-metals, that is, advantageously, the shielding element on nickel and preferably, the shielding element on iron. Nickel-iron alloys and in particular soft magnetic nickel-iron alloys are advantageously used for the shielding element. These shielding elements can be placed in the form of dividers between the divisions. However, it would also be conceivable that the shielding elements are also attached in the form of a half-shell with or without bottom to a container handling system.

Advantageously, this μ metal has a permeability of between 50,000 and 140,000. In this way it is achieved that the flow of magnetic fields and in particular of low frequency magnetic fields in the material is concentrated.

In the context of production, it is advantageous if this shielding material is first brought into its final shape and then heated again, in particular to temperatures in a range of 1000 ° C-1200 ° C. Furthermore, the film-like material can be arranged on a carrier, which in turn can be attached over the acceleration device or around it.

Advantageously, shell sections, for example half shells, are provided which For example, in the vicinity of the beam emitter or the rod-shaped body are preferably fixedly mounted. By a relative movement between the container treatment system and the radiation device, a partial or almost complete shielding of the plastic preform would be possible in this way. It is also conceivable that said half-shells are designed such that they overlap at least slightly at the joints and thus improve the shielding effect. In addition, these shells can also serve as protection of the beam finger.

For acceleration of the charge carriers or electrons, voltages between 50 and 150 kV are preferably used. Preferably, a classical cathode Wehnelt anode arrangement is used. The electrons fly after their acceleration through an elongated tube, at the end of which, as mentioned above, the exit window or the titanium window is located. The electrons come out of the vacuum here and are strongly scattered in the air. In this way, they form a cloud of ionizing particle radiation and sterilizing effect.

As mentioned above, the electrons on the acceleration path between the cathode and the anode and also the subsequent beam fingers are deflected by the external magnetic fields, which in particular also run perpendicular to the beam direction, and in extreme cases can no longer hit the titanium window centered. In this way, the electron cloud can be laterally shifted and distorted (or even deflected so much that it no longer hits the exit window) and a uniform or axially symmetric irradiation of the inner surface of containers such as bottles and plastic preforms is no longer guaranteed.

However, it could be determined that the mentioned deflection effect is stronger when the electrons are slower, for example at the beginning of the acceleration section. Thus, in the vicinity of the radiator also far stronger magnetic fields than those of the earth's field were measured. During the movement of the jet device by the magnetic fields very significant effects are measured, for example in the context of current measurements. The measured current on a lateral measuring plate depends very much on the orientation of the radiation source or the emitter, or on the angular position of the carousel, although nothing has changed in the parameters of the radiation emitter. This is due to different magnetic field directions and magnetic field strengths that the electron beam experiences on its carousel track. For the irradiation of surfaces in hollow bodies, this means that they are no longer treated evenly during a circulation in the carousel.

In a further advantageous embodiment, the shielding device is arranged outside a housing of the acceleration device. It should be noted that, as mentioned above, very strong acceleration voltages are used. It is important to ensure that the structure in the interior of the accelerator is designed to be as simple as possible in order to prevent flashovers. In addition, it would still be possible for a protective layer, for example a protective plastic layer, to be arranged on the shielding device, in particular if it is designed as a foil. The shielding device offers the advantage of being a passive shielding device. Active compensations of the beam deflections are known in some cases from the prior art. However, this is particularly difficult because, in the case of the invention, the jet devices or the radiators themselves move and thus the direction of the magnetic field with respect to the orientation of the jet device constantly changes.

However, it would also be possible to provide additional active shielding devices, such as, for example, Helmholtz coils, which compensate the magnetic fields in the region of the radiation devices.

Advantageously, therefore, the shielding means is a passive shielding means, i. in particular, a shielding device through which current does not flow or is supplied with a current for the purpose of shielding.

The present invention is further directed to an apparatus for sterilizing plastic containers and in particular plastic preforms. This device has a movable support, to which at least one device of the type described above is arranged, and a movement device, which generates a relative movement between a charge carrier line device and a container to be sterilized. Advantageously, this relative movement is generated in a longitudinal direction of the container and thus the charge carrier line device or the beam finger is introduced into the container. However, it would be possible that the charge carrier line device or the entire device is moved, but advantageously the container is also moved in its longitudinal direction.

The present invention is further directed to a method for sterilizing plastic containers, wherein the plastic containers are transported along a predetermined transport path and sterilized during this transport by application of accelerated charge carriers. At the transport track it acts preferably around a circular transport path. Preferably, the containers move relative to the Ladsträgerleiteinrichtungen such that in particular the inner surfaces of the containers can be sterilized or charged with electrons.

According to the invention, the charge carriers are shielded from magnetic fields by means of a shielding device. Preferably, the charge carriers are at least temporarily shielded during their acceleration by means of the shielding device with respect to the magnetic fields.

Advantageously, a rod-shaped body is introduced via an opening of the containers in this. In this case, the containers are advantageously moved relative to the acceleration device, in particular in a longitudinal direction of the containers. Advantageously, inner walls of the containers are charged with the charge carriers. Advantageously, the containers are plastic preforms.

Further advantages and embodiments will become apparent from the accompanying drawings. Show:

1 a representation of a device according to the prior art for illustrating the object underlying the invention;

2 a further illustration of a device according to the prior art;

3 a representation of a device according to the invention in a first embodiment;

4 another illustration of in 1 shown device;

5 a representation of the device 1 in another operating condition;

6 a representation of the device 2 in another operating condition;

7 a plan view of the device 1 ;

8th a schematic representation of the operation of the device according to the invention;

9 a representation of a device according to the invention in a further embodiment.

1 shows a device according to the prior art to illustrate the problem underlying the invention. One recognizes here again the charge carrier generation device 2 and the accelerator 4 (only shown schematically). The charge carrier line device 6 is in the interior of a container 10 introduced and gives a charge carrier cloud W from. Due to the magnetic field represented by the four crosses, however, a deflection of the electrons is effected precisely in the region of the acceleration device but also in the region of the charge carrier line device so that they no longer impinge concentrically on the exit window at the lower end of the charge carrier line device. In this way, there is a shift of the electron cloud and thus it may happen that no longer the entire inner wall 10b the containers are sterilized evenly.

At the in 2 As shown, the magnetic field is reversed and insofar as the charge carrier cloud W is displaced in the other direction, so that areas of the plastic container are now insufficiently sterilized on the left side. Perhaps the effects do not occur as much as shown in the schematic figure, but in any case so strong that proper sterilization can no longer be guaranteed.

3 shows a side view of a device according to the invention. This device has one in its entirety 30 designated movable carrier. This carrier can be designed as a wheel to which a variety of sterilization devices 1 is arranged. The reference number 50 indicates a clean room in the area where the plastic containers, here the plastic preforms 10 , being transported, being trained. This can be this clean room 50 also through walls 30a and 30b of the carrier 30 be limited.

Furthermore, the device 1 have additional walls, which the clean room 50 limit. Preferably, these other walls, which are located in the 1 would connect left, not movable but arranged stationary. In addition, a sealing device may be provided, which the walls 30a and 30b that deals with the devices 1 move, seal against the stationary walls (not shown). Thus, for example, a so-called water lock could be provided, which is designed as a circumferential channel and in which a, for example, movable sword of each movable wall dips.

The clean room 50 is thus advantageous in the direction of movement of the plastic preforms in terms of its geometric structure 10 formed like a channel or torus.

The device 1 For sterilization in this case has a generating means only schematically shown, which generates charge carriers and in particular electrons. Furthermore, an acceleration device 4 provided, which is also shown only schematically and which accelerates the charge carriers, in particular electrons, in the direction B. This accelerator device is followed by a charge carrier line device 6 which is embodied here as a rod-like body, in the interior of the plastic preforms 10 is insertable. At the lower end of this charge carrier line device is an exit window 8th provided over which the charge carriers can escape.

Inside the charge carrier generating device, a vacuum is formed. For sterilization of the plastic preforms this charge carrier line device 6 or the beam finger in the interior of the plastic preforms 10 introduced and there the electrons exit. For this purpose, the plastic preform 10 by means of a movement device 40 Lifting in its longitudinal direction L, which here coincides with the direction of acceleration B, are raised, so as to the charge carrier line means 6 in the plastic preform 10 introduce. In principle, it would also be conceivable that the charge carrier generating device is guided in the direction of the container.

The reference number 44 indicates a sealing device which seals this movement of the plastic preform, in this way the clean room 50 not to endanger. A corresponding drive 46 (shown only schematically) is preferably arranged outside of the clean room. Thus, for example, outside the clean room guide curves may be provided which the movement of the plastic preform 10 cause.

The reference number 20 schematically indicates a shielding device, which here the charge carrier line device 6 shields with respect to magnetic fields. Here, the shielding device has a first shielding element 22 which is stationary with respect to the charge carrier line device 6 is arranged and a second shielding 24 , which here with the plastic preform 10 is designed to be movable.

These two shielding elements can be designed here as curved shielding elements, which the plastic preform 10 surrounded in its circumferential direction.

The reference number 42 indicates a holding element which holds the plastic preform and thus transported. This can advantageously be a gripper clip which transports the plastic preform directly below its support ring. At this holding device is also the second shielding 24 arranged so that it moves together with the plastic preform in the direction of movement L. In this case, furthermore, the shielding device 24 also a floor element 24a on, which shields below the plastic preform.

4 shows a perspective view of in 1 shown device without the carrier 30 , It can be seen here that the two shielding elements 22 and 24 in each case semicircular the charge carrier line element 6 surrounded and so together a complete shielding of the charge carrier line element 6 form. Furthermore, it can be seen that the holding device 42 a gripping element 42a having, which the plastic preforms 10 below her support ring 10a attacks.

5 shows the device according to 1 but in a state where the charge carrier conduction means enters the plastic preform 10 has largely retracted. It can be seen here that the two shielding elements 22 and 24 already partially overlapping. The sealing element or the bellows 44 is stretched here extensively.

6 shows a perspective view of in 3 shown situation. Again, it can be seen that now the charge carrier line device almost completely in its longitudinal direction of the two shielding elements 22 and 24 and down to the bottom section 24a is surrounded.

7 shows a plan view of the device according to the invention. You can see here again the holding device 42 with the gripping element 42a , which the plastic preforms below the support ring 10a holds. Below the gripping element is also (here only partially shown), the second shielding 24 recognizable. The reference number 28 indicates a suspension device which the gripping clamp 42a delivered to the plastic preform and this holds it.

8th shows a schematic representation of the device according to the invention. It can be seen that here the two shielding elements 22 and 24 the charge carrier line device 6 completely surrounded in the circumferential direction.

9 shows a schematic representation of the device according to the invention. Here is an area of the accelerator 4 , wherein in a region of this accelerator 4 a shielding element 20 is provided. This shielding element is designed here as a film, which at least partially and at least temporarily around the acceleration device 4 is wrapped around. In this case, this film advantageously has a thickness which is between 0.05 and 3 mm, preferably between 0.09 and 1.5. In this way, in the very sensitive area in which the charge carriers are accelerated, a substantially complete shielding of the magnetic field M is achieved. In this way, the electrons are no longer undesirably deflected in the acceleration region and the carrier cloud W thus emerges centrally from the exit window and in this way can, as in FIG 9 shown all areas of the container 10 be charged with charge carriers for their sterilization.

It would also be possible to combine the embodiments shown in the individual figures, ie both the charge carrier line device 6 shield as well as the accelerator 4 , In addition, even in the field of generating the charge carriers, the magnetic fields can be shielded accordingly.

It would also be conceivable to use the charge carrier line device 6 to wrap with a corresponding shielding foil.

The Applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are novel individually or in combination with respect to the prior art.

LIST OF REFERENCE NUMBERS

B

acceleration direction

L

Longitudinal direction L

W

Carrier cloud W

1

sterilization devices

2

Charge carrier generation means

4

accelerator

6

Carrier conduit means

8th

exit window

10

The plastic preforms

10a

support ring

10b

inner wall

20

shielding

22

shielding

24

shielding

24a

Floor element / bottom portion

28

suspension device

30

movable carrier

30a

wall

30b

wall

40

mover

42

retaining element

42a

gripping clamp

44

Sealing device / bellows

46

drive

50

cleanroom

Claims (11)

Facility ( 1 ) for sterilizing containers and in particular plastic preforms ( 10 ) with a charge carrier generating device ( 2 ), which generates charge carriers, with an acceleration device ( 4 ) which accelerates the charge carriers in a predetermined direction of acceleration (B) and with a bar-shaped charge carrier line device ( 6 ), which has an exit window ( 8th ), via which the charge carriers from the charge carrier line device ( 6 ), characterized in that the device ( 1 ) a shielding device ( 20 ), which the acceleration device ( 4 ) and / or the charge carrier line device at least partially shields against magnetic fields. Facility ( 1 ) according to claim 1, characterized in that the shielding device ( 20 ) the acceleration device ( 4 ) with respect to the acceleration direction (B) at least temporarily and at least partially surrounds. Facility ( 1 ) according to claim 2, characterized in that the shielding device ( 20 ) the acceleration device ( 4 ) at least temporarily completely surrounds with respect to the direction of acceleration (B). Facility ( 1 ) according to at least one of the preceding claims, characterized in that the shielding device is at least partially stationary relative to the acceleration device ( 4 ) is arranged. Facility ( 1 ) according to at least one of the preceding claims, characterized in that the charge carrier line device ( 6 ) over a mouth of the container ( 10 ) is insertable into this container. Facility ( 1 ) according to at least one of the preceding claims, characterized in that the shielding device ( 20 ) has a foil-like body which supports the bar-shaped charge carrier conduction device ( 6 ) and / or the acceleration device ( 4 ) at least partially and preferably completely surrounds. Facility ( 1 ) according to at least one of the preceding claims, characterized in that the shielding means comprises a μ-metal. Facility ( 1 ) according to at least one of the preceding claims, characterized in that the shielding device comprises a first shielding element ( 22 ) and with respect to this first shielding element ( 22 ) movable second shielding element ( 24 ) having. Contraption ( 1 ) for sterilizing plastic containers ( 10 ) and in particular of plastic preforms ( 10 ) with a movable support ( 30 ) on which at least one device according to at least one of the preceding claims is arranged, and with a movement device ( 40 ), which a relative movement between a charge carrier line device ( 6 ) and a container to be sterilized ( 10 ) generated. Method for sterilizing plastic containers ( 10 ), the plastic containers ( 10 ) are transported along a predetermined transport path and sterilized during this transport by exposure to accelerated charge carriers, characterized in that these charge carriers to magnetic fields by means of a shielding device ( 20 ) are shielded. A method according to claim 10, characterized in that the charge carriers are at least partially shielded during their acceleration at least partially against the magnetic fields.

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